Search

Sesame (Sesamum indicumL.) is one of the oldest and most nutritional oilseed crops, of which domestication history has been poorly understood. This study suggested that sesame has undergone domestication bottleneck during its use for a long time. In this investigation, the molecular analysis included 4.4 Mbp of the genomic DNA of sesame comprising stearoyl acyl desaturase (sad), fatty acid desaturase 2 (fad2) and omega 3 fatty acid desaturase (o3fad) genes in 99 accessions of four populations of sesame germplasm namely: wild species, landraces, improved cultivars and introgressed lines. Results indicated that the improved cultivars and landraces lost 46.6 and 36.7% of nucleotide diversity, respectively, which indicate that the genetic diversity of the crop had been eroded due to selection after domestication. However, there was no significant reduction in genetic diversity of improved cultivars compared with landraces, indicating that unique improved cultivars generated through crosses were of less frequency in this population. Moreover, introgressed lines retained only 17.77% (π) and 4.57% (θ) of landrace diversity. To evaluate the impact of selection across fatty acid biosynthetic pathway, individual nucleotide diversity at three major genes involved in the pathway was surveyed. The analysis between wild and improved cultivars supported positive selection infad2ando3fadloci. Though locus-to-locus sequence variation was observed, positive results with two most important loci supported selection after domestication. Reduced diversity in these critical quality governing genes in improved cultivars suggested that future sesame cultivation would benefit from the incorporation of alleles from sesame's wild relatives.

Dark patches of charnockitic rocks characterized by orthopyroxene occur within garnetiferous granite gneisses (leptynites) in a granulite-migmatite suite around the Chilka Lake, Orissa, within the Eastern Ghats belt in the Indian Precambrian. Analysis of structures of different scales observed in this terrain establishes the presence of three phases of deformation. S1 is pervasive in the metapelitic granulites (mainlykhondalite), while in the migmatite complex composed of leptynites, charnockites and quartzofeldspathic veins, S1 is present exclusively within the charnockite lenses and bands, and shows different stages of obliteration in the associated leptynites. Thus, the charnockite patches must be earlier than the surrounding migmatitic rocks. The charnockite patches and the surrounding leptynitic gneisses are chemically quite different and the two rock types are not related by any prograde or retrograde transformation. The shapes and disposition of charnockite patches in the mixed exposures are found to be largely controlled by the third phase of folding and locally associated shearing. The kinematics of this late deformation are not favourable for fluid ingress from deeper levels.

The mechanism of feeding in ticks has been fully described in numerous text-books. Briefly, it is believed to be as follows: After the tick has fixed itself on the host's body by means of the denticles on the ventral surface of the hypostome, the chelicerae, or the so-called mandibles, are brought into action, and the “protrusion and retraction of the shaft, together with the extension of the teeth on the digits, results in a saw-like movement which tears a hole in the skin” (Patton and Cragg, 1913). More recently, Sharif (1928) has suggested the possibility that the actual incisions in the skin of the host are, as a rule, made by the cheliceral digits and that through the incisions thus made, the proboscis (i.e. the chelicerae and the hypostome collectively) is pushed into the deeper tissues.