Erythrophoromas in Colored Crucian Carp, Carassius auratus

Chromatophoromas, cutaneous pigment cell tumors that originate from skin dermochromatophores of fish, amphibians, and reptiles are rarely reported. The four basic pigment cell types found in poikilothermic vertebrates are melanomas (melanophoromas), iridophoromas, xanthophoroma, and erythrophoromas. In the present study, we diagnosed spontaneous lesions in the skin of a group of ornamental colored crucian carp, Carassius auratus, from an artificial ornamental fish pond located in Southeastern China. Necropsy, paraffin section, and hematoxylin-eosin staining methods were used to evaluate the neoplasm. Histological changes were observed and photographed using a Nikon microscope image system. The results showed oval nodular masses observed on the various parts of the body including flank, caudal peduncle, and tail. Histologically, neoplastic stromata were composed of bundles of compact parallel arrays cells. Dendric or spindle-shaped erythrophoroma cells were arranged as sheets or clusters with interlacing connective tissue. Congested capillaries and focal areas of hemorrhage were interspersed through the tissue. The tumor foci were infiltrated with neoplastic cells, inflammation cells, and necrotic tissue cells. Some olive to red intracytoplasmic pigment with polarized light could be seen on many parts of the erythrophoroma tissue. From the gross and histological pathology, we could conclude that the colored crucian carp suffered erythrophoromas. Further study is needed to confirm the etiology of this case

Eye fluke effects on Danish freshwater fish:Field and experimental investigations

Eye flukes in fish are common in freshwater lakes. Fish become infected by the penetration of cercariae released from freshwater snails, and high infection pressures may be associated with mortalities in a Danish lake. Examination of two other freshwater lakes, combined with laboratory study, supported the notion. We investigated 77 freshwater fish from two lakes and the infection level suggested the occurrence of a high cercarial infection pressure in the Danish lakes. Dominant genera were Tylodelphys and Diplostomum covering a range of species identified by PCR and sequencing of the 18S (partial)‐ITS1‐5.8S‐ITS2‐28S (partial) of the rDNA. Cercariae of the prevalent species Diplostomum pseudospathaceum were used to infect zebrafish Danio rerio for the elucidation of short‐term effects on the fish host. Zebrafish did not display abnormal behaviour when exposed to 200–400 cercariae, but a dosage of 600 and 1,000 cercariae/fish proved lethal. When fish were exposed to sublethal dosages, 19 out of 27 immune genes were significantly regulated and three genes encoding cytokine (IL 4/13B, IL‐6 and IL‐8) were upregulated at 3 hr post‐infection (hpi), whereas others were downregulated especially at a later time point. We suggest that direct massive cercarial penetration of fish surfaces may be detrimental and may represent a threat to fish populations

The Effect of Vitamin E and Metallothionein on the Antioxidant Capacities of Cadmium-Damaged Liver in Grass Carp Ctenopharyngodon idellus

Cadmium (Cd) causes a broad spectrum of toxicological effects to animals. Aquatic animals were more likely to accumulate Cd than terrestrial animals because of the living environment. Clearance of Cd in aquatic animals has become an important part of aquatic food safety. The present study was focused on the oxidative damage induced by Cd in the liver of grass carp Ctenopharyngodon idellus and the protective effect of vitamin E (VE) and metallothionein (MT). Grass carp were divided into four groups: the control group, Cd+phosphate-buffered saline (PBS) group, Cd+VE group, and Cd+MT group. All fish were injected with CdCl2 on the first day and then VE, MT, and PBS were given 4 days after injection, respectively. The liver function and antioxidant capacity of grass carp were evaluated. Cd administration resulted in damage of liver function and morphology in liver, which was expressed as the increased content of AST and ALT, rupture of organelles, and decrease of CAT, SOD, and GSH-Px activity. However, VE and MT treatments protected against Cd-induced damage of liver in grass carp by decreasing AST and ALT content, repairing organelles, and maintained the antioxidant system by elevating CAT, SOD, and GSH-Px activity and regulating related mRNA transcript expression. The results revealed that VE and MT might play an important role in the treatment of heavy metal poisoning through their antioxidative effects

Hepatoprotective Activity of Vitamin E and Metallothionein in Cadmium-Induced Liver Injury in Ctenopharyngodon idellus

As an environmental and industrial pollutant, cadmium (Cd) can cause a broad spectrum of toxicological effects. Multiple organs, especially the liver, are considerably affected by Cd in both humans and animals. We investigated the protective effects of metallothionein (MT) and vitamin E (VE) supplementation on Cd-induced apoptosis in the grass carp (Ctenopharyngodon idellus) liver. Grass carp were divided into four groups: the control group, Cd + phosphate-buffered saline (PBS) group, Cd + VE group, and Cd + MT group. All fish were injected with CdCl2 on the first day and then VE, MT, and PBS were given 4 days postinjection, respectively. The results showed that Cd administration resulted in liver poisoning in grass carp, which was expressed as an increase in Cd contents, malondialdehyde (MDA) concentration, percentage of hepatocyte apoptosis, and apoptosis-related gene mRNA transcript expression. However, VE and MT treatments protected against Cd-induced hepatotoxicity in grass carp by decreasing Cd contents, lipid peroxidation, and histological damage and reducing the percentage of hepatocyte apoptosis by regulating related mRNA transcript expression. These data demonstrate that oxidative stress and activation of the caspase signaling cascade play a critical role in Cd-induced hepatotoxicity. However, VE and MT alleviate Cd-induced hepatotoxicity through their antioxidative and antiapoptotic effects, and MT has a more powerful effect than VE