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Pimentel-Schmitt EF Thomae AW Amon J Klieber MA Roth HM Muller YA Jahreis K Burkovski A Titgemeyer F 《Journal of molecular microbiology and biotechnology》2007,12(1-2):75-81
Carbon metabolism and regulation is poorly understood in mycobacteria, a genus that includes some major pathogenic species like Mycobacterium tuberculosis and Mycobacterium leprae. Here, we report the identification of a glucose kinase from Mycobacterium smegmatis. This enzyme serves in glucose metabolism and global carbon catabolite repression in the related actinomycete Streptomyces coelicolor. The gene, msmeg1356 (glkA), was found by means of in silico screening. It was shown that it occurs in the same genetic context in all so far sequenced mycobacterial species, where it is located in a putative tricistronic operon together with a glycosyl hydrolase and a putative malonyl-CoA transacylase. Heterologous expression of glkA in an Escherichia coli glucose kinase mutant led to the restoration of glucose growth, which provided in vivo evidence for glucose kinase function. GlkA(Msm) was subsequently overproduced in order to study its enzymatic features. We found that it can form a dimer and that it efficiently phosphorylates glucose at the expense of ATP. The affinity constant for glucose was with 9 mM about eight times higher and the velocity was about tenfold slower when compared to the parallel measured glucose kinase of S. coelicolor. Both enzymes showed similar substrate specificity, which consists in an ATP-dependent phosphorylation of glucose and no, or very inefficient, phosphorylation of the glucose analogues 2-deoxyglucose and methyl alpha-glucoside. Hence, our data provide a basis for studying the role of mycobacterial glucose kinase in vivo to unravel possible catalytic and regulatory functions. 相似文献
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Rehab Kamel Simone Garcia Frank Lezoualc'h Rodolphe Fischmeister Sylviane Muller Johan Hoebeke Pierre Eftekhari 《BMC developmental biology》2007,7(1):34
Background
The presence of functional 5-HT4 receptors in human and its involvement in neonatal lupus erythematosus (NLE) have prompted us to study the receptor expression and role during embryogenesis. Earlier we managed to demonstrate that female BALB/c mice immunized against the second extracellular loop (SEL) of the 5-HT4 receptor gave birth to pups with heart block. To explain this phenomenon we investigated the expression of 5-HT4 receptors during mouse embryogenesis. At the same time we looked whether the consequence of 5-HT4 receptor immunomodulation observed earlier is in relation to receptor expression. 相似文献176.
Persaud SJ Muller D Belin VD Papadimitriou A Huang GC Amiel SA Jones PM 《Archives of physiology and biochemistry》2007,113(3):104-109
Arachidonic acid (AA) is generated in pancreatic beta-cells through the activation of Ca2+-dependent cytosolic phospholipase A2 (cPLA2) and the consequent hydrolysis of membrane phospholipids in the sn-2 position of the glycerophospholipid backbone. AA acts as a second messenger in beta-cells to elevate cytosolic Ca2+ levels and stimulate insulin secretion, but it is not clear whether these are direct effects of AA or are dependent on its metabolism by cyclooxygenase (COX) and/or lipoxygenase (LOX) enzymes. In addition, much of the published data in this area have been generated using insulin-secreting cell lines or rodent islets, with very little information on AA generation and metabolism in human islets of Langerhans. This short review examines cPLA2, COX and LOX expression and function in insulin- secreting cell lines and rodent and human islets. 相似文献
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Overwintering is a key demographic stage for migratory birds but remains poorly understood, especially among multiple declining grassland bird species. The non-breeding ranges all 4 species of longspur (i.e., chestnut-collared [Calcarius ornatus], Smith's [C. pictus], Lapland [C. lapponicus], thick-billed [Rhynchophanes mccownii]) overlap in Oklahoma and the Texas Panhandle, USA, making this region ideal to study their wintering ecology. We evaluated the relationship between wintering longspur occurrence and fine-scale habitat characteristics using a combination of standardized bird surveys and vegetation plot sampling. Our study encompassed large, representative tracts of 3 prairie ecosystems (i.e., shortgrass, mixed-grass, and tallgrass prairies) that intersect within the Southern Great Plains, during winters of 2018–2019 and 2019–2020. Using randomization tests and classification trees, we characterized longspur habitats and compared these associations across the 3 prairie ecosystems. Fine-scale winter habitats (horizontal structure, vertical structure, and species compositions) varied among all 4 longspur species, varied at very fine scales, and differed between grassland types. Our findings can be applied to the management of grasslands such as decreasing vegetation height in mixed-grass prairies for chestnut-collared longspurs or removing woody vegetation in shortgrass prairies for thick-billed longspurs to help develop full-life cycle conservation for longspurs, which have experienced population declines. 相似文献
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Santillán-Saldivar Jair Gemechu Eskinder Muller Stéphanie Villeneuve Jacques Young Steven B. Sonnemann Guido 《The International Journal of Life Cycle Assessment》2022,27(3):457-468
The International Journal of Life Cycle Assessment - We observe a methodological gap for assessing impacts within the Area of Protection (AoP) Natural Resources in LCA with regard to concerns about... 相似文献
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Cardiac‐Specific Disruption of Bin1 in Mice Enables a Model of Stress‐ and Age‐Associated Dilated Cardiomyopathy 下载免费PDF全文