Spawning habits and embryonic development of the banded lampeye killifish Aplocheilichthys spilauchen (Duméril 1861) in ex situ fresh and brackish water environments

Aside from ornamental uses, there is growing interest in using killifishes for a multiplicity of purposes including baitfish and mosquito biocontrol. This experiment explored the spawning habits and embryonic development of the banded lampeye, Aplocheilichthys spilauchen in ex situ freshwater (0.04‰) and brackish water (5.01‰) to ascertain the captive breeding prospects for mosquito control in areas where they occur. Significantly higher number of eggs were laid in the brackish water than the freshwater (X² = 1613.0, P < 0.05), and black mop was the most preferred spawning substrate, followed by green, blue and white mops. Microscopic monitoring of embryos revealed that cleavage occurred within the first 30 min after fertilization, organogenesis commenced on average in the 25th hour and hatching in approximately 230 h. Although freshwater eggs were relatively bigger than brackish water eggs and certain embryonic developmental stages occurred faster in the freshwater than brackish water, these differences were overall not significant and had no effects on the development and hatching. The observed outcome that A. spilauchen can be optimally propagated with black mops in brackish water offers a significant step in its use for the mosquito biocontrol programme, as well as other potential uses not yet explored.     

官亭水库黄尾鲴食性的初步研究

黄尾鲴仔幼鱼阶段的食性是随着鳃耙和肠管形态的变化而变化。体长11.8—12.3mm,鳃耙形状开始分化,肠呈1—2弯曲,仔鱼吞食小型枝角类,主要是裸腹溞;体长15.8—17.4mm,口端位,鳃耙成筛网,肠呈4—8弯曲,前肠膨大,主要食物是腐屑,摇蚊幼虫,“水华”型的裸藻与蓝绿藻。体长18mm的幼鱼,口下位,鳃耙与肠管进一步发育,幼鱼转入底栖,其前肠内含物主要为泥沙、腐屑、摇蚊幼虫,浮游动物与浮游植物。黄尾鲴成鱼的主要食物为大量的腐屑和极少数的着生硅藻、颤藻。成鱼食物营养价值很差,其总N含量为0.372%,有机质为4.8%,每克湿重的热值为146.35卡,成鱼周年摄食,摄食量大,这是黄尾鲴摄食的特点。       

钾肥类型对菜心(菜薹)生长、细胞保护酶和内源激素的影响

为探讨钾肥类型对菜心(Brassica campestris L. ssp. chinensis var. utilis Tsen et Lee)的作用效应,研究了不同钾肥类型和水平对菜心生长、细胞保护酶和内源激素的影响。结果表明,氯化钾或硫酸钾处理可提高菜心叶片的POD 和CAT 活性、IAA 和GA₃ 含量,降低MDA 含量,提高菜薹产量。随着钾水平的提高,叶片IAA 和GA₃ 含量、POD 和CAT 活性以及菜薹质量明显提高,MDA 含量降低。当施钾90 kg hm^-2 时,叶片的GA₃ 和IAA 含量显著下降,而POD 活性和菜薹产量没有显著变化。在相同水平下,氯化钾与硫酸钾对植株生长、菜薹产量、叶片GA₃ 含量的影响不显著。当施钾0~90 kg hm^-2 时,氯化钾处理的叶片POD 活性显著高于硫酸钾处理;而施钾135~180 kg hm^-2 时,氯化钾处理的叶片POD 活性则显著低于硫酸钾处理。除了90 kg hm^-2 氯化钾处理的CAT 活性和45 kg hm^-2 氯化钾处理的MDA 含量低于硫酸钾处理以及90 kg hm^-2 和180 kg hm^-2 氯化钾处理的IAA 含量高于硫酸钾处理的外,相同水平氯化钾和硫酸钾处理的CAT 活性、MDA 含量和IAA 含量没有显著差异。可见,钾肥类型对菜心的活性氧代谢系统及内源激素含量有一定的影响,但氯化钾与硫酸钾对菜心的施用效果相当,生产上可采用氯化钾代替硫酸钾以节约肥料成本,K₂O 施用量以90 kg hm^-2 为宜。     

Growth, senescence and water use efficiency of spring oilseed rape (Brassica napus L. cv. Mozart) grown in a factorial combination of nitrogen supply and elevated CO2

Atmospheric CO₂ enrichment is expected to affect the resource use efficiency of C3 plants with respect to water, nutrients and light in an interactive manner. The responses of oilseed rape (OSR) to elevated CO₂ have not much been addressed. Since the crop has low nitrogen use efficiency, the interactive effects of CO₂ enrichment and nitrogen supply deserve particular attention.Spring OSR was grown in climate chambers simulating the seasonal increments of day length and temperature in South-Western Germany. Three levels of N fertilisation representing 75, 150 and 225 kg ha⁻¹ and two CO₂ concentrations (380 and 550 μmol mol⁻¹) were used to investigate changes in source-sink relationships, plant development and senescence, water use efficiency of the dry matter production (WUE_prod.), allocation patterns to different fractions, growth, yield and seed oil contents. Seven harvests were performed between 72 and 142 days after sowing (DAS).Overall, plant performance in the chambers was comparable to the development under field conditions. While CO₂ responses were small in the plants receiving lowest N-levels, several significant N × CO₂ interactions were observed in the other treatments. Increasing the N availability resulted in longer flowering windows, which were furthermore extended at elevated CO₂ concentrations. Nevertheless, significantly less biomass was allocated to reproductive structures under elevated CO₂, while the vegetative C-storing organs continued to grow. At the final harvest shoot mass of the CO₂ exposed plants had increased by 9, 8 and 15% in the low, medium and high N treatments. Root growth was increased even more by 17, 43 and 33%, respectively and WUE_prod. increased by 23, 42 and 35%. At the same time, seed oil contents were significantly reduced by CO₂ enrichment in the treatments with ample N supply.Obviously, under high N-supply, the CO₂ fertilisation induced exaggerated growth of vegetative tissues at the expense of reproductive structures. The interruption of source-sink relationships stimulated the formation of side shoots and flowers (branching out). While direct effects of elevated CO₂ on flowering can be excluded, we assume that the increased growth under high N and CO₂ supply created nutrient imbalances which hence affected flowering and seed set.Nevertheless, the final seed macronutrient concentrations were slightly increased by elevated CO₂, indicating that remobilisation of nutrients from the sources (leaves) to the sinks (seeds) remained effective. These findings were supported by the lower nitrogen concentrations in senescing leaves and probably increased N remobilisation to other plant parts under elevated concentrations of CO₂. All the same, CO₂ enrichment caused a decline in seed oil contents, which may translate into a reduced crop quality.     

环境因素对薇甘菊开花结实影响初探

2001—2002年度在广东东莞市选取不同的自然小生境,研究土壤肥力、土壤水分和生境郁闭度对薇甘菊(Mikania micrantha H．B．K)开花结实的影响,结果表明：土壤肥力较高,花数较多,花期较长,结实率较高,种子千粒重较大;但土壤肥力过高,虽然种子千粒重大,花期长,但花数少,结实率低。在开阔的生境中,薇甘菊花数多,花期长;在林荫处花期短,花数少,但种子千粒重反而有所升高;植株在郁闭度为10％-20％的生境中结实率最高,高于20％或低于10％结实率均有所降低,过强或过弱的光照均不利于结实。土壤湿度虽然对种子千粒重无明显影响,但对薇甘菊花数、花期和结实率的影响显著,土壤湿度大,花数多,结实率高,花期长。在自然生境中,三种因素的影响既相对独立又相互制约。     

Cyclic GMP stimulates flower induction of <Emphasis Type="Italic">Pharbitis nil</Emphasis> via its influence on cGMP regulated protein kinase

It was revealed that cGMP is involved in the control of photoperiodic flower induction. Further insight into the signalling function of cGMP is likely to be obtained by analysis of its effectors. Therefore, in the present study, we used various agents that cause changes in cGMP-dependent kinase (PKG) activity and examined their effects on the activity of kinase isolated from Pharbitis nil and flower induction. It was found that exogenous applications of PKG activators (cGMP, 8-pCPT-cGMP, 8-Br-cGMP, 8-pCPT-PET-cGMP) to cotyledons which were exposed to a 12-h-long subinductive night significantly increased flowering response. From among the many antagonists of cGMP-dependent protein kinase Rp-8-Br-PET-cGMPS, Rp-8-pCPT-cGMP and the synthetic heptapeptide inhibitor of PKG were used for our analysis. When Rp-8-Br-PET-cGMPS and Rp-8-pCPT-cGMP were applied during a 16-h-long inductive night, significant reduction in the number of flower buds was observed, whereas synthetic heptapeptide did not change the intensity of flowering. The influence of the analysed chemicals on protein kinase activity was also examined in vitro. With the exception of synthetic heptapeptide, which seems ineffective, the enzyme activity was stimulated by all agonists and significantly reduced by all antagonists. The activity of protein kinase was assayed in P. nil soluble protein fractions from plants grown under flower-inducing and non-inducing conditions. In vitro phosphorylation was slightly greater in the soluble fraction obtained from plants grown under the flower-inducing condition, reaching 1.05 nmol/min/mg protein, when compared to the control 0.81 nmol/min/mg protein. In relation to the results described above, we can conclude that cGMP as a mediator participating in photoperiodic flower induction may govern this process by the phosphorylation mechanism via its influence on cGMP-dependent protein kinase activity.     

花灌木种质资源及其遗传多样性研究

综述了国内外关于花灌木种质资源在形态学、细胞学、酶、DNA等水平的多样性研究,探讨了目前花灌木种质资源遗传多样性研究中存在的一些问题和建议。