Viral co‐infections in farmed Atlantic salmon,Salmo salar L., displaying myocarditis

Several different viruses have been associated with myocarditis‐related diseases in the Atlantic salmon aquaculture industry. In this study, we investigated the presence of PMCV, SAV, PRV and the recently identified Atlantic salmon calicivirus (ASCV), alone and as co‐infections in farmed Atlantic salmon displaying myocarditis. The analyses were performed at the individual level and comprised qPCR and histopathological examination of 397 salmon from 25 farms along the Norwegian coast. The samples were collected in 2009 and 2010, 5–22 months post‐sea transfer. The study documented multiple causes of myocarditis and revealed co‐infections including individual fish infected with all four viruses. There was an overall correlation between lesions characteristic of CMS and PD and the presence of PMCV and SAV, respectively. Although PRV was ubiquitously present, high viral loads were with a few exceptions, correlated with lesions characteristic of HSMI. ASCV did not seem to have any impact on myocardial infection by PMCV, SAV or PRV. qPCR indicated a negative correlation between PMCV and SAV viral loads. Co‐infections result in mixed and atypical pathological changes which pose a challenge for disease diagnostic work.     

Effects of salinity on osmoregulation,growth and survival in Asian swamp eel (Monopterus albus) (Zuiew 1793)

The Asian swamp eel Monopterus albus is normally considered a freshwater species, but can also occasionally be found in brackish water. It is an obligate air‐breather with highly reduced gills, making its osmoregulation physiology interesting because the gills normally represent the primary site of osmoregulation in teleosts. Being a popular fish for human consumption, the swamp eel is cultured extensively in freshwater ponds in the Mekong Delta of Vietnam. However, very little is known about its salinity tolerance, which is becoming topical due to the increasing salt‐water intrusions into tropical deltas. We therefore studied how increased salinity affects survival, growth, blood pressure, heart rate, blood osmolality and plasma ions. All eels survived prolonged exposure to 5 and 10 g L^?1, although plasma osmolality increased significantly at 10 g L^?1. Further elevation to 15 and 20 g L^?1 was associated with significantly elevated mortality, with a corresponding increase in plasma osmolality and ion con‐centrations. Our results show that swamp eels thrive in 0–10 g L^?1 with an optimum growth between 0 and 9 g L^?1, indicating that utilization of low saline brackish waters for aquaculture is possible.     

Watermelon lycopene β-cyclase: promoter characterization leads to the development of a PCR marker for allelic selection

In the carotenoid biosynthetic pathway, lycopene β-cyclase (LCYB) catalyzes the cyclization that converts lycopene into β-carotene. Only a single copy of LCYB was identified and was suggested to encode a chromoplast-specific LCYB (CYCB type) in watermelon [Citrullus lanatus (Thunb.), Matsum & Nakai]. Splicing variants in the 5′-untranslated region were identified, but alternative splicing did not provide an explanation of the regulation of carotenoid accumulation in watermelon flesh. A quantitative assay using real time-PCR showed that differential expression was not detected between red- and canary yellow-fleshed watermelon cultivars. LCYB promoter regions were isolated and characterized, and a sequence difference was identified in the promoter region between red and canary yellow LCYB alleles. This polymorphism did not change the expression of LCYB, but does provide a reliable marker for discriminating LCYB alleles for red and canary yellow flesh. To develop a PCR-based marker to distinguish between the two LCYB alleles, we designed primers flanking the polymorphic region. The newly developed marker, designated Clcyb.600, co-segregated perfectly with flesh color phenotypes and single nucleotide polymorphism (SNP) markers developed in our previous study. Moreover, the Clcyb.600 marker offers easier discrimination of LCYB alleles than SNP or cleaved amplified polymorphic sequence markers, as it does not require restriction enzyme digestion for genotyping. Genotyping of LCYB promoter alleles in various commercial cultivars and plant introductions indicated that watermelon cultivars can be classified into two groups, those carrying a red LCYB allele or a canary yellow LCYB allele.     

玛纳斯河流域下游土壤的盐分特征分析

[目的]了解玛纳斯河下游土壤的盐渍化类型及盐分特征,为该地区土壤盐渍化治理及发展提供科学依据.[方法]以冲积洪积扇缘的142团和冲积平原的121团为例,依照Cl<'->/SO<,4><'2->的当量比对两种地貌的土壤进行分类,并利用SPSS13.0软件对土壤可溶性离子进行统计及相关性分析.[结果]两种地貌的土壤盐分在表层存在差异,142团0～40 cm属氯化物-硫酸盐或硫酸盐-氯化物类型,121团则属于氯化物类型.两种土壤的含水率都随土层深度的增加而增加,电导率则相反.通过对各离子变异系数的比较发现,属于强变异性的有142团的CO<,3><'2->与Cl<'->,以及121团的CO<,3><'2->;两种地貌土壤pH变异系数都低于10;,属于弱变异性;其他离子变异系数都为中等变异.142团的土壤可溶性盐与土壤含水率关系密切,121团则与土壤pH的关系较为紧密.[结论]玛纳斯河冲积扇扇缘至冲积平原的表层土壤盐分是由氯化物-硫酸盐为主过渡至氯化物为主.不同地貌下的土壤含水率、pH以及可溶性盐分离子之间确实存在着不同程度的差异性与相关性.     

干旱区滴灌棉田冻融季土壤水热盐分布规律研究

[目的]研究滴灌棉田冻融期及其前后水热盐分布规律.[方法]实验以野外实测和室内试验数据为基础,分析水热盐在干旱区滴灌棉田冻融季土壤各层中分布特征.[结果]表层土壤11月下旬开始冻结,到翌年2月上旬达到最大冻结深度,4月上旬土壤完全融通,冻融期5 cm深处土壤温度变幅为19.95℃,170 cm深处变幅为10.25℃;0～60 cm土层2009年11月29日～2010年2月11日含水量和含盐量冻结过程中都呈上升趋势,2010年2月11日～4月21日为融化期,土壤垂直含水量和含盐量分布表现出复杂的变化方式,60～200 cm土壤水盐垂直分布变化不大;土壤水分与盐分时间变异特征表现为:冻融期土壤表层变异性大于底层,0～80cm水分变异程度大于盐分,80～200 cm水盐变异系数差异不大,变异性低.[结论]为冻融季土壤水热盐分布进一步研究提供参考,对盐渍土的改良、农业灌溉等相关问题的研究有一定参考价值.     

主养草鱼池塘三种混养模式鱼类生长和效益的比较

为进一步提高我国广大池塘养鱼的产品质量、经济效益和改善其生态环境。本试验在武汉新洲973项目实验基地9个陆基鱼池中进行了三种不同混养模式鱼类生长和效益的比较研究,每种模式设3个重复。模式Ⅰ中放养草鱼、鲢、鳙和高背鲫;模式Ⅱ中放养草鱼、鲢、鳙、匙吻鲟和高背鲫;模式Ⅲ中放养草鱼、鲢和高背鲫。 结果表明：通过122d的养殖试验,模式Ⅱ中草鱼的生长不仅显著高于模式Ⅰ和模式Ⅲ（P<0.05）,而且其经济效益模式Ⅱ同样高于模式Ⅰ和模式Ⅲ。     

Interspecific and intergeneric hybridization and chromosomal engineering of Brassicaceae crops

In Brassicaceae crop breeding programs, wild relatives have been evaluated as genetic resources to develop new cultivars with biotic and abiotic stress resistance. This has become necessary because of the diversification of ecotypes of diseases and pests, changing food preferences, advances in production technology, the use of new approaches such as in vitro breeding programs, and the need for economical production of F₁ seed. To produce potential new cultivars, interspecific and intergeneric hybridizations have been performed between cultivated species and between cultivated species and their wild relatives. Furthermore, interspecific and intergeneric hybrids have been successfully produced using embryo rescue techniques. In this paper, we review the interspecific and intergeneric incompatibilities between Brassicaceae crops and their wild relatives, and the production, characterization, and improvement of synthetic amphidiploid lines, alien gene introgression lines, alloplasmic lines, monosomic alien chromosome addition lines, and monosomic alien chromosome substitution lines. The goal is to provide useful materials to support practical breeding strategies and to study the genetic effects of individual chromosomes on plant traits, the number of genes that control a trait, their linkage relationships, and genetic improvement in Brassicaceae crops.     

恩施州耕地土壤剖面理化特征及养分分布变化规律

对恩施州利川市齐岳山蔬菜、汪营粮食、恩施市芭蕉茶叶基地等3个观测点土壤剖面的理化特征及养分分布规律进行了研究。3个观测点土壤容重在1.23～1.43 g/cm3之间,为壤土或砂壤土;电导率23.57～38.83μS/cm,无盐碱化;pH 4.22～6.61,偏酸性或强酸性;有机质12.97～52.88 g/kg、铵态氮16.09～31.72 mg/kg、有效磷1.59～185.56mg/kg、速效钾0～131.03 mg/kg;总硒0.30～1.32 mg/kg,有效硒0.02～0.23 mg/kg,属富硒土壤。剖面有效养分从表层到底层呈下降趋势,绝对系数R2在0.132 9～0.939 9之间,不同养分差异大,剖面间分布规律基本一致。该项研究是土壤质量长期监测的基础工作,目的是监测不同施肥方式对蔬菜、粮食、茶叶基地土壤质量变化的影响,为修复土壤、提高农产品质量提供参考。     

黄芩栽培技术

黄芩(Scutellaria baicalensis Genorgi),为唇形科黄芩属植物,黑龙江大部分地区均有分布,质量较好。但人工栽培在黑龙江省发展较慢,仅有少量种植,为适应林区经济发展,应大力推广在林下栽培经济植物黄芩。