A simplified model of scar contraction

The healing of wounds is a complex process and the contraction of the resulting scar can have a negative impact on the neighbouring skin. A finite element model of skin simulating the contraction of a scar and deformation of the surrounding skin is presented. The skin is represented by an orthotropic–viscoelastic constitutive law, which is validated against experimental data in the literature. A simplified experimental model of a contracting scar in real skin is also developed. The pattern and size of the wrinkles formed around the contracting scar in the finite element model compare favourably with those formed in the experimental model. The orthotropic nature of skin plays a significant role in the behaviour of skin around scars—the wrinkles have a preferential orientation that corresponds to a direction perpendicular to the Langer's lines in the skin. The pre-stress in skin (a property that is ignored in many skin models) is shown to be an important factor in wrinkle formation around scars. The proposed model can be used to analyse the suturing and closure of wounds of various shapes.     

Allelic diversity associated with aridity gradient in wild emmer wheat populations

The association between allelic diversity and ecogeographical variables was studied in natural populations of wild emmer wheat [ Triticum turgidum ssp. dicoccoides (Körn.) Thell.], the tetraploid progenitor of cultivated wheat. Patterns of allelic diversity in 54 microsatellite loci were analyzed in a collection of 145 wild emmer wheat accessions representing 25 populations that were sampled across naturally occurring aridity gradient in Israel and surrounding regions. The obtained results revealed that 56% of the genetic variation resided among accessions within populations, while only 44% of the variation resided between populations. An unweighted pair-group method analysis (UPGMA) tree constructed based on the microsatellite allelic diversity divided the 25 populations into six major groups. Several groups were comprised of populations that were collected in ecologically similar but geographically remote habitats. Furthermore, genetic differentiation between populations was independent of the geographical distances. An interesting evolutionary phenomenon is highlighted by the unimodal relationship between allelic diversity and annual rainfall ( r  = 0.74, P  < 0.0002), indicating higher allelic diversity in populations originated from habitats with intermediate environmental stress (i.e. rainfall 350–550 mm year⁻¹). These results show for the first time that the 'intermediate-disturbance hypothesis', explaining biological diversity at the ecosystem level, also dominates the genetic diversity within a single species, the lowest hierarchical element of the biological diversity.     

Investigation on chlorosomal antenna geometries: tube,lamella and spiral-type self-aggregates

Molecular mechanics calculations and exciton theory have been used to study pigment organization in chlorosomes of green bacteria. Single and double rod, multiple concentric rod, lamella, and Archimedean spiral macrostructures of bacteriochlorophyll c molecules were created and their spectral properties evaluated. The effects of length, width, diameter, and curvature of the macrostructures as well as orientations of monomeric transition dipole moment vectors on the spectral properties of the aggregates were studied. Calculated absorption, linear dichroism, and polarization dependent fluorescence-excitation spectra of the studied long macrostructures were practically identical, but circular dichroism spectra turned out to be very sensitive to geometry and monomeric transition dipole moment orientations of the aggregates. The simulations for long multiple rod and spiral-type macrostructures, observed in recent high-resolution electron microscopy images (Oostergetel et al., FEBS Lett 581:5435–5439, 2007) gave shapes of circular dichroism spectra observed experimentally for chlorosomes. It was shown that the ratio of total circular dichroism intensity to integrated absorption of the Q _y transition is a good measure of degree of tubular structures in the chlorosomes. Calculations suggest that the broad Q _y line width of chlorosomes of sulfur bacteria could be due to (1) different orientations of the transition moment vectors in multi-walled rod structures or (2) a variety of Bchl-aggregate structures in the chlorosomes. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Overexpression of a TFIIIA-type zinc finger protein gene ZFP252 enhances drought and salt tolerance in rice (Oryza sativa L.)

We previously identified a salt and drought stress-responsive TFIIIA-type zinc finger protein gene ZFP252 from rice. Here we report the functional analysis of ZFP252 using gain- and loss-of-function strategies. We found that overexpression of ZFP252 in rice increased the amount of free proline and soluble sugars, elevated the expression of stress defense genes and enhanced rice tolerance to salt and drought stresses, as compared with ZFP252 antisense and non-transgenic plants. Our findings suggest that ZFP252 plays an important role in rice response to salt and drought stresses and is useful in engineering crop plants with enhanced tolerance to salt and drought stresses.     

DNA marker analysis for pyramided of Fusarium head blight (FHB) resistance QTLs from different germplasm

A pyramided FHB resistance line of wheat (WSY) was previously developed from three FHB resistant cultivars (Sumai 3, Wangshuibai, and Nobeokabouzu) in the Jiangsu Academy of Agricultural Sciences, China. In the present study, we analyzed the genetic relationship between WSY and the three parental cultivars using DNA markers in order to clarify how many and which resistance genes had accumulated in WSY. We analyzed 282 DNA markers from the 21 wheat chromosomes. WSY was found to include different chromosome regions that harbored putative FHB QTLs of the three parental germplasm. Haplotypes of DNA markers on these QTL regions revealed that the 1BL, 2BL, 5AS, and 7AL QTL regions were from Sumai 3, the 2AS, 2DS, 3AS, and 6BS QTL regions were from Wangshuibai, and the 3BS QTL region was from Nobeokabouzu. This study showed that different resistance genes from the different resistant germplasm had indeed accumulated in WSY. WSY is a potential resistant resource for FHB resistance in wheat breeding programs.     

<Emphasis Type="Italic">Mariner</Emphasis>-like elements in <Emphasis Type="Italic">Rhynchosciara americana</Emphasis> (Sciaridae) genome: molecular and cytological aspects

Two mariner-like elements, Ramar1 and Ramar2, are described in the genome of Rhynchosciara americana, whose nucleotide consensus sequences were derived from multiple defective copies containing deletions, frame shifts and stop codons. Ramar1 contains several conserved amino acid blocks which were identified, including a specific D,D(34)D signature motif. Ramar2 is a defective mariner-like element, which contains a deletion overlapping in most of the internal region of the transposase ORF while its extremities remain intact. Predicted transposase sequences demonstrated that Ramar1 and Ramar2 phylogenetically present high identity to mariner-like elements of mauritiana subfamily. Southern blot analysis indicated that Ramar1 is widely represented in the genome of Rhynchosciara americana. In situ hybridizations showed Ramar1 localized in several chromosome regions, mainly in pericentromeric heterochromatin and their boundaries, while Ramar2 appeared as a single band in chromosome A.