Effect of Gibberellic Acid on Dwarf and Normal Pea Plants

Gibberellic acid at concentrations between 10 and 100 mg/1 greatly stimulated the elongation growth of intact dwarf pea plant but showed little or no effect on that of Alaska pea. It showed no effect on the elongation growth of excised stem segments of either dwarf or normal pea when given alone. Indole-3-acetic acid stimulated the elongation of excised segments of both varieties. Gibberellic acid synergistically enhanced the indole-3-acetic acid-induced elongation of excised segments. Tryptophan also stimulated the elongation of these segments. Gibberellic acid showed a synergistic effect on the tryptophan-induced elongation, as on the indole-3-acetic acidinduced one. Gibberellic acid reduced the lag period of tryptophan-induced elongation, suggesting that gibberellic acid promotes the conversion of tryptophan to auxin.     

Mutants inducible for sexual agglutinability in Saccharomyces cerevisiae

Summary We have isolated the mutants, T55s-41(a) and T562s-161 () which have no sexual agglutinability when cultured at 28°C, but become sexually agglutinable by the action of the sex pheromone produced by respective opposite mating type. The sex-specific glycoproteins responsible for sexual agglutination were detected in the mutants treated with the opposite mating type pheromone, but not in those treated with the same mating type pheromone.The induction of sexual agglutinability by the pheromone required both nitrogen and carbon sources and was inhibited by cycloheximide. The induction by the pheromone of sexual agglutinability was much more sensitive to osmotic shock and Triton X-100 in T55s-41 than in H1-0, an inducible a strain found in our stock cultures. When cultured at 22°C both T55s-41 and T562s-161 produced respective agglutination substances without the sex pheromones.H1-0 carried more than one genes responsible for the inducibility (inducible genes). The inducible genes carried by T55s-41 and T562s-161 were recessive, possibly linked to none of the mating type locus, thr4 and his 4, and shown to be identical. The inducible gene in H22, an inducible a strain found in our stock cultures and at least one of the inducible genes in H1-0 were linked to the mating type locus. All the inducible genes observed so far were not specific to the mating type in their action.     

Functional analysis of the Hikeshi-like protein and its interaction with HSP70 in Arabidopsis

Heat shock proteins (HSPs) refold damaged proteins and are an essential component of the heat shock response. Previously, the 70 kDa heat shock protein (HSP70) has been reported to translocate into the nucleus in a heat-dependent manner in many organisms. In humans, the heat-induced translocation of HSP70 requires the nuclear carrier protein Hikeshi. In the Arabidopsis genome, only one gene encodes a protein with high homology to Hikeshi, and we named this homolog Hikeshi-like (HKL) protein. In this study, we show that two Arabidopsis HSP70 isoforms accumulate in the nucleus in response to heat shock and that HKL interacts with these HSP70s. Our histochemical analysis revealed that HKL is predominantly expressed in meristematic tissues, suggesting the potential importance of HKL during cell division in Arabidopsis. In addition, we show that HKL regulates HSP70 localization, and HKL overexpression conferred thermotolerance to transgenic Arabidopsis plants. Our results suggest that HKL plays a positive role in the thermotolerance of Arabidopsis plants and cooperatively interacts with HSP70.     

Regulation of steroid hormone biosynthesis enzymes and organic anion transporters by forskolin and DHEA-S treatment in adrenocortical cells

Several important physiological functions are regulated by cortisol. Previously, we demonstrated the involvement of human organic anion transporter 3 (hOAT3) in cortisol release. In the present study, we investigated the influence of dehydroepiandrosterone sulfate (DHEA-S) and estrone sulfate on cortisol release in a human adrenocortical cell line (NCI-H295R) compared with forskolin stimulation. Additionally, we examined the impact of forskolin and DHEA-S on the expression of key enzymes in steroid biosynthesis and expression of hOAT3 and -4 in NCI-H295R cells. The cortisol release was increased 10-fold after 24-h incubation with DHEA-S, but incubation with estrone sulfate did not show any significant change in cortisol release. When cells were incubated with DHEA-S in the presence of forskolin, an additive influence of DHEA-S stimulation of cortisol was recorded over forskolin alone. The 24-h stimulation of NCI-H295R cells with forskolin increased the expression of steroidogenic acute regulatory protein (StAR), CYP17, CYP21A2, and CYP11A1, whereas only StAR mRNA expression was increased significantly by incubation with DHEA-S. Immunofluorescence analyses revealed strongly elevated expression of hOAT3 by forskolin as well as by DHEA-S stimulation. We conclude that the increased cortisol release of adrenocortical cells by DHEA-S and forskolin stimulation is probably due to high expression of the key enzymes of steroid biosynthesis and hOAT3.     

The sexual agglutination substance is secreted through the yeast secretory pathway in Saccharomyces cerevisiae

Summary A Saccharomyces cerevisiae a strain carrying the secretory mutation sec1, sec7 or sec18 showed no sexual agglutination ability when treated with pheromone at the restrictive temperature 36° C, although the a agglutination substance had accumulated in the cytoplasm. These cells became sexually agglutinable, with a concomitant decrease in the agglutination substance in the cytoplasm, when the temperature was shifted from 36° C down to the permissive temperature 24° C after the addition of, cycloheximide. The a agglutination substance was barely detectable in sec53 cells (a) treated with pheromone at 36° C, indicating that the active a agglutination substance was formed after the export of its precursor into the endoplasmic reticulum. These results indicate that the a agglutination substance is exported through the yeast secretory pathway and that pheromone acts at the level of synthesis of the precursor molecule of the substance. An strain carrying sec1, sec7 or sec18 behaved just like an a strain carrying the sec gene in the induction of agglutination ability by the opposite mating type sex pheromone.     

Promotion of sporulation by caffeine pretreatment in Saccharomyces cerevisiae

Changes in RNase activity during sporulation of a homothallic diploid strain of Saccharomyces cerevisiae were measured in caffeine-treated and non-treated cells.

MOLECULAR ANALYSIS OF THE ALLELES OF ALCOHOL DEHYDROGENASE ALONG A CLINE IN DROSOPHILA MELANOGASTER. I. MAINE,NORTH CAROLINA,AND FLORIDA

Clinal variation in natural populations is often assumed to be due to the operation of natural selection. However, for many clines there exist plausible neutralist explanations which suggest that aspects of population structure maintain differences among subpopulations for particular traits. We used a restriction-mapping technique to investigate the contributions of population subdivision and selection to the maintenance of the allozyme polymorphism at the alcohol dehydrogenase (Adh) locus of Drosophila melanogaster. Digestions of genomic DNAs from 270 lines of flies by seven enzymes reveal 15–20% of all possible nucleotide substitutions and virtually all of the insertion/deletion variation in a 2.7-kilobase region containing the Adh structural locus. Analysis of large samples from each of three populations along the east coast of the United States provides evidence of founder effects in the most northerly population. Although there are signs of population differentiation among the samples, similarities between two of the populations indicate that migration among populations is extensive and strengthen the argument that natural selection plays a role in maintaining the cline.     

Anxiolytic effect of motilin and reversal with GM-109, a motilin antagonist, in mice

There have been few reports on the effects of the brain-gut peptide motilin on the central nervous system (CNS). We administered motilin intracerebroventricularly to mice and investigated the effect of motilin on anxiety using an elevated plus-maze. Motilin produced a significant decrease in anxiety with an inverted U-shaped dose response. To determine whether the anxiolytic effect of motilin was mediated via motilin receptors in the brain, the effect of GM-109, a novel motilin receptor antagonist, was investigated. GM-109 showed a significant and dose-dependent antagonism on the motilin-induced anxiolytic effect. GM-109 administered alone had no effect on anxiety. These results suggest that motilin receptors are present in the brain and may have a role in anxiety and emotion.