title: Large mass-independent oxygen isotope fractionations in mid-Proterozoic sediments: Evidence for a low-oxygen atmosphere?

authors: Planavsky, Noah J.

subjects: Atmospheric oxygenation

abstract: Earth's ocean-atmosphere system has undergone a dramatic but protracted increase in oxygen (O₂) abundance. This environmental transition ultimately paved the way for the rise of multicellular life and provides a blueprint for how a biosphere can transform a planetary surface. However, estimates of atmospheric oxygen levels for large intervals of Earth's history still vary by orders of magnitude-foremost for Earth's middle history. Historically, estimates of mid-Proterozoic (1.9-0.8 Ga) atmospheric oxygen levels are inferred based on the kinetics of reactions occurring in soils or in the oceans, rather than being directly tracked by atmospheric signatures. Rare oxygen isotope systematics-based on quantifying the rare oxygen isotope ¹⁷O in addition to the conventionally determined ¹⁶O and ¹⁸O-provide a means to track atmospheric isotopic signatures and thus potentially provide more direct estimates of atmospheric oxygen levels through time. Oxygen isotope signatures that deviate strongly from the expected mass-dependent relationship between ¹⁶O, ¹⁷O, and ¹⁸O develop during ozone formation, and these "mass-independent" signals can be transferred to the rock record during oxidation reactions in surface environments that involve atmospheric O₂. The magnitude of these signals is dependent upon 𝘱O₂, 𝘱CO₂, and the overall extent of biospheric productivity. Here, we use a stochastic approach to invert the mid-Proterozoic Δ¹⁷O record for a new estimate of atmospheric 𝘱O₂, leveraging explicit coupling of 𝘱O₂ and biospheric productivity in a biogeochemical Earth system model to refine the range of atmospheric 𝘱O₂ values that is consistent with a given observed Δ¹⁷O. Using this approach, we find new evidence that atmospheric oxygen levels were less than ∼1% of the present atmospheric level (PAL) for at least some intervals of the Proterozoic Eon.

text: Large mass-independent oxygen isotope fractionations in mid-Proterozoic sediments: Evidence for a low-oxygen atmosphere? Earth's ocean-atmosphere system has undergone a dramatic but protracted increase in oxygen (O₂) abundance. This environmental transition ultimately paved the way for the rise of multicellular life and provides a blueprint for how a biosphere can transform a planetary surface. However, estimates of atmospheric oxygen levels for large intervals of Earth's history still vary by orders of magnitude-foremost for Earth's middle history. Historically, estimates of mid-Proterozoic (1.9-0.8 Ga) atmospheric oxygen levels are inferred based on the kinetics of reactions occurring in soils or in the oceans, rather than being directly tracked by atmospheric signatures. Rare oxygen isotope systematics-based on quantifying the rare oxygen isotope ¹⁷O in addition to the conventionally determined ¹⁶O and ¹⁸O-provide a means to track atmospheric isotopic signatures and thus potentially provide more direct estimates of atmospheric oxygen levels through time. Oxygen isotope signatures that deviate strongly from the expected mass-dependent relationship between ¹⁶O, ¹⁷O, and ¹⁸O develop during ozone formation, and these "mass-independent" signals can be transferred to the rock record during oxidation reactions in surface environments that involve atmospheric O₂. The magnitude of these signals is dependent upon 𝘱O₂, 𝘱CO₂, and the overall extent of biospheric productivity. Here, we use a stochastic approach to invert the mid-Proterozoic Δ¹⁷O record for a new estimate of atmospheric 𝘱O₂, leveraging explicit coupling of 𝘱O₂ and biospheric productivity in a biogeochemical Earth system model to refine the range of atmospheric 𝘱O₂ values that is consistent with a given observed Δ¹⁷O. Using this approach, we find new evidence that atmospheric oxygen levels were less than ∼1% of the present atmospheric level (PAL) for at least some intervals of the Proterozoic Eon.

year: 2020

title: Isolation and characterisation of two chymotrypsins from Allocyttus niger (black oreo dory) viscera

authors: Krzyzosiak, J.

subjects: chymotrypsin

abstract: Two serine proteases from the viscera of deep-sea fish, black oreo dory (Allocyttus niger),were purified by hydrophobic, affinity, and cation exchange chromatography. They were designated as chymotrypsins on the basis of substrate specificity and susceptibility to inhibitors. The pH optima of chymotrypsin I and II were 8.6 and 10, respectively. Chymotrypsin II retained a remarkable 80% activity at pH 12.5. Thermal stability of both enzymes was enhanced in the presence of calcium ions. Both chymotrypsins were inhibited by high concentrations of substrate Suc-AAPF-NA.

text: Isolation and characterisation of two chymotrypsins from Allocyttus niger (black oreo dory) viscera Two serine proteases from the viscera of deep-sea fish, black oreo dory (Allocyttus niger),were purified by hydrophobic, affinity, and cation exchange chromatography. They were designated as chymotrypsins on the basis of substrate specificity and susceptibility to inhibitors. The pH optima of chymotrypsin I and II were 8.6 and 10, respectively. Chymotrypsin II retained a remarkable 80% activity at pH 12.5. Thermal stability of both enzymes was enhanced in the presence of calcium ions. Both chymotrypsins were inhibited by high concentrations of substrate Suc-AAPF-NA.

year: 1997

title: Taku manatawa, taku manapou. The learning of te reo Māori in adulthood: Perceptions of its contribution to overall wellbeing

authors: Rolleston, Jamie Huia

subjects: maori

abstract: Ko te tāhuhu o tēnei whare rangahau ko te toiora o te tangata. Ko te tūāpapa o te whare, ko te reo Māori. E toru ngā pou tūhono i te tāhuhu ki te papa, mō tēnei rangahau ko aua pou ko te oranga wairua, ko te oranga whānau, ko te oranga tinana. Ko tā tēnei rangahau he āta mātai i aua pou e toru e toko ana i te toiora o te tangata, ā, kia mātai hoki i te hononga o te reo Māori ki aua pou e toru me te toiora tangata.
Ko te pātai matua kei te aroaro o tēnei rangahau ko tēnei : He aha ngā hua o te ako i te reo Māori hei reo tuarua mō te hunga pakeke ake i te tekau mā waru tau?
E toru ngā wāhanga o te pātai matua:
1. He aha ngā hua ā-wairua?
2. He aha ngā hua ā-whānau?
3. He aha ngā hua ā-tinana?
E toru hoki ngā huarahi i whāia ai kia rapua he whakautu ki aua pātai. Tuatahi ake, i tirohia ngā mātātuhi maha e hāngai ana ki te toiora tangata (Upoko tuarua), arā, ko ngā kōrero a ngā mātanga o te ao whānui, o te ao Māori hoki kua whakawhārikitia kētia ki runga i tēnei kaupapa. Ka rua, i tīmata āku ake ketuketunga ki tētahi pākiki ā-ipurangi, ā, i tukuna atu tēnā ki te marea kia whai māramatanga mō ngā momo pānga a te reo Māori ki a rātou (Upoko tuatoru). Ka mutu, i uiuitia tokorima ngā tāngata kia rongo ai i ō rātou wheako ako i te reo me ngā hua i puta mai ki a rātou (Upoko tuawhā).
E ai ki te hunga i whai wāhi mai ki tēnei rangahau ko te hua nui o te reo Māori ko te whai hononga ki te ao Māori me te tuakiri Māori. I puta mai tēnei kōrero i roto i te pākiki me ngā uiuinga. He mātotoru ngā kōrero a te hunga nei mō te kimi i te mea ngaro, ā, mā te ako i te reo Māori i kitea te mea i te ngaro, anō nei i whakakīkīngia tētahi rua ki roto i te tangata. I roto i te pākiki me ngā uiuinga i kumea mai ai i te hunga nei ngā kōrero mō ō rātou oranga i mua i te ako i te reo, i te tīmatanga o te ako i te reo, me te nāianei hoki, ā, he mārakerake noa te kitea he hoa haere te whanaketanga o te reo Māori me te whanaketanga o te taha Māori o te tangata me tōna māramatanga ki a ia anō, ā, mā reira e piki ai he taha toiora o te tangata. I tua atu i wēnei hua, he maha kē atu ngā hua o te reo i puta mai ai i te rangahau nei, ko te whai hononga ki te taiao, ki te whakapapa, ko te whakapiki māia, ā, ko te whai mahi hoki ētahi o ngā hua i tino kitea i roto i ngā whakautu a tēnei hunga.

text: Taku manatawa, taku manapou. The learning of te reo Māori in adulthood: Perceptions of its contribution to overall wellbeing Ko te tāhuhu o tēnei whare rangahau ko te toiora o te tangata. Ko te tūāpapa o te whare, ko te reo Māori. E toru ngā pou tūhono i te tāhuhu ki te papa, mō tēnei rangahau ko aua pou ko te oranga wairua, ko te oranga whānau, ko te oranga tinana. Ko tā tēnei rangahau he āta mātai i aua pou e toru e toko ana i te toiora o te tangata, ā, kia mātai hoki i te hononga o te reo Māori ki aua pou e toru me te toiora tangata.
Ko te pātai matua kei te aroaro o tēnei rangahau ko tēnei : He aha ngā hua o te ako i te reo Māori hei reo tuarua mō te hunga pakeke ake i te tekau mā waru tau?
E toru ngā wāhanga o te pātai matua:
1. He aha ngā hua ā-wairua?
2. He aha ngā hua ā-whānau?
3. He aha ngā hua ā-tinana?
E toru hoki ngā huarahi i whāia ai kia rapua he whakautu ki aua pātai. Tuatahi ake, i tirohia ngā mātātuhi maha e hāngai ana ki te toiora tangata (Upoko tuarua), arā, ko ngā kōrero a ngā mātanga o te ao whānui, o te ao Māori hoki kua whakawhārikitia kētia ki runga i tēnei kaupapa. Ka rua, i tīmata āku ake ketuketunga ki tētahi pākiki ā-ipurangi, ā, i tukuna atu tēnā ki te marea kia whai māramatanga mō ngā momo pānga a te reo Māori ki a rātou (Upoko tuatoru). Ka mutu, i uiuitia tokorima ngā tāngata kia rongo ai i ō rātou wheako ako i te reo me ngā hua i puta mai ki a rātou (Upoko tuawhā).
E ai ki te hunga i whai wāhi mai ki tēnei rangahau ko te hua nui o te reo Māori ko te whai hononga ki te ao Māori me te tuakiri Māori. I puta mai tēnei kōrero i roto i te pākiki me ngā uiuinga. He mātotoru ngā kōrero a te hunga nei mō te kimi i te mea ngaro, ā, mā te ako i te reo Māori i kitea te mea i te ngaro, anō nei i whakakīkīngia tētahi rua ki roto i te tangata. I roto i te pākiki me ngā uiuinga i kumea mai ai i te hunga nei ngā kōrero mō ō rātou oranga i mua i te ako i te reo, i te tīmatanga o te ako i te reo, me te nāianei hoki, ā, he mārakerake noa te kitea he hoa haere te whanaketanga o te reo Māori me te whanaketanga o te taha Māori o te tangata me tōna māramatanga ki a ia anō, ā, mā reira e piki ai he taha toiora o te tangata. I tua atu i wēnei hua, he maha kē atu ngā hua o te reo i puta mai ai i te rangahau nei, ko te whai hononga ki te taiao, ki te whakapapa, ko te whakapiki māia, ā, ko te whai mahi hoki ētahi o ngā hua i tino kitea i roto i ngā whakautu a tēnei hunga.

year: 2015