The 56 kDa protein of human genital skin fibroblasts is identical to that radiolabelled by [3H]dihydrotestosterone 17 beta-bromoacetate

Analysis of soluble proteins from human genital skin fibroblasts by two-dimensional polyacrylamide gel electrophoresis reveals an abundant protein doublet of mol. wt 56,000 with isoelectric points (pI) of 6.7 and 6.5. This protein is absent in non-genital skin fibroblasts as well as in genital skin fibroblasts of most patients with complete forms of androgen insensitivity. The protein specifically binds androgen. A protein of similar estimated molecular weight (58,000) from human genital skin fibroblasts has recently been found to be covalently radiolabelled by the affinity ligand dihydrotestosterone 17 beta-bromoacetate (DHT-BA). In the present study these proteins have been found to be indistinguishable on one- and two-dimensional gel electrophoresis. Antibodies raised against the 56 kDa pI 6.7/6.5 protein also recognized the protein covalently radiolabelled by DHT-BA. A third protein of estimated mol. wt 59,000 has been found to be associated with several steroid hormone receptor complexes but has no known ligand binding activity. This protein was found to be clearly separable from the 56/58 kDa protein on two-dimensional gel electrophoresis as it has a more acidic pI of approximately 5.4. Furthermore, antibodies against the 59 kDa protein do not recognize the 56 kDa species, and vice versa.     

An antibody against a CFTR-derived synthetic peptide, incorporated into living submandibular cells, inhibits beta-adrenergic stimulation of mucin secretion.

An antibody raised against a peptide in the first nucleotide-binding domain (NBD) of CFTR [1], incorporated into intact rat submandibular acini by hypotonic swelling, inhibited beta-adrenergic stimulated mucin secretion, without affecting cyclic AMP rise. The data are the first to show that a CFTR-antibody-containing cell results in defective stimulation of mucin secretion, as is seen in CF cells, and that this can be reversed by an excessive increase in cyclic AMP.     

Involvement of the Dihydropyridine Receptor and Internal CaStores in Myoblast Fusion

The process of myoblast fusion during skeletal myogenesis is calcium regulated. Both dihydropyridine receptor and ryanodine receptor are already present on muscle precursors, at the prefusional stage, before they are required for excitation–contraction coupling. Previous pharmacological studies have shown the need for a special pool of Ca²⁺associated with the membrane for the fusion process to occur. We hypothesized that this pool of Ca²⁺is mobilized via a machinery similar to that involved in excitation–contraction coupling. The process of fusion in rat L6 muscle precursors was either totally or partially abolished in the presence of the L-type calcium channel inhibitors SR33557 and nifedipine (half inhibition towards 2 μM), respectively. The inhibition was reversible and dose-dependent. Drugs able to deplete internal calcium stores (caffeine, ryanodine, and thapsigargin) were also tested on the fusion. Both caffeine and thapsigargin drastically inhibited fusion whereas ryanodine had no effect. This suggests that fusion may be controlled by internal pools of Ca²⁺but that its regulation may be insensitive to ryanodine. We presumed that an early form of the ryanodine receptor may exist, with different pharmacological properties than the adult forms. Indeed, Western blot analysis of pre- and postfusional L6 cells demonstrated the presence, at the prefusional stage, of a transient form of the ryanodine receptor protein with an apparent molecular weight slightly different from those of the classical skeletal and cardiac forms. Taken together, these results support the hypothesis that the fusion process is driven by a mechanism involving both the dihydropyridine receptor (α1 subunit of the L-type Ca²⁺channel) and the internal stores of Ca²⁺. The machinery underlying this mechanism might consist of slightly different forms of the classic molecules that in adult muscle ensure excitation–contraction coupling. It remains to be seen, however, whether the mobilization of the internal pool of Ca²⁺is triggered by the type of mechanism already described in skeletal muscle.     

Variable influence of ferric and cupric ions on Saccharomyces cerevisiae strains used in asymmetric organic synthesis

Summary Fe (III) and Cu (II) each at 50 M in four commercial strains of Saccharomyces cerevisiae induced an increase of NAD(P)⁺ reduction in one strain (Turkish), but two others (Chilean and Brazilian), the presence of Fe(III) and/or Cu(II) diminished NAD(P)⁺ reduction presumably due to free radicais formation inside these living cells. Suprisingly, in the American strain, Fe(III) induced a decrease and Cu (II) an increase of NAD(P)⁺ reduction.     

Seasonal variability in mercury inputs into the Ria de Aveiro,Portugal

Water, suspended particulate matter (SPM) and sediments were collected from the Esteiro de Estarreja (Ria de Aveiro, Portugal), which receives considerable quantities of waste mercury from a chlor-alkali plant. Dissolved and particulate Hg concentrations in the effluent ranged between 4 –167 g I^–1 and 141–3144 g g^–1, respectively, at pH values of >10. The effluent plume undergoes significant chemical changes during advection downestuary. The evidence suggested that adsorption of dissolved Hg onto organic-rich SPM was an important process. A maximum sediment Hg concentration of 500 g g^–1 was found about 1.5 km from the discharge, as a result of the settling of Hg-rich SPM. Downestuary Hg concentrations in sediments decline to about 100 g g^–1 at the mouth of the Esteiro. The particle-water interactions are discussed in terms of the transport of dissolved and particulate Hg into the Ria de Aveiro.     

NAD Glycohydrolases: A possible function in calcium homeostasis

NAD glycohydrolases are the longest known enzymes that catalyze ADP-ribose transfer. The function of these ubiquitous, membrane-bound enzymes has been a long standing puzzle. The NAD glycohydrolase are briefly reviewed in light of the discovery by our laboratory that NAD glycohydrolases are bifunctional enzymes that can catalyze both the synthesis and hydrolysis of cyclic ADP-ribose, a putative second messenger of calcium homeostasis.Abbreviations NADase nicotinamide adenine dinucleotide glycohydrolase - NAD nicotinamide adenine dinucleotide - ADP-ribose adenosine diphosphoribose - cADPR cyclic adenosine diphosphoribose     

Fine mapping of the Autosomal Dominant Split Hand/Split Foot Locus on Chromosome 7, Band q21.3-q22.1

Split hand/split foot (SHFD) is a human developmental defect characterized by missing digits, fusion of remaining digits, and a deep median cleft in the hands and feet. Cytogenetic studies of deletions and translocations associated with this disorder have indicated that an autosomal dominant split hand/split foot locus (gene SHFD1) maps to 7q21-q22. To characterize the SHFD1 locus, somatic cell hybrid lines were constructed from cytogenetically abnormal individuals with SHFD. Molecular analysis resulted in the localization of 93 DNA markers to one of 10 intervals surrounding the SHFD1 locus. The translocation breakpoints in four SHFD patients were encompassed by the smallest region of overlap among the SHFD-associated deletions. The order of DNA markers in the SHFD1 critical region has been defined as PON–D7S812–SHFD1–D7S811–ASNS. One DNA marker, D7S811, detected altered restriction enzyme fragments in three patients with translocations when examined by pulsed-field gel electro-phoresis (PFGE). These data map SHFD1, a gene that is crucial for human limb differentiation, to a small interval in the q21.3-q22.1 region of human chromosome 7.     

Subject: Migration

Research Notes on Avian Biology 1994: Selected Contributions from the 21st International Ornithological CongressGeneral Biology: Migration

Subject: Migration     

A Pleiotropic Phospholipid Biosynthetic Regulatory Mutation in Saccharomyces Cerevisiae Is Allelic to Sin3 (Sdi1, Ume4, Rpd1)

Three mutants were identified in a genetic screen using an INO1-lacZ fusion to detect altered INO1 regulation in Saccharomyces cerevisiae. These strains harbor mutations that render the cell unable to fully repress expression of INO1, the structural gene for inositol-1-phosphate synthase. The Cpe(-) (constitutive phospholipid gene expression) phenotype associated with these mutations segregated 2:2, indicating that it was the result of a single gene mutation. The mutations were shown to be recessive and allelic. A strain carrying the tightest of the three alleles was examined in detail and was found to express the set of co-regulated phospholipid structural genes (INO1, CHO1, CHO2 and OPI3) constitutively. The Cpe(-) mutants also exhibited a pleiotropic defect in sporulation. The mutations were mapped to the right arm of chromosome XV, close to the centromere, where it was discovered that they were allelic to the previously identified regulatory mutation sin3 (sdi1, ume4, rpd1, gam2). A sin3 null mutation failed to complement the mutation conferring the Cpe(-) phenotype. A mutant harboring a sin3 null allele exhibited the same altered INO1 expression pattern observed in strains carrying the Cpe(-) mutations isolated in this study.     

Coordinate and independent regulation of αB-crystallin and HSP27 expression in response to physiological stress

α-Crystallins share structural and functional properties with the stress protein hsp27. These polypeptides are expressed at low constitutive levels in many tissues including brain, and αB-crystallin and hsp27 can accumulate in central nervous system glia in a variety of neurological conditions. We report here that heat shock and exposure to transition metals result in an increase in the steady state mRNA level of αB-crystallin and hsp27 in primary cultures of rat forebrain astrocytes. Both exposure to tumour necrosis factor-α and hypertonic conditions result in αB-crystallin mRNA accumulation but no change in the hsp27 mRNA level. Under some of these conditions increased synthesis and accumulation of αB-crystallin and hsp27 protein are also evident. We are unable to detect αA-crystallin mRNA in resting or stressed astrocytes. A novel phenomenon involving a transitory change in stress protein mRNA mobility in Northern blots during induction is reported, which is stress type and cell type independent. The results demonstrate multiple stress regulation of αB-crystallin and hsp27 in cultured astrocytes, suggesting that they can legitimately be regarded as stress proteins in the central nervous system. © 1994 wiley-Liss, Inc.