Podcasts about mcherry

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2023.07.26.550695v1?rss=1 Authors: Hood, E. M., Lipinski, R. A. J., Lipinski, D. M. Abstract: PURPOSE ARPE19 cells are a commonly used cell culture model for the study of retinal pigment epithelial cell biology and pathologies. However, numerous studies have demonstrated that ARPE19 undergo morphologic, transcriptomic and genomic alterations over time and with increasing passage number. Herein, we explore the mechanisms underlying increased resistance to the delivery of exogenous genetic material via transfection in ARPE19 cells using mass spectrometry. METHODS ARPE19 cells (N=5 wells/reagent) were seeded in 6-well plates at passages 24 through 30. At 70% confluency an mCherry reporter construct was delivered via transfection using Lipofectamine 3000, Lipofectamine LTX, Lipofectamine Stem, or PEI (polyethylenimine) reagents. After 72 hours, transfection efficiency was quantified by fluorescence microscopy and flow cytometry. Mass spectrometry and immunofluorescence of ARPE19 cells were performed at passages 24 and 30 to evaluate altered protein synthesis and localization between passage numbers. RESULTS ARPE19 transfection showed a maximum transfection efficiency of 32.4% at P26 using Lipofectamine 3000 reagent. All lipofectamine based reagents demonstrated statistically significant decreases in transfection efficiency between passages 24 and 30. Mass spectrometry analysis revealed 18 differentially expressed proteins, including down-regulation of clathrin light chain B (CLTB) and legumain (LGMN) that was confirmed via immunofluorescence imaging, which indicated altered intracellular localization. CONCLUSIONS ARPE19 cells demonstrate passage number dependent changes in lipofectamine-based transfection efficiency. Mass spectrometry and immunofluorescence indicates the observed decrease in transfection efficiency involves the dysregulation of endocytosis and intracellular endolysosomal trafficking at later passages. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2023.02.15.528709v1?rss=1 Authors: Lin, S.-S., Zhou, B., Chen, B.-J., Jiang, R., Li, B., Illes, P., Semyanov, A., Tang, Y., Verkhratsky, A. Abstract: Astrocyte atrophy is the main histopathological hallmark of the major depressive disorder (MDD) in humans and in animal models of depression. Here we show that electroacupuncture prevents astrocyte atrophy in the prefrontal cortex and alleviates depressive-like behaviour in mice subjected to the chronic unpredictable mild stress (CUMS). Treatment of mice with CUMS induced depressive-like phenotypes as confirmed by sucrose preference test, tail suspension test, and forced swim test. These behavioural changes were paralleled with morphological atrophy of astrocytes in the prefrontal cortex, revealed by analysis of 3D reconstructions of confocal Z-stack images of mCherry expressing astrocytes. This morphological atrophy was accompanied with a decrease in expression of cytoskeletal linker Ezrin, associated with formation of astrocytic leaflets, which form astroglial synaptic cradle. Electroacupuncture at the acupoint ST36 as well as treatment with anti-depressant fluoxetine prevented depressive-like behaviours, astrocytic atrophy and down-regulation of astrocytic ezrin. In conclusion, our data further strengthen the notion of a primary role of astrocytic atrophy in depression and reveal astrocytes as cellular target for electroacupuncture in treatment of depressive disorders. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2023.02.08.527629v1?rss=1 Authors: Ehring, K., Ehlers, S. F., Froese, J., Gude, F., Puschmann, J., Grobe, K. Abstract: The Sonic hedgehog (Shh) signaling pathway controls embryonic development and tissue homeostasis after birth. This requires regulated solubilization of dual-lipidated, firmly plasma membrane-associated Shh precursors from producing cells. Although it is firmly established that the resistance-nodulation-division transporter Dispatched (Disp) drives this process, it is less clear how lipidated Shh solubilization from the plasma membrane is achieved. We previously showed that Disp enhances proteolytic Shh solubilization from its lipidated terminal peptide anchors. This process, called shedding, converts tightly membrane-associated hydrophobic Shh precursors into delipidated soluble proteins. We show here that Disp-mediated Shh shedding is modulated by a serum factor that we identify as high-density lipoprotein (HDL). In addition to serving as soluble sinks for free membrane cholesterol, HDLs also accept the cholesterol-modified Shh peptide from Disp. The cholesteroylated Shh peptide is required and sufficient for Disp-mediated transfer because mCherry linked to cholesteroylated peptides associates with HDL in a Disp-dependent manner, but an N-palmitoylated Shh variant that lacks C-cholesterol does not. Disp-mediated Shh transfer to HDL is finalized by proteolytic processing of the palmitoylated N-terminal membrane anchor. The resulting mono-lipidated Shh variant may help meet the demands for Hh activity regulation in different cell types and developing tissues. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2022.11.16.516691v1?rss=1 Authors: Kim, J., Kratz, A., Sheng, J., Zhang, L., Singh, B. K., Chavez, A. Abstract: To facilitate the interrogation of proteins at scale, we have developed High-throughput Insertion of Tags Across the Genome (HITAG). HITAG enables users to produce libraries of cells, each with a different protein of interest C-terminally tagged, to rapidly characterize protein function. To demonstrate the utility of HITAG, we fused mCherry to a set of 167 stress granule-associated proteins and characterized the factors which drive proteins to strongly accumulate within stress granules. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

春の訪れ、Daylight saving time、ペッパーランチの思い出、マリトッツォって何、磁力を使って生きた細胞の中のクロマチンを動かす論文、種間で寿命のばらつきが非常に大きい(11-200歳)根魚のゲノム解析論文について話しました。Shownotes Daylight saving time … いわゆるサマータイム ソメイヨシノ … ソメイヨシノ研究といえば遺伝研の竹中要先生。 Daylight saving timeを一年中使うことの議論 ペッパーランチ 超高級食材でペッパーランチ作ったら美味すぎて言葉を失いました… (by ヒカキン) … 飯テロ許すまじ！ Pepper Lunch in Vancouver Yoshinoya Yayoi BOSSO … Harvard Buisiness Schoolを卒業した人が始めたラーメン屋さん。唐揚げが一番おいしかった。 mochi doughnuts & Taiyaki … ポンデリング系ドーナッツ(mochi doughnuts)とタイ焼きの口からアイスが突っ込まれているタイ焼きアイスクリームのヒットについてはまた話したい。 Tsurumen davis … Researchat.fm ep5で登場した1000日しか営業しないラーメン屋さん。ついに1000日を迎え、営業を終えた（らしい） マリトッツォ … 名前だけ聞いたことがある伝説上の食べ物 BOOK OFF NY Keizer et al. bioRxiv (2021) … “Live-cell micromanipulation of a genomic locus reveals interphase chromatin mechanics” John Gurdon Egli et al. Nature (2007) … “Developmental reprogramming after chromosome transfer into mitotic mouse zygotes” 体細胞の染色体スワップではなかったです… 光ピンセット(Optical tweezers) 磁気ピンセット(Magnetic tweezers) Atomic Force Microscope (AFM) Tetracycline (Tet) Inducible Expression mCherry Yang and Shah Front. Oncol. (2020) … “Nanobodies: Next Generation of Cancer Diagnostics and Therapeutics” Ferritin パーマロイ … ニッケル鉄の合金 Kolora et al. Science (2021) … “Origins and evolution of extreme life span in Pacific Ocean rockfishes” 根魚 Lu et al., Science (2021) … “Long-lived fish in a big pond” Editorial Notes 今年のカナダは歴史的な降水量で雨ばかりの日々でしたが、先週から1ヶ月遅れでようやく夏が来ました (soh) 時節の話なんかするものだから季節外れの話になってしまいました。タイトルにはTweezersを入れましたが、magnetic tweezersの論文ではないです。Rockfishの寿命論文はオープンアクセスではなかった…すいません。(tadasu)

This month on Episode 35 of Discover CircRes, host Cynthia St. Hilaire highlights two original research articles featured in the April 1 issue of Circulation Research, as well as highlights from the Stroke and Neurocognitive Impairment Compendium in the April 15th issue.  This episode also features a conversation with Dr Shubing Chen and Dr Yuling Han from Weill Cornell Medical College to discuss their study, SARS-CoV-2 Infection Induces Ferroptosis of Sinoatrial Node Pacemaker Cells.   Article highlights:   Pabel, et al. Effects of Atrial Fibrillation on the Ventricle   Pattarabanjird, et al. P62-Mediated B1b Cell Atheroprotection   Iadecola, et al. Introduction to the Compendium on Stroke and Neurocognitive Impairment   Cindy St. Hilaire:        Hi and welcome to Discover CircRes, the podcast of the American Heart Association's Journal, Circulation Research. I'm your host, Dr Cindy St. Hilaire, from the Vascular Medicine Institute at the University of Pittsburgh. And today I'm going to be highlighting articles from our April issues of Circulation Research.                                     I'll also speak with Dr Shubing Chen and Dr Yuling Han from Weill Cornell Medical College, and they're with me to discuss their study, SARS-CoV-2 infection induces ferroptosis of Sinoatrial node pacemaker cells.   Cindy St. Hilaire:        The first article I want to share is titled, Effects of Atrial Fibrillation on the Human Ventricle. The first author is Steffen Pabel and the corresponding author is Samuel Sossalla and they're from Regensburg University. Atrial fibrillation, or AFib, is the most common form of heart arrhythmia. Patients with AFib may experience shortness of breath, dizziness and weakness. And they're also at risk for more life-threatening complications, such as clot-induced stroke and heart failure. Focusing on heart failure, this study investigated how disruptions to rhythm in the atria might lead to changes in the ventricular myocardium. The team studied ventricular muscle tissue from 24 patients with AFib and 31 without AFib. While the levels of fibrosis were equivalent in ventricular myocytes from both the AFib and the non AFib patients, other cellular features were distinct. For example, patients with AFib had reduced systolic calcium release, prolonged action potential duration and increased oxidative stress, compared with the non AFib patient controls. These differences were largely recapitulated in ventricular myocytes derived from human induced pluripotent stem cells that had been electrically stimulated to either mimic AFib or normal sinus rhythm. The results indicate that AFib affects the ventricles just as well as the atria and might therefore be best studied and treated with the whole heart in mind.   Cindy St. Hilaire:        The second article I want to share is titled B-1b Cells Possess Unique bHLH-Driven P62-Dependent Self-Renewal and Atheroprotection. The first author is Tanyaporn Pattarabanjird and the corresponding author is Colleen McNamara, from the University of Virginia.   Atherosclerosis is a complex and dynamic chronic inflammatory condition. However, not all immune cells exacerbate this disease. Some immune cells are actively dampening the inflammation. B-1 cells are such cells that do this, and they produce IgM antibodies that bind cholesterol, preventing its uptake into macrophages and therefore limiting macrophage driven inflammatory responses. Increased number of B1 cells, therefore, might be atheroprotective. In mice, deletion of the transcription factor ID3 leads to a boost in B-1 cell IgM production.   Cindy St. Hilaire:        In this work the authors investigated the molecular mechanism underlying this effect and found that upon deletion of ID3 in mice B-1b cells, the level of P62 protein was increased. B-1b cell proliferation was found to be dependent on P62 and over expression of P62 in mouse B-1b cells increased cell numbers, raised plasma IgM levels and importantly, ameliorated diet-induced atherosclerosis in animals. The team went on to show that people with an ID3 mutation had an unusually high level of serum IgM and B-1b cell P62. This suggests that results from mice may hold true for humans, and if so, could inform the development of immunomodulatory treatments for atherosclerosis.   Cindy St. Hilaire:        So the April 15th issue of Circulation Research is our Stroke And Neurocognitive Impairment Compendium. The last Circulation Research Compendium on Stroke was published about five years ago. In this year Dr Costantino Iadecola, Dr Mark Fisher and Dr Ralph Sacco focused this update on advances made over the past five years, with a focus on topics that were not addressed in the previous compendium, that best reflect the leading edge of basic in clinical science related to cerebral vascular diseases. Seemant Chaturvedi, Brian Mac Grory and colleagues provide an overview of preventative strategies according to stroke mechanism, including stroke of unknown cause. And the challenges of stroke prevention with antithrombotic therapy and subjects with increased hemorrhage risk are also considered.   Cindy St. Hilaire:        Stéphanie Debette and Hugh Markus provide an account of the most recent developments in the genetics of cerebrovascular diseases. The gut microbiota is another factor that has recently been linked to stroke risk and Pedram Honarpisheh, Louise McCullough and colleagues provide a comprehensive overview of the microbiology and the microbiota, and the influence that stroke risk factors exert on its composition and homeostatic relationship with mucosal surfaces. Karin Hochrainer and Wei Yang provide a systematic review of the large amount of data and stroke proteomic from animal models and human patients. Matthias Endres and colleagues cover the dramatic effect that innate and adaptive immunity exert on stroke risk and on acute brain damage and post stroke sequelae, such as post-stroke cognitive impairment and depression.                                     Cindy St. Hilaire:        Manuela De Michele, Alexander Merkler and colleagues discuss the cerebral vascular diseases that have emerged as a frequent manifestation of the maladaptive immune response to severe SARS-CoV-2 infection. Jessica Magid-Bernstein and Lauren Sansing review the current concepts on epidemiology, risk factors in etiology, clinical features, as well as the medical and surgical interventions for cerebral hemorrhage. Yunyun Xiong and Marc Fisher cover the progress that has been achieved in the treatment of acute ischemic stroke and Natalie Rost and Martin Dichgans and colleagues address the long term impact of stroke on cognitive function, which is becoming a significant healthcare challenge in the world's aging population.   Cindy St. Hilaire:        So today I have Dr Shubing Chen and Yuling Han from Weill Cornell Medical College. And they're with me to discuss their study SARS-CoV-2 infection induces ferroptosis of Sinoatrial node pacemaker cells. And this article is in our April 1st issue of Circulation Research. So thank you both for joining me today.   Shubing Chen:             Thank you. It's really nice to join the program, and it's really a great honor.   Cindy St. Hilaire:        It's a really great article. I'm so excited to talk about. So there's a lot of research happening regarding SARS-CoV-2 virus and the patients who are infected and have COVID-19. And this paper is focusing on the impact of viral infection on the heart and specifically on the sinoatrial node, which is the primary cardiac pacemaker that keeps our hearts beating. So I was wondering if you could tell us what led you to focus on this particular aspect of COVID-19 symptoms, and also how early in the pandemic did you start this?   Shubing Chen:             Yeah, so we started working on SARS-CoV-2 through back to early 2020 when very unfortunately, New York City was a pandemic center and we had a lot of patients in the hospital unit, and also postdoc students working very hard in the lab. So that's the time we start working on SARS-CoV-2. And I was trained as a stem cell biologist. And what we're really interest is to set up a platform to basically understand which type of cells can be infected by SARS-CoV-2 and if they can, how they respond to SARS-CoV-2 infection. Not only for SARS-CoV-2, we sent it as like a viral infection platform, but SARS-CoV-2 is one of the virus we study now. And it's kind of very surprising. We have a pretty broad platform. We have a lung organoid, we have colon organoids, we have pancreas, we have cardiomyocytes, pacemaker cells. And as expected, we see lung can be infected like colon and because patient had GI tract, liver can be infected, but very surprisingly we see very high cardiomyocytes infection as well as pacemakers.                                       So as we'll know that still big controversy in the field, whether we can detect SARS-CoV-2 like viral protein or viral RA in the heart, in particular, cardiomyocytes. But I think now everyone agree that the cardiomyocytes really can be very well infected actually. Because it's very difficult to get the pacemaker tissue and the sinoatrial tissue from the COVID patient. So we collaborate with Dr Ben Andora's lab at NYU to get this hamster model. So we basically take SA tissue from hamster and then other colleagues basically did the section imaging, and we confirm that the hC4 polymerase cells can be infected by SARS-CoV-2. And at that time we start to learn a more clinical studies they report the COVID patient, they develop arrhythmia, or some other problem, not only with cardiomyocyte, as well as the conduction system. So at that time, that's the time that we say maybe we should do something on the pacemaker and focus on that. So that's how the project was developed.   Cindy St. Hilaire:        That is so interesting. And so I know humans infected, like you just said with SARS-CoV-2, they can develop arrhythmias. What's that timeframe? Is there a common timeframe that this happens? Does it normally happen very close to the infection or only in later stage? What's that window of when these arrhythmias are happening?   Shubing Chen:             At least based on the clinical study we show right now, actually the patient can develop acute arrhythmia. So it can be very soon after they developed symptom for COVID.   Cindy St. Hilaire:        Wow. That's amazing. So you mentioned this, your study utilized a hamster model, which you actually don't see a lot of. Most studies use a lot of rats or most studies I'm familiar with, especially in Circulation Research, they use more rats or more mouse models. So what advantages does that hamster model have and why were you interested in using it?   Shubing Chen:             Yeah, that's actually really specific for SARS-CoV-2. As SARS-CoV-2 mainly use ACE2 as a key entry factor to enter the cells. Of course, there's additional receptor, like neutrophils is one. Like all this enzyme involved, but human and mouse ACE2, they have very different structure. So the SARS-CoV-2 virus combine with human ACE2 very well but not mouse ACE2. So from the beginning, the rat and mouse was not used as a very good model to study SARS-CoV-2 infection. Of course there are other models, like knockin human ACE2 in the mouse and also like ACE2 transgenic mice. That's how different mouse model use. But hamster you don't need any modification, but they are very promising to SARS-CoV-2 infection. And so that's a reason we decide to use that as an animal model to basically run in parallel with our human stem cell model.   Cindy St. Hilaire:        We joke in my lab, mice are not little humans, but it's really true in a lot of cases, they're beautiful models in so many ways, but then when they don't work, they really don't work.   Shubing Chen:             Yeah. Before COVID every time when we try to talk about our human stem cell, derived cells, organoids as a disease model. People always ask, why do you want to work on human organoids? Right? It's that we have all these beautiful animal models like as you mentioned, mouse or rats, that's very broadly used. And we have to find different reasons. And now when we start working on SARS-CoV-2, which is very clear example, that mouse are not identical to human. Yeah.   Cindy St. Hilaire:        Yeah. That's great. I love finding additional models to use that are the best one for the question. So in order to investigate, I guess kind of the mechanism of how this was happening in the SAN cells, the sinoatrial node cells, you had to develop a new differentiation protocol that took the human embryonic stem cells, I think it was the H9 line you used, and essentially differentiate that cell line into a sinoatrial node-like cell. So I was wondering if you could tell us a little bit about A) how did you figure out that protocol and B) how does it work?   Shubing Chen:             So it's actually a long story to cell line.   Cindy St. Hilaire:        We can condense it. Let's get-   Shubing Chen:             At least based on the clinical study we show right now, actually the patient can. Let's condense it. But it's as you can imagine, we did not develop this cell line only for this particular project. Actually, we start working on this cell line back to maybe six, seven years ago. The first postdoc we have who basically knockin the mCherry, Myh6. Which basically label the atrial cardiomyocytes. And another postdoc, Zanir, he basically put a GFP in the SARS2 locus. So now we have this duel reporter line we can visualize the SA nodal cells. And we really spend a lot of time on that because we think that unfortunately in our hand, there is not really no good antibody for SARS2. We think it's very, very important that you can see these cells. So after developing these lines and because my lab run a lot of chemical screening, where we run Zanir, we run several chemical screening to develop the protocol.                                       And Jialing Zhu, another postdoc in the lab, also pick up the project to further develop the protocol. And there is several years' work. We do have this good protocol to make pretty efficiently to make the cells. And it's not only our work. I want to say that. For example, Dr Sean Wu from Stanford, they did this beautiful study on the single cell RNC mouse conduction system and Dr Gordon Keller and many other labs also basically published protocol in the field. We are very excited about this duel reporter line. I think they gave us a lot of new opportunity and we are very happy to share this line. Yeah. So if anyone in the field are interested in that, just contact us.   Cindy St. Hilaire:        Yeah. Anyone listening. That's great. So were you surprised to find the entry factors that SARS-CoV-2 uses to get into a cell, were you surprised to find them on these sinoatrial node cells? And I guess in the context of comparing these particular cells to other cells in the heart, are those entry factors higher in the sinoatrial node cells?   Shubing Chen:             So it can be either surprised or not surprised let's say this way. So because one, we see the cardiomyocytes that can be infected, we were kind of surprised. And then we find actually several type of cells in the heart can be infected, like endothelial cells. I will say that the ACE2 expression of like ACE2 aminophenol in pacemaker cell, it's not significantly higher than cardiomyocytes. So we are not really saying, or seeing that SA nodal cells are more permissive to SARS-CoV-2 infections compared to cardiomyocytes, even in the petri dish, but they can be infected.   Cindy St. Hilaire:        So you found SARS-CoV-2 infection in these sinoatrial nodal cells induces a process called ferroptosis. So Yuling, I was wondering if you could tell us what is ferroptosis and what is it doing in these pacemaker cells?   Yuling Han:                 For the ferroptosis, they was surprised so far that its by the RA sequencing of the SARS-CoV-2 infection make our cells. And the first process is mainly caused by the-   Shubing Chen:             Error in iron.   Yuling Han:                 Yes. So more intake of the iron error and induced the RA's pathway and caused the cell deaths. So by our RA sequencing, we found the key factor involved in ferroptosis pathway is the GPS score was checked after the SARS-CoV-2 infection. So we focused on the ferroptosis pathway and found other key factors or checked after the infection makes in the pacemaker cells.   Cindy St. Hilaire:        What is the ferroptosis doing that disrupts the SNA cells?   Shubing Chen:             Ferroptosis is a type of cell death mechanism. So eventually it will cause cell death. And we think something that is really surprising, but we think it's very interesting, is we only see ferroptosis in the SARS-CoV-2 infected general atrial cells. So SA cells, we actually, as Yuling mentioned, when we develop this platform, we see different type of cell can be affected. And we are very curious what happened. So we see that we run a sequence on each individual cells we can see infection and along, we can see cell death like apoptosis in cardiomyocytes. We see apoptosis and only in SA nodal cells, we actually see the ferroptosis pathway as we come up.   Cindy St. Hilaire:        Why do you think that is in that cell type versus in another? Do you have any ideas about why?   Shubing Chen:             No, we don't have any idea yet to be honest, but we are working on that. But at least I think that it gave us some clue that we really need to use different type of whole cells to study the whole cell response. Because traditionally when we study viral infection and when we see lung, we always say, oh, the cell died. It's fairly simple. But now if we really study the details and we think it's maybe over simplified way to think about how cells can respond to viral infection, not only to SARS-CoV-2 infection. So it gives us the motivation, very strong motivation to now really study how different host tissues response to viral infection.   Cindy St. Hilaire:        I thought that was really interesting, not all cell death is the same.   Shubing Chen:             Yeah. And another thing is kind of a little bit surprising is we actually did a very careful comparison between the SA nodal cells and the cardiomyocyte. We only see ferroptosis come up as SA nodal cell, but not cardiomyocyte. Again, we don't understand why as maybe some host factor that is specific, we're working on that.   Cindy St. Hilaire:        So in addition to working out this mechanism of what is going wrong when these cells are infected with the virus, you also used this embryonic stem cell like tool for a drug screen. So can you walk us through that process in terms of what you did to do that? Did you focus in on one specific type of drugs or was it just kind of an unbiased screen?   Yuling Han:                 For the sinoatrial pacemaker cells, we focus on the antiviral drugs screening. And we also did several other projects, like lot of night or some neuron cells. For the [they did drug screening to find some drugs to inhibit the SARS-CoV-2 entry. And for the dominic neuron, we found SARS-CoV-2 infection can cause neuro cells synapses. So we focus on the synapses associated drug screening, but for the pacemaker cells, they only did the antiviral drug screen.   Cindy St. Hilaire:        And you came up with two drugs that you wrote about in the paper, deferoxamine and imatinib. So what are the mechanisms of action of those drugs? Are they targeting the same thing or are they targeting slightly different things?   Yuling Han:                 For the imatinib, we also found this drug inhibit SARS-CoV-2 entry and we did several other screenings, like the lung organoids and neuro cells. We also found this drugs. And the six drug, the mechanism is kept and the spec protein of SARS-CoV-2. And this was found by several other groups and published some paper this year. And we found this in 2020 maybe. And we published this paper before and we found this mechanism. And for another drug, we checked the RA sequencing data of SARS-CoV-2 affect the peacemaker cells. And we did several run of RA sequencing. And we compared the key factors, involved in SARS-CoV-2 entry. Several key factors like CTSL and like TMPS2 and among several run of RA sequencing. We only found the drug can decrease the expression of CTSL. So we also did PTR immunostaining, and then we found the drug decrease the expression level of CTSL.   Shubing Chen:             Yeah. So actually the other drug, it's also an antiferroptosis drug. So we did the mechanism study and it's very nice to see, we also identify the drug from an unbiased chemical screen. And for the chemical screening, we actually have a pretty large platform and we have around 1200 FDA approved drugs. We have like a 2000 anatrofin amino acid that signal pathway regulators for most of the SARS-CoV-2 screening, as you did mention, we have multiple screening platform. We focus on FDA approved drug. So it's more like for the drug repurposing and for other screening we also write larger skills.   Cindy St. Hilaire:        So we got a mechanism, we got a super specific cell type and we now have some drugs. So what are the translational implications of these findings? And I guess I'm thinking about that in terms of the time course of when a patient gets infected, has symptoms, has arrhythmia, like where could you possibly target this ferroptosis pathway? Meaning if someone already is exhibiting AFib as a result of the infection, is that actually too late? Or can you start to treat it to reverse it or prevent it from getting worse? Like what do you see as a therapeutic potential for using these drugs?   Shubing Chen:             That's a very good question. I will say this way, I think when we identify all these drugs, it's very, very exciting. But for antiviral drug development perspective, we definitely want a drug that show broader spectrum. So for COVID patient, of course we want to protect their heart, but we also want to protect their lungs.   Cindy St. Hilaire:        Exactly. Protect everything.   Shubing Chen:             Exactly. Exactly. So for the real drug that can clinical use, I think the lack of broad spectrum antiviral drug, I think that will be the way to go for drug development and for the cardioprotective respective. So if the patient do have very severe cardio symptom, particularly like arrhythmia symptom, I think that can be considered. But I don't want to really say this is the drug to treat the COVID patient. I don't think that's a way to go, particularly for ferroptosis is a cell type. This is a phenotype, very specific for the pacemaker. And I think for us, as a basic scientist, is very, very important that we understand the biology and we can identify these normal chemical tools that we can manipulate the system that can facilitate the future drug development.   Cindy St. Hilaire:        So do you think your findings and I mean findings at multiple levels, that a viral infection can induce apoptosis in one cell, but ferroptosis in another cell, but also the findings of viral infection in general, sufficient enough to drives sinoatrial node cell dysfunction. Do you think this is specific to SARS-CoV-2 and corona viruses or do you think this is something that is more broad with other viruses that maybe we just haven't recognized possibly because we don't have the tools yet?   Shubing Chen:            That's a great question. I will say some other type of virus can also infect heart, at least cardiomyocyte, like a Coxsackie virus, regular virus three. And there's actually a lot of study on the viral infection on the cardiomyocytes. And for us, the most exciting part is we really have now in serious, limited starting materials to get these pacemaker cells. Like I SA nodal cells. So we can use this as a platform to study how other virus infect, how the viral infection in general cause cell dysfunction. Because in the study we also do the calcium blocks assay, we can monitor their beating and then we can do RN-seq to monitor their transcription changes. Because this we have this still reporting system, we can purify cells, we can even run larger scale, like epigenetic level, how they change. So that's a very useful tool to study how cell responds to viral infection. I'm very excited about that.   Cindy St. Hilaire:        That's great. Well, Dr Chen and Dr Han, thank you so much for joining me today. Congratulations on a beautiful story. And I look forward to hearing more out all these different organoid and cell models you have.   Shubing Chen:            Cindy, thank you. Thank you for so much for having us.   Cindy St. Hilaire:        That's it for the highlights from the April issues of Circulation Research. Thank you for listening. Please check out the CircRes Facebook page and follow us on Twitter and Instagram with the handle @CircRes and #DiscoverCircRes. Thank you to our guests, Dr Shubing Chen and Dr Yuling Han. This podcast was produced by Ishara Rantikac edited by Melissa Stoner and supported by the editorial team of Circulation Research. Some of the copy text for highlighted articles was provided by Ruth Williams. I'm your host, Dr Cindy St. Hilaire, and this is Discover CircRes, you're on the go source for the most exciting discoveries in basic cardiovascular research. This program is copyright of the American Heart Association, 2022. The opinions expressed by speakers in this podcast are their own and not necessarily those of the editors or of the American heart Association. For more our information visit ahajournals.org.  

ニューロンの細胞種はどう定義されるのか？萩原が in vivo Caイメージングとspatial transcriptomicsを組み合わせた研究２報を紹介しながら議論。トランスクリプトーム回の前編。 Show Notes: ・Dense Functional and Molecular Readout of a Circuit Hub in Sensory Cortex...今回メインで話題にした論文その１。CRACK: Comprehensive Readout of Activity and Cell Type Markers. (Jerry Chenラボ) ・Behavioral state coding by molecularly defined paraventricular hypothalamic cell type ensembles...今回メインで話題にした論文その２。CaRMA: Calcium and RNA multiplexed activity (Scott Sternsonラボ) ・Allen Institute for Brain Science...ポール・アレンの寄付によるシアトルにある研究所。脳のアトラス・マップ等のデータベース作り、Aiシリーズのマウスライン作りを中心に大規模リソースの提供を行っている。 ・Genetic Dissection of Neural Circuits...神経回路理解への遺伝学的アプローチのレビュー。Luo, Callaway, Svobodaらの2008年時点での見解。細胞種とは何か、という議論も。 ・Genetic Dissection of Neural Circuits: A Decade of Progress...同著者らによる2018年時点での10年間の振り返りと未来への展望。 ・t-type...遺伝子発現(transcriptome)により定義される神経細胞の細胞種 (by Allen) ・me-type...形態および電気生理的性質(morpho-electric)により定義される神経細胞の細胞種 (by Allen) ・生理研のKawaguchi, Kubota, Kondoらによる細胞種分類の先駆け的な仕事。1, 2, 3 ・Integrated Morphoelectric and Transcriptomic Classification of Cortical GABAergic Cells...Allen InstituteのPatch-seq論文。大量の抑制性ニューロンについてmet-typeの分類を試みた。 ・Phenotypic variation of transcriptomic cell types in mouse motor cortex...上とペアになるToliasらのPatch-seq論文。M1の興奮性/抑制性ニューロンについて。 ・Spatial Transcriptomes...様々な種類のmRNAの空間局在を見る手法 ・HCR v3...Hybridization chain reactionの略。FISHシグナル増幅手法の一種。v3はコンポーネント数が増えておりSN比が高い ・Janelia...HHMIによる研究所。各ラボのサイズを小さく保ち、プラットフォーム・プロジェクト・コアファシリティに重点を置く実験的・革新的な研究所。ハエの遺伝学およびGCaMPのアップデート等のリソース提供による分野への貢献も大きい。 ・RNAscope...FISHシグナル増幅手法の一種。Z型のプローブを用いるのが特徴。 ・GRINレンズ...視床など脳深部からCaイメージングをする際、脳へのダメージを最小限にするために脳表から刺入する内視鏡のこと。 ・Sensory coding mechanisms revealed by optical tagging of physiologically defined neuronal types...GCaMP-2A-PAmCherry (photoactivatable mCherry) 発現->Caイメージング->局所的な光照射によるsingle-cell解像度でのPAmCherryのphotoactivation-> FACS -> RNAseqにより、ex vivoカルシウムイメージングの結果を受けて特定の細胞種を標識し、その遺伝子発現プロファイルを調べる手法を作成。(Tim Holyラボ) ・RecV recombinase system for in vivo targeted optogenomic modifications of single cells or cell populations...光で会合するタンパク質VVDとsplit-Creを結合し、光照射によって活性を持つリコンビナーゼを作った論文。in vivo, 2photon刺激でも動いていそう。(Ali CetinらAllen, Stanford) ・Allenによるenhancerを利用したsubclassへのgenetic accessとAAVの作成。Creラインが要らなくなる日も近いか。 ・HongKui Zeng's #WWNDev​ Forum on March 11th 2021...HongKui Zengによる最新のAllen Insituteのshowcase。1時間のトークに現状の全てがいっぱいに詰め込まれていてThe answer感漂う仕上がり。 Editorial Notes: ・FISHプローブ剥がすのって比較的容易にできるんですね（宮脇） ・XXX-seqという手法が大量に出てくるのですが、どうもXXXスィークと流暢に言えずXXXセックと呼んでしまうのをやめたい。'下ネタ言おうとして踏みとどまったおじさん'みたいに見えてないか心配です(嘘) 尚、宮脇さんは'sick'と言いがちですが、病気なのか、あるいは"ヤバい"というポジティブなニュアンスを今風に付加しているのかは謎 (萩原)

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.10.27.357418v1?rss=1 Authors: Cihlova, B., Huskova, A., Böserle, J., Nencka, R., Boura, E., Silhan, J. Abstract: Spanish flu and other influenza outbreaks, the recent Zika epidemics, and the ongoing COVID-19 pandemic are the most profound examples of severe widespread diseases that are caused by RNA viruses. Perhaps less well-known yet dangerous RNA viruses cause deadly diseases such as polio, Ebola, measles, rubella, yellow fever, dengue fever, etc. To combat a particular viral disease by diminishing its spread and number of fatal cases, effective vaccines and antivirals are indispensable. Therefore, quick access to the means of discovery of new treatments for any epidemic outbreak is of great interest and in vitro, biochemical assays are the basis of drug discovery. The recent outbreak of the coronavirus pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) demands an affordable and reliable assay for testing antivirals. Here, we developed a quick and inexpensive high-throughput fluorescent assay to test inhibitors of viral proteases. Accordingly, we employed this assay to sample inhibitors for papain-like protease from SARS-CoV-2. In addition, we validated this assay for screening inhibitors of flaviviral protease from the tick-borne encephalitis virus to emphasize a broad range of applications of our approach. This fluorescent high-throughput assay is based on fluorescent energy transfer (FRET) between two distinct fluorescent proteins (eGFP and mCherry) connected via a substrate polypeptide. When the substrate is cleaved, FRET is abolished and the change in fluorescence corresponds to reaction progress. Our data show that this assay can be used for testing the inhibitors in the 96 or 384 well plates format with robust and reproducible outcomes. Copy rights belong to original authors. Visit the link for more info

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.07.21.214452v1?rss=1 Authors: Almeida, M. P., Welker, J. M., Ekker, S. C., Clark, K. J., Essner, J. J., McGrail, M. Abstract: The Cre/lox recombinase system has been widely used for spatiotemporal control of gene expression in animal model systems, however, efficient methods to isolate zebrafish Cre drivers that reliably recapitulate endogenous expression patterns of known genes are in need. Here, we apply CRISPR/Cas9 double-strand breaks to direct targeted integration using short homology of a 2A-Cre recombinase transgene into the early coding region of proneural genes ascl1b, olig2 and neurod1. The pPRISM-2A-Cre targeting vector contains a linked lens-specific fluorescent secondary marker cassette for identification of transgenic embryos, and we observed high rates of germline transmission ranging from 10%-100% (2/20 olig2; 1/5 neurod1; 3/3 ascl1b). The established transgenic lines Tg(ascl1b-2A-Cre)is75, Tg(olig2-2A-Cre)is76, and Tg(neurod1-2A-Cre)is77 expressed functional Cre recombinase. in situ hybridization showed Cre expression reflected the pattern of the endogenous targeted proneural gene. In combination with Tg(ubi:loxP-EGFP-loxP-mCherry), each driver induced a switch from EGFP to mCherry expression in the expected proneural cell populations and their descendants, indicating efficient Cre-mediated recombination and excision of the floxed EGFP cassette. The results demonstrate Cre recombinase expression is driven by the native promoter and regulatory elements of the targeted genes. This approach provides a straightforward, efficient, and cost-effective method to generate cell type specific zebrafish Cre drivers whose spatial and temporal restricted expression mimics endogenous genes, surmounting the challenges associated with promoter BAC cloning and transposon mediated transgenesis. Copy rights belong to original authors. Visit the link for more info

The September episode of 3 Minute 3rs, brought to you by the NC3Rs (www.nc3rs.org.uk), the North American 3Rs Collaborative (www.na3rsc.org), and Lab Animal (www.nature.com/laban) Papers behind the pod: 1. http://jpet.aspetjournals.org/content/371/1/15.long 2. https://www.sciencedirect.com/science/article/pii/S001216061830006X 3. https://www.nature.com/articles/s41467-019-11259-w [NC3Rs] Accurate measurements of drug and metabolite concentrations in the blood are vital to estimate exposure to the target in humans and animals during drug development. Zebrafish larvae are increasingly used for pharmacological research, but measurements of blood drug concentrations in these small animals have been technically challenging. A team at Leiden University have developed a method for nanoscale blood sampling from the posterior cardinal vein of zebrafish larvae at five days post fertilisation. A median volume of 1.12 nL of blood can be collected from each embryo and samples pooled to form a single replicate, which can be analysed by Liquid chromatography–mass spectrometry. While drug and metabolites could be successfully measured in the pooled samples, the authors suggest improvements to the sensitivity of the technique, which could reduce the number of embryos needed for each replicate. In addition, using microfluidic embryo handling techniques, blood sampling could be further automated and yield improved while reducing the amount of drug required. Further development of this microsampling technique has the potential to increase the use of the zebrafish embryo model to define drug pharmacokinetic properties. [NA3RsC] Josephine Morris and her colleagues at Bristol University used transgenic lines of zebrafish to study mechanisms of collagen formation and repair. This work was published in the journal Developmental Biology, Vol 441. They crossed transgenic zebrafish lines which integrated green fluorescent protein, expressed in the epidermis and mCherry collagen which is specifically expressed in the basal epidermis which allowed them to understand the dynamic nature of collagen 1 fibril deposition. The authors used Transmission Electron microscopy to demonstrate the intricate pattern integration of the fluorescent proteins in embryonic development. In other studies, a wound was created with a 30 g needle on the flank of 4 day old larvae and collagen repair was documented pictorially. By using the GFP collagen and mCherry collagen lines together, they were able to exploit the unique live imaging in larval fish to probe the process of collagen deposition and wound remodeling specifically in the basal epidermis and deeper layers. It is hoped that these transgenic lines will enable live imaging of collagen deposition and remodeling in various other organs and diseases. [LA] And finally, say hello to LipoGlo, a new reporter system for keeping track of lipoproteins in vivo. These proteins ferry fats throughout the body – you may be familiar with HDLs and LDLs, the latter of which can contribute to cardiovascular disease in people. A particular particle, Apolipoprotein B-containing lipoprotein, is particularly problematic and while it has been studied in mammals, such animals don't lend themselves to the large numbers needed for high-throughput drug discovery work. Enter the larval zebrafish. In order to visualize APoB-lipoproteins across the whole translucent organism, the research team took advantage of a glowing enzyme called NanoLuc, which they attached to APoB in the larvae. This bioluminescent reporter is highly sensitive and quite bright, allowing the team to follow the distribution and concentrations of the lipoprotein as it traversed the vascular system of the tiny little zebrafish. Additional details about the new tool can be found in the journal Nature Communications. See acast.com/privacy for privacy and opt-out information.

In late October of this year a gunman open fired in the Tree of Life Synagogue, killing eleven people. Pittsburgh local and KCSB repoter Megan Stafford reflects on how the Squirrel Hill neighborhood, where the shooting took place, has changed. She also interviews Soundcloud rapper MCherry on how he used his music to understand the tragic event.

Das Ektromelievirus, der Erreger der Mäusepocken, wird dem Genus der Orthopockenviren zugeordnet und gehört zu den Vertretern, die nur für einen Wirt virulent sind. Das Ektromelievirus ist spezifisch an die Maus adaptiert und induziert dort eine zyklisch, systemische Infektionskrankheit. An der Ausbildung dieser letalen Erkrankung sind vermutlich eine Vielzahl regulatorischer Virusproteine beteiligt, die sehr genau an das Immunsys-tem der Maus angepasst sind. Kandidaten für sogenannte Immunevasi-onsgene sind für fast alle Orthopockenviren identifiziert und beschrieben. Aufgrund limitierter Untersuchungsmöglichkeiten ist aber noch sehr wenig über die Funktionen dieser Gene bekannt, vor allem mit welchen Mecha-nismen die hier kodierten Faktoren agieren, um in vivo die Entwicklung eines fatalen Krankheitsverlaufes zu fördern. Das Ziel dieser Arbeit war es, einen neuen experimentellen Ansatz für die Analyse der Pathogenesemechanismen der Ektromelievirusinfektion in vitro und in vivo in der Maus zu entwickeln. Die Strategie beruhte auf der Markierung des Ektromelievirus mit einem rekombinanten Gen zur Ex-pression eines Fluoreszenzproteins. Dieser Reporter sollte neue nützliche Einblicke in den Ablauf des Lebenszyklus des Erregers ermöglichen, gleichzeitig sollte das fluoreszenzmarkierte Virus im Vergleich zu nicht rekombinantem Ektromelievirus unveränderte biologische Eigenschaften besitzen. Als Fluoreszenzmarker diente in der hier vorliegenden Arbeit das Protein mCherry, das mit den etablierten Detektionssystemen den best-möglichen Nachweis virusinfizierter Zellen in vitro und in vivo ermöglichen sollte. Zunächst konnte zur Generierung eines rekombinanten Ektromelie-mCherry Virus im Genom des Ektromelievirus ein neuartiger Insertionslo-kus identifiziert werden. Der Einbau der Fremdgensequenzen in den Zwi-schengenlokus EVM063 und EVM064 interferierte nicht mit anderen funk-tionellen Bereichen des Ektromeliegenoms und erlaubte die Herstellung stabiler rekombinanter Ektromelieviren. Die neue Insertionsstelle kann somit in Zukunft auch für die Konstruktion anderer gentechnisch modifi-zierter Ektromelieviren eingesetzt werden. Nach der erfolgreichen Rekom-bination des Ektromelie-mCherry Virus wurden drei voneinander unab-hängige klonale Isolate dieses Virus gewonnen und einer detaillierten Charakterisierung in in vitro Infektionsexperimenten unterzogen. Das mCherry Protein erwies sich hierbei als ein ausgezeichnetes molekularbio-logisches Werkzeug zur direkten Markierung der Infektion unterschiedli-cher Zielzellen mit Ektromelievirus. Jedes der drei untersuchten rekombi-nanten Ektromelieviren vermittelte eine deutlich sichtbare rote Fluores-zenz infizierter Zellen bereits innerhalb eines einzigen Infektionszyklus (12 Stunden nach Infektion). Zur Prüfung ob Einbau und Expression des Re-portergens das natürliche Infektionsverhalten des Ektromelievirus beein-flusst, wurde das Wachstum der drei rekombinanten Ektromelieviren in verschiedenen etablierten Zelllinien und in in vitro präparierten primären Mauszellen analysiert. Alle Ektromelie-mCherry-Viren wiesen eine mindes-tens genau so gute Vermehrungsfähigkeit wie das nicht rekombinante Ektromelie-Wildtypvirus auf. Zudem identifizierten die vergleichenden Un-tersuchungen das Ektromelie-mCherry-Virus 1 als das Virus mit den bes-ten Wachstumseigenschaften auf permanenten und primären Zellkulturen. Dieses Virus bietet sich daher als eine besonders vielversprechende Aus-gangsbasis für die Herstellung von gezielt mutierten Viren und für weitere Untersuchungen in in vitro und in vivo Infektionsexperimenten an. Mit den in dieser Arbeit dargestellten Experimenten ist es zum ersten Mal gelun-gen, rekombinante mCherry-markierte Ektromelieviren zu konstruieren, die in allen untersuchten biologischen Eigenschaften mit einem hoch virulen-ten Ektromelie-Wildtypvirus übereinstimmen. Die zukünftige Nutzung die-ser Viren verspricht völlig neue Einblicke in die molekularen Mechanismen der Wechselwirkung zwischen einem wirtspezifischen Orthopockenvirus und seinem natürlichen Wirt. Als Ergebnis erwartet werden dürfen ein um-fassenderes Verständnis zur Pathogenese systemischer Virusinfektionen und grundlegende Erkenntnisse zur Funktion der Immunabwehr. Beides sind wichtige Voraussetzungen für die Entwicklung neuer wirksamer Impf-stoffe und Therapieansätze.

Background: During their transit through the female genital tract, sperm have to recognize and discriminate numerous chemical compounds. However, our current knowledge of the molecular identity of appropriate chemosensory receptor proteins in sperm is still rudimentary. Considering that members of the Tas1r family of taste receptors are able to discriminate between a broad diversity of hydrophilic chemosensory substances, the expression of taste receptors in mammalian spermatozoa was examined. Methodology/Principal Findings: The present manuscript documents that Tas1r1 and Tas1r3, which form the functional receptor for monosodium glutamate (umami) in taste buds on the tongue, are expressed in murine and human spermatozoa, where their localization is restricted to distinct segments of the flagellum and the acrosomal cap of the sperm head. Employing a Tas1r1-deficient mCherry reporter mouse strain, we found that Tas1r1 gene deletion resulted in spermatogenic abnormalities. In addition, a significant increase in spontaneous acrosomal reaction was observed in Tas1r1 null mutant sperm whereas acrosomal secretion triggered by isolated zona pellucida or the Ca2+ ionophore A23187 was not different from wild-type spermatozoa. Remarkably, cytosolic Ca2+ levels in freshly isolated Tas1r1-deficient sperm were significantly higher compared to wild-type cells. Moreover, a significantly higher basal cAMP concentration was detected in freshly isolated Tas1r1-deficient epididymal spermatozoa, whereas upon inhibition of phosphodiesterase or sperm capacitation, the amount of cAMP was not different between both genotypes. Conclusions/Significance: Since Ca2+ and cAMP control fundamental processes during the sequential process of fertilization, we propose that the identified taste receptors and coupled signaling cascades keep sperm in a chronically quiescent state until they arrive in the vicinity of the egg - either by constitutive receptor activity and/or by tonic receptor activation by gradients of diverse chemical compounds in different compartments of the female reproductive tract.

Background: It is thought that foamy viruses (FVs) enter host cells via endocytosis because all FV glycoproteins examined display pH-dependent fusion activities. Only the prototype FV (PFV) glycoprotein has also significant fusion activity at neutral pH, suggesting that its uptake mechanism may deviate from other FVs. To gain new insights into the uptake processes of FV in individual live host cells, we developed fluorescently labeled infectious FVs. Results: N-terminal tagging of the FV envelope leader peptide domain with a fluorescent protein resulted in efficient incorporation of the fluorescently labeled glycoprotein into secreted virions without interfering with their infectivity. Double-tagged viruses consisting of an eGFP-tagged PFV capsid (Gag-eGFP) and mCherry-tagged Env (Ch-Env) from either PFV or macaque simian FV (SFVmac) were observed during early stages of the infection pathway. PFV Env, but not SFVmac Env, containing particles induced strong syncytia formation on target cells. Both virus types showed trafficking of double-tagged virions towards the cell center. Upon fusion and subsequent capsid release into the cytosol, accumulation of naked capsid proteins was observed within four hours in the perinuclear region, presumably representing the centrosomes. Interestingly, virions harboring fusion-defective glycoproteins still promoted virus attachment and uptake, but failed to show syncytia formation and perinuclear capsid accumulation. Non-fused or non-fusogenic viruses are rapidly cleared from the cells by putative lysosomal degradation. Monitoring the fraction of viruses containing both Env and capsid signals as a function of time demonstrated that PFV virions fused within the first few minutes, whereas fusion of SFVmac virions was less pronounced and observed over the entire 90 minutes measured. Conclusions: The characterized double-labeled FVs described here provide new mechanistic insights into FV early entry steps, demonstrating that productive viral fusion occurs early after target cell attachment and uptake. The analysis highlights apparent differences in the uptake pathways of individual FV species. Furthermore, the infectious double-labeled FVs promise to provide important tools for future detailed analyses on individual FV fusion events in real time using advanced imaging techniques.

Background: Photorhabdus luminescens is a Gram-negative luminescent enterobacterium and a symbiote to soil nematodes belonging to the species Heterorhabditis bacteriophora. P. luminescens is simultaneously highly pathogenic to insects. This bacterium exhibits a complex life cycle, including one symbiotic stage characterized by colonization of the upper nematode gut, and a pathogenic stage, characterized by release from the nematode into the hemocoel of insect larvae, resulting in rapid insect death caused by bacterial toxins. P. luminescens appears to sense and adapt to the novel host environment upon changing hosts, which facilitates the production of factors involved in survival within the host, host-killing, and -exploitation. Results: A differential fluorescence induction (DFI) approach was applied to identify genes that are up-regulated in the bacterium after infection of the insect host Galleria mellonella. For this purpose, a P. luminescens promoter-trap library utilizing the mCherry fluorophore as a reporter was constructed, and approximately 13,000 clones were screened for fluorescence induction in the presence of a G. mellonella larvae homogenate. Since P. luminescens has a variety of regulators that potentially sense chemical molecules, like hormones, the screen for up-regulated genes or operons was performed in vitro, excluding physicochemical signals like oxygen, temperature or osmolarity as variables. Clones (18) were obtained exhibiting at least 2.5-fold induced fluorescence and regarded as specific responders to insect homogenate. In combination with a bioinformatics approach, sequence motifs were identified in these DNA-fragments that are similar to 29 different promoters within the P. luminescens genome. By cloning each of the predicted promoters upstream of the reporter gene, induction was verified for 27 promoters in vitro, and for 24 promoters in viable G. mellonella larvae. Among the validated promoters are some known to regulate the expression of toxin genes, including tccC1 (encoding an insecticidal toxin complex), and others encoding putative toxins. A comparably high number of metabolic genes or operons were observed to be induced upon infection; among these were eutABC, hutUH, and agaZSVCD, which encode proteins involved in ethanolamine, histidine and tagatose degradation, respectively. The results reflect rearrangements in metabolism and the use of other metabolites available from the insect. Furthermore, enhanced activity of promoters controlling the expression of genes encoding enzymes linked to antibiotic production and/or resistance was observed. Antibiotic production and resistance may influence competition with other bacteria, and thus might be important for a successful infection. Lastly, several genes of unknown function were identified that may represent novel pathogenicity factors. Conclusion: We show that a DFI screen is useful for identifying genes or operons induced by chemical stimuli, such as diluted insect homogenate. A bioinformatics comparison of motifs similar to known promoters is a powerful tool for identifying regulated genes or operons. We conclude that signals for the regulation of those genes or operons induced in P. luminescens upon insect infection may represent a wide variety of compounds that make up the insect host. Our results provide insight into the complex response to the host that occurs in a bacterial pathogen, particularly reflecting the potential for metabolic shifts and other specific changes associated with virulence.