Analysis of gas exchange of Merkus pine populations by the optimality approach

We hypothesized that northern and northeastern Thai populations of Merkus pine (Pinus merkusii Jungh. et de Vriese), which differ in the duration of their grass stage and which originate from slightly different climates in terms of water availability, differ in their gas exchange characteristics. We compared CO(2) exchange response to irradiance, diurnal regulation of leaf conductance within a 10-day period and structural properties among the populations. We used a model, which is based on the concept of optimal stomatal regulation, to analyze CO(2) exchange and transpiration rates. The two geographical groups did not differ in CO(2) exchange response to irradiance, diurnal transpiration, or water use. Mean stomatal length was significantly greater in the northeastern population than in the northern populations, but stomatal frequency did not differ among populations. First-year shoot growth and dry matter production, allocation of nitrogen to needles and root:shoot ratios were similar in the two geographical groups. Genotypic variation in the duration of the grass stage was not reflected in variation in gas exchange, indicating that the grass stage is an adaptation to more site-specific conditions. The modeled response of CO(2) exchange rates to irradiance fitted well the rates measured under laboratory conditions. The transpiration model, which utilized maximum leaf conductance and other parameters derived from the CO(2) exchange measurements, also fitted well the transpiration rates measured in a greenhouse under changing environmental conditions.     

Genetic variation and gene flow among Prunus cerasoides D. Don populations in northern Thailand: analysis of a rehabilitated site and adjacent intact forest

This study describes the level of genetic variation and gene flow within and among populations of Prunus cerasoides in rehabilitated sites and adjacent intact forest. The seven microsatellite loci employed detected a total of 75 alleles (n = 401). Polymorphic information content (PIC) varied from 0.34 to 0.83. Between the adult populations there was moderate genetic differentiation with an F _ST value of 0.0575, which suggests that the restoration plots had a similar genetic composition to that of the natural population. The gene flow assessment provides some interesting insights into the genetic diversity of P. cerasoides. In the 16 naturally occurring trees over 83% of the genotyped seed were fathered by unidentified trees whereas in restoration plot A only about 32% of the pollen came from an unidentified father. This proportion was even less in Plot C where 25% of the pollen parents were unidentified. The naturally occurring trees within Doi Suthep were surrounded by planted trees, which were contributing to the paternity of the seed crop. This result demonstrates that ‘‘fill in’’ planting should consist of locally sourced material if it is considered important to conserve the genetic integrity of the local populations.     

Impact of risk aversion and disease outbreak characteristics on the incentives of producers as a group to participate in animal disease insurance-A simulation

The participation of agricultural producers in financing losses caused by livestock epidemics has been debated in many countries. One of the issues raised is how reluctant producers are to participate voluntarily in the financing of disease losses before an outbreak occurs. This study contributes to the literature by examining whether disease losses should be financed through pre- or post-outbreak premiums or their combination. A Monte Carlo simulation was employed to illustrate the costs of financing two diseases of different profiles. The profiles differed in the probability in which the damage occurs and in the average damage per event. Three hypothetical financing schemes were compared based on their ability to reduce utility losses in the case of risk-neutral and risk-averse producer groups. The schemes were examined in a dynamic setting where premiums depended on the compensation history of the sector. If producers choose the preferred financing scheme based on utility losses, results suggest that the timing of the premiums, the transaction costs of the scheme, the degree of risk aversion of the producer, and the level and the volatility of premiums affect the choice of the financing scheme.     

Effects of working-memory training on striatal dopamine release

Updating of working memory has been associated with striato-frontal brain regions and phasic dopaminergic neurotransmission. We assessed raclopride binding to striatal dopamine (DA) D2 receptors during a letter-updating task and a control condition before and after 5 weeks of updating training. Results showed that updating affected DA activity before training and that training further increased striatal DA release during updating. These findings highlight the pivotal role of transient neural processes associated with D2 receptor activity in working memory.     

北半球高卢蜜环菌的遗传多样性与分子鉴定

从北美、欧洲和中国收集２３个高卢密环菌菌株，ＰＣＲ扩增其rDNA的ＩＧＳ和ＩＴＳ区域，用ＡluI,HaeIII,HinfI和ＴagI四种限制性内切酶进行酶切，同时结合随机扩增微卫生（ＲＡＭＳ）多态性，对北半球的高卢蜜环菌的遗传多样性进行了分析，结果发现了高卢蜜环菌的６种ＩＧＳ－ＲＦＬＰ图谱类型，其中gal(B)和gal(D)是国内外无报道的新的ＩＧＳ－ＲＦＬＰ型，ＲＦＬＰ系统树发现该种有明显的大陆之间的遗传分化，存在中国，欧洲，北美和亚洲４个亚群体，ＲＡＭＳ分析表明北半球高卢蜜环菌存在亚洲，欧洲，北美－中国和北美－欧洲和北美－欧洲等４个高卢蜜环菌发育系，而且不同大陆的高卢蜜环菌具有较近的亲缘关系，而相同大陆的却具有不同的起源，特别是北美的高卢蜜环菌两个发育系异源性很高，北美东部的发育系同欧洲的关系比较近，而北西部的同亚洲关系比较近，同时表明ＲＡＭＳ技术是分析菌物种内遗传多样性的优越方法。     

Influence of dietary fat level on feed intake, growth and fat deposition in the whitefish Coregonus lavaretus

Whitefish, Coregonus lavaretus, of initial mean weight 260–265 g were fed either a high-fat or a low-fat diet (dietary fat: 27.5% vs. 12.6%) to examine the influence of dietary fat level on feed intake, growth and patterns of fat deposition. The fish were held at 14.5 °C under a 24L:0D photoperiod, and were fed for 4 h each day. The experiment was run for 11 weeks during which feed intake (three times by X-radiography) and growth were monitored. Samples of fish were taken for body composition analysis at the start and end of the experiment. There were only small differences between dietary treatment groups in feed intake and final body weights, but the body composition of the fish was significantly influenced by the fat content of the diet. The whitefish fed the high-fat diet tended to have higher relative fat contents in the viscera [% fat as mean (SD): 29.6 (9.4)% vs. 22.1 (10.0)%] and carcass [% fat: 12.7 (1.9)% vs. 10.5 (1.3)%] than their counterparts fed the low-fat diet. This resulted in a higher whole-body fat concentration [% fat: 14.0 (1.9)% vs. 11.5 (1.5)%] amongst the fish fed the high-fat diet, and these fish had a higher energy gain than the whitefish fed the low-fat diet. The results confirm that it is possible to manipulate the chemical composition of whitefish by changing dietary composition. © Rapid Science Ltd. 1998     

Isolation and structure elucidation of procyanidin oligomers from Saskatoon berries (Amelanchier alnifolia)

Proanthocyanidin oligomers with different degrees of polymerization were isolated from Saskatoon berries (Amelanchier alnifolia) by means of gel adsorption and normal-phase liquid chromatography. The proanthocyanidins were identified using electrospray ionization mass spectrometry, nuclear magnetic resonance spectroscopy, and thiolytic degradation coupled with reversed-phase liquid chromatography. The results established that Saskatoon berries contain proanthocyanidins from dimers through heptamers and higher polymers. Saskatoon proanthocyanidins are essentially of procyanidin type, consisting mainly of epicatechin units linked by B-type bonds. The simple procyanidin profile of Saskatoon berries allowed the procyanidins to be separated precisely according to their degrees of polymerization. In the future they can be used as standard compounds for qualitative and quantitative analysis of procyanidins as well as for elucidation of the biological activities of proanthocyanidins.     

Linking the gaps between conservation research and conservation management of rare dipterocarps: A case study of Shorea lumutensis

To conserve a rare plant, conservation programs must be guided by the biological attributes of the species. What constitutes the most critical biological information for plant conservation has been the issue of discussion for the last 30 years. Most scientists promote an approach that is either ecological or genetic in emphasis. Ecological and genetic processes will often interact synergistically to influence the population viability and to determine the persistence of populations in the long run. Consequently, conservation management of plant species, in addition to ecological information, requires a robust understanding of underlying genetic processes as well as the variation within and between populations. Conservation has a cost and the resources available for conservation programs are always limited. Therefore, conservation management strategies should not only be scientifically justified but also practical in terms of resource availability. Shorea lumutensis is a rare and endemic dipterocarp in Peninsular Malaysia. A comprehensive research activity was initiated to assess the population ecology and population genetics of S. lumutensis to elucidate specific ecological and genetic requirements and subsequently to set conservation strategies and priorities. This paper is apparently the first attempt at applying both the ecological and genetic approaches into conservation management of a rare dipterocarp. In addition, this paper also attempts to link the gaps between conservation research and conservation management in a realistic manner. It is our hope that this study will serve as a model for the study of other rare dipterocarps which should be given priority for conservation.     

Influence of dietary fat level and increased adiposity on growth and fat deposition in rainbow trout, Oncorhynchus mykiss (Walbaum)

Rainbow trout, Oncorhynchus mykiss (Walbaum), (initial weight ～ 90 g) were fed diets differing in fat content (27.5% versus 12.6%) to examine the effects of dietary fat level on growth and fat deposition. During phase 1, which was run for 11 weeks, the fish were fed either a high- (27.5%) or low-fat (12.6%) diet. The fish were held at 14.5 °C under a 24 h:0 h light:dark photoperiod and were fed for 4 h each day during this phase. Subsequently, in phase 2, both diets were presented simultaneously, and the influence of adiposity on growth and fat deposition was examined in a growth trial which lasted for 8 months. There were no significant differences in body weights at the end of phase 1 (360.7 ± 7.7 g versus 348.2 ± 18.7 g for the fish on the high- and low-fat diets, respectively), but body composition was influenced by the fat content of the diet. The trout fed the high-fat diet had higher viscerosomatic indices (VSI: 11.7 ± 2.0% versus 9.1 ± 0.7%) and higher visceral fat contents (per cent fat: 38.0 ± 6.7% versus 23.3 ± 3.7%) than trout fed the low-fat diet. The percentage fat contents of the carcass (per cent fat: 12.4 ± 1.0% versus 9.3 ± 0.7%) and whole body (per cent fat: 15.4 ± 1.6% versus 10.5 ± 0.7%) were higher amongst the trout fed the high-fat diet, and these fish had a higher energy gain than those fish fed the low-fat diet. Differences in adiposity between the trout fed the high- and low-fat diets did not result in any differences in weight gain when the fish were provided with both diets simultaneously. During phase 2, the fish that had previously been fed the low-fat diet deposited more fat than those fed the high-fat diet during phase 1. The latter maintained whole body fat concentrations at ± 15% (phase 1: 15.4 ± 1.6%; phase 2: 15.2 ± 1.2%), whereas the fish that had been fed the low-fat diet increased their body fat concentration during phase 2 (phase 1: 10.5 ± 0.7%; phase 2: 14.7 ± 1.3%). Thus, there were no significant differences between groups in either body weight or proximate composition by the end of the experiment.     

Economic values of supply chain productivity and quality traits calculated for a farmed European whitefish breeding program

Economic values of different fish traits are needed to direct breeding programs to optimize economic benefits for aquaculture industry. The aim of this article is to highlight and calculate how different traits affect the value of farmed fish supply chain. Supply chain approach is needed to calculate economic impact of fish traits because several fish traits affect costs and returns not only in fish farming but also at the processing and retail level. In this article, economic values are calculated for 14 productivity and product quality traits in European whitefish (Coregonus lavaretus). Productivity affecting traits, such as growth, mortality and different yields, are included in the study. In addition, economic values are calculated for several quality traits like fillet gaping, appearance and fat content of flesh.

Productivity traits had the highest economic importance if the traits could be improved. However, quality traits may cause even higher economic losses, if the quality decreases. Thus, the management of the breeding program should pay simultaneous attention to both quality and productivity traits.