Changes in fineroot growth dynamics in response to phosphorus application in an Acacia mangium plantation in Vietnam

Fineroots (≤ 2 mm diameter) are dynamic components of the forest ecosystems and play important role in water and nutrient acquisition in forests. These roots are sensitive to forest fertilization and therefore, the response of fineroots to nutrient application would provide better understanding of the forest carbon and nutrient dynamics that will be helpful in sustainable forest management plans. Two fertilization treatments, including (1) F400: 400 g P₂O₅ (16.5%)/tree and (2) F600: 600 g P₂O₅ /tree, and F0: control (without fertilization), were applied in an Acacia mangium plantation with a planting density of 1100 trees/ha (3 m?×?3 m). The evaluation of fineroot growth across seasons showed that fertilization significantly increased production and subsequent mortality and decomposition. The total decomposition associated with F600 application was 7.95 tons ha^?1 year^?1, equaling 121% of F400 and 160% of the control. Mortality in F600 was 8.75 tons ha^?1 year^?1, equaling 111% of F400 and 198% of F0, while production in F600 was 10.40 tons ha^?1 year^?1, equaling 127% of F400 and 143% of F0. Fineroot production, mortality, and decomposition are seasonally dependent, with higher values measured in the rainy season than in the dry season. Stand basal area increment was significantly correlated with fineroot production (R²?=?0.75), mortality (R²?=?0.44), and decomposition (R²?=?0.48). This study showed that fertilization could facilitate fineroot production, which can then lead to a higher turnover of carbon and nutrients through the decomposition of the greater mass of the fineroots.

     

天然防腐剂在果蔬保鲜涂料中的应用

采用适当的方法从中草药中提取有效成分，并将其与被膜剂复合。针对各种常见水果病菌，采用平板抑菌试验筛选出５种具有显著抑菌能力的药种，进而用最低抑制发育浓度试验比较了各药种对不同病菌的抑制作用，为天然防腐剂在果蔬保鲜涂料中应用提供了依据。     

固始鸡脐带间充质干细胞原代培养及其诱导分化潜能研究

为了研究固始鸡脐带间充质干细胞（umbilical cord mesenchymal stem cells,UCMSCs）的生物学特性和诱导分化,对其进行原代培养及定向诱导分化研究。选取14日龄固始鸡鸡胚的脐带组织,剥离脐带动、静脉,将华通胶部分剪成1 mm³大小,采用胶原酶消化法分离细胞并进行原代培养,观察细胞形态,绘制P3、P9、P15代生长曲线并测定群体倍增时间及克隆形成能力。结果表明,固始鸡UCMSCs形态为长梭形,生长趋势符合Logistic生长曲线规律,呈典型的S形;免疫荧光和RT-PCR结果显示,固始鸡UCMSCs表达CD29、CD44、CD73、CD90、CD166等间充质干细胞表面标记物基因,但不表达原始造血祖细胞标志物CD34和泛白细胞标志物CD45;经特异性染色和RT-PCR表明,体外诱导固始鸡UCMSCs可分化为脂肪、成骨和成软骨细胞。从固始鸡脐带华通胶中分离所获得的UCMSCs具有良好的体外增殖能力和分化潜能,与从其他物种体内分离的UCMSCs具有相似的生物学特征,它们的多项分化能力预示着细胞移植的应用前景,可为再生医学和组织工程学提供新的潜在种子细胞。     

日光温室黄瓜新品种津优33号的选育

津优33号是以优良自交系P4和242杂交而成,植株生长势强,叶片中等大小,深绿色,主蔓结瓜为主;低温(8~10℃)弱光(8000lx)条件下能够正常开花结果,且瓜条生长速度快,坐瓜率高;抗黄瓜霜霉病、白粉病和灰霉病;瓜条长30~32cm,心腔小于瓜横径的1/2,瓜把较短,刺瘤密,瓜条深绿色,有光泽,口感脆嫩,品质好,单瓜质量175g,每667m2产量6000kg左右,适于日光温室越冬栽培。     

Morphology and electrical conductivity of PS/PMMA/SMMA blends filled with carbon black

An alternative strategy to reduce the percolation threshold of carbon black (CB) in polymer blends was investigated using random copolymer ternary blends of polystyrene (PS), poly(methyl methacrylate) (PMMA), and a styrene-methyl methacrylate random copolymer (SMMA). The target morphology was to selectively locate CB particles in the encapsulating layer of SMMA during melt mixing. The CB used in this study is BP-2000 from Cabot and has a strong selective affinity to PS. Even when the CB was premixed with SMMA, it moves to the PS phase during the melt mixing. However, we also observed the CB particles located at the interface between SMMA and PS phases. Through this study it is found that the interaction between polymers and CB particles is critical for selectively localizing CB particles in multi-component polymer blends. Although appropriate processing condition may retard the movement of CB particles to the polymer phase with affinity, it cannot prevent it completely and locate them to the SMMA phase, which is not thermodynamically favored. To locate CB particles in an encapsulating layer of ternary polymer blends, first of all, polymers forming it should have selective affinity to CB.     

Species-specific responses to environmental stress on germination and juvenile growth of two Bolivian Andean agroforestry species

Integrating native trees in farmland can support soil, water and biodiversity conservation. This is particularly important in regions characterized by long periods of drought and soil erosion, such as the Bolivian Andes, where agroforestry with native woody species is rarely applied. Better knowledge on the effects of environmental stress on propagation and establishment of such native plants is needed to optimize their cultivation. In our study, we tested the effects of temperature and scarification on seed germination, and assessed seedling survival and juvenile growth of two potential agroforestry species (Prosopis laevigata var. andicola, Schinus molle) under diverse soil and water conditions. Temperatures above 30 °C accelerated germination, but they increased fungi infestation in the case of S. molle. The application of acid and mechanical scarification significantly improved the germination capacity of P. laevigata var. andicola. Medium to high moisture levels in sand provided the most favourable conditions for plant growth. S. molle was more sensitive to dry and P. laevigata var. andicola more vulnerable to water-saturated clay loam. Mulching enhanced the survival and growth of S. molle juveniles, but increased P. laevigata var. andicola’s growth in sand and dry soils only. Our results may facilitate guidance on improving propagation of these two potential agroforestry species under environmental stress conditions. More generally, our study shows that easily applicable treatments, such as mulching, can significantly improve the cultivation of native species, provided that their habitat requirements and limiting factors are well known. This highlights the relevance of identifying and closing such knowledge gaps for native trees and shrubs in order to promote their potential for use in agroforestry.     

Effects of milk replacer and starter diet provided as creep feed for suckling pigs on pre‐ and post‐weaning growth

This study was aimed at investigating the long‐term effects of provision of liquid milk replacer (MR) and solid starter diet (SD) during lactation on post‐weaning (PW) growth of pigs. In experiment 1, 33 cross‐bred litters were allotted to four treatments: no supplement (CON), MR ad libitum, SD ad libitum and 100 g SD/litter/day from lactation day 4 through weaning at day 21 during late fall. In experiment 2, 40 litters received MR or none in July. PW pigs received commercial diets to marketing. In experiment 1, weaning weight (WW), pre‐weaning average daily gain (ADG) and mortality (2.4%) were not influenced by creep‐feeding MR or SD. ADG was greater (P < 0.05) in the MR group versus CON during days 21–54, but did not differ across the treatments during days 54–162. In experiment 2, ADG during lactation and WW were greater in the MR group versus CON, with mortality lower in the former (5.6 vs. 10.3%). However, PW ADG to day 175 did not differ between the two groups. Results suggest that creep‐feeding MR or SD has no effect on PW growth. However, it remains possible that MR reduces PW mortality during the hot season.     

Innate immune homeostasis by the homeobox gene caudal and commensal-gut mutualism in Drosophila

Although commensalism with gut microbiota exists in all metazoans, the host factors that maintain this homeostatic relationship remain largely unknown. We show that the intestinal homeobox gene Caudal regulates the commensal-gut mutualism by repressing nuclear factor kappa B-dependent antimicrobial peptide genes. Inhibition of Caudal expression in flies via RNA interference led to overexpression of antimicrobial peptides, which in turn altered the commensal population within the intestine. In particular, the dominance of one gut microbe, Gluconobacter sp. strain EW707, eventually led to gut cell apoptosis and host mortality. However, restoration of a healthy microbiota community and normal host survival in the Caudal-RNAi flies was achieved by reintroduction of the Caudal gene. These results reveal that a specific genetic deficiency within a host can profoundly influence the gut commensal microbial community and host physiology.