共查询到19条相似文献，搜索用时 140 毫秒
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用蜂胶制剂失活牙髓300例效果观察 总被引：4，自引：0，他引：4
用蜂胶制剂失活牙髓３００例，成功率为９７．３３％，失活效果与砷剂相媲美，比多聚甲醛明显优良。未见因封药造成牙槽骨缺损坏死，也未见封存后出现皮疹、恶心、头晕、心慌等全身过敏反应和毒性反应，为蜂胶的药用价值的开发，开辟了新的途径。 相似文献
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《畜牧兽医学报》2017,(1)
胚胎发育是一个复杂的过程,其发生受到了很多转录调控因子的调控。随着高通量深度测序技术的发展,研究发现非编码RNA(ncRNA)对动物胚胎发育、X染色体失活、性别调控、脑部发育都具有十分重要的调控作用。其中,miRNA主要通过与其靶向mRNA的3′UTR结合参与调控胚胎发育的相关基因;lncRNA通过转录干扰或是修饰染色质来调控相关基因从而介导哺乳动物X染色体失活和昆虫W染色体的剂量补偿;piRNA通过沉默转座子来维持生殖细胞DNA完整性,并参与生殖细胞形成及家蚕性别调控;circRNA可以作为miRNA的海绵调控动物脑部的发育。本文拟从miRNA、lncRNA、piRNA、circRNA等ncRNA角度阐述其在胚胎发育过程中的研究进展,为进一步研究ncRNA参与调控动物胚胎发育过程的作用机制提供参考。 相似文献
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雌性多能干细胞(iPS细胞)多能性状态的获得伴随着X染色体的表观修饰重编程。分化终末状态的雌性体细胞中有1条X染色体发生异染色质化而导致其失活。在体细胞诱导多能性干细胞的过程中,失活的X染色体重新活化。在重编程过程中,多能因子和X染色体失活中心的非编码基因的联系紧密。文章主要从分子水平上讨论多能干细胞X染色体表观修饰的相关研究进展。小鼠胚胎干细胞(ES细胞)是标准的多能性基态。X染色体上非编码RNA的表达可能是一个评价iP S表观遗传状态的标记,相关研究可以为细胞治疗的临床应用提供重要依据。 相似文献
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使用H9N2亚型流感病毒作为系统模型,用不同浓度(2,4μmol/L)的光敏剂经激光照射(12 J/cm2,20 min),使病毒颗粒失活后,使用透射电子显微镜(TEM)观察病毒粒子形态,并对病毒的感染性进行测定。结果显示,低浓度光敏剂处理组的病毒粒子膜结构虽然保持完整性,但表面糖蛋白缺失,同时丧失了对MDCK细胞的感染性;高浓度光敏剂处理组的病毒粒子膜结构不完整,出现不同程度的膜结构损伤,病毒粒子对MDCK细胞无感染性。本试验为流感病毒的光动力失活提供了可靠的试验依据。 相似文献
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目的：建立小肠结肠炎耶尔森氏菌在猪肉中的存活／失活预测模型．并提出其控制措施。方法：用浓度梯度稀释法计细菌总量．按对数法作出不同条件下小肠结肠炎耶尔森氏菌的生长曲线。采用预测微生物学的基本方法和程序，并用CurveExpert1．38软件作为辅助工具。对试验数据进行拟合。结果：50℃、-18℃及速冻条件下该菌的初始菌数与时间为T时的菌数之比关于时间T的存活／失活预测模型符合Linear关系式。结论：实验表明，本菌对高温非常敏感，在冷冻．速冻过程中仍能存活。 相似文献
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表观遗传修饰是一种不依赖于DNA序列变化的可逆、可遗传修饰，在哺乳动物胚胎发育的整个阶段均可发生，是影响哺乳动物体细胞核移植效率的主要因素之一。其中，DNA甲基化、组蛋白的动态修饰、X染色体失活、端粒与端粒酶活性变化作为常见的表观遗传修饰类型，任一修饰形式的异常都会影响基因的表达，引发体细胞重编程错误导致核移植效率降低。近年来，随着体细胞核移植技术研究的不断深入，表观遗传修饰影响体细胞核移植效率的关键作用机制日益明确。本文通过综述不同类型的表观遗传修饰影响哺乳动物体细胞核移植效率的研究进展，以期在表观遗传修饰层面为提高哺乳动物体细胞核移植效率提供新思路。 相似文献
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Yoh-Ichi Miyake 《Reproduction in domestic animals》1982,17(3):151-158
The replicating patterns of bovine sex chromosomes were examined using the method of the alternate administration of BrdU and dT throughout the DNA synthesis of the cell cycle. It was clear that two X chromosomes of the female complement behaved in a different replicating patterns and that these differences were markedly shown in the last stage of the S period. The X chromosome of the male behaved in a similar replicating pattern to one of the two female X chromosomes. It was suggested that at the beginning of the S period, the X chromosomes replicated the DNA at the end of the short arm, in the central region, and at the distal region of the long arm. It was clear that the entire Y chromosome replicated in the last S period . 相似文献
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The chromosome number of the muskrat (Ondatra zibethica L.) was determined to be 54 in an investigation of the mitotic and meiotic chromosomes. All chromosomes are one-armed with the exception of one small pair which is biarmed. Further, the X chromosome, one of the largest of the complement, seems to have a small secondary arm making possible an identification of the pair. A systematic investigation of the chromosomes, and especially the sex chromosomes at different stages of the spcrmatocytogenesis, has been performed. 相似文献
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采用骨髓法制备经营田鼠染色体标本片,并对其染色体核型和G带进行分析。结果表明,经营田鼠体细胞染色体数为2n=38,雄性染色体核型由18对常染色体和1对异配型性染色体XY组成,雌性为18对常染色体和1对同配型性染色体XX组成。1～9号为端着丝粒（t）染色体（包括Y染色体）,10号为近端着丝粒（st）染色体,11～18号为中央着丝粒（m）染色体（包括X色体）。19对染色体共分布有370条G带（雄性365条）,其中深带190条,浅带180条。因此,经营田鼠的染色体数目、G带具有明显种的特征,与其他鼠类不同。 相似文献
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Ingemar Gustavsson 《Acta veterinaria Scandinavica》1965,6(1):274
The number of chromosomes of the cat (Felis domestica) was determined at 38, and both the X and the Y chromosomes have submedially situated centromeres. X is of medium size while Y is one of the smallest chromosomes of the complement. For practical purposes, the chromosomes have been divided into groups according to their appearance. 相似文献
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ASTRID BÖHNE Christina SCHULTHEIS Delphine GALIANA‐ARNOUX Alexander FROSCHAUER Qingchun ZHOU Cornelia SCHMIDT Yvonne SELZ Catherine OZOUF‐COSTAZ Agnès DETTAI Béatrice SEGURENS Arnaud COULOUX Sylvie BERNARD‐SAMAIN Valérie BARBE Stefan CHILMONCZYK Frédéric BRUNET Amandine DARRAS Marta TOMASZKIEWICZ Marie SEMON Manfred SCHARTL Jean‐Nicolas VOLFF 《Integrative zoology》2009,4(3):277-284
In contrast to mammals and birds, fish display an amazing diversity of genetic sex determination systems, with frequent changes during evolution possibly associated with the emergence of new sex chromosomes and sex‐determining genes. To better understand the molecular and evolutionary mechanisms driving this diversity, several fish models are studied in parallel. Besides the medaka (Oryzias latipes Temminck and Schlegel, 1846) for which the master sex‐determination gene has been identified, one of the most advanced models for studying sex determination is the Southern platyfish (Xiphophorus maculatus, Günther 1966). Xiphophorus maculatus belongs to the Poeciliids, a family of live‐bearing freshwater fish, including platyfish, swordtails and guppies that perfectly illustrates the diversity of genetic sex‐determination mechanisms observed in teleosts. For X. maculatus, bacterial artificial chromosome contigs covering the sex‐determination region of the X and Y sex chromosomes have been constructed. Initial molecular analysis demonstrated that the sex‐determination region is very unstable and frequently undergoes duplications, deletions, inversions and other rearrangements. Eleven gene candidates linked to the master sex‐determining gene have been identified, some of them corresponding to pseudogenes. All putative genes are present on both the X and the Y chromosomes, suggesting a poor degree of differentiation and a young evolutionary age for platyfish sex chromosomes. When compared with other fish and tetrapod genomes, syntenies were detected only with autosomes. This observation supports an independent origin of sex chromosomes, not only in different vertebrate lineages but also between different fish species. 相似文献
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Maryam Moradi Hadi Hajarian Hamed Karamishabankareh Leila Soltani Bijan Soleymani 《Reproduction in domestic animals》2021,56(2):263-269
Pre-conceptual sex selection is still a highly debatable process whereby X and Y chromosome bearing spermatozoa are isolated before oocyte fertilization. Recently, magnetic nanoparticles (MNP) have been used to determine X and Y chromosomes bearing spermatozoa as a result of searching for a cheap, highly efficient method using non-toxic materials. This study aimed to recover the sperm bearing X chromosomes in ram with different concentrations of MNP and then evaluate the success of this method using polymerase chain reaction (PCR). Ram sperms were divided into four groups, treated with 0 (control), 50, 100 and 200 μg/ml MNP, respectively. MNP was used to restore sperm cells bearing X chromosomes. Upon recovery, the PCR was performed to identify the X and Y sperms, Methyl ThiazoleTetrazolium (MTT), to assess MNP toxicity and sperm viability and acridine orange (AO) to evaluate sperm DNA integrity. The results of PCR revealed that the treatment of spermatozoa- bearing X chromosomes with 50 μg/ml MNP had the highest effects on the recovery of X sperm rather than the other concentrations of MNP. However, the concentrations of MNP did not have any toxic effects on spermatozoa, sperm viability and, DNA integrity, but the high concentration of MNP (200 μg/ml) significantly reduced DNA integrity. According to MTT and AO results, the concentrations of MNP used in this study had no toxic effects on spermatozoa and did not reduce the sperm viability and DNA integrity, except that 200 μg/ml MNP significantly reduced DNA integrity. 相似文献
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A cytogenetical study using metaphase chromosomes from cultured lymphocytes, was made of 2 Banteng (Bibos banteng) steers and 218 bulls representing 13 purebreeds (Bos taurus type, Bos indicus type and Sanga) and 7 cross-breeds. Studies were made of photographic karyotypes of Giemsa stained and C-banded chromosomes of bulls of each breed and of B-banded chromosomes from 3 breeds of Bos indicus and one cross-breed Australian Friesian Sahiwal) cattle. The relative lengths of chromosomes of Bos taurus and Bos indicus bulls were compared and significant difference in relative lengths of the X chromosomes were noted between these two species. There was a differences in morphology of the Y chromosomes; Sanga, Banteng and Bos taurus type breeds had a small submetacentric Y chromosome, except for the Jersey which had a metacentric Y chromosome. All Bos indicus type bulls had an acrocentric Y chromosome but the Droughtmaster breed had two forms of the Y chromosome (submetacentric and acrocentric). The C-banding patterns of the autosomes and X chromosomes were similar for all breeds while those of the Y chromosomes of Bos indicus type cattle allowed their accurate identification. G-banding patterns of Bos indicus resembled those of Bos taurus and enabled pairing of homologous chromosomes. Centromeres of the autosomes were unstained but those of the sex chromosomes were darkly stained. 相似文献