Chromosomal location of a <Emphasis Type="Italic">Triticum dicoccoides</Emphasis>-derived powdery mildew resistance gene in common wheat by using microsatellite markers

The powdery mildew resistance has been transferred from an Israeli wild emmer (Triticum dicoccoides) accession "G-305-M" into common wheat by crossing and backcrossing (G-305-M/781//Jing 411*3). Genetic analysis showed that the resistance was controlled by a single dominant gene at the seedling stage. Among the 102 pairs of SSR primers tested, four polymorphic microsatellite markers (Xpsp3029, Xpsp3071, Xpsp3152 and Xgwm570) from the long arm of chromosome 6A were mapped in a BC(2)F(3) population segregating for powdery mildew resistance and consisting of 167 plants. The genetic distances between the resistance gene and these four markers were: 0.6 cM to Xpsp3029, 3.1 cM to Xpsp3071, 11.2 cM to Xpsp3152 and 20.4 cM to Xgwm570, respectively. The order of these microsatellite loci agreed well with the established microsatellite map of chromosome arm 6AL. We concluded that the resistance gene was located on the long arm of chromosome 6AL. Based on the origin and chromosomal location of the gene, it is suggested that the resistance gene derived from "G-305-M" is a novel powdery mildew resistance gene and is temporarily designated MlG.     

High-temperature adult-plant (HTAP) stripe rust resistance gene Yr36 from Triticum turgidum ssp. dicoccoides is closely linked to the grain protein content locus Gpc-B1

Several new races of the stripe rust pathogen have become frequent throughout the wheat growing regions of the United States since 2000. These new races are virulent to most of the wheat seedling resistance genes limiting the resistance sources that can be used to combat this pathogen. High-temperature adult-plant (HTAP) stripe rust resistance has proven to be more durable than seedling resistance due to its non-race-specific nature, but its use is limited by the lack of mapping information. We report here the identification of a new HTAP resistance gene from Triticum turgidum ssp. dicoccoides (DIC) designated as Yr36. Lines carrying this gene were susceptible to almost all the stripe rust pathogen races tested at the seedling stage but showed adult-plant resistance to the prevalent races in California when tested at high diurnal temperatures. Isogenic lines for this gene were developed by six backcross generations. Field tests in two locations showed increased levels of field resistance to stripe rust and increased yields in isogenic lines carrying the Yr36 gene compared to those without the gene. Recombinant substitution lines of chromosome 6B from DIC in the isogenic background of durum cv. Langdon were used to map the Yr36 gene on the short arm of chromosome 6B completely linked to Xbarc101, and within a 2-cM interval defined by PCR-based markers Xucw71 and Xbarc136. Flanking locus Xucw71 is also closely linked to the grain protein content locus Gpc-B1 (0.3-cM). Marker-assisted selection strategies are presented to improve stripe rust resistance and simultaneously select for high or low Gpc-B1 alleles.     

WAVE binds Ena/VASP for enhanced Arp2/3 complex–based actin assembly

The WAVE complex is the main activator of the Arp2/3 complex for actin filament nucleation and assembly in the lamellipodia of moving cells. Other important players in lamellipodial protrusion are Ena/VASP proteins, which enhance actin filament elongation. Here we examine the molecular coordination between the nucleating activity of the Arp2/3 complex and the elongating activity of Ena/VASP proteins for the formation of actin networks. Using an in vitro bead motility assay, we show that WAVE directly binds VASP, resulting in an increase in Arp2/3 complex–based actin assembly. We show that this interaction is important in vivo as well, for the formation of lamellipodia during the ventral enclosure event of Caenorhabditis elegans embryogenesis. Ena/VASP''s ability to bind F-actin and profilin-complexed G-actin are important for its effect, whereas Ena/VASP tetramerization is not necessary. Our data are consistent with the idea that binding of Ena/VASP to WAVE potentiates Arp2/3 complex activity and lamellipodial actin assembly.     

RAPD polymorphism of wild emmer wheat populations, Triticum dicoccoides, in Israel

 Genetic diversity in random amplified polymorphic DNAs (RAPDs) was studied in 110 genotypes of the tetraploid wild progenitor of wheat, Triticum dicoccoides, from 11 populations sampled in Israel and Turkey. Our results show high level of diversity of RAPD markers in wild wheat populations in Israel. The ten primers used in this study amplified 59 scorable RAPD loci of which 48 (81.4%) were polymorphic and 11 monomorphic. RAPD analysis was found to be highly effective in distinguishing genotypes of T. dicoccoides originating from diverse ecogeographical sites in Israel and Turkey, with 95.5% of the 100 genotypes correctly classified into sites of origin by discriminant analysis based on RAPD genotyping. However, interpopulation genetic distances showed no association with geographic distance between the population sites of origin, negating a simple isolation by distance model. Spatial autocorrelation of RAPD frequencies suggests that migration is not influential. Our present RAPD results are non-random and in agreement with the previously obtained allozyme patterns, although the genetic diversity values obtained with RAPDs are much higher than the allozyme values. Significant correlates of RAPD markers with various climatic and soil factors suggest that, as in the case of allozymes, natural selection causes adaptive RAPD ecogeographical differentiation. The results obtained suggest that RAPD markers are useful for the estimation of genetic diversity in wild material of T. dicoccoides and the identification of suitable parents for the development of mapping populations for the tagging of agronomically important traits derived from T. dicoccoides. Received: 13 July 1998 / Accepted: 13 August 1998     

Detection of divinyl ether synthase in Lily-of-the-Valley (Convallaria majalis) roots

Incubations of linoleic acid with cell-free preparations from Lily-of-the-Valley (Convallaria majalis L., Ruscaceae) roots revealed the presence of 13-lipoxygenase and divinyl ether synthase (DES) activities. Exogenous linoleic acid was metabolized predominantly into (9Z,11E,1′E)-12-(1′-hexenyloxy)-9,11-dodecadienoic (etheroleic) acid. Its identification was confirmed by the data of ultraviolet spectroscopy, mass spectra, ¹H NMR, COSY, catalytic hydrogenation. The isomeric divinyl ether (8E,1′E,3′Z)-12-(1′,3′-nonadienyloxy)-8-nonenoic (colneleic) acid was detected as a minor product. Incubations with linoleic acid hydroperoxides revealed that 13-hydroperoxide was a preferential substrate, while the 9-hydroperoxide was utilized with lesser efficiency.     

Very high mutation rate in offspring of Chernobyl accident liquidators

Exposure to ionizing radiation has long been suspected to increase mutation load in humans. Nevertheless, such events as atomic bombing seem not to have yielded significant genetic defects. The Chernobyl accident created a different, long-term exposure to radiation. Clean-up teams (or 'liquidators') of the Chernobyl reactor are among those who received the highest doses, presumably in some combination of acute and chronic forms. In this study, children born to liquidator families (currently either in the Ukraine or Israel) conceived after (CA) parental exposure to radiation were screened for the appearance of new fragments using multi-site DNA fingerprinting. Their sibs conceived before (CB) exposure served as critical internal controls, in addition to external controls (non-exposed families). An unexpectedly high (sevenfold) increase in the number of new bands in CA individuals compared with the level seen in controls was recorded. A strong tendency for the number of new bands to decrease with elapsed time between exposure and offspring conception was established for the Ukrainian families. These results indicate that low doses of radiation can induce multiple changes in human germline DNA.     

In Silico Molecular Comparisons of C. elegans and Mammalian Pharmacology Identify Distinct Targets That Regulate Feeding

Phenotypic screens can identify molecules that are at once penetrant and active on the integrated circuitry of a whole cell or organism. These advantages are offset by the need to identify the targets underlying the phenotypes. Additionally, logistical considerations limit screening for certain physiological and behavioral phenotypes to organisms such as zebrafish and C. elegans. This further raises the challenge of elucidating whether compound-target relationships found in model organisms are preserved in humans. To address these challenges we searched for compounds that affect feeding behavior in C. elegans and sought to identify their molecular mechanisms of action. Here, we applied predictive chemoinformatics to small molecules previously identified in a C. elegans phenotypic screen likely to be enriched for feeding regulatory compounds. Based on the predictions, 16 of these compounds were tested in vitro against 20 mammalian targets. Of these, nine were active, with affinities ranging from 9 nM to 10 µM. Four of these nine compounds were found to alter feeding. We then verified the in vitro findings in vivo through genetic knockdowns, the use of previously characterized compounds with high affinity for the four targets, and chemical genetic epistasis, which is the effect of combined chemical and genetic perturbations on a phenotype relative to that of each perturbation in isolation. Our findings reveal four previously unrecognized pathways that regulate feeding in C. elegans with strong parallels in mammals. Together, our study addresses three inherent challenges in phenotypic screening: the identification of the molecular targets from a phenotypic screen, the confirmation of the in vivo relevance of these targets, and the evolutionary conservation and relevance of these targets to their human orthologs.     

Wheat syntenome unveils new evidences of contrasted evolutionary plasticity between paleo‐ and neoduplicated subgenomes

Bread wheat derives from a grass ancestor structured in seven protochromosomes followed by a paleotetraploidization to reach a 12 chromosomes intermediate and a neohexaploidization (involving subgenomes A, B and D) event that finally shaped the 21 modern chromosomes. Insights into wheat syntenome in sequencing conserved orthologous set (COS) genes unravelled differences in genomic structure (such as gene conservation and diversity) and genetical landscape (such as recombination pattern) between ancestral as well as recent duplicated blocks. Contrasted evolutionary plasticity is observed where the B subgenome appears more sensitive (i.e. plastic) in contrast to A as dominant (i.e. stable) in response to the neotetraploidization and D subgenome as supra‐dominant (i.e. pivotal) in response to the neohexaploidization event. Finally, the wheat syntenome, delivered through a public web interface PlantSyntenyViewer at http://urgi.versailles.inra.fr/synteny-wheat , can be considered as a guide for accelerated dissection of major agronomical traits in wheat.     

A population-based analysis of the impact of the COVID-19 pandemic on common abdominal and gynecological emergency department visits

BACKGROUND:Reduced use of the emergency department during the COVID-19 pandemic may result in increased disease acuity when patients do seek health care services. We sought to evaluate emergency department visits for common abdominal and gynecologic conditions before and at the beginning of the pandemic to determine whether changes in emergency department attendance had serious consequences for patients.METHODS:We conducted a population-based analysis using administrative data to evaluate the weekly rate of emergency department visits pre-COVID-19 (Jan. 1–Mar. 10, 2020) and during the beginning of the COVID-19 pandemic (Mar. 11–June 30, 2020), compared with a historical control period (Jan. 1–July 1, 2019). All residents of Ontario, Canada, presenting to the emergency department with appendicitis, cholecystitis, ectopic pregnancy or miscarriage were included. We evaluated weekly incidence rate ratios (IRRs) of emergency department visits, management strategies and clinical outcomes.RESULTS:Across all study periods, 39 691 emergency department visits met inclusion criteria (40.2 % appendicitis, 32.1% miscarriage, 21.3% cholecystitis, 6.4% ectopic pregnancy). Baseline characteristics of patients presenting to the emergency department did not vary across study periods. After an initial reduction in emergency department visits, presentations for cholecystitis and ectopic pregnancy quickly returned to expected levels. However, presentations for appendicitis and miscarriage showed sustained reductions (IRR 0.61–0.80), with 1087 and 984 fewer visits, respectively, after the start of the pandemic, relative to 2019. Management strategies, complications and mortality rates were similar across study periods for all conditions.INTERPRETATION:Although our study showed evidence of emergency department avoidance in Ontario during the first wave of the COVID-19 pandemic, no adverse consequences were evident. Emergency care and outcomes for patients were similar before and during the pandemic.

Avoidance of the emergency department for conditions that may require urgent surgery has been a global concern during the COVID-19 pandemic, and could result in higher case severity and morbidity.^1–3 Resource constraints and provider concerns around the safety of surgery^4–6 may influence rates of nonoperative management for abdominal and gynecological emergencies,⁷ even when existing nonoperative options are not optimal. Limited data suggest that patients with appendicitis and cholecystitis, the 2 most common abdominal emergencies that routinely require operative management,^8,9 may be more likely to avoid the hospital,¹⁰ present with more severe illness^9,10 and be managed nonoperatively during the pandemic, with uncertain consequences for patient outcomes.^10–13 Similarly, the management of early pregnancy complications (i.e., miscarriage and ectopic pregnancy) may be medical or surgical, depending on patient preference and pregnancy characteristics (e.g., stability, gestational age).¹⁴ Up to 80% of women experiencing miscarriage routinely access emergency services; however, there are concerns that women requiring emergency care for miscarriages are avoiding the emergency department.¹⁵ Reduced access to emergency care for early pregnancy complications may result in more adverse outcomes; a study in Italy found an increased rate of ruptured ectopic pregnancy in the early months of the pandemic.¹⁶We sought to characterize the impact of COVID-19 on emergency department visits for and management of appendicitis, cholecystitis, miscarriage and ectopic pregnancy. We aimed to determine if there was a difference in the rate of patients presenting to the emergency department before and during the pandemic, whether a reduction in emergency department visits for these conditions resulted in adverse patient outcomes and whether the proportion of patients undergoing operative management differed before and during the pandemic.