Importance of temporal variability at different spatial scales for diversity of floodplain aquatic communities

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Phenotypic and genotypic intra-diversity among Anatolian durum wheat “Kunduru” landraces

Kunduru is an important Anatolian landrace having peculiar traits that are appreciated by farmers and breeders. 33 accessions known as Kunduru collected by ICARDA from six geographical provinces of Turkey, were used to study the phenotypic and genotypic intra-diversity. Kunduru landraces exhibited high intra-diversity for most of the studied morphological traits. GPC (12.10–14.90%), vitreousness (75–100%), TKW (31.80–56.70 g), YP (4.70–8.00 ppm), b*-value (14.30–19.50), ash content (1.60–2.0%) and gluten strength (14–60 ml) showed marked variations. Gliadin and glutenin banding patterns showed high polymorphism. 65 alleles were detected with 14 SSR markers, giving a mean of 6.77 alleles per locus. The average PIC value was 0.44 and ranged from 0.11 to 0.70. The average genetic distance between pairs of landraces was 0.47 and ranged between 0.11 and 0.72. This study showed that Kunduru landraces maintains high allelic variation. PCoA indicated that eco-geographical variables have a significant effect on SSR diversity as well as morphological traits. Many of the landraces studied are in danger of disappearing from the local farmers' fields; this study demonstrates the importance of maintaining and conserving this precious genetic resources.     

Nonfunctional alleles of long‐day suppressor genes independently regulate flowering time

Due to the remarkable adaptability to various environments, rice varieties with diverse flowering times have been domesticated or improved from Oryza rufipogon. Detailed knowledge of the genetic factors controlling flowering time will facilitate understanding the adaptation mechanism in cultivated rice and enable breeders to design appropriate genotypes for distinct preferences. In this study, four genes (Hd1, DTH8, Ghd7 and OsPRR37) in a rice long‐day suppression pathway were collected and sequenced in 154, 74, 69 and 62 varieties of cultivated rice (Oryza sativa) respectively. Under long‐day conditions, varieties with nonfunctional alleles flowered significantly earlier than those with functional alleles. However, the four genes have different genetic effects in the regulation of flowering time: Hd1 and OsPRR37 are major genes that generally regulate rice flowering time for all varieties, while DTH8 and Ghd7 only regulate regional rice varieties. Geographic analysis and network studies suggested that the nonfunctional alleles of these suppression loci with regional adaptability were derived recently and independently. Alleles with regional adaptability should be taken into consideration for genetic improvement. The rich genetic variations in these four genes, which adapt rice to different environments, provide the flexibility needed for breeding rice varieties with diverse flowering times.     

The orientation of insulin receptors in the red cell membrane

High-affinity binding of insulin to receptors in human erythrocyte membranes occurred at the external surface, but not at the cytoplasmic surface of the plasma membrane, as assessed by insulin binding to right-side-out and inside-out membrane vesicles. Even after prolonged (3 h) incubation at 22°C, binding at the cytoplasmic membrane aspect remained negligible. The data indicate that the insulin receptor displays its hormone-binding site exclusively toward the extracellular space and that transmembrane mobility (“flip-flop”) of the receptor from one to the other membrane leaflet is severely restricted.     

Superhelicity of nucleosomal DNA changes its double-helical repeat

Winding DNA in a superhelix can be considered a process consisting of two smooth deformations: bending and twisting. The extra twist angle introduced by winding DNA into the nucleosomal superhelix is calculated by means of the Crick formula to be −0.5° per base pair (bp). This is equivalent to a change of −0.15±0.015 bp in the DNA double-helical repeat. Free DNA in solution is known to have a helical repeat of 10.55±0.1 bp. On the other hand, a weighted average of various estimates of the DNA repeat in the nucleosome is 10.38±0.02. The difference happens to be perfectly accounted for by the superhelicity of the nucleosomal DNA. This implies that the latter is essentially nonconstrained.