Strigolactones modulate cotton fiber elongation and secondary cell wall thickening

Cotton is one of the most important economic crops in the world,and it is a major source of fiber in the textile industry.Strigolactones(SLs)are a class of carotenoid-derived plant hormones involved in many processes of plant growth and development,although the functions of SL in fiber development remain largely unknown.Here,we found that the endogenous SLs were significantly higher in fibers at 20 days post-anthesis(DPA).Exogenous SLs significantly increased fiber length and cell wall thickness.Furthermore,we cloned three key SL biosynthetic genes,namely GhD27,GhMAX3,and GhMAX4,which were highly expressed in fibers,and subcellular localization analyses revealed that GhD27,GhMAX3,and GhMAX4 were localized in the chloroplast.The exogenous expression of GhD27,GhMAX3,and GhMAX4 complemented the physiological phenotypes of d27,max3,and max4 mutations in Arabidopsis,respectively.Knockdown of GhD27,GhMAX3,and GhMAX4 in cotton resulted in increased numbers of axillary buds and leaves,reduced fiber length,and significantly reduced fiber thickness.These findings revealed that SLs participate in plant growth,fiber elongation,and secondary cell wall formation in cotton.These results provide new and effective genetic resources for improving cotton fiber yield and plant architecture.

Chemokine platelet factor 4 accelerates peripheral nerve regeneration by regulating Schwann cell activation and axon elongation

Schwann cells in peripheral nerves react to traumatic nerve injury by attempting to grow and regenerate.Howeve r,it is unclear what factors play a role in this process.In this study,we searched a GEO database and found that expression of platelet factor 4 was markedly up-regulated after sciatic nerve injury.Platelet factor is an important molecule in cell apoptosis,diffe rentiation,survival,and proliferation.Further,polymerase chain reaction and immunohistochemical staining confirmed the change in platelet factor 4 in the sciatic nerve at different time points after injury.Enzyme-linked immunosorbent assay confirmed that platelet factor 4 was secreted by Schwann cells.We also found that silencing platelet factor 4 decreased the proliferation and migration of primary cultured Schwann cells,while exogenously applied platelet factor 4 stimulated Schwann cell prolife ration and migration and neuronal axon growth.Furthermore,knocking out platelet factor 4 inhibited the prolife ration of Schwann cells in injured rat sciatic nerve.These findings suggest that Schwann cell-secreted platelet factor 4 may facilitate peripheral nerve repair and regeneration by regulating Schwann cell activation and axon growth.Thus,platelet factor 4 may be a potential therapeutic target for traumatic peripheral nerve injury.

Vital contribution of brassinosteroids to hypoxia-stimulated coleoptile elongation in submerged rice

The rapid elongation of rice(Oryza sativa)coleoptile is pivotal for the plant plumule to evade hypoxia stress induced by submergence,a condition often arising from overirrigation,ponding,rainstorms,or flooding.While brassinosteroids(BRs)are recognized for their diverse roles in plant growth and development,their influence on coleoptile elongation under hypoxic conditions remains largely unexplored.In this study,we demonstrate the significant requirement of BRs for coleoptile elongation in deep water.During coleoptile development,Glycogen Synthase Kinase3-Like Kinase2(GSK2),the central inhibitor of BR signaling in rice,undergoes substantial suppression in deep water but induction in air.In contrast,the dephosphorylated form of BRASSINAZOLE RESISTANT1(OsBZR1),representing the active form of the key BR signaling transcription factor,is induced in water but suppressed in air.Remarkably,the knockout of GSK3-like kinase genes significantly enhances coleoptile elongation in deep water,strongly indicating a vital contribution of BR response to hypoxia-stimulated coleoptile elongation.Transcriptome analysis uncovers both BR-associated and BR-independent hypoxia responses,implicating substance metabolism,redox reactions,abiotic stress responses,and crosstalk with other hormones in the regulation of BR-induced hypoxia responses.In summary,our findings suggest that rice plumules rapidly elongate coleoptiles through the activation of BR response in deep water,enabling them to escape from submergence-induced hypoxia stress.

Chain Elongation Using Native Soil Inocula:Exceptional n-Caproate Biosynthesis Performance and Microbial Mechanisms

This study demonstrates the feasibility and effectiveness of utilizing native soils as a resource for inocula to produce n-caproate through the chain elongation(CE)platform,offering new insights into anaerobic soil processes.The results reveal that all five of the tested soil types exhibit CE activity when supplied with high concentrations of ethanol and acetate,highlighting the suitability of soil as an ideal source for n-caproate production.Compared with anaerobic sludge and pit mud,the native soil CE system exhibited higher selectivity(60.53%),specificity(82.32%),carbon distribution(60.00%),electron transfer efficiency(165.00%),and conductivity(0.59 ms∙cm^(-1)).Kinetic analysis further confirmed the superiority of soil in terms of a shorter lag time and higher yield.A microbial community analysis indicated a positive correlation between the relative abundances of Pseudomonas,Azotobacter,and Clostridium and n-caproate production.Moreover,metagenomics analysis revealed a higher abundance of functional genes in key microbial species,providing direct insights into the pathways involved in n-caproate formation,including in situ CO_(2)utilization,ethanol oxidation,fatty acid biosynthesis(FAB),and reverse beta-oxidation(RBO).The numerous functions in FAB and RBO are primarily associated with Pseudomonas,Clostridium,Rhodococcus,Stenotrophomonas,and Geobacter,suggesting that these genera may play roles that are involved or associated with the CE process.Overall,this innovative inoculation strategy offers an efficient microbial source for n-caproate production,underscoring the importance of considering CE activity in anaerobic soil microbial ecology and holding potential for significant economic and environmental benefits through soil consortia exploration.

Candidate genes conferring ethylene-response in cultivated peanuts determined by BSA-seq and fine-mapping

Ethylene plays essential roles in plant growth,development and stress responses.The ethylene signaling pathway and molecular mechanism have been studied extensively in Arabidopsis and rice but limited in peanuts.Here,we established a sand-culture method to screen pingyangmycin mutagenized peanut lines based on their specific response to ethylene(“triple response”).An ethylene-insensitive mutant,inhibition of peanut hypocotyl elongation 1(iph1),was identified that showed reduced sensitivity to ethylene in both hypocotyl elongation and root growth.Through bulked segregant analysis sequencing,a major gene related to iph1,named AhIPH1,was preliminarily mapped at the chromosome Arahy.01,and further narrowed to a 450-kb genomic region through substitution mapping strategy.A total of 7014 genes were differentially expressed among the ACC treatment through RNA-seq analysis,of which only the Arahy.5BLU0Q gene in the candidate mapping interval was differentially expressed between WT and mutant iph1.Integrating sequence variations,functional annotation and transcriptome analysis revealed that a predicated gene,Arahy.5BLU0Q,encoding SNF1 protein kinase,may be the candidate gene for AhIPH1.This gene contained two single-nucleotide polymorphisms at promoter region and was more highly expressed in iph1 than WT.Our findings reveal a novel ethylene-responsive gene,which provides a theoretical foundation and new genetic resources for the mechanism of ethylene signaling in peanuts.

The bHLH transcription factor CsPIF4 positively regulates high temperature-induced hypocotyl elongation in cucumber

High temperature-induced hypocotyl elongation is a typical thermomorphogenesis trait that may significantly affect early seedling growth and subsequent crop yield.The ambient temperature and endogenous auxin are two critical factors that regulate hypocotyl growth.However,the mechanism of temperature and auxin integration in horticultural plants remains poorly understood.In this study,the roles of the basic helix-loop-helix transcription factor CsPIF4 in regulating auxin biosynthesis genes and the auxin content in the hypocotyl of cucumber(Cucumis sativus L.)seedlings under high temperature were investigated.qRT-PCR and in situ hybridization analysis revealed that expression of CsPIF4 was enhanced in the epidermis and vascular bundles in the hypocotyl of cucumber seedlings in response to high temperature.qRT-PCR and HPLC analysis showed that CsPIF4 positively regulated transcription of the auxin biosynthesis gene CsYUC8 and the auxin content in the hypocotyl under high temperature(35℃).The CRISPR/Cas9-mediated knockout of CsPIF4 resulted in a shorter hypocotyl compared with that of the wild type,together with decreased expression of CsYUC8 and lower auxin content in response to high temperature.Furthermore,biochemical assays showed that CsPIF4 could bind directly to the G-box motif of the CsYUC8 promoter and thereby activate CsYUC8 expression.These findings provide insight into the molecular mechanism of high temperature-mediated hypocotyl elongation in cucumber.

Evolution of pore systems in low-maturity oil shales during thermal upgrading--Quantified by dynamic SEM and machine learning

In-situ upgrading by heating is feasible for low-maturity shale oil,where the pore space dynamically evolves.We characterize this response for a heated substrate concurrently imaged by SEM.We systematically follow the evolution of pore quantity,size(length,width and cross-sectional area),orientation,shape(aspect ratio,roundness and solidity)and their anisotropy—interpreted by machine learning.Results indicate that heating generates new pores in both organic matter and inorganic minerals.However,the newly formed pores are smaller than the original pores and thus reduce average lengths and widths of the bedding-parallel pore system.Conversely,the average pore lengths and widths are increased in the bedding-perpendicular direction.Besides,heating increases the cross-sectional area of pores in low-maturity oil shales,where this growth tendency fluctuates at<300℃ but becomes steady at>300℃.In addition,the orientation and shape of the newly-formed heating-induced pores follow the habit of the original pores and follow the initial probability distributions of pore orientation and shape.Herein,limited anisotropy is detected in pore direction and shape,indicating similar modes of evolution both bedding-parallel and bedding-normal.We propose a straightforward but robust model to describe evolution of pore system in low-maturity oil shales during heating.

Lateral root elongation in maize is related to auxin synthesis and transportation mediated by N metabolism under a mixed NO_(3)^(–) and NH_(4)^(+) supply

A mixed nitrate (NO_(3)^(–)) and ammonium (NH_(4)^(+)) supply can promote root growth in maize (Zea mays),however,the changes in root morphology and the related physiological mechanism under different N forms are still unclear.Here,maize seedlings were grown hydroponically with three N supplied in three different forms (NO_(3)^(–)only,75/25 NO_(3)^(–)/NH_(4)^(+)and NH_(4)^(+)only).Compared with sole NO_(3)^(–)or NH_(4)^(+),the mixed N supply increased the total root length of maize but did not affect the number of axial roots.The main reason was the increased total lateral root length,while the average lateral root (LR) length in each axle was only slightly increased.In addition,the average LR density of 2nd whorl crown root under mixed N was also increased.Compared with sole nitrate,mixed N could improve the N metabolism of roots (such as the N influx rate,nitrate reductase (NR) and glutamine synthase (GS)enzyme activities and total amino content of the roots).Experiments with exogenously added NR and GS inhibitors suggested that the increase in the average LR length under mixed N was related to the process of N assimilation,and whether the NR mediated NO synthesis participates in this process needs further exploration.Meanwhile,an investigation of the changes in root-shoot ratio and carbon (C) concentration showed that C transportation from shoots to roots may not be the key factor in mediating lateral root elongation,and the changes in the sugar concentration in roots further proved this conclusion.Furthermore,the synthesis and transportation of auxin in axial roots may play a key role in lateral root elongation,in which the expression of ZmPIN1B and ZmPIN9 may be involved in this pathway.This study preliminarily clarified the changes in root morphology and explored the possible physiological mechanism under a mixed N supply in maize,which may provide some theoretical basis for the cultivation of crop varieties with high N efficiency.

Evolution of Polymer Melt Conformation and Entanglement under High-Rate Elongational Flow

Using molecular dynamics(MD)simulations,this study explores the fluid properties of three polymer melts with the same number of entanglements,Z,achieved by adjusting the entanglement length Ne,while investigating the evolution of polymer melt conformation and entanglement under high-rate elongational flow.The identification of a master curve indicates consistent normalized linear viscoelastic behavior.Surprising findings regarding the steady-state viscosity at various elongational rates(Wi_(R)>4.7)for polymer melts with the same Z have been uncovered,challenging existing tube models.Nevertheless,the study demonstrates the potential for normalizing the steady-state elongational viscosity at high rates(Wi_(R)>4.7)by scaling with the square of the chain contour length.Additionally,the observed independence of viscosity on the elongational rate at high rates suggests that higher rates lead to a more significant alignment of polymer chains,a decrease in entanglement,and a stretching in contour length of polymer chains.Molecular-level tracking of tagged chains further supports the assumption of no entanglement under rapid elongation,emphasizing the need for further research on disentanglement in polymer melts subjected to high-rate elongational flow.These results carry significant implications for understanding and predicting the behavior of polymer melts under high-rate elongational flow conditions.

Prokaryotic Expression of Rubber Elongation Factor Gene and Preparation of Its Polyclonal Antibody

[Objective] The aim of this study was to prepare the recombination protein of rubber elongation factor and its polyclonal antibodies.[Method] The encoding gene of rubber elongation factor(REF)was amplified by RT-PCR,and cloned into the prokaryotic expression vector pDEST17 to transform into Escherichia coil BI2I-AI.The recombinant protein induced by L-Arabinose was purified by the affinity chromatography.As the immunogen,the recombination protein was used to immunize mice for preparing polyclonal antibodies,while ELISA and Western blot hybridization were used to detect the titers and specificity.[Result] The purified recombination protein of REF with high expression was used to immunize house mice for preparing polyclonal antibodies with high titer and specificity.The western blot hybridization showed that the antibody could recognize the natural REF from latex.[Conclusion] The recombination protein of REF was successfully obtained and the mouse anti REF antibody with high titer and specificity was prepared,which lays a basis for further studies on biological functions of rubber elongation factor and other membrane proteins in rubber particles.

Microstructures and mechanical properties of semi-solid squeeze casting ZL104 connecting rod

Semi-solid squeeze casting（SSSC） and liquid squeeze casting（LSC） processes were used to fabricate a ZL104 connecting rod, and the influences of the process parameters on the microstructures and mechanical properties were investigated. Results showed that the tensile strength and elongation of the SSSC-fabricated rod were improved by 22% and 17%, respectively, compared with those of the LSC-fabricated rod. For SSSC, the average particle size（APS） and the shape factor（SF） increased with the increase of re-melting temperature（Tr）, whereas the tensile strength and elongation increased first and then decreased. The APS increased with increasing the mold temperature（Tm）, whereas the SF increased initially and then decreased, which caused the tensile strength and elongation to increase initially and then decrease. The APS decreased and the SF increased as squeezing pressure（ps） increased, and the mechanical properties were enhanced. Moreover, the optimal Tr, ps and Tm are 848 K, 100 MPa and 523 K, respectively.

长薄鳅的精巢发育和精子发生

应用组织学和超微结构方法研究了长薄鳅(Leptobotia elongate Bleeker)精巢发育和精子发生。结果显示:长薄鳅精巢一对,其发育过程可划分为6个时期,Ⅰ期性腺肉眼无法分辨雌雄。组织学结构显示长薄鳅的精巢属于小叶型,根据发育过程中细胞的大小、核仁多少、细胞核和细胞质浓缩的程度将精子发生划分为6个时相。超微结构下精原细胞分为初级精原细胞和次级精原细胞,成熟精子分头部、中片和尾部3个部分,尾部有侧鳍,具"9+3"式微管结构。

长薄鳅幼鱼消化道指数和消化酶活性研究

测定了长薄鳅(Leptobotia elongate Bleeker)幼鱼(8.0～110.1 g)的消化道指数和不同体重组(10 g、30 g、50 g)幼鱼的胃、肝胰脏、前肠、中肠、后肠的淀粉酶、胃蛋白酶、胰蛋白酶及脂肪酶活性。结果:(1)长薄鳅幼鱼肝指数平均为(1.400±0.004)%,比肠长平均为(0.418±0.080),体重与体长呈幂函数相关,相关式为:W=0.019L2.818 1(R2=0.948,P<0.01,n=43);鱼体肥满度在30 g组中最高。(2)各部位消化酶活性均以蛋白酶>脂肪酶>淀粉酶;各体重组淀粉酶活性在肝胰脏中最高(P<0.05);蛋白酶活性在胃和中肠中较高;脂肪酶活性沿消化道从前至后升高;(3)各部位淀粉酶活性在各体重组间变化不大,胃蛋白酶、肠段胰蛋白酶和脂肪酶活性随体重增加而下降。本研究认为长薄鳅幼鱼为杂食、偏肉食性,其消化酶活性存在组织特异性,体重30 g左右是其营养需求转变或者生长发育的重要时期。

长薄鳅的卵巢发育和卵子发生

采用组织学、组织化学、电镜等方法研究了长薄鳅(Leptobotia elongate)的卵巢发育和卵子发生。结果表明:长薄鳅卵巢1个,根据形态、色泽、成熟系数等将发育过程分为5个时期,成熟系数最大达20.22%。第Ⅰ时相,卵原细胞位于生殖上皮内,成团分布,核质比大,核膜双层,清晰,核位于细胞中央。第Ⅱ时相,产卵板、卵黄核和滤泡细胞出现。第Ⅲ时相,卵子体积增加明显,卵黄泡出现,卵黄开始沉积,滤泡细胞2层。第Ⅳ时相,卵黄颗粒充满卵母细胞,核膜破裂,细胞核向动物极发生偏移,滤泡层分为3层。第Ⅴ时相,卵母细胞体积达最大,卵黄颗粒聚集成卵黄小板,核膜完全破裂,核向动物极移动。组织化学染色显示,随着卵母细胞的发育,糖类、蛋白质、脂肪等物质不断增加,卵子成熟时达到积累的顶点,而DNA、RNA由明显到不明显。电镜观察显示线粒体等多种细胞器参与了卵黄的合成;线粒体形态多样,在卵黄的形成过程中,起到了主要作用;卵黄小板有4种类型。

A Preliminary Study on Pollination Biology of an Endangered Orchid, Changnienia amoena, in Shennongjia

Changnienia amoena Chien is a monotypic species and endemic to China, and was listed on the Chinese Red Book in 1992. The species was once abundant but has become rare and endangered in recent years because of the habitat fragmentation and unduly commercial collections. Previous observation showed that this species has very low and even no fruit set, and the pollinators are not observed before this report. The present observation was conducted at the Shennongjia, Hubei Province during the spring of 2002. The results showed that Bombus (Diversobombus) trifasciatus Smith, B. imitator Pittion and one species of Apis visited the flowers of the orchid, but only B. tritasciatus could carry pollinaria on its body and was the legitimate pollinators of C amoena. During 113 h of observation, only nine visitations were recorded. The bumblebees mainly appeared during 12:00-15:00 during the day. Bumblebees stayed in a flower only a few seconds and never more than ten seconds. The flowers would persist in fresh for about three weeks when they were not pollinated, but 3 or 4 d after pollinated, the pollinated flowers underwent a series of color and morphological changes including stalk elongation and ovary swelling. Therefore, stalk elongation can be considered an index of fruits set. Artificial pollination indicated that C amoena is a highly self-compatible and outcrossing species, but dependent on pollinators for fruit set. Based on the field observations, we concluded that pollination system of C amoena is deceptive. The fruit set in nature is not very low (26.98% on average) compared to other deceptive orchids, which may be related to small population sizes. The number of pollinia removal is much higher than that of fruit set, indicating that there are some degrees of pollinia wasting in C amoena.

人Elongator复合物Elp4亚基基因可部分补偿酵母ELP4缺失菌株的生长缺陷

为研究人Elongator复合物Elp4亚基的功能 ,将人ELP4基因转入酵母ELP4基因缺失的突变菌株 (elp4△菌株 )中 ,并对转化菌株进行功能互补实验和SSA3和PHO5基因表达分析 ,结果表明人的ELP4基因不能恢复突变菌株对高盐的敏感性 ,但可以在一定程度上缓解突变菌株对高温、咖啡因 (Caffeine)和 6 氮尿嘧啶 (6 AU)的敏感性 ,部分恢复低磷条件下PHO5基因表达延迟的缺陷 ,并可在热激条件下提高SSA3基因的表达 ,因此人的ELP4基因可以部分补偿酵母ELP4基因缺失所引起的生长缺陷 ,提示人的Elp4亚基可能与酵母的该亚基功能相似。

Formation mechanism and organizational controlling of ultra-fine-grain copper processed by asymmetrical accumulative rolling-bond and annealing

The initial copper with large grain sizes of 60-100 μm was processed by six passes asymmetrical accumulative rolling-bond （AARB） and annealing, the ultra-fine-grained （UFG） copper with grain size of 200 nm was obtained, and the microstructures and properties were studied. The results show that there are large sub-structures and also texture component C for the UFG copper obtained by six passes AARB, possessing high strength and microhardness in company with poor elongation and conductivity. Thereafter, the UFG copper was annealed at 220 °C for 35 min, in which the sub-structures disappear, the grain boundaries are composed of big angle grain boundaries, and the textures are composed of a variety of texture components and parts of twins. Compared with the UFG copper obtained by six passes AARB, the tensile strength and yield strength for the UFG copper obtained by six passes AARB and annealing at 220 °C for 35 min are decreased slightly, the elongation and conductivity are improved obviously.

栽培稻与高州普通野生稻耐铝性的比较研究

【目的】研究栽培稻品种耐铝性及高州普通野生稻耐铝性的特点,明确供试品种中的耐铝品种和铝敏感品种,以及野生稻中的耐铝材料,为定位来自高州普通野生稻的耐铝基因奠定材料基础。【方法】以Al3+浓度为25、50和100μmol·L-1的简单钙溶液处理1d后的苗期种子根或野生稻离蘖茎新生根相对根伸长量(relative root elongation,RRE)的大小评价材料的绝对耐铝性,以各材料的RRE与耐铝性对照品种日本晴的RRE之比作为相对根伸长比衡量材料的相对耐铝性。【结果】供试品种间、不同Al3+浓度、不同处理时间对水稻种子根相对根伸长量RRE的影响均存在显著差异(P<0.0001);综合来看,日本晴、L202、辽粳944和88B等为耐铝品种;以Al3+浓度为50μmol·L-1的简单钙溶液处理1d后的RRE为指标衡量不同基因型材料的耐铝性是可靠的。广东高州普通野生稻种子根在Al3+浓度为50μmol·L-1简单钙溶液处理1d后RRE值表明,材料之间的耐铝性存在极显著差异(P<0.0001)。有55个编号材料的RRE≥0.50,为耐铝性材料。与栽培稻耐铝对照品种日本晴相比较,以50μmol·L-1Al3+浓度的简单钙溶液处理1d后RRE值大于日本晴(RRE=0.6198)的供试野生稻有37个编号(GZW020的RRE最大,为1.8730)。对高州普通野生稻离蘖茎新生根以Al3+浓度为50μmol·L-1溶液处理1d后RRE的比较,发现RRE≥0.50的耐铝性材料有13个。相关性分析表明,相同编号的野生稻其种子根RRE和离蘖茎新生根的RRE之间具有极显著的相关性(R=0.76012,P=0.0041)。认为高州普通野生稻材料蕴藏有耐铝的基因,随后在以栽培稻铝敏感品种华粳籼74为受体、耐铝野生稻GZW087为供体的BC3F2世代19个株系的耐铝性检测中发现2个株系具有耐铝性,表明来自野生稻亲本的耐铝性传递到了回交后代。【结论】水稻品种间耐铝性存在显著差异,广东高州普通野生稻有丰富的耐铝特性,这为定位其耐铝基因及创新水稻耐铝资源奠定了重要的材料基础。

Morphology development of elongated α phases in hot working of large-scale titanium alloy plate

The role of subtransus hot working on microstructure morphology of TA15 titanium alloy plate with elongatedαphases was studied by quantitative metallography on different sections. The results show that the microstructure morphology is mainly affected by loading direction. When the sample is compressed along normal direction, microstructure on the section vertical to normal direction has equiaxed primaryαphase but microstructure on the section vertical to rolling direction has strip primaryαphase with long axis along tangential direction. When the sample is compressed along rolling direction, microstructure on the section vertical to normal direction has strip primaryαphase elongated along tangential direction but microstructure on the section vertical to rolling direction consists of strip and irregular broad-band primaryαphase. The strip primaryαphase aspect ratio is smaller at lower temperature due to the dynamic break-down ofαphase. The difference on primaryαphase aspect ratio between different sections decreases after compression along distinct directions in two loading passes, suggesting the improvement of equiaxity of primaryαphase.

Modification on epoxy-based adhesive

This research adopted four methods to toughen epoxy adhesives. They were liquid hydroxyl group terminated polybutadiene (HTPB) rubber modification, silicon rubber modification, polyacrylate multiplicity elastomer particulates emulsion modification and chemical grafting modification. After modification, the shearing strength and the rupture elongation were tested. The interface and the chemical reaction between the modifiers and the epoxy were analyzed by scanning electron microscope (SEM) and infrared optical spectrum. The results show that the elastomer particulates modification and the chemical grafting modification can reach the better toughening effects.