Triploid induction in the South African abalone, Haliotis midae

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dc.contributor.advisorCook, Peteren_ZA
dc.contributor.authorStepto, Nigel Keithen_ZA
dc.date.accessioned2014-11-15T19:43:48Z
dc.date.available2014-11-15T19:43:48Z
dc.date.issued1997en_ZA
dc.descriptionBibliography: leaves 72-80.en_ZA
dc.description.abstractAn investigation was undertaken to determine whether triploidy could be induced and improve the growth rate of the South African abalone, Haliotis midae. From the polar body counts at 17 °C the release times of polar body 1 and 2 were found to be at 12 - 15 min. post insemination (pi.) and 33-36 min. pi. respectively. Cytochalasin B (CB) (0.5mg. 1-¹ seawater) and elevated temperature (30 °C) were used as stresses to induce triploidy. CB induced 48.4% polar body 1 and 70.9 % polar body 2 triploid larvae at 20 hrs pi. At 120 hrs pi. induction rates were 55.5% and 62.4% respectively. Temperature induction was more successful, producing 92.9% polar body 1 and 86.4% polar body 2 triploid larvae at 20 hrs pi. This success was still evident at 120 hrs pi, where 71.1 % polar body 1 and 62.5% polar body 2 triploid larvae were produced. In the CB induction, where polar body 1 was retained, there was a pronounced production of tetraploid larvae (34. 2%). It appeared that CB affected the ova's resistance to polyspermy, which was found to be dependent on both CB concentration and the amount of excess sperm present. At 0.4 mg 1-¹ CB in seawater, 86.5% triploids and 0% tetraploids were produced. However, on the addition of sperm, 25.4% triploids and 69% tetraploids resulted. CB (0.5 mg 1-¹ ) in seawater produced 42.6%> tetraploids which, after the addition of sperm, increased even further to 50. l % pentaploids. Larval survival was found to be low overall with only 17% and 22% of control (diploid) animals surviving the rearing period, in the temperature and CB treatments respectively. The survival rates of the polar body 2 treatment were 11 % and 15% whilst those of the polar body 1 treatment were 7% and 11 %. Although these percentages indicated a difference in survival rates between the CB and temperature inductions, the actual numbers of larvae surviving were the same. The polar body 1 triploid larval survival was significantly less than both control and polar body 2 triploid animals.en_ZA
dc.identifier.apacitationStepto, N. K. (1997). <i>Triploid induction in the South African abalone, Haliotis midae</i>. (Thesis). University of Cape Town ,Faculty of Science ,Department of Biological Sciences. Retrieved from http://hdl.handle.net/11427/9669en_ZA
dc.identifier.chicagocitationStepto, Nigel Keith. <i>"Triploid induction in the South African abalone, Haliotis midae."</i> Thesis., University of Cape Town ,Faculty of Science ,Department of Biological Sciences, 1997. http://hdl.handle.net/11427/9669en_ZA
dc.identifier.citationStepto, N. 1997. Triploid induction in the South African abalone, Haliotis midae. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Stepto, Nigel Keith AB - An investigation was undertaken to determine whether triploidy could be induced and improve the growth rate of the South African abalone, Haliotis midae. From the polar body counts at 17 °C the release times of polar body 1 and 2 were found to be at 12 - 15 min. post insemination (pi.) and 33-36 min. pi. respectively. Cytochalasin B (CB) (0.5mg. 1-¹ seawater) and elevated temperature (30 °C) were used as stresses to induce triploidy. CB induced 48.4% polar body 1 and 70.9 % polar body 2 triploid larvae at 20 hrs pi. At 120 hrs pi. induction rates were 55.5% and 62.4% respectively. Temperature induction was more successful, producing 92.9% polar body 1 and 86.4% polar body 2 triploid larvae at 20 hrs pi. This success was still evident at 120 hrs pi, where 71.1 % polar body 1 and 62.5% polar body 2 triploid larvae were produced. In the CB induction, where polar body 1 was retained, there was a pronounced production of tetraploid larvae (34. 2%). It appeared that CB affected the ova's resistance to polyspermy, which was found to be dependent on both CB concentration and the amount of excess sperm present. At 0.4 mg 1-¹ CB in seawater, 86.5% triploids and 0% tetraploids were produced. However, on the addition of sperm, 25.4% triploids and 69% tetraploids resulted. CB (0.5 mg 1-¹ ) in seawater produced 42.6%> tetraploids which, after the addition of sperm, increased even further to 50. l % pentaploids. Larval survival was found to be low overall with only 17% and 22% of control (diploid) animals surviving the rearing period, in the temperature and CB treatments respectively. The survival rates of the polar body 2 treatment were 11 % and 15% whilst those of the polar body 1 treatment were 7% and 11 %. Although these percentages indicated a difference in survival rates between the CB and temperature inductions, the actual numbers of larvae surviving were the same. The polar body 1 triploid larval survival was significantly less than both control and polar body 2 triploid animals. DA - 1997 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 1997 T1 - Triploid induction in the South African abalone, Haliotis midae TI - Triploid induction in the South African abalone, Haliotis midae UR - http://hdl.handle.net/11427/9669 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/9669
dc.identifier.vancouvercitationStepto NK. Triploid induction in the South African abalone, Haliotis midae. [Thesis]. University of Cape Town ,Faculty of Science ,Department of Biological Sciences, 1997 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/9669en_ZA
dc.language.isoengen_ZA
dc.publisher.departmentDepartment of Biological Sciencesen_ZA
dc.publisher.facultyFaculty of Scienceen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.subject.otherZoologyen_ZA
dc.titleTriploid induction in the South African abalone, Haliotis midaeen_ZA
dc.typeMaster Thesis
dc.type.qualificationlevelMasters
dc.type.qualificationnameMScen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
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