The curious case of Hermodice carunculata (Annelida: Amphinomidae): evidence for genetic homogeneity throughout the Atlantic Ocean and adjacent basins

Over the last few decades, advances in molecular techniques have led to the detection of strong geographic population structure and cryptic speciation in many benthic marine taxa, even those with long‐lived pelagic larval stages. Polychaete annelids, in particular, generally show a high degree of population divergence, especially in mitochondrial genes. Rarely have molecular studies confirmed the presence of ‘cosmopolitan’ species. The amphinomid polychaete Hermodice carunculata was long considered the sole species within its genus, with a reported distribution throughout the Atlantic and adjacent basins. However, recent studies have indicated morphological differences, primarily in the number of branchial filaments, between the East and West Atlantic populations; these differences were invoked to re‐instate Hermodice nigrolineata, formerly considered a junior synonym of H. carunculata. We utilized sequence data from two mitochondrial (cytochrome c oxidase subunit I, 16S rDNA) markers and one nuclear (internal transcribed spacer) marker to examine the genetic diversity of Hermodice throughout its distribution range in the Atlantic Ocean, including the Mediterranean Sea, the Caribbean Sea, the Gulf of Mexico and the Gulf of Guinea. Our analyses revealed generally low genetic divergences among collecting localities and between the East and West Atlantic, although phylogenetic trees based on mitochondrial data indicate the presence of a private lineage in the Mediterranean Sea. A re‐evaluation of the number of branchial filaments confirmed differences between East and West Atlantic populations; however, the differences were not diagnostic and did not reflect the observed genetic population structure. Rather, we suspect that the number of branchial filaments is a function of oxygen saturation in the environment. Our results do not support the distinction between H. carunculata in the West Atlantic and H. nigrolineata in the East Atlantic. Instead, they re‐affirm the older notion that H. carunculata is a cohesive species with a broad distribution across the Atlantic Ocean.     

遮荫对桂南种植罗汉果净光合速率和品质的影响

通过大田栽培试验,探讨生育后期不同遮荫处理(遮荫率0、30%、50%和70%)对罗汉果净光合速率和罗汉果品质的影响。经过遮荫处理,罗汉果净光合速率日变化曲线由对照组(遮荫率为0)的双峰型转变为单峰型,曲线峰值出现在中午12:00时。遮荫率50%处理的曲线峰值、罗汉果苷Ⅴ含量和干果重比其它遮荫处理和对照组的高。结果表明,在桂南种植的罗汉果,生育后期给予遮荫率50%的处理对增加罗汉果的净光合速率,提高罗汉果苷Ⅴ含量和干果重较为有利。     

生长调节剂调控龙眼冲梢的研究

为高效、安全地调控龙眼冲梢,在龙眼花芽形态分化开始期(露红点期)和花穗主轴长6～9 cm的花穗展叶期,施用生长调节剂,比较了不同方法调控龙眼冲梢的效果。结果发现龙眼花芽形态分化开始期树冠喷施200 mg/kg乙烯利+150 mg/kg多效唑混合液和土施多效唑每株4 g处理控冲梢效果都显著高于对照,冲梢率分别是10.5%和7.6%,在花穗小叶处于展叶期虹吸输300 mg/kg乙烯利防控龙眼冲梢有效且安全。     

不同倍性香石竹杂交受精过程及胚胎发育研究

采用石蜡切片法对以四倍体香石竹品种‘紫蝴蝶’(2n=4x=60)为母本,单瓣中间材料‘NH6’(2n=2x=30)为父本杂交后受精过程及胚胎发育进行研究。结果表明:(1)授粉后17h,花粉管进入助细胞并释放内容物,精核进入极核细胞内,与二极核细胞融合形成初生胚乳核;授粉后1d,精核向卵核方向移动,贴伏于卵核核膜上;授粉后2d,形成合子及游离的胚乳核;随后,胚发育经过原胚、球形胚、心形胚、鱼雷形胚阶段。(2)杂交障碍发生在受精过程及胚胎发育的各个时期,表现为:精子与卵细胞不相融合或精子与二极核不相融合、合子未分裂或初生胚乳核未分裂及胚胎的败育。(3)胚败育虽能发生在原胚、球形胚、棒状形胚、三角形胚、心形胚、鱼雷形胚及子叶形胚阶段,但主要发生在球形胚阶段。     

高等植物种子活力的生物学研究进展

种子活力是种子质量的重要指标和种用价值的重要组成部分。该文从种子活力概念的演变与延伸、种子活力的遗传分析、种子活力测定方法、与种子活力相关的miRNA和蛋白质组学以及引发提高种子活力的机理等方面对高等植物种子活力的最新研究进展进行了综述,并提出了种子活力未来的研究方向。     

采收期对青皮核桃果实生理特性与耐贮性的影响

以‘中林5号’(早熟)、‘辽宁4号’(中熟)、‘西扶1号’(中晚熟)青皮核桃果实为试材,于8月上、中、下旬3个采收期采果,在0~1℃冷藏过程中测定贮期生理指标和保鲜效应。结果显示:(1)各采收期和各品种果实呼吸强度(RI)均呈双峰型变化;8月中旬采收的果实呼吸峰出现较早,其纤维素酶(Cx)活性较另2个采收期多1个高峰;多聚半乳糖醛酸酶(PG)活性增强最早,其贮后核仁酸价上升幅度最大,果实腐烂最快。(2)8月下旬同期采收的3个品种果实的贮期各生理指标变化趋于一致;贮藏54d时,果实腐烂率依次为‘辽宁4号’>‘中林5号’>‘西扶1号’。(3)‘辽宁4号’核仁可溶性蛋白质含量越高,贮后下降率最大。研究表明,青皮核桃果实采后生理代谢活性与耐贮性主要与采收时期有关,受品种影响较小,且8月中旬采收的果实采后生理代谢旺盛,耐贮藏性均最差;‘辽宁4号’果实在各采收期的耐贮性均小于其他品种果实。     

中国北方杂草稻光合与水分生理特性

杂草稻是一类重要的稻属种质资源,具有耐寒、耐旱、耐瘠薄等优良特性.本文以88份中国北方杂草稻资源和4份栽培稻为材料,研究了中国北方杂草稻的光合速率、蒸腾速率、气孔导度等光合与水分生理特性及其相互关系.结果表明: 北方杂草稻资源的光合和水分生理特性存在较大差异,具有丰富的多样性.杂草稻的光合速率变化范围在12.47～28.67 μmol CO₂·m^-2·s^-1,瞬时水分利用效率的变化范围在1.39～3.40 mg·g^-1.光合参数中,胞间CO₂浓度的变异系数最小,气孔导度的变异系数最大.光合速率与蒸腾速率、气孔导度呈极显著的二次曲线关系,光合速率与胞间CO₂浓度呈显著的直线关系,瞬时水分利用效率与蒸腾速率、气孔导度呈极显著的二次曲线关系.可用杂草稻材料的优越性能对栽培稻进行品种改良.     

黄河三角洲典型植被与地下水埋深和土壤盐分的关系

土壤盐分和地下水埋深是影响黄河三角洲植被发育和分布的重要因素.本文通过野外调查与统计分析,研究了黄河三角洲区域典型植被(翅碱蓬 柽柳、刺槐、芦苇和棉花)、地下水埋深、土壤盐分之间的关系.结果表明: 研究区地下水埋深显著影响土壤盐分,平均影响系数为0.327,地下水埋深在0.5～1.5 m的土壤盐渍化最严重;整个研究区内植被发育较差,其中,研究区78%面积的归一化植被指数(NDVI)<0.4,地下水埋深、土壤盐分对天然植被分布有显著影响;土壤盐分对研究区翅碱蓬-柽柳、刺槐、芦苇及棉花NDVI的影响显著,地下水埋深对翅碱蓬-柽柳NDVI的影响显著,对芦苇、棉花、刺槐NDVI的影响不显著.