Salinity tolerance in different cultivars of barley (Hordeum vulgare L.)

Seven barley(Hordeum vulgäre L.) cultivars tested varied greatly in their responses to root medium salinity (electrical conductivity of 3, 5, 10, 15 and 20 dS nr^-1)-lant growth was relatively more adversely affected than seed germination. Dry/fresh mass ratio increased at higher salinity levels in all barley cultivars indicating reduced water uptake. Higher K/Na ratio in plant shoots compared to that in the root medium solution indicated selective uptake of K that seems to be among processes involved in tolerance of cultivars to salinity stress.     

Spatial Genetic Structure of the Abundant and Widespread Peatmoss Sphagnum magellanicum Brid.

Spore-producing organisms have small dispersal units enabling them to become widespread across continents. However, barriers to gene flow and cryptic speciation may exist. The common, haploid peatmoss Sphagnum magellanicum occurs in both the Northern and Southern hemisphere, and is commonly used as a model in studies of peatland ecology and peatmoss physiology. Even though it will likely act as a rich source in functional genomics studies in years to come, surprisingly little is known about levels of genetic variability and structuring in this species. Here, we assess for the first time how genetic variation in S. magellanicum is spatially structured across its full distribution range (Northern Hemisphere and South America). The morphologically similar species S. alaskense was included for comparison. In total, 195 plants were genotyped at 15 microsatellite loci. Sequences from two plastid loci (trnG and trnL) were obtained from 30 samples. Our results show that S. alaskense and almost all plants of S. magellanicum in the northern Pacific area are diploids and share the same gene pool. Haploid plants occur in South America, Europe, eastern North America, western North America, and southern Asia, and five genetically differentiated groups with different distribution ranges were found. Our results indicate that S. magellanicum consists of several distinct genetic groups, seemingly with little or no gene flow among them. Noteworthy, the geographical separation of diploids and haploids is strikingly similar to patterns found within other haploid Sphagnum species spanning the Northern Hemisphere. Our results confirm a genetic division between the Beringian and the Atlantic that seems to be a general pattern in Sphagnum taxa. The pattern of strong genetic population structuring throughout the distribution range of morphologically similar plants need to be considered in future functional genomic studies of S. magellanicum.     

The congenital cataract-causing mutations P20R and A171T are associated with important changes in the amyloidogenic feature,structure and chaperone-like activity of human αB-crystallin

Cataract is the major reason for human blindness worldwide. α-Crystallin, as a key chaperone of eye lenses, keeps the lenticular tissues in its transparent state over time. In this study, cataract-causing familial mutations, P20R and A171T, were introduced in CRYАB gene. After successful expression in Escherichia coli and subsequent purification, the recombinant proteins were subjected to extensive structural and functional analyses using various spectroscopic techniques, gel electrophoresis, and electron microscopy. The results of fluorescence and Raman assessments suggest important but discreet conformational changes in human αB-Cry upon these cataractogenic mutations. Furthermore, the mutant proteins exhibited significant secondary structural alteration as revealed by FTIR and Raman spectroscopy. An increase in conformational stability was seen in the human αB-Cry bearing these congenital cataractogenic mutations. The oligomeric size distribution and chaperone-like activity of human αB-Cry were significantly altered by these mutations. The P20R mutant protein was observed to loose most of the chaperone-like activity. Finally, these cataractogenic mutant proteins exhibited an increased propensity to form the amyloid fibrils when incubated under environmental stress. Overall, the structural and functional changes in mutated human αB-Cry proteins can shed light on the pathogenic development of congenital cataracts.     

Evaluation of the in vitro production of interferon gamma and other lymphokines in uremic patients

It has been suggested that a deficient immune response can be responsible at least partially for the high risk of infections and neoplasia in uremic patients. Since interferon (IFN) is critical to the immune response, we have evaluated the in vitro production of IFN-gamma and other lymphokines by peripheral blood mononuclear cells (PBMC) drawn from patients with end-stage renal disease and appropriate controls. We have correlated production of lymphokines by these cells with proliferative response to different mitogens. It was found that the secretion of IFN-gamma in response to all three mitogens was elevated in these patients compared with the control group. This elevation was significant with both phytohemagglutin and staphylococcal enterotoxin A, but not with Con A. No significant difference was observed in production of lymphotoxins, IL-2, and leukocyte migration inhibition responses. In contrast the proliferative response appeared diminished in the PBMC of uremic patients. We concluded that defective lymphokine generation is not a major immunological problem in patients with end-stage renal disease. Indeed, they appear to release excess amount of IFN-gamma which is known to be a macrophage-activating factor. It is suggested that high IFN-gamma activity could enhance the secretion of IL-1 or endogenous pyrogen and result in development of febrile reactions in dialysis patients.     

The interaction and photolabeling of myosin subfragment 1 with 3'(2')-O-(4-benzoyl)benzoyladenosine 5'-triphosphate

The photoprobe 3'(2')-O-(4-benzoyl)benzoyladenosine 5'-triphosphate (Bz2ATP) was used to characterize the nucleotide-binding site of myosin subfragment 1 (SF1). Improved synthesis and purification of Bz2ATP are reported. 1H NMR and ultraviolet spectroscopy show that Bz2ATP is a 60:40 mixture of the 3'(2')-ribose isomers and that the epsilon M261 is 41,000 M-1 cm-1. Bz2ATP is hydrolyzed by SF1 comparably to ATP in the presence of actin or K+, NH4+, or Mg2+ ions; and the product, Bz2ADP, has a single binding site on SF1 (K'a = 3.0 X 10(5) M-1). [3H]Bz2ATP was photoincorporated into SF1 with concomitant loss of K+-EDTA-ATPase activity. Analysis of photolabeled SF1 showed that the three major tryptic peptides (23, 50, and 20 kDa) of the heavy chain fragment and the alkali light chains were labeled. The presence of ATP during irradiation protected only the 50-kDa peptide, indicating that the other peptides were nonspecifically labeled. If Bz2ATP was first trapped on SF1 by cross-linking the reactive thiols, SH1 and SH2, with p-phenylenedimaleimide, only the 50-kDa tryptic peptide was labeled. These results confirm and extend previous observations that [3H]Bz2ATP trapped on SF1 by cobalt(III) phenanthroline photolabeled the same 50-kDa peptide (Mahmood, R., and Yount, R.G. (1984) J. Biol. Chem. 259, 12956-12959). Thus, the 50-kDa peptide is labeled with or without thiol cross-linking, indicating that the relative position of SH1 and SH2 does not affect the labeling pattern.     

Response of field-grown chickpea (Cicer arietinum L.) to phosphorus fertilization for yield and nitrogen fixation

Application of phosphorus at 40, 60, 80 and 100 kg P₂O₅ ha^–1 in the presence of a uniform dressing of nitrogen (N) and potash (K₂O) each applied at 20 and 24 kg ha^–1 to chickpea (CM-88) grown in sandy loam soil in a replicated field experiment improved the nodulation response of the crop, increased its grain yield (ka ha^–1) by 18, 59, 40 and 14 percent, biomass yield (ka ha^–1) by 32, 32, 54 and 14 percent, biomass N (kg ha^–1) by 31, 48, 49, 19 percent, and biomass P (kg ha^–1) by 26, 40, 41 and 11 percent, respectively. The effect of phosphorus on the nitrogenase activity of the excised roots of chickpea was, however, inconsistent.     

The effect of beta-estradiol, progesterone and testosterone on the production of human leukocyte derived interferons

Sex hormones including estrogens, progesterone and testosterones are known to have adverse effects on the immune system and particularly on the proliferative response. Since cytokine production is known to be dissociable from the proliferation of lymphocytes and since other steroid hormones profoundly affect cytokine production, we felt it would be important to know the effect of sex steroids on the production of interferons (IFN), particularly since the latter are known to be key substances in the immune response. We have shown estradiol can slightly reduce gamma IFN yields with certain inducers (Con A, SEA) but only in pharmacologic concentrations. Similarly, progesterone had a modest effect in the same concentrations but only when Con A was the inducer. Testosterone did not effect IFN titers at any concentration. None of the sex steroids affected alpha IFN production and none of them influenced the bioactivity of either IFN species. In all cases these hormones diminished proliferative responses as has been previously noted.     

Associative N2-fixation in plants growing in saline sodic soils and its relative quantification based on15N natural abundance

The interactive effect of low P supply (0, 10, 20 and 40 M) and plant age on nodule number, mass and functioning (ureide analysis technique), vegetative growth and pod production were investigated in glasshouse-grown nodulated cowpea (Vigna unguiculata L.cv. Kausband) in sand culture. Compared with 40 M P, P stress (0 M P) or very low (10 M P) supply markedly impaired nodulation, allantoin and amino-N concentrations and weight of N solutes in xylem exudates. Consequently, P stress reduced top growth and pod yields by 48 and 90%, respectively. N solutes in xylem exudates and total plant N assayed by Kjeldahl technique (as estimates of N₂ fixation) responded similarly to P supply. However, the relative ureide index [(ureide-N/ureide N+amino-N)×100] remained constant (99%), irrespective of P supply, indicating the plants' complete dependency on symbiosis for growth, without implying that growth was markedly increased by N₂ fixation. Although P concentrations in plant tops, roots and nodules increased with P supply, N concentrations in these plant tissues were unaffected by P supply. The concentrations of N and P in the nodules were 2–2 1/2 times higher than in plant tops. P application interacted strongly with plant age, with the largest P effect evidently achieved at the early podding stage. The significance and implications of these results are discussed.