A protocol for using attenuated total reflection Fourier-transform infrared spectroscopy for pre-screening ancient bone collagen prior to radiocarbon dating.

Rationale: Pre-screening of bone collagen quality is important to reduce the cost for analyses such as radiocarbon ( C) dating with accelerator mass spectrometry in archaeological studies. We developed a pre-screening protocol based on attenuated total reflection (ATR) Fourier-transform infrared spectroscopy (FTIR) for assessing the chemical composition and mineralogy of ancient bone samples.

Methods: ATR-FTIR measurements were performed on bulk bones of diverse origin and age before collagen extraction.

Improved Method for Isolation and Purification of Underivatized Amino Acids for Radiocarbon Analysis.

We have improved a method for isolation and purification of individual amino acids for compound-specific radiocarbon analysis (CSRA). To remove high-performance liquid chromatography (HPLC) eluent blanks from isolated amino acid fractions prior to the radiocarbon (ΔC) measurement, each fraction was filtered through a membrane filter and then washed with diethyl ether twice. Radiocarbon measurements on standard amino acids processed and purified with the above method using elemental analyzer-accelerator mass spectrometry resulted in ΔC values that were in strong agreement ( R = 0.

Widespread collapse of the Ross Ice Shelf during the late Holocene.

The stability of modern ice shelves is threatened by atmospheric and oceanic warming. The geologic record of formerly glaciated continental shelves provides a window into the past of how ice shelves responded to a warming climate. Fields of deep (-560 m), linear iceberg furrows on the outer, western Ross Sea continental shelf record an early post-Last Glacial Maximum episode of ice-shelf collapse that was followed by continuous retreat of the grounding line for ∼200 km.

Exposure age and ice-sheet model constraints on Pliocene East Antarctic ice sheet dynamics.

The Late Pliocene epoch is a potential analogue for future climate in a warming world. Here we reconstruct Plio-Pleistocene East Antarctic Ice Sheet (EAIS) variability using cosmogenic nuclide exposure ages and model simulations to better understand ice sheet behaviour under such warm conditions. New and previously published exposure ages indicate interior-thickening during the Pliocene.

Relationship between uterine morphology and peripheral concentrations of sex steroid hormone in wild Japanese black bears (Ursus thibetanus japonicus).

Developing a better understanding of the reproductive physiology and breeding condition peculiar to wild Japanese black bears (Ursus thibetanus japonicus) is crucial for estimation of their habitat distribution. The aim of this study was to clarify the changes in morphology of the genital organs, cellular proliferation in the endometrium and sex steroid hormone concentrations along with the reproductive cycle in Japanese black bears. Samples were collected from a total of 24 female Japanese black bears (1-15 presumptive years old) that were caught in the wild in Iwate prefecture during the period between August 1999 and September 2005.

Rac1 activity is required for cardiac myocyte alignment in response to mechanical stress.

Mechanical stretch is essential for the cardiac growth. The exposure of cardiac myocytes to the mechanical stretch leads to the cell alignment in parallel to the stretch direction, determining the cell polarity, though it remains to be addressed how mechanical stretch regulates cell orientation. In the present study, we investigated the signal transduction pathways responsible for the cell orientation response to mechanical stretch, focusing on Rho family proteins.

N-cadherin signals through Rac1 determine the localization of connexin 43 in cardiac myocytes.

It has been proposed that the formation of gap junction is influenced by adherens junction in cardiac myocytes. To examine whether signals through N-cadherin are involved in the distribution of connexin 43 (Cx43), the distribution of cell-cell adhesion molecules, N-cadherin and Cx43, was analyzed in aligned cardiac myocytes. To induce cell orientation running in parallel to tension direction, neonatal rat cardiac myocytes were plated for 3 hours and exposed to 20% cyclic stretch for 24 hours on silicone dishes.

Platelet activating factor induces cytoskeletal reorganization through Rho family pathway in THP-1 macrophages.

In the process of atherosclerosis, platelet activating factor (PAF) promotes the infiltration of inflammatory cells into atherosclerotic plaque by modulating their cytoskeleton. Here, we examined whether Rho family proteins are involved in PAF-induced cytoskeletal reorganization in THP-1 macrophages. PAF stimulation rapidly induced cell elongation, accompanied by filopodia formation.