Micro-Heterogeneity and Micro-Rheological Properties of High-Viscosity Barley β-Glucan Solutions Studied by Diffusing Wave Spectroscopy (DWS)

Soluble fiber β-glucan is one of the key dietary materials in healthy food products known for reducing serum cholesterol levels. The micro-structural heterogeneity and micro-rheology of high-viscosity barley β-glucan solutions were investigated by the diffusing wave spectroscopy (DWS) technology. By comparing the mean-square displacement (MSD) of the microspheres imbedded in eight concentrations of β-glucan solutions, we found that the solutions exhibited nearly homogeneous behavior at ≤0.1 %, but the material showed a clear degree of heterogeneity at ≥0.25 %. Micro-rheology investigation revealed that β-glucan solutions displayed nearly perfect viscous behavior at ≤0.1 %, but the property changed into viscoelastic one at ≥0.25 %. The magnitude of high-frequency viscoelastic moduli for the 0.25 % - 0.75 % β-glucan solutions can be characterized by ?G*? ∝ ω^3/4, which is the semi-flexible polymer behavior. However, the magnitude of high-frequency viscoelastic moduli (?G*?) for the 1.0 % - 1.25 % β-glucan solutions is proportional to ω^1/2, which is the flexible polymer behavior. All micro-structural heterogeneity and micro-rheological property shifts occurred in relatively small concentration ranges.     

Electron microscopic and morphometric study of the effects of ENKAD preparation on photoreceptor cells of the retina in Campbell rats with hereditary retinal dystrophy

The drug , a complex of ribonucleotides, which was found to improve the vision in some patients with retinitis pigmentosa, stimulates the morphogenesis of rod outer segments (ROS) in mutant Campbell rats with inherent retinal dystrophy. Four litters of neonatal rats, which being subdivided into groups, were injected subcutaneously with either 0.1 ml of 3.5% drug (experimental group) or 0.1 ml of 0.9% NaCl (control group) daily for 6-7 days. The results were checked in posterior area of the retina at Day 7 by the method of electron microscopy and morphometry. The drug treatment resulted in the 12-20 per cent increase of ROS disc number as compared with that in control group. Therefore, photoreceptors are the first retinal cells to be stimulated by the complex of ribonucleotides in rats.     

Present-day and mid-Holocene biomes reconstructed from pollen and plant macrofossil data from the former Soviet Union and Mongolia

Fossil pollen data supplemented by tree macrofossil records were used to reconstruct the vegetation of the Former Soviet Union and Mongolia at 6000 years. Pollen spectra were assigned to biomes using the plant-functional-type method developed by Prentice et al . (1996). Surface pollen data and a modern vegetation map provided a test of the method. This is the first time such a broad-scale vegetation reconstruction for the greater part of northern Eurasia has been attempted with objective techniques. The new results confirm previous regional palaeoenvironmental studies of the mid-Holocene while providing a comprehensive synopsis and firmer conclusions. West of the Ural Mountains temperate deciduous forest extended both northward and southward from its modern range. The northern limits of cool mixed and cool conifer forests were also further north than present. Taiga was reduced in European Russia, but was extended into Yakutia where now there is cold deciduous forest. The northern limit of taiga was extended (as shown by increased Picea pollen percentages, and by tree macrofossil records north of the present-day forest limit) but tundra was still present in north-eastern Siberia. The boundary between forest and steppe in the continental interior did not shift substantially, and dry conditions similar to present existed in western Mongolia and north of the Aral Sea.     

Genetic dissection of drought tolerance in chickpea (Cicer arietinum L.)

Key message

Analysis of phenotypic data for 20 drought tolerance traits in 1–7 seasons at 1–5 locations together with genetic mapping data for two mapping populations provided 9 QTL clusters of which one present on CaLG04 has a high potential to enhance drought tolerance in chickpea improvement.

Abstract

Chickpea (Cicer arietinum L.) is the second most important grain legume cultivated by resource poor farmers in the arid and semi-arid regions of the world. Drought is one of the major constraints leading up to 50 % production losses in chickpea. In order to dissect the complex nature of drought tolerance and to use genomics tools for enhancing yield of chickpea under drought conditions, two mapping populations—ICCRIL03 (ICC 4958 × ICC 1882) and ICCRIL04 (ICC 283 × ICC 8261) segregating for drought tolerance-related root traits were phenotyped for a total of 20 drought component traits in 1–7 seasons at 1–5 locations in India. Individual genetic maps comprising 241 loci and 168 loci for ICCRIL03 and ICCRIL04, respectively, and a consensus genetic map comprising 352 loci were constructed (http://cmap.icrisat.ac.in/cmap/sm/cp/varshney/). Analysis of extensive genotypic and precise phenotypic data revealed 45 robust main-effect QTLs (M-QTLs) explaining up to 58.20 % phenotypic variation and 973 epistatic QTLs (E-QTLs) explaining up to 92.19 % phenotypic variation for several target traits. Nine QTL clusters containing QTLs for several drought tolerance traits have been identified that can be targeted for molecular breeding. Among these clusters, one cluster harboring 48 % robust M-QTLs for 12 traits and explaining about 58.20 % phenotypic variation present on CaLG04 has been referred as “QTL-hotspot”. This genomic region contains seven SSR markers (ICCM0249, NCPGR127, TAA170, NCPGR21, TR11, GA24 and STMS11). Introgression of this region into elite cultivars is expected to enhance drought tolerance in chickpea.     

PARALLEL EVOLUTION OF LOCAL ADAPTATION AND REPRODUCTIVE ISOLATION IN THE FACE OF GENE FLOW

Parallel evolution of similar phenotypes provides strong evidence for the operation of natural selection. Where these phenotypes contribute to reproductive isolation, they further support a role for divergent, habitat‐associated selection in speciation. However, the observation of pairs of divergent ecotypes currently occupying contrasting habitats in distinct geographical regions is not sufficient to infer parallel origins. Here we show striking parallel phenotypic divergence between populations of the rocky‐shore gastropod, Littorina saxatilis, occupying contrasting habitats exposed to either wave action or crab predation. This divergence is associated with barriers to gene exchange but, nevertheless, genetic variation is more strongly structured by geography than by ecotype. Using approximate Bayesian analysis of sequence data and amplified fragment length polymorphism markers, we show that the ecotypes are likely to have arisen in the face of continuous gene flow and that the demographic separation of ecotypes has occurred in parallel at both regional and local scales. Parameter estimates suggest a long delay between colonization of a locality and ecotype formation, perhaps because the postglacial spread of crab populations was slower than the spread of snails. Adaptive differentiation may not be fully genetically independent despite being demographically parallel. These results provide new insight into a major model of ecologically driven speciation.