Podcasts about apicomplexa

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2023.07.31.551351v1?rss=1 Authors: Hawkins, L. M., Wang, C., Chaput, D., Batra, M., Marsilia, C., Awshah, D., Suvorova, E. Abstract: Division of apicomplexan parasites differs drastically from the division of their host cells. A fraction of apicomplexans divides in the traditional binary mode, such as Toxoplasma gondii in asexual stages, whereas the vast majority instead divide in a multinuclear fashion. Such variety of replication modes and a dearth of conserved conventional regulators have hindered the progress of apicomplexan cell cycle studies. We previously identified five Cdk-related kinases (Crk) involved in endodyogenic division of T. gondii tachyzoites. The current study investigates the roles of a novel essential cell cycle kinase TgCrk4. We identified this kinase cyclin partner and demonstrated that TgCrk4 regulates processes carried out during conventional G2 phase, such as repression of chromosome re-replication and centrosome re-duplication. Profiles of the G2 phase confirmed a cell cycle stop prior to the TgCrk6-regulated spindle assembly checkpoint. Accumulation of TgCyc4 in the nucleus and on the centrosomes, supported the role of TgCrk4-TgCyc4 complex as a coordinator of chromosome and centrosome cycles in T. gondii. Furthermore, we identified a previously missing DNA replication licensing factor TgCdt1 that was a dominant interactor of the TgCrk4-TgCyc4 complex. T. gondii Cdt1 is highly divergent, but preserved critical signature domains and appears to play a minimal or no role in licensing DNA replication in G1 phase. Functional analyses indicated the primary role of TgCdt1 is in controlling chromosome re-replication and centrosome re-duplication. Global phosphoproteome analyses identified immediate TgCrk4 substrates, such as DNA replication licensing factor TgORC4, gamma-tubulin nucleation factor TgGCP2, and the catalytic subunit of cell cycle phosphatase TgPP2ACA. Importantly, our phylogenetic and structural analyses established that the functional TgCrk4-TgCyc4 complex was encoded in the limited group of apicomplexans that employ binary cell division. Together with the minimal representation of binary division in Apicomplexa phylum, our findings support the novel view of apicomplexans acquiring binary division to repress ancestral multinuclear mechanisms. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Apicomplexa are evolutionarily distinct eukaryotes that play an important role in human diseases such as toxoplasmosis and malaria. So how do scientists study their unique biology? Dr. Sebastian Lourido explains that his lab uses Toxoplasma gondii as a model to study the phylum Apicomplexa. In part one of his talk, he explains the complex life cycle of T. gondii and he describes the unique organelles found in apicomplexa and used to facilitate invasion, survival and replication inside host cells. He highlights research from his lab demonstrating the importance of calcium signaling for T. gondii invasion.

Whitehead Member Sebastian Lourido studies a group of parasites called the Apicomplexa. These single-celled organisms are among the most common pathogens and are capable of causing devastating diseases in humans and animals, including toxoplasmosis, malaria, and infant diarrhea. Lourido’s laboratory is investigating in particular how the Apicomplexan Toxoplasma gondii  invades host cells and establishes its site of replication. The work … Continue reading Whitehead’s Sebastian Lourido on Toxoplasma, malaria parasites, and global health →

Daniel and Vincent solve the case of the Woman With Anal Area Discomfort, and discuss the multiple functions of a clathrin adapter protein in formation of rhoptry and microneme secretory organelles of Toxoplasma gondii. Hosts: Vincent Racaniello and Daniel Griffin Become a patron of TWiP. Links for this episode: Journal of Microbiology and Biology Education SciComm Issue (link) TWiP 19: Enterobius vermicularis, the pinworm Multiple roles of Toxoplasma gondii clathrin adaptor AP1 protein (PLoS Path) Image credit Letters read on TWiP 133 Case Study for TWiP 133 Seen while working in remote mountain makeshift mobile clinic in Dominican Republic, on Haitian border. Traveled 3 h by pickup truck, remote mountain town, womens centers. Set up makeshift mobile clinic in this center. Mother concerned about 6 yo girl, failure to thrive compared with sister, protuberant belly, frequent abdominal discomfort, going on over 1 year. No surgeries, no meds, first time ever seeing medical person. Mother and sister are family. Three children in family. Father does timber work. Very impoverished region, living in dirt floor home, drinking untreated water from local stream, go to bathroom outside, could be contamination. Diet: carbohydrate, plantains, rice, beans. On exam: lungs clear, heart fine, belly protuberant, liver and spleen not enlarged, some edema. Mother said noticed long motile worm in girls feces. Firm belly, not painful to her. Send your case diagnosis, questions and comments to twip@microbe.tv Music by Ronald Jenkees

Hemogregarines are protozoan blood parasites, belonging to the phylum Apicomplexa. They have a life cycle which includes two or three hosts. The merogony and gamogony takes place in the reptile host and the sporogony takes place in an invertebrate host. Therefore reptiles always represent intermediate hosts, while invertebrates act as definitive hosts. In reptiles, the genera Haemogregarina, Hepatozoon, Karyolysus and Hemolivia have been described including about 400 different species in reptiles. Most of the genera and species have been described based only on morphological characteristics and the reptilian host species. However, usefulness of these features for genus or species diagnosis is currently under debate. The parasite stages that are located in the erythrocytes of reptiles can, however, very often not be distinguished by their morphology. In the present study, therefore, a molecular biological approach was chosen to distinguish the hemogregarines from blood samples of reptiles, which were recently imported to Germany. Blood samples, which had been previously found to contain hemogregarines by microscopical investigation, were included in the investigation. As a target sequence the 18S rRNA gene was chosen. Using three different primer pairs HEMO1/HEMO2 (Perkins and Keller, 2001), HepF300/Hep900 (Ujvari et al., 2004) and A mod / 18AP1488.R (Medlin et al., 1988; Wozniak et al., 1994). PCR amplification was performed and phylogenetic analyses were based on the sequences obtained directly from the PCR amplification products. Blood samples from 13 ball pythons (Python regius), 23 emerald tree boas (Corallus caninus), seven African mud turtles (Pelusios castaneus) and one tokay gecko (Gekko gecko) were analysed. Three sequences from ball pythons, nine different sequences from emerald tree boas, and two sequences from African mud turtles could be obtained. Only one of these sequences was completely identical with one of the sequences available at the NCBI genbank originating from a Hepatozoon sp. from an elegant sand racer (Psammophis elegans). The remaining sequences thus seem to be first molecular description and characterisations of hemogregarines.In a phylogenetic tree the sequences obtained from the snakes clustered with Hepatozoon sp. but formed several separated groups indicating the existence of several species. The sequences obtained from parasites of the African mud turtles formed a sister clade to Haemogregarina sp. but were also close to species described as Hepatozoon sp. The formation of this clade was not supported by high bootstrap values. The taxonomic position thus seems to be unsolved. The present study shows that a variety of hemogregrine species have been introduced into Germany via imported reptiles. Using molecular methods most hemogregarines detected here were unequivocally characterized for the first time. Since the exact identification is fundamental for determination of pathogenicity of these hemogregarines in reptiles and for the development of a therapy, this study represents an important prerequisite for future investigations.

Hosts: Vincent Racaniello and Dickson Despommier Vincent and Dickson update the multistate outbreak of cyclosporiasis, discuss the avian malaria parasite P. lophurae, and review protection against malaria by intravenous immunization with a nonreplicating sporozoite vaccine. Links for this episode: Cyclosporiasis outbreak in US (CDC) Extraordinary history of REV (PLoS Biology) Avian malaria (Ann NY Acad Sci) P. lophurae (J Parasitol) TWiP infects TWiV (TWiV 248) Intravenous malaria vaccine (Science) Unconventional malaria vaccine (Science) Image of apicomplexan structure: Wikipedia Letters read on TWiP 59 Contact Send your questions and comments (email or mp3 file) to twip@twiv.tv Subscribe (free) Subscribe to TWiP (free) in iTunes, by the RSS feed or by email

Neospora caninum - a causal agent of abortion in cows The present study gives an overview of the current knowledge of N. caninum, particularly concerning the incidence of abortions in cattle populations infected by this parasite. In 1988 the Toxoplasma-like protozoon found in dogs was named N. caninum. In more than 40 countries N. caninum has been diagnosed since that time and about 17 different species were found to host infections by N. caninum. There are reports about 26 isolates. A different species, N. hughesi, was found to infect horses. Three different isolates of this species were described. There are conflicting reports about the exact phylogenetic classification of N. caninum. Especially the taxonomical relationship between Neospora, Toxoplasma and Hammondia is still being discussed controversely. It is generally accepted that N. caninum belongs to the phylum of Apicomplexa, the class of Sporozoa, the subclass of Coccidia, the order of Eucoccidia and the suborder of Eimeriina. During its life cycle N. caninum passes through various phases like sporogony, schizogony and gamogony. Definitive and intermediate hosts are needed for parasite`s development. To date not every detail of the parasite`s life has been investigated. Numerous investigations took place up until 1998 when it became obvious that the dog is a definitive host of N. caninum. Currently there is no evidence that other canids may also function as definitive hosts. It is difficult to distinguish oocysts of N. caninum from those of other eimerian species. N. caninum is transmitted either vertically from a cow to its fetus by tachyzoites or horizontally by ingesting oocysts, tachyzoites or bradyzoites. Reduced fertility and abortions are severe problems caused by neosporosis in cattle populations. Abortions can occur sporadically, endemically or epidemically. Concerning the season in which abortions take place a connection to climatic conditions favouring the survival of oocysts in the environment was suggested. But nevertheless N. caninum induced abortions can happen during the whole of the year. After the infection of a cow by N. caninum its first pregnancy probably results in abortion. During the following pregnancies the fetus of the same cow is likely to become infected, too, but abortion is unprobable. The resulting calf is infected chronically and also gives birth to infected offsprings. Only in exceptional circumstances may abortion occur again during the second or third pregnancy of the same cow. Sometimes stillbirths or malformations occur. The individual immune system of a cow chronically infected by N. caninum plays an important role for the transmission of the fetus and for the probability of abortion. Serological diagnoses of infections by N. caninum have to be confirmed by histopathological examinations to ensure that symptoms observed were really caused by this parasite. But former investigations demonstrate that the confirmation of diagnosis is difficult, especially if tissues dispatched are in bad condition. Immunological studies have been initiated to learn more about the parasitic activities of N. caninum and the host-parasite interaction. There is a chance to develop a vaccine to avoid the transplacental transmission of the parasite. The next step is the prevention of the horizontal infection. In general prevention from infection is of great importance in herds with infertility and abortions. Feeding with contaminated food and water should be avoided. Furthermore placentas potentially infected and stillborn calves should be removed. Affected herds should be examined serologically and histopathologically. Economic losses caused by infections by N. caninum result from reduced fertility, reduced milk production, lower average daily weight gain as well as from abortion. But up to now the severity of economical losses can not be quantified exactly, because aborted fetuses are not examined routinely. There is no zoonotic potential of N. caninum. Allthough it was possible to infect monkeys with a high dose of tachyzoites, there has been no natural infection seen up to now. And no indicate of N. caninum infections in aborted human fetuses were fou