The Open Access Israeli Journal of Aquaculture Bamidgeh

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1 The Open Aess Isreli Journl of Aquulture Bmidgeh As from Jnury 21 The Isreli Journl of Aquulture - Bmidgeh (IJA) will e pulished exlusively s n on-line Open Aess (OA) qurterly essile y ll AquultureHu ( memers nd registered individuls nd institutions. Plese visit our wesite ( for free registrtion form, further informtion nd instrutions. This trnsformtion from susription printed version to n on-line OA journl, ims t supporting the onept tht sientifi peer-reviewed pulitions should e mde ville to ll, inluding those with limited resoures. The OA IJA does not enfore uthor or susription fees nd will endevor to otin lterntive soures of inome to support this poliy for s long s possile. Editor-in-Chief Dn Mires Editoril Bord Rin Chkrrti Aqu Reserh L, Dept. of Zoology, University of Delhi, Indi Angelo Colorni Dniel Golni Ntionl Center for Mriulture, IOLR Eilt, Isrel The Herew University of Jeruslem Jeruslem, Isrel Pulished under uspies of The Soiety of Isreli Aquulture nd Mrine Biotehnology (SIAMB), University of HwiɄi t Māno Lirry & University of HwiɄi t Māno Aquulture Progrm in ssoition with AquultureHu Hillel Gordin Kiutz Yotvet, Arv, Isrel Sheenn Hrpz Gideon Hult Agriulturl Reserh Orgniztion Beit Dgn, Agriulturl Reserh Orgniztion Beit Dgn, George Wm. Kissil Ntionl Center for Mriulture, IOLR, Eilt, Isrel Ingrid Luptsh Swnse University, Singleton Prk, Swnse, UK Spener Mleh Dept. of Humn Nutrition, Food & Animl Sienes, CTAHR, University of Hwii Constntinos Mylons Amos Tndler Emilio Tildi Jp vn Rijn Zvi Yron Helleni Center for Mrine Reserh, Crete, Greee Ntionl Center for Mriulture, IOLR Eilt, Isrel Udine University Udine, Itly Fulty of Agriulture, The Herew University of Jeruslem, Isrel Dept. of Zoology, Tel Aviv University, Tel Aviv, Isrel ISSN X Isreli Journl of Aquulture - BAMIGDEH. PUBLISHER: Isreli Journl of Aquulture - BAMIGDEH - Kiutz Ein Hmifrtz, Moile Post 2521, ISRAEL Phone: Copy Editor Ellen Rosenerg

2 The Isreli Journl of Aquulture - Bmidgeh, IJA_ , 9 pges The IJA ppers exlusively s peer-reviewed on-line open-ess journl t To red ppers free of hrge, plese register online t registrtion form. Sle of IJA ppers is stritly foridden. Food Deprivtion of Blunt Snout Brem, Meglorm Amlyephl Fingerlings nd the Susequent Effet of Feeding with Different Dietry Strh Levels on Gluose Metolism Minghun Ren 1, 2, Hte-Mihel Hte-Tsion 2, Bo Liu 1, 2, Jun Xie 1, 2, Xinping Ge 1, 2*, Qunln Zhou 1, 2, Lingkun Pn 1 1 Key Lortory of Freshwter Fisheries nd Germplsm Resoures Utiliztion, Ministry of Agriulture, Freshwter Fisheries Reserh Center, Chinese Ademy of Fishery Sienes, Wuxi, Jingsu 21481, Chin 2 Wuxi Fisheries College, Nnjing Agriulturl University, Wuxi, Jingsu 21481, Chin (Reeived , Aepted ) Key words: lunt snout rem; strvtion nd feeding; metolism; enzymes tivities Astrt A study ws onduted to ssess the speifi gluose metoli pthwys of the lunt snout rem (Meglorm mlyephl) fter short strvtion period followed y feeding with different dietry strh levels. Blunt snout rem (54±1.7 g) were fsted for 2 dys, nd then fed with three isonitrogenous nd isolipidi diets ontining %, 3% nd 45% strh, respetively. Fish were smpled on the 1st, 7th, nd 2th dy of strvtion (dy 1S, 7S nd 2S) nd t the 3rd hour (H3) fter the first feeding, nd on the 1st, 3rd, 1th nd 2th dy of feeding (dy 1R, 3R, 1R nd 2R). The results showed tht seven dys strvtion indued shrp derese in heptosomti index, tissue glyogen ontents, plsm triglyerides, nd hepti lipid levels. Plsm protein ontent signifintly deresed on dy 2S. Fish weight nd gluose ontent signifintly deresed with prolonged strvtion. Hepti gluokinse (GK) nd pyruvte kinse (PK) tivities were not signifintly ffeted y short-term strvtion. Gluose-6-phosphte dehydrogense (G6PDH) tivity showed signifint derese on dy 2S. Hepti frutose-1, 6-isphosphtse (FBPse) tivity showed signifint inrese on dy 7S. The level of metoli tivity prior to strvtion returned on dy 1R, with reestlishment of musle nd liver omposition, plsm metolites, nd hepti gluose metoli enzymes tivity. However, liver glyogen ontent reovered fster on dy 3R. High dietry rohydrte levels stimulted GK, PK nd G6PDH enzyme tivity, ut deresed FBPse nd sprtte trnsminse (AST) tivity t H3. The results indited tht gluose is n importnt energy soure for lunt snout rem, whih is moilized s result of nutritionl hllenges. 45% dietry strh level indued fster reovery of glyogen in the liver nd musle, nd signifintly redued the gluoneogenesis pthwy (FBPse tivity) nd the restortion of glyogen from threeron ompounds ompred to groups fed lower strh level t the erly feeding stge. *Corresponding uthor: Xinping Ge, e-mil: gexp@ffr.n; renm@ffr.n The first uthor: Minghun Ren, e-mil: renm@ffr.n

3 Ren et l Introdution Frmed fish my experiene strvtion s result of severl ftors suh s trnsporttion, ute wter temperture hnges, poor quulture proedures, nd speifi medil tretments. Feed deprivtion is lso used in the quulture industry s n effiient tool to improve the prodution qulity, nd to indue ompenstory growth in overstoking situtions (Cruso et l., 212). Hene, it is essentil to know how fish dpt to food deprivtion nd their response to susequent feeding. Generlly, fish redue their energy expenditure whih dittes metoli djustments, nd moilizes ody energy reserves to survive during the food deprivtion period (Pérez-Jiménez et l., 212). However, these djustments re speies speifi. For most fish speies, glyogen nd lipids re utilized s n energy soures in the erly stge of strvtion. With prolonged strvtion, protein is metolized when reserve glyogen nd lipids re prtilly depleted (Pérez-Jiménez et l., 27). In ontrst, some speies protet liver glyogen stores, degrding protein for gluoneogenesis nd using lipid nd protein s energy soures (Gillis nd Bllntyne, 1996). Metoli responses of feeding my e ffeted y fish speies, environmentl onditions, nd previous feeding history (Nvrro nd Gutiérrez, 1995). Composition of diets signifintly influenes the metoli responses during the strvtion nd feeding periods in fish (Pérez-Jiménez et l., 27). Crohydrte is the hepest dietry energy soure, nd the pproprite supplementtion into fish feed my redue the ost of formulted diets, espeilly for herivorous nd omnivorous fish speies. Long term, fish generlly show poor utiliztion of dietry rohydrte ompred to mmmls (Hemre et l., 22). However, during short intervls etween strvtion nd feeding periods, fish, even rnivorous speies, hve the ility to regulte gluose metolism. This suggests tht higher dietry rohydrte levels ould serve s n effetive energy soure fter strvtion in fish (Metón et l., 23). Blunt snout rem, Meglorm mlyephl is Chinese ntive freshwter fish with long history of ultivtion. It is renowned for its exellent flesh qulity, rpid growth, nd high lrvl survivl rte. In previous studies, 31% dietry strh ws estimted to e optiml for growth performne in juvenile fish (Zhou et l., 213) ut needed to e orrelted to the lipid levels in the feeds. The omined effets of dietry lipid nd rohydrte in lunt snout se rem hs een studied (Li et l, 214). However, the mehnism of the intermediry metoli modifitions following nutritionl hllenges remins unler. Bsed on the ove informtion, the present study ws onduted to investigte the metoli mehnisms of lunt snout rem fter short strvtion-feeding period nd the effets of dietry strh levels on their metoli responses during the feeding period. The results will enle us to lern out the gluose metoli strtegy in lunt snout rem during strvtion nd susequent feeding with different rohydrte levels, in order to prevent possile dmge to fish helth, nd optimize the ulture of this speies. Mterils nd Methods Experimentl diet. Three isonitrogenous nd isolipidi diets (32% rude protein nd 8% rude lipid), supplemented with fish mel, sein, nd geltin s protein soures, nd soyen oil s lipid soure, were formulted to ontin grded levels of strh (%, 3% nd 45% of dry weight, respetively). These were repled y equl proportions of ellulose (Tle 1). All the ingredients were ground into powder, thoroughly mixed with soyen oil nd wter, fored though pelletizer (4-2 style, Xinhng mhinery LTD, Chin), nd dried in ventilted oven t 3 C. After drying, the diets were seled in gs nd stored t -15 C until use. Tle 1. Composition nd proximte nlyses of the experimentl diets Diet Ingredients (%) 45% 3% % strh Csein Geltin White fish mel Soyen Oil Soyen leithin Whet strh Mirorystlline Croxyl-methyl Vitmin premix Minerl premix Clium iphosphte Proximte nlysis (%dry mtter) Crude protein Crude lipid Strh Ash Csein, otined from Hu n Biologil Produts Lit. (Gnsu, Chin), rude protein 9.2%; Geltin, otined from Zhnyun hemil Lit. (Shnghi, Chin), rude protein 91.3%; fish mel, otined from Copein (Lim, Peru), rude protein 67.4%, rude lipid 9.3%. 2 Whet strh otined from Gungsheng strh Lit. (Jingsu, Chin). 3 Mirorystlline ellulose, otined from Xinwng hemil Lit. (Zhejing, Chin). 4 Vitmin premix (IU or per kg premix): vitmin A 9 IU, vitmin D, 25 IU, vitmin E 45 mg, vitmin K3 22 mg, vitmin B1 32 mg, vitmin B2 19 mg, vitmin B5 2 mg, vitmin B6 5 mg, vitmin B mg, vitmin C 5 mg, pntothente 1 mg, foli id 165 mg, foli id 165 mg, holine 6 mg. 5 Minerl premix (per kg premix): CuSO 4 5H 2O 2.5g, FeSO 4 7H 2O 28g, ZnSO 4 7H2O 22g, MnSO 4 4H 2O 9g, N 2SeO 3.45g, KI.26g, CoCl 2 6H 2O.1g.

4 Gluose Metolism Responses To Strvtion nd Feeding Experimentl fish nd proedure. Blunt snout rem fingerlings (verge weight 54±1.7g) were otined from ommeril frm (Jingsu, Chin), nd fed with ommeril feed for 2 weeks to limte them to the experimentl onditions. They were then rndomly divided into nine 3L fierglss ylindril tnks with 3 fish per tnk thermo-regulted in reirulted fresh wter system. Therefter, fish were fsted for 2 dys fter whih eh of the diets ws rndomly ssigned to triplite tnks, nd hnd-fed twie dily t 8: nd 16: until pprent stition s ssessed y visul oservtion. During the experiment, the wter temperture ws onstnt 25±.5 C. There were no mortlities during the tril. Smple olletion. Three fish per tnk were rndomly smpled on the 1 st, 7 th, nd 2 th dy of strvtion (dy 1S, 7S nd 2S), nd on the 1 st 3 rd, 1 th nd 2 th dy of feeding (dy 1R, 3R, 1R nd 2R). In ddition, fish were lso smpled t the 3 rd hour (H3) fter the first feeding. Fish were euthnized with MS-222 (1mg/L), nd lood smples were immeditely drwn from the udl veins with heprinzed syringes. Following entrifugtion (35 g, 1 min, 4 C), the plsm ws seprted. Livers nd musles were exised, immeditely frozen in liquid nitrogen nd stored t -8 C until nlysis. Whole ody fish, liver nd viser weights were reorded to determine their heptosomti nd viserl indexes. Lortory nlysis. Dry mtter, rude protein, nd lipid in the diets nd musle were determined ording to estlished methods of AOAC (23): dry mtter fter drying in n oven t 15 C until onstnt weight; rude protein (N 6.25) y Kjeldhl method fter id digestion; lipid y ether extrtion y Soxhlet proedure. Crude protein in the liver ws determined ording to the method of Brdford (1976) using ovine serum lumin s stndrd. Extrtion of lipids from the liver ws performed y the method of Folh et l. (1957). Glyogen ws determined y the method desried y Hssid nd Arhm (1957). Anlyses of gluose nd triglyeride in plsm were rried out on n utomti iohemil nlyzer (Mindry BS-4, Mindry Medil Interntionl Ltd., Shenzhen, Chin), using gluose, totl holesterol nd triglyerides kits (GPO-POD Method) respetively. Hepti enzyme tivities were determined s desried y Pérez-Jiménez et l. (27) nd Metón et l. (1999). Alnine minotrnsferse (ALT) nd sprtte trnsminse (AST) tivities were mesured y detetion kits (Nnjing Jinheng Bioengineering Institute, Chin). Sttistil nlysis. Sttistil nlyses were rried out using the SPSS version 11.5 for Windows softwre pkge. Signifint differenes in the mens mong dietry tretments (e.g. plsm gluose of diet, 3 nd 45% strh on dy 3R) nd mong different smplings (e.g. plsm gluose of diet 45% strh on dy 1S, 7S, 2S, 1R, 3R, 1R, 2R, nd t H3) were evluted y Dunn's multiple rnge tests nd p.5 ws onsidered to e sttistilly signifint. Results re expressed s men ± S.E.M. Results Fish weight nd feed intke. Strvtion indued signifint derese in fish weight tht ws regined on dy 1R (P<.5). There were no signifint differenes mong the tretments. Signifintly higher feed intke vlues were oserved on dy 2R (P<.5) in fish fed with diets ontining 3% nd 45% strh level ompred to those fed the non-strh diet.. Strvtion indued signifint derese in heptosomti index (HSI), while feeding inresed the vlue. Signifintly higher HSI ws oserved in fish fed the diet ontining higher strh levels during the feeding period (P<.5) (Tle 2). Tle 2. Fish weight, feed intke nd heptosomti index of lunt snout rem during strvtion (S) nd feeding (R) period 1 1S 7S 2S 3R 1R 2R Fish weight (g) 45% strh 54.6± ± ± ± ± ±1.23 d 3% strh 54.2± ± ± ± ± ±2.25 d % strh 54.2± ± ± ± ± ±.92 d Feed intke 2 45% strh ± ±.2 2.3±.1 * 3% strh ± ± ±.9 * % strh ± ± ±.6 ** Heptosomti index (%) 45% strh 1.35±.6.76±.3.53±.1 2.6±.9 *** 2.76±.9 d*** 1.91±.11 ** 3% strh 1.36±.8.74±.1.54± ±.7 ** 2.22±.11 ** 2.9±.11 ** % strh 1.35±.8 d.75±.4.53±.4 1.4±.7 * 1.52±.5 d* 1.4±.8 d*

5 Ren et l 1 Vlues re mens± S.E.M.; different supersript letters in the sme row indite signifint differenes (P<.5) mong smpling points in eh group; sterisk indites signifint differenes (P<.5) mong groups t eh smpling point. Feed Intke (FI) s g/fish/dy ws lulted: dry diet fed in g/((wf + Wi)/2 t), t is the experimentl durtion in dys from lst weighing in eh tnk. 2 Fish were not weighed in eh tnk t hour H3 nd dy 1R in order not to stress fish. Feed intke (FI, g/fish/dy) = dry diet fed in g / ((Wf + Wi)/2 t), t is the experimentl durtion in dys from lst weighed in eh tnk. Plsm metolites. Plsm totl protein levels signifintly deresed on dy 2S, nd reovered to the pre-strvtion levels in ll the groups on dy 1R (P<.5). Plsm totl protein levels were similr mong the three groups throughout the experiment (P>.5). On dy 7S, plsm triglyeride levels were shrply redued (P<.5). From dy 7S onwrds, these vlues remined low. Feeding restored the plsm triglyeride to pre-strvtion levels in ll groups from dy 1R. No signifint differenes were oserved mong the three groups (P>.5). Plsm protein nd gluose ontent showed flututing trend during strvtion nd feeding periods. However, signifintly higher plsm gluose levels were found in fish fed diet ontining 45% strh ompred with those fed with diets ontining % nd 3% strh t H3 (P<.5). Results of plsm prmeters re presented in Tle 3. Tle 3. Plsm protein, triglyeride nd gluose ontent of lunt snout rem during strvtion (S) nd feeding (R) period 1 Protein (g/l) 45% strh 35.4± ± ± ± ± ± ± ±1.92 3% strh 35.8± ± ± ± ± ± ± ±1.77 % strh 35.8± ± ± ± ± ± ± ±1.3 Triglyeride (mmol/l) 45% strh 3.2±.5.77±.2.54±.3.41±.4.66± ±.32 d** 3.34±.27 e 2.25±.12 d 3% strh 3.35±.9 f.78±.2.52±.2.39±.4.57± ±.11 * 2.85±.12 e 2.25±.15 d % strh 3.32±.9 d.73±.2.54±.2.44±.4.62± ±.11 * 3.4± ±.15 d Gluose (mmol/l) 45% strh 4.33± ± ± ±.1 ** 2.47± ± ± ±.35 3% strh 4.43±.6 d 2.61± ± ±.1 * 2.28± ± ± ±.35 d % strh 4.51± ± ± ±.5 * 1.9± ± ± ±.68 Vlues re mens± S.E.M.; different supersript letters in the sme row indite signifint differenes (P<.5) mong smpling points in eh group; sterisk indites signifint differenes (P<.5) mong groups t eh smpling point. Liver nd musle omposition. On dy 7S, glyogen ontent in liver nd musle rpidly deresed to extremely low levels fter whih, the vlues remined low. After feeding, glyogen ontent in liver nd musle ws grdully restored. The glyogen levels restored more rpidly in fish fed higher dietry strh levels. From dy 3R, liver nd musle glyogen were signifintly higher in oth the 45% nd 3% groups thn in the % group (P<.5). Musle protein nd hepti protein ontents were reltively onstnt throughout the experiment. Hepti lipid deresed on dy 7S, nd grdully reovered fter dy 3R. However, protein ontent in the whole liver signifintly deresed on dy 1S nd reovered only on dy 1R (P<.5). Results of liver nd musle omposition re present in Tle 4 nd Figure 1 respetively.

6 Musle lipid (%) Musle glyogen (mg/g) Musle protein (%) Gluose Metolism Responses To Strvtion nd Feeding Tle 4. Liver omposition of lunt snout rem during strvtion (S) nd feeding (R) period 1 Protein (%/liver) 45% strh 3.22± ± ± ± ± ± ± ±.45 3% strh 3.42± ± ± ± ±.1 3.2± ± ±.21 % strh 3.9± ± ± ± ± ± ± ±.6 Protein (mg/whole liver) 45% strh 21.6± ± ± ± ± ±1.58 d 6.7±6.4 e 37.6±4.48 d 3% strh 22.9± ± ± ± ± ± ±5.87 e 46.5±9.22 d % strh 21.8± ± ± ± ± ± ±3.28 e 42.6±6.54 d Lipid (%/liver) 45% strh 1.6±.23 d 7.28± ± ± ± ±.42 d 9.55±.42 d 1.9±1.61 d 3% strh 1.6± ± ± ± ± ± ± ±1.4 % strh 1.5± ±.85 7.± ± ± ± ± ±1.26 Glyogen (%/liver) 45% strh 6.82±.19.12±.1.21± ± ± ±.14 ** 7.88±.7 ** 6.15±1.88 3% strh 6.54±.16 d.14±.2.25±.1.99± ± ±.77 ** 7.45±.8 ** 4.49±.3 % strh 6.88±.14 d.13±.1.28± ± ± ±.45 d* 5.7±.18* 4.3±.52 Vlues re mens ± S.E.M.; different supersript letters in the sme row indite signifint differenes (P<.5) mong smpling points in eh group; sterisk indites signifint differenes (P<.5) mong groups t eh smpling point. A B C 7 45% Strh 6 3% Strh 5 ** 4 % Strh ** ** ** 3 ** 2 * 1 * * * % strh 14 3% strh 12 % strh % strh 3% strh % strh Figure 1. Musle glyogen (A), protein (B) nd lipid (C) ontents of lunt snout rem during strvtion (S) nd feeding (R) period. Different letters indite signifint differenes (P<.5) mong smpling points for eh group. Asterisk indites signifint differenes (P<.5) mong groups t eh smpling point. Hepti enzyme tivities. Hepti GK, PK nd G6PDH tivity showed deresing trend on dy 2S (P>.5) nd there were no signifint differenes mong the groups throughout the experiment, exept H3 where higher tivities of these enzymes were oserved in fish fed diets with higher strh levels (P<.5). Hepti FBPse tivity inresed with prolonged strvtion. In % strh group, FBPse tivity ws signifintly higher ompred to tht in strvtion period, nd vlues deresed on dy R3. FBPse tivity inresed on dy 1R in oth 45% nd 3% strh groups. However, fter rehing the pek on dy 1R in 45% strh group nd on dy 3R in 3% strh group, tivity showed deresing trend. The FBPse tivity in fish fed % strh diet ws signifintly higher thn those fed with 3% nd 45% strh diets t H3 (P<.5). Higher vlue of PK: FBPse rtio ws oserved in fish fed diet with higher strh level during the feeding period. Results of hepti gluose enzyme tivities re presented in Figure 2.

7 AST ALT PK: FBPse FBPse G6PDH GK PK A C E ** ** * ** * * 45% Strh 3% Strh % Strh 45% Strh 3% Strh % Strh 45% Strh 3% Strh % Strh 2 C B BC** d d * d 1 BC*** A * A ** A** A * * * Ren et l B D ** * * 45% strh 3% strh % strh % Strh 2 45% Strh 3% Strh Figure 2. Hepti GK (A), PK (B), FBPse (C), G6PDH (D) tivities (mu/mg protein) nd PK: FBPse rtio (E) of lunt snout rem during strvtion (S) nd feeding (R) period. Different letters indite signifint differenes (P<.5) mong smpling points for eh group. Asterisk indites signifint differenes (P<.5) mong groups t eh smpling point. Hepti ALT tivity ws independent of this nutritionl hllenge. However, dy 7S showed signifint inrese in AST tivity. High rohydrte diets promoted high AST tivity (P<.5) t H3 nd dy 1R (Figure 3). A B ** * ** ** * 45% strh 3% strh % strh % strh 3% strh % strh Figure 3. Hepti AST (A) nd ALT (B) tivities (U/mg protein) for lunt snout rem during strvtion (S) nd feeding (R) period. Different letters indite signifint differenes (P<.5) mong smpling points for eh group. Asterisk indites signifint differenes (P<.5) mong groups t eh smpling point.

8 Gluose Metolism Responses To Strvtion nd Feeding Disussion Strvtion period. In this study, seven dys strvtion indued shrp derese of glyogen ontent in the liver nd musle, whih suggests tht glyogen is the first sustrte used s n energy soure t the erly stge of strvtion, s in most fish speies suh s ommon rp, Cyprinus rpio (Shimeno et l., 1997). Similrly delining trends were oserved in hepti lipid ontent, ut not in musle lipid ontent. This suggests tht lipid in the liver ws used for energy in prllel with glyogen utiliztion. If strvtion is prolonged, protein is moilized s n energy soure in some fish speies (Nvrro nd Gutiérrez, 1995; Metón et l., 23). In this study, signifintly lower plsm protein levels were oserved on dy 2S ompred to the vlues on dy 7S nd 1S, wheres protein levels in liver nd musle were not ffeted y strvtion. The solute totl protein quntity of the whole liver is meningful physiologil mesurement (Nvrro nd Gutiérrez 1995); in ft it did deline on dy 2S ompred to dy 1S nd 7S in this study, suggesting tht protein in lunt snout rem ould e used s the energy soure fter most glyogen nd lipid were onsumed. In the present study, there ws ontinuous redution in plsm gluose level during the strvtion period, whih ws in greement with the reports on Europen se ss (Pérez-Jiménez et l., 27), sturgeon, nd rinow trout, Onorhynhus mykiss (Furné et l., 212). However, ompred to plsm triglyeride, the redution of lood gluose ontent ws slight in this study, nd the plsm gluose mintenne ws diretly relted to the pity to moilize liver glyogen t dy 7S. Blood gluose mintenne my e due to metoli dpttion involving the derese of glyolysis nd the pentose phosphte pthwy enzymes tivities, nd inrese of gluoneogeni enzyme tivity (Csers et l., 22). In this study, gluoneogeni enzyme tivity (FBPse) ws signifintly stimulted on dy 2S, nd the tivity of hepti GK, PK, nd G6PDH, showed deresing trend. These results indited tht during the strvtion period, the soure of metolized gluose ould derive from glyogen nd gluoneogeni pthwy in lunt snout rem. ALT nd AST enzyme tivity re the most importnt mino trnsferses in fish (Cowey nd Wlton, 1989). The effets of strvtion on ALT nd AST tivity in fish were speies dependent, s oth inreses nd no hnges fter strvtion hve een reported (Moon nd Johnston, 1981; Cowey nd Wlton, 1989; Kim et l., 1992). In this study, nutritionl sttus did ffet hepti AST tivity, ut not ALT tivity inditing tht AST plys more prominent role in protein moiliztion ompred to ALT in lunt snout rem. Feeding period. There were no signifint differenes in fish weight mong the tretments during the feeding period. Blunt snout rem seem to hve the ility to regulte lood gluose levels effiiently fter erly feeding, whih is similr to results in previous report on this speies (Li et l., 213). The ility to regulte lood gluose possily involves gluose metoli enzyme hnges t the erly stge of refeeding. At H3, signifintly higher level of plsm gluose ws oserved in fish fed 45% strh diet ompred to those fed % nd 3% strh diets, whih ws in response to improving glyolysis (GK nd PK tivity) nd pentose phosphte pthwy (G6PDH tivity), nd reduing gluoneogenesis (FBPse tivity) pthwy. This differed to the report on gilthed se rem, rnivorous speies. In gilthed se rem, PK, FBPse, G6P-DH nd 6PG-DH tivities were reovered to the levels on dy 1R (Metón et l., 23). These differenes might suggest tht herivorous fish n utilize higher dietry rohydrte levels ompred to rnivorous speies. Liver glyogen ontent returned to pre-strvtion levels in fish fed three different diets on dy 3R, nd reovery speed ws fster thn tht of protein nd lipid in this study, inditing tht lunt snout rem initilly restores glyogen levels t the erly stge of refeeding. On the other hnd, 3 dys feeding were not suffiient to redue hepti FBPse tivity in fish fed % strh, nd the vlues inresed stedily until dy 1R, similrly to gilthed serem Sprus urt, (Metón et l., 23). However, FBPse tivity ws signifintly redued in fish fed diet ontining 45% strh in the present study, whih indited tht dietry strh supplementtion ould improve glyogen restortion diretly, nd redue the ontriution of three-ron ompounds vi gluoneogenesis (Pilkis nd Grnner, 1992). In the present study, higher vlues of PK:FBPse rtio were oserved in fish fed diets with higher strh levels throughout the feeding period, inditing n inrese in glyolysis nd thus metoli dpttion to high-rohydrte diets. During the feeding period, high dietry rohydrte ould stimulte the glyolysis pthwy in order to metolize the exess gluose to produe pyruvte in lunt snout rem. Similr results hve een reported in some rnivorous fish speies suh s in gilthed se rem (Metón et l., 1999). In previous study, the dministrtion of high rohydrte diets lso inresed the liver PK tivity in juvenile lunt snout rem fter longterm feeding tril (Li et l., 213). In ontrst, no indution of PK tivity y dietry rohydrtes

9 Ren et l ws oserved in some rnivorous fish speies (Surez et l., 22; Dis et l., 24; Enes et l., 28). At H3 nd dy 1R, signifintly lower hepti AST tivity ws oserved in fish fed the 45% strh diet ompred to those fed % strh diet. A possile explntion is tht high dietry rohydrte levels in feeds redue utiliztion of mino ids s sustrte for gluoneogenesis t erly feeding stges. Our results further onfirmed tht exess dietry protein nd lipid intke y the lower dietry strh group is proly utilized to replenish the hepti glyogen. We n onlude tht gluose is n importnt energy soure in lunt snout rem, nd is moilized from glyogen nd gluoneogenesis pthwy during the strvtion period. Juvenile lunt snout rem, s herivorous fish speies fed diets ontining 45% strh, experiened rpid metoli djustments fter food deprivtion. Aknowledgements This study ws finnilly supported y Speil Fund for Agro-sientifi Reserh in the Puli Interest (2132), the Ntionl Nturl Siene Foundtion of Chin ( ), Chinese Ademy of Fishery Sienes nd the Modern Agriulture Industril Tehnology System speil projet, the Ntionl Stple Freshwter Fish Industril Tehnology System (CAS-46). Referenes AOAC (ssoition of offiil nlytil hemists), 23. Offiil methods of nlysis, 15th ed. Assoition of Offiil Anlytil Chemists, In., Arlington, VA. Brdford M.M., A rpid nd sensitive method for the quntittion of mirogrm quntities of protein utilizing the priniple of protein-dye inding. Anlytil Biohemistry, 72: Cruso G., Denro M.G., Cruso R., Genovese L., Mnri F. nd G. Mrihiolo, 212. Short fsting nd refeeding in red porgy (Pgrus pgrus, Linneus 1758): Response of some hemtologil, iohemil nd non speifi immune prmeters. Mrine Environmentl Reserh, 82: Csers A., Metón I., Vives C., Ege M., Fernández F., nd I.V. Bnnte, 22. Nutritionl regultion of gluose-6-phosphtse gene expression in liver of Sprus urt. British Journl of Nutrition, 88: Cowey C.B., nd M.J. Wlton, Intermediry metolism. In Fish Nutrition, pp [JE Hlver, editor]. Sn Diego, CA: Ademi Press. Dis J., Rued-Jsso R., Pnsert S., d Coneição L.E.C., Gomes E.F. nd M.T. Dinis, 24. Effet of dietry rohydrte-to lipid rtios on growth, lipid deposition nd metoli hepti enzymes in juvenile Seneglese sole (Sole seneglensis, Kup). Aquulture Reserh, 35: Enes P., Pnsert S., Kushik S. nd A. Oliv-Teles, 28. Growth performne nd metoli utiliztion of diets with ntive nd wxy mize strh y gilthed se rem (Sprus urt) juveniles. Aquulture, 274: Folh J., Lees M. nd G.H. Slone-Stnley, A simple method for the isoltion nd purifition of totl lipides from niml tissues. Journl of Biologil Chemistry, 226: Furné M., Morles A.E., Trenzdo C.E., Grí-Gllego M., Hidlgo M.C., Domezin A. nd A. Snz, 212. The metoli effets of prolonged strvtion nd refeeding in sturgeon nd rinow trout. Journl of Comprtive Physiology, 182B: Gillis T.E. nd J.S. Bllntyne, The effets of strvtion on plsm free mino id nd gluose onentrtions in lke sturgeon. Journl of Fish Biology, 49: Hssid W.Z., nd S. Arhm, Chemil proedures for nlysis of polyshrides. In: Methods in Enzymology, Vol.3 (ed. y S.P. Colowik & N.O. Kpln), pp Ademi Press, NewYork, NY, USA. Hemre G-I., Mommsen T.P., nd Å. Krogdhl, 22. Crohydrtes in fish nutrition: effets on growth, gluose metolism nd hepti enzymes. Aquulture Nutrition, 8: Kim K.I., Grimshw T.W., Kyes T.B., nd C.H. Amundson, Effet of fsting or feeding diets ontining different levels of protein or mino ids on the tivities of the liver mino iddegrding enzymes nd mino id oxidtion in rinow trout (Onorhynhus mykiss). Aquulture 17:

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