FISHERY BULLETIN: VOL. 74, NO. 3 



MATERIALS AND METHODS 



Spotted seatrout were obtained by hook and line 

 at seven localities from Corpus Christi, Tex., to 

 Indian River, Fla. Weakfish were caught by hook 

 and line in Peconic Bay, N.Y., and together with 

 silver seatrout in otter trawls in Wassaw Sound, 

 Ga. Sand seatrout were collected by hook and line 

 at Pensacola, Fla., and by shrimp trawl in the 

 vicinity of Carrabelle, Fla. 



Preparation of serum and eye lens samples and 

 electrophoretic methods are identical to those 

 recently described by Weinstein and Yerger (in 

 press). Samples were electrophoresed in 7% 

 acrylamide gel, using a modified Davis (1964) 

 technique. Diluting tissue preparations with 10% 

 glycerol avoided the tedius requirement of 

 producing three-layered gels, yet allowed highly 

 satisfactory resolution. 



Soluble muscle proteins were prepared by 

 homogenizing 1-g tissue samples with 2 volumes of 

 ice cold 0.05 M phosphate buffer (pH 7.4). 

 Homogenates were centrifuged in a SorvalF RC-2 

 refrigerated centrifuge at 20,000 rpm for 20 min. 

 Fifty microliters of supernate were combined with 

 an equal volume of 10% glycerol, and 50 jul of the 

 mixture layered on each gel. During electrophore- 

 sis the dye band was allowed to migrate to within 

 0.5 cm of the end of each gel. 



RESULTS 



4«^ 



 <Mi*SS« 



A 



B G 



D 



Figure 1. -Serum protein electropherograms derived from whole 

 sera of four seatrouts. (A) Cynoscion nothus, (B) C. arenarius, 

 (C) C. regaliif, (D) C. nebulosus. 



tion study on C. nebulosus (see Weinstein 1975). 



Because of the widespread variation observed in 

 the blood serum patterns, direct comparison 

 between the species investigated was difficult. In 

 order to "sum" the intraspecific variation observed 

 and subsequently to use the composites for direct 

 comparison, the taxonomic distance (dji,) measure 

 of Sokal (1961) was utilized. In this formula 



2 



di2 = 



1 



n 



E i^n-^i2f 



i=i 



Serum Proteins 



Although serum protein patterns varied intra- 

 specifically both in the frequency of occurrence of 

 particular bands, and occasionally in their compo- 

 sition (intensity), species specificity was evident. 

 Differences among patterns were not so pro- 

 nounced as to prevent assigning a given pattern to 

 the proper taxon. Typical results obtained from 

 the four seatrouts are shown in Figure 1, and are 

 diagrammed in Figure 2. All bands observed in the 

 total number of electrophoresed samples are in- 

 dicated. Their position on the diagrams is also an 

 accurate representation of the relative distances 

 (on the gels) that each band migrated. 



We follow the standard method of defining 

 protein zones (a, (i, y, albumin, prealbumin). The 

 various designations were derived from a popula- 



+ 



a 



alb 



p alb 



B 



^Reference to trade names does not imply endorsement by the 

 National Marine Fisheries Service, NOAA. 



Figure 2.-Diagrammatic representation of protein bands 

 occurring in serum electropherograms of four seatrouts. Protein 

 zones are as follows: y = immunoglobin zone; /? = /3-globulin 

 zone; « = a-globulin zone; alb = albumins; p-alb = prealbumins. 

 * indicates band present in 100% of samples. (A) Cynoscion 

 iiotkus, (B) C. arenarius, (C) C. regalis, (D) C. nebulosus. 



600 



