Hagfish: champions of CO2 tolerance question the origins of vertebrate gill function

The gill is widely accepted to have played a key role in the adaptive radiation of early vertebrates by supplanting the skin as the dominant site of gas exchange. However, in the most basal extant craniates, the hagfishes, gills play only a minor role in gas exchange. In contrast, we found hagfish gills to be associated with a tremendous capacity for acid-base regulation. Indeed, Pacific hagfish exposed acutely to severe sustained hypercarbia tolerated among the most severe blood acidoses ever reported (1.2 pH unit reduction) and subsequently exhibited the greatest degree of acid-base compensation ever observed in an aquatic chordate. This was accomplished through an unprecedented increase in plasma [HCO3−] (>75 mM) in exchange for [Cl−]. We thus propose that the first physiological function of the ancestral gill was acid-base regulation, and that the gill was later co-opted for its central role in gas exchange in more derived aquatic vertebrates

Emerging medical and engineering strategies for the prevention of long-term indwelling catheter blockage

Urinary catheters have been used on an intermittent or indwelling basis for centuries, in order to relieve urinary retention and incontinence. Nevertheless, the use of urinary catheters in the clinical setting is fraught with complication, the most common of which is the development of nosocomial urinary tract infections, known as catheter-associated urinary tract infections. Infections of this nature are not only significant owing to their high incidence rate and subsequent economic burden but also to the severe medical consecutions that result. A range of techniques have been employed in recent years, utilising various technologies in attempts to counteract the perilous medical cascade following catheter blockage. This review will focus on the current advancement (within the last 10 years) in prevention of encrustation and blockage of long-term indwelling catheters both from engineering and medical perspectives, with particular emphasis on the importance of stimuli-responsive systems.</p

The limits of osmoregulation : strategies for tolerance and acclimation of 'California' Mozambique tilapia (Oreochromis mossambicus x O. urolepis hormorum) to conditions of the Salton Sea

The Salton Sea is a large inland lake in southeastern California with salinity currently near 44 g/l that is increasing at a rate of 0.3 g/l annually. Along with salinity, large fluctuations in temperature and dissolved oxygen levels combine to make a very challenging environment that may be responsible for dramatic losses to the Salton Sea's once robust fishery. The dominant species within the fishery is a Mozambique tilapia hybrid (Oreochromis mossambicus x O. urolepis hornorum), which is well known both for euryhalinity and tolerance of extremely high salinities; as such, it provides a unique model for tolerance to hypersaline conditions as well as the interactions of multiple stressors such as those within the Salton Sea. In part one I describe two responses by tilapia to salinities greater than seawater at 25°C. When transfers were conducted below 60 g/l salinity, tilapia maintained osmotic balance without increasing drinking rate, mitochondrial-rich cell (MRC) turnover, or branchial Na⁺,K⁺-ATPase (NKA) activity. With additional increase above 60 g/l, these variables increased in similar fashion to that which has been described in other teleosts during acclimation to elevated salinity. These acclimation responses were defined as response I or response II, with a transition point between the two at 60 g/l. Tilapia exhibiting response I had a reduced whole animal oxygen consumption rate, as well as, liver and brain ATPase activity in proportion to salinity. In part two, I describe how changes in temperature affect the salinity tolerance of this species. Variation in temperature from 25°C to 15 or 35°C resulted in increased plasma osmolality and/or mortality, indicating a combined temperature/salinity stress is more challenging than salinity alone. Using tissue microarrays and laser scanning microscopy, I show that tilapia attempted to respond to the loss of osmotic balance in cold temperatures with MRC hypertrophy and enhanced NKA capacity.Science, Faculty ofZoology, Department ofGraduat

Using Tephrochronology and palynology to date the MIS 13 lacustrine sediments of the Mercure basin (Southern Apennines - Italy)

The present paper deals with the chronostratigraphy of the lacustrine infilling of the Mercure basin, an intramontane depression of Southern Apennines, located along the Calabria-Lucania boundary. Tephrochronology and pollen analysis were carried out on the outcropping portion of the infilling succession, exposed along V-shaped tributary valleys of the Mercure river. Lithological and chemical features of the thickest and best preserved tephra layer were fully characterized and the layer was 40Ar/39Ar dated to 514 ± 16 ka. Pollen analyses revealed the occurrence of warm and humid interglacial conditions that were correlated to MIS 13 on the basis of age determination. The chemical composition of glasses made it possible to point out the Sabatini Volcanic District as the most probable source of the investigated tephra layer. Although chemical features would corroborate correlation with the Tufo Giallo della Via Tiberina multiphase eruption, occurred between 561 and 548 ka, the integration of tephrochronology and pollen analysis points to a younger age, falling within MIS 13. On this basis, correlation with one of the four explosive events occurred at the Latial district in the 514-449 time span has been proposed, making the Mercure tephra layer a valid marker for MIS 13 in central -southern Italy

Tectonic and climatic control on geomorphological and sedimentary evolution of the Mercure basin, southern Apennines, Italy

The morpho-tectonic and sedimentary evolution of the Mercure intramontane basin (Calabria-Lucania boundary, southern Apennines) has been assessed through fades analysis, morphostratigraphy and geomorphological correlation with adjacent areas. The Mercure basin, one of the most active seismogenic zones of the southern Apennines, is a favorable area for reconstructing the main stages of landscape evolution of the axial zone because of its capability to record changes in base level during the Quaternary. In addition, the presence of both erosional and depositional Palaeosurfaces is a useful marker for reconstructing tectonic and morphogenetic events, and hence to detect the role played by tectonics and climate in its genesis, evolution and extinction. The present study identifies the key role of tectonics and denudation, combined with high-frequency floods, as mechanisms controlling alluvial sedimentation in the study area. During endorheic conditions, denudational processes driven by pulses of extensional deformation of the basin margin caused strong alluvial inputs that resulted in the development of alluvial fans. Alluvial fades are mainly characterized by turbulent, subaerial, hyperconcentrated flood flows deposited during the glacial, semi-arid conditions of MIS 14. The retrogradational stacking pattern of the alluvial system indicates decreasing rates of tectonic activity along with declining river gradients. The Mercure coalescing alluvial fans were inundated by lake transgression during MIS 13 in response to (i) abrupt tectonic subsidence at the basin margins and (ii) large decrease of coarse sediment supply due to the interplay among climate, tectonics and catchment size changes. In this regard, it is suggested that tectonic control on the drainage network along with climate and long-term slope evolution may have caused marked pulses in sediment supply, thus influencing the arrangement of facies associations in the sedimentary succession. In addition, the study points out that the main tectonic landforms developed during each period of the landscape evolution well correspond with some active fault segments. (C) 2014 Elsevier B.V. All rights reserved