de VLAMING: CONTROL OF FATTENING IN NOTEMIGONUS 



was observed in F. similis acclimated to a short 

 photoperiod during July and treated with this in- 

 dolamine (de Vlaming, Sage, Charlton, and Tiegs 

 1974). These investigators concluded that the 

 pineal might be somehow involved in regulating 

 body fat reserves in teleosts. The data of de 

 Vlaming, Sage, Charlton, and Tiegs (1974) and 

 others (Fenwick 1970; Urasaki 1972a, b, c) indicate 

 that the influence of the pineal on physiological 

 functions in teleosts may vary depending on 

 season and photoperiod conditions. 



The objectives of the present investigation were 

 to examine the effects of various photoperiod- 

 temperature regimes on body lipid reserves in the 

 cyprinid teleost Notemigonus crysoleucas and to 

 determine if pinealectomy altered the response of 

 this fish to the experimental regimes. The possible 

 relationship between reproductive activity and 

 body fat reserves was also examined. That is, the 

 effects of photoperiod-temperature regimes and 

 pinealectomy on reproductive activity were de- 

 termined and compared to the data on fat me- 

 tabolism. The effects of pinealectomy on 

 reproductive activity and fattening were 

 examined during different phases of the natural 

 sexual cycle (at various times of the year) to de- 

 termine if physiological responses vary seasonally. 



MATERIALS AND METHODS 



Samples of A'^. crysoleucas were collected in 

 ponds around the area of Menomonee Falls, Wis. 

 (lat. 43°10'N) at several different times during the 

 year. The reproductive cycle consists of a spawn- 

 ing season which extends from May through July. 

 There is a postspawning season during August 

 and September in which the gonads regress. From 

 October through February there is a gonadal 

 preparatory period, in which spermatogonia 

 proliferate slowly and spermatocytes appear in 

 the testes. Vitellogenesis is initiated during this 

 period. March and April can be referred to as the 

 prespawning period; during this time, final 

 gonadal maturation occurs (i.e., spermatozoa fill 

 the testes and ovaries are distended with mature 

 oocytes). Several fish from each field sample were 

 sacrificed, the gonads examined and body lipid 

 levels determined at the time of collection; these 

 fish served as a reference for the experiments that 

 followed. In the following discussion the fish 

 sacrificed at the time of collection will be identified 

 as initial controls. 



Sham operated and pinealectomized fish were 

 maintained under various photoperiod and con- 

 stant temperature regimes (see Results) in 114- or 

 285-liter tanks supplied with aerated and filtered 

 dechlorinated tap water. Temperatures selected 

 for these experiments are within the range nor- 

 mally experienced during the year in nature by 

 this species. Illumination was a combination of 

 incandescent and cool white fluorescent bulbs 

 which gave a light intensity of 200 to 275 Ix at the 

 surface of each tank. Fish were fed ad libitum on a 

 commercial fish food (Tetra-Min)-; animals main- 

 tained at warm temperatures were fed twice daily 

 whereas fish at low temperatures were fed only 

 once a day. All Notemigonus used in these studies 

 weighed between 12 and 17 g. 



For pinealectomies, fish were anesthetized in 

 buffered tricaine methane-sulfonate (1:4,000). 

 Each fish was then wrapped in cheesecloth and 

 submerged in water so that only the top of the 

 skull was emergent. The section of skin covering 

 the pineal area was cut and folded back to reveal 

 the parietal bone. Using a diamond-edged wheel 

 saw (diameter = 2.2 cm) attached to a dental drill, 

 three sides of a rectangle (5x4 mm) were cut in 

 the parietal bone. This bone flap was then lifted 

 forward toward the animal's mouth to expose 

 parts of the cerebrum and midbrain. The pineal 

 could then be easily removed using a gentle suc- 

 tion applied through a Pasteur pipette. After 

 removal of the pineal, the parietal bone and the 

 epithelial flaps were individually sealed into place 

 with Eastman's 910 Adhesive. Sham operations 

 consisted of raising the parietal bone flap without 

 removing the pineal. Removal of the pineal can be 

 completed within 2 min in this species. 



The effects of pinealectomy on reproductive 

 function were assessed by gravimetric and his- 

 tological techniques. Fish were sacrificed by 

 severing the spinal cord. Body weight and gonadal 

 weight were recorded immediately after sacrifice. 

 Gravimetric data are expressed in terms of the 

 gonosomatic index (GSI) (gonadal weight/body 

 weight X 100) since gonadal size in this species 

 depends on body weight. After weighing, gonads 

 were fixed in Bouin's solution and embedded in 

 paraplast for histological examination. The data 

 obtained on the effects of pinealectomy on 

 reproductive function in Notemigonus are the 

 subject of another report (de Vlaming 1975). GSI 



-Reference to trade names does not imply endorsement by the 

 National Marine Fisheries Service, NOAA. 



767 



