New Role for Cdc14 Phosphatase: Localization to Basal Bodies in the Oomycete Phytophthora and Its Evolutionary Coinheritance with Eukaryotic Flagella

Cdc14 protein phosphatases are well known for regulating the eukaryotic cell cycle, particularly during mitosis. Here we reveal a distinctly new role for Cdc14 based on studies of the microbial eukaryote Phytophthora infestans, the Irish potato famine agent. While Cdc14 is transcribed constitutively in yeast and animal cells, the P. infestans ortholog is expressed exclusively in spore stages of the life cycle and not in vegetative hyphae where the bulk of mitosis takes place. PiCdc14 expression is first detected in nuclei at sporulation, and during zoospore formation the protein accumulates at the basal body, which is the site from which flagella develop. The association of PiCdc14 with basal bodies was supported by co-localization studies with the DIP13 basal body protein and flagellar β-tubulin, and by demonstrating the enrichment of PiCdc14 in purified flagella-basal body complexes. Overexpressing PiCdc14 did not cause defects in growth or mitosis in hyphae, but interfered with cytoplasmic partitioning during zoosporogenesis. This cytokinetic defect might relate to its ability to bind microtubules, which was shown using an in vitro cosedimentation assay. The use of gene silencing to reveal the precise function of PiCdc14 in flagella is not possible since we showed previously that silencing prevents the formation of the precursor stage, sporangia. Nevertheless, the association of Cdc14 with flagella and basal bodies is consistent with their phylogenetic distribution in eukaryotes, as species that lack the ability to produce flagella generally also lack Cdc14. An ancestral role of Cdc14 in the flagellar stage of eukaryotes is thereby proposed

Role of B-cell receptors for B-cell development and antigen-induced differentiation

B-cell development is characterized by a number of tightly regulated selection processes. Signals through the B-cell receptor (BCR) guide and are required for B-cell maturation, survival, and fate decision. Here, we review the role of the BCR during B-cell development, leading to the emergence of B1, marginal zone, and peripheral follicular B cells. Furthermore, we discuss BCR-derived signals on activated B cells that lead to germinal center and plasma cell differentiation

Strategy as Discourse

From Crossref via Jisc Publications Router

A phylogenetic interpretation of nematode vulval variations

Over the last few years vulva development in nematodes has been used as a model system to study the evolution of developmental processes by carrying out cell lineage and cell ablation studies in various nematodes. Furthermore, a genetic and molecular analysis of vulva development has been initiated in Pristionchus pacificus. Evolutionary interpretation of these comparative developmental studies requires a phylogenetic understanding of nematodes. Recently, a molecular phylogeny for the phylum Nematoda has been published. Here, we place the comparative data of vulva development onto this phylogeny of nematodes to infer the direction of evolutionary change

DISC-mediated activation of caspase-2 in DNA damage-induced apoptosis

The tumor suppressor p53 protein supports growth arrest and is able to induce apoptosis, a signaling cascade regulated by sequential activation of caspases. Mechanisms that lead from p53 to activation of individual initiator caspases are still unclear. The present model for caspase-2 activation includes PIDDosome complex formation. However, in certain experimental models, elimination of complex constituents PIDD or RAIDD did not significantly influence caspase-2 activation, suggesting the existence of an alternative activation platform for caspase-2. Here we have investigated the link between p53 and caspase-2 in further detail and report that the latter is able to utilize the CD95 DISC as an activation platform. The recruitment of caspase-8 to this complex is required for activation of caspase-2. In the experimental system used, the DISC is formed through a distinct, p53-dependent upregulation of CD95. Moreover, we show that caspase-2 and -8 cleave Bid, and that both act simultaneously upstream of mitochondrial cytochrome c release. Finally, a direct interaction between the two caspases and the ability of caspase-8 to cleave caspase-2 are demonstrated. Thus, the observed functional link between caspase-8 and -2 within the DISC represents an alternative mechanism to the PIDDosome for caspase-2 activation in response to DNA damag

Cytokine mRNA expression and iron status in children living in a malaria endemic area.

Iron deficiency has been reported to affect both malaria pathogenesis and cell-mediated immune responses; however, it is unclear whether the protection afforded by iron deficiency is mediated through direct effects on the parasite, through immune effector functions or through both. We have determined cytokine mRNA expression levels in 59 children living in a malaria endemic area on the coast of Kenya who we selected on the basis of their biochemical iron status. Real-time quantitative reverse transcriptase polymerase chain reaction analysis of cytokine mRNA levels of peripheral blood mononuclear cells (PBMC) obtained from these children showed an association between interleukin-4 (IL-4) mRNA levels and all the biochemical indices of iron that we measured. Furthermore, IL-10 mRNA was higher in parasite blood smear-positive children than in blood smear-negative children irrespective of their iron status. This study suggests that IL-4 expression by PBMC may be affected by iron status

Pristionchus pacificus: a satellite organism in evolutionary developmental biology

Pristionchus pacificus has been described as a satellite organism, for functional comparative studies with Caenorhabditis elegans. Like C. elegans, P. pacificus is also easily cultured in the laboratory on a lawn of E. coli bacteria. P. pacificus is a hermaphroditic species with a 4-day life cycle, but unlike most nematodes which pass through four juvenile stages during their development, P. pacificus has only three juvenile stages. The combination of genetic, molecular and cell-biological studies have made P. pacificus a model system in the new field of evolutionary developmental biology. One process that has been studied in detail is the development of the vulva. Genetic and molecular studies revealed that the function of several genes involved in vulva development differs between P. pacificus and C. elegans. Here, we review our genetic and molecular studies of P. pacificus. We show that P. pacificus is well-suited as a satellite organism not only for understanding the cellular and genetic aspects of evolutionary change, but also for addressing questions of molecular evolution at the genomic level. Pristionchus pacificus wurde vor mehrerern Jahren als “Satelitten-Organism” für funktionelle-vergleichende Studien mit dem Modellorganismus C. elegans beschrieben. P. pacificus ist eine hermaphroditische Art mit einer Generationszeit von 4 Tagen und kann auf E. coli gezüchtet werden. Die Analyse des Lebenszyklus hat gezeigt dass diese Art im Gegensatz zu den meisten Nematoden nur drei Juvenilstadien durchläuft. Da in P. pacificus genetische, molekular-biologische und zelluläre Methoden in ähnlicher Weise zum Einsatz kommen können wie in C. elegans, ist diese Art ein ideales Modellsystem für evolutionäre entwicklungsbiologische Fragestellungen. Ein besonders detailliert analysierter Entwicklungsprozess ist die Bildung der Vulva. Genetische und molekulare Arbeiten haben gezeigt dass einige in beiden Arten an der Vulva-Bildung beteiligte homologen Gene, sich in ihrer detaillierten Funktion deutlich voneinander unterscheiden. Die vorliegende Arbeit gibt einen Überblick über die genetischen und molekularen Aspekte der Vulva-Entwicklung in P. pacificus und zeigt die Potenzen der Art auch für zukünftige molekulare und genomische Untersuchungen