Biochemical analysis of meiosis in the male mouse

Spermatogenic cells of the mouse have been separated by gravity sedimentation using a modification of a previously published method. Details are given for the collection of purified samples of specific meiotic stages and for the collection of labelled cell fractions following injection of ³H-thymidine. Suppression of semi-conservative meiotic DNA synthesis, essential to the biochemical analysis of pachytene DNA metabolism, has been achieved by in vivo administration of 1 M hydroxyurea.     

A sequential screening of the cytogenetic damage induced by triaziquone.

A sequence is described of test procedures for a screening in vivo of the clastogenic potential of the alkylating agent triaziquone (Trenimon). Two intraperitoneal injections of 0.125 mg/kg body weight caused a considerable increase in the number of aberrations in both the micronucleus test and the bone-marrow metaphase test, but not in the spermatocyte translocation test or the spermatogonial metaphase test. With the latter test a severe cell-killing effect was detected. An analysis of whole mounts of seminiferous tubules showed that 0.125 mg/kg was a lethal dose for all B- and intermediate-type spermatogonia and partly killed A-type spermatogonia. A single administration of the same dose caused stable chromosomal rearrangements in spermatids that could be demonstrated with the F1 translocation test, and gave rise to dominant lethality of fetuses originating from post-meiotic sperm. The comparative triaziquone study has provided arguments in favor of the micronucleus test as a reliable screening method for chromosomal aberrations. The analysis of seminiferous tubules is a recommendable method for studying lethal effects of a compound on germ cells, whereas the F1 translocation test gives important information about viable aberrations and their effect on the fertility of the progeny.     

A sequential analysis of the development of the synaptonemal complex in spermatocytes of the mouse by electron microscopy using hydroxyurea and agar filtration

A method is presented for sequential analysis of the development and behaviour of the Synaptonemal Complex (SC) in primary spermatocytes of male mice, using agar filtration for electron microscope grid preparation. The mice were treated with hydroxyurea (HU) to produce a gap in the spermatogenic line. The front of surviving cells behind the gap was examined day by day. The first visible parts of unpaired axial elements, with some barely recognizable paired regions were found 9 days after the last HU injection i.e. directly after the last S-phase before meiosis. During mid zygotene and late zygotene the axes of the autosomes had a fuzzy ill-defined appearance with irregular regions of apparent thickening. The axes of the XY pair could be recognized only at late zygotene. During pachytene the SCs of the autosomal pairs did not show a significant change except for a slight increase in size of the attachment points of the axial elements. On the first day of pachytene the axes of the XY pair appeared thin and long. On the second day the axes of the XY pair showed maximal pairing of about 50% of the axis of the Y chromosome. From the third to the fifth day a decrease of the paired region of the sex chromosomes was found together with an increase in thickness of the axes, which reached its maximum on the fourth day. Diplotene could be easily recognized: the autosomal axes showed a sharp, well-defined outline with thick attachment points with deltoid structure, and desynapsis was very clear. The axes of the XY pair showed variation during diplotene but on the third day of diplotene a characteristic bulging could be seen. The axes of the autosomes disappeared at this time and in most cases only the attachment points remained visible. The duration of the prophase classes of meiosis I was found to be: zygotene approximately 2 days; pachytene a little more than 5 days and diplotene approximately 3 days. Leptotene could not be traced by the method used. If it exists at all, it must be a stage of very short duration.     

Precocious initiation of meiosis by male germ cells of the mouse

12 1/2-15 1/2 day embryonic mouse testes of 129/terSv and CBA/T6T6 strains were transplanted under the kidney capsule of adult hosts. After 3-5 days in 41% of CBA/T6T6 transplants and in 82% of 129/terSv transplants a limit number of germ cells began meiosis. The percentage of meiotic germ cells was inversely related to the total number of gonocytes and the organization of seminiferous cords. The presented evidence indicates that the ability of the germ cells to begin meiosis precociously depends on: 1) genotype of donor embryos; 2) age of transplanted testis, and 3) using whole of half of gonad for transplantation. After 10-15 days in two out of 46 129/terSv testes (4%) growing oocytes were observed.     

Proteomic analysis of male 4C germ cell proteins involved in mouse meiosis

Male meiosis is a specialized type of cell division that gives rise to sperm. Errors in this process can result in the generation of aneuploid gametes, which are associated with birth defects and infertility in humans. Until now, there has been a lack of a large-scale identification of proteins involved in male meiosis in mammals. In this study, we report the high-confidence identification of 3625 proteins in mouse male germ cells with 4C DNA content undergoing meiosis I. Of these, 397 were found to be testis specific. Bioinformatics analysis of the proteome led to the identification of 28 proteins known to be essential for male meiosis in mice. We also found 172 proteins that had yeast orthologs known to be essential for meiosis. Chromosome distribution analysis of the proteome showed underrepresentation of the identified proteins on the X chromosome, which may be due to meiotic sex chromosome inactivation. Characterization of the proteome of 4C germ cells from mouse testis provides an inventory of proteins, which is useful for understanding meiosis and the mechanisms of male infertility.     

The unbalanced offspring of the male carriers of the 11q;22q translocation: nondisjunction at meiosis II in a balanced spermatocyte

Summary Carriers of the standard translocation t(11;22) (q23.3;q11.2) produce only one type of unbalanced offspring, a tertiary trisomy resulting into the karyotype 47,XX or XY, +der(22)t(11;22)(q23.3;q11.2), usually derived from the mother. The exception is one single patient 47,XY,t(11;22)(q23.3;q11.2),+der(22)t(11;22) (q23.3;q11.2)pat. We report a second case with the same karyotype, also of paternal origin. Thus, the rare unbalanced offspring of a carrier father (only 5 cases known) may receive a supernumerary der(22), as a consequence of tertiary trisomy, but also as a consequence of nondisjunction at meiosis II of a balanced spermatocyte.     

Distamycin A/DAPI staining of heterochromatin in male meiosis of man

The sequential staining with distamycin A/DAPI provides an ideal method for studying the behaviour of heterochromatic regions in human male meiosis. The various meiotic and postmeiotic stages were found to have different staining qualities. Although all heterochromatic regions in human pachytene cells show specific DA/DAPI fluorescence, bright and clearly stained heterochromatic blocks can be distinguished from small DA/DAPI spots. Pachytene nuclei exhibit associations between heterochromatic regions of non-homologous bivalents. The heterochromatin of bivalent 9 generally presents as a cluster of small, discrete bodies. The heterochromatic regions of chromosomes 1, 9, 15, 16 and Y are preferentially stained at diakinesis and metaphase of the second meiotic division. The specific DA/DAPI staining disappears with the progressive volume reduction of middle and late spermatid nuclei. The heterochromatin of the chromatids fuses to form a large chromocenter during spermatid differentiation.     

Constitutive antigen presentation by mouse splenic macrophages is restricted to the progeny of a distinct progenitor population

Mouse splenic macrophage progenitors differ in their ability to give rise to cloned progeny that constitutively present complex protein antigens to T-cell hybridomas. To determine if the constitutive presentation of diverse antigens is restricted to cells derived from the same subpopulation of progenitors, we expanded macrophage clones into multiple subcultures and compared them for the ability to present different antigens to their respective antigen-specific T-cell hybridomas. Only subcultures derived from the same minority fraction of splenic macrophage progenitors were capable of constitutively presenting the antigens, and the activity of these subcultures was unaffected by the addition of recombinant murine IFN-gamma. This suggests that a specialized sub-population of constitutive antigen-presenting macrophages exists in the spleens of mice.     

Centromere localization at meiosis and the position of chiasmata in the male and female mouse

Techniques for obtaining differential Giemsa staining of the paracentromeric (p.c.) regions of male and female mouse meiotic chromosomes (centromeric heterochromatin) were explored and standard procedures developed for the different meiotic cells in the two sexes. The best result followed the use of heat at controlled pH in Sörensen's phosphate buffer or in Standard Saline Citrate (SSC) solutions. With these techniques, morphological features of the p.c. regions and their variation were studied in normal animals (CFLP strain) and in a strain (AKR) homozygous for a centric fusion [T(11; ?)-1 Ald] between chromosomes No. 6 and No. 15 (Miller et al., 1971). The Y chromosome was often found to show distinct p. c. staining at first and apparently at second meiotic metaphase, and the X and Y chromosomes were found to associate as bivalents by their long arms. Autosomal p.c. regions showed variation in size which might indicate differences between non-homologous chromosomes but a tendency to similarity between homologues. Differences were found between males and females in respect to proportions and variation of bivalents with single and double chiasmata. The relative positions of chiasmata were different in the two sexes. The presence of the centric fusion in the males did not seem to affect the pairing behaviour of the remaining autosomes or of those taking part in the centric fusion. The possibility is discussed that the p.c. regions, to which also other functions would seem to appertain, may be important for chromosome recognition and pairing, possibly on a quantitative basis.     

空间环境诱发玉米细胞质雄性不育突变体的遗传分析

从返回式卫星"实践八号"搭载的08-641和18-599两份玉米自交系后代选育出3份雄性不育突变体,在不同地点、不同年份、不同季节进行种植观察,鉴定其育性表现,通过测交、反交及回交对不育性状的遗传特性进行分析。结果表明:3份不育突变材料均能稳定遗传,属可遗传的细胞质雄性不育类型。恢保关系测定和特异引物PCR扩增结果显示,3份不育材料均属玉米C型细胞质雄性不育类型,但3份不育材料在恢保关系上存在一定差异,推测它们可能分别属于玉米C型细胞质雄性不育的不同亚组。这些不育材料的发现,丰富了雄性不育胞质的遗传基础,在玉米不育化制种中具有一定应用价值。     

Biological treatment of acid dyeing wastewater using a sequential anaerobic/aerobic reactor system

The treatment of the wastewater taken from a wool dyeing processing in a wool manufacturing plant was investigated using an anaerobic/aerobic sequential system. The process units consisted of an anaerobic UASB reactor and an aerobic CSTR reactor. Glucose, alkalinity and azo dyes were added to the raw acid dyeing wastewater in order to simulate the dye industry wastewater since the raw wastewater contained low levels of carbon, NaHCO₃ and color through anaerobic/aerobic sequential treatment. The UASB reactor gave COD and color removals of 51–84% and 81–96%, respectively, at a HRT of 17 h. The COD and color removal efficiencies of the UASB/CSTR sequential reactor system were 97–83% and 87–80%, respectively, at a hydraulic retention time (HRTs) of 3.3 days. The aromatic amines (TAA) formed in the anaerobic stage were effectively removed in the aerobic stage.