Metal-handling strategies of various fish species are known to vary significantly in association with their intracellular metal behaviour. Thus, to better understand the possible consequences of ...increased metal exposure in fish it is important to perform comparative studies on metal-binding biomolecules in organs of different species. This study was the first of this kind on a liver of an esocid fish (northern pike, Esox lucius), and the gathered information were compared to fish belonging to three other families, Leuciscidae, Cyprinidae and Salmonidae. Distributions of ten elements among cytosolic biomolecules of different molecular masses were studied by size exclusion HPLC combined offline with high resolution ICP-MS. The results indicated predominant association of Co, Fe and Mo to high molecular mass biomolecules (>100 kDa), of Zn and Bi to both high and medium molecular mass biomolecules (>30 kDa), of Mn and Se to medium molecular mass biomolecules (30–100 kDa), and Ag, Cd and Cu to low molecular mass biomolecules (10–30 kDa), presumably metallothioneins. Evident binding to metallothioneins was also detected for Zn and Bi. For several metals, distinct differences were observed when cytosolic metal distributions of northern pike were compared to leuciscids, salmonids and cyprinids. More pronounced Zn binding to metallothioneins was recorded in leuciscids and cyprinids than both esocids and salmonids, whereas cytosolic Mn and Se distributions clearly differed between all studied fish families. Accordingly, in assessment of metal pollution it is vital to consider the exposed species, which requires prior comprehensive comparative research on numerous aquatic organisms.
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•The first comprehensive study of metal-binding biomolecules in an esocid fish•Metal distributions in northern pike hepatic cytosol determined by SEC-HPLC-ICP-MS•Binding to metallothioneins established for Ag, Bi, Cd, Cu, and Zn•Essential metals tend to bind biomolecules of higher molecular masses (>100 kDa).•Differences between several freshwater fish species established for Zn, Mn, and Se
ABSTRACT
Trypanosoma (Megatrypanum) melophagium is a parasite of sheep transmitted by sheep keds, the sheep‐restricted ectoparasite Melophagus ovinus (Diptera: Hippoboscidae). Sheep keds were 100% ...prevalent in sheep from five organic farms in Croatia, Southeastern Europe, whereas trypanosomes morphologically compatible with T. melophagium were 86% prevalent in the guts of the sheep keds. Multilocus phylogenetic analyses using sequences of small subunit rRNA, glycosomal glyceraldehyde‐3‐phosphate dehydrogenase, spliced leader, and internal transcribed spacer 1 of the rDNA distinguished T. melophagium from all allied trypanosomes from other ruminant species and placed the trypanosome in the subgenus Megatrypanum. Trypanosomes from sheep keds from Croatia and Scotland, the only available isolates for comparison, shared identical sequences. All biologic and phylogenetic inferences support the restriction of T. melophagium to sheep and, especially, to the sheep keds. The comparison of trypanosomes from sheep, cattle, and deer from the same country, which was never achieved before this work, strongly supported the host‐restricted specificity of trypanosomes of the subgenus Megatrypanum. Our findings indicate that with the expansion of organic farms, both sheep keds and T. melophagium may re‐emerge as parasitic infections of sheep.
Hematological and biochemical tests are widely used for assessment of health status and diagnosis of disease in domestic animals. They are almost indispensible in health management of organic flocks, ...but environmental conditions and food supply can be highly variable in organic farming, which may cause levels of many analytes to lie outside the published reference intervals. We investigated key hematological and biochemical parameters in organically raised sheep in Croatia. Different (mostly indigenous) breeds raised in various geographic regions were evaluated throughout the year. We identified key parameters that varied under different conditions using classification based on machine learning. Our findings suggest that location (which determines climate and food availability) has a profound effect on hematological and biochemical values in organically raised sheep. The effect of location was more pronounced than that of breed and season. The results clearly show the merit of establishing specific reference intervals for each flock, especially in organic farming. We demonstrate feasibility of this approach by successful calculation of reference intervals from a small sample (30 individuals) using robust statistical methods.
An increased frequency of Proteus mirabilis isolates resistant to expanded-spectrum cephalosporins was observed recently in a long-term care facility in Zagreb (Godan). The aim of this study was the ...molecular characterization of resistance mechanisms to new cephalosporins in P. mirabilis isolates from this nursing home.
Thirty-eight isolates collected from 2013-2015 showing reduced susceptibility to ceftazidime were investigated. Antibiotic susceptibilities were determined by broth microdilution method. Inhibitor-based tests were performed to detect extended-spectrum (ESBLs) and AmpC β-lactamases. AmpC β-lactamases were characterized by polymerase chain reaction (PCR) followed by sequencing of bla ampC genes. Quinolone resistance determinants (qnr genes) were characterized by PCR. Genotyping of the isolates was performed by repetitive element sequence (rep)-PCR and pulsed-field gel electrophoresis (PFGE).
Presence of an AmpC β-lactamase was confirmed in all isolates by combined-disk test with phenylboronic acid. All isolates were resistant to amoxicillin alone and combined with clavulanate, cefotaxime, ceftriaxone, cefoxitin, and ciprofloxacin; but susceptible to cefepime, imipenem, and meropenem. PCR followed by sequencing using primers targeting bla ampc genes revealed CMY-16 β-lactamase in all but one strain. Bla cmy-16 was carried by a non-conjugative plasmid which did not belong to any known plasmid-based replicon typing (PBRT) group. Rep-PCR identified one large clone consisting of 15 isolates, three pairs or related isolates, one triplet, and four singletons. PFGE confirmed the clonality of the isolates.
This is the first report of multidrug resistant P. mirabilis in a nursing home in Croatia. Cephalosporin resistance was due to plasmid-mediated AmpC β-lactamase CMY-16.
The antimicrobial susceptibility of coagulase-negative staphylococci isolated from spontaneously fermented sausages was assessed using both traditional and molecular methods. Isolates were tested for ...sensitivity to vancomycin, ampicillin, erythromycin, tetracycline, gentamycin and oxacillin by the disk diffusion method and quantitative-qualitative epsilometer test. PCR was used for the detection of resistance genes mecA, ermB, tetK and tetM. The identified coagulase-negative staphylococci were Staphylococcus epidermidis (69 %), S. capitis (5 %) and S. warneri (2.5 %). S. epidermidis showed a high rate of phenotypical resistance to tetracycline and erythromycin (44.4 % of strains). Molecular evaluation of resistance determinants revealed tetK or tetM genes in eight S. epidermidis strains. Although S. epidermidis is not classical food poisoning bacteria, its presence in food could be of public health significance due to the possible spread of antimicrobial resistance determinants. Our findings implicate that spontaneous meat fermentation could result in products with a potential hazard to consumers.
Metacercariae of the digenetic trematode Clinostomum complanatum Rudolphi, 1814 were observed in chub (Squalius cephalus) and common carp (Cyprinus carpio) from the Orljava River (Croatia). Both the ...prevalence and infection intensity were higher in the chub (prevalence 23.4%, average intensity 70.5) than in the common carp (5.9%, 4.5). In general, the metacercariae were located in the wall of the anterior part of the digestive tract and branchial cavity, the supraocular region, and the hypaxial musculature near the paired fins. Histology revealed the obvious affinity of the parasite for striated muscles and connective tissue. In situ, the metacercariae were surrounded by wellvascularized connective tissue capsules composed primarily of collagen fibers, fibroblasts, and fibrocytes. This study provides some insight into the parasite’s pathogenicity and the relationship between host and parasite.
The relationship between growth rate and ossification is not consistent among fish. In some species, fast-growing individuals ossify earlier, while in other species, a trade-off between growth rate ...and ossification exists. This research was conducted to test the hypothesis about the existence of a trade-off mechanism in common carp offspring. For this purpose, specimens from two groups of common carp offspring (96 in total) with different growth rates were sampled at multiple time points between 5 and 29 days post-hatching. The standard length was measured and presented in correlation with the days post-hatching. To evaluate the skeletal system development, whole specimens were fixed in 10% neutral buffered formalin and stained for bone and cartilage. Particular emphasis was placed on the onset of ossification in the clearly visible bones of the head, vertebral column, and fins. According to our findings, larger, fast-growing specimens ossify earlier. The hypothesis on the existence of a trade-off between fast growth and the onset of ossification in common carp was not confirmed in our study.
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