Parametric Study and Design of the Ultimate Strength of Tube gusset Plate Connections

The tube gusset plate connections are widely used in electric transmission towers. However, there is little technical information regarding the behavior of tube gusset plate connections. Thus, a analytical parametric study was conducted to investigate the behavior of tube gusset plate connections. The analytical results were compared with the existing experimental results. It was found that the finite element analysis results were in good agreement with the experimental results. In the parametric study, the effects of geometry, chord load and stiffener on the ultimate strength were considered. Based on the analytical results, a design method for predicting the ultimate strength of tube gusset connections was proposed, and its applicability was verified.     

油棕不同叶序的叶片长宽及其含水量变化规律研究

对成龄油棕不同叶序的叶片长、宽以及含水量进行了测定,探讨叶序与这三个因素之间是否存在一定的规律性。根据油棕叶片在树冠轮生的规律来对不同成熟度的叶片进行排序并取样测定。结果表明成龄油棕树种8～26叶长度呈现较为一致的变化规律,而小叶宽则呈无规则变化,各油棕树第16叶的小叶长最为接近,且各油棕树第18叶的小叶宽最为接近。叶长与宽比值无规律,变化范围17.6～33.5;油棕不同叶序的叶片含水量呈现比较一致的变化趋势,均以16和18叶含水量最高,可达59.4%～64.6%,而且嫩叶总体比老叶含水量高。     

Genetic variation of seedling traits responded to brassinosteroid and gibberellin inhibitors in maize (Zea mays) doubled haploid lines

The purpose of this study was to examine the genotypic variation in maize doubled haploid (DH) lines response to brassinosteroid and gibberellin inhibitors. Plant responses to hormone inhibitors were determined in growth chamber experiments using germination paper for three different seedling treatments: application of propiconazole (Pcz), uniconazole (Ucz) or water (control). Mesocotyl length (ML) was more sensitive to hormone inhibitors, especially to the Ucz treatment, than other seedling traits. ML was significantly correlated with other traits in the Ucz treatment. All the seedling traits showed moderate-to-high broad sense heritability values, ranging from 0.39 to 0.82. The Euclidian genetic distances of inbred line pairs ranged from 1.27 to 19.94, indicating there was a high level of variability across the maize DH lines used in this study. DH lines with extreme MLs were identified, which can provide valuable breeding resources for improving abiotic stress tolerance, and for further genetic studies.     

小麦T型细胞质雄性不育保持系线粒体DNA片段转化不育系的初步研究

细胞质雄性不育在植物界普遍存在,其不育机理一直是人们研究的热点。采用花粉管通道法,利用T型细胞质雄性不育保持系75-3369B线粒体的基因文库,选取其中所载外源片段较大的重组子转化T型不育系小麦75-3369A,结果重组子ME252和ME317的转化后代变成可育,表明线粒体的部分片段可以使细胞质雄性不育系的育性发生转变。     

利用F2和F3群体定位水稻粒形和千粒重QTL

水稻籽粒的粒长、粒宽和粒厚共同塑成了水稻粒形,并决定水稻籽粒的千粒重及外观品质,而千粒重是决定水稻产量三要素之一。本研究以籼型温敏核不育系广占63-4S为母本,以大粒籼稻TGMS29为父本杂交衍生的F2和F3群体,对影响水稻籽粒粒形和千粒重的数量性状位点(quantitative trait loci, QTL)进行定位。2014年和2015年检测到影响籽粒粒长的QTL 5个,粒宽QTL 8个,粒厚的QTL 4个,千粒重QTL 4个。其中,两年重复检测到2个粒长QTL,分别位于第1染色体RM1和RM490之间,可解释的表型变异为21.3%、22%,和第2染色体RM240和RM208之间,可解释的表型变异为12.8%、15.7%。两年均被检测到的粒宽QTL位于第3染色体RM251和RM571之间,可解释表型变异分别为53.60%、55.00%。两年均被检测到的千粒重QTL位于第1染色体RM220和RM1之间,可解释表型变异分别为15.1%、15.4%。这些QTLs的鉴定为稻米粒形和千粒重的遗传研究提供了帮助,也为稻米品质和产量的改良提供了宝贵的基因资源。     

酶解油菜蜂花粉抑制超氧阴离子自由基的研究

【研究目的】探讨油菜蜂花粉中水溶性有效组分的抗氧化能力及其在黄嘌呤氧化酶体系中抑制O2-.的机理。【方法】采用酶解技术和膜分离技术提取分离油菜蜂花粉中水溶性抗氧化有效组分,用黄嘌呤氧化酶体系测定酶解物的不同相对分子质量级分淬灭超氧阴离子自由基(O2-.)的能力。【结果】实验结果表明,经酶解和超滤后得到的相对分子质量大于1000的组分抑制O2-.的效果非常显著【结论】酶解和膜分离技术是提高花粉抗氧化功效成分含量的有效途径。     

Incidence and molecular markers of 2n pollen in Populus tomentosa Carr.

Microscopic examination, amplified fragment length polymorphism (AFLP) and SCAR (sequence-characterized amplified region) molecular markers were employed to determine the incidence of 2n pollen (unreduced pollen) in Chinese white poplar (Populus tomentosa Carr.) and to identify related molecular markers. The presence of a parallel and tripolar spindle at metaphase II and the absence of cytokinesis at telophase II were found to be determining factors in 2n pollen formation. A group of 298 clones that originated from their indigenous areas were investigated for the production of 2n pollen based on pollen size differences, both within a clone and between n and 2n pollen. Pollen grains were collected from 224 of the clones, six of which were subsequently determined to produce only normal pollen; the remainder produced 2n pollen at different frequencies (0.6–21.9%). The frequency at which 2n pollen was produced was significantly and highly significantly different among and within indigenous populations, respectively. Clones produced by the six normal and twenty-two 2n pollen clones were selected for AFLP analysis. Following an initial screening with 55 primer combinations, the E50-M38 (CAT/ACT) primer was identified: it generated a PCR fragment (246 bp) from the normal clones, but not from the 2n pollen producers. In addition, the E31-M50 (AAA/CAT)-amplified DNA fragment (204 bp) was present in 2n pollen producers, and absent in normal clones. These two discriminating AFLP markers were developed into easily detectable SCAR (sequence characterized amplified region) markers which can be used in combination with previously developed AFLP markers to distinguish between normal and 2n pollen clones.     

Meiosis and fertility in interspecific hybrids of Nicotiana tabacum L. ×N. glauca Grah. and their derivatives

Nicotiana glauca is of potential interest to breeders as it carries resistance to black root rot of tobacco. Cytological investigations of sexual interspecific hybrids of N. tabacum T′T′TT (2n = 4x = 48) cv. ‘Wiślica’ × N. glauca GG (2n = 2x = 24) were carried out. The analyses of chromosome association at diakinesis and metaphase I in the PMCs of amphihaploid F₁ T′TG (2n = 3x = 36) revealed low variable pairing with 0–5 bivalents. The sterile amphihaploids F₁ were converted into partial female fertile amphidiploids T′T′TTGG by chromosome doubling. Among 36 mature plants obtained, 15 were found to have chromosome numbers (2n = 6x = 72) and were verified as amphidiploids, 9 had (2n = 6x = 70 or 71) chromosomes while the remaining 12 were haploid. True amphidiploids, in spite of quite high chromosome pairing during meiosis, were very different in pollen fertility, ranging from 0% to 85%. Male fertility disturbances did not correlate with the degree of female fertility upon pollination with N. tabacum. Sesquidiploids T′TG (2n = 5x = 60) obtained from backcrossing the amphidiploids to parental tobacco showed more than 22 bivalents, 10–12 univalents and occasional multivalents that indicated the possibility of interchange events between N. tabacum and N. glauca genomes.     

Molecular marker analysis of genetic variation characterizing a grasspea (Lathyrus sativus) collection from central Italy

Levels of genetic similarity characterizing 20 grasspea (Lathyrus sativus L.) populations collected in central Italy (17 populations in the Marche region and three populations in the Abruzzo region) were analysed with amplified fragment length polymorphism (AFLP) molecular markers. Two main clusters were found: one included large‐seeded populations from farms that were not market‐oriented (named Household populations) and the second, small‐seeded populations, cultivated in market‐oriented farms (named Commercial populations). Relationships among populations collected in different regions were found, although one population of the Abruzzo region was placed between the two main clusters, suggesting a possible further genetic differentiation within this grasspea germplasm collection. Principal component analysis based on AFLP marker frequency was effective in identifying polymorphic markers showing high discriminating ability between clusters H and C. In particular, seven markers showing high positive and three markers with low negative PC1 scores showed an almost cluster‐specific distribution. These results will be useful for enhancing Italian grasspea germplasm use in plant‐breeding programmes and for extending grasspea cultivation within the sustainable agricultural systems of central Italy.     

乙烯受体ETR1基因同源性分析及乙烯敏感性与植物采后寿命的关系

将37种不同科属植物及5个不同月季品种的ETR1核苷酸、氨基酸序列进行同源性分析并构建了分子系统发生树,并对植物的呼吸跃变类型、乙烯敏感性及采后寿命的关系进行了归纳和分析.结果表明,在核苷酸水平上,分子性状的同源性与形态性状同源性具有一致性,但月季不同品种种间差异大于异源植物的属间差异.氨基酸序列的同源性分析结果与核苷酸相似,但仍存在差异,可能由于氨基酸密码子简并性、翻译起始位置的不同、ETR1片段大小的差异所造成.在蛋白质水平上,所分析的ETR1片段均具有高度保守结构域.植物的呼吸跃变类型虽与内源乙烯的生成有密切的关系,但与外源乙烯的敏感性无直接关系;植物对外源乙烯的敏感性与植物采后寿命的关系更为密切.