title: Overcoming barriers to circular product design

authors: Wang, Jason X.

abstract: The circular economy concept provides sustainability research with a new vision in place of the present linear economic model. This study focuses on product design, the starting point of applying circular thinking in supply chain functions. We investigate barriers to circular product design from a stakeholder perspective. Using thematic analysis and data collected from 15 semi-structured interviews in New Zealand, we identify four prominent barriers: financial constraints, inadequate infrastructure, government inaction, and global market barriers. The most influential stakeholder classes for overcoming the barriers are consumers, industry leaders, and governments. Circumventing measures lie in sustainable end-of-life product and waste management, resource circularity, modularity and standardization in design, and supply chain collaboration. Based on these new insights, we develop a roadmap for circular product design, providing practical guidance for businesses and policymakers. We also add to research on stakeholder theory by exploring its descriptive aspect in the context of a transition to circular economy at the supply chain level.

text: Overcoming barriers to circular product design The circular economy concept provides sustainability research with a new vision in place of the present linear economic model. This study focuses on product design, the starting point of applying circular thinking in supply chain functions. We investigate barriers to circular product design from a stakeholder perspective. Using thematic analysis and data collected from 15 semi-structured interviews in New Zealand, we identify four prominent barriers: financial constraints, inadequate infrastructure, government inaction, and global market barriers. The most influential stakeholder classes for overcoming the barriers are consumers, industry leaders, and governments. Circumventing measures lie in sustainable end-of-life product and waste management, resource circularity, modularity and standardization in design, and supply chain collaboration. Based on these new insights, we develop a roadmap for circular product design, providing practical guidance for businesses and policymakers. We also add to research on stakeholder theory by exploring its descriptive aspect in the context of a transition to circular economy at the supply chain level.

year: 2021-10-29

title: Using putative bovine embryonic stem cell-like cells for nuclear transfer cloning to determine their functional potential

authors: Appleby, Sarah Jane

subjects: cloning

abstract: The potential for cloning to improve dissemination of elite genetics has been a goal of livestock scientists for many years. However, efficiency of this technique has remained low compared to other in vitro embryo production methods. One hypothesised method to improve cloning efficiency is to use donor cells that require less reprogramming, as donor cells must be reprogrammed to an embryonic state in order to generate a whole embryo. Somatic cells are the most readily available cell type for donor cells, making them the most often used, but also the most differentiated. Embryonic stem cells (ESCs) are pluripotent cells, capable of generating all cell types. As ESCs are at a much lower differentiated state, they would be hypothesised to improve cloning efficiency. However, ESCs have only been derived from mice and rats. Using a novel culture method, bovine ESC-like cells (ePSCs) can be maintained for several weeks in vitro. The aim of this research was to evaluate the efficiency of using these bovine ePSCs in nuclear transfer (NT) cloning.

ePSC colonies were generated from in vitro produced blastocysts and arrested into mitosis with an overnight incubation with 500 nM nocodazole. A method was devised to isolate single cells, using serial treatment in dispase, pronase, and trituration in Ca-Mg-free dissociation media containing cytochalasin B. Arrested colonies were characterised for the degree of mitotic arrest, showing approximately 40% of the colony was arrested in mitosis, and the proportion of cells in DNA synthesis phase had significantly decreased. Cells expressing pluripotency genes SOX2 and NANOG were enriched in the central dome-shaped colony. Analysis of mitotic cells showed that 63% were also pluripotent. NT cloning was optimised for use with donor cells synchronised into mitosis. Pronase treated donor cells fused to metaphase II arrested cytoplasts in isoosmolar fusion buffer resulted in highest fusion rate. Comparison of artificial activation with ionomycin followed by DMAP, CHX, or anisomycin showed that ionomycin/DMAP activation produced the highest blastocyst development rate. Using these optimised conditions, cloning with ePSC donor cells resulted in a three-fold higher blastocyst development than with somatic cells. As donor cells were in metaphase, they contained double the normal amount of DNA. Therefore, it was important to assess the karyotype of blastocysts for normal ploidy. A bimodal distribution of chromosome spreads of around 60 and 120 chromosomes was observed, with higher chromosome numbers apparently restricted to trophoblast cells.

Further validation of blastocyst ploidy, characterisation of donor cells used for NT, and continued optimisation of protocols, through double cytoplast cloning or timing of gap between fusion and activation, is required before completing in vivo cloning trials. Embryo transfer trials will be the final step in addressing the long-term aim of this project: to demonstrate that elite bovine embryos can be converted into ePSCs and then ePSC derived animals.

text: Using putative bovine embryonic stem cell-like cells for nuclear transfer cloning to determine their functional potential The potential for cloning to improve dissemination of elite genetics has been a goal of livestock scientists for many years. However, efficiency of this technique has remained low compared to other in vitro embryo production methods. One hypothesised method to improve cloning efficiency is to use donor cells that require less reprogramming, as donor cells must be reprogrammed to an embryonic state in order to generate a whole embryo. Somatic cells are the most readily available cell type for donor cells, making them the most often used, but also the most differentiated. Embryonic stem cells (ESCs) are pluripotent cells, capable of generating all cell types. As ESCs are at a much lower differentiated state, they would be hypothesised to improve cloning efficiency. However, ESCs have only been derived from mice and rats. Using a novel culture method, bovine ESC-like cells (ePSCs) can be maintained for several weeks in vitro. The aim of this research was to evaluate the efficiency of using these bovine ePSCs in nuclear transfer (NT) cloning.

ePSC colonies were generated from in vitro produced blastocysts and arrested into mitosis with an overnight incubation with 500 nM nocodazole. A method was devised to isolate single cells, using serial treatment in dispase, pronase, and trituration in Ca-Mg-free dissociation media containing cytochalasin B. Arrested colonies were characterised for the degree of mitotic arrest, showing approximately 40% of the colony was arrested in mitosis, and the proportion of cells in DNA synthesis phase had significantly decreased. Cells expressing pluripotency genes SOX2 and NANOG were enriched in the central dome-shaped colony. Analysis of mitotic cells showed that 63% were also pluripotent. NT cloning was optimised for use with donor cells synchronised into mitosis. Pronase treated donor cells fused to metaphase II arrested cytoplasts in isoosmolar fusion buffer resulted in highest fusion rate. Comparison of artificial activation with ionomycin followed by DMAP, CHX, or anisomycin showed that ionomycin/DMAP activation produced the highest blastocyst development rate. Using these optimised conditions, cloning with ePSC donor cells resulted in a three-fold higher blastocyst development than with somatic cells. As donor cells were in metaphase, they contained double the normal amount of DNA. Therefore, it was important to assess the karyotype of blastocysts for normal ploidy. A bimodal distribution of chromosome spreads of around 60 and 120 chromosomes was observed, with higher chromosome numbers apparently restricted to trophoblast cells.

Further validation of blastocyst ploidy, characterisation of donor cells used for NT, and continued optimisation of protocols, through double cytoplast cloning or timing of gap between fusion and activation, is required before completing in vivo cloning trials. Embryo transfer trials will be the final step in addressing the long-term aim of this project: to demonstrate that elite bovine embryos can be converted into ePSCs and then ePSC derived animals.

year: 2015

title: A discontinuous ca. 80 ka record of Late Quaternary environmental change from Lake Omapere, Northland, New Zealand

authors: Newnham, Rewi M.

subjects: Last Glacial

abstract: We present an integrated record of environmental change from Lake Omapere, Northland, New Zealand, based on palaeolimnological analysis of a 7-m-long core and eight adjunct cores spanning part of the last 80 calendar (cal.) ka. The chronology was developed using tephrochronology, palaeomagnetism and radiocarbon dating together with climato- and palyno-stratigraphy. Two of 14 tephra layers in the cores provide markers for correlating the record with other New Zealand climato-stratigraphic sequences, deep-sea cores and the global marine isotope record. Pollen, diatom, palaeomagnetic, sedimentologic and pigment analyses show that Lake Omapere, currently 2 m deep, has had a discontinuous history. Occupying a shallow basin perched partly within old basalt lavas, the initial (alkaline) lake formed towards the end of MIS 5a at ca. 80 cal. ka, presumably because of blockage of local drainage of a swampy alluvial floodplain, inundating peat deposits and forest trees, including kauri (Agathis australis). The lake filled rapidly to a level 1–2 m above that at present. Such filling was probably unrelated to climate but a subsequent phase of variable but generally falling lake levels and increasing dystrophy may have been climatically controlled, commencing during MIS 4 and culminating in periods early in MIS 3 when the lake became swampy or dry. Conditions of non-deposition (or non-preservation) obtained for most of the period after ca. 55 cal. ka (Rotoehu Ash) until formation of the modern lake approximately 600–700 cal. years ago or soon after, as indicated by the presence of Tephra-1, identified in part as Kaharoa Tephra (AD 1314), near the top of the core. The modern lake originated possibly through damming of the western outlet as a consequence of accelerated erosion accompanying earliest Polynesian deforestation, an interpretation supported by Maori oral tradition.
The pollen record indicates that beech Nothofagus (presumably N. truncata) was much more common in Northland during the Last Glacial, and that for this region the relative abundance of Nothofagus vs. Agathis pollen serves as a better indicator of cooler versus warmer intervals during the Quaternary than the ratio of tree to non-tree pollen. However, it seems likely that moisture balance was a more critical factor than temperature in vegetation composition and distribution, particularly during the LGM, and the long periods of hiatus may also be linked to a drier climate than present. Correlation coefficients between the pollen curves confirm that several tree species (Halocarpus bidwillii, H. biformis and Phyllocladus alpinus), previously palynologically concealed within generic taxonomic groups, occurred about two degrees latitude further north and at a much lower altitude than their current limits during cooler or drier phases of the Last Glacial. A temperature depression in Northland of 4 °C at various times during the Last Glacial is inferred from these range expansions. Nevertheless, the persistence of widespread forest cover suggests that the late Pleistocene climate of Northland was less severe than for most of the rest of New Zealand and strengthens the argument for a heightened temperature gradient across northern New Zealand during the Last Glacial.

text: A discontinuous ca. 80 ka record of Late Quaternary environmental change from Lake Omapere, Northland, New Zealand We present an integrated record of environmental change from Lake Omapere, Northland, New Zealand, based on palaeolimnological analysis of a 7-m-long core and eight adjunct cores spanning part of the last 80 calendar (cal.) ka. The chronology was developed using tephrochronology, palaeomagnetism and radiocarbon dating together with climato- and palyno-stratigraphy. Two of 14 tephra layers in the cores provide markers for correlating the record with other New Zealand climato-stratigraphic sequences, deep-sea cores and the global marine isotope record. Pollen, diatom, palaeomagnetic, sedimentologic and pigment analyses show that Lake Omapere, currently 2 m deep, has had a discontinuous history. Occupying a shallow basin perched partly within old basalt lavas, the initial (alkaline) lake formed towards the end of MIS 5a at ca. 80 cal. ka, presumably because of blockage of local drainage of a swampy alluvial floodplain, inundating peat deposits and forest trees, including kauri (Agathis australis). The lake filled rapidly to a level 1–2 m above that at present. Such filling was probably unrelated to climate but a subsequent phase of variable but generally falling lake levels and increasing dystrophy may have been climatically controlled, commencing during MIS 4 and culminating in periods early in MIS 3 when the lake became swampy or dry. Conditions of non-deposition (or non-preservation) obtained for most of the period after ca. 55 cal. ka (Rotoehu Ash) until formation of the modern lake approximately 600–700 cal. years ago or soon after, as indicated by the presence of Tephra-1, identified in part as Kaharoa Tephra (AD 1314), near the top of the core. The modern lake originated possibly through damming of the western outlet as a consequence of accelerated erosion accompanying earliest Polynesian deforestation, an interpretation supported by Maori oral tradition.
The pollen record indicates that beech Nothofagus (presumably N. truncata) was much more common in Northland during the Last Glacial, and that for this region the relative abundance of Nothofagus vs. Agathis pollen serves as a better indicator of cooler versus warmer intervals during the Quaternary than the ratio of tree to non-tree pollen. However, it seems likely that moisture balance was a more critical factor than temperature in vegetation composition and distribution, particularly during the LGM, and the long periods of hiatus may also be linked to a drier climate than present. Correlation coefficients between the pollen curves confirm that several tree species (Halocarpus bidwillii, H. biformis and Phyllocladus alpinus), previously palynologically concealed within generic taxonomic groups, occurred about two degrees latitude further north and at a much lower altitude than their current limits during cooler or drier phases of the Last Glacial. A temperature depression in Northland of 4 °C at various times during the Last Glacial is inferred from these range expansions. Nevertheless, the persistence of widespread forest cover suggests that the late Pleistocene climate of Northland was less severe than for most of the rest of New Zealand and strengthens the argument for a heightened temperature gradient across northern New Zealand during the Last Glacial.

year: 2004