title: Effects of cortisol on female-to-male sex change in a wrasse

authors: Goikoetxea, Alexander

abstract: Sex change occurs as a usual part of the life cycle for many teleost fish and the modifications involved (behavioural, gonadal, morphological) are well studied. However, the mechanism that transduces environmental cues into the molecular cascade that underlies this transformation remains unknown. Cortisol, the main stress hormone in fish, is hypothesised to be a key factor linking environmental stimuli with sex change by initiating gene expression changes that shift steroidogenesis from oestrogens to androgens but this notion remains to be rigorously tested. Therefore, this study aimed to experimentally test the role of cortisol as an initiator of sex change in a protogynous (female-to-male) hermaphrodite, the New Zealand spotty wrasse (Notolabrus celidotus). We also sought to identify potential key regulatory factors within the head kidney that may contribute to the initiation and progression of gonadal sex change. Cortisol pellets were implanted into female spotty wrasses under inhibitory conditions (presence of a male), and outside of the optimal season for natural sex change. Histological analysis of the gonads and sex hormone analyses found no evidence of sex change after 71 days of cortisol treatment. However, expression analyses of sex and stress-associated genes in gonad and head kidney suggested that cortisol administration did have a physiological effect. In the gonad, this included upregulation of amh, a potent masculinising factor, and nr3c1, a glucocorticoid receptor. In the head kidney, hsd11b2, which converts cortisol to inactive cortisone to maintain cortisol balance, was upregulated. Overall, our results suggest cortisol administration outside of the optimal sex change window is unable to initiate gonadal restructuring. However, our expression data imply key sex and stress genes are sensitive to cortisol. This includes genes expressed in both gonad and head kidney that have been previously implicated in early sex change in several sex-changing species.

text: Effects of cortisol on female-to-male sex change in a wrasse Sex change occurs as a usual part of the life cycle for many teleost fish and the modifications involved (behavioural, gonadal, morphological) are well studied. However, the mechanism that transduces environmental cues into the molecular cascade that underlies this transformation remains unknown. Cortisol, the main stress hormone in fish, is hypothesised to be a key factor linking environmental stimuli with sex change by initiating gene expression changes that shift steroidogenesis from oestrogens to androgens but this notion remains to be rigorously tested. Therefore, this study aimed to experimentally test the role of cortisol as an initiator of sex change in a protogynous (female-to-male) hermaphrodite, the New Zealand spotty wrasse (Notolabrus celidotus). We also sought to identify potential key regulatory factors within the head kidney that may contribute to the initiation and progression of gonadal sex change. Cortisol pellets were implanted into female spotty wrasses under inhibitory conditions (presence of a male), and outside of the optimal season for natural sex change. Histological analysis of the gonads and sex hormone analyses found no evidence of sex change after 71 days of cortisol treatment. However, expression analyses of sex and stress-associated genes in gonad and head kidney suggested that cortisol administration did have a physiological effect. In the gonad, this included upregulation of amh, a potent masculinising factor, and nr3c1, a glucocorticoid receptor. In the head kidney, hsd11b2, which converts cortisol to inactive cortisone to maintain cortisol balance, was upregulated. Overall, our results suggest cortisol administration outside of the optimal sex change window is unable to initiate gonadal restructuring. However, our expression data imply key sex and stress genes are sensitive to cortisol. This includes genes expressed in both gonad and head kidney that have been previously implicated in early sex change in several sex-changing species.

year: 2022

title: Behavioural Economics: The Inferior-Good Effect

authors: Messick, Eric Michael

subjects: behavioural economics

abstract: These experiments used 15 domestic hens to investigate the inferior-good effect, a decrease in consumption of a commodity as income increases.  Experiment 1 investigated plain and salted wheat to serve as superior goods (opposite to inferior goods) and inferior goods.  Hens consumed mostly plain wheat when given ad-libitum access so it was the intended superior good and salted wheat was the intended inferior good.  In the next experiments, 3 s of plain wheat and 10 s of salted wheat were available for single responses on 2 keys during discrete trials.  Income changed by changing the inter-trial interval (ITI) of fixed-length sessions or the total number of trials.  Experiment 2 partially replicated the Silberberg et al. (1987) procedure, using the ITI income analogue for 6 hens.  When income increased, 4 hens sometimes responded less on the salted-wheat key (demonstrating the inferior-good effect), 2 of these hens and a 5th hen sometimes responded more on both keys but proportionally more on the plain-wheat key (termed here as a relative inferior-good effect).  Experiment 3a partially replicated the Hastjarjo et al. (1990a) procedure using the total-trials analogue for 7 other hens.  The inferior-good effect occurred across some conditions for 2 hens while other hens tended to respond on the plain-wheat key, suggesting lack of contingency contact.  When a 60-s ITI was added in Experiment 3b, variability increased for most hens, but only 1 hen showed the effect, 1 of the hens that did so in Experiment 3b.  These 6 hens' (1 died) 80% bodyweights were re-assessed in Experiment 4 and hens were below 80% during Experiments 3a and 3b, suggesting that the lack of the inferior-good effect was not due to some hens being at high weights.  The ITI analogue was used for these 6 hens in Experiment 5 and the effect occurred for 2 hens.  Experiment 6 added forced-choice trials to the total-trials analogue (with 60-s ITI) to guarantee contingency contact.  The inferior- and/or relative-inferior-good effect occurred for 3 hens.  Across Experiments 2 through 6, body weights were usually heavier in high-income conditions and a within-session pattern of early-salted-late-plain responding occasionally occurred.   Crop capacities  of 5 Experiment-2 hens and a new hen (1 died) were assessed in Experiment 7 and there was no relation between this measure and inferior-or relative-inferior-good effects.  Experiments 8 and 9 examined effects of pre- and post-feed in low-income conditions using the ITI analogue.  When hens were pre-fed, responding for 5 of 7 hens resembled responding in high-income conditions of Experiment 2 with more plain-wheat responding and similar or less salted-wheat responding in some conditions (behaviour similar to the inferior- and relative-inferior-good effects, but without the income change).  A similar pattern was found for 4 of 5 hens when hens were post-fed in Experiment 9, suggesting that food in the digestive tract may have played a role, and perhaps not the income manipulations themselves, where it (or other component of body weight) may have abolished quantity (i.e., the intended-inferior-good) as a reinforcer.  Although these experiments occasionally demonstrated inferior- and relative-inferior-good effects, but less convincingly than published studies, the effects of income may have been non-specific.  The usefulness of the inferior-good concept and other income-related economic concepts are thus challenged.

text: Behavioural Economics: The Inferior-Good Effect These experiments used 15 domestic hens to investigate the inferior-good effect, a decrease in consumption of a commodity as income increases.  Experiment 1 investigated plain and salted wheat to serve as superior goods (opposite to inferior goods) and inferior goods.  Hens consumed mostly plain wheat when given ad-libitum access so it was the intended superior good and salted wheat was the intended inferior good.  In the next experiments, 3 s of plain wheat and 10 s of salted wheat were available for single responses on 2 keys during discrete trials.  Income changed by changing the inter-trial interval (ITI) of fixed-length sessions or the total number of trials.  Experiment 2 partially replicated the Silberberg et al. (1987) procedure, using the ITI income analogue for 6 hens.  When income increased, 4 hens sometimes responded less on the salted-wheat key (demonstrating the inferior-good effect), 2 of these hens and a 5th hen sometimes responded more on both keys but proportionally more on the plain-wheat key (termed here as a relative inferior-good effect).  Experiment 3a partially replicated the Hastjarjo et al. (1990a) procedure using the total-trials analogue for 7 other hens.  The inferior-good effect occurred across some conditions for 2 hens while other hens tended to respond on the plain-wheat key, suggesting lack of contingency contact.  When a 60-s ITI was added in Experiment 3b, variability increased for most hens, but only 1 hen showed the effect, 1 of the hens that did so in Experiment 3b.  These 6 hens' (1 died) 80% bodyweights were re-assessed in Experiment 4 and hens were below 80% during Experiments 3a and 3b, suggesting that the lack of the inferior-good effect was not due to some hens being at high weights.  The ITI analogue was used for these 6 hens in Experiment 5 and the effect occurred for 2 hens.  Experiment 6 added forced-choice trials to the total-trials analogue (with 60-s ITI) to guarantee contingency contact.  The inferior- and/or relative-inferior-good effect occurred for 3 hens.  Across Experiments 2 through 6, body weights were usually heavier in high-income conditions and a within-session pattern of early-salted-late-plain responding occasionally occurred.   Crop capacities  of 5 Experiment-2 hens and a new hen (1 died) were assessed in Experiment 7 and there was no relation between this measure and inferior-or relative-inferior-good effects.  Experiments 8 and 9 examined effects of pre- and post-feed in low-income conditions using the ITI analogue.  When hens were pre-fed, responding for 5 of 7 hens resembled responding in high-income conditions of Experiment 2 with more plain-wheat responding and similar or less salted-wheat responding in some conditions (behaviour similar to the inferior- and relative-inferior-good effects, but without the income change).  A similar pattern was found for 4 of 5 hens when hens were post-fed in Experiment 9, suggesting that food in the digestive tract may have played a role, and perhaps not the income manipulations themselves, where it (or other component of body weight) may have abolished quantity (i.e., the intended-inferior-good) as a reinforcer.  Although these experiments occasionally demonstrated inferior- and relative-inferior-good effects, but less convincingly than published studies, the effects of income may have been non-specific.  The usefulness of the inferior-good concept and other income-related economic concepts are thus challenged.

year: 2007

title: Te mana o te wahine: Young mothers healthcare experiences in pregnancy, birth, and into motherhood

authors: Kolo, Mia Elaine

subjects: Health

abstract: In Aotearoa-New Zealand being a young mother is often associated with clinical and societal ‘risks.’ Younger women have higher rates of maternal depression and suicide, complications during birth, and their babies are more likely to be born preterm, and of smaller gestational age and weight (Perinatal and Maternal Mortality Review Committee, 2012; Te Whatu Ora - Health New Zealand, 2023b, 2023a). Research also indicates that young mothers experience stigmatisation and discrimination that they attribute to their age and/or ethnicity (Adcock, 2016; Makowharemahihi et al., 2014; Rawiri, 2007; Ware, 2019).
In discussion with researchers, discrimination was the topic that young mothers at He Puaawai Teen Parent Centre wanted to talk about. They shared a strong desire to see change in the way that doctors, nurses, and midwives service young parents and were passionate about ensuring that future young mothers had more support. Thus, in responding to their call, 22 parents, including two fathers attending (or recent school-leavers of) He Puaawai Teen Parent Centre volunteered to participate in this study. This qualitative kaupapa Māori study employed a series of wānanga, individual kōrero, and an investigator-triangulation thematic analysis. The research questions explored both the positive and negative healthcare experiences of this cohort during pregnancy, birth, and into motherhood.
The aim of this study was to listen and learn about the experiences of these young parents and co-design informational and/or educational materials to help healthcare practitioners better understand and support young mothers/parents. To spread awareness of the experiences of these young parents, the co-design materials and findings of this study were disseminated via various healthcare seminars and meetings around the Waikato region. The findings of this study contribute to previous research that revealed over the last 20 years young parents have continued to report predominantly negative experiences in their maternity journey. Participants of this study reported experiences of unsolicited judgement and advice, a general lack of manaakitanga (care, empathy, respect), communication, and support from doctors, nurses, and midwives. The relatively small number of positive experiences shared in this study emphasises the importance of manaakitanga regardless of age. An unexpected finding was the impact that receptionists had on young parents’ healthcare experiences, as the face and entry point of healthcare services.

text: Te mana o te wahine: Young mothers healthcare experiences in pregnancy, birth, and into motherhood In Aotearoa-New Zealand being a young mother is often associated with clinical and societal ‘risks.’ Younger women have higher rates of maternal depression and suicide, complications during birth, and their babies are more likely to be born preterm, and of smaller gestational age and weight (Perinatal and Maternal Mortality Review Committee, 2012; Te Whatu Ora - Health New Zealand, 2023b, 2023a). Research also indicates that young mothers experience stigmatisation and discrimination that they attribute to their age and/or ethnicity (Adcock, 2016; Makowharemahihi et al., 2014; Rawiri, 2007; Ware, 2019).
In discussion with researchers, discrimination was the topic that young mothers at He Puaawai Teen Parent Centre wanted to talk about. They shared a strong desire to see change in the way that doctors, nurses, and midwives service young parents and were passionate about ensuring that future young mothers had more support. Thus, in responding to their call, 22 parents, including two fathers attending (or recent school-leavers of) He Puaawai Teen Parent Centre volunteered to participate in this study. This qualitative kaupapa Māori study employed a series of wānanga, individual kōrero, and an investigator-triangulation thematic analysis. The research questions explored both the positive and negative healthcare experiences of this cohort during pregnancy, birth, and into motherhood.
The aim of this study was to listen and learn about the experiences of these young parents and co-design informational and/or educational materials to help healthcare practitioners better understand and support young mothers/parents. To spread awareness of the experiences of these young parents, the co-design materials and findings of this study were disseminated via various healthcare seminars and meetings around the Waikato region. The findings of this study contribute to previous research that revealed over the last 20 years young parents have continued to report predominantly negative experiences in their maternity journey. Participants of this study reported experiences of unsolicited judgement and advice, a general lack of manaakitanga (care, empathy, respect), communication, and support from doctors, nurses, and midwives. The relatively small number of positive experiences shared in this study emphasises the importance of manaakitanga regardless of age. An unexpected finding was the impact that receptionists had on young parents’ healthcare experiences, as the face and entry point of healthcare services.

year: 2024