Assessing the potential health risk of cyanobacteria and cyanotoxins in Lake Naivasha,Kenya

Hydrobiologia - This study discerned the causes of cyanobacteria blooms in Lake Naivasha (Kenya). We hypothesized that phytoplankton and cyanobacteria biomass respond to hydrologic cycles, peaking...     

The control of seed oil polyunsaturate content in the polyploid crop species Brassica napus

Many important plant species have polyploidy in their recent ancestry, complicating inferences about the genetic basis of trait variation. Although the principal locus controlling the proportion of polyunsaturated fatty acids (PUFAs) in seeds of Arabidopsis thaliana is known (fatty acid desaturase 2; FAD2), commercial cultivars of a related crop, oilseed rape (Brassica napus), with very low PUFA content have yet to be developed. We showed that a cultivar of oilseed rape with lower than usual PUFA content has non-functional alleles at three of the four orthologous FAD2 loci. To explore the genetic basis further, we developed an ethyl methanesulphonate mutagenised population, JBnaCAB_E, and used it to identify lines that also carried mutations in the remaining functional copy. This confirmed the hypothesised basis of variation, resulting in an allelic series of mutant lines showing a spectrum of PUFA contents of seed oil. Several lines had PUFA content of ~6 % and oleic acid content of ~84 %, achieving a long-standing industry objective: very high oleic, very low PUFA rapeseed without the use of genetic modification technology. The population contains a high rate of mutations and represents an important resource for research in B. napus.     

Prevalence of Seropositivity to Pandemic Influenza A/H1N1 Virus in the United States following the 2009 Pandemic

Background

2009 pandemic influenza A/H1N1 (A(H1N1)pdm09) was first detected in the United States in April 2009 and resulted in a global pandemic. We conducted a serologic survey to estimate the cumulative incidence of A(H1N1)pdm09 through the end of 2009 when pandemic activity had waned in the United States.

Methods

We conducted a pair of cross sectional serologic surveys before and after the spring/fall waves of the pandemic for evidence of seropositivity (titer ≥40) using the hemagglutination inhibition (HI) assay. We tested a baseline sample of 1,142 serum specimens from the 2007–2008 National Health and Nutrition Examination Survey (NHANES), and 2,759 serum specimens submitted for routine screening to clinical diagnostic laboratories from ten representative sites.

Results

The age-adjusted prevalence of seropositivity to A(H1N1)pdm09 by year-end 2009 was 36.9% (95%CI: 31.7–42.2%). After adjusting for baseline cross-reactive antibody, pandemic vaccination coverage and the sensitivity/specificity of the HI assay, we estimate that 20.2% (95%CI: 10.1–28.3%) of the population was infected with A(H1N1)pdm09 by December 2009, including 53.3% (95%CI: 39.0–67.1%) of children aged 5–17 years.

Conclusions

By December 2009, approximately one-fifth of the US population, or 61.9 million persons, may have been infected with A(H1N1)pdm09, including around half of school-aged children.     

A comparative linkage map of oilseed rape and its use for QTL analysis of seed oil and erucic acid content

We have developed a new DH mapping population for oilseed rape, named TNDH, using genetically and phenotypically diverse parental lines. We used the population in the construction of a high stringency genetic linkage map, consisting of 277 loci, for use in quantitative genetic analysis. A proportion of the markers had been used previously in the construction of linkage maps for Brassica species, thus permitting the alignment of maps. The map includes 68 newly developed Sequence Tagged Site (STS) markers targeted to the homologues of defined genes of A. thaliana. The use of these markers permits the alignment of our linkage map with the A. thaliana genome sequence. An additional 74 loci (31 newly developed STS markers and 43 loci defined by SSR and RFLP markers that had previously been used in published linkage maps) were added to the map. These markers increased the resolution of alignment of the newly constructed linkage map with existing Brassica linkage maps and the A. thaliana genome sequence. We conducted field trials with the TNDH population at two sites, and over 2 years, and identified reproducible QTL for seed oil content and erucic acid content. The results provide new insights into the genetic control of seed oil and erucic acid content in oilseed rape, and demonstrate the utility of the linkage map and population.Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.D. Qiu and C. Morgan authors contributed equally to the work.     

Facultative apomixis and hybridization in arctic Potentilla section Niveae (Rosaceae) from Svalbard

The degree of sexual seed set and the ability to cross were investigated in three taxa of Potentilla section Niveae ( P. chamissonis , P. insularis and P. nivea ) from the Svalbard Archipelago. Emasculated and bagged flowers had little or no seed set, while 71% of the emasculated, bagged and pollinated flowers had some. The taxa are interpreted as pseudogamous apomicts. Parental plants and offspring were subjected to isozyme analysis. Most of the offspring were clones of the mother plant, but 1.7% had bands from the pollen donor. The sexual offspring were all produced by mother plants of P. insularis , which is interpreted as a facultative apomict. Surprisingly, crosses between different taxa gave higher seed to ovule ratios and numbers of sexually produced offspring than crosses within taxa. Some of the sexually produced hybrid offspring had the same kind of hairs on the petioles as their mother taxon, showing that hybrids may not be intermediate in hair characters, which are considered important in the delimitation of these taxa. The results of the present study indicate very close relationships among the investigated plants.  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 142 , 373−381.     

Pollen-stigma adhesion in Brassica spp involves SLG and SLR1 glycoproteins.

The adhesion of pollen grains to the stigma is the first step of pollination in flowering plants. During this step, stigmas discriminate between pollen grains that can and cannot be permitted to effect fertilization. This selection is operated by various constituents of the cell walls of both partners. Several genes structurally related to the self-incompatibility system that prevents self-pollination in Brassica spp are known to target their products into the stigma cell wall. We proposed previously that one of these genes, the one encoding the S locus glycoprotein (SLG)-like receptor 1 (SLR1), which is coexpressed with that encoding SLG, may participate in pollen-stigma adhesion. Here, we exploit a biomechanical assay to measure the pollen adhesion force and show that it is reduced both by transgenic suppression of SLR1 expression and by pretreatment of wild-type stigmas with anti-SLR1 antibodies, anti-SLG antibodies, or pollen coat-protein extracts. Our results indicate a common adhesive function for the SLR1 and SLG proteins in the pollination process.     

Sequence complexity of the S receptor kinase gene family in Brassica

A genomic library from an S ₂₉/S ₂₉ self-incompatible genotype of Brassica oleracea was screened with a probe carrying part of the catalytic domain of a Brassica S-receptor kinase (SRK)-like gene. Six positive phage clones with varying hybridisation intensities (K1 to K6) were purified and characterised. A 650–700 by region corresponding to the probe was excised from each clone and sequenced. DNA and predicted protein sequence comparisons based on a multiple alignment identified K5 as a pseudogene, whereas the others could encode functional proteins. K3 was found to have lost an intron from its genomic sequence. The six genes display different degrees of sequence similarity and form two distinct clusters in a dendrogram. The 98% similarity between K4 and K6, which extends across intron sequences, suggests that these might be very recently diverged alleles or daughters of a duplication. In addition, K2 showed a comparably high similarity to the probe. Clones K1, K3 and K5 cross-hybridised with an SLG ₂₉ cDNA probe, indicating the presence of upstream receptor domains homologous to the Brassica SLG gene. This suggests that the previously reported S sequence complexity may be ascribed to a large receptor kinase gene family.     

Effects of dietary calcium on the metabolism of trace elements in male and female rats

The effect of dietary calcium on the metabolism of iron, zinc, copper, and manganese in male and female rats was investigated. For 3 or 6 weeks the rats were fed three diets containing: (1) 0.26, (2) 0.52, or (3) 2.08% Ca. The apparent absorption of iron was depressed by the high calcium diet, and manganese absorption was highest in the low calcium groups. Generally there was a decrease in the absorption of minerals from 3 to 6 weeks. With an increase in the dietary calcium the absorption of Ca and P decreased. The liver iron concentration in the females fed diet 3 decreased from about 600 to 200 microg/g dry weight. The high calcium intake also caused a slight increase in the heart calcium levels in both sexes. However, diet 3 prevented kidney calcification in the female rats at 6 weeks and this was attributed to a dramatic decrease in the urinary phosphorus, although the calcium had increased about 40 times. In males, on the other hand, the high calcium diet caused some kidney calcification.