Rice chloroplast RNA polymerase genes: The absence of an intron in rpoC1 and the presence of an extra sequence in rpoC2

Summary The chloroplast genome contains sequences homologous to the Escherichia coli rpoA, rpoB and rpoC genes. The Choroplast rpoC gene is divided into rpoC1 and rpoC2, of which rpoC1 contains an intron. Comparison of the rice rpo genes with those from tobacco, spinach and liverwort revealed unique features of the rice genes; the lack of an intron in rpoC1 and the presence of an extra sequence of 381 by in rpoC2. The intron in rpoC1 is thus optional, and possible intron boundary sites in split rpoC1 genes can be estimated by comparison with rice rpoC1. The extra sequence is located in the middle of rpoC2 and has repeated structures. The amino acid sequence deduced from this sequence is extremely hydrophilic and anionic. The origin and function of this sequence are discussed.     

Detection of mRNAs correlated with proliferation of cells in suspension cultures of Catharanthus roseus

Gene expression correlated with proliferation was investigated in Catharanthus roseus (L.) G. Don. cells. Polyadenylated RNAs were isolated from cells in proliferative states or in nonproliferative states and the variations in the population and levels of mRNA were analyzed by in vitro translation followed by separation of the corresponding polypeptides by two-dimensional gel electrophoresis. Levels of two mRNAs increased in the actively cycling cells, while they were hardly detected in cells in stationary phase or in cells arrested by starvation of phosphate, sucrose or nitrogen. The molecular masses of the translated products of these two mRNAs were 53 and 60 kDa. No mRNAs were specifically synthesized in common among the various cultures of cells whose growth was arrested by nutrient starvation.     

Stored mRNA in cotyledons of Vigna unguiculata seeds: nucleotide sequence of cloned cDNA for a stored mRNA and induction of its synthesis by precocious germination

By differential hybridization screening, we previously selected a class of cDNA clones from a gt10 cDNA library that was constructed from the total poly(A)⁺ RNA of mature cowpea cotyledons (Plant Cell Physiol 31: 39–44, 1990). pSAS10, a clone of this class, hybridized with a cDNA probe complementary to poly(A)⁺ RNA from cotyledons collected 1 day after the onset of imbibition (DAI), but not with the cDNA probe from cotyledons at development stage II (13 to 15 days after flowering, DAF). pSAS10 mRNA was detectable only in cotyledons at development stage III (17 to 19 DAF) or later, and its level began to decline when seeds germinated. We have suggested that pSAS10 mRNA is likely to belong to the class of stored mRNA or the mRNA that is formed at the late stage of seed maturation, is conserved in quiescent seeds and becomes functional at the early stage of germination. We determined the nucleotide sequence of pSAS10 cDNA consisting of 459 bp and an approximately 36 bp poly(A) tract, and deduced the amino acid sequence of its product, a 10-kDa cysteine-rich polypeptide. Synthesis of pSAS10 mRNA was induced just before germination began, not only in mature seeds but also in immature seeds even at stages I (9 to 11 DAF) and II (13 to 15 DAF) if they were placed under conditions suitable for germination.     

The recQ gene of Escherichia coli K12: molecular cloning and isolation of insertion mutants

Summary The recQ gene of Escherichia coli K12 was subcloned from plasmid pKO1 (Oeda et al. 1981) by monitoring the capacity of the resulting recombinant plasmids partially to reverse the increased ultraviolet (UV) sensitivity of a recF143 recQ1 double mutant. We were able to trace this complementation activity to a 3.4 kilobase (kb) SalI-PvuII fragment. Furthermore, analysis of the Tn3 insertion mutations that abolished the complementation revealed the exclusive localisation of such insertions in the same 3.4 kb segment. This segment was situated about 4 kb clockwise from corA on the chromosome, a result consistent with the transductional data previously reported. In addition, a comparison of our restriction endonuclease cleavage map with the published data has placed recQ between pldA and pldB. When relocated to the recQ site on the chromosome, the recQ::Tn3 mutations conferred partial resistance to thymineless death (TLD) or, in the case of a recBC sbcB background, recombination deficiency and increased UV sensitivity. This has provided the firm evidence that both the TLD resistance and the deficiency in the RecF recombination pathway result from loss of the functional recQ gene. We also identified the recQ gene product as a 74 kilodalton polypeptide by using the maxicell technique.Abbreviations TLD thymineless death - UV ultraviolet light - Ap ampicillin - Km kanamycin - Sm streptomycin - Tc tetracycline - ^r resistant - ^s sensitive - kb kilobase - kdal kilodalton     

Enhanced synthesis and secretion of apolipoprotein E from sciatic nerves of streptozotocin-induced diabetic rats after injury

To elucidate the pathogenesis of diabetic neuropathy, synthesis and secretion of apolipoprotein E (apo E) from sciatic nerves after injury was studied in normal and streptozotocin-induced diabetic rats. Seven, 14, 28, 45 and 59 days after making crush injury on sciatic nerves with concomitant administration of streptozotocin (50 mg/kg body weight), the nerves were taken out and incubated with [35S]methionine. The [35S]labeled apo E was precipitated with specific antiserum. The amounts of apo E secreted into medium by nerves of diabetic rats were 7 times greater than those of non-diabetic rats 7 days after injury. This enhanced secretion of apo E was relatively selective for this protein, since the ratio of the immunoprecipitable apo E to the TCA preciptitable protein in the medium increased in diabetic rats. Intriguing possibility deduced from these results is that the secretion of apo E is involved in the development of diabetic neuropathy.     

Genetic mapping of the Escherichia coli gene for the stringent starvation protein and its dispensability for normal cell growth

Summary To determine its map position, the sSP gene was cloned into plasmid pBR322 and the recombinant plasmid was integrated into the chromosome of a polA mutant at the site of the sSP gene by homologous recombination. The chromosomal location of Amp^r was then determined by P1 phage-mediated transduction. Thus, the sSP gene was mapped between gltB and glnF at min 69.5 on the Escherichia coli chromosome. Strains were constructed in which the sSP gene was brought under the control of the lac regulatory system. This indicated that the stringent starvation protein (SSP) is dispensable for growth, at least under normal culture conditions.Abbreviations SSP stringent starvation protein - Amp^r ampicillin resistant - IPTG isopropyl -d-thiogalactopyranoside     

Seed coat anatomy ofCrossostylis (Rhizophoraceae): its evolutionary and systematic implications

The seed coat structure of all 13 species ofCrossostylis was studied to contribute to an understanding of species delimitation and relationships within the genus. The mature seed coat is relatively uniform and consistently constructed mainly by a well-developed exotesta and a well-developed fibrous exotegmen. The species differ in the thickness of the exotesta and exotegmen, the anatomy of exotestal cells, the presence and absence of persistent mesotesta, and so forth. On the basis of comparisons of these characters, close relationships are suggested in the species groups such as:Crossostylis banksiana andC. cominsii; C. biflora, C. raiateensis andC. multiflora; C. gandiflora, C. sebertii andC. imera; and five species in the Fiji Islands. These relationships except for those of Fijian five species are also supported by cladistics as their common characters are evaluated as synapomorphy. Species-level separation ofC. banksiana, C. pedunculata andC. raiateensis each from the closest species is doubted based on the results of seed coat structure.     

Effects of interspecific competition on development and reproduction in two giant water bugs,Diplonychus japonicus vuillefroy andDiplonychus major esaki (Hemiptera: Belostomatidae)

We studied the interpecific competition between 2 species of predatory aquatic bugs, Diplonychus japonicus and D. major by conducting a field experiment. We set up 3 types of experimental plots in the paddy fields where D. major predominated. The two plots contained single species of either D. japonicus or D. major, respectively, and one plot had both species in equal number. We compared the development and the reproductive performance between plots in each species. In D. japonicus, the number of eggs and early instar nymphs were significantly smaller in the plots containing both species than in the monospecific plots. However, the numbers of late instar nymphs and newly emerged adults were not significantly different between plots. The proportions of starved nymphs in both plots were larger than those in the D. japonicus's natural habitats. The final densities of adults in both plots were lower than those in the natural habitats. These results suggest that lower density of D. japonicus in these paddy fields is due to the lack of available food for nymphs rather than the effects of interspecific competition with D. major. In D. major, significant differences were not found in the number of eggs, each instar nymphs and adults. These results suggest that the effects of interspecific competition did not affect the reproductive performance of D. major.     

Isolation of three forms of cystatin from submandibular saliva of isoproterenol-treated rats, its properties and kinetic data

Three rat salivary cystatins (designated as RSC-1, RSC-2 and RSC-3) induced by chronic isoproterenol (IPR) treatment, but not detected in normal rats, were purified from submandibular saliva of chronically IPR-treated rats by Mono-Q, hydroxyapatite and TSKgel Phenyl-5PW chromatographies. Their molecular weights (Mr) and isoelectric points (pI) differed from each other as follows: RSC-1 (Mr 16,500, pI 4.4), RSC-2 (Mr 15,500, pI 4.4) and RSC-3 (Mr 14,500, pI 4.5). The amino acid compositions of these inhibitors were very similar and the three forms showed complete immunological identity in a double immunodiffusion system. The partial amino acid sequence results showed that these inhibitors belonged to family 2 of the cystatin superfamily. These three forms strongly inhibited the enzyme activities of ficin and papain, but not of cathepsin B and trypsin. The inhibition constants (Ki) of RSC-1, RSC-2 and RSC-3 for ficin were 0.19, 0.50 and 0.012 nM, and for papain were 1.5, 0.93 and 0.03 nM, respectively. RSC-3 inhibited ficin and papain more strongly than did RSC-1 and RSC-2.