title: Proton and cadmium adsorption by the archaeon Thermococcus zilligii: Generalising the contrast between thermophiles and mesophiles as sorbents

authors: Daughney, Christopher J.

subjects: proton adsorption

abstract: Adsorption by microorganisms can play a significant role in the fate and transport of metals in natural systems. Surface complexation models (SCMs) have been applied extensively to describe metal adsorption by mesophilic bacteria, and several recent studies have extended this framework to thermophilic bacteria. We conduct acid-base titrations and batch experiments to characterise proton and Cd adsorption onto the thermophilic archaeon Thermococcus zilligii. The experimental data and the derived SCMs indicate that the archaeon displays significantly lower overall sorption site density compared to previously studied thermophilic bacteria such Anoxybacillus flavithermus, Geobacillus stearothermophilus, G. thermocatenulatus, and Thermus thermophilus. The thermophilic bacteria and archaea display lower sorption site densities than the mesophilic microorganisms that have been studied to date, which points to a general pattern of total concentration of cell wall adsorption sites per unit biomass being inversely correlated to growth temperature.

text: Proton and cadmium adsorption by the archaeon Thermococcus zilligii: Generalising the contrast between thermophiles and mesophiles as sorbents Adsorption by microorganisms can play a significant role in the fate and transport of metals in natural systems. Surface complexation models (SCMs) have been applied extensively to describe metal adsorption by mesophilic bacteria, and several recent studies have extended this framework to thermophilic bacteria. We conduct acid-base titrations and batch experiments to characterise proton and Cd adsorption onto the thermophilic archaeon Thermococcus zilligii. The experimental data and the derived SCMs indicate that the archaeon displays significantly lower overall sorption site density compared to previously studied thermophilic bacteria such Anoxybacillus flavithermus, Geobacillus stearothermophilus, G. thermocatenulatus, and Thermus thermophilus. The thermophilic bacteria and archaea display lower sorption site densities than the mesophilic microorganisms that have been studied to date, which points to a general pattern of total concentration of cell wall adsorption sites per unit biomass being inversely correlated to growth temperature.

year: 2010

title: The decrease in mature myostatin protein in male skeletal muscle is developmentally regulated by growth hormone

authors: Oldham, Jenny M.

subjects: myostatin

abstract: Myostatin inhibits myogenesis and there is reduced abundance of the mature protein in skeletal muscles of adult male compared with female mice. This reduction probably occurs after translation, which suggests that it is a regulated mechanism to reduce the availability of myostatin in males. Reduced myostatin may, thereby, contribute to the development of sexually dimorphic growth of skeletal muscle. Our first objective was to determine if the decrease in mature myostatin protein occurs before the linear growth phase to aid growth, or afterwards to maintain the mass of adult muscle. Mice were killed from 2 to 32 weeks and the gastrocnemius muscle was excised. Myostatin mRNA increased from 2 to 32 weeks and was higher in males than females (P < 0.001). In contrast, mature protein decreased in males after 6 weeks (P < 0.001). Our second objective was to determine if growth hormone (GH) induces the decrease in mature myostatin protein. GH increased myostatin mRNA and decreased the abundance of mature protein in hypophysectomised mice (P < 0.05). Our final objective was to determine if the decrease in mature protein occurs in skeletal muscles of male Stat5b−/− mice (Stat5b mediates the actions of GH). As expected, mature myostatin protein was not reduced in Stat5b−/− males compared with females. However, myostatin mRNA remained higher in males than females irrespective of genotype. These data suggest that: (1) the decrease in mature myostatin protein is developmentally regulated, (2) GH acting via Stat5b regulates the abundance of mature myostatin and (3) GH acts via a non-Stat5b pathway to regulate myostatin mRNA.

text: The decrease in mature myostatin protein in male skeletal muscle is developmentally regulated by growth hormone Myostatin inhibits myogenesis and there is reduced abundance of the mature protein in skeletal muscles of adult male compared with female mice. This reduction probably occurs after translation, which suggests that it is a regulated mechanism to reduce the availability of myostatin in males. Reduced myostatin may, thereby, contribute to the development of sexually dimorphic growth of skeletal muscle. Our first objective was to determine if the decrease in mature myostatin protein occurs before the linear growth phase to aid growth, or afterwards to maintain the mass of adult muscle. Mice were killed from 2 to 32 weeks and the gastrocnemius muscle was excised. Myostatin mRNA increased from 2 to 32 weeks and was higher in males than females (P < 0.001). In contrast, mature protein decreased in males after 6 weeks (P < 0.001). Our second objective was to determine if growth hormone (GH) induces the decrease in mature myostatin protein. GH increased myostatin mRNA and decreased the abundance of mature protein in hypophysectomised mice (P < 0.05). Our final objective was to determine if the decrease in mature protein occurs in skeletal muscles of male Stat5b−/− mice (Stat5b mediates the actions of GH). As expected, mature myostatin protein was not reduced in Stat5b−/− males compared with females. However, myostatin mRNA remained higher in males than females irrespective of genotype. These data suggest that: (1) the decrease in mature myostatin protein is developmentally regulated, (2) GH acting via Stat5b regulates the abundance of mature myostatin and (3) GH acts via a non-Stat5b pathway to regulate myostatin mRNA.

year: 2009

title: The reform of Maori land tenure and the quest for sustainability in New Zealand

authors: Jay, Grace Mairi M.

subjects: geography

abstract: Many of the countries of the Pacific region (including Australia and New Zealand) have a British colonial legacy. This history has had wide implications for the development of the region: economically, politically and socially. The cadastral (property based) systems in these countries have been influenced by British land conveyance and registration practices, and by colonial history. To date, Australia and new Zealand are still trying to resolve land tenure and information problems which are steeped in historical and ethnic dimensions. Land is the single most important factor for Maori development in New Zealand, and has great implications for the development of this country.

text: The reform of Maori land tenure and the quest for sustainability in New Zealand Many of the countries of the Pacific region (including Australia and New Zealand) have a British colonial legacy. This history has had wide implications for the development of the region: economically, politically and socially. The cadastral (property based) systems in these countries have been influenced by British land conveyance and registration practices, and by colonial history. To date, Australia and new Zealand are still trying to resolve land tenure and information problems which are steeped in historical and ethnic dimensions. Land is the single most important factor for Maori development in New Zealand, and has great implications for the development of this country.

year: 1997