Isobel Ronai
University of Sydney
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Featured researches published by Isobel Ronai.
Insect Molecular Biology | 2016
Isobel Ronai; Benjamin P. Oldroyd; Vanina Vergoz
In social insect colonies the presence of a queen, secreting her pheromones, is a key environmental cue for regulating the reproductive state of workers. However, until recently the proximate molecular mechanisms underlying facultative worker sterility were unidentified. Studies into worker oogenesis in the honey bee (Apis mellifera) have indicated that programmed cell death is central to the regulation of oogenesis. Here we investigate how queen pheromone, age of the worker and ovary state affect both programmed cell death and cell number in worker ovaries. We describe a novel method to simultaneously measure programmed cell death (caspase activity) and live cell number (estimated from the amount of adenosine triphosphate) in an insect tissue. Workers exposed to queen pheromone have higher levels of caspase activity in the ovary than those not exposed. Our results suggest that queen pheromone triggers programmed cell death at the mid‐oogenesis checkpoint causing the abortion of worker oocytes and reproductive inhibition of the worker caste. Nonetheless, high caspase activity is present in activated ovaries from workers not exposed to queen pheromone. This caspase activity is most likely to be from the nurse cells undergoing programmed cell death, in late oogenesis, for normal oocyte development. Our study shows that the social environment of an organism can influence programmed cell death within a tissue.
Proceedings of the Royal Society B: Biological Sciences | 2017
Isobel Ronai; Michael H. Allsopp; Ken Tan; Shihao Dong; Xiwen Liu; Vanina Vergoz; Benjamin P. Oldroyd
In the social insects, ovary state (the presence or absence of mature oocytes) and ovary size (the number of ovarioles) are often used as proxies for the reproductive capacity of an individual worker. Ovary size is assumed to be fixed post-eclosion whereas ovary state is demonstrably plastic post-eclosion. Here, we show that in fact ovary size declines as honeybee workers age. This finding is robust across two honeybee species: Apis mellifera and A. cerana. The ovariole loss is likely to be due to the regression of particular ovarioles via programmed cell death. We also provide further support for the observation that honeybee workers with activated ovaries (mature oocytes present) most commonly have five ovarioles rather than a greater or smaller number. This result suggests that workers with more than five ovarioles are unable to physiologically support more than five activated ovarioles and that workers with fewer than five ovarioles are below a threshold necessary for ovary activation. As a workers ovariole number declines with age, studies on worker ovariole number need to take this plasticity into account.
Journal of Insect Physiology | 2015
Isobel Ronai; Deborah A. Barton; Benjamin P. Oldroyd; Vanina Vergoz
Molecular Biology and Evolution | 2016
Isobel Ronai; Benjamin P. Oldroyd; Deborah A. Barton; Guénaël Cabanes; Julianne Lim; Vanina Vergoz
Advances in The Study of Behavior | 2016
Isobel Ronai; Vanina Vergoz; Benjamin P. Oldroyd
Apidologie | 2017
Miles P. Cole-Clark; Deborah A. Barton; Michael H. Allsopp; Madeleine Beekman; Rosalyn S. Gloag; Theresa C. Wossler; Isobel Ronai; Nicholas C. Smith; Rebecca J. Reid; Benjamin P. Oldroyd
Archive | 2017
Isobel Ronai
Archive | 2017
Isobel Ronai
Archive | 2017
Isobel Ronai; Michael H. Allsopp; Ken Tan; Shihao Dong; Xiwen Liu; Vanina Vergoz; Benjamin P. Oldroyd
Insect Molecular Biology | 2016
Isobel Ronai; Benjamin P. Oldroyd; Vanina Vergoz