Nuclear localization of the testis determining gene product SRY

We have studied the expression of the human SRY protein (termed p27SRY) in two different cell lines by using specific antibodies. Confocal microscopy enabled us to localize p27SRY precisely in the nucleus in a discrete punctuate pattern. Furthermore, through microinjection experiments, we have demonstrated that the localization of the p27SRY protein into the nucleus was an event involving the NH2-terminal part of the high mobility group (HMG) domain. With the help of several synthetic peptides and various p27SRY mutants, we have characterized a bipartite basic motif in this part of the protein corresponding to a nuclear localization signal. This nuclear localization signal appears to be highly conserved in SRY box- and HMB box-containing proteins, suggesting common properties of nuclear targeting within the HMG box protein family.     

Assignment of the casein kinase II gene family to cattle chromosomes

Theileriosis, or East Coast fever, a parasitic disease in cattle, is associated with overexpression of casein kinase II. Casein kinase II is composed of two catalytic subunits (α or α') and two regulatory β subunits. The genes encoding these subunits of casein kinase II were mapped to bovine chromosomes by polymerase chain reaction analysis of a well-characterized bovine × rodent somatic hybrid cell panel. The α-subunit (CSNK2A1) was mapped to bovine chromosome 13, the α'-subunit (CSNK2A2) to chromosome 5 and the β-subunit (CSNK2B) to chromosome 23. Both CSNK2A1 and CSNK2B mapped to known regions of conserved synteny between human and cattle, while CSNK2A2 defined a new homology segment between the human and bovine genomes.     

The heterochromatin regions of the mitotic chromosomes in cattle]

Cytochemical and molecular peculiarities of heterochromatic regions of bovine chromosomes have been studied, using specific fluorochrome staining induced decondensation, in situ hybridization, pretreatment of restriction enzymes. The heterochromatin of autosomes demonstrated a strong homogeneity. In chromosome Y two small specific heterochromatic regions were found lacking a long repeated tandem block of nucleotides enriched in GC base pairs and having no tandem block of Bkm repeats (10(4) b.p.). This class repeats are probably interspersed in the bovine genome. A rather seldom character of mammalian karyotypes is the absence of cytochemical heterochromatin in the X chromosome.     

p38 MAPK在小鼠睾丸不同发育阶段的表达和定位

为探讨丝裂原活化蛋白激酶p38 MAPK在小鼠睾丸不同发育阶段的表达,应用蛋白质免疫印迹杂交技术和免疫组织化学SABC法检测1至7周龄小鼠睾丸p38 MAPK的表达、定位及发育变化,并通过图像分析技术对免疫组织化学结果进行统计学分析。免疫印迹杂交发现,p38 MAPK在2～7周龄小鼠睾丸中均有表达。免疫组织化学结果显示,在2周龄小鼠睾丸曲细精管上皮中即可观察到p38 MAPK免疫阳性反应,免疫反应阳性细胞为精原细胞;3、4、5周龄小鼠睾丸仅有个别曲细精管上皮可见p38 MAPK免疫阳性反应;6、7周龄小鼠睾丸中p38 MAPK表达较丰富,免疫反应阳性细胞为精原细胞和初级精母细胞,免疫阳性反应物均主要位于细胞核内。在7周龄小鼠睾丸中还可见到部分间质细胞的细胞质亦呈p38 MAPK阳性。这些结果提示,p38 MAPK可能对生精细胞的增殖分化具有调控作用。     

The location of repeated DNA sequences in the chromosomes of Chironomus tentans

Polytene chromosomes of Chironomus tentans were hybridized in situ with in vivo labelled nuclear and chromosomal RNA. Nuclear RNA formed hybrids preferentially in five distinct regions considered to contain clustered, repeated DNA sequences. These are the two nucleolar organizer regions, Balbiani ring 1 and 2, and the 5 S RNA genes in region 2A of chromosome II, which together comprised almost 70% of the total number of grains over the complement. The remaining grains were diffusely distributed over the chromosomes. There was a significant difference in the distribution of grains when RNA from different chromosomes was used for hybridization. Chromosome I RNA hybridized preferentially with chromosome I, and chromosome II+III RNA preferentially with chromosome II+III. Some regions within the chromosomes hybridized significantly more chromosomal RNA than other regions. A considerable cross-hybridization of RNA from one particular type of chromosome with the other chromosomes was also found. It is concluded that repeated DNA sequences which hybridize with heterogeneous chromosomal RNA in C. tentans are widely dispersed in the genome. Some of these sequences have a delimited localization, others are dispersed, and some sequences which are transcribed in one particular chromosome are present also in the other chromosomes.     

Chromatin condensation behaviour of the Y chromosomes in the human testis

The condensation behaviour of the human Y chromosome in germ cells and Sertoli cells of pre- and post-pubertal testes was followed by fluorescence in situ hybridisation using probes for three different regions of the Y chromosome. Patterns of expansion or contraction of signal are taken to reflect degrees of condensation of the related Y chromatin and hence its potential for genetic activity. For probe pHY2.1, which labels the distal non-fluorescent and fluorescent heterochromatin of the Y chromosome (Yq12), an expanded signal seen in gonocytes of the prepubertal testis is superseded by a condensed signal seen in adult germ cells at all but the zygotene stage of meiotic prophase when meiotic pairing takes place. In contrast, Sertoli cells show a condensed signal pre-pubertally but a greatly expanded signal in the adult testis. A totally condensed pHY2.1 signal is found in a chromosomally normal man with Sertoli-cell-only syndrome. It is hypothesised that control over at least some facets of spermatogenesis may not, in the adult, be autonomous to the germ cells, but rather may emanate from the Sertoli cells. Chromatin expansion at zygotene could, however, be important for pairing and crossing over in the XY bivalent, successful synapsis ensuring survival of spermatocytes into the post-meiotic stages.     

The location of highly repetitious DNA in the somatic chromosomes of Drosophila melanogaster

In situ hybridization of Drosophila melanogaster somatic chromosomes has been used to demonstrate the near exact correspondence between the location of highly repetitious DNA and classically defined constitutive heterochromatin. The Y chromosome, in particular, is heavily labeled even by cRNA transcribed from female (XX) DNA templates (i.e., DNA from female Drosophila with 2 Xs and 2 sets of autosomes). This observation confirms earlier reports that the Y chromosome contains repeated DNA sequences that are shared by other chromosomes. In grain counting experiments the Y chromosome shows significantly heavier label than any other chromosome when hybridized with cRNA from XY DNA templates (i.e., DNA from male Drosophila with 1 X and 1 Y plus 2 sets of autosomes). However, the preferential labeling of the Y is abolished if the cRNA is derived from XX DNA. We interpret these results as indicating the presence of a class of Y chromosome specific repeated DNA in D. melanogaster. The relative inefficiency of the X chromosome in binding cRNA from XY and XYY DNA templates, coupled with its ability to bind XX derived cRNA, may also indicate the presence of an X chromosome specific repeated DNA.     

The location of ribosomal cistrons (rDNA) in chromosomes of the rat

In situ hybridization of ³H-labelled ribosomal RNA to the chromosomes of rat bone marrow cells revealed that clusters of ribosomal cistrons (rDNA) are located in the secondary constrictions of chromosomes No. 3 and 12 and near the centromere of chromosome No. 11, both associated with the late DNA-replicating regions. They were not found in Nos. 1, 2, 13, 19, 20, and the Y chromosome.     

Specificity of the location of human chromosomes in the nucleus of a moving cell

Data are presented on the distribution of centromeric heterochromatin of the human X-chromosome in the interphase nucleus of a moving cell. The in situ hybridization made it possible to obtain some results leading to the following conclusions: in moving fibroblasts centromeric heterochromatin of the X-chromosome is located in end regions of the interphase nucleus; there was no preferential localization noted of the centromeric region of the X-chromosome in the front or back areas of the nucleus as to the direction of the movement.     

基因在染色体上的定位

概述了染色体的发现和基因在染色体上定位的荧光原位杂交技术,放射杂交体法,重叠群拼接和染色体步移及基因定位克隆的常用方法以及基因定位的应用。     

The location of the gene for haemophilia

Summary Sirks' theory that the gene for haemophilia can cross over between the X and Y chromosomes is critically examined. The cross-over frequency must be of the order of one in ten thousand. Some difficulties in the theory are pointed out, and methods by which it may be tested are discussed.     

The interaction of knobs and B chromosomes of maize in determining the level of recombination

Enhancement of recombination by B chromosomes is influenced by the kind of heterochromatic knob present in or near the tested region of the A chromosomes. In homomorphic chromosome 9 bivalents of K^s/K^s constitution, double exchanges were increased at the expense of singles, but in the K*/K^s heteromorphs there was a gain in both single and double exchanges at the expense of no-exchange tetrads. Modification of the B chromosome enhancement in different knob compounds was observed only in the megasporocytes.—Different frequencies of recombination are found in plants with odd and even numbers of B chromosomes; this effect is especially striking in the megasporocytes. The modification in recombination produced by an odd or even number of B chromosomes is a function of the interaction of a particular region and the knob constitution. Odd numbers of B chromosomes were more effective than even numbers in causing increased recombination.—It is concluded that heterochromatic knobs and the essentially heterochromatic supernumeraries may interact in the process of crossing over, with the level of recombination determined in part by knob constitution.