Abstract. Photoacoustic tomography is a hybrid modality based on optical absorption excitation and ultrasonic detection. It is sensitive to melanin, one of the primary absorbers in skin. For cells that do not naturally contain melanin, melanin production can be induced by introducing the gene for tyrosinase, the primary enzyme responsible for expression of melanin in melanogenic cells. Optical resolution photoacoustic microscopy was used in the ex vivo study reported here, where the signal from transfected cells increased by more than 10 times over wild-type cells. A subsequent in vivo experiment was conducted to demonstrate the capability of photoacoustic microscopy to spectrally differentiate between tyrosinase-catalyzed melanin and various other absorbers in tissue. C 2011 Society of Photo-Optical Instrumentation Engineers (SPIE).

Cryptochrome (CRY) is the primary circadian photoreceptor in Drosophila. It resets the circadian clock by promoting lightinduced degradation of the clock proteins Timeless and Period, as well as its own proteolysis. The E3 ligases that ubiquitylate Timeless and Period before degradation are known and it is known that Drosophila (d) CRY is degraded by the ubiquitin-proteasome system as well. To identify the E3 ligase for dCRY we screened candidates in S2 cells by RNAi. Knockdown of each of the 25 putative F-box proteins identified by bioinformatics did not attenuate the light-induced degradation of dCRY. However, knockdown of a WD40 protein, Bromodomain and WD repeat domain containing 3 (Brwd3) (CG31132/Ramshackle) caused strong attenuation of dCRY degradation following light exposure. We found that BRWD3 functions as a Damage-specific DNA binding protein 1 (DDB1)-and CULLIN (CUL)4-associated factor in a Cullin4-RING Finger E3 Ligase (CRL4) that mediates light-dependent binding of dCRY to CUL4-ROC1-DDB1-BRWD3, inducing ubiquitylation of dCRY and its lightinduced degradation. Thus, this study identifies a light-activated E3 ligase complex essential for light-mediated CRY degradation in Drosophila cells.circadian rhythm | sensory flavoprotein | photocycle

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Structural congenital heart disease (CHD) has not previously been linked to autoimmunity. In our study, we developed an autoimmune model of structural CHD that resembles hypoplastic left heart syndrome (HLHS), a life-threatening CHD primarily affecting the left ventricle. Because cardiac myosin (CM) is a dominant autoantigen in autoimmune heart disease, we hypothesized that immunization with CM might lead to transplacental passage of maternal autoantibodies and a prenatal HLHS phenotype in exposed fetuses. Elevated anti-CM autoantibodies in maternal and fetal sera, and IgG reactivity in fetal myocardium were correlated with structural CHD that included diminished left ventricular cavity dimensions in the affected progeny. Further, fetuses that developed a marked HLHS phenotype had elevated serum titers of anti-β adrenergic receptor antibodies as well as increased protein kinase A activity, suggesting a potential mechanism for the observed pathological changes. Our maternal-fetal model presents a new concept linking autoimmunity against CM and cardiomyocyte proliferation with cardinal features of HLHS. This report shows the first evidence to support a novel immune-mediated mechanism for pathogenesis of structural CHD that may have implications in its future diagnosis and treatment.