Dr Zamira Gibb
ARC Decra Fellow
School of Environmental and Life Sciences
- Phone:(02) 4921 5637
A many trick pony
Dr Zamira Gibb is a postdoctoral researcher in the field of equine fertility enhancement who works closely with industry to improve reproductive outcomes.
A request by a horse breeder has resulted in Dr Zamira Gibb and a team of researchers at the University of Newcastle working at the cutting edge of applied reproductive technology for livestock and, more recently, aquaculture.
Producing around half of all horses born in Australia and employing hundreds of thousands of people, the Hunter Valley's equine breeding industry is a valuable, sustainable, and culturally significant contributor to the Australian economy.
A combination of external factors such as pollutants, stress and land degradation, plus thousands of years of artificial selection in human sanctioned breeding processes, has seen the fertility of horses decrease over time.
Zamira works with the Thoroughbred racehorse industry - using natural methods only - and the Standardbred racehorse industry - using artificial reproductive technology - to improve fertility and improve reproductive outcomes, with a focus on stallions.
Working closely with several prominent industry groups including Harness Racing Australia, the Hunter Valley Equine Research Centre and equine reproductive specialists in both Australia and New Zealand, Zamira is a talented speaker renowned for her ability to present appropriately pitched information to both industry and scientific audiences alike.
Her understanding of the science down to the molecular level, plus depth of knowledge of both the veterinary and breeding industries, uniquely positions Zamira as a powerful conduit for the expedition of improvements in industry practice, as well as a scout for the identification of areas of industry need.
Zamira wasn't born into horses. As a pre-teen living in suburban Sydney, her love of horses was ignited when her parents sent her to a school holiday riding camp. When her interest failed to wane, they brokered a deal with a nearby riding school to exchange her labour for a weekly riding lesson.
"I spent every weekend there, cleaning stables and brushing horses, which was fine because I was happy just to pick up horse manure, and my parents were happy for me to be out of the house," she laughs.
"When I was 11 going on 12, my parents promised that if I worked at the riding school every weekend for twelve months, they would buy me a pony, thinking I would never follow through."
"But I did it for a year and they bought me a pony!"
"Mum always laments, 'Why didn't I buy you a tennis racket?'"
With her interest in horses continuing to grow, a degree in Animal and Veterinary Bioscience from the University of Sydney was the only choice for tertiary study.
Horses weren't available for Zamira's Honours project so she stepped out of her chosen species comfort zone and worked with alpacas. During her PhD studies, Zamira set to creating a commercially viable technology for cryopreserving and sex sorting of horse sperm. This project had mixed results, with its success being limited by accessibility and cost issues.
After presenting her PhD work at the Annual Scientific Meeting of the Society for Reproductive Biology, Zamira was approached by Laureate Professor John Aitken, the Director of the University of Newcastle's Priority Research Centre for Reproductive Science, who asked her to head up a new team in horse fertility.
Laureate Professor Aitken was the researcher originally approached by the Hunter Valley horse breeder who wondered if the expertise garnered from John's research involving human fertility could translate to horses.
Zamira jumped at the chance to become what she describes as "the person on the ground who deals with the horse farms. It's my job to work out what we need to achieve and what is important for industry."
"One of the beautiful things about working here is that my supervisor is John Aitken, unarguably one of the world's leaders in human sperm research," Zamira confirms.
Although not translating directly due to differences in metabolic processes between horse and human sperm, working alongside a world leader in human fertility is a great advantage for the horse fertility team, as is having access to the relevant research facilities at the University of Newcastle. The availability of the mass spectrometers and flow cytometers for Zamira and her team's work elevates them above many researchers and most practitioners in their field.
Zamira explains: "Most people undertaking horse research are at veterinary schools with limited access to this kind of equipment because they don't have the funding. If they do have access to it, it might be the apex of five years' worth of work, and cost tens of thousands of dollars for them to utilise."
"Molecular biology is not something they taught us in vet school. Having molecular capabilities make us really quite unique."
Students working with Zamira are undertaking several fascinating projects, focused on fertilisation or reproduction processes.
One group of students is working with the Invasive Animals Cooperative Research Centre, based at the University of Canberra, on a project developing a method of controlling feral horses. Ideally, a single dose sterilisation injection would render the majority of wild brumby herds infertile.
This strategy addresses damage to native plants, animals and ecosystems without necessitating cruel culling regimes which merely leave the newly corrected environments open to repopulation.
The team is also under-taking longitudinal data collection supporting what appears to be a correlation between inhalation of coal dust and damage to the germ line which may manifest as orthopedic disease in the offspring.
A REAL PEARLER
Recently decimated by disease, the oyster industry in Australia is looking for a new and hardy disease-resistant strain. The usefulness of explorative selective crosses is hampered by the amount of time needed for the new breeds to be tested for resilience. Waiting usually means the corresponding gametes have become non-viable.
A student in the team is looking at the storage of oyster eggs, so original eggs are still viable after testing of the selective crosses. This would create the ability to re-cross, strip and send the eggs of the robust cross to oyster farms around the country, remaining viable for weeks at a time, and allowing for repopulation.
RIDING OFF INTO THE SUNSET
Looking to the future, the team is working towards several research goals as well as continuing to advise breeders and government departments on the practical applications of their work in the lab.
The promulgation of strategies that naturally enhance fertility, including nutritional supplementation and management controls, will continue through the team's work with the Throroughbred breeding industry. Immunocontraceptive research will one day ensure the natural mating cycles of feral brumbies are permanently interrupted.
In the Standardbred industry, increasing the efficiency of embryo surrogacy processes is one goal. Another project being undertaken by the team is related to transporting sperm for artificial insemination and has the potential to overhaul assisted reproductive technology practice.
With Zamira at the reins, working as a valuable two-way interface between science and industry, plus shepherding a talented herd of researchers, this team have the winning post well in their sights.
- Doctor of Philosophy, University of Sydney
- Certificate IV in Horse Industry Applications, TAFE (NSW)
- Bachelor of Animal and Veterinary Bioscience (Hon), University of Sydney
- Animal Science
- Assisted Reproductive Technologies
- Cell Metabolism
- English (Mother)
- French (Working)
Fields of Research
For publications that are currently unpublished or in-press, details are shown in italics.
Chapter (1 outputs)
Gibb Z, Aitken RJ, 'Physiological and pathological aspects of sperm metabolism', The Sperm Cell: Production, Maturation, Fertilization, Regeneration, Cambridge University Press, Cambridge, UK 109-125 (2017) [B1]
Journal article (34 outputs)
Swegen A, Smith ND, Gibb Z, Curry BJ, Aitken RJ, 'The serine protease testisin is present on the surface of capacitated stallion spermatozoa and interacts with key zona pellucida binding proteins', Andrology, 7 199-212 (2019) [C1]
Griffin RA, Baker M, Aitken RJ, Swegen A, Gibb Z, 'What makes a fertile sperm? Unique molecular attributes of stallion fertility.', Reproduction, 158 R125-R137 (2019) [C1]
Carnevale EM, Metcalf LS, Stout TAE, Meyers S, Gibb Z, 'Foreword', Reproduction, Fertility and Development, 31 III (2019)
Ortega Ferrusola C, Martin Muñoz P, Ortiz-Rodriguez JM, Anel-López L, Balao da Silva C, Álvarez M, et al., 'Depletion of thiols leads to redox deregulation, production of 4-hydroxinonenal and sperm senescence: a possible role for GSH regulation in spermatozoa.', Biology of Reproduction, 100 1090-1107 (2019) [C1]
Swegen A, Grupen CG, Gibb Z, Baker M, de Ruijter-Villani M, Smith ND, et al., 'From Peptide Masses to Pregnancy Maintenance: A Comprehensive Proteomic Analysis of The Early Equine Embryo Secretome, Blastocoel Fluid and Capsule.', Proteomics, 17 1-13 (2017) [C1]
Hall SE, Aitken RJ, Nixon B, Smith ND, Gibb Z, 'Electrophilic aldehyde products of lipid peroxidation selectively adduct to heat shock protein 90 and arylsulfatase A in stallion spermatozoa', BIOLOGY OF REPRODUCTION, 96 107-121 (2017) [C1]
Gibb Z, Aitken RJ, 'The Impact of Sperm Metabolism during In Vitro Storage: The Stallion as a Model.', BioMed research international, 2016 9380609 (2016) [C1]
Aitken RJ, Gibb Z, Baker MA, Drevet J, Gharagozloo P, 'Causes and consequences of oxidative stress in spermatozoa', REPRODUCTION FERTILITY AND DEVELOPMENT, 28 1-10 (2016) [C1]
Gibb Z, Lambourne SR, Curry BJ, Hall SE, Aitken RJ, 'Aldehyde Dehydrogenase Plays a Pivotal Role in the Maintenance of Stallion Sperm Motility', BIOLOGY OF REPRODUCTION, 94 (2016) [C1]
Swegen A, Lambourne SR, Aitken RJ, Gibb Z, 'Rosiglitazone Improves Stallion Sperm Motility, ATP Content, and Mitochondrial Function', BIOLOGY OF REPRODUCTION, 95 (2016) [C1]
Gibb Z, Aitken RJ, 'Recent Developments in Stallion Semen Preservation', JOURNAL OF EQUINE VETERINARY SCIENCE, 43 S29-S36 (2016) [C1]
Varner DD, Gibb Z, Aitken RJ, 'Stallion fertility: A focus on the spermatozoon', Equine Veterinary Journal, 47 16-24 (2015) [C1]
© 2014 EVJ Ltd. Stallion fertility is a vast subject, with a wide array of permutations that can impact reproductive performance in either positive or negative ways. This review i... [more]
© 2014 EVJ Ltd. Stallion fertility is a vast subject, with a wide array of permutations that can impact reproductive performance in either positive or negative ways. This review is intended to address a mere segment of the male fertility issue, but the very essence of the male contribution to fertilisation, that of the spermatozoon. Spermatozoal ultrastructure and form-to-function are detailed and spermatozoal metabolism is discussed, with specific reference to distinctive characteristics of stallion spermatozoa. Lastly, methods for assessment of spermatozoal function are considered, with emphasis on spermatozoal motility, the acrosome reaction and spermatozoon-oocyte interactions. Closing comments address the need for development and standardisation of molecular-based assays for use with spermatozoa of stallions whose subfertility cannot be explained with conventional tests.
Swegen A, Curry BJ, Gibb Z, Lambourne SR, Smith ND, Aitken RJ, 'Investigation of the stallion sperm proteome by mass spectrometry', Reproduction, 149 235-244 (2015) [C1]
© 2015 Society for Reproduction and Fertility. Stallion spermatozoa continue to present scientific and clinical challenges with regard to the biological mechanisms responsible for... [more]
© 2015 Society for Reproduction and Fertility. Stallion spermatozoa continue to present scientific and clinical challenges with regard to the biological mechanisms responsible for their survival and function. In particular, deeper understanding of sperm energy metabolism, defence against oxidative damage and cell-cell interactions should improve fertility assessment and the application of advanced reproductive technologies in the equine species. In this study, we used highly sensitive LC-MS/MS technology and sequence database analysis to identify and characterise the proteome of Percoll-isolated ejaculated equine spermatozoa, with the aim offurthering our understanding of this cell's complex biological machinery. We were able to identify 9883 peptides comprising 1030 proteins, which were subsequently attributed to 975 gene products. Gene ontology analysis for molecular and cellular processes revealed new information about the metabolism, antioxidant defences and receptors of stallion spermatozoa. Mitochondrial proteins and those involved in catabolic processes constituted dominant categories. Several enzymes specific to ß-oxidation of fatty acids were identified, and further experiments were carried out to ascertain their functional significance. Inhibition of carnitine palmitoyl transferase 1, a rate-limiting enzyme of ß-oxidation, reduced motility parameters, indicating that b-oxidation contributes to maintenance of motility in stallion spermatozoa.
Gibb Z, Lambourne SR, Quadrelli J, Smith ND, Aitken RJ, 'L-carnitine and pyruvate are prosurvival factors during the storage of stallion spermatozoa at room temperature', Biology of Reproduction, 93 (2015) [C1]
© 2015 by the Society for the Study of Reproduction, Inc. The spermatozoa of many stallions do not tolerate being cooled, restricting the commercial viability of these animals and... [more]
© 2015 by the Society for the Study of Reproduction, Inc. The spermatozoa of many stallions do not tolerate being cooled, restricting the commercial viability of these animals and necessitating the development of a chemically defined room temperature (RT) storage medium. This study examined the impact of two major modulators of oxidative phosphorylation, pyruvate (Pyr) and L-carnitine (L-C), on the storage of stallion spermatozoa at RT. Optimal concentrations of Pyr (10 mM) and L-C (50 mM) were first identified and these concentrations were then used to investigate the effects of these compounds on sperm functionality and oxidative stress at RT. Mitochondrial and cytosolic reactive oxygen species, along with lipid peroxidation, were all significantly suppressed by the addition of L-C (48 h MitoSOX Red negative: 46.2% vs. 26.1%; 48 and 72 h dihydroethidium negative: 61.6% vs. 43.1% and 64.4% vs. 46.9%, respectively; 48 and 72 h 4-hydroxynonenal negative: 37.1% vs. 23.8% and 41.6% vs. 25.7%, respectively), while the Pyr + L-C combination resulted in significantly higher motility compared to the control at 72 h (total motility: 64.2% vs. 39.4%; progressive motility: 34.2% vs. 15.2%). In addition, supplementation with L-C significantly reduced oxidative DNA damage at 72 h (9.0% vs. 15.6%). To investigate the effects of LC as an osmolyte, comparisons were made between media that were osmotically balanced with NaCl, choline chloride, or L-C. This analysis demonstrated that spermatozoa stored in the L-C balanced medium had significantly higher total motility (55.0% vs. 39.0%), rapid motility (44.0% vs. 25.7%), and ATP levels (70.9 vs. 12.8 ng/ml) following storage compared with the NaCl treatment, while choline chloride did not significantly improve these parameters compared to the control. Finally, mass spectrometry was used to demonstrate that a combination of Pyr and L-C produced significantly higher acetyl-L-carnitine production than any other treatment (6.7 pg/106 spermatozoa vs. control at 4.0 pg/106 spermatozoa). These findings suggest that Pyr and L-C could form the basis of a novel, effective RT storage medium for equine spermatozoa.
Aitken JB, Naumovski N, Curry B, Grupen CG, Gibb Z, Aitken RJ, 'Characterization of an L-amino acid oxidase in equine spermatozoa.', Biol Reprod, 92 125 (2015) [C1]
Gibb Z, Lambourne SR, Aitken RJ, 'The paradoxical relationship between stallion fertility and oxidative stress.', Biology of Reproduction, 91 1-10 (2014) [C1]
Aitken RJ, Lambourne S, Gibb Z, 'The John Hughes Memorial Lecture: Aspects of Sperm Physiology-Oxidative Stress and the Functionality of Stallion Spermatozoa', JOURNAL OF EQUINE VETERINARY SCIENCE, 34 17-27 (2014) [C1]
Bromfield EG, Aitken RJ, Gibb Z, Lambourne SR, Nixon B, 'Capacitation in the presence of methyl-beta-cyclodextrin results in enhanced zona pellucida-binding ability of stallion spermatozoa', REPRODUCTION, 147 153-166 (2014) [C1]
Gibb Z, Butler TJ, Morris LHA, Maxwell WMC, Grupen CG, 'Quercetin improves the postthaw characteristics of cryopreserved sex-sorted and nonsorted stallion sperm', THERIOGENOLOGY, 79 1001-1009 (2013) [C1]
Gibb Z, Morris LHA, Maxwell WMC, Grupen CG, 'Dimethyl formamide improves the postthaw characteristics of sex-sorted and nonsorted stallion sperm', THERIOGENOLOGY, 79 1027-1033 (2013) [C1]
Druart X, Rickard JP, Mactier S, Kohnke PL, Kershaw-Young CM, Bathgate R, et al., 'Proteomic characterization and cross species comparison of mammalian seminal plasma', Journal of Proteomics, 91 13-22 (2013)
Seminal plasma contains a large protein component which has been implicated in the function, transit and survival of spermatozoa within the female reproductive tract. However, the... [more]
Seminal plasma contains a large protein component which has been implicated in the function, transit and survival of spermatozoa within the female reproductive tract. However, the identity of the majority of these proteins remains unknown and a direct comparison between the major domestic mammalian species has yet to be made. As such, the present study characterized and compared the seminal plasma proteomes of cattle, horse, sheep, pig, goat, camel and alpaca. GeLC-MS/MS and shotgun proteomic analysis by 2D-LC-MS/MS identified a total of 302 proteins in the seminal plasma of the chosen mammalian species. Nucleobindin 1 and RSVP14, a member of the BSP (binder of sperm protein) family, were identified in all species. Beta nerve growth factor (bNGF), previously identified as an ovulation inducing factor in alpacas and llamas, was identified in this study in alpaca and camel (induced ovulators), cattle, sheep and horse (spontaneous ovulators) seminal plasma. These findings indicate that while the mammalian species studied have common ancestry as ungulates, their seminal plasma is divergent in protein composition, which may explain variation in reproductive capacity and function. The identification of major specific proteins within seminal plasma facilitates future investigation of the role of each protein in mammalian reproduction. Biological significance: This proteomic study is the first study to compare the protein composition of seminal plasma from seven mammalian species including two camelid species. Beta nerve growth factor, previously described as the ovulation inducing factor in camelids is shown to be the major protein in alpaca and camel seminal plasma and also present in small amounts in bull, ram, and horse seminal plasma. © 2013.
Aitken RJ, Gibb Z, Mitchell LA, Lambourne SR, Connaughton HS, De Iuliis GN, 'Sperm motility is lost in vitro as a consequence of mitochondrial free radical production and the generation of electrophilic aldehydes but can be significantly rescued by the presence of nucleophilic thiols', Biology of Reproduction, 87 1-11 (2012) [C1]
Aitken RJ, De Iuliis GN, Gibb Z, Baker MA, 'The Simmet lecture: New horizons on an old landscape - oxidative stress, DNA damage and apoptosis in the male germ line', Reproduction in Domestic Animals, 47 7-14 (2012) [C2]
Gibb Z, Morris LHA, Maxwell WMC, Grupen CG, 'Use of a defined diluent increases the sex-sorting efficiency of stallion sperm', Theriogenology, 75 610-619 (2011) [C1]
The low efficiency of flow cytometric sex-sorting of stallion sperm has been attributed to the use of an opaque skim milk-based diluent during Hoechst 33342 (H33342) staining. Thr... [more]
The low efficiency of flow cytometric sex-sorting of stallion sperm has been attributed to the use of an opaque skim milk-based diluent during Hoechst 33342 (H33342) staining. Three experiments were conducted to formulate an optically clear stallion semen diluent for use during H33342 staining, and to determine whether a clear diluent improved resolution during sorting. For Experiment 1, sperm were incubated at 34 °C in each of five diluents containing either no protein, skim milk, 0.25% Cohn's Fraction V BSA, 0.5% BSA, or 1% BSA, following an 18 h storage (15 °C) period, or shortly after collection. Sperm incubated in both skim milk and 1% BSA-supplemented diluents had equivalent total (47 and 49.5%, respectively) and progressive (4.73 and 5.67%, respectively) sperm motilities after 45 min, and comparable acrosome integrity (65.9 and 67.9%, respectively). For Experiment 2, the protein source was optimised by comparing the characteristics of sperm stored and incubated in five diluents supplemented with skim milk, BSA, fatty acid and endotoxin free BSA (I-BSA), KnockOut¿ Serum Replacement, and ß-lactoglobulin, respectively. The I-BSA diluent was superior to skim milk for motility maintenance during incubation (74.0 vs 63.7%). The effect of diluent on sorting was investigated in Experiment 3 using a range of H33342 concentrations and incubation durations. The clear (1% BSA) diluent improved the split ratio compared with the opaque (skim milk) diluent (0.17 vs 0.08), with an optimum staining time of 45 min using 0.09 mM H33342. In conclusion, a diluent containing 1% fatty acid free, low endotoxin BSA in lieu of skim milk improved the sorting efficiency and motility characteristics of stallion sperm after storage for 18 h. © 2011.
|Show 31 more journal articles|
Conference (1 outputs)
Gibb Z, Lambourne SR, Aitken RJ, 'Do spermatozoa from fertile thoroughbred stallions live fast and die young?', Reproduction in Domestic Animals: Proceedings of the 17th International Congress on Animal Reproduction (ICAR), Vancouver, Canada (2012) [E3]
Number of supervisions
|Commenced||Level of Study||Research Title||Program||Supervisor Type|
|2019||PhD||Investigations of Early Pregnancy in the Mare using novel in vitro modeling techniques||PhD (Biological Sciences), Faculty of Science, The University of Newcastle||Principal Supervisor|
|2019||Masters||Developing a Novel Diagnostic Test for Early Pregnancy of the Mare and Find out the Embryo Endometrial Interaction||M Philosophy (Biological Sc), Faculty of Science, The University of Newcastle||Co-Supervisor|
|2018||PhD||A Novel Semen Extender to Accelerate Genetic Improvement Programs in Northern Australian Beef Cattle Breeding Programs||PhD (Biological Sciences), Faculty of Science, The University of Newcastle||Principal Supervisor|
|2017||PhD||The Role of Bacteria and Fungi in Defending Against Batrachochytrium Dendrobatidis Infection||PhD (Biological Sciences), Faculty of Science, The University of Newcastle||Principal Supervisor|
|2017||PhD||Enhancing Fertility for the Thoroughbred and Standardbred Industries||PhD (Biological Sciences), Faculty of Science, The University of Newcastle||Principal Supervisor|
|2017||PhD||Factors affecting oocyte quality and early embryo development in the mare||Veterinary Science, The University of Sydney||Co-Supervisor|
|2017||PhD||Equine Reproductive Research: Research into the Early Detection of Pregnancy in the Mare to Optimise Management of Insemination Schedules, Reduce Risk and Gain Further Insight into Early Pregnancy Loss and Infertility.||PhD (Biological Sciences), Faculty of Science, The University of Newcastle||Principal Supervisor|
|Year||Level of Study||Research Title||Program||Supervisor Type|
|2017||PhD||Investigation of Equine Fertility Mechanisms through Proteomic Analysis of Stallion Spermatozoa, Early Equine Embryos and Pregnant Mare Uterine Fluid||PhD (Biological Sciences), Faculty of Science, The University of Newcastle||Co-Supervisor|
|2017||PhD||Towards Non-Surgical Sterilisation of Feral Horses: Biomarkers of Folliculogenesis and Covalent Modification of Proteins Using Electrophilic Aldehydes||PhD (Biological Sciences), Faculty of Science, The University of Newcastle||Co-Supervisor|
February 27, 2019