Nicotinic Acid Adenine Dinucleotide Phosphate (NAADP) and Endolysosomal Two-pore Channels Modulate Membrane Excitability and Stimulus-Secretion Coupling in Mouse Pancreatic β Cells

Pancreatic β cells are electrically excitable and respond to elevated glucose concentrations with bursts of Ca²⁺ action potentials due to the activation of voltage-dependent Ca²⁺ channels (VDCCs), which leads to the exocytosis of insulin granules. We have examined the possible role of nicotinic acid adenine dinucleotide phosphate (NAADP)-mediated Ca²⁺ release from intracellular stores during stimulus-secretion coupling in primary mouse pancreatic β cells. NAADP-regulated Ca²⁺ release channels, likely two-pore channels (TPCs), have recently been shown to be a major mechanism for mobilizing Ca²⁺ from the endolysosomal system, resulting in localized Ca²⁺ signals. We show here that NAADP-mediated Ca²⁺ release from endolysosomal Ca²⁺ stores activates inward membrane currents and depolarizes the β cell to the threshold for VDCC activation and thereby contributes to glucose-evoked depolarization of the membrane potential during stimulus-response coupling. Selective pharmacological inhibition of NAADP-evoked Ca²⁺ release or genetic ablation of endolysosomal TPC1 or TPC2 channels attenuates glucose- and sulfonylurea-induced membrane currents, depolarization, cytoplasmic Ca²⁺ signals, and insulin secretion. Our findings implicate NAADP-evoked Ca²⁺ release from acidic Ca²⁺ storage organelles in stimulus-secretion coupling in β cells.     

Heme Oxygenase-1 Protects Corexit 9500A-Induced Respiratory Epithelial Injury across Species

The effects of Corexit 9500A (CE) on respiratory epithelial surfaces of terrestrial mammals and marine animals are largely unknown. This study investigated the role of CE-induced heme oxygenase-1 (HO-1), a cytoprotective enzyme with anti-apoptotic and antioxidant activity, in human bronchial airway epithelium and the gills of exposed aquatic animals. We evaluated CE-mediated alterations in human airway epithelial cells, mice lungs and gills from zebrafish and blue crabs. Our results demonstrated that CE induced an increase in gill epithelial edema and human epithelial monolayer permeability, suggesting an acute injury caused by CE exposure. CE induced the expression of HO-1 as well as C-reactive protein (CRP) and NADPH oxidase 4 (NOX4), which are associated with ROS production. Importantly, CE induced caspase-3 activation and subsequent apoptosis of epithelial cells. The expression of the intercellular junctional proteins, such as tight junction proteins occludin, zonula occludens (ZO-1), ZO-2 and adherens junctional proteins E-cadherin and Focal Adhesion Kinase (FAK), were remarkably inhibited by CE, suggesting that these proteins are involved in CE-induced increased permeability and subsequent apoptosis. The cytoskeletal protein F-actin was also disrupted by CE. Treatment with carbon monoxide releasing molecule-2 (CORM-2) significantly inhibited CE-induced ROS production, while the addition of HO-1 inhibitor, significantly increased CE-induced ROS production and apoptosis, suggesting a protective role of HO-1 or its reaction product, CO, in CE-induced apoptosis. Using HO-1 knockout mice, we further demonstrated that HO-1 protected against CE-induced inflammation and cellular apoptosis and corrected CE-mediated inhibition of E-cadherin and FAK. These observations suggest that CE activates CRP and NOX4-mediated ROS production, alters permeability by inhibition of junctional proteins, and leads to caspase-3 dependent apoptosis of epithelial cells, while HO-1 and its reaction products protect against oxidative stress and apoptosis.     

Examining the Species-Specificity of Rhesus Macaque Cytomegalovirus (RhCMV) in Cynomolgus Macaques

Cytomegalovirus (CMV) is a highly species-specific virus that has co-evolved with its host over millions of years and thus restricting cross-species infection. To examine the extent to which host restriction may prevent cross-species research between closely related non-human primates, we evaluated experimental infection of cynomolgus macaques with a recombinant rhesus macaque-derived CMV (RhCMV-eGFP). Twelve cynomolgus macaques were randomly allocated to three groups: one experimental group (RhCMV-eGFP) and two control groups (UV-inactivated RhCMV-eGFP or media alone). The animals were given two subcutaneous inoculations at week 0 and week 8, and a subset of animals received an intravenous inoculation at week 23. No overt clinical or haematological changes were observed and PBMCs isolated from RhCMV-eGFP inoculated animals had comparable eGFP- and IE-1-specific cellular responses to the control animals. Following inoculation with RhCMV-eGFP, we were unable to detect evidence of infection in any blood or tissue samples up to 4 years post-inoculation, using sensitive viral co-culture, qPCR, and Western blot assays. Co-culture of urine and saliva samples demonstrated the presence of endogenous cynomolgus CMV (CyCMV) cytopathic effect, however no concomitant eGFP expression was observed. The absence of detectable RhCMV-eGFP suggests that the CyCMV-seropositive cynomolgus macaques were not productively infected with RhCMV-eGFP under these inoculation conditions. In a continued effort to develop CMV as a viral vector for an HIV/SIV vaccine, these studies demonstrate that CMV is highly restricted to its host species and can be highly affected by laboratory cell culture. Consideration of the differences between lab-adapted and primary viruses with respect to species range and cell tropism should be a priority in evaluating CMV as vaccine vector for HIV or other pathogens at the preclinical development stage.     

Synchrotron µXRF imaging of live seedlings of Berkheya coddii and Odontarrhena muralis during germination and seedling growth

Plant and Soil - Nickel hyperaccumulator plants require highly evolved mechanisms to avoid cellular-level toxicity to cope with the high prevailing concentrations of nickel in their seeds and...     

Bacterial community diversity in the rhizosphere of nickel hyperaccumulator plant species from Borneo Island (Malaysia)

The Island of Borneo is a major biodiversity hotspot, and in the Malaysian state of Sabah, ultramafic soils are extensive and home to more than 31 endemic nickel hyperaccumulator plants. The aim of this study was to characterize the structure and the diversity of the rhizosphere bacterial communities of several of these nickel hyperaccumulator plants and factors that affect these bacterial communities in Sabah. The most abundant phyla were Proteobacteria, Acidobacteria and Actinobacteria. At family level, Burkholderiaceae and Xanthobacteraceae (Proteobacteria phylum) were the most abundant families in the hyperaccumulator rhizospheres. Redundancy analysis based on soil chemical analyses and relative abundances of the major bacterial phyla showed that abiotic factors of the studied sites drove the bacterial diversity. For all R. aff. bengalensis rhizosphere soil samples, irrespective of studied site, the bacterial diversity was similar. Moreover, the Saprospiraceae family showed a high representativeness in the R. aff. bengalensis rhizosphere soils and was linked with the nickel availability in soils. The ability of R. aff. bengalensis to concentrate nickel in its rhizosphere appears to be the major factor driving the rhizobacterial community diversity unlike for other hyperaccumulator species.     

Comparing an adiposopathy approach with four popular classifications schemes to categorize the metabolic profile of postmenopausal women

Journal of Physiology and Biochemistry - Numerous classifications are used to discern metabolically healthy obese (MHO) from metabolically abnormal obese (MAO) individuals. The goal of this study...     

Variation of morphological and leaf stoichiometric traits of two endemic species along the elevation gradient of Mount Kenya,East Africa

环境能一定程度上影响和改变植物的形态结构和生理生化。本文旨在拟研究热带东非高山不同海拔梯度下两 种代表植物Dendrosenecio keniensis和Lobelia gregoriana的形态结构和生理生化的变化。我们沿海拔梯度在海拔3500 m至4300 m的范围内 建立了90个10 m × 10 m的样方,使用1 km × 1 km网格单元在ArcGis 10.5 中栅格化研究区域并获取每个样方的气候数据,包括年平均气温、 年平均降水量、年总辐射量、水汽压,同时获取了每个样方的地形变量,包括坡向、坡度和阴影等。我们收集了每个样方两种植物的形态性状,包括株高、叶面积、叶厚、叶干重、比叶面积,以及叶化学计量性状,包括氮、碳、磷的含量,同时收集了样方的土壤有机碳、 土壤全氮、土壤有机氮和土壤磷数据。我们将海拔高度设为解释变量,对两种植物的形态性状和叶片化学计量性状进行线性回归分析,同时,在海拔梯度上对叶片形态和化学计量性状与气候、土壤和地形变量进行了相关分析。我们的研究发现,D. keniensis 有羊毛状的短柔毛叶, 而L. gregoriana则有粘液填充的肉质和蜡质的角质层叶子,以避免冻害。这两个物种都呈现出了降低的代谢率,表现在叶片磷含量较低。我 们的研究结果还表明,形态和叶片化学计量的变化是由气候、土壤和地形变量共同决定的,这些变量随肯尼亚山海拔的变化而变 化。我们推测,沿海拔梯度两种植物的形态和叶片化学计量性状的变异是对恶劣环境条件的适应。     

A frequency difference in optical-density oscillations of early Dictyostelium discoideum density classes and its implications for development

Abstract. This paper describes the separation of preaggregation-stage Dictyostelium discoideum cells into various density classes on preformed, linear Percoll density gradients and reports the finding of frequency differences in the cyclic-AMP (cAMP) oscillatory signalling system of different density classes. The cAMP oscillations were measured via their associated optical-density oscillations using a device constructed to measure cell agglutination via light-scattering changes and capable of handling 24 samples simultaneously. We found that the least dense cells oscillated at a higher frequency than the most dense cells. Mixtures of fast- and slow-oscillating cell populations synchronized at an intermediate frequency. We propose that the 'tip' is a high-frequency pacemaker which persists throughout development and use these findings to explain how the 'tip', i.e. the anterior end of all multicellular structures, can function as an organizer.