Microbial consortia that degrade 2,4-DNT by interspecies metabolism: isolation and characterisation

Two consortia, isolated by selective enrichment from a soil sample of anitroaromatic-contaminated site, degraded 2,4-DNT as their sole nitrogensource without accumulating one or more detectable intermediates. Thoughoriginating from the same sample, the optimised consortia had no commonmembers, indicating that selective enrichment resulted in different end points.Consortium 1 and consortium 2 contained four and six bacterial speciesrespectively, but both had two members that were able to collectivelydegrade 2,4-DNT. Variovorax paradoxus VM685 (consortium 1)and Pseudomonas sp. VM908 (consortium 2) initiate the catabolismof 2,4-DNT by an oxidation step, thereby releasing nitrite and forming4-methyl-5-nitrocatechol (4M5NC). Both strains contained a gene similarto the dntAa gene encoding 2,4-DNT dioxygenase. They subsequentlymetabolised 4M5NC to 2-hydroxy-5-methylquinone (2H5MQ) and nitrite,indicative of DntB or 4M5NC monooxygenase activity. A second consortiummember, Pseudomonas marginalis VM683 (consortium 1) and P.aeruginosa VM903, Sphingomonas sp. VM904, Stenotrophomonasmaltophilia VM905 or P. viridiflava VM907 (consortium 2), was foundto be indispensable for efficient growth of the consortia on 2,4-DNT and forefficient metabolisation of the intermediates 4M5NC and 2H5MQ. Knowledgeabout the interactions in this step of the degradation pathway is rather limited.In addition, both consortia can use 2,4-DNT as sole nitrogen and carbon source.A gene similar to the dntD gene of Burkholderia sp. strain DNT that catalyses ring fission was demonstrated by DNA hybridisation in the secondmember strains. To our knowledge, this is the first time that consortia are shownto be necessary for 2,4-DNT degradation.     

Drinking water quality and arsenic health risk assessment in Sistan and Baluchestan,Southeastern Province,Iran

Access to drinking water is one of the most important indicators determined by the World Health Organization (WHO). This investigation surveyed the concentration of various pollutants in drinking water and its health risk attribute to Arsenic in Sistan and Baluchistan province, Iran. Water samples were collected from ground water and analyzed for physical parameters, anions, and heavy metals using the standard procedures. The concentrations of sulfate (269 ± 127 mg/l) in five sites exceeded the permissible limit (250 mg/l), while chlorine concentrations (223 ± 100 mg/l) in four sites exceeded the permissible limit (250 mg/l) set by WHO. Similarly, the concentrations of Mg (30 ± 11 mg/l) in four sites exceeded the permissible limit (30 mg/l), while Na concentrations (222 ± 99 mg/l) in five sites exceeded the permissible limit (200 mg/l) set by Institute of Standards and Industrial Research of Iran (ISIRI). In addition, arsenic was in acceptable levels recommended by WHO and local regulations. Based on the calculated indices of hazard qutient (HR) and excess lifetime cancer risk (ELCR), the in-use drinking water has no adverse effects on the consumer's health. Excessive use of fertilizers and pesticides, unsuitable sewerage systems, and inappropriate sludge and solid waste disposal in this province can lead to drinking water pollution. Also, excessive pumping of ground water should be managed as an effective method for supply of safe drinking water.     

Regulation of Mammalian Cone Phototransduction by Recoverin and Rhodopsin Kinase

Cone photoreceptors function under daylight conditions and are essential for color perception and vision with high temporal and spatial resolution. A remarkable feature of cones is that, unlike rods, they remain responsive in bright light. In rods, light triggers a decline in intracellular calcium, which exerts a well studied negative feedback on phototransduction that includes calcium-dependent inhibition of rhodopsin kinase (GRK1) by recoverin. Rods and cones share the same isoforms of recoverin and GRK1, and photoactivation also triggers a calcium decline in cones. However, the molecular mechanisms by which calcium exerts negative feedback on cone phototransduction through recoverin and GRK1 are not well understood. Here, we examined this question using mice expressing various levels of GRK1 or lacking recoverin. We show that although GRK1 is required for the timely inactivation of mouse cone photoresponse, gradually increasing its expression progressively delays the cone response recovery. This surprising result is in contrast with the known effect of increasing GRK1 expression in rods. Notably, the kinetics of cone responses converge and become independent of GRK1 levels for flashes activating more than ∼1% of cone pigment. Thus, mouse cone response recovery in bright light is independent of pigment phosphorylation and likely reflects the spontaneous decay of photoactivated visual pigment. We also find that recoverin potentiates the sensitivity of cones in dim light conditions but does not contribute to their capacity to function in bright light.     

Molecular Systematics of Trilliaceae I. Phylogenetic Analyses of Trillium Using matK Gene Sequences

matK was conducted using 41 Trillium taxa and two out-group taxa (Veratrum maackii and Helonias bullata). A total of 1608 base pairs were analyzed and compared., and then there were 61 variable (36 informative) sites among Trillium species. Fifteen insertion/deletion events (indels) of six or fifteen base pairs were also detected. Phylogenetic analyses of the sequence data revealed that the subgenus Phyllantherum (sessile-flowered species) forms a distinct monophyletic group, whereas the subgenus Trillium (pedicellate-flowered species) does not form a monophyletic group, and is composed of three distinct groups and three basally located species in the tree: (1) the Erectum group, (2) the Grandiflorum group, and (3) the Pusillum group and (4) the three species, including T. govanianum, T. undulatum, and T. rivale. T .rivale appears to be the most basally diverged and a very specialized taxon among the ingroup members. Our matK data indicated that the closest relative of the subgenus Phyllantherum is the Grandiflorum group. The results are concordant with the results of the RFLP analysis of cpDNA and also more or less with those of the cladistic analysis of morphological characters. Received 11 September 1998/ Accepted in revised form 25 December 1998     

Elevated atmospheric CO2 affects soil microbial diversity associated with trembling aspen

The effects of elevated atmospheric CO₂ (560 p.p.m.) and subsequent plant responses on the soil microbial community composition associated with trembling aspen was assessed through the classification of 6996 complete ribosomal DNA sequences amplified from the Rhinelander WI free-air CO₂ and O₃ enrichment (FACE) experiments microbial community metagenome. This in-depth comparative analysis provides an unprecedented, detailed and deep branching profile of population changes incurred as a response to this environmental perturbation. Total bacterial and eukaryotic abundance does not change; however, an increase in heterotrophic decomposers and ectomycorrhizal fungi is observed. Nitrate reducers of the domain bacteria and archaea, of the phylum Crenarchaea , potentially implicated in ammonium oxidation, significantly decreased with elevated CO₂. These changes in soil biota are evidence for altered interactions between trembling aspen and the microorganisms in its surrounding soil, and support the theory that greater plant detritus production under elevated CO₂ significantly alters soil microbial community composition.     

Complete Genome Sequence of Clostridium sp. Strain BNL1100, a Cellulolytic Mesophile Isolated from Corn Stover

We present the full genome sequence of Clostridium sp. strain BNL1100, a Gram-positive, endospore-forming, lignocellulolytic bacterium isolated from a corn stover enrichment culture. The 4,613,747-bp genome of strain BNL1100 contains 4,025 putative protein-coding genes, of which 103 are glycoside hydrolases, the highest detected number in cluster III clostridia.     

Connective tissue growth factor is induced in bleomycin-induced skin scleroderma

The origin of fibrotic cells within connective tissue is unclear. For example, the extent to which microvascular pericytes contribute to the number of myofibroblasts present in dermal fibrosis in uncertain. Connective tissue growth factor (CTGF/CCN2) is a marker and mediator of fibrosis. In this report, we use an antibody recognizing CCN2 to assess the cell types in mouse dermis which express CCN2 in the bleomycin model of skin scleroderma. Control (PBS injected) and fibrotic (bleomycin-injected) dermis was examined for CCN2, α-smooth muscle actin (α-SMA) (to detect myofibroblasts), and NG2 (to detect pericytes) expression. Consistent with previously published data, CCN2 expression was largely absent in the dermis of control mice. However, upon exposure to bleomycin, CCN2 was observed in the dermis. Cells that expressed CCN2 were α−SMA-expressing myofibroblasts. Approximately 85% of myofibroblasts were NG2-positive, CCN2-expressing pericytes, indicating that pericytes significantly contributed to the presence of myofibroblasts in sclerotic dermis. Thus CCN2 is induced in fibrotic skin, correlating with the induction of myofibroblast induction. Moreover, CCN2-expressing pericytes significantly contribute to the appearance of myofibroblasts in bleomycin-induced skin scleroderma.     

Genetic diversity of some wild almonds and related <Emphasis Type="Italic">Prunus</Emphasis> species revealed by SSR and EST-SSR molecular markers

Almond and its related wild species, which are widely distributed in Central and West Asia, have high genetic variation. This is an important source of genetic diversity for crop improvement. In this study a set of 32 SSR and 12 EST-SSR primer pairs were used to determine genetic diversity in 89 accessions of almond and other Prunus species. Most of the accessions (68) were collected from natural habitats of Iran. SSR primers amplified higher numbers of alleles than EST-SSR markers and discriminated genotypes more effectively. Results indicated high diversity among accessions. Observed heterozygosity (Ho) was 0.581. Nei’s index of diversity (He) and average number of alleles per locus (na) were 0.885 and 34, respectively. The mean value of polymorphism information content (PIC) was 0.874. The average Fst (F-statistics index) was 0.271 and the fixation index (Fis) was 0.151. Estimated variance among putative populations (AP) and individuals (AI) and within individuals (WI) were 5, 35, and 60%, respectively, which revealed that most of the variation was distributed among individuals rather than groups. Cultivated almonds were highly similar to P. fenzeliana, which is native to West Asia, supporting the importance of these regions in almond domestication. In the dendrogram of groups, minimum genetic distance was observed between Amygdalus and Orientalis groups from the Euamygdalus section. The Leptopus and Chameamygdalus sections were more distant from almonds than plums. The results also showed Dodecandra (Lycioides) series should be taxonomically classified closer to the section Euamygdalus.