Characterization of a novel testicular form of human hormone-sensitive lipase

Hormone-sensitive lipase (HSL) is an esterase and lipase, which are essential for spermatogenesis. Two HSL mRNAs are expressed in human testis. A long form is encoded by a testis-specific exon and nine exons common to testis and adipocyte HSL. Here we show that the short-form 3.3-kb mRNA possesses a unique 5' end that is transcribed from a novel testis-specific exon. The corresponding protein is similar to the 775-amino-acid-long adipocyte HSL. Immunohistochemistry experiments on human testis sections revealed that the long form is strictly expressed in haploid germ cells whereas the short form is expressed in interstitial and tubular somatic cells as well as premeiotic germ cells.     

Forskolin up-regulates metastasis-related phenotypes and molecules via protein kinase B,but not PI-3K,in H7721 human hepato-carcinoma cell line

Forskolin (FSK) is known as an up-regulator of intracellular cAMP and inhibitor of cancer growth and metastasis. The effects of FSK on the metastasis potential and its mechanisms were studied using a human hepatocarcinoma cell line, H7721. It was found that FSK stimulated cell growth, increased cAMP in the cells, and enhanced the metastasis-related phenotypes, including adhesion to laminin (Ln) and human umbilical vein epithelial cells (HUVEC), chemotactic migration and invasion. These effects were supposed to result from the increase of the SLe^x expression induced by FSK, since only the monoclonal antibody of SLe^x showed a significant attenuation of the enhanced metastasis-associated phenotypes. Using H7721 cells transfected with the sense or antisense cDNA of protein kinase B (PKB) and some inhibitors of signal transduction, it was discovered that FSK up-regulated the expression of SLe^x via PKB, but it was independent of phosphotidylinositide-3-kinase (PI-3K). A subtype of atypical protein kinase C (-PKC) might also participate in the up-regulation of SLe^x expression by FSK, and cAMP/PKA pathway is a negative regulator of SLe^x expression on H7721 cells. It can be concluded that FSK shows a metastasis-promoting effect ex vivo.     

Crystal structure of the catalytic domain of human bile salt activated lipase

Bile-salt activated lipase (BAL) is a pancreatic enzyme that digests a variety of lipids in the small intestine. A distinct property of BAL is its dependency on bile salts in hydrolyzing substrates of long acyl chains or bulky alcoholic motifs. A crystal structure of the catalytic domain of human BAL (residues 1-538) with two surface mutations (N186D and A298D), which were introduced in attempting to facilitate crystallization, has been determined at 2.3 A resolution. The crystal form belongs to space group P2(1)2(1)2(1) with one monomer per asymmetric unit, and the protein shows an alpha/beta hydrolase fold. In the absence of bound bile salt molecules, the protein possesses a preformed catalytic triad and a functional oxyanion hole. Several surface loops around the active site are mobile, including two loops potentially involved in substrate binding (residues 115-125 and 270-285).     

Pirimiphos-methyl resistance in two stored product mites, Acarus siro and Acarus farris, as detected by impregnated paper bioassay and esterase activity assays

The response to pirimiphos-methyl, in one strain of Acarus farris and two strains of Acarus siro, was assessed using an impregnated filter paper bioassay and by the selection of adults following exposure to pirimiphos-methyl. It was concluded that one of the strains of A. siro was resistant to pirimiphos-methyl and that a major resistance mechanism was involved. The second strain of A. siro gave a response similar to that of a laboratory strain unexposed to organophosphates and was considered to be susceptible. The A. farris strain responded to selection at the ED50 but not at the ED99, and it was concluded that a minor resistance mechanism is present in this strain. Assays of esterase activity were used to attempt to identify the biochemical mechanisms involved in the resistance detected by the bioassays. The A. farris and susceptible A. siro strains showed similar levels of esterase activity but the esterase activity of the resistant A. siro strain was significantly greater. An increase in esterase activity followed selection of both the A. farris strain and the resistant A. siro strain. An acetylcholinesterase assay showed no significant difference between the susceptible and pirimiphos-methyl selected strains of A. siro. The results suggest that esterases are involved in the resistance to pirimiphos-methyl found in A. siro and A. farris but that in A. siro, at least, other mechanisms may also be present.     

Production of xylanases from a newly isolated alkalophilic thermophilic Bacillus sp.

A new thermophilic strain of Bacillus SPS-0 which produces thermostable xylanases was isolated from a hot spring in Portugal. Xylanase production was 50 nkat/ml in the presence of wheat bran arabinoxylan. The temperature and pH for optimum activity were 75°C and 6–9, respectively. The hydrolysis patterns demonstrated that crude xylanases yield mainly xylose and xylobiose from xylan, whereas xylose and arabinose were produced from destarched wheat bran. An increase in xylose release was observed when SPS-0 xylanase was supplemented by a ferulic acid esterase. © Rapid Science Ltd. 1998     

A critical evaluation of copper metabolism in indian wilson’s disease children with special reference to their phenotypes and relatives

Wilson’s disease is an autosomal recessive disorder of copper accumulation in various organs, with most common clinical manifestations such as hepatic, neurological, and renal dysfunctions. Serum copper and ceruloplasmin in Wilson’s disease were significantly lower as compared to normals, controls, and relatives of Wilson’s disease patients, whereas marked hypercupriuria (145 ± 7 μg/24 h) was observed in Wilson’s children only. A good correlation (r = 0.92) was found between non-ceruloplasmin-bound copper and 24-h urinary copper excretion in Wilson’s disease patients. Further, copper studies among the different phenotypes of Wilson’s disease revealed substantially low serum ceruloplasmin and a marked hypercupriuria in Wilson’s disease children associated with renal tubular acidosis as compared to the patients with either hepatological or neurological manifestations. Serum ceruloplasmin levels in 14 patients of Wilson’s disease were between 14 and 20 mg/dL. These patients of Wilson’s disease were confirmed by measuring liver biopsy copper, which was about nine times higher than normal hepatic copper content. During the family screening by copper studies, four asymptomatic siblings were diagnosed for Wilson’s disease. These subjects were then started on D-penicillamine therapy because presymptomatic treatment prevents progression of the disease complications.     

Characterization of a shiitake mutant strain producing ballshaped fruiting bodies

Growth characteristics of a spontaneous mutant of shiitake Lentinula edodes (Berk.) Pegler were studied. The mutant was first detected as a result of changes in the growth habit of the normal strain in the liquid medium. Abundant formation of aerial hyphae was distinctive. In sawdust logs the mutant strain produced abnormal basidiocarps, lacking stipe, gill and spore formation.
Growth rates of the normal and the mutant strain were compared in two liquid media: malt-yeast extract and Leatham's medium. The increase in dry weight of the mutant's mycelium was much higher than that of the wild type in both media, which indicated better adaptation to liquid culture. In the sawdust, however, growth of the mutant was slower than that of the normal strain. The mutant's intracellular protein content was lower than that of the normal strain. The pH of the liquid cultures differed: the wild type decreased the pH during growth, while the mutant increased the pH. Comparison of the protein and esterase isoenzyme profiles of the vegetative hyphae of both strains indicated profound differences. One protein (pI 6.5, 39 kDa), which in earlier studies has been found to be typical of L. edodes species, was absent from the mutant's profile. Differences in the esterase profile were also clear.     

Reproductive isolation among allopatric Drosophila montana populations

An outstanding goal in speciation research is to trace the mode and tempo of the evolution of barriers to gene flow. Such research benefits from studying incipient speciation, in which speciation between populations has not yet occurred, but where multiple potential mechanisms of reproductive isolation (RI: i.e., premating, postmating‐prezygotic (PMPZ), and postzygotic barriers) may act. We used such a system to investigate these barriers among allopatric populations of Drosophila montana. In all heteropopulation crosses we found premating (sexual) isolation, which was either symmetric or asymmetric depending on the population pair compared. Postmating isolation was particularly strong in crosses involving males from one of the study populations, and while sperm were successfully transferred, stored, and motile, we experimentally demonstrated that the majority of eggs produced were unfertilized. Thus, we identified the nature of a PMPZ incompatibility. There was no evidence of intrinsic postzygotic effects. Measures of absolute and relative strengths of pre‐ and postmating barriers showed that populations differed in the mode and magnitude of RI barriers. Our results indicate that incipient RI among populations can be driven by different contributions of both premating and PMPZ barriers occurring between different population pairs and without the evolution of postzygotic barriers.     

Receptor binding and pH stability — How influenza A virus hemagglutinin affects host-specific virus infection

Influenza A virus strains adopt different host specificities mainly depending on their hemagglutinin (HA) protein. Via HA, the virus binds sialic acid receptors of the host cell and, upon endocytic uptake, HA triggers fusion between the viral envelope bilayer and the endosomal membrane by a low pH-induced conformational change leading to the release of the viral genome into the host cell cytoplasm. Both functions are crucial for viral infection enabling the genesis of new progeny virus.