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101.
Orihuela PA Parada-Bustamante A Cortés PP Gatica C Croxatto HB 《Biology of reproduction》2003,68(4):1225-1231
This investigation examined the role of estrogen receptor (ER) on the stimulatory effect of estradiol (E2) on protein phosphorylation in the oviduct as well as on E2-induced acceleration of oviductal oocyte transport in cyclic rats. Estrous rats were injected with E2 s.c. and with the ER antagonist ICI 182 780 intrabursally (i.b.), and 6 h later, oviducts were excised and protein phosphorylation was determined by Western blot analysis. ICI 182 780 inhibited the E2-induced phosphorylation of some oviductal proteins. Other estrous rats were treated with E2 s.c. and ICI 182 780 i.b. The number of eggs in the oviduct, assessed 24 h later, showed that ICI 182 780 blocked the E2-induced egg transport acceleration. The possible involvement of adenylyl cyclase, protein kinase A (PK-A), protein kinase C (PK-C), or tyrosine kinases on egg transport acceleration induced by E2 was then examined. Selective inhibitors of adenylyl cyclase or PK-A inhibited the E2-induced egg transport acceleration, whereas PK-C or tyrosine kinase inhibitors had no effect. Furthermore, forskolin, an adenylyl cyclase activator, mimicked the effect of E2 on ovum transport and E2 increased the level of cAMP in the oviduct of cycling rats. Finally, we measured PK-A activity in vitro in the presence of E2 or E2-ER complex. Activity of PK-A in the presence of E2 or E2-ER was similar to PK-A alone, showing that E2 or E2-ER did not directly activate PK-A. We conclude that the nongenomic pathway by which E2 accelerates oviductal egg transport in the rat requires absolute participation of ER and cAMP and partial participation of PK-A signaling pathways in the oviduct. 相似文献
102.
Naveira HF 《Genetica》2003,118(1):41-50
The modern theory of speciation assigns a prominent role to the recessivity of genetic incompatibilities in the two rules of speciation, namely Haldane's rule and the large X effect, and considers that the contribution of faster evolution of the X versus the autosomes to those patterns is generally of relatively minor importance. By extending Turelli and Orr's previous analysis of the model of two-locus Dobzhansky–Muller incompatibilities, I first show that when the X and the autosomes evolve at the same rate, the two dominance parameters involved in that model are not equally important for the declaration of a large X effect, but that the degree of recessivity of homozygous–homozygous incompatibilities is the major determinant for such a declaration. When the X evolves faster than the autosomes, the model obviously predicts that the importance of both dominance parameters will progressively vanish. It is then of importance to obtain estimates of the relative evolutionary rate of X-linked incompatibility loci. Several different procedures to obtain such estimates from the perspective of the large X effect are suggested. The application of the appropriate test to the only suitable data from Drosophila hybridizations so far available leads to the conclusion that the X actually evolves at least 2.5 times faster than the autosomes, as far as hybrid male sterility determinants are concerned, thus making dominance considerations absolutely irrelevant. Notwithstanding the necessity of further tests, the relative roles currently assigned to faster-X evolution and dominance in the theory of speciation should be revised, giving due prominence to faster-X evolution, at least for hybrid male sterility in the genus Drosophila. 相似文献
103.
104.
Proline oxidase is a p53-induced gene that can mediate apoptosis in lung carcinoma cells. Here, we provide evidence implicating a role for proline oxidase in renal carcinoma. We observed absent or reduced expression of proline oxidase in 8 of 12 primary renal cell carcinomas, with respect to their normal tissue counterparts. Two renal cell carcinomas, which displayed little or no expression of proline oxidase, expressed p53s that were less capable of inducing proline oxidase than p53 isolated from normal renal tissue. One of those tumor-derived p53s contained a double transition mutation at amino acid residues 125 (Ala to Thr) and 193 (Arg to His), and the other exhibited a single transition mutation at amino acid 149 (Ser to Phe). Forced up-regulation of proline oxidase induced the formation of reactive oxygen species and mediated apoptosis in the 786-0 renal cell carcinoma cell line. A proline oxidase antisense vector repressed p53-induced up-regulation of proline oxidase, release of cytochrome c from mitochondria, and apoptosis in 786-0 renal carcinoma cells. Taken together, these findings support a role for proline oxidase as a downstream effector in p53-mediated apoptosis. We hypothesize that its altered expression can contribute to the development of renal carcinomas. The presence of proline oxidase in mitochondria, a primary organelle that regulates apoptosis, places this molecule in a subcellular localization that can directly influence the apoptotic pathway and thus tumorigenesis. 相似文献
105.
106.
Pirpignani ML Rivera E Hellman U Biscoglio de Jiménez Bonino M 《Archives of biochemistry and biophysics》2002,407(2):224-230
Vespid venoms contain Antigen 5, an important allergen whose primary structure and immunological behavior have been extensively studied from venoms of vespids of the Northern Hemisphere. We report herein structural and immunological aspects of Antigen 5 from Polybia scutellaris subspecies rioplatensis (vulgar name: camoati) found in South America. Mast cell degranulation, histamine release, and IgE induction experiments performed in mice allow us to suggest that P. scutellaris Antigen 5 is a variant with reduced IgE response and anaphylactic activity. Sequence data indicate that the protein has a 72.5-90.3% similarity to that of members of the vespid Antigen 5 family with an already known primary structure. Moreover, results suggest that the protein-a new member of an extracellular protein superfamily-could be a good candidate for immunotherapy related to vespid allergy. 相似文献
107.
Horizontal gene transfer in microbial genome evolution 总被引:1,自引:0,他引:1
Horizontal gene transfer is the collective name for processes that permit the exchange of DNA among organisms of different species. Only recently has it been recognized as a significant contribution to inter-organismal gene exchange. Traditionally, it was thought that microorganisms evolved clonally, passing genes from mother to daughter cells with little or no exchange of DNA among diverse species. Studies of microbial genomes, however, have shown that genomes contain genes that are closely related to a number of different prokaryotes, sometimes to phylogenetically very distantly related ones. (Doolittle et al., 1990, J. Mol. Evol. 31, 383-388; Karlin et al., 1997, J. Bacteriol. 179, 3899-3913; Karlin et al., 1998, Annu. Rev. Genet. 32, 185-225; Lawrence and Ochman, 1998, Proc. Natl. Acad. Sci. USA 95, 9413-9417; Rivera et al., 1998, Proc. Natl. Acad. Sci. USA 95, 6239-6244; Campbell, 2000, Theor. Popul. Biol. 57 71-77; Doolittle, 2000, Sci. Am. 282, 90-95; Ochman and Jones, 2000, Embo. J. 19, 6637-6643; Boucher et al. 2001, Curr. Opin., Microbiol. 4, 285-289; Wang et al., 2001, Mol. Biol. Evol. 18, 792-800). Whereas prokaryotic and eukaryotic evolution was once reconstructed from a single 16S ribosomal RNA (rRNA) gene, the analysis of complete genomes is beginning to yield a different picture of microbial evolution, one that is wrought with the lateral movement of genes across vast phylogenetic distances. (Lane et al., 1988, Methods Enzymol. 167, 138-144; Lake and Rivera, 1996, Proc. Natl. Acad. Sci. USA 91, 2880-2881; Lake et al., 1999, Science 283, 2027-2028). 相似文献
108.
Marques S Barros-Battesti DM Faccini JL Onofrio VC 《Memórias do Instituto Oswaldo Cruz》2002,97(8):1141-1146
Amblyomma varium, commonly known in Brazil as the "carrapato-gigante-da-pregui a" (sloth's giant tick) is found from southern Central America to Argentina. The present study adds information on the geographical distribution of A. varium, as well as on their hosts, based on material deposited in the main Brazilian collections and on the available literature. Eighty-two vials, containing 191 adult specimens, deposited in five Acari collections between 1930 and 2001, were examined. These vials included data on the host and collection localities. The biology of A. varium is unknown. However it is known that, during the adult stage, the tick presents a high host specificity and is found almost exclusively on the sloths Bradypus tridactylus, B. variegatus, B.torquatus (Bradypodidae), Choloepus hoffmanni and C. didactylus (Megalonychidae). Based on the material examined, the states of Rond nia, Amazonas, Bahia and Alagoas are newly assigned to geographic distribution of A. varium in Brazil. 相似文献
109.
Detection of viral DNA and immune responses to the human herpesvirus 6 101-kilodalton virion protein in patients with multiple sclerosis and in controls 总被引:6,自引:0,他引:6 下载免费PDF全文
Tejada-Simon MV Zang YC Hong J Rivera VM Killian JM Zhang JZ 《Journal of virology》2002,76(12):6147-6154
Human herpesvirus 6 (HHV-6), a latent lymphotropic and neurotropic virus, has been suspected as an etiologic agent in multiple sclerosis (MS). The study was undertaken to correlate virologic evidence for HHV-6 activity with the state of host immunity to HHV-6 in MS patients and control subjects. The study revealed that cell-free DNA of HHV-6 was detected more frequently in both serum and cerebrospinal fluid of MS patients than in those of control subjects. T cells recognizing the recombinant 101-kDa protein (101K) corresponding to the major immunoreactive region unique to HHV-6 occurred at significantly lower precursor frequency in MS patients than in control subjects. The resulting HHV-6-specific T-cell lines obtained from MS patients exhibited skewed cytokine profiles characterized by the inability to produce interleukin-4 (IL-4) and IL-10. The decreased T-cell responses to HHV-6 and the altered cytokine profile were consistent with significantly declined serum immunoglobulin G (IgG) titers for HHV-6 of MS patients compared to those of control subjects. In contrast, elevated serum IgM titers for HHV-6 were detected in the majority of MS patients, which may reflect frequent exposure of B cells to HHV-6. The findings suggest that the decreased immune responses to HHV-6 may be responsible for ineffective clearance of HHV-6 in MS patients. 相似文献
110.
Origin of human immunodeficiency virus type 1 quasispecies emerging after antiretroviral treatment interruption in patients with therapeutic failure 下载免费PDF全文
Kijak GH Simon V Balfe P Vanderhoeven J Pampuro SE Zala C Ochoa C Cahn P Markowitz M Salomon H 《Journal of virology》2002,76(14):7000-7009
The emergence of antiretroviral (ARV) drug-resistant human immunodeficiency virus type 1 (HIV-1) quasispecies is a major cause of treatment failure. These variants are usually replaced by drug-sensitive ones when the selective pressure of the drugs is removed, as the former have reduced fitness in a drug-free environment. This was the rationale for the design of structured ARV treatment interruption (STI) studies for the management of HIV-1 patients with treatment failure. We have studied the origin of drug-sensitive HIV-1 quasispecies emerging after STI in patients with treatment failure due to ARV drug resistance. Plasma and peripheral blood mononuclear cell samples were obtained the day of treatment interruption (day 0) and 30 and 60 days afterwards. HIV-1 pol and env were partially amplified, cloned, and sequenced. At day 60 drug-resistant variants were replaced by completely or partially sensitive quasispecies. Phylogenetic analyses of pol revealed that drug-sensitive variants emerging after STI were not related to their immediate temporal ancestors but formed a separate cluster, demonstrating that STI leads to the recrudescence and reemergence of a sequestrated viral population rather than leading to the back mutation of drug-resistant forms. No evidence for concomitant changes in viral tropism was seen, as deduced from env sequences. This study demonstrates the important role that the reemergence of quasispecies plays in HIV-1 population dynamics and points out the difficulties that may be found when recycling ARV therapies with patients with treatment failure. 相似文献