短蛸外套膜和足甲硫氨酸脑啡肽的免疫组织化学定位

采用免疫组织化学SABC法对短蛸外套膜和足中甲硫氨酸脑啡肽(met-Enk)进行定位研究。试验结果表明,短蛸外套膜、腕、腕间膜、漏斗中均有met-Enk存在,外套膜背面、腕和腕间膜上皮组织及其附近的部分细胞和神经纤维呈met-Enk强阳性或阳性;外套膜腹面和漏斗上皮组织及其附近的部分细胞和神经纤维呈met-Enk阳性或弱阳性。met-Enk在短蛸外套膜和足不同部位分布密度的不同,可能与各部位的功能不同有关。     

Use of Chlorella vulgaris as a carotenoid source for rainbow trout: effect of dietary lipid content on pigmentation, digestibility and retention in the muscle tissue

Apparent digestibility, deposition and retention of carotenoids in the muscle of rainbow trout, Oncorhynchus mykiss, were investigated comparing the feeding of pigments from Chlorella vulgaris against commercially available pigments at two different total lipid contents (15% and 20% lipid). Algal biomass (ALG) was included in rainbow trout diets and muscle pigmentation was compared to that obtained in trout fed diets containing a 5:3 mixture of canthaxanthin and astaxanthin (MIX) (reflecting the relative concentrations of these carotenoids in the dry alga) or those fed a diet containing astaxanthin only (AST). Apparent digestibilities of pigments and nutrients were determined by the indirect method, using Cr2 O3 as indicator, and the colour intensity and pigment concentration were assessed in the muscle, using the Roche colour card for salmonids and UV-vis spectrophotometry. After 6 weeks feeding, colour intensity was similar for the various pigment sources, achieving levels 12 to 13, yet significantly higher in fish fed the diet with the higher lipid content ( 20%) (p<0.05). Pigment concentration in the muscle was also higher in the fish fed the high-fat diet. Muscle pigment concentrations were similar for fish fed diets ALG and MIX, and over 1.5 times higher than for diet AST (p<0.05) after 6 weeks. Apparent digestibility of dry matter, crude protein, lipid, total energy and specific carotenoid concentrations were also measured. Increased dietary fat content was shown to increase the deposition and the retention of carotenoids in muscle, and the difference increased with time (deposition increase of 10–20% at week 3 and 30–40% at week 6 and retention increase of 10–15% at week 3 and 30% at week 6). Pigment digestibility also apparently increases (10–20%) under those conditions despite the fact that no significant effects in terms of apparent digestibility increase were found for dry matter, protein, lipids or energy. © Rapid Science Ltd. 1998     

营养元素对小球藻生长及胞内蛋白质和多糖含量的影响

在24～26℃、自然光照的条件下,首先考察小球藻生长与胞内蛋白质和多糖积累的关系,其次利用正交设计实验考察不同浓度的营养元素对小球藻生长及胞内蛋白质和多糖含量的影响。结果表明,小球藻中蛋白质和多糖的合成与积累主要发生在生长过程的平衡期。实验的目标不同,所需要的营养元素浓度及其优化组合不同。利于小球藻生长、胞内蛋白质和多糖积累的营养元素的优化组合分别为:C6H12O6:2g/L;KNO3:0.8g/L;NaH2PO4:0.2 g/L;C6H12O6:10 g/L;KNO3:1.6 g/L;NaH2PO4:0.2 g/L;C6H12O6:6 g/L;KNO3:1.6g/L;NaH2PO4:0.1g/L。与之对应的细胞密度、蛋白质和总糖含量分别为:6.46×107个细胞/L,655.4 mg/g,168.1mg/g。     

干旱胁迫条件下臭柏的生长

为了探讨干旱胁迫条件下臭柏(Sabina vulgaris Ant)的生长特性及适应机理，进行了长期的野外调查和室内模拟实验。野外调查是在毛乌素沙地的天然臭柏分布区，设置固定样方，定期测定样方内立地条件不同的24个臭柏群落。室内实验是将臭柏插穗带往日本冈山大学扦插，生根扦插苗移植于砾耕栽培装置中，设置对照区，弱干旱胁迫区，强干旱胁迫区(培养液渗透势分别为0 MPa，-0．1MPa和-0．3MPa)3种处理进行长期的干旱胁迫室内模拟实验，研究各处理区臭柏的生长变化规律。结果表明：(1)毛乌素沙地的天然臭柏群落的半径以每年约11cm的速度逐渐扩大，随着干旱胁迫的加剧，群落的半径生长量及最大树高都减少；(2)室内干旱胁迫条件下，臭柏的伸长生长和地径生长逐渐减少，而且伸长生长优先受到抑制。     

西瓜果实可溶性固形物含量配合力测定分析

试验结果表明:西瓜果实可溶性固形物含量,一般配合力和特殊配合力均较高的B_2(SO4自交系)、B_4(石红2号自交系)是提高西瓜甜度育种较为理想的亲本。在十五个杂交组合中,B_2(SO4自交系)×B_6(兴城红自交系)F_1,B_3(富研自交系)×B_4(石红2号自交系)F_1特殊配合力最高,是提高果实甜度较为理想的杂交组合。     

Invasive slug populations (Arion vulgaris) as potential vectors for Clostridium botulinum

Background

Norwegian meadows, including those for silage production, are recently found heavily invaded by the slug Arion vulgaris in exposed areas. As a consequence, large numbers of slugs might contaminate grass silage and cause a possible threat to animal feed quality and safety. It is well known that silage contaminated by mammalian or avian carcasses can lead to severe outbreaks of botulism among livestock. Invertebrates, especially fly-larvae (Diptera), are considered important in the transfer of Clostridium botulinum type C and its toxins among birds in wetlands. C. botulinum form highly resistant spores that could easily be consumed by the slugs during feeding. This study aimed to determine whether Arion vulgaris could hold viable C. botulinum and enrich them, which is essential knowledge for assessing the risk of botulism from slug-contaminated silage. Slug carcasses, slug feces and live slugs were tested by a quantitative real-time PCR (qPCR) method after being fed ≅ 5.8 × 10⁴ CFU C. botulinum type C spores/slug.

Results

Low amounts of C. botulinum were detected by qPCR in six of 21 slug carcasses with an even spread throughout the 17 day long experiment. Declining amounts of C. botulinum were excreted in slug feces up to day four after the inoculated feed was given. C. botulinum was only quantified the first two days in the sampling of live slugs. The viability of C. botulinum was confirmed for all three sample types (slug carcasses, slug feces and live slugs) by visible growth in enrichment media combined with obtaining a higher quantification cycle (Cq) value than from the non-enriched samples.

Conclusions

Neither dead nor live invasive Arion vulgaris slugs were shown to enrich Clostridium botulinum containing the neurotoxin type C gene in this study. Slugs excreted viable C. botulinum in their feces up to day four, but in rapidly decreasing numbers. Arion vulgaris appear not to support enrichment of C. botulinum type C.     

蛇口腔炎病原菌的分离与鉴定

从眼镜蛇、榕蛇、水律蛇和广蛇的口腔溃烂处以及肝、肺分离到两种细菌，经致病性试验，证实这两种细菌都具有致病性。根据形态、生长特征和生化特性，8株被鉴定为变形菌属的普通变形杆菌，6株被定为摩根氏菌属的摩根氏菌。药敏试验结果表明，普通变形杆菌和摩根氏菌均对菌必治、呋喃妥因、头孢他啶、环丙沙星敏感。采取以菌必治为主，配合环丙沙星和头孢他啶的治疗方案，总的治愈率达70．6％。     

保水肥、液态地膜对仁用杏土壤水分和生长的影响

为了促进半干旱风沙区仁用杏的抗旱造林,通过田间试验,比较研究保水肥、液态地膜对仁用杏土壤水分和生长的影响。结果表明:保水肥、液态地膜同时使用,在短期就可以明显提高土壤含水量,增加树木生长量。     

Potassium efficiency mechanisms of wheat,barley, and sugar beet grown on a K fixing soil under controlled conditions

Plant species differ in their potassium (K) efficiency, but the mechanisms are not clearly documented and understood. Therefore, K efficiency of spring wheat, spring barley, and sugar beet was studied under controlled conditions on a K fixing sandy clay loam. The effect of four K concentrations in soil solution ranging from low (5 and 20 μM K) to high (2.65 and 10 mM K) on plant growth and K uptake was investigated at 3 harvest dates (14, 21, and 31 days after sowing). The following parameters were determined: shoot dry matter (DM), K concentration in shoot dry matter, root length (RL), root length/shoot weight ratio (RSR), shoot growth rate/average root length ratio (GR_s/aRL), K influx, and soil solution K concentrations. Wheat proved to have a higher agronomic K efficiency than barley and sugar beet, indicated by a greater relative yield under K‐deficient conditions. As compared to both cereals, sugar beet was characterized by higher K concentrations in the shoot dry matter, only 30—50 % of the root length, 15—30 % of the RSR and a 3 to 6 times higher GR_s/aRL. This means that the shoot of sugar beet had a 3 to 6 times higher K demand per unit root length. Even at low K concentrations in the soil solution, sugar beet had a 7 to 10 times higher K influx than the cereals, indicating that sugar beet was more effective in removing low available soil K. Wheat and barley were characterized by slow shoot growth, low internal K requirement, i.e. high K utilization efficiency, and high RSR, resulting in a low K demand per unit root length. At low soil K concentrations, both cereals increased K influx with age, an indication of adaptation to K deficiency. The mechanism of this adaptation merits closer investigation. Model calculations were performed to estimate the K concentration difference between the bulk soil and the root surface (ΔC_L) needed to drive the measured K influx. For the two cereals, the calculated ΔC_L was smaller than the K concentration in the soil solution, but for sugar beet, ΔC_L was up to seven times higher. This indicates that sugar beet was able to mobilize K in the rhizosphere, but the mechanisms responsible for this mobilization remain to be studied.