title: The inflection point hypothesis: The relationship between the temperature dependence of enzyme-catalyzed reaction rates and microbial growth rates.

authors: Prentice, Erica J.

subjects: Peptides and proteins

abstract: The temperature dependence of biological rates at different scales (from individual enzymes to isolated organisms to ecosystem processes such as soil respiration and photosynthesis) is the subject of much historical and contemporary research. The precise relationship between the temperature dependence of enzyme rates and those at larger scales is not well understood. We have developed macromolecular rate theory (MMRT) to describe the temperature dependence of biological processes at all scales. Here we formalize the scaling relationship by investigating MMRT both at the molecular scale (constituent enzymes) and for growth of the parent organism. We demonstrate that the inflection point (𝘛ᵢₙ𝒻) for the temperature dependence of individual metabolic enzymes coincides with the optimal growth temperature for the parent organism, and we rationalize this concordance in terms of the necessity for linearly correlated rates for metabolic enzymes over fluctuating environmental temperatures to maintain homeostasis. Indeed, 𝘛ᵢₙ𝒻 is likely to be under strong selection pressure to maintain coordinated rates across environmental temperature ranges. At temperatures at which rates become uncorrelated, we postulate a regulatory catastrophe and organism growth rates precipitously decline at temperatures where this occurs. We show that the curvature in the plots of the natural log of the rate versus temperature for individual enzymes determines the curvature for the metabolic process overall and the curvature for the temperature dependence of the growth of the organism. We have called this "the inflection point hypothesis", and this hypothesis suggests many avenues for future investigation, including avenues for engineering the thermal tolerance of organisms.

text: The inflection point hypothesis: The relationship between the temperature dependence of enzyme-catalyzed reaction rates and microbial growth rates. The temperature dependence of biological rates at different scales (from individual enzymes to isolated organisms to ecosystem processes such as soil respiration and photosynthesis) is the subject of much historical and contemporary research. The precise relationship between the temperature dependence of enzyme rates and those at larger scales is not well understood. We have developed macromolecular rate theory (MMRT) to describe the temperature dependence of biological processes at all scales. Here we formalize the scaling relationship by investigating MMRT both at the molecular scale (constituent enzymes) and for growth of the parent organism. We demonstrate that the inflection point (𝘛ᵢₙ𝒻) for the temperature dependence of individual metabolic enzymes coincides with the optimal growth temperature for the parent organism, and we rationalize this concordance in terms of the necessity for linearly correlated rates for metabolic enzymes over fluctuating environmental temperatures to maintain homeostasis. Indeed, 𝘛ᵢₙ𝒻 is likely to be under strong selection pressure to maintain coordinated rates across environmental temperature ranges. At temperatures at which rates become uncorrelated, we postulate a regulatory catastrophe and organism growth rates precipitously decline at temperatures where this occurs. We show that the curvature in the plots of the natural log of the rate versus temperature for individual enzymes determines the curvature for the metabolic process overall and the curvature for the temperature dependence of the growth of the organism. We have called this "the inflection point hypothesis", and this hypothesis suggests many avenues for future investigation, including avenues for engineering the thermal tolerance of organisms.

year: 2020

title: Evidence of bias in assessment of fisheries management impacts

authors: Slooten, Elizabeth

subjects: Science & Technology

abstract: Melnychuk et al.'s analysis (1) is not a trustworthy evaluation of the effectiveness of fisheries management. Given the strong bias in the NZ sample, it would be surprising if NZ was the only country for which there were problems with the selection of respondents. Instead of providing a robust analysis of the effectiveness of fisheries management, Melnychuk et al. (1) seem to be arguing for business-as-usual while ignoring broader issues, such as ecosystem impacts, environmental change, and social outcomes. Such an analysis does fisheries management no service.

text: Evidence of bias in assessment of fisheries management impacts Melnychuk et al.'s analysis (1) is not a trustworthy evaluation of the effectiveness of fisheries management. Given the strong bias in the NZ sample, it would be surprising if NZ was the only country for which there were problems with the selection of respondents. Instead of providing a robust analysis of the effectiveness of fisheries management, Melnychuk et al. (1) seem to be arguing for business-as-usual while ignoring broader issues, such as ecosystem impacts, environmental change, and social outcomes. Such an analysis does fisheries management no service.

year: 2017-06-20

title: Personality and Representation in Environmental Law

authors: Daya-Winterbottom, Trevor

abstract: Jorge Vinuales from the University of Cambridge observed in his working paper on “Law and the Anthropocene” that law is founded on a series of core concepts, such as, “legal personality, representation, obligation, debt, causality or damage” (CEENRG Working Papers 2016- 4, page 49). This led him to note that a “significant problem” faced by environmental law is how to flesh out these core concepts in relation to the protection of the environment (page 53). For example, should we regard natural resources (e.g. rivers or mountains) as “subjects” of environmental law with their “own interests and capacity to act (through representation)”, or merely as the “objects” of environmental law – to be protected either “directly” as specific natural resources, or “indirectly” via the protection of the environment generally (page 53). This article interrogates these perspectives by reference to recent New Zealand developments.

text: Personality and Representation in Environmental Law Jorge Vinuales from the University of Cambridge observed in his working paper on “Law and the Anthropocene” that law is founded on a series of core concepts, such as, “legal personality, representation, obligation, debt, causality or damage” (CEENRG Working Papers 2016- 4, page 49). This led him to note that a “significant problem” faced by environmental law is how to flesh out these core concepts in relation to the protection of the environment (page 53). For example, should we regard natural resources (e.g. rivers or mountains) as “subjects” of environmental law with their “own interests and capacity to act (through representation)”, or merely as the “objects” of environmental law – to be protected either “directly” as specific natural resources, or “indirectly” via the protection of the environment generally (page 53). This article interrogates these perspectives by reference to recent New Zealand developments.

year: 2018-02-06