Herbaceous plant diversity in forest ecosystems: patterns,mechanisms, and threats

Plant Ecology - Studies conducted in forests have resulted in much of the ecological theory we build upon today. However, our basic understanding of forest ecology comes almost exclusively from the...     

Ectopic expression of AmNAC1 from Avicennia marina (Forsk.) Vierh. confers multiple abiotic stress tolerance in yeast and tobacco

Plant Cell, Tissue and Organ Culture (PCTOC) - Abiotic factors like salinity, drought and cold affect agricultural productivity substantially worldwide. NAC (NAM, ATAF1/2 and CUC2) family...     

Cooperative binding ensures the obligatory melibiose/Na+ cotransport in MelB

MelB catalyzes the obligatory cotransport of melibiose with Na⁺, Li⁺, or H⁺. Crystal structure determination of the Salmonella typhimurium MelB (MelB_St) has revealed a typical major facilitator superfamily (MFS) fold at a periplasmic open conformation. Cooperative binding of Na⁺ and melibiose has been previously established. To determine why cotranslocation of sugar solute and cation is obligatory, we analyzed each binding in the thermodynamic cycle using three independent methods, including the determination of melting temperature by circular dichroism spectroscopy, heat capacity change (ΔC_p), and regulatory phosphotransferase EIIA^Glc binding with isothermal titration calorimetry (ITC). We found that MelB_St thermostability is increased by either substrate (Na⁺ or melibiose) and observed a cooperative effect of both substrates. ITC measurements showed that either binary formation yields a positive sign in the ΔC_p, suggesting MelB_St hydration and a likely widening of the periplasmic cavity. Conversely, formation of a ternary complex yields negative values in ΔCp, suggesting MelB_St dehydration and cavity closure. Lastly, we observed that EIIA^Glc, which has been suggested to trap MelB_St at an outward-open state, readily binds to the MelB_St apo state at an affinity similar to MelB_St/Na⁺. However, it has a suboptimal binding to the ternary state, implying that MelB_St in the ternary complex may be conformationally distant from the EIIA^Glc-preferred outward-facing conformation. Our results consistently support the notion that binding of one substrate (Na⁺ or melibiose) favors MelB_St at open states, whereas the cooperative binding of both substrates triggers the alternating-access process, thus suggesting this conformational regulation could ensure the obligatory cotransport.     

Synthesis of novel bis(pyrimido[5,4-c]quinoline-2,4(1H,3H)-dione) and its derivatives: Evaluation of their antioxidant properties

One pot cyclocondensation reaction of barbituric/thiobarbituric acid with aromatic aldehydes and p-phenylenediamine/2,6-diaminopyridine by refluxing in glacial acetic acid afforded novel bis(pyrimido[5,4-c]quinoline-2,4(1H,3H)-diones)/pyrido bis(pyrimido[5,4-c]quinoline-2,4(1H,3H)-diones. All the synthesized compounds were screened for their antioxidant activities using FRAP and DPPH methods. Compounds with chloro substituents showed relatively good antioxidant properties.     

Human microvascular dysfunction and apoptotic injury induced by AL amyloidosis light chain proteins

Light chain amyloidosis (AL) involves overproduction of amyloidogenic light chain proteins (LC) leading to heart failure, yet the mechanisms underlying tissue toxicity remain unknown. We hypothesized that LC induces endothelial dysfunction in non-AL human microvasculature and apoptotic injury in human coronary artery endothelial cells (HCAECs). Adipose arterioles (n = 34, 50 ± 3 yr) and atrial coronary arterioles (n = 19, 68 ± 2 yr) from non-AL subjects were cannulated. Adipose arteriole dilator responses to acetylcholine/papaverine were measured at baseline and 1 h exposure to LC (20 μg/ml) from biopsy-proven AL subjects (57 ± 11 yr) without and with antioxidant cotreatment. Coronary arteriole dilation to bradykinin/papaverine was measured post-LC exposure. HCAECs were exposed to 1 or 24 h of LC. LC reduced dilation to acetylcholine (10(-4) M: 41.6 ± 7 vs. 85.8 ± 2.2% control, P < 0.001) and papaverine (81.4 ± 4.6 vs. 94.8 ± 1.3% control, P < 0.01) in adipose arterioles and to bradykinin (10(-6) M: 68.6 ± 6.2 vs. 90.9 ± 1.6% control, P < 0.001) but not papaverine in coronary arterioles. There was an increase in superoxide and peroxynitrite in arterioles treated with LC. Adipose arteriole dilation was restored by cotreatment with polyethylene glycol-superoxide dismutase and tetrahydrobiopterin but only partially restored by mitoquinone (mitochondria-targeted antioxidant) and gp91ds-tat (NADPH oxidase inhibitor). HCAECs exposed to LC showed reduced NO and increased superoxide, peroxynitrite, annexin-V, and propidium iodide compared with control. Brief exposure to physiological amounts of LC induced endothelial dysfunction in human adipose and coronary arterioles and increased apoptotic injury in coronary artery endothelial cells likely as a result of oxidative stress, reduced NO bioavailability, and peroxynitrite production. Microvascular dysfunction and injury is a novel mechanism underlying AL pathobiology and is a potential target for therapy.     

Pyrrolo[1,2-f]triazines as JAK2 inhibitors: achieving potency and selectivity for JAK2 over JAK3

SAR studies of pyrrolo[1,2-f]triazines as JAK2 inhibitors is presented. Achieving JAK2 inhibition selectively over JAK3 is discussed.     

Expressed sequence tags (ESTs) based identification of genes and expression analysis of leukocyte cell-derived chemotaxin-2 (LECT2) from Epinephelus bruneus

The kelp grouper, Epinephelus bruneus, is an economically important intensively cultured species in Southeast Asia. Despite the insatiable demand its large-scale production has been hindered by problems associated with water quality, nutrition, and diseases especially due to increased rearing density. It is generally accepted that in fish both innate and adaptive immune system provide protection from diseases. In the present study a cDNA library of Streptococcus iniae-challenged kelp grouper was constructed to identify the genes that reveal molecular mechanism, physiological functions, and gene expression in different tissues using expressed sequence tags (ESTs) and RT-PCR strategy. Of a total of 2170 ESTs examined 279 (12.9%) were identified as contig and 860 (39.6%) as singletons. A total of 190 important immune and enzyme related genes (16.7%) were identified in both contig and singletons. The key immune molecules identified comprise complement factors, chemotaxin, chemokine, Fas ligand, ferritins, hepcidin, lysozyme c, MHC, and TLR which are involved in the innate or adaptive immune system. Among the genes a full-length cDNA of leukocyte cell-derived chemotaxin-2 (EbLECT2) with 540 base pair (bp) was identified; it consists of a 5′-untranslated region (UTR) of 17 bp, a 3′-UTR of 76 bp, and a stop codon TAA in 3′-UTR. The EbLECT2 is an important molecule in the innate immunity. It is a multifunctional protein involved in cell growth, differentiation, and autoimmunity. The open reading frame (ORF) of the EbLECT2 encodes with 155 amino acid (aa) residues with a predicted molecular weight and isoelectric point (pI) of 17 kDa and 9, respectively. The close phylogenetic relationship of EbLECT2 shares the highest similarity with the already reported LECT2 from Epinephelus coioides (96%) and Epinephelus akaara (94%). EbLECT2 mRNA was expressed predominantly in liver, spleen, and kidney while the expression was moderate in gills, heart, and muscle in E. bruneus after being challenged with LPS from Escherichia coli and pathogenic bacterium Vibrio anguillarum both of which involve the immune defense system. Further, the recombinant mature EbLECT2 (rEbLECT2) was successfully expressed in E. coli BL21 (DE3), and the antiserum against EbLECT2 was obtained for further investigations. The significant number of ESTs genome results obtained constitutes a powerful resource for further investigation to establish the gene discovery, functional genomic research, molecular mechanisms, and development of microarrays for the gene expression studies in kelp grouper.     

Non-specific immune response and disease resistance induced by Siegesbeckia glabrescens against Vibrio parahaemolyticus in Epinephelus bruneus

The immunomodulatory effect of Siegesbeckia glabrescens extract-supplementation diets on innate immune response and disease resistance of kelp grouper, Epinephelus bruneus against Vibrio parahaemolyticus at weeks 1, 2, and 4 is reported. The serum lysozyme activity was significantly enhanced with any enriched diet from weeks 1-4 when compared to control diet (0%). The alternative complement haemolytic activities significantly were enhanced with all enriched diets on weeks 2 and 4 whereas the cellular reactive oxygen species (ROS) was significantly enhanced only with 1.0% and 2.0% diets. The reactive nitrogen intermediate (RNI) value was significantly enhanced with any enriched diet on weeks 2 and 4, but on first week it did not differ from control. The myeloperoxidase (MPO) production significantly increased with 1.0% and 2.0% diets from second week onwards; with other enriched diets the increase manifested on fourth week; but during first week it did not vary from that of the control with any enriched diet. The protection in terms of cumulative mortality was the least being 25% and 20% when fed with 1.0% and 2.0% diets. The present results indicate that feeding kelp grouper with S. glabrescens extract enriched diet at 1.0% and 2.0% levels significantly enhance the immunological parameters, increase the disease resistance and minimize the cumulative mortality in E. bruneus against V. parahaemolyticus.     

Effect of Coriolus versicolor supplemented diet on innate immune response and disease resistance in kelp grouper Epinephelus bruneus against Listonella anguillarum

The effect of Coriolus versicolor extract supplemented diets on innate immune response and disease resistance in kelp grouper, Epinephelus bruneus against Listonella anguillarum, is reported. Kelp grouper were divided into four groups of 25 each and fed with C. versicolor enriched diets at 0% (control), 0.01%, 0.1%, and 1.0% level. After 30 days of feeding, all fish were injected interaperitoneally (i.p.) with 50 μl of L. anguillarum (4.7 × 10⁷ CFU) to investigate the immune parameters at weeks 1, 2, and 4. The reactive oxygen species and reactive nitrogen species production were significantly enhanced in fish fed with 0.1% and 1.0% supplementation diets from weeks 1-4 when compared to the non enriched diet fed and infected control. The phagocytic activity significantly increased with 0.1% and 1.0% diets on weeks 2 and 4. The leucocyte myeloperoxidase content, lysozyme activity, and total protein level significantly increased when fed with 0.1% and 1.0% supplementation diets from weeks 1-4. The cumulative mortality was 35% and 45% in 1.0% and 0.1% enriched diet fed groups whereas it was 55% and 80% in 0.01% and 0% groups respectively. The present results suggest that diets enriched with C. versicolor at 0.1% or 1.0% level positively enhance the innate immune system and affords protection from L. anguillarum.