Novel genetic engineering technology which increases leaf lipid content modifies the ensiling properties of perennial ryegrass : a thesis presented in partial fulfillment of the requirements for the degree of Masters in Agricultural Science at Massey University, Palmerston North

A novel strategy to increase the metabolisable energy (ME) yield of pastures has been the development of a genetic engineering technology which increases the leaf lipid content and biomass production of perennial ryegrass (PRG). Outdoor plot/feeding trials of genetically engineered crops are prohibited under the current New Zealand (NZ) regulatory framework. However, this high lipid PRG may become available to farmers and eventually be used to make silage, which could fulfill an important role as a high ME, inexpensive, supplementary feed for livestock. Ensiling preserves a crop’s nutrients at a high moisture content and at a low pH, by microbial fermentation of plant sugars into lactic acid under anaerobic conditions. In a preliminary investigation into the ensiling biochemistry of this high lipid PRG, glasshouse-grown materials were wilted and inoculated, and then ensiled on a miniature scale. A series of method development ensiling experiments revealed that non-transgenic PRG grown in glasshouse conditions during the NZ spring/summer was very difficult to ensile naturally, due to its low water soluble sugar to buffering capacity ratio. In order to generate well-preserved silage in the main experiment, glucose was added (post-harvest) to a non-transgenic PRG genotype (WT) and two transgenic PRG genotypes containing ‘medium’ and ‘high’ leaf lipid levels (ML and HL). The HL plants produced 51% more dry biomass than WT during the regrowth period. Pre-ensiled HL had 31% higher fatty acid content, 70% higher nitrate content and a 17% lower water soluble sugar to crude protein ratio than WT. ML was intermediate. The glasshouse growth environment resulted in an atypical overall PRG nutritional composition. WT, ML and HL underwent a similar fermentation, and nutrients were well-preserved. The nutritional differences in the ensiled material largely reflected those in their fresh counterparts, although a longer wilt caused greater overall digestible nutrient losses in HL. In an in vitro rumen incubation experiment the fatty acids in HL silage exhibited less complete biohydrogenation than in fresh and ensiled WT. Experiments using a range of high lipid PRG lines grown in a range of environments will be needed to validate these results

Sobre el patriarcat

En aquest article Veronica Beechey planteja l’examen d’una selecció de textos feministes sobre el patriarcat (entre altres les contribucions de Kate Millett, Sheila Jeffreys, McKenzie, etc.) i analitza també la conceptualització dualista de la societat implícita en aquests textos (sistema classe econòmica versus sistema classe sexual; mode de producció familiar versus mode de producció industrial, etc.). Beechey fa també referència als problemes que es presenten quan el patriarcat i el capitalisme són tractats com a estructures diferents (per exemple, ús de diferents conceptes de reproducció; separació del patriarcat d’altres aspectes del mode de producció; el fet que tot mode de producció suposa producció i reproducció; etc.). Després d’una extensa i profunda anàlisi crítica dels diferents usos que del concepte patriarcal han fet diferents teòrics (Mitchell i els sistemes de parentiu; Hartman i la dominació masclista; Eisenstein i la jerarquia sexual; etcètera), l’autora apunta que caldria concretar una teoria específica del patriarcat i investigar les formes de patriarcat que existeixen en les institucions socials concretes

Eureka! Women and birthing on the Ballarat goldfields in the 1850s

The Ballarat goldfields were a raucous, noisy, exhilarating place that was a tent home for thousands of men, women and children in the 1850s. The Ballarat goldrush and the Eureka Rebellion are among the most significant events in the history of Australia. They set the scene for this study titled Eureka! Women and birthing on the Ballarat goldfields in the 1850s. This qualitative study utilised and historical research method informed by a feminist perspective. This account reveals the story of women’s lives and their birthing at this time as found in historical documents. These documents revealed that the women birthed in their tents with a female friend, relative or lay midwife present. Trained midwives were rare and doctors were too expensive for the majority of poor diggers with no guarantee they were genuine. While most women birthed safely the appalling conditions, infection and birth complications all contributed to high rates of maternal and neonatal mortality and morbidity. This study has implications for both women and midwives. Hearing voices through this story of their lives and birthing will expand the understanding of issues specific to women. The sharing of the story of birthing in the 1850s will raise awareness of the connections between midwifery history and the twenty-first century giving midwives an appreciation of the past along with different perspectives and greater understanding of women and birthing so their midwifery practice in the future will be enhanced

Evidence for the Existence of a Channel in the Glucose-Specific Carrier EIIGlc of the Salmonella typhimurium Phosphoenolpyruvate-Dependent Phosphotransferase System

The effect of membrane-impermeable sulfhydryl reagents on glucose-specific enzyme II (EIIGlc) activity has been studied in Salmonella typhimurium whole cells and in properly sealed inverted cytoplasmic membrane vesicles. Glutathione N-hexylmaleimide and N-polymethylenecarboxymaleimides inactivate methyl α-D-glucopyranoside (α-MeGlc) transport and phosphorylation in whole cell preparations at a dithiol that can be protected by oxidizing reagents, trivalent arsenicals, or phosphorylation of EIIGlc. Accessibility to this activity-linked site is restricted to small apolar reagents or to polar reagents with a hydrophobic spacer between the polar group and the reactive maleimide moiety. These same reagents inactivate α-MeGlc phosphorylation in inverted cytoplasmic membrane vesicles. Inhibition results from reaction at a dithiol that can be protected by nonpermeant mercurials, oxidants, and arsenicals as well as by phosphorylation of EII. The characteristics of this site are virtually identical with those of the activity-linked dithiol elucidated in intact cells. No evidence could be found for a second activity-linked site on the other side of the membrane when the permeable reagent N-ethylmaleimide was used. Since only one activity-linked dithiol can be detected with sealed inverted membrane vesicles or intact cells and it is accessible to membrane-impermeable sulfhydryl reagents from both sides of the cytoplasmic membrane, we suggest that it is located in a channel constructured by the carrier and that the channel spans the membrane. A second dithiol, not essential for activity, is located near the outer surface of the cytoplasmic membrane

Explaining Reinforcement Learning with Shapley Values

For reinforcement learning systems to be widely adopted, their users must understand and trust them. We present a theoretical analysis of explaining reinforcement learning using Shapley values, following a principled approach from game theory for identifying the contribution of individual players to the outcome of a cooperative game. We call this general framework Shapley Values for Explaining Reinforcement Learning (SVERL). Our analysis exposes the limitations of earlier uses of Shapley values in reinforcement learning. We then develop an approach that uses Shapley values to explain agent performance. In a variety of domains, SVERL produces meaningful explanations that match and supplement human intuition.Comment: 12 pages, 9 figures. Accepted at ICML 202

Explaining Reinforcement Learning with Shapley Values

For reinforcement learning systems to be widely adopted, their users must understand and trust them. We present a theoretical analysis of explaining reinforcement learning using Shapley values, following a principled approach from game theory for identifying the contribution of individual players to the outcome of a cooperative game. We call this general framework Shapley Values for Explaining Reinforcement Learning (SVERL). Our analysis exposes the limitations of earlier uses of Shapley values in reinforcement learning. We then develop an approach that uses Shapley values to explain agent performance. In a variety of domains, SVERL produces meaningful explanations that match and supplement human intuition