Do European starlings prefer light environments containing UV?

Many captive birds are kept in artificial lighting that is typically deficient in ultraviolet (UV) wavelengths. Most birds can perceive the range of light that humans see but also have an additional retinal cone type that is tuned to UV wavelengths. Consequently, artificial lighting may be detrimental as it might limit the functionality of their vision. We examined the preferences of European starlings, Sturnus vulgaris, for various artificial light environments. In our first experiment, groups of starlings showed a preference for environments that contained UV (UV+) over those where UV wavelengths had been removed (UV -). This preference was not affected by the sex of the individuals within the group or, as shown in a later experiment, by whether the birds had been previously housed in UV+ or UV - conditions. In contrast, individual starlings showed no preference for UV+ over UV - environments, although the power of our test was low. In a subsequent experiment, starling groups preferred the higher of two light intensities that were presented; however, equalizing the overall quantal flux between UV+ and UV - extinguished any preference for UV+ over UV -. The group preference for UV+ conditions in the first experiment may therefore have resulted from a preference for brighter conditions rather than a specific preference for UV. However, equalizing the quantal flux may not equalize perceived brightness, because it is not known how birds' visual systems weight input from each cone type. We conclude that, for nonbreeding, group-housed captive starlings, there is no positive evidence of a preference for the presence of UV as a specific wavelength. (C) 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.

Synchronization by low-amplitude light-dark cycles of 24-hour pineal and plasma melatonin rhythms of hatchling European starlings (Sturnus vulgaris)

In young European starlings, as in other avian species, high-amplitude 24-hr rhythms in plasma and pineal melatonin are already present around the time of hatching. In chickens this rhythmicity results at least partly from the light sensitivity of the melatonin-producing and -secreting system. In contrast to the chicken, the starling is a hole-nesting bird, and it seemed questionable whether the low light intensities in the nest are sufficient to synchronize perinatal melatonin rhythms. We therefore exposed starling eggs to light cycles roughly simulating those measured in nest-boxes, i.e., an 11-hr phase of complete darkness and a 13-hr phase consisting of 15 min of dim light (10 lux) alternating with 30 min of darkness. For one group the photophase lasted from 0600 to 1900 hr; for the other group the photophase lasted from 1800 to 0700 hr. In approximately 10-hr-old hatchlings of both groups, plasma and pineal melatonin concentrations were high during the dark phase and low during the light phase. We conclude that perinatal low-amplitude light intensity changes of the kind experienced by hatching starlings in the field are sufficient for synchronizing the melatonin-producing and -secreting system in the pineal and possibly other organs.

Photosynthetic performance of transplanted ecotypes of Ecklonia cava (Laminariales, Phaeophyta)

Young sporophytes of short-stipe ecotype of Ecklonia cava from a warmer locality (Tei, Kochi Pref., southern Japan) and those of long-stipe ecotype from a cooler locality (Nabeta, Shizuoka Pref., central Japan) were transplanted in 1995 to artificial reefs immersed at the habitat of long-stipe ecotype in Nabeta Bay, Shizuoka Pref., central Japan. The characteristics of photosynthesis and respiration of bladelets of the transplanted sporophytes of the two ecotypes were compared in winter and summer 1997; the results were assessed per unit area, per unit chlorophyllacontent and per unit dry weight. In photosynthesis-light curves at 10–29 °C, light saturation occurred at 200–400 µmol photon m^–2s^–1in sporophytes from both Tei and Nabeta. The maximum photosynthetic rate (P max) at 10–29 °C and the light-saturation index (I k) at 25–29 °C in sporophytes from both localities were generally higher in winter than in summer.P_max at 25–29 °C (per unit area and chlorophylla) were higher in sporophytes from Tei than those from Nabeta in both seasons. The optimum temperature for photosynthesis was 25 °C in winter and 27 °C in summer at high light intensities of 100–400 µmol photon m^–2s^–1. However, at lower light intensities of 12.5–50 µmol photon m^–2s^–1, it was 20 °C in winter and 25–27 °C in summer for sporophytes from both locations. Dark respiration increased with temperature rise in the range of 10–29 °C in sporophytes from both locations in summer and winter. The sporophytes transplanted from Tei (warmer area) showed higher photosynthetic activities than those from Nabeta (cooler area) at warmer temperatures even under the same environmental conditions. This indicates that these physiological ecotypes have arisen from genetic differentiation.

Mobile phone-based electrochemiluminescence sensing exploiting the 'USB On-The-Go' protocol

A low-cost system to generate, control and detect electrochemiluminescence using a mobile smartphone is described. A simple tone-detection integrated circuit is used to switch power sourced from the phone's Universal Serial Bus (USB) 'On-The-Go' (OTG) port, using audible tone pulses played over the device's audio jack. We have successfully applied this approach to smartphones from different manufacturers and with different operating system versions. ECL calibrations of a common luminophore, tris(2,2′-bipyridine)ruthenium(II) ([Ru(bpy)3]²⁺), with 2-(dibutylamino)ethanol (DBAE) as a co-reactant, showed no significant difference in light intensities when an electrochemical cell was controlled by a mobile phone in this manner, compared to the same calibration generated using a conventional potentiostat. Combining this novel approach to control the applied potential with the measurement of the emitted light through the smart phone camera (using an in-house built Android app), we explored the ECL properties of a water-soluble iridium(III) complex that emits in the blue region of the spectrum. The iridium(III) complex exhibited superior co-reactant ECL intensities and limits of detection to that of the conventional [Ru(bpy)3]²⁺ luminophore.