Duplication of the glucosephosphate isomerase locus in vertebrates

1. Two glucosephosphate isomerases (GPI) have been found in lampreys but not in Myxine or in Elasmobranchiomorphs. 2. The tissue specificities of the isomerases in lampreys were similar to those previously found for GPI-A and GPI-B in teleosteans. 3. Lampreys and teleosteans are the only vertebrate groups in which multiple GPI genes are known

). Muscle proteins of the coelecanth Latimeria chalumnae Smith.

Although the anatomy of the coelacanth muscles has been examined very thoroughly, their protein composition has, until recently, not been investigated. Thanks, however, to the 1972 British-French-American expedition to the Comores, frozen material has been made available and some results on myoglobin and four glycolytic enzymes have already been published. We have carried out a comparison of the sarcoplasmic proteins of red and white muscle by starch-gel electrophoresis. The ninhydrin-positive dialysable constituents and the myofibrillar proteins of white muscle have also been examined. A few puzzling results obtained with the white muscle extracts have been related to the occurrence of 0.1 M ammonia, due presumably to the splitting of urea by a bacterial urease, and to an alteration of the active thiol groups of GAPDH and PK. If due account is taken of these unusual post-mortem changes, the extractability of the proteins and their properties are strikingly similar to those of teleosteans. The comparison of the sarcoplasmic proteins of white and red muscle by starch- gel electrophoresis revealed also that the differentiation observed in the coelacanth was similar to that occurring in the carp. A study of the low-molecular-weight proteins, or parvalbumins, of white muscle and of the myofibrillar proteins also shows the expected differences between the two muscle types. The only abnormal features observed in this study were the high concentration of parvalbumins, 1.5-2 times that found in other species examined, and the occurrence of an unusual globulin fraction which was easily extracted at ionic strength 0.5 and insoluble at ionic strength 0.35 and neutral pH

Muscle proteins of the coelacanth <i>Latimeria chalumnae</i> Smith

Although the anatomy of the coelacanth muscles has been examined very thoroughly, their protein composition has, until recently, not been investigated. Thanks, however, to the 1972 British–French–American expedition to the Comores, frozen material has been made available and some results on myoglobin and four glycolytic enzymes have already been published. We have carried out a comparison of the sarcoplasmic proteins of red and white muscle by starch-gel electrophoresis. The ninhydrin-positive dialysable constituents and the myofibrillar proteins of white muscle have also been examined.A few puzzling results obtained with the white muscle extracts have been related to the occurrence of o.1 M ammonia, due presumably to the splitting of urea by a bacterial urease, and to an alteration of the active thiol groups of GAPDH and PK. If due account is taken of these unusual post-mortem changes, the extractability of the proteins and their properties are strikingly similar to those of teleosteans. The comparison of the sarcoplasmic proteins of white and red muscle by starch-gel electrophoresis revealed also that the differentiation observed in the coelacanth was similar to that occurring in the carp. A study of the low-molecular-weight proteins, or parvalbumins, of white muscle and of the myofibrillar proteins also shows the expected differences between the two muscle types.The only abnormal features observed in this study were the high concentration of parvalbumins, 1.5–2 times that found in other species examined, and the occurrence of an unusual globulin fraction which was easily extracted at ionic strength 0.5 and insoluble at ionic strength 0.35 and neutral pH

Spatial distribution and budget for submarine groundwater discharge in Eckernforde Bay (Western Baltic Sea)

Submarine groundwater discharge (SGD) from subseafloor aquifers, through muddy sediments, was studied in Eckernförde Bay (western Baltic Sea). The fluid discharge was clearly traced by 222Rn enrichment in the water column and by the chloride profiles in pore water. At several sites, a considerable decrease in chloride, to levels less than 10% of bottom-water concentrations, was observed within the upper few centimeters of sediment. Studies at 196 sites revealed that >22% of the seafloor of the bay area was affected by freshwater admixture and active fluid venting. A maximal discharge rate of .9 L m−2 d−1 was computed by modeling pore water profiles. Based on pore water data, the freshwater flow from subseafloor aquifers to Eckernförde Bay was estimated to range from 4 x 106 to 57 × 106 m3 yr−1. Therefore, 0.3–4.1% of the water volume of the bay is replaced each year. Owing to negligible surface runoff by rivers, SGD is a significant pathway within the hydrological cycle of this coastal zone. High-resolution bathymetric data and side-scan sonar surveys of pockmarks, depressions up to 300 m long, were obtained by using an autonomous underwater vehicle. Steep edges, with depths increasing by more than 2 m within 8–10 m in lateral directions, equivalent to slopes with an angle of as much as 11°, were observed. The formation of pockmarks within muddy sediments is suggested to be caused by the interaction between sediment fluidization and bottom currents. Fluid discharge from glacial coastal sediments covered by mud deposits is probably a widespread, but easily overlooked, pathway affecting the cycle of methane and dissolved constituents to coastal waters of the Baltic Sea

Chemoautotrophic Microbial Mats in Submarine Caves with Hydrothermal Sulphidic Springs at Cape Palinuro, Italy

Observations were made on the distribution, morphology, and chemoautotrophic potential of microbial mats found in submarine caves of dolomitized limestone which contain hydrothermal sulphidic springs at Cape Palinuro, Italy. The distribution of microbial mats is closely associated with the flow of hydrothermal fluid from springs whose activity is intermittent and initiated during low tide. Fluid emitted from active springs in the Grotta Azzurra has a maximum temperature of 24.6°C and is enriched in dissolved sulfur species (H2S, S2O3 2−) and dissolved gases (CH4, CO2). However, it is depleted in NaCl and dissolved O2, in comparison with ambient seawater. This fluid is less dense and rises above the ambient seawater to form a visible thermocline and chemocline separating both layers in the submarine caves. Microbial mats were attached to rock surfaces immersed in fluid above the chemocline and were differentiated into brown and white forms. Brown mats were composed of trichomes (4.2 ± 0.1 μm and 20.3 ± 0.7 μm in diameter) resembling the calcareous rock-boring cyanobacterium Schizothrix and clusters (6 μm in diameter) of sarcina-like cells morphologically resembling methanogenic bacteria. White mats were composed of attached filaments resembling Beggiatoa (19.3 ± 0.5 μm, 39.0 ± 1.7 μm, and 66.9 ± 3.3 μm in diameter) and Thiothrix (4.2 ± 0.2 μm in diameter). Flexibacteria (\u3c1 μm in diameter) were common to both mats. Beggiatoa-like filaments were morphologically similar to those attached to rocks and the byssal threads of mussels from Lucky Strike vent field on the Mid-Atlantic Ridge. Morphological comparisons were also made with typical gliding Beggiatoa from shallow seeps in Eckernförder Bucht, Baltic Sea. White mats displayed chemoautotrophic fixation of CO2 under relatively well-oxygenated laboratory conditions (maximum rate 50.2 nmol CO2/mg dry wt/h) using internal S0 or possibly S2O3 2− as electron donor. Photosynthesis may be limited in the Grotta Azzurra by insufficient illumination (6.3 × 10−7μ einsteins/c

Gas seep induced interstitial water circulation: observations and environmental implications

An interstitial water circulation, generated by gas flow through a permeable sediment, was observed at an intertidal site on the Kattegat coast of Denmark. Concentrations of methane dissolved in the interstitial water of the near-surface sediment decreased sharply only centimetres away from gas seeps venting almost pure methane (circs 99% methane). Water was driven out of the sediment by the rising bubbles of gas at the seep and was replaced by an equivalent draw-down of overlying, oxygenated water into the surrounding sediment. This process steepened the chemical gradients close to the gas flow channel, with the effects progressively diminishing with increasing distance from the seep. The position of the redox potential discontinuity (RPD) moved by as much as 7 cm deeper into the sediment close to the seep: this effect was less marked, but still detectable, 50 cm away. The degree of displacement from the “normal” sediment profiles depended on the magnitude of the interstitial flow rate. The distribution of pore water pH and sulphate:sodium ratios were also dependent on the flow rate of the circulating water. The concentrations of sulphide, thiosulphate and sulphite in the interstitial water from the top 10 cm of sediment, were high at a seep, decreased to a minimum at 20-30 cm distance, then increased again at 40-50 cm distance. Laboratory experiments confirmed that gas bubbling through a fluid filled permeable matrix generated a flow, out of the sediment at the gas exit and into the sediment over the peripheral surfaces surrounding the outlet. Experimentally determined rates of dispersion, for gas flow rates of 3-20 ml/min, for a 40 g/l sodium chloride solution, were 62.5 x 10-9 to 540 x 10-9 m2 s-l, 40-400 times the molecular diffusion coefficient. Linear interstitial fluid velocities of 3-12 mm/min, were recorded at 14-3 cm from the seep axis respectively, with a gas flow rate of 5 ml/min. Two-dimensional modelling of the experimental system confirmed the flow patterns determined visually with dye. Implications of this process with regard to the recycling rates of elements generally, and of nutrient and waste materials,in particular, are discussed