Enhancement of extractable ethylene at light/dark transition in primary leaves of paclobutrazol-treated Phaseolus vulgaris seedlings

Paclobutrazol [(2RS,3RS)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)pentan-3-ol], a triazole growth retardant, increased the 1-aminocyclopropane-1-carboxylic acid (ACC) level and resulted in reduced ethylene production, estimated as ethylene release in a closed system or by vacuum-extraction, in the primary leaves of Phaseolus vulgaris L. cv. Juliska seedlings exposed to light. At the light/dark transition, a definite enhancement of the endogenous ethylene level was observed by vacuum-extraction of primary leaves of treated plants and the ethylene deficiency of retardant-treated leaves ceased. The concentration of ACC after the light/dark transition followed the pattern for ethylene, and the increase in ACC content was paralleled by a decrease in malonyl-ACC.
It is concluded that the internal level of ethylene is not necessarily lower in the primary leaves of paclobutrazol-treated bean plants, but under special environmental conditions in vivo it may reach that of the control.     

旋毛虫肌幼虫ES抗原的基因克隆及高效表达

作者对编码旋毛虫肌幼虫ES抗原的部分结构基因进行了克隆、鉴定和表达。用RNA PCR技术直接从旋毛虫肌幼虫总RNA中反转录并扩增出0．7kh的靶DNA,酶切分析后将其克隆到融合表达载体pEx3lC中。SDS—PAGE电泳表明,含重组子的大肠杆菌能够表达出一分子量为37kDa的融合蛋白(P37),后者占菌体总蛋白的22%以上,并以包含体形式存在于菌体中。经对纯化后表达蛋白的ELlSA检测,证明它能被猪旋毛虫病阳性血清和抗旋毛虫单克隆抗体识别。研究结果揭示,重组蛋白P37对于研制旋毛虫病诊断抗原和免疫抗原具有潜在的应用价值。     

转化生长因子α－绿脓杆菌外毒素融合蛋白TGFα－PE40高效表达质粒的构建和表达

利用基因工程技术,将质粒pYX382用xbaI和EcoRl切下插入的TGFa—PE40融合 基因片段-连接到可表达载体pCB604的XbaⅠ／EcoR Ⅰ位点中,构建成新的重组质粒p2x—TP1。P2x—TP1转化E.coli BL2l感受志菌后,在ⅠPTG诱导下Ⅰpp启动子转录表达TGFα—PE40融合蛋白。表达产物主要以包涵体形式沉积在细胞内。融合蛋白表达量的高低与诱导时的细胞密度,诱导的温度以及培养基有关。在一定范围内与诱导剂的剂量以及诱导时间的长短无关。P2x—TPl重组质粒在工程菌中的表达TGFα－PE40融合蛋白量约为50mg／L。     

世居及移居高原青少年最大有氧能力的特征

本文报道海拔３４１７ｍ和４２８０ｍ地区世居藏族和移居汉族青少年运动状态下心肺功能的对比研究。结果显示：３４１７ｍ和４２８０ｍ世居藏族的最大氧耗量、无氧阈值及最大心输出量都明显大于汉族,血氧饱和度（Ｓａｏ２）随运动负荷的增加而降低。海拔３４１７ｍ藏、汉族的△Ｓａｏ２分别为７．４６％和１０．０３％,４２８０ｍ处为８．５７％和１３．７５％,最大心率随海拔升高而下降。研究提示,藏族青少年有较高的最大有氧能力,反映了他们对低氧环境的适应优势。     

Large old trees increase growth under shifting climatic constraints: Aligning tree longevity and individual growth dynamics in primary mountain spruce forests

In a world of accelerating changes in environmental conditions driving tree growth, tradeoffs between tree growth rate and longevity could curtail the abundance of large old trees (LOTs), with potentially dire consequences for biodiversity and carbon storage. However, the influence of tree-level tradeoffs on forest structure at landscape scales will also depend on disturbances, which shape tree size and age distribution, and on whether LOTs can benefit from improved growing conditions due to climate warming. We analyzed temporal and spatial variation in radial growth patterns from ~5000 Norway spruce (Picea abies [L.] H. Karst) live and dead trees from the Western Carpathian primary spruce forest stands. We applied mixed-linear modeling to quantify the importance of LOT growth histories and stand dynamics (i.e., competition and disturbance factors) on lifespan. Finally, we assessed regional synchronization in radial growth variability over the 20th century, and modeled the effects of stand dynamics and climate on LOTs recent growth trends. Tree age varied considerably among forest stands, implying an important role of disturbance as an age constraint. Slow juvenile growth and longer period of suppressed growth prolonged tree lifespan, while increasing disturbance severity and shorter time since last disturbance decreased it. The highest age was not achieved only by trees with continuous slow growth, but those with slow juvenile growth followed by subsequent growth releases. Growth trend analysis demonstrated an increase in absolute growth rates in response to climate warming, with late summer temperatures driving the recent growth trend. Contrary to our expectation that LOTs would eventually exhibit declining growth rates, the oldest LOTs (>400 years) continuously increase growth throughout their lives, indicating a high phenotypic plasticity of LOTs for increasing biomass, and a strong carbon sink role of primary spruce forests under rising temperatures, intensifying droughts, and increasing bark beetle outbreaks.     

Dominant vs. codominant genetic markers in the estimation of male mating success

Although a major component of fitness, male reproductive success is generally extremely difficult to estimate. As a result, genetic methods and maximum likelihood models have been developed to estimate male parentage, but all are limited in practice by the degree of genetic variation observable. Scoring individuals phenotypically at a large number of random loci exhibiting dominance (e.g. RAPD markers) may provide a means of detecting sufficient genetic variation. Dominance, however, represents a loss of information and therefore greater variation in the estimate of paternity. A mixture model describing mating in a population is presented to quantify the trade-off between marker types when estimates of male fertility are sought. A sample size 1.5-2.0 times greater is required for dominant markers under some conditions to obtain the same confidence in fertility estimates as for codominant markers, although with large sample sizes the fertility estimates are similar for either marker type. Since the number of dominant DN A markers is not limited in the same manner as is the number of codominant protein markers, one's confidence in the estimates can be increased above that possible from proteins by surveying additional loci. However, for a fixed sample size a trade-off exists between the number of progeny assayed per female and the number of loci surveyed. In many cases more progeny per female provide better estimates of fertility than more loci.     

Dietary protein requirement for captive juvenile green turtles (Chelonia mydas)

Head-starting programs are extremely important for restoring the population of sea turtles in wild whereas husbandry conditions and feeding regimens of captive turtles are still limited. In the current study, the optimal dietary protein requirement for green turtle (Chelonia mydas) was investigated to support rearing in head-starting programs. Twenty-five-day-old turtles (44.5–46.2 g body weight, n = 45) were randomly distributed into 15 experimental plastic tanks, comprising three treatment replications of 3 turtles each. They were fed fishmeal-based feeds containing different levels of protein (30%, 35%, 40%, 45%, and 50%) for 8 weeks. At the end of feeding trial, growth performance (specific growth rate = 1.86% body weight/day) and feed utilization (protein efficiency ratio = 3.30 g gain/g protein) were highest in turtles fed with 40% protein in feed (p < .05). These nutritional responses were significantly supported by specific activities of fecal digestive enzymes, especially trypsin, chymotrypsin, amylase, and the amylase/trypsin ratio. Also, this dietary level improved the deposition of calcium and phosphorus in carapace, supporting a hard carapace and strong healthy bones. There were no negative effects in general health status of reared turtles, as indicated by hematological parameters. Based on a broken-line analysis between dietary protein levels and specific growth rate, the optimal protein level for green turtles was estimated as 40.6%. Findings from the current study support the use of artificial diets of specific protein levels to rear captive green turtle before release to natural habitats.     

Upper thermal limits predict herpetofaunal responses to forest edge and cover

Amphibians and reptiles are sensitive to changes in the thermal environment, which varies considerably in human-modified landscapes. Although it is known that thermal traits of species influence their distribution in modified landscapes, how herpetofauna respond specifically to shifts in ambient temperature along forest edges remains unclear. This may be because most studies focus on local-scale metrics of edge exposure, which only account for a single edge or habitat patch. We predicted that accounting for the combined effect of multiple habitat edges in a landscape would best explain herpetofaunal response to thermally mediated edge effects. We (1) surveyed herpetofauna at two lowland, fragmented forest sites in central Colombia, (2) measured the critical thermal maximum (CT_max) of the species sampled, (3) measured their edge exposure at both local and landscape scales, and (4) created a thermal profile of the landscape itself. We found that species with low CT_max occurred both further from forest edges and in areas of denser vegetation, but were unaffected by the landscape-scale configuration of habitat edges. Variation in the thermal landscape was driven primarily by changes in vegetation density. Our results suggest that amphibians and reptiles with low CT_max are limited by both canopy gaps and proximity to edge, making them especially vulnerable to human modification of tropical forest. Abstract in Spanish is available with online material.     

Functional data analysis with covariate-dependent mean and covariance structures

Functional data analysis has emerged as a powerful tool in response to the ever-increasing resources and efforts devoted to collecting information about response curves or anything that varies over a continuum. However, limited progress has been made with regard to linking the covariance structures of response curves to external covariates, as most functional models assume a common covariance structure. We propose a new functional regression model with covariate-dependent mean and covariance structures. Particularly, by allowing variances of random scores to be covariate-dependent, we identify eigenfunctions for each individual from the set of eigenfunctions that govern the variation patterns across all individuals, resulting in high interpretability and prediction power. We further propose a new penalized quasi-likelihood procedure that combines regularization and B-spline smoothing for model selection and estimation and establish the convergence rate and asymptotic normality of the proposed estimators. The utility of the developed method is demonstrated via simulations, as well as an analysis of the Avon Longitudinal Study of Parents and Children concerning parental effects on the growth curves of their offspring, which yields biologically interesting results.     

Influences of sea level changes and volcanic eruptions on Holocene vegetation in Tonga

Here, we investigate Mid- to Late-Holocene vegetation changes in low-lying coastal areas in Tonga and how changing sea levels and recurrent volcanic eruptions have influenced vegetation dynamics on four islands of the Tongan archipelago (South Pacific). To investigate past vegetation and environmental change at Ngofe Marsh (‘Uta Vava’u), we examined palynomorphs (pollen and spores), charcoal (fire), and sediment characteristics (volcanic activity) from a 6.7-m-long sediment core. Radiocarbon dating indicated the sediments were deposited over the last 7700 years. We integrated the Ngofe Marsh data with similar previously published data from Avai’o’vuna Swamp on Pangaimotu Island, Lotofoa Swamp on Foa Island, and Finemui Swamp on Ha’afeva Island. Plant taxa were categorized as littoral, mangrove, rainforest, successional/ disturbance, and wetland groups, and linear models were used to examine relationships between vegetation, relative sea level change, and volcanic eruptions (tephra). We found that relative sea level change has impacted vegetation on three of the four islands investigated. Volcanic eruptions were not identified as a driver of vegetation change. Rainforest decline does not appear to be driven by sea level changes or volcanic eruptions. From all sites analyzed, vegetation at Finemui Swamp was most sensitive to changes in relative sea level. While vegetation on low-lying Pacific islands is sensitive to changing sea levels, island characteristics, such as area and elevation, are also likely to be important factors that mediate specific island responses to drivers of change.