Reproduction in five sympatric batoid species (family urolophidae) from south-eastern Australia

This PhD determines the reproductive biology of five stingaree species caught as bycatch from south-eastern Australian commercial fisheries for fisheries stock assessments, ecological risk assessments, and species extinction risk evaluations.

O where are you going? O do you imagine? Reproduction and response : a reflexive sociology of scholarship of teaching and learning in practical legal training

My doctoral research studies Australian PLT practitioners’ engagement with scholarship of teaching and learning. I argue that many PLT practitioners are motivated to engage with scholarship of teaching and learning in their work. There are, however, individual and extra-individual impediments.
PLT practitioners are lawyers that teach in institutional practical legal training (“PLT”). Satisfactory completion of mandatory PLT is an eligibility requirement for admission to the Australian legal profession. The PLT requirement is additional to academic legal qualifications. PLT is undertaken at a post-graduate level with, or after, the academic law degree.
My study investigates PLT practitioners’ motivations and capabilities to engage with scholarship of teaching and learning (“SoTL”). I study organisational symbolic support for SoTL in PLT, and organisational allocation of resources to SoTL in PLT.
The study involves individual and extra-individual domains of PLT practitioners’ work. It considers how social structures (e.g. “the juridical”) are inscribed into individuals’ practices (“teaching”) and, conversely, whether practices influence social structures.
My research adopts qualitative methodologies. These involve inter-disciplinary exchanges between law, legal education, practice research, sociology of law, cultural theory, and theory and practice of teaching and learning. My theoretical framework draws on Pierre Bourdieu’s “reflexive sociology”, and Michel de Certeau’s “heterological science”.
I sourced data from documents, and semi-structured interviews with 36 Australian PLT practitioners. Documentary sources include statutory instruments, speeches, reports, practice directions, histories, and scholarly publications.
To analyse the data I adopted Kelle’s characterisation of “theoretical sensitivity”, drawing on “explicit” and “emergent” analysis strategies derived from “grounded theory”. The explicit strategies were based on my theoretical framework. The emergent strategy involved sensitivity to non-explicit concepts and theories that emerged from the data. Computer-aided qualitative data analysis software expedited these methods.
My findings to date question dominant legal structures’ readiness for change, the implications of this for teaching and learning in PLT, and in particular for PLT practitioners’ engagement with SoTL in PLT.
The espoused rationale for mandatory PLT (in statutes) is improvement for the protection of clients, the administration of justice, and to assure quality legal services. The tacit rationale is improved quality of legal education, and experiences, for lawyers-to-be. My thesis argues dominant structures in legal education impede the espoused and tacit objectives, and impede PLT practitioners’ engagement with scholarship of teaching and learning.

The effect of repeated boar exposure on cortisol secretion and reproduction in gilts

It has been proposed that short-term activation of the hypothalamo-pituitary adrenal axis, with a consequent increase in the secretion of cortisol, amy disrupt the endocrine events prior to ovulation and thereby impair reproduction in females. We investigated this concept in gilts in which oestrus was detected by introduction to boars, where intense physical contact is possible, or by applying pressure to the back of gilts (back-pressure test) during fence-line exposure to boars, where intense physical contact is prohibited. We expected that there would be a greater release of cortisol and that reproduction would be inhibited in gilts introduced to boars compared to gilts in which the back-pressure test was used. As expected, introduction of gilts to boars resulted in a significant transient increase in plasma concentrations of cortisol while there was no significant effect of using the back-pressure test on plasma cortisol. Nevertheless, introduction of gilts to boars did not impair reproduction and there was no effect of method of detecting oestrus on duration of oestrus, sexual receptivity, fertility or fecundity. The length of the oestrous cycle was decreased and ovulation rate increased in gilts that were introduced to boars compared to gilts that underwent the back-pressure test, indicating that introduction of gilts to boars may have stimulated these aspects of reproduction. These stimulatory effects may have been due to an increased exposure of gilts to sexual behaviour and stimuli from boars when introduced to boars and/or to stimulatory effects of the hypothalamo-pituitary adrenal axis on some aspects of reproduction.

Effects of stress on reproduction in non-rodent mammals : the role of glucocorticoids and sex differences

The means by which stress influences reproduction is not clearly understood, but may involve a number of endocrine, paracrine and neural systems. Stress impacts on the reproductive axis at the hypothalamus (to affect GnRH secretion) and the pituitary gland (to affect gonadotrophin secretion), with direct effects on the gonads being of less importance. Different stressors have different effects and there are differences in response to short- and long-term stress. Many short-term stresses fail to affect reproduction and there are reports of stimulatory effects of some 'stressors'. There are species differences in the way that specific stressors affect reproduction. Sex differences in the effects of a particular stressor have been delineated and these may relate to effects of stress at different levels of the hypothalamo-pituitary axis. The significance of stress-induced secretion of cortisol varies with species. In some instances, there appears to be little impact of short-term increases in cortisol concentrations and protracted increases in plasma concentration seem to be required before any deleterious effect on reproduction is apparent. Issues of sex, sex steroid status, type of stressor and duration of stress need to be considered to improve understanding of this issue.

Susceptibility of reproduction in female pigs to impairment by stress and the role of the hypothalamo-pituitary-adrenal axis

Although it is generally considered that stress can impair reproduction, we suggest that the impact of acute or repeated acute stress or acute or repeated acute elevations of cortisol are of little consequence in female pigs, even if these occur during the series of endocrine events that induce oestrus and ovulation. It is important to understand the impact of acute stress on reproduction because, in the intensive production of livestock, animals are often subjected to short-term challenges. There seems little doubt that reproduction in a proportion of female pigs is susceptible to impairment by severe and prolonged stress or the sustained elevation of cortisol but only when this continues for a substantial period. In female pigs, where reproduction is susceptible to impairment by severe prolonged stress, it is possible that the mediators of this suppression are cortisol, corticotrophin-releasing factor and vasopressin but, in pigs, there is evidence to suggest that adrenocorticotrophic hormone is not involved. Other substances secreted during stress may be involved but these are not considered in this review. It is possible that the mediators of stress act at any level of the hypothalamo-pituitary-ovarian axis. Although a variety of experimental manipulations have provided potential mediators and mechanisms for the stress-induced suppression of reproduction, these experimental manipulations rarely represented physiological circumstances so it is not clear if such mechanisms would be important in a physiological context. The precise mediators and mechanisms by which hormones released during stress may inhibit reproductive processes during severe prolonged stress are yet to be determined.

Stress and reproduction: central mechanisms and sex differences in non-rodent species

Despite extensive research, the mechanisms by which stress affects reproduction are unknown. Activation of stress systems could potentially influence reproduction at any level of the hypothalamo-pituitary gonadal axis. Nonetheless, the predominant impact is on the secretion of gonadotrophin releasing hormone (GnRH) from the brain and the secretion of the gonadotrophins, luteinizing hormone (LH) and follicle stimulating hormone (FSH), from the gonadotrophs of the anterior pituitary gland. When stress is prolonged, it is likely that secretion of the gonadotrophins will be suppressed but the effects of acute stress or repeated acute stress are not clear. Different stressors activate different pathways for varying durations, and the actions of stress vary with sex and are influenced by the predominance of particular sex steroids in the circulation. The mechanisms by which stress influences reproduction are likely to involve complex interactions between a number of central and peripheral pathways and may be different in males and females. To understand these mechanisms, it is important to determine the stress pathways that are activated by particular stressors and to establish how these pathways affect the secretion and actions of GnRH. Furthermore, there is a need to know how stress influences the feedback actions of gonadal steroids and inhibin.

Reproduction, egg morphology and development observed in Monographis queenslandicus (Diplopoda: Polyxenidae)

This study provides new insight into penicillate sexual behaviour and eggdevelopment as observed in Monographis queenslandicus Huynh et Veenstra, 2013 (Polyxenidae). The developing eggs were found to have two distinct stages, namely the chorion and pupoid, which both proved to be of 12–14 days duration. Both stages were characterized by distinctive external morphology. Morphological features observed pre ecdysis included the development of a smooth, tough membrane of the chorion. In contrast, the pupoid stage exhibited an embryonic cuticle with tiny spines, which were later being used to rupture the chorion. Additionally, an aperture bordered by protective sensilla located on the anterior of the pupoid is described for the first time.How to cite this article: Huynh C., Veenstra A.A. 2014. Reproduction, egg morphology and development observed in Monographis queenslandicus (Diplopoda: Polyxenidae)

The value of eutherian-marsupial comparisons for understanding the function of glucocorticoids in female mammal reproduction.

This article is part of a Special Issue "SBN 2014". Chronic stress is known to inhibit female reproductive function. Consequently, it is often assumed that glucocorticoid (GC) concentrations should be negatively correlated with reproductive success because of the role they play in stress physiology. In contrast, a growing body of evidence indicates that GCs play an active role in promoting reproductive function. It is precisely because GCs are so integral to the entire process that disruptions to adrenal activity have negative consequences for reproduction. The goal of this paper is to draw attention to the increasing evidence showing that increases in adrenal activity are important for healthy female reproduction. Furthermore, we outline several hypotheses about the functional role(s) that GCs may play in mediating reproduction and argue that comparative studies between eutherian and marsupial mammals, which exhibit some pronounced differences in reproductive physiology, may be particularly useful for testing different hypotheses about the functional role of GCs in reproduction. Much of our current thinking about GCs and reproduction comes from research involving stress-induced levels of GCs and has led to broad assumptions about the effects of GCs on reproduction. Unfortunately, this has left a gaping hole in our knowledge about basal GC levels and how they may influence reproductive function, thereby preventing a broader understanding of adrenal physiology and obscuring potential solutions for reproductive dysfunction.

The empty child: the reproduction of culture through schooling

This research provides a needed glimpse at the ‘underside’ (Giroux, 1981) of Australian pedagogy.By charting the lives of six teachers and six students from a range of Victorian schools, the research examines our assumptions about how identities are produced and reproduced through schooling. It provides a detailed analysis through a combination of photo elicitation and narrative inquiry methods. The study examines the resistance to sameness and why some students and teachers submit and accept the sameness, while others push back.Building initially from the work of Michael Apple and his positioning of ideology, curriculum and power relations, this study explores what are the values and assumptions that shape pedagogical practice and in what ways do these practices inculcate Victorian students into ideologically ridden‘common sense’ practices that are not articulated but understood through the consumption of cultural capital?This research seeks access to the powerful undercurrents that shape the identities of our teachers and our students as ‘foot soldiers in the long front of modernity’ (Willis, 2003, p. 390). The research is concerned with schooling and the process that happens to an individual within a school. It examines power and education and asks how do both students and teachers internalize and express the pedagogies of contemporary schooling and in what ways do the everyday aspects of teaching and learning reinforce the notion of schools as mechanisms of cultural capital distribution?