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1.
Fish skin bacteria: Colonial and cellular hydrophobicity 总被引:1,自引:0,他引:1
Dental plaque is a complex community of bacteria coexisting in an environment frequently limited by carbon and energy sources. UnlikeStreptococcus mutans, other oral streptococci such asS. milleri andS. sanguis have an absolute requirement for and actually consume all available arginine when grown glucose limited in a chemically defined medium. The conditions, particularly in terms of arginine concentration, under which the dental plaque bacteriaS. mutans andS. milleri would coexist under glucose-limiting conditions were investigated. The minimum level of arginine supporting optimal growth ofS. milleri was found to be ca. 50M, and above this level these strains outcompetedS. mutans. However, coexistence withS. mutans could be achieved at arginine levels of 14–40M, depending upon theS. milleri andS. mutans strains used. Under such dual limitation,S. milleri was unable to respond to glucose pulses but did respond to pulses of arginine and arginine plus glucose. One of the twoS. milleri strains did not tolerate low pH. In contrast,S. mutans did not tolerate high pH whereasS. milleri was unaffected. This is relevant to dental plaque where arginine catabolism produces a pH rise. Additionally, arginine is an important nutrient since it can be used as an energy source by some oral streptococci. 相似文献
2.
Summary A new distinctive feature between the two Mediterranean species of Tethya, T. aurantium and T. citrina has been found in the body arrangement of different types of micrasters. Contrary to the previous assumptions, T. aurantium has two clearly distinct categories of micrasters: the chiaster-tylaster in the cortex and the larger, slender oxyaster in the choanosome. T. citrina has only slightly differentiated micraster sets in the cortex and choanosome; in the latter the shape of micrasters is close to that of oxyasters. SEM analysis shows that differences in micraster shape depend on the cylindrical or conical form of rays and on the distribution, density and strength of the microspines along their axis. The relationship between the degree of micraster differentiation and the development of the cortex in the two species is discussed. 相似文献
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Dr. G. Schleicher W. E. Stumpf U. Drews K. U. Thiedemann M. Sar 《Histochemistry and cell biology》1985,82(5):453-461
Summary The distribution of specific nuclear binding sites for androgens and estrogens in the male accessory sex organs of the mouse
was assessed by autoradiography with3H dihydrotestosterone (3H DHT) and3H estradiol (3H E2).
With3H DHT nuclear labeling differed among the epithelia of the organs. It was high in seminal vesicle and ampullary gland, moderate
in ventral prostate, urethral gland, prostatic excretory ducts and the ampulla ductus deferentis, low in dorsal prostate and
low or absent in coagulation gland. With3H E2, in contrast, epithelial nuclear labeling was high only in coagulation gland, moderate or low in seminal vesicle, low or
absent in ventral and dorsal prostate and absent in ampullary gland and ampulla ductus deferentis. In the lamina propria of
all organs nuclear labeling with3H DHT was generally moderate and existed only in some cells, with the highest number in the ampulla ductus deferentis. With3H E2, nuclear labeling in the lamina propria showed a high intensity in all organs, except in ventral and dorsal prostate which
remained unlabeled. Many labeled cells were found in the deferent duct and its ampulla, while in the other organs only a few
cells showed nuclear labeling with3H E2. In the smooth muscle sheath of all organs, some muscle cells were moderately labeled with3H DHT, but not with3H E2.
The results indicate the presence of nuclear receptors in male accessory sex organs for both dihydrotestosterone and estradiol.
The differential patterns of3H DHT and3H E2 nuclear uptake suggest differential sensitivities of the individual organs and their tissue compartments for androgens and
estrogens.
Supported by PHS grant NSO9914 to W.E.S. and Deutsche Forschungsgemeinschaft Dr94/4 to U.D. The work of Dr. Schleicher and
his stay in Chapel Hill were additionally sponsored by Studienstiftung des Deutschen Volkes and Boehringer-Ingelheim Fonds 相似文献
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Protha Biswas Uttpal Anand Suchismita Chatterjee Saha Nishi Kant Tulika Mishra Harison Masih Ananya Bar Devendra Kumar Pandey Niraj
Kumar Jha Madhumita Majumder Neela Das Vijaykumar
Shivaji Gadekar Mahipal S. Shekhawat Manoj Kumar Radha Jarosaw Prokw Jos M. Prez de la Lastra Abhijit Dey 《Journal of cellular and molecular medicine》2022,26(11):3083
8.
Arginine-rich cell-penetrating peptides are short cationic peptides capable of traversing the plasma membranes of eukaryotic cells. While successful intracellular delivery of many biologically active macromolecules has been accomplished using these peptides, their mechanisms of cell entry are still under investigation. Recent dialogue has centered on a debate over the roles that direct translocation and endocytotic pathways play in internalization of cell-penetrating peptides. In this paper, we review the evidence for the broad range of proposed mechanisms, and show that each distinct process requires negative Gaussian membrane curvature as a necessary condition. Generation of negative Gaussian curvature by cell-penetrating peptides is directly related to their arginine content. We illustrate these concepts using HIV TAT as an example. 相似文献
9.
Hadley KC Borrelli MJ Lepock JR McLaurin J Croul SE Guha A Chakrabartty A 《Cell stress & chaperones》2011,16(5):549-561
The inability of cells to maintain protein folding homeostasis is implicated in the development of neurodegenerative diseases,
malignant transformation, and aging. We find that multiphoton fluorescence imaging of 1-anilinonaphthalene-8-sulfonate (ANS)
can be used to assess cellular responses to protein misfolding stresses. ANS is relatively nontoxic and enters live cells
and cells or tissues fixed in formalin. In an animal model of Alzheimer’s disease, ANS fluorescence imaging of brain tissue
sections reveals the binding of ANS to fibrillar deposits of amyloid peptide (Aβ) in amyloid plaques and in cerebrovascular
amyloid. ANS imaging also highlights non-amyloid deposits of glial fibrillary acidic protein in brain tumors. Cultured cells
under normal growth conditions possess a number of ANS-binding structures. High levels of ANS fluorescence are associated
with the endoplasmic reticulum (ER), Golgi, and lysosomes—regions of protein folding and degradation. Nuclei are virtually
devoid of ANS binding sites. Additional ANS binding is triggered by hyperthermia, thermal lesioning, proteasome inhibition,
and induction of ER stress. We also use multiphoton imaging of ANS binding to follow the in vivo recovery of cells from protein-damaging
insults over time. We find that ANS fluorescence tracks with the binding of the molecular chaperone Hsp70 in compartments
where Hsp70 is present. ANS highlights the sensitivity of specific cellular targets, including the nucleus and particularly
the nucleolus, to thermal stress and proteasome inhibition. Multiphoton imaging of ANS binding should be a useful probe for
monitoring protein misfolding stress in cells. 相似文献
10.
Aline Awad Sokhavuth Sar Ronan Barré Clotilde Cariven Mickael Marin Jean Pierre Salles Christophe Erneux Didier Samuel Ama Gassama-Diagne 《Molecular biology of the cell》2013,24(14):2171-2185
The main targets of hepatitis C virus (HCV) are hepatocytes, the highly polarized cells of the liver, and all the steps of its life cycle are tightly dependent on host lipid metabolism. The interplay between polarity and lipid metabolism in HCV infection has been poorly investigated. Signaling lipids, such as phosphoinositides (PIs), play a vital role in polarity, which depends on the distribution and expression of PI kinases and PI phosphatases. In this study, we report that HCV core protein, expressed in Huh7 and Madin–Darby canine kidney (MDCK) cells, disrupts apicobasal polarity. This is associated with decreased expression of the polarity protein Dlg1 and the PI phosphatase SHIP2, which converts phosphatidylinositol 3,4,5-trisphosphate into phosphatidylinositol 4,5-bisphosphate (PtdIns(3,4)P2). SHIP2 is mainly localized at the basolateral membrane of polarized MDCK cells. In addition, PtdIns(3,4)P2 is able to bind to Dlg1. SHIP2 small interfering RNA or its catalytically dead mutant disrupts apicobasal polarity, similar to HCV core. In core-expressing cells, RhoA activity is inhibited, whereas Rac1 is activated. Of interest, SHIP2 expression rescues polarity, RhoA activation, and restricted core level in MDCK cells. We conclude that SHIP2 is an important regulator of polarity, which is subverted by HCV in epithelial cells. It is suggested that SHIP2 could be a promising target for anti-HCV treatment. 相似文献