Assessing the Potential of Using the Langdon 5D(5B) Substitution Line for the Introgression of Aegilops tauschii Into Durum Wheat.

Aegilops tauschii, the D-genome donor of hexaploid wheat, provides a source of genetic variation that could be used for tetraploid (durum) wheat improvement. In addition to the genes for wheat quality on the D-genome, which differentiate between bread and durum wheats in terms of end-use properties, genes coding for resistances to biotic and abiotic stresses are also present on the D-genome which would be useful in durum wheat. The introgression of Ae. tauschii into durum wheat, however, requires cytogenetic manipulation to induce homoeologous chromosome pairing to promote recombination. For this purpose, the introgression of Ae. tauschii into durum wheat was performed through a bridge cross of the wild species to the Langdon 5D(5B) disomic substitution line that lacks the Ph1 locus present on chromosome 5B, followed by a cross of the F1 to the durum wheat cultivar Om Rabi 5. Subsequent generations were self-fertilized, and these were screened for D-genome introgressions using (i) D-genome-specific Kompetitive Allele-Specific PCR (KASP) markers and (ii) KASP markers polymorphic between the 5D chromosomes of wheat, present in the Langdon 5D(5B) substitution line, and of Ae. tauschii. Homozygous introgression lines were confirmed using genomic and fluorescence in situ hybridization. The results showed that the use of the Langdon 5D(5B) disomic substitution line did not promote D-genome introgression across all linkage groups with only a limited success in the introgression of Ae. tauschii 5D segments into durum wheat.

Introgression of the Triticum timopheevii Genome Into Wheat Detected by Chromosome-Specific Kompetitive Allele Specific PCR Markers.

Triticum timopheevii (2n = 28, A t A t GG) is a tetraploid wild relative species with great potential to increase the genetic diversity of hexaploid wheat Triticum aestivum (2n = 42, AABBDD) for various important agronomic traits. A breeding scheme that propagated advanced backcrossed populations of wheat-T. timopheevii introgression lines through further backcrossing and self-fertilisation resulted in the generation of 99 introgression lines (ILs) that carried 309 homozygous segments from the A t and G subgenomes of T. timopheevii. These introgressions contained 89 and 74 unique segments from the A t and G subgenomes, respectively. These overlapping segments covered 98.9% of the T. timopheevii genome that has now been introgressed into bread wheat cv. Paragon including the entirety of all T. timopheevii chromosomes via varying sized segments except for chromosomes 3A t , 4G, and 6G. Homozygous ILs contained between one and eight of these introgressions with an average of three per introgression line. These homozygous introgressions were detected through the development of a set of 480 chromosome-specific Kompetitive allele specific PCR (KASP) markers that are well-distributed across the wheat genome. Of these, 149 were developed in this study based on single nucleotide polymorphisms (SNPs) discovered through whole genome sequencing of T. timopheevii. A majority of these KASP markers were also found to be T. timopheevii subgenome specific with 182 detecting A t subgenome and 275 detecting G subgenome segments. These markers showed that 98% of the A t segments had recombined with the A genome of wheat and 74% of the G genome segments had recombined with the B genome of wheat with the rest recombining with the D genome of wheat. These results were validated through multi-colour in situ hybridisation analysis. Together these homozygous wheat-T. timopheevii ILs and chromosome-specific KASP markers provide an invaluable resource to wheat breeders for trait discovery to combat biotic and abiotic stress factors affecting wheat production due to climate change.

Psychological peritraumatic risk factors for post-traumatic stress disorder in children and adolescents: A meta-analytic review.

BACKGROUND: Meta-analytic reviews concerning predictors of PTSD in children and adolescents have predominantly identified evidence relating to pre- and post-trauma risk factors; however, there is little evidence regarding peritraumatic risk factors. This paper comprised a systematic review and meta-analysis of studies exploring psychological peritraumatic risk factors for PTSD in youth. METHODS: Thirty-two studies were identified. Random effects meta-analyses were undertaken, with meta-regressions to explore the moderating role of study characteristics (gender, sex, timing of assessment after trauma, study quality, design and trauma type) on the size of effect of predictive factors. RESULTS: Peritraumatic subjective threat (k = 28; r = 0.37, 95% CI=0.31-0.42) yielded a medium effect size estimate, while dissociation (k = 5; r = 0.17, 95% CI=0.03-0.29) and data-driven processing (feeling muddled or confused during the trauma) (k = 2; r = 0.29, 95% CI=0.14-0.43) yielded smaller population effect size estimates for the relationship with PTSD symptoms. Perceived life threat yielded a medium sized effect (k = 12; r = 0.37, 95% CI=0.32-0.41). The relationship between subjective threat and PTSD symptoms was moderated by the percentage of female participants. Estimates of heterogeneity were high in studies assessing perceived threat and fear (I2 = 95%), but moderate and low within studies assessing dissociation and data-driven processing (I2 = 57% and 0%, respectively). LIMITATIONS: Peritraumatic psychological processes were commonly assessed using single-item measures. Studies primarily concerned single-incident traumas, limiting generalisability. CONCLUSIONS: Peritraumatic experiences, particularly relating to subjective threat, are important correlates of subsequent PTSD, which implicates timely assessment of these experiences in youth to inform identification of at-risk groups and implementation and design of intervention.

Asperity level characterization of abrasive wear using atomic force microscopy.

Using an atomic force microscope, a nanoscale wear characterization method has been applied to a commercial steel substrate AISI 52100, a common bearing material. Two wear mechanisms were observed by the presented method: atom attrition and elastoplastic ploughing. It is shown that not only friction can be used to classify the difference between these two mechanisms, but also the 'degree of wear'. Archard's Law of adhesion shows good conformity to experimental data at the nanoscale for the elastoplastic ploughing mechanism. However, there is a distinct discontinuity between the two identified mechanisms of wear and their relation to the load and the removed volume. The length-scale effect of the material's hardness property plays an integral role in the relationship between the 'degree of wear' and load. The transition between wear mechanisms is hardness-dependent, as below a load threshold limited plastic deformation in the form of pile up is exhibited. It is revealed that the presented method can be used as a rapid wear characterization technique, but additional work is necessary to project individual asperity interaction observations to macroscale contacts.

Development of Wheat-Aegilops caudata Introgression Lines and Their Characterization Using Genome-Specific KASP Markers.

Aegilops caudata L. [syn. Ae. markgrafii (Greuter) Hammer], is a diploid wild relative of wheat (2n = 2x = 14, CC) and a valuable source for new genetic diversity for wheat improvement. It has a variety of disease resistance factors along with tolerance for various abiotic stresses and can be used for wheat improvement through the generation of genome-wide introgressions resulting in different wheat-Ae. caudata recombinant lines. Here, we report the generation of nine such wheat-Ae. caudata recombinant lines which were characterized using wheat genome-specific KASP (Kompetitive Allele Specific PCR) markers and multi-color genomic in situ hybridization (mcGISH). Of these, six lines have stable homozygous introgressions from Ae. caudata and will be used for future trait analysis. Using cytological techniques and molecular marker analysis of the recombinant lines, 182 KASP markers were physically mapped onto the seven Ae. caudata chromosomes, of which 155 were polymorphic specifically with only one wheat subgenome. Comparative analysis of the physical positions of these markers in the Ae. caudata and wheat genomes confirmed that the former had chromosomal rearrangements with respect to wheat, as previously reported. These wheat-Ae. caudata recombinant lines and KASP markers are useful resources that can be used in breeding programs worldwide for wheat improvement. Additionally, the genome-specific KASP markers could prove to be a valuable tool for the rapid detection and marker-assisted selection of other Aegilops species in a wheat background.

Challenges in developing collaborative interdisciplinary research between gastroenterologists and engineers.

The role of technology in healthcare is rapidly evolving. However, it can be argued that gastroenterology has not kept pace with other medical fields due to the multifaceted needs of this speciality and other issues. Innovation in healthcare technology increasingly requires interdisciplinary collaboration between engineers and clinicians. Nevertheless, working in such an interdisciplinary environment can be challenging due to factors such as working culture, communication and difference in priorities. We surveyed the views of clinicians specialising in gastroenterology and engineers on interdisciplinary health research. The 21 respondents expressed a range of opinions on the perceived benefits and challenges of interdisciplinary collaboration. Though engineers and clinicians recognised its advantages, they expressed a need for further improvement. However, engineers and clinicians differed in how best this could be achieved. The results of this survey are discussed with reference to the literature on interdisciplinary collaboration.