The effects of diet supplemented with Lactobacillus rhamnosus on tissue parameters of rainbow trout,Oncorhynchus mykiss (Walbaum)

This study was carried out to establish the effects of a 6 week treatment with the diet supplemented with L. rhamnosus in concentrations of 10⁷ CFU g^?1 (G1 group) and 10⁸ CFU g^?1 (G2 group) on the condition expressed by condition factors (Fulton's, Clark's and B), intestinal microbiology, haematological, histological and selected antioxidative parameters of rainbow trout. A significantly higher condition factors were found in G1 group indicating that higher concentration of probiotic (10⁸ CFU g^?1) did not result in the better condition. Cholesterol and urea levels were significantly higher in both G1 and G2 groups, albumin in G1 and creatinine in G2 group with respect to control. A significantly higher liver TBARS level was observed in G2 group. The feeding with supplemented probiont apparently changed the resident microbiota. Three weeks after withdrawal of the supplemented feed, the microflora mostly reverted to the control composition, although L. rhamnosus in faecal matter of fish remained inherent. The epithelial structure of the proximal and distal intestine revealed the increased absorptive area in both treated groups, as well as the increase in the mucin‐secreting goblet cells. The L. rhamnosus‐treated groups demonstrated the capacity for the augmentation of the innate host defence.     

Occurrence of enteric redmouth disease in rainbow trout (Oncorhynchus mykiss) on farms in Croatia

During the spring of 1996 and autumn of 1997 unusual mortality outbreaks among rainbow trout fry and yearlings occurred at two different trout farms, resulting in mortality of 20 and 10 per cent, respectively. Generally, the affected fish, swimming at the water surface, were reluctant to eat and were dark pigmented with visible haemorrhages around and within the oral cavity. Bacterial isolates from moribund fish from both cases were identified as Yersinia ruckeri by standard biochemical tests and API 20E. The isolated strains were found to be sensitive to tetracycline, chloramphenicol, co-trimoxazole, nalidixic acid, flumequine, enrofloxacin, carbenicillin and gentamicin. Microplate agglutination assay confirmed that both isolates belonged to serotype O1. The pathogenicity of the isolated bacteria was confirmed by challenge experiment. Titres of specific antibodies were determined in the sera of survivors. The titre was highest on the 21st day postchallenge and was detectable until the 81st day.     

A predator unmasked: life cycle of Bdellovibrio bacteriovorus from a genomic perspective

Predatory bacteria remain molecularly enigmatic, despite their presence in many microbial communities. Here we report the complete genome of Bdellovibrio bacteriovorus HD100, a predatory Gram-negative bacterium that invades and consumes other Gram-negative bacteria. Its surprisingly large genome shows no evidence of recent gene transfer from its prey. A plethora of paralogous gene families coding for enzymes, such as hydrolases and transporters, are used throughout the life cycle of B. bacteriovorus for prey entry, prey killing, and the uptake of complex molecules.     

Prevalence and molecular typing of Giardia spp. in captive mammals at the zoo of Zagreb, Croatia

A total of 131 faecal samples from 57 mammalian species housed at the zoo of Zagreb, Croatia, were tested for the presence of Giardia spp. cysts using epifluorescence microscopy. The overall prevalence (29%) was high, yet all animals were asymptomatic at the time of sampling. Positive samples were characterized by PCR and sequence analysis of both conserved and variable loci, for the identification of Giardia species and G. duodenalis assemblages and genotypes. Assemblages A and C were identified in Artiodactyla, assemblage B in Primates, Rodentia and Hyracoidea, and assemblages A, B, C and D, as well as Giardia microti, in Carnivora. Genotyping at the ITS1-5.8S-ITS2 region, at the triose phosphate isomerase, glutamate dehydrogenase and beta-giardin genes revealed extensive polymorphisms, particularly among assemblage B isolates. A phylogenetic analysis of concatenated sequences showed that isolates from captive mammals housed at the zoo are genetically different from isolates of human and domestic animal origin. This is the first survey in a zoological garden to include a molecular characterization of the parasite, and provides novel sequence data of G. duodenalis from many previously uncharacterized hosts.     

Gas-phase ligation of Fe+ and Cu+ ions with some flavonoids

It was assumed that gas-phase ligation of metal monocations by flavonoids might provide some insight on the intrinsic antioxidant activity of the latter. Thus, the ligation of Fe+ and Cu+ ions by apigenin (1), luteolin (2), kaempferol (3), quercetin (4), myricetin (5), and naringenin (6) was investigated in the gas phase in a Fourier transform mass spectrometer (FTMS). Both of the metal ions, which were produced by laser desorption ionization (LDI), bind consecutively to two neutral flavonoid molecules either with or without the simultaneous loss of some part (H, CO, H2O) of the latter. The flavonoids are present in the instrument at steady concentrations. The formation of flavonoid positive ions by charge exchange is also a common observation but is accompanied, in some cases, by a loss of H, CO, or H2O fragments. The reaction paths and observed fragmentations are presented. The results are supported by DFT B3LYP calculations that indicate a preference for metal ion attack at C-ring and not at the B-ring site considered to be mainly responsible for flavonoid antioxidant activity.     

Morphology of the lymph nodes in bottlenose dolphin (Tursiops truncatus) and striped dolphin (Stenella coeruleoalba) from the Adriatic Sea

Morphology of the lymph nodes was examined in six bottlenose dolphins (Tursiops truncatus) and three striped dolphins (Stenella coeruleoalba) from the Adriatic Sea. All animals had been found dead in nature. One group of the nodes was taken from the tracheal branching area and was marked as bifurcational lymph node, and the other group was taken from the mesenteric root and was marked as mesenteric lymph node. Microscopic analysis showed that the lymph nodes in both dolphin species were surrounded by a connective tissue capsule comprising smooth muscle cells. The parenchyma of the mesenteric and bifurcational lymph nodes in bottlenose dolphin was divided into the peripherally situated cortex with the lymphatic nodules and diffuse lymphatic tissue, and the centrally situated medulla structured of the medullary cords separated by the medullary sinuses. These lymph nodes structurally correspond to the lymph nodes in the majority of terrestrial mammals. The mesenteric lymph node of striped dolphin also had a peripherally situated cortex and a centrally positioned medulla as the majority of terrestrial mammals. In the bifurcational lymph nodes of striped dolphin, there was a central dense lymphatic tissue with the lymphatic nodules and a peripheral less dense lymphatic tissue structured of the cell cords and sinuses. The bifurcational lymph node in striped dolphin resembled porcine lymph nodes and belonged to the inverse lymph nodes.     

Whole-genome shotgun sequencing of mitochondria from ancient hair shafts

Although the application of sequencing-by-synthesis techniques to DNA extracted from bones has revolutionized the study of ancient DNA, it has been plagued by large fractions of contaminating environmental DNA. The genetic analyses of hair shafts could be a solution: We present 10 previously unexamined Siberian mammoth (Mammuthus primigenius) mitochondrial genomes, sequenced with up to 48-fold coverage. The observed levels of damage-derived sequencing errors were lower than those observed in previously published frozen bone samples, even though one of the specimens was >50,000 14C years old and another had been stored for 200 years at room temperature. The method therefore sets the stage for molecular-genetic analysis of museum collections.