title: A case for paid surrogate motherhood

authors: van Zyl, Liezl

subjects: commercial surrogacy

abstract: It has become commonplace to distinguish between altruistic and commercial surrogate motherhood. Altruistic surrogacy refers to cases where the surrogate mother is motivated by care or concern for an infertile couple, usually friends or relatives, to bear a child and then to transfer parental rights to them. Although she may be reimbursed for expenses associated with the pregnancy, she is not paid. Commercial surrogacy, on the other hand, is arranged through an agency which puts potential surrogates in contact with people wishing to employ their services. In addition to her expenses, the surrogate mother is paid a fee. Although both forms of surrogacy are morally controversial, the dominant view is that altruistic surrogacy is morally superior to, or at least less problematic than, commercial surrogacy.

text: A case for paid surrogate motherhood It has become commonplace to distinguish between altruistic and commercial surrogate motherhood. Altruistic surrogacy refers to cases where the surrogate mother is motivated by care or concern for an infertile couple, usually friends or relatives, to bear a child and then to transfer parental rights to them. Although she may be reimbursed for expenses associated with the pregnancy, she is not paid. Commercial surrogacy, on the other hand, is arranged through an agency which puts potential surrogates in contact with people wishing to employ their services. In addition to her expenses, the surrogate mother is paid a fee. Although both forms of surrogacy are morally controversial, the dominant view is that altruistic surrogacy is morally superior to, or at least less problematic than, commercial surrogacy.

year: 2008

title: A new intrinsic thermal parameter for enzymes reveals true temperature optima

authors: Peterson, Michelle E.

subjects: enzyme

abstract: Two established thermal properties of enzymes are the Arrhenius activation energy and thermal stability. Arising from anomalies found in the variation of enzyme activity with temperature, a comparison has been made of experimental data for the activity and stability properties of five different enzymes with theoretical models. The results provide evidence for a new and fundamental third thermal parameter of enzymes, Teq, arising from a subsecond timescale-reversible temperature-dependent equilibrium between the active enzyme and an inactive (or less active) form. Thus, at temperatures above its optimum, the decrease in enzyme activity arising from the temperature-dependent shift in this equilibrium is up to two orders of magnitude greater than what occurs through thermal denaturation. This parameter has important implications for our understanding of the connection between catalytic activity and thermostability and of the effect of temperature on enzyme reactions within the cell. Unlike the Arrhenius activation energy, which is unaffected by the source (“evolved”) temperature of the enzyme, and enzyme stability, which is not necessarily related to activity, Teq is central to the physiological adaptation of an enzyme to its environmental temperature and links the molecular, physiological, and environmental aspects of the adaptation of life to temperature in a way that has not been described previously. We may therefore expect the effect of evolution on Teq with respect to enzyme temperature/activity effects to be more important than on thermal stability. Teq is also an important parameter to consider when engineering enzymes to modify their thermal properties by both rational design and by directed enzyme evolution.

text: A new intrinsic thermal parameter for enzymes reveals true temperature optima Two established thermal properties of enzymes are the Arrhenius activation energy and thermal stability. Arising from anomalies found in the variation of enzyme activity with temperature, a comparison has been made of experimental data for the activity and stability properties of five different enzymes with theoretical models. The results provide evidence for a new and fundamental third thermal parameter of enzymes, Teq, arising from a subsecond timescale-reversible temperature-dependent equilibrium between the active enzyme and an inactive (or less active) form. Thus, at temperatures above its optimum, the decrease in enzyme activity arising from the temperature-dependent shift in this equilibrium is up to two orders of magnitude greater than what occurs through thermal denaturation. This parameter has important implications for our understanding of the connection between catalytic activity and thermostability and of the effect of temperature on enzyme reactions within the cell. Unlike the Arrhenius activation energy, which is unaffected by the source (“evolved”) temperature of the enzyme, and enzyme stability, which is not necessarily related to activity, Teq is central to the physiological adaptation of an enzyme to its environmental temperature and links the molecular, physiological, and environmental aspects of the adaptation of life to temperature in a way that has not been described previously. We may therefore expect the effect of evolution on Teq with respect to enzyme temperature/activity effects to be more important than on thermal stability. Teq is also an important parameter to consider when engineering enzymes to modify their thermal properties by both rational design and by directed enzyme evolution.

year: 2004

title: Toitu Te Moananui a Toi – The Effects of the MV Rena on the Water Quality, Chemistry and Zooplankton of Otaiti (Astrolabe Reef)

authors: Dempsey, Te Puea Toni

subjects: metal contamination

abstract: Humans have had a profound effect on the world’s oceans, particularly through pollution. Marine pollution incidents are particularly important and increasingly involve both petrochemical and metal contamination. The effects of complex high level, point source pollution events such as ship wrecks on larval recruitment to reef environments is not well understood. Larval settlement is heavily influenced by chemical cues, hence pollution events could have a long term influence on reef ecology, and the likelihood that planktonic zooplankton can entrain contaminants into the reef food web is also of concern.
This thesis aims to address concerns from local Tangata Whenua, government, researchers, stakeholders and the public about the long term recovery of Otaiti following the MV Rena shipwreck and subsequent reef contamination. The incident is a complex one involving metallic container debris contamination along with oil. Research focussed on assessing the effects of water borne contamination surrounding the wreck site in order to examine acute and chronic responses of planktonic invertebrates: (1) the influence of Rena and associated debris to the chemistry and quality of water in the benthic zone around the wreck, (2) the toxicity of contaminants to survivorship of zooplankton, and (3) the influence on contaminant plumes to zooplankton recruitment behaviour of Otaiti.
There is a clear effect from the Rena and its associated debris field on the water quality and chemistry of Otaiti. Aluminium and copper for example, were consistently elevated in dissolved and total metal concentrations around the debris field. Laboratory based exposure of zooplankton to realistic concentration gradients of Rena contaminated sediments resulted in increased mortality with increased contaminant concentrations. Behavioural responses of pelagic and settling invertebrates to Rena pollution influenced sediment highlighted sensitivity to associated contaminant plumes. This could have significant ecological implications to the recruitment behaviour of other planktonic organisms that rely on reef conspecifics and chemical cues to initiate settlement.
Ecological concepts such as ecosystem function and biodiversity dynamics (including recruitment) relate the life force and longevity of a system. Key concerns within the scope of this research were highlighted that may have implications to Tangata Whenua decision making in assessing the Mauri of Otaiti. It can be implied that the Rena continues to impact the Mauri of Otaiti due to the presence of contaminants within the debris field.

text: Toitu Te Moananui a Toi – The Effects of the MV Rena on the Water Quality, Chemistry and Zooplankton of Otaiti (Astrolabe Reef) Humans have had a profound effect on the world’s oceans, particularly through pollution. Marine pollution incidents are particularly important and increasingly involve both petrochemical and metal contamination. The effects of complex high level, point source pollution events such as ship wrecks on larval recruitment to reef environments is not well understood. Larval settlement is heavily influenced by chemical cues, hence pollution events could have a long term influence on reef ecology, and the likelihood that planktonic zooplankton can entrain contaminants into the reef food web is also of concern.
This thesis aims to address concerns from local Tangata Whenua, government, researchers, stakeholders and the public about the long term recovery of Otaiti following the MV Rena shipwreck and subsequent reef contamination. The incident is a complex one involving metallic container debris contamination along with oil. Research focussed on assessing the effects of water borne contamination surrounding the wreck site in order to examine acute and chronic responses of planktonic invertebrates: (1) the influence of Rena and associated debris to the chemistry and quality of water in the benthic zone around the wreck, (2) the toxicity of contaminants to survivorship of zooplankton, and (3) the influence on contaminant plumes to zooplankton recruitment behaviour of Otaiti.
There is a clear effect from the Rena and its associated debris field on the water quality and chemistry of Otaiti. Aluminium and copper for example, were consistently elevated in dissolved and total metal concentrations around the debris field. Laboratory based exposure of zooplankton to realistic concentration gradients of Rena contaminated sediments resulted in increased mortality with increased contaminant concentrations. Behavioural responses of pelagic and settling invertebrates to Rena pollution influenced sediment highlighted sensitivity to associated contaminant plumes. This could have significant ecological implications to the recruitment behaviour of other planktonic organisms that rely on reef conspecifics and chemical cues to initiate settlement.
Ecological concepts such as ecosystem function and biodiversity dynamics (including recruitment) relate the life force and longevity of a system. Key concerns within the scope of this research were highlighted that may have implications to Tangata Whenua decision making in assessing the Mauri of Otaiti. It can be implied that the Rena continues to impact the Mauri of Otaiti due to the presence of contaminants within the debris field.

year: 2015