Murine GRXCR1 Has a Different Function Than GRXCR2 in the Morphogenesis of Stereocilia

Mutations in human glutaredoxin domain-containing cysteine-rich protein 1 (GRXCR1) and its paralog GRXCR2 have been linked to hearing loss in humans. Although both GRXCR1 and GRXCR2 are required for the morphogenesis of stereocilia in cochlear hair cells, a fundamental question that remains unclear is whether GRXCR1 and GRXCR2 have similar functions in hair cells. Previously, we found that GRXCR2 is critical for the stereocilia morphogenesis by regulating taperin localization at the base of stereocilia. Reducing taperin expression level rescues the morphological defects of stereocilia and hearing loss in Grxcr2-deficient mice. So far, functions of GRXCR1 in mammalian hair cells are still unclear. Grxcr1-deficient hair cells have very thin stereocilia with less F-actin content inside, which is different from Grxcr2-deficient hair cells. In contrast to GRXCR2, which is concentrated at the base of stereocilia, GRXCR1 is diffusely distributed throughout the stereocilia. Notably, GRXCR1 interacts with GRXCR2. In Grxcr1-deficient hair cells, the expression level of GRXCR2 and taperin is reduced. Remarkably, different from that in Grxcr2-deficient mice, reducing taperin expression level does not rescue the morphological defects of stereocilia or hearing loss in Grxcr1-deficient mice. Thus, our findings suggest that GRXCR1 has different functions than GRXCR2 during the morphogenesis of stereocilia.

Cretaceous amniote integuments recorded through a taphonomic process unique to resins

Fossil records of vertebrate integuments are relatively common in both rocks, as compressions, and amber, as inclusions. The integument remains, mainly the Mesozoic ones, are of great interest due to the panoply of palaeobiological information they can provide. We describe two Spanish Cretaceous amber pieces that are of taphonomic importance, one bearing avian dinosaur feather remains and the other, mammalian hair. The preserved feather remains originated from an avian dinosaur resting in contact with a stalactite-shaped resin emission for the time it took for the fresh resin to harden. The second piece shows three hair strands recorded on a surface of desiccation, with the characteristic scale pattern exceptionally well preserved and the strands aligned together, which can be considered the record of a tuft. These assemblages were recorded through a rare biostratinomic process we call “pull off vestiture” that is different from the typical resin entrapment and embedding of organisms and biological remains, and unique to resins. The peculiarity of this process is supported by actualistic observations using sticky traps in Madagascar. Lastly, we reinterpret some exceptional records from the literature in the light of that process, thus bringing new insight to the taphonomic and palaeoecological understanding of the circumstances of their origins.

Cuticular and Medullary Structure of Some Wild Herbivoresof India

The dorsal guard hair is considered as a mammalian exoskeleton. The anatomical feature of the three concentric layers of the mammalian hair, viz., medulla, cortex, and cuticle vary considerably with different species. The characteristics features of cuticular scales and medullary pattern can be used as an important tool for species identification by using various methods for hair analysis. The morphological features of cuticle and medulla of dorsal guard hair samples of Sambar (Rusa unicolor), Nilgai/blue bull (Boselaphus tragocamelus) and Spotted deer (Axix axis), six each, were studied during post-mortem examination. The microscopic studies showed a difference in some of the cuticular scale and medullar cells among three species. Hence, a single morphological feature of hair may not be a confirmative tool for species identification but multiple morphological features can be used as a confirmative tool of species identification. This study provides pictographic details in eead of some wild species which can be used to curb criminal acts against wild animals.

ANIDACIÓN DEL GORRIÓN CRIOLLO ZONOTRICHIA CAPENSIS (EMBERIZIDAE) EN QUITO, ECUADOR

Incrementar información sobre la biología reproductiva siempre es útil para evidenciar patrones. En este trabajo presento los detalles de un nido del Gorrión Criollo Zonotrichia capensis en forma de taza abierta, construido principalmente con fibras vegetales y una cubierta interior de pelos de mamífero, observado entre noviembre 2015 y julio 2016. El nido fue construido en un macetero colgante en una casa de un barrio céntrico de la ciudad de Quito. Dos huevos de color celeste pálido con manchas pardas fueron incubados durante 14 días. Estimé un periodo de 11 días de construcción del nido, 2 días de puesta y 14 de empollamiento.Palabras clave: Chingolo, huevos, incubación, nido, pichones, Quito, reproducción. Nesting of Rufous-collared Sparrow Zonotrichia capensis (Emberizidae) in Quito, EcuadorAbstractIncreasing information about the breeding biology of bird species is useful for evidencing patterns. In this study, I present observations of an open cup nest of Rufous-collared Sparrow Zonotrichia capensis, built primarily with plant fibers and an inner lining mammalian hair, which was observed from November 2015 through July 2016. The nest was built in a pendant flowerpot at a house located in the downtown of Quito. Two pale bluish eggs speckled with brown were incubated. I estimated a period of 11 days for nest building, 2 days for egg laying, 14 days for incubation, and 14 days for brooding.Keywords: breeding, eggs, incubation, nest, nestlings, Quito, Rufous-collared Sparrow.