Identification of a putative RNA helicase (HRH1), a human homolog of yeast Prp22.

In the budding yeast Saccharomyces cerevisiae, a number of PRP genes known to be involved in pre-mRNA processing have been genetically identified and cloned. Three PRP genes (PRP2, PRP16, and PRP22) were shown to encode putative RNA helicases of the family of proteins with DEAH boxes. However, any such splicing factor containing the helicase motifs in vertebrates has not been identified. To identify human homologs of this family, we designed PCR primers corresponding to the highly conserved region of the DEAH box protein family and successfully amplified five cDNA fragments, using HeLa poly(A)+ RNA as a substrate. One fragment, designated HRH1 (human RNA helicase 1), is highly homologous to Prp22, which was previously shown to be involved in the release of spliced mRNAs from the spliceosomes. Expression of HRH1 in a S. cerevisiae prp22 mutant can partially rescue its temperature-sensitive phenotype. These results strongly suggest that HRH1 is a functional human homolog of the yeast Prp22 protein. Interestingly, HRH1 but not Prp22 contains an arginine- and serine-rich domain (RS domain) which is characteristic of some splicing factors, such as members of the SR protein family. We could show that HRH1 can interact in vitro and in the yeast two-hybrid system with members of the SR protein family through its RS domain. We speculate that HRH1 might be targeted to the spliceosome through this interaction.     

A seed-specific Brassica napus oleosin promoter interacts with a G-box-specific protein and may be bi-directional

Corrigendum

Upstream regulatory sequences from two -conglycinin genes     

Hypoxanthine-guanine phosphoribosyltransferase (HPRT) deficiency: Identification of point mutations in Japanese patients with Lesch-Nyhan syndrome and hereditary gout and their permanent expression in an HPRT-deficient mouse cell line

Two different single nucleotide transitions of hypoxanthine-guanine phosphoribosyltransferase (HPRT) were identified in a Japanese patient with Lesch-Nyhan syndrome (LNS) and a patient with hereditary gout. HPRT enzyme activities in the two patients were severely deficient, but the size and amount of mRNA were normal according to Northern analysis. Entire coding regions of HPRT cDNAs were amplified by PCR and sequenced. A G-to-A substitution at base 208 in exon 3, which predicted glycine 70 to arginine, was detected in the LNS patient (identical mutation with HPRT_Utrecht). A C-to-A substitution at base 73 in exon 2, which predicted proline 25 to threonine, was detected in the gout patient (designated HPRT_Yonago). We transfected normal HPRT cDNA, mutant cDNA with HRPT_Utrecht or mutant cDNA with HPRT_Yonago, respectively, to HPRT-deficient mouse cells and isolated permanent expression cell lines. The HPRT-deficient mouse cells had no detectable HPRT activity and a very low amount of HPRT mRNA. When the HPRT-deficient mouse cells were transfected with normal human cDNA, HPRT enzyme activity increased to 21.8% that of normal mouse cells. The mouse cells transfected with HPRT_Utrecht showed no increase in HPRT activity; however, when the mouse cells were transfected with HPRT_Yonago, the activity increased to 2.4% that of normal activity. The proliferative phenotypes of these cells in HAT medium and in medium containing 6-thioguanine were similar to those of skin fibroblasts from the patients. This series of studies confirmed that each of the two point mutations was responsible for the decreases in HPRT enzyme activity, and the proliferative phenotypes in HAT medium and medium containing 6-thioguanine.     

Effect of selenium and protein deficiency on selenium and glutathione peroxidase in rats

Twenty-four weanling male Wistar rats were divided into four groups fed diets containing adequate or deficient levels of selenium (0.5 ppm [+ Se] or <0.02 ppm [−Se] and protein (15% [+Pro] or 5% [−Pro]), but adequate levels of all other nutrients for 4 wk to determine the effects of Se deficiency and protein deficiency on tissue Se and glutathione peroxidase (GSHPx) activity in rats. Plasma, heart, liver, and kidney Se and GSHPx were significantly lower in Se-deficient groups in relation to Se-sufficient groups. In Se-deficient groups, Se and GSHPx were significantly higher in −Se−Pro rats in heart, liver, and kidney. Data analysis showed that there were significant interaction effects between dietary Se and protein on Se and GSHPx of rats. It is assumed that under the condition of Se deficiency. a low level of protein may decrease Se and GSHPx utilization, increase GSHPx synthesis, and result in Se redistribution. This could account for high levels of Se and GSHPx in the −Se−Pro rats compared to −Se+Pro rats.     

Presynaptic α2 Adrenoceptors Inhibit Glutamate Release from Rat Spinal Cord Synaptosomes

Abstract: The presynaptic regulation of amino acid release from nerve terminals was investigated using synaptosomes prepared from the rat spinal cord. The basal releases of endogenous glutamate (Glu), aspartate (Asp), and γ-amino-butyric acid (GABA) were 34.6, 21.5, and 10.0 pmol/min/mg of protein, respectively. Exposure to a depolarizing concentration of KCl (30 m M ) evoked 2.7-, 1.5-, and 2.9-fold increases in Glu, Asp, and GABA release, respectively. Clonidine reduced the K⁺-evoked overflow of Glu to 56% of the control overflow with a potency (IC₅₀) of 17 n M , but it did not affect K⁺-evoked overflow of Asp, GABA, and their basal releases. Similarly, noradrenaline inhibited the K⁺-evoked overflow of Glu, although phenylephrine and isoproterenol showed no effect. The inhibitory effect of clonidine was counteracted by α₂-adrenoceptor antagonists, rauwolscine, yohimbine, and idazoxan, regardless of the imidazoline structures. Because Glu is considered a neurotransmitter of primary afferents that transmit both nociceptive and nonnociceptive stimuli in the spinal cord, these data suggest that part of Glu release may be regulated by the noradrenergic system through α₂ adrenoceptors localized on the primary afferent terminals.     

Seasonal variation in the physical properties of agar and biomass of Gracilaria sp. (chorda type) from Tosa Bay,southern Japan

Plants of Gracilaria sp.(chorda type), which grow along the coast of Uranouchi Inlet in Tosa Bay, southern Japan, showed the highest biomass in the summer (26 °C to 31 °C) and spring season (15.1 °C to 24.9 °C). Maximum biomass was 6952 g m^–2 in July, but gradually decreased in the autumn (30.5 °C in September to 20 °C in November) and winter (19.5 °C in December to 14.9 °C in February). Variation in yields and gel strength of the agars, were shown to depend on the time in the season. After alkali treatment (5% NaOH, 2 h) at three different temperatures (70, 80, and 90 °C), the agars showed gel strengths essentially that of commercial grade agars, with the best gel obtained at 80 °C. Maximum gel strength (1455 g cm^–2 of 1.5% agar gel) occurred in winter when the biomass and agar yield were low. Minimum gel strength was in spring. Gel strength was inversely correlated with agar yield, but was positively correlated with apparent viscosity. Maximum viscosity was 40 cP. in December. Gelling temperatures, pH of 1.5% agar gel, and moisture content in agars showed little variation.     

Immunohistochemical Detection of Sialyl LeX Antigen on Mucosal Langerhans Cells of Human Oral Mucosa following Neuraminidase Pretreatment

Histochemical assessment of selected carbohydrate sequences on Langerhans cells of human oral mucosa was made by combined use of enzyme digestion and immunostain-ing with monoclonal antibodies against specific carbohydrate structures. In both frozen sections and epithelial sheets without the enzyme pretreatment, mucosal Langerhans cells, identified by positive staining with anti-CD1a and HLA-DR antibodies, did not express any carbohydrate antigens on their surface. In contrast, following neuraminidase pretreatment of both types of material, the fucosylated type 2 chain (Le^X) became detectable on Langerhans cells, indicating that sialic acid is the terminal residue of this sequence. Other enzymes were ineffective in this apparent unmasking, and the staining patterns of the other related carbohydrate sequences (Le^y. Le^a, Le^b) remained unaffected by pretreatment with any of the enzymes used. These findings suggest that the mucosal Langerhans cells possess a unique carbohydrate chain, the sialyl fucosylated type 2 sequence (sialyl Le^X antigen).     

Structural characterization of the dihydroflavonol 4-reductase B (DFR-B) gene in the sweet potato.

A genomic fragment containing the dihydroflavonol 4-reductase B (DFR-B) gene was cloned from the sweet potato (Ipomoea batatas) and its nucleotide sequence was analyzed. The exons and flanking regions were highly homologous to those of previously reported DFR-B genes of the Japanese morning glory, whereas the introns and the intergenic region were less conserved. In addition to the sequences of three miniature inverted-repeat transposable elements (MITEs) and one direct repeat previously reported in the DFR-B gene of Japanese morning glory, two mobile element-like sequences were newly identified in the sweet potato DFR-B gene. At least four allelic sequences were found to exist by amplification of the DFR-B gene from various sweet potato cultivars. One of these allelic sequences had a 2-kb deletion in the intergenic region and was observed in the cultivars with high anthocyanin content in their storage roots.