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新受精卵超越早期分裂阶段必需胚胎基因转录 ( ZGA)的重新起动与续后调控 ,在各类动物早期卵裂过程的胚胎基因转录起动精确时间是可变的 ,涉及染色质结构成分、调控元件 (顺 /反式 )、RNA降解、DNA复制、修饰或加工作用、卵子发生因子、合子钟及天然信号等多种因素 ,因此提出哺乳动物胚胎发育期胚胎基因激活表达的调控机制 相似文献
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Schier AF 《Science (New York, N.Y.)》2007,316(5823):406-407
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Koepp DM Schaefer LK Ye X Keyomarsi K Chu C Harper JW Elledge SJ 《Science (New York, N.Y.)》2001,294(5540):173-177
Cyclin E binds and activates the cyclin-dependent kinase Cdk2 and catalyzes the transition from the G1 phase to the S phase of the cell cycle. The amount of cyclin E protein present in the cell is tightly controlled by ubiquitin-mediated proteolysis. Here we identify the ubiquitin ligase responsible for cyclin E ubiquitination as SCFFbw7 and demonstrate that it is functionally conserved in yeast, flies, and mammals. Fbw7 associates specifically with phosphorylated cyclin E, and SCFFbw7 catalyzes cyclin E ubiquitination in vitro. Depletion of Fbw7 leads to accumulation and stabilization of cyclin E in vivo in human and Drosophila melanogaster cells. Multiple F-box proteins contribute to cyclin E stability in yeast, suggesting an overlap in SCF E3 ligase specificity that allows combinatorial control of cyclin E degradation. 相似文献
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HONG Qi-bin LI Xi-qing JIANG Dong CHEN Zhu-sheng XIANG Su-qiong GONG Gui-zhi YE Qing-liang 《中国农业科学(英文版)》2003,2(5)
Polyembryony is a serious handicap in citrus breeding. To obtain zygotic off-springs, monoem-bryonic seed parents were usually used in breeding programs. Kiyomi, a superior monoembryonic tangor, wasused as seed parent in 7 cross combinations. When pollen parents was Chandler pummelo or Tarocco blood or-ange, only monoembryonic seeds were observed. However, when Washington Sanguine, Li-xing orange andBing-tang orange were used as pollen parents, no more than 7.2 % of polyembryonic seeds were observed. In-terestingly, while male parents were Nucellar3 Ponkan and Oota Ponkan, high ratio of polyembryonic seedswas observed. The ratio of polyembryonic seeds was steadily at about 30 % in two consecutive years and was ob-viously different from other results reported. Polyembronic seeds were observed in monoembryonic varietiessometimes, but normally their ratios were no more than 7 %. Polyembryonic-seedlings were got by separatingthe multi-embryos in seeds of Kiyomi × Nucellar3 Ponkan and then their leaves were used in RAPD analysis.Identical bands of male parent and/or different bands from seed parent were found in most of the polyembry-onic-seedlings and so it can be sure that these seedlings were of zygotic origin. Some pairs of polyembryonic-seedlings have identical bands in all tested primers and may be resulted from zygotic embryo divisions. Differ-ent bands were found in other pairs of polyembryonic-seedlings also and this may indicate multi-egg fertiliza-tion or other source of variation. 相似文献
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Stomata regulate gas exchange and are distributed across the leaf epidermis with characteristic spacing. Arabidopsis stomata are produced by asymmetric cell divisions. Mutations in the gene TOO MANY MOUTHS (TMM) disrupt patterning by randomizing the plane of formative asymmetric divisions and by permitting ectopic divisions. TMM encodes a leucine-rich repeat-containing receptor-like protein expressed in proliferative postprotodermal cells. TMM appears to function in a position-dependent signaling pathway that controls the plane of patterning divisions as well as the balance between stem cell renewal and differentiation in stomatal and epidermal development. 相似文献
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Volarevic S Stewart MJ Ledermann B Zilberman F Terracciano L Montini E Grompe M Kozma SC Thomas G 《Science (New York, N.Y.)》2000,288(5473):2045-2047
Because ribosome biogenesis plays an essential role in cell proliferation, control mechanisms may have evolved to recognize lesions in this critical anabolic process. To test this possibility, we conditionally deleted the gene encoding 40S ribosomal protein S6 in the liver of adult mice. Unexpectedly, livers from fasted animals deficient in S6 grew in response to nutrients even though biogenesis of 40S ribosomes was abolished. However, liver cells failed to proliferate or induce cyclin E expression after partial hepatectomy, despite formation of active cyclin D-CDK4 complexes. These results imply that abrogation of 40S ribosome biogenesis may induce a checkpoint control that prevents cell cycle progression. 相似文献
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通过现代分子生物学技术,从三角帆蚌(Hyriopsis cumingii)中克隆了细胞周期蛋白B(cyclin B)基因的cDNA,得到长度为1 024 bp的序列信息,包括768 bp的ORF,197 bp的3′-UTR,编码255个Aa。进一步分析表明,三角帆蚌cyclin B基因与牡蛎、扇贝具有较高的相似性,其氨基酸序列中具有1个典型的周期蛋白框(cyclin-box),并存在2个周期蛋白依赖性蛋白激酶(CDK)的作用位点。通过RT-qPCR研究显示:三角帆蚌cyclin B基因在性腺中的表达最高,在雌性中的表达量显著高于雄性(P0.05);而cyclin B基因在其他组织中的表达量均显著低于性腺(P0.05),且无显著雌雄差异(P0.05);沉默cyclin B基因后,除外套膜外,其在性腺和鳃的表达显著降低(P0.05),表明RNA干扰(RNAi)对三角帆蚌不同组织具有不同的沉默效果。流式细胞仪测定RNAi后细胞的分裂时相变化,发现性腺和鳃细胞中G2/M期占比下降,表明cyclin B基因在三角帆蚌中能调控细胞分裂。初步研究了三角帆蚌cyclin B基因及其功能,为三角帆蚌细胞体外建系奠定分子基础。 相似文献
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A central question in the study of cell proliferation is, what controls cell-cycle transitions? Although the accumulation of mitotic cyclins drives the transition from the G2 phase to the M phase in embryonic cells, the trigger for mitotic entry in somatic cells remains unknown. We report that the synergistic action of Bora and the kinase Aurora A (Aur-A) controls the G2-M transition. Bora accumulates in the G2 phase and promotes Aur-A-mediated activation of Polo-like kinase 1 (Plk1), leading to the activation of cyclin-dependent kinase 1 and mitotic entry. Mechanistically, Bora interacts with Plk1 and controls the accessibility of its activation loop for phosphorylation and activation by Aur-A. Thus, Bora and Aur-A control mitotic entry, which provides a mechanism for one of the most important yet ill-defined events in the cell cycle. 相似文献
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Signal transduction by the platelet-derived growth factor receptor 总被引：81，自引：0，他引：81
L T Williams 《Science (New York, N.Y.)》1989,243(4898):1564-1570
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以大蒜体细胞胚胎发生不同阶段的培养材料为试材进行组织学研究,结果表明:体胚形成过程中,表层薄壁细胞首先经脱分化恢复分生能力,形成愈伤组织,随后在其表面形成许多瘤状突起—胚性细胞团,胚性细胞团继续发育成球形胚、盾形胚最后发育成熟形成完整植株。从实验结果可以初步认为由大蒜体细胞培养而获得的体细胞胚在结构上也具有类似合子胚的基本结构。 相似文献
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Inhibition of cellular proliferation by antisense oligodeoxynucleotides to PCNA cyclin 总被引：69，自引：0，他引：69
D Jaskulski J K deRiel W E Mercer B Calabretta R Baserga 《Science (New York, N.Y.)》1988,240(4858):1544-1546
The proliferating cell nuclear antigen (PCNA or cyclin) is a nuclear protein recently identified as a cofactor of DNA polymerase delta. When exponentially growing Balb/c3T3 cells are exposed to antisense oligodeoxynucleotides to PCNA, both DNA synthesis and mitosis are completely suppressed. A corresponding sense oligodeoxynucleotide has no inhibitory effects. These experiments indicate that PCNA (cyclin) is important in cellular DNA synthesis and in cell cycle progression. 相似文献
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Gene regulation by transcription factors and microRNAs 总被引：1，自引：0，他引：1
Hobert O 《Science (New York, N.Y.)》2008,319(5871):1785-1786