Effects of predator-induced visual and olfactory cues on 0+ perch (Perca fluviatilis L.) foraging behaviour

Abstract –  Foraging juvenile fish with relatively high food demands are usually vulnerable to various aquatic and avian predators. To compromise between foraging and antipredator activity, they need exact and reliable information about current predation risk. Among direct predator-induced cues, visual and olfactory signals are considered to be most important. Food intake rates and prey-size selectivity of laboratory-reared, naive young-of-the-year (YOY) perch, Perca fluviatilis , were studied in experiments with Daphnia magna of two size classes: 2.8 and 1.3 mm as prey and northern pike, Esox lucius , as predator. Neither total intake rate nor prey-size selectivity was modified by predator kairomones alone (water from an aquarium with a pike was pumped into the test aquaria) under daylight conditions. Visual presentation of pike reduced total food intake by perch. This effect was significantly more pronounced (synergistic) when visual and olfactory cues were presented simultaneously to foraging perch. Moreover, the combination of cues caused a significant shift in prey-size selection, expressed as a reduced proportion of large prey in the diet. Our observations demonstrate that predator-induced olfactory cues alone are less important modifiers of the feeding behaviour of naive YOY perch than visual cues under daylight conditions. However, pike odour acts as a modulatory stimulus enhancing the effects of visual cues, which trigger an innate response in perch.     

腐殖酸复合生物肥对日光温室番茄增产增收效果的影响

为验证腐殖酸复合生物肥在日光温室番茄上的施用增产效果,选用液体冲施型腐殖酸复合生物肥,采用多处理随机区组试验,结果表明:常用肥+腐殖酸生物肥配施追肥与常用肥单施追肥比较,番茄的植物学性状、产量及经济效益均存在显著差异,常用肥+腐殖酸生物肥配合追施产量高达8697.62kg·(667 m2)-1,较常用肥单施追肥增产671.01kg·(667 m2)-1,增产率8.36%,收益达20544.28元/667m2,增收1580.4元/667m2,增加8.33%,增产增收效果明显,适宜在温室番茄生产上推广应用。     

烤烟和作物轮间作提高烟叶品质的研究现状

烤烟是我国重要的经济作物,但栽培过程中存在连作障碍。烟田连作导致病害增加,影响烟叶和轮间作作物的品质,进一步影响农田产出,另一方面,连作障碍导致烤烟种植土地匮乏。生产实践发现通过与其他作物轮间作可以改善烤烟连作障碍。本文从作物-土壤-微生物组成的根际微生态系统的视角,综述了烤烟与不同作物轮间作的现状以及轮间作后的土壤生物学性状变化,分析了不同轮间作模式下土壤理化性质和根际微生物群落的变化,特别是烤烟产量和烟叶内在品质的变化,对于烤烟与作物的轮间作机制进行了总结和展望,为烤烟轮间作种植模式提供了科学依据。     

Study on some functional and compositional properties of yak butter lipid

The present experiment was performed to determine some functional properties of yak butter lipids such as lipid class composition; conjugated linoleic acid (CLA) composition, differential scanning calorimetric (DSC) analysis, tyrosinase inhibition activity and antioxidant property. Yak butter lipids composition contained 98% triacylglycerols, 0.9% free fatty acids, 0.32% free sterols and 0.27% phospholipids. The CLA content in yak butter was 2.5% and the major portion was of cis‐9 and trans‐11 (90%). The DSC analysis of yak butter lipids showed a similar path for transition temperature as cow butter lipids, although the enthalpy of yak lipid was higher (40.0 mJ/mg) compared to cow butter lipids (32.0 mJ/mg). Melting point of yak butter was observed at 41°C. Yak butter with lactic acid, NaCl, citric acid and ascorbic acid showed pronounced tyrosinase inhibition activity. Vegetable oils blended with yak butter have extended the oxidation induction time.     

乳铁蛋白的生物学功能及其基因工程研究进展

乳铁蛋白是一种具有多种生物活性的糖蛋白。本文主要就乳铁蛋白的生物学功能及其基因工程研究进展作一综述。     

基于文献统计分析桑树研究的进展

通过对国内外各大数据库中桑树相关文献量的计量,对桑树的研究状况进行了分析。结果显示,桑叶作为家蚕饲料的传统农业模式已被打破,现已转向涉及医药、食品与保健等领域的多元化发展的桑树资源综合开发利用模式。其中,对桑树活性物质的研究由生物碱类物质转向多酚类物质和多糖类物质,桑树的抑制肿瘤和抗癌活性逐渐被重视,国内研究者对桑树的研究深度及影响力逐年提高。该结果可为桑树资源的进一步研究提供一定的参考。     

Biological Variability and Measurement Error Variability in Ocular Biometry in Samoyed Dogs

A-scan ultrasonography was performed in 40 healthy Samoyeds aged 2–5 years. Mydriasis and cycloplegia were induced in all dogs and 25 of the dogs were also sedated prior to the ultrasound examination. Five consecutive A-scans were taken on each eye and the intrasubject variance (measurement error) and true intersubject variance (true biological variation) were computed. The true biological variation was found to be of the same magnitude in both sedated and unsedated dogs, whereas the measurement errors were considerably larger in the group of unsedated dogs compared to the sedated ones. Magnitudes of the measurement errors for the anterior chamber depth and length of the vitreous body in the unsedated group were unacceptable. The sizes of the measurement errors in the sedated dogs were all within an acceptable range.     

细胞凋亡的常用调控基因研究近况

细胞凋亡主要受基因的控制，现已发现许多基因对细胞凋亡均有直接或间接的调控作用。通常将这些基因分为两大类，即细胞生存基因和细胞死亡基因。一般认为与细胞生存有关的基因包括C－myc,C-abl,Ras,V-src,Bcl-2,EIB,LMW5-HL,C-kit和Bcl-x等；与细胞死亡有关的基因包含P^35,P^53,RB,DCC,WT-1,CpGv,Bcr-abl,V-erb-A,tats20,DAD1,ADO/Fas,TGF-β，TRP－2，RP－8，TRPM－2，SGP－2，TIA，Bax,ICE,C-rel,irrecrst等。本文对目前使用较多研究较深入的几种凋亡调控基因，即C－myc基因，Bcl-2基因，P^53基因，ICE基因，Fas基因及FasL和Cdc2基因的来源，作用和相互间关系的研究近况，予以综述，做一简介。