Physiology of the epididymis and spermatozoa

The epididymis is an ideal extragonadal target site to inhibit fertility in the male. Synthesis and secretion of constituents like sialic acids, protein and glycerylphosphoryl choline by the epididymal epithelium under androgen control provide an ideal fluid environment for sperm maturation. An optimal level of sialic acid secretion by the epididymal epithelium is needed to maintain functional integrity of sperm. The existence of specific androgen receptors in the epididymis and spermatozoa are related to their ability to metabolise androgens.     

Effect of L-cystine on macromolecular changes during spore and parasporal crystal formation inBacillus thuringiensis var.thuringiensis

High concentration of L-cystine (0.25%) when present in a glucose-mineral salt medium inhibited sporulation-specific events like protease production, calcium uptake and dipicolinic acid synthesis inBacillus thuringiensis var.thuringiensis. In addition, the enzymes of the Krebs cycle from aconitase onwards were completely inhibited by a high concentration of cystine. At a low concentration of cystine (0.05%), none of the above mentioned macromolecular changes were affected. Lipid synthesis monitored by [1,2¹⁴ C]-acetate incorporation into lipid as well as into whole cells was completely inhibited.     

Spore and crystal formation inBacillus thuringiensis var.thuringiensis during growth in cystine and cysteine

The effect of the addition of different concentratons of cystine and cysteine on sporulation and parasporal crystal formation inBacillus thuringiensis var.thuringiensis was studied. The effect was well pronounced when the cystine/cysteine additions were made after the stationary phase. Heat stable spores and crystals were formed when the culture was provided with a low concentration of cystine/cysteine (0.05 per cent w/v). At a moderate concentration of cystine or cysteine (0.15%), only heat labile spores were formed without the production of the crystal. When the cystine/cysteine concentration was high (0.25%), spore and crystal formation were completely inhibited. Partial reversal of inhibition of sporulation was brought about by sodium sulphate or Zinc sulphate and lead, copper, cadmium or cobalt acetate at 0.2 mM or at 0.2% of sodium or potassium pyruvate, citrate, cisaconitate, oxalosuccinate, ∞ -keto-glutarate, succinate, fumarate, malate, or oxalacetate. Glutamate (0.2%) overcame the inhibitory effect of cystine/cysteine completely. The structural changes observed using phase contrast microscopy were dependent upon the concentration of cystine/cysteine.     

In vivo replication of carcinogen-modified rat liver DNA: increased susceptibility of O6-methylguanine compared to N-7-methylguanine in replicated DNA to S1-nuclease

In order to characterize rat liver DNA replicated $\text{in}\text{vivo}$ on a carcinogen-damaged template, the replicated DNA was treated with S₁-nuclease and the release of (¹⁴C)-dimethyl-nitrosamine induced 0⁶-methylguanine, a lesion associated with miscoding and N-7-methylguanine, a lesion that does not miscode were monitored. The results indicated that both the methylated guanines became susceptible to S₁-nuclease upon replication. However, a greater percentage of 0⁶-methylguanine (22% of the total 0⁶-methylguanine present in the DNA) compared to N-7-methylguanine (4% of the total N-7-methylguanine present in the DNA) was rendered acid soluble by S₁-nuclease. The preferential release of 0⁶-methylguanine compared to N-7-methylguanine from replicated DNA was interpreted to indicate its occurrence in local denatured regions probably generated as a result of misbase pairing.     

In vitro metabolism of androgens by mammalian cauda epididymal spermatozoa.

The in vitro metabolism of [3H] testosterone (17beta-hydroxy-4-androsten-3-one), [3H] androstenedione (4-androstene-3,17-dione) and [3H] dehydroepiandrosterone (3beta-hydroxy-5-androsten-17-one) by cauda epididymal spermatozoa from the rat, rabbit, hamster, guinea-pig and ram, varied between species. There were differences in the androgens utilized, the extent of their conversion and the identities of the metabolites formed. Of the steroid substrates tested rat spermatozoa metabolized testosterone preferentially while spermatozoa from guinea-pig transformed [3H] dehydroepiandrosterone (DHEA) almost exclusively. Rabbit spermatozoa converted all three [3H] androgens while hamster sperm utilized [3H] testosterone and [3H] DHEA. Spermatozoa collected from rams killed at the abattoir metabolized both [3H] androstenedione and [3H] DHEA but this capacity was dramatically reduced in spermatozoa collected from rams subjected to short-term anaesthesea. The results are discussed in relation to the possible direct roles of androgens in sperm physiology.     

Serum and semen levels of immunoreactive prolactin, LH and FSH in normospermic, oligospermic and azoospermic men with obstructive infertility prior to and after vasoepididymostomy.

Attempts were made to validate RIA for prolactin (PRL), LH and FSH in semen from normospermic, oligospermic and azoospermic subjects. The RIA used to measure PRL and LH in semen fulfilled the criteria of reliability, whereas low levels of FSH in semen precluded the validation of FSH assay in semen. Semen levels of PRL and LH were significantly (P < 0.05) higher than serum levels in all groups of subjects investigated. Semen levels of FSH in azoospermic men after vasoepididymostomy (VEA), were significantly (P < 0.05) higher compared to azoospermic men prior to surgery. Serum levels of PRL were significantly higher (P < 0.05) in normospermic men compared to oligospermic and azoospermic men prior to and after surgery. Semen levels of PRL in normospermic men were comparable with oligospermic and azoospermic subjects prior to and after surgery. Serum levels of LH in oligospermic and azoospermic men who did not undergo surgery and in men reporting oligospermia after VEA were comparable to normospermic subjects but in men showing azoospermia post surgically, serum LH levels were significantly (P < 0.005) elevated. Semen levels of LH in men reporting azoospermia before surgery and in subjects showing oligospermia or azoospermia post surgically were significantly lower (P < 0.05) compared to men with normal sperm count. Serum levels of FSH were significantly elevated (P < 0.05) compared to semen levels in oligospermic men prior to surgery but this increase was not seen in post VEA subjects. These results were discussed.     

Growth promotion activity and biological control for the management of leaf blight incited by Alternaria helianthi

The Pseudomonas fluorescens (Pf1), Bacillus subtilis (Bs1) are the major potential biocontrol agents against foliar pathogens. MPf1 and MBs1 were found to be the most effective in inhibiting the mycelial growth of Alternaria helianthi. These biocontrol agents have the maximum capacity in controlling the spore germination, and data showing the growth-promoting effect of biocontrol agents and inhibition of seed-borne fungi are available. Seed-borne infections of A. helianthi are controlled by seed treatment with P. fluorescens, which showed least seed infection. The root length and shoot length has also been increased.     

Genome Sequencing Unveils a Novel Sea Enterotoxin-Carrying PVL Phage in Staphylococcus aureus ST772 from India

Staphylococcus aureus is a major human pathogen, first recognized as a leading cause of hospital-acquired infections. Community-associated S. aureus (CA-SA) pose a greater threat due to increase in severity of infection and disease among children and healthy adults. CA-SA strains in India are genetically diverse, among which is the sequence type (ST) 772, which has now spread to Australia, Europe and Japan. Towards understanding the genetic characteristics of ST772, we obtained draft genome sequences of five relevant clinical isolates and studied the properties of their PVL-carrying prophages, whose presence is a defining hallmark of CA-SA. We show that this is a novel prophage, which carries the structural genes of the hlb-carrying prophage and includes the sea enterotoxin. This architecture probably emerged early within the ST772 lineage, at least in India. The sea gene, unique to ST772 PVL, despite having promoter sequence characteristics typical of low expression, appears to be highly expressed during early phase of growth in laboratory conditions. We speculate that this might be a consequence of its novel sequence context. The crippled nature of the hlb-converting prophage in ST772 suggests that widespread mobility of the sea enterotoxin might be a selective force behind its ‘transfer’ to the PVL prophage. Wild type ST772 strains induced strong proliferative responses as well as high cytotoxic activity against neutrophils, likely mediated by superantigen SEA and the PVL toxin respectively. Both proliferation and cytotoxicity were markedly reduced in a cured ST772 strain indicating the impact of the phage on virulence. The presence of SEA alongside the genes for the immune system-modulating PVL toxin may contribute to the success and virulence of ST772.