Hydrolytic activity of symbiotic microflora enzymes in pike (<Emphasis Type="Italic">Esox lucius</Emphasis> L.) intestines

This study has revealed the existence of microflora which is, to different degrees, associated with the intestinal mucosa of pike. A total of 82 bacterial strains have been isolated. These microorganisms produce enzymes that hydrolyze the major food substrates (proteins and carbohydrates). These enzymes are produced by the pool of various microorganisms living in the intestines, as well as by separate strains isolated in pure cultures. These strains produce enzymes with different levels of activity. Most of the isolated strains (68%) produce proteases. The calculated values of the C/P factor (the ratio of carbohydrase to protease activity) indirectly testify to the autochthonous nature of the microflora associated with the intestinal mucosa of pike. Presumably, the contribution that the microflora enzymes make to the enzymatic activity of the pike intestine is substantial, but it is difficult to estimate now.     

Turbidity decreases anti-predator behaviour in pike larvae, <Emphasis Type="Italic">Esox lucius</Emphasis>

Synopsis We tested how algal turbidity and light conditions influence anti-predator behaviour of first-feeding pike. Results showed that pike larvae were able to detect the predator by both chemical and visual signals in turbid water. However, the anti-predator behaviour was reduced in turbid water compared with clear water. Larvae hid in the vegetation in the presence of predator cues more in clear water than in turbid water. The attack rate on zooplankton in clear water was lower in the presence of predator cues, whereas no such difference was detected in turbid water. Both of these results indicate that turbidity acted as a refuge for larvae. Light proved to be an important regulating factor for feeding pike in the absence of predators, demonstrated as lowered attack rates in 50 light level in both clear and turbid water. This indicates that long-term turbidity may be critical for small larvae, which need to feed continuously to survive.     

Spawning population characteristics of pike <Emphasis Type="Italic">Esox lucius</Emphasis> L. in Lake Rubikiai (Lithuania)

The aim of the study was to describe the peculiarities of pike spawning in mesotrophic Lake Rubikiai, to determine the spawning population structure and evaluate the influence of some environmental factors on year-class strength formation. The data were collected in April and May (1994–2011). A total of 1586 individuals were caught. The age of pike ranged from 1 to 12 years; 2–5-yearold males (96.0%) and 3–8-year-old females (89.1%) prevailed. The overall sex ratio of females to males was 1:4.1. One-year-old spawning males (26.5–28.5 cm) and two-year-old spawning females (31.5–35.5 cm) constituted 2.1% and 2.6%, respectively. Water temperature during the spawning period was relatively stable, between 4 and 6°C, during March and increased slightly towards 10°C in the middle of April. No correlation was observed between female length and spawning date. Year-class strength did not correlate with the last day of ice presence and the minimal water level at the end of spawning (WL_min), but statistically significantly negatively correlated with the maximum water level at the beginning of spawning (WL_max) and the difference between WL_max and WL_min. The mean annual survival rate for pike (aged ≥2) was 0.74 and the mean annual instantaneous mortality rate was 0.45.     

The impact of catch-and-release angling on short-term behaviour and habitat choice of northern pike (<Emphasis Type="Italic">Esox lucius</Emphasis> L<Emphasis Type="Italic">.</Emphasis>)

In the northern hemisphere, pike (Esox lucius Linnaeus) is one of the most important recreational fisheries resources, and regulatory or voluntary catch-and-release angling is common. No information is available about the potential sublethal impacts on pike that catch-and-release fishing may cause, such as behavioural alterations and changes in habitat choice after release. Radio telemetry with N = 20 pike was used to test the hypothesis that fish modify behaviour by reducing movement as a reaction to a catch-and-release event in a previously unfished, slightly eutrophic lake, having an area of 25 ha and located in northeastern Germany. During a 7-month tracking period, activity of pike was monitored for consecutive 24 h every week. Minimum displacement per hour (m) and distance to shore (m) were significantly lower upon the first post release tracking compared to tracking before the capture. Two tracking events after capture, both movement and distance to shore were similar to those measured during pre-angling. There were no significant relations between the change in movement and distance to shore and size of pike. In terms of habitat choice, pike significantly selected for reed and avoided the pelagic area over the whole study period that was not influenced by catch-and-release angling. The results indicated that catch-and-release induces short-term behavioural alterations in pike, probably explained by physiological disturbances and facilitated by evolved anti-predation behaviours. Such alterations, however, seem to be of short duration and reversible suggesting sublethal catch-and-release impacts on pike behaviour are limited. Guest editors: J. M. Farrell, C. Skov, M. Mingelbier, T. Margenau & J. E. Cooper International Pike Symposium: Merging Knowledge of Ecology, Biology, and Management for a Circumpolar Species     

Taxonomic characteristics and physiological properties of microorganisms from the gut of pike (<Emphasis Type="Italic">Esox lucius</Emphasis>)

The taxonomic composition and distribution of microorganisms differing in the degree of association with the intestinal mucosa of the pike (Esox lucius) has been studied. Microorgansism of the families Enterobacteriaceae, Aeromonadaceae, and Vibrionaceae dominate in the gut microflora. Numerically prevailing bacterial species are characterized by high proteolytic and amylolytic enzyme activities as well as by high persistence accounted for by antilysozyme and antihistone activities. The results of this study show that Hafnia alvei, Yersinia ruckeri, Vibrio vulnificus, V. furnissii, Aeromonas salmonicida, and Shewanella putrefaciens may be regarded as normal components of the pike gut microflora.     

Potential effects of spawning habitat changes on the segregation of northern pike (<Emphasis Type="Italic">Esox lucius</Emphasis>) and muskellunge (<Emphasis Type="Italic">E</Emphasis>. <Emphasis Type="Italic">masquinongy</Emphasis>) in the Upper St. Lawrence River

Changes in spawning habitat of northern pike (Esox lucius) may affect their segregation from and coexistence with the closely related muskellunge (E. masquinongy). We estimated the areal coverage of robust and shallow emergent vegetation in three shared-spawning bays in the Upper St. Lawrence River from aerial photographs taken from 1948 to 2003. Robust emergent vegetation (e.g., cattail) increased in coverage by 155–241% while shallow emergents (sedges) decreased by 46–96%. The loss of sedges, an important northern pike-spawning habitat, may facilitate greater spawning overlap in offshore-submersed aquatic vegetation within bay habitats used by muskellunge. Development rates and characteristics of northern pike and muskellunge eggs and larvae were compared to better understand the implications of greater spawning overlap. Northern pike eggs developed faster than muskellunge eggs at temperatures of 4.7–19°C, and adhesive eggs and the presence of adhesive papillae were present in both species. Equations were used to predict degree-day requirements for hatching and swim-up in three habitats (shallow emergents, bay, and offshore shoal) along a temperature gradient. Northern pike required more estimated degree days to reach hatching in bay and offshore shoal habitat relative to shallow emergent habitat due to cooler temperatures. Significant spawning overlap is known to occur within bay habitats, but poor success of northern pike in deep bay habitats and overall reductions in abundance are hypothesized to currently buffer muskellunge from potential negative interactions between these species. Guest editors: J. M. Farrell, C. Skov, M. Mingelbier, T. Margenau & J. E. Cooper International Pike Symposium: Merging Knowledge of Ecology, Biology, and Management for a Circumpolar Species     

Age-dependent accumulation of <Superscript>137</Superscript>Cs by pike <Emphasis Type="Italic">Esox lucius</Emphasis> in the Yenisei River

Age-dependent accumulation of ¹³⁷Cs in the muscles and bodies of the pike Esox lucius (aged two to seven years) inhabiting a section of the Yenisei River polluted with artificial radionuclides has been studied. The content of ¹³⁷Cs in muscles varied from 0.5 to 7.0 Bq/kg of fresh weight. The maximum content of the radionuclide has been found in juveniles. The content of ¹³⁷Cs in pike muscles and body decreased considerably with age. The high content of ¹³⁷Cs in the muscles of juveniles is probably a consequence of their higher intensity of feeding as compared to older individuals, which is due to the intense growth of juveniles.     

New combinations and typifications in <Emphasis Type="Italic">Bistorta</Emphasis>, <Emphasis Type="Italic">Persicaria</Emphasis>, <Emphasis Type="Italic">Polygonum,</Emphasis> and <Emphasis Type="Italic">Rumex</Emphasis> (Polygonaceae)

New combinations are proposed in anticipation of the Polygonaceae treatment in the forthcoming volume of Intermountain Flora: Polygonum kelloggii var. esotericum, P. kelloggii var. watsonii , Rumex densiflorus var. pycnanthus , R. salicifolius var. utahensis, and R. occidentalis var. tomentellus. Typifications are proposed to facilitate ongoing studies in Polygonaceae and to maintain current usage.     

Growth and feeding of juvenile pike <Emphasis Type="Italic">Esox lucius</Emphasis> (Esocidae) of different hatching dates during its first months of life

Groups of fingerlings of the pike Esox lucius, that hatched from the eggs of the same female at the beginning and end of hatching are compared. It was found that larvae of pike of the beginning of hatching passed to external feeding earlier. In the period of mixed and exogenous feeding, they not only grew, but also developed more rapidly than larvae from the same brood. It was shown that pike juveniles of the end of hatching were characterized by a retarded development and growth in the first weeks of life (until reaching a length of 100 mm and a weight of 7 g). In the second month of life, specimens of this group began to feed intensively, grow, and according to body length and weight, reached pike juveniles of the beginning of hatching. Pike fingerlings of the end of hatching were characterized by compensation growth that was manifested at the excess of fish food (at cultivation in separate aquariums when the inhibitory effect of large fish on the growth of small fish was excluded) and in ponds where fish food availability was considerably lower.     

<Emphasis Type="Italic">Ty</Emphasis>1<Emphasis Type="Italic">/copia</Emphasis>- and <Emphasis Type="Italic">Ty</Emphasis>3<Emphasis Type="Italic">/gypsy</Emphasis>-like DNA sequences in <Emphasis Type="Italic">Helianthus </Emphasis>species

Two repeated DNA sequences isolated from a partial genomic DNA library of Helianthus annuus, p HaS13 and p HaS211, were shown to represent portions of the int gene of a Ty3 /gypsy retroelement and of the RNase-Hgene of a Ty1 /copia retroelement, respectively. Southern blotting patterns obtained by hybridizing the two probes to BglII- or DraI-digested genomic DNA from different Helianthus species showed p HaS13 and p HaS211 were parts of dispersed repeats at least 8 and 7 kb in length, respectively, that were conserved in all species studied. Comparable hybridization patterns were obtained in all species with p HaS13. By contrast, the patterns obtained by hybridizing p HaS211 clearly differentiated annual species from perennials. The frequencies of p HaS13- and p HaS211-related sequences in different species were 4.3x10(4)-1.3x10(5) copies and 9.9x10(2)-8.1x10(3) copies per picogram of DNA, respectively. The frequency of p HaS13-related sequences varied widely within annual species, while no significant difference was observed among perennial species. Conversely, the frequency variation of p HaS211-related sequences was as large within annual species as within perennials. Sequences of both families were found to be dispersed along the length of all chromosomes in all species studied. However, Ty3 /gypsy-like sequences were localized preferentially at the centromeric regions, whereas Ty1/ copia-like sequences were less represented or absent around the centromeres and plentiful at the chromosome ends. These findings suggest that the two sequence families played a role in Helianthusgenome evolution and species divergence, evolved independently in the same genomic backgrounds and in annual or perennial species, and acquired different possible functions in the host genomes.     

Revision of the <Emphasis Type="Italic">Serrulati</Emphasis> species of <Emphasis Type="Italic">Penstemon</Emphasis> section <Emphasis Type="Italic">Saccanthera</Emphasis> subsection <Emphasis Type="Italic">Serrulati</Emphasis>

A revision of Penstemon sect. Saccanthera subsect. Serrulati includes a new species (P. salmonensis), a new variety (P. triphyllus var. infernalis), and the elevation of a subspecies to species (P. curtiflorus), bringing the total number of species to eight, which are keyed and described, complete with nomenclature and type citations.     

Activity of cytochrome P-450 in whitefish <Emphasis Type="Italic">Coregonus lavaretus</Emphasis> and pike <Emphasis Type="Italic">Esox lucius</Emphasis> from subarctic water bodies exposed to waste water of mining enterprises

The response of hydroxylase activity of cytochrome P-450 from the microsomes of fish liver depends on fish species and on the kind of pollution. Differences in activity of the enzyme in whitefish Coregonus lavaretus and Pike Esox lucius depend on differences in ecology and in sensitivity of species to industrial effluents. Whitefish reacted to pollution by decrease in the activity of cytochrome P-450. In pike the activity of the enzyme increased under the influence of industrial wastewater. Males of both species are less resistant than females to the aforementioned pollutants. With consideration to the obtained results, the determination of activity of cytochropme P-450 may be recommended as the indicator of pollution level of the aquatic environment with industrial waste products, including those containing heavy metals.     

<Emphasis Type="Italic">In silico</Emphasis> and <Emphasis Type="Italic">in situ</Emphasis> characterization of the zebrafish (<Emphasis Type="Italic">Danio rerio</Emphasis>) <Emphasis Type="Italic">gnrh3</Emphasis> (sGnRH) gene

Background

Gonadotropin releasing hormone (GnRH) is responsible for stimulation of gonadotropic hormone (GtH) in the hypothalamus-pituitary-gonadal axis (HPG). The regulatory mechanisms responsible for brain specificity make the promoter attractive for in silico analysis and reporter gene studies in zebrafish (Danio rerio).

Results

We have characterized a zebrafish [Trp⁷, Leu⁸] or salmon (s) GnRH variant, gnrh 3. The gene includes a 1.6 Kb upstream regulatory region and displays the conserved structure of 4 exons and 3 introns, as seen in other species. An in silico defined enhancer at -976 in the zebrafish promoter, containing adjacent binding sites for Oct-1, CREB and Sp1, was predicted in 2 mammalian and 5 teleost GnRH promoters. Reporter gene studies confirmed the importance of this enhancer for cell specific expression in zebrafish. Interestingly the promoter of human GnRH-I, known as mammalian GnRH (mGnRH), was shown capable of driving cell specific reporter gene expression in transgenic zebrafish.

Conclusions

The characterized zebrafish Gnrh3 decapeptide exhibits complete homology to the Atlantic salmon (Salmo salar) GnRH-III variant. In silico analysis of mammalian and teleost GnRH promoters revealed a conserved enhancer possessing binding sites for Oct-1, CREB and Sp1. Transgenic and transient reporter gene expression in zebrafish larvae, confirmed the importance of the in silico defined zebrafish enhancer at -976. The capability of the human GnRH-I promoter of directing cell specific reporter gene expression in zebrafish supports orthology between GnRH-I and GnRH-III.

     

Floral development and systematic position of <Emphasis Type="Italic">Arillastrum</Emphasis>, <Emphasis Type="Italic">Allosyncarpia</Emphasis>, <Emphasis Type="Italic">Stockwellia</Emphasis> and <Emphasis Type="Italic">Eucalyptopsis</Emphasis> (Myrtaceae)

We have investigated the floral ontogeny of Arillastrum, Allosyncarpia, Stockwellia and Eucalyptopsis (of the eucalypt group, Myrtaceae) using scanning electron microscopy and light microscopy. Several critical characters for establishing relationships between these genera and to the eucalypts have been determined. The absence of compound petaline primordia in Arillastrum, Allosyncarpia, Stockwellia and Eucalyptopsis excludes these taxa from the eucalypt clade. Post-anthesis circumscissile abscission of the hypanthium above the ovary in Stockwellia, Eucalyptopsis and Allosyncarpia is evidence that these three taxa form a monophyletic group; undifferentiated perianth parts and elongated fusiform buds are characters that unite Stockwellia and Eucalyptopsis as sister taxa. No floral characters clearly associate Arillastrum with either the eucalypt clade or the clade of Stockwellia, Eucalyptopsis and Allosyncarpia.We gratefully acknowledge Clyde Dunlop and Bob Harwood (Northern Territory Herbarium) for collecting specimens of Allosyncarpia, and Bruce Gray (Atherton) for collecting specimens of Stockwellia. The Australian National Herbarium (CANB) kindly lent herbarium specimens of Eucalyptopsis for examination. This research was supported by a University of Melbourne Research Development Grant to Andrew Drinnan.     

<Emphasis Type="Italic">In vitro</Emphasis> organogenesis and antioxidant enzymes activity in <Emphasis Type="Italic">Acanthophyllum sordidum</Emphasis>

The effect of various hormonal combinations on callus formation and regeneration of shoot and root from leaf derived callus of Acanthophyllum sordidum Bunge ex Boiss. has been studied. Proteins and activity of antioxidant enzymes were also evaluated during shoot and root organogenesis from callus. Calli were induced from leaf explants excised from 30-d-old seedlings grown on Murashige and Skoog medium containing 4.52 μM 2,4-dichlorophenoxyacetic acid + 4.65 μM kinetin. Maximum growth of calli and the most efficient regeneration of shoots and roots occurred with 2.69 μM 1-naphthalene acetic acid (NAA), 2.69 μM NAA + 4.54 μM thidiazuron and 2.46 μM indole-3-butyric acid. Protein content decreased in calli and increased significantly during regeneration of shoots from callus. Superoxide dismutase activity decreased in calli comparing to that of seedlings, then increased in regenerated shoots and roots. High catalase activity was detected in seedlings and regenerated shoots, whereas high peroxidase activity was observed in calli and regenerated roots.     

Pedogamy in <Emphasis Type="Italic">Neidium</Emphasis> (<Emphasis Type="Italic">Bacillariophyceae</Emphasis>)

Single (unpaired) vegetative cells of freshwater pennate diatom Neidium cf. ampliatum differentiated into gametangia and produced a single zygote (auxospore) via a pedogamic process. The gametic nuclei fused after auxospore expansion had begun. The auxospore expanded in parallel to the apical axis of the gametangium.     

<Emphasis Type="Italic">Galleria</Emphasis><Emphasis Type="Italic">mellonella</Emphasis> are Resistant to <Emphasis Type="Italic">Pneumocystis</Emphasis><Emphasis Type="Italic">murina</Emphasis> Infection

Studying Pneumocystis has proven to be a challenge from the perspective of propagating a significant amount of the pathogen in a facile manner. The study of several fungal pathogens has been aided by the use of invertebrate model hosts. Our efforts to infect the invertebrate larvae Galleria mellonella with Pneumocystis proved futile since P. murina neither caused disease nor was able to proliferate within G. mellonella. It did, however, show that the pathogen could be rapidly cleared from the host.     

<Emphasis Type="Italic">Agrobacterium</Emphasis><Emphasis Type="Italic">tumefaciens</Emphasis>-mediated transformation of callus cells of <Emphasis Type="Italic">Crataegus</Emphasis><Emphasis Type="Italic">aronia</Emphasis>

A genetic transformation system has been developed for callus cells of Crataegus aronia using Agrobacterium tumefaciens. Callus culture was established from internodal stem segments incubated on Murashige and Skoog (MS) medium supplemented with 5 mg l⁻¹ Indole-3-butyric acid (IBA) and 0.5 mg l⁻¹ 6-benzyladenine (BA). In order to optimize the callus culture system with respect to callus growth and coloration, different types and concentrations of plant growth regulators were tested. Results indicated that the best average fresh weight of red colored callus was obtained on MS medium supplemented with 2 mg l⁻¹ 2,4-dichlorophenoxyacetic acid (2,4-D) and 1.5 mg l⁻¹ kinetin (Kin) (callus maintenance medium). Callus cells were co-cultivated with Agrobacterium harboring the binary plasmid pCAMBIA1302 carrying the mgfp5 and hygromycin phosphotransferase (hptII) genes conferring green fluorescent protein (GFP) activity and hygromycin resistance, respectively. Putative transgenic calli were obtained 4 weeks after incubation of the co-cultivated explants onto maintenance medium supplemented with 50 mg l⁻¹ hygromycin. Molecular analysis confirmed the integration of the transgenes in transformed callus. To our knowledge, this is the first time to report an Agrobacterium-mediated transformation system in Crataegus aronia.     

Replication timing of large <Emphasis Type="Italic">Sorex granarius</Emphasis> (<Emphasis Type="Italic">Soricidae</Emphasis>, <Emphasis Type="Italic">Eulipotyphla</Emphasis>) telomeres

Previously, we described the unique feature of telomeric regions in Iberian shrew Sorex granarius: its telomeres have two ranges of size, very small (3.8 kb of telomeric repeats on average) and very large discontinuous telomeres (213 kb) interrupted with 18S rDNA. In this study, we have demonstrated extraordinary replication pattern of S. granarius large telomeres that have not been shown before in other studied mammal. Using the ReD-FISH procedure, we observed prolonged, through S period, large telomere replication. Furthermore, revealed ReD-FISH asymmetric signals were probably caused by partial replication of telomeres within an hour of 5-bromodeoxyuridine treatment due to the large size and special organization. We also found that in contrast to the telomeric halo from primary fibroblasts of bovine, mink, and common shrew, telomere halo of S. granarius consists of multiple loops bundled together, some of which contain rDNA. Here, we suggested several replicons firing possibly stochastic in each large telomere. Finally, we performed the TIF assay to reveal DNA damage responses at the telomeres, and along with TIF in nuclei, we found large bodies of telomeric DNA and ?-H2AX in the cytoplasm and on the surface of fibroblasts. We discuss the possibility of additional origin activation together with recombination-dependent replication pathways, mainly homologous recombination including BIR for replication fork stagnation overcoming and further S. granarius large telomere replication.