Cytochemical characterization of peripheral blood cell populations of two Cyprinidae, Carassius auratus and Ctenopharyngodon idellus

Morphological and cytochemical characterization of the peripheral blood cells of farmed streaked prochilod Prochilodus lineatus (Characiformes, Prochilodontidae)

ABSTRACT Morphological and cytochemical studies of peripheral blood cells of fish have improved the understanding of their functions and cell types. The present study performed the Morphological and cytochemical analysis of the peripheral blood of Prochilodus lineatus, Characiform native to South America, which has been gaining space in local aquaculture and as a species introduced in Asia. Our analysis provided information on the morphological and cytochemical characteristics of the leukocytes, for the formulation of hypothesis about their role in the immune system of the species. It was found that Prochilodus lineatus has morphological and cytochemical features in common with other fish species, mainly of the Characiformes order. However, we detected the presence of heterophils and PAS positive granulocytes simultaneously with neutrophils. We also found that heterophils and PAS positive granulocytes are very similar, both morphologically and cytochemically.

Comparative study of peripheral blood cells in two marine fishes (Synechogobius hasta and Sebastes schlegelii): Morphological and cytochemical characterization

The morphology, cell size and relative number of peripheral blood cells in two teleosts, Synechogobius hasta and Sebastes schlegelii, were compared using different staining methods. The results showed significant differences in cell size. The percentage of monocytes in S. hasta was greater than that in S. schlegelii (P < 0.01); however, the opposite results were obtained in the percentage of lymphocytes and thrombocytes. The two fishes shared common cytochemical-staining results, which showed that both erythrocytes were negative for all cytochemical staining; monocytes were strongly positive for PAS and positive for SBB and NAE; lymphocytes were negative for SBB, POX and NAE; neutrophils were positive for SBB and NAE; and thrombocytes were negative for SBB, ALP, POX and NAE. However, species specificity existed in the cytochemical properties. For S. hasta, monocytes were strongly positive for ALP and ACP; lymphocytes were strongly positive for ALP and weakly positive for ACP; neutrophils were strongly positive for ACP and POX; and thrombocytes were weakly positive for PAS and positive for ACP. Unlike S. hasta, monocytes were strongly positive for ACP and positive for ALP in S. schlegelii; lymphocytes were positive for ALP and partially positive for PAS; neutrophils were positive for ACP and POX; and thrombocytes were negative for PAS and ACP. The POX activity of monocytes in S. hasta was greater than that in S. schlegelii (P < 0.05), while the POX activity of neutrophils and the NAE activity of monocytes in S. hasta were significantly greater than those in S. schlegelii (P < 0.01). The results of this study can be used as a reference for the construction of haematological parameters in S. hasta and S. schlegelii for the assessment of fish health and can provide a research basis for fish diseases and immunity.

Hematological and cytochemical characteristics of peripheral blood cells in the argus snakehead (Ophiocephalus argus Cantor)

BACKGROUND

The argus snakehead (Ophiocephalus argus Cantor) is a highly nutritious, freshwater, cultured bony fish with a high economic value. The health of the fish is closely related to its blood cells, which are critical for oxygen transport, natural defense, and immunity. We investigated the morphometry, microstructure, and cytochemical characteristics of the peripheral blood cells of O. argus. Our results may provide the basic reference values needed to monitor the health of this fish for large-scale cultivation.

METHODS

The number of blood cells in O. argus were counted on a hemocytometer and their size was measured using a micrometer under light microscope. The morphology and classification of the blood cells were studied using Wright's staining and the cytochemical characteristics were studied using seven chemical stains including peroxidase (POX), Sudan black B (SBB), periodic acid-Schiff (PAS), acid phosphatase (ACP), alkaline phosphatase (ALP), chloroacetic acid AS-D naphthol esterase (AS-D), and α-naphthol acetate esterase (α-NAE).

RESULTS

The peripheral blood cells in O. argus can be classified as erythrocytes, leukocytes, and thrombocytes; of which, females had 2.9597 million/mm3, 88,400/mm3, and 43,600/mm3, respectively, and males had 3.0105 million/mm3, 105,500/mm3, and 34,000/mm3, respectively. Leukocytes consisted of neutrophils, monocytes, large lymphocytes, and small lymphocytes. Eosinophils and basophils were not found. Monocytes were the most numerous leukocytes identified, followed by neutrophils and small lymphocytes, while large lymphocytes were the least frequently identified. Cytochemical staining showed that erythrocytes were only positive for PAS staining. Neutrophils were strongly positive for POX, SBB, and ACP, and positive for all the other cytochemical stains. Monocytes were positive for PAS and α-NAE and were weakly positive for ACP and AS-D staining. Large lymphocytes were positive for PAS and were weakly positive for ALP, AS-D, and α-NAE staining. Small lymphocytes were positive for PAS and weakly positive for AS-D and α-NAE staining. Thrombocytes were positive for PAS and were weakly positive for ACP and AS-D, but negative for the remaining cytochemical stains. The morphology of peripheral blood cells in O. argus was generally similar to that of other fish species, while the cytochemical staining patterns showed clear species specificity.

Comparative Morphology and Morphometry of Blood Cells in Zebrafish (Danio rerio), Common Carp (Cyprinus carpio carpio), and Tilapia (Oreochromis niloticus)

Several diagnostic tools are available for veterinarians and fish health professionals to evaluate fish health and their abnormalities. However, reference data regarding the character and size of fish blood cells are limited. The purpose of this study was to analyze the morphology and morphometry of normal blood cells in zebrafish (Danio rerio), common carp (Cyprinus carpio carpio), and tilapia (Oreochromis niloticus). To get a representative sample, we took blood from ten 6-mo old healthy fish from each species. Fish were purchased from an ornamental fish market and the local government fish breeding center in Yogyakarta, Indonesia. A total of 100 erythrocytes and a maximum of 30 leukocytes (neutrophils, eosinophils, basophils, lymphocytes and monocytes) were randomly sampled and analyzed qualitatively and quantitatively, including morphometric analysis of both the long axis (LA) and short axis (SA) of these cells. All data obtained were analyzed using ANOVA statistical tests to compare the blood cells in each species with SPSS software. The findings revealed distinct differences in both morphology and morphometry of the blood cells among the species. Basic knowledge obtained from this research will aid in the development of biomarkers and other ancillary diagnostic tools for further hematology research, conservation, and clinical diagnosis in these 3 fish species.

Molecular characterization and functional analysis of interferon regulatory factor 9 (irf9) in common carp Cyprinus carpio: a pivotal molecule in the Ifn response against pathogens

In the present study, interferon (IFN) regulatory factor (IRF) 9 gene (irf9) was identified and characterized in common carp Cyprinus carpio. The predicted protein sequence of Irf9 contains a DNA binding domain (DBD) that possess five tryptophans, an IRF association domain (IAD) and two nuclear localisation signals (NLS). Alignment of Irf9 of C. carpio with the corresponding Irf9 proteins of other species showed that the DBD is more highly conserved than the IAD. The putative Irf9 protein sequence of C. carpio shares higher identities with teleosts (53.8-82.3%) and lower identities with mammals (30.2-31.0%). Phylogenetic studies of the putative amino-acid sequence of IRF9 based on the neighbour-joining method showed that Irf9 of C. carpio has the closest relationship with the grass carp Ctenopharyngodon idella. Tissue distribution analysis showed that irf9 transcripts were detectable in all examined tissues with the highest expression in the skin and the lowest expression in the head kidney. Poly I:C and Aeromonas hydrophila stimulation up-regulated irf9 expression in the spleen, head kidney, foregut and hindgut at different time intervals. In addition, irf9 was induced by Poly I:C and lipopolysaccharides (LPS) in vitro. These results indicate that Irf9 participates in antiviral and antibacterial immunity. Transfection of irf9 up-regulated the expression of cytokines, including type I IFN, protein kinase R (PKR), interferon-stimulated gene (ISG)15 and tumour necrosis factor (TNF)α in epithelioma papulosum cyprini cells (EPC) upon poly I:C and LPS stimulation. A dual-luciferase reporter assay revealed that Irf9 has no effect on NF-κB activation. The present study on Irf9 provides new insights into the IFN system of C. carpio and a valuable experimental platform for future studies on the immune system of fish.