Transactions of the American Fisheries Socict_v 125 :798-802, l 996 <J Copyright by the American Fisheries Society 1996 Efect of Osmotic Pressure on the Activation and Storage of Channel Catfsh Sperm  C. S A R. A AN N R. S 1 Schooi u/" Forestr, Wildlife, and Fisheries. Louisiana Agricultural Eeriment Stotion Louisiana State Universit Agricultural Center. Baton Rouge, Louisiano 70803. US Abstract.-Artificial paningochannel tsh  rlurus punctatus elieonthemoalotestiandsus penionospemnnetendersoluionrstoragead useinrtiliatioÎ ttle iknown abouteelation ship among omoticpressure spermactiationmotil ity and storaeÏ Our objetives wer to () estimate motlity o chanel catsh sperm diuted in solutions angingnosmoticpresseom8to2 mlliosmols (mosmol)/g (2) identiy theosmotipresurethatin ducesthresholdactatio 10%motiity)andthehih estpesure hainduce comlte activation (3dete mine teroleoionicdilution  acivaton byuse o iondcint olutons and 4 evaluate the ect of osoicpƦessureothe retentionofoilituringstor ageÐ otilitypecntageofactiveysimmingsper waeimated inilted ank balacedsaltsolutin (HBSSandsucrose oltions ora rangeoosmotic presureÑheSSosmoticpressureofthresholdand completeactiationwere218 mosmol/kgand 32   mosmol/g respectivelyÒ e fund that osmotic pƦures aov 220 mosmol/kg ndued minmal 0%actiaionandpressuresbelow 30mosmol/kg nducedcomleteaivationÓihintheoneofincom plete activation 2230mosmol/kg)adeceaseof5 mosolkginosoticresueincreaedmotiltyabout 0 1 Ô uedsucrose solutionstoproideanosmotic environmentwhminialionicnuecerthetesting ofaciaionÕ Osmoticprurerthreshol(214ð  osmol/kg ad complete (125  2 osmolg acti vationereonisentiththoseobtainedwithdiluted HBSS uggesting that reduction in osotic pressue la a major role n the activato ofchannelctish sermÖSpermstoredn 22mosmolgHBlos82 oinialmotiltyaer2×5 hØ owevespermtoredin soltonthhigherosmolalitiesetainedmotilitsig ntly longe (  0Ù001Ú  miimum reduction o omoticpressurtobelow10mosmol/kgesential toinducecompleemotlityochannelcatsh sermf motilityestiates an aticial eƦtiliationÛ Sperm o channel catsh ltalurus punctatus canno ecollectedbystripingthemaleÜhetes ti mus beremoved and hoogenied inan e tendrslutifrstorageÝhessuspensionscan beusedtoproducespecccrosseorhybrdsnot poseby natural spwnngÞ Because sperm ar activated and become motie upon contact with ehwateteymus etoredinaolution . such   whomorepodnc houlde addsedß as ans alanced sal solution (BSS) which hassucientosmoicpressureto maintain rm vablity or be soed indeniely by eans o cryoreservation ierschetalí 994). heactivationochannecashsperhasnev er receiveddrectattentionà partofastudy on cryopreservation uest et î (97a evaluated hreativatorsfrchannelcathspermdiile wate á05% saline solutio and pond waterâ hileeach of theeactivated sperm theosmotic pressureswerenoteportdandteotentialfo thedlution ospeci ionstoactivatespermwꜳs notinvestigatedãThepuroseofthepreentstudy wasto determinethe pecic relationshipamong osotic pressure sperm aciation an motility pecentageofacielyswimmingsperm).urob ectiveweeto()estimate motilityofserdi lutedinsoltionsrangingnosoticpressurefro  mlliomos (mosmol/g (deionied water) o 9 osmol/g ä llstrength BSS) ( ienty theosmoticressuethatinducesthresh oldactivation(l0%oility)andthe hihestpres sure that induces complete actvation in diluted BSS ) determine terole oionicdiution in activation by use of iondecient (sucrose) solu tionsinsteadofBSSand4)evaluatetheefect of ooticpressureonmotilityretentonofchan nelcatsh sper during storaå Methods Experimental animals and collection of 1perm.- hanelcatshusedinthisstuywereodoes ticated pondraised stocæ nterio andposterior testes (Sneedandlemens 19 were suray reovedstoredinvialscontainingBSS(Tiersch eaï 994)orsucrosesolution (295 mosmo/g and transported to the laboratory on iceç o e periment 1thetesteswerecrusedè andsperm weresspede  gtestis/20mof BSSor su crose stoc solution) stored at 4 °  ad stdied within 24 é t this concentation êë uspension of sperminBSS (95 mosmog reutedinare duction of osotic presureof the solutionbyas much as 0 mosmol/g mean  S     mosmol/g)ì o epermen 4  g oftestis was 79