利用盐田卤水池塘养殖卤虫的研究

1988年和1989年,作者在山东省盐场利用盐田卤水池进行了卤虫池塘养殖的研究。研究内容包括微藻培养试验、卤虫群体生长能力试验和间捕法养殖卤虫试验。通过试验在6个投饵池塘获得的鲜活卤虫产量为423.5—551.0公斤/亩(平均491.6公斤/亩),在4个不投饵池塘获得的产量为240.5—299.5公斤/亩(平均272.3公斤/亩)。本文报告了以上三个试验的内容和结果,并对卤虫养殖中出现的几个问题进行了讨论。     

南四湖区新建池塘主养鲤鱼高产试验

本文介绍了南四湖区新建池塘主养鲤鱼高产试验的全部过程。试验选用了优良大规格鲤鱼种,研制颗粒饲料,强化精养,合理搭配其他品种的方法,获得了高产量和显著的经济效益。本试验从一九八九年四月上旬开始,至同年十一月止。通过验收、鉴定,50.52亩水面,总净产47289.32公斤,平均亩净产936.05公斤,其中鲤成鱼总净产40324.12公斤,平均亩净产798.18公斤,亩均纯收入3500多元,为开发湖区宜渔资源,加快湖区经济建设提供了一条极好途径。     

三疣梭子蟹雌雄隔离养殖技术研究

在193亩池塘中开展三疣梭子蟹雌雄分养和雌雄混养对比试验。其中雌雄分养面积93亩，亩产商品蟹182公斤，平均壳宽12．6厘米，平均个体重230．1克，成活率40．2％。与雌雄混养相比，亩产量提高了53．6％，成活率提高了1.51倍。专家鉴定认为，梭子蟹雌雄分养，方式新颖，效果明显，技术水平属国内先进。     

济宁市推广池塘机械化养鱼

南四湖是山东省淡水鱼类养殖基地,在发展大水面湖泊养鱼的同时,池塘养鱼在该地区发展的也很快。为了提高池塘养鱼的产量,提高经济效益和减轻劳动强度,必须从人工养鱼走向机械养鱼,为此省科委和省水产局于1988年给济宁市下达了池塘机械化养鱼技术推广项目,经过两年的工作,该地区的池塘养鱼机械化程度有了很大的提高。推广面积达2188亩,取得了平均亩产624.8公斤的成绩。现在已拥有各种养鱼机械3030.8瓩,平均每亩1.37瓩,其中有增氧机219台、498.8瓩;饲料加工机13台,498.8瓩;挖塘机11部,挖掘机1部,推土机1部,并有一批从4马力到130马力的运输机械。增氧机的使用,增加了放氧密度,一类塘亩放鱼种110—130公斤,1000—1200尾;二类塘亩放鱼种90—100公斤,1000尾以上;三     

烟单14号玉米产量构成模型及提高产量途径分析

根据1984—1986年烟单14号玉米田间试验的大量数据,作者在引进弹性系数概念后,建立了烟单14号夏玉米产量的非线性模型: Q=Ay~α_1y~β_2y~γ_3e~ε通过对模型中弹性系数的统计分析,提出大面积烟单14号玉米不同产量水平增产的途径,低产水平区(<250公斤/亩),着重提高亩穗数:中产水平区(250—400公斤/亩),在一定亩穗数的基础上,着重提高穗粒数;高产水平区(>400公斤/亩),提高粒重对产量的增产效益较大。     

刺参池塘养殖的研究

本文报道了刺参池塘养殖的研究成果。本试验在水深80cm、日换水率在3%以上、面积为3.91亩的养虾池中进行。在虾池内建造人工海参礁;往虾池投放体长5—7cm的参苗1249头和体长1cm左右的参苗2500头;不投任何饵料。经过1年半饲养,刺参有147头(约4%)长到商品规格,平均体重达179.6g,有600头平均体重达到50—120g。 本项试验的意义在于:为刺参的人工养殖开辟了新的途径,对刺参要求的环境条件提供了新的依据,同时为生物净化养虾池创出了新路,具有重要的理论意义和经济价值。     

假睛东方鲀鱼养成试验通过验收

1991年10月19～20日,山东省盐务局在莱州市东方红盐场组织了“假睛东方鲀鱼养成试验”验收会,出席会议的有中科院海洋所、青岛海洋大学、中国水科院黄海所、山东省海水养殖所的有关专家及山东省盐务局、烟台市、莱州市的有关领导。 该项目由山东省盐务局下达,中科院海洋所及莱州市东方红盐场承担。试验用鱼苗为中科院海洋所     

虾池养殖鲈鱼经济效益好

近几年来,由于流行性虾病暴发,致使目前有相当一部分虾池荒废。为了寻找出路,重新利用这些虾池,笔者于1995年在广西防城港市公车虾场进行了鲈鱼养殖试验,结果在五个虾池(共60亩)中,收获成品鲈鱼15 480公斤,平均亩产258公斤。其养殖方法如下:     

海湾扇贝虾池不同保苗器试验

海湾扇贝(Argopeclen irradians Lamarck)育苗保苗率的高低直接影响到扇贝养殖业的发展。扇贝中间暂养一般在海上进行,由于海区海况复杂,使保苗率偏低,一般在8～15％。 为了提高扇贝的保苗率,1987年作者在文登市小观乡养虾场,利用170亩(1亩=666.6m~2,下同)的对虾养殖池进行了海湾扇贝稚贝的保苗试验。6月1日出池稚贝2.995×10~7只,到6月26日达到商品苗为     

江苏赣榆县宋庄乡粮虾互促效益显著

1986年,地处沿海的宋庄乡,在8000亩滩涂上仅用250多名养虾能手担负养殖对虾的任务,就夺得年总产几百吨的最新水平;多余的千余铝养虾能手出县、出省承包近两万亩滩涂,生产对虾产量也很高。而本乡的18000亩粮田,仅投入不足40%的劳力,就创年总产1656.3万公斤的历史最高水平;其中小麦平均单产创413.3公斤的最高纪录,位于全省前列。     

Tissue slice technology for assessing alterations in fish hepatic phase I and phase II XME activity

Alterations to hepatic xenobiotic metabolizing enzymes (XMEs) is an important biomarker of contaminant exposure in aquatic toxicology. Measurement of XMEs in fish liver slices in vitro is an emerging tool for examining enzyme activity and response within the intact 3-D architecture of the liver tissue. We examined integrated phase I/phase II, and phase II metabolism of XMEs from liver slices in control and B[a]P-treated rainbow trout and channel catfish. Fluorescent assay substrates to measure rates of metabolism included 7-methoxycoumarin (7-MC), 7-ethoxycoumarin (7-EC) and 7-hydroxycoumarin (7-HC). Time-dependent increases in metabolism, and a lower rate of 7-MC metabolism compared with 7-EC metabolism, were observed at all time points for both fish species. In rainbow trout, B[a]P pretreatment caused a 10-fold increase in phase I metabolism of both 7-MC and 7-EC, and a 1.6-fold increase in phase II metabolism of 7-HC. Phase I activity in channel catfish was not notably altered by B[a]P pretreatment. However, B[a]P pretreatment in channel catfish caused a 48% decrease in phase II metabolism of 7-HC. These results indicate differences in baseline and B[a]P-altered XME profiles between rainbow trout and channel catfish.     

Biotransformation and estrogenic activity of Methoxychlor and its metabolites in channel catfish (Ictalurus punctatus)

Methoxychlor (MXC) has been shown to possess estrogenic activity in mammals and fish. Although MXC does not appear to appreciably bind the mammalian estrogen receptor, its demethylated metabolites have been shown to be significantly more potent agonists and are believed responsible for estrogenic effects in mammals following exposure to this pesticide. To determine whether catfish were capable of MXC demethylotion, and, hence, activation to a more estrogenic compound, in vitro biotransformation studies were carried out using hepatic microsomes from mature male channel catfish. Hepatic microsomes catalyzed the NADPH-dependent formation of monodemethylated (mono-MXC) and bisdemethylated (bis-MXC) metabolites of MXC. Treatment with mono-MXC at 40% of the MXC dose in catfish significantly induced serum vitellogenin (Vg) levels compared to MXC. Estrogen receptor binding studies in catfish liver cytosol showed that a racemic mixture of the mono-MXC had approximately 43 times the affinity for the receptor than MXC, but was still over 1000-fold less potent that 17β-estradiol. These results demonstrate that catfish are capable of biochemically activating MXC to a more potent hepatic estrogen receptor agonist.     

Cloning and sequencing of cytochrome P450 2X1 from channel catfish (Ictalurus punctatus)

Previous purification and immunochemical studies in livers of channel catfish indicated the presence of at least four cytochrome P450 (CYP) 2-like isoforms. Sequencing of the first 18 amino acids of one purified form indicated a CYP2 isoform. From this N-terminal sequence and other published CYP2 sequences from fish, primers were designed and a full-length CYP cDNA was identified from reverse-transcribed catfish liver mRNA. 5' and 3' RACE was used to obtain an open reading frame of 1470 bp encoding a 490 amino acid protein (approximately 57 kD). CYP2X1 was most identical to Fundulus heteroclitus CYP2P2 (41%); CYP2N2 (40%): and CYP2N1 (39%).     

Kinetics of hepatic phase I and II biotransformation reactions in eight finfish species

Hepatic microsomes and cytosols of channel catfish (Ictalurus punctatus), rainbow trout (Oncorhynchus mykiss), Atlantic salmon (Salmo salar), red tilapia (Oreochromis sp.), largemouth bass (Micropterus salmoides), striped bass (Morone saxatilis), hybrid striped bass (M. saxatilis × M. crysops), and bluegill (Lepomis macrochuris) (n = 8) were used to study the kinetics of phase I (ECOD, EROD, PROD, BROD) and phase II (UDP-glucuronosyltransferase (UDPGT)-, sulfotransferase (ST)- and glutathione-s-transferase (GST)-mediated) reactions. The best catalytic efficiency for ECOD and GST activities was performed by channel catfish, Atlantic salmon, rainbow trout and tilapia. The highest EROD catalytic efficiency was for Atlantic salmon. None of the species had either PROD or BROD activities. Rainbow trout had very similar UDPGT catalytic efficiency to tilapia, channel catfish, Atlantic salmon, largemouth bass and bluegill. Sulfotransferase conjugation had no significant differences among the species. In summary, tilapia, channel catfish, Atlantic salmon and rainbow trout had the best biotransforming capabilities; striped bass, hybrid striped bass and bluegill were low metabolizers and largemouth bass shared some capabilities with both groups.     

Comparative vitellogenic responses in three teleost species: extrapolation to in situ field studies.

Induction of vitellogenin (VTG) was compared among three teleostean species to determine their relative sensitivity of exposure to 17 beta-estradiol (E2). Japanese medaka (Oryzias latipes), sunshine bass (Morone saxatalis x Morone chrysops) and channel catfish (Ictalurus punctatus) were exposed to aqueous concentrations of E2 ranging from 10 to 100,000 ng/l for 21 days. Respective EC50 values for plasma VTG detected by western blot in medaka, catfish and bass were 200, 170 and 1560 ng E2/l. Since these EC50 values are based on VTG induction curves calculated relative to control values, they indicate differences in species' sensitivity to E2 exposure. Catfish and bass VTG responses obtained in laboratory exposures were compared to VTG responses previously observed with 21-day wastewater treatment plant effluent exposures. Plasma VTG induction in effluent-exposed fish ranged from 14 to 82% above reference values depending on species. Extrapolation of field responses with laboratory-exposed fish indicate catfish and bass were exposed to the equivalent of 27-240 ng E2/l in sewage effluent.     

Role of biotransformation in determining aldicarb toxicity in fish

The carbamate pesticide, aldicarb, demonstrates significant acute toxicity in fish, and is readily biotransformed by most organisms studied. In fish, both the cytochrome P450 (CYP) and the flavin monooxygenase systems (FMO) are involved in bioactivating aldicarb to aldicarb sulfoxide, which is a more potent inhibitor of acetylcholinesterase (AChE). Channel catfish (Ictalurus punctatus), along with many other fresh water species, do not express FMO and are relatively resistant to the effects of aldicarb. This project examined the toxicity, AChE inhibition, metabolism, and toxicokinetic of aldicarb in channel catfish, and compared these values with an aldicarb-sensitive species, rainbow trout, which expresses FMO. Studies of in vitro and in vivo aldicarb biotransformation in catfish suggest that a low rate of bioactivation (10 times slower V_max), resulting in less initial conversion to the activated metabolite, aldicarb sulfoxide, may be a contributing factor to resistance of channel catfish to aldicarb toxicity. These data are supported by toxicokinetic and enzyme inhibition studies. This work demonstrates that differences in FMO expression among fish species may have significant influence on toxicity resulting from exposure to some xenobiotics.     

Glutathione-mediated chlorothalonil detoxification in channel catfish gills

Maintenance of the glutathione (GSH) pathway is critical in guarding against the toxic effects of a variety of pollutants. However, despite their importance as an initial line of defense against waterborne toxicants, little is known regarding the role of fish gills in GSH-mediated xenobiotic metabolism. In these studies, the role of channel catfish gills in the detoxification of 2,4,5,6-tetrachloroisophthalonitrile (chlorothalonil), an electrophilic fungicide, was examined. Chlorothalonil was metabolized in vitro by gill cytosolic and microsomal glutathione S-transferases (GSTs). Chlorothalonil metabolism by cytosolic fructions was reduced markedly when GSH was omitted from reaction mixtures. Microsomal metabolism of chlorothalonil did not occur in the absence of GSH and in the presence of an NADPH-regenerating system lacking GSH. Channel catfish exposed in vivo to chlorothalonil had increased gill GSH and cysteine concentrations after 72 h exposure, and increased gill gamma-glutamylcysteine synthetase (GCS) activity at 144 h of exposure. Our results show that the gills play an important role in the metabolism and detoxification of chlorothalonil in the channel catfish. Catfish can maintain elevated gill GSH concentrations in the presence of chlorothalonil by increasing gill cysteine concentrations.     

Mycobacteria, but not mercury, induces metallothionein (MT) protein in striped bass, Morone saxitilis, phagocytes, while both stimuli induce MT in channel catfish, Ictalurus punctatus, phagocytes

Recent advances in molecular immunology indicate that the expression of inducible pro-inflammatory proteins is increased in vertebrates in response to both infectious disease agents and various xenobiotics. For example, iNOS, COX-2, and CYP1A are induced by both inflammation and AhR ligands. Moreover, the expression of these proteins in response to stimuli varies among individuals within populations. Little is known of the differences among fish in the inducibility of proinflammatory proteins in response to both infectious agents and xenobiotics. Through random screening of a striped bass, Morone saxitilis, peritoneal macrophage cDNA library, a full length metallothionein (MT) gene was cloned and sequenced. MT is a low-molecular weight (6–8 kDa), cysteine-rich metal binding protein. Metals are required by pathogenic bacteria for growth, and by the host defense system by serving as a catalyst for the generation of reactive oxygen intermediates (ROIs) by phagocytes. A recombinant striped bass MT (rMT) was expressed and purified, then used to generate a specific mAb (MT-16). MT protein expression was followed in freshly isolated striped bass and channel catfish, Ictalurus punctatus, phagocytes after in vitro exposure to the naturally occurring intracellular pathogen Mycobacteria fortuitum or to 0.1 and 1 μM mercury (Hg), as HgCl₂. MT expression was increased by 24 h in both channel catfish and striped bass phagocytes as a result of exposure to M. fortuitum cells. On the other hand, MT was induced by Hg in channel catfish cells, but not those of striped bass. These results indicate that metal homeostasis in phagocytes is different between catfish and striped bass. In addition, these data suggest that care should be taken to distinguish between inflammation-induced vs. metal-induced MT when using MT expression as a biomarker of metal exposure.     

Mycobacteria, but not mercury, induces metallothionein (MT) protein in striped bass, Morone saxitilis, phagocytes, while both stimuli induce MT in channel catfish, Ictalurus punctatus, phagocytes

Recent advances in molecular immunology indicate that the expression of inducible pro-inflammatory proteins is increased in vertebrates in response to both infectious disease agents and various xenobiotics. For example, iNOS, COX-2, and CYP1A are induced by both inflammation and AhR ligands. Moreover, the expression of these proteins in response to stimuli varies among individuals within populations. Little is known of the differences among fish in the inducibility of proinflammatory proteins in response to both infectious agents and xenobiotics. Through random screening of a striped bass, Morone saxitilis, peritoneal macrophage cDNA library, a full length metallothionein (MT) gene was cloned and sequenced. MT is a low-molecular weight (6-8 kDa), cysteine-rich metal binding protein. Metals are required by pathogenic bacteria for growth, and by the host defense system by serving as a catalyst for the generation of reactive oxygen intermediates (ROIs) by phagocytes. A recombinant striped bass MT (rMT) was expressed and purified, then used to generate a specific mAb (MT-16). MT protein expression was followed in freshly isolated striped bass and channel catfish, Ictalurus punctatus, phagocytes after in vitro exposure to the naturally occurring intracellular pathogen Mycobacteria fortuitum or to 0.1 and 1 microM mercury (Hg), as HgCl(2). MT expression was increased by 24 h in both channel catfish and striped bass phagocytes as a result of exposure to M. fortuitum cells. On the other hand, MT was induced by Hg in channel catfish cells, but not those of striped bass. These results indicate that metal homeostasis in phagocytes is different between catfish and striped bass. In addition, these data suggest that care should be taken to distinguish between inflammation-induced vs. metal-induced MT when using MT expression as a biomarker of metal exposure.     

Induction of phenol-type sulfotransferase and glucuronosyltransferase in channel catfish and mummichog

Conjugation of phenolic xenobiotics and metabolites through sulfation and glucuronidation is an important biotransformation pathway. Sulfotransferases (SULT) are generally considered non-inducible, while some UDP-glucuronosyltransferase (UGT) isoenzymes are co-induced with cytochrome P450-1A by Ah-receptor ligands. To test these assumptions for two fish species, we measured sulfation and glucuronidation of 9-hydroxybenzo[a]pyrene in 3-methylcholanthrene (3-MC) treated channel catfish (Ictalurus punctatus) and in mummichog (Fundulus heteroclitus) from the creosote contaminated Atlantic Wood site in the Elizabeth River, VA. The results show a significant induction of both UGT and SULT activity in 3-MC treated catfish, linked to the expected induction of EROD activity. In mummichog, significant induction of UGT was measured at the contaminated site over the reference site (King's Creek, VA), as well as extremely low SULT activities at both sites. Western blots, using a polyclonal antibody for catfish phenol-type SULT, confirmed the absence of phenol-type SULT in mummichog. Residual, though slightly inducible, SULT activity may be attributed to other SULT isoforms.