In vitro characterization of salt stress effects and the selection of salt tolerant plants in rice (Oryza sativa L.)

Summary The response of plant cells to salt stress was studied on embryo derived calli of rice (Oryza sativa L.) in order to identify cellular phenotypes associated with the stress. The feasability of selecting salt tolerant callus and its subsequent regeneration to plants was also studied. Callus was grown on agar-solidified media containing 0%, 1% and 2% (w/v) NaCl for 24 days. Parameters such as fresh weight, dry weight, soluble protein and proline content were measured. The callus growth decreased markedly with increasing NaCl concentration in the medium. The proline content was enhanced several fold in salt stressed calli. A prolonged exposure of callus to the salt environment led to discolouration and arrested growth in the majority of the calli and only a small number of callus cells maintained healthy and stable growth. These variants were subcultured every three weeks for a period of four months onto medium containing 1% NaCl to identify tolerant lines. At the end of the third cell passage, the tolerant calli were transferred to regeneration medium to regenerate plants. The regeneration frequency in the salt-selected lines was enhanced when compared to unselected lines.     

Harijans and Girijans of Andhra Pradesh: an application of analysis of variance in the study of fertility,mortality and family planning

Research on the Bagatha tribe and the Malas and Madigas in India has been done for economic and social planning purposes in regard to family planning. Bagatha are mostly agricultural people where the nuclear family is prevalent and polygamy is popular as well as cousin marriage. The Madigas and Males (Harijans) are lower caste with the 1st being leather workers and the latter being agricultural helpers. The data was collected by direct interview of 202 tribesmen and 202 caste households with women from 15-49 years of age. The data collected on fertility include live births, child survival rate, fetal wastage, husband and wives education, income, and occupations. On mortality, the number of deaths, age at marriage, number of and intervals of pregnancies. As expected, educated and employed families show healthier and higher levels of fertility especially if the wife is educated. The wife shows more of the responsibility for family planning. The age at marriage and the number of pregnancies appears to have little effect on mortality. In the caste group the education level of the husband has little effect on fertility and again the wife has the primary responsibility in using family planning techniques.     

Contextual constraints on codon pair usage: structural and biological implications

Complementary DNA sequence data of 278 protein coding genes from prokaryotic systems have been analysed at the level of near neighbour codon pairs. Our analysis points out that constraints exist even at the level of near neighbour codon pairs. These constraints are in addition to those which arise due to relative levels of tRNA. Codon pairs, which in the data base have different occurrence values from their expected values, neither have common secondary structure nor do have better stabilization due to high base stacking. Our study points out that there are strong interaction between constituent codons in these codon pairs. These strongly interacting codon pairs, we suggest, are involved in the formation of three dimensional structural elements of cDNA/mRNA and interact with ribosome and thus modulate translation.     

Construction of a new yeast cloning vector containing autonomous replication sequences from Candida utilis.

DNA sequences from the Candida utilis genome which, when cloned into a yeast integration plasmid (YIp5), confer on YIp5 the ability to replicate autonomously in Saccharomyces cerevisiae are described. Several recombinant plasmids which transform S. cerevisiae YNN27 to Ura3+ with an efficiency of 2 X 10(3) transformants per microgram of DNA were obtained. One of the recombinant plasmids, pHMR22 (6.6 kilobases) contains ars (autonomous replication sequence), which is homologous with two different DNA fragments of the C. utilis genome but has no detectable homology to total DNA from Candida albicans, Pachysolen tannophilus, or S. cerevisiae. Restriction and subcloning analyses of pHMR22 showed that Sau3A destroys the functions of cloned ars whereas there are no BamHI, PstI, SalI, HindIII, EcoRI, or PvuII sites in the region of ars which is required for its functional integrity. Thus, pHMR22 appears to be a useful vector for cloning desired genes in S. cerevisiae.     

Productivity and nutrient uptake of water hyacinth,Eichhornia crassipes I. Effect of nitrogen source

Water hyacinth,Eichhornia crassipes, growth and nutrient uptake rates, as influenced by different N sources and N transformations, were measured using microcosm aquaculture systems. Net productivity was highest in the system receiving equal amounts of NH₄ ⁺ and NO₃ ^- (at 10 mg N 1^-1 each) and decreased in the order of NO₃ ^-, NH₄ ⁺, urea (added at 20 mg N 1^-1 each), and methane digestor effluent (at 6 mg N 1^-1). During the first 7-wk study (average ambient air temperature was 26–28°C), biomass yields were in the range of 19–53 g dry wt m^-2 day^-1, while between the 8th and 12th wk (average ambient air temperature was 16–22°C), biomass yields were in the range of 10–33 g dry wt m^-2 day^-1. In the systems with either NH₄ ⁺ or NO₃ ^-, or both added in equal proportions, about 14–20% of the total yield was contributed by roots, whereas in the system with urea and digestor effluent, roots contributed about 23 and 44% of the total yield, respectively. Nitrogen and P uptake per unit area followed trends similar to biomass yields. Nitrogen uptake rates were in the range of 533–2, 161 mg N m^-2 day^-1 for the systems receiving NH₄ ⁺, NO₃ ^-, and urea, while uptake rates were in the range of 124–602 mg N m^-2 day^-1 for the system receiving methane digestor effluent. Phosphorus uptake rates were found to be in the range of 59–542 mg P m^-2 day^-1. Under the most favorable conditions, maximum recorded biomass yield was 53 g dry wt m^-2 day^-1, with N and P removal rate of 2,161 mg N m^-2 day^-1 and 542 mg P m^-2 day^-1, indicating the potential of water hyacinth to produce large amounts of biomass which can be potentially used as a feedstock to produce methane.     

The role of cardiolipin as an acyl donor in dog heart N-acylethanolamine phospholipid biosynthesis

N-Acylethanolamine phospholipids were produced from endogenous substrates with dog heart mitochondrial and microsomal preparations. With mitochondria the N-acyl group contained 13.8% linoleate, with microsomes only 3.6%. Cardiolipin comprised 18.5% of mitochondrial and 3.3% of microsomal lipid P and contained 93.7 and 72.4% linoleic acid, respectively. Incubation of dog heart subcellular fractions with [1-14C]linoleoyl cardiolipin in the presence of Ca2+ resulted in the formation of N-acylethanolamine phospholipids labeled primarily in the N-acyl and 1-O-acyl moieties. The data indicate that cardiolipin is the major source of linoleic acid used in the N-acylation of ethanolamine phospholipids by transacylase activity.     

Isolation and functional characterization of hydrocarbon emulsifying and solubilizing factors produced by a Pseudomonas species

Pseudomonas PG-1 cultivated on pristane produced in good amount a heat-stable polymeric substance which showed strong hydrocarbon emulsifying and solubilizing properties. The substance was isolated in crude form and was found to contain 34% protein, 16% carbohydrate, and 40% lipid. The hydrocarbon solubilizing activity of the isolate was strongly inhibited by EDTA but the chelating agent had no effect on the hydrocarbon emulsifying activity. Both activities of the isolate were strongly inhibited by chymotrypsin treatment indicating the importance of the protein moiety for its activity. Hydrocarbon solubilization by the isolate showed a certain degree of specificity to pristane in modest agitation generally used in microbial cultivation, but this specificity was lost by vigorous agitation in a Waring blender. It was proposed that in the first case, solubilization was effected by a solubilizing factor specific to pristane, whereas in the latter case, nonspecific solubilization occurred due to the action of the emulsifying factor. The rate of pristane solubilization by heat-treated culture broth under the conditions of agitation used in cultivation (rotary shaker, 120 rpm) was found to be ca. 750 mg L(-1) h(-1) which was much larger than the maximal pristane uptake rate of 170 mg L(-1) h(-1) observed during microbial growth on the substrate. It was concluded that hydrocarbon solubilization could satisfactorily account for the substrate uptake and growth.