Early birds are sexy: male age, dawn song and extrapair paternity in blue tits, Cyanistes (formerly Parus) caeruleus

Sexual selection theory predicts that signals reflecting the relative quality of individuals should be used in mate choice. Females could base their choice of copulation partners on male secondary sexual traits that honestly signal male age, as predicted by the age-based indicator mechanism. Studies have shown that female blue tits prefer older males and that aspects of dawn song reflect male quality, but it remains unknown whether dawn song characteristics correlate with male age. We compared dawn song characteristics of second-year (SY) and older (ASY) male blue tits (cross-sectional analysis), and tested for age-related changes within individuals (longitudinal analysis) and differential overwinter survival of SY males. We further investigated the relation between dawn song and paternity gain and loss. We found that ASY male blue tits began to sing earlier relative to sunrise than did SY males. This difference in the onset of dawn singing was due to age-related changes in individual performance rather than differential survival of individuals with varying expression of the trait. Males that began to sing earlier at dawn had more mating partners, and were more likely to gain extrapair paternity. Our findings suggest that the onset of dawn song can provide a simple mechanism for females to assess the relative quality of their mate and of neighbouring males. We propose that females use the onset of singing as a cue for their choice of extrapair partners. (c) 2006 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

Experimentally elevated plasma testosterone levels do not influence singing behaviour of male blue tits (Parus caeruleus) during the early breeding season

Sexual selection theory suggests that females might prefer males on the basis of testosterone (T)-dependent secondary sexual traits such as song. Correlational studies have linked high plasma T-levels to high diurnal song output. This has been confirmed in experiments where T-levels were kept high at times when natural T-levels have decreased. However, surprisingly little is known about the relation between T-levels during the early breeding season and song. In many passerine birds males sing at a high rate at dawn early in the breeding season, referred to as the dawn chorus. In blue tits (Parus caeruleus), the dawn chorus coincides with the fertile period of the female, whereas diurnal song occurs throughout the breeding season. Previous studies on blue tits showed that characteristics of the dawn chorus correlate with male reproductive success. We experimentally elevated plasma T-levels in male blue tits during the pre-fertile and fertile period. Our aim was to test whether increased plasma T-levels affect dawn song characteristics and increase the amount of diurnal song. Although T-implants successfully raised circulating T-levels, we did not find any difference between T- and control males in temporal performance measures of dawn song or in diurnal song output. Our results suggest that either there is no direct causal link between song output or quality and individual T-levels, or experimental manipulations of T-levels using implants do not permit detection of such effects during the early breeding season. Although we cannot exclude that individual T-levels are causally linked to other (e.g. structural) song parameters, our results cast doubt on T-dependence as the mechanisms that enforces honesty on song as a sexually selected trait.

The natural plasma testosterone profile of male blue tits during the breeding season and its relation to song output

In male birds, the gonadal hormone testosterone (T) is known to influence territorial and mating behaviour. Plasma levels of T show seasonal fluctuations which vary in relation to mating system and social instability. First, we determined the natural T profile of male blue tits Parus caeruleus during the breeding season. We found that plasma levels of T increased at the onset of nest building. Thus, the increase in circulating T was not associated with territory establishment, nor with the fertile period of the males' mates. In most individuals, T levels dropped to values close to zero during the period of chick feeding. Second, we investigated the relationship between plasma levels of T and male age, size, and singing behaviour. During the mating period, T levels did not differ between 1 yr old and older males and did not correlate with body size or condition. However, song output during the dawn chorus tended to be positively correlated with T levels. Therefore, if high T levels are costly, song output might be an honest indicator of male quality in blue tits. Finally, we show that plasma levels of T are significantly higher during the night than during the day. This pattern has also been observed in captive non-passerine birds, but its functional significance remains unknown.

Multiple major outbursts from a restless luminous blue variable in NGC 3432

We present new photometric and spectroscopic observations of an unusual luminous blue variable (LBV) in NGC 3432, covering three major outbursts in 2008 October, 2009 April and 2009 November. Previously, this star experienced an outburst also in 2000 (known as SN 2000ch). During outbursts the star reached an absolute magnitude between -12.1 and -12.8. Its spectrum showed H, He I and Fe II lines with P-Cygni profiles during and soon after the eruptive phases, while only intermediate-width lines in pure emission (including He II lambda 4686) were visible during quiescence. The fast-evolving light curve soon after the outbursts, the quasi-modulated light curve, the peak magnitude and the overall spectral properties are consistent with multiple episodes of variability of an extremely active LBV. However, the widths of the spectral lines indicate unusually high wind velocities (1500-2800 km s-1), similar to those observed in Wolf-Rayet stars. Although modulated light curves are typical of LBVs during the S-Dor variability phase, the luminous maxima and the high frequency of outbursts are unexpected in S-Dor variables. Such extreme variability may be associated with repeated ejection episodes during a giant eruption of an LBV. Alternatively, it may be indicative of a high level of instability shortly preceding the core-collapse or due to interaction with a massive, binary companion. In this context, the variable in NGC 3432 shares some similarities with the famous stellar system HD 5980 in the Small Magellanic Cloud, which includes an erupting LBV and an early Wolf-Rayet star.

Proteomics Identification of Azaspiracid Toxin Biomarkers in Blue Mussels, Mytilus edulis

Azaspiracids are a class of recently discovered algae-derived shellfish toxins. Their distribution globally is on the increase with mussels being most widely implicated in azaspiracid-related food poisoning events. Evidence that these toxins were bound to proteins in contaminated mussels has been shown recently. In the present study characterization of these proteins in blue mussels, Mytilus edulis, was achieved using a range of advanced proteomics tools. Four proteins present only in the hepatopancreas of toxin-contaminated mussels sharing identity or homology with cathepsin D, superoxide dismutase, glutathione S-transferase Pi, and a bacterial flagellar protein have been characterized. Several of the proteins are known to be involved in self-defense mechanisms against xenobiotics or up-regulated in the presence of carcinogenic agents. These findings would suggest that azaspiracids should now be considered and evaluated as potential tumorigenic compounds. The presence of a bacterial protein only in contaminated mussels was an unexpected finding and requires further investigation. The proteins identified in this study should assist with development of urgently required processes for the rapid depuration of azaspiracid-contaminated shellfish. Moreover they may serve as early warning indicators of shellfish exposed to this family of toxins. Molecular & Cellular Proteomics 8: 1811-1822, 2009.

Development and characterization of 10 polymorphic microsatellite loci for the blue shark, Prionace glauca, and their cross shark-species amplification.

Ten polymorphic nuclear microsatellite loci were developed from a microsatellite enriched genomic library of the blue shark, Prionace glauca. The utility of these markers for genetic studies of this globally distributed, heavily exploited, oceanic predator was assessed by screening 120 specimens sampled from six locations throughout the species’ range. Both moderately and highly polymorphic marker loci were identified. Three to 35 alleles were found to be segregating per locus (mean 10.1) with observed heterozygosities ranging from 24 to 91%. Evaluation of the cross-species amplification of these markers across 18 additional shark species indicates that these microsatellites are potentially useful for genetic studies of other species of conservation concern.

How Wonderful Days became Sky Blue: The Transnational Circulation of South Korean Animation

This article examines the transnational circulation of South Korean animation, with a particular focus on the production and release of "Wonderful Days" in Korea and around the world, arguing that Korean animation's international identity is defined in relation to the more visible Japanese cinema.

Voltage-activated currents in cardiac myocytes of the blue mussel, Mytilus edulis

Voltage-sensitive ionic currents were identified and characterised in ventricular myocytes of the bivalve mollusc, Mytilus edulis, using the whole-cell patch-clamp technique. Two outward currents could be distinguished. A potassium A current (I-A) activated at - 30 mV from a holding potential of - 60 mV. This transient current was inactivated by holding the cells at a potential of - 40 mV and was also blocked by applying 4-aminopyridine (3 mM) to the external bath solution. A second current was identified as a delayed rectifier (I-K). This also activated at - 30 mV but exhibited a sustained time course and was still activated at a holding potential of - 40 mV. Both outward currents were reduced in the presence of tetraethylammonium ions (30 mM). A small number of heart cells also showed an inward sodium current (I-Na). This current appeared at potentials more positive than - 50 mV, reached a maximum at - 20 mV, and decreased with further depolarisation. I-Na was inactivated at a holding potential of - 40 mV and was blocked by tetrodotoxin (1 mu M). A second inward current had a sustained time course and was not inactivated by holding the cell at a potential of -40 mV, and was also not abolished by tetrodotoxin. This current peaked at 0 mV, decreasing with further depolarisation. Furthermore, it was enhanced by the addition of barium ions (3 mM) to the bath and was blocked by external cobalt (2 mM) or nifedipine (15 mu M) These findings are consistent with this being an L-type calcium current (I-Ca) The possible physiological roles of these currents in M. edulis heart are discussed. (C) 1999 Elsevier Science Inc. All rights reserved.