Geographic and temporal genetic structure in <Emphasis Type="Italic">Lepeophtheirus salmonis</Emphasis> from four salmon farms along the northwest and west coasts of Ireland: results from a microsatellite analysis

The marine ectoparasitic copepod of salmonids, Lepeophtheirus salmonis (Krøyer), is a major pest of farmed Atlantic salmon (Salmo salar L.) causing great economic impact. The spatial scales over which L. salmonis populations in different salmon farms are typically connected, and the temporal scales over which L. salmonis from the same farm typically undergo genetic change are largely unknown. These questions were posed in a small-scale geographic study of population structure in L. salmonis from four salmon farms, along the northwest and west coasts of Ireland, using two outgroups from Norway and Canada. The temporal stability of genetic composition was also studied in samples collected quarterly during one year from one salmon farm in Ireland. Genetic composition in L. salmonis was characterised using four nuclear microsatellites. Significant but low genetic differentiation was observed between all sites (F _ST = 0.08), with no evidence that differentiation was correlated with geographic distance. Temporal genetic differentiation was also evident (F _ST = 0.07). An analysis of all L. salmonis samples except the ones from Norway detected two separate clusters. Each cluster contained both geographical and temporal samples. These results are consistent with a population model in which L. salmonis in salmon farms along the northwest and west coasts of Ireland are not isolated, but are potentially subject to (i) localised ecological factors at the particular farm sites or (ii) selection post-settlement or a combination thereof.     

Search for genes influencing the maintenance of the [<Emphasis Type="Italic">ISP</Emphasis><Superscript>+</Superscript>] prion-like antisuppressor determinant in yeast with the use of an insertion gene library

The prion-like determinant [ISP ⁺] manifests itself as an antisuppressor of certain sup35 mutations. To establish that [ISP ⁺] is indeed a new yeast prion, it is necessary to identify the gene that codes for the protein whose prion form is [ISP ⁺]. Analysis of the transformants obtained by transformation of an [ISP ⁺] strain with an insertion gene library revealed three genes controlling the [ISP ⁺] maintenance: UPF1, UPF2, and SFP1. SFP1 codes for a potentially prionogenic protein, which is enriched in Asn and Gln residues, and is thereby the most likely candidate for the [ISP ⁺] structural gene. UPF1 and UPF2 code for components of nonsense-mediated mRNA decay. The [ISP ⁺] elimination caused by UPF1 and UPF2 inactivation was reversible, and Upf1p and Upf2p were not functionally related to phosphatase Ppz1p, which influences the [ISP ⁺] manifestation. Possible mechanisms sustaining the influence of UPF1 and UPF2 on [ISP ⁺] maintenance are discussed.     

Construction of flavocytochrome <Emphasis Type="Italic">b</Emphasis><Subscript>2</Subscript>-overproducing strains of the thermotolerant methylotrophic yeast <Emphasis Type="Italic">Hansenula polymorpha</Emphasis> (<Emphasis Type="Italic">Pichia angusta</Emphasis>)

L-Lactate cytochrome c oxidoreductase (flavocytochrome b ₂, FC b ₂) from the thermotolerant methylotrophic yeast Hansenula polymorpha (Pichia angusta) is, unlike the enzyme form baker’s yeast, a thermostable enzyme potentially important for bioanalytical technologies for highly selective assays of L-lactate in biological fluids and foods. This paper describes the construction of flavocytochrome b ₂ producers with over-expression of the H. polymorpha CYB2 gene, encoding FC b ₂. The HpCYB2 gene under the control of the strong H. polymorpha alcohol oxidase promoter in a plasmid for multicopy integration was transformed into the recipient strain H. polymorpha C-105 (grc1 catX), impaired in glucose repression and devoid of catalase activity. A method was developed for preliminary screening of the transformants with increased FC b ₂ activity in permeabilized yeast cells. The optimal cultivation conditions providing for the maximal yield of the target enzyme were found. The constructed strain is a promising FC b ₂ producer characterized by a sixfold increased (to 3 μmol min^?1 mg^?1 protein in cell-free extract) activity of the enzyme.     

Thermotolerance and place memory in adult <Emphasis Type="Italic">Drosophila</Emphasis> are independent of natural variation at the <Emphasis Type="Italic">foraging</Emphasis> locus

Natural polymorphisms at the foraging (for) gene influence several behaviors. However, it is seldom clear how different for alleles could be selected. In one case, Drosophila with the rover allele (for ^r ) have higher locomotor activity in the presence of food than animals with the sitter allele (for ^s ), suggesting a complementary feeding strategy. There are, in addition, differences between for ^r and for ^s Drosophila in some tests of short-term memory (for ^r animals generally perform at higher levels) and thermotolerance (for ^s larvae are more resistant to the effects of high-temperature). We asked whether there could be a direct compensating advantages in adult for ^s flies that could maintain the natural for variants. First, are adult for ^s flies more thermotolerant? Second, do for ^r flies have a higher short-term place memory? Third, as an alternative, might for ^s flies have higher place memory? Our results do not confirm these possibilities. Thus, a thermotolerance advantage of for ^s flies does not compensate for a potential for ^r short-term memory advantage; for ^r flies do not have a universal advantage in short-term memory; and for ^s flies do not have an advantage in place memory that could compensate for for ^r advantages in other learning contexts.     

Regulatory activity of heterologous gene-activator <Emphasis Type="Italic">xlnR</Emphasis> of <Emphasis Type="Italic">Aspergillus niger</Emphasis> in <Emphasis Type="Italic">Penicillium canescens</Emphasis>

The gene encoding the xlnR xylanolytic activator of the heterologous fungus Aspergillus niger was incorporated into the Penicillium canescens genome. Integration of the xlnR gene resulted in the increase in a number of activities, i.e. endoxylanase, β-xylosidase, α-L-arabinofuranosidase, α-galactosidase, and feruloyl esterase, compared to the host P. canescens PCA 10 strain, while β-galactosidase, β-glucosidase, endoglucanase, and CMCase activities remained constant. Two different expression constructs were developed. The first consisted of the nucleotide sequence containing the mature P. canescens phytase gene under control of the axhA promoter region gene encoding A. niger (1,4)-β-D-arabinoxylan-arabinofuranohydrolase. The second construct combined the P. canescens phytase gene and the bgaS promoter region encoding homologous β-galactosidase. Both expression cassettes were transformed into P. canescens host strain containing xlnR. Phytase synthesis was observed only for strains with the bgaS promoter on arabinose-containing culture media. In conclusion, the bgaS and axhA promoters were regulated by different inducers and activators in the P. canescens strain containing a structural tandem of the axhA promoter and the gene of the xlnR xylanolytic activator.     

Influence of aperiodic summer droughts on leaf litter breakdown and macroinvertebrate assemblages: testing the <Emphasis Type="Italic">drying memory</Emphasis> in a Central Apennines River (Aterno River,Italy)

Management of multiple exploited stocks of anadromous salmonids in large catchments requires understanding of movement and catchment use by the migrating fish and of their harvesting. The spawning migration of sea trout (Salmo trutta) and Atlantic salmon (Salmo salar) was studied in the River Tweed, UK, using acoustic telemetry to complement exploitation rate data and to quantify catchment penetration. Salmon (n = 79) and sea trout (n = 65) were tagged in the tidal-influenced Tweed in summer–autumn. No tagged salmon left the river before spawning, but 3% (2010) and 8% (2011) of pre-spawning sea trout dropped out. Combined tag regurgitation/fish mortality in salmon was 12.5%, while trout mortality was 6% (2010) and 0% (2011). The estimated spawning positions of salmon and sea trout differed; tagged salmon were mostly in the main channel while trout occurred mostly in the upper Tweed and tributaries. Early fish migrated upstream slower than later fish, but sea trout moved through the lower-middle river more quickly than salmon, partly supporting the hypothesis that the lower exploitation rate in autumn of trout (1 vs 3.3% for salmon) there is generated by differences in migration behaviour.     

Effect of excretory-secretory products of some fouling organisms on settling and metamorphosis of the larvae of <Emphasis Type="Italic">Styela rustica</Emphasis> (Ascidiae)

The effect of the excretory-secretory products of some fouling animals on the settling and metamorphosis of larvae of the solitary ascidian Styela rustica was assessed. The substances secreted by the sponge Halichondria panicea stimulated settling of larvae, but concurrently blocked their metamorphosis. The excretory-secretory products of the mussel Mytilus edulis and the ascidian Molgula citrine did not affect settling of the S. rustica larvae but impeded their subsequent development. Water conditioned by the bivalve Hiatella arctica, stimulated settling and, apparently, metamorphosis of the larvae of S. rustica. The chemical substances produced by adult individuals of S. rustica facilitated settling of conspecific larvae but slightly delayed their metamorphosis.     

Photosynthetic activity and components of the electron transport chain in the aerobic bacteriochlorophyll <Emphasis Type="Italic">a</Emphasis>-containing bacterium <Emphasis Type="Italic">Roseinatronobacter thiooxidans</Emphasis>

Bioenergetics of the aerobic bacteriochlorophyll a-containing (BCl a) bacterium (ABC bacterium) Roseinatronobacter thiooxidans is a combination of photosynthesis, oxygen respiration, and oxidation of sulfur compounds under alkaliphilic conditions. The photosynthetic activity of Rna. thiooxidans cells was established by the photoinhibition of cell respiration and reversible photobleaching discoloration of the BCl a of reaction centers (RC), connected by the chain of electron transfer with cytochrome c ₅₅₁ oxidation. The species under study, like many purple bacteria and some of the known ABC bacteria, possesses a light-harvesting pigment-protein (LHI) complex with the average number of 30 molecules of antenna BCl a per one photosynthetic RC. Under microaerobic growth conditions, the cells contained bc ₁ complex and two terminal oxidases: cbb ₃-cytochrome oxidase and the alternative cytochrome oxidase of the a ₃ type. Besides, Rna. thiooxidans was shown to have several different soluble low- and high-potential cytochromes c, probably associated with the ability of utilizing sulfur compounds as additional electron donors.     

<Emphasis Type="Italic">Malassezia</Emphasis> spp. in Acoustic Meatus of Bats (<Emphasis Type="Italic">Molossus molossus</Emphasis>) of the Amazon Region,Brazil

The yeasts of the Malassezia genus are opportunistic microorganisms and can cause human and animal infections. They are commonly isolated from the skin and auricular canal of mammalians, mainly dogs and cats. The present study was aimed to isolate Malassezia spp. from the acoustic meatus of bats (Molossus molossus) in the Montenegro region, “Rondônia”, Brazil. From a total of 30 bats studied Malassezia spp. were isolated in 24 (80%) animals, the breakdown by species being as follows (one Malassezia sp. per bat, N = 24): 15 (62.5%) M. pachydermatis, 5 (20.8%) M. furfur, 3 (12.5%) M. globosa and 1 (4.2%) M. sympodialis. This study establishes a new host and anatomic place for Malassezia spp., as it presents the first report ever of the isolation of this genus of yeasts in the acoustic meatus of bats.     

Polymorphism of <Emphasis Type="Italic">yellow</Emphasis> locus in <Emphasis Type="Italic">Drosophila melanogaster</Emphasis> mutants from natural populations

We have studied the molecular characteristics of the yellow locus (y; 1–0.0), which determines the body color of phenotypically wild-type and mutant alleles isolated in different years from geographically distant populations of Drosophila melanogaster. According to the Southern blot, data restriction maps of the yellow locus of all examined strains differ from one another, as well as from Oregon stock. FISH analysis shows that, in the neighborhood of the yellow locus in the X chromosome, neither P nor hobo elements are found in y^1–775 stock, while only hobo is found in these region in y^1–859 and y^1–866 stocks, only the P element is found in y⁺sn⁸⁴⁹ stock, and both elements are found in y^1–719 stock. Thus, all yellow mutants studied are of independent origin. Locus yellow located on the end of X chromosome (region 1A5–8 on the cytologic map) carries significantly more transposon than retrotransposon induced mutations compared to the white locus (region 3C2). It is possible that, at the ends of Drosophila melanogaster chromosomes, transposons are more active than retrotransposons.     

Chromosomal differentiation of the sibling species <Emphasis Type="Italic">Pichia membranifaciens</Emphasis> and <Emphasis Type="Italic">Pichia manshurica</Emphasis>

The molecular karyotyping analysis of 21 strains within the taxonomic complex Pichia membranifaciens allowed the sibling species P. membranifaciens and P. manshurica, as well as P. deserticola and P. punctispora, to be differentiated. Heterogeneity of the species P. membranifaciens at the variety level is discussed.     

Development and relations of <Emphasis Type="Italic">Fusarium culmorum</Emphasis> and <Emphasis Type="Italic">Pseudomonas fluorescens</Emphasis> in soil

The development of Fusarium culmorum and Pseudomonas fluorescens in soil, and the relations between them, were studied using membrane filters containing the fungus, the bacterium, or both microorganisms; the filters were incubated in soil. F. culmorum was identified by indirect immunofluorescence; the GUS-labeled strain was used to visualize P. fluorescens. It was found that F. culmorum introduced in soil can develop as a saprotroph, with the formation of mycelium, macroconidia, and a small amount of chlamydospores. Introduction of glucose and cellulose resulted in increased density of the F. culmorum mycelium and macroconidia. P. fluorescens suppressed the development of the F. culmorum mycelium in soil, but stimulated chlamydospore formation. Decreased mycelial density in the presence of P. fluorescens was more pronounced in soil without additions and less pronounced in the case of introduction of glucose or cellulose. F. culmorum had no effect on P. fluorescens growth in soil.     

Cloning of <Emphasis Type="Italic">rec</Emphasis>A gene of <Emphasis Type="Italic">Corynebacterium glutamicum</Emphasis> and phenotypic complementation of <Emphasis Type="Italic">Escherichia coli</Emphasis> recombinant deficient strain

Nucleotide and amino acid sequences of Corynebacterium glutamicum recA genes, from GenBank, were compared in silico. On the basis of the identity found between sequences, two degenerate primers were designed on the two sides of the deduced open reading frame (ORF) of the recA gene. PCR experiments, for amplifying the recA ORF region, were done. pGEM^®-T Easy vector was selected to be used for cloning PCR products. Then recA ORF was placed under the control of Escherichia coli hybrid trc promoter, in pKK388-1 vector. pKK388-1 vector, containing recA ORF, was transformed to E. coli DH5α ΔrecA (recombinant deficient strain), in an attempt to phenotypically complement it. Ultraviolet (u.v.) exposure experiments of the transformed and non-transformed E. coli DH5α ΔrecA cells revealed tolerance of transformed cells up to dose 0.24 J/cm², while non-transformed cells tolerated only up to dose 0.08 J/cm². It is concluded that phenotypic complementation of E. coli DH5α ΔrecA with recA ORF of C. glutamicum, could be achieved and RecA activity could be restored.     

Interactions of Algae within the Community of <Emphasis Type="Italic">Gracilaria gracilis</Emphasis> (Rhodophyta)

Interactions among the unattached red alga Gracilaria gracilis, the dominant species of an algal community, and associated algal species Chaetomorpha linum, Enteromorpha prolifera f. prolifera, and Polysiphonia sp. were studied during and after an algal bloom. It was shown that during their bloom the associated algae Enteromorpha and Polysiphonia sp. significantly decreased the photosynthetic rate of G. gracilis but did not affect its growth rate. It is suggested that the inhibition of Gracilaria gracilis photosynthesis is connected to the impact of extracellular metabolites excreted by Chaetomorpha linum, Enteromorpha prolifera f. prolifera, and Polysiphonia sp. In laboratory experiments, the photosynthetic rate of the associated species was enhanced in the presence of Gracilaria. However, no significant alterations were observed in the content of chlorophyll a, growth, and the dark respiration rates of associated algae when they were kept together with Gracilaria. It was suggested that allelopathic interactions observed among algal species during the formation of the monospecific Gracilaria community, as well as during algal blooms, are not determinative.     

Cytochromes <Emphasis Type="Italic">c</Emphasis> of the anaerobic methacrylate reducer <Emphasis Type="Italic">Geobacter sulfurreducens</Emphasis> AM-1

Cytochromes c were found in the cells of the bacterium Geobacter sulfurreducens AM-1 grown on acetate and methacrylate. The periplasmic extract of G. sulfurreducens AM-1 contained about 88% of the total content of cytochromes c of intact cells. The analysis of cytochromes c from the native cells of G. sulfurreducens AM-1, from the periplasmic extract and from the cells treated by an alkaline solution showed the presence of nine proteins containing heme c. The molecular masses of cytochromes c from G. sulfurreducens AM-1 were 12.5, 15.5, 25.7, 29.5, 34.7, 41.7, 50.1, 63.1, and 67.6 kDa; localization of each cytochrome c was determined. Three heme-containing proteins (15.5 kDa, 25.7 kDa, and 29.5 kDa with the most intensive staining) were present mainly in the periplasm of the bacterium. The other two (50.1 and 67.6 kDa) were supposedly localized in the cell membrane. Cytochromes c with the molecular masses of 12.5, 15.5, and 67.6 kDa are considered as possible components of the methacrylate redox system of G. sulfurreducens AM-1.