Sperm concentration influences fertilization and male pronuclear formation in vitro in pigs

To study the effect of sperm concentration on the results of pig in vitro fertilization (IVF), 313 oocytes recovered from oviducts of prepubertal gilts after induction of ovulation were used. After capacitation, the number of live spermatozoa in the fertilization dishes was adjusted to 3 x 10(5), 6 x 10(5) and 12 x 10(5) cell/ml. After 4 hours of co-culture in TCM-199, the oocytes were pippeted to remove cumulus cells and the excess spermatozoa around the zona pellucida, and were transferred to fresh TCM-199 for another 12 14 hours . The results showed that 6 x 10(5) spermatozoa/ml is the optimum concentration for this system; the percentage of fertilized ova (71.6%) was not different from the best (76.8%), that was obtained with the highest concentration, and the percentage of monospermy (62.3%) was not different from the best (68.1%), that was obtained with the lowest concentration. The percentage of spermatozoa that reached the pronuclear stage increased while sperm concentration was decreased. The percentage of spermatozoa at the decondensed stage was decreased when the sperm concentration increased.     

Repetitive DNA sequence families in Crepis capillaris

Three families of tandemly repetitive DNA from Crepis capillaris were cloned and characterized. Data obtained from in situ hybridization indicate that these families are located mainly in the heterochromatic C-bands. The pCcH32 family hybridizes at the paracentromeric C-band of the NOR (nucleolus-organized region) chromosome and along most of the long arm of the same chromosome. The pCcD29 family is located in all the remaining C-bands of the karyotype, while the third family, pCcE9, is restricted to the more proximal C-bands. Nucleotide sequence comparisons between one cloned repeating unit from each DNA family showed some significant regions of homology between the families. We discuss the sequence relationships between the three DNA families and the significance of our data in relation to models of heterochromatin evolution, emphasizing the concepts of equilocality and the differentiation of the NOR-bearing chromosome. We also examine the possible role that chromosome disposition, in either mitotic or meiotic nuclei, plays in the distribution and homogenization of heterochromatic DNA sequences.     

Histopathological studies ofSporothrix schenckii-inoculated mice

Defense mechanisms againstSporothrix schenckii were studied using mouse models. After an intracutaneous injection of the yeast form ofS. schenckii to the dorsal skin of the congenitally athymic nude and normal heterozygote littermate mice, nodules were formed. They regressed and disappeared in 10 weeks in the case of normal mice. On the other hand, nodules and then ulceration developed progressively in nude mice until all animals expired by dissemination of microorganisms at the 11th week of inoculation. Histopathologically the migrated cells were similar in both the normal and the nude mice, particularly during the early phase (within 24 h), with infiltration by PMNs being predominant. Fragmentation ofS. schenckii commenced early during the 12–24 h stage of inoculation in the normal mice, while such fragmentation was scarce in nude mice even though numerous PMNs accumulated. Microscopic observations in the early stages (within 24 h of inoculation) suggested that the lack of killing activity by PMNs in nude mice contributes more to the impaired defense than the lack of macrophage activation by T-cells.     

Gastric colonization withCandida albicans

This is the first report on the isolation ofCryptococcus neoformans from pigeon droppings in China and their serotypes.C. neoformans colonies which produced brown colonies on caffeic acid-cornmeal agar were found in Twenty-five out of thirty-six samples of pigeon droppings. Fifty-one colonies randomly picked from the positive samples were identified asC. neoformans by a commercially available kit for carbon source assimilation test and Christensen's urea agar. Forty (78%) out of the 51 strains were serotyped as A and 11 (22%) as AD. At the same time, seventeen out of nineteen clinical isolates were serotyped as A and 2 as B. There are three findings in our results. One is that onlyC. neoformans var.neoformans strains could be isolated from pigeon droppings, although the varietygattii strains were found in the clinical isolates obtained in the same geographic site in China. The second is that serotype A strains were most frequently seen in natural and clinical materials in the southeast part of China, and serotype AD strains were isolated in pigeon droppings but not in clinical materials. The third is that the coexistence of serotype A and AD cells ofC. neoformans strains in same samples of pigeon droppings were observed.     

Two bacteria causing farmer's lung: Fine structure ofThermoactinomyces vulgaris andSaccharopolyspora rectivirgula

Larval cuticle ofHelicoverpa (Heliothis)zea and yeast extract added to a minimal medium (MM) induced germination of conidia ofNomuraea rileyi whereas sterile distilled water or MM alone did not. Yeast extract increased mycelial yield, but when cuticle was added, mycelial yield significantly decreased. Proteases and chitinases ofN. rileyi were only expressed when cuticle was added to the MM.This article reports the results of research only. Mention of a proprietary product in this paper does not constitute a recommendation for use by US Department of Agriculture.     

Antibacterial activity of Lactobacillus strains isolated from dry fermented sausages

One hundred strains of lactic acid bacteria isolated from dry cured sausages were tested for antagonistic activity against a set of test strains. Nine of 52 strains of Lactobacilus casei and three of 48 strains of Lact. plantarun produced inhibition zones against the indicator species. The substance excreted by Lact. casei CRL 705 was active against Lact. plantarum, Listeria monocytogenes, Staphylococcus aureus and a wide range of Gram-negative bacteria. The activity of the antibacterial compound from Lact. casei CRL 705 was destroyed by papain, trypsin and pepsin, but was resistant to heat (100°C for 20 min), lysozyme and catalase. The agent was produced during the growth cycle and when the concentrated and neutralized supernatant fluid was added to a fresh culture of sensitive cells it produced a rapid inactivation. A decrease in optical density (O.D.) over time, indicative of cell lysis, was also observed. These characteristics allowed us to identify the inhibitory compound as a bacteriocin which we termed Lactocin 705.     

Inducible transport of citrate in Lactobacillus rhamnosus ATCC 7469

Lactobacillus rhamnosus ATCC 7469 exhibited diauxie when grown in a medium containing both glucose and citrate as energy source. Glucose was used as the primary energy source during the glucose-citrate diauxie. Uptake of citrate was carried out by an inducible citrate transport system. The induction of citrate uptake system was repressed in the presence of glucose. This repression was reversible and mediated by cAMP.     

Physiology of lipase formation inPenicillium candidum

Penicillium candidum grew and produced lipase in a culture medium supplemented with 0.2% olive oil. Significant enzyme production required the presence of olive, oil and was prevented by cycloheximide. Polyacrylamide gel electrophoresis of filtrates from olive oil fermentations gave a single band of lipase activity (MW 80 KDa). Among the olive oil components only oleate allowed significant lipase production. Other carboxylic and saturated fatty acids containing similar or lower numbers of carbon atoms, did not cause derepression of lipase formation.     

Differential ligand binding by two subunits of the rat liver asialoglycoprotein receptor

The rat liver asialoglycoprotein receptor consists of two typesof subunits, a predominant polypeptide designated rat hepaticlectin 1 (RHL-1) and a minor polypeptide, RHL-2/3, that comesin two differentially glycosylated forms. The exact stoichiometryand arrangement of the subunits in the RHL oligomer are notknown. The carbohydrate-recognition domain of RHL-2/ has beenprepared by limited proteolysis of the liver receptor so thatits properties can be compared with those of the correspondingdomain of RHL-1 previously produced in a bacterial expressionsystem. Binding studies indicate that while RHL-1 binds N-acetylgalactosaminewith approximately 60-fold higher affinity than it binds galactose,RHL-2/ has only 2-fold selectivity for N-acetylgalactosamine.In general, the pattern of monosaccharide-binding specificityfor RHL-2/ is similar to RHL-1, but the discrimination of varioussugars relative to galactose is reduced substantially. Limitedproteolysis and crosslinking studies demonstrate that RHL- 2/is easily removed from the RHL oligomer in detergent solutionand that RHL-1 remains at least trimeric following removal ofRHL-2/. These studies suggest that RHL-1 forms a ligand-bindingcore while RHL-2/ acts more as an accessory subunit contributingto selective binding of certain oligosaccharide structures. asialoglycoprotein receptor binding carbohydrate recognition lectin proteolysis