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61.
We describe a new specimen of a supposed Paleozoic tetrapod body impression from the Lower Permian S?upiec Formation in the Intra-Sudetic Basin, Poland. The size, integument morphology of belly and part of tail imprints, and the morphology of a well-preserved pes track diagnose the specimen and readily distinguish it from other described specimens of body impressions of Paleozoic tetrapods. The eupelycosaur identity of this new specimen is based on the identification of the footprint Dimetropus leisnerianus (Geinitz, 1863), which is connected with the inferred body imprint. The morphology of integument impressions indicates the presence of the various-sized square or rectangular-shaped scales on the bottom part of the belly and tail of this eupelycosaurid trackmaker. 相似文献
62.
吐鲁番-哈密盆地早二叠世晚期植物群 总被引:2,自引:1,他引:2
首次记述了吐鲁番-哈密盆地的早二叠世晚期植物11属13种(包括4新种和4未定种),这是一个以科达类及其相关属为主的安加拉植物群。典型的安加拉植物Vojnovskya属的发现,不但在时代的判定上,而且在植物地理区划上都具重要意义。文中还对这一植物群的特征和时代问题作了简要讨论。 相似文献
63.
Herr JC Chertihin O Digilio L Jha KN Vemuganti S Flickinger CJ 《Developmental biology》2008,314(2):300-316
We report the cloning and characterization of MOEP19, a novel 19 kDa RNA binding protein that marks a defined cortical cytoplasmic domain in oocytes and provides evidence of mammalian oocyte polarity and a form of pre-patterning that persists in zygotes and early embryos through the morula stage. MOEP19 contains a eukaryotic type KH-domain, typical of the KH-domain type I superfamily of RNA binding proteins, and both recombinant and native MOEP19 bind polynucleotides. By immunofluorescence, MOEP19 protein was first detected in primary follicles throughout the ooplasm. As oocytes expanded in size during oogenesis, MOEP19 increased in concentration. MOEP19 localized in the ovulated egg and early zygote as a symmetrical spherical cortical domain underlying the oolemma, deep to the zone of cortical granules. MOEP19 remained restricted to a cortical cytoplasmic crescent in blastomeres of 2-, 4- and 8-cell embryos. The MOEP19 domain was absent in regions underlying cell contacts. In morulae, the MOEP19 domain was found at the apex of outer, polarized blastomeres but was undetectable in blastomeres of the inner cell mass. In early blastocysts, MOEP19 localized in both mural and polar trophectoderm and a subset of embryos showed inner cell mass localization. MOEP19 concentration dramatically declined in late blastocysts. When blastomeres of 4- to 8-cell stages were dissociated, the polarized MOEP19 domain assumed a symmetrically spherical localization, while overnight culture of dissociated blastomeres resulted in formation of re-aggregated embryos in which polarity of the MOEP19 domain was re-established at the blastomere apices. MOEP19 showed no evidence of translation in ovulated eggs, indicating that MOEP19 is a maternal effect gene. The persistence during early development of the MOEP19 cortical oocyte domain as a cortical crescent in blastomers suggests an intrinsic pre-patterning in the egg that is related to the apical-basolateral polarity of the embryo. Although the RNAs bound to MOEP19 are presently unknown, we predict that the MOEP19 domain directs RNAs essential for normal embryonic development to specific locations in the oocyte and early embryo. 相似文献
64.
Korgun ET Celik-Ozenci C Acar N Cayli S Desoye G Demir R 《Histochemistry and cell biology》2006,125(6):615-624
Although placental development and implantation depend on the coordination of trophoblast proliferation, differentiation and invasion, little is known about the cell cycle regulators that govern the control of these events. The hypothesis that the coordinated expression of cell cycle progression and inhibition factors will determine whether cytotrophoblasts proliferate or undergo cell cycle arrest or cell cycle exit allowing subsequent differentiation was tested. The cell cycle promotors cyclin A, cyclin B1, PCNA, Ki67 and the cell cycle inhibitors p21, p27 and p57 were immunolocalized in tissue sections of first trimester pregnancies (weeks 6 and 9–12). Double staining with cytokeratin 7 allowed unambiguous identification of extravillous cytotrophoblast (EVT) in the decidua. Villous cytotrophoblasts were immunolabelled for Ki67 and cyclin A but only few were stained with anti-cyclin B1. The syncytiotrophoblast was devoid of immunoreactivity for any of the cell cycle progression factors. It expressed especially p21, whereas p27 and p57 were predominantly found in villous cytotrophoblasts. PCNA, Ki67, cyclin A and cyclin B1 were immunolocalized in proximal and distal EVTs of anchoring villi and in EVT which had invaded the upper decidual segments. All EVTs strongly expressed p27 and p57, but not p21. These data clearly suggest different functions for p21, p27 and p57 in placental development with distinct roles for p21 and p57 in syncytiotrophoblast and EVT differentiation, respectively. p27 appears to be involved in both the processes. The results may also challenge the concept of differential mitotic activity in the proximal and distal parts of the first trimester cytotrophoblast cell column, but more functional studies are clearly needed. The presence of p27 and p57 in EVT cells, which invade the deciduas deeply, may account for the loss of mitogenic potential of these cells. 相似文献
65.
The smallest known specimen (20mm standard length: SL) of Triodon macropterus Lesson is described and illustrated. It is easily distinguished from superficially similar tetraodontid and diodontid larvae or early juveniles of comparable size by the following characters: separate premaxillae in conjunction with the fused dentaries; the presence of multicuspid spinoid scales; the jet-black mark in front of the soft dorsal fin; the developing pelvis, which is visible through the distended skin of the belly; and the presence of a number of procurrent caudal fin rays. The small Triodon differs from the adult in possessing a huge head that measures 45% SL (vs. 28.5–32.7% in adult), the absence of the characteristic dewlap with the conspicuous lateral ocellus, and the structure of the scales and nostrils. 相似文献
66.
M. R. Naidu P. Singh B. S. Dahiya 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1988,75(3):514-517
Summary Selection in the F3 generation for seed yield, fruiting branches/plant, effective pods/plant, and seed index (100-seed weight) was carried out in two chickpea crosses. Sixty F5 lines (15 lines/selection criterion) along with check variety were evaluated for seed yield in three distinct environments. The effects of selection criteria on yield stability was examined using linear regression approach and genotype-grouping technique. There were no differences between selection criteria for linear yield responses of F5 lines to different environments. Within all four selection criteria the lines showed similar linear responses. The non-linear component was relatively higher for lines selected for effective pods and seed index than lines selected for yield and fruiting branches. On the basis of mean yield and coefficient of variation across environments, the seed index was the least effective selection criterion for developing high yielding and stable lines. When the results of stability parameters and genotype-grouping technique were considered together, selection for yield and fruiting branches was highly effective for isolating stable and high yielding lines. 相似文献
67.
辽西下白垩统九佛堂组尾羽龙类—新属(英文) 总被引:2,自引:0,他引:2
记述了一件采自辽西热河群九佛堂组一新的窃蛋龙类:义县似尾羽龙(Similicaudipteryx yixianensis gen.et sp.nov.),并依据其和尾羽龙属的相似特征,及其匕首状的尾综骨,肠骨、踱骨和脚趾的形态等将其归入窃蛋龙类的尾羽龙科,但其所具有的一些特征也不同于该科已建立的尾羽龙属,如尾综骨的形态和较大的个体等。该化石具有许多典型的窃蛋龙类的特征,如短尾、较短的前肢等,有别于其他窃蛋龙类的特征还包括耻骨和肠骨的长度比为1.46,背椎上发育2个大而深的椎体下突、背椎侧部具孔等。义县似尾羽龙是又一类具有真正尾综骨的恐龙,表明尾综骨这一曾经被认为是鸟类特有的结构可能是在恐龙中独自演化的。它具有一些进步的特征如具尾综骨等,但同时也具有一些原始的特征如5个愈合的荐椎,耻骨联合长,表明在窃蛋龙类中存在着特征的镶嵌进化现象。似尾羽龙与驰龙类、其他窃蛋龙类等恐龙一样,脚趾并没有对握,已有的证据说明完全的对握目前还只是出现于鸟类中。根据其短尾、中部收缩的趾骨和灵巧的身体等都表明它是一类适于快速奔跑的动物。目前为止,已知的尾羽龙类化石均发现于北票四合屯地区的义县组下部尖山沟层(段),距今约125Ma。新标本发现于义县西二虎桥地点,属于九佛堂组,距今约120Ma,这也是迄今为止在九佛堂组发现的惟一一件尾羽龙类化石,对研究早白垩世窃蛋龙类的演化和热河生物群恐龙组合的特征具有重要的意义。 相似文献
68.
69.
目的:分析ART患者早期流产组织染色体异常及其相关影响因素。方法:回顾性分析2013-2017年ART患者行早期流产组织染色体检查的409例样本,分析胚胎染色体非整倍性发生及其与女方年龄、不孕年限、不孕因素、促排卵指标之间的关系。结果:ART流产患者中,流产组织染色体非整倍性发生率为57.46%,发生频次以16三体占比最高(23.95%),其次是22三体(13.45%)及Turner(9.24%)。流产组织染色体非整倍性患者平均年龄高于染色体整倍性患者(P0.001)。16三体组患者年龄低于22三体(P0.01)及Turner组(P0.05)。16三体组患者平均Gn使用量低于22三体组(P0.05)。16三体组患者移植15天血HCG值低于22三体(P0.05)及Turner组(P0.01)。结论:ART患者流产组织染色体非整倍性与女方年龄正相关,但16三体及Turner的发生与女方年龄相关性不大,且16三体更容易引发早期流产。 相似文献
70.
目的:观察尿微量白蛋白在糖尿病患者中的改变情况,探讨提高社区糖尿病肾病早期诊断检出率的方法。方法:选择社区2型糖尿病患者73例,根据空腹血糖控制情况及糖尿病病程时长分别分组,比较不同组间患者尿微量白蛋白水平及阳性病例检出率,同时进行相关性分析。结果:MAlb在不同血糖控制情况患者中,血糖水平与MAlb数值、阳性检出率具有正相关性(P<0.05);血糖控制良好患者与其他血糖控制情况患者相比,差异具有(高度)统计学意义(P<0.01;P<0.05);MAlb在不同病程患者中,病程时间与MAlb数值、阳性检出率具有正相关性(P<0.05);≤5年组患者与5~10年组和≥10年组相比,差异具有(高度)统计学意义(P<0.01;P<0.05)。结论:尿微量白蛋白(MAlb)可作为早期糖尿病肾病检测的重要指标,能够提示肾脏病变的发展,定期检查能够提高早期糖尿病肾病的检出率。 相似文献