Several injections of 3–5 μl of 2.5% Alexa-Fluor 488-coupled Dextranamin MW 3000 (total 20 μl) were made into the liver. The application needle was left inside the injection site for 30 s before retraction to avoid dye leakage. Following the injection the wound was sutured, a local anesthetic (Xylocain-Gel) administered and the animal was allowed to recover. Optimal labeling of the DRGs was found 3–4 days postinjection. Trpv4−/− mice were genotyped using PCR and backcrossed onto a C57Bl/6 background for

at least four generations ( Mizuno et al., 2003). Transgenic α3nAChR-EGFP-mice were obtained from the Gene Expression Nervous System Atlas (GENSAT) Project. Genotyping was performed by PCR using EGFP-primers according to the GENSAT-protocol. Statistical analyses were performed using GraphPad Prism 5.0. Means selleck chemicals are shown ± SEM. This work was supported by an internal clinical cooperation grant from the MDC and ECRC to G.R.L. and J.J. We would like to thank Andrew Plested, selleck Jan Siemens, and Paul Heppenstall for critical reading of the manuscript. Additional support was obtained from the Deutsche Forschungsgemeinschaft to G.R.L. (SFB 665). We are thankful for the excellent technical assistance of Heike Thränhardt. “
“Each fall,

millions of monarch butterflies (Danaus plexippus) migrate from eastern North America to their overwintering grounds in central Mexico, some traveling distances approaching 4000 km. The yearly migration is one of the most astonishing and biologically intriguing phenomena in the animal world. Behavioral experiments have shown that the migrants use a time-compensated sun compass to maintain a southerly Tryptophan synthase flight direction over the duration of the migration ( Perez et al., 1997, Mouritsen and Frost, 2002 and Froy et al., 2003). In general, this sun compass mechanism postulates that skylight cues, providing directional information, are sensed by the eyes and that this sensory information is then transmitted to a sun compass system in the central brain. There, information from both eyes is integrated and time compensated by the circadian clock so that flight direction is constantly

adjusted to maintain a southerly bearing over the day. The monarch butterfly is an excellent model in which to study the time compensation process, because more is known about its circadian clock mechanism and clock cellular locations than in any other nondrosophilid insect ( Reppert, 2007). How are skylight cues used by migrating monarchs (Figure 1)? Flight simulator experiments have shown that the visibility of the outdoor sun, the most prominent light in the sky, is sufficient for proper orientation (Stalleicken et al., 2005). Moreover, other cues resulting from the scattering of sunlight, such as the pattern of polarized light and spectral gradients in the sky, also contain orientation information (Wehner, 2001 and Coemans et al., 1994) (Figure 1A).