Effects of environmental variation during seed production on seed dormancy and germination

The environment during seed production has major impacts on the behaviour of progeny seeds. It can be shown that for annual plants temperature perception over the whole life history of the mother can affect the germination rate of progeny, and instances have been documented where these affects cross whole generations. Here we discuss the current state of knowledge of signal transduction pathways controlling environmental responses during seed production, focusing both on events that take place in the mother plant and those that occur directly as a result of environmental responses in the developing zygote. We show that seed production environment effects are complex, involving overlapping gene networks active independently in fruit, seed coat, and zygotic tissues that can be deconstructed using careful physiology alongside molecular and genetic experiments

Dissecting weed adaptation: fitness and trait correlations in herbicide resistant Alopecurus myosuroides

BACKGROUND Unravelling the genetic architecture of non-target-site resistance (NTSR) traits in weed populations can inform questions about the inheritance, trade-offs and fitness costs associated with these traits. Classical quantitative genetics approaches allow study of the genetic architecture of polygenic traits even where the genetic basis of adaptation remains unknown. These approaches have the potential to overcome some of the limitations of previous studies into the genetics and fitness of NTSR. RESULTS Using a quantitative genetic analysis of 400 pedigreed Alopecurus myosuroides seed families from nine field-collected populations, we found strong heritability for resistance to the acetolactate synthase and acetyl CoA carboxylase inhibitors (h2 = 0.731 and 0.938, respectively), and evidence for shared additive genetic variance for resistance to these two different herbicide modes of action, rg = 0.34 (survival), 0.38 (biomass). We find no evidence for genetic correlations between life-history traits and herbicide resistance, indicating that resistance to these two modes of action is not associated with large fitness costs in blackgrass. We do, however, demonstrate that phenotypic variation in plant flowering characteristics is heritable, h2 = 0.213 (flower height), 0.529 (flower head number), 0.449 (time to flowering) and 0.372 (time to seed shed), demonstrating the potential for adaptation to other nonchemical management practices (e.g. mowing of flowering heads) now being adopted for blackgrass control. CONCLUSION These results highlight that quantitative genetics can provide important insight into the inheritance and genetic architecture of NTSR, and can be used alongside emerging molecular techniques to better understand the evolutionary and fitness landscape of herbicide resistance

Novel techniques for data visualisation and exploration in multidimensional datasets

Presentation focusing on new techniques for data visualisation and exploration in multidimensional datasets

How does treatment influence endocrine mechanisms in acute severe heart failure? Effects on cardiac natriuretic peptides, the renin system, neuropeptide Y and catecholamines.

1. Hormones involved in cardiovascular regulation are influenced by drug treatment. It is therefore difficult to study endocrine mechanisms in heart failure as most patients are already on treatment by the time they reach hospital. 2. We studied nine hospital in-patients before and after treatment of acute New York Heart Association class IV heart failure. 3. Before treatment, plasma brain and atrial natriuretic peptides were markedly elevated (BNP 121 +/- 26 pg/ml, ANP 163 +/- 33 pg/ml; normal range: BNP 3.9 +/- 0.3 pg/ml, ANP 8.6 +/- 0.8 pg/ml) and correlated positively with serum creatinine and left ventricular end-diastolic diameter and negatively with ejection fraction. Eight patients improved and one died. 4. With improvement plasma ANP and BNP fell. Initial renin activity was within the normal range but increased on treatment. Plasma neuropeptide Y and adrenaline remained normal before and after treatment in the eight patients who improved. Initial plasma noradrenaline was in the normal range in four of these patients and just above normal in a further four. In the patient who died, initial plasma neuropeptide Y and catecholamines were very high. 5. Plasma BNP emerged as complementary to ANP as a dynamic index in severe heart failure; however, renal function is also an important determinant of plasma BNP and ANP. There is little evidence for activation of the circulating renin-angiotensin-aldosterone system or neuropeptide Y before treatment of acute heart failure

Model selection reveals control of cold signalling by evening-phased components of the plant circadian clock

Circadian clocks confer advantages by restricting biological processes to certain times of day through the control of specific phased outputs. Control of temperature signalling is an important function of the plant oscillator, but the architecture of the gene network controlling cold signalling by the clock is not well understood. Here we use a model ensemble fitted to time-series data and a corrected Akaike Information Criterion (AICc) analysis to extend a dynamic model to include the control of the key cold-regulated transcription factors C-REPEAT BINDING FACTORs 1–3 (CBF1, CBF2, CBF3). AICc was combined with in silico analysis of genetic perturbations in the model ensemble, and selected a model that predicted mutant phenotypes and connections between evening-phased circadian clock components and CBF3 transcriptional control, but these connections were not shared by CBF1 and CBF2. In addition, our model predicted the correct gating of CBF transcription by cold only when the cold signal originated from the clock mechanism itself, suggesting that the clock has an important role in temperature signal transduction. Our data shows that model selection could be a useful method for the expansion of gene network models

Carrier-free sup11sup 11C-labeled catecholamines in nuclear medicine and biochemical research

The catecholamines, dopamine, norepinephrine, and epinephrine, are synthesized and secreted by tissues such as brain, sympathetic nerve endings, and chromaffin cells. Dopamine and norepinephrine are primarily neurotransmitters while epinephrine functions mainly as a hormone. The biosynthesis of the catecholamines from tyrosine is reviewed. Abnormalities in the quantities and metabolism of these compounds are associated with many pathological conditions such as hypertension, Parkinsonism, and chromaffin tissue tumors. Rapid synthetic methods (for the preparation off)/sup 11/C-labeled catecholamines have been developed. The potential use of these labeled catecholamines as scanning agents for the adrenal glands and heart myocardium was evaluated in dogs. (CH

Synthetic and theoretical MO calculational studies of lithiotriazine intermediates produced during alkyllithium-induced cyclotrimerisation reactions of organic nitriles, and comparison of their structures with that of a methylmagnesiotriazine derivative

Benzonitrile can be readily cyclotrimerised by treatment with a suitable alkyllithium to give a simple triazine, or to a solvated lithiodihydrotriazine derivative. Which cyclic product dominates depends mainly on the source of the active Li+ cation (n-butyllithium, t-butyllithium and tetramethylguanidinolithium are considered here), and on the solvent employed. X-ray crystallographic studies on a representative compound show that the lithio species exists as a mononuclear, contact ion pair structure, with the triazine ring in a 1,4-dihydro state. On reaction with the Grignard reagent, MeMgCl, this compound gives a methylmagnesiodihydrotriazine, which has also been crystallographically characterised and found to closely resemble its lithio precursor. Ab initio MO calculations on model systems reveal that the 1,4-dihydrotriazine arrangement is energetically preferred to the 1,2-dihydro alternative irrespective of the counterion (Li+ or H+) present. A theoretical investigation of the methanolysis of the lithio species indicates that the formation of an intermediate MeOH complex, with the alcohol attached to a ring N atom and not to Li+, directs the reaction towards ultimate formation of a 1,2-dihydrotriazine