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1.
线纹尖塘鳢的形态生物学与核型 总被引：6，自引：0，他引：6
This paper reports the morphological character and karyotype of Oxyeleotris lineolatus. Oxyeleotris lineolatus is native in Australia and call
ed sleepy cod. It belongs to Oxyeleotris, Eleotridae, Gobioidei, Perciformes in taxonomy. Recently, it was introduced to China and local people were not familiar with it. So we carried out this study. 30 individuals have been observed and some data were recorded. It has a large mouth that is in front and up. The mandible stands out and is longer than the up jaw. There are many rows of thin teeth in up and down jaws. The pelvie fins are located in chest and pectoral fins are large and fanlike. There are two dorsal fins. The tail fin is circular. Gill rakers are sparse and the number of gill rakers is 8-12+3-4. The gas bladder belongs to physoclistaus and its stomach is strong and I-like. The intestine is thick and short and no pyloric caecas. The length of the digestive path is 48.1％-80.3% of the length of body. Its liver has two lobes and the liver weight is 4.1%-7.2% of the body weight. The digestive organs characters are same as the trait of flesheater fish. Its scale belongs to ctenoid scale and its body surface shows several long lines. There is not lateral line in the body. The number of vertebra is 26-27 and it has 10-11 pairs rib. The number of diploid chromosome is 2n=46 and the karyotype formula is 2sm+8st+36t，NF=48. The relative length of chromosome is from 1.37% to 3.48% and it is continuity. No strange size chromosomes relation to sex was observed. The karyotype of Oxyeleotris lineolatus is similar to that of Oxyeletris marmoratus Bleeker from South East Asia and both of them belong to Oxyeleotri. It testifies the correctness of traditional classification on cytology. 相似文献
2.
Interleukin-1β(IL-1β) is one of the most pleiotropic cytokines and a central regulator of the immune and inflammatory responses. Interleukin-1β was initially discovered within mice and humans and over the last 10 years has been characterized within a wide variety of animals. The IL-1β plays a key role in the inflammatory process, enhancing cell-mediated immunity by inducing the growth and proliferation of lymphocytes, connective tissue cells, and by stimulating immune and inflammatory response effector cells.As an immunoregulatory cytokine, IL-1β has the potential to enhance the immune response induced by a vaccine and/or to modulate the immune response leading to different effector mechanisms. It is produced by many cell types, including monocytes, macrophages,T and B lymphocytes, fibroblasts, and endothelial and epithelial cells. Expression is induced by a diverse range of stimuli, including mitogens, cytokines, and microbial products. There have been considerable evidences provided by biological cross reaction that fish produce IL-1β during immune responses, and the bioactivity of IL-1 in fish has been known for over a decade. But only. since 1999,IL-1β gene has been cloned from the rainbow trout. And from then on, IL-1β gene has been cloned and expressed in many fish confirming that fish produces IL-1β gene during immune responses. In mammals it is produced as an inactive precursor that is processed by interleukin converting enzyme (ICE) to give a biologically active ‘mature‘ peptide. There is no signal peptide in IL-1β and its mechanism is unknown. This is the special part of the gene structure of the IL-1β. And through the program analyzing, we found this special structure in fish IL-1β gene. This paper reviews the functions and structure of gene IL-1β and the studies of the gene IL-1β in fish recently. 相似文献
3.
丁鱥雌核发育鱼的异源精子诱导及其与亲本的RAPD比较分析 总被引：1，自引：0，他引：1
Gynogenesis is thought to be a useful method to generate fully inbred line and to initiate monosex culture in teleost fish. This article presents results of a study of gynogenesis of tench, Tinca tinca L. from Eltrix River of Xinjiang, China, induced by the common carp ( Cyprinus carpio ) sperm inactivated with UV irradiation. When cold shocking method was used to prevent exmasion of the second polar body in order to produce gynogenetic diploids, the optimum treated parameters were screened as cold shocking for 20min at 4℃, 5min after insemination. On this condition, 10.23% of the treated eggs survived at feeding stage. A comparative study between the gynogenesis and their parents was made by RAPD technique. 82 random primers of 10 nucleotide long sequence were used in RAPD analysis. The results showed that each primer gives 3- 12 fragments for each sample with the fragment length 330 - 2 460 bp, and the genetic similarity between gynogenesis and their mother was 97.4 %, while the genetic similarity between gynogenesis and their father was 27.4%, and there were no bands only shared by gynogenesis and their father, the common carp. It revealed that the chromosome of their father, the common carp, did not penetrate into the construction of gynogenetic tench. 相似文献
4.
水产食品特定腐败菌与货架期的预测和延长 总被引：25，自引：2，他引：25
Fresh fish and lightly preserved fish products are welcome by the global market, however, they are also among the most perishable food products. The research on specific spoilage organisms (SSO) reveals the spoilage process of aquatic product. This paper reviews the current knowledge (past ten years) on SSO of fresh fish and lightly preserved fish products with particular emphasis on characteristics of SSO and how to apply this concept to determine, predict and extend the shelf life of aquatic product. During storage, the microflora changes owing to different abilities of the microorganisms to tolerate the preservation conditions. SSO is defined as special microorganisms which can increase rapidly during preservation and has the ability to produce off- odours and off- flavours associated with spoilage, and spoilage metabolites. Identification of an SSO relies on comparison of the sensory and chemical characteristics of spoiled product with those of isolates from the spoilage microflora. Generally, the SSO of fresh fish may be a single species or genus, but the ones of lightly preserved fish products will be more complex. One exciting area for use of SSO aims to obtain quantitative knowledge about probable behavior of SSO and their function during the progression of spoilage. Thus mathematical models on the growth of SSO are established to evaluate the quality lost degree of product, which provide a sound information for the rational development of devices to monitor loss of products shelf life. Models for the growth of Pseudomonas spp, S. putrefaciens, P. phosphoreum have been established, and validated for shelf life prediction of seafood successfully. Another application field of SSO intends to develop the techniques to prolong the shelf life of food products by inhibiting SSO targetedly. Targeted inhibition of spoilage bacteria during preservation reduces their growth and results in a significant extension of shelf life in despite of the activity of non - spoilage organisms has not been influenced. Such techniques have been applied in perversion field of fresh fish and lightly preserved fish. 相似文献
5.
动植物蛋白源替代鱼粉研究进展 总被引：42，自引：5，他引：37
With the fast development of aquaculture, fish meal needs increased in recent years, however the quantity of fish catching decreases gradually. Fishmeal is a limited feed resource, and serious concem exists on the future availability of this feedstuff for incorporation in fish diets. Undoubtedly, fish meal is well recognized as the best dietary protein source for most marine carnivorous fishes which required high dietary protein levels compared to omnivorous or herbivorous fish. Fishmeal is known for their high content of essential amino acids and fatty acids, low carbohydrates, high digestibility, low levels of anti-nutritional factors (for fresh fish meal) and is a very good source of minerals and is highly palatable. Thus fish meal is in high demand as the protein source for many formulated diets. However, production of fish meal consumes approximately 35 % of the total global fish catch, and the increasing price and potentially unstable supply in the market could be limiting factors for marine fish culture. There have been strong efforts to define and develop cost-effective protein sources that can, at least partly, substitute for expensive high-quality fish meals in least-cost feed formulations. The search for fish meal substitutes and altemative dietary protein sources is an international research priority that could be of considerable economic advantages. Therefore it is urgent task to find animal and plant protein sources in place of fish meal. Among these, plant feedstuffs have received most attention in recent years, but due to their amino acid unbalances, .presence of anti-nutritional factors and low palatability, a high level of replacement of fish meal with plant feedstuffs in omnivorous fish is generally not well accepted. This paper reviews the research status for other protein sources replacing fish meal based on available information in the literature. Animal and plant protein sources nutrient values are evaluated from the aspect of digestibility, antinutrients, physiological status and suitable supplementation. 相似文献
6.
基于模糊AHP的长寿湖生态系统健康评价 总被引：2，自引：0，他引：2
Ecosystem health assessment is a focus and hot spots field of ecological research, there is no unified evaluation indicators and evaluation methods. First, according to the area physical, human features of the Changshou lake and existed research, We established ecosystem health evaluation system which has included three secondary indexes ： the ecological characteristics indicators, the function indicators and the socio - economic indicators, and has 20 indicators. Second, we assess the Changshou lake ecosystem with the ecosystem health index which based on the fuzzy AHP. The conclusions are as follows： in 2006, the Changshou lake ecosystem health index was 0. 471, it is showed that the ecosystem is in sub health, the mainly reasons is its upper reaches of the Di- anjiang county, Liangping county long - term discharge of industrial sewage and pollution of fencing fish. 相似文献
7.
鱼粉在水产饲料中的应用研究 总被引：6，自引：0，他引：6
As a main protein source in aquafeeds, fish meal has been extensively studied. Fish sources, freshness, processing temperature, lipid quality and microbiological index are five main aspects of the evaluation of fish meal quality. This paper reviewed the researches on fish meal including the evaluation of fish meal quality, the use of fishmeal and the environmental problems. Biogenic amine is the main potential toxin in decomposed fish meal including mainly histamine, cadaverine, putrescine and tyramine and most studies showed that they could affect the fish growth performance and health. The determination of protein digestibility of fish meal includes pepsin-digestion method, animal test, capillary electrophoresis, etc. The content of phosphorus in fish meal and its utilization can introduce pollution to water bodies and the use of alternative protein and improvement of utilization of fish meal can help to reduce the pollution from fish meal. 相似文献
8.
大西洋中部金枪鱼延绳钓渔场大眼金枪鱼的生物学特性 总被引：8，自引：3，他引：8
Based on the biological data of bigeye tuna measured from the longlining ground of the Central Atlantic Ocean from Jun. 2001 to Oct. 2001, this paper analyzed the bigeye tuna‘s maturity stages of the gonad, feeding intensity, species composition of prey, sex ratio, fork length distribution, relationships between fork length and dressed weight, fork length and round weight, round weight and dressed weight by statistic and regression methods. The results indicate: ( 1 ) Maturity at Ⅳ-Ⅵ of the gonad are dominant with the highest percentage of Ⅴ (30.11% ). (2)The feeding intensity is mainly in the class 1 ,class 2 or class 3,totally 83.16%. (3)In the bigeye tuna‘s species composition of prey, the percentage of miscellaneous fish or cephalopod is relatively high, 38.05 % or 30.48 % respectively. Catch rate of bigeye tuna can be enhanced when cephalopod is used as the bait. (4) The male-female ratio is 2 : 1. This pattern might result from elevated mortality of adult females. (5) The fork length distribution is suitable for the normal. The dominant fork length is 1.13 - 1.49m, 64.16%, with the mean value of 1.32m. (6)The relationship between fork length and dressed weight. (7)The relationship between fork length and round weight. If the fork length is the same, the round weight converted in this paper‘s formula is a little lighter than the round weight converted in Parks‘s formula concluded at 1981 of the longline bigeye tuna catch. It might be caused by the different sampling areas or sampling time. (8)The relationship between round weight and dressed weight. The round weight conversion factor in this paper is a little higher than the ICCAT. It might be caused by the different processing methods. ICCAT is recommended to adapt this paper‘s conversion factor. 相似文献
9.
In order to investigate the difference in utilization of diets with different quality in Jian carp（Cyprinus carpio var. Jian）and allogynogenetic silver curcian carp(Carassius auratus gibelio), a 55 d growth trial was conducted and low quality diet (LQ-diet) and high quality diet (HQ diet) were tested. LQ-diet contained 33.91% dietary protein which is mainly from soybean meal while HQ-diet contained 45.59% dietary protein which is mainly from fish meal. The initial average body weights were from 5.58 g to 5.82 g for two fish strains. The trial was carried out in a system consisting of 12 self circulation 320 L tanks. During the experiment, the fish were fed to satiation twice a day (at 9: 00 and 15:00), and uneaten feed was collected 1 h after feeding and dried. Feces were collected twice a day (at 11:00 and 16:45) from the fecal traps and dried at 70 ℃. The results show that feed intake was higher in Jian carp than in allogynogenetic silver curcian carp when fed LQ diet, while there was no significant difference between weight gain, feed conversion efficiency, protein efficiency rate and apparent digestibility. When fed HQ diet, Jian carp showed a lower feed intake, but higher feed conversion efficiency and protein efficiency rate than allogynogenetic silver curcian carp while there was no significant difference in the weight gain and apparent digestibility of both species. For Jian carp, feed intake and protein efficiency rate for the fish fed HQ diet and LQ diet were not significantly different, while the fish fed HQ diet showed higher weight gain, feed conve
rsion efficiency and apparent digestibility. For allogynogenetic silver curcian carp, the fish fed HQ diet showed significantly higher feed intake, apparent digestibility, weight gain, feed conversion efficiency and lower protein efficiency rate. For Jian carp, body contents of dry matter, protein, lipid and energy for the fish fed HQ diet and LQ diet were significantly higher. For allogynogenetic silver curcian carp, body contents of dry matter and protein was significantly higher, while body contents of lipid and energy were affected by diet qualities. Compared to Jian carp, allogynogenetic silver curcian carp showed better utilization when fed LQ diet while poorer utilization when fed HQ diet. 相似文献
10.
鱼类粘膜免疫研究进展 总被引：7，自引：1，他引：7
Fish immunology has achieved great progress in recent years. While before 1990s, most researches focused on the fish systematic immunity, and the mucosal immunity of fish had not been given enough attention. Indeed, it has been shown that fish mucosal immunity plays an important role in disease defense. Fish mucosal immunity research has made some exciting progress in this decade. This review will focus on such progress: Constitution of mucosal-associated tissues and distribution of different immune cells, including T/B lymphocytes, granules, monocytes, macrophages, goblet cells, etc, in these sites have been well described with the development of some monoclonal antibody to these cells and associated techniques. Non-specific immune response mechanism of mucosal tissues reported these years, such as secretion of non-specific anti-bacteria and anti-fungi substances in mucus, the respiratory burst, enzyme activity of immune cells and so on, is believed important for fish disease defense. The specific immunity of mucosal tissues also attracts much interest and makes great achievement in antigen presenting, MHC genes, antibody producing and antibody secreting cells, comparison of serum and mucus immunoglobulin, relationships of immune response between different mucosal immune tissues. Whether mucosal immune system is independent of systematic immune system is another interesting question and causes great concern. In recent years, some evidences from phyletic evolution and ontogenesis show that mucosal immunity is prior to systematic immunity in evolution. Dynamics of antibody producing of mucosal tissues and serum in immersion or oral vaccines immunized fish also shows immune response can be elicited in mucosal tissues independent of systematic immune system. Some researchers also begin to pay attention to factors involved in mucosal immune regulations, for instance, neuromodulators and cytokines. The level of these factors changes in fish immune response process but the mechanisms of regulation still remain unknown. Prospect of the promising future of fish mucosal immunity has also been discussed in this review. 相似文献
11.
Association between the interannual variation in the oceanic environment and catch rates of bigeye tuna (Thunnus obesus) in the Atlantic Ocean 
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下载免费PDF全文 The environmental processes associated with variability in the catch rates of bigeye tuna in the Atlantic Ocean are largely unexplored. This study used generalized additive models (GAMs) fitted to Taiwanese longline fishery data from 1990 to 2009 and investigated the association between environmental variables and catch rates to identify the processes influencing bigeye tuna distribution in the Atlantic Ocean. The present findings reveal that the year (temporal factor), latitude and longitude (spatial factors), and major regular longline target species of albacore catches are significant for the standardization of bigeye tuna catch rates in the Atlantic Ocean. The standardized catch rates and distribution of bigeye tuna were found to be related to environmental and climatic variation. The model selection processes showed that the selected GAMs explained 70% of the cumulative deviance in the entire Atlantic Ocean. Regarding environmental factors, the depth of the 20 degree isotherm (D20) substantially contributed to the explained deviance; other important factors were sea surface temperature (SST) and sea surface height deviation (SSHD). The potential fishing grounds were observed with SSTs of 22–28°C, a D20 shallower than 150 m and negative SSHDs in the Atlantic Ocean. The higher predicted catch rates were increased in the positive northern tropical Atlantic and negative North Atlantic Oscillation events with a higher SST and shallow D20, suggesting that climatic oscillations affect the population abundance and distribution of bigeye tuna. 相似文献
12.
Liping Li Rui Wang Wanwen Liang Xi Gan Ting Huang Yan Huang Jian Li Yunliang Shi Honglin Luo Ming Chen 《广西水产科技》2014,(1)
Previously, we reported 10 PEGE types of 85 tilapia Streptococcus agalactiae(GBS), which shifted from Streptococcus iniae in China, by using PEGE method. Presently, larger and more representative tilapia GBS were isolated, for the ?rst time in China, to characterize their serotypes and genetic diversities more precisely than had done before. 168 GBS strains were distributed in ?ve provinces of China, in which Guangdong, Guangxi and Hainan were the major ones, holding36.9%(62/168), 37.5%(63/168) and 19.6%(33/168), respectively. Serotypes, Ia, Ib and III, were observed in these strains and the most predominant one was Ia(95.2%), which mainly distributed in Guangdong, Guangxi and Hainan. Ia initially occurred in 2009, it shoot up to 32.1% in 2010,but decreased to 16.1% in 2011 before went up to 45.2% in 2012. Ib sporadically occurred during2007–2011, III onlyoccurred in 2012. 14 different PFGE types, including 4 new types(N, O,P and Q), were observed, in which B, D, F and G were the predominant types, holding 83.9%(141/168) of the total GBS strains. Ia corresponded to 11 PFGE types(A–H, N–P), in which type D predominated(51%). Ib represented 3 genotypes(I, J and Q) and III harbored only 2genotypes(N and F). Type N and Fsynchronously presented in Ia and III. In summary, the genetic diversity of tilapia GBS varied by serotypes and changed with geographical locations and years.Although Iastillpredominated, new rareserotypeIII alreadyoccurred in China. 相似文献
13.
14.
In this experiment, a feeding trial was performed to determine the effects of fructooligosaccharide (FOS) on growth performance, digestive enzyme activity and immune response of Japanese sea bass, Lateolabrax japonicus juveniles (initial weight 38.3 ± 0.5 g), and the fish were examined following feeding with six levels of FOS (0, 0.5, 1, 2, 4 and 6 g/kg) for 28 days. Significant enhancement of weight gain (WG) and specific growth rate (SGR) was found in fish fed 1 g/kg FOS incorporated diets (p < .05), while the feed conversion ratio (FCR) in the 1, 2 g/kg FOS groups reduced significantly compared with the control (p < .05). Besides, the crude lipid in the 4, 6 g/kg FOS groups increased significantly compared with the control (p < .05). On the other hand, the erepsin and lipase activities significantly elevated in intestine of fish fed 2 g/kg FOS (p < .05) and the lysozyme activity in serum of fish fed 2 g/kg FOS were significantly higher than that in the control (p < .05). Moreover, the alkaline phosphatase activities in serum of fish fed 0.5, 1, 2 g/kg FOS were significantly higher than in control (p < .05). Regression analysis showed that the relationships between dietary FOS levels and either SGR, FCR, erepsin or lysozyme activities were best expressed by regression equations, and the optimal inclusion levels are 1.37, 1.80, 3.06, 3.11, 1.93 and 1.80 g/kg for SGR, FCR, erepsin, lipase, lysozyme and total superoxide dismutase activities, respectively. Overall, this study revealed that FOS incorporated diets could beneficial for L. japonicus culture in terms of increasing the growth, digestion and immune activities. Under the present experimental condition, the optimal supplementary level of FOS in the diet of L. japonicus is 1–3 g/kg. 相似文献
15.
Growth hormone (GH) and reproduction: a review 总被引：5，自引：0，他引：5
Florence Le Gac Odile Blaise Alex Fostier Pierre-Yves Le Bail Maurice Loir Brigitte Mourot Claudine Weil 《Fish physiology and biochemistry》1993,11(1-6):219-232
Interaction between growth and reproduction occurs in many vertebrates and is particularly obvious at certain stages of the life cycle in fish. Endocrine interactions between the gonadotropic axis and the somatotropic axis are described, the potential role of GH being emphasised. A comparative analysis of these phenomena in mammals, amphibians and fish, suggests a specific role of GH in the physiology of puberty, gametogenesis and fertility. It also shows the original contribution made by studies on the fish model in this field of investigations. 相似文献
16.
Two gonadotropins (GtH; Qa and Qb) were purified by gel filtration and ion exchange chromatography from the pituitaries of Indian walking catfish (Clarias batrachus). The presence of GtH during purification was assessed by in vitro oocyte maturation and in vivo steroidogenic activity, and their identities were determined by elution profiles, molecular weight, biological activities and yield. The molecular weights of Qa and Qb were 37 and 42 kDa, respectively, and composed of distinct subunits (Qa: 20 and 14 kDa and Qb: 26 and 18 kDa). Polyclonal antibodies raised against Qa immunostained Qa, Qb and pituitary GtH cells. A competitive Qa‐ELISA was developed whose sensitivity was 6.25 ng mL?1 (1.25 ng well?1) with intra‐ (3.5%) and inter‐ (12.4%) assay coefficients of variation. Displacement curves parallel to the standard were obtained with plasma and pituitary extracts of catfish, Qb and carp GtHII. The assay was validated by measuring the plasma Qa levels after LHRH treatment and in relation to ovarian growth in the female catfish during different reproductive phases. Based on the results, Qa and Qb corresponded to fish LH and FSH respectively. The findings will increase the knowledge of the mechanisms controlling fish reproduction and identification of sensitive phases in fish in captivity for hormonal manipulation. 相似文献
17.
Controlled infection of Poecilia reticulata Peters (guppy) with Tetrahymena by immersion and intraperitoneal injection 下载免费PDF全文
下载免费PDF全文 G Sharon M Pimenta‐Leibowitz M C L Vilchis N Isakov D Zilberg 《Journal of fish diseases》2015,38(1):67-74
Tetrahymena is a protozoan parasite, which infects guppy, Poecilia reticulata Peters, and causes substantial economical losses in commercial farms worldwide. Studies of guppy infected by Tetrahymena require standardized infection protocols. The LD50 for Tetrahymena infection of guppies by intraperitoneal (IP) injection was calibrated, and the level obtained was 946 parasites per fish. Guppy infection with Tetrahymena by immersion, imitating the natural route of infection via the integument, was studied under normal or stress conditions. Exposure to cold and netting (CNI) and to cold only (CI) followed by immersion exposure to 10 000 Tetrahymena per mL resulted in 22.5% and 19.2% mortality, respectively, as compared to 14.2% and 10% in groups that were netted only (NI) or non‐stressed (I). Histopathology revealed that immersion infection resulted in a systemic infection. Lysozyme levels, measured 3 weeks after infection, were significantly higher in the CNI group (288 μg per mg protein) compared with CI‐, NI‐ and I‐treated groups (94.5, 64 and 62.3 μg mg?1, respectively). There was no evident parasite immobilization activity in body homogenates, suggesting no development of acquired immunity. Re‐infection by IP injection revealed no increase in protection in any of the treatment groups, mortality range of 56.3–75%, higher than in the non‐exposed control (40.6% mortality). 相似文献
18.
Sandra García‐Garrido Ismael Hachero‐Cruzado Carlos Rosas Pedro Domingues 《Aquaculture Research》2013,44(11):1741-1751
Protein and amino acid composition of the mantle of juvenile O ctopus vulgaris (Cuvier, 1797) during fasting for 27 days were determined. Average protein content of octopus mantle was of 711.19 ± 46.80 g kg?1 DW, and it decreased with increasing fasting days. The non‐essential amino acids content was higher (486.18 ± 11.08 g kg?1 protein) than essential amino acids (425.82 ± 9.15 g kg?1 protein) at the start of the experiment (unstarved animals). The results suggest that the amino acid profile of the mantle where the most abundant amino acids are Arg, His, Lys, Gly, Leu and Pro could indicate a prolonged fasting condition (>20 days) or poor nutrition of O . vulgaris. This study supports the idea of using mantle for metabolic needs of starved O . vulgaris suggesting that the degradation pathway of amino acids to pyruvate and tricarboxylic acid cycle intermediates was favoured contrary to the degradation pathway of ketogenic amino acids. Special considerations should be taken concerning Thr, Ile, Ser, Ala, Asx (Asp, Asn), Glx (Glu, Gln) (because of their fast intake) and Lys and His (due to their stable contents) during a prolonged period of fasting. 相似文献
19.
The endemic, anadromous cyprinidChalcalburnus tarichi is the only fish species known to occur in alkaline Lake Van (Eastern Anatolia, Turkey). EightC. tarichi were maintained individually in Lake Van water (17 – 19°C; pH 9.8; 153 mEq·I–1 total alkalinity; 22 total salinity) and tank water samples analyzed for 24 h in 2 to 4 h intervals. At zero time, < 1µM ammonia was present and urea was undetectable in the tank water; at 24 h, total ammonia and urea made up 114±32 and 35±25µM, respectively. Over the experimental period, ammonia-N and urea-N excretion averaged 1041±494 and 607±169moles·kg–1 fish·h–1, respectively. The extent of urea excretion was highly variable between specimens. Uric acid excretion was not detectable.Urea was present at high concentrations in all tissues and plasma (25 – 35moles·g–1·ml–1) of freshly caughtC. tarichi; total ammonia content of the tissues was by a factor of 1.9 (liver) to 3.0 (brain) lower. High arginase activity (2.4±0.2 U·min–1·g–1) was detected in the liver ofC. tarichi but ornithine carbamoylphosphate transferase, a key enzyme of the ornithine-urea-cycle, was absent. Ureagenesis is likely through degradation of arginine and/or uricolysis. High glutamine synthetase activity (11±0.6 U·min–1·g–1) and low ammonia content in brain suggest that, like other teleosts,C. tarichi has an efficient ammonia detoxification in the brain, but in no other tissue.Nitrogenous waste excretion at alkaline pH is discussed. The ability ofC. tarichi to excrete high levels of ammonia at extremely alkaline pH is unique among teleosts studied so far. The mechanism of ammonia excretion under Lake Van conditions remains to be elucidated. 相似文献
20.
There has been growing concern about the overuse of antibiotics in the ornamental fish industry and its possible effect on the increasing drug resistance in both commensal and pathogenic organisms in these fish. The aim of this study was to carry out an assessment of the diversity of bacteria, including pathogens, in ornamental fish species imported into North America and to assess their antibiotic resistance. Kidney samples were collected from 32 freshwater ornamental fish of various species, which arrived to an importing facility in Portland, Oregon from Colombia, Singapore and Florida. Sixty‐four unique bacterial colonies were isolated and identified by PCR using bacterial 16S primers and DNA sequencing. Multiple isolates were identified as bacteria with potential to cause disease in both fish and humans. The antibiotic resistance profile of each isolate was performed for nine different antibiotics. Among them, cefotaxime (16% resistance among isolates) was the antibiotic associated with more activity, while the least active was tetracycline (77% resistant). Knowing information about the diversity of bacteria in imported ornamental fish, as well as the resistance profiles for the bacteria will be useful in more effectively treating clinical infected fish, and also potential zoonoses in the future. 相似文献