Comparative study of erythrocytes of polyploid hybrids from various fish subfamily crossings

Abstract

We have undertaken comparative studies of the number and phenotypes of erythrocytes in the peripheral blood of red crucian carp (RCC), blunt snout bream (BSB), and their hybrids, including triploids, tetraploids, and pentaploids. The results indicate that the mean nuclear volume of erythrocytes in peripheral blood increases regularly with increasing ploidy. Furthermore, many more mature erythrocytes have a dumbbell nucleus in the peripheral blood of polyploid hybrids compared with their diploid parents. With the increase in ploidy level, the percentage of such erythrocytes increases. The polyploid hybrids also have a large number of erythrocytes with abnormal shapes. For example, round and tear-shaped erythrocytes have been observed in the peripheral blood of polyploid hybrids. Since the erythrocytes in polyploid hybrids with their larger volume and lower specific surface area are unfavorable for the conveyance of oxygen, morphological variations of erythrocytes might improve defective blood circulation.

A novel field technique to assess ploidy in introduced Grass Carp (Ctenopharyngodon idella, Cyprinidae)

“…In triploid Grass Carp, a much larger proportion of erythrocyte nuclei were abnormally shaped than in diploid Grass Carp. More than half of the nuclei observed in triploids were of the dumbbell shape described by Lu et al (2009). Very rarely a teardrop shaped nucleus was observed.…”

“…Nuclei in the shape of a dumbbell were measured as the sum volume of two adjoining ellipses, and teardrop shaped nuclei were measured as a single ellipse; each of these measures erring as an underestimate of the actual nuclear volumes ( Fig. 1; Lu et al 2009). The mean value for each variable was calculated for each fish, and the means were then compared between diploid and triploid for each variable.…”

“…One promising technique to determine ploidy is the use of nuclear shape. Although novel in terms of application, this technique has been used in comparative biological studies of other species including Goldfish (Carassius auratus) 9 Wuchang Bream (Megalobrama amblycephala) hybrids by Lu et al (2009), who described ratios of abnormally shaped (dumbbell, acanthoid, ligule, moniliform, and tear-drop shaped) erythrocyte nuclei increasing with increasing sets of chromosomes. 3n polyploids were found to have normal (ellipse) shaped erythrocytes as well as dumbbell and acanthoid shaped nuclei, whereas in 4n polyploids normal ellipse, dumbbell, tear-drop, moniliform, and U-shaped nuclei were observed.…”

“…Nonnative carps are known to alter water quality, predate on and compete with native species, and in some cases hybridize with native species (Bain 1993;Richardson et al 1995;Schofield et al 2005). Two filter-feeding species, Bighead Carp (Hypophthalmichthys nobilis) and Silver Carp (H. molitrix), were imported to North America (Arkansas) in the early 1970s to improve water clarity in commercial ponds, now are established in the Mississippi River, and are thought to outcompete native species for plankton as a food source (Kolar et al 2005;Sampson et al 2009). Similarly, Grass Carp (Ctenopharyngodon idella) regularly are released intentionally to control aquatic vegetation and have become established in many non-native environments (Guillory and Gassaway 1978;Hargrave and Gido 2004).…”

Research advances in animal distant hybridization

“…As ploidy levels increase, nuclear and cellular diameters of erythrocytes and other blood cells increase, as well as the percentage of unusual erythrocytes [96,97]. In 4nAT, erythrocyte nuclei appear particularly dumbbell-shaped [98].…”