Mouse spermatocytes

The highly restricted tissue-specific transcription of c-mos poses an interesting problem in gene regulation during germ cell development. Moreover, c-mos is transcribed from different promoters in mouse spermatocytes and oocytes (Fig. 4) (Propst et al., 1987). In spermatocytes, transcription initiates approximately 280 nucleotides upstream of the c-mos ATG (Propst et al., 1987), whereas the transcription start site in oocytes has been mapped to 53 base pairs upstream of the ATG (Pal et al., 1991). Neither the spermatocyte nor oocyte promoter regions are... 

FA069 Walia, K. Effects of asafetida (7 hy-droxycoumarin) on mouse spermatocytes. Cytologia 1973 38 19-724. FA079... 

In vivo in mouse bone marrow, hydroquinone induced micronuclei and chromosomal aberrations in several studies but not sister chromatid exchanges in a single study. Hyper-ploidy and chromosome loss (as demonstrated by centromere-positive micronuclei) but not polyploidy were also found in mouse bone marrow. In mouse spermatocytes, chromosomal aberrations and hyperploidy were observed. 

Cytogenetic damage Mouse spermatocytes In vivo cytogenetic analysis Chromosomal rearrangements <3 mo M H S NA... 

Biosynthesis of sterols and of dolichol are independently controlled in developing rat brain [214], in maturing mouse spermatocytes [215] and in mouse spleen cells during phenylhydrazine-induced erythropoiesis [216]. 

Fig. 2 Electron micrograph of a microspread mouse spermatocyte, stained with phosphotungstic acid. The axis of the X and Y chromosomes show a short synaptic region in the lower part of the figure. A nucleolar body (asterisk) is close to the XY pair. The autosomal bivalent (up) shows a recombination nodule (arrowhead). xSOOO.

Solari, A. J. (1970). The spatial relationship of the X and Y chromosomes during meiotic prophase in mouse spermatocytes. Chromosoma 29, 217-236. 

Evidence indicating that, in interphase nuclei, the chromosomes are attached to the nuclear membrane comes from ultrastructural studies and from analysis of the segregation of newly synthesized DNA. Woollam et al. (1967) describe attachment of both distal and centro-meric ends of pachytene chromosomes to the nuclear membrane of mouse spermatocytes moreover, these authors suggest, on the basis of the nearness of centromeric attachments to the sex vesicle in these cells, that centromeric and distal attachment points are at opposite poles of the nucleus (cf. also, Sved, 1966). Davies and Tooze (1966) have examined mitotic chromosomes of newt erythroblasts, a cell type characterized by scarcity of endoplasmic reticulum. In interphase erythroblasts, numerous areas are found where chromatin appears to be closely associated with the nuclear membrane. At mitosis the chromosomes are observed to carry fragments of nuclear membrane, sometimes appearing as membrane-limited sheets of chromatin, continuous with the chromosomes. 

Figure 4. Transcriptional regulatory sequences of the mouse c-mos gene. Transcription in oocytes and spermatocytes initiates 53 and approximately 280 base pairs upstream of the c-mos ATG, respectively. Efficient transcription in oocytes requires an initiator (Inr)-I ike sequence located downstream of the transcription start site. A negative regulatory element (NRE) located upstream of the spermatocyte promoter acts to suppress c-mos transcription in somatic cells.

In rodents treated in vivo, acrylonitrile did not induce unscheduled DNA synthesis in hepatocytes or spermatocytes of rats, chromosomal aberrations in the bone marrow of mice or rats, chromosomal aberrations in spermatogonia of mice, micronuclei in the bone marrow of mice, or dominant lethal effects in either rats or mice. Sister chromatid exchanges were, however, induced in mouse bone marrow. 

Caprolactam treatment in vivo did not increase DNA single-strand breaks in hepatocytes or unscheduled DNA synthesis in spermatocytes of rats, did not induce sister chromatid exchanges, micronuclei or chromosomal aberrations in mouse bone marrow and did not induce morphological abnormalities in mouse sperm. Inconclusive results were reported in two mouse spot test studies for gene mutations. 

Leonard. A. Linden. G. (1972) Observation of dividing spermatocytes for chromosome aberrations induced in mouse spermatogonia by chemical mutagens. Mutat. Res., 16, 297-300 Lide. D.R.. ed. (1997) CRC Handbook of Chemistry and Physics, 78th Ed., Boca Raton, FL, CRC... 

Packer Al, Besmer P Bachvarova RF. 1995. Kit ligand mediates survival of type A spermatogonia and dividing spermatocytes in postnatal mouse testes. Mol. Re prod. Dev. 42 303-10... 

Santi, C.M., Darszon, A., and Hemandez-Cruz, A. (1996). A dihydropyridine-sensitive T-type Ca current is the main Ca current carrier in mouse primary spermatocytes. Amer. J. Physiol. 277 C1583-C1593. 

Meistrich, M. L., P. K. Trostle, M. Frapart, and R. P. Erickson. 1977. Biosynthesis and localization of lactate dehydrogenase X in pachytene spermatocytes and spermatids of mouse testes. Developmental Biology 60 428 41. 

Figure 4 Triantennary iV-glycans involved in germ cell and Sertoli cell interaction in the mouse testis. Spermatogenesis takes place in the tubal structure called seminiferous tube in the testis. Inside of seminiferous tube is lined by Sertoli cells, the tail epithelial cells. When germ stem cells at the base of Sertoli cells differentiate to spermatocytes, the cells move upward interacting with Sertoli cells. The MX gene knockout mouse revealed that fucosylated GlcNAc-terminated triantennary A-glycan (insert) plays an important role in germ cell adhesion to Sertoli cells (59).

Mutagenic effects of monofunctional alkylating chemicals in vivo have already yielded substantial results. Toxicity trials indicate that the Armenian hamster is two and a half times more sensitive than the mouse to ethyl methanesulfonate (Lavappa and Yerganian, 1969). With regard to induction of chromosomal anomalies, intraperitoneal administration of low doses (100 mg/kg) of ethyl methanesulfonate is sufficient to produce an overall incidence of 30% viable translocations in the male progeny. Furthermore, translocated chromosomes and bivalents can be accurately identified in terms of specific sites of breakage and reunion in both spermatogonia and spermatocytes (Table 2). Since the translocated F males are found in litters... 

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