Host-induced silencing of MpPar6 confers Myzus persicae resistance in transgenic rape plants

Plant-mediated RNA interference(RNAi)has emerged as a promising technology for insect control.The green peach aphid,Myzus persicae,feeds on over 400 species of host plants.Brassica napus(rape)is the second most important oilseed crop worldwide.Myzus persicae is highly reproductive and causes severe damage to the rape plants due to its quite flexible life cycle.In this study,we tested the RNAi effects of transgenic rape plants on M.persicae.By in vitro feeding M.persicae with artificial diets containing double-stranded RNAs(dsRNAs)targeting seven aphid genes,we identified a new gene encoding the partitioning-defective protein 6(Par6)as the most potent RNAi target.Tissue-and stage-expression analysis of Par6 suggested this gene is highly expressed in the embryo and adult stage of M.persicae.We next generated transgenic rape plants expressing ds Par6 by Agrobacteriummediated transformation and obtained nine independent transgenic lines.Compared to wild-type control plants,transgenic rape lines expressing ds Par6 showed strong resistance to M.persicae.Feeding assays revealed that feeding transgenic rape plants to M.persicae significantly decreased MpPar6 expression and survival rate and impaired fecundity.Furthermore,we showed that the resistance levels to M.persicae are positively correlated with ds Par6 expression levels in transgenic rape plants.Our study demonstrates that transgenic rape plants expressing ds Par6 are efficiently protected from M.persicae.Interfering with the genes involved in embryo development could be the effective RNAi targets for controlling aphids and potentially other insect pests.

基于近40年降水数据的全国七大地理区屋面雨水利用可行性研究

雨水利用是解决城市水资源危机和缓解城市内涝的有效途径,降水特征和雨水利用可行性是衡量雨水利用工程可行与否的关键指标。基于全国各监测站点1980—2020年降水量数据,分析了全国七大地理区的降水特征;运用水量平衡原理,建立了日降水量-用水量平衡模型,探究了屋面雨水利用的影响因素,分析了全国七大地理区7座典型城市的雨水利用可行性。结果表明:1)我国年均降水量受地形和气候差异的影响,呈现出由东南向西北逐渐递减的趋势;季节降水量和年均降水量空间分布趋势一致,各季节降水量以夏季最高、春秋季次之;降水集中度分布特征与降水量不同,年均降水量较小的地区降水相对更加集中。2)降水特征、雨水罐设计容积、集雨面积、日用水需求量、节水效率和溢流率对不同地区雨水利用可行性具有显著影响。降水量越大的地区雨水利用可靠性越高,不同地理区7座典型城市雨水利用可靠性顺序为广州>武汉>南京>昆明>哈尔滨>北京>西宁,但各城市的雨水利用可靠性均难以达到100%。3)雨水利用可靠性随雨水罐容积的增大而增大,但当雨水罐容积达到10m3时,其增加显著减缓;雨水利用可靠性与集雨面积成正比,与日用水需求量成反比;节水效率的曲线趋势变化与可靠性趋势变化基本一致,但是数值上高于可靠性;合理控制溢流率可以提高雨水利用效益,在实际应用中应结合可靠性和溢流率来确定雨水罐最佳尺寸。总体上,华南、华东、西南地区进行雨水利用的可行性较高,东北、华北地区次之,而西北地区的可行性最低。

Functional conservation of the meiotic genes SDS and RCK in male meiosis in the monocot rice

The Arabidopsis SDS （SOLO DANCERS） and RCK （ROCK-N-ROLLERS） genes are important for male meiosis, but it is still unknown whether they represent conserved functions in plants. We have performed phylogenetic analyses of SDS and RCK and their respective homologs, and identified their putative orthologs in poplar and rice. Quantitative real-time RT-PCR analysis indicated that rice SDS and RCK are expressed preferentially in young flowers, and transgenic RNAi rice lines with reduced expression of these genes exhibited normal vegetative development, but showed significantly reduced fertility with partially sterile flowers and defective pollens. SDS deficiency also caused a decrease in pollen amounts. Further cytological examination of male meiocytes revealed that the SDS deficiency led to defects in homolog interaction and bivalent formation in meiotic prophase I, and RCK deficiency resulted in defective meiotic crossover formation. These results indicate that rice SDS and RCK genes have similar functions to their Arabidopsis orthologs. Because rice and Arabidopsis, respectively, are members of monocots and eudicots, two largest groups of flowering plants, our results suggest that the functions of SDS and RCK are likely conserved in flowering plants.

基于蚁群算法的机头结构二级布局优化方法

针对民机机头结构布局设计的拓扑变量与尺寸优化变量共存的混合变量设计问题,改进一般的蚁群算法,提出多城市层的蚁群算法转移概率准则,建立基于蚁群算法拓扑优化及准则法尺寸优化设计的二级结构布局优化法,第一级针对离散设计变量,采用蚁群算法确定结构的拓扑布局;第二级针对连续设计变量,基于准则法完成结构在前一级布局下的尺寸优化设计。优化设计结果表明:在满足强度和刚度约束下,相较于初始结构,杆件结构总重量减轻32%,且较常规尺寸优化效果更好。

A faster killing effect of plastid-mediated RNA interference on a leaf beetle through induced dysbiosis of the gut bacteria

The expression of double-stranded RNAs(dsRNAs)from the plastid genome has been proven to be an effective method for controlling herbivorous pests by targeting essential insect genes.However,there are limitations to the efficiency of plastid-mediated RNA interference(PM-RNAi)due to the initial damage caused by the insects and their slow response to RNA interference.In this study,we developed transplastomic poplar plants that express dsRNAs targeting the b-Actin(dsACT)and Srp54k(dsSRP54K)genes of Plagiodera versicolora.Feeding experiments showed that transplastomic poplar plants can cause significantly higher mortality in P.versicolora larvae compared with nuclear transgenic or wild-type poplar plants.The efficient killing effect of PM-RNAi on P.versicolora larvae was found to be dependent on the presence of gut bacteria.Importantly,foliar application of a gut bacterial strain,Pseudomonas putida,will induce dysbiosis in the gut bacteria of P.versicolora larvae,leading to a significant acceleration in the speed of killing by PM-RNAi.Overall,our findings suggest that interfering with gut bacteria could be a promising strategy to enhance the effectiveness of PM-RNAi for insect pest control,offering a novel and effective approach for crop protection based on RNAi technology.

基于静压气悬浮变频离心冷水机组的系统研究

静压气悬浮轴的悬浮技术,是利用多孔质材料做成的轴承,对高压气体节流降压,在轴承和轴之间形成一层薄的气膜,使轴悬浮,实现轴的无接触式工作,从而达到降低摩擦提高工作效率的目的。本论文基于的50冷吨的气悬浮离心制冷机组,名义工况的制冷量为170 kW,制冷能效5.6,IPLV值7.3,通过对该系统及测试数据进行分析,用理论计算制热量和实测制热量之间的差值,得出从100%负荷到25%负荷工况,悬浮轴的供气量的流量,大约在6 g/s~9 g/s,占系统制冷剂循环量的0.82%~2.2%。

Isomaltooligosaccharide and Bacillus regulate the duration of farrowing and weaning-estrous interval in sows during the perinatal period by changing the gut microbiota of sows

This study investigated the effects of isomaltooligosaccharide(IMO)and Bacillus in perinatal diets on the duration of farrowing and post-weaning estrus,serum reproductive hormone concentrations,and gut microbiota and its metabolites of sows.Multiparous sows(n=130)were fed diets without IMO(control,CON group),or diets containing only IMO(IMO group),IMO and Bacillus subtilis(IMOS group),IMO and Bacillus licheniformis(IMOL group),and IMO and B.subtilis and B.licheniformis(IMOSL group),respectively.The results indicate that the duration of farrowing and post-weaning estrus was shorter in sows in the IMOS,IMOL,and IMOSL groups,and the weaning-estrous interval was lower in sows in the IMOL greoup.In addition,the lowest fecal score was observed in the IMOL group during d 106 to 112 of gestation.Sows in most of the treatment groups had a higher concentration of serum prolactin and prostaglandin at farrowing,but a lower serum concentration of estradiol,oxytocin,and progesterone on d 18 of lactation than sows in the CON group.The treatment groups had a higher abundance of Candidatus Methanoplasma and Bacillus and a lower abundance of Escherichia-Shigella in their feces at farrowing.Furthermore,the treatment groups had higher concentrations of total short-chain fatty acids(SCFA)in feces at farrowing and a higher concentration of branched fatty acids in feces on d 18 of lactation.Furthermore,the abun-dance of Bacillus in feces was positively correlated with serum prostaglandin concentrations and fecal total SCFA of sows at farrowing,but was negatively correlated with the duration of farrowing.Overall,dietary IMO and Bacillus supplementation affected the concentration of serum reproductive hormones and the duration of farrowing and post-weaning estrus,and the gut microbiota is a key factor.

Plastid engineering with an efficient RNAi delivery system based on bacteriophage MS2 virus-like particles enhances plant resistance to cotton bollworm

Dear Editor,RNA-based pesticides are approaching the market,offering great potential to control agricultural pests such as the coleopteran insect Diabrotica virgifera virgifera(Head et al.,2017).However,application to lepidopteran pests has been hampered by their inconsistent response to RNA interference(RNAi).As a notorious lepidoptera pest,Helicoverpa armigera feeds on over 300 species of host plants(Fu et al.,2022).Although transgenicplants expressingdouble-stranded RNAs or microRNAs that target essential insect genes can inhibit the growth of larvae,complete protection of the plants and efficient killing of this insect have not been achieved(Bally et al.,2020;Chung et al.,2021;Li et al.,2023).The relatively low RNAi efficiency in lepidopterans is mainly attributable to the degradation and intracellular sequestration of double-stranded RNA(Shukla et al.,2016;Zhu and Palli,2020).To overcome these obstacles and improve RNAi efficiency in H.armigera,we attempted to deliver RNAi molecules using a bacteriophage MS2 virus-like particle(VLP)-based delivery system(Wang et al.,2016).

Control of a sap-sucking insect pest by plastidmediated RNA interference

Expression of double-stranded RNAs in plastids offers great potential for the efficient control of chewing insects.However,many insect pests do not consume plant tissue but rather feed on the host plant by sucking sap from the vascular system.Whether or not plastid-mediated RNA interference(RNAi)can be employed to control sap-sucking insects is unknown.Here,we show that five species of sap-sucking hemipteran insects acquire plastid RNA upon feeding on plants.We generated both nuclear transgenic and transplastomic tobacco plants expressing double-stranded RNAs targeting the MpDhc64C gene,a newly identified efficient target gene of RNAi whose silencing causes lethality to the green peach aphid Myzus persicae.In a whole-plant bioassay,transplastomic plants exhibited significant resistance to aphids,as evidenced by reduced insect survival,impaired fecundity,and decreased weight of survivors.The protective effect was comparable with that conferred by the best-performing nuclear transgenic plants.We found that the proportion of aphids on mature leaves of transplastomic plants was significantly lower compared with that of nuclear transgenic plants.When aphids were allowed to infest.only the mature leaves,transplastomic plants grew significantly faster and were overall better protected from the pest compared with nuclear transgenic plants.When monitored by electrical-penetration-graph analyses and aphid avoidance response experiments,the insects displayed remarkable alterations in feeding behavior,which was different in nuclear transgenic and transplastomic plants,likely reflecting specific avoidance strategies to toxic RNA molecules.Taken together,our study demonstrates that plastid-mediated RNAi provides an efficient strategy for controlling at least some sap-sucking insect pests,even though there is most likely no or only very little chloroplast RNA in the sap.

Synthesis of super-fine L1_(0)-FePt nanoparticles with high ordering degree by two-step sintering under high magnetic field

Super-fine L1_(0)-Fe Pt nanoparticles(NPs)with high ordering degree were successfully prepared by a modified two-step sintering method,which includes low-temperature pre-sintering,and the high magnetic field(HMF)assisted post-sintering processes.The particle size of the L1_(0)-FePt NPs was obviously refined by lowering the sintering temperature.By applying the HMF during the post-sintering process,the fine size characteristics of L1_(0)-Fe Pt NPs were retained,and the ordering degree was significantly improved.The L1_(0)-Fe Pt NPs with sizes of about 4.5 nm,ordering degree of 0.940,and coercivity of 22.01 k Oe were obtained by this two-step sintering under a magnetic field of 12 T.The mechanism investigation of HMF enhancing the ordering degree indicates that the HMF enhances lattice distortion and magnetization energy(Zeeman energy).The enhanced lattice distortions cause high stress existing in the lattice,which can effectively promote the disordered-order transition.When the magnetic field reaches to 3 T,the Zeeman energy of the NPs is higher than the thermal disturbing energy of the NPs,and the magnetization effect is stronger.Therefore,the HMF(higher than 3 T)can obviously improve the disorder-order transition by lowering the energy barrier and accelerating the orderly diffusions of atoms.The HMF is a promising assistant to synthesize the L1_(0)-phase NPs with both of high ordering degree and super-fine size.

Coupled aerobic and anoxic biodegradation for quinoline and nitrogen removals

Quinoline （C9H7N） commonly occurs in wastewaters from the chemical, pharmaceutical, and dyeing industries. As quinoline is biodegraded, nitrogen is released as ammonium. Total-N removal requires that the ammonium-N be nitrified and then denitrified. The objective of this study was to couple quinoline biodegradation with total-N removal. In a proof-of-concept step, activated sludge was sequenced from aerobic to anoxic stages. The ammonium nitrogen released from quinoline biodegradation in the aerobic stage was nitrified to nitrate in parallel. Anoxic biodegradation of the aerobic effluent then brought about nitrogen and COD removals through denitrification. Then, simultaneous quinoline biodegradation and total-N removal were demonstrated in a novel airlift internal loop biofilm reactor （AILBR） having aerobic and anoxic zones. Experimental results showed that the AILBR could achieve complete removal of quinoline, 91% COD removal, and 85% total-N removal when glucose added as a supplemental electron donor once nitrate was formed.

Oral administration of dibutyryl adenosine cyclophosphate improved growth performance in weaning piglets by enhancing lipid fatty acids metabolism

Dibutyryl adenosine cyclophosphate(dbc AMP-Ca), an analog of cyclic adenosine monophosphate(c AMP), plays greater roles in regulating physiological activities and energy metabolism than c AMP. The aim of this study was to investigate the effect of oral administration of dbc AMP-Ca on growth performance and fatty acids metabolism in weaning piglets. A total of 14 early weaning piglets(7 ± 1 d of age,3.31 ± 0.09 kg, Landrace ? Large White ? Duroc) were randomly divided into 2 groups: control group and dbc AMP-Ca group, and the piglets received 7 m L of 0.9% Na Cl or 1.5 mg dbc AMP-Ca dissolved in 7 m L of 0.9% Na Cl per day for 10 d, respectively. The results showed that the average daily gain(ADG)increased by 109.17%(P < 0.05) in the dbc AMP-Ca group compared with the control group. Besides,dbc AMP-Ca significantly decreased blood high density lipoprotein cholesterol(HDLC) concentration(P < 0.05) and significantly increased blood low density lipoprotein cholesterol(LDLC) concentration(P < 0.05) compared with the control group. Further, liver C18:2 n6 t content significantly increased in dbc AMP-Ca group(P < 0.05) compared with the control group. With the increase of C18:2 n6 t content,the m RNA expression levels of peroxisome proliferator-activated receptor a(PPARa) and hormone sensitive glycerol three lipase(HSL), of which genes are related to lipid metabolism, were also significantly increased(P < 0.05 or P < 0.01). All of the results indicated that dbc AMP-Ca improved the ADG, which was probably done by regulating fatty acids metabolism in the liver of weaning piglets.

Advancing organelle genome transformation and editing for crop improvement

Plant cells contain three organelles that harbor DNA:the nucleus,plastids,and mitochondria.Plastid transformation has emerged as an attractive platformfor the generation of transgenic plants,also referred to as transplastomic plants.Plastid genomes have been genetically engineered to improve crop yield,nutritional quality,and resistance to abiotic and biotic stresses,as well as for recombinant protein production.Despite many promising proof-of-concept applications,transplastomic plants have not been commercialized to date.Sequence-specific nuclease technologies are widely used to precisely modify nuclear genomes,but these tools have not been applied to edit organelle genomes because the efficient homologous recombination system in plastids facilitates plastid genome editing.Unlike plastid transformation,successful genetic transformation of higher plant mitochondrial genome transformation was tested in several research group,but not successful to date.However,stepwise progress has been made in modifying mitochondrial genes and their transcripts,thus enabling the study of their functions.Here,we provide an overview of advances in organelle transformation and genome editing for crop improvement,and we discuss the bottlenecks and future development of these technologies.

Dendritic Boundary Corrosion of AA2198 Weld Using Fiber Laser Welding with Al–Cu Filler Wire

The microstructures and corrosion behaviors of AA2198-T851 alloy and weld were analyzed under corrosive conditions. Weld was formed using an innovative fiber laser welding process with AA2319 Al-Cu filler wire. The metallurgic morphology and distribution of the chemical compositions were determined using imaging techniques such as optical micrograph, scanning electron micrograph, high-resolution transmission electron microscopy, energy-dispersive X-ray spectrometry and X-ray diffraction. Corrosion was evaluated using an immersion test and electrochemical impedance spectroscopy in 3.5% NaC1 solution at room temperature. Results indicate that the parent alloy suffered from pitting corrosion during the initial 4-h immersion which was caused by the inhomogeneous distribution of its chemical compo- nents and the different intermetallics formed during the rolling process. The weld experienced dendritic boundary corrosion under the same conditions due to the addition of the Al-Cu filler and rapid solidification during laser welding, which led to the precipitates Cu enrichment along the grain boundary. When a welding joint was immersed in the solution for 5 days, a big crack was observed across the center of the weld. In comparison, there was good corrosion resistance in the heat- affected zone with a compact protective film.