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931.
María Ferriol Hugo Merle Alfonso Garmendia 《Botanical journal of the Linnean Society. Linnean Society of London》2014,176(1):82-98
Survival of polyploids in nature depends on several factors, including competition from diploid relatives and increased genetic diversity. Unlike other reported Centaurea polyploid complexes, diploid Centaurea aspera and tetraploid Centaurea seridis coexist in hybrid zones with frequent triploid individuals. The polyploid origin of C. seridis, the genetic diversity and population structure of the three cytotypes, and the degree of genetic differentiation among them were analyzed in seven mixed‐ploidy zones, involving different subspecies and ecological conditions. Ploidy was determined by flow cytometry. Microsatellite data suggested an allopolyploid origin of C. seridis. In the contact zones, diploids and tetraploids were genetically differentiated. When compared with the related C. aspera, a low genetic diversity was observed in C. seridis, which is uncommon in tetraploids. Furthermore, although diploid individuals were grouped in a single widespread genetic cluster, tetraploids were grouped in two highly differentiated clusters and showed significant isolation by distance. This genetic pattern in C. seridis may be related to a minimal gene flow with diploid relatives and/or other genetic factors, such as rare polyploidization events, founder effects or an increased selfing rate. Neither taxonomic assignment at subspecies level, nor ecological conditions could explain the genetic differentiation between tetraploid clusters. © 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 176 , 82–98. 相似文献
932.
Na Li Feng Yan Yuda Huo Xing Liu Xuebiao Yao 《Biochemical and biophysical research communications》2009,384(1):76-404
Mitotic chromosome movements are orchestrated by interactions between spindle microtubules and chromosomes. It is well known that kinetochore is the major site where microtubule-chromosome attachment occurs. However, the functions of other domains of chromosome such as chromosome periphery have remained elusive. Our previous studies show that PinX1 distributes to chromosome periphery and kinetochore during mitosis, and harbors the microtubule binding activity. Here we report that PinX1 interacts with Nucleolin, a chromosome periphery protein, through its C-termini. Deconvolution microscopic analyses show PinX1 mainly co-localizes with Nucleolin at chromosome periphery in prometaphase. Moreover, depletion of Nucleolin abolishes chromosome periphery localizations of PinX1, suggesting a functional interrelationship between PinX1 and Nucleolin. Importantly, repression of PinX1 and Nucleolin abrogates chromosome segregation in real-time mitosis, validating the functional importance of PinX1-Nucleolin interaction. We propose PinX1 is recruited to chromosome periphery by Nucleolin and a complex of PinX1 and Nucleolin is essential for faithful chromosome congression. 相似文献
933.
Won Hee Kim Hyung-Rock Lee Pusoon Chun Jungsu Kim Lak Shin Jeong 《Carbohydrate research》2009,344(17):2317-304
An efficient synthetic route of l-hamamelose was successfully accomplished starting from d-ribose. l-Hamamelose was synthesized in 42% overall yield with six reaction steps via a stereoselective Grignard reaction, a stereoselective crossed aldol reaction and a controlled oxidative cleavage of the double bond of a vinyl diol compound. During the oxidative cleavage of the double bond of the vinyl diol compound with osmium tetroxide and NaIO4, an over-oxidative cleavage of α-hydroxyl aldehyde generated from ring opening of the first cleaved product, formyl lactol, did not occur, probably due to the stability of the lactol form. A plausible mechanism for the stereoselective crossed aldol reaction was suggested. The final target compound, l-hamamelose can play a very important role as a chiral building block in synthesizing a wide variety of enantiopure compounds. 相似文献
934.
Confronting a recently mated female with a strange male can induce a pregnancy block ('Bruce effect'). The physiology of this effect is well studied, but its functional significance is still not fully understood. The 'anticipated infanticide hypothesis' suggests that the pregnancy block serves to avoid the cost of embryogenesis and giving birth to offspring that are likely to be killed by a new territory holder. Some 'compatible-genes sexual selection hypotheses' suggest that the likelihood of a pregnancy block is also dependent on the female's perception of the stud's and the stimulus male's genetic quality. We used two inbred strains of mice (C57BL/6 and BALB/c) to test all possible combinations of female strain, stud strain, and stimulus strain under experimental conditions (N(total) = 241 mated females). As predicted from previous studies, we found increased rates of pregnancy blocks if stud and stimulus strains differed, and we found evidence for hybrid vigour in offspring of between-strain mating. Despite the observed heterosis, pregnancies of within-strain matings were not more likely to be blocked than pregnancies of between-strain matings. A power analysis revealed that if we missed an existing effect (type-II error), the effect must be very small. If a female gave birth, the number and weight of newborns were not significantly influenced by the stimulus males. In conclusion, we found no support for the 'compatible-genes sexual selection hypotheses'. 相似文献
935.
Maintaining undifferentiated state and self-renewal ability of embryonic stem cells is a process that many genes and factors
participate in. Using bioinformatics analyses and suppression subtractive hybridization we cloned a novel human gene related
to the proliferation of human embryonic stem (hES) cells and its mouse homologue and identified them as being borealin. Our
data demonstrated that borealin was highly expressed in undifferentiated ES cells, mouse pre-implantation embryos and the
brain of 8.5–9.5 day post-coitum mouse embryos. Furthermore, following Borealin depletion by microinjecting anti-Borealin
antibody into the zygotes the mouse embryos were arrested at the 2 or 4-cell stage and chromosomes could not correctly localize
at the equator plane of the mitotic spindle and most cells had two or more nuclei. Taken together, these results indicate
that Borealin plays a crucial role in the early mouse embryonic development. 相似文献
936.
Stefano Carganico Paolo Rovero Jose A. Halperin Anna Maria Papini Michael Chorev 《Journal of peptide science》2009,15(2):67-71
Growing interest in synthetic peptides carrying post‐traslational modifications, in general, and the Amadori modification in particular, raises the need for specific building blocks that can be used in stepwise peptide synthesis. Herein, we report the synthesis of Nα‐Fmoc‐Lys‐OH derivatives containing Nε‐1‐deoxyfructopyranosyl moiety. Copyright © 2008 European Peptide Society and John Wiley & Sons, Ltd. 相似文献
937.
The hermaphrodite Caenorhabditis elegans germline has become a classic model for stem cell regulation, but the male C. elegans germline has been largely neglected. This work provides a cellular analysis of the adult C. elegans male germline, focusing on its predicted stem cell region in the distal gonad. The goals of this study were two-fold: to establish the C. elegans male germline as a stem cell model and to identify sex-specific traits of potential relevance to the sperm/oocyte decision. Our results support two major conclusions. First, adult males do indeed possess a population of germline stem cells (GSCs) with properties similar to those of hermaphrodite GSCs (lack of cell cycle quiescence and lack of reproducibly oriented divisions). Second, germ cells in the mitotic region, including those most distal within the niche, exhibit sex-specific behaviors (e.g. cell cycle length) and therefore have acquired sexual identity. Previous studies demonstrated that some germ cells are not committed to a sperm or oocyte cell fate, even in adults. We propose that germ cells can acquire sexual identity without being committed to a sperm or oocyte cell fate. 相似文献
938.
Rello-Varona S Gámez A Moreno V Stockert JC Cristóbal J Pacheco M Cañete M Juarranz A Villanueva A 《The international journal of biochemistry & cell biology》2006,38(12):2183-2195
DNA damage, cell cycle and apoptosis form a network with important implications for cancer chemotherapy. Dysfunctions of the cycle checkpoints can allow cancer cells to acquire drug resistance. Etoposide is a well-known inducer of apoptosis, which is widely used in cell biology and in clinical practice. In this work we report that a pulse of 50 μM etoposide (incubation for only 3 h) on HeLa cells causes a sequence of events that leads to abnormal mitotic figures that could be followed either by cell death or, more commonly, by interphase restitution and endocycle. The endocycling polyploid cells enter immediately into mitosis and suffer metaphase blockage with multiple spindle poles, which were generally followed by a direct triggering of apoptosis from metaphase (mitotic catastrophe), or by a new process of endocycling, until surviving cells finally became apoptotic (96 h after the treatment). 相似文献
939.
Songcheng Zhu Ruiqi Jing Yiwei Yang Yitong Huang Xin Wang Ye Leng Jiajie Xi Guiying Wang Wenwen Jia Jiuhong Kang 《The Journal of biological chemistry》2015,290(18):11282-11292
Human BUB3 is a key mitotic checkpoint factor that recognizes centromeric components and recruits other mitotic checkpoint molecules to the unattached kinetochore. The key amino acid residues responsible for its localization are not yet defined. In this study, we identified a motif from Lys216 to Lys222 in BUB3 as its nuclear localization signal. A BUB3 mutant with deletion of this motif (Del216–222) was found to localize to both the cytoplasm and the nucleus, distinct from the exclusively nuclear distribution of wild-type BUB3. Further analysis revealed that residues Glu213, Lys216, Lys217, Lys218, Tyr219, and Phe221, but not Lys222, contribute to nuclear localization. Interestingly, the nuclear localization signal was also critical for the kinetochore localization of BUB3. The deletion mutant Del216–222 and a subtle mutant with four residue changes in this region (E213Q/K216E/K217E/K218E (QE)) did not localize to the kinetochore efficiently or mediate mitotic checkpoint arrest. Protein interaction data suggested that the QE mutant was able to interact with BUB1, MAD2, and BubR1 but that its association with the centromeric components CENP-A and KNL1 was impaired. A motif from Leu61 to Leu65 in CENP-A was found to be involved in the association of BUB3 and CENP-A in cells; however, further assays suggested that CENP-A does not physically interact with BUB3 and does not affect BUB3 localization. Our findings help to dissect the mechanisms of BUB3 in mitotic checkpoint signaling. 相似文献
940.
摘要 目的:观察全身麻醉结合股神经及坐骨神经阻滞对下肢骨折患者术后苏醒质量、应激反应和认知功能的影响。方法:选择2020年7月-2021年7月期间我院收治的103例下肢骨折手术患者,依据双色球随机分组法分为对照组(51例,接受全身麻醉)和观察组(52例,接受全身麻醉结合股神经及坐骨神经阻滞)。观察两组血流动力学、术后苏醒质量、应激反应和认知功能的变化,记录两组围术期不良反应发生情况。结果:两组诱导麻醉后(T2)时间点心率(HR)、平均动脉压(MAP)较麻醉前(T1)时间点下降,观察组置喉罩即刻(T3)~置喉罩后60 min(T5)时间点HR、MAP低于对照组(P<0.05)。两组不良反应发生率对比无差异(P>0.05)。观察组的苏醒时间短于对照组,躁动发生率低于对照组(P<0.05)。两组麻醉苏醒期肾上腺素(E)、皮质醇(Cor)均较麻醉维持期升高,但观察组低于对照组(P<0.05)。观察组视空间与执行、记忆、命名、注意、语言、抽象、定向力、延迟回忆维度评分及总分均高于对照组(P<0.05)。结论:下肢骨折患者采用全身麻醉结合股神经及坐骨神经阻滞,可稳定血流动力学,提高术后苏醒质量,减轻应激反应和对认知功能的影响。 相似文献