Preliminary Study On Iron Accumulation And Serum Transferrin Of Several Cetacean Species

In order to understand the characteristics of iron (Fe) bioaccumulation and serumtransferrin of cetacean animals, the preliminary studies have been carried out on tissularpattern of Fe concentrations with two Indo-Pacific humpback dolphins (Sousa chinensis)(animal code: XM20040429 and XM20040430), on serum iron total, iron-binding capacityand iron saturation with three bottlenose dolphins (Tursiops truncatus) (animal code: LE,LU, BE) and a rough-toothed dolphin (Steno bredanensis), on the polyacrylamide gelelectrophoresis (PAGE) performation of serum transferrin with the same bottlenosedolphins and rough-toothed dolphin above, as well as three Yangtze finless porpoise(Neophocaena phocaenoides asiaeorientalis), and on the molecular weight and isoelectricpoint of serum transferrin with the bottlenose dolphin LE and LU.Iron concentration was analyzed with samples of the liver, pancreas, stomach, kidney,intestine, lung, muscle, heart, skin, and brain from the Indo-Pacific humpback dolphinXM20040429 and XM20040430. Both individuals showed a similar tissular pattern, i.e.,high Fe concentrations were in the blood, liver, lung, and kidney (range: 427.4-2968.2μg/g). Moderate concentrations were in the muscle, pancreas andheart (range: 179.6-393.4μg/g). Lower concentrations were in the stomach, intestine, brain and skin (range:51.8-199.8μg/g). The iron concentrations in the liver, pancreas and kidney of adultXM20040430 (estimated age 4-5 year-old) were 2.89, 1.95 and 1.39 times higher thanthose in young XM20040429 (estimated age 2-3 year-old), respectively.The ranges of serum iron concentration, total iron-binding capacity, and iron saturationof bottlenose dolphin BE, LU, LE and rough-toothed dolphin were 23.6-45.0μmol/L,52.0-75.0μmol/L, and 38.7-74.6ï¼…, respectively. Serum iron and iron saturation of fourcetacean individuals were generally higher than those of fishes comparatively studied,indicating that the activity of cetacean transferrin and utilization efficiency of serum ironare generally higher. Cetaceans seem to enhance the respiratory effectivity and divingability by elevation of serum iron and iron saturation levels to deal with the deficiency ofhematologic oxygen during the diving period, and adapt to aquatic habitats completely. Results. of PAGE indicated that serum transferrins of bottlenose dolphin,rough-toothed dolphin and finless dolphin wereβ-globulin. Serum transferrin of thesecetaceans possessed 4-7 bands, generally more than those of the fishes (yellow catfishPelteobagrus fulvidraco, sharptooth catfish Clarias leather, turbot Scophthalmus maximus,margined bullhead Liobagrus marginatus, Chinese Sturgeon Acipenser sinensis) andterrestrial mammals (human Homo sapiens, terrestrial mice Mus musculus, yellow cattleBos taurus domesticus, buffalo Bubalus bubalis, goat Capra hircus, pig Sus scrofadomestica, dog Canisfamiliaris) studied for a comparative purpose, and serum transferrinzones of former distributed wider. Serum transferrin of three bottlenose dolphins and threefinless dolphins distributed to all serum transferrinâ… -â…£(TFâ… -TFâ…£) zones. In contrast,serum transferrin of the rough-toothed dolphin possessed no band in Tfâ…£zone.Furthermore, serum transferrin polymorphism was observed in bottlenose dolphins andfinless dolphins studied. Although the distribution characteristics on former five serumtransferrin binds were similar between the bottlenose dolphins and Yangtze finless dolphin,the migration rate of each serum transferrin band in finless dolphin seemed to be slower,suggesting a difference in electric charge and molecular weight. The plausible explanationmight be that bottlenose dolphin lives in the ocean, while Yangtze finless dolphin lives inthe fresh water. Individual variation among the bottlenose dolphins was observed in TFâ… and TFâ…¡zones, i.e., Serum transferrin of bottlenose dolphin LU possessed all the serumtransferrin bands showed by the dolphin LE and BE. Serum transferrin genotypes ofbottlenose dolphin BE and LE were temporarily named as A and B in the present study, andthus, the phenotypes of bottlenose dolphin LE, BE and LU were AA, BB and AB,respectively. Individual variation of finless dolphins was also observed in IV zone. Inaddition, serum transferrin bands of the rough-toothes dolphin distributed only amongTfâ… -Tfâ…¢zones.Results of both molecular weight and isoelectrc point of bottlenose dolphin LE andLU showed that serum transferrin of the dolphins were composed by two differentcomponents. Molecular weights of serum transferrin were 72,700 Da/69,900 Da and 73,100Da/69,700 Da in bottlenose dolphin LE and LU, respectively. Likewise, isoelectrc points ofserum transferrin were 6.2/6.3, and 6.3/6.4 in bottlenose dolphin LE and LU, respectively.Similar phenomena on molecular weight of serum transferrin were also documented onmany artiodactyl animals in previous literatures. Noteworthily, serum transferrin ofbottlenose dolphin possessed lower molecular weight and higher isoelectrc point in comparison of those of terrestrial mammalsin in previous literatures. Such a specificationmay rnake serum transferrin easier to bind Fe³⁺. According to the results of PAGE,molecular weight and isoelectric point, we conjectured that serum transferrin of bottlenosedolphin seem to be coded by 6 or even more alleles. The difference of molecular weight fortwo components of serum transferrin and isoelectric point were 3,000Da and 0.1,respectively.