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111.
112.
Spermatogenic cells of the prepuberal mouse: isolation and morphological characterization 总被引:62,自引:6,他引:56 下载免费PDF全文
AR Bellve JC Cavicchia CF Millette DA O'Brien YM Bhatnagar M Dym 《The Journal of cell biology》1977,74(1):68-85
A procedure is described which permits the isolation from the prepuberal mouse testis of highly purified populations of primitive type A spermatogonia, type A spermatogonia, type B spermatogonia, preleptotene primary spermatocytes, leptotene and zygotene primary spermatocytes, pachytene primary spermatocytes and Sertoli cells. The successful isolation of these prepuberal cell types was accomplished by: (a) defining distinctive morphological characteristics of the cells, (b) determining the temporal appearance of spermatogenic cells during prepuberal development, (c) isolating purified seminiferous cords, after dissociation of the testis with collagenase, (d) separating the trypsin-dispersed seminiferous cells by sedimentation velocity at unit gravity, and (e) assessing the identity and purity of the isolated cell types by microscopy. The seminiferous epithelium from day 6 animals contains only primitive type A spermatogonia and Sertoli cells. Type A and type B spermatogonia are present by day 8. At day 10, meiotic prophase is initiated, with the germ cells reaching the early and late pachytene stages by 14 and 18, respectively. Secondary spermatocytes and haploid spermatids appear throughout this developmental period. The purity and optimum day for the recovery of specific cell types are as follows: day 6, Sertoli cells (purity>99 percent) and primitive type A spermatogonia (90 percent); day 8, type A spermatogonia (91 percent) and type B spermatogonia (76 percent); day 18, preleptotene spermatocytes (93 percent), leptotene/zygotene spermatocytes (52 percent), and pachytene spermatocytes (89 percent), leptotene/zygotene spermatocytes (52 percent), and pachytene spermatocytes (89 percent). 相似文献
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Background
Scientific workflows improve the process of scientific experiments by making computations explicit, underscoring data flow, and emphasizing the participation of humans in the process when intuition and human reasoning are required. Workflows for experiments also highlight transitions among experimental phases, allowing intermediate results to be verified and supporting the proper handling of semantic mismatches and different file formats among the various tools used in the scientific process. Thus, scientific workflows are important for the modeling and subsequent capture of bioinformatics-related data. While much research has been conducted on the implementation of scientific workflows, the initial process of actually designing and generating the workflow at the conceptual level has received little consideration. 相似文献116.
Plant cell vacuoles may have storage or lytic functions, but biochemical markers specific for the tonoplasts of functionally distinct vacuoles are poorly defined. Here, we use antipeptide antibodies specific for the tonoplast intrinsic proteins alpha-TIP, gamma-TIP, and delta-TIP in confocal immunofluorescence experiments to test the hypothesis that different TIP isoforms may define different vacuole functions. Organelles labeled with these antibodies were also labeled with antipyrophosphatase antibodies, demonstrating that regardless of their size, they had the expected characteristics of vacuoles. Our results demonstrate that the storage vacuole tonoplast contains delta-TIP, protein storage vacuoles containing seed-type storage proteins are marked by alpha- and delta- or alpha- and delta- plus gamma-TIP, whereas vacuoles storing vegetative storage proteins and pigments are marked by delta-TIP alone or delta- plus gamma-TIP. In contrast, those marked by gamma-TIP alone have characteristics of lytic vacuoles, and results from other researchers indicate that alpha-TIP alone is a marker for autophagic vacuoles. In root tips, relatively undifferentiated cells that contain vacuoles labeled separately for each of the three TIPs have been identified. These results argue that plant cells have the ability to generate and maintain three separate vacuole organelles, with each being marked by a different TIP, and that the functional diversity of the vacuolar system may be generated from different combinations of the three basic types. 相似文献
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Jin-Oh You Dariela Almeda George JC Ye Debra T Auguste 《Journal of biological engineering》2010,4(1):15
For years, the field of drug delivery has focused on (1) controlling the release of a therapeutic and (2) targeting the therapeutic
to a specific cell type. These research endeavors have concentrated mainly on the development of new degradable polymers and
molecule-labeled drug delivery vehicles. Recent interest in biomaterials that respond to their environment have opened new
methods to trigger the release of drugs and localize the therapeutic within a particular site. These novel biomaterials, usually
termed "smart" or "intelligent", are able to deliver a therapeutic agent based on either environmental cues or a remote stimulus.
Stimuli-responsive materials could potentially elicit a therapeutically effective dose without adverse side effects. Polymers
responding to different stimuli, such as pH, light, temperature, ultrasound, magnetism, or biomolecules have been investigated
as potential drug delivery vehicles. This review describes the most recent advances in "smart" drug delivery systems that
respond to one or multiple stimuli. 相似文献
119.
Cytosolic isocitrate dehydrogenase in humans, mice, and voles and phylogenetic analysis of the enzyme family 总被引:3,自引:0,他引:3
Nekrutenko A; Hillis DM; Patton JC; Bradley RD; Baker RJ 《Molecular biology and evolution》1998,15(12):1674-1684
In this study, we report cDNA sequences of the cytosolic NADP-dependent
isocitrate dehydrogenase for humans, mice, and two species of voles
(Microtus mexicanus and Microtus ochrogaster). Inferred amino acid
sequences from these taxa display a high level of amino acid sequence
conservation, comparable to that of myosin beta heavy chain, and share
known structural features. A Caenorhabditis elegans enzyme that was
previously identified as a protein similar to isocitrate dehydrogenase is
most likely the NADP-dependent cytosolic isocitrate dehydrogenase enzyme
equivalent, based on amino acid similarity to mammalian enzymes and
phylogenetic analysis. We also suggest that NADP-dependent isocitrate
dehydrogenases characterized from alfalfa, soybean, and eucalyptus are most
likely cytosolic enzymes. The phylogenetic tree of various isocitrate
dehydrogenases from eukaryotic sources revealed that independent gene
duplications may have given rise to the cytosolic and mitochondrial forms
of NADP-dependent isocitrate dehydrogenase in animals and fungi. There
appears to be no statistical support for a hypothesis that the
mitochondrial and cytosolic forms of the enzyme are orthologous in these
groups. A possible scenario of the evolution of NADP-dependent isocitrate
dehydrogenases is proposed.
相似文献
120.
Caroline B Michielse Ringo van Wijk Linda Reijnen Ben JC Cornelissen Martijn Rep 《Genome biology》2009,10(1):R4-18