In-vitro and in-vivo responsiveness of the corpus luteum of the mare to gonadotrophin stimulation

Dispersed horse luteal cells were used to evaluate the ability of horse LH, hCG and PMSG to stimulate progesterone secretion in vitro. Morphological characterization of these cells before gonadotrophin stimulation indicated the presence of two populations of cells based on cell diameters. In luteal cells incubated as suspended cells, horse LH and hCG stimulated (P less than or equal to 0.05) progesterone production at all levels of treatment. Stimulation of progesterone secretion by hCG was greater (P less than or equal to 0.05) than by horse LH over the range of concentrations utilized. When mares (N = 7) received an intramuscular injection of 1000 i.u. hCG on Days 3, 4 and 5 after the end of oestrus, there was an increase (P less than or equal to 0.05), in peripheral progesterone concentrations beginning on Day 7 and continuing until Day 14 compared with controls (N = 7). Peripheral progesterone concentrations continued to be elevated in hCG-treated mares for Days 15-30 after oestrus in those mares that conceived. Although treatment with hCG increased progesterone concentrations, it had no influence on anterior pituitary release of LH as measured by frequency and amplitude of LH discharge. We conclude that the mare corpus luteum is responsive to gonadotrophins in vitro and that exogenous hCG can enhance serum progesterone concentrations throughout the oestrous cycle and early pregnancy.     

Cloning, sequencing and distribution of the Salmonella typhimurlum LT2 siaiidase gene, nanH, provides evidence for interspecies gene transfer

The Salmonella typhimurium LT2 sialidase (neuraminidase, EC 3.2.1.18) structural gene, nanH, has been cloned and sialidase overproduced from multicopy plasmids in Escherichia coli. Sialidase expression was regulated positively by cAMP. In contrast, certain Tn1000 insertions located upstream of nanH coding sequences reduced sialidase activity. A nanH chromosomal insertion mutation constructed by marker exchange demonstrated a single sialidase gene copy in S. typhimurium LT2. The complete nucleotide sequence of nanH, encoding a 41,300 dalton polypeptide, was determined and the derived primary structure was similar to sialidases from Clostridium perfringens, Clostridium sordellii, Bacteroides fragilis, and Trypanosoma cruzi. Comparative sequence analysis, including codon usage and secondary structure predictions, indicated that the S. typhimurium and clostridial sialidases are homologous, strongly suggestive of an interspecies gene transfer event. At least two primary sequence motifs of the bacterial enzymes were detected in influenza A virus sialidases. The predicted secondary structure of the bacterial enzymes was strikingly similar to viral sialidase. From the population distribution of nanH detected within a collection of salmonellae, it was apparent that S. typhimurium obtained its nanH copy most recently from Salmonella arizonae. S. typhimurium LT2 is thus a genetic mosaic that differs from other strains of even the same serotype by nanH plus potentially additional characters linked to nanH. These results have relevance to the evolution and function of sialidases in pathogenic microbes, and to the origin of the sialic acids.     

HPLC isolation and GC-MS characterization of a compound strongly cross reacting with tetrahydroaldosterone antiserum

Urines from patients with hypertension and elevated aldosterone levels, i.e. primary aldosteronism due to adrenal adenoma or hyperplasia or carcinoma were extracted, paper chromatographed and thereafter chromatographed repeatedly with normal phase and repeatedly with reversed phase HPLC systems in an attempt to find new metabolites of aldosterone. Specific 3 alpha-hydroxy-5 beta-tetrahydroaldosterone antiserum was used in a radioimmunoassay system to detect possible aldosterone metabolites in the HPLC fractions after each isolation step. The immunoactive HPLC fractions were derivatized and analysed by GC-MS. A relatively nonpolar compound, 11 beta:18(S),18:20 alpha-diepoxy-5 beta-pregnan-3 alpha-ol, was isolated and identified in this manner. This material was originally described by Kelly et al., in 1962 after loading human subjects with huge amounts (25-160 mg) of exogenous aldosterone. This material has not yet been described from endogenously produced aldosterone. Very small amounts, if any, were similarly isolated from the urine of a control subject. Therefore, this compound could prove to be a new marker for hypertension due to hyper-production of aldosterone.     

The regulation of steroidogenesis is different in the two types of ovine luteal cells

Ovine luteal tissue contains two distinct steroidogenic cell types, small (8-20 microns) and large (greater than 20 microns), which differ based on morphological and biochemical criteria. Unstimulated small cells secrete low levels of progesterone, respond to LH or dibutyryl cAMP (dbcAMP) with enhanced secretion of progesterone, and contain most of the receptors for LH. The unstimulated large cells, conversely, secrete high levels of progesterone, have few, if any, receptors for LH, and do not respond to LH or dbcAMP with increased progesterone secretion. The lack of response to dbcAMP by large cells was investigated. Large cells incubated in the presence of cholesterol, ram serum, or 25-hydroxycholesterol did not demonstrate substrate limitation. Hormone-independent stimulation of adenylate cyclase by cholera toxin or forskolin resulted in increased adenylate cyclase activities (P less than 0.01), cAMP accumulation (P less than 0.05), and the binding of endogenous cAMP (P less than 0.05) by type I cAMP-dependent protein kinase in both small and large cells. These treatments were accompanied by enhanced secretion of progesterone (P less than 0.05) in small cells. In contrast, large cells did not respond with an increase in progesterone secretion under these conditions. These observations suggest that the high rate of secretion of progesterone in unstimulated large cells is not regulated by cAMP.     

immunocytochemical localization of urokinase-type plasminogen activator in lewis lung carcinoma

The invasively growing and metasizing Lewis lung carcinoma consistently contained urokinase-type plasminogen activator (u-PA) enzyme activity. When investigated immunocytochemically with antibodies against u-PA, different parts of individual tumors showed a pronounced heterogeneity in staining intensity. Strong staining was found in areas with invasive growth and degradation of surrounding normal tissue, while other areas were completely devoid of staining. Immunoreactivity occurred both with a perinuclear cytoplasmic localization in tumor cells and associated with apparently extracellular material. SDS PAGE of tumor extracts, under both reducing and nonreducing conditions, followed by immunoblotting, showed only one immunocytochemically stainable band with an electrophoretic mobility corresponding to that of purified proenzyme to u-PA, while no two-chain u-PA was detected. This indicates that the major part of the activator in Lewis lung carcinoma is present as one-chain pro-u-PA.     

Influence of photoperiod and temperature on testicular recrudescence and body growth in the lizards, Lacerta sicula and Lacerta muralis

Annual testicular cycles in the lizards Lacerta sicula and L. muralis appear to be regulated by the interaction between seasonal changes in body temperature and an endogenous rhythmicity in thermal responsiveness. Photoperiodism does not appear to be an important factor; i.e. testicular activity does not appear to be regulated by daylength.
Following testicular regression in July, the lizards are refractory to sexual stimulation by high temperatures (i.e. normal preferred levels) for about five months. High temperatures accelerate gonadal regression and prevent recrudescence during late summer. Reduced temperatures stimulate testicular enlargement and spermatid formation during the autumn; this recrudescence can be blocked by treatment with testosterone. Very low temperatures suppress gonadal activity during mid-winter.
Maintenance of lizards at constant high temperatures (33°C) starting in July suppresses testicular recrudescence until December. Also, testicular collapse occurs in lizards transferred to high temperatures after recrudescence has started. The gonads are stimulated by exogenous gonadotropins at 33°C during the fall indicating that high temperatures reduce circulating levels of gonadotropins.
The refractoriness to high temperatures is "spontaneously" terminated during midwinter (December) under a wide range of photo-thermal conditions. Low temperatures may accelerate the termination of refractoriness. Thereafter, high temperatures stimulate, and are required for the final development of the testes and accessory sexual structures. Thus, the increase in body temperature following hibernation times the onset of breeding in the spring.
Temperature also has a marked influence on appetite and growth, independent of photo-period. Weight gains are greater at 33° than at 20°C. At 33° there is a tendency for abdominal fat bodies to enlarge but with little hepatic growth; whereas, the reverse occurs at 20°C.     

Haemophilia A: database of nucleotide substitutions, deletions, insertions and rearrangements of the factor VIII gene, second edition.

A large number of different mutations in the factor VIII (F8) gene have been identified as a cause of haemophilia A. This compilation lists known single base-pair substitutions, deletions and insertions in the F8 gene and reviews the status of the inversional events which account for a substantial proportion of mutations causing severe haemophilia A.     

Haemophilia A: database of nucleotide substitutions, deletions, insertions and rearrangements of the factor VIII gene, second edition.

A large number of different mutations in the factor VIII (F8) gene have been identified as a cause of haemophilia A. This compilation lists known single base-pair substitutions, deletions and insertions in the F8 gene and reviews the status of the inversional events which account for a substantial proportion of mutations causing severe haemophilia A.     

The sialidase superfamily and its spread by horizontal gene transfer

Sialidases (neuraminidases, EC 3.2.1.18) belong to a class of glycosyl hydrolases that release terminal N-acylneuraminate (slalic acid) residues from glycoproteins, glycolipids, and polysaccharides. These enzymes are common in animals of the deuterostomate lineage (Echinodermata through Mammalia) and also in diverse microorganisms that mostly exist as animal commensals or pathogens. Sialidases, and their sialyl substrates, appear to be absent from plants and most other metazoans. Even among bacteria, sialidase is found irregularly so that related species or even strains of one species differ in this property. This unusual phylogenetic distribution makes sialidases interesting for evolutionary studies. The biochemical diversity among bacterial sialidases does not indicate close relationships. However, at the molecular level, homologies are detectable, supporting the hypothesis of a common sialidase origin and thus of a sialidase super family. Some findings indicate that sialidase genes were recently transferred via phages among bacteria. The proposal of a sialidase origin in higher animals is suggested by the presence of apparently homologous enzymes in this kingdom, supporting the idea that some microbes may have acquired the genetic information during association with their animal hosts.