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221.
Wolf C 《Bioelectromagnetics》2008,29(8):658-659
Whether exposure to electromagnetic fields well below accepted exposure limits has a cytogenetic effect on human cells has long been debated. It is widely published and generally accepted that the exposure unit invariably used in these experiments is capable of providing blinded exposure conditions. The following short report illustrates, however, that exposure conditions might not always be as effectively masked as is generally assumed. 相似文献
222.
The karyotypic and chromosomal characteristics of the hatchetfish Thoracocharax stellatus from the Araguaia River, Brazil (Araguaia-Tocantins basin) were analyzed using Giemsa, AgNO(3), and CMA(3) fluorescent staining, and C-banding. The diploid chromosome number was 54 and the karyotypes of females and males were composed of six metacentrics, six submetacentrics, six subtelocentrics and 36 acrocentrics. Two unpaired acrocentric chromosomes were detected in the female karyotype. C-banding showed heterochromatic blocks at several chromosomes and an entirely heterochromatic acrocentric chromosome in females that was lacking in the male karyotype. This discovery indicated a heteromorphic sex chromosome system of the ZZ/ZW type. Ag-staining and CMA(3) fluorescence revealed one major chromosome pair bearing the NORs with the presence of additional signals in some metaphases. Both heterochromatic segments associated with Ag-NORs and the W chromosome were positively stained by CMA(3). Considering the present data and previous findings it is hypothesized that the occurrence of ZW sex chromosome system is widespread in the genus Thoracocharax. 相似文献
223.
224.
Tuomo Mantere Kornelia Neveling Cline Pebrel-Richard Marion Benoist Guillaume van der Zande Ellen Kater-Baats Imane Baatout Ronald van Beek Tony Yammine Michiel Oorsprong Faten Hsoumi Daniel Olde-Weghuis Wed Majdali Susan Vermeulen Marc Pauper Aziza Lebbar Marian Stevens-Kroef Damien Sanlaville Jean Michel Dupont Dominique Smeets Alexander Hoischen Caroline Schluth-Bolard Laïla El Khattabi 《American journal of human genetics》2021,108(8):1409-1422
225.
家蚕细胞遗传学及其应用 总被引:1,自引:0,他引:1
由于家蚕染色体数目较多、着丝粒弥散, 在较长时期内, 家蚕染色体识别、核型分析、染色体结构和功能的研究都受到很大限制。近年来, 应用比较基因组杂交、基因组原位杂交、基于细菌人工染色体克隆的原位杂交技术建立了家蚕的细胞学图, 综合分子连锁图构建高密度的细胞遗传学图已成为可能。分子细胞遗传学的应用正在推动家蚕染色体结构和功能的研究, 揭示出家蚕W染色体密集地分布着嵌套结构的逆转座子, 染色体端粒由重复序列(TTAGG)n以及端粒特异的非长末端逆转座子TRAS1和SART1组成, TRAS1、SART1具有较高的转录活性, 可能与维持染色体的稳定性有关。 相似文献
226.
Alain Ducos Pascal Dumont Anne Séguéla Alain Pinton Hélène Berland Corinne Brun-Baronnat Aafke Darré Brigitte Marquant-Le Guienne Patrice Humblot Didier Boichard Roland Darré 《遗传、选种与进化》2000,32(6):589-598
Three bulls of the Montbéliarde breed that exhibited fertility rates lower than 30% following more than 400 artificial inseminations were examined. Semen quality (sperm motility and morphology) from these bulls was normal. Fertilizing ability estimated from in vitro embryo production results was studied for two of them. In vitro production rate was very low for one bull (A) and normal for the other (B). Cytogenetic analyses were carried out on the three bulls using chromosome banding techniques. These analyses revealed a reciprocal translocation (12;17)(q22;q14) in bull B. Based on family analyses, the hypothesis of a de novo origin of this rearrangement is proposed. 相似文献
227.
The vast genetic diversity, specific genome organization and sequencing of the Arabidopsis thaliana genome made crucifers an ideal group for comparative genomic studies. Arabidopsis genomic resources have greatly expedited comparative genomics within Brassicaceae and fostered the establishment of new Arabidopsis relative model systems (ARMS). The extent of genome colinearity, modes and evolutionary rates of genome alterations are being
analyzed by genetic mapping with ever increasing levels of precision. Comparative cytogenetic studies in Brassicaceae are
employing various chromosome landmarks and cytogenetic techniques, including localization of rDNA, variation in centromeric
satellite repeats, genomic in situ hybridization (GISH), fluorescence ISH using bacterial artificial chromosomes (BAC FISH), and large-scale comparative chromosome
painting. Some genome alterations may represent rare genomic changes (RGCs) and thus have the potential to resolve complex/conflicting
phylogenetic relationships inferred from DNA sequencing. Comparative genomics should increasingly be integrated with molecular
phylogenetics and population genetics to elucidate the processes responsible for genetic variation in Brassicaceae. 相似文献
228.
The karyotype of Vaillantella maassi, a loach with an unusually long dorsal fin, was investigated using sequential CMA3 and AgNO3 staining to test if this character evolved in parallel with Vaillantella’s morphological distinctness. The karyotype was 2n = 50 with 13 pairs of metacentric-submetacentric and 12 pairs of subtelocentric chromosomes. Sequential CMA3 banding and AgNO3 staining evidenced NORs in the short arms of pair no. 2. Additional CMA3-positive, Ag-negative signals were present in the short arms of pairs 14 and 15. The karyotype paralleled those of most other
cobitoid loaches studied so far and is apparently not associated with the morphological distinctness of Vaillantella. 相似文献
229.
Adachi-Hagimori T Miura K Stouthamer R 《Proceedings. Biological sciences / The Royal Society》2008,275(1652):2667-2673
Vertically transmitted endosymbiotic bacteria, such as Wolbachia, Cardinium and Rickettsia, modify host reproduction in several ways to facilitate their own spread. One such modification results in parthenogenesis induction, where males, which are unable to transmit the bacteria, are not produced. In Hymenoptera, the mechanism of diploidization due to Wolbachia infection, known as gamete duplication, is a post-meiotic modification. During gamete duplication, the meiotic mechanism is normal, but in the first mitosis the anaphase is aborted. The two haploid sets of chromosomes do not separate and thus result in a single nucleus containing two identical sets of haploid chromosomes. Here, we outline an alternative cytogenetic mechanism for bacterial endosymbiont-induced parthenogenesis in Hymenoptera. During female gamete formation in Rickettsia-infected Neochrysocharis formosa (Westwood) parasitoids, meiotic cells undergo only a single equational division followed by the expulsion of a single polar body. This absence of meiotic recombination and reduction corresponds well with a non-segregation pattern in the offspring of heterozygous females. We conclude that diploidy in N. formosa is maintained through a functionally apomictic cloning mechanism that differs entirely from the mechanism induced by Wolbachia. 相似文献
230.
Yan WH Lin A Chen BG Luo WD Dai MZ Chen XJ Xu HH Li BL 《Journal of cellular and molecular medicine》2008,12(3):889-898
Human leukocyte antigen-G (HLA-G) molecule exerts multiple immunoregulatory functions that have been suggested to contribute to the immune evasion of tumour cells. Studies on HLA-G expression in malignant haematopoietic diseases are controversial, and the functions of HLA-G on this context are limited. In the current study, HLA-G expression was analysed in different types of patients: de novo acute myeloid leukaemia (AML, n = 54), B cell acute lymphoblastic leukaemia (B-ALL, n= 13), chronic myeloid leukaemia (CML, n= 9) and myelodysplastic syndrome (MDS, n= 11). HLA-G expression was observed in 18.5% cases of AML, 22.2% in CML and 18.2% in MDS, but not in B-ALL patients. In AML, HLA-G-positive patients had a significant higher bone marrow leukaemic blast cell percentage when compared with that of HLA-G-negative patients (P < 0.01). Total T-cell percentage was dramatically decreased in HLA-G-positive patients (P < 0.05). Cytogenetic karyotyping results showed that all HLA-G-positive AML patients (n= 5) were cytogenetically abnormal, which was markedly different from that of HLA-G-negative patients (P < 0.01). Ex vivo cytotoxicity analysis revealed that HLA-G expression in AML leukaemic cells could directly inhibit NK cell cytolysis (P < 0.01). These findings indicated that HLA-G expression in AML is of unfavourable clinical implications, and that HLA-G could be a potential target for therapy. 相似文献