Somatostatin-containing fibers and neurophysin-containing fibers in the median eminence of the fox, as seen with a double staining cytoimmunoenzyme technique]

In the external layer of the median eminence of the fox, the somatostatin-containing fibers and neurophysin-containing fibers of the hypothalamo-infundibular tract are located in distinct areas. In the neural lobe, somatostatin-positive areas are simultaneously neurophysin-positive. Outside the SON and PVN, some somatostatin-positive and neurophysin-negative perikarya are scattered close to the third ventricle. These facts suggest the existence of two somatostatin systems: a hypothalamo-infundibular (neurophysin-negative) one and a hypothalamo-neurohypophyseal (neurophysin-positive) one.     

Immunocytological study of the gonadotrophic and thyrotrophic cells of the rat adenohypophysis]

On paraffin or semi-thin sections various anti-LH or anti-TSH sera stain indifferently all the thyrotrophs and the gonadotrophs. Inversely anti-beta-TSH, anti-beta-LH or anti-beta-FSH purified sera permit the discrimination of these two cell populations. The constancy of fixation of the anti-beta-LH and anti-beta-FSH sera on all the gonadotrophs gives evidence of their ability to produce both FSH and LH. However in a few female rats the central gonadotrophs are stained more weakly by anti-beta-FSH serum than by anti-beta-LH serum. The purification of the antisera by adjunction of hormonal antigens (alpha subunits or heterologous hormone) does not enable, with the PAP technique on thin sections, a selective staining of the secretory granules of the thyrotrophs or of the gonadotrophs.     

Nuclear cytochrome-deficient mutants of Neurospora crassa: isolation, characterization, and genetic mapping.

Summary We have isolated twenty-six nuclear, singlegene cytochrome-deficient mutants of Neurospora crassa as an initial step toward the study of the structural components and regulatory mechanisms involved in the biogenesis of the mitochondrial cytochrome system. These mutants, together with two previously described mutants, cyt-1 and cyt-2, have been classified into six distinct groups on the basis of cytochrome phenotype: a) cytochrome aa ₃ deficiency (due to mutations affecting loci designated cya); b) cytochrome b deficiency (cyb-1 locus); c) cytochrome b deficiency with a partial deficiency of cytochrome aa ₃ (cyb-2 locus); d) deficiency of both cytochromes aa ₃ and b (cyt loci); e) deficiency of both cytochromes aa ₃ and c (cyt-2 locus); and f) partial deficiency of cytochromes aa ₃ and c (cyt-12 locus).Four of seven mutations affecting cya loci have been mapped and are located on linkage groups I, II, V, and VI. It is not yet known whether these genes code for structural components of cytochrome oxidase or have a regulatory function that affects synthesis or assembly of the enzyme. The cyb-1 and cyb-2 genes are located on linkage groups V and VI, respectively, and appear to code for regulatory elements that control the biogenesis of cytochromes b and aa ₃ . The positions of the cyt mutations that cause a simultaneous deficiency of cytochromes aa ₃ and b are dispersed throughout the genome, except for two gene clusters on the left arm of linkage group I. Some of these mutants may be deficient in mitochondrial protein synthesis. Two mutations, cyt-2 and cyt-12, are located on linkage groups VI and II, respectively, and appear to affect genes that code for components of a regulatory system that controls the biogenesis of cytochromes aa ₃ and c.     

Yeast temperature-sensitive mutants specifically impaired in processing of Poly(A)-Containing RNAs

Summary The selection at 22° C of yeast cordycepin (3-deoxyadenosine) sensitive mutants which would be temperature-sensitive at 37°C allowed the obtention of mutants specifically impaired in processing of Poly(A)-containing RNAs at 37°C. The mutants displaying this phenotype belong to two different loci. The biochemical study of the physiological function which is blocked by the mutation has revealed that the level of radioactive Poly(A)-containing RNAs found in a 5 min pulse after a 10 min shift at 37°C is 6 times less in the mutants than in the wild type without reduction of the non Poly(A)-containing RNAs fraction. Further studies have shown no alteration in the two Poly(A) polymerases activities and suggest strongly a faster decay of Poly(A)-containing RNAs in the mutants.     

Immunocytological studies of C cells with anti-calcitonin or antisomatostatin immunoserums in rats treated with vitamin D, thyroxine or benzyl-thiouracil]

In rats treated with vitamin D3, thyroxin or BTU alone or with associations of vitamin D3 + BTU or vitamin D + thyroxin, immunocytochemical studies with an anti-human calcitonin serum show a stimulating effect of vitamin D and of thyroxin and an inhibiting effect of BTU on the C cells of the thyro?d. These results are in agreement with the existence of functional relations between follicular and C cells. A few calcitonin-containing cells are immunoreactive to an anti-somatostatin serum. All the C cells contain both calcitonin and somatostatin when they are grouped in a single big interfollicular cluster.     

Analysis of Escherichia coli TonB membrane topology by use of PhoA fusions.

Alkaline phosphatase (PhoA) fusions to TonB amino acids 32, 60, 125, 207, and 239 (the carboxy terminus) all showed high PhoA activity; a PhoA fusion to TonB amino acid 12 was inactive. The full-length TonB-PhoA fusion protein was associated with the cytoplasmic membrane and retained partial TonB function. These results support a model in which TonB is anchored in the cytoplasmic membrane by its hydrophobic amino terminus, with the remainder of the protein, including its hydrophobic carboxy terminus, extending into the periplasm.     

Simultaneous detection of two messenger RNAs in the central nervous system: a simple two-step in situ hybridization procedure using a combination of radioactive and non-radioactive probes

We present here a method enabling the simultaneous detection of two messenger RNAs in tissue sections by use of a two-step in situ hybridization procedure. Tissue sections were hybridized with a radioactive probe and coated with emulsion. The emulsion was processed for development, fixed, and a second hybridization was performed through the emulsion with a biotinylated probe subsequently revealed with streptavidin-alkaline phosphatase. This procedure allows the detection of two mRNAs without loss of signal, removal of the emulsion, or spurious reaction. The simultaneous detection of oxytocin and vasopressin mRNAs in the hypothalamus, and of dopamine receptor and neuropeptide mRNAs in the striatum, demonstrated the efficiency of the procedure. Such a two-step procedure provides a simple and flexible way to make possible comparative analysis of the localization of two mRNAs within the same tissue section.