The ecoresponsive genome of Daphnia pulex

We describe the draft genome of the microcrustacean Daphnia pulex, which is only 200 megabases and contains at least 30,907 genes. The high gene count is a consequence of an elevated rate of gene duplication resulting in tandem gene clusters. More than a third of Daphnia's genes have no detectable homologs in any other available proteome, and the most amplified gene families are specific to the Daphnia lineage. The coexpansion of gene families interacting within metabolic pathways suggests that the maintenance of duplicated genes is not random, and the analysis of gene expression under different environmental conditions reveals that numerous paralogs acquire divergent expression patterns soon after duplication. Daphnia-specific genes, including many additional loci within sequenced regions that are otherwise devoid of annotations, are the most responsive genes to ecological challenges.     

Flaxleaf fleabane (Conyza bonariensis) populations have developed glyphosate resistance in north-east Australian cropping fields

In recent years flaxleaf fleabane has become a widespread and difficult-to-control weed in no-tilled fallowed fields, where weeds are controlled by applications of glyphosate, in annual cropping systems of north-east Australia. Fifty-two populations, collected in a national survey from agricultural and non-agricultural areas, were tested in two glyphosate dose-response pot experiments. In two subsequent pot experiments, a sub-set of these populations was tested with a field rate of glyphosate when weeds of two ages were grown at different soil moistures. In the first and second experiments, most populations collected from chemical fallowed or cropped fields in north-east Australia had GR₅₀ (estimated dose for 50% biomass reduction) values three to six times greater than the susceptible populations, indicating low levels of glyphosate resistance. Several populations from roadsides adjacent to chemical fallowed or cropped fields also had higher GR₅₀ values, indicating movement of seeds from resistant plants. In the third experiment, weed biomass of all populations from chemical fallowed or cropped fields was 70-98% of unsprayed compared to 2-3% for the susceptible populations, irrespective of weed age or soil moisture. In the fourth experiment which treated older weeds, the response of several resistant populations to glyphosate was unaffected by differences in weed age and soil moisture, whereas the biomass of the other resistant populations was greater following spraying of older and/or moisture stressed plants compared with smaller non-stressed plants. Thus, exclusive reliance on glyphosate for fallow weed control in this region has resulted in the evolution of resistance in flaxleaf fleabane populations in a cropping system with annual non-transgenic crops. Prolific production of windborne seeds, combined with poor control associated with spraying large moisture-stressed weeds, is likely to have contributed also to flaxleaf fleabane becoming such a problem weed.     

Inactivation at various temperatures of bovine viral diarrhea virus in beef derived from persistently infected cattle

Bovine viral diarrhea virus (BVDV) is a pestivirus that is enzootic in most cattle populations throughout the world. This virus is present throughout the body of persistently infected (PI) cattle. Previous research has not assessed the cooking temperature at which BVDV in meat from PI cattle can be inactivated. Therefore, muscle tissue from 6 PI cattle was harvested, refrigerated, frozen, and heated to various internal temperatures. The concentration of virus present was determined by virus isolation. Average cell culture infective doses (50% endpoint; CCID(50)) of BVDV per gram of frozen, uncooked meat from PI cattle were 10(5.85) CCID(50)/g of whole cuts and 10(6.02) CCID(50)/g of ground meat. The virus in whole and ground meat was consistently inactivated when cooked to temperatures greater than or equal to 75°C. A second objective of this research was to thoroughly reassess if Vero cells were permissive to BVDV infection in our laboratory to provide further indication of whether primates, including humans, might be susceptible to BVDV. Vero cells were not permissive to infection with any of 43 different strains of BVDV that readily replicated in Madin Darby bovine kidney cells. In conclusion, this bovine pathogen, which is not considered to be a human pathogen, can be inactivated by cooking ground or whole cuts of meat to 75°C or higher. Care should be taken to ensure that susceptible hosts such as pigs are not fed improperly cooked meat, meat by-products, or waste food originating from PI cattle.     

Bauxite residue fines as an amendment to residue sands to enhance plant growth potential—a glasshouse study

Purpose  

This glasshouse study was conducted to determine if amending bauxite residue sand with residue fines would improve its suitability as a growth medium. Alcoa’s West Australian operations mechanically separate residue into two size fractions: residue fines (which are dominated by particles <150 μm) and residue sands (>150 μm). Residue sand represents the primary material used as a growth medium for rehabilitation, and prior to amendments, it exhibits many characteristics unfavourable for plant growth.     

Development of a sandwich ELISA and comparison with PCR for the detection of F11 and F165 fimbriated Escherichia coli isolates from septicaemic disease in farm animals

The P fimbriae F11 and F165 that have been demonstrated on Escherichia coli septicaemic strains in poultry and calves, respectively, possess a nearly identical major subunit that demonstrates a serological cross-reaction. A polyclonal antibody-based sandwich ELISA (sELISA) that was specific for both F11 and F165 fimbriated strains was compared with a PCR method to detect F11/F165 fimbriated strains, in a collection of E. coli strains isolated from diseased animals. Of 298 isolates tested, 36 were positive by PCR of which only 14 were sELISA positive. There were no sELISA positive but PCR negative results. The 36 PCR positive isolates comprised 11 avian strains of which 10 were sELISA positive, 20 bovine strains of which 4 were sELISA positive and 3 ovine strains, 1 porcine strain and 1 equine strain all of which were sELISA negative. The F11/F165 incidence of 10.7% in 103 poultry and 18.3% in 109 bovine isolates demonstrates a moderate level of these factors in E. coli septicaemic cases in Northern Ireland.     

Sampling plan and test protocol for the semiquantitative detection of genetically modified canola (Brassica napus) seed in bulk canola seed

Using a statistical approach, sampling plans for the semiquantitative detection of genetically modified (GM) canola within a bulk seed sample can be developed and tailored to meet different GM thresholds, costs, and confidence limits. This is achieved by changing the number of subsamples analyzed, the number of seeds per subsample, and the percentage of positive results allowed. These sampling plans must be devised carefully, taking into account the detection capability of the analytical assay. This is particularly important in the case of InVigor (a registered trademark of Bayer CropScience) canola, for which expression levels of the introduced protein in seed are very low. Lateral flow assays and enzyme-linked immunosorbent assays (ELISA) were both investigated for their suitability as a qualitative assay using a subsampling approach. On the basis of an ELISA, several sampling plans have been devised and validated to provide at least 99% confidence that bulk seed samples containing at least 0.9% (w/w) InVigor canola will be detected. Although the term "seed" is used throughout this paper to refer to the canola, the term "seed" is to be taken to include both seed and the canola seed (grain) that is harvested by the farmer/grower.