Search

AbstractIn this study, we used a 4.00-m pit on Belukha glacier in Russia’s Altai region and attempted to establish the timing of chemical deposition events by analyzing pollen profiles. As the pollen deposition of each examined taxon on the glacier surfaces followed a distinct seasonal phenology, seasonal layers could be identified over a two-year period. The seasonal layer boundaries reconstructed from the pollen analyses were in close agreement with the in situobservations and indicated that the snow deposition on the glacier originates mainly from summer precipitation. The record of oxygen isotope ratios showed a relatively high mean value of −13.3‰, which was attributed to the absence of winter depositions. The formate (HCOO−) concentration records displayed seasonal variation with the highest emissions occurring in the spring, and a dust event in the spring of 2003 was detected from the Mg2+, Ca2+, and dust concentration profiles. Taken together, these results suggest the analysis of pollen profiles in combination with chemical data in snow pits and ice cores may lead to better reconstruction of seasonal variation.

The limited number of surface mass balance (SMB) observations in the Antarctic inland hampers estimates of ice‐sheet contribution to global sea level and locations with million‐year‐old ice. We present finely resolved SMB over the past three centuries in a low‐accumulation region with significant depth hoar formation on Dome Fuji derived from ∼1,100 km of microwave radar stratigraphy dated with a firn core. The regional‐mean SMB over the past 264 years is estimated to ∼22.5 ± 3.3 kg m−2a−1, but with large local variability of up to 30%. We found that local SMB is negatively correlated with surface slope at scales of a few hundred meters, resulting in anomalous zones of low SMB which represent as much as 8–10% of the total SMB on the inland plateau if the SMB‐slope relationship is more widely valid. This impact should be investigated further to improve estimates of Antarctic mass balance and sea‐level contribution. Sampling the world's Oldest Ice (more than 1 million years) is crucial for understanding why pacing of glacier‐interglacial cycles has changed in the past. Such ice will be preserved at the base of the Antarctic ice‐sheet interior, though its location depends on many factors, including snow accumulation rate. We mapped snow accumulation in the Dome Fuji region, using radar‐detected snow layers dated with volcanic signals in ice cores. Although climate models indicate a very low and nearly uniform snow accumulation in this region, the observations show large variations of up to about 30% which we found to be related to local surface slope at a scale of a kilometer or less. This new knowledge contributes to better locate Oldest Ice and to improve estimates of ice‐sheet mass changes and its contributions to global sea level. Ultrawide band microwave radar reveals spatially highly variable surface mass balance (SMB) over the past three centuries in inland AntarcticaSMB anomalies resulting from local surface slopes may represent as much as 8–10% of the total SMB on the inland plateauThe new SMB data have direct implications for the search for million‐year‐old ice in the Dome Fuji area, East Antarctica Ultrawide band microwave radar reveals spatially highly variable surface mass balance (SMB) over the past three centuries in inland Antarctica SMB anomalies resulting from local surface slopes may represent as much as 8–10% of the total SMB on the inland plateau The new SMB data have direct implications for the search for million‐year‐old ice in the Dome Fuji area, East Antarctica

OBJECTIVE: To identify molecular mechanisms of retinal responses to intraocular pressure elevation in primate experimental glaucoma. METHODS: An experimental glaucoma model was created by repeated laser trabeculophotocoagulation. After the preparation of complementary DNAs from extracted total RNAs in the retinas, polymerase chain reaction (PCR) experiments were performed for the following screening target genes: β-tubulin β2 and β5 and glial fibrillary acidic protein (GFAP). To investigate the amplified sequences derived from the PCR experiments, sequencing, subcloning, and Southern blot analysis of PCR products were performed. In addition, an immunohistochemical analysis was performed in an attempt to show the distribution of the target gene products in the retinas. RESULTS: A series of PCR experiments suggested up-regulation of gene expression for GFAP but not for β-tu bulins. Sequencing of the PCR products and results of the Southern blot analysis showed that the amplified sequences were derived mainly from the target gene, GFAP, and that increased expression of GFAP was found despite the severity of glaucoma. Immunohistochemical studies also demonstrated increased expression of GFAP proteins in Müller cells and astrocytes in the retinas of primate eyes with experimental glaucoma. CONCLUSION: Our study showed up-regulation of GFAP at gene and protein levels, which suggests that glial components in the retina may contribute to the pathologic processes induced by elevated intraocular pressure.