Organization and nucleotide sequence of the genes for ribosomal protein S2 and elongation factor Ts in Spirulina Platensis

A 6.5 kb region from the genome of the cyanobacterium Spirulina platensis was cloned using as a probe the Escherichia coli gene for ribosomal protein S2. Sequence analysis revealed, in this region, the presence of the gene for ribosomal protein S2 and part of the gene for the elongation factor Ts (EF-Ts). The arrangement rpsB-spacer-tsf resembles that reported for E. coli. The deduced amino acid sequences of the platensis S2 and EF-Ts show significant homology with the E. coli counterparts.     

Studies on theStellaria longipes complex (Caryophyllaceae): Isozyme variability and the relationship betweenStellaria longipes andS. longifolia

Genetic variation within and the relationship betweenStellaria longipes Goldie andS. longifolia Muhl. were studied. Ten enzyme systems were assessed in eight natural populations ofS. longipes (25 loci) and three ofS. longifolia (20 loci) using starch and polyacrylamide gel electrophoresis. Patterns of population differentiation corresponded to geographic distance. There was no evidence that polyploidS. longipes had greater electrophoretic variability than diploidS. longipes. The isozyme data confirmed extensive population differentiation in these species and, within that context, a relatively close relationship betweenS. longipes andS. longifolia. It was postulated that diploids of these two species might be the progenitors of tetraploidS. longipes.     

Structure of cDNA clones for the small subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase from a fern (Asplenium cataractarum rosenstock,aspleniaceae), and its comparison with those of various seed plants

We isolated the small subunit of ribulose-1, 5-bisphosphate carboxylase/oxygenase (RuBisCO SSu) from a fern,Asplenium cataractarum and determined its 34 N-terminal amino acid sequence. We obtained a cDNA clone that contains the entire coding region of the SSu from the same fern species, using synthetic oligonucleotide probes derived from the above amino acid sequence. It contains a 525 bp open reading frame capable of coding for a polypeptide with 174 amino acids, 31 bp 5′-and 206 bp 3′-noncoding regions. It was also elucidated that the precursor to the SSu contains a transit peptide of 53 amino acid residues and a mature protein of 121 residues. We compared the deduced amino acid sequence of the fern SSu with those of 11 other vascular plant species (including gymnosperms, monocots and dicots). As low as 55% homology was observed between those of a fern and seed plants. Constancy of the amino acid substitution rate in RuBisCO SSu was supported by our relative rate test. Amino acid substitution rate per year per site for RuBisCO SSu was calculated to be 0.81×10⁻⁹ assuming that the separation between pteridophytes and seed plants arose 380 million years ago.     

Developmental appearance of the Ca2+-binding proteins parvalbumin,calbindin D-28K,S-100 proteins and calmodulin during testicular development in the rat

Summary Calcium and intracellular Ca²⁺-binding proteins are possibly involved in hormone production and spermatogenesis in rat testis. Parvalbumin, calbindin D-28K, S-100 proteins and calmodulin were localized in the Leydig cells, which are sites of testosterone synthesis. Only the appearance of parvalbumin-immunoreactivity is closely correlated to testosterone production during development of the testes. Calbindin D-28K-immunoreactivity persisted in foetal-type Leydig cells and in adult-type Leydig cells at all stages of development. S-100-immunoreactivity was low during all foetal stages, absent between birth and puberty, and increased thereafter. Calmodulin staining is most prominent in the cytoplasm of developing spermatocytes and of maturing spermatids. All four proteins co-exist in the seminiferous tubules. The distinct localization and developmental appearance of these proteins suggests different regulatory roles in Leydig cell function and spermatogenesis.     

Frequent duplication and deletion events in the 5S RNA genes and the associated spacer regions of theTriticeae

The 5 S DNA units from 15 grasses in theTriticeae were analysed at the DNA sequence level. Four units carried duplications near the 3-end of the 5 S RNA gene with 3 of the duplications centred on the same base pairs as a duplication previously reported byGerlach & Dyer. The fourth duplication was located 3 downstream from the gene, in the spacer region. Apparent deletions were very frequent when units of the different grasses were compared and it was clear that these deletions did not extend into a 75 bp spacer region upstream from the 5 S RNA gene. This 75 bp region also tended to be more conserved between the grasses as compared to the high level of sequence change in the rest of the spacer region. — Phenetic relationships were established between the grasses using the sequence data. The relationships were generally consistent with the data from other parameters and, in addition, showed that two Australian grasses were closely related to the other Northern hemisphere genera examined. The data concerning the Australian grasses is discussed in relation to the isolated nature of Australia.     

Linear and non-linear regression analysis of genotype X environment interactions in pearl millet

Summary Regression analysis was computed on the grain yield of 15 single cross F₁ hybrids of pearl millet (Pennisetum typhoides (Burm.) S. & H.) evaluated in 20 environments at 19 sites in India to assess the nature of genotype X environment interactions. Linear, quadratic, cubic, twoand three-intersecting straight line models were examined for fit. The interactions of six hybrids viz. MH 110, MH 113, MH 114, MH 115, MH 120 and MBH 110 were explained by the linear regression model. The response of the remaining nine hybrids was largely non-linear. The two and three-intersecting straight line models fit better than the quadratic and cubic models and explained non-linearity of response. The two-intersecting straight line models fit for 6 hybrids MH 106, MH 107, MH 112, MH 116, MH 117 and BJ 104. The response of MH 109 was best explained by a three-intersecting straight line model, but there still existed a significant remainder variation. The truncation of environmental range by assuming moving division points was more efficient than the fixed division points for the segmental regression models. The stability of hybrid varieties on the best fitting model has been discussed.     

Properties of the 12-O-Tetradecanoylphorbol-13-Acetate-Stimulated S6 Kinase from Rat Astroglial Cells

The S6 kinase activity of astroglial cells in primary culture stimulated by 12-O-tetradecanoylphorbol-13-acetate (TPA) has been studied. This activity was eluted as a single peak at 0.15 M NaCl from a DEAE-Sephacel column. The chromatography of this peak on phosphocellulose revealed an activity eluted at 0.15 M NaCl. This partially purified enzyme had a sedimentation coefficient of 3.7S; Km values were 2 X 10(-5) M for ATP and 10(-6) M for 40S ribosomal subunits. The optimal Mg2+ concentration requirement was 2-3 mM. Mn2+ and Co2+ could substitute for Mg2+ (optimum concentrations 1.5 and 0.8 mM, respectively), but these cations were strong inhibitors in the presence of Mg2+. The enzyme was inhibited by N-ethylmaleimide, indicating that it contained thiol groups. This S6 kinase used ATP, but not GTP, as a phosphate donor, and exhibited great specificity for S6 as phosphate acceptor. Whole histones and protamine were slightly phosphorylated whereas phosvitin, histone H1, and surprisingly the peptide Arg-Arg-Leu-Ser-Ser-Leu-Arg-Ala were not phosphorylated. The TPA-stimulated S6 kinase resembles the insulin-, fibroblast growth factor- and cyclic AMP-stimulated enzymes, suggesting that several pathways might activate the same entity.     

Unusual evolutionary conservation of 5S rRNA pseudogenes inAspergillus nidulans: Similarity of the DNA sequence associated with the pseudogenes with the mouse immunoglobulin switch region

Summary AllAspergillus nidulans 5S rRNA pseudogenes known so far are the result of integration of an approx. 0.2-kbp-long DNA sequence into the 5S rRNA genes. This sequence, called block C, is present in at least five copies in theA. nidulans genome and seems to be associated either with 5S rRNA genes or pseudogenes. In contrast to the 78% sequence conservation of the C-block in pseudogenes, the truncated 5 halves of the pseudogenes are very highly conserved (96.9–100%). We postulate that the 5S rRNA pseudogenes are still a subject of concerted evolution. The C-block sequence shows similarity to the switch region of the mouse heavy chain immunoglobulin gene. A characteristic motif GGGTGAG is repeated several times in both sequences; the sequence conservation is 63%.     

Comparative Study of Glial Marker Proteins in the Hypoplastic Cerebellum of Jaundiced Gunn Rats

The behavior of marker proteins of glial cells [alpha-enolase, beta-S100 protein, and glial fibrillary acidic protein (GFAP)] was investigated quantitatively by using enzyme immunoassay systems during the development of cerebellar hypoplasia in jaundiced Gunn rats. A neuronal marker protein, gamma-enolase, was also measured as a reference. At postnatal day 8 corresponding to the early stage of cerebellar damage, the amount of beta-S100 on a protein basis was significantly higher in jaundiced homozygotes (jj) than in control nonjaundiced heterozygotes (j+), whereas no differences in alpha- and gamma-enolases and GFAP were observed between the two groups of rats. At days 15 and 30, which correspond, respectively, to the advanced and late stages of cerebellar damage, the three glial proteins, especially GFAP, were higher and the neuronal protein was lower in the jj rat cerebellum than in the control. These results are consistent with the reported histological observations that neuronal cells are vulnerable and damaged by bilirubin, whereas glial cells seem to be less sensitive. On the other hand, the amounts of beta-S100 and alpha-enolase per cerebellum were significantly lower in jj rats at days 15 and 30, as in the case of gamma-enolase, whereas that of GFAP remained at the same level as the control at day 15 and showed a slight but significant decrease at day 30. The possibility is suggested that beta-S100 and GFAP may be available as biochemical indicators of glial cells, especially in the early and advanced stages of cerebellar damage, respectively, but that alpha-enolase is less available.