Growth and biomass partitioning of nine provenances of Quillaja saponaria seedlings to water stress

Information on the morphological and physiological responses of seedlings to stressors, such as water stress, is required for successful early establishment of seedlings. We examined provenance variation in morphological and physiological traits of Quillaja saponaria Molina seeds from nine provenances representing a latitudinal transect across the species range in Chile. The seedlings were subjected to two water regimes (well-watered vs water restriction) in a nursery experiment, and growth, biomass, survival, and gas exchange traits were measured. As expected, well-watered seedlings exhibited a superior performance in all traits analysed. Provenance effects were significant for most of the morphological and physiological traits. In the growth and biomass analysis, the northernmost provenance showed the lowest survival, growth and dry biomass, whereas in the gas exchange analysis, the southern interior provenance showed the highest net photosynthesis, transpiration, stomatal conductance and water use efficiency. The interaction between water regimes and provenance was only significant for diameter and net photosynthesis. These results indicate that different provenances of Q. saponaria show a stable performance across different controlled drought conditions. This information is of relevance for sourcing seeds for the restoration of the species.     

Effect of Initial Full Feeding of Broiler Breeder Pullets on Carcass Development and Body Weight Variation

Broiler breeder pullets are fully fed for several weeks to give chicks a vigorous start, to establish an adequate frame size, and to build increased flock BW uniformity. This study was designed to determine whether reducing the length of the initial ad libitum feeding period of pullets would be detrimental to subsequent fleshing, skeletal development, and BW variation. A total of 720 Ross 308 pullets were placed in 8 pens on the day of hatch and provided ad libitum access to feed at 1 wk (1WK) or 3 wk (3WK) of age, at which time a 5:2 restriction program began. Individual BW and external fleshing scores, and flock BW variation (CV and uniformity) were monitored. At 4, 8, 12, and 16 wk, 60 randomly selected birds per treatment were dissected for assessment of breast muscle, fatness, and reproductive development. At 3 wk of age, BW of the 3WK pullets (471 g) was greater than that of the 1WK pullets (312 g), and the daily rate of gain was double. Although feed allocation was decreased markedly at 3 wk in 3WK birds, by 4 wk they weighed 30% more, and had a greater frame size and proportion of breast muscle than the 1WK birds. At 8 wk of age, the 3WK birds were still heavier (973 g for 3WK vs. 899 g for 1WK). Most carcass measures were similar between treatments at 12 wk of age, by which time BW profiles were similar. At 16 wk of age, frame size and proportion of breast muscle were not different between groups. The BW variation did not differ through the initial 12 wk, but was superior at 14 and 16 wk of age in 1WK birds, possibly because of greater feed allocation between 8 to 16 wk, which is the most intense feed restriction period. The reduced feed intake of 3WK birds at the onset of feed restriction reduced their ME requirement for maintenance, likely contributing to this result. Increasing the length of the ad libitum feed access period after hatch altered growth and conformation traits to 8 wk of age and did not affect frame size or proportion of breast muscle, but increased BW variability late in the rearing period.     

Intestinal microbiota of broilers submitted to feeding restriction and its relationship to hepatic metabolism and fat mass: Fast‐growing strain

The present study was conducted to verify how feed restriction affects gut microbiota and gene hepatic expression in broiler chickens and how these variables are related to body weight gain. For the experiment, 21‐d‐old Cobb500^TM birds were distributed in a completely randomized experimental design with three treatments: T1. Control (ad libitum—3.176 Mcal/kg ME—metabolizable energy—and 19% CP—crude protein); T2. Energetic restriction (2.224 Mcal/kg ME and 19% CP) from 22 to 42 days with consumption equivalent to control; T3. Quantitative restriction (70% restriction, i.e., restricted broilers ingested only 30% of the quantity consumed by the control group—3.176 Mcal/kg ME and 19% CP) for 7 days, followed by refeeding ad libitum from 28 to 42 days. Ileum and caecum microbiota collections were made at 21, 28 and 42 days of age. Hepatic tissue was collected at 28 and 42 days old for relative gene expression analyses. At 43‐d‐old, body composition was quantified by DXA (Dual‐energy X‐ray Absorptiometry). Both feed restriction programmes decreased Lactobacillus and increased Enterococcus and Enterobacteriaceae counts. No differences were found in the refeeding period. Energetic restriction induced the expression of CPT1‐A (Carnitine palmitoyltransferase 1A) gene, and decreased body fat mass. Quantitative feed restriction increased lipogenic and decreased lipolytic gene expression. In the refeeding period, CPT1‐A gene expression was induced, without changing the broilers body composition. Positive associations were found between BWG (Body Weight Gain) and Lactobacillus and Clostridium cluster IV groups, and negatively associations with Enterobacteriaceae and Enterococcus bacterial groups. In conclusion, differences found in microbiota were similar between the two feed restriction programmes, however, hepatic gene expression differences were only found in quantitative restriction. Higher counts of Lactobacillus and Clostridium cluster IV groups in ileum are likely to be related to better broiler performance and low expression of lipogenic genes.     

鸡痘病毒282E4株Bam HI部分片段的重组载体质粒构建与序列分析

在中国鸡痘病毒２８２Ｅ４弱毒株基因组部分ＢａｍＨＩ片段的质粒ｐＵＢ、ｐＵＣ、ｐＵＤ、ｐＵＤ２、ｐＵＥ和ｐＵＦ酶切分析的基础上,对ｐＵＦ进行了亚克隆获得ｐＵＦ－Ｅ和ｐＫＳ－Ｘ,对最可能存在非必需区的ｐＵＥ质粒进行了序列分析,改造了含Ｐ１１Ｐ７．５－ＬａｃＺ报告基因盒,并在上述质粒的相应单一酶切位点插入Ｐ１１Ｐ７．５－ＬａｃＺ报告基因盒,构建成ｐＵＢ１、ｐＵＦＣ１、ｐＵＦＥ１、ｐＵＦ－Ｅ１和ｐＫＳＦ－Ｘ１５个重组载体质粒。体内重组等工作正在进行中。     

花生DNA快速简便提取方法的研究

在花生新鲜针叶和干叶ＤＮＡ提取过程中,应用ｐＨ值较低,无机盐浓度较高的提取缓冲液可沉淀蛋白质,其中加入２％的β－巯基乙醇可有效地防止次生代谢物质使ＤＮＡ变色。提取出的ＤＮＡ样品产率在９２．６～２１６．３１ｎｇ／ｍｇ．ｆｗ,ＤＮＡ质量和纯度较高,２６０ｎｍ／２８０ｎｍ光密度比值在１．８～１．９之间。所得ＤＮＡ可直接用于限制性内切酶酶切,并可用于随机引物ＰＣＲ扩增。该方法为花生分子生物学研究提供基础。     

Growth performance and whole‐body composition of yellow catfish (Pelteobagrus fulvidraco Richardson) under feeding restriction

Fish growth is an important index in aquaculture practice. However, the effect of growth under restricted feeding on quality of fish grown to the same size remains poorly unknown. In this study, yellow catfish were reared by feeding them at three different feeding rates such as low (FR‐L group), medium (FR‐M group) and high (apparent satiation) ration levels for 82, 58 and 34 days to reach the same size, respectively. After this period, the growth performance, whole‐body amino acid composition and fatty acid profile of the fish were evaluated. Feeding restriction led to significant decreases in specific growth rate and feed conversion efficiency. Significant increases in dry matter, protein and energy contents were observed in fish under both restricted feeding treatments. FR‐L‐treated fish had significantly lower whole‐body essential amino acid contents, and significantly higher Ala and non‐essential amino acid contents compared to fish fed to satiation. Fish in restricted feeding treatments had significantly higher n‐3 PUFA and n‐3/n‐6 ratio compared to the fish fed to satiation. The present results indicate that from a quality perspective, there are certain advantages in improvement of whole‐body composition and enrichment of n‐3 PUFA associated with the restricted feeding of yellow catfish at slow growth rate.     

Anabolism,catabolism and proteomic analysis in the slow‐twitch muscle of pacu (Piaractus mesopotamicus) submitted to prolonged fasting followed by refeeding

Here, we aimed to study the slow muscle of the fish Piaractus mesopotamicus submitted to 30 days of fasting (D30) followed by 1 day (D31) or 30 days of refeeding (D60). Histological analysis of fibre diameter was performed in D30 and D60. The gene expression of parvalbumin (pvalb), atrogenes (murf1a, murf1b, mafbx) and anabolic genes (igf‐1, mtor) was analysed using RT‐qPCR in D30, D31 and D60. The proteome was obtained by shotgun proteomics at D30 and D60, and the set of differentially expressed proteins was analysed by bioinformatics. In all experiments, the control was regularly fed fish. The histological analysis showed no changes in muscle fibre diameter. The expression of catabolic and anabolic genes was not changed, except for the downregulation of igf‐1 in D30 and of mafbx in D31. The expression of pvalb was not changed in D30 and D60 but was decreased in D31. The proteomic analysis identified 169 proteins in D30 (24 upregulated and 18 downregulated) and 170 proteins in D60 (17 upregulated and 21 downregulated); many of them were related to energetic metabolism and intracellular Ca²⁺ homoeostasis. Overall, our results indicate that the slow‐twitch muscle presented few changes upon prolonged fasting and refeeding condition.     

我国集体林区林业规模经营的现实分析与实现路径

林业规模经营是我国实现林业现代化发展的一个必要过程。新一轮集体林权制度改革既为发展林业规模经营带来了挑战,但同时也为其创造了必要的条件。文中通过对规模经营相关理论的分析,对我国集体林区发展林业规模经营的现实必要性以及阻碍其发展的制约因素进行探讨,并就其实现路径提出如下建议:创新林地流转机制、培育新型林业规模经营主体、逐步建立健全林业社会化服务体系、把握好林业规模经营的"度",以期为我国林业向规模化、集约化和现代化方向发展提供参考。     

木霉菌REMI突变菌株在降解敌敌畏中的作用

本研究对木霉菌T30野生株和限制性内切酶介导的DNA整合技术(REMI)构建的突变株进行降解敌敌畏能力和最佳条件的研究。结果表明,野生株和几个REMI突变株均能降解有机磷农药敌敌畏,但以突变株TK-3降解活性最高,其降解效率达98％。TK-3突变株降解有机磷农药效率取决于葡萄糖剂量、敌敌畏初始浓度、初始pH等。突变株降解敌敌畏的葡萄糖最佳浓度为1 000 μg/mL,最适pH为7.0,敌敌畏浓度500 μg/mL。敌敌畏浓度超过1 000 μg/mL则会抑制木霉菌降解能力。