Control of hydrogen concentrations by microbial sulfate reduction in two contrasting anoxic coastal sediments.

Introduction: Molecular hydrogen is produced by the fermentation of organic matter and consumed by organisms including hydrogenotrophic methanogens and sulfate reducers in anoxic marine sediment. The thermodynamic feasibility of these metabolisms depends strongly on organic matter reactivity and hydrogen concentrations; low organic matter reactivity and high hydrogen concentrations can inhibit fermentation so when organic matter is poor, fermenters might form syntrophies with methanogens and/or sulfate reducers who alleviate thermodynamic stress by keeping hydrogen concentrations low and tightly controlled. However, it is unclear how these metabolisms effect porewater hydrogen concentrations in natural marine sediments of different organic matter reactivities.

Thermal tolerance for the tropical clawed frog, Xenopus tropicalis with comments on comparative methods for amphibian studies.

Thermal tolerance data are important for identifying the potential range of non-native species following introduction and establishment. Such data are particularly important for understanding invasion risks of tropical species introduced to temperate climates and identifying whether they can survive outside tropical regions. A breeding population of the tropical clawed frog (Xenopus tropicalis) was recently discovered in west-central Florida, U.

Microbial activity in the marine deep biosphere: progress and prospects.

The vast marine deep biosphere consists of microbial habitats within sediment, pore waters, upper basaltic crust and the fluids that circulate throughout it. A wide range of temperature, pressure, pH, and electron donor and acceptor conditions exists-all of which can combine to affect carbon and nutrient cycling and result in gradients on spatial scales ranging from millimeters to kilometers. Diverse and mostly uncharacterized microorganisms live in these habitats, and potentially play a role in mediating global scale biogeochemical processes.

Evidence for microbial carbon and sulfur cycling in deeply buried ridge flank basalt.

Sediment-covered basalt on the flanks of mid-ocean ridges constitutes most of Earth's oceanic crust, but the composition and metabolic function of its microbial ecosystem are largely unknown. By drilling into 3.5-million-year-old subseafloor basalt, we demonstrated the presence of methane- and sulfur-cycling microbes on the eastern flank of the Juan de Fuca Ridge.

Pressurized laboratory experiments show no stable carbon isotope fractionation of methane during gas hydrate dissolution and dissociation.

The stable carbon isotopic ratio of methane (δ(13)C-CH(4)) recovered from marine sediments containing gas hydrate is often used to infer the gas source and associated microbial processes. This is a powerful approach because of distinct isotopic fractionation patterns associated with methane production by biogenic and thermogenic pathways and microbial oxidation. However, isotope fractionations due to physical processes, such as hydrate dissolution, have not been fully evaluated.

Measuring temporal variability in pore-fluid chemistry to assess gas hydrate stability: development of a continuous pore-fluid array.

A specialized pore-fluid array (PFA) sampler was designed to collect and store pore fluids to monitor temporal changes of ions and gases in gas hydrate bearing sediments. We tested the hypothesis that pore-fluid chemistry records hydrate formation or decomposition events and reflects local seismic activity. The PFA is a seafloor probe that consists of an interchangeable instrument package that houses OsmoSamplers, long-term pore-fluid samplers, a specialized low-dead volume fluid coupler, and eight sample ports along a 10 m sediment probe shaft.

An anaerobic methane-oxidizing community of ANME-1b archaea in hypersaline Gulf of Mexico sediments.

Sediments overlying a brine pool methane seep in the Gulf of Mexico (Green Canyon 205) were analyzed using molecular and geochemical approaches to identify geochemical controls on microbial community composition and stratification. 16S rRNA gene and rRNA clone libraries, as well as mcrA gene clone libraries, showed that the archaeal community consists predominantly of ANME-1b methane oxidizers; no archaea of other ANME subgroups were found with general and group-specific PCR primers. The ANME-1b community was found in the sulfate-methane interface, where undersaturated methane concentrations of ca.

Enhancement of orimulsion biodegradation through the addition of natural marine carbon substrates.

Orimulsion is a bitumen-based heavy fuel that is a less expensive alternative to traditional fuel oils. However, because its density is intermediate between that of freshwater and seawater, in the event of a spill, the fuel could strand in the sediments. Previous work indicated that only 0.

New ratiometric fluorescent calcium indicators with moderately attenuated binding affinities.

Mono-halogenated derivatives of the calcium indicators fura-2 and indo-1 were synthesized and their spectroscopic properties evaluated. Halogenation ortho or para to the bridging oxygen in the BAPTA nucleus had a more pronounced weakening effect on binding affinity than in the meta position in the fura derivatives. Two new excitation ratioable fluorescent calcium indicators, benzothiaza-1 and 2, were also synthesized.

Summary of the Seychelles child development study on the relationship of fetal methylmercury exposure to neurodevelopment.

The Seychelles Child Development Study is examining the association between fetal methylmercury exposure from a maternal diet high in fish and subsequent child development. The study is double blind and uses maternal hair mercury as the index of fetal exposure. An initial cross-sectional pilot study of 804 infants aged 1 to 25 months suggested that mercury may affect development.

Monitoring methylmercury during pregnancy: maternal hair predicts fetal brain exposure.

Autopsy brains were obtained from infants dying from a variety of causes within a few days of birth in a population exposed to methylmercury in fish. Infant and maternal blood and hair samples were also obtained. The concentration of total mercury in 6 major brain regions were highly correlated with maternal hair levels.

An analysis of autopsy brain tissue from infants prenatally exposed to methymercury.

Brains from 32 neonatal autopsies from the Seychelles were examined histologically and analyzed for mercury levels. Six brain regions were sampled: frontal and occipital cortex, temporal cortex with hippocampus, basal ganglia with thalamus, cerebellum, and pons with medulla. Tissue blocks for histology and mercury analysis were taken from opposing faces to provide for correlation of findings.

Acute cerebellar hemorrhage secondary to capillary telangiectasia in an infant. A case report.

We encountered an unusual case of an acute cerebellar hemorrhage secondary to a capillary telangiectasia in a 4-month-old infant. Prompt surgical evacuation of the cerebellar hematoma resulted in an excellent neurologic outcome. To the best of our knowledge, ours represents the only clinical case report of massive cerebellar bleed due to a capillary telangiectasia.

Herpes simplex myelitis as a cause of acute necrotizing myelitis syndrome.

We report a patient with herpes simplex virus (HSV) myelitis with a clinical history of rapidly progressive spinal cord dysfunction and extensive necrosis of the lumbosacral spinal cord at autopsy. The etiologic agent was HSV type 2. The close resemblance of the clinical features of this case to the syndrome of acute necrotizing myelitis emphasizes the need to recognize HSV myelitis as a cause of this syndrome, since it is diagnosable during life by culturing the CSF and is treatable.

Clinicopathologic correlates in Alzheimer disease: assessment of clinical and pathologic diagnostic criteria.

The neuropathologic findings from a group of 123 patients who have come to autopsy from the Rochester Alzheimer Disease Project (RADP) are presented. Among these 123 cases, there were 94 demented subjects who met the National Institute of Neurological and Communicative Disorders and Stroke-Alzheimer Disease and Related Disorders Association (NINCDS-ADRDA) clinical criteria for the diagnosis of "probable Alzheimer disease," and 29 normal elderly controls. Autopsy confirmation of Alzheimer disease (AD) was based on the age-graded National Institutes of Health (NIH) consensus conference pathologic criteria.

Devout observances.

A noted commentator suggests that Americans revere activities that reformers call "waste" or "mismanagement."

Reduced GAP-43 message levels are associated with increased neurofibrillary tangle density in the frontal association cortex (area 9) in Alzheimer's disease.

We previously suggested the hypothesis that defective neuronal plasticity is a major neurobiological deficit causing the dementia of Alzheimer's disease (AD). We used message levels of the growth-associated protein, GAP-43, as a marker of axonal plasticity to examine the hypothesis of defective neuronal plasticity in AD. When all AD cases are combined, the average level of GAP-43 message in area 9 of the AD frontal association cortex was not significantly different from the level in the comparably aged control cortex.

In situ hybridization of calcium/calmodulin dependent protein kinase II and tau mRNAs; species differences and relative preservation in Alzheimer's disease.

Abnormal phosphorylation of the microtubule associated protein tau component of neurofibrillary tangles (NFTs) in Alzheimer's disease (AD) may result from alterations in protein kinase expression. Calcium/calmodulin dependent protein kinase II (CaM kinase II) has been shown to phosphorylate tau in vitro in such a way to decrease its electrophoretic mobility. A68, apparently a modified form of tau in AD brain, also shows abnormal phosphorylation and slower mobility than tau.

The amygdala in Alzheimer's disease: neuropathology and Alz 50 immunoreactivity.

Patients with Alzheimer's disease (AD) often show emotional, motivational, and memory disturbances which may have morphological substrates that include the amygdaloid complex. Neuropathological studies in other limbic areas have recently been enhanced by immunocytochemical studies with Alz 50 antibody. Therefore, we examined the distribution of Alz 50 immunoreactive (Alz 50-IR) neuritic plaques (NP) and neurofibrillary tangles (NFT) in the amygdala in AD cases, in one aged patient with Down's syndrome, and in controls of similar ages.

Generalized cortical dysplasia. Clinical and pathologic aspects.

Three children with profound mental retardation and intractable seizures died at ages 10 months, 3 years, and 7 years, respectively. Complete examination of their brains showed generalized cortical dysplasia, without any major malformation of the external gyral pattern. The neuropathologic features of cortical dysplasia include abnormally thickened cortex with indistinct demarcation of the gray-white matter junction.

DNA synthesis in Alzheimer type II astrocytosis. The question of astrocytic proliferation and mitosis in experimentally induced hepatic encephalopathy.

Hepatic encephalopathy is associated with development of Alzheimer type II astrocytosis consisting of large, pale, frequently paired astrocytic nuclei. Previous studies have suggested that the paired forms are a manifestation of astrocytic proliferation and that the two nuclei of paired forms are in separate cells and have an equal (diploid) DNA complement. A model of hepatic encephalopathy can be produced using methionine sulfoximine to inhibit irreversibly the enzyme glutamine synthetase, resulting in elevated brain ammonia levels and development of Alzheimer type II astrocytosis.

Neuropeptides and neuropathology in the amygdala in Alzheimer's disease: relationship between somatostatin, neuropeptide Y and subregional distribution of neuritic plaques.

This study examined the amygdaloid complex in Alzheimer's disease (AD). We compared the distribution and morphology of somatostatin (SOM-) and neuropeptide Y-immunoreactive (NPY-IR) neurons in the amygdala with the distribution of neuritic plaques (NP) and acetylcholinesterase (AChE) staining patterns in various subnuclei. We found that in AD, there was an increase in the number of small, atrophic neurons for both SOM and NPY, and subregional analysis revealed similar size reductions in all subnuclei.

Cell counts in cerebral cortex of an autistic patient.

Numbers of neurons and glia were counted in the cerebral cortex of one well-documented case of autism and two age- and sex-matched controls. Areas in which cell counts were made were primary auditory cortex, Broca's speech area, and auditory association cortex. No consistent differences in cell density were found between the brains of the autistic patient and the control patients.

Cutaneous and auditory function in rats following methyl mercury poisoning.

Rats were given a total dose of 50 mg/kg (Exp. 1), 13.3 or 40 mg/kg (Exp.