Muscle growth of triploid Atlantic cod juveniles (Gadus morhua)

This study has investigated the muscle growth of diploid and triploid Atlantic cod (Gadus morhua) juveniles raised in replicate tanks over a period of 29 weeks and analysed at three sampling points (February, June and September). Data for weight, length, condition factor (K), muscle fibre growth and myogenic progenitor cells (MPCs) number were collected and results were analysed in relation to body growth and ploidy status. Diploids were significantly heavier than triploids throughout the trial (~10–20%) and had K in June and September samplings. Over the whole period, the rate of muscle fibres' recruitment was 318 fibres per day and 252 fibres per day for diploid and triploid cod respectively. The larger body weight of diploids resulted in a total number of fast fibre number of 114 979 compared to 91 086 in triploids. The average diameter of the 2.5% of the smallest fibres (2.5th percentile) was higher in diploids than triploids at the start of the trial, with a reversed picture for the average of the upper 2.5% (97.5th percentile) at the end of the trial. The probability density function of the estimated muscle fibre diameters showed similar fibre size distribution between size‐matched diploids and triploids at all sample points. The peak fibre diameter was approximately 25 μm in February and increased to approximately 50 μm in June and September, irrespectively of ploidy. Pax 7 were used as molecular markers for MPCs. A positive correlation between Pax 7⁺ cells and total body length was observed only among triploid fish at the onset of the experiment.     

冷冻贮藏对凡纳滨对虾肌肉质构特性的影响

采用质构仪TPA模式对冷冻贮藏条件下凡纳滨对虾（Litopenaeus vannamei）肌肉的硬度、黏附性、弹性、咀嚼性、胶黏性和凝聚性等进行了测试。结果显示,在-18℃和-50℃的贮藏条件下,随着贮藏期的延长,凡纳滨对虾肌肉的硬度、咀嚼性、胶黏性和凝聚性均呈现缓慢下降的趋势,弹性的变化不明显,而黏附性则有所上升。这表明冷冻贮藏凡纳滨对虾虽然能保证其较长的货架期,但其口感特征总体上持续下降,而温度越低越有利于保持其肌肉的质构特性。     

大西洋鲑、三倍体虹鳟和金鳟的肌肉营养成分与品质特性

为了解大西洋鲑(Salmo salar)、三倍体虹鳟(Oncorhynchus mykiss)、金鳟(Oncorhynchus mykiss)3种鱼肌肉营养成分和品质特性,利用生化分析、物性分析方法分析3种鱼肌肉的营养成分、氨基酸和脂肪酸组成、肉色、系水力和质构特性。结果表明,大西洋鲑、三倍体虹鳟、金鳟肌肉的水分质量分数分别为62.91%、67.15%、73.02%,粗蛋白质量分数分别为22.39%、21.03%、22.11%,粗脂肪质量分数分别为14.64%、17.16%、5.11%。3种鱼肌肉的滴水损失、黄色值(b~*)、羟脯氨酸含量、内聚性均显著不差异(P0.05)。3种鱼肌肉的硬度和咀嚼性由低到高依次为大西洋鲑、三倍体虹鳟、金鳟,而pH值的结果则与之相反(P0.05)。大西洋鲑和三倍体虹鳟肌肉的灰分、解冻损失、蒸煮损失、回复性、弹性和红色值(a~*)差异不显著(P0.05),但灰分、蒸煮损失、回复性均小于金鳟肌肉的对应指标(P0.05),弹性和红色值(a~*)则均大于金鳟肌肉的对应指标(P0.05)。大西洋鲑、三倍体虹鳟、金鳟肌肉中必需氨基酸含量占氨基酸总量分别为42.28%、41.84%、41.63%(质量分数),必需氨基酸/非必需氨基酸(EAA/NEAA)比值分别为73.25%、71.94%、71.32%,均符合联合国粮农组织/世界卫生组织(FAO/WHO)对优质蛋白质的评价标准;3种鱼肌肉中均检测到22种脂肪酸,组成丰富,其中不饱和脂肪酸含量较高。综上所述,3种鱼的肌肉都是符合人体营养需求的优质水产品,其中大西洋鲑和三倍体虹鳟肉质接近,且都优于金鳟的肉质。     

Post-mortem degradation of the muscle tissue in diploid and triploid turbots (Scophthalmus maximus L.)

Structural and ultrastructural muscle changes were studied throughout post-mortem degradation in diploid (2N) and triploid (3N) 22-month-old turbots (Scophthalmus maximus L.). Textural changes were also studied. Muscle degradation was fast in 2N and 3N turbot, as indicated by detachment of myofibrils from the sarcolemma and swollen organelles from day one post-mortem onwards. Interfibrillar and intermyofibrillar spaces, disruptions in sarcolemma-endomysium and autophagic vacuoles increased after 3 days in both fish groups. The percentage of interfibrillar detachments increased from 3 to 7 days in 2N and 3N, remaining constant until 14 days post-mortem, whereas the autophagic processes were more marked after 7 days. Post-mortem muscle alterations were stronger in the triploid group. Thus, the autophagic mechanisms and the percentage of interfibrillar detachments were higher in triploid than in diploid turbot. Hardness was not affected by ploidy or post-mortem stages.     

Reproductive ability of triploid ornamental (koi) carp (Cyprinus carpio L.) × goldfish (Carassius auratus L.) hybrids and characteristics of their offspring

The purpose of this study was to investigate reproductive ability of backcross triploid koi (Cyprinus carpio L.) × goldfish (Carassius auratus L.) hybrids. These triploids have been obtained by crossing of F₁ hybrid females producing diploid eggs with males of parental species. Triploid hybrid females, when crossed with goldfish or koi males, produced mostly aneuploid fish with ploidy range from approximately 2.2n–3.2n with a mean value 2.5n; some fish in crosses of triploid females with koi males were tetraploid (4.0n). Since analysed fish had in their genomes one haploid set from parental males, the data indicate that triploid hybrid females mostly produced aneuploid eggs with ploidy range from approximately 1.2n–2.2n and a mean ploidy around 1.5n while some eggs were triploid. Triploid hybrid males were completely sterile and have not released any sperm after hormonal injection. Despite their low viability, some aneuploid fish obtained from triploid hybrid females were raised in indoor recirculating systems until the age of 2 years and their reproductive ability has been evaluated. One aneuploid female with ploidy 2.1n produced larvae with ploidy range from 2.9n to 3.4n with a mean ploidy of 3.1n when crossed with a koi male; about 60% of obtained larvae had ploidy from 3.0n to 3.2n. These data indicate that this female produced mostly eggs with unreduced ploidy level.     

不同倍性长牡蛎闭壳肌和精子的组织学和超微结构观察

以二倍体、三倍体、四倍体长牡蛎(Crassostrea gigas)闭壳肌和精子为研究对象, 采用石蜡组织切片、透射电镜和扫描电镜方法, 比较了 3 种倍性长牡蛎闭壳肌和精子的组织学特性及超微结构的差异。研究结果显示, 二、三、 四倍体闭壳肌组织的肌纤维都包含粗肌丝、细肌丝、肌膜、肌束膜、肌内膜、线粒体、囊泡、小管、细胞核、肌浆网等结构, 但三者的形态及超微结构不同, 其中三倍体闭壳肌线粒体直径、肌纤维直径、粗肌丝密度显著大于二倍体和四倍体, 肌纤维密度显著小于二倍体和四倍体。不同倍性精子的扫描电镜和透射电镜结果显示, 二、三、四倍体长牡蛎精子在组成结构上相似, 分别由头部、中段和尾部构成, 但不同倍性精子中各结构大小和线粒体数目不同。在长牡蛎精子头部长度、宽度, 顶体高度、宽度, 线粒体长度的测量分析中, 四倍体精子的头部、顶体以及线粒体显著大于二、三倍体。三倍体精子的头部和顶体显著大于二倍体, 但三倍体精子的线粒体大小与二倍体相比无显著差异。此外, 二、三倍体精子均含 4 个线粒体, 但在本研究中发现了二倍体精子含有 5 个(占比 1%)线粒体的特例。四倍体长牡蛎精子的线粒体数目不同, 含有 4 个(占比 46%)、5 个(占比 52%)、6 个(占比 2%)这 3 种情况。 该研究阐明了不同倍性长牡蛎闭壳肌及精子的组织学特性和超微结构, 为深入研究长牡蛎肌纤维生物学特性和精子繁育生物学提供了基础资料。     

Skeletal anomaly assessment in diploid and triploid juvenile Atlantic salmon (Salmo salar L.) and the effect of temperature in freshwater

Triploid Atlantic salmon tend to develop a higher prevalence of skeletal anomalies. This tendency may be exacerbated by an inadequate rearing temperature. Early juvenile all‐female diploid and triploid Atlantic salmon were screened for skeletal anomalies in consecutive experiments to include two size ranges: the first tested the effect of ploidy (0.2–8 g) and the second the effect of ploidy, temperature (14 °C and 18 °C) and their interaction (8–60 g). The first experiment showed that ploidy had no effect on skeletal anomaly prevalence. A high prevalence of opercular shortening was observed (average prevalence in both ploidies 85.8%) and short lower jaws were common (highest prevalence observed 11.3%). In the second experiment, ploidy, but not temperature, affected the prevalence of short lower jaw (diploids > triploids) and lower jaw deformity (triploids > diploids, highest prevalence observed 11.1% triploids and 2.7% diploids) with a trend indicating a possible developmental link between the two jaw anomalies in triploids. A radiological assessment (n = 240 individuals) showed that at both temperatures triploids had a significantly (P < 0.05) lower number of vertebrae and higher prevalence of deformed individuals. These findings (second experiment) suggest ploidy was more influential than temperature in this study.     

Effect of triploidy on quality traits of shi drum (Umbrina cirrosa L.) until the second rearing year

Carcass and flesh morphometric, reological and chemical traits of triploid (3n) and diploid (2n) shi drum (Umbrina cirrosa L.) were evaluated through 7 months. Three age groups, 17‐, 21‐ and 24‐month‐old fish, were investigated. The effects of ploidy were statistically evaluated and the weight of fish was included in the model as a covariate because triploids grew less than diploids. As expected, fish weight was found to be significantly correlated with all the investigated morphometric traits, but showed a negative correlation with some chemical (pH) and colour traits (lightness) of raw fillet. In comparison with controls, triploid shi drums were characterized by different morphological traits that involved a slender body shape. In triploids, a reduction in condition factor, backbone weight, dressing index and an increase in the agility index were also recorded. When the commercial size (i.e. over 300 g) was achieved, triploids exhibited larger coelomatic and fillet (dorsal white muscle) fat deposition than diploids. Among reological traits, colour and texture were affected by ploidy; raw fillet lightness and cooked flesh tenderness were higher among triploids in all the investigated age groups. As fish were fed with a restricted feeding regimen, fillet fat deposition was supposed to be limited. Thus, the effects of ploidy on reological traits may be only partially explained by lipid fillet amount and are supposed to be more related to different fibre muscle architecture.     

Growth and gut morphology of diploid and triploid juvenile Atlantic cod (Gadus morhua)

The objective of this paper was to compare the growth and gut morphology of juvenile diploid and triploid Atlantic cod (Gadus morhua) reared under similar conditions. Individually tagged 36‐week‐old diploid (mean weight 49.3 ± 13.8 g) and triploid (mean weight 43.6 ± 11.2) juvenile cod were measured at intervals during a 29‐week growth trial. Data for weight, length, condition factor (K), hepato‐somatic index (HSI), gonado‐somatic index (GSI), Relative Gut Length (RGL) and pyloric caeca number were collected and results were analysed in relation to ploidy status, gender and family contribution. At the end of the experiment, only one family (M2xF3) had many representatives with a relatively even distribution of sexes and ploidies. Diploid females were significantly heavier and had higher K than triploid females in the M2xF3 family (body weight 371.2 ± 120.2 vs. 298.4 ± 100.7 g; K 1.1 ± 0.1 vs. 0.93 ± 0.1), but no differences were found between diploid and triploid males. In the other families (pooled data), no differences in body weight were found between the ploidy groups. In general, triploids had a shorter intestine (RGL) and fewer pyloric caeca than their diploid siblings regardless of gender suggesting possible impairments in nutrient utilization and growth.     

Seasonal changes in muscle structure and flesh quality of 0+ and 1+ Atlantic salmon (Salmo salar L.): impact of feeding regime and possible roles of ghrelin

Growth performance, muscle cellularity, flesh quality, and plasma ghrelin were investigated in 0+ and 1+ farmed Atlantic salmon (Salmo salar L.) from 40 g to 4.3 kg. Reduced meal frequency was introduced in both smolt groups from ~1.5 kg; one meal per second day (<5 °C) to one daily meal (>5 °C), while control groups were fed one to three daily meals. Results show that 0+ salmon had higher final fibre number and density, pigment content, red colour intensity, firmer flesh, and lower fillet fat content than 1+ salmon at 4.3 kg, affected by season and smolt type. Muscle fibre recruitment was an important determinant of fillet firmness and colour, possibly influenced by the prenatal temperature regime. Fish fed reduced meal frequency showed temporal reduced feeding ration, but growth performance was not compromised in any smolt groups at harvest. However, fillet fat, gaping, and colour decreased by less frequent feeding, with permanent effects in 1+ salmon for gaping and fat. Reduced meal frequency is therefore considered to be a promising tool for managing important flesh quality attributes in salmon without compromising growth performance. It is also suggested that ghrelin stimulates short‐term appetite, and perhaps also in the longer term.     

The influence of anaerobic muscle activity,maturation and season on the flesh quality of farmed turbot

In order to test seasonal, rearing, maturing and anaerobic muscle activity effect on the flesh quality of turbot (Scophthalmus maximus) a total of 80 farmed turbot from three different strains from reared under natural or continuous light were killed by a percussive blow to the head in November (winter, Icelandic strain), March (spring, Portuguese strain) and June (summer, domesticated strain (France turbot)). To test the effect of anaerobic muscle activity, 10 fish were on each occasion pre rigor filleted, where one fillet was used as a control, while the other fillet was electrically stimulated using a squared 5 Hz, 10 V pulsed DC for 3 min. All pre rigor fillets were measured for pH, weighed, wrapped in aluminum foil and stored in polystyrene boxes with ice. After 7 days of storage the fillets were measured instrumentally for pH, drip loss, colour (CIE L* a* b*) and texture properties such as hardness and shear force, while fillet shrinkage and colour (RBG) were evaluated with computer imaging on photographs from a standard lightbox. Results showed that softness of the flesh was mainly influenced by factors associated with growth, such as season, photoperiod and maturation. Anaerobic muscle activity simulated with electrical stimulation caused an increase in drip loss (<1%) and loss of shear force (<4%), but had no effect on hardness or fillet shrinkage. Computer imaging revealed that muscle contractions related to the electrical stimulus forced out blood from the fillet causing less reddishness for the entire storage period. We conclude that a pH drop upon slaughter associated with anaerobic muscle activity has a minor effect on the flesh quality in the short run, while seasonal/alternatively genetic effects are predominant.     

二次杀菌条件对凡纳滨对虾软烤虾品质的影响

通过基于栅栏效应的工艺将凡纳滨对虾加工成高水分软烤虾,对产品进行二次杀菌,测定不同杀菌条件下软烤虾的色泽、质构、p H值、感官品质,并判定是否处于商业无菌状态。结果表明,随着杀菌温度的增加,L*值、a*值与b*值均呈现下降趋势,随杀菌时间增加,L*值略有下降,a*值与b*值略有上升。杀菌温度上升,硬度、胶粘性、咀嚼性、弹性在一定范围内先上升再下降;而粘附性一直上升,内聚性一直下降但变化相对较小,最大剪切力的整体趋势也下降。杀菌时间增加,硬度、粘附性与咀嚼性升高,内聚性与最大剪切力下降,胶粘性先下降再上升,而弹性先上升再下降。软烤虾的p H值随着杀菌温度升高变化较复杂,但杀菌时间增加时p H值上升。当杀菌条件为90℃·(30 min)-1时,软烤虾的感官品质最好,并且达到商业无菌状态。     

Comparison of Post‐mortem Mass Changes in Myosin Heavy Chain and Textural Characteristics among Oncorhynchus mykiss (Walbaum, 1972), Salmo trutta fario (Linnaeus, 1758) and Salvelinus fontinalis (Mitchill, 1814)

In this study, post‐mortem myofibril proteins change in myosin heavy chain (MHC) mass using sodium dodecyl sulphate‐polyacrylamide gel electrophoresis (SDS‐PAGE), texture properties such as hardness, stickiness, cohesiveness, elasticity, chewiness, gumminess and stress relaxation test parameters (Fmax, Fmin and Fmax‐Fmin) were determined and compared on the days 0, 3, 6 and 9 in three different trout species (Oncorhynchus mykiss, Salmo trutta fario and Salvelinus fontinalis). In terms of texture properties, post‐mortem hardness, cohesiveness, elasticity, chewiness and gumminess were decreased day by day, whereas stickiness, Fmax, Fmin and Fmax‐Fmin were significantly increased (p < .05). According to SDS‐PAGE results, a decreased value on MHC was determined (p < .05). Texture properties and SDS‐PAGE results were found different among groups (p < .05). Correlation between chewiness, gumminess, MHC and hardness; between chewiness and gumminess; between Fmin, Fmax‐Fmin and Fmax; between Fmin and Fmax‐Fmin were significant. As a result of the study, S. fontinalis exhibited least deterioration in comparison with other species and it was determined that SDS‐PAGE results and texture properties support each other.     

Oxidative effect of l -carnitine on energy metabolism in diploid and triploid rainbow trout ( Oncorhynchus mykiss ): impact on metabolites

l-Carnitine plays a key role in the regulation of energy metabolism and growth in fish. The aim of this study was to determine the effects of dietary l-carnitine levels on carnitine homeostasis and energy metabolism in diploid and triploid trout (Oncorhynchus mykiss). Diploid and triploid trout (29.5 ± 0.6 and 31.8 ± 0.5 g, respectively) were fed with three diets supplemented with 15, 200 or 530 mg l-carnitine/kg, respectively, for 56 days. Compared to 15 mg l-carnitine, total carnitine content increased in the liver by 182% in diploid and by 154% in triploid trout fed 530 mg l-carnitine. In muscle, total carnitine content increased by 60 and 73% in diploid and by 34 and 75% in triploid with the increase in dietary l-carnitine levels. l-Carnitine caused no significant change in the plasma concentrations of metabolites like proteins (ammonia, urea and protein), lipid (triglycerides), carbohydrate (glucose, lactate) and enzyme activities (lipase, lactate, alanine transaminase, lactic acid dehydrogenase). Triploid trout had significantly lower plasma ammonia (P = 0.003), lipase (P = 0.005) and triiodothyronine (T3; P = 0.003) levels than diploid trout. In conclusion, ploidy significantly affected the energy metabolism in rainbow trout, dietary l-carnitine levels altered the l-carnitine homeostasis, but not influence nutritional metabolism.     

Flesh quality of Atlantic salmon smolts reared at different temperatures and photoperiods

Possible interactive effects of temperature and photoperiod on flesh quality in Atlantic salmon post‐smolts were studied. Juvenile (initial mean weight 96.0 g ± 3.1 SEM) Atlantic salmon were reared at six different combinations of temperatures (4.3, 6.5 or 9.3°C) and photoperiods (continuous light or simulated natural photoperiod). At termination of the trial, the fish were slaughtered and flesh samples taken to investigate quality and textural properties in the different experimental groups. Final weight in the six experimental groups varied between 174 and 345 g. Softer texture was seen in the fast growing groups. Photoperiod has only minor effect on flesh quality and textural properties, whereas temperature had significant impact on most of the measured variables. Although positive for growth, higher temperatures might be less favourable in relation to softer muscle tissue.     

不同养殖模式对斑点叉尾鮰生长和肌肉品质特性的影响

为探究不同养殖模式下斑点叉尾鮰的生长性能和肌肉品质特性,随机选取传统池塘（TP）、高密度循环水系统（HD-RAS）和水泥池塘（CP）养殖模式下的鲜活斑点叉尾鮰,测定其生长状况,以及肌肉营养成分、颜色、持水力和质构特性。结果显示,TP和HD-RAS的斑点叉尾鮰的增重率和特定生长率差异不显著,但均高于CP;CP的肝体比（2.35%±0.22%）显著高于TP和HD-RAS;与TP相比,HD-RAS和CP肌肉的粗脂肪含量更低,粗蛋白和灰分含量更高;HD-RAS肌肉的亮度值（L*）（58.18±3.56）、红度值（a*）（6.05±1.08）最高,CP最低,分别为48.15±6.04和4.81±0.84;传统池塘养殖的斑点叉尾鮰熟肉率最低,离心损失、滴水损失和失水率最高,HD-RAS和CP之间差异不显著;HD-RAS和CP肌肉的硬度、咀嚼性和弹性显著高于TP,但3处理组间的内聚性和回复性没有显著差异。研究表明,与传统池塘养殖模式相比,水泥池塘养殖模式易造成斑点叉尾鮰生长减慢,而高密度循环水养殖模式对斑点叉尾鮰生长性能没有显著影响,并且在该养殖模式下肌肉具有更高的持水力、质构特性,同时呈现高蛋白、低脂肪的营养特点。     

Differences in metabolism of triploid and diploid Salmo trutta f. lacustris under acclimation conditions and after exposure to stress situations

Differences in metabolism (enzyme activities, metabolites) between diploid and triploid Salmo trutta f. lacustris were investigated under acclimation and stress conditions. Under acclimation conditions enzyme activities differed for 35% of the 27 investigated key regulatory enzymes and temperature optima for 23%. Muscle and liver metabolites related to energy metabolism and diagnostic indices of blood serum were similar, with exception of acetyl‐CoA being increased in triploids. Metabolic rate was lower and gill ventilation rate higher in triploids in comparison with diploids. During the tested stress situations (24 hr endurance swimming, 3 hr exposure to hypoxia in water with 32% oxygen saturation) muscle and liver glycogen decreased and serum and muscle lactate increased in both ploidy levels. Specifically, for triploids muscle adenylate energy charge and phosphocreatine levels decreased after endurance swimming and muscle and liver adenylate energy charge after exposure to hypoxia. Acetyl‐CoA increased in triploids during both stress situations. In summary, there existed differences in metabolism between the two ploidy levels and the energy metabolism of triploids was less balanced under stress.     

Comparative performance of growth,vertebral structure and muscle composition in diploid and triploid Paralichthys olivaceus

Growth, skeletal structure and muscle composition of cold‐shock‐induced triploid olive flounder Paralichthys olivaceus were investigated. The average values of total length and total weight of triploids were higher than those of diploids from 5 to 11 months posthatch (mph). The growth difference disappeared after 11 mph. The skeletal structure of flounder at 11 mph was observed by X‐ray imaging method. There are four kinds of vertebral deformity including vertebrae fusion, one‐sided compression, two‐sided compression and vertically shifted. The trunk region (V8–18) and tailing end of the vertebral column were the predominant locations of deformity. In general, the frequencies of vertebral deformities in triploids (60.0%) were higher than those in diploids (33.3%, p < 0.05). Both the number of fish with deformed vertebrae and the average frequencies of deformed vertebrae in triploids were significantly higher than those in diploids (p < 0.05). The muscle tissues of diploid and triploid flounder at 11 mph contain the same types of fatty acid and free amino acid profiles. The number of fatty acids with significant higher contents in diploids and triploids was one and ten, respectively (p < 0.05). The contents of free amino acids showed no difference between triploid and diploid fish.