Nikolina Novakov

Organochlorine pesticides in canned tuna and sardines on the Serbian market

ABSTRACT The aim of this study was to determine the level of organochlorine (OC) pesticides in 57 samples of canned tuna and 31 samples of canned sardines in vegetable oil, collected from supermarkets in Serbia. OC pesticides α-HCH, β-HCH, δ-HCH, dichlorodiphenyltrichloroethane (DDT), DDE, DDD, dielderin, endosulfane I, endosulfane II, endosulan sulfate, endrin, endrin ketone, heptachlor, heptachlor epoxide, lindane, aldrin, metoxichlor, cis-chlordane and trans-chlordane were determined using a GS-MS method. The highest concentrations (µg kg−1, arithmetic means) in canned tuna were for δ-HCH (60.6 ± 97.0) and p, p´-DDT (55.0 ± 25.1), while the corresponding values in canned sardines were for δ-HCH (90.7 ± 102.7) and endosulfane II (78.0 ± 145.9). Mean level for the sum of endosulfans was above the maximum limit in canned sardines (85.0 µg kg−1). Also, dieldrin (39.7 µg kg−1) was measured above the ML.

The first determination of Eustrongylides excisus Jägerskiöld, 1909 — larvae (Nematoda: Dioctophymatidae) in the pike-perch Sander lucioperca in Vojvodina (Serbia)

Twenty-one specimens of pike-perch (Sander lucioperca) were caught in the Danube-Tisa-Danube Canal in the city area of Novi Sad for parasitological examination. The presence of nematodes in the muscles was revealed in three fish. The parasites were identified to belong to the species Eustrongylides excisus, for which the pike-perch is a paratenic host. This finding represents the first determination of the larvae in the pike-perch in Serbia. The pike-perch is infected by ingestion of benthos- or plankton-eating fishes, the second intermediate hosts harbouring the fourth-stage nematode larvae. E. excisus is pathogenic to humans, who may be infected by consuming raw or undercooked fish.

Heavy metals and PAHs in canned fish supplies on the Serbian market

ABSTRACT The aim of this study was to determine the level of heavy metals and polycyclic aromatic hydrocarbons (PAHs) in 57 samples of canned tuna, 25 samples of canned sardines, and 16 samples of canned smoked sprouts, collected from supermarkets in Serbia. Heavy metal levels (lead, cadmium, mercury, arsenic, iron, copper, and zinc) were determined using an inductive coupled plasma mass spectrometry method. Sixteen analysed PAHs were determined using a gas chromatography–mass spectrometry method. The trace elements in canned fish were in the range (mg kg−1) of 0.01–0.28 for lead, 0.003–0.08 for cadmium, 0.007–0.64 for mercury, 0.17–3.73 for arsenic, 3.88–52.2 for iron, 0.2–5.95 for copper, and 1.35–44.5 for zinc. Total PAH levels reached 17.67 µg kg−1 in canned tuna and 15.12 µg kg−1 in sardines, whereas in smoked sprouts it amounted to 57.19 µg kg−1. Some of the samples contained cadmium, arsenic, copper, and benzo(a)pyrene above the limits as set by the European and Serbian legislation.

The establishment of the cell culture of preadipocytes of common carp (Cyprinus carpio L.)

Common carp is the most important freshwater fish in aquaculture in Republic of Serbia. Excess fat deposition in the meat and abdominal cavity of farmed carp can affect carp flesh quality, dressing percentage and consequently restrict the further development of aquaculture production. The reasons for lipid deposition in carp flesh and around visceral organs are not well known, and it is important to develop method which would enable us to understand process which occurs in common carp lipid cells. The aim of this study was to establish a new model of common carp preadipocytes and evaluate proliferation and differentiation capacity of carp preadipocytes in vitro. The establishment of the cell culture of preadipocytes of common carp could serve as a valuable tool for studying fat metabolism in this fish species.

Comparison of the Efficacy of Hydrogen Peroxide and Salt for Control of Fungal Infections on Brown Trout (Salmo trutta) Eggs

Background: Fungal infections can cause serious problems infecting fish eggs, especially unfertilized or dead eggs. In the past, this problem was solved by using very effective chemicals such as malachite green and formalin. But, due to its toxicity and carcinogenicity, malachite green was banned for use in fish intended for human consumption. Formalin also has been banned in most countries. Chemicals and drugs recommended for use to treat fungal infections are hydrogen peroxide, salt, potassium permanganate etc. The goal of the present study was to determine and compare the efficacy of antifungal effects of hydrogen peroxide and sodium chloride on brown trout eggs. Materials, Methods & Results: The experiment was conducted in the brown trout hatchery, Sipovo, Bosnia and Herzegovina. The experimental groups contained 500 and 1000 mg/L of hydrogen peroxide with 15 and 30 min of exposition; 1 and 2.5% of sodium chloride with 15 and 30 min of exposition and a negative control group (no chemical treatment). The treatment concentrations were calculated and prepared from hydrogen peroxide of 35% active ingredient, and sodium chloride (sterilized) of 100% active ingredient. Eggs for the study were spawned from 11 females and 4 males. The first treatment was performed on the fourth day, and each next treatment was performed at 3-day intervals. Six treatments were administered until the 19th day after the fertilization. The treatment of the eggs was provided until the eggs reached the eyed stage. The effectiveness of the chemical treatments was measured by a hatch rate. There was a significant difference between all treated groups and the negative control group (P < 0.05). Hydrogen peroxide with a concentration of 500 mg/L for 30 min was the most effective and demonstrated a higher hatching rate (75.7%). Sodium chloride treatments resulted in statistically significantly lower hatching rates than hydrogen peroxide treatments. The hatching rate in salt treatment with a concentration of 2.5% for 30 min was 27.3% lower than in hydrogen peroxide treatment with a concentration of 500 mg/L for 30 min. Discussion: Hydrogen peroxide is an effective antifungal, antibacterial and antiviral compound, and according to the Food and Drug Administration (FDA), hydrogen peroxide and salt are approved and classified as a low regulatory priority for the control of oomycetes on all species and life stages of fish. It is considered to be a very environmentally compatible chemical because it does not produce any toxic bioproducts when it decomposes. Hydrogen peroxide stood out as the best candidate substance for fungal control. The fact that the treatment with hydrogen peroxide at a concentration of 500 mg/L for 30 min was more effective than treatments at a concentration of 1000 mg/L can be explained by temperature dependency and treatment frequency of this chemical. Salt was not such an effective fungicide as hydrogen peroxide. When using salt, toxicity to the eggs should also be considered. Salt solutions may cause egg deaths at levels of 2.5% or higher. It is possible that high salinities have an inhibitory effect on the movement of fish embryo due to the high osmotic impact on the perivitelline layer. Thus, hydrogen peroxide has proven to be efficient, inexpensive, easy to use and environmentally safe in preventing fungal infections on brown trout eggs.

Helminth fauna and zoonotic potential of the European hamster Cricetus cricetus Linnaeus, 1758 in agrobiocoenoses from Vojvodina province (Serbia)

Summary A total of 359 European hamsters (Cricetus cricetus) captured at four localities in Vojvodina Province were examined for the presence of helminths. The majority of the captured animals (88 %) were infected with nematode species Heligmosomoides travassosi and six species of cestodes (Hymenolepis diminuta, Rodentolepis fraterna, R. straminea, Paranoplocephala omphalodes and Mesocestoides sp. - in larval stages). Nematodes were the dominant group. The dominant cestode species was H. diminuta. All of the tapeworm species reported here represent new findings for the European hamster in Serbia. The tapeworms H. diminuta and Mesocestoides sp. are capable of infecting humans and causing pathological symptoms, making the hamster a carrier of zoonoses and a potential threat to public health. In order to uncover the full range of helminths utilizing the European hamster as a host in Serbia and understanding the scope of its zoonotic potential, further research on the subject must be carried out.

Different manifestations of Thelohanellus nikolskii infection in carp (Cyprinus carpio).

Thelohanellosis is a disease that occurs in all carp categories. The cause is protozoa Thelohanellus nikolskii Achmerov, 1955. It manifests itself in two forms. The first form occurs on the fins in oneyear- old carp fry and the second one occurs on scales in two-yearold, three-year-old and older categories of common carp (Cyprinus carpio). The researches conducted between 2008 and 2012 covered 22 fish ponds, 18 of which are located in Serbia, and 4 in Bosnia and Herzegovina, Republic of Srpska. It has been concluded that both forms of the disease were present in all observed fish ponds. Prevalence of telohanellosis located on the fins ranged between 3% and 30%, and the infection intensity was between 2 and 86 cysts per individual, while in the case of thelohanellosis on scales the values were higher. Changes on the scales were present during April and May, and on the fins during July and August. After determination of morphological characteristics of spores and histopathological characteristics of plasmodia located on the fins and scales, no significant differences were noticed between them. Also, artificial infestation of carp fingerlings for species differentiation was done. Since there are no adequate therapeutic measures, control of thelohanellosis is still based on compliance with basic sanitaryprophylactic measures such as drying of equipment, freezing, mechanical cleaning and disinfection with lime.