Effects of environmental salinity on somatic growth and growth hormone/insulin-like growth factor-I axis in juvenile tilapia <Emphasis Type="Italic">Oreochromis mossambicus</Emphasis>     

Sameh Magdeldin  Katsuhisa Uchida  Tetsuya Hirano  Gorron Grau  Ahmed Abdelfattah  Masumi Nozaki 《Fisheries Science》2007,73(5):1025-1034

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Effects of environmental Ca²⁺ levels on branchial chloride cell morphology in freshwater-adapted killifish Fundulus heteroclitus     

FUMI  KATOH  TOYOJI  KANEKO 《Fisheries Science》2002,68(2):347-355

ABSTRACT: To examine the involvement of chloride cells in the uptake of Ca²⁺ in freshwater (FW) killifish, chloride cell morphology was compared in fish acclimated to different defined FW environments with Ca²⁺ concentrations of either 0.1 mM, 0.5 mM, or 2.5 mM. Numerous chloride cells were detected in whole-mount preparations of the gill filaments, which were stained with an antiserum specific for Na⁺, K⁺-ATPase. Chloride cells, located mostly on the afferent–vascular edge of the filaments, were larger at lower Ca²⁺ concentrations. Electron microscopic observations showed that in the 0.1 mM and 0.5 mM Ca²⁺ experimental groups, the apical membrane of chloride cells were flat or slightly projecting and equipped with numerous microvilli. In the 2.5 mM Ca²⁺ group, some chloride cells formed an apical pit, whereas other cells were similar to those observed in the 0.1 mM and 0.5 mM Ca²⁺ groups. Plasma osmolality decreased with decreasing ambient Ca²⁺ concentration, suggesting that environmental Ca²⁺ affects the permeability of the body surfaces. Gill Na⁺, K⁺-ATPase activity in the 0.1 mM and 0.5 mM Ca²⁺ groups were significantly higher than that in the 2.5 mM Ca²⁺ group, implying the involvement of the Na⁺–Ca²⁺ exchanger in Ca²⁺ uptake in the gills. These findings suggest that chloride cells function as the site for Ca²⁺ uptake in killifish acclimated to low Ca²⁺ environments.  相似文献   

Morphological changes in gill mitochondria-rich cells in cultured Japanese eel <Emphasis Type="Italic">Anguilla japonica</Emphasis> acclimated to a wide range of environmental salinity     

Mi Young Seo  Kyung Mi Lee  Toyoji Kaneko 《Fisheries Science》2009,75(5):1147-1156

Morphological changes in gill mitochondria-rich (MR) cells were examined in cultured Japanese eel acclimated to deionized freshwater (DFW), freshwater (FW), 30%-diluted seawater (DSW), and seawater (SW). The gill Na⁺/K⁺-ATPase activity was higher in SW-acclimated eel than in those acclimated to DFW, FW, and DSW. Immunocytochemical observations revealed that MR cells in the gill filaments were most developed in SW, whereas MR cells in the lamellae were preferentially observed in DFW, suggesting that filament and lamellar MR cells are responsible for ion secretion and absorption, respectively. In scanning electron microscopic observations, the apical membrane of lamellar MR cells appeared as a flat or slightly projecting disk with a mesh-like structure on its surface. In contrast, the apical membrane of filament MR cells showed a slightly concave surface. Whole-mount immunocytochemistry revealed that most MR cells showed cystic fibrosis transmembrane conductance regulator immunoreaction in their apical region in fish in DSW and SW, but not in those in DFW and FW, indicating that MR cells developed in DSW and SW function as an ion-secreting site. In addition to MR cells, distinct Na⁺/K⁺-ATPase immunoreaction was observed in the outermost layer of gill epithelia, suggesting that pavement cells are an additional site of ion uptake in the gills.  相似文献   

Transcriptional regulation of the Na<Superscript>+</Superscript>-NADH:quinone oxidoreductase gene, <Emphasis Type="Italic">nqr</Emphasis>, in <Emphasis Type="Italic">Vibrio anguillarum</Emphasis>, a fish pathogen,in the stationary phase     

Erina Fujiwara-Nagata  Yoko Eguchi  Ryutaro Utsumi  Mitsuru Eguchi 《Fisheries Science》2007,73(2):348-355

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Low-salinity tolerance of juvenile fugu <Emphasis Type="Italic">Takifugu rubripes</Emphasis>   总被引：1，自引：0，他引：1  

Kyung?Mi?Lee  Toyoji?KanekoEmail author  Katsumi?Aida 《Fisheries Science》2005,71(6):1324-1331

ABSTRACT:   To study the adaptability of juvenile fugu Takifugu rubripes to low-salinity environments, fish were transferred from full-strength seawater (100% SW) to freshwater (FW) and 25, 50, 75 and 100% SW, and checked for mortality over 3 days. No mortality was observed in 25–100% SW, whereas all fish died in FW. In fish transferred to 25–100% SW, blood osmolality was maintained within a physiological range. To further explore the lower limit of salinity that fugu could tolerate, fish were transferred from 100% SW to FW and 1, 5, 10, 15 and 25% SW. All fish survived in 5–25% SW, but fish died in FW and 1% SW. In fish surviving transfer to FW and 1 and 5% SW, blood osmolality was decreased to a near sublethal level of approximately 300 mOsm/kg·H₂O. Therefore, the lower limit of salinity tolerance is estimated to lie between 5 and 10% SW. Preacclimation in 25% SW for 7 days did not essentially affect the survival salinity range. Although survival rates and blood osmolality were slightly improved by preacclimation in 25% SW, blood osmolality was markedly decreased in salinities less than 10% SW, as was seen in the direct transfer. Neither chloride cell morphology nor sodium-potassium adenosinetriphosphatase activity in the gills showed a significant change following transfer to low salinities. These findings indicate that fugu can be adapted to hypoosmotic environments to some extent, exerting hyperosmoregulatory ability, although chloride cells are less likely to absorb ions in hypoosmotic environments.  相似文献   

Immunolocalization of chloride transporters to gill epithelia of euryhaline teleosts with opposite salinity-induced Na<Superscript>+</Superscript>/K<Superscript>+</Superscript>-ATPase responses     

Tang CH  Hwang LY  Shen ID  Chiu YH  Lee TH 《Fish physiology and biochemistry》2011,37(4):709-724

Opposite patterns of branchial Na⁺/K⁺-ATPase (NKA) responses were found in euryhaline milkfish (Chanos chanos) and pufferfish (Tetraodon nigroviridis) upon salinity challenge. Because the electrochemical gradient established by NKA is thought to be the driving force for transcellular Cl⁻ transport in fish gills, the aim of this study was to explore whether the differential patterns of NKA responses found in milkfish and pufferfish would lead to distinct distribution of Cl⁻ transporters in their gill epithelial cells indicating different Cl⁻ transport mechanisms. In this study, immunolocalization of various Cl⁻ transport proteins, including Na⁺/K⁺/2Cl⁻ cotransporter (NKCC), cystic fibrosis transmembrane conductance regulator (CFTR), anion exchanger 1 (AE1), and chloride channel 3 (ClC-3), were double stained with NKA, the basolateral marker of branchial mitochondrion-rich cells (MRCs), to reveal the localization of these transporter proteins in gill MRC of FW- or SW-acclimated milkfish and pufferfish. Confocal microscopic observations showed that the localization of these transport proteins in the gill MRCs of the two studied species were similar. However, the number of gill NKA-immunoreactive (IR) cells in milkfish and pufferfish exhibited to vary with environmental salinities. An increase in the number of NKA-IR cells should lead to the elevation of NKA activity in FW milkfish and SW pufferfish. Taken together, the opposite branchial NKA responses observed in milkfish and pufferfish upon salinity challenge could be attributed to alterations in the number of NKA-IR cells. Furthermore, the localization of these Cl⁻ transporters in gill MRCs of the two studied species was identical. It depicted the two studied euryhaline species possess the similar Cl⁻ transport mechanisms in gills.  相似文献   

Using Efinol^®L during transportation of marbled hatchetfish, Carnegiella strigata (Günther)     

Levy Carvalho Gomes  Richard Philip Brinn  Jaydione Luiz Marcon  Lucelle Araújo Dantas  Franmir Rodrigues Brandão  Janessa Sampaio de Abreu  Dawn Michelle McComb  & Bernardo Baldisserotto 《Aquaculture Research》2008,39(12):1292-1298

The objective of this experiment was to test the efficacy of a probiotic (Efinol^®L) during transportation of marbled hatchetfish, Carnegiella strigata . Wild specimens were captured from a small stream and transported for 24 h in plastic fish boxes with a probiotic (10 mg L⁻¹) and probiotic-free water. The boxes were sampled at 3, 12 and 24 h of transport. At the end of the experiment, the survival rate was close to 100% in both treatments. Dissolved oxygen diminished with time in both treatments, but the probiotic group had significantly higher levels. Conductivity, pH and ammonia increased significantly during the transport, demonstrating higher levels in the probiotic-free group. Fish from both treatments presented very high net Na⁺ and K⁺ effluxes after 3 h of transport. At 24 h, net K⁺ effluxes in fish of the probiotic treatment reached values close to zero and a significantly lower Na⁺ efflux was observed. Cortisol levels in both treatments at 3 and 12 h were significantly higher than that in control samples. Higher body cortisol levels were observed in the probiotic-free group than that in the probiotic group at 3 and 12 h. The results demonstrate that addition of a probiotic during fish transport improves water quality and leads to fish presenting a lower stress response intensity.  相似文献   

Purification and characterization of the amylase from a small abalone <Emphasis Type="Italic">Haliotis sieboldii</Emphasis>     

Meng-Shun Hsieh  Li-Jung Yin  Shann-Tzong Jiang 《Fisheries Science》2008,74(2):425-432

ABSTRACT:   Amylase, with MW of 59 kDa, was purified from small abalone Haliotis sieboldii by ammonium sulfate fractionation, CM Sepharose Fast Flow and Sephacryl S-100 HR chromatographies. The optimal pH and temperature of purified amylase were 6.0 and 37°C, respectively. The purified enzyme was stable at pH 6.0–8.0 and low temperatures. It was activated by Ba²⁺, Mg²⁺, Ca²⁺, Co²⁺, Ni²⁺, Mn²⁺, K⁺, Ag⁺, Na⁺ and Li⁺, but completely or partially inhibited by Al³⁺, Cu²⁺, Cd²⁺, Hg²⁺ and Zn²⁺. EDTA could completely inhibit, while iodoacetamide, N-ethylmaleimide and urea partially inhibit the purified amylase. According to the digestion mode of various polysaccharides, the purified enzyme was considered to be an α-amylase.  相似文献   

Comparison of physiological smolt status in descending and nondescending wild brown trout (Salmo trutta) in a Danish stream     

C. Nielsen  K. Aarestrup  S. S. Madsen 《Ecology of Freshwater Fish》2006,15(2):229-236

Abstract –  Downstream movement of a wild population of brown trout was examined in a small Danish stream in relation to morphological and physiological smolt status from March to May. Downstream movement was monitored in a Wolf-type trap covering all possible passage routes in the stream. Trout caught in the trap were classified as parr, pre-smolt or smolt based on morphological criteria and compared with trout randomly caught by electrofishing upstream of the trap. Representative gill samples from trap-caught and electrofished trout were analysed for gill Na⁺, K⁺-ATPase activity and used as a measure of physiological smolt status. Only a few parr occurred in the trap. Few pre-smolts occurred in the trap evenly in March and early April. In late April, pre-smolt movement peaked. By comparison, the main downstream movement of smolts occurred in distinct peaks through late March and April. The majority of fish caught in the trap were judged as pre-smolts or smolts based on morphological criteria's and they were characterised by relatively high gill Na⁺, K⁺-ATPase activity compared with trout judged as parr. Trout caught by electrofishing upstream the trap, were classified as parr, pre-smolts and smolts early in the season (March). During and after the main smolt-run in April the distribution of the remaining trout in the brook became skewed in favour of pre-smolt and parr. The study suggests that smolting trout initiate downstream movement once having reached a certain physiological smolt condition (judged by increased gill Na⁺, K⁺-ATPase activity).  相似文献   

Comparison of horse mackerel and tilapia surimi gel based on rheological and <Superscript>1</Superscript>H NMR relaxation properties     

Moin?Uddin?Ahmad  Yuri?Tashiro  Shingo?Matsukawa  Hiroo?OgawaEmail author 《Fisheries Science》2005,71(3):655-661

ABSTRACT:   Horse mackerel and tilapia surimi were subjected to six different heat and pressure treatments in order to compare gelation characteristics of easy- and difficult-setting gels, that is, temperature dependence, by observing rheological properties and microscopic molecular mobility. The stress–relaxation and proton spin–spin relaxation time (¹H T ₂) of water were measured for all treated gels. Horse mackerel gel demonstrated higher elasticity, large distribution of the stress–relaxation process, and smaller water ¹H T ₂ than tilapia in both heat and pressure treatments. The water ¹H T ₂ was steeply increased in the pressure treatment at around 294 MPa for both fishes. In contrast, the ¹H T ₂ rarely changed in the heat treatment in spite of the considerable change in rheological properties. From the experimental results, it is considered that the gelation of horse mackerel (easy setting) surimi is induced by highly unfolding and re-aggregation of protein, which contributes to the formation of a strong network structure compared with tilapia in both heat and pressure treatments, and that pressure treatments hardly improve the gel strength of tilapia (difficult setting) surimi. The water ¹H T ₂ measurement was used effectively in order to study gelation characteristics of easy- and difficult-setting fish through observing its molecular dynamics.  相似文献   

A rapid and inexpensive method to assay transport of short chain peptides across intestinal brush-border membrane vesicles from the European eel (Anguilla anguilla)     

T. VERRI  A. DANIELI  S. BAKKE  A. ROMANO  A. BARCA  I. RØNNESTAD  M. MAFFIA  & C. STORELLI 《Aquaculture Nutrition》2008,14(4):341-349

Membrane potential depolarization due to electrogenic peptide transport activity was examined in eel ( Anguilla anguilla ) intestinal brush-border membrane vesicles (BBMV) by monitoring the fluorescence quenching of the voltage-sensitive dye 3,3'-diethylthiadicarbocyanine iodide. Our experimental approach consisted of generating an internal negative membrane potential mimicking in vivo conditions and measuring membrane potential depolarization due to different extravesicular dipeptides. Peptide-dependent membrane potential depolarization was observed in both the presence and absence of extravesicular Na⁺ and was inhibited by diethylpyrocarbonate, which is consistent with the involvement of electrogenic, Na⁺-independent, H⁺-dependent peptide transport activity. Kinetic analysis indicated that peptide-dependent membrane potential depolarization is a saturable process ( K _m,app ∼ 1.5 mmol L⁻¹) and that within the 0.1–10 mmol L⁻¹ peptide range a single carrier system is involved in the transport process. Our results suggest that a peptide transport activity, kinetically resembling the PepT1(Slc15A1)-type-mediated H⁺/peptide cotransport action, can be monitored in eel intestinal BBMV using an easy and inexpensive fluorescence assay.  相似文献   

Insight into nucleotide and Ca<Superscript>2+</Superscript> binding to carp α-actin     

Atsushi Ooi  Hisaaki Soematsu 《Fisheries Science》2007,73(3):684-693

ABSTRACT:   Nucleotides and Ca²⁺ binding to α-actin prepared from ordinary skeletal muscle of carp Cyprinus carpio was studied. When bound Ca²⁺ was removed with ethylenediaminetetraacetic acid, carp α-actin denatured more rapidly than chicken α-actin. Kinetic studies of the denaturation process showed that in the absence of divalent cations, the binding constants of ATP to carp and chicken actin were 5.0 × 10⁴/M and 1.2 × 10⁵/M, respectively. Competitive binding of Ca²⁺ between actin and 8-amino-2-[(2-amino-5-methylphenoxy)methyl]-6-methoxyquinoline-N,N,N',N'-tetraacetic acid (Quin 2) showed that affinity of Ca²⁺ for carp actin was also lower than that for chicken actin by a factor of 1.6. These results indicated that carp actin could relatively easily denature due to the low affinities of these ligands. Enthalpy changes upon ATP binding to carp and chicken actin were −65 kJ/mol and −110 kJ/mol, respectively. Thermodynamic analyses of our results revealed that the entropy change associated with ATP binding to carp actin was significantly smaller than that to chicken actin, suggesting that structural stabilization upon ATP binding was less effective in carp actin.  相似文献   

Functional morphology of chloride cells in killifish Fundulus heteroclitus, a euryhaline teleost with seawater preference     

Toyoji  KANEKO  Fumi  KATOH 《Fisheries Science》2004,70(5):723-733

ABSTRACT:   Recent advances in the functional morphology of chloride cells in killifish Fundulus heteroclitus , a euryhaline teleost with seawater (SW) preference, were reviewed. Immunocytochemical detection of chloride cells with anti-Na⁺/K⁺-ATPase revealed transitional processes of the chloride cell distribution during early life stages. Chloride cells first appear in the yolk-sac membrane at an early embryonic stage, followed by their appearance in the body skin in the later embryonic stages. The principal site for the chloride cell distribution then shifts from the yolk-sac membrane and body skin during embryonic stages to the gills and opercular membrane in larval and later developmental stages. Morphologically distinct SW- and freshwater (FW)-type chloride cells were identified in adult killifish adapted to SW and FW, respectively. Both types of chloride cells are equally active in the two environments, but exert different ion-transporting functions. Following direct transfer of killifish from SW to FW, SW-type chloride cells were transformed into FW-type cells as a short-term response, followed by the promotion of chloride cell replacement as a long-term response. In killifish acclimated to low NaCl (0.1 mM) FW, intense immunoreactivity for vacuolar-type proton pump (V-ATPase) was detected in the basolateral membrane of FW-type chloride cells, whereas the immunoreactivity was much weaker in fish acclimated to FW with higher NaCl concentrations (1.0 and 10.0 mM). These results suggest the occurrence of active ion absorption in FW-type chloride cells and the involvement of V-ATPase in ion-absorbing mechanisms. In view of recent advances in this field, future chloride cell research should be considered in relation to the functional diversity of chloride cells.  相似文献   

Effects of including catla and tilapia in a freshwater prawn–mola polyculture in a rotational rice–fish culture systems     

Mrityunjoy Kunda  M Ekram Azim  M Abdul Wahab  Somen Dewan  M Abdul Majid  & Shakuntala H Thilsted 《Aquaculture Research》2009,40(9):1089-1098

An on-farm trial was carried out from February to June 2006 to evaluate the growth and production performance of catla ( Catla catla ) and tilapia ( Oreochromis niloticus ) with freshwater prawn ( Macrobrachium rosenbergii ) and mola ( Amblypharyngodon mola ) in farmer's rice fields. In all treatments, 20 000 mola ha⁻¹ and 20 000 prawn ha⁻¹ were stocked. Besides, stocking included 2500 catla ha⁻¹ in treatment-I, 2500 tilapia ha⁻¹ in treatment-II and catla and tilapia at 1250 ha⁻¹ each in treatment-III . Prawns were fed in the evening with pellets at a feeding rate of 3–8% body weight (initially 8% and gradually decreased to 3%). Catla and tilapia were fed in the morning with a paste of mustard oil cake and rice bran at a feeding rate of 3% body weight. Significantly higher combined production of fish and prawn observed was 2142 kg ha⁻¹ in treatment-I. The benefit:cost ratio was found to be significantly higher in treatment-I than in treatment-II and there were no differences between treatments I and III. From the production and economic point of view, treatment-I was found to be the best proposition for the rotational rice–fish culture systems.  相似文献   

Metabolic costs of changing the cation–anion difference in the diet of juvenile African catfish Clarias gariepinus (Burchell)     

Dersjant-Li  Verreth  Tijssen  Booms  Verstegen  & Huisman 《Aquaculture Nutrition》2000,6(1):39-45

The influence of dietary cation–anion difference (CAD, Na⁺ + K⁺– Cl^–, mEq kg^–1) on energy metabolism and nitrogen losses in juvenile African catfish Clarias gariepinus (Burchell) was examined in fish exposed to different dietary CAD levels (–146, 116, 497, 713 and 828 mEq kg^–1 diet). The experiment was conducted in open circuit balance respiration chambers over a 3-week period. Five 24-h monitoring periods were carried out at 3-day intervals during the experimental period with O₂ consumption, ammonia and nitrate + nitrite (NO_x) and CO₂ production being measured at 5-min intervals for each chamber. The negative dietary CAD (–146 mEq kg^–1) resulted in the highest energy expenditures (83 kJ kg^–0.8· d^–1). With increasing dietary CAD levels, heat loss gradually decreased to minimum values of 56 kJ kg^–0.8 day^–1 at a dietary CAD level of 713 mEq kg^–1. Consequently, metabolizable energy utilization efficiency (MEU, percentage of retained energy over metabolizable energy) quadratically ( P  < 0.05) increased and reached a maximum at a dietary CAD of 713 mEq kg^–1.  相似文献   

Immunolocalization of Na⁺, K⁺-ATPase-rich cells in the gill and urinary system of Persian sturgeon, Acipenser persicus, fry     

Saber Khodabandeh  Zahra Khoshnood  & Saeide Mosafer 《Aquaculture Research》2009,40(3):329-336

Localization of Na⁺, K⁺-ATPase-rich cells in the gill and urinary system of Acipenser persicus fry was performed through immunofluorescence light microscopy using a mouse monoclonal antibody IgGα₅ raised against the α-subunit of chicken Na⁺, K⁺-ATPase. Different types of epithelia were clearly identified in the gill epithelium: epithelia of branchial arch, interbranchial septum, filament and lamellar epithelium. The Na⁺, K⁺-ATPase-rich cells were found in the epithelia of branchial arch, interbranchial septum, filament, interlamellar region and also in the lamellae. Histologically, the urinary system is divided into head kidney, trunk kidney and short caudal kidney. The head kidney is composed of the pronephric tubules and the haemopoietic tissues, while the trunk kidney is composed of a large number of glomeruli and convoluted nephrons. Each nephron consisted of a large glomerulus and tubules (neck, proximal, distal and collecting tubules) which connected to ureters. Posteriorly, ureters extended and joined together to form a small urinary bladder. In the urinary system, no specific fluorescence staining was observed in the glomerulus, neck segment and proximal tubules. The distal tubule cells and collecting tubule cells showed a strong immunostaining of Na⁺, K⁺-ATPase. Epithelia of ureters and urinary bladder also showed several isolated immunofluorescent cells. Immunofluorescent cells were rich in Na⁺, K⁺-ATPase enzyme which is very important for osmoregulation.  相似文献   

Growth performance of gilthead sea bream Sparus aurata in different osmotic conditions: Implications for osmoregulation and energy metabolism     

Raúl Laiz-Carrin  Susana Sangiao-Alvarellos  Jos M. Guzmn  María P. Martín del Río  Jos L. Soengas  Juan M. Mancera 《Aquaculture (Amsterdam, Netherlands)》2005,250(3-4):849-861

The influence of three different environmental salinities (seawater, SW: 38 ppt salinity; brackish water, BW: 12 ppt; and low salinity water, LSW: 6 ppt salinity) on the growth, osmoregulation and metabolism of young gilthead sea bream (Sparus aurata L.) was studied over a period of 100 days. 480 inmature fish (20 g mean body weight) were randomly divided into six tanks of 2500 l (80 fish per tank) and maintained under three different salinities (38 ppt, 12 ppt and 6 ppt) in an open system. Every three weeks, 10 fish from each tank were anesthetized, weighed and lenghed. At the end of experiment, 10 fish from each tank were anesthetized, weighed and sampled for plasma, brain, gill and liver. Gill Na⁺, K⁺-ATPase activity, plasma osmolality, ions (sodium and chloride), glucose, lactate, protein and triglyceride, and hepatosomatic index were examined. In addition, levels of glycogen, lactate, ATP and activities of potential regulatory enzymes (hexokinase, pyruvate kinase, glycogen phosphorylase, and glucose 6-phosphate dehydrogenase) were assesed in liver, brain, and gill. BW-acclimated fish showed a better growth with respect to SW- or LSW-acclimated fish (12 > 38 > 6 ppt). The same relationship was observed for weight gain and specific growth rate. Osmoregulatory parameters in plasma (osmolality, Na⁺ and Cl⁻ levels) were similar in SW- and BW-acclimated fish but significantly higher than those of LSW-acclimated fish. Gill Na⁺, K⁺-ATPase activity showed lower values in intermediate salinity (6 > 38 > 12 ppt). No changes were observed in metabolic parameters analyzed in plasma, whereas only minor changes were observed in metabolic parameters of liver, gills and brain that could be correlated with the higher growth rates observed in fish acclimated to BW, which do not allow us to attribute the best growth rate observed at 12 ppt to lower metabolic rates in that salinity.  相似文献   

Expression of insulin-like growth factor I gene is involved in enhanced growth of juvenile four-spine sculpin <Emphasis Type="Italic">Cottus kazika</Emphasis> in seawater     

Hozi?Iwatani  Koji?InoueEmail author  Yoshio?Takei 《Fisheries Science》2005,71(3):621-626

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Carbonic anhydrase and Na/K-ATPase activities at different molting stages of the giant freshwater prawn <Emphasis Type="Italic">Macrobrachium rosenbergii</Emphasis>     

Safiah Jasmani  Vidya Jayasankar  Marcy N Wilder 《Fisheries Science》2008,74(3):488-493

ABSTRACT:   In the present study, the role of carbonic anhydrase (CA) and Na/K-ATPase in the gill and epidermal tissues in the giant freshwater prawn Macrobrachium rosenbergii was examined as a function of molting stage. CA activity levels in the front and back gills were low at the intermolt stage C₀, but increased significantly at premolt stage D₃, and then decreased after molting. In the epidermal tissue, activity levels decreased gradually towards premolt to a minimum level at stage D₃, but became elevated at postmolt stages A and B. Na/K-ATPase levels in the front and back gills did not change significantly during the molt cycle. CA in the gill is possibly involved in supplying counter-ions for ion uptake, while CA in the epidermal tissue may play a role in mineralizing the exoskeleton after ecdysis. Na/K-ATPase in the gills may function in ion uptake from the ambient medium; however, since its activity was not influenced by the molt cycle, it probably does not have a major role in osmoregulation in the freshwater environment.  相似文献   

Growth of juvenile tilapia, Oreochromis niloticus L. from Lakes Zwai, Langeno and Chamo (Ethiopian rift valley) based on otolith microincrement analysis     

D.Admassu  I.Ahlgren 《Ecology of Freshwater Fish》2000,9(3):127-137

Abstract – Age and growth of juvenile tilapia, Oreochromis niloticus , from Lakes Zwai, Langeno and Chamo (Ethiopia) were studied from microincrements in otoliths. Growth in length was best described by the Gompertz model. Average growth rate of the fish was most rapid in Lake Chamo (0.39 mm  ·  day⁻¹, 1.14%  ·  day⁻¹), intermediate in Lake Zwai (0.20 mm  ·  day⁻¹, 0.72%  ·  day⁻¹) and slowest in Lake Langeno (0.16 mm  ·  day⁻¹, 0.62%  ·  day⁻¹). Similarly, back-calculation from otolith increment widths gave growth rates of 0.28 to 0.43 mm  ·  day⁻¹, 0.15 to 0.32 mm  ·  day⁻¹ and 0.11 to 0.28 mm  ·  day⁻¹ for Chamo, Zwai and Langeno fish, respectively. In addition, Fulton's condition factor was largest for Chamo tilapia and smallest for Langeno tilapia; the difference between fish from Langeno and Zwai was small. Rapid growth of juvenile O. niloticus in Lake Chamo was attributed to warm temperature and better food quality. ^Note  相似文献