GABA transporters mediate glycine release from cerebellum nerve endings: roles of Ca(2+)channels, mitochondrial Na(+)/Ca(2+) exchangers, vesicular GABA/glycine transporters and anion channels

GABA transporters accumulate GABA to inactivate or reutilize it. Transporter-mediated GABA release can also occur. Recent findings indicate that GABA transporters can perform additional functions. We investigated how activation of GABA transporters can mediate release of glycine. Nerve endings purified from mouse cerebellum were prelabeled with [(3)H]glycine in presence of the glycine GlyT1 transporter inhibitor NFPS to label selectively GlyT2-bearing terminals. GABA was added under superfusion conditions and the mechanisms of the GABA-evoked [(3)H]glycine release were characterized. GABA stimulated [(3)H]glycine release in a concentration-dependent manner (EC(50) = 8.26 μM). The GABA-evoked release was insensitive to GABA(A) and GABA(B) receptor antagonists, but it was abolished by GABA transporter inhibitors. About 25% of the evoked release was dependent on external Ca(2+) entering the nerve terminals through VSCCs sensitive to ω-conotoxins. The external Ca(2+)-independent release involved mitochondrial Ca(2+), as it was prevented by the Na(+)/Ca(2+) exchanger inhibitor CGP37157. The GABA uptake-mediated increases in cytosolic Ca(2+) did not trigger exocytotic release because the [(3)H]glycine efflux was insensitive to clostridial toxins. Bafilomycin inhibited the evoked release likely because it reduced vesicular storage of [(3)H]glycine so that less [(3)H]glycine can become cytosolic when GABA taken up exchanges with [(3)H]glycine at the vesicular inhibitory amino acid transporters shared by the two amino acids. The GABA-evoked [(3)H]glycine efflux could be prevented by niflumic acid or NPPB indicating that the evoked release occurred essentially by permeation through anion channels. In conclusion, GABA uptake into GlyT2-bearing cerebellar nerve endings triggered glycine release which occurred essentially by permeation through Ca(2+)-dependent anion channels. Glial GABA release mediated by anion channels was proposed to underlie tonic inhibition in the cerebellum; the present results suggest that glycine release by neuronal anion channels also might contribute to tonic inhibition.     

Inhibition of acid-catalyzed depolymerization of cellulose with boric acid in non-aqueous acidic media

Boric acid inhibited the acid-catalyzed depolymerization of cellulose in sulfolane, a non-aqueous medium, at high temperature. Formation of the dehydration products such as levoglucosenone, furfural, and 5-hydroxymethyl furfural were also effectively inhibited. Similar inhibition was observed for cellooligosaccharides and starch, although the glucosidic bonds in methyl glucopyranosides and methyl cellobioside were cleaved to form alpha-d-glucofuranose cyclic 1,2:3,5-bisborate.     

Cyclic sedimentation across a Middle Ordovician carbonate ramp (Duwibong Formation), Korea

Summary The Middle Ordovician Duwibong Formation (about 100 m thick), Korea, comprises various lithotypes deposited across a carbonate ramp. Their stacking patterns constitute several kinds of meter-scale, shallowing-upward carbonate cycles. Lithofacies associations are grouped into four depositional facies: deep- to mid-ramp, shoal-complex, lagoonal, and tidal-flat facies. These facies are composed of distinctive depositional cycles: deep subtidal, shallow subtidal, restricted marine, and peritidal cycles, respectively. The subtidal cycles are capped by subtidal lithofacies and indicate incomplete shallowing to the peritidal zone. The restricted marine and peritidal cycles are capped by tidal flat lithofacies and show evidence of subaerial exposure. These cycles were formed by higher frequency sea-level fluctuations with durations of 120 ky (fifth order), which were superimposed on the longer term sea-level events, and by sediment redistribution by storm-induced currents and waves. The stratigraphic succession of the Duwibong Formation represents a general regressive trend. The vertical facies change records the transition from a deep- to mid-ramp to shoal, to lagoon, into a peritidal zone. The depositional system of the Duwibong Formation was influenced by frequent storms, especially on the deep ramp to mid-ramp seaward of ooid shoals. The storm deposits comprise about 20% of the Duwibong sequence.     

Stratigraphy and geologic history of a southeastern salt marsh basin,North Inlet,South Carolina,USA

Forty seven vibracores and fifteen radiocarbon dates have beenobtained to outline the Holocene history of the North Inlet saltmarsh basin. Marsh deposits date from about 3500 years BP and havetransgressed over a Late Pleistocene beach-ridge terrain that waspartly eroded by Late Holocene tidal channel meandering. Marsh mudalso has prograded southward over shallow subtidal estuarine Macomamuds which date from about 4500 years BP and which are stillaccumulating in adjacent Winyah Bay. The southward migration of themarsh environment probably is due to the southward migration ofboth North Inlet and the mouth of Winyah Bay. The stratigraphy ofthe North Inlet basin offers no evidence for Late Holocene sea-level oscillations.Application of this model of marsh history to the study long-term ecosystem succession driven by slowly rising sea level isdiscussed.     

Sedimentology of the Late Quaternary Wadi Hasa Marl Formation of Central Jordan: a record of climate variability

The sedimentary features and fossils within the Wadi Hasa Marl Formation coupled with optical luminescence chronology indicate alternating wet and dry periods have occurred on the Jordanian plateau since the last interglacial. The Jurf Ed Darawish Member rests unconformably on the Maastrichtian Muwaqqar Chalk Marl Formation and is composed predominantly of poorly sorted, clast-supported conglomerate. Palaeocurrents and clast composition indicate provenance from Cretaceous sedimentary rocks and Tertiary basalts to the west and southwest of the study site and the facies suggest a flashy alluvial depositional environment probably similar to the modern wadis. The overlying Burma Member consists of bedded grey-green clayey silts and marls with calcrete profiles, up to 1.2 m thick, and isolated gravel lenses. The fine-grained sediments contain charophytes, ostracods, bivalves and various species of gastropod indicating normal freshwater lacustrine conditions. The calcretes contain a poorly preserved fauna suggesting lacustrine deposition followed by subaerial exposure and pedogenesis. Three optical luminescence ages have been obtained from the Burma Member which suggest that the member ranges in age from >111 ka through to <40 ka. The facies variations are indicative of climatic fluctuations in Jordan during this period and human artefacts are found embedded in the sediments. This preliminary study suggests that the Late Quaternary central Jordan sedimentary record may preserve valuable evidence of complex climatic variation which will supplement the data from the Jordan Valley where tectonic activity complicates the sedimentary record.     

The impact of extreme run-off events from the Sakasagawa river on the Senjogahara ecosystem, Nikko National Park. V. The importance of adventitious root systems for burial tolerance of different tree species

We surveyed the morphological responses of tree species buried by alluvial deposits, and measured the physicochemical properties of alluvial materials which buried each of the individual trees, on Senjogahara moor, Nikko National Park, Japan. The results showed that these species had a different capcity to form adventitious roots.Malus toringo Sieb. individuals, which had survived in spite of heavy deposits over the past 10 years, developed many adventitious roots from the buried parts of their trunks. However,Larix kaempferi Carr. andBetula platyphylla Sukatchev var.japonica Hara, which both died in heavy deposit areas, were inferior toM. toringo in the formation of adventitious roots. From these facts, we presumed that the ability to develop adventitious roots contributed to the survival of trees and resulted in the difference in burial tolerance among each species. Adventitious roots tended to form in the depositional layers which consisted of fine particle size materials. It is thought that these layers prevent gas exchange between soil and air, causing a lack of oxygen to the rhizosphere. Thus, we concluded that adventitious roots have a physiological importance in reducing the obstruction, and in the survival of buried trees.     

Episodic development of Cambrian eocrinoid-sponge meadows in the Iberian Chains (NE Spain)

Summary The Lower-Middle Cambrian transition in the Iberian Chains (NE Spain) records a transgressive deposition from peritidal to open-shelf environments. This overall trangressive trend took place across an interval of syndepositional tectonic processes. which have been illustrated during late Bilbilian to Leonian times. The scarcity of building organisms in this areas seems to be directly related to a rhythmic influence of fine terrigenous decantation, which inhibited and interrupted the carbonate production. Only in the more proximal and quiet environments, the episodic establishment of stromatolitic boundstones is evidence. Eocrinoid-sponge meadows were developed in shallow subtidal environments, and were completed by the presence of trilobites, inarticulate brachiopods, hyoliths and Chancelloriid sclerites. The biggest accumulation rates associated to these complex meadow communities seem to be reflected by differential synsedimentary faulting processes.     

Methanogenic activity and biomass in Holocene permafrost deposits of the Lena Delta, Siberian Arctic and its implication for the global methane budget

Permafrost environments within the Siberian Arctic are natural sources of the climate relevant trace gas methane. In order to improve our understanding of the present and future carbon dynamics in high latitudes, we studied the methane concentration, the quantity and quality of organic matter, and the activity and biomass of the methanogenic community in permafrost deposits. For these investigations a permafrost core of Holocene age was drilled in the Lena Delta (72°22′N, 126°28′E). The organic carbon of the permafrost sediments varied between 0.6% and 4.9% and was characterized by an increasing humification index with permafrost depth. A high CH₄ concentration was found in the upper 4 m of the deposits, which correlates well with the methanogenic activity and archaeal biomass (expressed as PLEL concentration). Even the incubation of core material at −3 and −6°C with and without substrates showed a significant CH₄ production (range: 0.04–0.78 nmol CH₄ h⁻¹ g⁻¹). The results indicated that the methane in Holocene permafrost deposits of the Lena Delta originated from modern methanogenesis by cold‐adapted methanogenic archaea. Microbial generated methane in permafrost sediments is so far an underestimated factor for the future climate development.     

The Regime for Transboundary Hydrocarbon Deposits in the Maritime Delimitation Treaties and Other Related Agreements of Arctic Coastal States

This article assesses the treaty practice of the five Arctic Ocean coastal states and Iceland in dealing with the issue of transboundary hydrocarbon deposits as part of the conclusion of maritime delimitation and other related agreements. That practice suggests a number of different ways in which states deal with the issue of hydrocarbon deposits bisected by a maritime delimitation: (1) silence, (2) a standard unity of deposit clause, (3) more complex variations on the standard clause including framework agreements for the development of transboundary deposits, and (4) a delimitation line with some form of joint development zone. This article assesses the Arctic state practice within this typology seeking to supplement the existing literature which tends to focus on the North Sea and Southeast Asia.