饲料中添加“健肝散”对丁桂鱼脂肪肝的影响

研究饲料中添加"健肝散"预防丁桂鱼脂肪肝病变的作用。采用"健肝散"添加量分别为0.1%、0.2%、0.4%的饲料进行丁桂鱼养殖实验,实验周期为40d,观察"健肝散"对丁桂鱼生长、血清主要生化指标的影响,以及肝脏的组织病理学变化。实验结果,当"健肝散"添加量为0.4%时,丁桂鱼的增重率、相对生长率和高密度脂蛋白胆固醇最高,肝脏脂肪含量最低,与氯化胆碱组均无显著差异(P0.05)。血清中胆固醇、甘油三酯含量最高,与氯化胆碱组有显著差异(P0.05)。谷丙转氨酶、谷草转氨酶、乳酸脱氢酶的活性较低,其中乳酸脱氢酶的活性显著低于氯化胆碱组(P0.05)。添加量为0.2%和0.4%时,肝体比均较低,与氯化胆碱组无显著差异(P0.05)。添加量为0.1%、0.2%和0.4%时,低密度脂蛋白胆固醇均较高,与氯化胆碱组无显著差异(P0.05)。肝组织病理显示,0.4%"健肝散"添加组可有效降低肝细胞的脂肪病变程度。     

Reproductive cycle of Aulacomya ater [Bivalvia: Mytilidae (Molina 1782)] in Punta Arenas Cove (Antofagasta Region,Chile)

Changes in the condition of broodstock, presence of larvae, and post-larval settlement of A. ater in Punta Arenas Cove (Antofagasta Region, Chile) were used to determine its reproductive cycle. The condition used as a spawning indicator shows that these events occur in three periods throughout the year (May–July, August–November, and December–February). Intense periods recorded in October–November and December–February coincided with periods in which the water temperature descended to less than 13 °C. Simultaneously, plankton samples indicated constant presence of A. ater larvae at this site, with large increases in abundance during August and between October and January, reaching a maximum of 2,192 larvae m^?3 in October. The periods of increase in larval abundance coincide with spawning periods; however, the greatest abundances were recorded before the start of the descent of the spawning indicator of the population under study. Monthly installation and replacement of collectors, after recording the first spawning, showed the permanent settlement of A. ater post-larvae over the course of the study, with a period of greater intensity occurring from the end of August to the end of January, registering peaks in October and November with 5,667 and 4,183 post-larvae × 600 cm² collector^?1, months which also coincide with the greatest larval abundance. The presence of larvae and post-larvae of the mytilids Choromytilus chorus and Semimytilus algosus was also recorded alongside A. ater larvae and post-larvae. Ch. chorus presented a cycle very similar to that of A. ater in both stages, with a maximum abundance of 4,531 larvae m^?3 in November and 13,533 post-larvae × 600 cm² collector^?1 in December.     

A Preliminary Study of the Nuclear Basic Proteins from Hoki [Macruronus novaezelandiae (Hector) (Merlucciidae)] Milt,an Underutilized Resource

ABSTRACT

Hoki (Macruronus novaezelandiae) (Hector) (Merlucciidae) were collected on six occasions from the fishing grounds off the west and east coasts of New Zealand. Light and electron micrographs showed that gonads were at different stages of maturity while the yields of the crude nucleoprotein extracts of the gonads from the different collection dates were similar. The crude extracts were purified by ion exchange chromatography. The molecular weights and amino acid composition of purified fractions indicated that the sperm nuclear basic proteins in hoki gonad were more like histones than protamines and were tentatively identified as histones H2A, H3, and H4.     

Egg production in the salmon louse [Lepeophtheirus salmonis (Krøyer)] in relation to origin and water temperature

Egg strings of salmon lice, Lepeophtheirus salmonis (Krøyer 1837), collected from farmed and wild Atlantic salmon had similar length and number of eggs string^?1. Egg production was investigated at water temperatures from 7.1 °C to 12.2 °C. A regression model indicated that at low temperatures egg strings were longer and had more eggs. Mean length of single eggs was significantly smaller and the percentage of non‐viable eggs in the strings was higher at 7.1 °C than at 12.2 °C. Adult females survived for up to 191 days at 7.2 °C, and during this period 11 pairs of egg strings were produced.     

Laboratory and field investigations of salmon lice [Lepeophtheirus salmonis (Krøyer)] infestation on Atlantic salmon (Salmo salar L.) post-smolts

Hatchery‐reared 1‐year‐old Atlantic salmon post‐smolts (Salmo salar L.), artificially infected with salmon lice [Lepeophtheirus salmonis (Krøyer)] copepodids, were found to suffer from primary alterations (increased cortisol levels) at early lice stages. Secondary alterations, such as osmotic stress (increased chloride levels), first occurred after the preadult stages of the lice appeared. Fish with the highest salmon lice infections died throughout the experiment. Seven years of field investigation of Trondheimsfjorden showed that Atlantic salmon post‐smolts descending coastal waters can become heavily infected with salmon lice. The migrating post‐smolts were only infected with the chalimus stages, showing that the fish had only recently left the rivers. The infection level, however, varied considerably between the years, and, in 1998, the infection was higher than previous years. The experimental results have been combined with the field data to appraise the consequences of the infection.     

Natural spawning, early development and first feeding of the semicircle angelfish [Pomacanthus semicirculatus (Cuvier, 1831)] in captivity

Successful natural spawning of Pomacanthus semicirculatus in captivity from 11 September to 18 October, 2006 is described for the first time. Each female laid an average of 230 000 eggs during the spawning period. Fertilized eggs were spherical, transparent and buoyant and had a mean diameter of 0.61 ± 0.03 mm (mean ± SD). Embryonic development lasted 18–21 h at 28.5 °C. Newly hatched larvae were 1.35 ± 0.02 mm in total length (TL) with 27 (12+15) myomeres and had an oil globule in the ventroposterior area of the yolk sac. Larvae completed yolk absorption within 3 days post hatching at 2.37 ± 0.05 mm TL. Larvae were fed either 100% microalgae ( Nannochloropsis sp.), 100% s-type rotifers ( Brachionus rotundiformis ), 100% dinoflagellates ( Gonyaulax sp.) or different combinations of the three (50%:50%:0%, 30%:35%:35%) to determine the effect of live feed on the survival rate. The survival was significantly ( P <0.001) better in larvae fed a combination of diets (30%: 35%: 35%) than others. These results indicate that P. semicirculatus is a potential species for captive-breeding programmes and the use of a combination of diets (microalgae plus s-type rotifers and dinoflagellates) may be a suitable first food for fish larvae.     

Increasing the genetic uniformity of bighead carp [Aristichthys nobilis (Richardson)] by means of spontaneous diploidization of gynogenetically activated eggs

Three groups of gynogenetic diploid bighead carp were successfully obtained by means of artificial gynogenesis. The activation rates of gynogenesis varied from 75.9% to 98.8%, and the frequency of spontaneous diploidization was around 0.4%. Over 2000 normally gynogenetic diploid fry were obtained in three gynogenetic groups. The haploid karyotype consisted of nine metacentric, 12 submetacentric, three subtelocentric chromosomes and 45 arms. The chromosome number was 48 from gynogenetic diploid. The results showed that the genetic material of offspring was maternal. The aneuploid hybrid embryos of bighead carp and Xingguo red common carp with chromosome numbers ranging from 28 to 73 did not survive post hatch, likely the result of incompatibility between the nucleus and the cytoplasm of two parents. Sixty RAPD primers from three groups were used for total DNA amplification of gynogenetic offspring, maternal and ‘paternal’ fish. A total of 451 bands were amplified from three kinds of samples above. From maternal bighead carp, 256 bands were amplified; however, there were 251 shared bands between maternal and gynogenetic bighead carp. From artificial gynogenetic offspring, two ‘paternal’ DNA segments without an expression function were found. An UPGMA tree showed that gynogenetic offspring were closely clustered and the genetic identity among them was very high (0.956).     

The effect of different numbers of feeding days on feed consumption and growth of rainbow trout [Oncorhynchus mykiss (Walbaum)]

A trial was conducted to evaluate the effects of the number of feeding days on feed consumption and growth of rainbow trout, Oncorhynchus mykiss (Walbaum) (initial mean weight 53.6 ± 11.3 g). Fish were held under natural winter–spring (40°57′N) photoperiod (L:8 D:16 – L:14 D: 10) and ambient water temperatures (4–12 °C) for 128 days, and fed on day 7 (F₇), day 5 (F_5.1: no feeding on weekends and F_5.2: no feeding on Sundays and Wednesdays) or every other day (F_EOD). Feeding treatments were replicated with 50 fish held in 200‐L tanks. Number of feeding days affected final live weight, with fish in group F₇ achieving a mean weight of 285.6 g, followed by F_5.1 (256.6 g), F_5.2 (247.6 g) and F_EOD (223.2 g). Final condition factors (CF) differed between the F_EOD group and the others. Feed conversion ratios (FCR) exhibited significant differences among some of the groups. The results suggest that depriving rainbow trout of feed for more than 1 day a week has a negative effect on growth, but little influence on feed conversion.     

Oral DNA vaccination of rainbow trout, Oncorhynchus mykiss (Walbaum), against infectious haematopoietic necrosis virus using PLGA [Poly(D,L-Lactic-Co-Glycolic Acid)] nanoparticles

A DNA vaccine against infectious haematopoietic necrosis virus (IHNV) is effective at protecting rainbow trout, Oncorhynchus mykiss, against disease, but intramuscular injection is required and makes the vaccine impractical for use in the freshwater rainbow trout farming industry. Poly (D,L-lactic-co-glycolic acid) (PLGA) is a U.S. Food and Drug Administration (FDA) approved polymer that can be used to deliver DNA vaccines. We evaluated the in vivo absorption of PLGA nanoparticles containing coumarin-6 when added to a fish food pellet. We demonstrated that rainbow trout will eat PLGA nanoparticle coated feed and that these nanoparticles can be detected in the epithelial cells of the lower intestine within 96 h after feeding. We also detected low levels of gene expression and anti-IHNV neutralizing antibodies when fish were fed or intubated with PLGA nanoparticles containing IHNV G gene plasmid. A virus challenge evaluation suggested a slight increase in survival at 6 weeks post-vaccination in fish that received a high dose of the oral vaccine, but there was no difference when additional fish were challenged at 10 weeks post-vaccination. The results of this study suggest that it is possible to induce an immune response using an orally delivered DNA vaccine, but the current system needs improvement.     

Determination of amino acid and fatty acid composition of goldband goatfish [Upeneus moluccensis (Bleeker, 1855)] fishing from the Gulf of Antalya (Turkey)

In this study, we aimed to determine the basic food components, fatty acids and amino acids, and variations in these components with months in goldband goatfish (Upeneus moluccensis) that fishing from Gulf of Antalya. As a result of the analyzes, the crude fat values were determined between 1.43 and 3.78%, and the crude protein values were determined between 20.79 and 22.16%. The most abundant fatty acids were determined: palmitic acid (C16:0), stearic acid (C18:0), palmitoleic acid (C16:1c9), oleic acid (C18:1c9), linoleic acid (C18:2n-6), eicosatrienoic acid (C20:3n-3), arachidonic acid (C20:4n-6), eicosapentaenoic acid (C20:5n-3), docosapentaenoic acid (C22:5n-6), and docosahexaenoic acid (C22:6n-3). The most abundant amino acids were determined lysine and leucine, aspartic acid, glutamic acid, alanine, and glycine. The differentiations of essential nutrient components, fatty acids, and amino acids were found generally significant (P < 0.05).

     

Spawning behaviour,early development and first feeding of the bluestriped angelfish [Chaetodontoplus septentrionalis (Temminck & Schlegel, 1844)] in captivity

Successful natural spawning of Chaetodontoplus septentrionalis in captivity from 19 March to 11 May, 2008 is described for the first time. A single male dominates a harem of two females, spawning with each at dusk, from 10 min before to 20 min after sunset. Each female laid an average 119 × 10³ eggs during the spawning period. Fertilized eggs were spherical, buoyant and had a diameter of 0.83 ± 0.02 mm (mean ± SD). Embryonic development lasted 15–18 h at 28.1 °C. Newly hatched larvae were 1.60 ± 0.07 mm in total length (TL) with 27 myomeres. Larvae completed yolk absorption within 3 days post hatching (ph) at 3.01 ± 0.08 mm TL. Ten days ph, the larvae had attained 3.95 ± 0.12 mm TL. Larvae were fed either 100% s‐type rotifers (Brachionus rotundiformis), 100% copepods (Microsetella sp.), a combination of the two (50%:50%) or without live feed (starved control) to determine the effect of live feed on the survival rate. The survival was significantly (P<0.001) higher in larvae fed a combination of diet than the others. These results indicate that C. septentrionalis is a potential species for captive breeding programs and the use of a combination of diet (s‐type rotifers and copepods) may be a suitable first food for the larvae.     

Modelling the effects of capture and sea lice [Lepeophtheirus salmonis (Krøyer)] infestation on the cortisol stress response in trout

Measuring baseline cortisol in wild salmonids is problematic because of the stress induced by most capture methods. The cortisol response to different periods of confinement stress was modelled in a laboratory population of rainbow trout [Oncorhynchus mykiss (Walbaum)]. A quadratic model was used to predict baseline (precapture) cortisol levels in these fish. A similar quadratic response pattern of cortisol was observed in wild sea trout (Salmo trutta L.). These were captured in timed sequences on four dates by seine netting in Clew Bay, west coast of Ireland. The estimated precapture cortisol for these fish indicated higher levels soon after migration to sea and a positive correlation with the level of infestation by Lepeophtheirus salmonis (Krøyer). Curvilinearity of the quadratic model was correlated with levels of lice infestation, indicating an enhanced cortisol response to confinement stress during capture when parasitic abundance was high. Estimated precapture cortisol for individual sea trout was positively correlated with numbers of lice although the linear regression had low predictive power. The method provides, for the first time, a means to estimate baseline cortisol levels in wild salmonids, and addresses one of the most difficult problems in working with wild fish. Keywords: Cortisol, trout, Lepeophtheirus salmonis (Krøyer), capture, quadratic model     

Variation in sensitivity of sea lice [Lepeophtheirus salmonis (Krøyer)] to dichlorvos on Irish salmon farms in 1991–92

Variation in sensitivity of Lepeophtheirus salmonis (Krøyer) to dichlorvos in static toxicity tests was recorded on salmon farms in Ireland. Five hour LC50s ranged from 60 to 202 μg l ^?1 at 15 °C for five farms in Autumn 1991 and 76–151 μg l^?1 at 10 °C for four farms in Spring of 1992. Resistance ratios, calculated using the most sensitive sites as baseline, were low and ranged from 1.32 to 3.27 in 1991 and 1.28–1.98 in 1992. Repeat sampling on three farms in 1991 and 1992 also indicated short‐term changes in sensitivity to dichlorvos within farms.