Review of Statoconia Formation in Birds and Original Research in Chicks (Gallus domesticus)

This paper reviews published materials on statoconia formation in birds, and emphasizes works dealing with the embryonic chick (Gallus domesticus) saccule and utricule. Histological, biochemical and histochemical aspects of forming statoconial membranes and statoconial crystals of mammals are included. Results from our work with chick embryos permitted us to conclude that statoconia probably do not form by seeding of a subunit around central core. Instead, immature statoconia may emerge already formed, from a segmenting mass of organic material that seems to be secreted by the supporting cells of the saccular and utricular maculae. Crystallization of each statoconium may involve seeding of multiple subunits around many nucleation centers in the organic matrix. Following these processes, calcium (sometimes granular) attaches to immature statoconia and become subsequently incorporated between the fibrils of the organic matrix starting at the peripheral zone and advancing toward the central core. Our transmission electron microscopy findings, histochemistry and X-ray microanalysis complements of other investigators, who used chicks with light microscopic studies. These results agree with the notion that the secretion of an organic matrix constitutes the first step toward the formation of the statoconial membrane and statoconia. We show ultra-structurally how statoconia may be assembled from the organic matrix before they acquire their characteristic geometric shapes

High temporal resolution chemical analysis of H72 ice core in east Dronning Maud Land, Antarctica

The H72 ice core collected in east Dronning Maud Land, Antarctica has been analyzed in detail. Concentrations of Na^+ and Cl^- indicate the highest correlation coefficients, so we can say that both ions in the H72 ice core originated from sea salt. The fluctuation pattern of δ18O below the depth of 45m proves that the δ^(18)O distribution is smoothed by water vapor diffusion in the firn layer. An increasing tendency of NO_3^- and nssSO_4^(2-) concentrations in the shallow layer has not been found in the H72 ice core. The H72 ice core is dated as AD 1837 by the periodic concentration fluctuation of MSA at 73.29m depth. Volcanic signals are detected in 49 layers in the H72 ice core. In the late 19th century many volcanic eruptions were recorded, which explains why many volcanic signals are present in the H72 ice core. It is noted that a year with low temperatures in winter and a low annual minimum δ^(18)O will have high surface mass balance and more snowfall. Considerable nssSO_4^(2-) has been released into the atmosphere by human activity in the 20th century, but we cannot find traces of a recent increase in deposition of nssSO_4^(2-) at the H72 site

Picosecond carrier dynamics induced by coupling of wavefunctions in a Si-nanodisk array fabricated by neutral beam etching using bio-nano-templates

The picosecond carrier dynamics in a closely packed Si-nanodisk (Si-ND) array with ultrathin potential barrier fabricated by neutral beam etching using bio-nano-templates was investigated by time-resolved photoluminescence (PL). The PL decay curves were analyzed as a function of photon energy by the global fitting method. We show three spectral components with different decay times, where the systematic energy differences of the spectral peaks are clarified: 2.03 eV for the fastest decaying component with a decay time τ = 40 ps, 2.02 eV for τ = 300 ps, and 2.00 eV for τ = 1.6 ns. These energy separations ranging from 10 to 30 meV among the emissive states can be attributed to the coupling of wavefunctions of carriers between neighboring NDs

New chemically induced skin tumour susceptibility loci identified in a mouse backcross between FVB and dominant resistant PWK

<p>Abstract</p> <p>Background</p> <p>A variety of skin cancer susceptibility among mouse strains has allowed identification of genes responsible for skin cancer development. Fifteen <it>Skts </it>loci for skin tumour susceptibility have been mapped so far by using the two-stage skin carcinogenesis model [induced by 7.12-dimethylbenz(a)anthracene (DMBA)/12-O-tetradecanoylphorbol-13-acetate (TPA)]. A few responsible genes have been identified using wild-derived dominant resistant <it>Mus spretus </it>mice, and one has been confirmed as a low penetrance cancer susceptibility gene in a variety of human cancers.</p> <p>Results</p> <p>In the present study, we found that wild-derived PWK mice developed no tumour by treatment with the two-stage skin carcinogenesis protocol. This phenotype is dominant resistant when crossed with the highly susceptible strain FVB. By analyzing the F1 backcross generation between PWK and FVB, we found empirical evidence of significant linkage at the new loci <it>Skts-fp1 </it>on chromosome 4 and suggestive linkage on chromosomes 1, 3, 11, 12 and 14 for skin tumour susceptibility. <it>Skts-fp1 </it>includes the <it>Skts7 </it>interval, which was previously mapped by a <it>Mus spretus </it>and NIH backcross. We also observed suggestive linkage on chromosomes 1 and 2 in the female population only, while suggestive linkage on chromosomes 14 and 15 only was observed in the male population. A significant genetic interaction was seen between markers of <it>D11Mit339</it> and <it>D16Mit14</it>.</p> <p>Conclusion</p> <p>Analysis of this new cross may facilitate the identification of genes responsible for mouse skin cancer susceptibility and may reveal their biological interactions.</p

Periodicities of palaeo-climatic records extracted from the Dome Fuji deep core

The Antarctic ice sheet preserves palaeo-climate information in the form of physical and chemical stratigraphy. A deep ice core was continuously drilled down to a depth of 2503m at Dome Fuji Station, East Dronning Maud Land, Antarctica, during the 1993-97 JARE inland operations. A time scale for the Dome Fuji core is calculated from past accumulation rates and an ice flow model. A depth-age profile was obtained for the past 320kyr back in time. The obtained palaeo-temperature profile shows the past three glacial and interglacial periods. The power spectrum for oxygen isotope variation for 320kyr shows three dominant cycles of 107kyr, 40kyr and 21kyr. Each of these three cycles is similar to Milankovitch cycles. Moving-window spectrum analysis, using a 130kyr window stepped by 10kyr over the past 320kyr, found these main cycles in every age. Variations of other chemical concentrations were also recovered from the Dome Fuji ice core, and are inversely correlated to the temperature profile. Concentrations of terrestrial and marine origin substances are high in glacial periods, and low in interglacial periods. Over the past 320kyr, the dominant periodicities of temperature were also detected in almost all chemical records