244 



Fishery Bulletin 89(2). 1991 



In the present study, the transient recovery of otolith 

 growth occurred on the first day following refeeding. 

 Although the definite reason for this remains unex- 

 plained, an accelerated recovery process after growth 

 suppression is well known as "repletion" in mammalian 

 skeletal tissue formation (Linkhart et al. 1988). Mech- 

 anisms for repletion would differ depending on tissues. 

 Since the otolith is an acellular product secreted by 

 otolith-forming cells (Saitoh and Yamada 1989), a possi- 

 ble explanation for otolith repletion is as follows: Star- 

 vation may interrupt the releasing activity partly due 

 to the reduced processing of the secretory product. This 

 would inversely result in some accumulation of otolith 

 precursor materials in the cells (Anderson and Capen 

 1976). Refeeding stimulates release of the accumulated 

 precursors through some factors (e.g., calcium-calmo- 

 dulin interaction; Mugiya 1986) regulating the secre- 

 tory activity. A steady-state recovery in synthesis and 

 processing of the secretory product is probably a time- 

 consuming process, running parallel to the recovery of 

 RNA-DNA ratios in muscle. These possibilities await 

 further examination. 



In the present study, we have demonstrated corre- 

 sponding variations in otolith calcification and RNA- 

 DNA ratios in muscle, but a causal relationship be- 

 tween specific growth rate and otolith calcification 

 remains to be studied. 



Acknowledgments 



The present study was financially supported in part by 

 Grant No. 01560197 from the Ministry of Education 

 of Japan. 



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