Podcasts about biogenic

This week we're talking about natural fibre insulation and the potential of biogenic building products with IndiNature manufacturer (and co-founder) Sam Baumber. It feels like a timely follow-up to last week's episode about quantifying embodied carbon, particularly in relation to the role biogenic products have in providing a mid-to-long-term carbon buffer. But we get into the other aspects of interest, addressing fire safety, health, thermal performance, and economic benefits.It wasn't intended to sound like an advertorial but, listening back it does a little. This is because it's a product that we're enthusiastic about. We hope that you are too.Notes from the showSam on LinkedInThe IndiNature websiteJeff's whole life carbon presentation from the AECB Conference 2022**SOME SELF-PROMOTING CALLS TO ACTION**We don't actually earn anything from this, and it's quite a lot of work, so we have to promote the day jobs.Jeff, Alex, and Dan about websites, branding, and communications - zap@eiux.agency; Everything is User ExperienceFollow us on the Zero Ambitions LinkedIn pageSubscribe and advertise with Passive House Plus (UK edition here too)Check Lloyd's Substack: Carbon UpfrontJoin ACANJoin the AECB Join the IGBCCheck out Her Own Space, the renovation and retrofit platform for women (but not in a patronising way)**END OF SELF-PROMOTING CALLS TO ACTION**

Architects Paul Lewis and Marc Tsurumaki, principals of the New York-based practice LTL Architects, join Charles Waldheim to discuss their recent book Manual of Biogenic House Sections.

This week we are talking carbon capture and storage technology (BECCS) with Michael Brogle. Michael works as a Business Development Manager at Neustark AG. Based in Switzerland, Neustark is a BECCS company, which captures biogenic CO2 and permanently stores it in recycled concrete. Neustark's plants and processes are in use in Switzerland and various European countries, the company currently expands its international operations with a strong focus on the French market. They have a very unique approach from source to sink. We are delighted that they have chosen to come to Bio360 Expo to further their development and build up the international markets in collaboration with local biogas and concrete recycling partners.

I polled people on IG last month and almost 80% of people that saw my story said they felt like they have food sensitivities. So, that's a problem because once you dive into the intricacies of that there is a lot of nuances.So to help with this & answer the question I get in so many different flavors each week, I'm hosting a live training and Q&A session called “What should I eat? Answering your questions about food reactions and inflammation”.You can register at christabiegler.com/foodreactionsThis week I talk to the brilliant and humble Tim Hyatt, ND of Biogenic Nutrition. Dr. Hyatt shares his expertise on amino acid therapy. He deep dives into anxiety and proper testing for neurotransmitters and hormones. He shares the mental checklist he goes through as a practitioner as well as useful tips for patients and practitioners alike.KEY TAKEAWAYS:What does anxiety look like in patients?ANXIETY def: our reaction or response to the emotion of fearAmino Acid therapyNeurotransmitter testing for anxietyUnderstanding and quantifying stress: Perception and PerspectiveCortisol and HormonesWhat's going on in the brain with anxietyCortisol/stress impact on sex hormonesDR. TIM SHARED HELPFUL TIPS ON:Not dismissing "stress"Looking at the lab but also the rest of the personWhat helps with receptor function -Good nutrition, reduction of inflammation, good absorption of AA is hugeProper testing of cortisol and what results tell usMechanisms in the body/brain that lead to anxietyWhat is anxiety and what is it NOT? Do we miscategorize anxiety? MENTIONED ON THIS EPISODE:DUTCH testABOUT DR. TIM:As an innovator who enjoys discovery, research, and science, Dr. Timothy Hyatt loves to create and improve products that help people. It was his frustration with conventional medicine's treatment of his mother when she came down with a life-ending chronic illness that turned his thoughts to alternative medicine. Dr. Hyatt earned his doctorate in naturopathic medicine at the National College of Natural Medicine in Portland, Oregon in 2006. From there he began working in the biotech industry where he was directly involved in product development, research, and sales and marketing. . His first product idea was an amino acid formula that improves symptoms of brain-based disorders and, in late 2011, after moving his practice to Oregon, he founded Biogenic Nutrition other partners and currently serves as the company's president. WHERE TO FIND DR. TIM: https://biogenicnutrition.com/ WHERE TO FIND CHRISTA:https://www.christabiegler.com/On IG:instagram.com/anti.inflammatory.nutritionist/Shop our Favoriteschristabiegler.com/shopLoving the podcast? Leave us a review and ENTER OUR GIVEAWAY NOW!Sharing & reviewing this podcast is the BEST way to help us succeed with our mission to help integrate the best of East & West empower you to raise the bar on your health story. Just go to https://reviewthispodcast.com/lessstressedlifeSPONSORS:A special thanks to our VIP sponsor RUPA Health, our lab concierge service that helps our clients get standard bloodwork 2/3 off retail direct to consumer lab test pricing. Let them know I sent you when you sign up for your free practitioner account.

A west of Ireland TD has described as nonsense trying to calculate biogenic methane at national rather than international level. And we hear how wool from Leitrim sheep is being used for a membrane for walking trails locally by volunteers on the Leitrim way

Biogenic Amorphous Silica is a natural product that offers an impressive array of benefits when added to any soil type or potting medium. Nick Clayton is a Co-Founder of a company called Mineral Magic which is mining and distributing BAS in Australia, and in this episode he helps us understand why we might consider purchasing some to help give our soils water retaining and drainage as well as provide plant-available silica for our plants.AUSTRALIAN GIVEAWAYWe are excited to announce a giveaway for two 10kg bags of Mineral Magic to two lucky Aussie listeners. Make sure to join our mailing list to enter!https://plants-grow-here.ck.page/068b495fadHead to the Podcast page Plants Grow Here website if you can't see clickable links on your podcast app.EPISODE LINKSMineral Magic's website: https://www.mineralmagic.com.au/Shop: https://www.mineralmagic.com.au/products.htmlFacebook: https://www.facebook.com/mineralmagic.com.au/LinkedIn: https://www.linkedin.com/company/mineral-magic/Instagram: https://www.instagram.com/Mineral_Magic_Australia/Youtube: https://www.youtube.com/channel/UCbO_mVokUrwMD9gy0oKdW8AFOLLOW US ON SOCIAL MEDIATwitter: @PlantsGrowHere / Facebook: @PlantsGrowHerePodcast - Join our Facebook group!VISIT OUR WEBSITEYou'll find heaps of educational blog articles, including What Is Healthy Soil, And How Can We Build It?, How To Encourage Soil Biodiversity In The Garden & 8 Types Of Soil-Dwelling Organisms, and Organic vs Artificial Fertilisers & The Best Options To Keep Your Plants Satisfied.LET'S WORK TOGETHERAre you in the industry or an enthusiast with something of value to share? We're always on the hunt for interesting people, doing interesting things. If you'd like to work with us send a message via our online form or a direct email to plantsgrowhere@gmail.com.

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.09.25.312967v1?rss=1 Authors: Braco, J. T., Saunders, C. J., Nelson, J. M., Johnson, E. C. Abstract: In insects, Adipokinetic hormone is the primary hormone responsible for the mobilization of stored energy. While a growing body of evidence has solidified AKHs role in modulating the physiological and behavioral responses to metabolic stress, little is known about the upstream endocrine circuit that directly regulates AKH release. We evaluated the AKH-expressing cell transcriptome to identify potential regulatory elements controlling AKH cell activity, and found that a number of receptors show consistent expression levels, including all known dopamine receptors, dopamine ecdysone receptor (DopEcR), Dopamine 2-like receptor (D2R), Dopamine 1-like receptor 2 (DopR2), DopR, and the Pigment Dispersing Factor (PDFR). We tested the consequences of targeted genetic knockdown and found that RNAi elements targeting each dopamine receptor caused a significant reduction in survival under starvation. In contrast, PDFR knockdown significantly extended lifespan under starvation whereas expression of a tethered PDF in AKH cells resulted in a significantly shorter lifespan during starvation. These manipulations also caused various changes in locomotor activity under starvation. Specifically, there were higher amounts of locomotor activity in dopamine receptor knockdowns, in both replete and starved states. PDFR knockdown resulted in increased locomotion during replete conditions and locomotion levels that were comparable to wild-type during starvation. Expression of a membrane-tethered PDF led to decreased locomotion under baseline and starvation. Next, we used live-cell imaging to evaluate the acute effects of the ligands for these receptors (dopamine, ecdysone, and Pigment Dispersing Factor) on AKH cell activation. Dopamine application led to a transient increase in intracellular calcium in a sugar-dependent manner. Furthermore, we found that co-application of dopamine and ecdysone led to a complete loss of this response, suggesting that these two hormones are acting antagonistically. We also found that PDF application directly led to an increase in cAMP in AKH cells, and that this response was dependent on expression of the PDFR in AKH cells. Together these results suggest a complex circuit in which multiple hormones act on AKH cells to modulate metabolic state. Copy rights belong to original authors. Visit the link for more info

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.09.17.301382v1?rss=1 Authors: Morud, J., Hardege, I., Liu, H., Wu, T., Basu, S., Zhang, Y., Schafer, W. Abstract: Pentameric ligand-gated ion channels (LGCs) play conserved, critical roles in fast synaptic transmission, and changes in LGC expression and localisation are thought to underlie many forms of learning and memory. The C. elegans genome encodes a large number of LGCs without a known ligand or function. Here, we deorphanize five members of a family of Cys-loop LGCs by characterizing their diverse functional properties that are activated by biogenic amine neurotransmitters. To analyse the neuronal function of these LGCs, we show that a novel serotonin-gated cation channel, LGC-50, is essential for aversive olfactory learning. lgc-50 mutants show a specific defect in learned olfactory avoidance of pathogenic bacteria, a process known to depend on serotonergic neurotransmission. Remarkably, the expression of LGC-50 in neuronal processes is enhanced by olfactory conditioning; thus, the regulated expression of these receptors at synapses appears to represent a molecular cornerstone of the learning mechanism. Copy rights belong to original authors. Visit the link for more info

Brian Cheshire joins Jack Walker and Paul Atzemis to discuss SSPC Technology Guide 27 - Recommended Performance Properties for Liquid-Applied Organic Polymeric Coatings and Linings for Concrete Structures in Municipal Wastewater Facilities. Listen as the trio discuss the factors that challenge coating systems in a wastewater treatment plant. 0:00 – Intro 0:51 – Brian Cheshire and Chumbawumba 3:10 – SSPC Technology Guide 27¬¬ – Recommended Performance Properties for Liquid-Applied Organic Polymeric Coatings and Linings for Concrete Structures in Municipal Wastewater Facilities http://shop.sspc.org/ST-000G27 4:56 – Collection systems - Manholes, interceptors, lift stations 5:20 – Hydrogen sulfide gas, methane gas present in the headspace challenges to concrete and coating systems 5:52 – Biogenic sulfide corrosion, commonly known as microbial induced corrosion (MIC) 7:00 – Hydrogen sulfide becomes sulfuric acid due to microbial induced corrosion within wastewater systems 9:22 – Assets constructed of concrete within a wastewater treatment plant 10:01 – The Clean Water Act and MIC 10:25 – Factors that make a coating suitable for wastewater collection systems 10:58 – Unintended consequences associated with regulations 12:54 – Preliminary wastewater treatment systems and considerations for coating systems 15:05 – Primary wastewater treatment systems and considerations for coating systems 16:54 – The aggressive environment found in wastewater treatment systems 18:00 – Testing protocol outlined in SSPC Technology Guide 27 to identify coating systems for concrete in wastewater treatment 20:10 – ASTM G210 - Standard Practice for Operating the Severe Wastewater Analysis Testing Apparatus https://www.astm.org/Standards/G210.htm 21:30 – Wrap up Subscribe via iTunes, Google Play, or Spotify. Find out more at https://carboline-tech-service-podcast.pinecast.co

Cow farts aren't the problem, says professor Frank Mitloehner, UC-Davis air quality specialist in the Department of Animal Sciences, who dispels three myths about cows and the environment.

Cow farts aren't the problem, says professor Frank Mitloehner, UC-Davis air quality specialist in the Department of Animal Sciences, who dispels three myths about cows and the environment.

Cow farts aren't the problem, says professor Frank Mitloehner, UC-Davis air quality specialist in the Department of Animal Sciences, who dispels three myths about cows and the environment.

Cow farts aren't the problem, says professor Frank Mitloehner, UC-Davis air quality specialist in the Department of Animal Sciences, who dispels three myths about cows and the environment.

What's in the FF-FG-Green programme for government, how is it going down with the grassroots, and what about that Irish Times / Ipsos-MRBI poll? Discussing it all are Pat, Fiach and Jen with host Hugh Linehan.

Supplements that may increase deep sleep. So, deep sleep is, primarily what's going on in deep sleep is that all of your biogenic amines, which are most of the neurotransmitters that you make from protein with the possible except — like depending on how you classify it, you could say ultimately you make melatonin from protein, but it's not a biogenic amine. Biogenic amines, which are the catecholamines — all are basically shut off. They're probably not zero, zero, but they're almost zero during sleep. Acetylcholine is also shut down during deep sleep, but it pops up during REM sleep. I really don't think this is a supplement issue.  First of all, you definitely don't want to be taking anything that has acetylcholinesterase inhibitors at night.  Non-organic foods have pesticides that are acetylcholinesterase inhibitors. I don't know if that's relevant here dose-wise. Things that improve cognitive function are often acetylcholinesterase inhibitors. So, gingko biloba is one. I wouldn't take that at night. There are drugs that treat neurological problems, especially Alzheimer's, that are acetylcholinesterase inhibitors; I wouldn't take those at night.  I'm on the fence about whether you should take choline at night. I think it's most likely fine to eat eggs at night. If you're taking something like alpha-GPC; I'm not sure. You might want to avoid that at night if you find, particularly if you find that when you're tracking your sleep with an Oura ring your REM is higher than normal and your deep sleep is lower than normal.  But other than that — I would say that methylation support is very important to help lower some of the important biogenic amines. Histamine, for example, is primarily gotten rid of with methylation in the brain and if your histamine levels are high during the day, it might cause anxiety during the night and that could interfere with your deep sleep. Electrolytes are also super important. Calcium, magnesium, salt and potassium. All these things you need to get straight in order for your sleep cycle to be working right. If your cortisol is high at night or other factors of anxiety are high at night you might want a targeted supplement there, like phosphatidylserine — the evidence is conflicting, but has been used to lower the stress response.  I don't think it's a blanket answer to that question. I think it's like figuring out what's the cause of the low deep sleep and working from there.   This Q&A can also be found as part of a much longer episode, here:https://chrismasterjohnphd.com/podcast/2019/02/09/ask-anything-nutrition-feb-1-2019/    If you would like to be part of the next live Ask Me Anything About Nutrition, sign up for the CMJ Masterpass, which includes access to these live Zoom sessions, premium features on all my content, and hundreds of dollars of exclusive discounts. You can sign up with a 10% lifetime discount here: https://chrismasterjohnphd.com/q&a

So, deep sleep is, primarily what's going on in deep sleep is that all of your biogenic amines, which are most of the neurotransmitters that you make from protein with the possible except — like depending on how you classify it, you could say ultimately you make melatonin from protein, but it's not a biogenic amine. Biogenic amines, which are the catecholamines — all are basically shut off. They're probably not zero, zero, but they're almost zero during sleep. Acetylcholine is also shut down during deep sleep, but it pops up during REM sleep. I really don't think this is a supplement issue.  First of all, you definitely don't want to be taking anything that has acetylcholinesterase inhibitors at night.  Non-organic foods have pesticides that are acetylcholinesterase inhibitors. I don't know if that's relevant here dose-wise. Things that improve cognitive function are often acetylcholinesterase inhibitors. So, gingko biloba is one. I wouldn't take that at night. There are drugs that treat neurological problems, especially Alzheimer's, that are acetylcholinesterase inhibitors; I wouldn't take those at night.  I'm on the fence about whether you should take choline at night. I think it's most likely fine to eat eggs at night. If you're taking something like alpha-GPC; I'm not sure. You might want to avoid that at night if you find, particularly if you find that when you're tracking your sleep with an Oura ring your REM is higher than normal and your deep sleep is lower than normal.  But other than that — I would say that methylation support is very important to help lower some of the important biogenic amines. Histamine, for example, is primarily gotten rid of with methylation in the brain and if your histamine levels are high during the day, it might cause anxiety during the night and that could interfere with your deep sleep. Electrolytes are also super important. Calcium, magnesium, salt and potassium. All these things you need to get straight in order for your sleep cycle to be working right. If your cortisol is high at night or other factors of anxiety are high at night you might want a targeted supplement there, like phosphatidylserine — the evidence is conflicting, but has been used to lower the stress response.  I don't think it's a blanket answer to that question. I think it's like figuring out what's the cause of the low deep sleep and working from there.

Chris Masterjohn PhD knows more about neurotransmitters than anyone I've ever met. And in this episode, you'll find out exactly what I mean. Chris is offering all listeners of the OPP 20% off his Testing Nurtitional Status - The Ultimate Cheat Sheet - A massively powerful tool for understanding your own nutritional needs.  Testing Nurtitional Status - The Ultimate Cheat Sheet  Link - https://chrismasterjohnphd.com/sean PROMO CODE: SEAN In this episode we cover: •The best foods for neurotransmitter support •Which nutrients are most critical to a healthy brain •The importance of testing nutritional approaches for optimal results. • A comprehensive breakdown for understanding key neurotransmitters. • Serotonin not a feel good chemical, but a stress coping chemical • 3 grams of glycine before bed to lower core temp and  get to sleep faster and get deeper sleep • Biogenic amines • Dopamine • Acetylcholine • Gaba • Glutamate • Glycine - eating nose to tail, • Keto as a fasting-mimicking diet • Choline for sustained focus • The role of histamines • Testing nutritional status  - cheat sheet A system for managing nutritional status.  • B1,2,3,5, Niacin, ATP and Magnesium, Iron, Copper, Sulfer, Sodium, Glycine, • The role of endocannabinoids in learning at the edge of our comfort zone • Supporting the process of methylation with a 23 and me test to determine how much choline you need • Vitamins and minerals cheat sheet To stay up to date and in the loop with Chris Masterjohn via facebook. Click Below  

Dr. Matilde Parente joins us for a fun - but serious - discussion on wine and Health. From headaches and hangovers, science and sulfites, to biogenic amines and everything in between. How to distill conflicting headlines? How much should we really be drinking? We address all this and more. This could quite possibly change the way you drink. You're welcome.  Photos, links & more at winetwofive.com     Wine, Health, Spirits, Congeners, Biogenic Amines, Hangovers, Headaches, Natural Wine, Ask the Doc, Matilde Parente MD, Wine Education [ad]

In this podcast I'll be exploring Food Sensitivities: I’ll explain the difference between food allergies, food intolerances, and food sensitivities I’ll talk about the many many health issues associated with food sensitivities Finally, I’ll share 5 ways you can identify foods your body is most sensitive to CLICK HERE TO LEARN WHAT ARE THE BEST FOODS TO GET YOU LEAN Most people have heard about food allergies, like a peanut allergy and food intolerances, like lactose intolerance. But not many people know about food sensitivities. Let me explain the difference between the three of these. Now a food allergy is a dramatic and immediate reaction by your body’s immune system to a particular food that you’ve eaten. Allergic reactions include immediate swelling and itchiness and also anaphylactic shock which can be fatal. The top eight allergenic foods are: Peanuts Tree nuts Wheat Shellfish Soy Milk Eggs and Fish   Food intolerance on the other hand is a more subtle, minor delayed reaction. We’re talking a few minutes to a few hours here before you experience symptoms. Food intolerances do not involve your immune system and are actually caused by your body not having the right enzymes or not having enough enzyme activity to breakdown the compounds that are in real food or in the chemicals added to fake pretend food-like products. Common food substances that people are intolerant to and do not have the enzymes to fully breakdown include: Gluten in grains Lactose in dairy Biogenic amines like histamine, tyramine, and arginine Preservatives and Additives   Alright food sensitivities. Now food sensitivities are similar to intolerances in that they provoke a small delayed reaction in your body. When I say delayed I mean delayed. Reaction times to a food your body is sensitive to can vary from hours to weeks.  Food sensitivities are similar to allergies in that your immune system is the cause for the reaction, but a different branch of your immune system, which is why instead of an immediate allergic reaction you get a delayed smaller reaction. So a food sensitivity is your body’s immune system having a reaction to the food you eat or the compounds added to or found on the food you eat and these immune reactions are small and can take a while to show up as a visible and noticeable symptom. Common foods and substances found in food that people are most sensitive to include what I mentioned earlier for allergies and intolerances, but also the following: Sugar and sugar alcohols Industrial seed oils more commonly known as vegetable oils Corn Legumes Seeds Grains whether they contain gluten or not Artificial sweeteners Alcohol Caffeine Cacao Nightshade vegetables Citrus fruits Agricultural chemical sprays Genetically modified organisms and Mould toxins like aflatoxin and ochratoxin most commonly found in peanuts and instant coffee   As you can see when you add up all three food categories together that makes quite the list of food and food compounds that can cause food sensitivities. Keep in mind that these foods and compounds are the most common sensitivities found in people who are experiencing health issues, but you can actually be sensitive to any food. No food is off-limits when it comes to causing negative reactions in your body. Whether it’s seaweed, beef, pork, broccoli, or even beautifully roasted sweet potatoes, food sensitivities can occur with any food. Let me list (yes another list) the many health issues and symptoms that a food sensitivity can cause: Brain fog Inability to focus Food cravings Low energy Irritability Fatigue Insomnia Headaches Mood swings

Cancer is a leading cause of death worldwide. Although several common treatment options exist, there is an urgent need for improved tumor therapeutics. Therefore, we evaluated three innovative anticancer approaches in vivo. These were newly synthesized siRNA polyplexes, novel myxobacterial anticancer compounds, and innovative polymeric melphalan formulations. We evaluated the in vivo characteristics of polymeric bound siRNA. We could demonstrate that the polymer FolA-PEG24-K(Stp4-C)2 is an efficient carrier for targeting siRNA to the folate receptor expressing tumor tissue of mice. Moreover, the siRNA was able to enter tumor cells and led to specific gene silencing. After systemic injection, the polyplexes did neither cause any toxic side effects nor accumulate in any healthy organ. With only 6 nm average diameter, polyplexes were very small, resulting in fast removal from blood circulation by renal clearance. Addition of larger PEG spacers to the initial polyplex led to an increased polyplex size. As a result, the renal clearance was decreased, and polyplex distribution in the body was optimized. These results show that the in vivo hurdles of siRNA delivery can be overcome by binding siRNA to the precise and multifunctional polymers. Natural compounds have broad therapeutic effects, and are basis for the production of various anticancer drugs. Myxobacterial products often target cell structures which are rarely targeted by other metabolites, and they exert novel modes of action. Therefore, they are of particular importance for the development of new anticancer drugs. In this thesis, we evaluated three novel myxobacterial compounds in vivo. Within our experimental settings, we could demonstrate for the first time that archazolid, pretubulysin and chondramide can impair the migration and colonization of breast cancer cells in mice. Concerning their impact on tumor growth reduction, the compounds have promising characteristics, but the experimental setups need further improvement. Cytostatic drugs, like melphalan play an important role in cancer therapy, but bear problems, such as a low therapeutic efficacy and strong toxic side effects. Immobilization of chemotherapeutics on polymers is an interesting option to reduce their toxicity and enhance their efficacy, mainly by passive tumor targeting. We evaluated three innovative polymer-melphalan formulations in cell viability and proliferation assays. The covalent conjugate of poly(oxyethylene H-phosphonate) with melphalan was additionally investigated in vivo. This polymeric immobilization of melphalan led to an improved therapeutic effect compared to the pure cytostatic drug, as the growth and regrowth of HuH7 tumors could be hampered effectively. In conclusion, this thesis deals with the in vivo evaluation of innovative cancer therapeutics, which were successfully investigated in murine tumor models. The results with the experimental agents, based on siRNA, polymers or biogenic drugs, are encouraging starting points for further anticancer research.

Fri, 28 Oct 2011 13:17:

Magnetite is a widespread accessory mineral in rocks and soils. As was first shown by Lowenstam (1962), magnetite frequently forms also by biochemical processes, with varying degrees of control of the organisms over the mineralization process. Lowenstam distinguishes between biologically induced (BIM) and biologically controlled mineralization(BCM). The former refers to processes with no biological control, and the later to processes with strict metabolic and genetic control. In this thesis, two examples of biogenic magnetite with eminently different magnetic properties are studied. One is magnetite as found in so-called magnetotactic bacteria; the second example is magnetite as identi¯ed in tissue of pigeon's heads. In the first part of this work, the results of a series of rock magnetic measurements on concentrated samples of pure magnetotactic bacteria will be presented. These bacteria offer a unique opportunity to study the process of biologically controlled mineralization, since these organisms synthesize intracellular particles of magnetite or greigite arranged in chains, that give the bacterium the characteristic property of a swimming compass needle. The magnetic crystals, so-called magnetosomes, are magnetically speaking stable single-domain particles, characterized by a size such that the particles have minimum induced magnetization and maximum permanent magnetic moment (i.e. particle size between 30 and 130 nm). The bacteria studied here have been harvested in sediments from lake Chiemsee. They were extracted from the sediments and concentrated to an extent that enabled a detailed characterization by macroscopic magnetic measurements. The so-called Bacteriodrome was used to concentrate samples of approximately 10E7 cells. Different magnetic criteria, aiming to specifically identify bacterial magnetite in sediments, have been tested, including: (1) acquisition and demagnetization of isothermal remanent magnetization (IRM); (2) acquisition of anhysteretic remanent magnetization and (3) thermal dependence of low temperature saturation IRM, after cooling in zero field (ZFC) or in a 2.5 T field (FC) from 300 to 5 K. The best method turns out to be the so-called delta-delta test (dFC/dZFC), first proposed by Moskowitz et al. (1993), and based on the low temperature variation of the SIRM, measured both in a strong field (FC) and in zero field (ZFC). At the Verwey transition (ca. 120 K) the d-value for each curve is determined and the d-ratio (dFC/dZFC) calculated. Values exceeding 2, are indicators for the presence of chains of stable single-domain particles, which form only under strict biological control. However, it is shown that the suitability of rock magnetic techniques to detect and characterize biogenic magnetite in bulk, natural samples such as lake sediments is still limited, due to diagenetic processes and the occurrence of other non-biogenic magnetic minerals, which blur the distinct magnetic properties of the former. The only certain proof for bacterial magnetite is the optical identification -although time consuming and tedious- by Transmission Electron Microscopy. The magnetite inclusions found in pigeon tissue are very different in their magnetic properties with respect to bacterial magnetite. With their small grain size (between 2 and 10 nm), these particles fall within the superparamagnetic size range and are characterized by a large induced magnetization and no permanent magnetic moment. The pigeon magnetite is concentrated in spherical clusters of approximately 1-3 micrometers in diameter. The response of these clusters to magnetic fields has been simulated by spherules of ferrofluid. Depending on their geometrical arrangement these spherules show peculiar magnetic properties. Based on these properties, three models have been developed experimentally and theoretically with respect to a possible application as biological sensory elements. The magnetic properties of the sensory models are tested in the light of behavioral experiments conducted in the past on homing pigeons and migratory birds. In these experiments, the birds were exposed to defined magnetic fields to specifically affect a magnetite-based magnetoreceptor. As will be seen, most of the responses of the birds observed in the behavioral experiments can be explained by simulating the effects of these magnetic treatment on ferrofluid spherules.

Fri, 1 Jan 1988 12:00:00 +0100 https://epub.ub.uni-muenchen.de/6909/1/6909.pdf Eisenmenger, Wolfgang; Gilg, T.; Zucker, T.; Kauert, G.