少、弱精子症生殖激素水平与染色体核型改变的研究

目的探讨少、弱精子症病人的遗传因素和内分泌因素。方法收集少、弱精子症病例240例,取外周血做染色体核型分析,然后全部病人取血用化学发光法检测血清泌乳素(PRL)、卵泡刺激素(FSH)、黄体生成素(LH)、睾酮(T)水平。结果 240例少、弱精子症患者染色体核型分析中,检出39例异常染色体核型。其中染色体平衡易位3例,罗氏易位3例,随体增加4例,性染色质改变29例。在生殖激素水平的检测中,与201例染色体正常组相比,39例染色体异常组的FSH和LH值均明显升高(P<0.01),而T值明显降低(P<0.01),PRL值差异无统计学意义(P>0.05)。结论染色体异常是导致少、弱精子症发生的一个重要原因,染色体异常可能是通过生殖激素水平的改变起作用。     

识别正常人类G带染色体的标准与鉴别检索表——Ⅱ.Prometaphase haploid 500带期

<正> 4.染色体最大。P上有9个深色带.其中第1带(P21)最宽,其次为第3带(P31.1),其余带均窄。P端部为浅色带。q远端的4个带的宽窄大小由近至远的顺序为窄宽窄宽(即q32.2q42.2相似文献   

Atomic force microscopy of plant chromosomes

Atomic force microscopy has been used to image plant chromosomes from standard preparations without staining or coating. This has enabled the collection of high-resolution three-dimensional data on surface structure. The technique has been further applied to the imaging of C-banded chromosomes revealing structural changes resulting from the banding treatment. The bands were observed as localized areas of high relief.     

High-resolution cytological localization of theXhol andEcoRI repeat sequences in the pachytene ZW bivalent of the chicken

The pachytene ZW pair of the chicken has been studied with a novel combination of fluorescentin situ hybridization and silver staining of the synaptonemal complexes, and with electron microscopicin situ hybridization. Probes for theEcoRI and theXhol repeat sequences were used for light microscopy and probes forXhol for electron microscopy.Xhol repeats are pericentromeric and correspond to 27.3% of the W axis length.EcoRI repeats form three distinct domains: domain I covers the distal 19.4% of the late-synapsing arm, and domains II and III cover respectively 21.7% and 8.5% of the W axis. The early-synapsing end containing the recombination nodule is free from any of both signals. This non-hybridizing region accounts for 25.9% of the W axis. It is suggested that this region is composed of a proximal region containing other repeat types and a terminal region which is the recombining or pseudoautosomal region. The successful combination of silver staining and fluorescentin situ hybridization will be generally useful for high-resolution localization of DNA sequences in meiotic chromosomes.     

亚砷酸盐对小鼠细胞遗传学效应的实验研究

本文报告了亚砷酸钠引起小鼠骨髓细胞的细胞遗传学效应。作者测定了亚砷酸盐在小鼠体内引起染色体畸变、姊妹染色单体交换和微核率的改变。试验结果表明,砷化物在体内未能引起染色体畸变,这和体外试验结果有所不同。但砷化物可使体内姊妹染色单体交换频率和微核率升高,这和体外试验结果是一致的。作者最后对砷化物引起的体内试验和体外试验结果进行了讨论。     

The influence of B chromosomes on rDNA organization in rye interphase nuclei

Patterns of rye rDNA organization in interphase nuclei were studied through the use ofin situ hybridization in spreads of root meristem cells from plants with and without B chromosomes (Bs). In cells from plants without Bs each rDNA locus is organized as a single perinucleolar knob of condensed chromatin with decondensed chromatin inside the nucleolus. In plants with Bs there is a marked modification of the pattern, found in more than 23% of nuclei, which involves several regions of condensed chromatin interspersed with decondensed chromatin inside the nucleolus. This B-induced alteration in rDNA interphase organization suggests a change in expression of the rRNA genes located on the A chromosomes probably related to the reduction in nuclear RNA observed previously in plants with Bs. The influence of the Bs on the expression of A chromosome genes, through rearrangement of interphase chromatin, could provide the basis of an explanation for some of the known phenotypic effects of B chromosomes in rye.     

Impact of rearrangements on function and position of chromosomes in the interphase nucleus and on human genetic disorders

A synthesis of numerous published data and my own observations reveal that chromatin structure in interphase is functional, dynamic and complex. I hypothesize that: (1) chromosome regions organize nuclear structures and thus their own environment (address themselves in sites and condensation patterns most appropriate for their functional state in the particular cell); (2) chromosome rearrangement could alter nuclear architecture and thus function; and (3) these ideas can explain the contribution of chromosome rearrangements, even in a balanced form, to human pathologic conditions.     

Chromosome testing in children with developmental delay in whom the aetiology is not evident clinically

A review was carried out to establish the value of chromosome testing in children with significant developmental delay, where the aetiology was not evident clinically. During 1990, 315 children had been assessed at a child development clinic and found to be significantly delayed in one or more areas of development; in 256, the aetiology was not evident clinically. Chromosome testing of these children revealed an abnormality in 10 (3.9%). Thirty children had dysmorphic features; six (20%) of these had an abnormal karyotype. Four (2%) of the 226 who had no dysmorphic features had a chromosome abnormality. One hundred and fifty-five children had intellectual disability; eight (5%) of these had an abnormal karyotype. Two (2%) of 101 who had a specific delay in their development had a chromosome abnormality. The advantages of chromosome testing in children with developmental delay in whom the aetiology is not evident clinically are discussed.     

Meiotic behavior of the X1X2Y1Y2 quadrivalent of the primateAlouatta caraya

A multiple sex chromosome system was found in three unrelated individuals of the primateAlouatta caraya. This mechanism is originated by a translocation between the Y chromosome and one of the autosomes (A7). Mitotic karyotypes show two small, acrocentric chromosomes (A^Y and Y^A), which are the translocation products. In metaphase I of male meiosis, there is a very long chain quadrivalent in which the order of the element is: X–Y^A–A7–A^Y. Segregation in the quadrivalent is alternate and gives balanced products. Synaptonemal complex karyotypes at pachytene show the structure of the quadrivalent made by the four axes. There is a slight difference in the relative length of A^Y and Y^A and the kinetochore of A7 aligns with that of A^Y. The synaptic pattern and changes in the quadrivalent during pachytene are described. Thin sections of the quadrivalent body show that the chromatin packing in the sex chromosome region is different from that of the autosomal region. This X1X2Y1Y2/X1X1XX2 sex chromosome system may be extended among other members of the genusAlouatta.accepted for publication by M. Schmid