Genome analysis of Betanodavirus from cultured marine fish species in Malaysia

Betanodavirus is the causative agent of the viral nervous necrosis (VNN) or viral encephalopathy and retinopathy disease in marine fish. This disease is responsible for most of the mass mortalities that occurred in marine fish hatcheries in Malaysia. The genome of this virus consists of two positive-sense RNA molecules which are the RNA1 and RNA2. The RNA1 molecule contains the RdRp gene which encodes for the RNA-dependent RNA polymerase and the RNA2 molecule contains the Cp gene which encodes for the viral coat protein. In this study, total RNAs were extracted from 32 fish specimens representing the four most cultured marine fish species in Malaysia. The fish specimens were collected from different hatcheries and aquaculture farms in Malaysia. The RNA1 was successfully amplified using three pairs of overlapping PCR primers whereas the RNA2 was amplified using a pair of primers. The nucleotide analysis of RdRp gene revealed that the Betanodavirus in Malaysia were 94.5-99.7% similar to the RGNNV genotype, 79.8-82.1% similar to SJNNV genotype, 81.5-82.4% similar to BFNNV genotype and 79.8-80.7% similar to TPNNV genotype. However, they showed lower similarities to FHV (9.4-14.2%) and BBV (7.2-15.7%), respectively. Similarly, the Cp gene revealed that the viruses showed high nucleotide similarity to RGNNV (95.9-99.8%), SJNNV (72.2-77.4%), BFNNV (80.9-83.5%), TPNNV (77.2-78.1%) and TNV (75.1-76.5%). However, as in the RdRp gene, the coat protein gene was highly dissimilar to FHV (3.0%) and BBV (2.6-4.1%), respectively. Based on the genome analysis, the Betanodavirus infecting cultured marine fish species in Malaysia belong to the RGNNV genotype. However, the phylogenetic analysis of the genes revealed that the viruses can be further divided into nine sub-groups. This has been expected since various marine fish species of different origins are cultured in Malaysia.     

Histochemical and morphometric studies of the cranial tibial muscle in dogs of different dynamic aptitudes (greyhound, German shepherd and fox terrier)

A histochemical and morphometric study of the cranial tibial muscle of the greyhound, the German shephard and the fox terrier was carried out using hematoxyline-eosin, PAS, Gomori trichrome, SDH, LDH, NADH-tr and ATPase staining (with pH adjustments to both acidic and basic levels), with the goal of comparing the proportion and distribution of type I and type II fibers within the muscle. Significant differences were found between the three breeds of dogs. It is suggested that these differences are related to the locomotor activities of the three breeds.     

Influence of supraphysiological cortisol manipulation on predator avoidance behaviors and physiological responses to a predation threat in a wild marine teleost fish

The stress axis in teleost fish attempts to maintain internal homeostasis in the face of allostatic loading. However, stress axis induction has been associated with a higher predation rate in fish. To date, the physiological and behavioral factors associated with this outcome are poorly understood. The purpose of the present study was to investigate the impact of experimental cortisol elevation on anti‐predator behavior and physiological responses to predator presence. We hypothesized that semi‐chronic cortisol elevation would increase susceptibility to predation by increasing stress‐induced risk‐taking behaviors. To test this hypothesis, schoolmaster snapper were given cocoa butter implants without cortisol (sham) or with cortisol (50 mg/kg body weight) and tethered to cover. Fish were exposed to either a lemon shark or control conditions for 15‐min. Space use and activity were recorded throughout and fish were terminally sampled for blood. Cortisol implantation, relative to shams, resulted in higher blood glucose and plasma cortisol concentrations with a lower plasma lactate concentration. Shark exposure, relative to controls, elicited higher blood glucose and lactate concentrations but had no effect on plasma cortisol concentration. No interactions were detected between shark exposure and cortisol treatment for any physiological trait. Behavioral metrics, including shelter use and activity, were unaffected by either cortisol implantation or shark exposure. Physiological responses to cortisol implantation likely resulted from enhanced gluconeogenic activity, whereas alterations under predator exposure may have been the product of catecholamine mobilization. Further work should address context‐specific influences of stress in mediating behavioral responses to predation.     

全球鱼类和水产品前瞻

1市场和价格鱼类及鱼产品价格总体下行。由于需求减少．只有那些产量供应紧张的品种才幸免于这场价格下跌风暴．包括野生白鱼和黄鳍金枪鱼、养殖三文鱼和罗非鱼．价格仍趋稳定。其他养殖品种．如欧洲鲷和大菱鲆价格创历史新低,原因是产量大幅增长。另一方面．越南鲶鱼价格尽管在2008年初下跌．不过正在恢复中上涨。     

Histochemical and morphometric characterization of broncho-pneumonia in calves caused by infection with Mycoplasma bovis

The aim of this study was to identify morphometric histological features of pneumonia caused by Mycoplasma bovis in calves. Eight three-month-old calves were infected with M. bovis and samples of their lung tissue, three weeks after exposure, compared to samples from four uninfected calves. In the uninfected animals the goblet cells were clustered in the crypt area of the epithelial folds, while in the infected calves they had migrated towards the tips of the folds and were distributed evenly throughout the folds. In infected lung tissue there was goblet cell hyperplasia and metaplasia in the bronchioles and an increased epithelial height. Goblet cell mucin in uninfected calves was acidic, but in infected calves most goblet cells contained neutral mucins. These morphometric and histochemical bronco-epithelial changes may be able to be used as markers of the severity of bovine respiratory mycoplasmosis.     

Animal welfare aspects of the killing of fish

According to the Animal Protection Law (1986) fish are to be killed by methods which do not cause pain. However, the regulations do not cover the killing of non-food fish. A questionnaire, conducted among 85 fish scientists, revealed that single fish should be killed by a blow on the head, and larger numbers by electrical methods or by use of chemicals. Decapitation was proposed for eels. A regulation from 1936 stipulates the methods for the slaughtering of food fish. Mechanical or electrical stunning is compulsory except for eel and flatfish. The questionnaire showed that in general the present legal regulations are sufficient for the slaughtering of fish with the exception of eels. The commercially available apparatus for stunning and killing do not always fulfill the requirements of animal protection, slaughtering technology and safety for the user. Official testing of these apparatus as well as the evaluation of new methods--like CO2-stunning--are necessary in order to prevent the use of methods which are feasible, but do not fulfill animal welfare, especially for eel.     

鱼油在水产饲料中的应用

鱼油是湿法加工鱼粉过程中的副产品,是将海洋鱼类及其废弃物经蒸馏、压榨和精炼而得到,以脂肪形式存在于鱼肉中或以分散油形式存在于鱼体内的油脂。鱼油的主要成分是甘油三脂,此外还含有少量类脂、磷甘油醚、脂溶性维生素以及蛋白质降解物等,其中磷脂主要由磷脂酰胆碱和磷脂酰乙醇胺组成。与一般动植物油脂相比,鱼油中大部分脂肪酸具有较长的碳链和多元不饱和度,长链脂肪酸通常占总脂肪量的1/4￣1/3,有时高达1/2,其中5￣6个双键的脂肪酸通常占鱼油的15%￣30%,尤其以n-3系列的高度不饱和脂肪酸(H U FA),如二十碳五烯酸(E PA)和二十二碳六…     

Effect of heat-inactivated fish and non-fish derived probiotics on the innate immune parameters of a teleost fish (Sparus aurata L.)

The in vitro effects of four heat-inactivated bacterial species on the cellular innate immune responses of the gilthead seabream (Sparus aurata L.) were investigated. Head-kidney leucocytes were isolated and incubated for 30 min with two bacteria isolated from seabream skin (Pdp11 and 51M6; members of the Vibrionaceae and in the genus Shewanella) and two bacteria used as probiotics in humans and cattle (Lactobacillus delbrüeckii subsp. lactis and Bacillus subtilis) at 5 x 10(5), 5 x 10(6) or 5 x 10(7)CFU/ml. After incubation, different cellular innate immune parameters (leucocyte peroxidase content, phagocytosis, respiratory burst activity and cytotoxicity) were evaluated. The leucocyte peroxidase content was significantly higher after incubation with 51M6 at 5 x 10(7)CFU/ml. Head-kidney phagocytes were able to engulf the four bacterial species in all four cases, L. delbrüeckii subsp. lactis and B. subtilis being the most actively phagocytized. The incubation of seabream leucocytes with 51M6, L. delbrüeckii subsp. lactis and B. subtilis resulted in a great increase in respiratory burst activity. Cytotoxic activity was generally stimulated in a dose-dependent manner, the enhancement obtained with 5 x 10(7)CFU/ml being statistically significant. The usefulness of in vitro assays for screening and selecting candidate probiotic bacteria, as well as for optimising their effective dose, is discussed in relation with their immune-modulatory properties.     

Seasonal changes in the humoral immune response and the lymphoid tissues of the marine teleost, Sebastiscus marmoratus

Seasonal modulation in antibody production in relation to the state of lymphoid tissue development was studied in the ovoviviparous fish, S. marmoratus. Animals were kept in tanks with running seawater at 23 +/- 1 degrees C for a minimum 2 week acclimatization period and then immunized three times at 2 day intervals with 20% SRBC (5 microliters/g body weight) intraperitoneally. Immunized fish were bled 2 weeks after the first injection at the time of peak response and plasma were analyzed for titration. The thymus and pronephros were weighed and the number of leukocytes counted in the cell suspension. Antibody levels in fish immunized in summer were higher than those in fish immunized in winter, even if the environmental temperature was held constant. Furthermore, the reactivity of mature females to SRBC was lower than that of males or immature females in the spawning season (winter). The antibody titre was inversely related to the weight of the thymus with the exception of females during the spawning season, while the weight of the pronephros did not show any significant change throughout the year. In addition, the thymus of pregnant, and especially post-spawning females, was entirely involuted, showing a marked decrease in the number of lymphocytes in both the cortex and medulla. Preliminary experiments to examine the effect of photoperiod on antibody production indicated a slight increase in titre among adult fish under a long photoperiod regimen. The present data show that both the season and stage of sexual maturity affect the humoral immune response and lymphoid tissues, and suggest that the thymus might have a function other than that concerned with immunity.     

Antigenic properties and experimental transmission to several fish species of a marine birnavirus isolated from sole (Solea senegalensis).

A cross-neutralization test was used to study the antigenic relationship of an aquabirnavirus isolated from sole (Solea senegalensis), named solevirus, and several infectious pancreatic necrosis virus (IPNV) strains. Solevirus was antigenically similar to IPNV strain Sp. Transmission of the solevirus to other fish species has been determined by inoculation to freshwater and marine fish species (two salmonids and gilt-head seabream). A higher pathogenicity was obtained for the marine fish species, although solevirus caused an asymptomatic infection in all species tested, as demonstrated by the detection of viral RNA and of viral antigens in fish leucocytes, respectively, using polymerase chain reaction (PCR) and flow cytometry (FC).     

Wound management in teleost fish: biology of the healing process, evaluation, and treatment.

Wound healing, although similar to terrestrial vertebrates, occurs faster in fish species in a proper aquatic environment. Wound management must involve identification and correction of potential noninfectious and/or infectious causes of disease. Wound evaluation includes assessment of the wound as well as systematic examination of the patient, water quality conditions, and husbandry practices. Diagnostic evaluation should, at a minimum, include physical examination, skin/cornea (if indicated) scraping, and lesions cultures. The clinician should also consider full thickness wound biopsies, gill and fin biopsies, blood collection, and radiographs for systemic evaluation as well. Local wound management should follow basic principles of wound care including cleaning and lavage, debridement, primary closure if indicated, and local and/or systemic antiinfectives. Monofilament absorbable or nonabsorbable sutures are commonly used for primary closure of wounds. Diagnostic results, patient and client compliance, and economic impact should guide systemic methods of treatment for wound care. Options for systemic therapy include oral or gavage, parenteral, bath, or prolonged immersion treatments. With bath or prolonged immersion therapies, aquatic systems must be properly prepared for treatment. Treatment of identified pathogens, proper water quality and husbandry, supportive care and nutrition must all be provided to promote an ideal wound healing environment for the teleost fish.     

Radiodiagnostic examination of the swimbladder of some fish species

Radiodiagnostic methods have not been used previously for studying the anatomy and diseases of the swimbladder of freshwater fish species. In this study, the radiographic anatomy of the swimbladder and species-related differences in swimbladder structure were studied on plain radiographs taken of 12 Hungarian fish species of major economic importance. Changes observed by radiography were also studied by conventional parasitological methods. The radiodiagnostic method reported here appears to be a useful complement to diagnostic examinations that have been based merely on dissection so far. It enables evaluation of the pathological lesions in live condition, without causing damage to the fish.