1997, 21(1).
Abstract:A method to purify the hepatopancreat ic parvovirus of penaeid shrimp f rom the infected t issue by density gradient centrifug at ion using potassium tart rate-glycerol as subst rate is described in this art icle. Taken f rom the heavily infected shrimp populat ion, the hepatopancrea w as ground thoroughly and treated w ith 1, 1, 2-t richlorot rifuoroethane or chloroform. After the concent rat ion w ith 6% ~ 8% of polyethylene glycol ( PEG) , centrifugat ion through a sucrose cushion of 35% ( w/ w ) was performed. Then, the resulted pellet w as resuspended and centifugalized through a density gradient of potassium tart rate-glycerol prepared according to Ashley ( 1982) . It is indicated from the purif icat ion result that the method is as effect ive as the CsCl density gradient cent rifugation yet less expensive.
1997, 21(1).
Abstract:The scale under pectoral f in is selected for the ag e determinat ion material of L utianus r ussell i in the lit toral w aters of Zhangjiang. The relat ionship betw een the leng th of the scale( R) and the body leng th ( L. mm) is L = 19. 815 9 + 63. 369 6R ( r = 0. 991 6) . The relat ionship betw een body length or body w eight (W. g ) and age can be described by the grey dynamic grow th model ( GDGM) and Von Bertalanffy grow th equat ion ( VBGF) . The grow th models are as follow s: Lt 1= 474. 0- 342. 6e - 0. 236t , Wt 1= - 1 594. 4 1 656. 2e - 0. 123t , 1 期 陈 刚: 勒氏笛鲷年龄、生长和生活史类型的研究 11 Lt= 441. 8[ 1- e- 0. 319 1( t 0. 955 2) ] 1 0. 643, Wt= 2 539. 7[ 1- e- 0. 319 1( t 0. 955 2) ] 3. 065 1 0. 643 , Lt= 469. 8[ 1- e - 0. 242 5( t 0. 376 2) ] , Wt= 3 366. 6[ 1- e - 0. 242 5( t 0. 376 2) ] 3 . According to the ty pical characterist ics of r and k select ion and the given values of seven ecolog ical parameters, namely, asymptotic body-length( L) , asymptot ic body-w eight ( W) , growth coeff icient ( k) , instantaneous natural mortality( M) , primary reproduct ive age ( T m) , max imum age ( Tmax ) and populat ion fecundity( PF) , it is concluded that the life-history pattern of L . r ussell i tends to r-select ion. Equilibrium yield model is applied to calculate the f ish y ield. When the instaneous fishing mortality( F) is changed, the yield curve has a w eaker peak at relat ively low value of F, and beyond the value of F, the yield inreases to a max imum value at t c= 1. 5years and then decreases greatly w ith raising t c. Analysis of yield curves also demonstrates that the life-history pat tern inclines to r-select ion. As a st rategy of fishery management , the harvest ing age can be decided above three years of age , the strength of f ishing can not be more than 1. 5. Under the condit ion of artificial raise, the cycle of cult ivat ion can be determined at tw o to three years of age.
1997, 21(1).
Abstract:Heat shocks were used in this experiment for inducing tetraploids through inhibition o f the first cleavage division in the freshwater prawn Macrobrachium nipponense .Te traploidy prawn embryos had been produced by treating egg s at either 38、39 、40 o r 41 ℃ for 1 ~ 2 minute duration from 210 ~ 230 minutes shortly af ter spawning .At 40 ℃ , shock lasting 1.5 minutes yield 36 .8% tetraploidy embryos .The percentage of mosaics were significantly higher than that of tetraploids at shock of either 39 ℃ for 2 minutes.With shock 41 ℃, the mo rtality of embry os was high due to abono rmal kary okinesis at mitosis.Optional treatment time is needed fo r further investigating in o rder to yield hig h percentages of te traploids .
1997, 21(1).
Abstract:Induct ion of t riploidy and tet raploidy in the Chinese mitten-handed crab, Er iochei r sinensis, w as successfully carried out for the f irst time by administration of cytochalasin B( C. B) t reatment to zygotes from January to April in 1992 and January to May in 1993 in Shanghai. Result s of studies shows that the C. B treatment w as feasible for this species in chromosome manipulat ion. In t reatment w ith 0. 5~ 2. 0 mg/ L C. B, begun at 10~ 20 min after insemination and t reatment s last ing 10~ 20mm, the proport ion of t riploid embryo, as judged from chromosome counts, varied between 14. 29% and 58. 18% in this ex periment . Follow ing the results of t riploidy induct ion, tetraploids w ere also produced by treatments for 18 min w ith 1. 5 mg/ L C. B prior to the f irst cleavage. The optimum C. B treatment for inducing tetraploidy appeared to be 9. 2 and 9. 5 h pos-t fert ilizat ion at 20 e , which yielded 56. 94% and 57. 89% tetraploids respectively. The results of observat ion and analysis of the effect of C. B t reatment on the ex tent of embryo development w ere also discussed in this paper. Sterile t riploids could potentially cont inue to moult and grow af ter reaching the mature age of the diploid crab. The successful induction of chromosome polyploidy in the crab has g reat scient if ic significance in conservation and mordern breeding programs in this species.
1997, 21(1).
Abstract:Act ivit ies of several dig est ive enzymes f rom larval Penaeus chinese w ere analyzed w ith the enzyme analy tical method during its ontogenet ic development . The results show ed that there were 4 different pat terns in the act ivit ies of 5 digest ive enzymes from larval praw n. The act ivit ies of pepsin enzyme and t ry ptase increased along w ith the growth of larval praw n, w hile the act ivit ies of amylase decreased. T he activities of cellulase enzyme and lipase w ere fairly low . The act ivit ies of pepsin enzyme, t rytase and amylase changed obviously in feeding habit s transformat ion. T he act ivities of digest ive enzyme f rom larval praw n w ere af fected obviously by the different diets and ontogent ic development . T he authors suggested that the act ivit ies of dig est ive enzyme in the larval praw n w ere associated w ith its genet ic cont rol and liver different iat ion and adjust ing mechnism.
1997, 21(1).
Abstract:Grass carp, Ctenopharyngodon idellus ( C. et V. ) , w eighing about 15g, w ere fed on a cont rol diet and on three treatment diets containing 4, 6 and 8% soybean phospholipids respectively. After a 52- day feeding t rial, the fatty acid composit ion of hepatopancreas lipids w as determined by gas..liquid chromatography. Compared w ith the cont rol g roup f ish, hepatopancreas lipids of the three treatment group fish fed on diets supplemented with soybean phospholipids showed a hig her level of 18..2n- 6 and a low er rat io of 20..4n- 6/ 18..2n- 6. On the contrary, the content of 18..3n- 3 decreased by 30% ~ 69% and that of total n- 3 long..chain ( C ..20) highly unsaturated fatty acids ( n- 3 HUFA: 20..5n- 3, 22..5n- 3 and 22..6n- 3) increased, forming a markedly high rat io of n- 3 HU FA/ 18..3n- 3. The results obtained in this experiment indicated that the supplement of soybean phospholipids to diet s affected the fat ty acid composit ion of hepatopancreas lipids in g rass carp, and improved especially the level of total n- 3 highly unsaturated fatty acids.
1997, 21(1).
Abstract:Eels were kept in experimental tanks w ith aerated tapw ater at temperatures of 23~ 27 e . T he weig ht per fish w as 200~ 300g. The eels w ere fed medicated feed by syringe. T he dosage of Ox ytet racycline ( OTC) w as 200mg/ kg b. w . per day for 5 days. Muscle and liver tissues were taken from five eels at hours 0, 6, 12, 24, 48, 72, 120, 168, 216 af ter the last dose w ith OTC. Tissues samples w ere homogenized w ith 4% t richloroacet ic acid - 0. 02mol/ LNa2HPO4 aqueous solut ion and trichloromethane, fat w as removed by pet roleum ether. The aqueous layer was purified by a C18 solid-phase ext ract ion column. The OTC residues w ere determined by HPLC external standard method using a SGE- ODS- 5 L 250 @ 4. 0mmID column w ith a mobile phase of methano-l acetonit rile-DMF-buffer ( Na2EDTA-citric acid-sodium cit ratew ater) = 1B1. 2B0. 42B1. 9 at UV detect ionwavelength of 360nm. The OT C level in eel muscle reached 1. 0mg/ kg at 24 hours and decreased to 0. 1mg / kg at 168 hours ( 7 days) after w ithdrawal.
1997, 21(1).
Abstract:The dist ribut io n pat terns of Japanese anchovy w ere studied based on the data o f aver age catch per ho ur and reco rding o f echo tra ce o f ancho vy during 7 w inter se asons. The dist ribut ion patterns of co ncent rated anchovy ca n be classif ied as sur face, middle and near bot tom laye rs. 14 typical reco rds of echo t races are useful fo r comme rcial f ishing. The distr ibutio n density o f middle layer is the highest , the density of near bot tom layer is higher than surface layer . The av erage catch per ho ur f rom middle layer, nea r bo t tom layer and sur face layer pat tern by pe lagic tr aw l w ith 520mesh X 600mm net w ere reported to be 5. 0~ 14. 0t , 3. 6~ 4. 5t and 2. 3~ 3. 0t r espect ively.
1997, 21(1).
Abstract:The 960. 000m @ 226. 275m( 107. 800m) mid-water t raw l, widely used in China for Alaska pollack fishing in the North Pacif ic in the 90. s, w as selected as the target net in model test ing through w hich to research the effect of the w idth of side-panel as w ell as the length of w ings and body on the performance of four-panel mid-w ater t raw ls. The result s w ere as follows: ( 1) With the other condit ions unchanged, side-panel w idth has obvious impact on the vert ical opening of four-panel t raw ls. In the tow ing speed of 3. 5 to 5. 0knot net A2, in w hich Lf/ Ld( Lf - the side-panel w idth, Ld-belly-panel width) w as 0. 714, got the greatest vertical opening. When tow ing speed increased to 5. 5knot and more, net A3 w ith Lf/ Ld of 0. 846 reached the top value of vert ical opening . If the Lf / Ld value w ent to the rang e above 1. 0, the vert ical opening decreased w ith the increase of Lf / Ld. It w as found in the model test ing that the smaller the side-panel w idth w as the greater the sw eeping sect ion area would be. ( 2) At low er tow ing speed, shorter w ings w ould result in hig her vert ical opening of net mouth. When t raw ling speed went above 4. 5knot , net B2 of 17. 678% in Ls / La ( Ls-stretched lenth of w ing, La-st retched lenth of full net) obtained the highest vert ical opening value. When Ls/ La w as smaller than 30. 936% the sw eeping sect ion area increased with extention of w ing w hile in the condit ion of Ls/ La above 30. 936% , the sw eeping area w as reversely proport ional to the Ls/ La value. At all tow ing speed, drag force increased w hen w ings leng thened. ( 3 ) When the Lb/ C ( Lb-body leng th, C-st retched circumference of fore part of body ) value w as 25. 554%, the hig hest vert ical opening of net mouth was reached. The change rate of vertical opening at different speed resulted f rom the change of body length w ere directly proport ional to the tow ing speed. As to the changes of energ y consumption coef ficient for net tow ing and that of vertical opening w ith horizontal opening unchanged, the t rends w ere basically the same.
1997, 21(1).
Abstract:T he volat ile compounds of aqueous muscle ext ract of P. or ientali s by GC..MSD w ere ex amined. The experimental data indicated that some compounds such as alkyl py razine, thiazole, pyridine, indole, dithiazine, t rithiolane and so on had great inf luence upon shrimp f lavor. T he model system was set up by the addit ion of proper compounds, such as Gly, Ala, Arg and IMP. The change of major compounds in the dif ferent systems w as discovered. A comparison of volat ile compounds in w ild praw n w ith those in cultured praw n w as also studied. The result s indicated that the major f lavor precusors of P . or ientali s included free amio acids of Gly ,Ary, Ala and Cys, carbonhydrates and water soluble proteins.
1997, 21(1).
Abstract:Muscle content in 1 ~ 2 year-old Catla cat la w as determined .Biochemical composi tio ns of muscle were analysed for the fish of same seasons but dif ferent ages .The water content of muscle decreased g radually , but the contents of protein and fat increased w ith the increase of age .The content s of ash and non-nit rogen ex tract had a lit tle change , while the total content of amino acid had some change with the increase of age .How ever , there w as no regularity among these three co ntents .For the same age f ish , the w ater content of muscle in summer was lower than that of muscle in winter , w hile the contents of pro tein , fat , ash and non-nitrogen ex tract of muscle in summer w ere higher than those of muscle in w inter .The biochemical composi tio n of muscle of 1 year-old Catla cat la and Aristichthys nobi lis w as relatively indentical . For 2 year-old f ish , biochemical composition of muscle of Cat la catla w as hig her than that of A . nobi lis ex cept for the content s of water and ash .The changes in w ater and protein contents and also in w ater and fat content in Cat la catla muscle were of a negative correlat ion .