Seminal inhibin--prospects for immunocontraception.

Passive immunization of adult rats, hamsters and marmosets with rabbit anti-seminal inhibin resulted in complete or partial block of fertility. The antiserum treatment presumably neutralized endogenous inhibin resulting in an unopposed rise in circulating FSH. This probably led to a refractoriness of the testes to FSH resulting in complete spermatogenic arrest. Nevertheless, there was no change in the mating behaviour of the animals. The antibodies also affected the epididymal spermatozoa by causing large scale agglutination.     

PCR Amplification of the Gene acmA Differentiates Lactococcus lactis subsp. lactis and L. lactis subsp. cremoris

The occurrence of the acmA gene, encoding the lactococcal N-acetylmuramidase in new lactococcal isolates from raw milk cheeses, has been determined. Isolates were genotypically identified to the subspecies level with a PCR technique. On the basis of PCR amplification of the acmA gene, the presence or absence of an additional amplicon of approximately 700 bp correlated with Lactococcus lactis subspecies. L. lactis subsp. lactis exhibits both the expected 1,131-bp product and the additional amplicon, whereas L. lactis subsp. cremoris exhibits a single 1,131-bp fragment.     

Influence of the Temperature and the Genotype of the HSP90AA1 Gene over Sperm Chromatin Stability in Manchega Rams

The present study addresses the effect of heat stress on males'' reproduction ability. For that, we have evaluated the sperm DNA fragmentation (DFI) by SCSA of ejaculates incubated at 37°C during 0, 24 and 48 hours after its collection, as a way to mimic the temperature circumstances to which spermatozoa will be subject to in the ewe uterus. The effects of temperature and temperature-humidity index (THI) from day 60 prior collection to the date of semen collection on DFI were examined. To better understand the causes determining the sensitivity of spermatozoa to heat, this study was conducted in 60 males with alternative genotypes for the SNP G/C₋₆₆₀ of the HSP90AA1 promoter, which encode for the Hsp90α protein. The Hsp90α protein predominates in the brain and testis, and its role in spermatogenesis has been described in several species. Ridge regression analyses showed that days 29 to 35 and 7 to 14 before sperm collection (bsc) were the most critical regarding the effect of heat stress over DFI values. Mixed model analyses revealed that DFI increases over a threshold of 30°C for maximum temperature and 22 for THI at days 29 to 35 and 7 to 14 bsc only in animals carrying the GG₋₆₆₀ genotype. The period 29–35 bsc coincide with the meiosis I process for which the effect of the Hsp90α has been described in mice. The period 7–14 bsc may correspond with later stages of the meiosis II and early stages of epididymal maturation in which the replacement of histones by protamines occurs. Because of GG₋₆₆₀ genotype has been associated to lower levels of HSP90AA1 expression, suboptimal amounts of HSP90AA1 mRNA in GG₋₆₆₀ animals under heat stress conditions make spermatozoa DNA more susceptible to be fragmented. Thus, selecting against the GG₋₆₆₀ genotype could decrease the DNA fragmentation and spermatozoa thermal susceptibility in the heat season, and its putative subsequent fertility gains.     

2′–5′ oligoadenylate synthetase and its relationship to HLA and genetic markers of insulin-dependent diabetes mellitus

Cytokines and their related enzyme pathways may play a part in the development of insulin-dependent diabetes mellitus (IDDM). We have therefore studied the activity of the enzyme 2′–5′ oligoadenylate synthetase (which is induced by both interferon and the tumour necrosis factors) in circulating mononuclear cells from 40 subjects with IDDM and 32 healthy control subjects. There was no difference in mean basal enzyme activity between the two groups. A polymorphism of the 2′–5′ oligoadenylate synthetase gene, not previously described, was found using the restriction enzymeBam HI. There was no association of 2′–5′ oligoadenylate synthetase genotypes with IDDM, but there was a significant correlation between basal 2′–5′ oligoadenylate synthetase activity and 2′–5′ oligoadenylate synthetase genotypes. Significantly higher mean basal levels of 2′–5′ oligoadenylate synthetase activity were associated with HLA-DQA 4.6 phenotype (determined using the restriction enzymeTaq 1 and a DQA probe) and HLA-DR3 (determined serologically), whereas significantly lower mean levels of enzyme activity were associated with HLA-DQA 5.5 and HLA-DR7, in both IDDM and control subjects. An analysis of variance confirmed that these associations were independent 2′–5′ oligoadenylate synthetase genotype. Likewise, a significantly higher mean level of enzyme activity was associated with the heterozygous 1/3 insulin-related genotype in the IDDM subjects only. This study therefore suggests that the possession of certainHLA haplotypes might be associated with differing levels of basal 2′–5′ oligoadenylate synthetase activity.     

Localization of inhibin in testes of human, bonnet monkey, dog and rat by immunoperoxidase technique

Immunocytochemical study on the localization of inhibin in the testes of human, bonnet monkey, dog and rat was carried out using indirect immunoperoxidase technique, in order to investigate the cell types involved in inhibin production/storage. A positive reaction was observed in the testes of human, monkey and dog while it was negative in rat testis using specific antiserum to human testicular inhibin generated against homogeneous preparation of human testicular inhibin in our laboratory. Inhibin was found to be localized in Sertoli cells, spermatogonia and primary spermatocytes of human, monkey and dog testes. A weak positive reaction was observed in spermatids of human testis only. Interestingly, Leydig cells of human, monkey and dog testes showed positive reaction indicating presence of inhibin in these cells also.     

Molecule-based magnets with TC above room temperature: Improved synthesis of vanadium–chromium Prussian blue analogues with inserted alkali cations

We report the synthesis of several new vanadium–chromium Prussian blue analogues with a Curie temperature above room temperature. A catalytic amount of vanadium(III) during the synthesis allows to get improved magnetic properties, stable Curie temperatures (T_C) and a magnetisation at saturation in satisfying agreement with the stoichiometry. The insertion of alkali cations (potassium, rubidium, caesium) allows to reach a V:Cr stoichiometry close to 6:5, hence to enhance the number of magnetic neighbours compared to the usual V:Cr 3:2 stoichiometry and to increase accordingly the Curie temperature. For the same stoichiometry, the ferrimagnetic ordering temperature varies slightly with the nature of the inserted alkali cation (T_C/K = 360, 346 and 340 K for the potassium, rubidium and caesium derivatives, respectively). X-ray absorption spectroscopy allows to characterise the local surroundings of the chromium and vanadium ions and to propose an explanation of the magnetic properties.     

Prostate--a novel target for evaluation of FSH modulating peptides

Effects of prostatic inhibin peptide and its synthetic fragments on FSH biosynthesis by the human pituitary and prostate, were examined in vitro. The results showed that FSH biosynthesis by prostatic tissue is modulated by these peptides in a similar fashion to that observed at the pituitary level.     

Electron microscopic evidence of an immobilized living cell system

Whole cells of Rhodopseudomonas capsulata were immobilized by entrapment in Ca²⁺ alginate gel. The cell growth inside the matrix was observed by transmission electron microscopy. Colonies enlarged upon incubation, giving some evidence of an immobilized living cell system. This observation was correlated by measurements of bacteriochlorophyll, nitrogen, and protein content.     

Sperm design and sperm function

Spermatozoa vary enormously in their form and dimensions, both between and within species, yet how this variation translates into fertilizing efficiency is not known. Sperm swimming velocity is a key determinant of male fertilization success, but previous efforts to identity which sperm phenotypic traits are associated with swimming velocity have been unsuccessful. Here, we examine the relationship between the size of several sperm components and sperm swimming velocity in natural populations of red deer (Cervus elaphus hispanicus) where selective pressures to enhance male reproductive success are expected to be strong. Our results show that there is little within-male and considerable between-male variation in sperm dimensions. Spermatozoa with longer midpieces swim more slowly, a finding which does not support the hypothesis that the size of the midpiece determines the amount of energy which is translated into swimming speed. In contrast, spermatozoa with elongated heads, and those in which the relative length of the rest of the flagellum is longer, swim faster. Thus, the hydrodynamic shape of the head and the forces generated by the relative size of the rest of the flagellum seem to be the key determinants of sperm swimming velocity.