Glial Hsp70 Protects K+ Homeostasis in the Drosophila Brain during Repetitive Anoxic Depolarization

Neural tissue is particularly vulnerable to metabolic stress and loss of ion homeostasis. Repetitive stress generally leads to more permanent dysfunction but the mechanisms underlying this progression are poorly understood. We investigated the effects of energetic compromise in Drosophila by targeting the Na+/K+-ATPase. Acute ouabain treatment of intact flies resulted in subsequent repetitive comas that led to death and were associated with transient loss of K+ homeostasis in the brain. Heat shock pre-conditioned flies were resistant to ouabain treatment. To control the timing of repeated loss of ion homeostasis we subjected flies to repetitive anoxia while recording extracellular [K+] in the brain. We show that targeted expression of the chaperone protein Hsp70 in glial cells delays a permanent loss of ion homeostasis associated with repetitive anoxic stress and suggest that this is a useful model for investigating molecular mechanisms of neuroprotection

Climate variability during the past 2,000 years and past economic and irrigation activities in the Aral Sea basin

International audienceThe lake level history, here based on the relative abundance of Ca (gypsum), is used for tracing past hydrological conditions in Central Asia. Lake level was close to a minimum before approximately A.D. 300, at about A.D. 600, A.D. 1220, A.D. 1400 and since 1960s it is lowering again. Lake water level was lowest during the fourteenth or early fifteenth centuries as indicated by a coeval settlement, which today is still under water near the well-dated mausoleum of Kerderi. Pollen data from riparian vegetation indicate generally wet conditions between A.D. 400 and A.D. 900, intermitted by short intervals with drier conditions (AD 550–600; A.D. 650–700) and riverbanks were again dry from A.D. 900–1150, A.D. 1450–1550, and from A.D. 1970 onward moisture decreased steadily. Irrigation activities were at a maximum between 300 B.C. and A.D. 300 (Classical Antiquity) and between A.D. 800 and A.D. 1300 (Medieval Age) and after A.D. 1960