An increasing number of microRNAs （miRNAs） have been shown to play crucial regulatory roles in the process of plant development. Here, we used high-throughput sequencing combined with computational analysis to chara...An increasing number of microRNAs （miRNAs） have been shown to play crucial regulatory roles in the process of plant development. Here, we used high-throughput sequencing combined with computational analysis to characterize miRNAomes from the ovules of wild-type upland cotton and a fiberless mutant during fiber initiation. Comparative miR- NAome analysis combined with northern blotting and RACE-PCR revealed seven fiber initiation-related miRNAs expressed in cotton ovules and experimentally validated targets of these miRNAs are involved in different cellular responses and metabolic processes, including transcriptional regulation, auxin and gibberellin signal transduction, actin bundles, and lignin biosynthesis. This paper describes a complex regulatory network consisting of these miRNAs expressed in cotton ovules to coordinate fiber initiation responses. In addition, 36 novel miRNAs and two conserved miRNAs were newly iden- tified, nearly doubling the number of known cotton miRNA families to a total of 78. Furthermore, a chromatin remodeling complex subunit and a pre-mRNA splicing factor are shown for the first time to be miRNA targets. To our knowledge, this study is the first systematic investigation of fiber initiation-related miRNAs and their targets in the developing cotton ovule, deepening our understanding of the important regulatory functions of miRNAs in cotton fiber initiation.展开更多
As a new source of natural fibers,the Bombax ceiba tree can provide thin,light,extremely soft and warm fiber material for the textile industry.Natural fibers are an ideal model system for studying cell growth and diff...As a new source of natural fibers,the Bombax ceiba tree can provide thin,light,extremely soft and warm fiber material for the textile industry.Natural fibers are an ideal model system for studying cell growth and differentiation,but the molecular mechanisms that regulate fiber initiation are not fully understood.In B.ceiba,we found that fiber cells differentiate from the epidermis of the inner ovary wall.Each initiated cell then divides into a cluster of fiber cells that eventually develop into mature fibers,a process very different from the classical fiber initiation process of cotton.We used high-throughput single-cell RNA sequencing(scRNA-seq)to examine the special characteristics of fiber initiation in B.ceiba.A total of 15567 high-quality cells were identified from the inner wall of the B.ceiba ovary,and 347 potential marker genes for fiber initiation cell types were identified.Two major cell types,initiated fiber cells and epidermal cells,were identified and verified by RNA in situ hybridization.A developmental trajectory analysis was used to reconstruct the process of fiber cell differentiation in B.ceiba.Comparative analysis of scRNAseq data from B.ceiba and cotton(Gossypium hirsutum)confirmed that the additional cell division process in B.ceiba is a novel species-specific mechanismfor fiber cell development.Candidate genes and key regulators that may contribute to fiber cell differentiation and division in B.ceiba were identified.This work reveals gene expression signatures during B.ceiba fiber initiation at a single-cell resolution,providing a new strategy and viewpoint for investigation of natural fiber cell differentiation and development.展开更多
Background:Fiber,as the main product of cotton,provides main raw material for the textile industry.Many key factors have been revealed a significant role in fiber cell development including Myb proteins,phytohormones,...Background:Fiber,as the main product of cotton,provides main raw material for the textile industry.Many key factors have been revealed a significant role in fiber cell development including Myb proteins,phytohormones,fatty acid metabolites,and epigenetic modifications.DNA methylation is one of the important epigenetic modifications to regulate plant development and responses to abiotic or biotic stimuli.In general,DNA methylation consisting of 5mC and 6mA regulates the chromatin structure and gene transcription to affect plant development,however,the detailed role and underlying mechanism of DNA methylation in the fiber development of cotton are yet vague.Results:Here,systematical study of the 5mC and 6mA DNA methylation profiles during the fiber initiation period of Xu142 and its glabrous mutant Xu142fl represented a clear alteration of global DNA methylation associated with fiber cell initiation.Then,the genome-wide identification of genes responsible for methylation regulation at the fifth carbon of cytosine and the sixth carbon of adenine of DNA was operated in Gossypium hirsutum.As a result,13,10,6,and 17 genes were identified for 5mC methylation,5mC demethylation,6mA methylation,and 6mA demethylation,respectively.We then investigated the tissue expression pattern of all these genes,and some genes showed higher expression levels in fiber initiation,among which some displayed a significant change in transcription between Xu142 and Xu142fl.The possible interaction between histone acetylation and DNA methylation in fiber initiation through in vitro culture was studied by dot blot,and the results showed that repressed histone deacetylation by Trichostatin A(TSA)inhibited the global DNA methylation,and some causal genes(e.g.,GhDMT13,GhDAMT2,GhALKBH12,GhDM7)were also identified.Conclusions:In this study,all the findings indicated the interplay between histone acetylation and DNA methylation,supporting their important roles and providing precious clues for the epigenetic modifications associated with DNA methylatio展开更多
Carbon fiber reinforced polymer(CFRP) and AZ31B Mg alloy were joined by the friction self-piercing riveting(F-SPR) with different steel rivet shank sizes. With the increase of rivet shank size, lap shear fracture load...Carbon fiber reinforced polymer(CFRP) and AZ31B Mg alloy were joined by the friction self-piercing riveting(F-SPR) with different steel rivet shank sizes. With the increase of rivet shank size, lap shear fracture load and mechanical interlock distance increased. Ultrafine grains were formed at the joint in AZ31B as a result of dynamic recrystallization, which contributed to the higher hardness. Fatigue life of the CFRP-AZ31B joint was studied at various peak loads of 0.5, 1, 2, and 3 kN and compared with the resistance spot welded AZ31B-AZ31B from the open literature. The fatigue performance was better at higher peak load(>2 kN) and comparable to that of resistance spot welding of AZ31B to AZ31B at lower peak loads(<1 kN). From fractography, the crack initiation for lower peak load(<1 kN) case was observed at the fretting positions on the top and bottom surfaces of AZ31B sheet. When peak load was increased, fretting between the rivet and the top of AZ31B became more dominant to initiate a crack during fatigue testing.展开更多
基金This work was supported by grants from the State Key Basic Re- search and Development Plan （2010CB126003）, the National Natural Science Foundation of China （90608016）, the Hi-Tech Re- search and Development Program of China （2008AA02Z116）, and the National Transgenic Animals and Plants Research Project （2009ZX08009-069B, 2009ZX08005-026B, and 2008ZX08009- 003）.
文摘An increasing number of microRNAs （miRNAs） have been shown to play crucial regulatory roles in the process of plant development. Here, we used high-throughput sequencing combined with computational analysis to characterize miRNAomes from the ovules of wild-type upland cotton and a fiberless mutant during fiber initiation. Comparative miR- NAome analysis combined with northern blotting and RACE-PCR revealed seven fiber initiation-related miRNAs expressed in cotton ovules and experimentally validated targets of these miRNAs are involved in different cellular responses and metabolic processes, including transcriptional regulation, auxin and gibberellin signal transduction, actin bundles, and lignin biosynthesis. This paper describes a complex regulatory network consisting of these miRNAs expressed in cotton ovules to coordinate fiber initiation responses. In addition, 36 novel miRNAs and two conserved miRNAs were newly iden- tified, nearly doubling the number of known cotton miRNA families to a total of 78. Furthermore, a chromatin remodeling complex subunit and a pre-mRNA splicing factor are shown for the first time to be miRNA targets. To our knowledge, this study is the first systematic investigation of fiber initiation-related miRNAs and their targets in the developing cotton ovule, deepening our understanding of the important regulatory functions of miRNAs in cotton fiber initiation.
基金supported by the National Natural Science Foundation of China(31960437).
文摘As a new source of natural fibers,the Bombax ceiba tree can provide thin,light,extremely soft and warm fiber material for the textile industry.Natural fibers are an ideal model system for studying cell growth and differentiation,but the molecular mechanisms that regulate fiber initiation are not fully understood.In B.ceiba,we found that fiber cells differentiate from the epidermis of the inner ovary wall.Each initiated cell then divides into a cluster of fiber cells that eventually develop into mature fibers,a process very different from the classical fiber initiation process of cotton.We used high-throughput single-cell RNA sequencing(scRNA-seq)to examine the special characteristics of fiber initiation in B.ceiba.A total of 15567 high-quality cells were identified from the inner wall of the B.ceiba ovary,and 347 potential marker genes for fiber initiation cell types were identified.Two major cell types,initiated fiber cells and epidermal cells,were identified and verified by RNA in situ hybridization.A developmental trajectory analysis was used to reconstruct the process of fiber cell differentiation in B.ceiba.Comparative analysis of scRNAseq data from B.ceiba and cotton(Gossypium hirsutum)confirmed that the additional cell division process in B.ceiba is a novel species-specific mechanismfor fiber cell development.Candidate genes and key regulators that may contribute to fiber cell differentiation and division in B.ceiba were identified.This work reveals gene expression signatures during B.ceiba fiber initiation at a single-cell resolution,providing a new strategy and viewpoint for investigation of natural fiber cell differentiation and development.
基金supported financially by National Natural Science Foundation of China(32072022 and 31690093)the Creative Research Groups of China(31621005)Central Public-interest Scientific Institution Basal Research Fund(1610162020010202)for scientific research into non-profit industries。
文摘Background:Fiber,as the main product of cotton,provides main raw material for the textile industry.Many key factors have been revealed a significant role in fiber cell development including Myb proteins,phytohormones,fatty acid metabolites,and epigenetic modifications.DNA methylation is one of the important epigenetic modifications to regulate plant development and responses to abiotic or biotic stimuli.In general,DNA methylation consisting of 5mC and 6mA regulates the chromatin structure and gene transcription to affect plant development,however,the detailed role and underlying mechanism of DNA methylation in the fiber development of cotton are yet vague.Results:Here,systematical study of the 5mC and 6mA DNA methylation profiles during the fiber initiation period of Xu142 and its glabrous mutant Xu142fl represented a clear alteration of global DNA methylation associated with fiber cell initiation.Then,the genome-wide identification of genes responsible for methylation regulation at the fifth carbon of cytosine and the sixth carbon of adenine of DNA was operated in Gossypium hirsutum.As a result,13,10,6,and 17 genes were identified for 5mC methylation,5mC demethylation,6mA methylation,and 6mA demethylation,respectively.We then investigated the tissue expression pattern of all these genes,and some genes showed higher expression levels in fiber initiation,among which some displayed a significant change in transcription between Xu142 and Xu142fl.The possible interaction between histone acetylation and DNA methylation in fiber initiation through in vitro culture was studied by dot blot,and the results showed that repressed histone deacetylation by Trichostatin A(TSA)inhibited the global DNA methylation,and some causal genes(e.g.,GhDMT13,GhDAMT2,GhALKBH12,GhDM7)were also identified.Conclusions:In this study,all the findings indicated the interplay between histone acetylation and DNA methylation,supporting their important roles and providing precious clues for the epigenetic modifications associated with DNA methylatio
基金financially sponsored by the US Department Energy Vehicle Technologies Office, as part of the Joining Core Program。
文摘Carbon fiber reinforced polymer(CFRP) and AZ31B Mg alloy were joined by the friction self-piercing riveting(F-SPR) with different steel rivet shank sizes. With the increase of rivet shank size, lap shear fracture load and mechanical interlock distance increased. Ultrafine grains were formed at the joint in AZ31B as a result of dynamic recrystallization, which contributed to the higher hardness. Fatigue life of the CFRP-AZ31B joint was studied at various peak loads of 0.5, 1, 2, and 3 kN and compared with the resistance spot welded AZ31B-AZ31B from the open literature. The fatigue performance was better at higher peak load(>2 kN) and comparable to that of resistance spot welding of AZ31B to AZ31B at lower peak loads(<1 kN). From fractography, the crack initiation for lower peak load(<1 kN) case was observed at the fretting positions on the top and bottom surfaces of AZ31B sheet. When peak load was increased, fretting between the rivet and the top of AZ31B became more dominant to initiate a crack during fatigue testing.
