Analytical methods for the geometric optics of thermal vision illustrated with four species of pitvipers.

The pitviper facial pit is a pinhole camera-like sensory organ consisting of a flask-shaped cavity divided into two chambers by a suspended membrane. Neurophysiological studies and simplified optical models suggest that facial pits detect thermal radiation and form an image that is combined with visual input in the optic tectum to form a single multispectral image. External pit anatomy varies markedly among taxonomic groups. However, optical function depends on unknown internal anatomy. Therefore, we developed methods for relating anatomy to optical performance. To illustrate, we constructed detailed anatomical models of the internal anatomy of the facial pits of four individuals of four pitviper species using X-ray tomography sections of fresh material. We used these models to define the point spread function, i.e. the distribution of radiation from a point source over the pit membrane, for each species. We then used optical physics, heat transfer physics and computational image processing to define the thermal image formed on the pit membrane for each species. Our computed pit membrane images are consistent with behavioral observations if the sensitivity of membrane receptors equals the most sensitive (ca. 0.001°C) laboratory estimates. Vignetting (variation in optical aperture size with view angle) and differences between body and environmental temperatures can create temperature variation across the membrane that greatly exceeds image temperature contrasts, potentially impairing imaging. Spread functions plotted versus source point azimuth and elevation show distinct patterns that suggest new research directions into the relationships among the optical anatomy, ecology, behavior and sensory neurophysiology of pitvipers.

DP58, an inducible myeloid protein, is constitutively expressed in murine neuronal nuclei.

A novel cytosolic phosphoprotein, DP58 induced in bone marrow-derived dendritic progenitors was found in this study to be constitutively expressed at a very high level in neuronal nuclei. Amplified cDNA confirmed by sequencing to be DP58 was present only in brain tissue, and DP58-like protein was expressed in neurons as a 52 kDa nuclear protein, phosphorylated primarily at the serine residues. In contrast, its isoform in dendritic progenitors appeared as a 58 kDa inducible protein with phosphorylation at serine, threonine and tyrosine residues. Although protein markers common to brain and hematopoietic cells are known, no report was found on constitutive expression in neuronal nuclei of DP58, an inducible Pro-myloid marker. The sequence of DP58 reveals ankyrin repeats present in a wide spectrum of interacting proteins including NF-kappaB-binding BCL3, a predominantly nuclear protein of I-kappaB family. The contrasting phosphorylated forms of DP58 suggest a distinct physiological role in neuronal cells and early dendritic progenitors.