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.     

Seasonal variability of some biochemical parameters in the whitefish (<Emphasis Type="Italic">Coregonus muksun</Emphasis> and <Emphasis Type="Italic">Coregonus lavaretus</Emphasis>)

The base levels and seasonal variability of ethoxyresorufin-O-deethylase (EROD) activity, glutathione-S-transferase (GST) activity, reduced glutathione concentration (GSH) and phospholipids concentration (PhL) of Coregonus lavaretus (Linnaeus, 1758) and Coregonus muksun (Pallas, 1814) were investigated. The relationships between this biochemical markers, hepatosomatic index and seasonal growth were also examined.     

Special traits of tissue lipids of whitefish <Emphasis Type="Italic">Coregonus lavaretus</Emphasis> living in water bodies with different anthropogenous load

The impact of water pollution on the content of lipid components of the liver and eggs of whitefish Coregonus lavaretus is investigated. The content of triacylglycerols (TAG), sphingomyelin (SPM), phosphatidylinositol (PI), and phosphatidylserine (PS) is higher in the liver of whitefish from polluted waters being a part of adaptogenous reactions (modification of permeability of biomembranes, of activity of membrane enzymes, etc.) providing a possibility of the survival of fish under unfavorable ecological factors. The lipid spectra of whitefish gonads are more stable in comparison with the liver. This may be related to protection of the reproductive system from external influences.     

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 status and origin of some ecological forms of whitefish <Emphasis Type="Italic">Coregonus lavaretus</Emphasis> (L.) from water bodies of Siberia

Molecular genetic analysis of some ecological forms of whitefish belonging to the Coregonus lavaretus (L.) complex from different water bodies of Siberia revealed a high degree of differentiation between them. On the basis of the analysis of the mitochondrial DNA protein-coding ND1 gene, it was demonstrated that the previously described ecological forms of C. anaulorum, Yenisei River whitefish, or Issatschenko’s whitefish (C. fluviatilis), and cisco-like whitefish from Lake Baunt were good biological species. Moreover, each ecological form was represented by a number of phylogenetic lineages, one of which was species-specific. The remaining lineages were characterized by the mitochondrial DNA of another whitefish species, usually, the most common in each geographic region. The results of genetic analysis demonstrated that the formation of modern ecological forms of Siberian pidschian-like whitefish was accompanied by natural introgressive hybridization. It is suggested that most of the modern pidschian-like whitefish species originated as a result of reticulate evolution.     

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.     

The activity of digestive enzymes of the pike <Emphasis Type="Italic">Esox lucius</Emphasis> L. Infected with the cestode <Emphasis Type="Italic">Triaenophorus nodulosus</Emphasis> (Pallas)

It has been shown that protease activity increases and amylase activity decreases from the first to the fifth intestinal segment of pike, while lipase and esterase activities vary within fairly narrow limits. The level of proteolytic enzyme activities increases in pikes infected with Triaenophorus nodulosus (Pallas), but the invasion has no effect on amylase, lipase, or esterase activities. The T. nodulosus infection of pike had no substantial influence on glycogen or protein content in the hepatopancreas of fish. However, it was noted that the ratio of protease and amylase activities in the intestines changed toward an increase in the share of proteases and the share of protein in the hepatopancreas of infected fish.     

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.     

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.     

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.     

Comparative study of bile acid composition of bile of the European vendace <Emphasis Type="Italic">Coregonus albula</Emphasis> L. and the European whitefish <Emphasis Type="Italic">Coregonus lavaretus</Emphasis> L. under conditions of technogenic water reservoir pollution

Changes of the bile acid composition were studied in bile of the vendace Coregonus albula L. and the sea whitefish Coregonus lavaretus L. under effect of sewers of an ore mining and processing plant, the main polluting agents of the sewers being heavy metals. The revealed variability of the bile acid composition indicates different species-related sensitivity to the studied pollutants as well as a lower resistance of males as compared with females to this type of pollution. Mechanisms of effects of industrial sewers on the bile formation processes and a possibility of using parameters of the steroid lipid metabolism at evaluation of the state of aquatic ecosystems are discussed.     

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     

Electrostatic attraction between cytochrome <Emphasis Type="Italic">bc</Emphasis><Subscript>1</Subscript> and cytochrome <Emphasis Type="Italic">c</Emphasis> affects kinetics of cytochrome <Emphasis Type="Italic">c</Emphasis> reduction

The kinetics of the ubiquinol-cytochrome c reductase reaction was examined using membrane fragments and purified bc(1) complexes derived from a wild-type (WT) and a newly constructed mutant (MUT) strains of Paracoccus denitrificans. The cytochrome c(1) of the WT samples possessed an additional stretch of acidic amino acids, which was lacking in the mutant. The reaction was followed with positively charged mitochondrial and negatively charged bacterial cytochromes c, and specific activities, apparent k(cat) values, and first-order rate constant values were compared. These values were distinctly lower for the MUT fractions using mitochondrial cytochrome c but differed only slightly with the bacterial species. The MUT preparations were less sensitive to changes of ionic strength of the reaction media and showed pure first-order kinetics with both samples of cytochrome c. The reaction of the WT enzyme was first order only with bacterial cytochrome c but proceeded with a non-linear profile with mitochondrial cytochrome c. The analysis of the reaction pattern revealed a rapid onset of the reaction with a successively declining rate. Experiments performed in the absence of an electron donor indicated that electrostatic attraction could directly participate in cytochrome c reduction.     

<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.     

Phylogeography of Common Whitefish (<Emphasis Type="Italic">Coregonus lavaretus</Emphasis> L.) of Northwestern Russia

This paper elucidates the features of colonization by whitefish (Coregonus lavaretus L.) of waterbodies of the European part of Russia in relation to Pleistocene glaciation. Based on the data on the frequencies and phylogenetic relationships of mitochondrial DNA haplotypes, a significant role of migrants from the western periglacial refugia is shown. The first large refugium was located at the North Atlantic; the second was at the South-Eastern Baltic. Until the last glaciation, with the maximum at about 20000 years ago, migrations from Siberia took place as well. However, at present the descendants of these migrants in the waterbodies of Northwestern Russia are not the dominants. The size of the refugium where the population lived prior to expansion may be an important condition for the successful spreading of common whitefish.     

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.     

<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.     

Linear growth of sparsely rakered whitefish <Emphasis Type="Italic">Coregonus lavaretus</Emphasis> (Coregonidae) of the Imandra Lake (Murmansk oblast)

This paper studies the properties of linear growth in sparsely rakered whitefish Coregonus lavaretus in the stretches of the large subarctic Imandra Lake, which are characterized by the diversity of habitat conditions and anthropogenic stress levels. The groups of sparsely rakered whitefish that are confined to different areas of the lake are marked out based on the properties of growth, trophic status, and anthropogenic stress intensity. A direct relationship of the linear growth in whitefish with the age of sexual development and trophic level of its habitats is found.     

<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.