Humic substances

GOALS, SCOPE AND BACKGROUND: Changing environmental conditions and handling stress are well known to cause chronic or acute stress situations in fish with subsequent infections. These requires a therapy by means of antibiotics and chemicals. In contrast to the huge number of pathogens, only a few substances are permitted for application as therapeutics in German aquaculture. Hence, there emerges an urgent need for highly effective and residueless alternatives. MAIN FEATURES: The prophylactic stimulation and training of the defense system of fish by alternative approaches becomes increasingly necessary. One approach is the application of dissolved humic substances (HS) of natural or artificial origin. For example, there exist several reports on the positive effect of HS to fishes. These effects shall be considered in detail. Furthermore, the impact of HS on the constitution of parasites and pathogens will be displayed. The reports on this issue are diverse, if not inconsistent. We try to shed some light on these discrepancies. The last aspect covered by this review is the outdated paradigm that calcium ions act as antidotes. In the presence of HS, even the opposite effect may occur. APPROACH: To overcome old paradigms on HS and their potential interactions with fish and fish parasites, we reviewed recent international literature, as well as 'grey' literature. We also include results from own former and ongoing studies. RESULTS AND DISCUSSION: HS are able to increase the physiological condition of the individuals and to reduce adverse physiological and histological consequences caused by stress; the mechanism behind remains obscure. HS detoxify heavy metals and organic pollutants. Damages caused by several fish pathogens, such as bacteria and parasites, can be repaired more quickly in the presence of HS. Some parasites--mainly fungi--appear to be directly affected by HS. Comparing the fungicidal effects of HS from various sources, evidence is increasing that the aliphatic moiety may be the effective structures. However, further research is necessary to relate more physiological and anti-pathogenic effects to the chemical characteristics of HS. CONCLUSIONS: HS are not real alternatives to strong traditional therapeutics. However, they show different advantages in repairing secondary, stress induced damages in fish. The ecophysiological relevance of HS in either aquatic systems or aquaculture is getting conspicuously. PERSPECTIVES: The lack of therapeutic and antiparasitic substances in aquaculture requires new strategies and ways of thinking. The search for alternatives to the 'traditional' chemical therapeutics calls for the intensive research. Inevitably, this search will lead to an intensive contemplation on HS as 'health promoting substances' and/or even therapeutics. Basic research is needed to detect the functional groups of the HS responsible for the effects observed. Health promoting effects of first investigations made in vitro to affect pathogens via application of HS and several field studies with HS raises hopes for a broader utilisation of HS to reduce stress consequences in fish and fish pathogens residuelessly.     

紫外诱变选育高效降酚微生物

用紫外线作为诱变剂,处理由燕化炼油厂污水厂的活性污泥中驯化筛选得到的降酚菌株,好氧条件筛选出2种高效降酚微生物QH2、QH3,分别为紫外线照射2min和3min。通过正交实验可知,温度对QH2、QH3生长影响有非常显著的意义P<0.01,在30℃时生长良好。应用QH2、QH3菌种处理炼油厂含酚废水,菌种能够有效降解较为复杂的含酚污水,且QH2菌种处理效果最佳。     

Multi-locus DNA fingerprinting supports genetic monogamy in Florida scrub-jays

Extensive behavioural and pedigree data on a colour-marked population of Florida scrub-jays (Aphelocoma coerulescens) suggested that this cooperatively breeding species is monogamous, with extremely rare exceptions in which males have two mates. We used multi-locus DNA fingerprinting to test these observations by determining genetic parentage. Despite restricted dispersal and high relatedness between behavioural parents and non-breeding members of the group, DNA fingerprints provided sufficient variability to determine parentage unambiguously in almost all cases. We found no evidence of extra-pair fertilisation of females or egg dumping, and confirmed a suspected case of polygyny in which a mother and daughter laid and incubated in the same nest. Our results confirm that detailed behavioural data allow accurate assignment of genetic parentage in this species. In Florida scrub-jays, large territory size may limit opportunities for cuckoldry, and persistent intense competition for limited breeding space may lead to low variance in the quality of established male breeders. These factors would reduce both the opportunity for, and benefits of engaging in extra-pair fertilisations. Delayed dispersal and cooperative breeding in this species have not evolved as avenues for direct reproduction by unpaired individuals. Received: 25 May 1998 / Accepted after revision: 26 June 1998     

微生物苯丙氨酸解氨酶(PAL)/肉桂酸途径生物转化制L-苯丙氨酸酶源菌种选育

Ｌ苯丙氨酸（Ｌｐｈｅｎｙｌａｌａｎｉｎｅ,ＬＰｈｅ）是生化营养的必需氨基酸之一,作为临床医药用氨基酸输液、食品、饲料添加剂的必需成份和一些抗癌药物苯丙氨酸氮芥、甲酰溶肉瘤素等合成的中间体而得到广泛应用．自１９６５年天冬甜肽（Ａｓｐａｒｔａｍｅ,ＡＰＭ,阿斯巴甜）发现并开发生产以来,这一新型甜味剂日渐风行,导致对高光学纯度ＬＰｈｅ这一主要构成原料需求量激增,人们纷纷开展ＬＰｈｅ的研制生产．在众多生物合成途径中,肉桂酸酶法转化生产ＬＰｈｅ的研究开发因其原料易得价廉,倍受国内外的许多公司和…     

盐碱地养鱼的水质改良

报道了盐碱地池塘、水库、湖泊养鱼中的水质改良技术。池塘水质改良措施主要为加注淡水、施用有机肥、注水与施肥相结合、改造盐碱土质、控制生石灰用量及合理注排水 ;水库、湖泊等大水面水质改良的主要措施是引淡水和增施肥料 (有机肥和化肥 )。     

Synchrony in egg-laying and reproductive success of neighboring common murres,Uria aalge

Common murres (Uria aalge) are highly colonial; pairs often breed at the highest possible densities, in bodily contact with neighbors. At Bluff, a colony in western Alaska, we tested for synchrony in egg laying at various spatial scales and found little evidence for higher synchrony, either within study plots of 15–195 pairs, or within subplots containing several pairs, than among plots in a 5-year study. Egg laying of neighbors generally was more synchronous than expected based on overall frequency distributions in laying dates, however. Breeding success was positively correlated with the number of breeding neighbors and the number of neighbors tending eggs or nestlings at the time of egg laying. Breeding success of pairs with neighbors was positively related to the breeding success of neighbors. Pairs that produced eggs synchronously with at least one neighboring pair had higher success than those that began breeding either before or after their neighbors. Most reproductive failures at Bluff are due to accidental egg loss and predation on eggs by common ravens, Corvus corax, soon after laying. By occupying space where a raven might otherwise land and defending their own eggs, active breeding neighbors locally reduce the probability of egg predation. Active breeding neighbors also are less likely to flush and accidentally dislodge nearby eggs when disturbed than are nonbreeders. Murres breeding synchronously with neighbors have the highest assurance of the presence of active breeding neighbors both at the time of egg laying and throughout their reproductive attempts. Groups of neighboring murres can be considered small “selfish herds,” demonstrating by-product mutualism through their continued presence and defense of their own eggs and nestlings. Despite the advantages of breeding synchronously with neighbors, early breeding may often be favored, however. Received: 22 January 1996/Accepted after revision: 16 June 1996     

MOBILE OXYGEN DISPERSION CRAFT1

Water pollution control by effluent treatment becomes increasingly expensive as the degree of treatment is increased. As has previously been demonstrated, instream aeration provides an economical alternative for the higher degrees of treatment. For large, deep, navigable rivers, another alternative may be still more economical, namely, mobile oxygenating craft, using fine bubble diffusers. The propellors in the craft plus its mobility would give important advantages in dispersing the oxygenated water; and one craft could replace a multiplicity of static aeration sites.     

“熟人社会”农村与“原子化”农村中的生猪养殖废弃物能源化利用——博弈、仿真与现实检验

以生猪粪便制沼气为例,应用博弈论和仿真方法,探究了“熟人社会”农村和“原子化”农村中养猪户的行为演化规律和稳定策略。进而以规模养猪户微观数据为基础,应用计量经济学研究方法,对博弈和仿真结果进行了检验。研究表明：“地方性共识”引致的隐性激励是维系“熟人社会”农村生猪养殖废弃物能源化利用集体行动的重要机制。而在“原子化”农村中,由于人情机制与礼俗机制的衰弱,“地方性共识”近乎消失殆尽,养猪户倾向于成为严格的机会主义者,从而导致生猪养殖废弃物能源化利用集体行动举步维艰。据此,在强化法律法规、政策方针等正式制度建设的同时,还应推动“地方性共识”建设,以乡村文化振兴助推乡村生态振兴。     

海滨垃圾填埋场渗滤液污染土壤的复电阻率特性

为了解渗滤液污染土壤的复电阻率特性及其与海水入侵所造成的电特性差异,指导海滨场地的污染探测,设计了黏土和砂土两种土壤,在水饱和情况下通入不同浓度的渗滤液,测量复电阻率的幅值和相位响应;在砂土中通入与渗滤液电阻率相同的模拟海水,对比海水入侵与渗滤液污染所造成的相位差异.结果表明:受渗滤液污染土壤的复电阻率变化明显,0.1 Hz下被2%渗滤液（渗滤液体积占溶液总体积比例为2%）污染的土壤中,与背景值相比,黏土的幅值和相位分别降低了78%和70%,砂土的幅值和相位分别降低了66%和33%,且渗滤液浓度越高,幅值和相位的值就越小;而对于电阻率背景值较低的土壤（如海水入侵场地或地下水-海水交错带区域）,通入渗滤液后,其复电阻率参数没有明显变化.对比海水入侵与渗滤液污染,受渗滤液污染较轻的土壤的相位略高于海水入侵污染土壤,而当渗滤液浓度较高时,二者几乎没有区别.研究显示,正常条件下,复电阻率法对渗滤液污染的反映灵敏,有较好的指示意义,其参数变化主要与孔隙水中金属离子的含量和双电层极化有关;而在天然低电阻率背景条件下,渗滤液污染引起的电阻率变化很小,但相位变化较为明显,这种相位的变化有可能被识别出来.