- Email: [email protected]
Induced maturation and development of pinfish eggs
Aquaculture, 8 (1976) 389-393 o Elsevier Scientific Publishing Company, Amsterdam - Printed in The Netherlands
389
Short Communication INDUCED MATURATION AND DEVELOPMENT OF PINFISH EGGS PAUL T. CARDEILHAC Whitney Marine Laboratory, Box 121, St. Augustine, Fla. 32084 and Department of Veterinary Science, Institute of Food and Agricultuml Sciences, University of Florida, Gainesville, Fla. 32611 (U.S.A.) Florida Agricultural Experiment Stations Journal Series No. 5970 (Received January 12th, 1976; revised April 9th, 1976)
ABSTRACT Cardeilhac, P.T., 1976. Induced maturation and development of pinfish eggs. Aquaculture, 8: 389-393. Pelagic eggs of pinfish (Lagodon rhomboides), a common marine teleost found along the Atlantic coast of the southeastern United States, were induced to mature with mammalian gonadotropins and steroid hormones. The eggs were artificially fertilized and subsequent development of the eggs and yolk-sac larvae appeared normal. Yolk-sac larvae at 18” C utilized 50% of the yolk stores in 15 h, and of the oil droplet in 17.4 h.
INTRODUCTION
The pinfish (Lcrgodon rhomboides) is a common species in estuaries of the southeastern United States and has been the subject of many systematic and physiological studies (Hildebrand and Cable, 1938; Caldwell, 1957; Cameron, 1969; Hoss et al., 1973). Natural or hormone-induced spawning of the pinfish has not been reported. The present study describes the use of mammalian gonadotropins to induce the final stage of oocyte maturation in pinfish. Artificial fertilization of the eggs was accomplished and apparently normal development of the embryo and yolk-sac larva occurred. The rate of utilization of yolk and of the oil drop was determined. MATERIAL AND METHODS
Hormones used to stimulate oocyte maturation in females were (a) pituitary luteinizing hormone (PLH) of mammalian origin (Armour-Baldwin Laboratories), a steroid mixture containing estradiol bensoate, testosterone propionate and progesterone (1 : 25 : 25 ratio by weight; Tristers, Zerin Laboratories); and (b) human chorionic gonadotrophin (HCG) (Croval, Eli Lilly). Hormones were not required for spermatogenesis in males during the spawning season.
390
Pinfish weighing approximately 250 g were maintained in tanks of 120-l capacity with flowing sea water (34 + 2.2%;) at 18 f 2.5%. The fish were between 1 and 2 years old; attempts to induce oocyte maturation in the l-year-old fish have been unsuccessful. The fish were fed pellet-size no. 4 Purina Trout Chow and cut fish or squid daily. Eggs in the yolk globule stage (Kuo et al., 1974) and ripe egg stage were obtained’ from the fish by applying gentle pressure to the abdominal wall. Fish with oocytes that had developed to the yolk globule stage were given injections of 1 000 units of HCG and 0.7 mg of the steroid mixture in the muscle mass just below the dorsal fin to induce maturation of the oocytes. Oocytes in the yolk globule stage (Fig. 1A) were approximately 0.5 mm in diameter and contained many yolk globules occupying virtually all of the ooplasm. Eggs from the fish were examined 16 h after the first injection, and a second injection of 5 mg of PLH was given 24 h later if the oocytes had not completed maturation. The oocytes were examined again in 16 h. In the ripe egg stage the eggs had doubled in size. A fusion of the yolk globules as well as oil droplets had occurred to produce a spherical yolk and a single oil drop (Fig. 1B). Volumes of the spherical or ellipsoidal yolk and oil drop were calculated from diameters obtained from photographs of the eggs and of a stage micrometer taken at the same magnification.
F’ig.1. Stages in development of pinfish eggs at 18“ C. A. Yolk globule stage (16 h prior to fertilization). B. Ripe unfertilized egg. C. 16 h (hlaetoderm overgrowth). D. 27 h (26 somites). E. 42 h (prior to hatching). F. 48 h (newly hatched larva). G. Larva (76 h after hatching).
391
RESULTS
Mean diameter (and range) of ripe unfertilized eggs (Fig. 1B) was 1.02 mm (0.99-1.05 mm). Two or three hundred eggs were stripped from the female into a petri dish containing 5 ml of filtered sea water. Approximately 0.5 ml of freshly collected milt was mixed with the eggs. After 10 min, the eggs were transferred to a l-l bottle equipped with gentle aeration. Three-quarters of the eggs reached the early blastula stage in about 3 h; an expanding blastula became evident in 6 h. Late gastrulation occurred and the embryonic axis was evident in 16 h (Fig. 1C). The optic cups and lens were present in 23 h. The oil drop attached to the embryo by 23 h; heartbeat and body twitching were visible at 27 h (Fig. 1D). Most eggs hatched in 48 h at 18°C. The yolk-sac larvae were transferred to petri dishes for observation and rearing. Fifty percent yolk utilization was calculated to occur 15 h after hatching (Fig. 2). Hatching did not occur where more than one oil drop was present. No detectable changes in the volume of the oil drop occurred until after hatching. Fifty percent utilization of the oil droplet occurred 17 h after hatching.
ACKNOWLEDGEMENTS
Photography
by Bill Huck; technical assistance by Mary Smith.
393
10.0
1.0 ::
iiT 0 x y
0.1
3
B J0 >
.Ol
Ferlilizotion I/.OO’
/-Hatch (
30
60
90
120
150
180
HOURS
Fig.2. Utilization of yolk (circles) and oil droplet (triangles) by pinfish yolk-sac larvae. REFERENCES Caldwell, D.K., 1957. The biology and systematics of the pinfish, Lagodon rhomboides (Linnaeus). Bull. Fla. State Mus. Biol. Ser., Z(6): 77-173. Cameron, J.N., 1969. Growth, respiratory metabolism and seasonal distribution of juvenile pinfish (Lagodon rhomboides Linnaeus) in Redfish Bay, Texas. Contrib. Mar. Sci., 14: 19-36. Hildebrand, S.F. and Cable, L.E., 1938. Further notes on the development and life history of some teleosts at Beaufort, N.C. U.S. Bur. Fish, Bull., 48(24): 505-642. Hess, D.E., Hettler Jr., W.F. and Coston, L.C., 1973. Effects of thermal shock on larval estuarine fish-ecological implications with respect to entrainment in power plant cooling systems. In: J.H.S. Blaxter (Editor), The Early Life History of Fish. Springer Verlag, New York, N.Y., pp. 358-371. Kuo, C.-M., Nash, C.E. and Shehadeh, Z.H., 1974. A procedural guide to induce spawning in grey mullet (Mugil cephalus L.). Aquaculture, 3: l-14.
389
Short Communication INDUCED MATURATION AND DEVELOPMENT OF PINFISH EGGS PAUL T. CARDEILHAC Whitney Marine Laboratory, Box 121, St. Augustine, Fla. 32084 and Department of Veterinary Science, Institute of Food and Agricultuml Sciences, University of Florida, Gainesville, Fla. 32611 (U.S.A.) Florida Agricultural Experiment Stations Journal Series No. 5970 (Received January 12th, 1976; revised April 9th, 1976)
ABSTRACT Cardeilhac, P.T., 1976. Induced maturation and development of pinfish eggs. Aquaculture, 8: 389-393. Pelagic eggs of pinfish (Lagodon rhomboides), a common marine teleost found along the Atlantic coast of the southeastern United States, were induced to mature with mammalian gonadotropins and steroid hormones. The eggs were artificially fertilized and subsequent development of the eggs and yolk-sac larvae appeared normal. Yolk-sac larvae at 18” C utilized 50% of the yolk stores in 15 h, and of the oil droplet in 17.4 h.
INTRODUCTION
The pinfish (Lcrgodon rhomboides) is a common species in estuaries of the southeastern United States and has been the subject of many systematic and physiological studies (Hildebrand and Cable, 1938; Caldwell, 1957; Cameron, 1969; Hoss et al., 1973). Natural or hormone-induced spawning of the pinfish has not been reported. The present study describes the use of mammalian gonadotropins to induce the final stage of oocyte maturation in pinfish. Artificial fertilization of the eggs was accomplished and apparently normal development of the embryo and yolk-sac larva occurred. The rate of utilization of yolk and of the oil drop was determined. MATERIAL AND METHODS
Hormones used to stimulate oocyte maturation in females were (a) pituitary luteinizing hormone (PLH) of mammalian origin (Armour-Baldwin Laboratories), a steroid mixture containing estradiol bensoate, testosterone propionate and progesterone (1 : 25 : 25 ratio by weight; Tristers, Zerin Laboratories); and (b) human chorionic gonadotrophin (HCG) (Croval, Eli Lilly). Hormones were not required for spermatogenesis in males during the spawning season.
390
Pinfish weighing approximately 250 g were maintained in tanks of 120-l capacity with flowing sea water (34 + 2.2%;) at 18 f 2.5%. The fish were between 1 and 2 years old; attempts to induce oocyte maturation in the l-year-old fish have been unsuccessful. The fish were fed pellet-size no. 4 Purina Trout Chow and cut fish or squid daily. Eggs in the yolk globule stage (Kuo et al., 1974) and ripe egg stage were obtained’ from the fish by applying gentle pressure to the abdominal wall. Fish with oocytes that had developed to the yolk globule stage were given injections of 1 000 units of HCG and 0.7 mg of the steroid mixture in the muscle mass just below the dorsal fin to induce maturation of the oocytes. Oocytes in the yolk globule stage (Fig. 1A) were approximately 0.5 mm in diameter and contained many yolk globules occupying virtually all of the ooplasm. Eggs from the fish were examined 16 h after the first injection, and a second injection of 5 mg of PLH was given 24 h later if the oocytes had not completed maturation. The oocytes were examined again in 16 h. In the ripe egg stage the eggs had doubled in size. A fusion of the yolk globules as well as oil droplets had occurred to produce a spherical yolk and a single oil drop (Fig. 1B). Volumes of the spherical or ellipsoidal yolk and oil drop were calculated from diameters obtained from photographs of the eggs and of a stage micrometer taken at the same magnification.
F’ig.1. Stages in development of pinfish eggs at 18“ C. A. Yolk globule stage (16 h prior to fertilization). B. Ripe unfertilized egg. C. 16 h (hlaetoderm overgrowth). D. 27 h (26 somites). E. 42 h (prior to hatching). F. 48 h (newly hatched larva). G. Larva (76 h after hatching).
391
RESULTS
Mean diameter (and range) of ripe unfertilized eggs (Fig. 1B) was 1.02 mm (0.99-1.05 mm). Two or three hundred eggs were stripped from the female into a petri dish containing 5 ml of filtered sea water. Approximately 0.5 ml of freshly collected milt was mixed with the eggs. After 10 min, the eggs were transferred to a l-l bottle equipped with gentle aeration. Three-quarters of the eggs reached the early blastula stage in about 3 h; an expanding blastula became evident in 6 h. Late gastrulation occurred and the embryonic axis was evident in 16 h (Fig. 1C). The optic cups and lens were present in 23 h. The oil drop attached to the embryo by 23 h; heartbeat and body twitching were visible at 27 h (Fig. 1D). Most eggs hatched in 48 h at 18°C. The yolk-sac larvae were transferred to petri dishes for observation and rearing. Fifty percent yolk utilization was calculated to occur 15 h after hatching (Fig. 2). Hatching did not occur where more than one oil drop was present. No detectable changes in the volume of the oil drop occurred until after hatching. Fifty percent utilization of the oil droplet occurred 17 h after hatching.
ACKNOWLEDGEMENTS
Photography
by Bill Huck; technical assistance by Mary Smith.
393
10.0
1.0 ::
iiT 0 x y
0.1
3
B J0 >
.Ol
Ferlilizotion I/.OO’
/-Hatch (
30
60
90
120
150
180
HOURS
Fig.2. Utilization of yolk (circles) and oil droplet (triangles) by pinfish yolk-sac larvae. REFERENCES Caldwell, D.K., 1957. The biology and systematics of the pinfish, Lagodon rhomboides (Linnaeus). Bull. Fla. State Mus. Biol. Ser., Z(6): 77-173. Cameron, J.N., 1969. Growth, respiratory metabolism and seasonal distribution of juvenile pinfish (Lagodon rhomboides Linnaeus) in Redfish Bay, Texas. Contrib. Mar. Sci., 14: 19-36. Hildebrand, S.F. and Cable, L.E., 1938. Further notes on the development and life history of some teleosts at Beaufort, N.C. U.S. Bur. Fish, Bull., 48(24): 505-642. Hess, D.E., Hettler Jr., W.F. and Coston, L.C., 1973. Effects of thermal shock on larval estuarine fish-ecological implications with respect to entrainment in power plant cooling systems. In: J.H.S. Blaxter (Editor), The Early Life History of Fish. Springer Verlag, New York, N.Y., pp. 358-371. Kuo, C.-M., Nash, C.E. and Shehadeh, Z.H., 1974. A procedural guide to induce spawning in grey mullet (Mugil cephalus L.). Aquaculture, 3: l-14.