Potential of microsatellites to distinguish four races of Fusarium oxysporum f. sp. ciceri prevalent in India

Fusarium oxysporum f. sp. ciceri, the causal agent of chickpea wilt, is an important fungal pathogen in India. Thirteen oligonucleotide probes complementary to microsatellite loci, in combination with 11 restriction enzymes, were used to assess the potential of such markers to study genetic variability in four Indian races of the pathogen. Hybridisation patterns, which were dependent upon both the restriction enzyme and oligonucleotide probe used, revealed the presence of different repeat motifs in the F. oxysporum f. sp. ciceri genome. Among the restriction enzymes used, hexa-cutting enzymes were more informative than tetra- and penta-cutting enzymes, whereas tetranucleotide and trinucleotide repeats yielded better hybridisation patterns than dinucleotide repeats. Dependent upon the levels of polymorphism detected, we have identified (AGT)5, (ATC)5 and (GATA)4 as the best fingerprinting probes for the F. oxysporum f. sp. ciceri races. The distribution of microsatellite repeats in the genome revealed races 1 and 4 to be closely related at a similarity index value of 76.6%, as compared to race 2 at a similarity value of 67.3%; race 3 was very distinct at a similarity value of 26.7%. Our study demonstrates the potential of oligonucleotide probes for fingerprinting and studying variability in the F. oxysporum f. sp. ciceri races and represents a step towards the identification of potential race diagnostic markers

Trends in DDT and pyrethroid resistance in Anopheles gambiae s.s. populations from urban and agro-industrial settings in southern Cameroon

Background: Pyrethroid insecticides are widely used for insect pest control in Cameroon. In certain insect species, particularly the malaria vector Anopheles gambiae, resistance to this class of insecticides is a source of great concern and needs to be monitored in order to sustain the efficacy of vector control operations in the fields. This study highlights trends in DDT and pyrethroid resistance in wild An. gambiae populations from South Cameroon. Methods: Mosquitoes were collected between 2001 and 2007 in four sites in South Cameroon, where insecticides are used for agricultural or personal protection purposes. Insecticide use was documented in each site by interviewing residents. Batches of 2-4 days old adult female mosquitoes reared from larval collections were tested for susceptibility to DDT, permethrin and deltamethrin using standard WHO procedures. Control, dead and survivors mosquitoes from bioassays were identified by PCR-RFLP and characterized for the kdr mutations using either the AS-PCR or the HOLA method. Results: Four chemical insecticide groups were cited in the study sites: organochlorines, organophosphates, carbamates and pyrethroids. These chemicals were used for personal, crop or wood protection. In the four An. gambiae populations tested, significant variation in resistance levels, molecular forms composition and kdr frequencies were recorded in the time span of the study. Increases in DDT and pyrethroid resistance, as observed in most areas, were generally associated with an increase in the relative frequency of the S molecular form carrying the kdr mutations at higher frequencies. In Mangoum, however, where only the S form was present, a significant increase in the frequency of kdr alleles between 2003 to 2007 diverged with a decrease of the level of resistance to DDT and pyrethroids. Analyses of the kdr frequencies in dead and surviving mosquitoes showed partial correlation between the kdr genotypes and resistance phenotypes, suggesting that the kdr mechanism may act with certain cofactors to be identified. Conclusion: These results demonstrate the ongoing spread of kdr alleles in An. gambiae in Central Africa. The rapid evolution of insecticide resistance in this highly dynamic and genetically polymorphic species remains a challenge for its control

Reduced antioxidant defense in early onset first-episode psychosis: a case-control study

Background:Our objective is to determine the activity of the antioxidant defense system at admission in patients with early onset first psychotic episodes compared with a control group. Methods: Total antioxidant status (TAS) and lipid peroxidation (LOOH) were determined in plasma. Enzyme activities and total glutathione levels were determined in erythrocytes in 102 children and adolescents with a first psychotic episode and 98 healthy controls. Results: A decrease in antioxidant defense was found in patients, measured as decreased TAS and glutathione levels. Lipid damage (LOOH) and glutathione peroxidase activity was higher in patients than controls. Our study shows a decrease in the antioxidant defense system in early onset first episode psychotic patients. Conclusions: Glutathione deficit seems to be implicated in psychosis, and may be an important indirect biomarker of oxidative stress in early-onset schizophrenia. Oxidative damage is present in these patients, and may contribute to its pathophysiology

Development and validation of new SSR markers from expressed regions in the garlic genome

Only a limited number of simple sequence repeat (SSR) markers is available for the genome of garlic (Allium sativum L.) despite the fact that SSR markers have become one of the most preferred DNA marker systems. To develop new SSR markers for the garlic genome, garlic expressed sequence tags (ESTs) at the publicly available GarlicEST database were screened for SSR motifs and a total of 132 SSR motifs were identified. Primer pairs were designed for 50 SSR motifs and 24 of these primer pairs were selected as SSR markers based on their consistent amplification patterns and polymorphisms. In addition, two SSR markers were developed from the sequences of garlic cDNA-AFLP fragments. The use of 26 EST-SSR markers for the assessment of genetic relationship was tested using 31 garlic genotypes. Twenty six EST-SSR markers amplified 130 polymorphic DNA fragments and the number of polymorphic alleles per SSR marker ranged from 2 to 13 with an average of 5 alleles. Observed heterozygosity and polymorphism information content (PIC) of the SSR markers were between 0.23 and 0.88, and 0.20 and 0.87, respectively. Twenty one out of the 31 garlic genotypes were analyzed in a previous study using AFLP markers and the garlic genotypes clustered together with AFLP markers were also grouped together with EST-SSR markers demonstrating high concordance between AFLP and EST-SSR marker systems and possible immediate application of EST-SSR markers for fingerprinting of garlic clones. EST-SSR markers could be used in genetic studies such as genetic mapping, association mapping, genetic diversity and comparison of the genomes of Allium species

Interview with Dileep Ranjekar, founder CEO, Azim Premji Foundation

The emerging markets and companies in South Asia have been getting increasing attention for their economic growth and prominence in world commerce. The social sector development is seen as key to accelerate their economic process and overall sustainabilit

Haemoglobin phenotypes in water buffalo (Bos bubalus) during development

The water buffalo has two foetal haemoglobins along with small amounts of adult components at birth. The structural differences between the two foetal haemoglobins are located in the α -chains and the two foetal haemoglobin types appear to be α21 γ2 and α211γ 2. Each adult buffalo has two haemoglobins with variant α-chains and which are of α21β 2 and α211β 2 Hb types. During post-natal development, the γ -chain is gradually replaced by the β -chain, the concentrations of α1 and α11 chains remaining, more or less, constant. A duplcation of the α-chain gene followed by mutation is assumed to account for the presence of two variant α-chain genes which are expressed together in each water buffalo from birth through maturity

Comprehensive evaluation of in vitro antioxidant activity, total phenols and chemical profiles of two commercially important strawberry varieties

Strawberry is one of the most popular fruits globally because of its color, texture, and aroma. Previous studies have shown that the fruits are rich in antioxidant compounds like flavonoids, anthocyanins and proanthocyanins. We, for the first time, comprehensively evaluated the total phenol content, and antioxidant activity (based on 1,1-diphenyl-2-picrylhydrazyl (DPPH) free-radical scavenging, anti-lipid peroxidation and ferric reduction potential (FRP) assay) of two popular strawberry cultivars namely, Sweet Charlie and Camarosa, at four different fruit developmental stages. A significant decrease in phenol content (nearly 89%) was observed in ripened fruits as compared to green fruits. The antioxidant potential, as evidenced by DPPH and FRP assays, increased gradually during fruit maturation with dose-dependent increase in activity. The EC50 values for DPPH and FRP assays ranged from 23.71±6.40% to 296.85±3.50% and 120.06±4.9μg to 219.50±1.0μg, respectively. The anti-lipid peroxidation assay also revealed a steady increase in activity from green to red fruit. The HPLC-DAD profiling of fruits revealed stage-specific chemical patterns during the four stages of fruit development. We studied the changes in concentrations of Chlorogenic acid, Catechin, Rutin and Quercetin during fruit developmental stages. It was clearly demonstrated that the antioxidant activity varied during fruit maturation stages. Maximum antioxidants were found to accumulate during the fruit ripening stage. To the best of our knowledge, this is the first report of such a comprehensive analysis of antioxidant potential of strawberry fruits from commercial varieties in India

Novel DNA sequence organization in rice genome

DNA sequence organization in rice genome has been investigated by studying the extent of DNA reassociation as a function of DNA fragment size. The reassociation kinetics curves indicate that there is no sequence interspersion of repeated and single-copy sequences at a DNA length of 6500 nucleotide pairs. The reassociation at lower C0t values, however, shows that there is an interspersion of DNA sequences within the repetitive DNA fraction. The size distribution of the repeated sequences is determined by agarose gel electrophoresis of C0t 50 DNA fraction of 6500-nucleotide-pair-long rice DNA digested with S1 nuclease. About 35-40% of the S1-resistant duplexes consist of 6000-6400 nucleotide pairs and 60-65% have a fragment size less than 150 nucleotide pairs. Among plants, rice is the first genome in which no DNA sequence interspersion is observed

Detection of genetic variability in pearl millet downy mildew (Sclerospora graminicola) by AFLP

Downy mildew, caused by Sclerospora graminicola, is an economically important disease of pearl millet in the semiarid regions of Asia and Africa. Amplified restriction fragment length polymorphism (AFLP) was used to detect the extent of genomic variation among 19 fungal isolates from different cultivars of pearl millet grown in various regions of India. Fourteen AFLP primer combinations produced 184 polymorphic bands. An unweighted pair-group method of averages cluster analysis represented by dendrogram and principal coordinate analysis separated the mildew collections into four distinct groups. Isolates having characteristic opposite mating abilities, geographic relatedness, virulence, common host cultivars, and changes through asexual generations reflected heterogeneity of the pathogen. The use of AFLP to detect genetic variation is particularly important in selecting mildew isolates to screen breeding material for identification of resistant millet and monitoring changes in S. graminicola in relation to changes in host for effective disease managemen