Chemical constituents in the abdominal muscle of cultured mud crab Scylla serrata in relation to seasonal variation and maturation

ABSTRACT:     Seasonal changes in levels of chemical constituents in the abdominal muscle of male and female mud crab Scylla serrata were investigated. The gonadosomatic index in the female crab was higher in October and August, of which the muscle yield, glycogen, and total amount of adenosine 5'-triphosphate (ATP)-related compounds (ARC) in the October sample were the highest throughout the year, but the total amount of free amino acids (FAA) was the lowest. The total FAA and individual FAA such as glycine, alanine, and arginine increased in the August and November female samples, while that in the male specimens was higher in January, March, and August. The total ARC in both crabs was lower in the samples collected from winter than in other seasons whereas glycinebetaine was higher in winter and early spring. Glutamic acid, glycine, alanine, arginine, glycinebetaine, and adenosine monophosphate might be responsible for the taste of mud crab. Their level together was relatively higher in the August and January male samples, and in the August and November female specimens. However, the correlation between the taste component content and degree of gonad maturation was low.     

Utilization of free amino acids, yolk proteins and lipids in developing eggs and yolk-sac larvae of walleye pollock Theragra chalcogramma

ABSTRACT:   To elucidate the utilization of the major yolk nutrient stocks in eggs and larvae of walleye pollock Theragra chalcogramma , the contents of free amino acids (FAA), the major yolk protein (180 kDa lipovitellin originated from vitellogenin B in ovulated eggs: oLv B), and lipids were measured. Most eggs hatched 18 days after fertilization at 5°C, and all larvae absorbed almost all their yolk mass by 28 days. The total FAA content showed no change during the first 6 days, and then decreased to 28% of the initial level by 18 days. The oLv B contents, measured by an enzyme-linked immunosorbent assay using a specific antiserum against oLv B, gradually decreased from 6 to 18 days, followed by a rapid decline. The content of phospholipids (PL) and triacylglycerols (TG) showed no marked change until hatching, and then decreased until disappearance of yolk sac. From these results, it is proposed that there are two main periods for nutrient utilization in embryos and larvae of walleye pollock. In the first period, FAA was mainly utilized until 18 days after fertilization. Active utilization of oLv B and lipids (PL and TG) instead of FAA occurred during the second period from 18 to 28 days.     

Augmentation of free amino acids in eggs of red snapper,Lutjanus campechanus as part of the induced spawning protocol

An attempt was made to increase free amino acids (FAA) concentrations in eggs of red snapper Lutjanus campechanus as part of an induced spawning protocol. Mature female red snapper were given intramuscular injections of human chorionic gonadotropin (HCG) at a 1100 IU kg^?1 of female body weight. Immediately after the HCG injection, one set of females received an intramuscular injection of FAA in a buffered saline solution at a dose of 20 mg FAA cocktail kg^?1 of body weight. The FAA cocktail was 25% isoleucine, 25% leucine, 25% lysine and 25% valine on a molecular weight basis. A second set of fish did not receive the FAA supplement. Both sets of fish were equally successful in spawning with ovulation occurring 21–32.5 h post injection. Injection of FAA into brooders as eggs began final maturation and hydration resulted in an increase in leucine (nmoles mg egg^?1) and a slight increase in isoleucine (nmoles egg^?1) in recently ovulated eggs. FAA supplementation via brood injection altered FAA utilization rates by embryos and during larval development, resulted in a greater yolk sac and oil globule reserve in larvae as they approached the time of first feeding.     

禁食状态下凡纳滨对虾游离氨基酸的降解代谢

在禁食胁迫下,对在盐度为0(S0)和30(S30)水体中的凡纳滨对虾肌肉游离氨基酸(FAA)的浓度变化进行测定.结果表明,禁食15d后,两种盐度中的凡纳滨对虾肌肉游离氨基酸总量均有所升高,但其中游离的牛磺酸(Tau)、苏氨酸(Thr)、脯氨酸(Pro)、丙氨酸(Ala)、半胱氨酸(Cys)、缬氨酸(Val)、蛋氨酸(Met)、异亮氨酸(Ile)、亮氨酸(Leu)、苯丙氨酸(Phe)、赖氨酸(Lys)、组氨酸(His)的浓度却有不同程度的降低,脯氨酸(Pro)在禁食15d后的浓度降为0,牛磺酸(Tau)、苏氨酸(Thr)、丙氨酸(Ala)、半胱氨酸(Cys)、苯丙氨酸(Phe)、赖氨酸(Lys)的降幅也比较显著(P<0.05);但甘氨酸(Gly)、天门冬氨酸(Asp)、酪氨酸(Tyr)、精氨酸(Arg)等主要游离氨基酸的浓度却显著升高,从而使游离氨基酸总浓度升高.实验表明,凡纳滨对虾肌肉里游离氨基酸浓度在禁食胁迫下降解代谢强度不一,饲料中添加脯氨酸(Pro)、精氨酸(Arg)和赖氨酸(Lys)等游离氨基酸后,可能会对凡纳滨对虾的生长起到促进作用.     

Appetite,metabolism and growth regulation in Atlantic salmon (Salmo salar L.) exposed to hypoxia at elevated seawater temperature

High temperature combined with low dissolved oxygen (DO) is one of the most challenging environmental conditions farmed fish experience; thus, understanding their impact on growth regulation is of relevance to cultured and wild populations. This study examines appetite‐ and growth‐regulating mechanisms in Atlantic salmon postsmolt exposed to either high (HO) or low oxygen (LO) at a suboptimally high temperature (17°C). Additionally, the effects of high (HE) and low (LE) dietary energy (DE) were examined. After a month of treatment, analyses of hormones, regulating appetite (ghrelin) and growth (growth hormone receptor ghr1 and insulin‐like growth factor IGF‐1), and free amino acids (FAA) were measured pre‐ and postprandially at ?4, ?2, 0, 2, 4 and 6 h. No preprandial ghrelin peaks were detected despite a significant reduction in feed intake and growth under hypoxia compared to normoxia. LO treatment also had an overall negative effect on survival compared to HO, while nutrient retention efficiency, FCR and plasma FAA concentrations were unaffected (P > 0.05). Feeding HE diet resulted in increased growth (+17%) and improved FCR (?14%) and energy retention efficiency (+26%) independent of DO. Plasma FAA concentrations were unaffected by LO treatment and DE (P > 0.05). Growth regulatory gene expressions possibly reflect an overall lower growth at a high temperature overriding the impacts of DO and DE. This study also indicates that optimal adaptation time to environmental conditions and feeding regime is crucial for establishing a regular hormonal appetite signalling that reflects real feeding anticipation in salmon.     

Seasonal variations of chemical constituents in the muscle and viscera of small abalone fed different diets

SUMMARY: The seasonal changes in levels of chemical constituents in the muscle and viscera of small abalone Haliotis diversicolor fed gracilar and an artificial diet were investigated. Muscle yields were higher in winter and spring. In October specimens, total adenosine 5'-triphosphate (ATP)-related compounds (ARC), total free amino acids (FAA), and glycogen in both muscle and viscera decreased markedly. The artificial diet fed to small abalone had much higher glycogen in the muscle than those fed on gracilar, and showed a great seasonal change. Total amounts of ARC in the muscles were higher through March to July, while those in the viscera were maximal in January. Taurine, arginine, glycine, glutamic acid, and alanine were the major FAA in both tissues, accounting for 81–94% of the total FAA. Total amounts of FAA in the muscles were higher in the samples collected from winter and early spring than in other seasons. Glycine, glutamic acid, and adenosine monophosphate might be the most important taste components related to the palatability of small abalone. Their total amounts in the muscles of the two specimens were considerably high in December to March. This finding suggested that small abalone produced in winter and early spring might be more palatable.     

Changes in free amino acid profile of red snapper <Emphasis Type="Italic">Lutjanus campechanus</Emphasis>, eggs,and developing larvae

The free amino acids (FAA) profile was determined for newly fertilized eggs and resultant larvae from wild-caught red snapper Lutjanus campechanus induced to spawn with hCG. Yolk sac and oil globule volumes of eggs and larvae were monitored over time from digital photographs. FAA profiles of the eggs and larvae were measured in picomoles (pmol) of FAA/mg of eggs by HPLC. Newly fertilized eggs had a mean total FAA content of 21.72 ± 3.55 nmoles/egg (92.81 ± 9.71 nmoles/mg eggs). Leucine, valine, lysine, and isoleucine were the most abundant essential FAA comprising 35.9% of the total FAA. Alanine, serine, asparagine, and glycine were the most abundant non-essential FAA comprising 34.2% of the total FAA. At 24 h post-hatch (hph) the mean total FAA had decreased by 81% since egg fertilization. The bulk of the FAA decrease was between the time of hatch and 12 hph. Only 8.5 ± 1.5% of the initial concentration in fertilized eggs of isoleucine, 9.7 ± 2.5% of arginine, and 9.9 ± 2.0% of threonine remained at 12 hph. Among the non-essential FAA, alanine dropped the most by 12 hph with 4.6% of the concentration found in a recently fertilized egg remaining, while cysteine had increased 254.7 ± 26.2%. The yolk sac volume decreased rapidly in the first 12 hph and was further reduced 77.0 ± 2.5% from 12 to 24 hph. The oil globule depletion rate was a more linear decline from fertilized egg to 36 hph.     

Elution and internal migration of free amino acids in fish meats by soaking in sodium chloride or sorbitol solution

ABSTRACT:   Elution and internal migration of free amino acids (FAA) in fish meats by soaking were investigated when the meat strips were soaked in various concentrations of sodium chloride (NaCl) or sorbitol solution. Rapid decrease of FAA in an earlier phase of soaking was followed by a mild one, irrespective of the kind and the concentration of soaking solution. The loss of FAA by soaking in NaCl solution was slightly larger than that in sorbitol solution. However, regardless of the kinds of soaking solution, the elution of FAA from fish meats by soaking was only dependent on the soaking time, independently of the concentration, namely osmotic pressure of the soaking solution. Conversely, sluggish migration of FAA from the inside to the surface of the meat strips proceeded by soaking. These results suggested that the elution of FAA from fish meats by soaking was driven by a simple diffusion from the surface of the meats to soaking solution, but it was regulated by sluggish migration rate of FAA in fish meats.     

Absorption, assimilation and catabolism of individual free amino acids by larval Atlantic halibut (Hippoglossus hippoglossus)

Following the completion of the lecithotrophic phase, most marine larvae rely on an incompletely developed digestive tract to absorb amino acids (AA) and other nutrients needed for rapid growth. Despite their undeveloped state, larvae must absorb nutrients in sufficient amounts to fuel exceptionally high rates of growth. This study examined the ability of larval Atlantic halibut to absorb, assimilate and catabolise dispensable (alanine, glutamate) and indispensable (arginine, lysine) dietary free amino acids (FAA) using tube-fed AA solutions with ¹⁴C tracers. Absorption of FAA was rapid with an average of 71% absorbed from the gut within 30 min after tube feeding. Evacuation of FAA by larvae was low, averaging only 6% of tube-fed dose. Dispensable amino acids (DAA) were catabolised in greater proportion (17%) than indispensable FAA (54%). Saturation of FAA transporters was not attained under the present conditions (20 mM, 20% midgut filling). Absorption rates did not differ significantly between the four FAA.     

Variability of the total free amino acid (TFAA) pool in Mytilus galloprovincialis cultured on a raft system. Effect of body size

Variability of total free amino acid (TFAA) pool in Mytilus galloprovincialis was analysed following raft culture of growing mussels. With the aim to ensure the actual effect of animal’s size, a mussel population was sampled in laboratory covering the field size (15‐ to 60‐mm shell length). TFAA showed a constant profile regardless size increase of individuals in both field and laboratory experiments. Environmental salinity and temperature varied within a relatively narrow range in the field (34–35 g L^?1 and 14–19 °C, respectively). Despite the narrow variability of TFAA, significant differences were reported for the most representative amino acids. Specifically, taurine content significantly dropped with soft tissues increase in both field and laboratory experiments. Up to 40% of taurine drop in growing individuals was counterbalanced by the increase in alanine as main protein free amino acid (PFAA), whereas glycine showed high variability and inconsistency. PFAA increased linearly with the endogenous condition of individuals and were inversely correlated with protein content. In summary, TFAA pool of M. galloprovincialis remained unchanged with animal’s size, which might ensure optimal protein turnover rates during growth and establish a significant link between energetic status (condition) and PFAA, values that are equilibrated by a significant drop of the most abundant taurine.