Cooperation between passive and active silicon transporters clarifies the ecophysiology and evolution of biosilicification in sponges.

The biological utilization of dissolved silicon (DSi) influences ocean ecology and biogeochemistry. In the deep sea, hexactinellid sponges are major DSi consumers that remain poorly understood. Their DSi consumption departs from the Michaelis-Menten kinetics of shallow-water demosponges and appears particularly maladapted to incorporating DSi from the modest concentrations typical of the modern ocean.

Microbial Strategies for Survival in the Glass Sponge .

Few studies have explored the microbiomes of glass sponges (Hexactinellida). The present study seeks to elucidate the composition of the microbiota associated with the glass sponge and the functional strategies of the main symbionts. We combined microscopic approaches with metagenome-guided microbial genome reconstruction and amplicon community profiling toward this goal.

Climate-induced changes in the suitable habitat of cold-water corals and commercially important deep-sea fishes in the North Atlantic.

The deep sea plays a critical role in global climate regulation through uptake and storage of heat and carbon dioxide. However, this regulating service causes warming, acidification and deoxygenation of deep waters, leading to decreased food availability at the seafloor. These changes and their projections are likely to affect productivity, biodiversity and distributions of deep-sea fauna, thereby compromising key ecosystem services.

Predicted distribution of the glass sponge Vazella pourtalesi on the Scotian Shelf and its persistence in the face of climatic variability.

Emerald Basin on the Scotian Shelf off Nova Scotia, Canada, is home to a globally unique aggregation of the glass sponge Vazella pourtalesi, first documented in the region in 1889. In 2009, Fisheries and Oceans Canada (DFO) implemented two Sponge Conservation Areas to protect these sponge grounds from bottom fishing activities. Together, the two conservation areas encompass 259 km2.

Kernel density surface modelling as a means to identify significant concentrations of vulnerable marine ecosystem indicators.

The United Nations General Assembly Resolution 61/105, concerning sustainable fisheries in the marine ecosystem, calls for the protection of vulnerable marine ecosystems (VME) from destructive fishing practices. Subsequently, the Food and Agriculture Organization (FAO) produced guidelines for identification of VME indicator species/taxa to assist in the implementation of the resolution, but recommended the development of case-specific operational definitions for their application. We applied kernel density estimation (KDE) to research vessel trawl survey data from inside the fishing footprint of the Northwest Atlantic Fisheries Organization (NAFO) Regulatory Area in the high seas of the northwest Atlantic to create biomass density surfaces for four VME indicator taxa: large-sized sponges, sea pens, small and large gorgonian corals.

A comparison of corneal cellular responses after 213-nm compared with 193-nm laser photorefractive keratectomy in rabbits.

Purpose: Corneal refractive surgery is typically performed using a 193-nm excimer laser. However, a recently developed 213-nm solid-state (5th harmonic) Nd:YAG laser presents some practical and user safety advantages, although the biological impact of using this wavelength remains poorly characterized. Here, we provide in vivo and in vitro comparisons of the corneal cellular outcomes after irradiation with 213 and 193 nm wavelengths.

Graft outcomes influenced by co-expression of Pax7 in graft and host tissue.

Cell replacement therapies offer promise in the treatment of neurotrauma and neurodegenerative disorders and have concentrated on the use of primary fetal brain tissue. However, there is a growing promise of using neural stem cells, in which case other factors may be important in their successful engraftment. We therefore investigated whether the co-expression of the major developmental transcription factor (Pax7 in this study) of donor tissue to graft site influences transplant survival and differentiation in the rat midbrain.

Cone visual pigments in two species of South American marsupials.

Marsupials are largely confined to Australasia and to Central and South America. The visual pigments that underlie the photosensitivity of the retina have been examined in a number of species from the former group where evidence for trichromatic colour vision has been found, but none from the latter. In this paper, we report the cone opsin sequences from two nocturnal South American marsupial species, the gray short-tailed opossum, Monodelphis domestica, and the big-eared opossum, Didelphis aurita.

Exogenous metallothionein-IIA promotes accelerated healing after a burn wound.

Severe injury to the epidermal barrier often results in scarring and life-long functional deficits, the outcome worsening with a number of factors including time taken to heal. We have investigated the potential of exogenous metallothionein IIA (Zn(7)-MT-IIA), a naturally occurring small cysteine-rich protein, to accelerate healing of burn wounds in a mouse model. Endogenous MT-I/II expression increased in basal keratinocytes concurrent with reepithelialization after a burn injury, indicating a role for MT-I/II in wound healing.

Regional and cellular distribution of ephrin-B1 in adult mouse brain.

The membrane-bound proteins ephrins and their receptors, Eph receptor tyrosine kinases, are known for their key role during development of the central nervous system (CNS). Ligand/receptor interactions as a result of cell-cell contacts activate intracellular signalling pathways which mediate specific cellular responses. Activation can occur bidirectionally in both the receptor and the ligand-bearing cells.

Neurite responses to ephrin-A5 modulated by BDNF: evidence for TrkB-EphA interactions.

In the developing visual system, growing retinal ganglion cell (RGC) axons are exposed to multiple guidance and growth factors. Furthermore, the relative levels of these factors are differentially regulated as topography is roughly established and then refined. We have shown that during the establishment of rough topography (P3), growth cones of pure and explanted RGCs treated with combinations of BDNF and ephrin-A5-Fc responded differently than RGCs treated with BDNF or ephrin-A5-Fc alone (p=0.

Cone visual pigments in two marsupial species: the fat-tailed dunnart (Sminthopsis crassicaudata) and the honey possum (Tarsipes rostratus).

Uniquely for non-primate mammals, three classes of cone photoreceptors have been previously identified by microspectrophotometry in two marsupial species: the polyprotodont fat-tailed dunnart (Sminthopsis crassicaudata) and the diprotodont honey possum (Tarsipes rostratus). This report focuses on the genetic basis for these three pigments. Two cone pigments were amplified from retinal cDNA of both species and identified by phylogenetics as members of the short wavelength-sensitive 1 (SWS1) and long wavelength-sensitive (LWS) opsin classes.

The influence of ontogeny and light environment on the expression of visual pigment opsins in the retina of the black bream, Acanthopagrus butcheri.

The correlation between ontogenetic changes in the spectral absorption characteristics of retinal photoreceptors and expression of visual pigment opsins was investigated in the black bream, Acanthopagrus butcheri. To establish whether the spectral qualities of environmental light affected the complement of visual pigments during ontogeny, comparisons were made between fishes reared in: (1) broad spectrum aquarium conditions; (2) short wavelength-reduced conditions similar to the natural environment; or (3) the natural environment (wild-caught). Microspectrophotometry was used to determine the wavelengths of spectral sensitivity of the photoreceptors at four developmental stages: larval, post-settlement, juvenile and adult.

Redefining the role of metallothionein within the injured brain: extracellular metallothioneins play an important role in the astrocyte-neuron response to injury.

A number of intracellular proteins that are protective after brain injury are classically thought to exert their effect within the expressing cell. The astrocytic metallothioneins (MT) are one example and are thought to act via intracellular free radical scavenging and heavy metal regulation, and in particular zinc. Indeed, we have previously established that astrocytic MTs are required for successful brain healing.

Ephrin-B2 immunoreactivity distribution in adult mouse brain.

Ephrin ligands and their receptors Eph receptor tyrosine-kinases have received extensive attention for their multiple key roles during development, particularly in the central nervous system (CNS). For example, at early stages of brain and spinal cord development, membrane-bound ephrins provide signals that direct migrating cells and axons. However, much less is known about the role of ephrins and Eph receptors in the adult CNS.

Spectral sensitivities of the seahorses Hippocampus subelongatus and Hippocampus barbouri and the pipefish Stigmatopora argus.

The Syngnathidae are specialized diurnal feeders that are known to possess a retinal fovea and use independent eye movements to locate, track, and strike individual planktonic prey items. In this study, we have investigated the spectral sensitivities of three syngnathid species: a pipefish and two seahorses. We used spectrophotometry to measure the spectral transmission properties of ocular lenses and microspectrophotometry to measure the spectral absorption characteristics of visual pigments in the retinal photoreceptors.

Regenerating optic axons restore topography after incomplete optic nerve injury.

Following complete optic nerve injury in a lizard, Ctenophorus ornatus, retinal ganglion cell (RGC) axons regenerate but fail to restore retinotectal topography unless animals are trained on a visual task (Beazley et al. [ 1997] J Comp Neurol 370:105-120, [2003] J Neurotrauma 20:1263-1270). Here we show that incomplete injury, which leaves some RGC axons intact, restores normal topography.

Metallothionein-IIA promotes neurite growth via the megalin receptor.

Metallothionein (MT)-I/II has been shown to be neuroprotective and neuroregenerative in a model of rat cortical brain injury. Here we examine expression patterns of MT-I/II and its putative receptor megalin in rat retina. At neonatal stages, MT-I/II was present in retinal ganglion cells (RGCs) but not glial or amacrine cells; megalin was present throughout the retina.

Erythropoietin is both neuroprotective and neuroregenerative following optic nerve transection.

The cytokine hormone erythropoietin (EPO) is neuroprotective in models of brain injury and disease, and protects retinal ganglion cells (RGC) from cell death after axotomy. Here, we assessed EPO's neuroprotective properties in vivo by examining RGC survival and axon regeneration at 4 weeks following intraorbital optic nerve transection in adult rat. EPO was administered as a single intravitreal injection at the time of transection (5, 10, 25, 50 units, PBS control).

EphA5 and ephrin-A2 expression during optic nerve regeneration: a 'two-edged sword'.

During development, gradients of EphA receptors (nasal(low)-temporal(high)) and their ligands ephrin-As (rostral(low)-caudal(high)) are involved in establishing topography between retinal ganglion cells (RGCs) and the superior colliculus (SC). EphA5-expressing RGC axons are repulsed by ephrin-A2-expressing SC neurones. In adult rats RGCs maintain graded EphA5 expression but ephrin-A2 expression is down-regulated in the SC to a weak gradient.

Pax7 expression in the adult rat superior colliculus following optic nerve injury.

The transcription factor Pax7 has been implicated in the normal development of the superior colliculus and continues to be expressed in the adult superior colliculus, where it is concentrated in the retino-recipient laminae. Here we assessed, immunohistochemically, Pax7 expression in the adult rat superior colliculus after unilateral intraorbital optic nerve transection. We show that after optic nerve transection, the number of Pax7-expressing cells increased to re-establish the developmental rostral-caudal gradient and that these Pax7-expressing superior colliculus cells were neurons.