Enhanced salt tolerance of transgenic tobacco plants by co-expression of PcINO1 and McIMT1 is accompanied by increased level of myo-inositol and methylated inositol

Introgression and functional expression of either the PcINO1 (l-myo-inositol 1-phosphate synthase or MIPS coding gene from the wild halophytic rice, Porteresia coarctata) or McIMTI (inositol methyl transferase, IMTI coding gene from common ice plant Mesembryanthemum crystallinum) has earlier been shown to confer salt tolerance to transgenic tobacco plants (Sheveleva et al., Plant Physiol 115:1211–1219, 1997; Majee et al., J Biol Chem 279:28539–28552, 2004). In this communication, we show that transgenic tobacco plants co-expressing PcINO1 and McIMT1 gene either in cytosol or in chloroplasts accumulate higher amount of total inositol (free and methyl inositol) compared to non-transgenic plants. These transgenic plants were more competent in terms of growth potential and photosynthetic activity and were less prone to oxidative stress under salt stress. A positive correlation between the elevated level of total inositol and methylated inositol and the capability of the double transgenic plants to withstand a higher degree of salt stress compared to the plants expressing either PcINO1 or McIMT1 alone is inferred.     

Novel multiplex PCR approaches for the simultaneous detection of human pathogens: Escherichia coli 0157:H7 and Listeria monocytogenes

Escherichia coli 0157:H7 and Listeria monocytogenes are the two most important food-borne human pathogens. To develop a single, rapid and sensitive PCR based test for simultaneous detection of both the organisms, fliCh7 and iap gene specific primers were used respectively for E. coli 0157:H7 and L. monocytogenes. Initially, with equal quantities of purified genomic DNAs of these organisms a multiplex PCR reaction was standardized to yield uniform amplification of both targets. Although, this assay detected E. coli 0157:H7 with high sensitivity, it failed to pick up L. monocytogenes after several hours of enrichment in broth medium initially spiked with equal numbers of live cells. This was found to be due to unequal growth of these organisms leading to disparity in the amount of template DNAs represented in the DNA preparation applied for conventional multiplex PCR amplification. To circumvent this, we have developed a modified method of enrichment and harvesting leading to highly sensitive and rapid single reaction PCR detection of both pathogens. We have also successfully developed two novel multiplex PCR formats for the generation of uniform PCR signals. Some of these methods might find broader application for the simultaneous detection of different combinations of multiple pathogens.     

Mapping of yield influencing QTL in <Emphasis Type="Italic">Brassica juncea</Emphasis>: implications for breeding of a major oilseed crop of dryland areas

Quantitative trait loci (QTL) analysis of yield influencing traits was carried out in Brassica juncea (AABB) using a doubled haploid (DH) mapping population of 123 lines derived from a cross between Varuna (a line representing the Indian gene pool) and Heera (representing the east European gene pool) to identify potentially useful alleles from both the parents. The existing AFLP based map of B. juncea was further saturated with RFLP and SSR markers which led to the identification of the linkage groups belonging to the A (B. rapa) and B (B. nigra) genome components of B. juncea. For QTL dissection, the DH lines were evaluated at three different environments and phenotyped for 12 quantitative traits. A total of 65 QTL spread over 13 linkage groups (LG) were identified from the three environments. QTL analysis showed that the A genome has contributed more than the B genome to productivity (68% of the total QTL detected) suggesting a more prominent role of the A genome towards domestication of this crop. The east European line, Heera, carried favorable alleles for 42% of the detected QTL and the remaining 58% were in the Indian gene pool line, Varuna. We observed clustering of major QTL in a few linkage groups, particularly in J7 and J10 of the A genome, with QTL of different traits having agronomically antagonistic allelic effects co-mapping to the same genetic interval. QTL analysis also identified some well-separated QTL which could be readily transferred between the two pools. Based on the QTL analysis, we propose that improvement in yield could be achieved more readily by heterosis breeding rather than by pure line breeding. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Endocannabinoids acting at CB1 receptors mediate the cardiac contractile dysfunction in vivo in cirrhotic rats

Advanced liver cirrhosis is associated with hyperdynamic circulation consisting of systemic hypotension, decreased peripheral resistance, and cardiac dysfunction, termed cirrhotic cardiomyopathy. Previous studies have revealed the role of endocannabinoids and vascular CB(1) receptors in the development of generalized hypotension and mesenteric vasodilation in animal models of liver cirrhosis, and CB(1) receptors have also been implicated in the decreased beta-adrenergic responsiveness of isolated heart tissue from cirrhotic rats. Here we document the cardiac contractile dysfunction in vivo in liver cirrhosis and explore the role of the endocannabinoid system in its development. Rats with CCl(4)-induced cirrhosis developed decreased cardiac contractility, as documented through the use of the Millar pressure-volume microcatheter system, low blood pressure, and tachycardia. Bolus intravenous injection of the CB(1) antagonist AM251 (3 mg/kg) acutely increased mean blood pressure, as well as both load-dependent and -independent indexes of systolic function, whereas no such changes were elicited by AM251 in control rats. Furthermore, tissue levels of the endocannabinoid anandamide increased 2.7-fold in the heart of cirrhotic compared with control rats, without any change in 2-arachidonoylglycerol levels, whereas, in the cirrhotic liver, both 2-arachidonoylglycerol (6-fold) and anandamide (3.5-fold) were markedly increased. CB(1)-receptor expression in the heart was unaffected by cirrhosis, as verified by Western blotting. Activation of cardiac CB(1) receptors by endogenous anandamide contributes to the reduced cardiac contractility in liver cirrhosis, and CB(1)-receptor antagonists may be used to improve contractile function in cirrhotic cardiomyopathy and, possibly, in other forms of heart failure.     

Pulmonary arterial hypertension: a disease of tethers, SNAREs and SNAPs?

Histological and electron microscopic studies over the past four decades have highlighted "plump," "enlarged" endothelial, smooth muscle, and fibroblastic cellular elements with increased endoplasmic reticulum, Golgi stacks, and vacuolation in pulmonary arterial lesions in human and in experimental (hypoxia and monocrotaline) pulmonary arterial hypertension. However, the contribution of disrupted intracellular membrane trafficking in the pathobiology of this disease has received insufficient attention. Recent studies suggest a pathogenetic role of the disruption of intracellular trafficking of vasorelevant proteins and cell-surface receptors in the development of this disease. The purpose of this essay is to highlight the molecular regulation of vesicular trafficking by membrane tethers, SNAREs and SNAPs, and to suggest how their dysfunction, directly and/or indirectly, might contribute to development of pulmonary arterial hypertension in experimental models and in humans, including that due to mutations in bone morphogenetic receptor type 2.     

Nature of selective constraints on synonymous codon usage of rice differs in GC-poor and GC-rich genes

Synonymous codon usage and cellular tRNA abundance are thought to be co-evolved in optimizing translational efficiencies in highly expressed genes. Here in this communication by taking the advantage of publicly available gene expression data of rice and Arabidopsis we demonstrated that tRNA gene copy number is not the only driving force favoring translational selection in all highly expressed genes of rice. We found that forces favoring translational selection differ between GC-rich and GC-poor classes of genes. Supporting our results we also showed that, in highly expressed genes of GC-poor class there is a perfect correspondence between majority of preferred codons and tRNA gene copy number that confers translational efficiencies to this group of genes. However, tRNA gene copy number is not fully consistent with models of translational selection in GC-rich group of genes, where constraints on mRNA secondary structure play a role to optimize codon usage in highly expressed genes.