Genetic and physiological evidence for the production of N-acyl homoserine lactones by Pseudomonas syringae pv. syringae and other fluorescent plant pathogenic Pseudomonas species

N-acyl homoserine lactones (AHLs) function as cell density (quorum) sensing signals and regulate diverse metabolic processes in several gram negative bacteria. We report that strains of Pseudomonas syringae pvs. syringae (Pss), tabaci and tomato as well as P. corrugata and P. savastanoi produce difussible AHLs that activate the lux operons of Vibrio fischeri or the tra::lacZ fusion of Agrobacterium tumefaciens. In Pss strain B3A, AHL production occurs in cell density dependent manner. Nucleotide sequence and genetic complementation data revealed the presence of ahlI_Pss, a luxI homolog within the Ahl⁺ DNA of Pss strain B3A. The DNA expresses in AHL-deficient strains of P. fluorescens and E. carotovora subsp. carotovora (Ecc), and restores extracellular enzyme production and pathogenicity in the Ecc strain. The derivatives of Pss strains B3A and 301D carrying chromosomal ahlI::lacZ do not produce AHL, but like their wild type parents, produce extracellular protease and the phytotoxin syringomycin as well as elicit the hypersensitive reaction in tobacco leaves. While these strains also produce a basal level of -galactosidase activity, the expression of ahlI::lacZ is substantially stimulated in the presence of multiple copies of the DNA or by the addition of cell-free spent cultures containing AHL. The activation of -galactosidase production occurs with spent cultures of some, but not all Pseudomonas strains which produce AHL as indicated by the Lux and tra::lacZ assays. Pss strains deficient in the global regulatory genes, gacA or lemA, produce very low levels of AHL. Since inactivation of ahlI_Pss eliminates AHL production and since Ahl⁺ Pseudomonas strains carry the homolog of ahlI_Pss, we conclude that ahlI_Pss specifies a key step in AHL biosynthesis and it has been conserved in many plant pathogenic pseudomonads.     

Water quality affects SDH activity, protein content and RNA:DNA ratios in fish (Catla catla, Labeo rohita and Oreochromis mossambicus) raised in ponds of a sewage-fed fish farm

The spatial and seasonal variability of the respiratory enzyme succinate dehydrogenase and the protein content were examined in different tissues of fish cultured in three ponds along the effluent gradient of a sewage-fed fish farm. Indian major carp Catla catla (150-230 g) and Labeo rohita (60-190 g) cultured in both the middle and last points of the sewage effluent (stocking pond 1) and (stocking pond 4) and Oreochromis mossambicus (50-160 g), a naturally growing fish of the inlet (facultative pond) and the out let of the sewage effluent (stocking pond 4) were procured every month during the period of January-December, 2005 and were subjected to determination of succinate dehydrogenase activity, total protein, DNA and RNA contents from gill, liver and muscle tissue respectively. The SDH activity of all three test fishes (Catla catla, Labeo rohita and Oreochromis mossambicus) was reduced significantly (ANOVA; P < 0.05) when cultured in SP-4 compared to SP-1 in the case of Catla catla and Labeo rohita and in facultative pond in the case of Oreochromis mossambicus.Conspicuous differences in the SDH activity of fish between the last and first stocking pond or the facultative pond were clearly due to the result of the differences in water quality. There was a direct relationship between SDH activity in gill tissue of any of the fish investigated and ammonia-N concentration of water or water pH. This shows that the respiratory activity of these fishes was strongly affected by the ammonia and pH of water. In other words, this suggests that as the distance from the point source increases, there was a substantial improvement of water quality in the ponds located along the sewage effluent gradient. Evidently, there is a progressive pattern of growth, survival and physiological health of fish and abundance of favorable diversity of food organisms with rich biodiversity.     

Karyomorphological studies of ten strains of Indian mustard (Brassica juncea Coss.)

Summary Karyomorphological studies on ten cultivated strains of Brassica juncea Coss. (Indian mustard) have been made. All of them were found to possess 2n=36 chromosomes and meiotic studies revealed 18 regular bivalents. A great many structural differences between chromosome complements have been recorded. It has been shown that though homogeneous in gross morphology, minute structural differences between the strains are noted in relation to the number of secondary constrictions, the position of primary constrictions as well as the changes in the arm ratio. A histogram of the haploid chromatin complement of the somatic set of ten strains illustrates the differences.     

Metroglyph analysis of Indian and exotic varieties of maize

Summary Metroglyph and index score analysis was carried out with 15 Indian and 15 exotic varieties of maize currently being used in the breeding programme of the Coordinated Maize Improvement Project at the Indian Agricultural Research Institute. It was found that the Indian varieties under study fall into three morphological complexes which differed among themselves. The variability pattern of the second and third Indian complexes resembled that of Mexican and Colombian germ plasm. The variability pattern of the Caribbean germ plasm was different from the Indian complexes. Index score analysis also gave similar results. Previous breeding experiments also confirmed the findings that these varieties might have originated from a few Mexican or Colombian introductions.     

Molecular mapping of a locus controlling resistance to Albugo candida in Indian mustard

Brassica juncea (L.) Czern & Coss is widely grown as an oilseed crop in the Indian subcontinent. White rust disease caused by Albugo candida (Pers.) Kuntze is a serious disease of this crop causing considerable yield loss every year. The present study was undertaken to identify molecular markers for the locus controlling white rust resistance in a mustard accession, BEC‐144, using a set of 94 recombinant inbred lines (RILs). The screening of individual RILs using an isolate highly virulent on the popular Indian cultivar ‘Varuna’ revealed the presence of a major locus for rust resistance in BEC‐144. Based on screening of 186 decamer primers employing bulked segregant analysis (BSA), 11 random amplified polymorphic DNA markers were identified, which distinguished the parental lines and the bulks. Five of these markers showed linkage with the rust resistance locus. Two markers, OPN0_l000 and OPB06₁₀₀₀, were linked in coupling and repulsion phases at 9.9 cM and 5.5 cM, respectively, on either side of the locus. The presence of only two double recombinants in a population of 94 RILs suggested that the simultaneous use of both markers would ensure efficient transfer of the target gene in mustard breeding programmes.     

Metabolism mediated interaction of α-asarone and Acorus calamus with CYP3A4 and CYP2D6

The present study was aimed to investigate the possible interaction of the standardized extract of Acorus calamus (AC) with Cytochrome P450 enzyme, quantitative determination of the α-asarone in the AC rhizome was performed by RP-HPLC method. In vitro interaction of the plant extract was evaluated by CYP450-carbon monoxide complex (CYP450-CO) assay. Effect on individual isoforms such as CYP3A4 and CYP2D6 isozymes were analyzed through fluorescence product formation and respective IC₅₀ values were determined. CYP450-CO assay showed moderate interaction potential. Extract showed higher IC₅₀ values (46.84 ± 1.83-32.99 ± 2.21 μg/ml) comparing to the standard inhibitors and lower IC₅₀ value than α-asarone (65.16 ± 2.37-42.15 ± 2.45 μg/ml).     

High-yield preparation of wax esters via lipase-catalyzed esterification using fatty acids and alcohols from crambe and camelina oils

Fatty acids obtained from seed oils of crambe (Crambe abyssinica) and camelina (Camelina sativa) via alkaline saponification or steam splitting were esterified using lipases as biocatalysts with oleyl alcohol and the alcohols derived from crambe and camelina oils via hydrogenolysis of their methyl esters. Long-chain wax esters were thus obtained in high yields when Novozym 435 (immobilized lipase B from Candida antarctica) and papaya (Carica papaya) latex lipase were used as biocatalysts and vacuum was applied to remove the water formed. The highest conversions to wax esters were obtained with Novozym 435 (> or =95%) after 4-6 h of reaction, whereas with papaya latex lipase such a high degree of conversion was attained after 24 h. Products obtained from stoichiometric amounts of substrates were almost exclusively (>95%) composed of wax esters having compositions approaching that of jojoba (Simmondsia chinensis) oil, especially when crambe fatty acids in combination with camelina alcohols or camelina fatty acids in combination with crambe alcohols were used as substrates.     

An update of the mercury inventory and atmospheric mercury fluxes to and from Finland

Finland, the northern-most agricultural/industrial country in the world, has been for some time steadily improving environmental mercury (Hg) research. This paper focuses upon Hg recovery during zinc production, uses of Hg, updating of information on Hg emissions and atmospheric transport of Hg to and from Finland. The recovery of Hg as a by-product of zinc production began in 1970. The highest amount of recovered Hg was noted to be 160 t in 1989. Total uses of Hg in different sectors were about 7.4 t in 1992, which had decreased by 50% since the year 1987. In 1992, the estimated Hg emission to air was 2 t yr^?1, whereas to water and land the emission was about 0.20 and 3.67 t yr^?1, respectively. Natural Hg emission in Finland was estimated to be about 0.4 t yr^?1 (range: 0.3 to 0.5 t yr^?1). In addition, an initial attempt was made to estimate the atmospheric Hg flux to and from Finland; these values were noted to be 2.7 and 2.1 t yr^?1, respectively.     

Response to ethanol reduced by past thiamine deficiency

Ethanol-induced intoxication and hypothermia were studied in rats approximately 7 months after severe thiamine deficiency, when treated rats appeared to have recovered their physical health. Previously induced thiamine deficiency without prior ethanol exposure significantly decreased the area under the curve plotted for the concentration of ethanol in blood and also decreased behavioral impairment and hypothermia due to ethanol exposure. Pathophysiologic changes resulting from thiamine deficiency may contribute to both the pharmacodynamic and pharmacokinetic tolerance to ethanol in chronic alcoholics.