Rising from the ashes: Changes in salmonid fish assemblages after 30 months of the Puyehue-Cordon Caulle volcanic eruption.

Events such as volcanic eruptions may act as disturbance agents modifying the landscape spatial diversity and increasing environmental instability. On June 4, 2011 the Puyehue-Cordon Caulle volcanic complex located on Chile (2236 m.a.s.l., 40° 02' 24" S- 70° 14' 26" W) experience a rift zone eruption ejecting during the first day 950 million metric tons into the atmosphere. Due to the westerly winds predominance, ash fell differentially upon 24 million ha of Patagonia Argentinean, been thicker deposits accumulated towards the West. In order to analyze changes on stream fish assemblages we studied seven streams 8, 19 and 30 months after the eruption along the ash deposition gradient, and compare those data to pre eruption ones. Habitat features and structure of the benthic macroinvertebrate food base of fish was studied. After the eruption, substantial environmental changes were observed in association with the large amount of ash fallout. In western sites, habitat loss due to ash accumulation, changes in the riparian zone and morphology of the main channels were observed. Turbidity was the water quality variable which reflected the most changes throughout time, with NTU values decreasing sharply from West to East sites. In west sites, increased Chironomid densities were recorded 8 months after the initial eruption as well as low EPT index values. These relationships were reversed in the less affected streams farther away from the volcano. Fish assemblages were greatly influenced both by habitat and macroinvertebrate changes. The eruption brought about an initial sharp decline in fish densities and the almost total loss of young of the year in the most western streams affecting recruitment. This effect diminished rapidly with distance from the emission center. Thirty months after the eruption, environmental changes are still occurring as a consequence of basin wide ash remobilization and transport.

Gene expression and functional studies of the optic nerve head astrocyte transcriptome from normal African Americans and Caucasian Americans donors.

PURPOSE: To determine whether optic nerve head (ONH) astrocytes, a key cellular component of glaucomatous neuropathy, exhibit differential gene expression in primary cultures of astrocytes from normal African American (AA) donors compared to astrocytes from normal Caucasian American (CA) donors. METHODS: We used oligonucleotide Affymetrix microarray (HG U133A & HG U133A 2.0 chips) to compare gene expression levels in cultured ONH astrocytes from twelve CA and twelve AA normal age matched donor eyes. Chips were normalized with Robust Microarray Analysis (RMA) in R using Bioconductor. Significant differential gene expression levels were detected using mixed effects modeling and Statistical Analysis of Microarray (SAM). Functional analysis and Gene Ontology were used to classify differentially expressed genes. Differential gene expression was validated by quantitative real time RT-PCR. Protein levels were detected by Western blots and ELISA. Cell adhesion and migration assays tested physiological responses. Glutathione (GSH) assay detected levels of intracellular GSH. RESULTS: Multiple analyses selected 87 genes differentially expressed between normal AA and CA (P<0.01). The most relevant genes expressed in AA were categorized by function, including: signal transduction, response to stress, ECM genes, migration and cell adhesion. CONCLUSIONS: These data show that normal astrocytes from AA and CA normal donors display distinct expression profiles that impact astrocyte functions in the ONH. Our data suggests that differences in gene expression in ONH astrocytes may be specific to the development and/or progression of glaucoma in AA.

Pressure induces loss of gap junction communication and redistribution of connexin 43 in astrocytes.

Astrocytes, the major glia in the nonmyelinated optic nerve head (ONH), connect via gap junctions built of connexin-43 (Cx43) to form a functional syncytium allowing communication and control of ionic and metabolic homeostasis of retinal ganglion cells (RGCs) axon. We examined gap junction intercellular communication (GJIC) by scrape loading assays in human ONH astrocytes exposed to hydrostatic (HP) or ambient pressure (CP) in vitro. Immunostaining, immunoprecipitation, and immunoblots were used to detect Cx43 distribution and phosphorylation in astrocytes exposed to HP with/without EGF receptor (EGFR) tyrosine kinase inhibitors AG1478 and AG82 and MAPK inhibitors U0126, PD98059, and SB203580. The data indicates that upon exposure to HP, astrocytes decrease GJIC and exhibit altered cellular localization and phosphorylation of Cx43. Inhibition of EGFR blocked the effects of HP on GJIC and HP-induced Cx43 tyrosine phosphorylation. Inhibitors of MAPK- ERK1/2 and -p38 caused partial closure of GJIC under CP and HP, which was maintained for 6 h. Inhibition of Big Mitogen-Activated Kinase 1/ERK5 (BMK1/ERK5) caused partial closure under CP and HP followed by full recovery after 6 h. Inhibition of MAPK did not affect the HP-induced increase in Cx43 serine 279/282 phosphorylation. We conclude that activation of the EGFR pathway in response to HP leads to decrease of GJIC via tyrosine phosphorylation of Cx43 in ONH astrocytes. In glaucoma under conditions of elevated intraocular pressure (IOP), astrocytes may lose GJIC altering the homeostasis of RGC axons, adopting the reactive phenotype, contributing to glaucomatous neuropathy.

An improved histochemical technique for differentiating adrenaline- and noradrenaline-containing cells.

BACKGROUND: Sevki's histochemical technique allows specific staining of catecholamine-containing cells, yet discrimination between adrenaline-(ADR-) cells and noradrenaline-(NOR-) cells is unreliable, being based on hue differences. METHODS: In this work, histochemical differentiation of ADR- and NOR-cells in rat adrenal medulla was carried out by introducing two modifications to Sevki's technique: 1) employment of aged Giemsa solution, and 2) addition of an alkaline differentiating step. RESULTS: With these changes, ADR-cells stained brown, whereas NOR-cells were deep-green, resulting in a clear-cut differentiation. CONCLUSIONS: The modified technique permits to differentiate ADR- from NOR-cells in the adrenal medulla using only a bright field microscope without any sophisticated equipment. The present procedure is inexpensive and easy to carry out.

An improved histochemical technique for differentiating adrenaline-and noradrenaline-containing cells

Background. Sevki's histochemical technique allows specific staining of catechomamine-containing cells, yet discrimiantion between adrenaline-(ADR-) cells and noradrenaline-(NOR-) cells is unrealiable, being based on hue differences. Methods. In this work, histochemical differentiation of ADR- and NOR-cells in rat adrenal medulla was carried out by introducing two modifications to Sevki's technique: 1) employment of aged Giemsa solution, and 2) addition of an alkaline differentiating step. Results. With these changes, ADR-cell stained brown, whereas NOR-cells were deep-green, resulting in a clear-cut differentiation. Conclusions. The modified technique permits to differentiate ADR- from NOR-cells in the adrenal medulla using only a bright field microscope without any sophisticated equipment. The present procedure is inexpensive and easy to carry out