Species distribution and <Emphasis Type="Italic">in vitro</Emphasis> antifungal susceptibility of oral yeast isolates from Tanzanian HIV-infected patients with primary and recurrent oropharyngeal candidiasis

Background  

In Tanzania, little is known on the species distribution and antifungal susceptibility profiles of yeast isolates from HIV-infected patients with primary and recurrent oropharyngeal candidiasis.     

Maternal brooding in the children’s python <Emphasis Type="Italic">(Antaresia childreni)</Emphasis> promotes egg water balance

Parental care provides considerable benefits to offspring and is widespread among animals, yet it is relatively uncommon among squamate reptiles (e.g., lizards and snakes). However, all pythonine snakes show extended maternal egg brooding with some species being facultatively endothermic. While facultative endothermy provides thermal benefits, the presence of brooding in non-endothermic species suggests other potential benefits of brooding. In this study we experimentally tested the functional significance of maternal brooding relative to water balance in the children’s python, Antaresia childreni, a small species that does not exhibit facultative endothermy. Clutch evaporative water loss (EWL) was positively correlated with clutch mass and was much lower than expected values based on individual eggs. The conglomerate clutch behaved as a single unit with a decreasing surface area to volume ratio as clutch size increased. Maternal brooding had a dramatic impact on evaporation from eggs, reducing and possibly eliminating clutch EWL. In a separate experiment, we found that viability of unattended eggs is highly affected by humidity level, even in the narrow range from 75 to 100% relative humidity at 30.5°C (20–33 mg m⁻³ absolute humidity). However, the presence of the brooding female ameliorated this sensitivity, as viability of brooded clutches at 75% relative humidity was higher than that of non-brooded eggs at either the same absolute humidity or at near-saturated conditions. Overall, these results demonstrate that brooding behavior strongly promotes egg water balance (and thus egg viability) in children’s pythons.     

Utilization of Sialylated Glycans as Coreceptors Enhances the Neurovirulence of Serotype 3 Reovirus

Mammalian reoviruses display serotype-specific patterns of tropism and disease in the murine central nervous system (CNS) attributable to polymorphisms in viral attachment protein σ1. While all reovirus serotypes use junctional adhesion molecule-A as a cellular receptor, they differ in their utilization of carbohydrate coreceptors. This observation raises the possibility that carbohydrate binding by σ1 influences reovirus pathology in the CNS. In this study, we sought to define the function of carbohydrate binding in reovirus neuropathogenesis. Newborn mice were inoculated intramuscularly with wild-type strain type 3 Dearing (T3D) and T3D-σ1R202W, a point mutant T3D derivative that does not bind sialic acid (SA). Infected mice were monitored for survival, and viral loads at the sites of primary and secondary replication were quantified. Fewer mice inoculated with the wild-type virus survived in comparison to those inoculated with the mutant virus. The wild-type virus also produced higher titers in the spinal cord and brain at late times postinoculation but lower titers in the liver in comparison to those produced by the mutant virus. In addition, the wild-type virus was more virulent and produced higher titers in the brain than the mutant following intracranial inoculation. These animal infectivity studies suggest that T3D-σ1R202W harbors a defect in neural growth. Concordantly, compared with the wild-type virus, the mutant virus displayed a decreased capacity to infect and replicate in primary cultures of cortical neurons, a property dependent on cell surface SA. These results suggest that SA binding enhances the kinetics of reovirus replication in neural tissues and highlight a functional role for sialylated glycans as reovirus coreceptors in the CNS.     

18S rRNA data indicate that Aschelminthes are polyphyletic in origin and consist of at least three distinct clades

The Aschelminthes is a collection of at least eight animal phyla, historically grouped together because the absence of a true body cavity was perceived as a pseudocoelom. Analyses of 18S rRNA sequences from six Aschelminth phyla (including four previously unpublished sequences) support polyphyly for the Aschelminthes. At least three distinct groups of Aschelminthes were detected: the Priapulida among the protostomes, the Rotifera-Acanthocephala as a sister group to the protostomes, and the Nematoda as a basal group to the triploblastic Eumetazoa.      

Interspecific and intraspecific comparisons of the period locus in the Drosophila willistoni sibling species

The period (per) locus has received much attention in molecular evolution studies because it is one of the best studied "behavioral genes" and because it offers insight into the evolution of repetitive sequences. We studied most of the coding region of per in Drosophila willistoni and confirmed previously observed patterns of conservation and divergence among distantly related species. Five regions are so highly diverged that they cannot be aligned, whereas a region encompassing the PAS domain is very conserved. Structural and nucleotide polymorphism patterns in the willistoni group are not the same as those observed in previously studied species. We sequenced the region homologous to the highly polymorphic threonine-glycine repeat of D. melanogaster in multiple strains of D. willistoni, as well as in other members of willistoni group, and found an unusual amount of conservation in this region. However, the next nonconserved region downstream in the sequence is quite variable and polymorphic for the number of repeated glycines. The glycine codon usage is significantly different in this glycine repeat as compared to other parts of the gene. We were able to plot the directionality of change in the glycine repeat region onto a phylogeny and find that the addition of glycines is the general trend with the diversification of the willistoni group.      

Single cell studies of the cell cycle and some models

Analysis of growth and division often involves measurements made on cell populations, which tend to average data. The value of single cell analysis needs to be appreciated, and models based on findings from single cells should be taken into greater consideration in our understanding of the way in which cell size and division are co-ordinated. Examples are given of some single cell analyses in mammalian cells, yeast and other microorganisms. There is also a short discussion on how far the results are in accord with simple models.