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91.
A genomic library of partially EcoRI-digested DNA from the lesser snow
goose, Anser caerulescens caerulescens, was constructed in the phage vector
Charon 4. Phage containing only unique sequences were identified by
screening plaques with 32P-labeled genomic DNA. Restriction-fragment-
length polymorphisms (RFLPs) were identified by probing DNA from 11-13 male
birds from the breeding colony at La Perouse Bay. Of the 17 probes
examined, all detected RFLPs with at least one of EcoRi, HindIII, Msp1, and
Taq1. Several of them identified highly variable regions with multiple
alleles. These RFLPs are valuable DNA markers that can be used for (1) the
examination of DNA variation, relatedness, and genetic distance and (2)
assessing paternity and maternity. These data suggest that there are higher
levels of variation of DNA sequence in birds than had previously been
thought to exist.
相似文献
92.
Summary The distribution of lymph vessels in the human testis was investigated using ink injection methods, and light and electron microscopy. Lymph capillaries occur in the septula testis but are absent in the intertubular tissue. They consist of endothelial cells provided with an incomplete basal lamina and anchoring filaments of the adjacent connective tissue. Frequently, the endothelial cells are separated by gaps measuring up to 2m. The lymph capillaries of the septula testis are connected to lymph vessels in the rete testis and tunica albuginea. These vessels have occasional smooth muscle cells and valves. At the posterior margin of the testis, the network of lymph vessels merges into collecting ducts, which together with vessels derived from the rete testis are drained by the lymphatic system in the spermatic cord.Dedicated to Prof. Henriette Oboussier, Hamburg, on the occasion of her 65th birthday 相似文献
93.
Multiple forms of tubulin in the cytoskeletal and flagellar microtubules of polytomella 总被引:14,自引:9,他引:5 下载免费PDF全文
The alga polytomella contains several organelles composed of microtubules, including four flagella and hundreds of cytoskeletal microtubules. Brown and co-workers have shown (1976. J. Cell Biol. 69:6-125; 1978, Exp. Cell Res. 117: 313-324) that the flagella could be removed and the cytoskeletans dissociated, and that both structures could partially regenerate in the absence of protein synthesis. Because of this, and because both the flagella and the cytoskeletons can be isolated intact, this organism is particularly suitable for studying tubulin heterogeneity and the incorporation of specific tubulins into different microtubule-containing organelles in the same cell. In order to define the different species of tubulin in polytonella cytoplasm, a (35)S- labeled cytoplasmic fraction was subjected to two cycles of assembly and disassembly in the presence of unlabeled brain tubulin. Comparison of the labeled polytomella cytoplasmic tubulin obtained by this procedure with the tubulin of isolated polytomella flagella by two-dimensional gel electrophoresis showed that, whereas the β-tubulin from both cytoplasmic and flagellar tubulin samples comigrated, the two α-tubulins had distinctly different isoelectic points. As a second method of isolating tubulin from the cytoplasm, cells were gently lysed with detergent and intact cytoskeletons obtained. When these cytoskeletons were exposed to cold temperature, the proteins that were released were found to be highly enriched in tubulin; this tubulin, by itself, could be assembled into microtubules in vitro. The predominant α-tubulin of this in vitro- assembled cytoskeletal tubulin corresponded to the major cytoplasmic α-tubulin obtained by coassembly of labeled polytomella cytoplasmic extract with brain tubulin and was quite distinct from the α-tubulin of purified flagella. These results clearly show that two different microtubule-containing organelles from the same cell are composed of distinct tubulins. 相似文献
94.
Effect of ML-236B (compactin) on biliary excretion of bile salts and lipids, and on bile flow, in the rat 总被引:2,自引:0,他引:2
H J Kempen J De Lange M P Vos-Van Holstein P Van Wachem R Havinga R J Vonk 《Biochimica et biophysica acta》1984,794(3):435-443
To assess the importance of de novo cholesterol synthesis for bile salt formation, the effects of ML-236B (an inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme A reductase) on biliary excretion of bile salts and lipids were studied in rats with permanent catheters in bile duct, heart and duodenum. In rats having their bile diverted continuously for 8 days, duodenal administration of ML-236B (50 mg/kg) caused an immediate transient choleresis, which subsided after 2 h. Concomitant with the choleresis concentrations of bile salt, phospholipid and cholesterol fell, but this decrease was maintained for 6 h. Consequently, ML-236B inhibited biliary output salts and lipids from the second till the sixth hour after injection. The kinetics of biliary excretion of intravenously injected [14C]taurocholate were not affected by ML-236B administration. In rats having their biliary catheter connected to the duodenal catheter, or in rats with prolonged bile diversion but treated with mevalonolactone, ML-236B again caused a transient choleresis (having subsided after 2 h), but now did not affect biliary excretion of bile salts and lipids. It is concluded that (1) ML-236B causes a transient bile salt-independent choleresis, (2) ML-236B depresses excretion of bile salts and lipids by blocking mevalonate synthesis and not by blocking the bile salt or lipid transport, (3) biliary excretions of phospholipids and cholesterol partly depend on excretion of bile salt, and (4) in rats with a prolonged total bile diversion newly formed mevalonate is a major substrate for bile salt synthesis. 相似文献
95.
Summary The ultrastructure of the lamina propria of human seminiferous tubules was analyzed in normal specimens and compared to biopsies showing great thickenning of this area in light microscopy.The contractile cells are stellate in shape, the intercellular gaps between their branchings being less than 150 Å. The cytoplasmic features of these cells are similar to those described by Ross and Long (1966) and do not differ significantly in the pathological cases examined.The intercellular components, namely collagen fibers, microfibrils and an incomplete basement membrane-like coating of the contractile cells, are strikingly increased in the thickenned lamina propria, although the number of layers making up this structure needs not be increased. Occasionally, the intercellular space is occupied by only one of these materials.The distribution of collagen permits identification of two main patterns in the thickenned lamina propria: a) one where the basement membrane of the seminiferous epithelium is separated from the first layer of contractile cells by a wide collagen zone, and b) another case where the layer displaying greater thickness because of increased collagen deposition is located further away from the germinal epithelium.The functional activity of the contractile cells, the physiological implication of structural alterations of the lamina propria and the necessity to correlate these observations to andrological findings, are discussed.Presented in part at the 68. Meeting of the Anatomische Gesellschaft, Lausanne, April 1973.Fellow of the Alexander von Humboldt Foundation, on leave of absence from Depto. de Biología y Genética, Sede Norte, Universidad de Chile, Santiago.Supported by Grants from the Deutsche Forschungsgemeinschaft. 相似文献
96.
Meeting cholera's challenge to Haiti and the world: a joint statement on cholera prevention and care
Farmer P Almazor CP Bahnsen ET Barry D Bazile J Bloom BR Bose N Brewer T Calderwood SB Clemens JD Cravioto A Eustache E Jérôme G Gupta N Harris JB Hiatt HH Holstein C Hotez PJ Ivers LC Kerry VB Koenig SP Larocque RC Léandre F Lambert W Lyon E Mekalanos JJ Mukherjee JS Oswald C Pape JW Gretchko Prosper A Rabinovich R Raymonville M Réjouit JR Ronan LJ Rosenberg ML Ryan ET Sachs JD Sack DA Surena C Suri AA Ternier R Waldor MK Walton D Weigel JL 《PLoS neglected tropical diseases》2011,5(5):e1145
97.
Zheng W Watts LT Holstein DM Prajapati SI Keller C Grass EH Walter CA Lechleiter JD 《PloS one》2010,5(12):e14401
Treatments to improve the neurological outcome of edema and cerebral ischemic stroke are severely limited. Here, we present the first in vivo single cell images of cortical mouse astrocytes documenting the impact of single vessel photothrombosis on cytotoxic edema and cerebral infarcts. The volume of astrocytes expressing green fluorescent protein (GFP) increased by over 600% within 3 hours of ischemia. The subsequent growth of cerebral infarcts was easily followed as the loss of GFP fluorescence as astrocytes lysed. Cytotoxic edema and the magnitude of ischemic lesions were significantly reduced by treatment with the purinergic ligand 2-methylthioladenosine 5' diphosphate (2-MeSADP), an agonist with high specificity for the purinergic receptor type 1 isoform (P2Y(1)R). At 24 hours, cytotoxic edema in astrocytes was still apparent at the penumbra and preceded the cell lysis that defined the infarct. Delayed 2MeSADP treatment, 24 hours after the initial thrombosis, also significantly reduced cytotoxic edema and the continued growth of the brain infarction. Pharmacological and genetic evidence are presented indicating that 2MeSADP protection is mediated by enhanced astrocyte mitochondrial metabolism via increased inositol trisphosphate (IP(3))-dependent Ca(2+) release. We suggest that mitochondria play a critical role in astrocyte energy metabolism in the penumbra of ischemic lesions, where low ATP levels are widely accepted to be responsible for cytotoxic edema. Enhancement of this energy source could have similar protective benefits for a wide range of brain injuries. 相似文献
98.
A. F. Holstein M. S. Davidoff H. Breucker N. Countouris G. Orlandini 《Cell and tissue research》1991,264(1):23-32
Summary The distal segment of the human male urethra, in particular the fossa navicularis, was studied with light- and electron microscopy as well as by means of histochemical and immunocytochemical methods. The fossa navicularis of the urethra contains a circumscribed zone of extremely thick, non-keratinized stratified squamous epithelium composed of cells containing a large amount of glycogen. These cells lack acid phosphatase activity and lysozyme-like immunoreactivity, both of which can be demonstrated to varying extents in the other zones of the distal male urethra. These glycogen-rich cells are considered to be the substrate for an endogenous flora of lactobacteria, whereas the acid-phosphatase activity and the lysozyme-like immunoreactivity indicate the presence of macrophages and the secretion of bactericidal agents at the epithelial surface. These observations suggest that the different zones with heterogeneous properties in the distal male urethra probably represent a defense system against the invasion of pathogenic microorganisms. Moreover, the glycogen-rich zone, which resembles the glycogen-rich epithelium of the vagina, is estrogen-dependent. This is demonstrated in cases of sex reversal in which after long-lasting estrogen treatment the glycogen-rich zone becomes extremely extended by displacement of the neighbouring epithelium. 相似文献
99.
We have analyzed the cell cycle parameters of interstitial cells in Hydra oligactis. Three subpopulations of cells with short, medium, and long cell cycles were identified. Short-cycle cells are stem cells; medium-cycle cells are precursors to nematocyte differentiation; long-cycle cells are precursors to gamete differentiation. We have also determined the effect of different cell densities on the population doubling time, cell cycle length, and cell size of interstitial cells. Our results indicate that decreasing the interstitial cell density from 0.35 to 0.1 interstitial cells/epithelial cell (1) shortens the population doubling time from 4 to 1.8 days, (2) increases the [3H]thymidine labeling index from 0.5 to 0.75 and shifts the nuclear DNA distribution from G2 to S phase cells, and (3) decreases the length of G2 in stem cells from 6 to 3 hr. The shortened cell cycle is correlated with a significant decrease in the size of interstitial stem cells. Coincident with the shortened cell cycle and increased growth rate there is an increase in stem cell self-renewal and a decrease in stem cell differentiation. 相似文献
100.
Previous studies have demonstrated that cGMP is produced by nitric oxide-mediated activation of soluble guanylyl cyclase (sGC) in seminiferous tubules of the human testis. It is not known, however, whether carbon monoxide (CO), another activator of sGC, is also involved in testicular function. To address this issue, testicular probes from 65- to 75-yr-old men have been examined. The CO-generating enzyme, heme oxygenase-1 (HO-1), could be localized by immunohistochemical and immunoblot analyses to Sertoli cells. In these cells, HO-1 is detectable in adluminal cell compartments, whereas sGC immunoreactivity is distributed exclusively in basal compartments. Treatments of isolated tubules with either sodium arsenite, known to induce HO-1, or hematin, an HO substrate, resulted in 4.4- and 1.8-fold, respectively, increases in cGMP levels. ODQ, a specific sGC inhibitor, inhibited completely the sodium arsenite-stimulated cGMP production. Moreover, the HO inhibitor zinc protoporphyrin-IX and the CO scavenger hemoglobin both significantly reduced (77% or 46% of control, respectively) tubular cGMP generation. These findings, demonstrating for the first time a link between HO-1 activity in Sertoli cells and sGC-dependent cGMP production in seminiferous tubules, suggest a functional role of CO in the human testis. 相似文献