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The metabolism of pregnenolone in subcellular fractions of the testes of the macaque (Macaca fascicularis) has been studied using capillary gas chromatography to characterize and quantify the metabolites, after their conversion into the O-methyloxime and/or trimethylsilyl ether derivatives. The microsomal incubations yielded the greatest quantities of metabolites, with lesser amounts in the mitochondrial fraction. The cytosolic fraction contained no significant quantity of metabolites after incubation, except for 5alpha-androst-16-en-3 beta-ol. This, and other odorous androst-16-enes, found in the microsomal fraction, are of particular interest in the context of animal communication because of their possible pheromonal role. Pregnenolone was converted into androst-5-ene-3 beta,17 beta-diol, androst-4-ene-3,17-dione and testosterone, suggesting that both classical pathways for testosterone synthesis were operating. Testosterone was further converted into 5 alpha-reduced androstanediols, especially in the microsomal fraction. 相似文献
4.
5.
Jan Klein Christophe Benoist Chella S. David Peter Demant Kirsten Fischer Lindahl Lorraine Flaherty Richard A. Flavell Ulrich Hämmerling Leroy E. Hood Stephen W. Hunt III Patricia P. Jones Philippe Kourilsky Hugh O. McDevitt Daniel Meruelo Donal B. Murphy Stanley G. Nathenson David H. Sachs Michael Steinmetz Susumu Tonegawa Edward K. Wakeland Elizabeth H. Weiss 《Immunogenetics》1990,32(3):147-149
6.
Mice bearing the H-2
bhaplotype are susceptible to the development of experimental autoimmune myasthenia gravis (EAMG), induced by acetylcholine receptor (AChR) autoimmunity. One of the genes influencing EAMG susceptibility has been mapped to the A
blocus of the major histocompatibility complex, and the A chain has been implicated in the pathogenesis. Mice of the H-2
bhaplotype, including C57BL/10 (B10), have a genomic deletion of the E
gene and therefore fail to express the E molecule on their cell surface. To test the hypothesis that failure to express the cell surface E molecule in B10 mice contributes to EAMG pathogenesis, E
inf
supk
transgenic B10 mice expressing the T molecule were examined. Expression of the E molecule in E
inf
supk
transgenic B10 mice partially prevented the development of EAMG. 相似文献
7.
8.
Expression of HLA-B27 in transgenic mice is controlled by gene(s) mapping between H-2D and H-2L loci 总被引:2,自引:0,他引:2
The level of HLA-B27 transgene expression on the cell surface is dependent on the host H-2 haplotype. Mice homozygous for the H-2
b
, H-2
f
, H-2
f
, H-2
p
, H-2
r
, and H-2
k
haplotypes express B27 at high levels. An intermediate level of B27 expression is observed in H-2
v
mice whereas low levels of B27 are expressed in H-2
q
and H-2
d
mice. The decreased expression of B27 maps to the D region of the major histocompatibility complex. Recombinant strain B10.RKDB (DdLb) mapped the low expression gene centromeric to H-2L. In order to determine the low expression within the H-2D region, the B27 transgene was introduced into B10.D2-H-2
dm1
and BALB/c-H-2
dm2
mice. Expression of B27 in both of these strains was high indicating that neither H-2D
d
nor H-2L
d
is responsible for the low expression. This maps the effect between the H-2D and H-2L loci. In addition, introduction of human 2-microglobulin (2m) into B10.D2-B27 transgenic mice caused a marked enhancement of B27 expression on the cell surface suggesting that the defect in B27 expression in certain haplotypes is due to an inability of B27 to associate with endogenous mouse 2m. We propose that gene(s) mapping between D and L (either D2, D3, D4, or some as yet unidentified gene) may be involved in class I assembly by helping association of 2m with class I. This putative molecule, designated Assembly Enhancer (AE) might have a negative influence in the association between human class II and mouse 2m. 相似文献
9.
The polyamines stimulated tyrosine hydroxylase in whole homogenates of bovine caudate nuclei approximately 2 fold. TheV
max forl-tyrosine increased by 2.3 fold while theK
m
s forl-tyrosine and for the cofactor (DMPH4) were unchanged.l-Aromatic amino acid decarboxylase from whole rat brain homogenate was stimulated by about 40% in the presence of polyamines. These findings suggest that increased polyamine levels associated with increased cellular synthetic activity can modify the synthesis of neurotransmitters. 相似文献
10.
Abstract— It has been reported that myelin basic protein (MBP) forms a specific complex with S-100 protein in the presence of either Ca2+ or Mn2+, as detected by Immunoelectrophoresis. We have now studied the binding of Ca2+ and Mn2+ to these two proteins. We find that MBP binds 1 mol of Mn2+/mol of protein, and this binding produces an increment in its fluorescence, indicating a conformational change. Ca2+ does not bind to MBP nor does it affect the fluorescence of MBP. S-100 protein, as has been reported, binds about 10 mol of Ca2+/mol and this binding produces a conformational change. S-100 protein also has 25 binding sites for Mn2+, but this binding does not alter fluorescence and does not appear to affect conformation. Competitive binding experiments demonstrate that the binding sites of S-100 protein for Ca2+ and Mn2+ are independent. The alteration of electrophoretic migration in gels of S-100 protein produced by Ca2+ and of MBP produced by Mn2+ are in accord with the observations based on fluorescence. Mn2+ does not affect the electrophoretic mobility of S-100. These results indicate that the formation of the complex between MBP and S-100 protein in the presence of either Ca2+ or Mn2+ is due to the conformational change induced by these ions in S-100 protein, MBP, or both. 相似文献