Leymus EST linkage maps identify 4NsL-5NsL reciprocal translocation, wheat-Leymus chromosome introgressions, and functionally important gene loci

Allotetraploid (2n = 4x = 28) Leymus triticoides and Leymus cinereus are divergent perennial grasses, which form fertile hybrids. Genetic maps with n = 14 linkage groups (LG) comprised with 1,583 AFLP and 67 heterologous anchor markers were previously used for mapping quantitative trait loci (QTLs) in these hybrids, and chromosomes of other Leymus wildryes have been transferred to wheat. However, identifications of the x = 7 homoeologous groups were tenuous and genetic research has been encumbered by a lack of functional, conserved gene marker sequences. Herein, we mapped 350 simple sequence repeats and 26 putative lignin biosynthesis genes from a new Leymus EST library and constructed one integrated consensus map with 799 markers, including 375 AFLPs and 48 heterologous markers, spanning 2,381 centiMorgans. LG1b and LG6b were reassigned as LG6b* and LG1b*, respectively, and LG4Ns and LG4Xm were inverted so that all 14 linkage groups are aligned to the x = 7 Triticeae chromosomes based on EST alignments to barley and other reference genomes. Amplification of 146 mapped Leymus ESTs representing six of the seven homoeologous groups was shown for 17 wheat-Leymus chromosome introgression lines. Reciprocal translocations between 4L and 5L in both Leymus and Triticum monococcum were aligned to the same regions of Brachypodium chromosome 1. A caffeic acid O-methyltransferase locus aligned to fiber QTL peaks on Leymus LG7a and brown midrib mutations of maize and sorghum. Glaucousness genes on Leymus and wheat chromosome 2 were aligned to the same region of Brachypodium chromosome 5. Markers linked to the S self-incompatibility gene on Leymus LG1a cosegregated with markers on LG2b, possibly cross-linked by gametophytic selection. Homoeologous chromosomes 1 and 2 harbor the S and Z gametophytic self-incompatibility genes of Phalaris, Secale, and Lolium, but the Leymus chromosome-2 self-incompatibility gene aligns to a different region on Brachypodium chromosome 5. Nevertheless, cosegregation of self-incompatibility genes on Leymus presents a powerful system for mapping these loci.     

N-acetylcysteine protects against apoptosis through modulation of group I metabotropic glutamate receptor activity

The activation of group I metabotropic glutamate receptor (group I mGlus) has been shown to produce neuroprotective or neurotoxic effects. In this study, we investigated the effects of N-acetylcysteine (NAC), a precursor of the antioxidant glutathione, on group I mGlus activation in apoptosis of glial C6 and MN9D cell lines, and a rat model of Parkinson's disease (PD). We demonstrated that NAC protected against apoptosis through modulation of group I mGlus activity. In glial C6 cells, NAC promoted phosphorylation of ERK induced by (s)-3,5-dihydroxy-phenylglycine (DHPG), an agonist of group I mGlus. NAC enhanced the group I mGlus-mediated protection from staurosporine (STS)-induced apoptosis following DHPG treatment. Moreover, in rotenone-treated MN9D cells and PD rat model, NAC protected against group I mGlus-induced toxicity by compromising the decrease in phosphorylation of ERK, phosphorylation or expression level of TH. Furthermore, the results showed that NAC prohibited the level of ROS and oxidation of cellular GSH/GSSG (E(h)) accompanied by activated group I mGlus in the experimental models. Our results suggest that NAC might act as a regulator of group I mGlus-mediated activities in both neuroprotection and neurotoxicity via reducing the oxidative stress, eventually to protect cell survival. The study also suggests that NAC might be a potential therapeutics targeting for group I mGlus activation in the treatment of PD.     

Efficacy of short-term high-dose statin in preventing contrast-induced nephropathy: a meta-analysis of seven randomized controlled trials

Background

A few studies focused on statin therapy as specific prophylactic measures of contrast-induced nephropathy have been published with conflicting results. In this meta-analysis of randomized controlled trials, we aimed to assess the effectiveness of shor-term high-dose statin treatment for the prevention of CIN and clinical outcomes and re-evaluate of the potential benefits of statin therapy.

Methods

We searched PubMed, OVID, EMBASE, Web of science and the Cochrane Central Register of Controlled Trials databases for randomized controlled trials comparing short-term high-dose statin treatment versus low-dose statin treatment or placebo for preventing CIN. Our outcome measures were the risk of CIN within 2–5 days after contrast administration and need for dialysis.

Results

Seven randomized controlled trials with a total of 1,399 patients were identified and analyzed. The overall results based on fixed-effect model showed that the use of short-term high-dose statin treatment was associated with a significant reduction in risk of CIN (RR = 0.51, 95% CI 0.34–0.76, p = 0.001; I² = 0%). The incidence of acute renal failure requiring dialysis was not significant different after the use of statin (RR = 0.33, 95% CI 0.05–2.10, p = 0.24; I² = 0%). The use of statin was not associated with a significant decrease in the plasma C-reactive protein level (SMD −0.64, 95% CI: −1.57 to 0.29, P = 0.18, I² = 97%).

Conclusions

Although this meta-analysis supports the use of statin to reduce the incidence of CIN, it must be considered in the context of variable patient demographics. Only a limited recommendation can be made in favour of the use of statin based on current data. Considering the limitations of included studies, a large, well designed trial that incorporates the evaluation of clinically relevant outcomes in participants with different underlying risks of CIN is required to more adequately assess the role for statin in CIN prevention.     

Low SIRT3 Expression Correlates with Poor Differentiation and Unfavorable Prognosis in Primary Hepatocellular Carcinoma

SIRT3, a mitochondrial sirtuin belonging to nicotinamide adenine nucleotide (NAD) dependent deacetylases, is implicated in metabolism, longevity and carcinogenesis. SIRT3 expression and its significance in hepatocellular carcinoma (HCC) remain largely unclear. In this study, we demonstrated that SIRT3 expression in HCC tissue was much lower than that in paracarcinoma tissue, at both mRNA and protein levels. The cutoff value for low SIRT3 expression in HCC was defined according to receiver operating characteristic curve (ROC) analysis. As disclosed by immunohistochemistry (IHC) results, low SIRT3 expression was present in 67.3% (167/248) of HCC cases. Furthermore, low expression of SIRT3 was significantly correlated to differentiation (P = 0.013), clinical stage (P = 0.005), serum AFP level (P<0.01), tumor multiplicity (P = 0.026) and relapse (P = 0.028). Moreover, Kaplan-Meier analysis indicated that low SIRT3 expression associated with unfavorable overall survival (P<0.01) and recurrence-free survival (P = 0.004). The prognostic impact of SIRT3 was further confirmed by stratified survival analysis. Importantly, multivariate analysis revealed that low SIRT3 expression was an independent poor prognostic marker for overall survival (Hazard Ratio (HR) 0.555, 95% confidence interval (95% CI) 0.344–0.897, P = 0.016). Collectively, we conclude that SIRT3 is decreased in HCC and is a novel unfavorable marker for prognosis of patients with this fatal disease.     

Proteomic analysis of Ketogulonicigenium vulgare under glutathione reveals high demand for thiamin transport and antioxidant protection

Ketogulonicigenium vulgare, though grows poorly when mono-cultured, has been widely used in the industrial production of the precursor of vitamin C with the coculture of Bacillus megaterium. Various efforts have been made to clarify the synergic pattern of this artificial microbial community and to improve the growth and production ability of K. vulgare, but there is still no sound explanation. In previous research, we found that the addition of reduced glutathione into K. vulgare monoculture could significantly improve its growth and productivity. By performing SEM and TEM, we observed that after adding GSH into K. vulgare monoculture, cells became about 4-6 folds elongated, and formed intracytoplasmic membranes (ICM). To explore the molecular mechanism and provide insights into the investigation of the synergic pattern of the co-culture system, we conducted a comparative iTRAQ-2-D-LC-MS/MS-based proteomic analysis of K. vulgare grown under reduced glutathione. Principal component analysis of proteomic data showed that after the addition of glutathione, proteins for thiamin/thiamin pyrophosphate (TPP) transport, glutathione transport and the maintenance of membrane integrity, together with several membrane-bound dehydrogenases had significant up-regulation. Besides, several proteins participating in the pentose phosphate pathway and tricarboxylic acid cycle were also up-regulated. Additionally, proteins combating intracellular reactive oxygen species were also up-regulated, which similarly occurred in K. vulgare when the co-cultured B. megaterium cells lysed from our former research results. This study reveals the demand for transmembrane transport of substrates, especially thiamin, and the demand for antioxidant protection of K. vulgare.     

Cu(ii)- and disulfide bonds-induced stabilization during the guanidine hydrochloride- and thermal-induced denaturation of NAD-glycohydrolase from the venom of Agkistrodon acutus

NAD-glycohydrolase (AA-NADase) from Agkistrodon acutus venom is a unique multicatalytic enzyme with both NADase and AT(D)Pase-like activities. Among all identified NADases, only AA-NADase is a disulfide-linked dimer and contains Cu(2+). Cu(2+) and disulfide bonds are essential for its multicatalytic activity. In this study, the effects of Cu(2+) and disulfide-bonds on guanidine hydrochloride (GdnHCl)- and thermal-induced unfolding of AA-NADase have been investigated by fluorescence, circular dichroism (CD) and differential scanning calorimetry (DSC). Cu(2+) and disulfide bonds not only increase the free energy change during the GdnHCl-induced unfolding as determined by fluorescence, but also increase the overall enthalpy change and the transition temperature during the thermal-induced unfolding as determined by CD and DSC. The slope of the GdnHCl-induced unfolding curve at its midpoint and the heat capacity of thermal-induced unfolding are slightly affected by Cu(2+) but significantly decrease after reduction of three disulfide-bonds. This work suggests that Cu(2+) stabilizes the folded state by increasing the enthalpy of unfolding, while disulfide-bonds stabilize the folded state by increasing the enthalpy of unfolding and stabilizing the packing of hydrophobic residues. Thus both Cu(2+) and disulfide bonds play a structural role in its multicatalytic activity.     

Cell expansion and microtubule behavior in ray floret petals of Gerbera hybrida: responses to light and gibberellic acid

It is still unclear how light and gibberellins are integrated to regulate petal size. Here, we report that light improves both the length and the width of the ray floret petals in G. hybrid, but GA(3) promotes only the petal length. It is also revealed that the control of the petal size by light and GA(3) depends on modulating the cell size, which is governed by the behavior of cortical microtubule.Light and gibberellins are important regulators of plant organ growth. However, little is known about their roles in petal size determination. Here, we report how light and gibberellic acid (GA(3)) signals are integrated to regulate the ray floret (Rf) size in Gerbera hybrida. The inflorescences of G. hybrida at stages 1.5 were cultivated in vitro for 9 d followed by the determination of the Rf petal size. Results demonstrated that the light signal significantly enhanced both the length and the width of Rf petals, but GA(3) promoted only the petal length. Moreover, GA(3) displayed a synergistic positive effect on the length but an antagonistic effect on the width with the light signal. Measurements of the petal cells revealed that the cell size, not the cell number, exhibited a dominant contribution to the petal size in response to light and GA(3) signals. Furthermore, light and GA(3) signals not only induced an obvious reorientation of cortical microtubules (MTs) into transverse arrays but also promoted the recovery of the MT lengths in petal cells following oryzalin (an MT depolymerizing agent) treatment. Importantly, disruption of the MT lengths and arrays by oryzalin could inhibit the cell expansion and the petal enlargement induced by light or/and GA(3) signals. Taken together, it is concluded that the control of the petal size by light and GA(3) signals mainly depends on modulating the cell size and, moreover, the organization of the cortical MTs plays a crucial role in the control of the cell size and hence the Rf petal growth.