Environmental variables affecting the sexual segregation of great white sharks Carcharodon carcharias at the Neptune Islands South Australia

The seasonal temporal sexual segregation of white sharks Carcharodon carcharias , at the Neptune Islands, South Australia, is described in relation to environmental variables. A significant sexual segregation was found at this site with sex ratios strongly favouring males overall. Males were more prevalent than females in all months in a 3 year sampling period, aside from April and May. There was a significant difference between the sexes in terms of mean daily numbers over the months of the study. It was also observed that sexual segregation fluctuated for unknown reasons on a temporal scale. Predictive models for estimating male and female numbers based on a series of abiotic factors were generated. Sea surface temperature, tidal height, tidal range, moon phase, cloud cover, underwater visibility and swell height were related to daily sightings of male and female white sharks to determine the influence of these variables on sexual segregation. Visibility and sea surface temperature affected male numbers, however, visibility did not affect sexual segregation. Tidal height was significantly different between males and females. Sea surface temperature also appeared to be related to sexual segregation in this species. Females were present when temperatures ranged from 15·7 to 18·1° C whereas males were observed at temperatures ranging from 14·3 to 17·8° C, with a peak in sightings in September, when sea surface temperatures were at their lowest. Since parturition is thought to occur in spring or summer, it is suggested that females are absent at this time and only return during prime feeding periods or times at which temperatures are elevated in order to increase developmental growth rates of their young. The significantly lower temperatures in 2003 may explain the absence of females in this year. Hypotheses related to temperature regulation in this species are put forward to explain the sexual segregation observed.     

桑树磷脂酶MaPLA1-2D亚型4个基因的克隆与胁迫应答分析

磷脂酶(phospholipase)是一类在植物生长发育和胁迫应答中起重要调控作用的磷脂水解酶,也是一类重要的信号转导酶。而磷脂酶A1(PLA1)在植物应答生物胁迫和非生物胁迫中的功能研究鲜见报道。研究从桑树(Morus alba L.)中克隆了磷脂酶PLA1的1个亚型MaPLA1-2D基因,对其进行了序列分析、组织表达、胁迫诱导表达和蛋白亚细胞定位分析。结果表明,桑树PLA1-2D亚型基因包括4个成员,命名为MaPLA1-2D.1~MaPLA1-2D.4。4个基因在桑树根和叶中高水平表达,蛋白亚细胞定位在叶绿体。序列和进化分析表明MaPLA1-2D基因4个成员与拟南芥AtDAD1基因的保守结构域序列具有较高相似度且进化关系紧密。MaPLA1-2D基因4个成员的启动子含有多种胁迫应答顺式元件和激素响应元件;胁迫诱导表达模式分析表明MaPLA1-2D基因表达受干旱和脱落酸处理显著诱导。以上结果说明,MaPLA1-2D基因与拟南芥DAD同源,可能在桑树非生物胁迫应答中发挥重要功能。     

糜子黄、黑种皮遗传及转录组学分析

同源异型域-亮氨酸拉链(homedomain-leucine zipper,HD-Zip)转录因子广泛参与植物的生长发育和抗胁迫过程。该研究通过生物信息学方法对青稞HD-Zip基因家族进行全基因组分析鉴定,并采用qRT-PCR技术分析非生物胁迫下该基因的表达特性,为深入探讨青稞HD-Zip转录因子的生物学功能及其在高原作物抗逆育种中的应用奠定基础。结果表明：(1)成功从青稞基因组中共鉴定出41个HD-Zip基因家族成员,依次命名为i>HvvHD-ZipⅠ-1~Ⅳ-13,且这些基因在7条染色体上呈不均匀分布。(2)理化性质分析发现,HvvHD-Zip蛋白包含197～885个不等的氨基酸残基;分子量范围在19 914.36～94 014.87 Da;亚细胞定位表明HvvHD-Zip蛋白都位于细胞核。(3)根据多序列比对、系统进化、基因结构和保守基序差异将其聚为4个亚家族,各亚家族分类特征与系统聚类结果一致。(4)顺式作用元件预测分析发现,i>HvvHD-Zip基因启动子中含有11种植物激素和胁迫响应元件。(5)qRT-PCR结果显示,HvvHD-Zip Ⅰ、Ⅱ、Ⅳ亚家族基因对各胁迫响应明显;与根组织相比,多数i>HvvHD-Zip基因在叶组织中响应明显(上调或下调);与冷和盐胁迫相比,i>HvvHD-Zip各基因对旱胁迫响应较强。     

葡萄蔗糖转化酶基因家族的生物信息学及响应逆境胁迫分析

蔗糖转化酶(invertase, INV)在植物生长发育和抵御胁迫中发挥着重要作用。研究从葡萄基因组数据库中鉴定出19个蔗糖转化酶基因,对基因结构和编码蛋白质的理化性质进行生物信息学分析,并利用qRT-PCR技术分析基因在不同激素和非生物胁迫条件下的表达特征,为进一步探索葡萄INV基因家族参与葡萄逆境响应提供了一定的理论依据。结果表明,(1)该基因家族编码蛋白的氨基酸长度在150～766 aa之间,理论等电点介于4.43～9.1之间,亚细胞定位预测发现其主要在细胞质中表达,此外液泡和细胞壁也存在部分基因表达;(2)共线性结果显示VvCINV与其他5个物种复制频率较高;(3)保守基序分析表明VvCwINV包含了所有的保守基序,且Glyco＿32和Glyco＿hydro＿100是VvINV基因主要结构域;(4)组织特异性表达分析发现多数基因在葡萄生长发育进程中都有表达;(5)qRT-PCR分析结果显示,VvINV基因家族在叶片中对激素处理和非生物胁迫的响应出现上调,VvCINV1在50 mg/L GA₃和10%PEG处理后上调表达极显著,VvCINV4在盐胁迫、ABA...     

Effect of Soil Temperature and pH on Resistance of Soybean to Heterodera glycines

Soybean cyst nematode (SCN), Heterodera glycines Ichinohe, is a major pest of soybean, Glycine max L. Merr. Soybean cultivars resistant to SCN are commonly grown in nematode-infested fields. The objective of this study was to examine the stability of SCN resistance in soybean genotypes at different soil temperatures and pH levels. Reactions of five SCN-resistant genotypes, Peking, Plant Introduction (PI) 88788, Custer, Bedford, and Forrest, to SCN races 3, 5, and 14 were studied at 20, 26, and 32 C, and at soil pH''s 5.5, 6.5, and 7.5. Soybean cultivar Essex was included as a susceptible check. Temperature, SCN race, soybean genotype, and their interactions significantly affected SCN reproduction. The effect of temperature on reproduction was quadratic with the three races producing significantly greater numbers of cysts at 26 C; however, reproduction on resistant genotypes remained at a low level. Higher numbers of females matured at the soil pH levels of 6.5 and 7.5 than at pH 5.5. Across the ranges of temperature and soil pH studied, resistance to SCN in the soybean genotypes remained stable.     

Drought‐stress and plant resistance affect herbivore performance and proteome: the case of the green peach aphid Myzus persicae (Hemiptera: Aphididae)

Little is known about the simultaneous effects of drought stress and plant resistance on herbivorous insects. By subjecting the green peach aphid Myzus persicae Sulzer to well‐watered and drought‐stressed plants of both susceptible and resistant peach (Prunus persica), the effects of both stressors on aphid performance and proteomics are tested. Overall, the influence of the water treatment on aphid performance is less pronounced than the effect of host plant genetic resistance. On the susceptible cultivar, aphid survival, host acceptance and ability to colonize the plant do not depend on water treatment. On the resistant cultivar, aphid survival and ability to colonize are higher on drought‐stressed than on well‐watered plants. A study examining the pattern of protein expression aiming to explain the variation in aphid performance finds higher protein expression in aphids on the drought‐stressed susceptible cultivars compared with the well‐watered ones. In the susceptible cultivar, the regulated proteins are related to energy metabolism and exoskeleton functionality, whereas, in the resistant cultivar, the proteins are involved with the cytoskeleton. Comparison of the protein expression ratios for resistant versus susceptible plants reveals that four proteins are down‐regulated in well‐watered plants and 15 proteins are down‐regulated in drought‐stressed plants. Drought stress applied to the susceptible cultivar induces the regulation of proteins in M. persicae that enable physiological adaptation to maintain an almost unaltered aphid performance. By contrast, for aphids on the resistant cultivar subjected to drought stress, the down‐regulation of proteins responds to an induced host susceptibility effect.