Zdravko Petrinec

Screening toxicity study in young carp (Cyprinus carpio L.) on feed amended with fumonisin B1

Fumonisin B1 (FB1) is one of several mycotoxins produced by Fusarium moniliforme, a major fungal pathogen of corn and widely spread throughout the world. FB1 produces a wide range of biological effects, some of which are specific for particular organs or species and some are common to all investigated animals. In this study we have evaluated subchronic toxicosis features in young carp (Cyprinus carpio L.) exposed to 0.5 and 5.0 mg FB1 kg−1 body weight for 42 days through nutritionally balanced diet. During the trial we observed loss of body weight in both treated groups, together with higher incidence of infective bacterial dermatological lesions erythrodermatitis cyprini (Aeromonas salmonicida subsp. nova) in the group treated with the higher FB1 dose. Several hematological parameters (erythrocyte count, platelet count) and serum chemical concentrations (creatinin, total bilirubin) and activities (aspartate aminotransferase, AST and alanine aminotransferase, ALT) were greater in the fumonisin treated groups than in the control group. Our results indicate that long-term dietary exposure to 0.5 and 5.0 mg FB1 kg−1 body weight is not lethal to young carp, but can produce adverse physiological effects. These findings also suggest that primary target organs of FB1 in the carp are kidney and liver, as it has already been observed in other animal species tested. Specifically changed red blood cell-parameters reveal that FB1 probably causes erythrocyte membrane defect or interferes with carps respiratory process.

The Development of the Digestive Tract in Larval European Catfish (Silurus glanis L.)

The European catfish, Silurus glanis L., has become an important aqua cultural fish in Croatia, and it is cultivated extensively in ponds in polyculture with carps. The development of the digestive tract in S. glanis was studied with the aim of improving intensive fish production. Research was carried out on S. glanis larval stadium from 1‐ to 19‐day post‐hatching (DPH). The main histological methods used were: haematoxylin and eosin staining, periodic acid Schiff staining (PAS), Alcian blue (AB) and toluidin blue staining (TB). A yolk sac was present during the first 5 days (1–5‐DPH). During the initial 3‐DPH period, there was no trace PAS and AB activity in the digestive tract. Differentiation of the digestive tract began at 3‐ to 5‐DPH. The oesophagus was positive for AB at 5‐DPH, PAS and TB after 7‐DPH. Differentiation of enterocytes began at 5‐DPG and the intestines were complete at 11‐DPH. Development of liver and pancreas was also studied. The analysis of data obtained in this study suggests that after 5‐DPH catfish larvae have morphologically completed digestive tracts.

Monitoring health status of Croatian honey bee colonies and possible reasons for winter losses

During recent years it appears that there have been increasing losses of honey bee colonies, and potential reasons are diseases, environmental factors such as pesticides and nutrition related stress among others. Honey bee diseases in particular pose considerable difficulties for beekeepers and the economy of a whole country. The intention of this study was to determine the total winter losses and the opinion of the beekeepers about the potential reasons for bee losses and the health conditions of their colonies.

Yersinia ruckeri septicaemia in experimentally infected carp (Cyprinus carpio L.) fingerlings.

The presence of Yersinia ruckeri, the causal agent of enteric redmouth disease (ERM) in salmonids and a few other freshwater fish, has so far been reported from a variety of sources including the intestine of healthy carp. Since there are no data on the pathogenicity of this bacterium for carp, 15 fingerlings were experimentally infected by intraperitoneal injection of about 5 x 10(5) cells. Thirteen injected fish were moribund or died within 4 days with septicaemic lesions. Two survivors were sampled on Day 28 after infection. Yersinia ruckeri was reisolated from the internal organs of all experimental fish. By histopathological examination moribund fish had generalised bacteriaemia with inflammation, degeneration and necrotic foci in kidney, liver and spleen, corresponding to findings described previously in ERM of rainbow trout. Survivors of challenge on Day 28 had a chronic disease characterised by prominent peritonitis and enteritis, exhaustion of the erythroid, granuloid and lymphoid components in haematopoietic kidney tissue as well as focal degeneration and necrosis in organs. These data indicate a high sensitivity of carp to intraperitoneal infection with a relatively low dose of Y. ruckeri.

Fumonisin B1 Neurotoxicity in Young Carp (Cyprinus carpio L.)

Fumonisin B1 Neurotoxicity in Young Carp (Cyprinus Carpio L.) For years scientists have suspected that the environment plays a role in neurodegenerative diseases such as Alzheimers disease, Parkinsons disease, and multiple sclerosis. Mycotoxin fumonisin B1 (FB1) is produced by several Fusarium species, mainly by Fusarium verticilioides, which is one of the most common fungi associated with corn worldwide. Fumonisins are known to cause equine leukoencephalomalacia, a disease associated with the consumption of corn-based feeds contaminated with FB1. Here we have reported chronic experimental toxicosis in one-year-old carp (Cyprinus carpio L.) receiving feed containing 100 mg kg-1 or 10 mg kg-1 of added FB1 for 42 days. We focused on fumonisin toxicity in the fish brain. After staining with hemalaun-eosin, histology of the fish brain revealed vacuolated, degenerate, or necrotic neural cells, scattered around damaged blood capillaries and in the periventricular area. These findings suggest that fumonisin, although it is a hydrophilic molecule, permeated the blood-brain barrier of young carp and had a toxic effect on neuronal cells. Neurotoksičnost fumonizina B1 u šaranske mLađi (Cyprinus carpio L.) Odavno je poznato da okoliš ima važnu ulogu u razvoju neurodegenerativnih bolesti kao što su Alzheimerova i Parkinsonova bolest te multipla skleroza. Mikotoksin fumonizin B1 (FB1) tvori nekoliko vrsta Fusariuma, najčešće F. verticillioides, koja je najučestaliji kontaminant kukuruza. Ovaj mikotoksin odgovoran je za leukoencefalomalaciju konja, mula i magaradi povezanu s konzumacijom kukuruza kontaminiranog s FB1. U ovom su radu prikazani rezultati kronične eksperimentalne toksikoze mlađi šarana (Cyprinus carpio L.) koji su u hrani primali 100 mg kg-1 i 10 mg kg-1 FB1 tijekom 42 dana. Nakon bojenja hemalaun-eozinom zabilježene su značajne histopatološke promjene na mozgu životinja uključujući vakuolizaciju, degeneraciju i nekrozu neurona, posebice u blizini oštećenih krvnih kapilara i u periventrikularnoj regiji. Ova saznanja pokazuju da FB1, kao hidrofilna molekula, prolazi kroz krvno-moždanu barijeru mladih šarana uzrokujući oštećenje neurona.

Metacercariae of Centrocestus formosanus in goldfish (Carassius auratus L.) imported into Croatia

SummaryThe presence of metacercariae of Centrocestus formosanus was detected on the gills of goldfish (Carassius auratus L.) imported from Singapore and obtained from two pet shops. This is the first report of the parasite in Croatia. The histopathological changes observed lead to the conclusion that the infection could be one of the reasons for the death of goldfish.

Osteological Development of the Garfish (Belone belone) Larvae

Garfish, Belone belone (Linnaeus, 1761) is an elongate, slander fish inhabiting the Eastern Atlantic and Mediterranean Sea. These fish from the Belonidae (Actinopterygii) family have important commercial value for Croatian fisheries. Samples for research were collected from experimental hatching in the Novigrad Sea. Preparation techniques included fixation in buffered formalin, trypsin clearing and staining with alcian blue and alizarin red. As little is known of garfish osteology and bone morphology, the main goal of this study was to describe ossification process in garfish fry. At hatching, no skeletal structure is present. Newly‐hatched larvae also had no osteological elements. Ossification started at 7 day post‐hatching (DPH) [total length (TL) 18 mm] with head bones and vertebral neural arch. Head skeleton continued to develop mostly over the period from 7 to 10 DPH. At 21 DPH (TL 49 mm), ossification process seemed to be finished, but it was not possible to distinguish borders of all bones. The primary interest of our research was to understand the growth dynamics as well as transformation of supporting body elements from cartilage to bone. At the end, developmental characteristics and functional aspects of this formation in different fish species are discussed.

Growth dynamics of white muscle fibres in relation to somatic growth of larvae of European sea bass (Dicentrarchus labrax, L.).

The body length and diameter of muscle fibres from the right hypaxial tail myomeres were measured in 100 sea bass larvae (Dicentrarchus labrax, L.) at ages of 40 to 90 days, from a fish farm in Croatia. The larvae were kept at a temperature of 19–20˚C and fed with standard feed for their respective ages. Body lengths of larvae 40–90 days old varied from 8 to 42 mm, increasing significantly in 10-day intervals (p<0.001), except between days 50 and 60 when there was no increase in the body length. The measured diameters of muscle fibres ranged from 10 to 80 μm, the mean value increasing except between days 50 and 60. The fibre diameter in larvae aged up to 60 days was 10–40 μm, while that in larvae older than 70 days was 51–80 μm. In 90-day-old larvae there were no fibres of 10–20 μm in diameter; however, the number of fibers of 61–80 μm diameter increased. A statistically significant concordance was determined between the body length and fibre diameter of larvae 70 to 90 days old. Between days 50 and 60, arrested growth of the larval body and corresponding decrease in fibre diameter was observed. From day 45 until days 59, larvae were fed with Artemia nauplii and microparticles of formulated diets. From the day 60, minced fish was added to formulated diets. This change in diet probably resulted in the observed growth arrest.

Detection of Nosema ceranae in honey bees from Croatia

honey bee, distribution, Nosema apis, Nosema ceranae, Croatia Journal of Apicultural Research and Bee World 49(4): 340-341 (2010)

Histochemical Analyses of Digestive Enzymes in the Intestine of Adult Large‐Scaled Gurnard (Lepidotrigla Cavillone, Lacepède, 1801)

With 9 figures and 2 tables