不同环境下水稻谷粒重发育的杂种优势和遗传相关性分析

选用9个不同类型的水稻品种(系),按双列杂交设计(6×5)配成两套亲本和F12个世代的遗传材料,采用数量性状的加性、显性遗传模型、发育遗传模型比较分析了水稻谷粒重发育的杂种优势和遗传相关性。结果表明,早季在谷粒充实前期(1～12d)群体平均优势较小,中后期(13～28d)正向优势趋于明显,在谷粒充实的全过程均表现较小的负向群体超亲优势;晚季则在谷粒充实前中期(1～18d)表现正向群体平均优势。后期(19～28d)优势不明显,在谷粒充实前期(1～12d)表现正向群体超亲优势,之后转为明显的负向群体超亲优势,表明晚季谷粒发育的杂种优势表现较之早季更有利于提高籽粒充实质量,不同发育时期谷粒重之间以及与最终谷粒重之间的遗传相关分析表明,早季以显性相关为主,晚季以加性相关为主,随着发育进程的推进,相关趋于密切。     

Genetic Determinants of Symptoms on Viral DNA Satellites

Begomovirus-DNA-β disease complexes induce different symptom phenotypes in their hosts. To investigate the genetic determinants of the phenotypic differences, Nicotiana spp. and tomato plants were inoculated with infectious clones of Tobacco curly shoot virus (TbCSV)/TbCSV DNA-β (TbCSB) and Tomato yellow leaf curl China virus (TYLCCNV)/TYLCCNV DNA-β (TYLCCNB) pseudorecombinants and showed that TYLCCNB induced characteristic vein-thickening and enation symptoms, while TbCSB only slightly exacerbated the leaf-curling symptoms, regardless of the helper virus being used. The roles of DNA-β-encoded βC1 and a 430-nucleotide fragment containing the A-rich region and the putative βC1 promoter region of the βC1 gene (referred to as AP) in symptom development were further investigated by constructing hybrid satellites in which the βC1 coding region or AP was exchanged between the two satellite molecules. A TYLCCNB hybrid with TbCSB βC1 lost the ability to elicit the vein-thickening and enation phenotypes. TbCSB hybrids containing the TYLCCNB βC1 or AP fragment failed to induce the characteristic vein thickening and enations. A TYLCCNB hybrid having the TbCSB AP fragment produced the enations, but the number of enations was less and their sizes were reduced. Differently from the phloem-specific pattern of the TYLCCNB promoter, a full-length fragment upstream of the TbCSB βC1 gene confers a constitutive β-glucuronidase expression pattern in transgenic tobacco plants. The above results indicate that the DNA-β-encoded βC1 protein is the symptom determinant, but the promoter of the βC1 gene has influence on symptom production.Geminiviruses are small plant viruses with circular single-stranded DNA (ssDNA) genomes that are encapsidated in unique twinned (geminate) particles. Members of the genus Begomovirus are transmitted by whiteflies (Bemisia tabaci) and infect dicotyledonous plants (42). Begomoviruses have either one or two circular ssDNA genomic components (DNA-A and DNA-B). The DNA-A component is capable of autonomous replication and encapsidation, whereas the DNA-B component encodes two proteins (BC1 and BV1) involved in movement (14). Recently, some monopartite begomoviruses have been found in association with a novel satellite DNA molecule, referred to as DNA-β and now known as a betasatellite (2, 5, 20, 22, 38, 45). DNA-β is approximately half the size of the viral genomic DNA, and apart from a nonanucleotide sequence (TAATATTAC), it has little sequence identity with viral genomic DNA. DNA-β depends on the helper virus for replication and encapsidation and, in turn, is required for the induction of bona fide disease symptoms. DNA-β bears a βC1 open reading frame (ORF) on the complementary-sense strand, which is conserved among distinct betasatellites in terms of position and size. Mutational analyses and constitutive expression have shown that βC1 is a strong pathogenicity/symptom determinant (7, 34, 39).Begomovirus-DNA-β disease complexes are associated with a wide range of plant species and induce different sets of symptom phenotypes in their natural hosts (25). However, the contributions of the helper virus and the satellite molecule to symptom development are not clear. Tomato yellow leaf curl China virus (TYLCCNV) and Tobacco curly shoot virus (TbCSV) are monopartite begomoviruses associated with DNA-β, but they differ in the symptom phenotypes induced in Nicotiana spp. and Solanum lycopersicum (7, 22). In the present work, we report that the symptom differences between TYLCCNV/TYLCCNV DNA-β (TYLCCNB) and TbCSV/TbCSV DNA-β (TbCSB) are determined by DNA-β and the DNA-β-encoded βC1 protein is the symptom determinant, but the promoter of the βC1 gene has influence on symptom production.     

PR55��, a Regulatory Subunit of PP2A, Specifically Regulates PP2A-mediated ��-Catenin Dephosphorylation

A central question in Wnt signaling is the regulation of β-catenin phosphorylation and degradation. Multiple kinases, including CKIα and GSK3, are involved in β-catenin phosphorylation. Protein phosphatases such as PP2A and PP1 have been implicated in the regulation of β-catenin. However, which phosphatase dephosphorylates β-catenin in vivo and how the specificity of β-catenin dephosphorylation is regulated are not clear. In this study, we show that PP2A regulates β-catenin phosphorylation and degradation in vivo. We demonstrate that PP2A is required for Wnt/β-catenin signaling in Drosophila. Moreover, we have identified PR55α as the regulatory subunit of PP2A that controls β-catenin phosphorylation and degradation. PR55α, but not the catalytic subunit, PP2Ac, directly interacts with β-catenin. RNA interference knockdown of PR55α elevates β-catenin phosphorylation and decreases Wnt signaling, whereas overexpressing PR55α enhances Wnt signaling. Taken together, our results suggest that PR55α specifically regulates PP2A-mediated β-catenin dephosphorylation and plays an essential role in Wnt signaling.Wnt/β-catenin signaling plays essential roles in development and tumorigenesis (1–3). Our previous work found that β-catenin is sequentially phosphorylated by CKIα⁴ and GSK3 (4), which creates a binding site for β-Trcp (5), leading to degradation via the ubiquitination/proteasome machinery (3). Mutations in β-catenin or APC genes that prevent β-catenin phosphorylation or ubiquitination/degradation lead ultimately to cancer (1, 2).In addition to the involvement of kinases, protein phosphatases, such as PP1, PP2A, and PP2C, are also implicated in Wnt/β-catenin regulation. PP2C and PP1 may regulate dephosphorylation of Axin and play positive roles in Wnt signaling (6, 7). PP2A is a multisubunit enzyme (8–10); it has been reported to play either positive or negative roles in Wnt signaling likely by targeting different components (11–21). Toward the goal of understanding the mechanism of β-catenin phosphorylation, we carried out siRNA screening targeting several major phosphatases, in which we found that PP2A dephosphorylates β-catenin. This is consistent with a recent study where PP2A is shown to dephosphorylate β-catenin in a cell-free system (18).PP2A consists of a catalytic subunit (PP2Ac), a structure subunit (PR65/A), and variable regulatory B subunits (PR/B, PR/B′, PR/B″, or PR/B‴). The substrate specificity of PP2A is thought to be determined by its B subunit (9). By siRNA screening, we further identified that PR55α, a regulatory subunit of PP2A, specifically regulates β-catenin phosphorylation and degradation. Mechanistically, we found that PR55α directly interacts with β-catenin and regulates PP2A-mediated β-catenin dephosphorylation in Wnt signaling.     

小鼠原核期受精卵体外培养系统的筛选

为了筛选出最佳的小鼠原核期受精卵的体外发育培养系统,分别进行了四个试验。试验I:在体外分别用自配的M16、mM16、KSOM、mKSOM、CZB进行体外发育培养,进而筛选出一种最佳的体外培养系统;试验Ⅱ、Ⅲ、Ⅳ分别:探讨了血清、PVA、rhLIF对小鼠胚胎发育的影响。结果,试验I中胚胎发育到2-细胞的比率差异不明显,但是在mM16和mKSOM中,发育到4-细胞的比率94.7%,90.7%(91/96;78/86)和发育到桑椹胚/囊胚的比率分别为78.1%,67.4%(75/96;58/86)均明显高于其他三种培养液;试验II用10?S代替M16中BSA时,胚胎的发育率均下降,即使在mM16中桑椹胚/囊胚率仅为4.8%(12/35)与对照组M16(40.5%)差异显著(p<0.05);试验Ⅲ用PVA取代mM16和mKSOM中的BSA其体外发育率显著下降,胚胎均无一例发育到桑椹胚/囊胚;试验Ⅳ:rhLIF能提高胚胎在体外的发育率可使mM16培养的胚胎囊胚率、囊胚脱出率分别达到84%(47/56)、39.2%(22/56)。结论:在不添减其他成分前提下,只在M16中添加0.1mMolEDTA、0.5mMol牛磺酸、1000IU/mlrhLIF便可获得84%的囊胚率,同时证明在M16或mM16添加血清都会降低其体外发育率;PVA还不能有效的取代mM16、mKSOM中的血清。     

HDAC8 drives spindle organization during meiotic maturation of porcine oocytes

ObjectivesHistone deacetylase 8 (HDAC8) is one of the class I HDAC family proteins, which participates in the neuronal disorders, parasitic/viral infections, tumorigenesis and many other biological processes. However, its potential function during female germ cell development has not yet been fully understood.Materials and methodsHDAC8‐targeting siRNA was microinjected into GV oocytes to deplete HDAC8. PCI‐34051 was used to inhibit the enzyme activity of HDAC8. Immunostaining, immunoblotting and fluorescence intensity quantification were applied to assess the effects of HDAC8 depletion or inhibition on the oocyte meiotic maturation, spindle/chromosome structure, γ‐tubulin dynamics and acetylation level of α‐tubulin.ResultsWe observed that HDAC8 was localized in the nucleus at GV stage and then translocated to the spindle apparatus from GVBD to M II stages in porcine oocytes. Depletion of HDAC8 led to the oocyte meiotic failure by showing the reduced polar body extrusion rate. In addition, depletion of HDAC8 resulted in aberrant spindle morphologies and misaligned chromosomes due to the defective recruitment of γ‐tubulin to the spindle poles. Notably, these meiotic defects were photocopied by inhibition of HDAC8 activity using its specific inhibitor PCI‐34051. However, inhibition of HDAC8 did not affect microtubule stability as assessed by the acetylation level of α‐tubulin.ConclusionsCollectively, our findings demonstrate that HDAC8 acts as a regulator of spindle assembly during porcine oocyte meiotic maturation.     

伊犁贝母药用资源研究现状与开发前景

伊犁贝母的主要药用部位是鳞茎,具有清热化痰、润肺止咳的功效,野生伊犁贝母资源曾被滥采滥挖,导致其药用资源短缺,新疆多地开展了人工伊犁贝母培育工作,但仍有许多不尽人意之处。本文就伊犁贝母鳞茎中以西贝素为主要代表的生物碱的化学成分、药理活性、临床作用、栽培工艺、开发应用现状及前景等方面进行全面的综述,为伊犁贝母药用资源的进一步深入研究和开发提供有益的参考和对策。     

我国南方红壤区氮磷湿沉降对森林流域氮磷输出及水质的影响

持续高通量的氮、磷输入导致水体富营养化的问题已引起广泛关注。通过对江西省千烟洲香溪流域水样(常规水样,降雨后的地表径流以及雨水水样)的季节性监测,研究大气氮、磷湿沉降对森林流域氮、磷输出动态及水质的影响。结果表明:从2013年6月至2014年5月,香溪流域内氮、磷湿沉降通量分别为11.86 kg/hm~2和0.38 kg/hm~2,其中氮湿沉降主要集中在夏秋两季,占全年输入量的64%,而磷沉降主要集中在夏季,占全年输入量的43%,表现出明显的季节性差异;水体p H值(6.22—8.89)的变化范围较大,而且氮、磷的输出受土地管理(施肥方式)及降雨事件的影响较为明显,尤其在耕作期,总氮的输出量占全年氮输出总量的96.2%,而总磷的输出量占全年磷输出总量的61.4%;对4场不同强度降雨(按降雨强度从大到小)的氮、磷输出动态过程分析,发现不同强度的降雨对水体氮、磷的输出过程影响不同,在径流未形成前以及降雨强度达到暴雨级别时,降雨对流域水体氮、磷的稀释作用明显,而在大雨强度下水体磷的输出量明显高于其他降雨;研究期间,香溪流域内氮湿沉降对水体的贡献量为101.97 kg,磷湿沉降的贡献量为0.60 kg,4场降雨氮对流域水体的贡献量为4.46kg,占流域氮输出负荷的15.22%,磷对水体的贡献量为0.032kg,占流域磷输出负荷的0.85%。同时,根据营养状态指数(EI),发现流域水体全年处于中至富营养状态,而且研究期间水体氮、磷浓度均超过水体富营养化阈值(氮1.5 mg/L,磷0.15 mg/L),存在爆发水体富营养化的威胁。