Growth variability in the late Vendian problematics <Emphasis Type="Italic">Parvancorina</Emphasis> Glaessner

Morphological and quantitative characteristics of the growth variability of two Parvancorina species were analyzed based on new abundant material from the Vendian of the White Sea. Growth variability in this problematic taxon appears to be wider than previously suggested. We found allometric growth in the White Sea population of P. minchami Glaessner, 1958, in contrast to isometric growth in Australian representatives of the species. Another White Sea species, P. sagitta Ivantsov, 2004, shows gradual formation of anchor-shaped structure in juveniles. Based on Australian material, it was previously believed that this structure did not change during ontogeny. These two distinctive features together with a strong variability of age-related measurements distinguish Parvancorina from other early arthropods (Scania, Primicaris), and cast doubt on the growth pattern as an argument in favor of the arthropodan nature of Parvancorina.     

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.     

Distribution and ecological relations among the alien crab, <Emphasis Type="Italic">Percnon gibbesi</Emphasis> (H. Milne-Edwards 1853) and autochthonous species,in and out of an SW Mediterranean MPA

The distribution of the allochthonous crab Percnon gibbesi and its relationships with other benthic invertebrate species was assessed inside the marine reserve of Cabo de Palos—Islas Hormigas (Mediterranean sea, Spain) and neighbouring non-protected sites. Although a significant spatial variability was detected at finer spatial scale, there was no influence of protection measures or insularity on the abundance of P. gibbesi. The presence of small holes, encrusting algae and low slope favour the colonization success of this crustacean, and the spatial distribution of these habitat features could explain the observed pattern. The abundance of P. gibbesi was similar to that of native crab species; however, a non-significant negative relationship between the abundance of P. gibbesi and native crabs (Pachygrapsus marmoratus and Eriphia verrucosa), urchins (Arbacia lixula and Paracentrotus lividus) and a snail (Phorcus turbinatus) was observed. This work highlights the importance of monitoring alien crab population densities taking structural habitat and other potentially influential factors into account and the likely effect of this alien species on the native ones.     

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.     

Intrapopulation heterogeneity of the fluorescence parameters of the marine plankton alga <Emphasis Type="Italic">Thalassiosira weissflogii</Emphasis> at various nitrogen levels

Fluorescence of the marine alga Thalassiosira weissflogii (Grunow) Fryxell et Hasle with open (F _o ) and closed (F _m ) reaction centers of photosystem 2 (PS 2) and its relative variable fluorescence (F _v/F _m ) were measured at various levels of inorganic nitrogen. A significant heterogeneity of the population in terms of these parameters was revealed. Some cells within the population were more sensitive to nitrogen deficiency, and their photosynthetic apparatus was disrupted to a greater extent. The cells within a population also differed in terms of their ability to recover after incubation at low nitrogen levels. Enhancement of nitrogen deficiency resulted in an increase in the variability of the F _o and F _v/F _m values of the cells. Fluorescence variability decreased at a less pronounced deficiency. Fluorescence variability should be taken into consideration in the studies concerning responses of algae to changes in nutrient contents.     

The influence of upwelling,coastal currents and water temperature on the distribution of the red tide dinoflagellate, <Emphasis Type="Italic">Noctiluca scintillans</Emphasis>, along the east coast of Australia

Quasi-synoptic surveys along the east coast of Australia between 28 and 34°S show that the heterotrophic dinoflagellate, Noctiluca scintillans, occurs along this entire stretch of the coast. Areas of relatively high abundance of Noctiluca were observed downstream of regions predisposed to current-induced upwellings as a consequence of alongshore topographic variations. High-resolution temporal and spatial sampling of upwelling events showed that Noctiluca was abundant (up to 28 cells l^?1) within mature upwelled waters. A high proportion (>80%) of fed Noctiluca cells (cells with prey in their vacuoles) was observed in the mature upwelled waters indicating that the observed increase in abundance of Noctiluca was associated with increased feeding activity. The absolute abundance of Noctiluca in upwelled waters was, however, found to vary from one upwelling location to another and between seasons. In particular, highest abundances of Noctiluca were recorded south of 31.5°S, where the East Australian Current (EAC) characteristically separates from the coast. The high abundances partly arise from southward advection and retention of the Noctiluca cells, and partly from upwelling inshore of the separated EAC driven by cross-shelf boundary layer fluxes. The temperature of the EAC was also found to influence absolute abundances. Surface water temperatures during our summer cruise were anomalously high due to a strong La Niña phase, and up to 4°C warmer than during our spring cruise. We found that the warmer surface water temperatures were associated with relatively lower average abundances of Noctiluca in the near shore zone.     

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.     

Spatial distribution of algae in the <Emphasis Type="Italic">Ahnfeltia tobuchiensis</Emphasis> bed in Amursky Bay (Sea of Japan)

Horizontal and vertical distribution of algae in Ahnfeltia tobuchiensis beds was studied in the area of Mt. Stolovaya in Amursky Bay, Sea of Japan. Thirty-four species of macroalgae (2 species of Chlorophyta, 26 Rhodophyta, and 6 Ochrophyta) were found in the area of study. Two fields of the unattached alga Ahnfeltia were located opposite Mt. Stolovaya; they differed in area, macrophyte stock, number and biomass of attendant species, hydrochemical and light conditions. A monodominant Ahnfeltia tobuchiensis community formed in the southern field and a bidominant community of Ahnfeltia tobuchiensis + Ahnfeltiopsis flabelliformis developed in the northern field. It is suggested that the horizontal distribution of common macrophyte species in the Ahnfeltia beds at Mt. Stolovaya is conditioned by the amount of photosynthetically active radiation (PAR) reaching the surface of the algal bed. Differences in tolerance of Ahnfeltia and attendant species to shadowing and in light conditions across the alga stratum define the vertical distribution of algae within the bed. Chondrus armatus and Ptilota filicina were found mainly in the upper layer of the algal bed. A. tobuchiensis, A. flabelliformis, Chaetomorpha linum, and Coccotylus orientalis extended across the entire thickness of the bed.     

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.     

No effect of round goby <Emphasis Type="Italic">Neogobius melanostomus</Emphasis> colonisation on young-of-the-year fish density or microhabitat use

The round goby Neogobius melanostomus has recently invaded several major freshwater systems in Europe and North America. Despite numerous studies predicting an impact on native fish assemblages, few have attempted to demonstrate it. In this case study, we monitored the effect of N. melanostomus colonisation on abundance and habitat utilisation of both young-of-the-year (YOY) native fish and YOY western tubenose goby Proterorhinus semilunaris in a typical, medium-sized European river. Colonisation by N. melanostomus had no apparent effect on either native fish abundance and species richness or P. semilunaris abundance. Moreover, after colonisation, both native fish and P. semilunaris occupied similar niches (i.e. microhabitats) to those occupied before colonisation. While niche use of YOY N. melanostomus and P. semilunaris overlapped significantly, YOY native fish utilised different habitats from the gobiids. We suggest that N. melanostomus did not compete for resources with YOY fish in our study area due to lack of niche overlap and/or surplus resources. As N. melanostomus rapidly dominated the fish assemblage at our site, we further suggest that utilisation of an empty niche, rather than competitive superiority, was the main factor facilitating its success.     

Effects of macrophyte leachate on <Emphasis Type="Italic">Anabaena</Emphasis> sp. and <Emphasis Type="Italic">Chlamydomonas moewusii</Emphasis> growth in freshwater tropical ecosystems

This study reports on the effects of dissolved organic matter (DOM) derived from the aquatic macrophyte Pistia stratiotes (collected from a tropical reservoir) on the mixotrophic growth of two phytoplankton species (Chlamydomonas moewusii and Anabaena sp.). The DOM from P. stratiotes had a mainly aliphatic structure, low molecular weight, low cellulose and lignin content and high carbon content. The addition of DOM (5% v/v) significantly decreased the growth rate of Anabaena sp. but increased the chlorophyll a concentration of C. moewusii. Higher light intensity (100 versus 30 µmol m^?2 s^?1) was important for Anabaena sp., increasing its growth rate and chlorophyll content. The use of DOM from P. stratiotes to mitigate cyanobacterial blooms should be further explored in future studies.     

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.     

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.     

The search for proteins involved in the formation of crustacean cuticular structures

Summer ichthyoplankton surveys were conducted in the northern Gulf of Mexico from 2007 to 2010 to characterize the distribution and abundance of tuna larvae. Larval assemblages of tunas were comprised of four genera: Thunnus, Auxis, Euthynnus, and Katsuwonus. Thunnus were the most abundant and four species were detected; T. atlanticus [blackfin tuna], T. obesus [bigeye tuna], T. albacares [yellowfin tuna], and T. thynnus [bluefin tuna]. Intra- and inter-annual variability in the distribution and abundance of Thunnus species were observed with higher densities in 2008 and 2009, with a decline in abundance observed in 2010. Distribution and abundance of Thunnus larvae were influenced by physical and chemical conditions of the water mass, notably sea surface temperature and salinity. Distinct species-specific habitat preferences were observed and the location of mesoscale oceanographic features influenced larval abundance with higher densities of T. atlanticus, T. obesus, and T. albacares near anticyclonic (warm core) regions and the Loop Current, while T. thynnus was observed in higher densities near cyclonic (cold core) regions. This study demonstrates that spatial and temporal variability in the location of mesoscale oceanographic features may be important to partitioning nursery habitat among Thunnus species.     

Phenotypic and Genetic Diversity of Local <Emphasis Type="Italic">Perilla</Emphasis> (<Emphasis Type="Italic">Perilla frutescens</Emphasis> (L.) Britt.) from Northern Thailand

Phenotypic and Genetic Diversity of Local Perilla ( Perilla frutescens (L.) Britt.) from Northern Thailand. Perilla frutescens (L.) Britt., an important oil and culinary crop in Asia, is a valuable genetic resource. Despite its nutritional value and historic and cultural importance, research on Perilla has been scarce, particularly as far as its genetic diversity is concerned. The aims of the present study were to assess variability within and between 29 seed samples of P. frutescens collected from farmers in northern Thailand, and evaluation conducted of their genetic, morphological, and agronomic characteristics, and the seed composition, including polyunsaturated fatty acids omega-3, omega-6, and omega-9, and the vitamin E γ-tocopherols. Perilla frutescens (L.) Britt. of northern Thailand is genetically variable, and structured according to origin of collection which was the consequence of local adaptation. The discovery of high levels of polyunsaturated fatty acids, namely α-linolenic acid and γ-tocopherols, in some Perilla samples indicates the potential for utilizing Perilla for its high omega-3 content including as a vitamin E supplement for humans, a prospect that should be taken into account when planning conservation strategies or when Perilla variability is used in breeding programs.     

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.     

Seasonal variations in moisture use in a piñon–juniper woodland

In water-limited environments of the intermountain region of North America, summer precipitation may play a role in the structure and function of aridland communities and ecosystems. This study examined the potential reliance on summer precipitation of two widespread, coexisting woody species in the southwestern United States, Pinus edulis Englmn. (Colorado piñon) and Juniperus osteosperma (Torr) Little (Utah juniper). The current distributions of P. edulis and J. osteosperma are highly suggestive of different dependencies on summer rainfall. We hypothesized that P. edulis was dependent on summer precipitation, utilizing summer precipitation even during extremely dry summers, whereas J. osteosperma was not dependent, using summer precipitation only when amounts were above some minimum threshold. Using sap flux and stable isotopic methods to assess seasonal water sources and water use efficiency, we examined the response of these two species to seasonal variations in moisture at a site located near the northern limits of the North American monsoon. Both sap flux and isotopic results indicated that P. edulis was responsive to summer rain, while J. osteosperma was not. Following summer rain events, sap flux density increased in P. edulis for several days, but not in J. osteosperma. Isotopic evidence indicated that P. edulis took up summer-derived moisture to a greater extent than J. osteosperma. Values of the natural abundance stable isotope ratio of carbon of leaf soluble carbohydrates increased over the summer for P. edulis, indicative of assimilation at higher water use efficiency, but were invariant for J. osteosperma. Our results supported the hypothesis that P. edulis and J. osteosperma are differentially sensitive to summer precipitation and are discussed in the light of potential changes in the seasonality of precipitation associated with climate change.