Genome-wide investigation reveals high evolutionary rates in annual model plants

Background: ;Rates of molecular evolution vary widely among species. While significant deviations from molecular clock have been found in many taxa, effects of life histories on molecular evolution are not fully understood. In plants, annual/perennial life history traits have long been suspected to influence the evolutionary rates at the molecular level. To date, however, the number of genes investigated on this subject is limited and the conclusions are mixed. To evaluate the possible heterogeneity in evolutionary rates between annual and perennial plants at the genomic level, we investigated 85 nuclear housekeeping genes, 10 non-housekeeping families, and 34 chloroplast;genes using the genomic data from model plants including Arabidopsis thaliana and Medicago truncatula for annuals and grape (Vitis vinifera) and popular (Populus trichocarpa) for perennials.;Results: ;According to the cross-comparisons among the four species, 74-82% of the nuclear genes and 71-97% of the chloroplast genes suggested higher rates of molecular evolution in the two annuals than those in the two perennials. The significant heterogeneity in evolutionary rate between annuals and perennials was consistently found both in nonsynonymous sites and synonymous sites. While a linear correlation of evolutionary rates in orthologous genes between species was observed in nonsynonymous sites, the correlation was weak or invisible in synonymous sites. This tendency was clearer in nuclear genes than in chloroplast genes, in which the overall;evolutionary rate was small. The slope of the regression line was consistently lower than unity, further confirming the higher evolutionary rate in annuals at the genomic level.;Conclusions: ;The higher evolutionary rate in annuals than in perennials appears to be a universal phenomenon both in nuclear and chloroplast genomes in the four dicot model plants we investigated. Therefore, such heterogeneity in evolutionary rate should result from factors that have genome-wide influence, most likely those associated with annual/perennial life history. Although we acknowledge current limitations of this kind of study, mainly due to a small sample size available and a distant taxonomic relationship of the model organisms, our results indicate that the genome-wide survey is a promising approach toward further understanding of the;mechanism determining the molecular evolutionary rate at the genomic level.

Coronary artery disease, nitric oxide and oxidative stress: the "Yin-Yang" effect--a Chinese concept for a worldwide pandemic

Prevention of coronary artery disease (CAD) and reduction of its mortality and morbidity remains a major public health challenge throughout the "Western world". Recent evidence supports the concept that the impairment of endothelial function, a hallmark of insulin resistance states, is an upstream event in the pathophysiology of insulin resistance and its main corollaries: atherosclerosis and myocardial infarction. Atherosclerosis is currently thought to be the consequence of a subtle imbalance between pro- and anti-oxidants that produces favourable conditions for lesion progression towards acute thrombotic complications and clinical events. Over the last decade, a remarkable burst of evidence has accumulated, offering the new perspective that bioavailable nitric oxide (NO) plays a pivotal role throughout the CAD-spectrum, from its genesis to the outcome after acute events. Vascular NO is a critical modulator of coronary blood flow by inhibiting smooth muscle contraction and platelet aggregation. It also acts in angiogenesis and cytoprotection. Defective endothelial nitric oxide synthase (eNOS) driven NO synthesis causes development of major cardiovascular risk factors (insulin resistance, arterial hypertension and dyslipidaemia) in mice, and characterises CAD-prone insulin-resistant humans. On the other hand, stimulation of inducible nitric oxide synthase (iNOS) and NO overproduction causes metabolic insulin resistance and characterises atherosclerosis, heart failure and cardiogenic shock in humans, suggesting a "Yin-Yang" effect of NO in the cardiovascular homeostasis. Here, we will present a concise overview of the evidence for this novel concept, providing the conceptual framework for developing a potential therapeutic strategy to prevent and treat CAD.

Argemone mexicana decoction for the treatment of uncomplicated falciparum malaria

A prospective, dose-escalating, quasi-experimental clinical trial was conducted with a traditional healer using a decoction of Argemone mexicana for the treatment of malaria in Mali. The remedy was prescribed in three regimens: once daily for 3 days (Group A; n=23); twice daily for 7 days (Group B; n=40); and four times daily for the first 4 days followed by twice daily for 3 days (Group C; n=17). Thus, 80 patients were included, of whom 80% were aged<5 years and 25% were aged<1 year. All presented to the traditional healer with symptoms of malaria and had a Plasmodium falciparum parasitaemia>2000/microl but no signs of severe malaria. The proportions of adequate clinical response (ACR) at Day 14 were 35%, 73% and 65% in Groups A, B and C, respectively (P=0.011). At Day 14, overall proportions of ACR were lower in children aged<1 year (45%) and higher in patients aged>5 years (81%) (P=0.027). Very few patients had complete parasite clearance, but at Day 14, 67% of patients with ACR had a parasitaemia<2000/microl. No patient needed referral for severe disease. Only minor side effects were observed. Further research should determine whether this local resource could represent a first-aid home treatment in remote areas.