p53基因在RA诱导SH-SY5Y细胞分化后低表达

全反式维甲酸(RA)的抑制肿瘤细胞生长和调控细胞分化的作用是一项重要的研究课题。而p53基因是一个重要的肿瘤抑制基因,在RA的作用中是否涉及到p53的作用尚有待阐明。本文用低浓度的RA(10 μmol/L)作用于SH-SY5Y细胞,每2d换一次液,在作用9 d后,用光学显微镜观察SH-SY5Y细胞的形态学变化,并提取细胞质总RNA进行RT-PCR反应半定量检测p53基因表达。结果显示,SH-SY5Y细胞经RA诱导后,细胞生出较长的突起,具有神经元的形态;而对照组保持成纤维细胞的形态、无明显的形态学变化。RT-PCR半定量显示,在细胞诱导后,p53基因表达明显下调。本文结果提示,RA的作用可能独立于p53基因途径,p53基因的表达变化可能是继发于RA的作用。     

DNA analysis of two patients with a non-fluorescent y chromosome

Summary Results of DNA study on two patients of gonadal dysgenesis with a 45,X/46,X,Ynf (non-fluorescent Y chromosome) karyotype are described. In one patient who developed gonadoblastoma, all 12 loci on the non-fluorescent part of Yq were detected. Another patient did not have gonadoblastoma at 20 years, and only the proximal 6 loci out of 12 were detected.     

A molecular and FISH analysis of structurally abnormal Y chromosomes in patients with Turner syndrome

Fourteen patients with Turner syndrome and a structurally abnormal Y chromosome were analysed by PCR amplification and fluorescence in situ hybridisation for the presence of sequences specific to defined regions of the Y chromosome. Thirteen patients had a mosaic karyotype including a 45,X cell line and one case was non-mosaic in cultured lymphocytes. Ten patients had a pseudodicentric Yp chromosome, two an isodicentric Yq, one a pseudodicentric Yq, and one a derived Y chromosome. Two of the patients with a psu dic(Yp) chromosome had complex karyotypes with more than two cell lines, one of which exhibited five morphologically distinct mar(Y) chromosomes, presumably derived from a progenitor psu dic(Yp). Nine of the ten psu dic(Yp) chromosomes were positive for all Yp and Yq probes used except DYZ1 which maps to Yq12, suggesting a common breakpoint near the Yq euchromatin/heterochromatin boundary. In the three patients with a dicentric Yq chromosome two different breakpoints were observed; in two it was between PABY and the subtelomeric repeat sequence and in one it was between DYZ5 and AMGY in proximal Yp. Our results suggest that the great majority of structurally abnormal Y chromosomes found in Turner syndrome mosaics contain two copies of virtually all of the functional Y chromosome euchromatin.     

Supernumerary marker chromosomes (SMCs) in Turner syndrome are mostly derived from the Y chromosome

DNA and FISH (fluorescence in situ hybridization) analysis were carried out in 12 patients with stigmata of Turner syndrome to determine whether the Supernumerary M arker C hromosome (SMC) found cytogenetically in each of these patients was derived from the Y chromosome. The presence of a Y chromosome in these patients may predispose them to develop gonadoblastoma. PCR-Southern blot analysis, followed by FISH, was used to detect the presence of Y chromosome material. The S ex determining R egion Y (SRY), T estis S pecific P rotein Y -encoded (TSPY) and Y -chromosome R NA R ecognition M otif (YRRM) genes, which map at Yp11.31, Yp11.1–11.2 and Yp11.2/Yq11.21–11.23, respectively, were selected as markers, because they span the whole Y chromosome, and more importantly, they are considered to be involved in the development of gonadoblastoma. It was shown that in 12 patients, all of whom had an SMC, the SMC of 11 was derived from the Y chromosome. Furthermore, the presence of the SRY, TSPY and YRRM gene sequences was determined and FISH analysis confirmed the Y origin of the SMCs. The methodology described in this report is a rapid, reliable and sensitive approach which may be easily applied to determine the Y origin of an SMC carried in Turner syndrome. The identification of an SMC is important for the clinical management and prognostic counseling of these patients with Turner syndrome.     

Partial gonadal dysgenesis in a patient with a marker Y chromosome

We evaluated a patient with partial gonadal dysgenesis including a right dysgenetic testis and a left streak gonad with rudimentary fallopian tube and uterus. She had ambiguous external genitalia and was raised female. Although her height is normal (25th centile at age 12 years), she has some findings of Ullrich–Turner syndrome. Her karyotype was reported to be 46, X, + marker; subsequent molecular investigations showed the marker to be the short arm of the Y chromosome. Genomic DNA, isolated from leukocytes of the patient and her father, was digested with a variety of restriction endonucleases and subjected to Southern blot analysis. A positive hybridization signal was obtained with probes for the short arm of the Y chromosome (pRsY0.55, SRY, ZFY, 47Z, pY-190, and YC-2) in DNA from the patient, indicating the presence of most if not all of the short arm, while long arm probes (HinfA and pY3.4) indicated that at least 75% of the long arm of the Y chromosome was missing. The gene responsible for testicular determination (TDF) is on the distal portion of the short arm of the Y chromosome; Yq has no known influence on sex determination. Hence, the deletion of the long arm of the Y chromosome cannot explain the gonadal dysgenesis in this patient. One explanation for the gonadal dysgenesis and Ullrich–Turner phenotype in the patient could be undetected 45, X/46,X, + marY mosaicism but no such mosaicism was observed in peripheral lymphocytes. Several investigators have suggested the presence of an “anti-Turner” gene near TDF. Hence it is possible that the clinical phenotype in our patient results from a Y chromosomal defect in sequences flanking TDF, which reduces the function of both TDF and the “anti-Turner” genes.     

Intracerebroventricular infusion of neuropeptide Y up-regulates synthesis and accumulation of luteinizing hormone but not follicle stimulating hormone in the pituitary cells of prepubertal female lambs

Neuropeptide Y (NPY) is a putative neuroregulator of the reproductive axis in the central nervous system. In this study we evaluated the effects of central infusion of exogenous NPY on the secretory activity of pituitary gonadotrophic cells in prepubertal lambs. Immature female Merino sheep (n=12) were infused of Ringer solution (control) or 50 microg of NPY to the third ventricle for 5 min and then slaughtered 3 h later. Immunoreactive luteinizing hormone (LH) and follicle stimulating hormone (FSH) cells were localised by immunohistochemistry using antibody raised against LHbeta and FSHbeta. Messenger RNA analyses were performed by in situ hybridisation using sense and antisense riboprobes produced from beta subunits of LH and FSH cDNA clones. The results were generated by computer image analysis to determine the area fraction occupied by immunoreactive and/or hybridising cells and optical density for immunostaining and hybridisation signal. LH in the blood plasma was determined by radioimmunoassay. It was found, that in the lambs infused with NPY the area fraction and optical density for immunoreactive LH cells and mRNA LHbeta-expressing cells increased significantly (P<0.001), compared to the vehicle-infused animals. The concentration of LH in the blood plasma did not differ between control and treated groups. The NPY infusions had no effect on the immunoreactivity of FSH cells or on expression of mRNA for FSHbeta. In conclusion we suggest that NPY may be an important component of mechanisms stimulating the synthesis and storage but not the release of LH in the pituitary gonadotrophs from prepubertal female sheep. In addition, this effect is specific for LH, no such effect was apparent on FSH.     

Occurrence of neuropeptide Y (NPY)-like immunoreactivity in catecholamine neurons in the human medulla oblongata

We report here the coexistence of a neuropeptide and catecholamines in neurons of the human brain. Using indirect immunofluorescence histochemistry, combined with elution and restaining experiments, neurons in the medulla oblongata of man were demonstrated to contain both a neuropeptide Y-like peptide and the catecholamine synthesizing enzyme tyrosine hydroxylase.     

Is there an effect of monocular deprivation on the proportions of X and Y cells in the cat lateral geniculate nucleus?

Summary The proportions and receptive field properties of X and Y cells in the A and A1 layers of the lateral geniculate nucleus (LGN) were studied in monocularly deprived cats. Contrary to previous reports, we found that there was no change in the relative number of Y cells in the geniculate layers driven by the deprived eye. There was also no marked change in the spatial resolution of X or Y cells driven from the deprived eye as compared to the cells driven from the normally experienced eye. In these same cats, the visual evoked potential from stimulation of the deprived eye with grating patterns was markedly reduced in amplitude. Furthermore, the cell bodies of the cells in the LGN driven by the deprived eye had shrunk. Therefore, these usual consequences of monocular deprivation are not necessarily associated with a loss of geniculate Y cells.     

Complex evolution of X and Y autosomal translocations in the giant mole-rat, Cryptomys mechowi (Bathyergidae)

Cross-species chromosome painting was used to determine homologous chromosomal regions between two species of mole-rat, the naked mole-rat, Heterocephalus glaber (2n = 60), and the giant mole-rat, Cryptomys mechowi (2n = 40), using flow-sorted painting probes representative of all but two of the H. glaber chromosomal complement. In total 43 homologous regions were identified in the C. mechowi genome. Eight H. glaber chromosomes are retained in toto in C. mechowi, and 13 produce two or more signals in this species. The most striking difference in the karyotypes of the two taxa concerns their sex chromosomes. The H. glaber painting probes identified a complex series of translocations that involved the fractionation of four autosomes and the subsequent translocation of segments to the sex chromosomes and to autosomal partners in the C. mechowi genome. An intercalary heterochromatic block (IHB) was detected in sex chromosomes of C. mechowi at the boundary with the translocated autosomal segment. We discuss the likely sequence of evolutionary events that has led to the contemporary composition of the C. mechowi sex chromosomes, and consider these in the light of prevailing views on the genesis of sex chromosomes in mammals.