There were three negative seawater strontium-isotope excursions (shifts to lower Sr/Sr values) during the Jurassic and Cretaceous that were of relatively short duration (5-13 my) and showed a relatively quick recovery to pre-excursion Sr/Sr ratios. These excursions occurred in the Pliensbachian-Toarcian (Early Jurassic), Aptian-Albian, and Cenomanian-Santonian (Early and Late Cretaceous respect...

The role of pH and protein kinase second messengers in triggering or potentiating anoxia-linked changes in enzyme binding to particulate matter were evaluated using in vitro incubations of isolated ventricle strips of Busycon canaliculatum (L.) (Prosobranchia, Melongenidae). Incubating whelks under anoxic conditions for 4h reduced the percentage of phosphofructokinase (PFK), aldolase, glycerald...

Cardiovascular control in cold-acclimated freshwater turtles during chronic anoxic exposure is not well understood. We tested the hypothesis that the observed bradycardia in Trachemys scripta results from increased cholinergic inhibitory tone and reduced sympathetic activity. Cardiovascular status was measured in vivo in turtles acclimated to either 22 degrees C or 5 degrees C and either acutel...

In this paper the advantages and disadvantages of denitrifying PAOs (polyphosphate accumulating organisms) in conventional BNRAS (biological nutrient removal activated sludge) and external nitrification BNRAS (ENBNRAS) systems are evaluated, with experimental data exhibiting a range of anoxic P uptake from low (<10%) to very high (>60%). The results indicate that the specific denitrification ra...

Simultaneous nitrification/denitrification and trace organic contaminant (TrOC) removal during wastewater treatment by an integrated anoxic-aerobic MBR was examined. A set of 30 compounds was selected to represent TrOCs that occur ubiquitously in domestic wastewater. The system achieved over 95% total organic carbon (TOC) and over 80% total nitrogen (TN) removal. In addition, 21 of the 30 TrOCs...

Excitotoxicity in brain ischemia triggers neuronal death and neurological disability, and yet these are not prevented by antiexcitotoxic therapy (AET) in humans. Here, we show that in neurons subjected to prolonged oxygen glucose deprivation (OGD), AET unmasks a dominant death mechanism perpetuated by a Ca2+-permeable nonselective cation conductance (IOGD). IOGD was activated by reactive oxygen...

The response of free nitrous acid (FNA)-adapted poly-phosphate accumulating organisms (PAOs) to FNA inhibition under aerobic and anoxic conditions was studied. Anoxic P-uptake was 1-6 times more sensitive to the inhibition compared to aerobic P-uptake. The aerobic nitrite reduction rate increased with FNA concentration, accompanied by an equivalent decrease in the oxygen uptake rate, suggesting...

This experimental work has been carried out with the aim of studying the ultrastructural myocardial changes caused by prolonged anoxic cardiac arrest during cardiopulmonary bypass, and their prevention by means of two different techniques of coronary perfusion--systemic-pressure continuous and low-pressure intermittent perfusion. After 30 minutes of cardiac anoxia, the ultrastructural changes o...

In Lake Matano, Indonesia, the world's largest known ferruginous basin, more than 50% of authigenic organic matter is degraded through methanogenesis, despite high abundances of Fe (hydr)oxides in the lake sediments. Biogenic CH₄ accumulates to high concentrations (up to 1.4 mmol L⁻¹) in the anoxic bottom waters, which contain a total of 7.4 × 10⁵ tons of CH₄. Profiles of dissolved inorganic ca...

For most vertebrates, cutting off the oxygen supply to the brain results in a rapid (within minutes) loss of ATP, the failure of ATP-dependent ion-transport process, subsequent anoxic depolarization of neuronal membrane potential and consequential neuronal death. The few species that survive brain anoxia for days or months, such as the freshwater turtle Trachemys scripta, avoid anoxic depolariz...