Effects of nest-box density on the behavior of Tree Swallows during nest building

ABSTRACT.   In territorial species, increased density is often linked to an increase in aggressive interactions, which may result in trade-offs between competitive behavior and nest construction. We examined the impact of nesting in areas of high-density versus low-density nest boxes on conspecific interactions and nest-building effort in a population of Tree Swallows ( Tachycineta bicolor ). We also examined whether expected differences in behavior related to variation in nest quality and reproductive success in high-density and low-density areas. No differences in either nest-building behavior or reproductive success were observed between areas of high-density and low-density boxes, but there was a tendency of more frequent behavioral interactions at high density. Similarly, there was a significant difference between pairs defending single nest boxes and those defending multiple nest boxes in the number of interactions with conspecifics. These results suggest that although there may be more competition with conspecifics for Tree Swallows nesting at high density, this does not appear to affect either nest quality or reproductive success.     

黄花补血草挥发性化学成分研究

为了研究黄花补血草挥发油的化学成分,本文采用了水蒸气蒸馏法从黄花补血草中提取挥发油,并用GC-MS法采用最佳分析条件对化学成分进行鉴定,用峰面积归一化法测定各化合物在挥发油中的相对百分含量;通过研究,鉴定出70种化合物,其峰面积相对含量约占挥发油总量82.12%。黄花补血草挥发油的主要组分为2-硝基乙醇(59.63%)、正二十四烷(3.71%)、二苯胺(2.31%)、6,10,14-三甲基-2-十五烷酮(1.79%)、正二十一烷(1.57%)、丙二醇(1.40%)等。     

Genomic clustering of cyanogenic glucoside biosynthetic genes aids their identification in Lotus japonicus and suggests the repeated evolution of this chemical defence pathway

Cyanogenic glucosides are amino acid-derived defence compounds found in a large number of vascular plants. Their hydrolysis by specific β-glucosidases following tissue damage results in the release of hydrogen cyanide. The cyanogenesis deficient1 (cyd1) mutant of Lotus japonicus carries a partial deletion of the CYP79D3 gene, which encodes a cytochrome P450 enzyme that is responsible for the first step in cyanogenic glucoside biosynthesis. The genomic region surrounding CYP79D3 contains genes encoding the CYP736A2 protein and the UDP-glycosyltransferase UGT85K3. In combination with CYP79D3, these genes encode the enzymes that constitute the entire pathway for cyanogenic glucoside biosynthesis. The biosynthetic genes for cyanogenic glucoside biosynthesis are also co-localized in cassava (Manihot esculenta) and sorghum (Sorghum bicolor), but the three gene clusters show no other similarities. Although the individual enzymes encoded by the biosynthetic genes in these three plant species are related, they are not necessarily orthologous. The independent evolution of cyanogenic glucoside biosynthesis in several higher plant lineages by the repeated recruitment of members from similar gene families, such as the CYP79s, is a likely scenario.     

Physico‐chemical mechanisms of resistance to shoot fly,Atherigona soccata in sorghum,Sorghum bicolor

Sorghum shoot fly, Atherigona soccata is an important pest of sorghum, and host plant resistance is one of the important components for minimizing the losses due to this pest. Therefore, we evaluated a diverse array of sorghum genotypes to identify physico‐chemical characteristics conferring resistance to A. soccata. Susceptibility to shoot fly was associated with high amounts of soluble sugars, fats, leaf surface wetness and seedling vigour; while leaf glossiness, plumule and leaf sheath pigmentation, trichome density and high tannin, Mg and Zn showed resistance to shoot fly. Stepwise regression indicated that Mg, Zn, soluble sugars, tannins, fats, leaf glossiness, leaf sheath and plumule pigmentation and trichome density explained 99.8% of the variation in shoot fly damage. Path coefficient analysis suggested that leaf glossiness, trichome density, Mg and fat content and plant plumule pigmentation can be used as markers traits to select for shoot fly resistance in sorghum.     

中华补血草多酚提取物对自由基的清除能力

采用超声波辅助浸提—大孔树脂吸附法从中华补血草[ Limonium sinense (Girard) Kuntze]根、根茎、叶和花中获得多酚提取物,并对它们的得率和组成成分进行了初步分析;在此基础上,比较研究了不同部位多酚提取物对DPPH·、·OH和O2的清除能力.实验数据表明:中华补血草根、根茎、叶和花多酚提取物的得率分别为12.42％、5.98％、5.27％和3.98％,差异明显;多酚提取物中总酚、原花色素、黄烷醇和总黄酮含量变化幅度较大,分别为51.87％ ～61.60％、5.62％～39.47％、3.69％～12.46％和2.53％ ～35.97％;其中,总酚、原花色素和黄烷醇含量均以根多酚提取物最高,总黄酮含量以花多酚提取物最高,均与其他部位多酚提取物有显著差异.随质量浓度提高,4个部位多酚提取物对3种自由基的清除率总体上逐渐增大;其中根多酚提取物对DPPH·的清除作用最强,半数清除质量浓度(ρSC50)为38.52 μg·L-1,显著低于阳性对照芦丁和BHT(ρSC50分别为67.40和74.25 μg·L-1);花多酚提取物对·OH和O2的清除能力最强,ρSC50分别为53.51和74.00 μg·L-1,均低于芦丁;总体上,4个部位多酚提取物对DPPH·的清除能力由强至弱依次为根、根茎、叶、花,对·OH和O2的清除能力由强至弱依次为花、根、叶、根茎.结果显示:中华补血草不同部位多酚提取物均具有较强的自由基清除能力,其中,根和花多酚提取物中高含量的原花色素和黄酮类成分分别与其自由基清除能力密切相关.     

Exogenous supply of pantoyl lactone to excised leaves increases their pantothenate levels

BACKGROUND AND AIMS: All plants synthesize pantothenate but its synthesis and regulation are not well understood. The aim of this work is to study the effect of exogenous supply of precursor compounds on pantothenate levels in leaves. METHODS: Precursor compounds were supplied in solution to excised leaves and the pantothenate content was measured using a microbial method. KEY RESULTS: Pantothenate levels in excised leaves of Limonium latifolium, tomato (Lycopersicon esculentum), bean (Phaseolus vulgaris) and grapefruit (Citrus x paradisi) were examined following an exogenous supply of the precursor compounds pantoyl lactone or beta-alanine. Significantly higher levels of extractable pantothenate were found when pantoyl lactone was supplied, but not when beta-alanine was supplied despite a measurable uptake of beta-alanine into the leaf. CONCLUSIONS: The results suggested that the pantoate supply may be rate-limiting or regulating pantothenate synthesis in leaves.     

江苏沿海滩涂中华补血草的保护性研究

中华补血草是一种经济价值、生态价值较高的盐生植物,花朵细小艳丽,全草含各种黄酮体和杨梅树皮甙等有效成份,不仅可供观赏,还可药用.中华补血草可改善盐碱土的土壤结构,使盐土脱盐,被誉为盐碱地改造的"先锋植物".由于沿海滩涂开发速度加快,中华补血草的适生环境受到极大的威胁,导致种群数量越来越少.因此,加强对中华补血草的研究与迁地保护,势在必行.