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Branchio-oto-renal syndrome, a phenotype consisting of hearing loss, auricular malformations, branchial arch remnants, and renal anomalies is now recognized as one of the more common forms of autosomal dominant syndromic hearing impairment. Three loci known to be associated with the BOR phenotype have been identified and two genes that act in a regulatory network have been cloned, EYA1 and SIX1. EYA1 and SIX1 are homologous to genes involved in Drosophila eye development, eyes absent gene (eya), and sine oculis (so), respectively. EYA1, a transcriptional co-activator has a conserved, 271-amino acid, C-terminal known as the Eya Domain (ED). SIX1 has two highly conserved domains; a homeodomain (HD) and a specific Six-domain (SD) whose products function as transcription factors with specific DNA-binding activity that are crucial for protein-protein interaction. To determine the molecular basis for the organ defects that occur in BOR syndrome, many studies have focused on the effects of mutations to EYA and effects of mutations of the EYA-SIX regulatory system. However, over 60% of BOR syndrome patients do not have known mutations in EYA1 and relatively little is known about mutations to SIX1. Further evaluation of SIX1 and its related target genes may provide a better understanding of the pathophysiology of BOR syndrome and offer greater clues to the disease mechanisms.

The cooling of vibrationally hot azulene is studied in different solvents by picosecond spectroscopy. Excitation to the electronic S1 state generates molecules with a vibrationally hot ground state by rapid internal conversion. The subsequent cooling is monitored by the temperature-dependent change of the S0–S1 absorption edge and occurs via interaction with the solvent on a time scale of several tens of picoseconds. A theoretical model of intermolecular energy transfer in the liquid phase is developed. The vibrational excess energy of azulene is transferred to the solvent molecules by isolated binary collisions, where the multimode vibrational system of the molecules is considered explicitly. The dissipation of energy within the solvent is simulated by the macroscopic conduction of heat. The temporal development of the vibrational temperature of the azulene molecules and the concommitant changes of absorption are calculated taking into account the properties of the specific solvent. The results of the theory show quantitative agreement with our data.

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Absorption spectra and light-induced absorbance changes of crystals from Rhodopseudomonas viridis reaction centers are recorded. A theoretical analysis of the absorption and circular dichroism spectra is presented, yielding a consistent picture of spectroscopic and structural information.The primary process in bacterial photosynthesis involves a light-driven electron transfer across a membrane. It is catalyzed by a protein-pigment complex, the photosynthetic reaction center (RC). The chemical nature and pigment composition are known for a number of RCs (1-4). The RC from the purple photosynthetic bacterium Rhodopseudomonas viridis was crystallized (5); the RCs in those crystals are photochemically active (6). Recently, an x-ray structure analysis at 3 A resolution provided the detailed arrangement of the pigments in the RC (7) [four bacteriochlorophyll b (BC), two bacteriopheophytin b (BP), and four heme groups]. The heme groups are bound to a c-type cytochrome. The BCs and BPs are associated with the protein subunits L and M, respectively, and are indexed in this paper by L and M accordingly. These pigments are arranged in two branches, which exhibit an approximate 2-fold rotation symmetry (7). At the axis of rotation, two BCs interact closely (Mg-Mg distance, -7 A) with their pyrrole rings I stacked on top of each other. They form the special pair and are denoted BCLP and BCMP. Next to the special pair are the so-called accessory monomers BCLA and BCMA. The Mg-Mg distance between the BC in the same branch is =11 A. In close proximity to the BCAS are the two BPs at the end of the branches. The distance of the ring centers of BP and BCA from the same branch is -11 A. The approximate 2-fold rotation symmetry is broken by the presence of only one quinone, probably menaquinone, at the end of the L branch; apparently, the RC's second quinone was lost during purification or crystallization.In this paper, we investigate absorption spectra and absorbance changes after illumination with actinic light by using single crystals of different orientations. This yields a considerable increase of information as compared to spectra from RC in solution. Circular dichroism (CD) spectra of reaction centers in solution are also considered (8, 9). The spectra are analyzed by using the structural information of the RCs