Mitochondrial DNA phylogeography of the polytypic North American rat snake (Elaphe obsoleta): a critique of the subspecies concept

Subspecies have been considered artificial subdivisions of species, pattern classes, or incipient species. However, with more data and modern phylogenetic techniques, some subspecies may be found to represent true species. Mitochondrial DNA analysis of the polytypic snake, Elaphe obsoleta, yields well-supported clades that do not conform to any of the currently accepted subspecies. Complete nucleotide sequences of the cytochrome b gene and the mitochondrial control region produced robust maximum-parsimony and maximum-likelihood trees that do not differ statistically. Both trees were significantly shorter than a most parsimonious tree in which each subspecies was constrained to be monophyletic. Thus, the subspecies of E. obsoleta do not represent distinct genetic lineages. Instead, the evidence points to three well-supported mitochondrial DNA clades confined to particular geographic areas in the eastern United States. This research underscores the potential problems of recognizing subspecies based on one or a few characters.     

Optimized Binding of [35S]GTPγS to Gq-Like Proteins Stimulated with Dopamine D1-Like Receptor Agonists

Subtypes of dopamine D₁-like receptors are coupled through the G proteins Gs or Gq to stimulate either adenylate cyclase or phospholipase C signaling cascades. In the present study, we have uncovered the marked enhancement by sodium deoxycholate of D1-like agonist-stimulated [³⁵S]GTPS binding to Gq-like G proteins in brain membranes, and determined the optimal experimental conditions for assessing agonist effects on [³⁵S]GTPS binding in the presence of the detergent. Factors and their optimal levels that were found to significantly enhance the sensitivity and robustness of the agonist-stimulated [³⁵S]GTPS binding reaction include protein concentration at 40 g/ml, cationic concentrations of 120 mM Na⁺, 1.8 mM K⁺, and 20 mM Mg²⁺, a molar guanine nucleotide ratio of 100,000 GDP to [³⁵S]GTPS, the presence of 1 mM deoxycholate, and an overall incubation duration of 30–120 min. Under the optimized conditions, the D₁-like agonist SKF38393 induced potent and highly efficacious (up to 1000%) stimulation of [³⁵S]GTPS binding in membrane preparations from the striatum and other rat brain regions. In striatal membranes incubated with drug for 2 h, immunoprecipitation of the [³⁵S]GTPS-bound proteins with specific G antibodies showed that at least 70% of SKF38393-stimulated [³⁵S]GTPS binding was to Gq. The present reaction parameters are consistent with conditions previously found to support dopaminergic stimulation of phospholipase C-mediated signaling in brain slice preparations. These results imply that different but equally physiologically relevant conditions can be obtained under which subtypes of dopaminergic receptors may couple preferentially to Gs and the adenylate cyclase pathway or to Gq and the phospholipase C pathway.     

G protein-coupled, extracellular Ca2+ (Ca o 2+ )-sensing receptor enables Ca o 2+ to function as a versatile extracellular first messenger

The cloning of a G protein-coupled, extracellular Ca²⁺ (Ca _o ²⁺ )-sensing receptor (CaR) has afforded a molecular basis for a number of the known effects of Ca _o ²⁺ on tissues involved in maintaining systemic calcium homeostasis, especially parathyroid gland and kidney. In addition to providing molecular tools for showing that CaR messenger RNA and protein are present within these tissues, the cloned CaR has permitted documentation that several human diseases are the result of inactivating or activating mutations of this receptor as well as generation of mice that have targeted disruption of the CaR gene. Characteristic changes in the functions of parathyroid and kidney in these patients as well as in the CaR “knockout” mice have elucidated considerably the CaR’s physiological roles in mineral ion homeostasis. Nevertheless, a great deal remains to be learned about how this receptor regulates the functioning of other tissues involved in Ca _o ²⁺ metabolism, such as bone and intestine. Further study of these human diseases and of the mouse models will doubtless be useful in gaining additional understanding of the CaR’s roles in these latter tissues. Furthermore, we understand little of the CaR’s functions in tissues that are not directly involved in systemic mineral ion metabolism, where the receptor probably serves diverse other roles. Some of these functions may be related to the control of intra- and local extracellular concentrations of Ca²⁺, while others may be unrelated to either systemic or local ionic homeostasis. In any case, the CaR and conceivably additional receptors/sensors for Ca²⁺ or other extracellular ions represent versatile regulators of a wide variety of cellular functions and represent important targets for novel classes of therapeutics.     

Ser84是spindlin1定位与功能发挥的关键位点

spindlin1为作者所在研究组克隆并命名的肿瘤相关新基因,之前研究表明spindlin1蛋白定位于细胞核,并有可能通过对TCF-4通路的调节参与对肿瘤细胞生长和周期的调控．为进一步探索spindlin1的作用机制,明确spindlin1结构与功能的关系,在生物信息学分析及晶体结构解析的基础上,构建系列突变表达载体,首先以spindlin1蛋白亚细胞定位为指标,观察野生型及系列突变体spindlin1蛋白的亚细胞定位,并进一步检测野生型及突变体spindlin1对TCF-4荧光素酶报告基因转录活性的调控作用,以明确spindlin1定位与功能的关键位点．结果表明：Ser14＋Ser84、Ser84＋Ser99、Ser14＋Ser84＋Ser99位点Ser到Ala的联合突变能使野生型融合蛋白在细胞核内集中分布的特性消失,成为全细胞弥散分布,而Ser14、Ser84、Ser99各位点的单独突变或Ser14＋Ser99联合突变对spindlin1蛋白的细胞核内分布没有影响．与此同时,对TCF-4荧光素酶报告基因活性的分析表明,Ser14＋Ser84、Ser84＋Ser99、Ser14＋Ser84＋Ser99的联合突变使spindlin1对其活性的激活作用消失或降低．上述结果表明,Ser84是spindlin1细胞定位与功能发挥的关键位点,其作用发挥需要Ser14与Ser99的协助．     

Candida albicans ABG1 gene is involved in endocytosis

The human fungal pathogen Candida albicans undergoes reversible morphogenetic transitions between yeast, hyphal and pseudohyphal forms. The fungal vacuole actively participates in differentiation processes and plays a key role supporting hyphal growth. The ABG1 gene of C. albicans encodes an essential protein located in the vacuolar membranes of both yeast and hyphae. Using fluorescence microscopy of a green fluorescent protein-tagged version of Abg1p, a fraction of the protein was detected in hyphal tips, not associated with vacuolar membranes. Live cell imaging of emerging germ tubes showed that Abg1p migrated to the polarized growth site and colocalized with endocytic vesicles. Phenotypic analysis of a methionine-regulated conditional mutant confirmed that Abg1p is involved in endocytosis.     

The protective effects of C16 peptide and angiopoietin-1 compound in lipopolysaccharide-induced acute respiratory distress syndrome

C16 peptide and angiopoietin-1 (Ang-1) have been found to have anti-inflammatory activity in various inflammation-related diseases. However, their combined role in acute respiratory distress syndrome (ARDS) has not been investigated yet. The objective of this study was to investigate the effects of C16 peptide and Ang-1 in combination with lipopolysaccharide (LPS)-induced inflammatory insult in vitro and in vivo. Human pulmonary microvascular endothelial cells and human pulmonary alveolar epithelial cells were used as cell culture systems, and an ARDS rodent model was used for in vivo studies. Our results demonstrated that C16 and Ang-1 in combination significantly suppressed inflammatory cell transmigration by 33% in comparison with the vehicle alone, and decreased the lung tissue wet-to-dry lung weight ratio to a maximum of 1.53, compared to 3.55 in the vehicle group in ARDS rats. Moreover, C  +  A treatment reduced the histology injury score to 60% of the vehicle control, enhanced arterial oxygen saturation (SO₂), decreased arterial carbon dioxide partial pressure (PCO₂), and increased oxygen partial pressure (PO₂) in ARDS rats, while also improving the survival rate from 47% (7/15) to 80% (12/15) and diminishing fibrosis, necrosis, and apoptosis in lung tissue. Furthermore, when C  +  A therapy was administered 4 h following LPS injection, the treatment showed significant alleviating effects on pulmonary inflammatory cell infiltration 24 h postinsult. In conclusion, our in vitro and in vivo studies show that C16 and Ang-1 exert protective effects against LPS-induced inflammatory insult. C16 and Ang-1 hold promise as a novel agent against LPS-induced ARDS. Further studies are needed to determine the potential for C16 and Ang-1 in combination in treating inflammatory lung diseases.     

Calpain activation mediates microgravity-induced myocardial abnormalities in mice via p38 and ERK1/2 MAPK pathways

The human cardiovascular system has adapted to function optimally in Earth''s 1G gravity, and microgravity conditions cause myocardial abnormalities, including atrophy and dysfunction. However, the underlying mechanisms linking microgravity and cardiac anomalies are incompletely understood. In this study, we investigated whether and how calpain activation promotes myocardial abnormalities under simulated microgravity conditions. Simulated microgravity was induced by tail suspension in mice with cardiomyocyte-specific deletion of Capns1, which disrupts activity and stability of calpain-1 and calpain-2, and their WT littermates. Tail suspension time-dependently reduced cardiomyocyte size, heart weight, and myocardial function in WT mice, and these changes were accompanied by calpain activation, NADPH oxidase activation, and oxidative stress in heart tissues. The effects of tail suspension were attenuated by deletion of Capns1. Notably, the protective effects of Capns1 deletion were associated with the prevention of phosphorylation of Ser-345 on p47^phox and attenuation of ERK1/2 and p38 activation in hearts of tail-suspended mice. Using a rotary cell culture system, we simulated microgravity in cultured neonatal mouse cardiomyocytes and observed decreased total protein/DNA ratio and induced calpain activation, phosphorylation of Ser-345 on p47^phox, and activation of ERK1/2 and p38, all of which were prevented by calpain inhibitor-III. Furthermore, inhibition of ERK1/2 or p38 attenuated phosphorylation of Ser-345 on p47^phox in cardiomyocytes under simulated microgravity. This study demonstrates for the first time that calpain promotes NADPH oxidase activation and myocardial abnormalities under microgravity by facilitating p47^phox phosphorylation via ERK1/2 and p38 pathways. Thus, calpain inhibition may be an effective therapeutic approach to reduce microgravity-induced myocardial abnormalities.     

The roles and functions of Paneth cells in Crohn’s disease: A critical review

Paneth cells (PCs) are located at the base of small intestinal crypts and secrete the α‐defensins, human α‐defensin 5 (HD‐5) and human α‐defensin 6 (HD‐6) in response to bacterial, cholinergic and other stimuli. The α‐defensins are broad‐spectrum microbicides that play critical roles in controlling gut microbiota and maintaining intestinal homeostasis. Inflammatory bowel disease, including ulcerative colitis and Crohn's disease (CD), is a complicated autoimmune disorder. The pathogenesis of CD involves genetic factors, environmental factors and microflora. Surprisingly, with regard to genetic factors, many susceptible genes and pathogenic pathways of CD, including nucleotide‐binding oligomerization domain 2 (NOD2), autophagy‐related 16‐like 1 (ATG16L1), immunity‐related guanosine triphosphatase family M (IRGM), wingless‐related integration site (Wnt), leucine‐rich repeat kinase 2 (LRRK2), histone deacetylases (HDACs), caspase‐8 (Casp8) and X‐box‐binding protein‐1 (XBP1), are relevant to PCs. As the underlying mechanisms are being unravelled, PCs are identified as the central element of CD pathogenesis, integrating factors among microbiota, intestinal epithelial barrier dysfunction and the immune system. In the present review, we demonstrate how these genes and pathways regulate CD pathogenesis via their action on PCs and what treatment modalities can be applied to deal with these PC‐mediated pathogenic processes.