Hydroxylations of substituted naphthalenes by Escherichia coli expressing aromatic dihydroxylating dioxygenase genes from polycyclic aromatic hydrocarbon-utilizing marine bacteria

Bioconversion experiments of various mono- or di-substituted naphthalenes such as dimethylnaphthalenes were carried out using the cells of Escherichia coli that expressed aromatic dihydroxylating dioxygenase genes (phnA1A2A3A4 and phdABCD) from polycyclic aromatic hydrocarbon-utilizing marine bacteria, Nocardioides sp. KP7 and Cycloclasticus sp. A5, respectively. We found that the former dioxygenase PhnA1A2A3A4 had broad substrate preference for these compounds and often was able to hydroxylate their methyl groups. Specifically, 1,4-dimethylnaphthalene was predominantly bioconverted into 1,4-dihydroxymethylnaphthalene.     

The association between the phytoplankton, Rhopalosolen species (Chlorophyta; Chlorophyceae), and Anopheles gambiae sensu lato (Diptera: Culicidae) larval abundance in western Kenya

Algae are important food resources of the larvae of the African malaria vectors, Anopheles gambiae Giles and Anopheles arabiensis Patton (Anopheles gambiae sensu lato), and other zooplankton, but empirical evidence remains meager about the agal flora in ephemeral water bodies. The animals present in natural aquatic habitats in western Kenya were sampled from July to November 2002 to study abiotic and biotic environmental factors determining A. gambiae sl larval abundance. The five highest concentrations of third and fourth instars and pupae (hereafter referred to as old-stage larvae) were sampled in conjunction with the unicellular epizoic green algae, Rhopalosolen species (Chlorophyta; Chlorophyceae). Canonical correspondence analysis revealed that the presence of Rhopalosolen species was the most important determinant of the animal assemblage. The density of old-stage A. gambiae sl larvae was positively correlated with the presence of Rhopalosolen species, but the density of first and second instars of A. gambiae sl was not. The water bodies with Rhopalosolen sp. yielded larger mosquitoes in spite of the higher density of larvae. We demonstrated that the productivity of water bodies in terms of the larvae of malaria vectors can differ in magnitude depending on the agal flora. We discuss phytoplankton as a regulator of mosquito larval populations.     

Mapping quantitative trait loci for root development under hypoxia conditions in soybean (<Emphasis Type="Italic">Glycine max</Emphasis> L. Merr.)

Key message

Greatest potential, QTLs for hypoxia and waterlogging tolerance in soybean roots were detected using a new phenotypic evaluation method.

Abstract

Waterlogging is a major environmental stress limiting soybean yield in wet parts of the world. Root development is an important indicator of hypoxia tolerance in soybean. However, little is known about the genetic control of root development under hypoxia. This study was conducted to identify quantitative trait loci (QTLs) responsible for root development under hypoxia. Recombinant inbred lines (RILs) developed from a cross between a hypoxia-sensitive cultivar, Tachinagaha, and a tolerant landrace, Iyodaizu, were used. Seedlings were subjected to hypoxia, and root development was evaluated with the value change in root traits between after and before treatments. We found 230 polymorphic markers spanning 2519.2 cM distributed on all 20 chromosomes (Chrs.). Using these, we found 11 QTLs for root length (RL), root length development (RLD), root surface area (RSA), root surface area development (RSAD), root diameter (RD), and change in average root diameter (CARD) on Chrs. 11, 12, 13 and 14, and 7 QTLs for hypoxia tolerance of these root traits. These included QTLs for RLD and RSAD between markers Satt052 and Satt302 on Chr. 12, which are important markers of hypoxia tolerance in soybean; those QTLs were stable between 2 years. To validate the QTLs, we developed a near-isogenic line with the QTL region derived from Iyodaizu. The line performed well under both hypoxia and waterlogging, suggesting that the region contains one or more genes with large effects on root development. These findings may be useful for fine mapping and positional cloning of gene responsible for root development under hypoxia.

     

The role of carbon flux and biometric observations in constraining a terrestrial ecosystem model: a case study in disturbed forests in East Asia

The process of confining unnecessary freedom is a step toward advanced ecosystem modeling. This study demonstrates the importance of carbon flux and biometric observation in constraining a terrestrial ecosystem model with a simple optimization scheme. At the selected sites from AsiaFlux network, a simultaneous optimization scheme for both carbon flux and biomass was compared with carbon flux-oriented and biomass-oriented optimization schemes using the Biome-BGC model. The optimization scheme oriented to either carbon flux or biomass provided simulation results that were consistent with observations, but with reduced performance in unconstrained variables. The simultaneous optimization scheme yielded results that were consistent with observations for both carbon flux and biomass. By comparing long-term projections simulated by three schemes, it was found that the optimization oriented only to carbon flux has limited performance because misrepresented biomass significantly affected a projection of carbon exchange through heterotrophic respiration. From these experiments, we found that (1) a process model like Biome-BGC is capable of reproducing both carbon flux and biomass within acceptable proximity, (2) constraining biomass is importance not just because it is one of carbon cycle components, but also it significantly affects simulations of carbon flux. Thus, it is important to invest more effort to improve simulation of biomass as well as carbon flux.     

Go, a GTP-Binding Protein: Immunochemical and Immunohistochemical Localization in the Rat

The tissue and cellular distribution of a GTP-binding protein, Go, was investigated in the rat by immunochemical and immunohistochemical methods. Because the specific antibody for the alpha subunit of bovine Go (Go alpha) cross-reacted with rat Go alpha, an enzyme immunoassay method developed for bovine Go alpha was applied for measuring the tissue concentration of Go alpha in the rat. Go alpha was detected in all tissues examined except blood cells. The concentration of Go alpha was highest in the CNS (approximately 7.7 and 4.4 nmol/g in the cerebrum and cerebellum, respectively), followed by the pituitary gland and sciatic nerve. Among the other peripheral tissues, relatively high concentrations of Go alpha were observed in the urinary bladder, stomach, and intestines; however, these values were less than 2% of the concentration in the cerebrum. Go alpha in the intestine was located mostly in the muscle layer. Immunohistochemical study showed that Go alpha was associated mostly with the neural elements but not with cells particular to each peripheral organ. Go alpha was also present in the membranes of neuroendocrine cells, including glandular cells in the anterior lobe of the pituitary gland, chromaffin cells in the medulla of the adrenal gland, islets cells in the pancreas, and parafollicular cells in the thyroid. These results indicate that Go is localized exclusively in the nervous tissues and neuroendocrine cells.     

Ontogeny of the GTP-Binding Protein Go in Rat Brain and Heart

We determined the ontogeny of the GTP-binding protein Go in rat brain and heart by employing highly sensitive enzyme immunoassay methods. In the brain, the alpha subunit of Go (Go alpha) gradually increased and reached adult levels approximately 20 and 30 days after birth in cerebral cortex and cerebellum, respectively. Concentrations of beta subunits, which were also quantified by the immunoassay, were almost equal to those of Go alpha in the brain of rats younger than 10 days, but were higher than those of Go alpha after 10 days. These results suggest that late development of GTP-binding proteins other than Go. Go alpha was immunohistochemically positive in neuropils and negative in cell bodies at any age tested. In the heart, the concentrations of Go alpha increased up to several times of the adult level just after birth, and then gradually decreased after the 20th postnatal day. The level of Go alpha in the liver, however, was very low and constant throughout ontogenic development. An immunohistochemical study indicated that Go alpha was positive in the cardiac muscle of young rat, but negative in that of adult rat. These results indicate that Go alpha exists in cells other than those of nervous tissues and neuroendocrine cells in some periods of ontogenic development.     

Species diversity and primary productivity inMiscanthus sinensis grasslands

In an old field grassland dominated byMiscanthus sinensis Anderss. the community structures, phytomass, dominance ofM. sinensis and species diversity were measured. Species and life form composition of the stand were characterized by higher percentages of therophytes, woody and shrubby species, liana and alien species. From May so September in 1982, all the aboveground parts were harvested from each of the four quadrats (2 m×2 m) once a month. Seasonal peak of aboveground phytomass, in September, was 1027 g d.w.m⁻² to whichM. sinensis contributed as much as 96.5%. With the progress of the growing season,M. sinensis became increasingly important both in stand phytomass and in dominance, whereas species diversity based on the dry weight contributions of constituent species decreased. Our analysis of these seasonal trends showed that the diversity was largely a function of dominance of the most important species, rather than that of stand phytomass or productivity. The simultaneous measurements of 20 quadrats in late August 1983, also supported the above conclusion.     

Cry2 Is Critical for Circadian Regulation of Myogenic Differentiation by Bclaf1-Mediated mRNA Stabilization of Cyclin D1 and Tmem176b

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