Proposed glucocorticoid-mediated zinc signaling in the hippocampus

Corticosteroid hormones are secreted from the adrenal glands in hourly pulses and signal the hippocampus for the development and function. In contrast, the stress-induced rise in corticosteroid concentrations has a profound effect on emotional arousal, motivational processes and cognitive performance. This rise is required as the stress response to maintain homeostasis in the living body or restore it. However, abnormal rise in corticosteroid concentrations is a disadvantage to the hippocampus. Corticosteroid-glutamatergic interactions during information processing are proposed as a potential model to explain many of the diverse actions of corticosteroids in synaptic plasticity such as long-term potentiation and cognition. Because zincergic neurons are a subtype of glutamatergic neurons and release Zn(2+) and glutamate into the synaptic cleft, it is possible that homeostasis of synaptic Zn(2+), in addition to homeostasis of glutamate, is modified by glucocorticoids, followed by the changes in cognitive function and stress response. Zn(2+) signal participates in cognitive and emotional behavior in cooperation with signaling of glucocorticoids and glutamate, while can disadvantageously act on the hippocampus under sever stress circumstances. This paper analyzes the actions of glucocorticoid-mediated Zn(2+) signal in the hippocampus under stressful circumstances and its significance in both hippocampal function and dysfunction.     

Trends in genomics and molecular marker systems for the development of some underutilized crops

The term ??underutilized?? is often used to characterize the range of plant species whose potential contribution to food security, health, income generation, and environmental services has not yet been fully exploited. To harness unexploited resources, the first step is to prevent them from extinction and to conserve them in- and/or ex-situ. To utilize plant species as crops, plants must be collected, conserved, evaluated, and then if necessary manipulated. In this context, significant international efforts have focused on impeding the erosion of genetic diversity. Thousands of new accessions are introduced into germplasm institutes each year. Assessment of their molecular diversity is necessary to eliminate redundant genotypes. Marker systems have been used not only for genotyping to reduce redundancy and develop a core set, but also for a wide variety of other purposes. The use of markers based on single nucleotide polymorphisms, copy number variation, and insertions/deletions, as well as genotyping by sequencing, is becoming popular for genetic mapping and analyses of quantitative trait loci. This review discusses current marker systems and genomic analyses of a number of underutilized crops.     

The role of phytochrome B,D and E in thermoperiodic responses of <Emphasis Type="Italic">Arabidopsis thaliana</Emphasis>

The objective of this work was to study the role of the phytochromes (phy) B, D and E in the thermoperiodic control of elongation and flowering time in Arabidopsis thaliana. WT, and phyB, phyD and phyE single mutants, and phyB phyD and phyB phyE double mutants, were grown under day/night temperatures (DT/NT) of 12/22°C, 17/17°C or 22/12°C (negative, zero and positive DIF, respectively) for inflorescence stem length measurements, and under DT/NT 17/25°C or 25/17°C (negative and positive DIF, respectively) for leaf morphology and flowering time measurements. In WT final length of the stem, petiole and leaf blade were longer under positive DIF compared to negative DIF. The temperature effect was stronger in the leaf petiole than the stem, whereas only a slight change was seen in the leaf blade length direction and none in the width direction. The temperature effect on stem and petiole elongation was reduced or nearly eliminated in the genotypes lacking phyB, while a phyD or a phyE mutation had no influence or a slightly positive influence on the temperature effect, respectively. These results suggest that phyB, and not phyD or phyE, is needed for a complete thermoperiodic control of elongation growth in A. thaliana. For all genotypes tested, plants flowered earlier at negative DIF than positive DIF, suggesting that none of the three phytochromes B, D, or E is needed for a thermoperiodic control of flowering time in A. thaliana.     

The molecular composition of square arrays

Square arrays are prominent structures in plasma membranes of brain, muscle, and kidneys with an unknown function. So far, the analysis of these arrays has been restricted to freeze fracture preparations, which have shown square arrays to contain the water channel Aquaporin-4 (AQP4). Using Blue-Native PAGE immunoblots, we provide evidence that higher-order AQP4 complexes correspond to square arrays, with the AQP4 isoform M23 playing a dominant role. Our data are consistent with the idea that square arrays consist of aggregates of AQP4 tetramers complexed with multiples of dimers. By comparison, Aquaporin-1 and Aquaporin-9 form tetramers, but not higher-order complexes. AQP4 square arrays are stable under several biochemical purification steps. Analyzing the internal composition of the higher-order complexes by 2D gels, we demonstrate that the square arrays in addition to M23 also invariably contain AQP4, M1, and a novel AQP4 isoform that we call Mz. The visualization AQP4 square arrays by a rapid, biochemical assay provides new insight in the molecular organization of square arrays and gives further proof of the heterogeneity of AQP4 square arrays in vivo.     

Functional and structural conservation in the mechanosensitive channel MscL implicates elements crucial for mechanosensation

mscL encodes a channel in Escherichia coli that is opened by membrane stretch force, probably serving as an osmotic gauge. Sequences more or less similar to mscL are found in other bacteria, but the degree of conserved function has been unclear. We subcloned and expressed these putative homologues in E . coli and examined their products under patch clamp. Here, we show that each indeed encodes a conserved mechanosensitive channel activity, consistent with the interpretation that this is an important and primary function of the protein in a wide range of bacteria. Although similar, channels of different bacteria differ in kinetics and their degree of mechanosensitivity. Comparison of the primary sequence of these proteins reveals two highly conserved regions, corresponding to domains previously shown to be important for the function of the wild-type E . coli channel, and a C-terminal region that is not conserved in all species. This structural conservation is providing insight into regions of this molecule that are vital to its role as a mechanosensitive channel and may have broader implications for the understanding of other mechanosensitive systems.     

Cardiac and muscle fatigue due to relative functional overload induced by excessive stimulation, hypersensitive excitation-contraction coupling, or diminished performance capacity correlates with sarcoplasmic reticulum failure

The development of muscle fatigue due to exhaustive exercise is associated with impaired sarcoplasmic reticulum (SR) Ca-transport activity. This study tested the hypothesis that SR failure is a consistent feature of cardiac and skeletal muscle fatigue owing to relative functional overload regardless of the method of induction: excessive stimulation, diminished performance capacity, or excessive excitation-contraction coupling. The Ca-transport activity was determined using three unique models of muscle fatigue: chronic and rapid ventricular pacing in dogs; metabolic inhibition caused by global cardiac ischemia in swine; and the hypermetabolic syndrome of porcine malignant hyperthermia (MH). Both pacing- and ischemia-induced fatigue resulted in reduction of SR Ca-transport ATPase activity: from 275 +/- 58 to 159 +/- 57 nmol.min-1.mg-1 (mU/mg) and from 577 +/- 82 to 177 +/- 133 mU/mg, respectively. Both pacing-induced fatigue and halothane-induced MH resulted in reduction of Ca-sequestration activity of muscle homogenates from 5.95 +/- 2.4 to 3.11 +/- 0.67 nM/s at 300 nM Ca and 38.7 +/- 10.5 to 16.3 +/- 8.0 nM/s at 1500 nM Ca, respectively (all p less than 0.01). The isolated SR Ca-ATPase activity correlated with Ca-sequestration activity of myocardial homogenates (r = 0.76; p less than 0.005). Different models were used to study the relationship of Ca-transport activity with relaxation function, degree of acidosis, and ionized Ca concentration.(ABSTRACT TRUNCATED AT 250 WORDS)