Behavioral differentiation of underyearlings of the Black Sea salmon <Emphasis Type=Italic>Salmo trutta labrax</Emphasis>: Rheoreaction in the year preceding smoltification

Hatchery rearing underyearlings of the Black Sea salmon Salmo trutta labrax at the age of five-six months (nine-ten months before the beginning of smoltification) divide into two spatial groups—bottom group and pelagic group. This is caused by lack of territory (bottom area): the minority of fish are bottom-dwelling—such fish are territorial, they extrude the majority of individuals to the water column. It is determined experimentally that the bottom-dwelling fish belonging to the bottom group, in comparison with the fish of pelagic group, are characterized by higher critical flow velocities and lower locomotor activity in the rheogradient. Part of individuals with the static type of rheoreaction among them is higher. The fish from the pelagic group do not have such resource as individual territory. This fact modifies the probability of manifestation of resident and migrant behavior after starvation (during ten days). The individuals from the pelagic group demonstrate the behavior characteristic of future migrants (downstream movement) to a higher degree. The individuals from the bottom group, in comparison with pelagic fish, demonstrate, to a great degree, behavior typical for future residents (upstream movement).     

Damaging effect of the fish pathogen <Emphasis Type=Italic>Aeromonas salmonicida</Emphasis> ssp. <Emphasis Type=Italic>salmonicida</Emphasis> on intestinal enterocytes of Atlantic salmon (<Emphasis Type=Italic>Salmo salar</Emphasis> L.)

In fish, bacterial pathogens can enter the host by one or more of three different routes: (a) skin, (b) gills and (c) gastrointestinal tract. Bacteria can cross the gastrointestinal lining in three different ways. In undamaged tissue, bacteria can translocate by transcellular or paracellular routes. Alternatively, bacteria can damage the intestinal lining with extracellular enzymes or toxins before entering. Using an in vitro (Ussing chamber) model, this paper describes intestinal cell damage in Atlantic salmon (Salmo salar L.) caused by the fish pathogen Aeromonas salmonicida ssp. salmonicida, the causative agent of furunculosis. The in vitro method clearly demonstrated substantial detachment of enterocytes from anterior region of the intestine (foregut) upon exposure to the pathogen. In the hindgut (posterior part of the intestine), little detachment was observed but cellular damage involved microvilli, desmosomes and tight junctions. Based on these findings, we suggest that A. salmonicida may obtain entry to the fish by seriously damaging the intestinal lining. Translocation of bacteria through the foregut (rather than the hindgut) is a more likely infection route for A. salmonicida infections in Atlantic salmon.Financial support from the Commission of the European Communities, quality of Life and Management of Living Resources programme, project Q5RT-2000-31656 Gastrointestinal Functions and Food Intake Regulation in Salmonids: Impact of Dietary vegetable Lipids (GUTINTEGRITY) and from Magnus Bergvalls Stiftelse for KS, is acknowledged.This work does not represent the opinion of the European Community, which is thus not responsible for any use of the data presented.     

Sequencing the genome of the Atlantic salmon (<Emphasis Type="Italic">Salmo salar</Emphasis>)

The International Collaboration to Sequence the Atlantic Salmon Genome (ICSASG) will produce a genome sequence that identifies and physically maps all genes in the Atlantic salmon genome and acts as a reference sequence for other salmonids.     

Control of pyrimidine nucleotide formation in <Emphasis Type=Italic>Pseudomonas</Emphasis><Emphasis Type=Italic>fulva</Emphasis>

Control of pyrimidine formation was examined in Pseudomonas fulva ATCC 31418. Pyrimidine supplementation lowered pyrimidine biosynthetic pathway enzyme activities in cells grown on glucose or succinate as a carbon source indicating possible repression of enzyme synthesis. Pyrimidine limitation experiments were conducted using an orotidine 5′-monophosphate decarboxylase mutant strain isolated in this study. Compared to uracil-supplemented, glucose-grown mutant cells, pyrimidine limitation of this strain caused aspartate transcarbamoylase, dihydroorotase, dihydroorotate dehydrogenase and orotate phosphoribosyltransferase activities to increase about 6-, 13-, 3-, 15-fold, respectively, which confirmed regulation of enzyme synthesis by pyrimidines. At the level of enzyme activity, transcarbamoylase activity in Ps. fulva was strongly inhibited by pyrophosphate, CTP, GTP and GDP under saturating substrate concentrations.     

Cryopreservation of <Emphasis Type=Italic>Robinia</Emphasis><Emphasis Type=Italic>pseudoacacia</Emphasis>

Cryopreservation of Robinia pseudoacacia explants by vitrification achieved 78% survival following the stepwise preculture of shoot tips in (0.3 + 0.5 + 0.7 M) sucrose with a 80 min incubation in PVS2; compared to 87% survival after desiccation of explants to 30% water content, following 3 days alginate bead (with glycerol and sucrose treatments) preculture in 0.7 M sucrose.     

Etho-biochemical mechanisms of early differentiation in juveniles of the Atlantic salmon <Emphasis Type="Italic">Salmo salar</Emphasis>

The social status of hatchery-reared juveniles of Atlantic salmon Salmo salar at the age of 11–19 months in conditions of lack of shelters was investigated experimentally. It was demonstrated that biochemical differentiation in such juveniles begins at the age of 13 months—one month before the first differences in the social status of fish and four months prior to the beginning of smoltification. The dominants occupy bottom areas with shelters and extrude the subordinates to the water column. The subordinates undergo smoltification or die from aggression of the dominants. Concentrations of dopamine, noradrenalin, and of their metabolites in the brain of fish in the beginning of smoltification were higher in the dominants and, by the end of smoltification, were higher in smolts. The social behavior of fish is considered to be one of the ethological mechanisms of differentiation of salmon juveniles into smolts and parr.     

Feeding activity and opercular pressure transients in Atlantic salmon (<Emphasis Type=Italic>Salmo salar</Emphasis> L.): application to feeding management in fish farming

Ecological and economical sustainability of marine aquaculture operations depend on proper feeding management. Feed wastage from overfeeding is a source of pollution, represents futile use of precious marine resources, and undermines the economic viability of operations. Additionally, underfeeding reduces growth and fish welfare. Finding an optimal feeding regime in terms of temporal and spatial distribution of the feed ration require intimate knowledge of the individual feeding behaviour of fish sustaining intensive culturing conditions. Fish telemetry has proved to be a valuable tool for studying spatial behaviour in sea cages, however there are currently no practical methods available with respect to detection of actual feed intake in fish on the individual level. The present study investigates pressure transients arising in the opercular cavity of farmed Atlantic salmon (Salmo salar L.) in connection with feeding, and whether such measurements can serve as an indication of feed ingestion. A technical solution to the sensing problem based on a differential pressure transducer is presented along with typical pressure signal traces obtained during feeding in a hard wire tank experiment. Measurements showed considerable variation of sub-ambient pressure transients (1.5 kPa ± 0.95) and their duration (519 ms ± 117), suggesting that the fish modulates its strike intensity depending on the particular feeding situation. Despite variations in scale, opercular pressure waveforms have distinct structural features that repeat between feeding instants. From a signal processing point of view waveforms provide sufficient information with respect to isolation and detection of feeding incidents, which is important with respect to a potential implementation of the sensing principle in a telemetry tag design. Issues regarding development and application of a telemetry system based on this sensing principle are discussed.     

Attenuation of fibrosis <Emphasis Type=Italic>in vitro</Emphasis> and <Emphasis Type=Italic>in vivo</Emphasis> with <Emphasis Type=Italic>SPARC</Emphasis> siRNA

Introduction  

SPARC is a matricellular protein, which, along with other extracellular matrix components including collagens, is commonly over-expressed in fibrotic diseases. The purpose of this study was to examine whether inhibition of SPARC can regulate collagen expression in vitro and in vivo, and subsequently attenuate fibrotic stimulation by bleomycin in mouse skin and lungs.     

Efficient separation and purification of allophycocyanin from <Emphasis Type=Italic>Spirulina</Emphasis> (<Emphasis Type=Italic>Arthrospira</Emphasis>) <Emphasis Type=Italic>platensis</Emphasis>

Allophycocyanin (APC) is a minor component of phycobiliproteins in cyanobacteria and red algae. This paper describes a simple and inexpensive extracting method for isolating APC from Spirulina (Arthrospira) platensis with high efficiency. The crude phycobiliprotein extract was pretreated by ammonium sulfate fractionation. Then, by adding hydroxylapatite into crude phycobiliprotein extract dissolved in 20 mM phosphate buffer (pH 7.0), APC was selectively adsorbed by hydroxylapatite but C-phycocyanin (C-PC) was not. The hydroxylapatite was collected and APC was extracted from the crude phycobiliprotein extract. Then, the enriched APC was washed off from the hydroxylapatite using 100 mM phosphate buffer (pH 7.0). In this simple extracting method it was easy to remove C-PC and isolate APC in large amounts. The absorbance ratio A ₆₅₀/A ₂₈₀ of extracted APC reached 2.0. The recovery yield was 70%, representing 4.61 mg · g⁻¹ wet weight. The extracted APC could be further purified by a simple anion-exchange chromatography with a pH gradient from 5.6 to 4.0. The absorbance ratio A ₆₅₀/A ₂₈₀ of the purified APC reached 5.0, and the overall recovery yield was 43%, representing 2.83 mg · g⁻¹ wet weight. Its purity was confirmed by native polyacrylamide gel electrophoresis (PAGE) and sodium dodecyl sulfate-PAGE.     

Development of ethologo-physiological differentiation between parrs and smolts of the Atlantic salmon <Emphasis Type="Italic">Salmo salar</Emphasis>

Dynamics of the level of monoamines and their metabolites in the brain of juveniles of the Atlantic salmon Salmo salar is investigated in the initial period of differentiation of the progeny into parrs and smolts. The first differences in the level of metabolism of noradrenaline (NA) and 5-HT arise in the optical tectum of the brain before the beginning of smolting. Appearance of the first signs of smolting in juveniles is accompanied by the increase of differences in the level of activity of HA-and 5-HT-ergic systems in the forebrain and hypothalamus. The first differences in the activity of the DAergic system between parrs and smolts were observed in the period of visible differences in fish coloration. In the same period, considerable differences in the level of adrenaline and noradrenaline in the fish blood were recorded. In experiments on a prolonged exposure of fish to a current of different intensity, it was shown that behavior and physiological response of the fish organism are different: in parrs, the stressogenous response is developed, they stop feeding, weight loss takes place, and they cannot withstand the water flow; smolts adapt to the current using heterogeneity of water movements.     

<Emphasis Type=Italic>In vitro</Emphasis> organogenesis of <Emphasis Type=Italic>Passiflora alata</Emphasis>

Passiflora alata in vitro organogenesis was studied based on explant type, culture medium composition, and incubation conditions. The results indicated that the morphogenic process occurred more efficiently when hypocotyl segment-derived explants were cultured in media supplemented with cytokinin and AgNO₃ incubated under a 16-h photoperiod. The shoot bud elongation and plant development were obtained by transferring the material to MSM culture medium supplemented with GA₃ and incubated in flasks with vented lids. Histological analyses of the process revealed that the difficulties in obtaining plants could be related to the development of protuberances and leaf primordia structures, which did not contain shoot apical meristem. Roots developed easily by transferring elongated shoots to 1/2 MSM culture medium. Plant acclimatization occurred successfully, and somaclonal variation was not visually detected. The efficiency of this organogenesis protocol will be evaluated for genetic transformation of this species to obtain transgenic plants expressing genes that can influence the resistance to Cowpea aphid borne mosaic virus.     

Interaction of <Emphasis Type=Italic>Bdellovibrio bacteriovorus</Emphasis> with bacteria <Emphasis Type=Italic>Campylobacter jejuni</Emphasis> and <Emphasis Type=Italic>Helicobacter pylori</Emphasis>

Interaction of Bdellovibrio bacteriovorus 100NCJB with bacteria Campylobacter jejuni (strains 1, 2, 3, 4, and 5) and Helicobacter pylori, strain TX30a, was confirmed. The results indicate that lytic activity of bdellovibrios both in liquid media and cells attached to a surface was observed. The potential use of the antimicrobial activity of predatory bacteria for environmental bioprotection and public health is discussed.     

Regulation of the <Emphasis Type=Italic>ALBINO3</Emphasis>-mediated transition to flowering in <Emphasis Type=Italic>Arabidopsis</Emphasis> depends on the expression of <Emphasis Type=Italic>CO</Emphasis> and <Emphasis Type=Italic>GA1</Emphasis>

ALBINO3, a homologue of PPF1 in Arabidopsis, encodes a chloroplast protein, and is essential for chloroplast differentiation. In the present study, ALBINO3(−) transgenic plants exhibited a significant decrease in both the number of rosette leaves at bolting and the days before bolting, suggesting the important roles of ALBINO3 in regulating flowering during non-inductive short-day photoperiods. ALBINO3 mRNA was apparently accumulated in shoot apical meristem and floral meristems around the shoot apical meristem in wild-type plants. ALBINO3 might be predominantly involved in inducing the floral repression pathway by activating the expression of TFL1, and by suppressing the expression of LFY, respectively, in the shoot apical meristem. Moreover, the function of ALBINO3 in regulating flowering transition depended on the expression of CO and GA1, because ALBINO3 might function in the downstream integration of the photoperiod-dependent and the photoperiod-independent pathways. These results suggest that ALBINO3 may have an important integrative function in the flowering process in Arabidopsis.     

Deep-diving of Atlantic salmon (<Emphasis Type="Italic">Salmo salar</Emphasis>) during their marine feeding migrations

Data from seven data storage tags recovered from Atlantic salmon marked as smolts were analyzed for depth movements and patterns of deep diving during the marine migration. The salmon mostly stayed at the surface and showed diurnal activity especially from autumn until spring. During the first months at sea the salmon stayed at shallower depths (<100 m). The salmon took short deep dives (>100 m), that were rare or absent during the first summer at sea but increased in frequency and duration especially in late winter. The maximum depth of the dives varied from 419 to 1187 m. Most of dives were short, (<5 h) but could last up to 33 h. The duration of dives increased in late winter until spring and the overall depth and maximum depth per dive increased exponentially over time. The initiation of the dives was more common in evenings and at night, suggesting nocturnal diving. We hypothesized that deep diving is related to feeding of salmon as mesopelagic fish can be important food for salmon during winter.     

Probiotic <Emphasis Type=Italic>Lactobacillus</Emphasis> strains: <Emphasis Type=Italic>in vitro</Emphasis> and <Emphasis Type=Italic>in vivo</Emphasis> studies

Three Lactobacillus strains (LOCK 0900, LOCK 0908, LOCK 0919) out of twenty-four isolates were selected according to their antagonistic activity against pathogenic bacteria, resistance to low pH and milieu of bile salts. Intragastric administration of a mixture of these strains to Balb/c mice affected cytokine T_H1-T_H2 balance toward nonallergic T_H1 response. Spleen cells, isolated from lactobacilli-treated mice and re-stimulated in vitro with the mixture of heat-inactivated tested strains, produced significantly higher amounts of anti-allergic tumor necrosis factor- and interferon-γ than control animals whereas the level of pro-allergic interleukin-5 was significantly lower. Lactobacillus cells did not translocate through the intestinal barrier into blood, liver and spleen; a few Lactobacillus cells found in mesenteric lymph nodes could create antigenic reservoir activating the immune system. The mixture of Lactobacillus LOCK 0900, LOCK 0908 and LOCK 0919 strains represents a probiotic bacterial preparation with possible use in prophylaxis and/or therapy of allergic diseases.