TY - JOUR
T1 - Sexual maturation and reproductive zinc physiology in the female squirrelfish
AU - Thompson, E D
AU - Mayer, G D
AU - Walsh, P J
AU - Hogstrand, C
PY - 2002/11
Y1 - 2002/11
N2 - Female squirrelfish (Holocentridae) accumulate higher concentrations of hepatic zinc than any other known organism. In the liver cells, up to 70% of zinc is bound to metallothionein (NIT), which is expressed at extremely high levels. These attributes are related to reproduction in ways that have not been fully characterized. In the present study, we have demonstrated that female-specific zinc and NIT accumulation and distribution are strongly correlated to the onset of sexual maturity in Holocentrus adsenscionis. Sexual maturation not only resulted in increased concentrations of zinc in the liver and plasma, but also increased levels of hepatic NIT mRNA. Furthermore, mature female squirrelfish exhibited greater proportions of NIT protein in the nuclear liver cell fractions. To characterize the physiology further, we have examined the influence of the female sex hormone 17 beta-estradiol (E-2). E-2 was not sufficient to elicit an increase in hepatic zinc concentrations or NIT mRNA levels. E-2 administration did, however, result in increased levels of NIT in the nuclear fraction as well as overall hepatic NIT protein. E-2 also increased concentrations of zinc in the plasma. The changes in zinc concentration in the bloodstream followed the same time course as vitellogenin (VTG) transport from the liver. However, the high ratio of molar concentrations of zinc to VTG in the bloodstream suggest that VTG may not be the primary vehicle for hepato-ovarian zinc transport in squirrelfish.
AB - Female squirrelfish (Holocentridae) accumulate higher concentrations of hepatic zinc than any other known organism. In the liver cells, up to 70% of zinc is bound to metallothionein (NIT), which is expressed at extremely high levels. These attributes are related to reproduction in ways that have not been fully characterized. In the present study, we have demonstrated that female-specific zinc and NIT accumulation and distribution are strongly correlated to the onset of sexual maturity in Holocentrus adsenscionis. Sexual maturation not only resulted in increased concentrations of zinc in the liver and plasma, but also increased levels of hepatic NIT mRNA. Furthermore, mature female squirrelfish exhibited greater proportions of NIT protein in the nuclear liver cell fractions. To characterize the physiology further, we have examined the influence of the female sex hormone 17 beta-estradiol (E-2). E-2 was not sufficient to elicit an increase in hepatic zinc concentrations or NIT mRNA levels. E-2 administration did, however, result in increased levels of NIT in the nuclear fraction as well as overall hepatic NIT protein. E-2 also increased concentrations of zinc in the plasma. The changes in zinc concentration in the bloodstream followed the same time course as vitellogenin (VTG) transport from the liver. However, the high ratio of molar concentrations of zinc to VTG in the bloodstream suggest that VTG may not be the primary vehicle for hepato-ovarian zinc transport in squirrelfish.
UR - http://www.scopus.com/inward/record.url?scp=0036851563&partnerID=8YFLogxK
M3 - Article
VL - 205
SP - 3367
EP - 3376
JO - Journal of Experimental Biology
JF - Journal of Experimental Biology
IS - 21
ER -