Bax Inhibitor-1-mediated Ca leak is decreased by cytosolic acidosis

Bax Inhibitor-1 (BI-1) is an evolutionarily conserved six-transmembrane domain endoplasmic reticulum (ER)-localized protein that protects against ER stress-induced apoptotic cell death. This function is closely connected to its ability to lower steady-state ER Ca²⁺ levels. Recently, we elucidated BI-1's Ca²⁺-channel pore in the C-terminal part of the protein and identified the critical amino acids of its pore. Based on these insights, a Ca²⁺-channel pore-dead mutant BI-1 (BI-1^D213R) was developed. We determined whether BI-1 behaves as a bona fide H⁺/Ca²⁺ antiporter or as an ER Ca²⁺-leak channel by investigating the effect of pH on unidirectional Ca²⁺-efflux rates. At pH 6.8, wild-type BI-1 expression in BI-1^−/− cells increased the ER Ca²⁺-leak rate, correlating with its localization in the ER compartment. In contrast, BI-1^D231R expression in BI-1^−/−, despite its ER localization, did not increase the ER Ca²⁺-leak rate. However, at pH < 6.8, the BI-1-mediated ER Ca²⁺ leak was blocked. Finally, a peptide representing the Ca²⁺-channel pore of BI-1 promoting Ca²⁺ flux from the ER was used. Lowering the pH from 6.8 to 6.0 completely abolished the ability of the BI-1 peptide to mediate Ca²⁺ flux from the ER. We propose that this pH dependence is due to two aspartic acid residues critical for the function of the Ca²⁺-channel pore and located in the ER membrane-dipping domain, which facilitates the protonation of these residues.     

The genus Meira: phylogenetic placement and description of a new species

The genus Meira currently contains three recently described species of mite-associated basidiomycete yeasts from Israel and Japan and is placed in the Exobasidiomycetes (Ustilaginomycotina) Incertae sedis. A previously undescribed species of Meira was isolated from the phylloplane of a magnolia leaf in Louisiana, USA. Herein, we describe Meira miltonrushii sp. nov. and include phylogenetic analyses from three rDNA loci to resolve the placement of Meira. This study provides evidence that Meira belongs to the family Brachybasidiaceae in the Exobasidiales and supports the placement of another mite-associated yeast genus, Acaromyces, within Cryptobasidiaceae (Exobasidiales). We also examine sequences produced by numerous environmental studies that suggest Meira species can be found as endophytes of many plant species. To our knowledge, this is the first record of a member of the genus Meira in North America.     

GABA Shapes the Dynamics of Bistable Perception

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Massively Parallel Sequencing Reveals the Complex Structure of an Irradiated Human Chromosome on a Mouse Background in the Tc1 Model of Down Syndrome

Down syndrome (DS) is caused by trisomy of chromosome 21 (Hsa21) and presents a complex phenotype that arises from abnormal dosage of genes on this chromosome. However, the individual dosage-sensitive genes underlying each phenotype remain largely unknown. To help dissect genotype – phenotype correlations in this complex syndrome, the first fully transchromosomic mouse model, the Tc1 mouse, which carries a copy of human chromosome 21 was produced in 2005. The Tc1 strain is trisomic for the majority of genes that cause phenotypes associated with DS, and this freely available mouse strain has become used widely to study DS, the effects of gene dosage abnormalities, and the effect on the basic biology of cells when a mouse carries a freely segregating human chromosome. Tc1 mice were created by a process that included irradiation microcell-mediated chromosome transfer of Hsa21 into recipient mouse embryonic stem cells. Here, the combination of next generation sequencing, array-CGH and fluorescence in situ hybridization technologies has enabled us to identify unsuspected rearrangements of Hsa21 in this mouse model; revealing one deletion, six duplications and more than 25 de novo structural rearrangements. Our study is not only essential for informing functional studies of the Tc1 mouse but also (1) presents for the first time a detailed sequence analysis of the effects of gamma radiation on an entire human chromosome, which gives some mechanistic insight into the effects of radiation damage on DNA, and (2) overcomes specific technical difficulties of assaying a human chromosome on a mouse background where highly conserved sequences may confound the analysis. Sequence data generated in this study is deposited in the ENA database, Study Accession number: ERP000439.     

Physico-chemical approach to adhesion of Alicyclobacillus cells and spores to model solid materials

Extremophiles - Acidothermophilic bacteria of the genus Alicyclobacillus are frequent contaminants of fruit-based products. This study is the first attempt to characterize the physico-chemical...     

New insights in the male anatomy,spermatophore formation,and sperm structure in Atyidae: The red cherry shrimp Neocaridina davidi

This study aims to analyze the functional anatomy of the male reproductive system in Neocaridina davidi, a very popular ornamental species of caridean shrimp. Mature males were cold‐anaesthetized and their reproductive systems were dissected for histological and histochemical analysis, while the spermatozoa and spermatophore wall ultrastructure were analyzed under transmission electron microscopy. The male reproductive system consisted of two coiled testes, which were continuous with the vasa deferentia. Testes were positioned on the dorsal side of the cephalothorax above the hepatopancreas, and comprised seminiferous tubules where spermatogenesis occurred. Each vas deferens (VD) was a long tube dorsolaterally positioned with respect to the hepatopancreas, and increased in diameter at the distal end. Three regions could be recognized in the VD: proximal, middle, and distal. The proximal region had a cylindrical epithelium with secretory cells. The middle region (or typhlosole) had a dorsal fold (or typhlosole) with a thick columnar epithelium and high secretory activity. The spermatophore was a continuous cord with three acellular layers, which were mainly characterized by the presence of neutral glycoconjugates and proteins. The sperm morphology was distinct from the inverted cup‐shaped spermatozoa observed in the majority of caridean shrimps. The spermatozoa in specimens of N. davidi were spherical in shape, with a cross‐striated, single, short spike, and arranged in clusters of three or four sperm cells. The composition of the spermatophore, and the arrangement and form of the spermatozoa, seem to be unique in comparison to other species of Caridea.