of recent growth rates in golden shiner, 

 Notem igon us crysoleucas .adults. He reported that 

 RNA-DNA ratios were very sensitive to changes 

 in feeding levels. The RNA content of a wide vari- 

 ety of organisms have been related to growth rate 

 (Sutcliffe 1970). Sutcliffe ( 1965) was able to pre- 

 dict quite accurately the growth rates of laborato- 

 ry populations of brine shrimp, Artemia salina, 

 and mud sna\\, Nassarius obsoletus, larvae using a 

 growth-RNA relation determined on whole 

 amphipod Orchestia platesis. Daggand Littlepage 

 (1972), however, concluded that the general posi- 

 tive relationship between growth rate and RNA 

 content lacked sufficient specificity for determina- 

 tion of growth rate. A positive relationship is ex- 

 pected since growth in marine teleosts is accom- 

 panied by and is partially a function of protein 

 synthesis, and certain types of RNA are directly 

 involved in protein synthesis serving as both a 

 template and organizer. The DNA content of an 

 organism has been used as an indication of cell 

 number since the DNA content of somatic cells is 

 generally constant for a given species. Some eggs 

 and early larvae, however, have been shown to 

 contain large amounts of cytoplasmic DNA, 

 greatly exceeding the amount of nuclear DNA 

 (Neyfakh and Abramova 1974). This study was 

 undertaken to determine the relationships be- 

 tween changes in DNA, RNA, and protein content 

 and events in the development of winter flounder, 

 Pseudopleuronectes amencaniis, and to determine 

 if measurements of these classes of biochemicals 

 could be used to determine the nutritional condi- 

 tion of winter flounder larvae. 



Methods 



Pseudopleuronectes americanus adults were 

 caught by trawl net off Rhode Island and kept in a 

 1,900 1 aquarium. Eggs were obtained, fertilized, 

 and incubated according to methods previously 

 described (Smigielski 1975). Larvae were main- 

 tained at 8' C in 38 1 all black glass aquaria. 

 Commencing 4 days after hatching the larvae 

 were fed zooplankton collected in the Narragan- 

 sett Bay area in excess of 2 organisms/ml accord- 

 ing to the methods of Laurence ( 1975). On days 3 

 and 28 a portion of the larvae were transferred to 

 an identical aquarium containing seawater 

 filtered through a 0.45 ^m Millipore' filter. Wild 



^Reference to trade name.s does not imply endorsement by the 

 National Marine Fi.sheries Service, NOAA. 



winter flounder larvae were collected in Narrow 

 River, R. I., with a 505 ^m 0.5 m plankton net. 



About 40 eggs or larvae were pooled per sample 

 through day 11 after hatching; thereafter 10 lar- 

 vae were pooled per sample except on days 43. 50, 

 and 58 when only 5 larvae were used for the 

 largest size group. All samples through day 36 

 were run in triplicate; thereafter samples were 

 run in duplicate. Starting on day 28 the standard 

 length of each larva sampled was determined 

 using an ocular micrometer and 10 larvae were 

 taken on each sampling day for dry weight deter- 

 minations. 



Eggs and larvae were homogenized in 2 ml of 

 ice-cold distilled water immediately after sam- 

 pling. Protein was determined on duplicate 0.1 or 

 0.05 ml samples of homogenate using a modifica- 

 tion of the Lowry method (Hartree 1972). RNA 

 and DNA were extracted and partially purified 

 from 1.7 ml of homogenate using a modification of 

 the Schmidt-Thannhauser method (Munro and 

 Fleck 1966) adapted for the micro quantities pres- 

 ent in larval fish and eggs. RNA concentration 

 was estimated from the absorbancy at 260 nm of 

 the acid-soluble, alkali-hydrolyzed fraction. The 

 DNA content of larvae was determined from the 

 absorbency at 260 nm of the alkali-stable, acid- 

 hydrolyzed fraction. Because of the very small 

 quantities of DNA in winter flounder eggs their 

 DNA content was determined on the alkali-stable 

 fraction using a modification of the 3,5-diamino- 

 benzoic acid dihydrochloride florometric assay de- 

 scribed by Holm-Hansen et al. (1968) and Hine- 

 gardner (1971). At the beginning of this study 

 RNA was also determined using the orcinol 

 method (Sutcliffe 1965) and DNA was determined 

 using the indole method (Ceriotti 1952). These 

 values were in good agreement with the values 

 reported. 



Results 



DNA content per egg increased rapidly between 

 fertilization and hatching ( Figure 1 ). Upon hatch- 

 ing 10 days after fertilization, larvae contained 

 slightly more RNA and DNA than unhatched eggs 

 and retained 78'> of the protein. During the period 

 from hatching to the end of the yolk-sac stage (day 

 5), DNA and RNA content remained essentially 

 constant while a decrease in protein was observed. 

 Although plankton was added on day 4 to aquaria 

 containing fed larvae, visual observation of the 

 gut indicated that the majority of the larvae had 



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