Local variation in arctic fox abundance on Svalbard,Norway

Arctic fox (Alopex lagopus) numbers vary greatly, with cyclic fluctuations often associated with fluctuations in microtine rodents. However, in areas where small prey mammals are absent, such as Iceland and Svalbard, such cyclic fluctuations are lacking. Annual fluctuations in the density of the arctic fox population on the Brøggerhalvøya peninsula and Kongsfjorden region on Svalbard, Norway, were studied from 1990 to 2001 by using indices of fox abundance. All indices showed similar trends; fox numbers were low in 1990, increased until 1995 whereupon they decreased sharply, before increasing again and levelling off in 2001. Increasing numbers of foxes during the first part of the study paralleled increasing numbers of Svalbard reindeer (Rangifer tarandus platyrhynchus) carcasses in winter and increasing numbers of nesting barnacle geese (Branta leucopsis) in summer. This study shows that the number of arctic foxes varies greatly even in areas without fluctuating microtine rodents.     

Genotypic characterization of clarithromycin-resistant Helicobacter pylori strains

Helicobacterpylori (Hp) resistance to clarithromycin, one of the antibiotics most used to eradicate infection, is connected with the presence of a point mutation on the level of adenine at position 2143 or 2144 of 23S rRNA. AIM: The aim of the study is to evaluate of the presence of these mutation vs control clarithromycin resistant Hp strains present in North Sardinia; to verify the real association between the type of mutation and the resistance-level; to use easier molecular biology methods to quickly locate the resistance-associated mutations beginning with the bioptic material. The clarithromycin susceptibility of Hp isolates was tested by the E-test method (antibiotic assay). Genomic DNA of Hp strains was amplified using specific primers for the domain V. of ribosomic 23S rRNA and sequenced after the reaction with a primer within the fragment 23S. At the same time PCR-RFLP reliability was examined underlining the presence of these mutations with BsaI, BbsI, MboII restriction enzymes. Two mutations in 2143 (A- - G) and 2144 (A- - G) were found by domain V sequencing. The strains with mutation 2143 are characterized by a greater resistance level (MIC>64 g/ml) than those with mutation 2144 (MIC <64 g/ml). Restriction endonucleases BbsI and MboII recognise the site containing the mutation 2143 (A- - G), while BsaI recognise the mutation 2144 (A- - G). These methods might enable us to identify the presence of Hp directly from bioptic material and possible clarithromycin resistance and plan a suitable therapeutic strategy and consequently a better control of the infection.     

IAA-overproducer mutants of Hebeloma cylindrosporum Romagnesi mycorrhizal with Pinus pinaster (Ait.) Sol. and P. sylvestris L. in hydroponic culture

Indole-3-acetic acid (IAA) is thought to play a role in the regulation of ectomycorrhiza development, and vigorous mycorrhiza formers such as Pisolithus and Laccaria have previously been shown to accumulate large amounts of IAA in the culture medium in vitro, particularly in the presence of tryptophan. Recently, 5-fluoroindole-resistant and IAA-overproducing mutant strains of Hebeloma cylindrosporum Romagnesi have been developed and described by Durand et al. (1992). We have used some of these and corresponding wild-type strains as mycobionts on seedlings of Pinus pinaster (Ait.) Sol. and P. sylvestris L. in semi-hydroponic culture in an attempt to study IAA effects independent of species-specific differences. However, no significant differences between strains were found in host growth rate, shoot carbohydrate concentration, root morphology, root IAA concentration or mycorrhizal biomass. Since previous work showed a stimulation by these and other mutants and strains on mycorrhiza formation in Petri dish and test tube cultures, we assume that a semi-hydroponic culture system prevents the build up of tryptophan of fungal origin, which is most likely a precondition for enhanced IAA production.     

Application of a semi-automated SOS chromotest for measuring genotoxicities of complex environmental mixtures containing polycyclic aromatic hydrocarbons.

Soxhlet-extracted samples of standard reference materials (SRMs) 1649 (PAR1: urban dust/organics) and 1650 (PAR2: diesel particulate matter) from the U.S. Institute of Standards and Technology were tested for induction of SOS functions using a semi-automated version of the SOS chromotest with Escherichia coli PQ37. Concentrations of 10 polycyclic aromatic hydrocarbons in the extracts were determined using reversed-phase HPLC. Only the diesel particulate matter (PAR2) extracts expressed SOS induction activity, which decreased when metabolic activation was used. Mutagenic PAH compounds (e.g., chrysene) were found in higher concentrations in the PAR2 extracts than in the PAR1 extracts but this could not explain the genotoxicity while it was mainly exhibited without metabolic activation. The direct genotoxic activity of the diesel particulate matter sample PAR2 is probably caused by nitroaromatic compounds; this was also supported by parallel studies with the Ames/Salmonella assay.     

Phylogenetic position of a paramyxovirus from Atlantic salmon Salmo salar

A paramyxovirus has been isolated from Atlantic salmon Salmo salar suffering from epitheliocystis. This virus does not cause any mortality when used to challenge disease-free salmon, but has been associated with 2 cases of mortality in salmon farms in Norway. Atlantic salmon paramyxovirus (ASPV) has been suggested as a name for the virus. The ASP virus is a slow-growing virus in cell cultures (rainbow trout gill cells: RTgill-W1). Little is known about its importance and its phylogenetic position is uncertain. Hence, the need for a fast and sensitive diagnostic method for studying the prevalence of this virus in salmon farms and for more basic knowledge about its identity were the motivation for this study. A partial nucleotide sequence (816 bp) from the large protein (L protein) gene of the ASP virus has been sequenced from 2 different isolates. The putative amino acid sequence has been compared with the L protein of other paramyxoviruses. This sequence gives strong support to a relationship between the ASP virus and members of the subfamily Paramyxovirinae, genus Respirovirus.     

Effects of Diverse Environmental Conditions on φLC3 Prophage Stability in Lactococcus lactis

The effects of various growth conditions on spontaneous LC3 prophage induction in Lactococcus lactis subsp. cremoris IMN-C1814 was analyzed with a half fraction of a 4⁴ factorial experimental design. The four factors included in the study were nutrient availability, acidity, osmolarity, and temperature, each applied at four levels. These environmental factors are related to the fermentation processes in the dairy industry, in which bacteriophage attacks on sensitive starter strains are a constant threat to successful fermentation processes. The frequency of spontaneous LC3 induction was determined by quantitative analyses of restored DNA attachment sites (attB) on the bacterial chromosomes in a population of lysogenic cells. Statistical analysis revealed that all four environmental factors tested affected LC3 prophage stability and that the environmental factors were involved in interactions (interactions exist when the effect of one factor depends on the level of another factor). The spontaneous LC3 induction frequency varied from 0.08 to 1.76%. In general, the induction frequency remained at the same rate or decreased when level 1 to 3 of the four environmental factors was applied. At level 4, which generally gave the least favorable growth conditions, the induction frequency was either unchanged, decreased, or increased, depending on the type of stress. It appeared that the spontaneous induction frequency was independent of the growth behavior of the host. It was the environmental growth conditions that were the decisive factor in induction frequency.     

Use of RT-PCR for diagnosis of infectious salmon anaemia virus (ISAV) in carrier sea trout Salmo trutta after experimental infection

This paper describes a new bacterial white spot syndrome (BWSS) in cultured tiger shrimp Penaeus monodon. The affected shrimp showed white spots similar to those caused by white spot syndrome virus (WSSV), but the shrimp remained active and grew normally without significant mortalities. The study revealed no evidence of WSSV infection using electron microscopy, histopathology and nested polymerase chain reaction. Electron microscopy indicated bacteria associated with white spot formation, and with degeneration and discoloration of the cuticle as a result of erosion of the epicuticle and underlying cuticular layers. Grossly the white spots in BWSS and WSS look similar but showed different profiles under wet mount microscopy. The bacterial white spots were lichen-like, having perforated centers unlike the melanized dots in WSSV-induced white spots. Bacteriological examination showed that the dominant isolate in the lesions was Bacillus subtilis. The occurrence of BWSS may be associated with the regular use of probiotics containing B. subtilis in shrimp ponds. The externally induced white spot lesions were localized at the integumental tissues, i.e., cuticle and epidermis, and connective tissues. Damage to the deeper tissues was limited. The BWS lesions are non-fatal in the absence of other complications and are usually shed through molting.     

Prevalence of infectious salmon anaemia virus (ISAV) in wild salmonids in western Norway

Studies of infectious salmon anaemia virus (ISAV), an important pathogen of farmed salmon in Norway, Scotland, the Faeroe Islands, Ireland, Canada, the USA and Chile, suggest that natural reservoirs for this virus can be found on both sides of the North Atlantic. Based on existing information about ISAV it is believed to be maintained in wild populations of trout and salmon in Europe. It has further been suggested that ISAV is transmitted between wild hosts, mainly during their freshwater spawning phase in rivers, and that wild salmonids, mainly trout, are possible carriers of benign wild-type variants of ISAV. Change in virulence is probably a result of deletions of amino acid segments from the highly polymorphic region (HPR) of benign wild-type isolates after transmission to farmed salmon. Hence, it has been suggested that the frequency of new outbreaks of ISA in farmed salmon could partly reflect natural variation in the prevalence of ISAV in wild populations of salmonids. The aims of the present study were to screen for ISAV in wild salmonids during spawning in rivers and to determine the pathogenicity of resultant isolates from wild fish. Tissues from wild salmonids were screened by RT-PCR and real-time PCR. The prevalence of ISAV in wild trout Salmo trutta varied from 62 to 100% between tested rivers in 2001. The prevalence dropped in 2002, ranging from 13 to 36% in the same rivers and to only 6% in 2003. All ISAV were nonpathogenic when injected into disease-free Atlantic salmon, but were capable of propagation, as indicated by subsequent viral recovery. However, non-pathogenic ISAV has also been found in farmed salmon, where a prevalence as high as 60% has been registered, but with no mortalities occurring. Based on the results of the present and other studies, it must be concluded that vital information about the importance of wild and man-made reservoirs for the emergence of ISA in salmon farming is still lacking. This information can only be gained by further screening of possible reservoirs, combined with the development of a molecular tool for typing virulence and the geographical origin of the virus isolates.     

New subtype of salmonid alphavirus (SAV), Togaviridae, from Atlantic salmon Salmo salar and rainbow trout Oncorhynchus mykiss in Norway

In Europe, 2 closely related alphaviruses (Togaviridae) are regarded as the causative agents of sleeping disease (SD) and salmon pancreas disease (SPD): SD virus (SDV) has been isolated from rainbow trout Oncorhynchus mykiss in France and the UK, while SPD virus (SPDV) has been isolated from salmon Salmo salar in Ireland and the UK. Farmed salmonids in western Norway also suffer from a disease called pancreas disease (PD), and this disease is also believed to be caused by an alphavirus. However, this virus has not yet been characterised at the molecular level. We have cultured a Norwegian salmonid alphavirus from moribund fishes diagnosed with cardiac myopathy syndrome (CMS) and fishes diagnosed with PD. The virus has also been found in salmon suffering from haemorrhagic smolt syndrome in the fresh water phase. The genomic organisation of the Norwegian salmonid alphavirus is identical to that in SPDV and SDV, and the nucleotide sequence similarity to the other 2 alphaviruses is 91.6 and 92.9%, respectively. Based on the pathological changes, host species and the nucleotide sequence, we suggest naming this virus Norwegian salmonid alphavirus (NSAV). Together with SPDV and SDV it constitutes a third subtype of salmonid alphavirus (SAV) species within the genus Alphavirus, family Togaviridae.     

Cost of reproduction in a long-lived bird: incubation effort reduces immune function and future reproduction

Life-history theory predicts that increased current reproductive effort should lead to a fitness cost. This cost of reproduction may be observed as reduced survival or future reproduction, and may be caused by temporal suppression of immune function in stressed or hard-working individuals. In birds, consideration of the costs of incubating eggs has largely been neglected in favour of the costs of brood rearing. We manipulated incubation demand in two breeding seasons (2000 and 2001) in female common eiders (Somateria mollissima) by creating clutches of three and six eggs (natural range 3-6 eggs). The common eider is a long-lived sea-duck where females do not eat during the incubation period. Mass loss increased and immune function (lymphocyte levels and specific antibody response to the non-pathogenic antigens diphtheria and tetanus toxoid) was reduced in females incubating large clutches. The increased incubation effort among females assigned to large incubation demand did not lead to adverse effects on current reproduction or return rate in the next breeding season. However, large incubation demand resulted in long-term fitness costs through reduced fecundity the year after manipulation. Our data show that in eiders, a long-lived species, the cost of high incubation demand is paid in the currency of reduced future fecundity, possibly mediated by reduced immune function.