Drosophila Sex lethal gene initiates female development in germline progenitors   总被引：1，自引：0，他引：1  

Hashiyama K  Hayashi Y  Kobayashi S 《Science (New York, N.Y.)》2011,333(6044):885-888

Sex determination in the Drosophila germ line is regulated by both the sex of the surrounding soma and cell-autonomous cues. How primordial germ cells (PGCs) initiate sexual development via cell-autonomous mechanisms is unclear. Here, we demonstrate that, in Drosophila, the Sex lethal (Sxl) gene acts autonomously in PGCs to induce female development. Sxl is transiently expressed in PGCs during their migration to the gonads; this expression, which was detected only in XX PGCs, is necessary for PGCs to assume a female fate. Ectopic expression of Sxl in XY PGCs was sufficient to induce them to enter oogenesis and produce functional eggs when transplanted into an XX host. Our data provide powerful evidence that Sxl initiates female germline fate during sexual development.  相似文献   

Recombination regulation by transcription-induced cohesin dissociation in rDNA repeats     

Kobayashi T  Ganley AR 《Science (New York, N.Y.)》2005,309(5740):1581-1584

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Essential role of Fkbp6 in male fertility and homologous chromosome pairing in meiosis     

Crackower MA  Kolas NK  Noguchi J  Sarao R  Kikuchi K  Kaneko H  Kobayashi E  Kawai Y  Kozieradzki I  Landers R  Mo R  Hui CC  Nieves E  Cohen PE  Osborne LR  Wada T  Kunieda T  Moens PB  Penninger JM 《Science (New York, N.Y.)》2003,300(5623):1291-1295

Meiosis is a critical stage of gametogenesis in which alignment and synapsis of chromosomal pairs occur, allowing for the recombination of maternal and paternal genomes. Here we show that FK506 binding protein (Fkbp6) localizes to meiotic chromosome cores and regions of homologous chromosome synapsis. Targeted inactivation of Fkbp6 in mice results in aspermic males and the absence of normal pachytene spermatocytes. Moreover, we identified the deletion of Fkbp6 exon 8 as the causative mutation in spontaneously male sterile as/as mutant rats. Loss of Fkbp6 results in abnormal pairing and misalignments between homologous chromosomes, nonhomologous partner switches, and autosynapsis of X chromosome cores in meiotic spermatocytes. Fertility and meiosis are normal in Fkbp6 mutant females. Thus, Fkbp6 is a component of the synaptonemal complex essential for sex-specific fertility and for the fidelity of homologous chromosome pairing in meiosis.  相似文献   

粳稻品种SSR多态性检出率的分析   总被引：8，自引：0，他引：8  

鲍根良  富田桂  小林麻子  骆荣挺  张小明  王俊敏  叶胜海 《中国农业科学》2005,38(12):2549-2554

 用395对SSR引物测得多态性检出率：日本近缘品种（粳型）间为11.12%，日本近缘品种与意大利品种（粳型）间、与美国品种（籼型）间及与菲律宾品种（籼型）间分别为17.58%、20.80%和38.62%，显示相同粳稻生态型品种间多态性检出率低于不同生态型品种间，而相同粳稻生态型内，日本近缘品种间的多态性检出率更低。在日本近缘品种中，不同品种间多态性检出率差异较大，其变幅为3.79~15.95%。此外，不同染色体间引物的多态性检出率也存在较大差异，其中第10染色体的供试引物多态性检出率无论在不同生态型品种间或相同生态型品种间均最低。  相似文献   

Oxygen isotopic compositions of asteroidal materials returned from Itokawa by the Hayabusa mission     

Yurimoto H  Abe K  Abe M  Ebihara M  Fujimura A  Hashiguchi M  Hashizume K  Ireland TR  Itoh S  Katayama J  Kato C  Kawaguchi J  Kawasaki N  Kitajima F  Kobayashi S  Meike T  Mukai T  Nagao K  Nakamura T  Naraoka H  Noguchi T  Okazaki R  Park C  Sakamoto N  Seto Y  Takei M  Tsuchiyama A  Uesugi M  Wakaki S  Yada T  Yamamoto K  Yoshikawa M  Zolensky ME 《Science (New York, N.Y.)》2011,333(6046):1116-1119

Meteorite studies suggest that each solar system object has a unique oxygen isotopic composition. Chondrites, the most primitive of meteorites, have been believed to be derived from asteroids, but oxygen isotopic compositions of asteroids themselves have not been established. We measured, using secondary ion mass spectrometry, oxygen isotopic compositions of rock particles from asteroid 25143 Itokawa returned by the Hayabusa spacecraft. Compositions of the particles are depleted in (16)O relative to terrestrial materials and indicate that Itokawa, an S-type asteroid, is one of the sources of the LL or L group of equilibrated ordinary chondrites. This is a direct oxygen-isotope link between chondrites and their parent asteroid.  相似文献   

Paraticulate metals in waters of a typical irrigation river: The River Sakuragawa,Japan     

Humitake Seki  Masayuki Takahashi  Katsumi Kobayashi  Shozo Ishizaka 《Water, air, and soil pollution》1979,12(2):265-271

The particulate metallic elements in waters of a water system of the River Sakuragawa and Lake Kasumigaura were measured by the multielement analyses using particle-induced X-ray emission. The heavy metal particulates for environmental standards were less than 0.0001 ppm for Cd, 0.00037 ppm for Cr, and 0.00078 ppm both for Hg and Pb in the river waters. The predominant metal particles in the waters were Fe, Mn, and Zn.  相似文献   

Food-drug interaction between ferulic acid and nateglinide involving the fluorescein/H+ cotransport system   总被引：2，自引：0，他引：2  

Itagaki S  Kobayashi Y  Otsuka Y  Kubo S  Kobayashi M  Hirano T  Iseki K 《Journal of agricultural and food chemistry》2005,53(7):2499-2502

In clinical, patients usually take many kinds of drugs at the same time. Thus, drug-drug interactions involving transporters can often directly affect the therapeutic safety and efficacy of many drugs. However, there have been few studies on food-drug interactions involving transporters. Dietary polyphenols have been widely assumed to be beneficial to human health. Polyphenols are commercially prepared and used as functional foods. We report here for the first time that ferulic acid, which is widely used as a functional food, affects the transport of clinical agents. It is important to be aware of the potential of food-drug interactions and to act in order to prevent undesirable and harmful clinical consequences.  相似文献   

Reduced immunogenicity of beta-lactoglobulin by conjugation with carboxymethyl dextran differing in molecular weight   总被引：2，自引：0，他引：2  

Kobayashi K  Hirano A  Ohta A  Yoshida T  Takahashi K  Hattori M 《Journal of agricultural and food chemistry》2001,49(2):823-831

To reduce the immunogenicity of beta-lactoglobulin (beta-LG), two beta-LG-carboxymethyl dextran (CMD) conjugates (Conj. 40 and Conj. 162) were prepared by using water-soluble carbodiimide (EDC). The molar ratios of beta-LG to CMD in Conj. 40 and Conj. 162 were 8:1 and 7:1, respectively. Each conjugate maintained approximately 50% of the retinol binding activity of beta-LG. Structural analyses by intrinsic fluorescence, CD spectra, and ELISA with monoclonal antibodies indicated that the surface of beta-LG in each conjugate was covered by CMD without great disruption of native conformation. By conjugation with CMD, the antibody response to beta-LG was reduced in BALB/c, C3H/He, and C57BL/6 mice, which was eminent in Conj. 162. The results of B cell epitope scanning using overlapping synthesized peptides showed that the linear epitope profiles of the conjugates were similar to those of beta-LG, whereas the antibody response to each epitope was reduced, which was eminent in Conj. 162. It was concluded that conjugation with CMD of higher molecular weight is effective in reducing the immunogenicity of beta-LG and that masking of epitopes by CMD is responsible for the reduced immunogenicity.  相似文献   

Analysis of glycosidically bound aroma precursors in tea leaves. 1. Qualitative and quantitative analyses of glycosides with aglycons as aroma compounds     

Wang D  Yoshimura T  Kubota K  Kobayashi A 《Journal of agricultural and food chemistry》2000,48(11):5411-5418

Twenty-six synthetic glycosides constituting aglycons of the main tea aroma compounds ((Z)-3-hexenol, benzyl alcohol, 2-phenylethanol, methyl salicylate, geraniol, linalool, and four isomers of linalool oxides) were synthesized in our laboratory as authentic compounds. Those compounds were used to carry out a direct qualitative and quantitative determination of the glycosides as aroma precursors in different tea cultivars by capillary gas chromatographic-mass spectrometric (GC-MS) analyses after trifluoroacetyl conversion of the tea glycosidic fractions. Eleven beta-D-glucopyranosides, 10 beta-primeverosides (6-O-beta-D-xylopyranosyl-beta-D-glucopyranoside) with aglycons as the above alcohols, and geranyl beta-vicianoside (6-O-alpha-L-arabinopyranosyl-beta-D-glucopyranoside) were identified (tentatively identified in the case of methyl salicylate beta-primeveroside) in fresh tea leaves and quantified on the basis of calibration curves that had been established by using the synthetic compounds. Primeverosides were more abundant than glucosides in each cultivar we investigated for making green tea, oolong tea, and black tea. Separation of the diastereoisomers of linalool and four isomers of linalool oxides by GC analyses is also discussed.  相似文献   

Nitrogen Retention in Japanese Cedar Stands in Northern Honshu, with High Nitrogen Deposition   总被引：1，自引：0，他引：1  

M. Baba  Y. Suzuki  H. Sasaki  K. Matano  T. Sugiura  H. Kobayashi 《Water, air, and soil pollution》2001,130(1-4):1103-1108

High nitrogen, especially ammonium, input has been observed in Schichinohe, Aomori Prefecture, northeastern Japan. A monitoring study on precipitation, throughfall, and stream water has been carried out to estimate the stage of nitrogen saturation since 1996. Fifty-two to 70% of nitrogen input in throughfall was retained in forest ecosystems. Nitrate concentration in stream water tended to decrease throughout the study. There was no symptom of nitrogen saturation at Japanese cedar stands in Shichinohe, although high nitrogen input in open bulk has been observed. Ammonium (NH₄ ⁺) was retained in the canopy. The ratio of NH₄ ⁺ input in throughfall to that by open bulk was 0.40 – 0.47. Total inorganic nitrogen input under the canopy amounted 0.68 – 0.72 kmolc ha^?1 yr^?1 (9.6 – 10.0 kg N ha^?1 yr^?1). Our results suggests that atmospheric nitrogen input has benefitted the three growth.  相似文献