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Techniques of quantitative stereology have been utilized to determine the relative volume occupied by the Sertoli cells and germ cells in two particular stages (I and VII) of the cycle of the seminiferous epithelium. Sertoli cell volume ranged from 24% in stage I of the cycle to 32% in stage VII. Early germ cells occupied 3.4% in stage I (spermatogonia) and 8.7% in stage VII (spermatogonia and preleptotene spermatocytes). Pachytene spermatocytes occupied 15% (Stage I) and 24% (stage VII) of the total volume of the seminiferous epithelium. In stage I the two generations of spermatids comprised 58% of the total epithelium by volume, whereas in stage VII, after spermiation, the acrosome phase spermatids occupied 35% of the total seminiferous epithelial volume. Show less

A procedure is described which permits the isolation from the prepuberal mouse testis of highly purified populations of primitive type A spermatogonia, type A spermatogonia, type B spermatogonia, preleptotene primary spermatocytes, leptotene and zygotene primary spermatocytes, pachytene primary spermatocytes and Sertoli cells. The successful isolation of these prepuberal cell types was accomplished by: (a) defining distinctive morphological characteristics of the cells, (b) determining the temporal appearance of spermatogenic cells during prepuberal development, (c) isolating purified seminiferous cords, after dissociation of the testis with collagenase, (d) separating the trypsin-dispersed seminiferous cells by sedimentation velocity at unit gravity, and (e) assessing the identity and purity of the isolated cell types by microscopy. The seminiferous epithelium from day 6 animals contains only primitive type A spermatogonia and Sertoli cells. Type A and type B spermatogonia are present by day 8. At day 10, meiotic prophase is initiated, with the germ cells reaching the early and late pachytene stages by 14 and 18, respectively. Secondary spermatocytes and haploid spermatids appear throughout this developmental period. The purity and optimum day for the recovery of specific cell types are as follows: day 6, Sertoli cells (purity>99 percent) and primitive type A spermatogonia (90 percent); day 8, type A spermatogonia (91 percent) and type B spermatogonia (76 percent); day 18, preleptotene spermatocytes (93 percent), leptotene/zygotene spermatocytes (52 percent), and pachytene spermatocytes (89 percent), leptotene/zygotene spermatocytes (52 percent), and pachytene spermatocytes (89 percent). Show less

The fine structure of the rete testis was examined in several primates, domestic animals and rodents. The rete testis consists of a series of interconnected wide channels lined with a simple cuboidal to columnar epithelium, resting on a thick basal lamina. Beneath the basal lamina dense bundles of collagen fibrils and a few blood vessels, lymphatics or nerve tissue are found. The epithelial cells are characterized by large, deeply indented nuclei, spherical or short rod-shaped mitochondria, supranuclear Golgi profiles, some cisterns of rough endoplasmic reticulum, free ribosomes and numerous micropinocytotic vesicles in the ectoplasmic regions. Smooth endoplasmic reticulum, secretory granules, lysosomes or other types of dense bodies are rarely seen. The apical surface of the cells bears numerous microvilli and a single very long flagellum which is presumed to be motile. Ajoining lateral cell membranes exhibit a juxtaluminal tight junction, elaborate interdigitations and desmosomes. The basal plasma membrane is highly irregular greatly increasing its surface area of contact with the underlying interstitium. The nuclei of the rete epithelial cells contain pale-staining, spherical structure, 2 mum in diameter, composed of circularly oriented fine filaments. The significance of the nuclear structures remains unknown. Thorotrast was injected into the lumen of the hamster and rat rete testis and 30 minutes later the proximal portion of the excurrent duct system of the testis was prepared for electron microscopy. Whereas the ductuli efferentes and first part of the epididymis possessed numerous apical vesicles filled with the thorotrast, this electron opaque substance was rarely found in the epithelium of the rete testis. Thus, incorporation of particulate matter into the lining cells of the rete from its lumen is apparently less active than in the epithelium of the ductuli and epididymis. Vascularly introduced intercellular tracer compounds such as lanthanum nitrate or horseradish peroxidase did not enter the lumen of the rete testis from the interstitium. The tracer molecules appeared to be blocked by the juxtaluminal tight junction separating adjacent epithelial cells. This latter observation suggests that a blood-testis barrier exists at the level of the rete testis epithelium. Although physiological studies have indicated that the composition of fluid secreted in the seminiferous epithelium is considerably modified in the rete testis, the present morphological study does not provide additional evidence to support a secretory or absorptive function for this region of the excurrent duct system of the testis. Show less

The effect of caffeine on postreplication repair, as seen in alkaline sucrose gradients, conjugation, and ultraviolet light (UV) survival, was studied in excision deficient strains of Escherichia coli K12 and B. A caffeine concentration of 2 mg/ml was chosen for the study which did not inhibit colony formation. Both E. coli K12 AB2500 and E. coli B WWP2 were more sensitive to UV when plated on caffeine plates. Conjugation was not inhibited in the E. coli K12 strain; however, the same procedure confirmed caffeine inhibition in the E. coli B strain [17]. Caffeine did not inhibit postreplication repair in either strain, as determined by sedimentation profile studies of DNA on alkaline sucrose gradients. No strand breakage or degradation was observed in parental or post-UV replicated DNA for as long as 50 min incubation in caffeine. Thus caffeine concentrations that inhibited two recA gene product related phenomena did not cause immediate changes in size of DNA or inhibit the rate of a DNA gap generating postreplication type of DNA repair. Show less

Although lymphocytes are never present in 'normal ' seminiferous epithelium, they are found in the terminal portions of the seminiferous tubles near their junctions with the tubuli recti. Intraepithelia lymphocytes are also found in the tubuli recti testis, ductuli efferentes, epididymis and ductus deferens. The ultrastructural morphology of these cells closely resembles that of the intraepithelial lymphocytes in the intestinal mucosa and those obtained from the lymph nodes, spleen blood and thoracic duct. The mucleus is spherical and is characterized by clumps of chromatin near the nuclear membrane. A thin rim of cytoplasm is usually found, and is remarkably free of most cell organelles except for free ribosomes. Frequently, a blunt cytoplasmic process can be seen extending from one end of the cell. Membrane-bounded granules and other dense bodies are occasionally encountered in the cytoplasm. The possible functional significance of intraepithelial lymphocytes in the male reproductive tract is discussed. Show less

Epidemiological studies and clinical observation suggesting potential hazards of arsenic compounds in increasing the incidence of cancer have been in complete contradiction with experimental findings in animals. Because of the predominance of skin cancers in the epidemiological reports, we decided to investigate the possibility that arsenic compounds might interfere with DNA repair. Using Escherichia coli as a test system, we show that this is indeed the case. Sodium arsenite, at concentrations of 0.1 mM and higher, decreases the survival of ultraviolet-irradiated E. coli WP2, a strain which possesses the full complement of repair genes. The effect of the arsenite increases with increasing ultraviolet dose. Similar results were obtained with the excision repair deficient strains WWP2 (uvrA) and WP6 (polA). Sodium arsenite had no effect on the survival of a recA mutant, WP10. Survival of ultraviolet-irradiated WP5 (exrA) was enhanced by sodium ardenite, the effect being greatest at low ultraviolet doses. It is postulated that arsenite inhibits a recA-dependent step in DNA repair. To account for the increased survival of the exrA mutant, we suggest that in the absence of the exr+ gene, the arsenite-sensitive recA-dependent function is deleterious. The ability of arsenite to inhibit DNA repair may account for the clinical and epidemiological reports linking arsenicals with an increased incidence of cancer. Show less

When the excision proficient strain E. coli WP2 Hcr+ trp- was grown to stationary phase by glucose starvation in M-9 minimal medium before UV -irradiation, the ability of nutrient broth enrichment of minimal medium to enhance trp- leads to Trp+ reversion was greatly reduced. Less than 50% of the Trp+ revertants were found to be ochre suppressors. However, in the WWP2 Hcr- strain, 75-86% of the tested revertants were ochre suppressors. This indicates that, under the cultural conditions employed, many potential suppressor mutations were removed by excision repair in the presence of broth enrichment. Broth enhancement of reversion also occurred in the Hcr- strain, which indicates that a less error-prone mode of recombination repair functions under minimal growth conditions. An Hcr+ strr derivative of WP2 Hcr+ was more resistant than its strs parent to the lethal effect of UV light and showed a lower UV-induced Trp+ reversion frequency. The percentage of Trp+ revertants that were due to ochre suppressors was markedly reduced in the strr strain. The Hcr- strr strain also had a lower UV-induced Trp+ reversion frequency than its strs parent. The excision repair inhibitor caffeine had little effect at lower UV doses on increasing Trp+ reversion in both Hcr+ strains. Acriflavine, however, was effective at lower UV doses in enhancing reversiin of the Hcr+ strains and the degree of enhancement increased with the dose. Acriflavine appeared to specifically enhance the number of ochre suppressing Trp+ revertants. In both Hcr- strains (strs and strr) caffeine (500 mug/ml) had no effect on survival but reduced the UV-induced Trp+ reversion frequency acting as an antimutagen. In contrast, acriflavine (2 mug/ml) decreased survival and increased the Trp+ reversion frequency of the Hcr- strains. The data on spontaneous Trp+ reversion frequencies show that the Hcr+ strs strain had a higher spontaneous reversion frequency than the Hcr- strs strain on all plating media. Further, caffeine was shown to reduce spontaneous Trp+ reversion in both Hcr+ and Hcr- strains while acriflavine increased the spontaneous reversion frequencies of both strains. Show less

Regulation of exocellular enzyme acid phosphatase 2 synthesis is studied. 21 mutants with consitutive synthesis of this enzyme are obtained by UV-irradiation. All mutants were recessive and were distributed among 3 complementation groups ACP80, ACP81, ACP82. Two groups, ACP80 and ACP81 corresponded to two different genes, which showed no linkage with ACP1, ACP2 and PHO1 genes. The type of synthesis of acid phosphatase 2 in strains acp1 acp80, acp1 acp81, acp2 acp80, acp2 acp81 is determined, and a conclusion is made about the participation of ACP2 gene in the regulation of acid phosphatase 2 synthesis. It is shown that some mutations in PHO1 gene, which block the activity of acid phosphatase 1, influence the activity and regulation of acid phosphatase 2. Show less

Genetic control of exocellular acid phosphatase of yeast Saccharomyces cerevisiae (acph 2) is studied. 64 mutants with the impaired activity of acid phosphatase have been obtained by UV-irradiation. All the mutations have been distributed among 4 genes: ACP1, ACP2, ACP3, ACP4 using functional and recombinational tests for allelism. It is shown that mutations in genes ACP1--ACP3 are recessive, but in the gene ACP4--dominant. The gene ACP4 is found to be located 0.41+/-0.064 in strains from centromere and to have no linkage with ACP1. Possible functions of genes studied are under discussion. Show less

A study was made of the effect of different light regimen on the changes in the reactive properties, and also of the efficacy of hormone therapy of the transplantable rat mammary carcinoma (RMC-1). In darkness the percentage of the take of the carcinoma proved to be less, and also the growth of the RMC-1 was delayed; there was also a marked increase in the efficacy of estrogen-therapy of mammary carcinoma. It is supposed that more effective treatment of the RMC-1 in darkness was associated with the change in functional activity of the hypothalamo-hypophyseal system. Show less

The human enzyme, lysosomal acid phosphatase ACP2, is expressed in nan-rodent somatic cell hybrids as a dimeric molecule. The human-rodent heteropolymer, as well as the human and rodent homopolymer, is associated with lysosomes in these cells. The genes specifying lysosomal acid phosphatase ACP(2) and LDH A are syntenic. Show less

A selection experiment was conducted for approximately 1,000 generations in a chemostat population of 10(9) cells of the haploid yeast, S. cerevisiae. The experiment was designed to enhance genetically the rate at which the external enzyme acid phosphatase catalyzed the hydrolysis of very low concentrations of beta-glycerophosphate at an unfavorably high pH. The observed genetic adaptation in this experiment consisted of a mutation (ACP-2) in the acid phosphatase structural gene which effected a shift in the pH optimum of the enzyme and incremented its activity. The effects of ACP-2 and a similar mutation, ACP-1, on acid phosphatase substrate specificity are also reported. Show less