Preliminary investigations on the utilization of tubificid worms by postlarvae of Macrobrachium lanchesteri (de Man)

Postlarvae of Macrobrachium lanchesteri were stocked in confined waters. The larvae were fed on an ad libitum food of Tubifex tubifex worms for 30 days and their rearing has been established. 1 Kg of initially stocked postlarvae need 4.5 Kg of live T. tubifex to produce 0.537 Kg of new flesh. The worms were found to increase the crude protein content of larval flesh by 17% of the dry matter.     

Effects of eyestalk ablation on moulting and growth of penaeid prawn Metapenaeus dobsoni (de Man)

Penaeid prawns M. dobsoni of two different size ranges were ablated both unilaterally (UEA) and bilaterally (BEA) and subjected to individual study. The UEA prawns consumed almost the same amount of food as the control prawns in the size group, 35-40mm, but consumed about 57.8% more food than the control prawns in the larger size group, 48-53mm. Growth was estimated as length and weight changes and significant variation was observed. The moult rate and dry moult weight showed marked differences. Average intermoult period increases with second ablation. Dry weight of moult in every succeeding moult was found to decrease irrespective of the level of ablation. Unilateral eyestalk ablation resulted in increase in dry weight whereas bilateral eyestalk ablation reduced the dry weight of moult and this decrease in the rate increased after each subsequent moult. In the larger size group, values of protein efficiency ratio (PER) were almost same as that of the lower size group. The UEA prawns exhibited highest conversion efficiency. The production rate of UEA prawns was 84% more than that of the control whereas BEA prawns indicated negative production. The same trend followed for net growth efficiency also. The results suggest that unilateral eyestalk ablation can be resorted to accelerate growth and conversion efficiency. Eyestalk ablation has been frequently resorted in matured forms for inducing maturation of gonads. For the first time attempts have been made to compare between the effects of removing one eyestalk versus two and changes taking place in juvenile forms especially in their physiology related to growth.     

Immunomodulatory effect of Withania somnifera supplementation diet in the giant freshwater prawn Macrobrachium rosenbergii (de Man) against Aeromonas hydrophila

The effect of Withania somnifera extract supplementation diets on innate immune response in giant freshwater prawn Macrobrachium rosenbergii (de Man) against Aeromonas hydrophila was investigated. The bacterial clearance efficiency significantly increased in prawn fed with 0.1% and 1.0% doses of W. somnifera supplementation diet against pathogen from weeks 1-4 as compared to the control. The innate immune parameters such as, phenoloxidase activity, superoxide anion level, superoxide dismutase activity, nitrate, and nitrite concentrations were significantly enhanced in prawn fed with 0.1% and 1.0% doses of W. somnifera supplementation diet from weeks 1-4 against pathogen. The total hemocyte counts (THC) significantly increased in prawn fed with 0.1% and 1.0% doses diet from weeks 1-4 against pathogen as compared to the control. These results strongly suggested that administration of W. somnifera through supplementation diet positively enhances the innate immune system and enhanced survival rate in M. rosenbergii against A. hydrophila infection.     

Neurosecretory cell types in the eyestalk of the freshwater prawn Palaemon paucidens

Summary In the medulla terminalis ganglionic X-organ (MTGX) of the eyestalk of the freshwater prawn, Palaemon paucidens, six peptidergic neuro-secretory cell types (A-, B-, C-, D-, E-, and F-cells) are distinguishable on the basis of the different morphology of their elementary granules and rough endoplasmic reticulum (rER). All of these cell types seem to correspond to Type-IIIa cells or dispersing Type-IV cells, that have previously been differentiated at the light microscopic level (Hisano, 1974), as judged from the dimensions of their cell bodies and nuclei. Two other peptidergic neurosecretory cell types that are apparently comparable to the Type-II and Type-IIIb cells (Hisano, 1974), respectively, are recognized in parts of the optic ganglia other than MTGX, and these are now designated as Gand H-cells, respectively. All the remaining cell types, designated as Type-I, cluster-forming Type-IV, Type-V and Type-VI cells in our previous light microscopic study, have small cored-vesicles in their cytoplasm. It remains undecided whether these, possibly aminergic, neurons are neurosecretory or not.The author wishes to express his sincere appreciation to Prof. T. Aoto for his invaluable advice during the course of this study.     

Effects of eyestalk ablation and limb amputation on the moult cycle of the shrimp Penaeus chinensis

The shrimp Penaeus chinensis at moult stage D_o were subjected to one of the three following treatments: bilateral eyestalk ablation, amputation of the fifth pair of pereiopods, and both of the above treatments. Two consecutive ecdyses after treatments were followed. Intact animals served as control. Precocious moulting was exhibited in all treated groups. Eyestalk ablation shortened the time to the first ecdysis more than does limb amputation. Additive effect was found in shrimps receiving both treatments. The duration between the first and second ecdyses in treated shrimps was shorter than that of intact animals, but the durations in the three treated groups were not significantly different from one another. Regenerates of limbs appeared after the second ecdysis following limb amputation. Further, change of body colour from black and green to red and white was observed in shrimps with eyestalk ablation.     

Effect of bilateral eyestalk ablation on ovarian development and moulting in early and late intermoult stages of female spiny lobster Panulirus homarus (Linnaeus, 1758)

Abstract

The present study describes the effect of bilateral eyestalk ablation (BESA) on reproduction and moulting of spiny lobster Panulirus homarus females in their early and late intermoult stages. The lobsters obtained from the wild were conditioned for the experiment. The experiments were conducted at the Calicut research centre of Central Marine Fisheries Research Institute, India. Eyestalk ablation of females was done by ligation. The responses of the bilaterally eyestalk-ablated lobsters were statistically analysed. BESA conducted on the early and late intermoult stages resulted in the simultaneous acceleration of the somatic growth and reproductive processes with higher emphasis for oogenesis in lobsters ablated in the early intermoult phase and comparatively lower activity in those ablated in the late intermoult phase. Ablation in late intermoult phase resulted in faster entry into the premoult stage compared to the control.     

罗氏沼虾(Macrobrachium rosenbergii)养殖池塘沉积物中细菌、硫酸盐还原菌和硫氧化菌的垂直分布特征

沉积物中微生物介导的硫循环在有机物分解和养分循环中发挥重要作用,但目前我们对水产养殖生态系统中的参与硫酸盐还原和硫氧化过程的微生物多样性及其调控机制仍知之甚少。【目的】探究硫酸盐还原菌(sulfate-reducing bacteria,SRB)和硫氧化菌(sulfur-oxidizing bacteria,SOB)的垂直分布特征及其主要的环境驱动因素。【方法】本研究利用高通量测序和荧光定量PCR (qPCR)分析了罗氏沼虾(Macrobrachium rosenbergii)养殖池塘沉积物表层(0–1 cm)、中层(10–11 cm)和底层(20–21 cm)中的细菌、SRB和SOB的丰度、多样性和群落组成。【结果】细菌(16S rRNA)、硫酸盐还原菌(dsrB)和硫氧化菌(soxB)的基因拷贝数呈现着从表层到中层急剧骤降的趋势(ANOVA,P<0.05),但中层和底层样品之间的差异却并不显著(P>0.05),以及α多样性分析显示3个群体的物种丰富度和均匀度都随深度而逐步降低,这都说明硫循环过程主要发生于沉积物的表层。γ-、δ-和β-变形菌分别是细菌、SRB和SOB的优势类群;其中SRB以Desulfobacca属和脱硫八叠球菌属(Desulfosarcina)为主,前者在表层有着最低的比重,而后者却与之相反;硫杆菌(Thiobacillus)作为细菌和SOB的优势属,更广泛地分布于中层沉积物中。RDA分析和Mantel检验揭示了影响细菌群落的主要环境因子是NO₃^–、SO₄^2–、TOC和TON,而SRB的群落变异主要是由As、TON、NO₃^–和Pb所驱动,以及SOB的群落变化则主要响应了TC、NO₂^–、NH₄⁺和TON浓度。【结论】养殖池塘底栖的细菌、SRB和SOB的丰度、多样性和群落结构的垂直分布特征可能受到多种环境因素共同的影响。     

Cells producing insulin-like androgenic gland hormone of the giant freshwater prawn, Macrobrachium rosenbergii, proliferate following bilateral eyestalk-ablation

We found that the androgenic gland (AG) of Macrobrachium rosenbergii possesses three cell types. Type I cells are small polygonal shaped-cells (13.4 μm in diameter), stain strongly with hematoxylin-eosin (H&;E), have abundant multilayered rough endoplasmic reticulum (rER), and nuclei containing mostly heterochromatin. Type II cells are slightly larger (18.6 μm in diameter), stain lightly with H&;E, have rER with dilated cisternae, and nuclei containing mostly euchromatin. Type III cells (previously undescribed) are similar in size and shape to type I cells, but the cytoplasm is unstained and they have a high amount of smooth endoplasmic reticulum (sER) and mitochondria with tubular cristae. Bilateral eyestalk-ablation resulted in AG hypertrophy with a proliferation and predominance of type I cells as determined by bromodeoxyuridine (BrdU) assays. Expression of insulin-like androgenic gland hormone (Mr-IAG), determined by immunohistochemistry, was weak in type I cells, strong in type II cells of both the intact and eyestalk-ablated, and negative in type III cells. It was also detected in spermatogonia, nurse cells, and epithelium lining of the spermatic duct. The function of Mr-IAG in these tissues is yet to be elucidated but the distribution implies a strong role in male reproduction.     

Effects of All-trans retinoic acid on germ cell development of embryos and larvae of the giant freshwater prawn, Macrobrachium rosenbergii

Embryos of the giant freshwater prawn, Macrobrachium rosenbergii, were treated with 1, 10 or 50 μg ml⁻¹ all-trans retinoic acid (AtRA) for 2 days. Survival and hatching rates were not affected. However, an increase in the number of primordial germ cells (PGCs), progenitors of gametes, and a slightly more advanced stage of the gonads were found in those treated with 10 or 50 μg ml⁻¹ AtRA. Newly hatched larvae were treated with 0.1, 0.5 or 1 μg ml⁻¹ AtRA for 2 days. Survival rates were lower in those treated with 0.5 or 1 μg ml⁻¹ AtRA; nevertheless, the gonads were slightly more developed. The results indicated that AtRA, an active metabolite of vitamin A, affected germ cell and gonad development of embryos and the larvae of giant freshwater prawn.     

Effects of feeding level and body size on food utilization of the freshwater snail Pila globosa

Food supply caused an increase in the overall energy budget of all size groups of Pila globosa. Feeding rate increased from 3.4 to 28.7, 2.0 to 19.1 and 0.2 to 7.2 mg/g/day in young, intermediate and old snails respectively. The corresponding increase in body weight (growth rate) ranged from 1.3 to 2.7, 0.5 to 1.5 and 0.4 to 0.5 mg/g/day. When compared with the other two groups, maximum values were recorded for young P. globosa, i.e. an increase in size (ageing) caused a decrease in the energy budget. Data obtained for the maintenance, optimum and maximum feeding rates for the young P. globosa were 12.0, 22.0 and 28.8 mg/g/day. The corresponding values for the intermediate and old snails were 7.4, 14.0 and 19.0 mg/g/day and 4.1, 5.6 and 7.2 mg/g/day. With the increase in body weight, a progressive reduction in the slope of the regression lines was noticed in the body weight-conversion rate relationship.Paper presented in the first Indian Conference on Ecology and Environmental Sciences, University of Rajasthan, Jaipur (1980).     

Effect of hypoxia on the immune response of giant freshwater prawn Macrobrachium rosenbergii and its susceptibility to pathogen Enterococcus

Giant freshwater prawns Macrobrachium rosenbergii (14-19 g) were challenged with Enterococcus (3 x 10(5) cfu prawn(-1)) previously incubated in TSB medium for 24 h, then placed in water having concentrations of dissolved oxygen (DO) at 7.75, 4.75, 2.75 and 1.75 mg l(-1). Onset of mortality occurred after 6 h exposure to 1.75 mg l(-1) DO, and after 12 h exposure to 2.75 mg 1(-1) DO. Cumulative mortality of prawns at 1.75 mg l(-1) DO was significantly higher than that at 4.75 and 2.75 mg l(-1) DO, and cumulative mortality of prawns at 4.75 and 2.75 mg l(-1) DO was significantly higher than that at 7.75 mg l(-1) DO after 96 h. The prawns (20-30 g) which had been placed in water for 0 to 120 h at 7.75, 4.75, 2.75 and 1.75 mg l(-1) DO were examined for the THC (total haemocyte counts), DHC (differential haemocyte counts), phenoloxidase activity, respiratory burst, percentage phagocytosis and clearance efficiency. No significant difference in semi-granular cells and granular cells of prawns was observed among four treatments. The prawns following 120 h exposure to 2.75 mg l(-1) DO decreased significantly the hyaline cells and THC by 39% and 36%, respectively. Phenoloxidase activity and respiratory burst decreased significantly by 33% and 11% when the prawns were exposed to 2.75 mg l(-1) DO after 24 h, respectively. Percentage phagocytosis and clearance efficiency to Enterococcus decreased significantly by 44% and 54% for the prawns following 12 h exposure to 2.75 mg l(-1) DO, respectively. It is concluded that DO as low as 2.75 mg l(-1) and 4.75 mg l(-1) causes depression in immune system of M. rosenbergii, and increases its susceptibility to Enterococcus infection.     

Countergradient variation in growth and food conversion efficiency of juvenile turbot

Growth performance of a high latitude (Norway) population of juvenile turbot Scophthalmus maximus , was superior to that of two other lower latitude populations (Scotland, France) especially at 18° and 22° C. Overall these results lend some support to the hypothesis of countergradient variation in growth. The Norwegian population had the highest estimated temperature optimum for growth ( T _opt.G, ±S.E.) (23·0±0·9°C) and food conversion efficiency ( T _opt.Ec) (17·5±0·3), followed by the French ( T _opt.G 21·1±1·0; T _opt.Ec, 16·7±0·1) population, whereas the Scottish population had the lowest optimum ( T _opt.G, 19·6±0·6; T _{opt Ec}, 16·5±0·1°C). These results have two major implications: firstly, for turbot culture, particularly in selection work focusing on growth performance; secondly, if countergradient variation in growth performance takes place within a species one cannot assume automatically that one set of physiological parameters, in this case growth-related parameters, is satisfactory to predict growth for a species throughout its range as different populations might show a difference in response towards different physiological parameters.     

Variation in food intake, food conversion efficiency and growth of juvenile turbot from different geographic strains

Food conversion efficiency and growth of juvenile turbot Scophthalmus maximus , reared under temperatures of 14, 18 and 22° C, were found to be higher in one experiment (7–70 g fish) in a higher latitude (Norway) strain than lower latitude (France and Scotland) strains. In a second study (20–150 g fish), food intake, food conversion efficiency and growth were higher in higher latitude (Iceland and Norway) compared with a lower latitude (France) strain.     

Characteristics of NADH-dependent lipid peroxidation in sarcoplasmic reticulum of white shrimp,Litopenaeus vannamei,and freshwater prawn,Macrobrachium rosenbergii

The iron-catalyzed NADH-dependent lipid peroxidation system in sarcoplasmic reticulum (SR) of cultured white shrimp, Litopenaeus vannamei and freshwater prawn, Macrobrachium rosenbergii was characterized. Production of thiobarbituric acid reactive substances was used to measure the activity of lipid peroxidation. In both species, the system preferred NADH to NADPH as the reducing agent. Lipid peroxidation activities of SR from both species increased when reaction temperatures increased from 6 to 26 °C. At 66 °C, the reaction was no longer NADH-dependent. Acidic pH amplified the lipid peroxidation activity. Sarcoplasmic reticular lipid peroxidation activity in white shrimp was always greater than in freshwater prawn. Fatty acid composition of SR lipids could be a major factor for this outcome. The proportion of n–3 highly unsaturated fatty acids, such as C20:5 and C22:6, in sarcoplasmic reticular lipids of white shrimp was twice of that in freshwater prawn. The results of this study provide important tools required for anti-oxidative nutrient study at sub-cellular level.     

L-(3H) glutamate binding to a membrane preparation from the optic lobe of the giant freshwater prawn Macrobrachium rosenbergii de Man.

Membrane preparation from the optic lobe of the giant freshwater prawn, Macrobrachium rosenbergii de Man, was examined for the presence of specific L-(3H) glutamate binding. The optic lobes were isolated from live animals. The tissue was homogenized and the membrane fraction isolated by differential centrifugation. The membrane suspension was incubated with 10-1,000 nM of L-(3H) glutamate at 37 degrees C for 60 min. Nonspecific binding was determined by incubating the mixture with 100 microM L-glutamate. L-(3H) glutamate specifically bound to the membrane fraction with a dissociation equilibrium constant (Kd) of 205 nM and maximum number of binding sites (Bmax) of 2.04 n mol/mg protein. By using LIGAND computerized program, the saturation isotherm binding pattern indicates a single type of binding. To determine the type of glutamate receptors, competitive inhibition and IC50 of several glutamate agonists and antagonists were determined. The study reveals a metabotropic type of binding site.     

The identification and distribution of gonadotropin-releasing hormone-like peptides in the central nervous system and ovary of the giant freshwater prawn, Macrobrachium rosenbergii

In the present study, we demonstrated the existence of GnRH-like peptides in the central nervous system (CNS) and ovary of the giant freshwater prawn, Macrobrachium rosenbergii using immunocytochemistry. The immunoreactivity (ir) of lamprey (l) GnRH-III was detected in the soma of medium-sized neurons located in neuronal cluster number 11 in the middle part of supraesophageal ganglion (deutocerebrum), whereas ir-octopus (oct) GnRH was observed in the soma of both medium-sized and large-sized neurons in thoracic ganglia, as well as in the fibers innervating the other medium-sized and large-sized neuronal cell bodies in the thoracic ganglia. In addition, ir-lGnRH-I was observed in the cytoplasm of late previtellogenic oocyte and early vitellogenic oocyte. These data suggest that M. rosenbergii contain at least three isoforms of GnRH: two GnRH isoforms closely related to lGnRH-III and octGnRH in the CNS, whereas another isoform, closely related to lGnRH-I, was localized in the ovary. This finding provides supporting data that ir-GnRH-like peptide(s) may exist in this decapod crustacean.     

Geographic variation in growth and food conversion efficiency of juvenile Atlantic halibut related to latitude

Higher growth capacity and food conversion efficiency was observed in populations of juvenile halibut from high Hippoglossus hippoglossus compared lower latitudes. In addition, temperature adaptation shown by the lower temperature optimum for growth in the Norwegian population (mean±S.E. 12·9±0·10 C) compared with the Icelandic and Canadian populations (14·2±0·2 and 13·9±0±30 C respectively), seems to occur. Overall the data support the hypothesis of countergradient variation in growth. These results have implications firstly for selection focusing on growth performance in halibut culture; and secondly, for safe prediction of growth, since if countergradient variation in growth performance occurs one cannot assume automatically that a species will respond to the same set of physiological parameters in the same way throughout its range.     

Continuous light increases N-acetyltransferase activity in the optic lobe of the giant freshwater prawn Macrobrachium rosenbergii de Man (Crustacea: Decapoda).

Giant freshwater prawns, Macrobrachium rosenbergii de Man, were reared under three different lighting conditions: continuous darkness (DD), 12 hr of light and 12 hr of darkness (LD 12:12) and continuous light (LL). After one month, the prawns were sacrificed and optic lobes isolated from the eyestalks were determined for N-acetyltransferase (NAT) activities and melatonin concentrations. Gonads were weighed and examined under light microscopy. The optic lobes from LL prawns contained significantly higher activities of NAT than those from LD 12:12 prawns. The melatonin concentrations and size and histological features of the gonads from the three groups of prawns did not differ. The results indicate that continuous light increases NAT activities in the optic lobe of M. rosenbergii but has no drastic effect on gonadal growth.     

Effects of starvation on growth and reproductive apparatus of two immature freshwater snails Biomphalaria pfeifferi and Biomphalaria glabrata (Gastropoda: Planorbidae)

Starvation of immature snails of Biomphalaria pfeifferi and B. glabrata results in an arrest of growth and animals remain immature. Spermatogenesis is limited to spermatogonia (B.g.) or spermatocytes 1 (B.p.). The number and the size of oocytes remain inferior to that of controls. Animals show reduced genital tracts.Once feeding is restored, growth is resumed but wet weight and shell diameter do not reach the same level as in controls. Fecundity and gametogenesis do not differ from that in controls. Genital tracts weight is proportional to body weight.