Distribution of individual members of the mosquito Anopheles maculipennis complex in Germany identified by newly developed real‐time PCR assays

Owing to their role as vectors of malaria parasites, species of the Anopheles maculipennis complex (Diptera: Culicidae) Meigen were intensively studied in the past, but with the disappearance of malaria in Germany in the middle of the last century, the interest in this field of research declined. A comprehensive ecological analysis of the current species distribution for Germany is lacking. Between 2010 and 2013, a total of 1445 mosquitoes of the An. maculipennis complex were collected at 72 different sites in Germany. The samples comprise 722 single individuals as well as 723 individuals in 90 pools of up to 25 mosquitoes. All samples were analysed with newly developed species‐specific qPCR assays for the identification of the four German species using nucleotide differences within the internal transcribed spacer 2 (ITS2) ribosomal DNA. All gathered data were used for species distribution modelling. The overall prevalence of An. messeae s.l. was highest with 98.89% of all pools; An. daciae with 6.93% of all individuals and An. messeae s.s. with 69.53%. The prevalence of the other two species was relatively low: An. maculipennis s.s. with 13.30% of all individuals (6.67% of all pools) and An. atroparvus with 1.80% of all individuals (1.11% of all pools).     

Screening of different algae for green synthesis of gold nanoparticles

The cyanobacteria Phormidium valderianum, P. tenue and Microcoleus chthonoplastes and the green algae Rhizoclonium fontinale, Ulva intestinalis, Chara zeylanica and Pithophora oedogoniana were exposed to hydrogen tetrachloroaurate solution and were screened for their suitability for producing nano‐gold. All three cyanobacteria genera and two of the green algae (Rhizoclonium fontinale and Ulva intestinalis) produced gold nanoparticles intracellularly, confirmed by purple colouration of the thallus within 72?h of treatment at 20°C. Extracted nanoparticle solutions were examined by UV‐vis spectroscopy, transmission electron microscopy (TEM) and X‐ray diffractometry (XRD). XRD confirmed the reduction of Au (III) to Au (0). UV‐vis spectroscopy and TEM studies indicated the production of nanoparticles having different shapes and sizes. Phormidium valderianum synthesized mostly spherical nanoparticles, along with hexagonal and triangular nanoparticles, at basic and neutral pHs (pH 9 and pH 7, respectively). Medicinally important gold nanorods were synthesized (together with gold nanospheres) only by P. valderianum at acidic pH (pH 5); this was initially determined by two surface plasmon bands in UV‐vis spectroscopy and later confirmed by TEM. Spherical to somewhat irregular particles were produced by P. tenue and Ulva intestinalis (TEM studies). The UV‐vis spectroscopy of the supernatant of other algal extracts indicated the formation of mostly spherical particles. Production of gold nanoparticles by algae is more ecofriendly than purely chemical synthesis. However, the choice of algae is important: Chara zeylanica and Pithophora oedogoniana were found to be unable to produce nanoparticles.     

Comparative methods for association studies: a case study on metabolite variation in a Brassica rapa core collection

Background

Association mapping is a statistical approach combining phenotypic traits and genetic diversity in natural populations with the goal of correlating the variation present at phenotypic and allelic levels. It is essential to separate the true effect of genetic variation from other confounding factors, such as adaptation to different uses and geographical locations. The rapid availability of large datasets makes it necessary to explore statistical methods that can be computationally less intensive and more flexible for data exploration.

Methodology/Principal Findings

A core collection of 168 Brassica rapa accessions of different morphotypes and origins was explored to find genetic association between markers and metabolites: tocopherols, carotenoids, chlorophylls and folate. A widely used linear model with modifications to account for population structure and kinship was followed for association mapping. In addition, a machine learning algorithm called Random Forest (RF) was used as a comparison. Comparison of results across methods resulted in the selection of a set of significant markers as promising candidates for further work. This set of markers associated to the metabolites can potentially be applied for the selection of genotypes with elevated levels of these metabolites.

Conclusions/Significance

The incorporation of the kinship correction into the association model did not reduce the number of significantly associated markers. However incorporation of the STRUCTURE correction (Q matrix) in the linear regression model greatly reduced the number of significantly associated markers. Additionally, our results demonstrate that RF is an interesting complementary method with added value in association studies in plants, which is illustrated by the overlap in markers identified using RF and a linear mixed model with correction for kinship and population structure. Several markers that were selected in RF and in the models with correction for kinship, but not for population structure, were also identified as QTLs in two bi-parental DH populations.     

The Cladosporium fulvum resistance gene Cf-ECP3 is part of the Orion cluster on the short arm of tomato Chromosome 1

The resistance of tomato to the pathogenic fungus Cladosporiumfulvum complies with the gene-for-gene relationship. Race specificresistance is based on Cf-gene mediated recognition ofsecreted avirulence products, resulting in a hypersensitive response (HR).Besides the avirulence gene products, C. fulvum secretes anumber of extra cellular proteins (ECPs) into the apoplast. Two L.esculentum accessions have previously been identified that reactedwith a HR upon injection with purified ECP3. The corresponding resistance genedesignated Cf-ECP3 was mapped by using an F₂population composed of 192 plants from the cross of susceptible MoneyMaker toresistant L. esculentum G1.1153.Cf-ECP3 inherited monogenically, cosegragated with theChromosome 1 Cleaved Amplified Polymorphic Sequence (CAPS) marker CT116 and wasmapped accurately at Orion, a locus harbouring Cf-ECP2 inother genotypes. RFLP anaysis with a Cf-9 probe furtherdemonstrated cosegregation of Cf-ECP3 with anHcr9 (Homologue of Cladosporiumfulvumresistance gene Cf-9) indicating that this gene is likelyan Hcr9. Thus in addition to the Milky Way locusharbouringthe Cf-4, Cf-4A andCf-9 resistance genes targeted against AVR4, AVR4A andAVR9, Orion is another complex locus on the short arm of Chromosome 1 thatharbours at least two functional Cf-genes,Cf-ECP2 and Cf-ECP3, targeted againstthe fungal excreted proteins ECP2 and ECP3.     

Quantitative trait loci analysis of non-enzymatic glucosinolate degradation rates in Brassica oleracea during food processing

Epidemiological and mechanistic studies show health-promoting effects of glucosinolates and their breakdown products. In literature, differences in non-enzymatic glucosinolate degradation rates during food processing between different vegetables are described, which provide the basis for studying the genetic effects of this trait and breeding vegetables with high glucosinolate retention during food processing. Non-enzymatic glucosinolate degradation, induced by heat, was studied in a publicly available Brassica oleracea doubled haploid population. Data were modeled to obtain degradation rate constants that were used as phenotypic traits to perform quantitative trait loci (QTL) mapping. Glucosinolate degradation rate constants were determined for five aliphatic and two indolic glucosinolates. Degradation rates were independent of the initial glucosinolate concentration. Two QTL were identified for the degradation rate of the indolic glucobrassicin and one QTL for the degradation of the aliphatic glucoraphanin, which co-localized with one of the QTL for glucobrassicin. Factors within the plant matrix might influence the degradation of different glucosinolates in different genotypes. In addition to genotypic effects, we demonstrated that growing conditions influenced glucosinolate degradation as well. The study identified QTL for glucosinolate degradation, giving the opportunity to breed vegetables with a high retention of glucosinolates during food processing, although the underlying mechanisms remain unknown.     

Kinetics of Na(+) transport in necturus proximal tubule

The dependence of proximal tubular sodium and fluid readsorption on the Na(+) concentration of the luminal and peritubular fluid was studied in the perfused necturus kidney. Fluid droplets, separated by oil from the tubular contents and identical in composition to the vascular perfusate, were introduced into proximal tubules, reaspirated, and analyzed for Na(+) and [(14)C]mannitol. In addition, fluid transport was measured in short-circuited fluid samples by observing the rate of change in length of the split droplets in the tubular lumen. Both reabsorptive fluid and calculated Na fluxes were simple, storable functions of the perfusate Na(+) concentration (K(m) = 35-39 mM/liter, V(max) = 1.37 control value). Intracellular Na(+), determined by tissue analysis, and open-circuit transepithelial electrical potential differences were also saturable functions of extracellular Na(+). In contrast, net reabsorptive fluid and Na(+) fluxes were linearly dependent on intracellular Na(+) and showed no saturation, even at sharply elevated cellular sodium concentrations. These concentrations were achieved by addition of amphotericin B to the luminal perfusate, a maneuver which increased the rate of Na(+) entry into the tubule cells and caused a proportionate rise in net Na(+) flux. It is concluded that active peritubular sodium transport in proximal tubule cells of necturus is normally unsaturated and remains so even after amphotericin-induced enhancement of luminal Na(+) entry. Transepithelial movement of NaCl may be described by a model with a saturable luminal entry step of Na(+) or NaCl into the cell and a second, unsaturated active transport step of Na(+) across the peritubular cell boundary.