The genomic sequence of the bovine T cell receptor gamma TRG loci and localization of the TRGC5 cassette

The bovine and ovine TRG genes have previously been shown to be located in two loci, TRG1 and TRG2, in contrast to human and mouse TRG genes that are located in a single locus. The bovine TRG1 and TRG2 loci are located on chromosome 4 at 4q3.1 and 4q1.5-2.2, respectively. The complete genomic organization of the two bovine loci is described: each locus comprises three cassettes, each one includes one or several variable genes (TRGV) and one or several joining genes (TRGJ) preceding a constant (TRGC) gene. The location of the TRGC5 cassette is conclusively described in 5' of the TRG1 locus. Analysis of 17 TRGV belonging to 10 different subgroups, 8 TRGJ and 6 TRGC genes is conducted which comprises the most comprehensive list to date.     

Is the 2000 CDC growth reference appropriate for developing countries?

In 2000, the Centers for Disease Control and Prevention (CDC) produced a revised growth reference. This has already been used in different settings outside the USA. Using data obtained during a nutritional survey in Madagascar, we compare results produced by using both the 2000 CDC and the 1978 National Center for Health Statistics (NCHS)/World Health Organization (WHO) growth references. We show that changing the reference has an important impact on nutritional diagnosis. In particular, the prevalence of wasting is greatly increased. This could generate substantial operational and clinical difficulties. We recommend continued use of the 1978 NCHS/WHO reference until release of the new WHO multi-country growth charts.     

Effect of freezing and thawing on microbial activity and glyphosate degradation in two Norwegian soils

Little research has been done on pesticide dissipation in cold climates and there is a need to focus on the influence of climate on pesticide degradation in soil. Glyphosate, N-(phosphonomethyl)glycine, is a herbicide frequently used for controlling perennial weeds through application after harvest and was used as a model compound for this study. The effect of freeze-thaw activity on the availability of glyphosate in soil, and consequently its mineralization by soil microorganisms, was studied through laboratory incubations of repacked soil cores treated with 14C-labelled glyphosate and subjected to different freeze-thaw treatments. Winter simulation regimes applied were constant thaw (+5 degrees C), constant freezing (-5 degrees C), unstable conditions with short fluctuations (24 h of -5 degrees C followed by 24 h of +5 degrees C), and long duration fluctuations (3 weeks of -5 degrees C followed by 3 weeks of +5 degrees C). Distribution of 14C-glyphosate was followed during the incubation through measurements of the mineralized fraction (14CO2), soil water fraction, KOH extractable fraction, and non-extractable fraction. Microbial parameters used to characterize the soils were estimates of size of microbial biomass, overall microbial activity and microbial diversity. The constant freezing treatment exhibited the lowest amount of glyphosate mineralization. The constant thawed treatment and the treatments with fluctuating temperature exhibited significantly increased mineralization. These results were in accordance with the observed concentration of glyphosate in soil water; the higher the activity, the lower the concentration. The amount of glyphosate extractable with KOH and the resulting non-extractable fraction, however, were not significantly affected by soil type or temperature regime. The glyphosate mineralization pattern was comparable with the overall microbial activity in the soils. Observed different levels of diversity might explain some of the difference in total glyphosate mineralization between soils.     

Extended nucleation of the 1999 Mw 7.6 Izmit earthquake

Laboratory and theoretical studies suggest that earthquakes are preceded by a phase of developing slip instability in which the fault slips slowly before accelerating to dynamic rupture. We report here that one of the best-recorded large earthquakes to date, the 1999 moment magnitude (M(w)) 7.6 Izmit (Turkey) earthquake, was preceded by a seismic signal of long duration that originated from the hypocenter. The signal consisted of a succession of repetitive seismic bursts, accelerating with time, and increased low-frequency seismic noise. These observations show that the earthquake was preceded for 44 minutes by a phase of slow slip occurring at the base of the brittle crust. This slip accelerated slowly initially, and then rapidly accelerated in the 2 minutes preceding the earthquake.     

Spatial variability of glyphosate mineralization and soil microbial characteristics in two Norwegian sandy loam soils as affected by surface topographical features

The aim of this study was to investigate the possible influence of surface topographical features on the spatial variability of glyphosate degradation and some microbial characteristics in sandy loam soil. Soil samples were taken from the ploughed layer across an agricultural field after seedbed preparation for grain (Grue site), and down to 1 m depth under a ridge tilled field (Målselv site), both sites having similar soil textural characteristics (sandy loam soil). Laboratory experiments were performed looking at glyphosate mineralization and soil microbial activity at the Grue site, as well as microbial biomass, activity and substrate utilization patterns at the Målselv site. Microbial biomass and activity decreased, and substrate utilization patterns changed with increasing soil depth, reflecting naturally occurring changes in quantity and quality of soil organic carbon. Further, our results show that considerable spatial heterogeneity in the degradation rate of glyphosate and general carbon utilization exists even across small areas within a single agricultural field. This horizontal variability was observed over several spatial scales, and could not be clearly explained. It evidently arose from differences in environmental factors affecting microbial activity and growth, and topographical features controlling redistribution of water and matter flow patterns were correlated to the investigated soil microbial variables.     

Spatial variability in 14C-herbicide degradation in surface and subsurface soils

The spatial variability in mineralization of atrazine, isoproturon and metamitron in soil and subsoil samples taken from a 135-ha catchment in north France was studied. Fifty-one samples from the top layer were taken to represent exhaustively the 31 agricultural fields and 21 soil types of the catchment. Sixteen additional samples were collected between depths of 0.7 and 10 m to represent the major geological materials encountered in the vadose zone of the catchment. All these samples were incubated with 14C-labelled atrazine under laboratory conditions at 28 degrees C. Fourteen selected surface samples which exhibited distinctly different behaviour for atrazine dissipation (including sorption and mineralization) were incubated with 14C-isoproturon and 14C-metamitron. Overall soil microbial activity and specific herbicide degradation activities were monitored during the incubations through measurements of total carbon dioxide and 14C-carbon dioxide respectively. At the end of the incubations, extractable and non-extractable (bound) residues remaining in soils were measured. Variability of herbicide dissipation half-life in soil surface samples was lower for atrazine and metamitron (CV < 12%) than for isoproturon (CV = 46%). The main contributor to the isoproturon dissipation variability was the variability of the extractable residues. For the other herbicides, spatial variability was mainly related to the variability of their mineralization. In all cases, herbicide mineralization half-lives showed higher variability than those of dissipation. Sorption or physicochemical soil properties could not explain atrazine and isoproturon degradation, whose main factors were probably directly related to the dynamics of the specific microbial degradation activity. In contrast, variability of metamitron degradation was significantly correlated to sorption coefficient (K(d)) through correlation with the sorptive soil components, organic matter and clay. Herbicide degradation decreased with depth as did the overall microbial activity. Atrazine mineralization activity was found down to a depth of 2.5 m; beyond that, it was negligible.     

Amitrole degradation in vineyard soils in relation to pedo-climatic conditions

The fate of [¹⁴C]-amitrole herbicide was studied in eight soils having different capacities for amitrole mineralisation. Laboratory incubations were run combining different experimental conditions: temperature (4, 28 and 50°C), soil moisture (50, 100 and 150% of soil water holding capacity) and microbial activity (sterile and non-sterile conditions). During incubation, samples of the soils were periodically extracted with 0.5 M NH₄OH and extracts were analysed by HPLC. The lengths of time needed for 50% dissipation of amitrole (DT50) in soils ranged from less than 1 day to more than 70 days. Amitrole mineralisation occurred only in non-sterile soils, showing that it is a biological process. Mineralisation was lower in soils with a coarse texture than in soils with a fine texture. Soil water content had little influence on the total amount of amitrole mineralised at the end of incubation. Temperature had a greater influence on mineralisation, although rates were still high at low and high temperatures. In non-sterile as in sterile soils, the major product detected in the extracts was amitrole. Additional non-identified radioactivity was occasionally extracted. However, it never represented more than 10% of initially applied amitrole. Non-extractable residues represented less than 15% of applied radioactivity in acidic soils and about 30% of applied radioactivity in alkaline and neutral soils. The amount of non-extractable radioactivity formed was enhanced in sterile as compared to non-sterile soils. Furthermore, in sterile soils, high temperature induced an increase of non-extractable residues, showing that amitrole is chemically quite reactive.     

Spatial and Genetic Analysis of a Flag Shoot Subpopulation of Erysiphe necator in Italy

ABSTRACT Erysiphe necator overwinters as ascospores in cleistothecia and mycelium in dormant buds of grapevines. Shoots developing from infected buds early in the growing season are covered with dense mycelium and are known as "flag shoots". Combining epidemiological and genetic analyses, the objective of this study was to analyze the spatial and genetic structure of a flag shoot subpopulation of E. necator as a way to assess the contribution of flag shoots as primary inoculum, and to determine if flag shoot subpopulations are clonal with only one mating type. One vineyard in Tuscany, Italy was surveyed intensively for flag shoots for 8 years; isolations of E. necator were made from flag shoots for 5 years. We observed distinct disease foci developing around flag shoots early in epidemics, demonstrating a steep dispersal gradient of conidia and the importance of flag shoots as primary inoculum sources. Flag shoots were spatially aggregated within and between years, most likely as a result of short-distance dispersal of conidia from flags early in the season when dormant buds for the next year's shoots are formed and are susceptible to infection. The two mating types were found in 1:1 ratios in this flag shoot subpopulation. Genotypic diversity, based on inter-simple sequence repeat markers, was high in all years with only two haplotypes occurring twice, and subpopulations were genetically differentiated between years. Similarities between haplotypes were not spatially autocorrelated. One multilocus analysis of population structure is consistent with the hypothesis of random mating but another is not. These results are not consistent with expectations for a strictly clonal or strictly randomly mating flag shoot subpopulation. Instead, the hypothesis that the flag shoot subpopulation of E. necator may reproduce clonally and sexually needs further testing.     

Expression of Introduced Genes after Tuber Propagation of Transgenic Potato Plants

The linkage relationship between eighteen isozyme loci and the morphological markers hypocotyl colour (R-r), monogerm character (M-m), pollen fertility (X) and stem fasciation (Verb.) are tested. Three linkage groups could be set up, involving all morphological marker loci and eight of the isozyme loci. Est-2, R-r, Fdp-2, Got2 and Icd-1 belong to linkage group I, linkage group II includes the loci Fas-fas M-m, Est-3 and Aco-1, linkage group III contains the loci X, Mdh-1 and Est-5. When analysing the inheritance of isozymes and RFLPs, deviations are usually found in some lines from the expected frequencies of a 3 : 1 or 1 : 2 : 1 segregation at single marker loci. In many cases these data can still be used for the estimation of recombination values with linked loci under the control of selection. Procedures to estimate linkage in such cases are given and applied to experimental data in Beta vulgaris.     

Herbicide degradation and copper complexation by bacterial mixed cultures from a vineyard stormwater basin

Purpose  

The use of stormwater basins as constructed wetlands for the bioremediation of agricultural runoff waters contaminated with pesticides has great potential. The structure and dynamics of the bacterial community in such system, and its function with respect to contaminant removal, remain to be investigated in detail.