title: Arginase from kiwifruit: properties and seasonal variation

authors: Hale, C.A.

subjects: actinidia deliciosa

abstract: The in vitro activity of arginase (EC 3.5.3.1) was investigated in youngest-mature leaves and roots (1-3 mm diameter) of kiwifruit vines (Actinidia deliciosa var. deliciosa) during an annual growth cycle, and enzyme from root material partially purified. No seasonal trend in the specific activity of arginase was observed in roots. Measurements in leaves, however, rose gradually during early growth and plateaued c. 17 weeks after budbreak. Changes in arginase activity were not correlated with changes in the concentration of arginine (substrate) or glutamine (likely end-product of arginine catabolism) in either tissue during the growth cycle. Purification was by (NH4)2SO4 precipitation and DEAE-cellulose chromatography. The kinetic properties of the enzyme, purified 60-fold over that in crude extracts, indicated a pH optimum of 8.8, and a Km (L-arginine) of 7.85 mM. Partially-purified enzyme was deactivated by dialysis against EDTA, and reactivated in the presence of Mn²⁺, Co²⁺, and Ni²⁺.

text: Arginase from kiwifruit: properties and seasonal variation The in vitro activity of arginase (EC 3.5.3.1) was investigated in youngest-mature leaves and roots (1-3 mm diameter) of kiwifruit vines (Actinidia deliciosa var. deliciosa) during an annual growth cycle, and enzyme from root material partially purified. No seasonal trend in the specific activity of arginase was observed in roots. Measurements in leaves, however, rose gradually during early growth and plateaued c. 17 weeks after budbreak. Changes in arginase activity were not correlated with changes in the concentration of arginine (substrate) or glutamine (likely end-product of arginine catabolism) in either tissue during the growth cycle. Purification was by (NH4)2SO4 precipitation and DEAE-cellulose chromatography. The kinetic properties of the enzyme, purified 60-fold over that in crude extracts, indicated a pH optimum of 8.8, and a Km (L-arginine) of 7.85 mM. Partially-purified enzyme was deactivated by dialysis against EDTA, and reactivated in the presence of Mn²⁺, Co²⁺, and Ni²⁺.

year: 1997

title: Rationale and methodology for a national study of higher education science and engineering learning communities

authors: Coll, Richard K.

subjects: high education

abstract: This paper reports on a major national study of higher education science and engineering learning communities in New Zealand. The scope of the research project along with a description of the methodology and method used in the study together with rationale for the study and research approach adopted are provided here. Details of the theoretical framework and a discussion of paradigm that underpinned the study are presented. A discussion of issues of reliability and validity and measures taken to maximize these also is presented. The paper begins with an overview of the New Zealand compulsory education sector and traces the now multitudinous pathways into higher education nationally. It thus provides a valuable context for this national study of higher education science and engineering learning communities.

text: Rationale and methodology for a national study of higher education science and engineering learning communities This paper reports on a major national study of higher education science and engineering learning communities in New Zealand. The scope of the research project along with a description of the methodology and method used in the study together with rationale for the study and research approach adopted are provided here. Details of the theoretical framework and a discussion of paradigm that underpinned the study are presented. A discussion of issues of reliability and validity and measures taken to maximize these also is presented. The paper begins with an overview of the New Zealand compulsory education sector and traces the now multitudinous pathways into higher education nationally. It thus provides a valuable context for this national study of higher education science and engineering learning communities.

year: 2008

title: Current state of the Rotorua Lakes

authors: Hamilton, David P.

abstract: The Rotorua Te Arawa Lakes’ programme of restoration has arguably been the most ambitious and effective of any for a group of lakes around the world. It has been characterised by willingness to ‘try things’, to be guided closely by scientific input, and to
now have excellent structures for monitoring and implementation of actions. Still, major challenges remain. One of these is the potential for a sense of complacency, particularly when some lakes have responded extremely positively to in-lake treatments (e.g. Rotorua) or major one-off actions (e.g. Rotoiti). It is essential that these improvements in lake water quality, some of which may not be able to be maintained indefinitely in their current mode, not delay further catchment management actions.
Another challenge is exotic oxygen weeds, particularly where it is difficult to harvest large accumulations. The final challenge relates to climate. Recent years have been characterised by droughts and intense rainfall events that challenge land management practices. Further, surface water temperatures in the lakes in 2015 have been greater than at any time in the past. If these changes are symptomatic of a future climate, then there will need to be greater effort put into building resilience in the lakes and their catchments.

text: Current state of the Rotorua Lakes The Rotorua Te Arawa Lakes’ programme of restoration has arguably been the most ambitious and effective of any for a group of lakes around the world. It has been characterised by willingness to ‘try things’, to be guided closely by scientific input, and to
now have excellent structures for monitoring and implementation of actions. Still, major challenges remain. One of these is the potential for a sense of complacency, particularly when some lakes have responded extremely positively to in-lake treatments (e.g. Rotorua) or major one-off actions (e.g. Rotoiti). It is essential that these improvements in lake water quality, some of which may not be able to be maintained indefinitely in their current mode, not delay further catchment management actions.
Another challenge is exotic oxygen weeds, particularly where it is difficult to harvest large accumulations. The final challenge relates to climate. Recent years have been characterised by droughts and intense rainfall events that challenge land management practices. Further, surface water temperatures in the lakes in 2015 have been greater than at any time in the past. If these changes are symptomatic of a future climate, then there will need to be greater effort put into building resilience in the lakes and their catchments.

year: 2015