An Na+/H+ antiporter gene from wheat plays an important role in stress tolerance.

A vacuole Na+/H+ antiporter gene TaNHX2 was obtained by screening the wheat cDNA library and by the 5'-RACE method. The expression of TaNHX2 was induced in roots and leaves by treatment with NaCl, polyethylene glycol (PEG), cold and abscisic acid (ABA). When expressed in a yeast mutant (deltanhx1), TaNHX2 suppressed the salt sensitivity of the mutant,which was deficient in vacuolar Na+/H+ antiporter, and caused partial recovery of growth of delta nhx1 in NaCl and LiCl media. The survival rate of yeast cells was improved by overexpressing the TaNHX2 gene under NaCl, KCl, sorbitol and freezing stresses when compared with the control. The results imply that TaNHX2 might play an important role in salt and osmotic stress tolerance in plant cells.

Ureases display biological effects independent of enzymatic activity: Is there a connection to diseases caused by urease-producing bacteria?

Ureases are enzymes from plants, fungi and bacteria that catalyze the hydrolysis of urea to form ammonia and carbon dioxide. While fungal and plant ureases are homo-oligomers of 90-kDa subunits, bacterial ureases are multimers of two or three subunit complexes. We showed that some isoforms of jack bean urease, canatoxin and the classical urease, bind to glycoconjugates and induce platelet aggregation. Canatoxin also promotes release of histamine from mast cells, insulin from pancreatic cells and neurotransmitters from brain synaptosomes. In vivo it induces rat paw edema and neutrophil chemotaxis. These effects are independent of ureolytic activity and require activation of eicosanoid metabolism and calcium channels. Helicobacter pylori, a Gram-negative bacterium that colonizes the human stomach mucosa, causes gastric ulcers and cancer by a mechanism that is not understood. H. pylori produces factors that damage gastric epithelial cells, such as the vacuolating cytotoxin VacA, the cytotoxin-associated protein CagA, and a urease (up to 10 percent of bacterial protein) that neutralizes the acidic medium permitting its survival in the stomach. H. pylori whole cells or extracts of its water-soluble proteins promote inflammation, activate neutrophils and induce the release of cytokines. In this paper we review data from the literature suggesting that H. pylori urease displays many of the biological activities observed for jack bean ureases and show that bacterial ureases have a secretagogue effect modulated by eicosanoid metabolites through lipoxygenase pathways. These findings could be relevant to the elucidation of the role of urease in the pathogenesis of the gastrointestinal disease caused by H. pylori.

Bemnisia tabaci feeding induces pathogenesis-related proteins in cassava (Manihot esculenta Crantz).

Cassava (Manihot esculenta Cranzts) plants fed upon by whitefly Bemisia tabaci showed increased levels of pathogenesis-related (PR) proteins, such as beta-1, 3-glucanase, peroxidase and chitinase activities, as compared to uninfested plants. The enzymes increased in specific activities from 2 to 7 fold and protein content in leaf extracts decreased in whitefly-infested plants, compared to uninfested plants. Among the three PR proteins, B. tabaci feeding induced significantly higher beta-1, 3-glucanase activities, when compared with other two PR proteins. Study also discussed the possible application of PR proteins in whitefly control program.

Intraspecific strains of Pythium aphanidermatum induced disease resistance in ginger and response of host proteins.

Intraspecific strains of Pythium aphanidermatum induced resistance in ginger against rhizome rot and activated biosynthesis of selected host proteins. Pre-inoculation of plants with IR strain (avirulent) or co-inoculation with SR2 (virulent) caused significant reduction in disease severity. Analysis of protein profiles of ginger leaves of inoculated and non-inoculated plants by SDS-PAGE and Image Master VDS-ID Gel Analysis version : 3.0 revealed that some specific defence proteins/stress proteins increased in inoculated plants. Five such proteins having molecular weight 56, 32, 27, 18 and 14 kDa were detected in leaves of plant treated with IR + SR2 strains. On the contrary, mycelial protein profiles and submerged growth of strains were studied separately and together. Mycelia of IR, SR2 and IR + SR2 exhibited 26, 23 and 25 protein bands, respectively although, 21 bands were common between IR and SR2. Growth of SR2 in synthetic medium was much higher than that of IR, but the growth of two strains together was lower than SR2 alone. To characterise strains, their differential growth response to DL-beta-aminobutyric acid (BABA), a known defence activator of ginger was also tested. Results suggested that at least 5 specific defence proteins/stress proteins were involved in microbially induced resistance in ginger and inducer strains were distinct in their specific protein profiles and sensitivity to BABA.

Nutrient enrichment of cassava peels using a mixed culture of Saccharomyces cerevisae and Lactobacillus spp solid media fermentation techniques

Cassava pulp was fermented with pure strains of Saccharomyces cerevisae and two bacteria namely Lactobacillus delbruckii and Lactobacillus coryneformis for 3 days. The squeezed liquid from the fermented pulp was used to ferment cassava peels for 7 days. Analysis of the dried fermented peels revealed that there was a significant (P < 0.05) increase in the protein content of the cassava peels fermented with squeezed liquid from the inoculated cassava pulp (21.5%) when compared with the unfermented cassava peel (8.2%). Moreover, the treatment equally brought about a significant (P < 0.05) decrease in the cyanide (6.2 mg/kg) and phytate content (789.7 mg/100g) when compared with the unfermented cassava peels, which had 44.6 mg/kg cyanide and 1043.6 mg/100g phytate. The fermented cassava peels could be a good protein source in livestock feeds.

Expression of a ribosome inactivating protein (curcin 2) in Jatropha curcas is induced by stress.

The open reading frame (ORF) encoding curcin 2 was cloned from total genomic and cDNA of Jatropha curcas leaves, which were treated by drought, temperature stress and fungal infection, by polymerase chain reaction (PCR) and reverse transcriptase (RT)-PCR amplification. The ORF has 927 bp that encodes a precursor protein of 309 amino acid residues. There are high similarities with curcin and the conserved domain of ribosome inactivating proteins (RIPs). Antiserum to curcin recognized one band of 32 kDa on Western blot of the leaves treated by temperature stresses at 4 degree C and 50 degree C and by fungal infections of Pestalotia funerea, Curvularia lunata (Walk) Boed, Gibberelle zeae (Schw.) Petch. Two bands of 32 kDa and 65 kDa were recognized on Western blot of the leaves treated by 10--40 percent polyethylene glycol (PEG). In addition, the 32 kDa band is nearly the molecular weight of curcin 2. This finding suggests that the protein of 32 kDa should be related to curcin 2. The presence of this protein molecular marker under stresses may provide an experimental foundation to study the stress proteins in J. curcas.

Micropropagation of Clerodendrum aculeatum through adventitious shoot induction and production of consistent amount of virus resistance inducing protein.

Rapid micropropagation through adventitious shoot induction from in vitro raised leaf explants of Clerodendrum aculeatum (Verbenaceae), was successfully achieved for the first time. Basal portion of the leaves showed highest regeneration potential when grown on MS medium supplemented with BA (5.0 mg/l) and NAA and IBA (0.5 mg/l of each). Shoots after elongation in growth regulator-free medium, were rooted in MS medium containing 0.5 mg/l of NAA and IBA. Aqueous leaf extract of in vitro raised plants, induced high degree of resistance against viruses in susceptible healthy hosts when applied prior to virus inoculation. Upon purification from leaves of cultured plants, the resistance inducing protein, showed molecular mass of 34 kDa. Amount of resistance inducing protein obtained from leaves of cultured plants, was consistent throughout the year, as compared to the protein isolated from leaves of field grown plants, which showed marked seasonal fluctuation. The purified 34 kDa protein from in vitro raised plants, was serologically related to field grown plants and possessed similar characteristics. The micropropagated plants were successfully established in earthen pots under greenhouse conditions.

Ebony (Phitecellobium flexicaule Benth) and proteins fractionation, solubilization, characterization and production of an isolate

Different combinations of pHs (2 to 12) and temperatures (25, 30 and 35 degrees C) were tested to obtain a protein isolate from ebony (Pithecellobium flexicaule, Benth) seeds. Seed proteins contained 54.6 per cent albumins, 32 per cent globulins, 5.7 per cent glutelins and 1.3 per cent prolamins. The isoelectric points for albumins, globulins and glutelins were in the pH range of 2.3-2.7. The average molecular weight of albumins ranged from 92 to 100 kDa and for the four globulin subunits in the range of 28.4 to 57.3 kDa. For isolate production, proteins were sequentially extracted with distilled water and a 5 per cent NaCl solution. The resulting supernatants were mixed. The best extraction was achieved at pH 11 and 25 degrees C. 45.6 per cent of the total seed protein was precipitated at pH 2.6 yielding an isolate with 90 per cent protein (N x 6.25). The isolate contained high quantities of lysine, leucine, threonine and phenylalanine but were low in sulfur containing amino acids methionine and cysteine. The extraction process reduced tannins, phytates and trypsin inhibitor in 53, 70 and 70 per cent, respectively. In vivo protein digestibility of the protein isolate was 85.4 per cent and the corrected digestibility essential amino acid score was of 44 per cent due to the lack of sulfur containing amino acids. In order to upgrade the protein quality of ebony isolate it is recommend to supplement with methionine or sulfur containing rich foods.

Enhancement of polygalacturonase activity during auxin induced para nodulation and endorhizosphere colonization of Azospirillum in rice roots.

Effect of different auxins, namely, 2,4-dichlorophenoxyacetic acid (2,4-D), naphthalene acetic acid (NAA) and indole acetic acid (IAA) and Azospirillum brasilense bioinoculation on the enhancement of polygalacturonase (PG) activity in rice roots during para nodulation and endorhizosphere colonization of Azospirillum was studied under in vitro condition. It was observed that Azospirillum bioinoculation could augment PG activity of rice roots to a lesser extent without any root morphogenesis whereas auxin application together with Azospirillum bioinoculation enhanced PG activity of rice roots to a higher level which resulted in better root morphogenesis (para nodule) and endorhizosphere colonisation of A. brasilense. Among the three auxins tested, 2,4-D, even at lower concentration (0.5 ppm) enhanced the rice root PG activity, root morphogenesis and endorhizosphere colonization of Azospirillum while it was 2.0 ppm with NAA and variable with IAA. It is concluded that there is a positive correlation existing among PG activity, degree of root morphogenesis and endorhizosphere colonization of Azospirillum brasilense in rice roots and the degree of correlation is determined by the chemical composition, concentration and mode of action of the auxin utilised.

Regulation of hordein synthesis in barley high lysine mutant Notch-2.

Genomic DNA isolated from barley cv. NP 113 and its high lysine mutant Notch-2, and restricted with different restriction enzymes was hybridized with B1 and C-hordein DNA probes. Similar Southern hybridization patterns were observed between NP 113 and Notch-2. Dot blot hybridization analysis of RNA isolated at different developmental stages and from different tissues of seed showed temporal as well as tissue specific expression. The results obtained indicate that regulation at the level of transcription/post transcription may be responsible for lower accumulation of hordein in mutant Notch-2.