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81.
To evaluate whether observed cycles in proceptive behavior in aging lowland gorilla females (age 40+) at Brookfield Zoo were driven by ovarian activity, we compared monthly behavioral data to estradiol and progestogen cycles based on fecal hormone assessments. Progestogen peaks showed regularity and close coincidence with monthly sexual behaviors. Estradiol was more variable. Progestogen peaks varied between 22+/-5 days for the control female (29 years old), to 24+/-2.5 and 29+/-8 for the two aged subjects. In the first aged female, which was housed with other females and a silverback, the high degree of cyclicity in sexual behavior, regularity of progestogen cycles, and close concordance between hormonal cycling and sexual behavior strongly compared to patterns found (in this and other studies) in gorilla females <35 years old. Cyclical progestogen peaks were longer and more variable in the second aged female-perhaps because she lacked the social mediation of other females or a male. For husbandry reasons she is not housed with the gorilla group, behavioral data were not collected from her. The value of our longitudinal study is in obtaining reproductive profiles of primate females that are approaching maximum lifespan. This pilot study is part of a larger research project on reproductive senescence that will include other captive females >35 years old, a population that is rapidly increasing in North American zoos as gorillas continue to age. 相似文献
82.
Genetic admixture of European FRDA genes is the cause of Friedreich ataxia in the Mexican population
Gómez M Clark RM Nath SK Bhatti S Sharma R Alonso E Rasmussen A Bidichandani SI 《Genomics》2004,84(5):779-784
Friedreich ataxia accounts for approximately 75% of European recessive ataxia patients. Approximately 98% of pathogenic chromosomes have large expansions of a GAA triplet repeat in the FRDA gene (E alleles), and strong linkage disequilibrium among polymorphisms spanning the FRDA locus indicates a common origin for all European E alleles. In contrast, we found that only 14 of 151 (9.3%) Mexican Mestizo patients with recessive ataxia were homozygous for E alleles. Analysis of polymorphisms spanning the FRDA locus revealed that all Mestizo E alleles had the common European haplotype, indicating that they share a single origin. Genetic admixture levels were determined, which revealed that the relative contributions to the Mestizo FRDA gene pool by Native American and European genes were 76-87% and 13-24%, respectively, commensurate with the observed low prevalence of Friedreich ataxia in Mestizos. This indicates that Friedreich ataxia in Mexican Mestizos is due to genetic admixture of European mutant FRDA genes in the Native American gene pool that existed prior to contact with Europeans. 相似文献
83.
Andersen GØ Skomedal T Enger M Fidjeland A Brattelid T Levy FO Osnes JB 《American journal of physiology. Heart and circulatory physiology》2004,286(4):H1354-H1360
We studied molecular and functional characteristics as well as hormonal regulation of the Na-K-2Cl cotransporter (NKCC) in the isolated rat heart and cardiomyocytes. NKCC activity was measured as bumetanide-sensitive (86)Rb(+) influx in isolated perfused rat hearts and isolated cardiomyocytes. Stimulation of alpha(1)-adrenoceptors (AR) by phenylephrine (30 microM) increased (86)Rb(+) influx. The NKCC inhibitor bumetanide (50 microM) reduced the response to phenylephrine by 45 +/- 13% (n = 12, P < 0.01). PD-98059 (10 microM), an inhibitor of the activation of the mitogen-activated protein kinases extracellular signal-regulated protein kinase 1 and 2 (ERK1/2), reduced the total response to phenylephrine by 51 +/- 13% (n = 10, P < 0.01) and eliminated the bumetanide-sensitive component, indicating that alpha(1)-AR mediated stimulation of NKCC is dependent on activation of ERK1/2. Inhibitors of protein kinase C or phosphatidylinositol 3-kinase had no effect. The presence of NKCC mRNA and protein was demonstrated in isolated rat cardiomyocytes. Phosphorylation of NKCC after alpha(1)-AR stimulation was shown by immunoprecipitation of the phosphoprotein from (32)P(i) prelabeled cardiomyocytes. Increased phosphorylation of the NKCC protein was also abolished by PD-98059. We conclude that the NKCC is present in rat cardiomyocytes and that ion transport by the cotransporter is regulated by alpha(1)-AR stimulation through phosphorylation of this protein involving the ERK pathway. 相似文献
84.
Protective vasodilation in response to tissue injury and acid back diffusion is associated with release of bradykinin in the rat stomach. We hypothesized that bradykinin might be involved in mechanisms behind such vasodilation via influence on mast cells and sensory neurons. Acid back diffusion after mucosal barrier disruption with hypertonic saline evoked degranulation of mast cells in the rat stomach wall. Acid back diffusion was also associated with increased luminal release of histamine and gastric blood flow in normal rats, but not in mast cell-deficient rats. Bradykinin (BK(2)) receptor blockade inhibited degranulation of submucosal mast cells in the stomach and attenuated gastric vasodilation both in response to acid back diffusion and after stimulation of sensory neurons with capsaicin. Gastric vasodilation caused by mucosal injury with hypertonic saline alone was associated with degranulation of mucosal mast cells. These events were unaffected by inhibition of prostaglandin synthesis, whereas bradykinin (BK(2)) receptor blockade was associated with abolished vasodilation and inhibition of mucosal mast cell degranulation. We conclude that bradykinin is involved in gastric vasodilation caused by hypertonic injury alone via influence on mast cells, and by acid back diffusion via influence on both sensory neurons and mast cells. 相似文献
85.
The growth and preference for utilisation of various sugar by the Penicillium species Penicillium pinophilum IBT 4186, Penicillium persicinum IBT 13226 and Penicillium brasilianum IBT 20888 was studied in batch cultivations using various monosaccharides as carbon source, either alone or in mixtures. P. pinophilum IBT 4186 and P. persicinum IBT 13226 had a micro(max) around 0.08-0.09 h(-1) using either glucose or xylose as carbon source. The micro(max) of P. brasilianum IBT 20888 was 0.16 and 0.14 h(-1) on glucose and xylose, respectively. Glucose was found to exert repression on the catabolism of mannose, galactose, xylose and arabinose. The three species were able to utilise all the tested monosaccharides, but arabinose was only slowly metabolised. Glucose was also found to repress the production of endoglucanases, endoxylanases and beta-xylosidases. After glucose depletion, the fungi started producing beta-glucosidase and endoglucanases. Xylose did not repress the enzyme production and it induced the production of endoxylanases and beta-xylosidases. 相似文献
86.
Blume A Ghaderi D Liebich V Hinderlich S Donner P Reutter W Lucka L 《Protein expression and purification》2004,35(2):387-396
UDP-GlcNAc 2-epimerase/ManNAc kinase is the key enzyme of sialic acid biosynthesis in mammals. Its functional expression is a prerequisite for early embryogenesis and for the synthesis of several cell recognition motifs in adult organism. This bifunctional enzyme is involved in the development of different diseases like sialuria or hereditary inclusion body myopathy. For a detailed understanding of the enzyme, large amounts of the pure active protein are needed. Different heterologous cell systems were therefore analyzed for the enzyme, which was found to be functionally expressed in Escherichia coli, the yeast strains Saccharomyces cerevisiae and Pichia pastoris, and insect cells. In all these cell types, the expressed enzyme displayed both epimerase and kinase activities. In E. coli, up to 2mg protein/l cell culture was expressed, in yeast cells only 0.4mg/L, while up to 100mg/L, were detected in insect cells. In all three cell systems, insoluble protein aggregates were also observed. Purification from E. coli resulted in 100microg/L pure and structurally intact protein. For insect cells, purification methods were established which resulted in up to 50mg/L pure, soluble, and active protein. In summary, expression and purification of the UDP-GlcNAc 2-epimerase/ManNAc kinase in Sf-900 cells can yield the milligram amounts of protein required for structural characterization of the enzyme. However, the easier expression in E. coli and yeast provides sufficient quantities for enzymatic and kinetic characterization. 相似文献
87.
Yeast lacking the SRO7/SOP1-encoded tumor suppressor homologue show increased susceptibility to apoptosis-like cell death on exposure to NaCl stress 总被引:7,自引:0,他引:7
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Yeast cells deleted for the SRO7/SOP1 encoded tumor suppressor homologue show increased sensitivity to NaCl stress. On exposure to growth-inhibiting NaCl concentrations, sro7Delta mutants display a rapid loss in viability that is associated with markers of apoptosis: accumulation of reactive oxygen species, DNA breakage, and nuclear fragmentation. Additional deletion of the yeast metacaspase gene YCA1 prevents the primary fast drop in viability and diminishes nuclear fragmentation and DNA breakage. We also observed that NaCl induced loss in viability of wild-type cells is Yca1p dependent. However, a yeast strain deleted for both SRO7 and its homologue SRO77 exhibits NaCl-induced cell death that is independent on YCA1. Likewise, sro77Delta single mutants do not survive better after additional deletion of the YCA1 gene, and both sro77Delta and sro77Deltayca1Delta mutants display apoptotic characteristics when exposed to growth-inhibiting salinity, suggesting that yeast possesses Yca1p-independent pathway(s) for apoptosis-like cell death. The activity of Yca1p increases with increasing NaCl stress and sro7Delta mutants achieve levels that are higher than in wild-type cells. However, mutants lacking SRO77 do not enhance caspase activity when subject to NaCl stress, suggesting that Sro7p and Sro77p exert opposing effects on the cellular activity of Yca1p. 相似文献
88.
Thioredoxin and glutathione systems are the major thiol-dependent redox systems in animal cells. They transfer via the reversible oxidoreduction of thiols the reducing equivalents of NADPH to numerous substrates and substrate reductases and constitute major defenses against oxidative stress. In this study, we cloned from the helminth parasite Echinococcus granulosus two trans-spliced mRNA variants that encode thioredoxin glutathione reductases (TGR). These variants code for mitochondrial and cytosolic selenocysteine-containing isoforms that possess identical glutaredoxin (Grx) and thioredoxin reductase (TR) domains and differ exclusively in their N termini. Western blot analysis of subcellular fractions with specific anti-TGR antibodies showed that TGR is present in both compartments. The biochemical characterization of the native purified TGR suggests that the Grx and TR domains of the enzyme can function either coupled or independently of each other, because the Grx domain can accept electrons from either TR domains or the glutathione system and the TR domains can transfer electrons to either the fused Grx domain or to E. granulosus thioredoxin. 相似文献
89.
FOXL2 and BPES: mutational hotspots,phenotypic variability,and revision of the genotype-phenotype correlation 总被引:15,自引:0,他引:15
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90.
Using (1)H NMR spectroscopy, the base-pair opening dynamics of an antiparallel foldback DNA triplex and the corresponding duplex has been characterized via catalyzed imino proton exchange. The triplex system was found to be in an equilibrium between a duplex and a triplex form. The exchange rate between the two forms (i.e., the on/off-rate of the third strand) was measured to be 5 s(-1) at 1 degrees C, and the base-pair dynamics of both forms were investigated separately. Both Watson-Crick and reverse Hoogsteen base pairs were found to have base-pair lifetimes in the order of milliseconds. The stability of the Watson-Crick base pairs was, however, substantially increased in the presence of the third strand. In the DNA triplex, the opening dynamics of the reverse Hoogsteen base pairs was significantly faster than the dynamics of the Watson-Crick pairs. We were able to conclude that, for both Watson-Crick and reverse Hoogsteen base pairs, spontaneous and individual opening from within the closed base triplet is the dominating opening pathway. 相似文献