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81.
The genetic diversity of 159 representative genotypes of native hop (Humulus lupulus var. lupuloides E. Small, Cannabaceae) from 34 selected populations was assessed by relative magnitudes and ranges of alpha acids (AA), beta acids (BA), and the cohumulone (CoH) component of alpha acids, with reference to temporal changes between 1989-1990 and 2001, and to the same attributes in American and European hop cultivars, principally H. lupulus var. lupulus L. Chemical profiles of these genotypes were generated by high pressure liquid chromatography (HPLC) of methanol extracts from their processed samples (cones). The alpha ratio (AR, alpha acids / alpha+beta acids) measured the degree to which alpha acids predominated in cone extracts. Synchronous ranges of AR and CoH were also selected for graphic portrayals of native hop genotypic diversity. Cones sampled and analyzed from eight populations that were accessible in both 1989 and 2001 were distinct in chemical attributes, indicating a succession of genotypes, and suggesting temporal cycling of H. lupulus var.lupuloides germplasm. The principal distinctions between the two sub-species were a markedly higher proportion of CoH (38-88% vs. 19-41%) in alpha acids of H. l. var. lupuloides, and generally higher concentrations of AA in cultivars of both American and European commercial hop cultivars, predominantly H. lupulus var. lupulus. All of the 159 native hop genotypes also contained detectable levels of xanthohumol and xanthogalenol, prenylflavonoids recently reported to have mammalian anti-cancer activity. Some native genotypes had previously exhibited natural repellence of insect and mite pests; thus H. lupulus var. lupuloides germplasm offers a diverse resource of underutilized and yet undefined biochemicals. 相似文献
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Sex determination in the mammalian embryo begins with the activation of a gene on the Y chromosome which triggers a cascade of events that lead to male development. The mechanism by which this gene, designated SRY in humans and Sry in mice (sex determining region of the Y chromosome), is activated remains unknown. Likewise, the downstream target genes for Sry remain unidentified at present. C57BL mice carrying a Y chromosome from Mus musculus musculus or molossinus develop normally as males. In contrast, C57BL/6 mice with the Y chromosome from M. m. domesticus often show sex reversal, i.e., develop as XY females. It has been documented that C57BL mice with the Y chromosome from Poschiavinus (YPOS), a domesticus subtype, always develop as females or hermaphrodites. This suggests that a C57BL gene either up- or downstream of Sry is ineffective in interacting with Sry, which then compromises the processes that lead to normal male sex development. Nonetheless, by selective breeding, we have been able to generate a sex reversal-resistant C57BL/6-congenic strain of mice in which the XYPOS individuals consistently develop as normal males with bilateral testes. Because the resistance to sex reversal was transferred from strain 129S1/Sv (nonalbino) by simple selection over 13 backcross generations, it is inferred that a single autosomal gene or chromosomal region confers resistance to the sex reversal that would otherwise result. XYPOS normal males generated in these crosses were compared to XYPOS abnormal individuals and to C57BL/6 controls for sexual phenotype, gonadal weight, serum testosterone, and major urinary protein (MUP) level. A clear correlation was found among phenotypic sex, MUP level, and testis weight in the males and in the incompletely masculinized XYPOS mice. The fully masculinized males of the congenic strain resemble C57BL/6 males in the tested parameters. DNA analysis confirmed that these males, in fact, carry the YPOS
Sry gene. 相似文献
87.
Phosphorylation of simian virus 40 T antigen on Thr 124 selectively promotes double-hexamer formation on subfragments of the viral core origin
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Cell cycle-dependent phosphorylation of simian virus 40 (SV40) large tumor antigen (T-ag) on threonine 124 is essential for the initiation of viral DNA replication. A T-ag molecule containing a Thr-->Ala substitution at this position (T124A) was previously shown to bind to the SV40 core origin but to be defective in DNA unwinding and initiation of DNA replication. However, exactly what step in the initiation process is defective as a result of the T124A mutation has not been established. Therefore, to better understand the control of SV40 replication, we have reinvestigated the assembly of T124A molecules on the SV40 origin. Herein it is demonstrated that hexamer formation is unaffected by the phosphorylation state of Thr 124. In contrast, T124A molecules are defective in double-hexamer assembly on subfragments of the core origin containing single assembly units. We also report that T124A molecules are inhibitors of T-ag double hexamer formation. These and related studies indicate that phosphorylation of T-ag on Thr 124 is a necessary step for completing the assembly of functional double hexamers on the SV40 origin. The implications of these studies for the cell cycle control of SV40 DNA replication are discussed. 相似文献
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J. Barry III Whitney Aya Leder Jada Lewis Raymond A. Popp Chris Paszty Edward M. Rubin W. Ronald Shehee Tim M. Townes Oliver Smithies 《Biochemical genetics》1998,36(1-2):65-77
The hematology of the laboratory mouse has beenwell characterized. Normal genetic differences at thealpha- and beta-globin gene loci serve as useful markersfor a wide variety of types of experimental studies. There are a number of naturallyoccurring or induced mutations that disrupt globinexpression and produce thalassemic phenotypes. Inaddition, much has been learned of the workings of theglobin locus control region from studies of transgenicmice, including those with mutations induced by targetedsite-specific modifications. After a new mutation ortransgene has been created, it must be maintained in living mice, and the genotypes of theoffspring must be ascertained. While it is possible todetermine genotypes by DNA analyses, such assays aretime consuming and relatively expensive. An osmoticchallenge test -- originally developed for thegenotyping of large-deletion alpha-thalassemia mutationsin mice -- has proven useful in detecting bothsevere and milder alpha- and beta-thalassemias, as wellas some transgenic genotypes in mice carrying human globin genes.Reliable genotyping can, in some cases, be completedwithin a few minutes with minimal expense.Quantification of red cell fragility for a variety ofthalassemic and transgenic mice is described here, alongwith a simplified test suitable for rapid, routinegenotyping. The osmotic challenge test is perfectlyreliable for distinguishing genotypes that causesignificantly decreased release of hemoglobin from the redcells, but it is also useful for some of the conditionsin which overall erythrocyte osmotic fragility isessentially normal. 相似文献
89.
p300/CREB Binding Protein-Related Protein p270 Is a Component of Mammalian SWI/SNF Complexes 总被引:9,自引:5,他引:4
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90.
Carey E. Gleason N. Maritza Dowling Whitney Wharton JoAnn E. Manson Virginia M. Miller Craig S. Atwood Eliot A. Brinton Marcelle I. Cedars Rogerio A. Lobo George R. Merriam Genevieve Neal-Perry Nanette F. Santoro Hugh S. Taylor Dennis M. Black Matthew J. Budoff Howard N. Hodis Frederick Naftolin S. Mitchell Harman Sanjay Asthana 《PLoS medicine》2015,12(6)