Toxo XV: A Congress at the Birthplace of Toxoplasma.

In this TrendsTalk article, the organizers of the 15th International Congress on Toxoplasma Biology and Toxoplasmosis, Professors Jorge Gomez Marin and Alejandra de-la-Torre, bring the highlights of this event and the key outcome from the inaugural workshop on the environmental transmission of Toxoplasma gondii organized by Doctors Aurélien Dumètre and Karen Shapiro

Proteomic Analysis of Fractionated Toxoplasma Oocysts Reveals Clues to Their Environmental Resistance

Toxoplasma gondii is an obligate intracellular parasite that is unique in its ability to infect a broad range of birds and mammals, including humans, leading to an extremely high worldwide prevalence and distribution. This work focuses on the environmentally resistant oocyst, which is the product of sexual replication in felids and an important source of human infection. Due to the difficulty in producing and working with oocysts, relatively little is known about how this stage is able to resist extreme environmental stresses and how they initiate a new infection, once ingested. To fill this gap, the proteome of the wall and sporocyst/sporozoite fractions of mature, sporulated oocysts were characterized using one-dimensional gel electrophoresis followed by LC-MS/MS on trypsin-digested peptides. A combined total of 1021 non-redundant T. gondii proteins were identified in the sporocyst/sporozoite fraction and 226 were identified in the oocyst wall fraction. Significantly, 172 of the identified proteins have not previously been identified in Toxoplasma proteomic studies. Among these are several of interest for their likely role in conferring environmental resistance including a family of small, tyrosine-rich proteins present in the oocyst wall fractions and late embryogenesis abundant domain-containing (LEA) proteins in the cytosolic fractions. The latter are known from other systems to be key to enabling survival against desiccation

Transcriptomic Analysis of Toxoplasma Development Reveals Many Novel Functions and Structures Specific to Sporozoites and Oocysts

Sexual reproduction of Toxoplasma gondii occurs exclusively within enterocytes of the definitive felid host. The resulting immature oocysts are excreted into the environment during defecation, where in the days following, they undergo a complex developmental process. Within each oocyst, this culminates in the generation of two sporocysts, each containing 4 sporozoites. A single felid host is capable of shedding millions of oocysts, which can survive for years in the environment, are resistant to most methods of microbial inactivation during water-treatment and are capable of producing infection in warm-blooded hosts at doses as low as 1–10 ingested oocysts. Despite its extremely interesting developmental biology and crucial role in initiating an infection, almost nothing is known about the oocyst stage beyond morphological descriptions. Here, we present a complete transcriptomic analysis of the oocyst from beginning to end of its development. In addition, and to identify genes whose expression is unique to this developmental form, we compared the transcriptomes of developing oocysts with those of in vitro-derived tachyzoites and in vivo-derived bradyzoites. Our results reveal many genes whose expression is specifically up- or down-regulated in different developmental stages, including many genes that are likely critical to oocyst development, wall formation, resistance to environmental destruction and sporozoite infectivity. Of special note is the up-regulation of genes that appear “off” in tachyzoites and bradyzoites but that encode homologues of proteins known to serve key functions in those asexual stages, including a novel pairing of sporozoite-specific paralogues of AMA1 and RON2, two proteins that have recently been shown to form a crucial bridge during tachyzoite invasion of host cells. This work provides the first in-depth insight into the development and functioning of one of the most important but least studied stages in the Toxoplasma life cycle

Les envenimations à l'île de la Réunion

AIX-MARSEILLE2-BU Pharmacie (130552105) / SudocSudocFranceF

Les pathologies estivales (conseils à l'officine)

AIX-MARSEILLE2-BU Pharmacie (130552105) / SudocSudocFranceF

Les remèdes de grand-mères sont-ils toujours d'actualité?

AIX-MARSEILLE2-BU Pharmacie (130552105) / SudocSudocFranceF

Ctenocephalides felis (de la biologie aux traitements)

AIX-MARSEILLE2-BU Pharmacie (130552105) / SudocSudocFranceF

Manifestations ophtalmologiques de la toxoplasmose (suivi d'une cohorte de 130 enfants atteints de toxoplasmose congénitale)

AIX-MARSEILLE2-BU Pharmacie (130552105) / SudocSudocFranceF