Research on abalone (Haliotis midae L.) cultivation in South Africa

Although abalone fisheries in South Africa have existed since 1949, cultivation started by successful spawning of captured specimens in 1981 to produce spat and juveniles. Twelve abalone farms, with an estimated investment of US$12 million, have since been established on the coast of South Africa, with a projected production of 500–800 tons. While Haliotis midae could reach a maximum size of about 200 mm shell length at an age of over 30 years in the wild, farm production is concentrating on an average size of 100 mm after 5 years. Growth rates of 0.08–4.5% body weight day ^?1 for abalone of 10–17 mm shell length have been found under stimulated farming conditions on formulated diets, while the corresponding feed conversion ratio (FCR) was 0.9–2.4. Growth rate, FCR and protein efficiency ratio decline at water temperatures above 20 °C. Anaesthetics, for example magnesium sulphate, are used to prevent injury during removal from tanks. Prostrate diatoms, such as Cocconeis sublittoralis (Hendey), Amphora proteoides (Hustedt) and Achnanthes brevipes (Agardh) are preferred after the larval stage (5–7 days, depending on temperature) are finished. South Africa abalone growers prefer formulated feeds in pellet form, which is convenience and cost favourable to farm operations and management. Although fish meal has been found to be the most suitable protein source for inclusion in formulated diets, plant proteins such as soy bean meal, cottonseed meal and sunflower meal presented good growth and apparent protein digestibility. The parasite sabellid polychaete, Terebrasabella heterouncinata, recently named by Australian and American researchers, is indigenous to a variety of South African intertidal molluscs and impedes growth by causing irritation beneath the mantle in abalone. Prevention to some degree is possible by high standards of hygiene and husbandry of abalone in the tanks, but new techniques to control large infestations now include ultrasound. In spite of a reputation for toughness, abalone meat frozen immediately after shucking is tender relative to red meat. The success of abalone farming in South Africa has been as a result of a high degree of cooperation between the private sector and government‐backed research institutions, and it is anticipated that this collaboration will continue.     

非洲黑鸵鸟人工饲养条件下繁殖性能的观察

14只2岁非洲黑鸵鸟按公母比例1:2～3分成4个繁殖组合,对产蛋、受精、孵化情况进行观察分析。结果显示,每只母鸵鸟年平均产蛋量为55.2枚,最高约为73枚,最低为39枚。4个组合鸟群之间种蛋的受精率存在显著的差异P<0.01,I组的受精率最高,为59.6%;IV组的受精率最低,仅8.9%。各组的受精率、孵化率差异不显著P>0.05,平均受精蛋孵化率达到92.6%。本次受精率较低的原因为公鸟年龄小,没有完全达到性成熟。     

2016/2017冬中国气温偏暖的基本特征及可能成因

利用中国740余站观测的月平均2 m气温资料以及NCEP/NCAR再分析资料,通过动力学诊断的方法,对2016—2017年中国冬季异常偏暖现象进行了研究。结果发现：中国2016—2017年冬季气温偏暖主要是由于西伯利亚高压和阿留申低压偏弱导致东亚冬季风偏弱,在中国存在异常的偏南风。阿留申低压偏弱由两个因素引起,一是由于阿留申群岛地区的海温偏低,冷源对应异常高压导致阿留申低压偏弱;二是阿留申低压在东亚副热带高空西风急流出口区以北,然而该冬季高空西风急流出口区位置偏南,导致阿留申地区偏离急流出口减压区,从而导致阿留申低压偏弱。此外,西风带偏北,中高纬亚洲大陆上空以纬向环流为主,不利于冷空气南下。     

援非农业技术示范中心可持续发展途径思考

中国援非农业技术示范中心陆续完成技术合作阶段,并逐步进入可持续发展期。顺利完成这个过渡期,需要前期大量的准备工作,如:中心选址、项目内容确定、专家遴选、项目设计及认真的实施过程等。     

Genotype-by-environment interaction analysis of rice (Oryza spp.) yield in a floodplain ecosystem in West Africa

West Africa has large areas of river floodplains, most of which are not currently used for farmland. Rice (Oryza spp.) is a promising crop for farming in floodplains because of its high adaptability to a wide range of water environments. On the other hand, there is great variation in soil fertility and water availability even in a small area within a floodplain. Hence, we evaluated 27 rice genotypes in four fields in three years in a floodplain of the Northern Region of Ghana to investigate genotype × environment (G × E) interactions for rice yield and to identify stable, high-yielding genotypes. The genotypes consisted of O. sativa, O. glaberrima and New Rice for Africa (NERICA), and many were selected for their reported submergence resistance because of the anticipated submergence damage in the floodplain. There were large variations in yield, which ranged from 0.14 to 5.35 t ha⁻¹ depending on the location within a floodplain, genotype and year, and there were significant genotype, environment and G × E interaction effects on yield, accounting for 24.8%, 20.2%, and 28.2%, respectively, of the total variation. The results suggested that selection of suitable location with high soil fertility and low risk of submergence is necessary to achieve high yield in a floodplain. In addition, early sowing would be effective high-yielding crop management, which reduced the risk of submergence-induced damage just after sowing and secured sufficient growth duration to achieve high yield. Genotype IR42 showed the highest average yield among environments, but its yield stability was low. On the other hand, several genotypes including Amankwatia, a local aromatic cultivar adapted to irrigated and lowland environments, and IRBL9-W[RL], a blast-tolerant variety containing the Sub1 gene for submergence tolerance, showed high, stable yield. To put these results to practical use in other floodplain areas in West Africa, physiological mechanisms causing G × E interaction for rice yield should be further studied.     

东佛里生羊MSTN基因多态性及其与生长性状的关联分析

试验旨在研究肌肉生长抑制素(myostatin,MSTN)基因多态性及其对东佛里生羊生长性状的影响。从324只东佛里生羊全血中提取DNA,对MSTN基因外显子序列和非翻译区(untranslated region,UTR)序列进行PCR扩增,采用一代测序技术鉴定单核苷酸多态性(single nucleotide polymorphism,SNP)位点,分析不同位点的遗传多态性,并将不同基因型与东佛里生羊的生长性状进行关联分析。结果显示,在东佛里生羊MSTN基因外显子中未检测到突变;在3'-UTR区的272 bp处存在G→A单碱基突变,该位点只检测到AG和AA基因型,且AA基因型频率高于AG基因型;在5'-UTR区的176 bp处存在C→A突变,该位点只检测到CC和AC基因型,且CC基因型频率高于AC基因型。遗传多样性参数分析结果表明,东佛里生羊群体MSTN基因3'-UTR-272和5'-UTR-176位点的纯合度分别为0.827和0.887,杂合度分别为0.173和0.113,2个位点的多态性均较低(PIC<0.25),其群体基因型分布均符合哈代-温伯格平衡(P>0.05)。关联分析发现,3'-UTR-272位点AG基因型体斜长显著高于AA基因型(P<0.05),5'-UTR-176位点CC基因型胸围显著高于AC基因型(P<0.05),其余指标均无显著差异(P>0.05)。综上,东佛里生羊MSTN基因3'-UTR和5'-UTR突变位点可作为其目标性状选育的分子标记。     

Stress steroid levels and the short-term impact of routine dehorning in female southern white rhinoceroses (Ceratotherium simum simum)

Rhinoceros populations in Africa are under severe threat as a result of surging poaching rates and risk-mitigation strategies are continuously adapted in an attempt to ensure the survival of the species. This study compared faecal glucocorticoid metabolite (fGCM) levels of two age classes of limited free-ranging female white rhinos with fGCM levels of adult free-ranging female white rhinos. Subsequently, fGCM alterations in the limited free-ranging animals were monitored following routine dehorning as a measure of the animals’ short-term physiological stress response. Baseline fGCM levels differed significantly between tested groups, with both free-ranging and limited free-ranging adult animals showing significantly higher fGCM levels compared with limited free-ranging juvenile females. In contrast, baseline fGCM levels did not differ significantly between limited free-ranging and free-ranging adult individuals. Routine dehorning procedures resulted in a short-term stress response expressed by a significant increase in fGCM levels 48 h post-dehorning, with stress steroid levels returning to pre-dehorning concentrations 72 h after the procedure.     

Do public attitudes affect conservation effort? Using a questionnaire-based survey to assess perceptions,beliefs and superstitions associated with frogs in South Africa

Globally, amphibians are among the least appreciated vertebrates and are often negatively perceived by the general public. Such attitudes are particularly prevalent in South Africa, where fear, superstitions and myths associated with frogs are pervasive in some cultures. These attitudes could have harmful consequences both for the animals concerned and conservation efforts. This study aimed to investigate attitudes to frogs throughout South Africa across multiple age and ethnic groups. We used a multi-language survey in both hard-copy and online versions. Respondents (n = 2 295) comprised both genders across six age groups and five ethnic groups. A functionalist approach using structural equation modelling was used to assess how liking of frogs and cultural beliefs varied with socio-demographic factors. Attitudes varied significantly between groups, with males more likely to like frogs than females and age and level of education also significantly linked to liking. The influence of cultural beliefs and lack of knowledge also directly influenced negative attitudes towards frogs. More than 60% of respondents expressed an interest in learning more about frogs, indicating an opportunity for improving attitudes through educational outreach. The findings of this study can be used to inform current efforts to protect amphibians in South Africa through social interventions.     

华南三省(自治区)部分西番莲种植区花叶病病原检测及EAPV多聚蛋白基因序列分析

<正>西番莲(Passiflora edulis Sims.)是热带亚热带地区重要经济作物,我国福建、广东、广西、海南等地广泛种植[1]。调查发现,我国南方多地西番莲花叶病为害严重,症状表现为叶片花叶、黄化、斑驳、畸形,甚至整株褪绿,严重影响西番莲的产量和品质。已报道能引起西番莲花叶症状的病毒有：黄瓜花叶病毒属(Cucumovirus)的黄瓜花叶病毒(cucumber mosaic virus, CMV),