棕色田鼠罗伯逊易位的研究(简报)

棕色田鼠(Microtus mandarinus Milne-Edwards,1871)又称北方田鼠,主要分布于我国。前苏联、蒙古的少数地区亦有分布,前苏联学者称该鼠为中国田鼠。关于该鼠的染色体研究国内外已有报道。仅推测罗伯逊易位是引起该鼠第一对常染色体多态及其染色体数目多态的主要原因。本文详细研究了该鼠第一对常染色体多态类型与个体染色体数目之间的一一对应关系、性个体(2n=51)的G带带型及其联会复合作中三价体的存在,完全证实了     

人类染色体罗伯逊易位及其与疾病相关性

人类罗伯逊易位是指罗伯逊融合,主要有D/D、D/G、G/G三种类型的易位。易位涉及到着丝粒、rRNA基因、断裂点位置及相关基因的活性等的变化,因此对机体的影响也是多方面的,其中减数分裂时配子的不平衡分配是导致后代各种多发症的原因。同时,罗伯逊易位在人类核型的演化过程中也可能起着一定的作用。     

温岭高峰牛的2/27罗伯逊易位

对11头伪e,29）饲养于浙江省温岭县的温岭高峰牛做了细胞遗传学检查。发现2头公牛和z头母牛是易位杂合体。经G带鉴别,为染色体2/27罗伯逊易位。     

棕色田鼠的细胞遗传学研究

本次首次报告棕色田鼠（Microtus mandarinus)的核型,核型公式为2n=50=2(M,T) 2SM 44T XX(M,SM),XY(SM,ST),发现第一对常染色体及X性染色体存在多态现象,在所研究的15只雌性个体中有7只雌性个体的细胞只有1条X性染色体,性染色体组成为XO型,核型公式为2n=49=2(M,ST) 2SM 44T＋XO,。其中X性染色体不同于雄性中的X（SM）,为M类型,本文提出的综色田鼠3种核型与Brown等人（1964）提出的Microtus oregoni的3种核型（XO,YO,XY）有异,本文还阐述了染色体多态产生的机制和探讨了XO型个体发生的机理及其繁殖。     

棕色田鼠种群年龄的研究

１９９１年２月至１９９２年４月,在河南省灵宝市、卢氏县捕获棕色田鼠１１１６只（雄５１５．雌６０１）,应用洞体重作指标,参考繁殖状况及毛色,将种群划分为５个年龄组：Ⅰ．幼体组,≤１１．５ｇ;Ⅱ．亚成体组,１１．６一２０．５ｇ;Ⅲ;成体Ⅰ组,２０．６一２６．０ｇ;Ⅳ。成体Ⅱ组,２６．１一３０．５ｇ;Ⅴ老体组,＞３０．６ｇ。对比体重、体长及头骨量度,胴体重法较能客观反映年龄状况。随季节变化,春季Ⅰ、Ⅱ组占优势,夏季Ⅱ、Ⅲ组占优势,秋季、冬季Ⅴ组数量增加,而其它各组的数量比较均匀。     

罗伯逊易位分子机理初探

目的：探讨复发性自然流产与染色体罗伯逊易位间的关系。方法：采用人外周血淋巴细胞培养,常规G显带技术行染色体核型检查,并结合临床资料对其进行分析。结果：57对复发性自然流产夫妇中,检出罗伯逊易位染色体核型4例,检出率3.51%。结论：罗伯逊易位是导致复发性流产的重要原因之一,对复发性自然流产患者进行常规的染色体检查及遗传咨询具有一定的临床意义。     

棕色田鼠和沼泽田鼠的气味识别

把棕色田鼠或沼泽田鼠暴露于同种个体底物(个体饲养箱内的锯末)1h,不同组别的田鼠在间隔15min、30min、60min后,记录对暴露过的熟悉底物和另一个陌生底物的访问、嗅闻、挖掘等社会探究行为(每组在每一个时间间隔只试验1次),统计分析发现,田鼠在暴露于同种异性底物,然后间隔不同的时间后,总是倾向于选择熟悉同种异性底物;田鼠在暴露于同种同性底物,然后间隔不同的时间后,总是倾向于选择陌生同种同性底物;棕色田鼠在暴露于同性底物1h,然后间隔60min后,对陌生的同性底物有明显多的探究行为,但沼泽田鼠在同种情况下却没有表现出这种选择倾向。在暴露底物1h,然后间隔60min后,雌性田鼠比雄性田鼠表现出更明显的选择倾向。以上结果表明不同种类和性别的田鼠对气味表现出不同的识别模式。这种差异可能表明不同种具有木同的社会组织、生态和生活史对策。     

罗伯逊易位研究的进展

本文总结了罗伯逊易位研究的现状、内容和技术方法,并对它在畜牧品种的改良、分子遗传学方面的应用作了探讨,指出了它在研究进化生物学方面的重要意义。 Abstract:Robertsonian translocation is important in the study of evolution biology.Current progress,contents,technology and methods about Robertsonian translocation studies are introduced in the article.The usefulness in improving the breeds of pasturages and molecular genetic aspect are also discussed.     

棕色田鼠XO雌体育性研究

通过对棕色田鼠外形特征,卵巢切片,怀胎和生产雌鼠染色体鉴定等方面研究,证实了该鼠ＸＯ雌鼠可孕,并具有生殖能力。染色体鉴定表明,ＸＸ雌体中的两条Ｘ性染以体,一条为Ｍ类型另一条为ＳＭ类型;ＸＯ雌体中的Ｘ性染色体为Ｍ类型。所以ＸＯ雌性的生育能力可能与Ｘ染色体有关,其上可能存在雌性育性基因。     

罗伯逊易位群体遗传结构的DNA指纹分析

用微卫星探针（GGAT）4得到了罗伯逊易位猪群体内共9个家猪品种的DNA指纹图。1－9品种依次为：13／17罗伯逊易位纯合子猪群体、13／17罗伯逊易位杂合子猪群体、13／17罗伯逊易位杂合子猪互交所得到的正常核型猪群体（杂交0号）、丹系长白猪群体、加系双肌臂杜洛克猪群体、加系双肌臀大约克猪群体、加系双肌臀长白猪群体、丹系长白猪与13／17易位杂合子猪产生的杂交后备猪群体（杂交1号）、杜洛克猪与13／17易位杂合子猪产生的杂交后备猪群体（杂交2号）。根据指纹带型计算了每个群体的相似系数（F）、平均等位基因频率（Q）、最底平均杂合率（H）和遗传距离指数（D）。9个品种的相似系数介于0．546－0．931,根据各品种之间的遗传距离指数作出矩阵图,并据此绘制出品种间亲缘关系树状聚类图。     

棕色田鼠不同性别中R-spondin1基因的特殊表达

哺乳动物睾丸决定的诱导一般依赖于Sry基因,然而棕色田鼠指名亚种的Sry基因已经丢失,而棕色田鼠指名亚种雌雄个体依然有繁殖能力。我们在研究涉及性别决定的一些基因时,发现R-spondin1与性别决定有关。为了探讨R-spondin1在棕色田鼠中的性别决定中的作用,我们用RT-PCR检测R-spondin1在棕色田鼠性腺中的表达。研究结果表明R-spondin1仅在出生后不久的棕色田鼠指名亚种雌性个体的卵巢中表达,在出生后的棕色田鼠指名亚种雄性个体睾丸中未见其表达,这说明R-spondin1可能在棕色田鼠指名亚种卵巢发育中具有某种角色。     

Sex determination of Microtus mandarinus mandarinus is independent of Sry gene

PCR was performed with primers corresponding to the Sry HMG-box of the mouse and eight Microtus species. Primers for the SALL4 gene and the ZFY/ZFX gene were used as positive controls. None of these sets of primers can amplify any homologous segment of the Sry gene in the genomic DNA of Microtus mandarinus mandarinus, but both can amplify the Sry HMG-box in the male mouse, SALL4 bands, and ZFY/ZFX bands in both male and female M. m. mandarinus and mouse. Southern blotting was also used. We used primers for the mouse Sry HMG-box to amplify the Sry HMG-box of the mouse, Microtus arvalis (Microtus), and Pitymys duodecimcostatus (Microtus). The probes were labeled with digoxigenin using PCR after being sequenced. Southern blots were used to detect the genomic DNA of M. m. mandarinus using alkaline phosphatase detection. The results showed that there was a 3.95-kb-blotting band in positive controls: mouse, Microtus arvalis, and Pitymys duodecimcostatus. However, no homologous sequence of the Sry HMG-box was detected in the genomic DNA of M. m. mandarinus. Therefore, we speculate that the Sry HMG-box of M. m. mandarinus is absent or had a big change; sex determination of M. m. mandarinus is independent of Sry. The sex determination mechanism without Sry of M. m. mandarinus is also discussed.     

棕色田鼠性别决定研究进展

哺乳动物性别决定方式属于雄性异配型性别决定, 依赖于Y染色体, SRY基因是性别决定中最重要的基因。文章报道了棕色田鼠指名亚种有Y染色体, 但是Y染色体上没有SRY基因, 性别决定不依赖于SRY基因, 排除了R-spondin 1基因是性别决定基因, 同时讨论了棕色田鼠指名亚种SRY基因缺失后可能的性别决定 机制。     

Exclusion of Sall 4 as the sex-determining gene in the Mandarin vole Microtus mandarinus mandarinus

In previous studies, we have shown that the Sry HMG-box is absent in Microtus mandarinus mandarinus (M. m. mandarinus), suggesting that sex determination of M. m. mandarinus is independent of the Sry gene. We amplified a 312 bp fragment within exon 2 of the Sall4 gene in the mouse and M. m. mandarinus using polymerase chain reaction (PCR) and detected Sall4 using fluorescence in situ hybridization (FISH) technique. The probes for the Sall4 gene were labeled with digoxigenin using PCR and hybridized to chromosomes and interphase nuclei of the mouse and M. m. mandarinus. Our results suggested that Sall4 exists in the genome of male and female M. m. mandarinus, and the sequence within exon 2 of the gene is the same in the mouse and M. m. mandarinus. The results also showed that Sall4 is localized on chromosome 6 in M. m. mandarinus. As they are the sex chromosomes in M. m. mandarinus, the results excluded the Sall4 gene from being the testis-determining factor in this species. We propose that in M. m. mandarinus, sex determination is controlled by another yet unknown gene on the sex chromosomes.     

The origin of the genetical diversity of Microtus mandarinus chromosomes

Here we describe our comparative studies on two types of X chromosomes, namely X(M) and X(SM,) of the mandarin vole (Microtus mandarinus). By chromosome G- and C-banding analysis, we have found that two different types of X chromosomes exist in mandarin voles. The two types of X chromosomes present two different G- and C-banding patterns: the X(M) chromosome is a longer metacentric X chromosome which is C-band negative; and the X(SM) is a shorter submetacentric X chromosome which has one C-band at the centromere and another one at the middle part of the short arm. The X(SM) has 6 G-bands including one on the kinetochore, one in the middle of the short arm, and four on the long arm. The X(M) has 7 G-bands including one on the kinetochore, two on the short arm, and four on the long arm. We have further found that female voles can be grouped into three types based on the composition of the X chromosome but the male voles have only one type. The three female groups are: (1) female voles (X(M)X(SM)), in which the two X chromosomes are different, the longer one is metacentric and the shorter is submetacentric; (2) female vole (X(SM)X(SM)), in which the two X chromosomes are both submetacentric; (3) female vole (X(M)O), in which there is only one X chromosome that is metacentric. Surprisingly, we have never found female voles with X(M)X(M), females with X(SM)O or males with X(M)Y. We hypothesize that the X(SM) chromosome is derived from the X(M) through its breakage and re-joining. The paper also discusses the formation of X(M)O females.     

棕色田鼠XO雌体的减数分裂

采用诱导卵泡发育、卵母细胞培养、制备减数分裂染色体标本等技术 ,对棕色田鼠两种雌体 (XO、XX)的减数分裂进行了比较研究。研究结果表明 :棕色田鼠XO和XX雌体在表型和内外生殖器结构上无差异 ;在用孕马血清促性腺激素刺激XO雌体和XX雌体后 ,两者卵巢上的有腔卵泡数目相近 ;两者产生的卵母细胞数目、生发泡破裂数目以及第一极体排放数目 ,统计学分析差异都不显著。同时表明XO雌体的减数分裂过程正常 ,能得到卵母细胞中期Ⅱ分裂相。据此我们认为 :雌体 (XO)与雌体 (XX)的卵巢功能都正常 ,两者的卵母细胞均具有较强的成熟能力且无差异。因此 ,棕色田鼠XO个体是核型异常、育性正常的雌体。另外 ,具有三种遗传性别的棕色田鼠可能是处于XX/XY与XO/XY性别决定系统进化途径的中间类型 ,其性别决定系统仍处于变化之中     

棕色田鼠血液生理生化指标的测定

报道了棕色田鼠指名亚种的正常血象值及几项血液生化值。结果表明,各项备注学和血液生化学参数值在成年个体间无性别差异（附红细胞数、血红蛋白浓度、红细胞压积外,但此三项指标尚未达到极显著差异水平）。与其它仓鼠科动物的血液生理生化参数值相比较,棕色田鼠除红细胞数、血红蛋白浓度及中性粒细胞略低外,其它各项参数虽有差异,但均无统计学意义。     

棕色田鼠的发声及其频谱分析

对不同年龄的棕色田鼠在不同状态下的发声进行了声谱分析,以研究其发声与行为之间的关系及其发育规律。棕色田鼠幼体的频谱图较简单,一般有１－２个波峰,主能峰频率在１８００ＨＺ左右,且能量区为１个,位于中频区（１３００－２５００ＨＺ）;发声以单音节为主,持续４０－１００μｓ。亚成体频谱图较幼体复杂,为２个相近的能量区,均位于中频区（７５０－１３２０Ｈｚ,１４３１－１５７０Ｈｚ）,ＭＰＦ＝９４５Ｈｚ;叫声单