Karyological, biochemical, and physiological aspects of Callophysus macropterus (Siluriformes, Pimelodidae) from the Solimões and Negro Rivers (Central Amazon)

Abstract Karyological characteristics, i.e., diploid number, chromosome mor-phology and nucleolus organizer regions (NORs), biochemical char-acteristics, i.e., electrophoretic analysis of blood hemoglobin and thetissue enzymes lactate dehydrogenase (LDH), malate dehydrogenase(MDH), alcohol dehydrogenase (ADH), and phosphoglucose isomerase(PGI), and physiological characteristics, i.e., relative concentration ofhemoglobin and intraerythrocytic concentrations of organic phos-phates were analyzed for the species Callophysus macropterus col-lected from Marchantaria Island (white water system – SolimoesRiver) and Anavilhanas Archipelago (black water system – NegroRiver). Karyological and biochemical data did not reveal significantdifferences between specimens collected at the two sites. However,the relative distribution of hemoglobin bands I and III (I = 16.33 ± 1.05and III = 37.20 ± 1.32 for Marchantaria specimens and I = 6.33 ± 1.32and III = 48.05 ± 1.55 for Anavilhanas specimens) and levels ofintraerythrocytic GTP (1.32 ± 0.16 and 2.76 ± 0.18 for Marchantariaand Anavilhanas specimens, respectively), but not ATP or total phos-phate, were significantly different, indicating a physiological adapta-tion to the environmental conditions of these habitats. It is suggestedthat C. macropterus specimens from the two collecting sites belong toa single population, and that they adjusted some physiological charac-teristics to adapt to local environmental conditions.