Effects of grazing on plant species diversity and carbon partitioning in semiarid rangelands of northeastern China

Grasslands are one of the most widespread landscapes worldwide, covering approximately one-fifth of the world’s land surface, where grazing is a common practice. How carbon storage responds to grazing in steppes remains poorly understood. We quantified the effects of grazing on community composition and species diversity, and carbon storage in two typical grasslands of northeastern China, one in Horqin and the other one in Hulunbeier. In both grasslands, grazing did not influence plant species diversity. However, it substantially decreased aboveground carbon by 31% and 54% in Horqin and Hulunbeier, respectively. Fenced and grazing treatments showed a similar belowground carbon at both locations. The predominant carbon pool in the study grassland ecosystem was found in the upper 100 cm soil depth, from 98.2 to 99.1% of the total carbon storage. There were no significant effects of grazing on soil carbon neither in the whole profile nor in the uppermost 20 cm soil depth in the two study grasslands. Studies on the effects of varying rangeland management, such as region disparity and grazing systems, may have important consequences on species diversity and carbon partitioning, and thus on rangeland stability and ecosystem functioning.     

Differential regulation of morphine antinociceptive effects by endogenous enkephalinergic system in the forebrain of mice

Background

Mice lacking the preproenkephalin (ppENK) gene are hyperalgesic and show more anxiety and aggression than wild-type (WT) mice. The marked behavioral changes in ppENK knock-out (KO) mice appeared to occur in supraspinal response to painful stimuli. However the functional role of enkephalins in the supraspinal nociceptive processing and their underlying mechanism is not clear. The aim of present study was to compare supraspinal nociceptive and morphine antinociceptive responses between WT and ppENK KO mice.

Results

The genotypes of bred KO mice were confirmed by PCR. Met-enkephalin immunoreactive neurons were labeled in the caudate-putamen, intermediated part of lateral septum, lateral globus pallidus, intermediated part of lateral septum, hypothalamus, and amygdala of WT mice. Met-enkephalin immunoreactive neurons were not found in the same brain areas in KO mice. Tail withdrawal and von Frey test results did not differ between WT and KO mice. KO mice had shorter latency to start paw licking than WT mice in the hot plate test. The maximal percent effect of morphine treatments (5 mg/kg and 10 mg/kg, i.p.) differed between WT and KO mice in hot plate test. The current source density (CSD) profiles evoked by peripheral noxious stimuli in the primary somatosenstory cortex (S1) and anterior cingulate cortex (ACC) were similar in WT and KO mice. After morphine injection, the amplitude of the laser-evoked sink currents was decreased in S1 while the amplitude of electrical-evoked sink currents was increased in the ACC. These differential morphine effects in S1 and ACC were enhanced in KO mice. Facilitation of synaptic currents in the ACC is mediated by GABA inhibitory interneurons in the local circuitry. Percent increases in opioid receptor binding in S1 and ACC were 5.1% and 5.8%, respectively.

Conclusion

The present results indicate that the endogenous enkephalin system is not involved in acute nociceptive transmission in the spinal cord, S1, and ACC. However, morphine preferentially suppressed supraspinal related nociceptive behavior in KO mice. This effect was reflected in the potentiated differential effects of morphine in the S1 and ACC in KO mice. This potentiation may be due to an up-regulation of opioid receptors. Thus these findings strongly suggest an antagonistic interaction between the endogenous enkephalinergic system and exogenous opioid analgesic actions in the supraspinal brain structures.     

Advances in the use of terminal restriction fragment length polymorphism (T-RFLP) analysis of 16S rRNA genes to characterize microbial communities

Terminal restriction fragment length polymorphism (T-RFLP) analysis is a popular high-throughput fingerprinting technique used to monitor changes in the structure and composition of microbial communities. This approach is widely used because it offers a compromise between the information gained and labor intensity. In this review, we discuss the progress made in T-RFLP analysis of 16S rRNA genes and functional genes over the last 10 years and evaluate the performance of this technique when used in conjunction with different statistical methods. Web-based tools designed to perform virtual polymerase chain reaction and restriction enzyme digests greatly facilitate the choice of primers and restriction enzymes for T-RFLP analysis. Significant improvements have also been made in the statistical analysis of T-RFLP profiles such as the introduction of objective procedures to distinguish between signal and noise, the alignment of T-RFLP peaks between profiles, and the use of multivariate statistical methods to detect changes in the structure and composition of microbial communities due to spatial and temporal variation or treatment effects. The progress made in T-RFLP analysis of 16S rRNA and genes allows researchers to make methodological and statistical choices appropriate for the hypotheses of their studies.     

Characterization of a novel thermophilic, cellulose-degrading bacterium Paenibacillus sp. strain B39

Aims:  The aims of this study were to identify and characterize the novel thermophilic, cellulose-degrading bacterium Paenibacillus sp. strain B39.
Methods and Results:  Strain B39 was closely related to Paenibacillus cookii in 16S rRNA gene sequence. Nonetheless, this isolate can be identified as a novel Paenibacillus sp. with respect to its physiological characteristics, biochemical reactions, and profiles of fatty acid compositions. A cellulase with both CMCase and avicelase activities was secreted from strain B39 and purified by ion-exchange chromatography. By sodium dodecyl sulfate–polyacrylamide gel electrophoresis analysis, the molecular weight of B39 cellulase was determined as 148 kDa, which was much higher than other cellulases currently reported from Paenibacillus species. The enzyme showed a maximum CMCase activity at 60°C and pH 6·5. Addition of 1 mmol l⁻¹ of Ca²⁺ markedly enhanced both CMCase and avicelase activities of the enzyme.
Conclusions:  We have identified and characterized a novel thermophilic Paenibacillus sp. strain B39 which produced a high-molecular weight cellulase with both CMCase and avicelase activities.
Significance and Impact of the Study:  Based on the ability to hydrolyse CMC and avicel, the cellulase produced by Paenibacillus sp. strain B39 would have potential applications in cellulose biodegradation.     

Poly(A)-binding protein-interacting protein 1 binds to eukaryotic translation initiation factor 3 to stimulate translation

Poly(A)-binding protein (PABP) stimulates translation initiation by binding simultaneously to the mRNA poly(A) tail and eukaryotic translation initiation factor 4G (eIF4G). PABP activity is regulated by PABP-interacting (Paip) proteins. Paip1 binds PABP and stimulates translation by an unknown mechanism. Here, we describe the interaction between Paip1 and eIF3, which is direct, RNA independent, and mediated via the eIF3g (p44) subunit. Stimulation of translation by Paip1 in vivo was decreased upon deletion of the N-terminal sequence containing the eIF3-binding domain and upon silencing of PABP or several eIF3 subunits. We also show the formation of ternary complexes composed of Paip1-PABP-eIF4G and Paip1-eIF3-eIF4G. Taken together, these data demonstrate that the eIF3-Paip1 interaction promotes translation. We propose that eIF3-Paip1 stabilizes the interaction between PABP and eIF4G, which brings about the circularization of the mRNA.     

Hyperbaric oxygen induces placental growth factor expression in bone marrow-derived mesenchymal stem cells

The bone marrow is home to mesenchymal stem cells (MSCs) that are able to differentiate into many different cell types. The effect of hyperbaric oxygen (HBO) on MSCs is poorly understood. Placental growth factor (PlGF) is an attractive therapeutic agent for stimulating revascularization of ischemic tissue. HBO has been shown to improve diabetic wound healing by increase circulating stem cells. We hypothesized that HBO induces PlGF expression in bone marrow-derived MSCs. The MSCs were obtained from adult human bone marrow and expanded in vitro. The purity and characteristics of MSCs were identified by flow cytometry and immunophenotyping. HBO at 2.5 ATA (atmosphere absolute) significantly increased PlGF protein and mRNA expression. The induction of PlGF protein by HBO was significantly blocked by the addition of N-acetylcysteine, while wortmannin, PD98059, SP600125 and SB203580 had no effect on PlGF protein expression. However, the specific inhibitor of nitric oxide synthase, L-NAME did not alter the PlGF protein expression induced by HBO. HBO significantly increased the reactive oxygen species production and pretreatment with N-acetylcysteine significantly blocked the induction of reactive oxygen species by HBO. HBO significantly increased the migration and tube formation of MSCs and pretreatment with N-acetylcysteine and PlGF siRNA significantly blocked the induction of migration and tube formation by HBO. In conclusion, HBO induced the expression of PlGF in human bone marrow-derived MSCs at least through the oxidative stress-related pathways, which may play an important role in HBO-induced vasculogenesis.     

Versatile role for hnRNP D isoforms in the differential regulation of cytoplasmic mRNA turnover

An important emerging theme is that heterogeneous nuclear ribonucleoproteins (hnRNPs) not only function in the nucleus but also control the fates of mRNAs in the cytoplasm. Here, we show that hnRNP D plays a versatile role in cytoplasmic mRNA turnover by functioning as a negative regulator in an isoform-specific and cell-type-dependent manner. We found that hnRNP D discriminates among the three classes of AU-rich elements (AREs), most effectively blocking rapid decay directed by class II AREs found in mRNAs encoding cytokines. Our experiments identified the overlapping AUUUA motifs, one critical characteristic of class II AREs, to be the key feature recognized in vivo by hnRNP D for its negative effect on ARE-mediated mRNA decay. The four hnRNP D isoforms, while differing in their ability to block decay of ARE-containing mRNAs, all potently inhibited mRNA decay directed by another mRNA cis element that shares no sequence similarity with AREs, the purine-rich c-fos protein-coding region determinant of instability. Further experiments indicated that different mechanisms underlie the inhibitory effect of hnRNP D on the two distinct mRNA decay pathways. Our study identifies a potential mechanism by which cytoplasmic mRNA turnover can be differentially and selectively regulated by hnRNP D isoforms in mammalian cells. Our results support the notion that hnRNP D serves as a key factor broadly involved in general mRNA decay.     

Synergistic effect of angiopoietin-1 and vascular endothelial growth factor on neoangiogenesis in hypercholesterolemic rabbit model with acute hindlimb ischemia

Vascular endothelial growth factor (VEGF) and angiopoietin-1 (Ang1) are essential for vascular integrity and development. The purpose of the study was to test the hypothesis that Ang1 will promote angiogenic response to VEGF in the spontaneous Watanabe heritable hypercholesterolemic (WHHL) rabbit model of acute hindlimb ischemia. Immediately after the ligation of the external iliac artery and the excision of the common and superficial femoral artery in one female WHHL rabbit, 250 microg of phVEGF(165) (n = 8), 500 microg of pAng1* (n = 8), or 250 microg of phVEGF(165) plus 500 microg of pAng1* (n = 8) was injected intramuscularly into the ischemic hindlimb muscles. Gross appearance of ischemic limb, collateral vessel formation and limb perfusion were assessed 30 days after treatment. The incidence of ischemic limb necrosis was higher in the animals treated by phVEGF(165) or by pAng1* than in those treated by phVEGF(165) plus pAng1* (100%, 75% and 14.3%, respectively; P = 0.002). Animals in the combination therapy group had a significantly higher calf blood pressure ratio at day 30 (VEGF plus Ang1* = 0.84 +/- 0.06; VEGF = 0.54 +/- 0.01; Ang1* = 0.59 +/- 0.05; P < 0.01). A combination therapy of VEGF plus Ang*1 had a significantly higher (P < 0.01) angiographic score than either therapy alone. Capillary density (P < 0.05) and capillary/muscle fiber ratio (P < 0.01) of the combination therapy group were also significantly higher than that of either therapy alone. In conclusion, Ang1 can potentiate the angiogenic response to VEGF in the hyperlipidemic rabbit model of acute hindlimb ischemia. Intramuscular administration of cytokines on revascularization of the ischemic hindlimb model of hyperlipidemic rabbit is feasible.     

Pathological and biochemical analysis of dilated cardiomyopathy of broiler chickens--an animal model

Forty-seven birds (M/F = 33/14) with natural outbreak dilated cardiomyopathy (DCM) of right ventricle (RV) and 33 birds with artificially cool-induced DCM hearts were studied. Clinically, 20 severe and 13 mild DCM cases were induced during five weeks and the peak morbidity was in the 2nd week. The progressive dilatation of RV and hypokinesis of septum was shown by echocardiography. At autopsy, the ratio of heart weights to the body weights was increased, the ratio of RV weight to the total ventricle significantly increased, especially in the severe DCM cases (P < 0.05). The RV was dilated and the wall thickness was increased and finally both RV and left ventricle (LV) were markedly dilated and the septum became thinner. The struts, weave and coil demonstrated by silver impregnation stain were fragmented, dissociated and overstretched. The promatrix metalloproteinases (MMP)-2, -9 and active MMP-2 were markedly increased in natural outbreak DCM cases, especially in the RV (P < 0.05). The proMMP-2 and active MMP-2 was increased in the cool induced DCM cases, especially in the RV of severe DCM (P < 0.05). These indicated that both the natural outbreak and the artificially induced DCM of broiler chickens are ideal DCM animal models.