Feeding site selection by Wigeon Anas penelope in relation to water

The feeding sites of European Wigeon Anas penelope are always close to water. Initial studies suggest that this is primarily an anti-predator behaviour rather than a requirement for drinking and bathing. Vigilance and flock-size measurements at varying distances from water support this hypothesis. However, birds will feed away from water if grass biomass is greater further away. The end of the shooting season also causes birds to feed further away from water.     

SubViral RNA: a database of the smallest known auto-replicable RNA species

We describe here the establishment of an online database containing a large number of sequences and related data on viroids, viroid-like RNAs and human hepatitis delta virus (vHDV) in a customizable and user-friendly format. This database is available on the World Wide Web at http://penelope.med.usherb.ca/subviral.     

Thallium contamination in wild ducks in Japan

Although thallium (Tl) is toxic to both humans and animals, there is little information on contamination in wildlife. In this study, Tl contents in wild ducks in Japan were determined. Contents of Tl in kidney and liver ranged from 0.42 to 119.61 and 0.10 to 33.94 microg/g dry weight, respectively. Significant correlations between Tl contents in kidney and liver were observed for all dabbling ducks except mallard (Anas platyrhynchos); similar correlations were not observed in diving ducks. Variation in Tl content was observed between sampling locations with the highest mean Tl content in the Eurasian wigeon (Anas penelope) collected in Ibaraki Prefecture.     

Effect of temperature on elastic properties of CNT-polyethylene nanocomposite and its interface using MD simulations

This paper investigates the effect of temperature on the elastic modulus of carbon nanotube-polyethylene (CNT-PE) nanocomposite and its interface using molecular dynamics (MD) simulations, by utilizing the second-generation polymer consistent force field (PCFF). Two CNTs—armchair and zigzag—were selected as reinforcing nano-fillers, and amorphous PE was used as the polymer matrix. For atomistic modelling of the nanocomposite, the commercially available code Materials Studio 8.0 was used and all other MD simulations were subsequently performed using the open source code Large-Scale Atomic/Molecular Massively Parallel Simulator (LAMMPS). To obtain the elastic modulus of the nanocomposite, stress-strain curves were drawn at different temperatures by performing uniaxial deformation tests on the nanocomposite material, whereas the curvatures of the interfacial interaction energy vs. strain curves were utilized to obtain Young’s modulus of the interface. In addition, the glass transition temperatures of the polymer matrix and nanocomposites were also evaluated using density-temperature curves. Based on the results, it is concluded that, irrespective of temperature condition, a nanocomposite reinforced with CNT of larger chirality (i.e., armchair) yields a higher value of Young’s modulus of the nanocomposite and its interface. It was also found that, at the phase transition (from a glassy to a rubbery state) temperature (i.e., glass transition temperature), Young’s moduli of the polymer matrix, nanocomposite, and its interface drop suddenly. The results obtained from MD simulations were verified with results obtained from continuum-based rule-of-mixtures.     

Effects of winter and early spring grazing by Wigeon Anas penelope on their food supply

Wigeon Anas penelope selectively grazed small patches of grassland near water. Their grazing activity affected the vegetation on which they fed, resulting in a 52% increase in leaf production over the winter and, at the end of winter, 4.75% higher protein levels compared with plants which were ungrazed. These responses of the plants were caused by defoliation, which stimulated growth, and not a fertiliser effect from the birds' droppings. We suggest that repeated feeding on the same areas is a deliberate strategy used by Wigeon which causes an improvement in their dietary quality in late winter and early spring.     

Intestinal carriage of Yersinia pseudotuberculosis by wild birds and mammals in Japan

Fecal specimens were obtained from wild birds and mammals in the eastern part of Shimane Prefecture, Japan, an area where serotype 1b, 2b, 3, and 4b strains of Yersinia pseudotuberculosis were found to be prevalent in humans. Each of 869 animals, including 259 wild birds and 610 wild mammals, was screened for yersiniae. A total of 37 strains of Y. pseudotuberculosis were isolated from 34 (5.6%) mammals, including 23 raccoon dogs (Nyctereutes procyonoides), eight deer (Cervus nippon), two hares (Lepus brachyurus), and one marten (Martes melampus), and from two (0.8%) birds, including one eastern spot-billed duck (Anas poecilorhyncha) and one wigeon (Anas penelope). The Y. pseudotuberculosis isolates collected belonged to virulence plasmid-positive (serotypes 1b, 2b, 3, 4b, and 6) and virulence plasmid-negative (serotype 5a) strains, the most predominant serotype being 4b. The close relationship between the regional distributions of Y. pseudotuberculosis in wild animals and humans suggests that wild animals are an important source of infection.     

Intestinal carriage of Yersinia pseudotuberculosis by wild birds and mammals in Japan.

Fecal specimens were obtained from wild birds and mammals in the eastern part of Shimane Prefecture, Japan, an area where serotype 1b, 2b, 3, and 4b strains of Yersinia pseudotuberculosis were found to be prevalent in humans. Each of 869 animals, including 259 wild birds and 610 wild mammals, was screened for yersiniae. A total of 37 strains of Y. pseudotuberculosis were isolated from 34 (5.6%) mammals, including 23 raccoon dogs (Nyctereutes procyonoides), eight deer (Cervus nippon), two hares (Lepus brachyurus), and one marten (Martes melampus), and from two (0.8%) birds, including one eastern spot-billed duck (Anas poecilorhyncha) and one wigeon (Anas penelope). The Y. pseudotuberculosis isolates collected belonged to virulence plasmid-positive (serotypes 1b, 2b, 3, 4b, and 6) and virulence plasmid-negative (serotype 5a) strains, the most predominant serotype being 4b. The close relationship between the regional distributions of Y. pseudotuberculosis in wild animals and humans suggests that wild animals are an important source of infection.     

Population and community level responses in Anas -species to patch disturbance caused by an ecosystem engineer, the beaver

We studied the response of a guild of three Anas -species, to patch disturbance caused by the beaver Castor canadensis in southern Finland during 1988–1996 Of the three species, the teal Anas crecca increased in beaver ponds during the first two years of beaver occupation compared to the situation before the beaver The mallard Anas platyrhynchos and wigeon Anas penelope did not respond to beaver flooding during the first two years Also dominance relations changed upon inundation The mallard usually was more numerous than the teal before the beaver, but the reverse was the case during beaver occupation The study shows that some animal guilds may benefit from disturbance although species dominance relations may change And, that this change in dominance can be caused by an ecosystem engineer, the beaver     

Density dependence, regulation and open-closed populations: insights from the wigeon, Anas penelope

We investigated whether the degree of exchange with other populations affects the occurrence of density-dependent regulation. We contrasted data from an Icelandic and a Finnish population of breeding wigeons ( Anas penelope ), the former population being more closed than the later. We looked for density dependence in time-series data and investigated whether breeding success is density dependent and plays a role in population dynamics and regulation. Time-series analysis did not reveal density-dependent regulation in either population. Nor did we find evidence of density-dependent breeding success in either population. However, population growth rate appeared to be strongly dependent on the breeding success in the previous year in the closed population but not in the open population. Our findings underline how important it is to link time-series analysis to the study of potential stabilizing mechanisms in order to understand population dynamics and regulation. We also suggest that it may be a difficult task to achieve sustainability in waterfowl harvesting, the theoretical basis of which is density-dependent population regulation.     

Breeding success of ducks in relation to different habitat factors

Breeding success of four duck species, Teal Anas crecca , Mallard Anas platyrhynchos , Wigeon Anas penelope and Goldeneye Bucephala clangula , was studied in a boreal watershed in southern Finland during 1988–1991 in relation to habitat type (based on vegetation development) and food abundance. Of the three common breeders, breeding success (broods/ pair) was highest in Teal (1.7) and lower in Mallard (1.4) and Goldeneye (1.2). Over the years, Goldeneye brood densities were less variable than were pair densities, so breeding success varied more among years that did that of Mallard or Teal. In Teal, the yearly numbers of pairs and broods fluctuated together, whereas in Mallard neither varied appreciably. Breeding success by Goldeneye was higher where nektonic invertebrates were more abundant, whereas breeding success of the dabbling ducks had very few significant correlations with environmental factors.     

Factors influencing tone in rabbit large intestine.

Pressure/volume curves obtained in the presence of papaverine have been compared with those obtained under control conditions in rabbit large intestine. Tension/length curves obtained on stimulation of the extrinsic nerve supply to the intestine have been compared with control curves. Evidence is presented for a small contribution of sustained muscular activity to the pressue/volume and tension/length curves. The effect of stretch on peak tension attained by the intestine has also been examined.     

Habitat associations of ducks during different phases of the breeding season

Habitat use of mallard Anas platvrhynchos , teal A crecca. wigeon A penelope and goldeneye Bucephala clangula was studied m southern Finland during 1988–1991 Emphasis included evaluation of the importance of food and vegetation structure and revealing of the patterns of habitat use throughout the breeding season Average lake scores of pairs, broods, and juveniles of all species were on the luxunant end of a principal component analysis axis describing habitat structure A more detailed examination, however, revealed clear differences in habitat distributions both between and within species Generally, habitat distributions seemed to shift toward the luxuriant from pairs to broods However, goldeneye juveniles used both the most luxuriant and the poorest habitats more than expected When all phases of the breeding cycle are considered, habitat luxuriance seemed to be more important for dabbling ducks and nektonic invertebrates more important for the goldeneye Emerging insects were most important to the teal     

Local stability and evolution of the genetic code

The standard genetic code is known to be robust to translation errors and point mutations. We studied how small modifications of the standard code affect its robustness. The robustness was assessed in terms of a proper stability function, the negative variations of which correspond to a more robust code. The fraction of more robust codes obtained under small modifications appeared to be unexpectedly high, about 0.1-0.4 depending on the choice of stability function and code modifications, yet significantly lower than the corresponding fraction in the random codes (about a half). In this sense the standard code ought to be considered distinctly non-random in accordance with previous observations. The distribution of the negative variations of stability function revealed very abrupt drop beyond one standard deviation, much sharper than for Gaussian distribution or for the random codes with the same number of codons in the sets coding for amino acids or stop-codons. This behavior holds for both the standard code as a whole and its binary NRN-NYN, NWN-NSN, and NMN-NKN blocks. Previously, it has been proved that such binary block structure is necessary for the robustness of a code and is inherent to the standard genetic code. The modifications of the standard code corresponding to more robust coding may be related to the different variants of the code. These effects may also contribute to the rates of replacements of amino acids. The observed features demonstrate the joint impact of random factors and natural selection during evolution of the genetic code.     

Stability of the genetic code and optimal parameters of amino acids

The standard genetic code is known to be much more efficient in minimizing adverse effects of misreading errors and one-point mutations in comparison with a random code having the same structure, i.e. the same number of codons coding for each particular amino acid. We study the inverse problem, how the code structure affects the optimal physico-chemical parameters of amino acids ensuring the highest stability of the genetic code. It is shown that the choice of two or more amino acids with given properties determines unambiguously all the others. In this sense the code structure determines strictly the optimal parameters of amino acids or the corresponding scales may be derived directly from the genetic code. In the code with the structure of the standard genetic code the resulting values for hydrophobicity obtained in the scheme “leave one out” and in the scheme with fixed maximum and minimum parameters correlate significantly with the natural scale. The comparison of the optimal and natural parameters allows assessing relative impact of physico-chemical and error-minimization factors during evolution of the genetic code. As the resulting optimal scale depends on the choice of amino acids with given parameters, the technique can also be applied to testing various scenarios of the code evolution with increasing number of codified amino acids. Our results indicate the co-evolution of the genetic code and physico-chemical properties of recruited amino acids.     

Peripheral encoding of behaviorally relevant acoustic signals in a vocal fish: single tones

The midshipman fish, Porichthys notatus, generates acoustic signals for intraspecific communication. Nesting males produce long-duration “hums” which attract gravid females and can be effectively mimicked by pure tones. In this study we examine the encoding of tonal signals by the midshipman peripheral auditory system. Single-unit recordings were made from afferents innervating the sacculus while presenting sounds via an underwater loudspeaker. Units were characterized by iso-intensity spike rate and vector strength of synchronization curves, as well as by peri-stimulus time histograms. Additionally, response-intensity curves and responses to long-duration (up to 10 s) stimuli were obtained. As has been seen in other teleosts, afferents had highly variable activity profiles. Excitatory frequencies ranged from 60 to over 300 Hz with most units responding best around 70 or 140 Hz. Thresholds at 90 Hz ranged from 95 to 145 dB re 1 μPa. Strong synchronization provided a robust temporal code of frequency, comparable to that described for goldfish. Spike rate showed varying degrees of adaptation but high rates were generally maintained even for 10-s stimuli. The midshipman peripheral auditory system is well suited to encoding conspecific communication signals, but nonetheless shares many response patterns with the auditory system of other teleosts. Accepted: 10 February 1999     

Analytical theory for the fluence,planar fluence,energy fluence,planar energy fluence and absorbed dose of primary particles and their fragments in broad therapeutic light ion beams

The purpose of the present work is to develop analytical expressions for the depth variation of the fluence, planar fluence, the energy fluence, planar energy fluence, the mean energy and absorbed dose of primary ions and their associated fragments in tissue-like media with ranges of clinical interest. The analytical expressions of the primary ions and associated fragments take into account nuclear interactions, energy losses, range straggling and multiple scattering. The analytical models of the radiation field quantities were compared with the results of the modified Monte Carlo (MC) code SHIELD-HIT₊. The results show that the shape of the depth absorbed dose distribution of the primary particles is characterized by an increasingly steep exponential fluence decrease with depth as the charge and atomic weight increase. This is accompanied by a compensating increased energy loss towards the Bragg peak as the charge of the ion increases. These largely compensating mechanisms are the main reason that the depth absorbed dose curve of all light ions is surprisingly similar. In addition, a rather uniform dose in the plateau region is obtained since the increasing fragment production almost precisely compensates the loss of primaries. The dominating light fragments such as protons and alpha particles are characterized by longer ranges than the primaries and their depth dose curves to some extent coincide well with the depth fluence curves due to a rather slow variation of mean stopping powers. In contrast, the heavier fragments are characterized by the build up of a slowing down spectrum similar to that of the primaries but with initially slightly shorter or longer ranges depending on their mass to atomic number ratio. The presented analytical theory for the light ion penetration in matter agree quite well with the MC and experimental data and may be very useful for fast analytical calculations of quantities like mean energy, fluence, energy fluence, absorbed dose, and LET.     

Serological survey of Toxoplasma gondii in wild waterfowl in Chukotka, Kamchatka, Russia and Hokkaido, Japan

Antibodies to Toxoplasma gondii were assayed by ELISA in 22 experimentally inoculated domestic ducks. In addition, a serological assay was carried out at Obihiro, Hokkaido, Japan, in 2004 and 2005, on 221 wild ducks of 5 species: Anas platyrhynchus (n = 111); A. poecilorhyncha (n = 27); A. acuta (n = 58); A. penelope (n = 16); and A. crecca (n = 9). Assays were also conducted using sera from 197 wild geese of 2 species, i.e., Anser albifrons (n = 162) and Ans. fabalis (n = 35). Birds were collected between 2003 and 2005 from 3 different areas: Lake Miyajima-numa, Hokkaido, Japan, regions around Anadyr city of Chukotka autonomous okrug, and Lake Makobetukoe, Kamchatka oblast, Russia. The ELISA cutoff value (OD) was > or =0.395 based on results from uninfected ducks; the final dilution ratio recognized as positive was represented by the end titer. The end titer in the experimentally infected ducks ranged from 1:400 to 1:3,200. Antibodies to T. gondii were found in 49 of the 221 wild duck samples from Japan: A. platyrhynchus (22/74); A. poecilorhyncha (2/15); A. penelope (3/16); A. acuta (4/58); and A. crecca (0/9), all in 2004. In 2005, T. gondii was found in A. platyrhynchus (13/37); and A. poecilorhyncha (5/12). Thirty-two of 197 wild goose samples were seropositive, i.e., Ans. albifrons (7/51) in 2004 and (11/72) in 2005 in Miyajima-numa, Japan and 9/39 in Chukotka, Russia as well as in Ans. fabalis (5/35) in Kamchatka, for which the end titer ranged from 1:100 to 1:3,200. In immunoblotting, the A. platyrhynchus samples showed specific IgG antibody binding to several antigens in the T. gondii lane, i.e., at 30 and 43 kDa, but not in the Neospora caninum lane. No specific bands were noted in samples for which antibody activity was not detected. These results suggest that wild waterfowl inhabiting Hokkaido, Chukotka, and Kamchatka may be exposed to T. gondii.     

The complementarity of the chemical parameters of amino acids and anticodons in the genetic code

Chemical language of the genetic code is suggested in which elementary information code units are presented by functional groups of amino acids and nucleotides. Using this language, the existence of correspondence and conformity of chemical parameters of amino acids and of central nucleotides of their anticodons was demonstrated. These findings confirm the idea that the genetic code is determined by chemical properties of amino acids and nucleotides and that this determination is the result of direct specific interactions between amino acids and nucleotide triplets at the stage of the origin of the code. The data obtained reveal primary role of anticodon triplets in the origin of the code. Key role of the central nucleotide in triplets for amino acid coding is confirmed.