ORCID Profile
0000-0002-4284-2201
Current Organisation
University of Adelaide
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Publisher: Bioscientifica
Date: 11-2005
DOI: 10.1530/REP.1.00521
Abstract: Obesity is associated with a erse set of metabolic disorders, and has reproductive consequences that are complex and not well understood. The adipose tissue-produced leptin has dominated the literature with regards to female fertility complications, but it is pertinent to explore the likely role of other adipokines – adiponectin and resistin – as our understanding of their biological functions emerge. Leptin influences the developing embryo, the functioning of the ovary and the endometrium, interacts with the release and activity of gonadotrophins and the hormones that control their synthesis. In this review such biological actions and potential roles of the adipokines leptin, adiponectin and resistin are explored in relation to female fertility and the complexity of the obese metabolic state.
Publisher: Oxford University Press (OUP)
Date: 21-02-2012
Abstract: Obesity and related conditions, notably subfertility, are increasingly prevalent. Paternal influences are known to influence offspring health outcome, but the impact of paternal obesity and subfertility on the reproductive health of subsequent generations has been overlooked. A high-fat diet (HFD) was used to induce obesity but not diabetes in male C57Bl6 mice, which were subsequently mated to normal-weight females. First-generation offspring were raised on a control diet and their gametes were investigated for signs of subfertility. Second-generation offspring were generated from both first generation sexes and their gametes were similarly assessed. We demonstrate a HFD-induced paternal initiation of subfertility in both male and female offspring of two generations of mice. Furthermore, we have shown that diminished reproductive and gamete functions are transmitted through the first generation paternal line to both sexes of the second generation and via the first generation maternal line to second-generation males. Our previous findings that founder male obesity alters the epigenome of sperm, could provide a basis for the developmental programming of subfertility in subsequent generations. This is the first observation of paternal transmission of diminished reproductive health to future generations and could have significant implications for the transgenerational lification of subfertility observed worldwide in humans.
Publisher: Springer Science and Business Media LLC
Date: 03-02-2015
Publisher: Mary Ann Liebert Inc
Date: 09-2011
Abstract: For most of the derived human embryonic stem cell (ESC) lines thus far, the majority of human embryos used have been frozen in liquid nitrogen at or prior to the compacting stage for up to 10 years before human ESC derivation. As such they were grown in media that were relatively simple in their formulation compared with those used today. Here we report that culture of mouse embryos in media similar to these produces blastocysts in which both the inner cell mass cell number and the number of ESC progenitor cells (epiblast cells) in the inner cell mass are reduced compared with blastocysts cultured in a purpose-designed sequential (G1/G2) system commonly used today. Embryos cultured in a simple medium were less likely to attach and generate outgrowths. Further, these outgrowths had increased metabolic activity, which has been linked to differentiation, and altered gene expression. Culture of embryos in a simple medium to the compacting stage followed by culture in G2 to the blastocyst stage reduced some of these effects. However, none were improved to the level seen for culture in G1/G2. These results highlight the influence of embryo culture on embryo quality and pluripotency, which is a key factor in determining ESC isolation efficiencies.
Publisher: American Physiological Society
Date: 02-2008
DOI: 10.1152/AJPENDO.00409.2007
Abstract: Despite the well-known benefits of omega-3 ( n-3) polyunsaturated fatty acid (PUFA) supplementation on human health, relatively little is known about the effect of n-3 PUFA intake on fertility. More specifically, the aim of this study was to determine how oocyte and preimplantation embryo development might be influenced by n-3 PUFA supply and to understand the possible mechanisms underlying these effects. Adult female mice were fed a control diet or a diet relatively high in the long-chain n-3 PUFAs for 4 wk, and ovulated oocytes or zygotes were collected after gonadotropin stimulation. Oocytes were examined for mitochondrial parameters (active mitochondrial distribution, mitochondrial calcium and membrane potential) and oxidative stress, and embryo developmental ability was assessed at the blastocyst stage following 1) in vitro fertilization (IVF) or 2) culture of in vivo-derived zygotes. This study demonstrated that exposure of the oocyte during maturation in the ovary to an environment high in n-3 PUFA resulted in altered mitochondrial distribution and calcium levels and increased production of reactive oxygen species. Despite normal fertilization and development in vitro following IVF, the exposure of oocytes to an environment high in n-3 PUFA during in vivo fertilization adversely affected the morphological appearance of the embryo and decreased developmental ability to the blastocyst stage. This study suggests that high maternal dietary n-3 PUFA exposure periconception reduces normal embryo development in the mouse and is associated with perturbed mitochondrial metabolism, raising questions regarding supplementation with n-3 PUFAs during this period of time.
Publisher: CSIRO Publishing
Date: 2011
DOI: 10.1071/RD10326
Abstract: Male obesity is associated with reduced sperm function and increased incidence of sperm DNA damage however, the underlying molecular mechanisms have not yet been identified. Mammalian SIRT6 protein is involved in caloric-dependant DNA damage repair in other tissue types, yet a possible role for SIRT6 in male obesity and subfertility has not been investigated previously. To assess SIRT6 levels and activity in the testes, male mice (n = 12 per diet) were fed either a control diet (CD 6% fat) or a high-fat diet (HFD 21% fat) for 16 weeks before the collection of testes and spermatozoa. SIRT6 protein was localised to the nucleus of transitional spermatids and the acrosome of mature spermatozoa, with levels significantly decreased in HFD-fed male mice (P 0.05). This decrease in SIRT6 protein was associated with transitional spermatids having increased levels of acetylated H3K9 in the nucleus (P 0.01) and increased DNA damage (P 0.001). We propose a role for SIRT6 in spermiogenesis and potentially protamination processes, which are known to be compromised by male obesity.
Publisher: Elsevier BV
Date: 08-2010
DOI: 10.1016/J.RBMO.2010.05.001
Abstract: The preimplantation embryo is highly susceptible to in-vitro stress, and although this does not necessarily perturb blastocyst development, it can significantly affect embryo physiology and the ability to form a viable pregnancy. This study determined that the preimplantation mouse embryo is highly sensitive to a small decrease in intracellular pH (<0.2 pH units). Embryos cultured in media containing a weak acid (5,5-dimethyl-2,4-oxazolidinedione DMO) formed blastocysts with decreased cell number and inner cell mass number, as well as increased apoptosis, even though blastocyst development and morphology were unchanged. Interestingly, the effects were similar regardless of whether the pH stress was present for a short-term 'acute' exposure (during the zygote to 2-cell, or 2-cell to 8-cell ision) or an extended 'chronic' period of time (continually from the zygote to the blastocyst stage). Exposure to DMO during the first cleavage ision did not alter implantation however, fetal weight and crown-rump length were significantly decreased (P<0.05). In contrast, continuous exposure to DMO throughout preimplantation development reduced not only implantation but also fetal weight and crown-rump length. This study highlights the importance of correct intracellular pH and demonstrates that slight deviations can significantly impact embryo development and viability.
Publisher: CSIRO Publishing
Date: 2012
DOI: 10.1071/RD11256
Abstract: Maternal obesity results in reproductive complications, whereas the impact of paternal obesity is unclear. In the present study, the effects of parental obesity on preimplantation embryo cell cycle length and carbohydrate utilisation were investigated. Maternal and paternal obesity were assessed independently by deriving zygotes from normal or obese C57BL/6 female mice mated with normal Swiss male mice (maternal obesity), or from normal Swiss female mice mated with normal or obese C57BL/6 male mice (paternal obesity). Zygotes were cultured in vitro and development was then assessed by time-lapse microscopy and metabolism determined using ultramicrofluorescence. Maternal obesity was associated with a significant delay in precompaction cell cycle kinetics from the 1-cell stage. A significant increase in glucose consumption by embryos from obese compared with normal females occurred after compaction, although glycolysis remained unchanged. Similarly, paternal obesity led to significant delays in cell cycle progression during preimplantation embryo development. However, this developmental delay was observed from the second cleavage stage onwards, following embryonic genome activation. Blastocysts from obese males showed disproportionate changes in carbohydrate metabolism, with significantly increased glycolysis. Overall, metabolic changes were not inhibitory to blastocyst formation however, blastocyst cell numbers were significantly lower when either parent was obese. These data suggest that both maternal and paternal obesity significantly impacts preimplantation embryo physiology.
Publisher: Oxford University Press (OUP)
Date: 09-2011
Abstract: Supplementing diets with n-3 fatty acids from fish oil has been shown to improve reproductive performance in dairy cattle and sheep, but there is little published literature on its effects in sows. The aim of this study was to evaluate the reproductive performance of sows fed fish oil as a source of n-3 PUFA prefarrowing and during lactation. From d 107.7 ± 0.1 of pregnancy, 328 sows ranging in parity from 0 to 7 (parity 1.95 ± 0.09, mean ± SE) were fed either a diet containing tallow (control) or an isocaloric diet containing 3 g of fish oil/kg of diet (n-3). Diets were formulated to contain the same amount of DE (13.9 MJ/kg), crude fat (54 g/kg), and CP (174 g/kg). Sows were fed their treatment diet at 3 kg daily for 8 d before farrowing and continued on treatment diets ad libitum until weaning at 18.7 ± 0.1 d of lactation. After weaning, all sows were fed a gestation diet without fish oil until their subsequent farrowing. There was no effect (P > 0.310) of feeding n-3 diets prefarrowing on piglet birth weight, preweaning growth rate, piglet weaning weight, or sow feed intake. However, n-3 sows had a larger subsequent litter size (10.7 ± 0.3 vs. 9.7 ± 0.3 total born 10.2 ± 0.3 vs. 9.3 ± 0.3 born live P < 0.05). In conclusion, this is the first study to demonstrate that feeding sows a diet containing n-3 PUFA from fish oil fed before farrowing and during lactation increased litter size in the subsequent parity independent of energy intake.
Publisher: Oxford University Press (OUP)
Date: 05-2006
DOI: 10.1095/BIOLREPROD.105.048553
Abstract: Glucose concentration during cumulus-oocyte complex (COC) maturation influences several functions, including progression of oocyte meiosis, oocyte developmental competence, and cumulus mucification. Glucosamine (GlcN) is an alternative hexose substrate, specifically metabolized through the hexosamine biosynthesis pathway, which provides the intermediates for extracellular matrix formation during cumulus cell mucification. The aim of this study was to determine the influence of GlcN on meiotic progression and oocyte developmental competence following in vitro maturation (IVM). The presence of GlcN during bovine IVM did not affect the completion of nuclear maturation and early cleavage, but severely perturbed blastocyst development. This effect was subsequently shown to be dose-dependent and was also observed for porcine oocytes matured in vitro. Hexosamine biosynthesis upregulation using GlcN supplementation is well known to increase O-linked glycosylation of many intracellular signaling molecules, the best-characterized being the phosphoinositol-3-kinase (PI3K) signaling pathway. We observed extensive O-linked glycosylation in bovine cumulus cells, but not oocytes, following IVM in either the presence or the absence of GlcN. Inhibition of O-linked glycosylation significantly reversed the effect of GlcN-induced reduction in developmental competence, but inhibition of PI3K signaling had no effect. Our data are the first to link hexosamine biosynthesis, involved in cumulus cell mucification, to oocyte developmental competence during in vitro maturation.
Publisher: Elsevier BV
Date: 04-2011
DOI: 10.1016/J.FERTNSTERT.2010.11.044
Abstract: To determine the relationship between paternal body mass index (BMI), embryo development and pregnancy, and live birth outcomes after assisted reproductive technology (ART). Retrospective analysis of ART cycles. Major assisted reproduction center. Three hundred five couples undergoing ART in a private fertility clinic. No intervention was undertaken in patients involved in this study. Live birth outcomes and clinical pregnancy rates. No significant relationship between paternal BMI and early embryo development was found. However, increased paternal BMI was associated with decreased blastocyst development, clinical pregnancy rates and live birth outcomes. To our knowledge, this is the first report linking increased paternal BMI and clinical pregnancy and live birth rates after ART treatment. Further work to elucidate the mechanisms involved is required.
Publisher: CSIRO Publishing
Date: 2007
DOI: 10.1071/RD06129
Abstract: The development of pre-elongation (ruminants) and preimplantation (e.g. mouse and humans) embryos ex vivo has evolved over the past four decades into a reliable technology that is used as a research tool in developmental biology, as well as other embryo technologies, for application in infertility treatment, species conservation and selective breeding. It is clear from a variety of embryo culture studies that adaptive responses by embryos during culture can lead to significant alterations in subsequent developmental profiles, the mechanisms of which are not entirely clear but are unlikely to be limited to a single mechanism because this does not account for the variability seen in responses and the emerging list of specific cellular stressors that cause long-term deviations in fetal development. Epigenetic mechanisms, especially deviation of methylation patterns, and adaptation via causal pathways linking gene expression signalling with critical developmental time points, especially of placental development, are two candidates. Observational studies on post-transfer consequences must now be designed so that specific candidate pathways are followed to elucidate their role in perturbed development following transfer.
Publisher: Oxford University Press (OUP)
Date: 03-2011
DOI: 10.1095/BIOLREPROD.110.087262
Abstract: The preimplantation embryo is sensitive to its environment and, despite having some plasticity to adapt, environmental perturbations can impair embryo development, metabolic homeostasis, fetal and placental development, and offspring health. This study used an in vitro model of embryo culture with increasing mitochondrial inhibition to directly establish the effect of impaired mitochondrial function on embryonic, fetal, and placental development. Culture in the absence of the carbohydrate pyruvate significantly increased blastocyst glucose oxidation via glycolysis to maintain normal levels of ATP and tricarboxylic acid (TCA) cycle activity. This culture resulted in a significant reduction in blastocyst development, trophectoderm cell number, and respiration rate but, importantly, did not impair implantation rates or fetal and placental development. In contrast, increasing concentrations of the mitochondrial inhibitor amino-oxyacetate (AOA) impaired glycolysis, TCA cycle activity, respiration rate, and ATP production incrementally reduced blastocyst development and decreased blastocyst inner cell mass and trophectoderm cell numbers. Importantly, AOA did not affect implantation rates however, 5 μM AOA significantly reduced placental growth but not fetal growth, increasing the fetal:placental weight ratio. Furthermore, 50 μM AOA significantly reduced both placental and fetal growth but not the fetal:placental weight ratio. Hence, this study demonstrates that a threshold of mitochondrial function is required for normal development, and despite developmental plasticity of the embryo, impaired mitochondrial function in the embryo affects subsequent fetal and placental growth. These results highlight the importance of mitochondrial function in regulating pre- and postimplantation development however, the effect on offspring health remains unknown.
Publisher: Elsevier BV
Date: 09-2006
DOI: 10.1016/J.ANIREPROSCI.2005.09.009
Abstract: One hundred and ninety-two Large White/Landrace crossbred gilts were used in this study. The study was conducted in two blocks, with 16 gilts allocated to each of six treatments in each block. The treatments compared the effects on puberty attainment of commencing boar exposure at 161, 182 or 203 days of age, and the effect of first mating gilts at either the pubertal or second oestrus on ovulation rate and early embryo survival. Boar contact took place in a detection-mating area (DMA), and consisted of 20 min/day of full contact with a vasectomized boar greater than ten months of age. Gilts were artificially inseminated at the allocated oestrus, with the reproductive tracts collected at 22.8+/-0.4 days after first mating (mean+/-S.E.M.), and the numbers of corpora lutea and viable embryos recorded. The age at which gilts attained puberty increased with the age at which boar exposure commenced. Mean gilt ages at puberty were 179.5+/-1.6, 191.7+/-1.2 and 210.3+/-0.9 days, respectively, when boar contact commenced at 161, 182 and 203 days of age, P<0.01. Mean days-to-puberty was significantly shorter when boar contact began at 182 and 203 days of age compared to 161 days of age (10.4+/-1.2 and 8.3+/-0.9 days versus 18.9+/-1.5 days, respectively, P<0.01). Similarly, commencing boar exposure at 182 or 203 days of age as opposed to 161 days of age significantly increased the proportion of gilts attaining puberty within 10 days of start of boar exposure (0.67 and 0.70 versus 0.24, P<0.01). Mean days-to-puberty and the synchrony of puberty attainment were similar when boar contact commenced at 182 and 203 days of age. There was no significant effect of mating oestrus or age of gilts at mating on ovulation rate, embryo number or embryo survival. In conclusion, the current data indicate that the timing and synchrony of puberty attainment is significantly improved when first boar exposure of gilts is delayed until 182 days of age. Further, it is evident that within the age range investigated, delaying first mating until the second oestrus does not significantly increase either ovulation rate or embryo number at day 20 post-mating.
Publisher: CSIRO Publishing
Date: 2008
DOI: 10.1071/RD07161
Abstract: A limiting factor in every embryology laboratory is its capacity to grow ‘normal’ embryos. In human in vitro fertilisation (IVF), there is considerable awareness that the environment of the laboratory itself can alter the quality of the embryos produced and the industry as a whole has moved towards the implementation of auditable quality management systems. Furthermore, in some countries, such as Australia, an established quality management system is mandatory for clinical IVF practice, but such systems are less frequently found in other embryology laboratories. Although the same challenges of supporting consistent and repeatable embryo development are paramount to success in all embryology laboratories, it could be argued that they are more important in a research setting where often the measured outcomes are at an intracellular or molecular level. In the present review, we have outlined the role and importance of quality control and quality assurance systems in any embryo laboratory and have highlighted ex les of how simple monitoring can provide consistency and avoid the induction of artefacts, irrespective of the laboratory’s purpose, function or species involved.
Publisher: Wiley
Date: 11-07-2013
DOI: 10.1096/FJ.12-224048
Abstract: Obesity is highly prevalent, and its incidence is increasing. The previous study showing a major effect of paternal obesity on metabolic health of offspring is confounded by comorbidity with diabetes. Therefore, we investigated the effect of diet-induced paternal obesity, in the absence of diabetes, on the metabolic health of two resultant generations and the molecular profiles of the testes and sperm. Founder (F0) male C57BL6 mice were fed either a high-fat diet (HFD) or a control diet (CD) n = 10/diet for a period of 10 wk. Testis expression of mRNA/microRNAs was analyzed by microarray and qPCR and sperm microRNA abundance by qPCR. Two subsequent generations were generated by mating F0 and then F1 mice to CD mice, and their metabolic health was investigated. All mice, other than F0 males, were maintained on a CD. HFD feeding induced paternal obesity with a 21% increase in adiposity, but not overt diabetes, and initiated intergenerational transmission of obesity and insulin resistance in two generations of offspring. This distinct phenotypic constellation is either partially or fully transmitted to both female and male F1 offspring and further transmitted through both parental lineages to the F2 generation, with a heightened effect on female F1 offspring (+67% in adiposity) and their F2 sons (+24% in adiposity). Founder male obesity altered the testes expression of 414 mRNAs by microarray and 11 microRNAs by qPCR, concomitant with alterations in sperm microRNA content and a 25% reduction in global methylation of germ cell DNA. Diet-induced paternal obesity modulates sperm microRNA content and germ cell methylation status, which are potential signals that program offspring health and initiate the transmission of obesity and impaired metabolic health to future generations. This study implicates paternal obesity in the transgenerational lification of obesity and type 2 diabetes in humans.
Publisher: Elsevier BV
Date: 03-2011
DOI: 10.1016/J.FERTNSTERT.2010.09.038
Abstract: To use a rodent model of male diet-induced obesity (DIO) to examine resultant preimplantation embryo development and implantation rate, as well as fetal and placental growth. Experimental animal study. University research facilities. C57BL/6 male and CBAxC57BL/6 female mice. Male mice were fed a standard rodent chow (lean) or a high-fat diet (obese) for up to 13 weeks. After mating, zygotes were collected and cultured to the blastocyst stage, then assessed or transferred into recipient females. Embryo morphology and cell number were assessed and pregnancy outcomes determined at postmortem day 18. Embryos from obese males had reduced cleavage and decreased development to blastocyst stage during culture relative to control males. Blastocysts from obese males implanted at a reduced rate, and the proportion of fetuses that developed was significantly decreased, although fetal and placental weight did not differ between groups. This study demonstrates that paternal obesity impairs preimplantation embryo development and implantation but does not influence gross fetal or placental morphology. It highlights the important contribution that paternal health and lifestyle choices have for achieving a viable pregnancy.
Publisher: CSIRO Publishing
Date: 2017
DOI: 10.1071/AN15871
Abstract: The effect of moderate restriction of pre- and peri-pubertal liveweight gain on puberty attainment and potential litter size was investigated. At 69 days of age, 48 Large White/Landrace crossbred gilts (28.3 ± 0.3 kg), were fed to attain a liveweight of 70 kg (LIGHT) or 100 kg (HEAVY) at 161 days of age (n = 24 gilts/treatment). At 161 days of age, half the gilts in each group were fed to gain liveweight at 0.5 (LOW) or 1.0 (HIGH) kg/day until puberty (n = 12 gilts/treatment). From 175 days of age, gilts received 20 min/day of full, physical boar contact. Gilts were artificially inseminated at the pubertal oestrus, with reproductive tracts collected 22 ± 0.1 days later, and the number of corpora lutea and viable embryos recorded. LIGHT-LOW gilts were older (P 0.05) at puberty compared with LIGHT-HIGH, HEAVY-LOW and HEAVY-HIGH gilts 207.7 ± 3.50 versus 191.7 ± 3.65, 193.1 ± 3.50 and 192.5 ± 3.65, respectively. Treatment (HIGH vs LOW) increased (P 0.05) pubertal ovulation rate (15.2 ± 0.43 vs 13.1 ± 0.47), oestradiol at oestrus (13.4 ± 1.87 vs 9.1 ± 1.22 pg/mL) and progesterone 72 h post-oestrus (7.1 ± 0.48 vs 4.6 ± 0.50 ng/mL). Embryo number (10.8 ± 0.46) and survival (77.0 ± 3.21) were unaffected (P 0.05) by treatment. To conclude, puberty was delayed by chronic, but not acute, dietary restriction. Although short-term, moderate increases in feed intake increased pubertal ovulation rates, embryo numbers and survival were unaffected.
Publisher: Wiley
Date: 27-09-2011
DOI: 10.1111/J.1365-2605.2010.01092.X
Abstract: Although obvious effects of obesity on female reproduction and oocytes are emerging, the effects on male fertility and sperm quality are less clear with studies reporting conflicting results. We hypothesize that male obesity affects sperm function and physiology probably as a result of elevated oxidative stress in spermatozoa and therefore elevated levels of sperm DNA damage and loss of function. Six-week-old C57/Bl6 male mice (n = 36) were randomly allocated to two groups: group 1 (n = 18) received a control diet, whereas group 2 (n = 18) received a high-fat diet (HFD). At the completion of a 9-week period, mice were sacrificed and spermatozoa were obtained. Sperm motility, concentration, intracellular reactive oxygen species (ROS) production and sperm DNA damage were measured. The ability of the sperm to undergo capacitation, acrosome reaction, sperm binding and ability to fertilize an oocyte were also assessed. The percentage of motile spermatozoa was decreased in the HFD group compared with controls (36 ± 2% vs. 44 ± 4% p < 0.05). Intracellular ROS was elevated (692 ± 83 vs. 409 ± 22 units p < 0.01) in the HFD group compared with controls. Sperm DNA damage was also increased (1.64 ± 0.6% vs. 0.17 ± 0.06% p < 0.05) in the HFD group compared with the control group. Furthermore, the percentage of non-capacitated sperm was significantly lower compared with controls (12.34% vs. 21.06% p < 0.01). The number of sperm bound to each oocyte was significantly lower (41.14 ± 2.5 vs. 58.39 ± 2.4 p < 0.01) in the HFD group compared with that in controls and resulted in significantly lower fertilization rates (25.9% vs. 43.9% p < 0.01). This report provides evidence that obesity may induce oxidative stress and sperm DNA damage as well as decreased fertilizing ability. This is important as DNA damage in the sperm as a result of oxidative stress has been linked to poor reproductive outcomes.
Publisher: Elsevier BV
Date: 04-2011
DOI: 10.1016/J.THERIOGENOLOGY.2010.12.001
Abstract: The objective was to investigate the effects of moderate restriction of pre- and peri-pubertal liveweight gain on ovarian development and oocyte meiotic competence. At 70 d of age, and 27.7 ± 0.4 kg liveweight (LW), 64 Large White/Landrace crossbred gilts were allocated to two treatment groups (n = 32 gilts/treatment) one group was fed to attain a LW of 70 kg at 161 d of age (LIGHT), while the other group was fed to reach 100 kg LW (HEAVY). At 161 d of age, half of the gilts in each group (n = 16) were fed to gain LW at 0.5 kg/d (LOW), while the remaining half (n = 16) were fed to gain LW at 1.0 kg/d (HIGH) between 161 and 175 d of age, at which point they were killed and ovaries collected. For each gilt, surface antral follicles were counted and aspirated according to three size categories: 1-2.9 mm (small) 3-6 mm (medium) and > 6 mm (large). Follicles were pooled for each size class and treatment. Cumulus-oocyte-complexes (COC) recovered from small and medium follicles were matured in vitro (IVM) for 44 to 46 h, and meiotic maturation assessed. There was an effect of treatment (LIGHT versus HEAVY) on the number of medium sized follicles: 25.1 ± 2.59 versus 34.3 ± 2.60 (P < 0.05). The ovaries of LOW gilts had more small follicles and fewer medium follicles compared to those of HIGH gilts: 92.8 ± 8.35 versus 59.8 ± 5.24, and 25.1 ± 2.59 versus 32.5 ± 2.86 (P < 0.05). Target LW at 161 d did not affect meiotic progression of oocytes. However, LOW compared to HIGH LW gain between 161 and 175 d resulted in fewer oocytes reaching MII (0.40 versus 0.54 P < 0.05). In conclusion, moderately restricting feed intake impaired follicle growth beyond 3 mm and reduced oocyte meiotic competence. Further, although a carry-over effect of long-term feed restriction on follicle growth was evident, acute changes in feed intake during the 14 d prior to ovary collection had the greatest effect on oocyte nuclear maturation in vitro.
Publisher: Springer Science and Business Media LLC
Date: 21-01-2021
DOI: 10.1038/S41598-021-81226-3
Abstract: Paternal obesity is known to have a negative impact on the male’s reproductive health as well as the health of his offspring. Although epigenetic mechanisms have been implicated in the non-genetic transmission of acquired traits, the effect of paternal obesity on gene expression in the preimplantation embryo has not been fully studied. To this end, we investigated whether paternal obesity is associated with gene expression changes in eight-cell stage embryos fathered by males on a high-fat diet. We used single embryo RNA-seq to compare the gene expression profile of embryos generated by males on a high fat (HFD) versus control (CD) diet. This analysis revealed significant upregulation of the Samd4b and Gata6 gene in embryos in response to a paternal HFD. Furthermore, we could show a significant increase in expression of both Gata6 and Samd4b during differentiation of stromal vascular cells into mature adipocytes. These findings suggest that paternal obesity may induce changes in the male germ cells which are associated with the gene expression changes in the resulting preimplantation embryos.
Publisher: Mary Ann Liebert Inc
Date: 09-2012
Abstract: High-quality embryos give rise to embryonic stem cells (ESCs) at greater efficiencies than poor-quality embryos. However, most embryos available for human ESC derivation are of a reduced quality as a result of culture in relatively simple media up to 10 years earlier, before cryopreservation, or before compaction. In the present study, we used a mouse model to determine whether a culture with insulin from the 8-cell stage could increase the number of ESC progenitor epiblast cells in blastocysts, as well as endeavor to determine the molecular mechanism of the insulin's effect. Culture in media containing 1.7 ρM insulin increased epiblast cell number (determined by Oct4 and Nanog co-expression), and proportion in day 6 blastocysts. The inhibition of phosphoinositide 3 kinase (PI3K) (via LY294002), an early second messenger of the insulin receptor, blocked this effect. The inhibition of glycogen synthase kinase 3 (GSK3) or p53, 2 s messengers inactivated by insulin signaling (via CT99021 or pifithrin-α, respectively), increased epiblast cell numbers. When active, GSK3 and p53 block the transcription of Nanog, which is important for maintaining pluripotency. A simultaneous inhibition of GSK3 and p53 had no synergistic effects on epiblast cell number. The induced activation of GSK3 and p53, via the inhibition of proteins responsible for their inactivation (PKA via H-89 and SIRT-1 via nicotinamide, respectively), blocked the insulin's effect on the epiblast.From our findings, we conclude that insulin increases epiblast cell number via the activation of PI3K, which ultimately inactivates GSK3 and p53. Furthermore, we suggest that the inclusion of insulin in culture media could be used as a strategy for increasing the efficiency with which the ESC lines can be derived from cultured embryos.
Publisher: Oxford University Press (OUP)
Date: 02-2009
Publisher: CSIRO Publishing
Date: 2013
DOI: 10.1071/AN12119
Abstract: The response in reproductive performance when pigs are fed diets supplemented with fats high in polyunsaturated fatty acids (PUFA) has not been widely studied. Improved fertility has been reported in sows and other species fed diets with added fish oil, a rich source of omega-3 PUFA, but results are inconsistent. The aim of the present study was to determine the effect of the duration and the level of supplementation of omega-3 PUFA from fish oil on the reproductive performance of gilts. In Experiment 1, 570 Large White and Landrace purebred gilts were fed ad libitum either an unsupplemented diet containing tallow (Control) or a diet containing 3 g fish oil/kg (Omega-3) as a partial replacement for tallow from 24 weeks (Omega-3 for 6 weeks) or 27 weeks of age (Omega-3 for 3 weeks) before mating. Liveweight and backfat gain between 24 weeks of age and mating were recorded. Gilts were then fed an unsupplemented diet during gestation and farrowing rate and first litter size were recorded. In Experiment 2, 356 Large White × Landrace F1 cross gilts were fed ad libitum diets containing either 0, 3 or 10 g fish oil/kg of diet as a partial replacement of tallow from 24 weeks of age and continued after mating at 2.2 kg/day until slaughter at 25 days of gestation. Pregnancy rate, ovulation and embryo survival were recorded. Data were analysed by general linear model ANOVA and Chi-square methods. In Experiment 1, there was no increase in farrowing rate or litter size born in gilts fed the omega-3-supplemented diet for either 3 or 6 weeks before mating compared with Control gilts. In Experiment 2, supplementation with omega-3 PUFA from 24 weeks of age through to mating and continued during early gestation did not increase ovulation rate but there was a trend (P 0.10) for an increase in embryo survival measured at Day 25 of gestation in gilts fed diets containing fish oil. Embryo survival was higher in gilts fed diets containing 3 g fish oil/kg of diet than in those fed the Control diet (P 0.05). Increasing the supplementation level to 10 g fish oil/kg did not increase embryo survival further. In both experiments, supplementation of omega-3 as fish oil did not affect the onset of oestrous, gilt removal and weight and backfat gain. In conclusion, supplementation of omega-3 PUFA before mating did not improve farrowing rate or litter size in gilts. It may be necessary to continue feeding diets with low concentrations of fish oil during early gestation to maximise the reproductive response to elevated omega-3 PUFA.
Publisher: CSIRO Publishing
Date: 2011
DOI: 10.1071/RD10292
Abstract: Environmental stress results in perturbations to mitochondrial function in the preimplantation embryo and hinders subsequent embryo and possibly offspring development. Global gene expression in fetal mouse brain was investigated following targeted mitochondrial inhibition by amino-oxyacetate (AOA) from the 2-cell to the blastocyst stage. Blastocysts were transferred to pseudopregnant recipients and RNA extracted from Day 18 fetal brains for microarray interrogation. Exposure to 5 μM AOA during preimplantation embryo development induced differential expression of 166 genes ( .25 fold) in the fetal brain, relative to control medium-cultured embryos. Altered expression pathways included carbohydrate metabolism, neurological development, cellular proliferation and death, DNA replication, recombination and repair. Of 28 genes exhibiting the greatest change in expression, qPCR confirmed that 16 were significantly altered. Targeted qPCR assessment of a further 20 genes associated with methylation, acetylation and mitochondrial dysfunction revealed that three were significantly altered (Immp1l, Nars2, Sat2) and Dmap1 exhibited a sex-specific response to AOA exposure. Only 2/48 genes had significantly altered expression by qPCR (Nola3, Timm8b) in fetal brains exposed to 50 μM AOA embryo culture, excluding an AOA dose-dependent response. It was concluded that perturbation of mitochondrial function induced by 5 μM AOA during preimplantation embryo development alters gene expression in the neonatal brain in a manner that suggests that proper brain development may be compromised.
Publisher: Oxford University Press (OUP)
Date: 04-2009
Publisher: Wiley
Date: 03-03-2017
DOI: 10.1002/MRD.22784
Abstract: Gene expression and/or epigenetic deregulation may have consequences for sperm and blastocysts, as well as for the placenta, together potentially contributing to problems observed in offspring. We previously demonstrated specific perturbations of fertilization, blastocyst formation, implantation, as well as aberrant glucose metabolism and adiposity in offspring using a mouse model of paternal obesity. The current investigation analyzed gene expression and methylation of specific CpG residues in F1 placentas of pregnancies fathered by obese and normal-weight male mice, using real-time PCR and bisulfite pyrosequencing. Our aim was to determine if paternal obesity deregulated placental gene expression and DNA methylation when compared to normal-weight males. Gene methylation of sperm DNA was analyzed and compared to placentas to address epigenetic transmission. Of the 10 paternally expressed genes (Pegs), 11 genes important for development and transport of nutrients, and the long-terminal repeat Intracisternal A particle (IAP) elements, derived from a member of the class II endogenous retroviral gene family, we observed a significant effect of paternal diet-induced obesity on deregulated expression of Peg3, Peg9, Peg10, and the nutrient transporter gene Slc38a2, and aberrant DNA methylation of the Peg9 promoter in F1 placental tissue. Epigenetic changes in Peg9 were also found in sperm from obese fathers. We therefore propose that paternal obesity renders changes in gene expression and/or methylation throughout the placental genome, which could contribute to the reproductive problems related to fertility and to the metabolic, long-term health impact on offspring.
Publisher: Informa UK Limited
Date: 29-06-2022
DOI: 10.1080/17446651.2022.2094366
Abstract: Women with overweight and obesity, and their children, are at increased risk of adverse pregnancy, birth, and longer term health outcomes, believed to be compounded by excessive gestational weight gain (GWG). Research to date has focused on interventions to reduce excessive GWG through changes to maternal diet and/or lifestyle. Current clinical recommendations for GWG vary according to a woman's early pregnancy body mass index, based on assumptions that associations between GWG and adverse pregnancy outcomes are causal in nature, and modifiable. While there are small differences in GWG following pregnancy interventions, there is little evidence for clinically relevant effects on pregnancy, birth, and longer term childhood outcomes. This review considers interventional studies targeting women with overweight or obesity to reduce GWG in an effort to improve maternal and infant health, and the current evidence for interventions prior to conception. GWG is not modifiable via diet and lifestyle change, and continued efforts to find the 'right' intervention for women with overweight and obesity during pregnancy are unjustified. Researchers should focus on gathering evidence for interventions prior to pregnancy to optimize maternal health and weight to improve pregnancy, birth, and longer term health outcomes associated with obesity.
No related grants have been discovered for Megan Mitchell.