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71.
Hepatitis B virus nucleocapsid particles do not cross the hepatocyte nuclear membrane in transgenic mice. 总被引:13,自引:10,他引:3 下载免费PDF全文
Transgenic mice that express the hepatitis B virus core protein were used to examine factors that influence the intracellular localization of nucleocapsid particles in the primary hepatocyte in vivo. In this model, viral nucleocapsid particles are strictly localized to the nucleus of the hepatocyte except when the nuclear membrane dissolves during cell division, at which time they enter the cytoplasm. The cytoplasmic nucleocapsid particles do not reenter the nucleus, however, when the nuclear membrane re-forms after cell division. The data support the notion that nucleocapsid particles can form de novo within the nucleus, and they suggest that performed nucleocapsid particles cannot be transported across the intact nuclear membrane in either direction. The results imply that nucleocapsid disassembly is probably required for entry of the hepadnaviral genome into the nucleus, and they question the role of the intranuclear viral nucleocapsid particle during the viral life cycle. 相似文献
72.
Summary
Coleus blumei cells were immobilized in a column reactor packed withLuffa cylindrica pieces. Medium was fed from the top of the column using a spray system and cells maintained high viability for 52 days. Cell
growth was slower but rosmarinic acid production was better compared to immobilized cells in the shake flasks. 相似文献
73.
G. León M. A. Martinez J. P. Etchegaray M. I. Vera J. Figueroa M. Krauskopf 《World journal of microbiology & biotechnology》1994,10(2):149-153
To obtain specific DNA probes for the identification of the fish pathogen, Renibacterium salmoninarum, a discriminatory recombinant DNA library was constructed using selective fragments of the bacterial genome. Three renibacterial clones, pMAM29, pMAM46 and pMAM77, containing 149, 73, and 154 bp respectively, were isolated and characterized. The specificity of the probes was confirmed by dot-blot and Southern hybridization analyses. Bacterial hybridization experiments revealed that pMAM29 discriminates the R. salmoninarum genome from that of other fish pathogens such as Aeromonas salmonicida, Yersinia ruckeri, Flexibacter columnaris, Lactobacillus piscicola, Vibrio ordalii, Vibrio anguillarum and Aeromonas hydrophila. Thus, this probe may provide a new means to diagnose bacterial kidney disease in asymptomatic fish and ova.The authors are with the instituto de Bioquímica, Universidad Austral de Chile, P.O. Box 567, Valdivia, Chile 相似文献
74.
Fish species composition before and after construction of a main stem reservoir on the White River,Colorado 总被引:3,自引:0,他引:3
Patrick J. Martinez Thomas E. Chart Melissa A. Trammell John G. Wullschleger Eric P. Bergersen 《Environmental Biology of Fishes》1994,40(3):227-239
Synopsis The completion in the fall of 1984 of Taylor Draw Dam on the White River, Colorado, formed Kenney Reservoir — thus impounding the last significant free-flowing tributary in the Upper Colorado River Basin. Fishes were sampled above and below the dam axis prior to closure of the dam and in the reservoir and river downstream following impoundment. While immediate effects of the dam to the ichthyofauna included blockage of upstream migration to 80 km of documented range for endangered Colorado squawfish, the reservoir also proved to have profound delayed effects on the river's species composition. Pre-impoundment investigations in 1983–1984 showed strong domination by native species above, within, and below the reservoir basin. By 1989–1990, non-native species comprised roughly 90% of the fishes collected in the reservoir and 80% of the fishes collected in the river below the dam. Initially, fathead minnow, whose numbers quickly increased in the new reservoir, dominated all post-impoundment collections, but red shiner became the most abundant fish collected in the river below the dam by 1989–1990. While agency stocking programs for the reservoir sought to emphasize a sport fishery for salmonids, primarily rainbow trout, local enthusiasm for warmwater sport fishes resulted in illicit transfers of these species from nearby impoundments. Several species, formerly rare or unreported in the White River in Colorado, including white sucker, northern pike, green sunfish, bluegill, largemouth bass and black crappie, were present in the river following impoundment. Our investigation indicates smaller-scale, main-stem impoundments that do not radically alter hydrologic or thermal regimes can still have a profound influence on native ichthyofauna by facilitating establishment and proliferation of nonnative species.Cooperators are the U.S. Fish and Wildlife, the Colorado Division of Wildlife, and Colorado State University 相似文献
75.
A. M. Bajo L. G. Guijarro M. G. Juarranz P. Valenzuela P. Martinez J. C. Prieto 《Bioscience reports》1993,13(2):69-77
Vasoactive intestinal peptide (VIP) has been shown to stimulate adenylyl cyclase activity in human endometrial membranes. The effect was dependent on the time and temperature of incubation as well as on the concentration of endometrial membrane proteins in the medium. In the presence of 1 M GTP, half-maximal stimulation of adenylyl cyclase activity was observed at 25.0±7.0 nM VIP, whereas the maximal activity (at 1 M VIP)corresponded to an increase of about 140% with respect to basal values (7.5±0.6 pmol cyclic AMP/min/mg of protein). However, the maximal stimulation of adenylyl cyclase activity was obtained with helodermin (1 M) that increased the activity by 170% over the basal. The relative potency of VIP-related peptides upon the adenylyl cyclase activity was: helodermin (ED50=1.8±1.4 nM)>VIP(ED50=25.0±7.0 nM)>PHI (ED50=725.0±127.2 nM). Secretin had a faint effect upon the adenylyl cyclase activity and glucagon was completely inefficient at this level. The presence of s and i subunits of G proteins in human endometrium was detected by immunoblot. Preliminary results showed the presence of two classes of125I-VIP receptors in human endometrial membranes with the following stoichoimetric parameters: high affinity receptor (Kd=2.0 nM, binding capacity 0.1 pmol VIP/mg protein) and low affinity receptor (Kd=0.43 M, binding capacity 13.1 pmol VIP/mg protein). The present results together with the known presence of VIP in human uterus and the actions of this neuropeptide in the adjacent myometrial tissue support the idea that VIP and related peptides may have a role in human endometrium. 相似文献
76.
77.
78.
Lucas Battisti Michele Potrich Everton Ricardi Lozano Claudia Bueno dos Reis Martinez Silvia Helena Sofia 《Journal of Applied Entomology》2023,147(1):1-18
Bees are declining worldwide, and the use of pesticides has been linked to this problem. Studies show that even herbicides can negatively impact bees, causing death or compromising health. As a result, concern about the use of glyphosate (GLY) has increased, as it is the most sold pesticide. Studies have shown that exposure of bees to GLY can trigger sublethal effects. Considering the speed with which information is published, reviews become important for the integration of knowledge, aiding understanding of the topic. Therefore, the present study aimed to review the literature on the sublethal effects of GLY and the different commercial formulations on bees. After the literary review, it was observed that the exposition, acute and chronic, of larvae and adults of social and solitary bees, to GLY and its formulations, can trigger alterations in gene expression, enzyme functioning, oxidative metabolism, cell/tissue structure, intestinal microbiota diversity, learning, food consumption, flight and vertical displacement capacity, circadian cycle and body development of these insects. The most used species in the studies was Apis mellifera L. Studies are still necessary to understand the sublethal effects of GLY on bees, in the medium and long term, on colony homeostasis, especially about the information on the toxicity of some surfactants present in the different commercial formulations. 相似文献
79.
K J Thompson J E Orfila P Achanta J L Martinez 《Cellular and molecular biology, including cyto-enzymology》2003,49(8):1281-1287
Affymetrix microarray technology was used to characterize whole-hippocampus gene expression associated with in vivo N-methyl-D-aspartate (NMDA)-R-independent long-term potentiation (LTP) in the mossy fiber (MF)-Cornus Ammonis (CA)3 pathway of adult male F344 rats. Acute MF responses were evoked by stimulation of the MF bundle and recorded in stratum lucidum of CA3. Following recording of baseline responses at 0.05 Hz, animals received either CPP (NMDA-R antagonist, 10 mg/kg) or naloxone (opioid-R antagonist, 10 mg/kg). LTP was induced by two 100 Hz 1-sec trains at the intensity sufficient to evoke 50% of the maximal response. Responses were collected for an additional hour. In controls, MF responses were collected at 0.05 Hz for 1 hr, but 100 Hz trains were not delivered. Hippocampi were harvested prior to total RNA isolation. Fragmented cRNA was hybridized to a rat U34 neurobiology array. F344 rats exhibited characteristic LTP in the presence of CPP and LTP blockade in the presence of naloxone. As a result, genes associated with both NMDA-independent LTP and naloxone-induced blockade were identified. These include genes involved in transmitter transport, intracellular messengers, growth factors and ion channels. Up-regulated include NMDA-R2D, neuropeptide Y (NPY), proenkephalin, BDNF and NGFR. Down-regulated genes include IGF-1 and GABA-B. 相似文献
80.
Ann-Christin Mörk Ailing Zhang J. Ricardo Martinez Godfried M. Roomans 《Histochemistry and cell biology》1996,105(4):297-303
Submandibular acinar cells of 1-day-old, 7-day-old, and adult rats were analyzed with X-ray microanalysis after stimulation with carbachol for different time periods (2–7 min). In unstimulated animals, marked differences in elemental content between compartments could be observed: secretory granules had a higher Ca and lower P and K content than other cell compartments. Comparison between different age groups showed significant differences for Ca, which increased with age in all compartments; Mg increased with age in the secretory granules and the apical cytoplasm. Only the glands from adult animals showed a significant effect of cholinergic stimulation: a transient decrease in Cl and K. The Cl concentration in the secretory granules decreased to 60% of the control value, which suggests that the granules release Cl upon stimulation. In young animals, no or little change in elemental distribution was observed after stimulation. This may indicate that Cl-secretion mechanisms are much less prominent in young animals. The ultrastructure of submandibular secretory granules depends on the preparation method: condensed and electrondense in freeze-substituted unfixed tissue, decondensed and more translucent in aldehyde-fixed tissue. This may indicate that the granules can transport water, and swell during the process of aldehyde fixation. 相似文献