Role of Human-Mediated Dispersal in the Spread of the Pinewood Nematode in China

Background

Intensification of world trade is responsible for an increase in the number of alien species introductions. Human-mediated dispersal promotes not only introductions but also expansion of the species distribution via long-distance dispersal. Thus, understanding the role of anthropogenic pathways in the spread of invading species has become one of the most important challenges nowadays.

Methodology/Principal Findings

We analysed the invasion pattern of the pinewood nematode in China based on invasion data from 1982 to 2005 and monitoring data on 7 locations over 15 years. Short distance spread mediated by long-horned beetles was estimated at 7.5 km per year. Infested sites located further away represented more than 90% of observations and the mean long distance spread was estimated at 111–339 km. Railways, river ports, and lakes had significant effects on the spread pattern. Human population density levels explained 87% of the variation in the invasion probability (P<0.05). Since 2001, the number of new records of the nematode was multiplied by a factor of 5 and the spread distance by a factor of 2. We combined a diffusion model to describe the short distance spread with a stochastic, individual based model to describe the long distance jumps. This combined model generated an error of only 13% when used to predict the presence of the nematode. Under two climate scenarios (stable climate or moderate warming), projections of the invasion probability suggest that this pest could expand its distribution 40–55% by 2025.

Conclusions/Significance

This study provides evidence that human-induced dispersal plays a fundamental role in the spread of the pinewood nematode, and appropriate control measures should be taken to stop or slow its expansion. This model can be applied to Europe, where the nematode had been introduced later, and is currently expanding its distribution. Similar models could also be derived for other species that could be accidentally transported by humans.     

Fusion of Self-Assembling Amphipathic Oligopeptides with Cyclodextrin Glycosyltransferase Improves 2-O-d-Glucopyranosyl-l-Ascorbic Acid Synthesis with Soluble Starch as the Glycosyl Donor

In this study, we fused six self-assembling amphipathic peptides (SAPs) with cyclodextrin glycosyltransferase (CGTase) from Paenibacillus macerans to catalyze 2-O-d-glucopyranosyl-l-ascorbic acid (AA-2G) production with cheap substrates, including maltose, maltodextrin, and soluble starch as glycosyl donors. The results showed that two fusion enzymes, SAP5-CGTase and SAP6-CGTase, increased AA-2G yields to 2.33- and 3.36-fold that of wild-type CGTase when soluble starch was used as a substrate. The cyclization activities of these enzymes decreased, while disproportionation activities increased. Enzymatic characterization of the two fusion enzymes was performed, and kinetics analysis of AA-2G synthesis confirmed the enhanced soluble starch specificity of SAP5-CGTase and SAP6-CGTase compared to that in the wild-type CGTase. As revealed by structure modeling of the fusion and wild-type CGTases, enhanced substrate-binding capacity may result from the increased number of hydrogen bonds present after fusion. This study demonstrates an effective protein fusion approach to improving the substrate specificity of CGTase for AA-2G synthesis. Fusion enzymes, especially SAP6-CGTase, are promising starting points for further development through protein engineering.     

Comparison between Gd-DTPA and several bisamide derivatives as potential MRI contrast agents

Four neutral gadolinium complexes of diethylenetriaminepentaacetic acid (DTPA)-bisamide derivatives have been synthesized and characterized. Their potential application as tissue-specific and low-osmolarity MRI contrast agents has been evaluated by in vitro and in vivo experiments. Their measured relaxivities in D(2)O, bovine serum albumin and human serum transferrin solutions showed favorable relaxation ability. In vivo studies have proven that Gd(DTPA-BDMA), Gd(DTPA-BIN), and Gd(cyclic-DTPA-1,2-pn) could be promising liver-specific MRI contrast agents and Gd(DTPA-BDMA), and Gd(cyclic-DTPA-1,2-pn) have favorable renal excretion capability. Among them, Gd(cyclic-DTPA-1,2-pn) is a more powerful hepatic contrast agent and Gd(DTPA-BIN) provides the stable imaging contrast for several hours. They also show a lower toxicity.     

A new bacteria-free strategy induced by MaGal2 facilitates pinewood nematode escape immune response from its vector beetle

Symbiotic microbes play a crucial role in regulating parasite–host interactions; however, the role of bacterial associates in parasite–host interactions requires elucidation. In this study, we showed that, instead of introducing numerous symbiotic bacteria, dispersal of 4th-stage juvenile (J_IV) pinewood nematodes (PWNs), Bursaphelenchus xylophilus, only introduced few bacteria to its vector beetle, Monochamus alternatus (Ma). J_IV showed weak binding ability to five dominant bacteria species isolated from the beetles’ pupal chamber. This was especially the case for binding to the opportunistic pathogenic species Serratia marcescens; the nematodes’ bacteria binding ability at this critical stage when it infiltrates Ma for dispersal was much weaker compared with Caenorhabditis elegans, Diplogasteroides asiaticus, and propagative-stage PWN. The associated bacterium S. marcescens, which was isolated from the beetles’ pupal chambers, was unfavorable to Ma, because it caused a higher mortality rate upon injection into tracheae. In addition, S. marcescens in the tracheae caused more immune effector disorders compared with PWN alone. Ma_Galectin2 (MaGal2), a pattern-recognition receptor, was up-regulated following PWN loading. Recombinant MaGal2 protein formed aggregates with five dominant associated bacteria in vitro. Moreover, MaGal2 knockdown beetles had up-regulated prophenoloxidase gene expression, increased phenoloxidase activity, and decreased PWN loading. Our study revealed a previously unknown strategy for immune evasion of this plant pathogen inside its vector, and provides novel insights into the role of bacteria in parasite–host interactions.     

1963-2012年新疆棉花需水量时空分布特征

研究基于新疆地区54个国家基本气象站1963-2012年的逐日气象资料,采用联合国粮食与农业组织FAO推荐的Penman-Monteith公式及作物系数法,计算了近50年来新疆棉花全育期和各生长阶段需水量。并利用线性趋势估计、MK检验、空间插值法对农作物全育期及各生长阶段需水量年际变化趋势和空间分布特征进行分析。结果表明：1）1963-2012年,新疆54个气象站棉花全育期平均需水量为759 mm,各站变化范围为555-1205 mm,差异明显。其空间分布整体呈现西北向东南递增、南疆大于北疆、东部大于西部的趋势。2）1963-2012年,在棉花的生长初期与发育期,全疆需水量空间分布总体由北向南增大并呈带状。在棉花的生长中期与生长末期,需水量空间分布表现为由西向东增大的格局。3）近50年棉花不同生长阶段需水量总体呈现下降趋势,并且除了生长中期下降趋势较显著外其他都不太明显。其中,生长中期下降速率最大为6.1 mm/10a,发育期及生长末期下降速率次之分别为2 mm/10a和1.3 mm/10a,生长初期下降速率最小,需水量以0.6 mm/10a的速率递减。4）新疆1963-2012年棉花全育期需水量总体呈下降趋势,递减速率平均约为5.3 mm/10a,并在1981年开始发生突变。5）全育期年需水量下降倾向率总体呈现与全育期平均需水量相同的空间分布特征,总体呈现北疆小于南疆、东部大于西部、由西北向东南递增的空间分布特征。     

Crocetin attenuates inflammation and amyloid-β accumulation in APPsw transgenic mice

Background

Crocetin, an agent derived from saffron, has multiple pharmacological properties, such as neuroprotective, anti-oxidant, and anti-inflammatory actions. These properties might benefit the treatment of Alzheimer’s disease (AD). In the present study, we tested whether crocetin attenuates inflammation and amyloid-β (Aβ) accumulation in APPsw transgenic mice, AD mouse models. Cell viability and the levels of Aβ40 and Aβ42 in HeLa cells stably transfected with Swedish mutant APP751 were evaluated. Mice with Swedish mutant APP751 transgene were used as transgenic mouse models of AD, and were orally administrated with crocetin. Aβ protein and inflammatory cytokines were measured with ELISA. NF-κB and P53 were measured with western blot assay. Learning and memory were analyzed with Morris water maze and novel object recognition tests.

Results

Crocetin significantly reduced Aβ40 and Aβ42 secretion in Hela cells without effecting cell viability. In AD transgenic mice, crocetin significantly reduced the pro-inflammatory cytokines and enhanced anti-inflammatory cytokine in plasma, suppressed NF-κB activation and P53 expression in the hippocampus, decreased Aβ in various brain areas, and improved learning and memory deficits.

Conclusion

Crocetin improves Aβ accumulation-induced learning and memory deficit in AD transgenic mice, probably due to its anti-inflammatory and anti-apoptotic functions.

     

Biodiesel production from high acid value waste frying oil catalyzed by superacid heteropolyacid

Transesterification of waste cooking oil with high acid value and high water contents using heteropolyacid H3PW12O40 x 6H2O (PW12) as catalyst was investigated. The hexahydrate form of PW(12) was found to be the most promising catalyst which exhibited highest ester yield 87% for transesterification of waste cooking oil and ester yield 97% for esterification of long-chain palmitic acid, respectively. The PW12 acid catalyst shows higher activity under the optimized reaction conditions compared with conventional homogeneous catalyst sulfuric acid, and can easily be separated from the products by distillation of the excess methanol and can be reused more times. The most important feature of this catalyst is that the catalytic activity is not affected by the content of free fatty acids (FFAs) and the content of water in the waste cooking oil and the transesterification can occur at a lower temperature (65 degrees C), a lower methanol oil ratio (70:1) and be finished within a shorter time. The results illustrate that PW12 acid is an excellent water-tolerant and environmentally benign acid catalyst for production of biodiesel from waste cooking oil.