Transcriptomic response of the red tide dinoflagellate, Karenia brevis, to nitrogen and phosphorus depletion and addition

<p>Abstract</p> <p>Background</p> <p>The role of coastal nutrient sources in the persistence of <it>Karenia brevis </it>red tides in coastal waters of Florida is a contentious issue that warrants investigation into the regulation of nutrient responses in this dinoflagellate. In other phytoplankton studied, nutrient status is reflected by the expression levels of N- and P-responsive gene transcripts. In dinoflagellates, however, many processes are regulated post-transcriptionally. All nuclear encoded gene transcripts studied to date possess a 5' <it>trans</it>-spliced leader (SL) sequence suggestive, based on the trypanosome model, of post-transcriptional regulation. The current study therefore sought to determine if the transcriptome of <it>K. brevis </it>is responsive to nitrogen and phosphorus and is informative of nutrient status.</p> <p>Results</p> <p>Microarray analysis of N-depleted <it>K. brevis </it>cultures revealed an increase in the expression of transcripts involved in N-assimilation (nitrate and ammonium transporters, glutamine synthetases) relative to nutrient replete cells. In contrast, a transcriptional signal of P-starvation was not apparent despite evidence of P-starvation based on their rapid growth response to P-addition. To study transcriptome responses to nutrient addition, the limiting nutrient was added to depleted cells and changes in global gene expression were assessed over the first 48 hours following nutrient addition. Both N- and P-addition resulted in significant changes in approximately 4% of genes on the microarray, using a significance cutoff of 1.7-fold and p ≤ 10^-4. By far, the earliest responding genes were dominated in both nutrient treatments by pentatricopeptide repeat (PPR) proteins, which increased in expression up to 3-fold by 1 h following nutrient addition. PPR proteins are nuclear encoded proteins involved in chloroplast and mitochondria RNA processing. Correspondingly, other functions enriched in response to both nutrients were photosystem and ribosomal genes.</p> <p>Conclusions</p> <p>Microarray analysis provided transcriptomic evidence for N- but not P-limitation in <it>K. brevis</it>. Transcriptomic responses to the addition of either N or P suggest a concerted program leading to the reactivation of chloroplast functions. Even the earliest responding PPR protein transcripts possess a 5' SL sequence that suggests post-transcriptional control. Given the current state of knowledge of dinoflagellate gene regulation, it is currently unclear how these rapid changes in such transcript levels are achieved.</p

Adjustment disorders as stress response syndromes: a new diagnostic concept and its exploration in a medical sample

OBJECTIVE: Adjustment disorders (AD) are an ill-defined category in the present diagnostic nomenclature. We propose a new diagnostic model that describes AD as particular forms of stress response syndrome, in which intrusions, avoidance of reminders and failure to adapt are the central processes and symptoms. In line with the existing classification, the description of AD subtypes is included. Backgrounds on existing psychopathological models of stress response disorders are outlined. METHODS: Data from a clinical sample of patients with an automatic implantable cardioverter defibrillator (n = 160, mean age 63 years, 90% males) are investigated. RESULTS: The items tapping the individual symptoms meet psychometric requirements for diagnostic applications. The diagnostic algorithm chosen indicates a 17% prevalence of AD in the sample. The subtype most commonly diagnosed is AD with mixed emotional features (41%). In a subsample, diagnostic sensitivity was 0.58 and specificity 0.81 in relation to traditional AD cases diagnosed by the Structured Clinical Interview for DSM-IV. By applying the most strongly conservative exclusion rule analogous to the Structured Clinical Interview for DSM-IV, the AD prevalence was reduced to 9%. CONCLUSION: The new AD concept is theory driven and shows methodological soundness. Its application to further samples is recommended

Focus on the Finish Line: Does High-Impact Practice Participation Influence Career Plans and Early Job Attainment?

High-impact practices (HIPs) are important co-curricular educational experiences in post-secondary education, as they promote learning, development, and persistence among students. The goal of this study was to extend the research on HIPs to explore potential connections with HIP participation and career outcomes. Using data from the National Survey of Student Engagement, this study explores whether HIP participation influences college seniors’ post-graduation plans for career and further education and whether HIP participation has a positive impact on early job attainment for these students. Results suggest that even after controlling for a variety of demographic and institutional factors, HIP participation is a significant predictor of future career plans and early job attainment. HIP participation can give students a career-related advantage through transferable skill development, engaging in learning opportunities, and generating “stories” for potential employers

Discovery of microbial natural products by activation of silent biosynthetic gene clusters

Microorganisms produce a wealth of structurally diverse specialized metabolites with a remarkable range of biological activities and a wide variety of applications in medicine and agriculture, such as the treatment of infectious diseases and cancer, and the prevention of crop damage. Genomics has revealed that many microorganisms have far greater potential to produce specialized metabolites than was thought from classic bioactivity screens; however, realizing this potential has been hampered by the fact that many specialized metabolite biosynthetic gene clusters (BGCs) are not expressed in laboratory cultures. In this Review, we discuss the strategies that have been developed in bacteria and fungi to identify and induce the expression of such silent BGCs, and we briefly summarize methods for the isolation and structural characterization of their metabolic products