Srebrenka Nejedli

Campylobacter, salmonella and chlamydia in free-living birds of Croatia

Campylobacteriosis, salmonellosis and avian chlamydiosis are zoonotic diseases in which birds have been suggested to play an important role as reservoirs. We have investigated the prevalence of Campylobacter and Salmonella spp. and Chlamydophila sp. in 107 free-living birds belonging to 25 species from 13 families from Croatia in order to examine the natural infections caused by these agents. Campylobacter jejuni-like organisms were isolated from 2 of 107 free-living bird species examined (1.9%). Salmonella was isolated from 8 fresh fecal specimens from free-living bird species (7.4%). These isolates were identified as S. typhimurium in 4 (3.7%), and S. enteriditis in 4 (3.7%) free-living birds. These samples originated from feral pigeons (Columba livia domesticus; n=14; 28.6%), rook (Corvus frugilegus; n=13; 15.4%), buzzard (Buteo buteo; n=12; 16.7%), black-headed gull (Larus ridibundus; n=8; 12.5%) and tawny owl (Strix aluco; n=8; 12.5%). The presence of Chlamydophila sp. was not detected in the free-living birds examined during this study. Epidemiological aspects and possible significance of the examined birds as a source of infections for domestic animals and humans are discussed.

Morphological and histochemical study of intestine in wild and reared European eel (Anguilla anguilla L.).

Diet-related differences between the ratio of intestine length to body size and the enzymatic activity in the intestinal tract of wild and reared European eel (Anguilla anguilla L.) were studied. Compared with reared eel, wild eel showed significantly shorter relative intestine length. For the purpose of histochemical examination, different parts (anterior, middle and posterior) of intestine proper were used. Activities of non-specific esterase, alkaline and acid phosphatase, and aminopeptidase were examined in each segment. All enzymes were present in the intestines of both wild and reared European eel. Fish from both groups showed similar enzyme distribution within the enterocytes, but distribution and intensity of enzyme activity along the intestine vary depending on the group. Generally, reared European eel showed highest enzymatic activity and wider distribution of enzymes throughout all parts of the intestine. These results suggest that different diets could be one of the reasons for observed changes.

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.

Histochemical distribution of digestive enzymes in the intestine of the common two-banded seabream, Diplodus vulgaris, Geoffroy St-Hilaire 1817.

The histochemical localization of non‐specific esterase, alkaline and acid phosphatase as well as aminopeptidase in the intestine of the free‐living common two‐banded sea bream (Diplodus vulgaris) was investigated. Fish were caught near the town of Zadar (Adriatic Sea, Croatia). Samples of pyloric caeca and three parts of the intestine proper (anterior, middle and posterior) were used for the description of non‐specific esterase, alkaline and acid phosphatase as well as aminopeptidase. Non‐specific esterase activity was found in the cytoplasm of enterocytes in pyloric caeca and in all investigated intestinal segments. The activity was stronger in the anterior and posterior part of the intestine than in the pyloric caeca and middle segment of the intestine. Intestinal alkaline phosphatase was detected in brush border of enterocytes of all investigated intestinal segments. Enzymatic activity gradually decreased in a posterior direction. Acid phosphatase activity was observed as a fine granular reaction product in the supranuclear region of enterocytes. This activity was almost equal in pyloric caeca as well as in the anterior intestinal segment, while it was stronger in the middle and posterior intestinal segment. Aminopeptidase was present along the intestinal epithelium brush border in all investigated parts of the digestive tube. The intensity of aminopeptidase increased posteriorly. The possible role of investigated enzymes in intracellular digestion and transport is discussed.

Zeolite clinoptilolite as a dietary supplement and remedy for honeybee (Apis mellifera L.) colonies

Control of the nosema disease poses a major challenge, and therefore, treatment of this serious para - sitic disease using natural preparations could be of great benefit. The aim of this study was to test the performance of zeolite clinoptilolite as a curative measure against honeybee colonies ( Apis mellifera L.) naturally infected by Nosema ceranae. The histopathological structure, and the content and distribution of mucosubstances and his - tochemical activity of aminopeptidase and non-specific esterase in the midgut mucosa of honeybees originating from colonies fed sugar syrup supplemented with zeolite minerals was studied. A decline in the number of spores in honeybees fed with zeolite clinoliptolite was observed on the first sampling day (Day 10; 53.25 15.15 million spores/bee), though a statistically lower number of spores in comparison to the control was confirmed on Day 20 (41.08 ± 9.4 million spores/bee), Day 30 (28.42 ± 7.79 million spores/bee) and Day 40 (24 ± 6.25 million spores/bee). The possibility of using natural zeolites as a dietary supplement for honeybee colonies as a preventative measure and for the reduction of the deleterious effects of nosemosis is discussed.