Microbial Endoliths on East Adriatic Limestone Coast: Morphological vs. Molecular Diversity

For the first time, a combined genotype-phenotype diversity analysis of endolithic microorganisms by pyrosequencing and microscopy was carried out across the intertidal and supratidal ranges of the Adriatic limestone coast. The coastal profiles represent ecotones between the sea and land, which express gradients of water supply, solar illumination, and salinity. The use of scanning electron microscopy imagery of resin casts showed that euendolith penetration remained shallow in the uppermost zones and was progressively deeper in the lower ranges where the water supply was more frequent. Microbial genotypes and phenotypes along the coastal profile showed large differences in dominance of taxa, but less in their diversity. The linkage between morphotypes observed along the profile and sequences was achieved by sequencing single cells/filaments, which were morphologically identified prior to their amplification. Molecular signatures of Hormathonema spp., Hyella caespitosa, Scytonema endolithicum, Solentia paulocellulare and Kyrtuthrix dalmatica were found on the profile and their specific placement was confirmed by morphological observations. Most sequences obtained were affiliated with Cyanobacteria (43%), Alphaproteobacteria (18%), and Gammaproteobacteria (7%). A total of 13 cyanobacterial morphospecies and 17 genotypes were found. Most cyanobacterial sequences belonged to the Pleurocapsales (33%), only 2% of the sequences belonged to the Nostocales and Oscillatoriales. The sequences corresponding to the cyanobacterial genus Hormathonema exhibited the highest abundances among all detected sequences, which is consistent with the microscopic observations in other parts of the world. The results of our investigation underline the importance of a combined approach in comparing the molecular data with microscopic observations in all phases of the study. Further RNA studies are needed to identify the actively growing parts of the endolithic community.     

Non-canonical role of wild-type SEC23B in the cellular stress response pathway

While germline recessive loss-of-function mutations in SEC23B in humans cause a rare form of anaemia, heterozygous change-of-function mutations result in increased predisposition to cancer. SEC23B encodes SEC23 homologue B, a component of coat protein complex II (COPII), which canonically transports proteins from the endoplasmic reticulum (ER) to the Golgi. Despite the association of SEC23B with anaemia and cancer, the precise pathophysiology of these phenotypic outcomes remains unknown. Recently, we reported that mutant SEC23B has non-canonical COPII-independent function, particularly within the ER stress and ribosome biogenesis pathways, and that may contribute to the pathobiology of cancer predisposition. In this study, we hypothesized that wild-type SEC23B has a baseline function within such cellular stress response pathways, with the mutant protein reflecting exaggerated effects. Here, we show that the wild-type SEC23B protein localizes to the nucleus in addition to classical distribution at the ER/Golgi interface and identify multiple putative nuclear localization and export signals regulating nuclear–cytoplasmic transport. Unexpectedly, we show that, independently of COPII, wild-type SEC23B can also localize to cell nucleoli under proteasome inhibition conditions, with distinct distribution patterns compared to mutant cells. Unbiased proteomic analyses through mass spectrometry further revealed that wild-type SEC23B interacts with a subset of nuclear proteins, in addition to central proteins in the ER stress, protein ubiquitination, and EIF2 signalling pathways. We validate the genotype-specific differential SEC23B–UBA52 (ribosomal protein RPL40) interaction. Finally, utilizing patient-derived lymphoblastoid cell lines harbouring either wild-type or mutant SEC23B, we show that SEC23B levels increase in response to ER stress, further corroborating its role as a cellular stress response sensor and/or effector. Overall, these observations suggest that SEC23B, irrespective of mutation status, has unexplored roles in the cellular stress response pathway, with implications relevant to cancer and beyond that, CDAII and normal cell biology.Subject terms: Cell biology, Cancer genetics     

Purification of β-xylosidase from Aspergillus tamarii using ground oats and a possible application on the fermented hydrolysate by Pichia stipitis

In this study we determined that Aspergillus tamarii Kita is able to utilize Avena sativa L. (oats) for the production of β-xylosidase under static or shaking conditions in submerged liquid-state (LSF), solid-state (SSF) and slurry-state (SlSF) cultures. The produced enzyme was purified and characterized. Maximum yield occurred under shaking conditions in SSF cultures (33.7 U/ml), with 24.9 and 5.5 U/ml produced in SISF and LSF cultures, respectively. Peptone was found to be the best nitrogen additive and enhanced enzyme production (41.5 U/ml). The produced enzyme was precipitated by ammonium sulfate (60 %) and further purified by gel filtration through a Sephadex G-100 and ion exchange column of diethylaminoethyl cellulose, with a yield of 40.57 % and 35.73-fold purification. Enzyme activity was optimal at pH 5.5 and 55 °C. The purified enzyme retained full activity even at the end of a 1-h incubation at this optimal condition. Midpoint of thermal inactivation (Tm) was recorded at 60 °C after 90 min of exposure. The Michaelis–Menten constant, maximal reaction velocity, turnover number and specificity constant of the purified enzyme were calculated to be 0.075 mg/ml, 71.42 U/mg of protein, 7.14/S and 95.2 mg/ml/s, respectively. The inability of the purified enzyme to hydrolyze celluloses indicated that the enzyme was a free cellulase. The most efficient enzyme activators were Mg2+, followed by Mn2+ and Zn2+ in that order. The molecular mass of the purified enzyme was 91 kDa as determined by SDS-PAGE. The possibility of using the fermentation of ground oat hydrolysate for the production of ethanol and xylitol in the presence of Pichia stipitis Pignal was assessed. The maximum production of ethanol and xylitol were obtained after 72 h of fermentation, resulting in 11.06 and 21.51 g/l respectively.     

Chromosome Segregation and Peptidoglycan Remodeling Are Coordinated at a Highly Stabilized Septal Pore to Maintain Bacterial Spore Development

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Comparison of exercise effects on the hemodynamics of the Bio 14.6 cardiomyopathic hamster.

1. Comparisons of the effects of 4 and 16 weeks of exercise were made on; cardiac output, stroke volume, heart rate, left intraventricular systolic and diastolic pressures, dP/dt, and heart calcium in the Bio 14.6 cardiomyopathic and F1 B hamsters. 2. In the cardiomyopathic hamster the cardiac output, stroke volume, left intraventricular systolic pressure and dP/dt, which were all depressed in the age related sedentary animals, were increased by both periods of exercise. The left intraventricular diastolic pressure which was elevated was likewise decreased by both exercise periods. Only the 16 week exercise period decreased the resting heart rate. 3. In the normal F1 B hamster, both periods of exercise increased the cardiac output and stroke volume while the left intraventricular systolic pressure was decreased. Only the 16 week exercise decreased the resting heart rate and left intraventricular diastolic pressure and increased the left ventricular dP/dt. 4. Both periods of exercise increased the total heart calcium in the Bio 14.6 hamster while the heart calcium in the F1 B was increased only by the 16 week exercise period.     

Thymic cell populations in amphibia: Quantitative study of the growth,stability, and regression of the cell populations in the thymus of the newtPleurodeles waltlii Michah

Summary Twenty days after fertilization (stage 40) the thymus ofPleurodeles waltlii consists of two main cell types: epithelial reticular cells (71%) and lymphoid stem-cells (24%).Between day 20 and day 72 (stage 53) the lymphoid stem-cells differentiate into lymphocytes, via the lymphoblast state. Commencing at day 20, epithelial reticular cells are transformed into epithelial reticular dense cells. Following day 65, other epithelial reticular cells begin to differentiate into epithelial hypertrophic cells, and these subsequently form thymic cysts. During this whole period intense proliferation takes place.The three types of polynuclear cells (neutrophil, eosinophil, and basophil), the macrophages, and the plasmocytes differentiate outside the thymus then migrate into it through the vascular system.Around day 72 (stage 53), the mature thymus consists of two parts: the first is visible as a background or cortex-like area, the second comprises medulla like spots, formed by small numbers of cysts.Around metamorphosis the cell populations reach a stable state.After metamorphosis the relative frequency of the lymphoid cell population progressively decreases, while the proportion of epithelial hypertrophic cells, together with cyst surface area, is increased. Consequently the ratio of cysts/background area increases with age.