Body increases during molt and molting cycle of the oriental brown shrimp Penaeus japonicus

Individuals of the oriental brown shrimp Penaeus japonicus Bate, were raised separately (1 shrimp per rearing cage) with surplus food, in almost dark, non-sediment conditions. Results were obtained regarding growth of each part of the body in conjunction with exuviation and molting cycle. Increases in carapace, body length and body weight conformed to the general pattern discribed by Hiatt (1948), with no difference in growth resulting from sex, or inflexion point in juvenile stage. The molting cycle of shrimp weighing 1.5 to 15 g was 6 to 17 days at a water temperature of 20° to 28°C. The molting cycle was prolonged in proportion to the size of the shrimp; shortened as the water temperature increased.     

Oocyte development in the kuruma prawn Penaeus japonicus

Female kuruma prawns (Penaeus japonicus Bate) with undeveloped, early developing, developing, nearly ripe and ripe ovaries, were collected from Ise Bay, Japan, in 1984. Oocyte development of the kuruma prawn was classified into ten stages according to morphological characters, namely: (1) synapsis stage, (2) chromatin nucleolus stage, (3) early perinucleolus stage, (4) late perinucleolus stage, (5) oil globule Stage I, (6) oil globule Stage II, (7) yolkless stage, (8) yolk granule stage, (9) prematuration stage, and (10) maturation stage. The synapsis stage is a multiplication stage. The chromatin nucleolus stage, early and late perinucleolus stages are previtellogenesis and primary growth stages. Oil globule Stage I is an initial stage of primary vitellogenesis and secondary growth. Follicle cells on the oil globule Stage I oocytes expand rapidly and reach maximum size during oogenesis. Yolk granule stage oocytes are in the initial stages of secondary vitellogenesis. Strongly acidophilic yolk granules accumulate within basophilic vesicles of the cytoplasm. The yolk granules are first concentrated in the inner part of the cytoplasm, then gradually spread to the periphery. Cortical crypts, which are separated from the oocyte cytoplasm by the cytoplasmic membrane, are situated outside of oocyte cytoplasm. Germinal vesicle breakdown (GVBD) is initiated in the late phase of prematuration and continues until the late phase of maturation immediately prior to spawning. At the beginning of the maturation stage, the oocytes are ovulated, after which the nuclei further shrink and migrate out-wards. After ovulation, meiotic division of the ovarian oocyte progressed up to the metaphase of primary maturation division. Finally, the meiotic metaphase is visible just beneath the cytoplasmic membrane in the mature oocyte. Though ovulation is synchronous within the same ovary, GVBD is not completely synchronous. Ovulated mature oocytes have many club-shaped cortical crypts in the peripheral part of the cytoplasm and contain extensive accumulations of yolk granules dispersed throughout the cytoplasm. The apical end of the club-shaped cortical crypts and cytoplasmic membrane are coated by the vitellin envelope in the mature oocyte.     

Osmotic and chloride regulation in the hemolymph of the tiger prawn Penaeus monodon during molting in various salinities

The effect of molting on osmotic and chloride concentrations in the blood of the prawn Penaeus monodon Fabricius (20±3 g) at various salinities was investigated. Prawns were obtained from ponds in Iloilo, Philippines, in 1984. They were stocked in salinities of 8, 20, 32 and 44, and their hemolymph was sampled during molt (Time 0), and then 0.125, 0.25, 0.5, 1, 2, 4, 6, 10 and 14 d after molting. Prawns during and immediately after molt tended to conform to the environmental osmolality. Subsequent postmolt (0.5 d) stages displayed more divergence from external salinity. The isosmotic point was higher (940±30 mOsm kg^-1) during molt than during intermolt (663±8 mOsm/kg^-1), suggesting different osmotic requirements in early molt. Hyperregulation of hemolymph chloride below 20 S, as well as isoionic point (301±6 mM), were independent of molting stage. At 20 S and above, newly molted (0 to 0.25 d post-molt) individuals tended to conform to the external chloride concentration while intermolt (0.5 d) post-molt individuals did not. Contribution of hemolymph chloride to hemolymph osmolality was greater during intermolt than during ecdysis, suggesting an important role for other negatively charged ions during molt. When molt occurred in 20 S (the test salinity most similar to the isoionic salinity), there was little or no change in hemolymph osmolality or chloride concentration from 0 to 14 d postmolt. At 8, 32 and 44 S, the change from molt to intermolt values in hemolymph osmotic and chloride concentrations was hyperbolic. Non-linear least-squares regression showed that prawns generally achieved intermolt values within 1 d after molting. Prawns at intermolt regulated hemolymph osmolality (620 to 820 mOsm kg^-1) and chloride concentration (300 to 450 mM) at a much narrower range than during molt (520 to 1 170 mOsm kg^-1 and 250 to 520 mM, respectively). Hemolymph osmolality was a more sensitive indicator of physiological response than hemolymph chloride concentration. Distribution and culture of P. monodon might be limited in low salinities by its ability to maintain a hemolymph osmolality 500 mOsm kg^-1 during molt and 600 mOsm kg^-1 in intermolt, and in high salinities by its capacity to reduce the hemolymph osmolality from values at molt to those in intermolt. Osmotic and chloride concentrations in the blood of P. monodon clearly varied with both molt stage and salinity of the medium. Dependence on external factors, however, gradually declined in older molt stages, suggesting a reduction in integument permeability and greater development of ion absorption/secretion mechanisms as the exoskeleton hardened.SEAFDEC Contribution No. 197     

Effect of salinity on hemolymph calcium concentration during the molt cycle of the prawn Penaeus monodon

Prawns (Penaeus monodon) were obtained from ponds in Iloilo, Philippines, in 1984 and 1985 and maintained in salinities from 8 to 44. Total hemolymph calcium was largely affected by molt stage and less so by salinity. A sharp, transient increase in hemolymph calcium occurred 3 to 6 h postmolt, followed by an equally rapid decrease from 6 h postmolt to intermolt. This biphasis response was limited to prawns in 8, 20 and 32S; in 44S, hemolymph calcium remained the same throughout the sampling period. Peak concentrations of total calcium were greater in low (8 and 20S) than in high salinities. Salinity had no effect on the duration of molt cycle nor on time of occurrence of molt. Almost half of molting incidents occurred between 18.01 and 0.00 hrs, and one-third between 0.01 and 06.00 hrs.     

Route of egg yolk protein uptake in the oocytes of kuruma prawn,Penaeus japonicus

The route of egg yolk protein uptake into the oocytes of kuruma prawn, Penaeus japonicus, was studied using immunohistochemical and electron microscopical methods. Although a significant immunofluorescence with anti-vitellin-immunoglobulin was observed in the enlarged follicle cells surrounding oil globule stage oocytes of the early vitellogenic ovary, no fluorescence was detected in shrunken follicle cells surrounding oocytes in the yolk granule stage. Electron microscopically, yolk granule stage oocytes have an irregular surface with numerous well-developed microvilli. In contrast, the surface of follicle cells is relatively smooth. The irregular surface of yolk granule stage oocytes was covered with a layer of electron dense material. Similar dense material was found in the spaces between the neighboring follicle cells on the yolk granule stage oocytes. The outer surface of the follicle cells on yolk granule stage oocytes was covered by dense materials which were similar to those found on the irregular surface of oocytes. Micropinocytotic vesicles containing dense material were found in the ooplasm near the irregular surface with numerous well-developed microvilli. Dense material was concentrated in the peripheral part of the small forming yolk bodies of yolk granule stage oocytes. This suggests that the electron dense material, probably egg yolk protein, transferred to the surface of yolk granule stage oocytes from the spaces between the neighboring follicle cells may be incorporated into the ooplasm by pinocytosis through the microvilli and subsequently aggregate to form yolk bodies.     

Carotenoids in the tiger prawn Penaeus esculentus during ovarian maturation

Female Penaeus esculentus Haswell were collected by 15 to 20 min duration trawls during 1990. Carotenoids were analysed in the digestive gland, abdominal muscle, the remainder of the body (hereafter called integument) and ovary of prawns in Stage 2 through Stage 4 (fully mature) of maturation. The only oxycarotenoids (xanthophylls) identified were astaxanthins or astaxanthin esters; occasionally low levels of -carotene were detected in the digestive gland. The concentrations of astaxanthin monoesters (AM) and diesters (AD) were highest, with only minor amounts of free astaxanthins (Ast), except in the maturing ovaries, where free astaxanthins predominated (up to 80% of the total carotenoid). Of the total carotenoid, 82 to 94% was in the integument, but at maturity the digestive gland contained 10.7±3.4% and the ovary 5.6±0.9% of the total carotenoid. Only the ovary increased in mass during maturation, reaching up to 5.2% of total prawn mass. During this period, digestive gland concentrations of AM, AD and Ast all increased (tota 20 to 120 g g^-1); levels in the muscle and integument varied little throughout maturation (total 0.4 and 100 g g^-1, respectively); ovary AM levels remained low throughout (1.5 to 1.2 g g^-1), AD increased from only 2 to 5 g g^-1, but Ast increased from 2 to 34 g g^-1. Apart from the ovary, AM concentrations were the most variable. In common with other decapod Crustacea, the maturing ovary of P. esculentus contained high levels of carotenoids, indicating that these may have an important role in early development. The natural diet of P. esculentus includes a variety of carotenoids, but except for a little -carotene, the digestive gland, where absorption occurs, contained astaxanthins, with only an occasional trace of -carotene. This suggests that the conversion of dietary carotenoids to astaxanthin occurs soon after ingestion.     

Rearing of prawn larvae,Penaeus japonicus,fed soy-cake particles and diatoms

Soy cake^* was homogenized and filtered through an 80 mesh net to produce small, detritus-like particles. The effect of soy-cake particles, an artificial detritus, on the survival and growth of Penaeus japonicus Bate zoea was then tested. The soy cake was considered to be effective for survival and growth of the zoea. The best survival rate, 85.9%, was obtained in a tank receiving soy cake in quantities of 0.16 mg/zoea/day. An experiment was also performed to compare three kinds of food: particles of soy cake alone, diatoms (Chaetoceros rigidus) alone, and a half and half mixture of the two. The best growth, 2.49 mm, and the highest survival rate, 79.1%, were found in larvae fed the mixture of soy-cake particles and diatoms. The results thus seem to demonstrate that particles of soy cake could be usefully applied to the mass-culture of the penaeid prawn.     

Fatty acid composition of organs and tissues of the tiger prawn Penaeus esculentus during the moulting cycle and during starvation

The fatty acids (FA) in neutral lipid (NL) and polar lipid (PL) of digestive gland, muscle and integument of Penaeus esculentus Haswell were analysed and compared during the moulting cycle and during starvation. The prawns were collected from Moreton Bay, Queensland, Australia, by trawling during 1985–1987, and were fed with a standard semi-purified diet. Compared with a natural diet, the artificial diet had much higher levels of 18:1n-9 and 18:2n-6, but only trace amounts of 20:4n-6, but there was no evidence of dietary imbalance. The fatty acid composition (percentage of total lipid) of the digestive gland changed markedly during the moulting cycle and during starvation, but the small changes observed in both muscle and integument suggested that these tissues maintained their composition under both conditions. When the fatty acids were calculated as absolute amounts, muscle composition, as well as that of the digestive gland, changed significantly. In the digestive gland, saturated FA (SFA), monounsaturated FA (MUFA), diunsaturated FA (DUFA) and polyunsaturated FA (PUFA) all increased up to the middle of the moulting cycle and then declined; with starvation all groups decreased. In muscle, SFA, MUFA and DUFA all increased during the moulting cycle; starvation caused SFA, MUFA and PUFA to decrease, whereas DUFA did not vary. Starvation caused both 18:2n-6 (linoleic) and 18:3n-3 (linolenic) in the digestive gland to reach or almost reach zero. The other essential PUFA, 20:4n-6 (arachidonic), 20:5n-3 (eicosapentaenoic) and 22:6n-3 (docosahexaenoic), decreased during the moulting cycle, but during starvation 20:4n-6 did not decrease as much. In muscle, the levels of 18:2n-6 and 18:3n-3 increased, while 20:4n-6, 20:5n-3 and 22:6n-3 remained approximately constant during the moulting cycle. Starvation reduced 20:5n-3 and 22:6n-3 to about 60%. The data suggest that levels of 18:3n-3, 20:4n-6, 20:5n-3 and 22:6n-3 are regulated, and that 20:4n-6 can be synthesised from 18:2n-6. There is no clear evidence that 20:5n-3 and 22:6n-3 are essential in P. esculentus, but tissue catabolism of cell membranes during starvation may have provided sufficient amounts for maintenance.     

Statolith implantation in the banana prawn Penaeus merguiensis

Specimens of Penaeus merguiensis de Man were captured between February and May 1981 from intertidal creeks and beaches of Cleveland Bay, Townsville, Australia, using a 15 m seine net. The statocyst of P. merguiensis resembles that of other macrurans in that it is a dorsal invagination of the basal antennular segment lined with groups of sensory hairs. The statolith is composed of sand grains implanted by the prawn from the substratum which must be done after every moult. Implantation begins within 90 min of ecdysis and has 3 phases: sifting; digging and finally eye withdrawal which pushes the sand grains into the statocyst chamber.     

Changes in protein-bound and free amino acids in the muscle of the tiger prawn Penaeus esculentus during starvation

Using the starvation technique, changes in protein and free amino acids were examined in Penaeus esculentus Haswell collected from Moreton Bay, Australia, by trawling in 1985. Prawns of 17.7±0.26 g wet weight were held at 25°C until 2 d after moulting. Groups of seven or eight were then starved fro 5, 10, or 15 d, with appropriate control groups. At the end of each period, ecreted amino acids were collected for 24 h and whole-muscle amino acids and free amino acids (FAA) g^-1 in each prawn were analysed. Concentrations of whole-muscle amino acids showed only minor changes with starvation, but concentrations of many of the FAA changed significantly. Total FAA averaged 1 182±45 mol g^-1 dry weight. Individual FAA, in order of abundance, were glycine, arginine, proline, taurine, threonine, hydroxyproline, alanine, glutamic acid, valine, aspartic acid and lysine; the remaining FAA each contributed <0.2% of the total. Only taurine and alanine did not show significant changes with starvation. Concentrations of glycine, arginine, hydroxyproline, glutamic and aspartic acid increased, while those of proline, threonine, valine and lysine decreased with starvation, that of proline approaching zero after 15 d starvation. Excreted amino acid-nitrogen represented <2% of excreted ammonianitrogen ornithine being the most abundant (35%), followed by leucine (22%) and lysine (17%). The relative abundance of excreted amino acids did not correspond with those of the FAA. It is suggested that, as starvation progresses, the muscle protein is progressively hydrolysed, but with the remaining muscle maintaining its amino acid composition. The liberated amino acids enter the FAA pool and become available for energy production. Proline may have an important role as an energy source, but the ability to synthesise proline may be limited, and thus the artificial food of penaeid prawns may be improved by its addition.     

Chitobiase activity in the epidermis and hepatopancreas of the fiddler crab Uca pugilator during the molting cycle

The activity of chitobiase, also known as N-acetyl-β-glucosaminidase, in the epidermis and hepatopancreas of the fiddler crab Uca pugilator (Bosc, 1802), during the molting cycle, was investigated. A pH optimum of 5 to 6 was found for the enzymatic activity in both the epidermis and hepatopancreas. The temperature optimum for epidermal and hepatopancreatic chitobiase activities was 50 to 60 °C. The K _m values for epidermal and hepatopancreatic chitobiase activities at 19 °C were 0.190 ± 0.027 and 0.203 ± 0.016 mM 4-methylumbelliferyl-N-acetyl-β-glucosaminide, respectively. Hepatopancreatic chitobiase activity was significantly higher than epidermal enzymatic activity in all the molt cycle stages tested except Postmolt Stage A-B. Chitobiase activity varied significantly during the molting cycle, with the epidermal enzymatic activity in Premolt Stage D_3–4 significantly higher than in Stage C (intermolt) and Premolt Stage D₀, whereas hepatopancreatic chitobiase activity in Premolt Stage D_3–4 was significantly higher than in all other molt stages tested. The patterns of chitobiase activity in the epidermis and hepatopancreas correlate well with the hemolymph titer of ecdysteroids in U. pugilator during the molting cycle; this suggests that chitobiase activity in both tissues is regulated at least in part by the steroid molting hormones. Received: 6 May 1998 / Accepted: 12 September 1998     

中华绒螯蟹幼蟹蜕壳期间池塘水环境的变化特征

为探究中华绒螯蟹幼蟹蜕壳期间池塘水环境的变化特征,于2018年5月7日至10月13日,对上海松江泖港地区幼蟹生态养殖池塘和水源进行水质监测.结果表明,大眼幼体经160 d养殖,蜕壳11次成长为幼蟹,T均值为27.0±2.9℃,总有效积温为3085.3℃·d;随蜕壳次数增加,有效积温增长趋势贴近指数函数y=42.166e~(0.2644)~x,R~2=0.9629;累计有效积温增长趋势贴近二次函数y=33.059x~2-98.244x+160.05,R~2=0.9992.幼蟹池溶解氧(DO)在养殖前期优于水源,NH~+_4-N、NO~-_2-N、NO~-_3-N总体优于水源,PO_4~(3-)-P在高温季节优于水源,COD_(Mn)在整个养殖阶段均较水源差.除TN、TP、COD_(Mn)有不同程度超标外,幼蟹池和水源其它水质因子基本符合渔业水质标准和地表水环境质量标准的Ⅲ级标准.     

Setal development,moult-staging and ecdysis in the banana prawn Penaeus merguiensis

Specimens of juvenile Penaeus merguiensis de Man (1888) were captured by seine netting from the shores of Cleveland Bay, Townsville, Queensland Australia between February 1980 and November 1981. Accurate determination of moult cycle stage can be achieved rapidly by microsopical examination of setal development in an excised whole pleopod. Four major stages and 5 substages within premoult were clearly defined. The rate of setogenesis varies along the length of a pleopod, precluding the examination of only one specific location on the pleopod for accurate moult cycle staging. The process of ecdysis lasts for no more than 40 s.     

Structure and function of the chelate pereiopods of the banana prawn Penaeus merguiensis

Penaeus merguiensis de Man systematically searches the substratum and removes small particles of food from it using the small chelae of the first three pairs of pereiopods. One or more chelae are used to transfer food particles to the mouth. The propus and dactylus of these limbs bear numerous setae arranged in discrete groups along the length of the segments. The tip of each seta is elaborately sculptured and has a large sub-terminal pore. It is probable that these are chemosensory organs responsible for discriminating edible from non-edible material. Proximal to almost every setal group is a much-branched seta (rarely two) which probably measures the depth to which the chela has been inserted into the substratum. At the articulation of the propus and carpus of the first pereiopod are three groups of differently sculptured setae, whose function is to clean the other chelate pereiopods. An elaborate system of pegs and a ridge on the apposable fringes of the chelae might be a mechano-receptive device with a particle size discriminating function. The ridges merge into opposable terminal denticulate pads whose function is to grasp food and other particles, which may be quite small (10 to 20 m upwards).     

Structure and function of the third maxillipeds of the banana prawn Penaeus merguiensis

The functions of the third maxilliped of Penaeus merguiensis de Man are described. It has a 6-segmented endopodite which is used in feeding, grooming and possible pheromone reception. In feeding, large pieces of food are gripped by the stout spines on inner borders of the ischia which hold them to the mouth so that particles can be torn off and ingested. All the distal segments have long setae used in grooming chelate pereiopods and the antennules. In mature males there is a tuft of about 300 slender setae at the end of the propus, but its function remains obscure.     

Population genetic structure of the brown tiger prawn, Penaeus esculentus, in tropical northern Australia

Eight polymorphic microsatellite loci were analysed in six population samples from four locations of the Australian endemic brown tiger prawn, Penaeus esculentus. Tests of Hardy–Weinberg equilibrium were generally in accord with expectations, with only one locus, in two samples, showing significant deviations. Three samples were taken in different years from the Exmouth Gulf. These showed no significant heterogeneity, and it was concluded that they were from a single panmictic population. A sample from Shark Bay, also on the west coast of Australia, showed barely detectable differentiation from Exmouth Gulf (F _ST = 0 to 0.0014). A northeast sample from the Gulf of Carpentaria showed low (F _ST = 0.008) but significant differentiation from Moreton Bay, on the east coast. However, Exmouth Gulf/Shark Bay samples were well differentiated from the Gulf of Carpentaria/Moreton Bay (F _ST = 0.047–0.063). The data do not fit a simple isolation by distance model. It is postulated that the east–west differentiation largely reflects the isolation of east and west coast populations that occurred at the last glacial maximum when there was a land bridge between north-eastern Australia and New Guinea.     

Functional cytology of the hepatopancreas of Penaeus semisulcatus (Crustacea: Decapoda) during the moult cycle

In the shrimp Penaeus semisulcatus, the digestive gland functions as the main site for the digestion, absorption and storage of nutrients and metals during the feeding stages of intermoult and for the mobilization of reserves during the non-feeding stages of pre-and post-moult. These different activities are reflected directly in the cytology of the gland. All the epithelial cells show marked fluctuations in frequency and changes in structure, form and function which occur in phase with the moult cycle. The shrimp were collected offshore from Kuwait in 1980.     

Influence of salinity and temperature on the oxygen consumption in young juveniles of the Indian prawn Penaeus indicus

Routine oxygen consumption of very young juveniles (0.1 g) of Penaeus indicus H. Milne Edwards was significantly influenced by ambient temperature and weight of the animal, but not by ambient salinity, when tested at salinities (7, 21, and 35) to which they had been long-term (over 10 days) acclimated. Standard oxygen consumption of young juvenile prawns (1 to 3 g), subjected to step-wise changes in ambient salinity, from sea water to low salinity waters (2 to 6), and measured after short-term (24 h) salinity acclimation at each step, was lowest at salinities where prawns such as those tested occur naturally (10 to 15). The metabolic rates do not appear to have a direct relation to the osmotic gradient, even when the influence of interfering activity is eliminated. It appears that factors other than osmotic gradient will have to be sought in order to explain the metabolic patterns of P. indicus in relation to salinity.     

Population structure of the giant tiger prawn Penaeus monodon in Australian waters, determined using microsatellite markers

 We describe three highly polymorphic microsatellite loci which have been isolated from the giant tiger prawn Penaeus monodon. The number of alleles present among 312 samples at the loci Pmo9, Pmo25 and Pmo27 were 84, 34 and 35, respectively, with heterozygosities all >90%. Analyses of the distribution of length variation at three microsatellite loci among five Australian P. monodon populations revealed strong differentiation between populations from the west and those from the northern and eastern coasts. Tests for population differentiation (F st) values and an analogous measure for microsatellite loci (R st) all demonstrated that Western Australian P. monodon are a separate genetic stock which exhibits reduced genetic variation relative to the other populations. Reduced variability is consistent with a recent population bottleneck or colonization by a small founding population from the east when sea links between Indonesia, New Guinea and Australia were re-established following the last ice age. The results of this study are in agreement with previous surveys of P. monodon conducted with allozymes and mtDNA. Received: 18 December 1998 / Accepted: 27 August 1999     

Studies on the nutritional requirements of the larval stages of Penaeus japonicus using microencapsulated diets

Fatty acid biosynthesis in the larval stages of Penaeus japonicus Bate was examined by feeding microencapsulated diets containing (1-¹⁴C) palmitic acid, and fat-free diets supplemented with defined fatty acids. Highest larval growth rates were achieved on diets containing Tapes philippinarum lipid and, when defined fatty acids were substituted, on diets containing 20:63 fatty acid. The radioactive tracer experiments indicate that 16:17, 18:0 and 18:19 fatty acids may be synthesised from palmitic acid and that P. japonicus larvae may possess the ability to elongate 18:33 to 20:53 and 22:63, and 18:26 to 20:46. However, the rates of these reactions appear to be too slow to meet the larval requirements for essential fatty acids and the 3 series of polyunsaturated fatty acids must be provided in the diet.