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1.
Denise Risch Nicholas J. Gales Jason Gedamke Lars Kindermann Douglas P. Nowacek Andrew J. Read Ursula Siebert Ilse C. Van Opzeeland Sofie M. Van Parijs Ari S. Friedlaender 《Biology letters》2014,10(4)
For decades, the bio-duck sound has been recorded in the Southern Ocean, but the animal producing it has remained a mystery. Heard mainly during austral winter in the Southern Ocean, this ubiquitous sound has been recorded in Antarctic waters and contemporaneously off the Australian west coast. Here, we present conclusive evidence that the bio-duck sound is produced by Antarctic minke whales (Balaenoptera bonaerensis). We analysed data from multi-sensor acoustic recording tags that included intense bio-duck sounds as well as singular downsweeps that have previously been attributed to this species. This finding allows the interpretation of a wealth of long-term acoustic recordings for this previously acoustically concealed species, which will improve our understanding of the distribution, abundance and behaviour of Antarctic minke whales. This is critical information for a species that inhabits a difficult to access sea-ice environment that is changing rapidly in some regions and has been the subject of contentious lethal sampling efforts and ongoing international legal action. 相似文献
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The photoreaction of opsin regenerated with 9-demethylretinal has been investigated by UV-vis spectroscopy, flash photolysis experiments, and Fourier transform infrared difference spectroscopy. In addition, the capability of the illuminated pigment to activate the retinal G-protein has been tested. The photoproduct, which can be stabilized at 77 K, resembles more the lumirhodopsin species, and only minor further changes occur upon warming the sample to 170 K (stabilizing lumirhodopsin). UV-vis spectroscopy reveals no further changes at 240 K (stabilizing metarhodopsin I), but infrared difference spectroscopy shows that the protein as well as the chromophore undergoes further molecular changes which are, however, different from those observed for unmodified metarhodopsin I. UV-vis spectroscopy, flash photolysis experiments, and infrared difference spectroscopy demonstrate that an intermediate different from metarhodopsin II is produced at room temperature, of which the Schiff base is still protonated. The illuminated pigment was able to activate G-protein, as assayed by monitoring the exchange of GDP for GTP gamma S in purified G-protein, only to a very limited extent (approximately 8% as compared to rhodopsin). The results are interpreted in terms of a specific steric interaction of the 9-methyl group of the retinal in rhodopsin with the protein, which is required to initiate the molecular changes necessary for G-protein activation. The residual activation suggests a conformer of the photolyzed pigment which mimics metarhodopsin II to a very limited extent. 相似文献
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The phylogeny of Greya Busck (Lepidoptera: Prodoxidae) was inferred from
nucleotide sequence variation across a 765-bp region in the cytochrome
oxidase I and II genes of the mitochondrial genome. Most parsimonious
relationships of 25 haplotypes from 16 Greya species and two outgroup
genera (Tetragma and Prodoxus) showed substantial congruence with the
species relationships indicated by morphological variation. Differences
between mitochondrial and morphological trees were found primarily in the
positions of two species, G. variabilis and G. pectinifera, and in the
branching order of the three major species groups in the genus. Conflicts
between the data sets were examined by comparing levels of homoplasy in
characters supporting alternative hypotheses. The phylogeny of Greya
species suggests that host-plant association at the family level and larval
feeding mode are conservative characters. Transition/transversion ratios
estimated by reconstruction of nucleotide substitutions on the phylogeny
had a range of 2.0-9.3, when different subsets of the phylogeny were used.
The decline of this ratio with the increase in maximum sequence divergence
among taxa indicates that transitions are masked by transversions along
deeper internodes or long branches of the phylogeny. Among transitions,
substitutions of A-->G and T-->C outnumbered their reciprocal
substitutions by 2-6 times, presumably because of the approximately 4:1
(77%) A+T-bias in nucleotide base composition. Of all transversions,
73%-80% were A<-->T substitutions, 85% of which occurred at third
positions of codons; these estimates did not decrease with an increase in
maximum sequence divergence of taxa included in the analysis. The high
frequency of A<-->T substitutions is either a reflection or an
explanation of the 92% A+T bias at third codon positions.
相似文献
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