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Mucin-type linkages (GalNAcalpha1-O-Ser/Thr) are initiated by a family of glycosyltransferases known as the UDP-N-acetylgalactosamine:polypeptide N-acetylgalactosaminyltransferases (ppGaNTases, EC 2.4.1.41). These enzymes transfer GalNAc from the sugar donor UDP-GalNAc to serine and threonine residues, forming an alpha anomeric linkage. Despite the seeming simplicity of ppGaNTase catalytic function, it is estimated on the basis of in silico analysis that there are 24 unique ppGaNTase human genes. ppGaNTase isoforms display tissue-specific expression in adult mammals as well as unique spatial and temporal patterns of expression during murine development. In vitro assays suggest that a subset of the ppGaNTases have overlapping substrate specificities, but at least two ppGaNTases (ppGaNTase-T7 and -T9 [now designated -T10]) appear to require the prior addition of GalNAc to a synthetic peptide before they can catalyze sugar transfer to this substrate. Site-specific O-glycosylation by several ppGaNTases is influenced by the position and structure of previously added O-glycans. Collectively, these observations argue in favor of a hierarchical addition of core GalNAc residues to the apomucin. Various forms of O-glycan pathobiology may be reexamined in light of the existence of an extensive ppGaNTase family of enzymes. Recent work has demonstrated that at least one ppGaNTase isoform is required for normal development in Drosophila melanogaster. Structural insights will no doubt lead to the development of isoform-specific inhibitors. Such tools will prove valuable to furthering our understanding of the functional roles played by O-glycans. 相似文献
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Innovation: Metabolomics: the apogee of the omics trilogy 总被引:3,自引:0,他引:3
Metabolites, the chemical entities that are transformed during metabolism, provide a functional readout of cellular biochemistry. With emerging technologies in mass spectrometry, thousands of metabolites can now be quantitatively measured from minimal amounts of biological material, which has thereby enabled systems-level analyses. By performing global metabolite profiling, also known as untargeted metabolomics, new discoveries linking cellular pathways to biological mechanism are being revealed and are shaping our understanding of cell biology, physiology and medicine. 相似文献
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Science China Life Sciences - The original article has been corrected. 相似文献
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Richard J. Franke 《The Yale journal of biology and medicine》2016,89(1):105-108
Palliative care is a quickly growing facet of modern medicine. While scientific advancements have broken new ground for the possibilities of end-of-life care, sensitive treatment of the patient as an individual has lagged behind and has frequently led to an unsatisfactory experience for patients, families, and the medical community at large. This essay argues that centralizing patients during the terminal phases of treatment by using humanistic perspectives has the potential to bring new meaning and improved effectiveness to patients and physicians alike. 相似文献
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J F Soothill 《BMJ (Clinical research ed.)》1976,1(6023):1467-1468
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《BMJ (Clinical research ed.)》1976,1(6019):1167-1168
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Barbara Schmidt 《The Yale journal of biology and medicine》2013,86(3):425-427
On April 3, 2013, the fourth biennial StemCONN conference took place at the Omni
Hotel at Yale in New Haven, Connecticut. This conference featured talks by
scientists from across the country who are currently at the forefront of stem
cell research, as well as talks by Edison Liu, President and CEO of the Jackson
Laboratory, and Jonathan Rotherberg, PhD, a Yale alumnus and Ion Torrent Systems
Founder and CEO. The conference highlighted the importance of stem cell research
to both science and medicine and emphasized the necessity of continued
government funding for this research, both in Connecticut and nationwide. 相似文献
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This study was designed to investigate the strength of attachment of plant seedling roots to the soil in which they were grown.
The study also assessed the effects of differing soil textures and differing soil matric potentials upon the strength of the
root:soil attachment. A device for growing roots upon a soil surface was designed, and was used to produce roots which were
attached to the soil. In order to quantify root:soil adhesion, roots of maize seedlings, grown on the soil surface, were subsequently
peeled off using a universal test machine, in conjunction with simultaneous time-lapse video observation. To clarify the partitioning
of energy in the root:soil peeling test, separate mechanical tests on roots, and on two adherent remoulded topsoil balls were
also carried out. The seedling root was characterised by a low bending stiffness. The energy stored in bending was negligible,
compared to the root:soil adhesion energy. The mechanical properties of two adherent remoulded topsoil balls were a decrease
of the soil:soil adhesion energy as the soil:soil plastic energy increased. These two parameters were therefore interdependent.
Using a video-camera system, it was possible to separate the different processes occurring during the root:soil peeling test,
in particular, the seed:soil adhesion and the root:soil soil adhesion. An interpretation of the complex and variable force:displacement
curves was thus possible, enabling calculation of the root:soil interfacial rupture energy. At a given suction (10 kPa), the
results of the peeling test showed a clear soil texture effect on the value of the root:soil interfacial rupture energy. In
contrast, for the same silty topsoil, the effect of the soil water suction on the value of the interfacial rupture energy
was very moderate. The root:soil interfacial rupture energy was controlled mainly by a product of microscopic soil specific
surface area and the macroscopic contact surface area between the root and the soil. Biological and physical interactions
contributing to root:soil adhesion such as root:soil interlocking mechanics were also analysed and discussed.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
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On the basis of the strict exclusion of the vis vitalis, the demand was raised by Carl Ludwig, Helmholtz, Du Bois-Reymond, and Brucke for a physiology which was causal-analytical and physically and chemically experimental. If, out of these four investigators, we pick Ludwig as the actual founder of modern physiology, the grounds for this must be justified specifically. That modern physiology is not to be contemplated without the works of the three great students of Johannes Muller is explicitly emphasized. However, Carl Ludwig occupies a special position for physiology. 相似文献
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Four Lactobacillus species, namely L. crispatus, L. iners, L. gasseri, and L. jensenii, commonly dominate the vaginal communities of most reproductive-age women. It is unclear why these particular species, and not others, are so prevalent. Historically, estrogen-induced glycogen production by the vaginal epithelium has been proffered as being key to supporting the proliferation of vaginal lactobacilli. However, the ‘fly in the ointment’ (that has been largely ignored) is that the species of Lactobacillus commonly found in the human vagina cannot directly metabolize glycogen. It would appear that this riddle has been solved as studies have demonstrated that vaginal lactobacilli can metabolize the products of glycogen depolymerization by α-amylase, and fortunately, amylase activity is found in vaginal secretions. These amylases are presumed to be host-derived, but we suggest that other bacterial populations in vaginal communities could also be sources of amylase in addition to (or instead of) the host. Here we briefly review what is known about human vaginal bacterial communities and discuss how glycogen-derived resources and resource competition might shape the composition and structure of these communities. 相似文献
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