Atrial Natriuretic Peptides in Antarctic Fi sh
221
Ir-Like ANP Immunoreactivity in Antarctic Teleost Larvae
The presence of ANP was studied in larvae of Pleuragramma antarcticum
(Nototheniidae) about 2 cm long. Immunoreactivity for a-rANP was
present in the thin wall of the atrium and in the trabeculae of the ventricle
(Fig. 9), in the conus, and in the bulbus arteriosus, where the immunostaining was particularly concentrated in the inner layer (Fig. 10). Immunoreactivity was also present in the walls of the ventral aorta and was
localized in cells of the branchial epithelium (Fig. 11) and of the
archinephric duct (Fig. 12). ANP is present during fetal life in mammals
and the presence of immunoreactive ANP granules was found in both atrial
and ventricular cardiocytes, contrasting with its restriction to the atrium of
the adult heart [30]. In the frog Rana dalmatina, ANP-like immunoreactivity was observed in both the ventricle and the two atria from larval
stages 22123. At stages 25-27 ANP was confined to the atria while the
ventricle was completely devoid of immunoreactivity [31]. The a-rANP
cardiac localization seems to change during development in mammals and
frogs, immunoreactivity concentrates in the atria as maturation progresses
and is absent from ventricular cardiocytes. The presence of a-rANP in the
ventricles of adult Antarctic te1eosts is controversial; there is ventricular
localization in N neglecta [32] and Champsocephalus [24] but not in
Chionodraco and Trematomus [22] . It seems that during ontogeny storage
and release of ANP changes in some teleosts as in frogs and mammals.
Figs. 9-12 Larvae of Pleuragramma antarcticum. Immunofluorescence for a-rANP in
atrium and ventricle (Fig. 9), in bulbus arteriosus (Fig. 10), in the gill lamellae (Fig. 11) and
in archinephric tubules (Fig. 12). x 400
221
Ir-Like ANP Immunoreactivity in Antarctic Teleost Larvae
The presence of ANP was studied in larvae of Pleuragramma antarcticum
(Nototheniidae) about 2 cm long. Immunoreactivity for a-rANP was
present in the thin wall of the atrium and in the trabeculae of the ventricle
(Fig. 9), in the conus, and in the bulbus arteriosus, where the immunostaining was particularly concentrated in the inner layer (Fig. 10). Immunoreactivity was also present in the walls of the ventral aorta and was
localized in cells of the branchial epithelium (Fig. 11) and of the
archinephric duct (Fig. 12). ANP is present during fetal life in mammals
and the presence of immunoreactive ANP granules was found in both atrial
and ventricular cardiocytes, contrasting with its restriction to the atrium of
the adult heart [30]. In the frog Rana dalmatina, ANP-like immunoreactivity was observed in both the ventricle and the two atria from larval
stages 22123. At stages 25-27 ANP was confined to the atria while the
ventricle was completely devoid of immunoreactivity [31]. The a-rANP
cardiac localization seems to change during development in mammals and
frogs, immunoreactivity concentrates in the atria as maturation progresses
and is absent from ventricular cardiocytes. The presence of a-rANP in the
ventricles of adult Antarctic te1eosts is controversial; there is ventricular
localization in N neglecta [32] and Champsocephalus [24] but not in
Chionodraco and Trematomus [22] . It seems that during ontogeny storage
and release of ANP changes in some teleosts as in frogs and mammals.
Figs. 9-12 Larvae of Pleuragramma antarcticum. Immunofluorescence for a-rANP in
atrium and ventricle (Fig. 9), in bulbus arteriosus (Fig. 10), in the gill lamellae (Fig. 11) and
in archinephric tubules (Fig. 12). x 400