title: Murray-Darling basin freshwater shells: riverine reservoir effect

authors: Gillespie, Richard

subjects: carbon isotopes

abstract: We report carbon isotope measurements on pre-bomb museum samples of freshwater mussel shells collected alive from riverine locations in New South Wales, Australia. The calculated reservoir ages, ranging from -60 to +112 years, are much smaller than those for Australian marine shells and not considered significant for the radiocarbon dating of Late Pleistocene freshwater shells from the Murray-Darling Basin.

text: Murray-Darling basin freshwater shells: riverine reservoir effect We report carbon isotope measurements on pre-bomb museum samples of freshwater mussel shells collected alive from riverine locations in New South Wales, Australia. The calculated reservoir ages, ranging from -60 to +112 years, are much smaller than those for Australian marine shells and not considered significant for the radiocarbon dating of Late Pleistocene freshwater shells from the Murray-Darling Basin.

year: 2009

title: Esterase catalysis of substrate vapour: enzyme activity occurs at very low hydration

authors: Lind, Penelope A.

subjects: hydrolase

abstract: It has been generally accepted that enzyme activity requires a minimal hydration of about 0.2 g H2O g⁻¹ protein. This fits well with evidence that hydration above this level is associated with the onset of intramolecular motions. The influence of enzyme hydration on the hydrolysis of substrate by Candida rugosa Lipase B and pig liver esterase was investigated. Each enzyme was studied as a powder at various hydration levels, using vapour phase ethyl butyrate as substrate. This procedure allows the separation of those effects that are due to hydration from those arising from diffusional constraints. We found hydrolytic activity in both enzymes at all hydration levels above zero (between 0.054–0.47 and 0.029–0.60 g H2O g⁻¹ protein, respectively) that were investigated. The lowest hydration level investigated, <0.03 g H2O g⁻¹ enzyme, corresponded to a water/enzyme mole ratio of 100 and a coverage of about 10% of the enzyme surface by water molecules. The hydrolytic activity of both enzymes was dependent on protein hydration. However, since the hydrolysis of ethyl butyrate requires water as a second substrate, the absence of activity at zero hydration does not rule out the possibility of enzyme activity in the absence of water. These results suggest that the properties conferred on proteins by water, at least above 10% surface coverage (in this case corresponding to a hydration level of 0.03 g H2O g⁻¹ protein), are not a requirement for enzyme catalysis.

text: Esterase catalysis of substrate vapour: enzyme activity occurs at very low hydration It has been generally accepted that enzyme activity requires a minimal hydration of about 0.2 g H2O g⁻¹ protein. This fits well with evidence that hydration above this level is associated with the onset of intramolecular motions. The influence of enzyme hydration on the hydrolysis of substrate by Candida rugosa Lipase B and pig liver esterase was investigated. Each enzyme was studied as a powder at various hydration levels, using vapour phase ethyl butyrate as substrate. This procedure allows the separation of those effects that are due to hydration from those arising from diffusional constraints. We found hydrolytic activity in both enzymes at all hydration levels above zero (between 0.054–0.47 and 0.029–0.60 g H2O g⁻¹ protein, respectively) that were investigated. The lowest hydration level investigated, <0.03 g H2O g⁻¹ enzyme, corresponded to a water/enzyme mole ratio of 100 and a coverage of about 10% of the enzyme surface by water molecules. The hydrolytic activity of both enzymes was dependent on protein hydration. However, since the hydrolysis of ethyl butyrate requires water as a second substrate, the absence of activity at zero hydration does not rule out the possibility of enzyme activity in the absence of water. These results suggest that the properties conferred on proteins by water, at least above 10% surface coverage (in this case corresponding to a hydration level of 0.03 g H2O g⁻¹ protein), are not a requirement for enzyme catalysis.

year: 2004-10

title: Te Kāuta

authors: Roa, Raukura

subjects: Kōrero paki

abstract: He rite tonu tā mātou hokihoki ki te take o Pirongia maunga, ki te tutungi i te ahi kā i Pūrekireki Marae. Ia wā ka hoki mātou ki tēnei o ngā marae, ka hīkaka taku ngākau, i te mea, ko taku mahi i reira, he tiaki ahi. Ao noa, pō noa, ko au te kaiwhakatutungi i te ahi o te kāuta, kei kewa. Ko te ahi o te kāuta o Pūrekireki marae, he ahi nui, he ahi kaitā. E ono tāngata pea ka uru ki te rua o te ahi nei. Nō reira, ko taku mahi i te rā, he kohi rākau i waho, he tapahi wahie, he whakamaroke anō hoki i te wahie, inā mākū i te ua. I ngā pō, kia hoki rā anō te iwi ki te moe, ko tāku, he noho ki roto i te kāuta me te tutungi ahi, kia wera tonu ai te wai mō āpōpō. Kei pōhēhē mai, he mahi mokemoke tēnei! Ehara! Ia pō, ka noho mai aku kuia ki taku taha ki te pahupahu. He nui ngā akoranga me ngā mātauranga i tuku iho mai ki a au i roto i tērā kāuta, i te taha o tērā ahi. Me uaua ka kitea tēnei momo ahi kaitā i ngā marae i ēnei rā. Kāore e whakaaengia ana e ngā ture Pākehā ngā ahi kaitā, pēnei nei te rahi, i roto i ngā kāuta o ngā marae; ‘Health and Safety Standards’ tā rātou i whakatau ai. Nō reira, i karangangia e taku pāpā tētehi hui ki te marae kia wānangahia te whakahōutanga o tō mātou kāuta. Nō taku rongotanga ake i te kaupapa o tēnei hui, ka tangi taku ngākau ki tō mātou kāuta. Nō reira, i whakarite ahau kia haere i tana taha.

text: Te Kāuta He rite tonu tā mātou hokihoki ki te take o Pirongia maunga, ki te tutungi i te ahi kā i Pūrekireki Marae. Ia wā ka hoki mātou ki tēnei o ngā marae, ka hīkaka taku ngākau, i te mea, ko taku mahi i reira, he tiaki ahi. Ao noa, pō noa, ko au te kaiwhakatutungi i te ahi o te kāuta, kei kewa. Ko te ahi o te kāuta o Pūrekireki marae, he ahi nui, he ahi kaitā. E ono tāngata pea ka uru ki te rua o te ahi nei. Nō reira, ko taku mahi i te rā, he kohi rākau i waho, he tapahi wahie, he whakamaroke anō hoki i te wahie, inā mākū i te ua. I ngā pō, kia hoki rā anō te iwi ki te moe, ko tāku, he noho ki roto i te kāuta me te tutungi ahi, kia wera tonu ai te wai mō āpōpō. Kei pōhēhē mai, he mahi mokemoke tēnei! Ehara! Ia pō, ka noho mai aku kuia ki taku taha ki te pahupahu. He nui ngā akoranga me ngā mātauranga i tuku iho mai ki a au i roto i tērā kāuta, i te taha o tērā ahi. Me uaua ka kitea tēnei momo ahi kaitā i ngā marae i ēnei rā. Kāore e whakaaengia ana e ngā ture Pākehā ngā ahi kaitā, pēnei nei te rahi, i roto i ngā kāuta o ngā marae; ‘Health and Safety Standards’ tā rātou i whakatau ai. Nō reira, i karangangia e taku pāpā tētehi hui ki te marae kia wānangahia te whakahōutanga o tō mātou kāuta. Nō taku rongotanga ake i te kaupapa o tēnei hui, ka tangi taku ngākau ki tō mātou kāuta. Nō reira, i whakarite ahau kia haere i tana taha.

year: 2016