Lineage-specific proteins essential for endocytosis in trypanosomes

Clathrin-mediated endocytosis (CME) is the most evolutionarily ancient endocytic mechanism known, and in many lineages the sole mechanism for internalisation. Significantly, in mammalian cells CME is responsible for the vast bulk of endocytic flux and has likely undergone multiple adaptations to accommodate specific requirements by individual species. In African trypanosomes, we previously demonstrated that CME is independent of the AP-2 adaptor protein complex, that orthologues to many of the animal and fungal CME protein cohort are absent, and that a novel, trypanosome-restricted protein cohort interacts with clathrin and drives CME. Here, we used a novel cryomilling affinity isolation strategy to preserve transient low-affinity interactions, giving the most comprehensive trypanosome clathrin interactome to date. We identified the trypanosome AP-1 complex, Trypanosoma brucei (Tb)EpsinR, several endosomal SNAREs plus orthologues of SMAP and the AP-2 associated kinase AAK1 as interacting with clathrin. Novel lineage-specific proteins were identified, which we designate TbCAP80 and TbCAP141. Their depletion produced extensive defects in endocytosis and endomembrane system organisation, revealing a novel molecular pathway subtending an early-branching and highly divergent form of CME, which is conserved and likely functionally important across the kinetoplastid parasites

Trypanosomatid protein phosphatases

Classification of kinetoplastid serine/threonine specific and protein tyrosine phosphatases based on sequence similarity. The groups absent from kinetoplastids are in white boxes. In spite of well-described kinetoplastid phosphatomes, few kinetoplastid protein phosphatases have been characterized and studied in vivo

Geochronologic and Paleoclimatic Characterization of Quaternary Sediments in the Great Hungarian Plan

From the 14th International Radiocarbon Conference held in Tucson, AZ, May 20-24, 1991.We reconstructed the climate of the Great Hungarian Plain between the years, 7-32 ka BP using a malacothermometer method. The reconstruction is based on seven Gastropoda taxa, for which optimal temperature and tolerance ranges have been determined. The temporal scales of the malacofaunal levels were calibrated with radiocarbon data. We compared our paleotemperature values with the temperature values of existing climatic curves and found the same climatic periods.This material was digitized as part of a cooperative project between Radiocarbon and the University of Arizona Libraries.The Radiocarbon archives are made available by Radiocarbon and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform February 202

Peroxisomes in parasitic protists

Representatives of all major lineages of eukaryotes contain peroxisomes with similar morphology and mode of biogenesis, indicating a monophyletic origin of the organelles within the common ancestor of all eukaryotes. Peroxisomes originated from the endoplasmic reticulum, but despite a common origin and shared morphological features, peroxisomes from different organisms show a remarkable diversity of enzyme content and the metabolic processes present can vary dependent on nutritional or developmental conditions. A common characteristic and probable evolutionary driver for the origin of the organelle is an involvement in lipid metabolism, notably H2O2-dependent fatty-acid oxidation. Subsequent evolution of the organelle in different lineages involved multiple acquisitions of metabolic processes—often involving retargeting enzymes from other cell compartments—and losses. Information about peroxisomes in protists is still scarce, but available evidence, including new bioinformatics data reported here, indicate striking diversity amongst free-living and parasitic protists from different phylogenetic supergroups. Peroxisomes in only some protists show major involvement in H2O2-dependent metabolism, as in peroxisomes of mammalian, plant and fungal cells. Compartmentalization of glycolytic and gluconeogenic enzymes inside peroxisomes is characteristic of kinetoplastids and diplonemids, where the organelles are hence called glycosomes, whereas several other excavate parasites (Giardia, Trichomonas) have lost peroxisomes. Amongst alveolates and amoebozoans patterns of peroxisome loss are more complicated. Often, a link is apparent between the niches occupied by the parasitic protists, nutrient availability, and the absence of the organelles or their presence with a specific enzymatic content. In trypanosomatids, essentiality of peroxisomes may be considered for use in anti-parasite drug discovery