Molecular tagging of a rust resistance gene in cultivated groundnut (Arachis hypogaea L.) introgressed from Arachis cardenasii

Rust is a serious and the most prevalent groundnut disease in tropical and subtropical growing regions of the world. A total of 164 recombinant inbred lines derived from resistant (VG 9514) and susceptible (TAG 24) cultivated groundnut parents were screened for rust resistance in five environments. Subsequent genotyping of these lines with 109 simple sequence repeat (SSR) markers generated a genetic linkage map with 24 linkage groups. The total length of the linkage map was 882.9 cM with an average of 9.0 cM between neighbouring markers. The markers pPGPseq4A05 and gi56931710 flanked the rust resistance gene at map distances of 4.7 cM and 4.3 cM, respectively, in linkage group 2. The significant association of these two markers with the rust reaction was also confirmed by discriminant analysis. The informative SSR markers classified rust-resistant and susceptible groups with 99.97% correctness. The SSR markers pPGPseq4A05 and gi56931710 were able to identify all the susceptible genotypes from a set of 20 cultivated genotypes differing in rust reaction. Tagging of the rust resistance locus with linked SSR markers will be useful in selecting the rust resistant genotypes from segregating populations and in introgressing the rust resistance genes from diploid wild species.     

Amyloid-Like Fibril Formation by Tachykinin Neuropeptides and Its Relevance to Amyloid β-Protein Aggregation and Toxicity

Protein aggregation and amyloid formation are associated with both pathological conditions in humans such as Alzheimer's disease and native functions such as peptide hormone storage in the pituitary secretory granules in mammals. Here, we studied amyloid fibrils formation by three neuropeptides namely physalaemin, kassinin and substance P of tachykinin family using biophysical techniques including circular dichroism, thioflavin T, congo red binding and microscopy. All these neuropeptides under study have significant sequence similarity with Aβ(25-35) that is known to form neurotoxic amyloids. We found that all these peptides formed amyloid-like fibrils in vitro in the presence of heparin, and these amyloids were found to be nontoxic in neuronal cells. However, the extent of amyloid formation, structural transition, and morphology were different depending on the primary sequences of peptide. When Aβ(25-35) and Aβ40 were incubated with each of these neuropeptides in 1:1 ratio, a drastic increase in amyloid growths were observed compared to that of individual peptides suggesting that co-aggregation of Aβ and these neuropeptides. The electron micrographs of these co-aggregates were dissimilar when compared with individual peptide fibrils further supporting the possible incorporation of these neuropeptides in Aβ amyloid fibrils. Further, the fibrils of these neuropeptides can seed the fibrils formation of Aβ40 and reduced the toxicity of preformed Aβ fibrils. The present study of amyloid formation by tachykinin neuropeptides is not only providing an understanding of the mechanism of amyloid fibril formation in general, but also offering plausible explanation that why these neuropeptide might reduce the cytotoxicity associated with Alzheimer's disease related amyloids.     

Molecular interpretation of ACTH-β-endorphin coaggregation: relevance to secretory granule biogenesis

Peptide/protein hormones could be stored as non-toxic amyloid-like structures in pituitary secretory granules. ACTH and β-endorphin are two of the important peptide hormones that get co-stored in the pituitary secretory granules. Here, we study molecular interactions between ACTH and β-endorphin and their colocalization in the form of amyloid aggregates. Although ACTH is known to be a part of ACTH-β-endorphin aggregate, ACTH alone cannot aggregate into amyloid under various plausible conditions. Using all atom molecular dynamics simulation we investigate the early molecular interaction events in the ACTH-β-endorphin system, β-endorphin-only system and ACTH-only system. We find that β-endorphin and ACTH formed an interacting unit, whereas negligible interactions were observed between ACTH molecules in ACTH-only system. Our data suggest that ACTH is not only involved in interaction with β-endorphin but also enhances the stability of mixed oligomers of the entire system.     

伊朗针蓟马亚科及其一新纪录属——滑胸针蓟马属（缨翅目）

针蓟马亚科是蓟马科中已经报道的4个亚科之一,该亚科在伊朗已知5属6种。本文首次报道了伊朗发现的单种属——滑胸针蓟马属Selenothrips Karny及其模式种——红带滑胸针蓟马Selenothrips rubrocinctus(Giard),并编制了针蓟马亚科6个属的检索表,对每个属进行了描述,并对7个种在伊朗的地理分布进行了报道。     

Transgenic approaches for genetic improvement in groundnut (Arachis hypogaea L.) against major biotic and abiotic stress factors

Cultivated groundnut (Arachis hypogaea L.) is considered as one of the primary oilseed crops and a major fodder for cattle industry in most of the developing countries, owing to its rich source of protein. It is due to its geocarpic nature of growth that the overall yield performance of groundnut is hindered by several biotic and abiotic stress factors. Multidimensional attempts were undertaken to combat these factors by developing superior groundnut varieties, modified with integral mechanism of tolerance/resistance; however this approach proved to be futile, owing to inferior pod and kernel quality. As a superior alternative, biotechnological intervention like transformation of foreign genes, either directly (biolistic) or via Agrobacterium, significantly aided in the development of advanced groundnut genotypes equipped with integral resistance against stresses and enhanced yield attributing traits. Several genes triggered by biotic and abiotic stresses, were detected and some of them were cloned and transformed as major parts of transgenic programmes. Application of modern molecular biological techniques, in designing biotic and abiotic stress tolerant/resistant groundnut varieties that exhibited mechanisms of resistance, relied on the expression of specific genes associated to particular stress. The genetically transformed stress tolerant groundnut varieties possess the potential to be employed as donor parents in traditional breeding programmes for developing varieties that are resilient to fungal, bacterial, and viral diseases, as well as to draught and salinity. The present review emphasizes on the retrospect and prospect of genetic transformation tools, implemented for the enhancement of groundnut varieties against key biotic and abiotic stress factors.     

Bacterial inclusion bodies contain amyloid-like structure

Protein aggregation is a process in which identical proteins self-associate into imperfectly ordered macroscopic entities. Such aggregates are generally classified as amorphous, lacking any long-range order, or highly ordered fibrils. Protein fibrils can be composed of native globular molecules, such as the hemoglobin molecules in sickle-cell fibrils, or can be reorganized beta-sheet-rich aggregates, termed amyloid-like fibrils. Amyloid fibrils are associated with several pathological conditions in humans, including Alzheimer disease and diabetes type II. We studied the structure of bacterial inclusion bodies, which have been believed to belong to the amorphous class of aggregates. We demonstrate that all three in vivo-derived inclusion bodies studied are amyloid-like and comprised of amino-acid sequence-specific cross-beta structure. These findings suggest that inclusion bodies are structured, that amyloid formation is an omnipresent process both in eukaryotes and prokaryotes, and that amino acid sequences evolve to avoid the amyloid conformation.     

A microsatellite study to disentangle the ambiguity of linguistic,geographic, ethnic and genetic influences on tribes of India to get a better clarity of the antiquity and peopling of South Asia

An understanding of the genetic affinity and the past history of the tribal populations of India requires the untangling of the confounding influences of language, ethnicity, and geography on the extant diverse tribes. The present study examines the genetic relationship of linguistically (Dravidian, Austro‐Asiatic, and Tibeto‐Burman) and ethnically (Australian and East Asian) diverse tribal populations (46) inhabiting different regions of the Indian subcontinent. For the purpose, we have utilized the published data on allele frequency of 15 autosomal STR loci of our study on six Adi sub‐tribes of Arunachal Pradesh and compared the same with the reported allele frequency data, for nine common autosomal STR loci, of 40 other tribes. Phylogenetic and principal component analyses exhibit geography based clustering of Tibeto‐Burman speakers and separation of the Mundari and Mon‐Khmer speaking Austro‐Asiatic populations. The combined analyses of all 46 populations show clustering of the groups belonging to same ethnicity and inhabiting contiguous geographic regions, irrespective of their different languages. These results help us to reconstruct and understand three plausible scenarios of the antiquity of Indian tribal populations: the Dravidian and Austro‐Asiatic (Mundari) tribes were possibly derived from common early settlers; the Tibeto‐Burman tribes possibly belonged to a different ancestry and the Mon‐Khmer speaking Austro‐Asiatic populations share a common ancestry with some of the Tibeto‐Burman speakers. Am J Phys Anthropol, 2009. © 2009 Wiley‐Liss, Inc.