title: Identification of quantitative trait loci for dynamic and steady-state photosynthetic traits in a barley mapping population

authors: Salter, William T.

subjects: Science & Technology

abstract: Enhancing the photosynthetic induction response to fluctuating light has been suggested as a key target for improvement in crop breeding programmes, with the potential to substantially increase whole-canopy carbon assimilation and contribute to crop yield potential. Rubisco activation may be the main physiological process that will allow us to achieve such a goal. In this study, we assessed the phenotype of Rubisco activation rate in a doubled haploid (DH) barley mapping population [131 lines from a Yerong/Franklin (Y/F) cross] after a switch from moderate to saturating light. Rates of Rubisco activation were found to be highly variable across the mapping population, with a median activation rate of 0.1 min−1 in the slowest genotype and 0.74 min−1 in the fastest genotype. A unique quantitative trait locus (QTL) for Rubisco activation rate was identified on chromosome 7H. This is the first report on the identification of a QTL for Rubisco activation rate in planta and the discovery opens the door to marker-assisted breeding to improve whole-canopy photosynthesis of barley. This also suggests that genetic factors other than the previously characterized Rubisco activase (RCA) isoforms on chromosome 4H control Rubisco activity. Further strength is given to this finding as this QTL co-localized with QTLs identified for steady-state photosynthesis and stomatal conductance. Several other distinct QTLs were identified for these steady-state traits, with a common overlapping QTL on chromosome 2H, and distinct QTLs for photosynthesis and stomatal conductance identified on chromosomes 4H and 5H, respectively. Future work should aim to validate these QTLs under field conditions so that they can be used to aid plant breeding efforts.

text: Identification of quantitative trait loci for dynamic and steady-state photosynthetic traits in a barley mapping population Enhancing the photosynthetic induction response to fluctuating light has been suggested as a key target for improvement in crop breeding programmes, with the potential to substantially increase whole-canopy carbon assimilation and contribute to crop yield potential. Rubisco activation may be the main physiological process that will allow us to achieve such a goal. In this study, we assessed the phenotype of Rubisco activation rate in a doubled haploid (DH) barley mapping population [131 lines from a Yerong/Franklin (Y/F) cross] after a switch from moderate to saturating light. Rates of Rubisco activation were found to be highly variable across the mapping population, with a median activation rate of 0.1 min−1 in the slowest genotype and 0.74 min−1 in the fastest genotype. A unique quantitative trait locus (QTL) for Rubisco activation rate was identified on chromosome 7H. This is the first report on the identification of a QTL for Rubisco activation rate in planta and the discovery opens the door to marker-assisted breeding to improve whole-canopy photosynthesis of barley. This also suggests that genetic factors other than the previously characterized Rubisco activase (RCA) isoforms on chromosome 4H control Rubisco activity. Further strength is given to this finding as this QTL co-localized with QTLs identified for steady-state photosynthesis and stomatal conductance. Several other distinct QTLs were identified for these steady-state traits, with a common overlapping QTL on chromosome 2H, and distinct QTLs for photosynthesis and stomatal conductance identified on chromosomes 4H and 5H, respectively. Future work should aim to validate these QTLs under field conditions so that they can be used to aid plant breeding efforts.

year: 2020

title: Establishment of THP-1 Monocytes with Compromised Mitochondrial Functions

authors: Chou, Tzu-wen Joy

subjects: THP-1 monocytes

abstract: The process of inflammation is important for both normal health and in a number of diseases, such as metabolic disorders, autoimmune diseases, and neurodegenerative diseases. Mitochondria are vital for the functioning of all cells. It had been implicated as a key player in inflammatory processes, especially through reactive oxygen species as signals of various immune responses. This study aimed to establish a THP-1 cell line with compromised mitochondrial functions, using antimycin A as a Complex III inhibitor, and to investigate the role of mitochondrial stress, as monitored by the expression of Hsp60, in inflammatory processes. High concentrations of antimycin A (100 and 200 μM) were cytotoxic to THP-1 monocytes that they were rapidly killed within 48 hours of exposure. Lower concentrations of antimycin A (5, 10, 25 and 50 μM) gave growth inhibition effects to THP-1 monocytes. Pyruvate and uridine were used with an intention of rescuing the THP-1 cell growth at lower antimycin A concentrations. The THP-1 monocytes treated with antimycin A with uridine and pyruvate showed more growth compared to the ones without uridine and pyruvate supplement. Yet this difference is insignificant statistically. The expressions of Hsp60 and TNF-α at the mRNA level was monitored using reverse transcriptase polymerase chain reaction. Hsp60 expression from THP-1 monocytes only showed some minor fluctuations in different antimycin A concentrations, regardless of uridine and iii pyruvate supplement, indicating the stress mitochondrial response was unobvious. On the other hand, TNF-α expression was dramatically down-regulated in THP-1 monocytes treated with antimycin A only compared to the untreated control and ones supplemented with uridine and pyruvate. These results suggest that antimycin A may have inhibition effect towards TNF-α expression, and uridine and pyruvate could also have other functions in THP-1 monocytes apart from redox rescue compounds. Yet the mitochondrial stress response shown by Hsp60 induction still remains to be further investigated.

text: Establishment of THP-1 Monocytes with Compromised Mitochondrial Functions The process of inflammation is important for both normal health and in a number of diseases, such as metabolic disorders, autoimmune diseases, and neurodegenerative diseases. Mitochondria are vital for the functioning of all cells. It had been implicated as a key player in inflammatory processes, especially through reactive oxygen species as signals of various immune responses. This study aimed to establish a THP-1 cell line with compromised mitochondrial functions, using antimycin A as a Complex III inhibitor, and to investigate the role of mitochondrial stress, as monitored by the expression of Hsp60, in inflammatory processes. High concentrations of antimycin A (100 and 200 μM) were cytotoxic to THP-1 monocytes that they were rapidly killed within 48 hours of exposure. Lower concentrations of antimycin A (5, 10, 25 and 50 μM) gave growth inhibition effects to THP-1 monocytes. Pyruvate and uridine were used with an intention of rescuing the THP-1 cell growth at lower antimycin A concentrations. The THP-1 monocytes treated with antimycin A with uridine and pyruvate showed more growth compared to the ones without uridine and pyruvate supplement. Yet this difference is insignificant statistically. The expressions of Hsp60 and TNF-α at the mRNA level was monitored using reverse transcriptase polymerase chain reaction. Hsp60 expression from THP-1 monocytes only showed some minor fluctuations in different antimycin A concentrations, regardless of uridine and iii pyruvate supplement, indicating the stress mitochondrial response was unobvious. On the other hand, TNF-α expression was dramatically down-regulated in THP-1 monocytes treated with antimycin A only compared to the untreated control and ones supplemented with uridine and pyruvate. These results suggest that antimycin A may have inhibition effect towards TNF-α expression, and uridine and pyruvate could also have other functions in THP-1 monocytes apart from redox rescue compounds. Yet the mitochondrial stress response shown by Hsp60 induction still remains to be further investigated.

year: 2009

title: Speaking the unspoken: Racism, sport and Māori

authors: Hippolite, Holly Raima

subjects: New Zealand

abstract: In this paper, we consider the silence that surrounds issues of racism in New Zealand sport. We argue that the intersection of two key ideologies – New Zealand’s purported history of good race relations, and the positive contribution that sport is believed to make to racial equality – contribute to a culture of silence in which it is difficult to talk about, let alone discuss constructively, Māori experiences of racism. Our aim is to put the issue on the agenda through engagement with ten experienced Māori sport participants, coaches and administrators whose experiences demonstrate the existence of, and pain caused by, cultural and institutional racism in New Zealand sport. In this aim, we do not seek to hide behind a veil of neutrality or objectivity. Rather, following a kaupapa Māori research approach, our interest is in bringing to light the voices, frustrations and concerns of Māori sportspeople in order to contribute to a much-needed conversation.

text: Speaking the unspoken: Racism, sport and Māori In this paper, we consider the silence that surrounds issues of racism in New Zealand sport. We argue that the intersection of two key ideologies – New Zealand’s purported history of good race relations, and the positive contribution that sport is believed to make to racial equality – contribute to a culture of silence in which it is difficult to talk about, let alone discuss constructively, Māori experiences of racism. Our aim is to put the issue on the agenda through engagement with ten experienced Māori sport participants, coaches and administrators whose experiences demonstrate the existence of, and pain caused by, cultural and institutional racism in New Zealand sport. In this aim, we do not seek to hide behind a veil of neutrality or objectivity. Rather, following a kaupapa Māori research approach, our interest is in bringing to light the voices, frustrations and concerns of Māori sportspeople in order to contribute to a much-needed conversation.

year: 2010