Isolation and identification of Flavobacterium columnaris like organisms from grass carp (Ctenopharyngodon idella) and assessment of its histopathological effects in Khouzestan Province, Southern Iran

Following a mortality of up to 40% of cultured Grass Carp (Ctenopharyngodon idella) in fish farms of Khouzestan province when water temperature was up to 20°C, samples were taken and examined for etiological clues. We observed that fish gills were coated with a gray-white mucus layer, fin was eroded and wounds were present in peduncle of the affected samples. Bacteriological studies on the samples of gills and eroded and wounded peduncle skin using Cytophaga selective medium, resulted in isolation of filamentous gram negative bacteria chemically similar to Flavobacterium columnaris. Histological observations showed the affected fish carrying symptoms including congestion, hemorrhagia, edema in base membrane, hyperplasia of chondrocyte and secondary lamellae cells, fusion of lamellae, necrosis and peeling of secondary lamellae and also presence of filamentous bacteria in gill tissue sections. Necrosis of skin layers and expansion of ulcer to underlying muscles, degeneration of muscle cells and necrosis of muscle bundles were seen in peduncle muscles. We did not find this bacterium in internal organs. We conclude that the isolation of the bacterium and observation of histo-pathological changes suggest the organisms may be considered as a primary or secondary factor in occurrence of the disease

Study of pathological effects of an organic germicide bathing on rainbow trout

The aim of this study was evaluation an organic germicide (Aquagerm) histological affects on Rainbow trout (Oncorhynchus mykiss) vital tissues. This new disinfectant is an aquatic antiseptic and mixed-oxidant disinfectant which is produced for the first time in Iran. This new product mechanism is based on oxidant properties of pro-sulphate which attack crucial structures of pathogens. In this study, forty healthy fish were selected and divided into two groups as control and treatment. The treatment group was treated with 1/2000 concentration of organic germicide for 45 min (according to the manufacturing protocols). At 4, 8, 12, 24, 48 and 96 h after bath challenge, 5 specimens were collected from treatment and one from control group. Gill, brain, kidney, and liver of all fish were sampled. Some histological damages such as edema and detachment of basic layer in secondary gill filaments were observed in gill microscopy results. The most important histological changes observed in the brain were congestion of some blood vessels. Furthermore, some evidences of increased melano-macrophage, glomerular shrinkage, and dilatation in Bowman capsules were recorded whereas no any damages were observed in liver. All histological changes removed after 48-96 h. It could be concluded that, all pathological observations in this study were just a natural response of fish body after exposing to the new disinfectant, and they were not recorded any damages like those which happen against hazardous chemicals. It seems that there is no risk associated with the consumption of this disinfectant for the fish tissues

Genetic characterization of Lactococcus garvieae isolated from farmed rainbow trout by random amplified polymorphic DNA-PCR in Iran

ΔΕΝ ΔΙΑΤΙΘΕΤΑΙ ΠΕΡΙΛΗΨΗLactococcosis is one of the main bacterial infections of fish around the world. Lactococcus garvieae has been a major cause of rainbow trout losses in freshwater farming. This study aimed to genotype and determine the variability of L. garvieae isolated from infected farmed rainbow trout in Iran by the RAPD-PCR method. Bacterial samples were collected from 12 farms located in the western part of Iran and suspect ted to carry Lactococcus infection. Two hundred bacterial cultures containing cocci shaped bacteria were cultured in Trypticase soy agar (TSA) and blood agar mediums. All bacterial cultures were tested by conventional microbiological and biochemical tests, and PCR assay to identify L. garvieae by 16S rDNA genes. The RAPD-PCR method was used to determine the genetic patternof all isolates. The sample strain pattern of the isolates was analyzed in the NTSYS program. According to a similarity coefficient index of 70%, all L. garvieae isolates were separated into two groups with four RAPD profile types. The highest and the lowest genetic pairwise similarity among the isolates were 98% and 54%, respectively. The results of the present study revealed that RAPD-PCR is an applicable method to describe the genetic diversity of different strains of L .garvieae among farmed fish

Genetic characterization of Lactococcus garvieae isolated from farmed rainbow trout by random amplified polymorphic DNA-PCR in Iran

Lactococcosis is one of the main bacterial infections of fish around the world. Lactococcus garvieae has been a major cause of rainbow trout losses in freshwater farming. This study aimed to genotype and determine the variability of L. garvieae isolated from infected farmed rainbow trout in Iran by the RAPD-PCR method. Bacterial samples were collected from 12 farms located in the western part of Iran and suspected to carry Lactococcus infection. Two hundred bacterial cultures containing cocci shaped bacteria were cultured in Trypticase soy agar (TSA) and blood agar mediums. All bacterial cultures were tested by conventional microbiological and biochemical tests, and PCR assay to identify L. garvieae by 16S rDNA genes. The RAPD-PCR method was used to determine the genetic pattern of all isolates. The sample strain pattern of the isolates was analyzed in the NTSYS program. According to a similarity coefficient index of 70%, all L. garvieae isolates were separated into two groups with four RAPD profile types. The highest and the lowest genetic pairwise similarity among the isolates were 98% and 54%, respectively. The results of the present study revealed that RAPD-PCR is an applicable method to describe the genetic diversity of different strains of L. garvieae among farmed fish

Study of anaesthetic effects of clove oil (Eugenia caryophyllata) in common carp (Cyprinus carpio) under various pH and temperature condition

The anaesthetic effects of clove oil in juvenile common carp (8-12 g) were investigated under various water quality conditions, consisting of different pH and temperature. The time to loss the equilibrium, induction of anesthesia, equilibrium recovery and response recovery were measured. The results showed that clove oil induced the desirable anaesthetic condition in less than 3 minutes in all experiments. However the time of equilibrium recovery and response recovery were longer than 5 minutes in many cases. When using clove oil at concentration of 100ppm, the most suitable anaesthetic effects and recovery times were observed at water temperature of 25֯ C and pH=7 and 8,as well as at 30֯ C with pH=9. No morbidity or mortality occurred during induction of anesthesia by clove oil and recovery of fishes

Experimental pathology of Streptococcus sp. in Rainbow Trout, Oncorhynchus mykiss

Experimental pathology of Streptococcus sp. was studied in Rainbow Trout weighing 18-20 grams each using bath (1.5t10 ^(3) 1.5t10 ^ (4), 1.5t10 ^ (5), 1.5t10 ^ (6) 1.5t10 ^ (7).5t10 ^ (8) cell/ml for one hour) and intraperitoneal (1.5t10 ^ (3) 1.5t10 ^ (4) 1.5t10 ^ (5), 1.5t10 ^ (6), 1.5t10 ^ (7) 1.5t10 ^ (8) cell/fish) challenges provided at 18C. Control groups were included by intraperitoneal injection of fish with sterile phosphate buffered saline (0.5 ml/fish) after anesthetizing fish with clove oil (100 mg/l). Six groups consisting of 12 fish each were used. No morbidity or mortality occurred in bath-immersion groups, while mortality occurred in intraperitoneally injected fish 24 hours post-challenge and reached LD _(50) at 1.5tl0 ^ (8) cell/fish 72 hours post-challenge. The affected fish showed anorexia, darkening of body, exophthalmia, and prolapsed anal abdominal distension. In histopathological sections, there were hyperemia and sinusoidal congestion plus necrosis and degeneration of liver hepatocytes. Also, hyperemia in heart tissue, an increase in interstitial tissue plus necrosis of kidney tubular, edema of Bowman capsules together with an increase in melano macrophage centers of kidney tissues were seen. In addition, congestion of spleen ellipsoids and necrosis of spleen cells were observable. Detachment of basal membrane of secondary lamella with infiltration of inflammatory cells, congestion and edema of menangial layers, hemorrhage in orbital adipose tissue and destruction of eye cornea were also observable

The effect of created hemolymph apoptosis on WSSV Gamma-vaccinated shrimp, Litopenaeus vannamei in WSSV disease control

White spot syndrome virus (WSSV) is the causative agent responsible for huge-shrimp viral epidemics in shrimp farms throughout the world. Our study was aimed to determine the effect of WSSV Gamma-vaccinated Litopenaeus vannamei on the occurrence of apoptosis. One thousand and twenty PL15 were randomly distributed among 2 treatments and two control groups. Gamma-Vaccinated shrimp and non-Gamma-vaccinated ones were our treated and untreated groups. Based on our results significant differences (p<0.05) were observed in survival percent between vaccinated-exposed group (82.33±2.51) and non-vaccinated exposed group (26.00±10.00). It is concluded that apoptosis can be a helpful process in enhancing the immune response in shrimp especially against WSSV

Histological study of liver and pancreas in adult Otolithes ruber in Bushehr, Iran

In this study, the digestive systems of 10 adult Otolithes ruber specimens from Bushehr province water, south-west Iran were removed and the livers and pancreases were fixed in formalin 10%. The routine procedures of preparation of tissues were followed and the paraffin blocks were cut at 6 microns, stained with H&E and studied under light microscope. The results of microscopic studies showed that liver as the largest accessory organ surrounds the pancreatic tissue in the fish. Liver was found to be a lobulated organ encircling the pancreas among its lobules. Hepatic tissue of the fish was found to be similar to many other bony fishes. Hepatocytes included glycogen and fat vacuoles that located around the hepatic sinusoids. Pancreas as a mixed gland microscopically, was composed of lobules consisting of serous acini (exocrine portion) and langerhans islets (endocrine portion). Pancreatic lobules are usually found as two rows of acini which a large blood vessel located in between

Effect of hypoxia, normoxia and hyperoxia conditions on gill histopathology in two weight groups of beluga (Huso huso)

The influence of dissolved oxygen concentration on gill histopathology of great sturgeon (Huso huso) was evaluated in two weight classes (initial weight 280.9±49.2 g and 1217.9±138.1 g respectively). Oxygen treatments included hypoxia (2-3 mg/l), normoxia (5-6 mg/l) and hyperoxia (9-10 mg/l). The fish were acclimated to experimental tanks for one week then randomly distributed into 9 tanks in each of the initial weight classes (3 and 6 fish per tank in higher and lower initial weight classes respectively) for 8 weeks. In order to find the histopathological changes, gill samples were collected, dehydrated through ethanol series, embedded in paraffin , sectioned at 7 µm thickness using a Leitz microtome and stained with H & E. No mortality was observed over the 8 weeks of the experimental period. There were significant differences in weight and feed intake between treatments in the both weight classes (P<0.05). Fork length showed significant differences in lower initial weight class (P<0.05). The main histopathological changes were observed in gills including: Hyperplasia, loss of secondary lamellae, hemorrhage and congestion in primary and secondary lamellae, lamellar fusion, epithelial lifting in secondary lamellae, clubbing of secondary lamellae, telangiectases, increase in melanin pigments and numerous vacuoles in primary and secondary lamellae (in hyperoxia treatment). All these lesions may reduce gill functional surface of gaseous exchange, impairing respiratory function