Nuclear exchange generates population diversity in the wheat leaf rust pathogen Puccinia triticina.

In clonally reproducing dikaryotic rust fungi, non-sexual processes such as somatic nuclear exchange are postulated to play a role in diversity but have been difficult to detect due to the lack of genome resolution between the two haploid nuclei. We examined three nuclear-phased genome assemblies of Puccinia triticina, which causes wheat leaf rust disease. We found that the most recently emerged Australian lineage was derived by nuclear exchange between two pre-existing lineages, which originated in Europe and North America. Haplotype-specific phylogenetic analysis reveals that repeated somatic exchange events have shuffled haploid nuclei between long-term clonal lineages, leading to a global P. triticina population representing different combinations of a limited number of haploid genomes. Thus, nuclear exchange seems to be the predominant mechanism generating diversity and the emergence of new strains in this otherwise clonal pathogen. Such genomics-accelerated surveillance of pathogen evolution paves the way for more accurate global disease monitoring.

Health Professionals Should be Involved in Shaping Substance Use Disorder Policy.

: Health professionals should become actively involved in creating evidence based SUD policies as individuals; as members of advisory commissions; as advocates within professional associations and through participation in political campaigns as candidates, donors or activists.

The Surgeon General's Facing Addiction report: An historic document for health care.

The publication of Facing Addiction in America: The Surgeon General's Report on Alcohol, Drugs, and Health presents an historic moment not only for the field of addiction medicine, but also for the United States as a nation. The Board of Directors of the Association for Medical Education and Research in Substance Abuse (AMERSA), on behalf of our organization, would like to express our appreciation of the efforts of Dr. Vivek Murthy and the Surgeon General's Office to publish the first surgeon general's report covering substance misuse and substance use disorders.

Can citrate efflux from roots improve phosphorus uptake by plants? Testing the hypothesis with near-isogenic lines of wheat.

Phosphorus (P) deficiency in some plant species triggers the release of organic anions such as citrate and malate from roots. These anions are widely suggested to enhance the availability of phosphate for plant uptake by mobilizing sparingly-soluble forms in the soil. Carazinho is an old wheat (Triticum aestivum) cultivar from Brazil, which secretes citrate constitutively from its root apices, and here we show that it also produces relatively more biomass on soils with low P availability than two recent Australian cultivars that lack citrate efflux. To test whether citrate efflux explains this phenotype, we generated two sets of near-isogenic lines that differ in citrate efflux and compared their biomass production in different soil types and with different P treatments in glasshouse experiments and field trials. Citrate efflux improved relative biomass production in two of six glasshouse trials but only at the lowest P treatments where growth was most severely limited by P availability. Furthermore, citrate efflux provided no consistent advantage for biomass production or yield in multiple field trials. Theoretical modeling indicates that the effectiveness of citrate efflux in mobilizing soil P is greater as the volume of soil into which it diffuses increases. As efflux from these wheat plants is restricted to the root apices, the potential for citrate to mobilize sufficient P to increase shoot biomass may be limited. We conclude that Carazinho has other attributes that contribute to its comparatively good performance in low-P soils.

Transposon-mediated alteration of TaMATE1B expression in wheat confers constitutive citrate efflux from root apices.

The TaMATE1B gene (for multidrug and toxic compound extrusion) from wheat (Triticum aestivum) was isolated and shown to encode a citrate transporter that is located on the plasma membrane. TaMATE1B expression in roots was induced by iron deficiency but not by phosphorus deficiency or aluminum treatment. The coding region of TaMATE1B was identical in a genotype showing citrate efflux from root apices (cv Carazinho) to one that lacked citrate efflux (cv Egret). However, sequence upstream of the coding region differed between these two genotypes in two ways. The first difference was a single-nucleotide polymorphism located approximately 2 kb upstream from the start codon in cv Egret. The second difference was an 11.1-kb transposon-like element located 25 bp upstream of the start codon in cv Carazinho that was absent from cv Egret. The influence of these polymorphisms on TaMATE1B expression was investigated using fusions to green fluorescent protein expressed in transgenic lines of rice (Oryza sativa). Fluorescence measurements in roots of rice indicated that 1.5- and 2.3-kb regions upstream of TaMATE1B in cv Carazinho (which incorporated 3' regions of the transposon-like element) generated 20-fold greater expression in the apical 1 mm of root compared with the native promoter in cv Egret. By contrast, fluorescence in more mature tissues was similar in both cultivars. The presence of the single-nucleotide polymorphism alone consistently generated 2-fold greater fluorescence than the cv Egret promoter. We conclude that the transposon-like element in cv Carazinho extends TaMATE1B expression to the root apex, where it confers citrate efflux and enhanced aluminum tolerance.

Importance of pre-anthesis anther sink strength for maintenance of grain number during reproductive stage water stress in wheat.

Reproductive stage water stress leads to spikelet sterility in wheat. Whereas drought stress at anthesis affects mainly grain size, stress at the young microspore stage of pollen development is characterized by abortion of pollen development and reduction in grain number. We identified genetic variability for drought tolerance at the reproductive stage. Drought-tolerant wheat germplasm is able to maintain carbohydrate accumulation in the reproductive organs throughout the stress treatment. Starch depletion in the ovary of drought-sensitive wheat is reversible upon re-watering and cross-pollination experiments indicate that the ovary is more resilient than the anther. The effect on anthers and pollen fertility is irreversible, suggesting that pollen sterility is the main cause of grain loss during drought conditions in wheat. The difference in storage carbohydrate accumulation in drought-sensitive and drought-tolerant wheat is correlated with differences in sugar profiles, cell wall invertase gene expression and expression of fructan biosynthesis genes in anther and ovary (sucrose : sucrose 1-fructosyl-transferase, 1-SST; sucrose : fructan 6-fructosyl-transferase, 6-SFT). Our results indicate that the ability to control and maintain sink strength and carbohydrate supply to anthers may be the key to maintaining pollen fertility and grain number in wheat and this mechanism may also provide protection against other abiotic stresses.

Starch storage in the stems of wheat plants: localization and temporal changes.

BACKGROUND AND AIMS: Carbohydrate temporarily accumulates in wheat stems during the early reproductive growth phase, predominantly as water soluble carbohydrate (WSC), and is subsequently remobilized during grain filling. Starch has also been reported as a minor storage carbohydrate component in wheat stems, but the details are lacking. METHODS: The accumulation and localization of starch in wheat stem and leaf sheath tissue over a developmental period from 6 d before anthesis to 35 d after anthesis was investigated. KEY RESULTS: The region of the peduncle enclosed by the flag-leaf sheath, and the penultimate internode were the main tissues identified as containing starch, in which the starch grains localized to the storage parenchyma cells. In contrast, the exposed peduncle lacked starch grains. Starch grains were also found in the flag-leaf and second-leaf sheath. Plants grown in low-nitrogen conditions exhibited increased storage of both starch and WSC compared with plants grown in high-nitrogen supply. CONCLUSIONS: The major accumulation and decrease of starch occurred temporally independently to that for WSC, suggesting a different functional role for starch in wheat stems. Starch reutilization concomitant with peduncle growth, and the early development of the reproductive structures, suggested a role in provision of energy and/or carbon scaffolds for these growth processes.

Risk factors for alcohol and other drug use by healthcare professionals.

BACKGROUND: Given the increasingly stressful environment due to manpower shortages in the healthcare system in general, substance induced impairment among some healthcare professions is anticipated to grow. Though recent studies suggest that the prevalence of substance abuse is no higher in healthcare professionals (HPs) than the general population, given the responsibility to the public, any impairment could place the public at increased risk for errors. Few studies have ever reported predictors or risk factors for alcohol and other drug use (AOD) across a sample of HPs. METHODS: The study used a cross-sectional, descriptive self-report survey in a small northeastern state. A 7-page survey was mailed to a stratified random sample of 697 dentists, nurses, pharmacists and physicians registered in a northeastern state. The main outcome measures were demographic characteristics, lifetime, past year and past month prevalence of AOD use, the frequency of use, drug related dysfunctions, drug misuse and abuse potential. Six contacts during the summer of 2002 resulted in a 68.7% response rate (479/697). RESULTS: Risk factors contributing to any reported past year AOD use, as well as significant (defined as the amount of AOD use by the top 25% of respondents) past year AOD use by HPs were examined using logistic regression. Risk factors of any self-reported past year AOD use included moderate or more frequency of alcohol use, being in situations when offered AODs, feeling immune to the addictive effects of drugs (pharmaceutical invincibility) and socializing with substance abusers. Risk factors of significant past year AOD use were HPs with younger licensees, a moderate pattern of alcohol use and not socializing with substance abusers. CONCLUSION: National and state organizations need to develop policies that focus on prevention, treatment, and rehabilitation of alcohol and other drug-using healthcare professionals. The results of this study may help to delineate the characteristics of HPs abusing drugs, leading to the development of more effective policies designed to protect the public, and move toward more tailored and effective intervention strategies for HPs.

Large scale transcriptome analysis of the effects of nitrogen nutrition on accumulation of stem carbohydrate reserves in reproductive stage wheat.

We investigated the molecular basis of the long-term adaptation to nitrogen (N) limitation of wheat plants grown in a simulated crop canopy, with a focus on the stage when carbon (C) reserves are accumulated in stems for later remobilization to grain. A cDNA microarray representing approximately 36,000 unique sequences was used to compare gene expression in a number of above-ground organs at anthesis. Fructan accumulation in stems was accompanied by elevated transcripts for a suite of fructosyltransferases (FTs) and for a fructan 6-exohydrolase (6-FEH) in the low N compared to high N stems. Clustering analysis identified a grouping that included several FTs and a number of genes thought to be involved in regulation of storage C metabolism or senescence in other systems. Transcripts for three FTs and for 6-FEH increased, while transcripts for 1-FEH decreased, in sucrose-fed wheat stems compared to controls. The opposite trends were seen for these transcripts in wheat stems fed ABA. Of the putative regulators, only transcripts for the WPK4 kinase increased in response to sucrose, suggesting a role for this kinase in C storage metabolism in the reproductive wheat stems grown in low N. This work represents the first large-scale transcriptome study of responses to the most common nutrient limitation in one of the world's most economically important crops.

Association for medical education and research in substance abuse.

The Association for Medical Education and Research in Substance Abuse (AMERSA) is a multi-disciplinary organization committed to health professional faculty development in substance abuse. In 1976, members of the Career Teachers Training Program in Alcohol and Drug Abuse, a US federally funded multi-disciplinary faculty development program, formed AMERSA. The organization grew from 59 founding members, who were primarily medical school faculty, to over 300 health professionals from a spectrum of disciplines including physicians, nurses, social workers, dentists, allied health professionals, psychologists and other clinical educators who are responsible for advancing substance abuse education. AMERSA members promote substance abuse education among health professionals by developing curricula, promulgating relevant policy and training health professional faculty to become excellent teachers in this field. AMERSA influences public policy by offering standards for improving substance abuse education. The organization publishes a peer-reviewed, quarterly journal, Substance Abuse, which emphasizes research on the education and training of health professions and also includes original clinical and prevention research. Each year, the AMERSA National Conference brings together researchers and health professional educators to learn about scientific advances and exemplary teaching approaches. In the future, AMERSA will continue to pursue this mission of advancing and supporting health professional faculty who educate students and trainees to address substance abuse in patients and clients.

Development of acute inhalation reference exposure levels (RELs) to protect the public from predictable excursions of airborne toxicants.

Uniform guidelines have been developed for the derivation of 1-h acute inhalation reference exposure levels (RELs) applicable to the general public exposed routinely to hazardous substances released into the environment. Existing acute exposure guidance values developed by other organizations have been examined, and strengths and weaknesses in these existing guidelines have been identified. The results of that examination have led to the development of a reproducible and resource-intensive methodology to calculate acute inhalation RELs for 41 prioritized chemicals. Approaches to estimating levels protective against mild and severe acute effects are discussed in this report. The default methodology is the no-observed-adverse-effect level (NOAEL)/uncertainty factor (UF) approach using mainly reports in the peer-reviewed toxicological and medical literature. For two well-studied chemicals, ammonia and formaldehyde, the data allowed a benchmark dose (or concentration) methodology, as a departure from the default options, to be used. However, better human dose-response data from, for example, improved workplace monitoring correlated with symptoms, and more extensive epidemiological studies are needed before the departure from default approaches can be expanded to more substances.

Medical Education in Alcohol and Other Drugs: Curriculum Developement for Primary Care.

Over the past twp decades, physician education about alcohol and other drug abuse has progressed from teaching guides to full-blown curricula that focus on teaching medical students skills that are critical to the successful diagnosis and treatment of alcohol abuse. Despite these advances in teaching materials and techniques, integration of substance abuse curricula into primary care medical education has been slow at best.