Alpha tocopherol control of sexuality and polymorphism in the rotifer Asplanchna   总被引：1，自引：0，他引：1  

J J Gilbert  G A Thompson 《Science (New York, N.Y.)》1968,159(816):734-736

A dietary component that initiates both the tranisition from parthenogenetic to sexual reproduction and the production of lateral, posterodorsal, and posterior outgrowths of the body wall of females was isolated from the neutral lipids of dried grass and identified as (alpha)-tocopherol. The smallest concentrations eliciting both responses were below 100 nanograms per milliliter. Relative activities of (alpha)-, beta3-, and (gamma)-tocopherol and (alpha)-tocopheryl-quinone were roughly 100 : 100 : 20 : 0.4. The synthetic antioxidants tested were without activity.  相似文献   

Esterase 6 and reproduction in Drosophila melanogaster   总被引：8，自引：0，他引：8  

R C Richmond  D G Gilbert  K B Sheehan  M H Gromko  F M Butterworth 《Science (New York, N.Y.)》1980,207(4438):1483-1485

A nonspecific carboxylesterase (esterase 6) of Drosophila melanogaster shows greater activity in adult males than in females and is highly concentrated in the anterior ejaculatory duct of the reproductive tract of the male. Esterase 6 is depleted in males by copulation and is transferred to females early during copulation as a component of the seminal fluid. That esterase 6 may be involved in a system controlling the timing of remating is suggested by differences in the activity of this enzyme in a strain of Drosophila selected for a decrease in time to remating and by differences in the timing of remating in females initially inseminated by males lacking or having active esterase 6.  相似文献   

从芸薹属作物同工酶和蛋白质表型差异探讨杂种优势机理     

范淑英  吴才君  曲雪艳  成广杰  王家辉  乐建刚  夏华英 《江西农业大学学报》2006,28(3):323-326

以芸薹种(Brassica campestrisL.,syn.B.rapaL.)的3个亚种,即白菜(B.campestrisL.ssp.chinensisM ak ino)、大白菜(B.campestrisssp.pekinensisO lsson)和芜菁(B.campestrisssp.rapifera(Matzg.)S insk)等芸薹作物为研究材料,对其杂种优势形成进行同工酶和蛋白质分析,结果表明:不同品种在同一生育期或同一品种在不同生育期酶谱和蛋白质表型有差异,但把各品种不同生育期的谱带叠加,所得到的总谱带是相同的;品种间杂交其F1的同工酶和蛋白质谱带不存在“杂种带”或“互补带”;酶谱和蛋白质表型上的差异,可能是芸薹属作物杂种优势产生的生理基础之一。  相似文献   

六偏磷酸钠对魔芋葡甘聚糖干法改性研究   总被引：17，自引：0，他引：17  

庞杰  孙远明  乐学义  刘佩瑛 《西南大学学报(自然科学版)》2000,22(1):59-61

用六偏磷酸钠对魔芋葡甘聚糖进行干法改性。结果表明,反应最佳条件为六偏磷酸钠：魔芋葡甘聚糖＝１：８（Ｗ／Ｗ）,在ｐＨ１,５５℃反应１．５ｈ。其透明度,粘度,冻融稳定性均比对照明显改善;水溶胶具有一定的耐酸、耐高温能力,具有相当的抑菌效果。  相似文献   

B lineage--specific interactions of an immunoglobulin enhancer with cellular factors in vivo   总被引：214，自引：0，他引：214  

A Ephrussi  G M Church  S Tonegawa  W Gilbert 《Science (New York, N.Y.)》1985,227(4683):134-140

The mouse heavy chain immunoglobulin gene contains a tissue-specific enhancer. The enhancer and flanking sequences were studied in vivo by carrying out dimethyl sulfate protection experiments on living cells, in combination with genomic sequencing. Relative to reactions on naked DNA, there are changes (protections and enhancements) in the reactivity of guanine residues to dimethyl sulfate within the enhancer sequence in myeloma, B, and early B cells, whereas virtually no alterations appear in cells of non-B lineage. Most of the affected residues are in four clusters, in sequences homologous to the octamer 5'CAGGTGGC 3' (C, cytosine; A, adenine; G. guanine; T, thymine). The alterations in the pattern of G reactivity are consistent with the tissue-specific binding of molecules to the mouse immunoglobulin heavy chain enhancer.  相似文献   

Diverse plant and animal genetic records from Holocene and Pleistocene sediments   总被引：1，自引：0，他引：1  

Willerslev E  Hansen AJ  Binladen J  Brand TB  Gilbert MT  Shapiro B  Bunce M  Wiuf C  Gilichinsky DA  Cooper A 《Science (New York, N.Y.)》2003,300(5620):791-795

Genetic analyses of permafrost and temperate sediments reveal that plant and animal DNA may be preserved for long periods, even in the absence of obvious macrofossils. In Siberia, five permafrost cores ranging from 400,000 to 10,000 years old contained at least 19 different plant taxa, including the oldest authenticated ancient DNA sequences known, and megafaunal sequences including mammoth, bison, and horse. The genetic data record a number of dramatic changes in the taxonomic diversity and composition of Beringian vegetation and fauna. Temperate cave sediments in New Zealand also yielded DNA sequences of extinct biota, including two species of ratite moa, and 29 plant taxa characteristic of the prehuman environment. Therefore, many sedimentary deposits may contain unique, and widespread, genetic records of paleoenvironments.  相似文献   

Sequence variants in SLITRK1 are associated with Tourette's syndrome   总被引：1，自引：0，他引：1  

Abelson JF  Kwan KY  O'Roak BJ  Baek DY  Stillman AA  Morgan TM  Mathews CA  Pauls DL  Rasin MR  Gunel M  Davis NR  Ercan-Sencicek AG  Guez DH  Spertus JA  Leckman JF  Dure LS  Kurlan R  Singer HS  Gilbert DL  Farhi A  Louvi A  Lifton RP  Sestan N  State MW 《Science (New York, N.Y.)》2005,310(5746):317-320

Tourette's syndrome (TS) is a genetically influenced developmental neuropsychiatric disorder characterized by chronic vocal and motor tics. We studied Slit and Trk-like 1 (SLITRK1) as a candidate gene on chromosome 13q31.1 because of its proximity to a de novo chromosomal inversion in a child with TS. Among 174 unrelated probands, we identified a frameshift mutation and two independent occurrences of the identical variant in the binding site for microRNA hsa-miR-189. These variants were absent from 3600 control chromosomes. SLITRK1 mRNA and hsa-miR-189 showed an overlapping expression pattern in brain regions previously implicated in TS. Wild-type SLITRK1, but not the frameshift mutant, enhanced dendritic growth in primary neuronal cultures. Collectively, these findings support the association of rare SLITRK1 sequence variants with TS.  相似文献   

Barometer exposure     

Gilbert GK 《Science (New York, N.Y.)》1886,7(177):571-572

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RHYTHMS AND GEOLOGIC TIME     

Gilbert GK 《Science (New York, N.Y.)》1900,11(287):1001-1012

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UNIVERSITY AND EDUCATIONAL NEWS     

Gilbert GK 《Science (New York, N.Y.)》1898,7(160):94-95

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