ORCID Profile
0000-0002-4623-932X
Current Organisation
Charles Darwin University
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Publisher: Herpetologists League
Date: 12-2013
Publisher: Elsevier BV
Date: 02-2019
DOI: 10.1016/J.TREE.2018.11.010
Abstract: A request for raw data from the corresponding authors of 771 animal biotelemetry-focused manuscripts, published between 1995 and 2015, highlighted a difference in data sharing practices across researcher career levels. Responses were positive in only 11% of requests made to corresponding authors (CAs) that were senior researchers, while 72% of responses were positive when CAs were early career researchers (ECRs), demonstrating that the majority of senior researchers perceived little benefit from the public data archiving of their published research, while they often remain the data custodian.
Publisher: Oxford University Press (OUP)
Date: 22-10-2018
DOI: 10.1093/BRAIN/AWY263
Abstract: Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels control neuronal excitability and their dysfunction has been linked to epileptogenesis but few in iduals with neurological disorders related to variants altering HCN channels have been reported so far. In 2014, we described five in iduals with epileptic encephalopathy due to de novo HCN1 variants. To delineate HCN1-related disorders and investigate genotype-phenotype correlations further, we assembled a cohort of 33 unpublished patients with novel pathogenic or likely pathogenic variants: 19 probands carrying 14 different de novo mutations and four families with dominantly inherited variants segregating with epilepsy in 14 in iduals, but not penetrant in six additional in iduals. Sporadic patients had epilepsy with median onset at age 7 months and in 36% the first seizure occurred during a febrile illness. Overall, considering familial and sporadic patients, the predominant phenotypes were mild, including genetic generalized epilepsies and genetic epilepsy with febrile seizures plus (GEFS+) spectrum. About 20% manifested neonatal/infantile onset otherwise unclassified epileptic encephalopathy. The study also included eight patients with variants of unknown significance: one adopted patient had two HCN1 variants, four probands had intellectual disability without seizures, and three in iduals had missense variants inherited from an asymptomatic parent. Of the 18 novel pathogenic missense variants identified, 12 were associated with severe phenotypes and clustered within or close to transmembrane domains, while variants segregating with milder phenotypes were located outside transmembrane domains, in the intracellular N- and C-terminal parts of the channel. Five recurrent variants were associated with similar phenotypes. Using whole-cell patch-cl , we showed that the impact of 12 selected variants ranged from complete loss-of-function to significant shifts in activation kinetics and/or voltage dependence. Functional analysis of three different substitutions altering Gly391 revealed that these variants had different consequences on channel biophysical properties. The Gly391Asp variant, associated with the most severe, neonatal phenotype, also had the most severe impact on channel function. Molecular dynamics simulation on channel structure showed that homotetramers were not conducting ions because the permeation path was blocked by cation(s) strongly complexed to the Asp residue, whereas heterotetramers showed an instantaneous current component possibly linked to deformation of the channel pore. In conclusion, our results considerably expand the clinical spectrum related to HCN1 variants to include common generalized epilepsy phenotypes and further illustrate how HCN1 has a pivotal function in brain development and control of neuronal excitability.
Publisher: Wiley
Date: 24-05-2012
Publisher: CSIRO Publishing
Date: 2008
DOI: 10.1071/WR07169
Abstract: The distribution and physiological condition of 116 Caiman crocodilus yacare was assessed over one year in the Southern Pantanal. Body mass and intermediary plasma metabolites were measured at three different time periods, representing large differences in the abundance of surface water. During the wet season the study site was completely submerged under water and C.c. yacare were distributed evenly throughout. High levels of [glucose] and [triglyceride] in the plasma indicated regular feeding. As the dry season progressed C.c. yacare became increasingly crowded around the remaining ponds. They showed a reduction in plasma [glucose] and [triglyceride], and an increase in plasma [β-hydroxy-butyrate], signifying that they were feeding less and utilising fat reserves. At this s ling period, ~40% of the male C. c. yacare that were years old inhabited dry grassland and did not have access to water. These animals were significantly lighter than males of a similar length that had immediate water access, and plasma [uric acid] indicated that they had not fed for a long time and were metabolising tissue proteins. Essentially, the adult male C.c. yacare that inhabited dry grassland were in a state of energy deficiency. This was so severe in some animals that recovery seemed unlikely. The study suggests that fluctuations in the abundance of surface ground water may influence the size and structure of the C. c. yacare population in the Pantanal.
Publisher: Elsevier BV
Date: 10-2009
DOI: 10.1016/J.CBPA.2009.06.014
Abstract: The localization, distribution and orientation of O(2) chemoreceptors associated with the control of cardio-respiratory responses were investigated in the neotropical, Hoplias lacerdae. Selective denervation of the cranial nerves (IX and X) was combined with chemical stimulation (NaCN) to characterize the gill O(2) chemoreceptors, and the fish were then exposed to gradual hypoxia to examine the extent of each cardio-respiratory response. Changes in heart rate (f(H)) and ventilation litude (V( )) were allied with chemoreceptors distributed on both internal and external surfaces of all gill arches, while ventilation rate (f) was allied to the O(2) chemoreceptors located only in the internal surface of the first gill arch. H. lacerdae exposed to gradual hypoxia produced a marked bradycardia (45%) and 50% increase in V( ), but only a relatively small change in f (32%). Thus, the low f(R) response yet high V( ) were in accord with the characterization of the O(2) chemoreceptors. Comparing these results from H. lacerdae with hypoxia-tolerant species revealed a relationship existent between general oxygenation of the in idual species environment, its cardio-respiratory response to hypoxia and the characterization of O(2) chemoreceptors.
Publisher: Wiley
Date: 05-08-2020
Publisher: Wiley
Date: 02-08-2023
DOI: 10.1111/AEC.13382
Abstract: Australian bio ersity is facing an extinction crisis yet, government spending on conservation is wholly inadequate. The involvement of local communities in fundraising, direct actions, and habitat restoration is becoming vital in the fate of threatened species. Here, we review the research outputs and impact generated from 22 years of conservation‐driven collaboration between researchers and a local community focused on saving the endangered Mary River turtle ( Elusor macrurus ) . The study found that this collaboration generated a significant body of research that advanced the ecological knowledge of the species and ensured the findings were being applied towards the conservation of the turtle, locally and nationally. While the national listing status of E. macrurus as endangered has not changed over the past 22 years, the knowledge gained about the turtle's biology and its use to better advise development and water resources in the catchment suggests that the species' future is brighter than when it was first discovered in 1994. This review demonstrates the potential of local communities in driving and supporting conservation initiatives and provides a blueprint for scientific endeavours that inform adaptive community conservation programmes for threatened species.
Publisher: Wiley
Date: 26-07-2013
DOI: 10.1111/FWB.12206
Publisher: Elsevier BV
Date: 08-2015
DOI: 10.1016/J.CBPA.2014.10.010
Abstract: Digesting snakes experience massive increases in metabolism that can last for many days and are accompanied by adjustments in the oxygen transport cascade. Accordingly, we examined the oxygen-binding properties of the blood in the South American rattlesnake (Crotalus durissus terrificus) during fasting and 24 and 48h after the snakes have ingested a rodent meal corresponding to 15% (±2%) of its own body mass. In general, oxygen-hemoglobin (Hb-O2) affinity was significantly increased 24h post-feeding, and then returned toward fasting values within 48h post-feeding. Content of organic phosphates ([NTP] and [NTP]/[Hb]), hemoglobin cooperativity (Hill's n), and Bohr Effect (ΔlogP50/ΔpH) were not affected by feeding. The postprandial increase in Hb-O2 affinity in the South American rattlesnake can be almost entirely ascribed by the moderate alkaline tide that follows meal ingestion. In general, digesting snakes were able to regulate blood metabolites at quite constant levels (e.g., plasma osmolality, lactate, glucose, and total protein levels). The level of circulating lipids, however, was considerably increased, which may be related to their mobilization, since lipids are known to be incorporated by the enterocytes after snakes have fed. In conclusion, our results indicate that the exceptional metabolic increment exhibited by C. d. terrificus during meal digestion is entirely supported by the aerobic pathways and that among the attending cardiorespiratory adjustments, pulmonary Hb-O2 loading is likely improved due to the increment in blood O2 affinity.
Publisher: CSIRO Publishing
Date: 09-04-2021
DOI: 10.1071/WR20032
Abstract: Abstract Context Understanding what constitutes high-quality habitat for threatened species is critical for conservation management planning. The endangered northern quoll (Dasyurus hallucatus) has experienced an uneven range contraction among habitat types. Once common across multiple habitats of northern mainland Australia, declining populations have now contracted to rocky escarpments. Aim The island refuge of Groote Eylandt, Northern Territory, Australia, has not experienced the declines as seen on mainland Australia. Here, northern quolls persist in both rocky escarpment and savanna woodland, which provides a rare opportunity to investigate the habitat quality of rocky escarpments and savanna woodland for the northern quoll. Methods Northern quolls (n = 111) were trapped in both rocky escarpment (n = 61) and savanna woodland (n = 50) habitats before the breeding season (May). We conducted body condition assessment, scat analysis, and measured trophic niche breadth of in iduals occupying each habitat type. Key results Female quolls occupying rocky escarpments exhibited a lower body condition than did quolls occupying savanna woodland. Quolls from rocky escarpments consumed a significantly higher proportion of mammals and fed within a narrower dietary niche than did those occupying savanna woodland. Conclusions Quolls had adapted to the dietary resources available within each habitat type, suggesting that the lack of quolls in savanna woodland on the mainland is due to factors other than availability of dietary resources. Implications Groote Eylandt is of critical conservation significance, where high numbers of northern quolls exist in both rocky escarpment and savanna woodland habitats. For population viability on the mainland, managing threats such as feral predators and inappropriate fire regimes in savanna woodland, particularly those surrounding rocky escarpment, should be prioritised.
Publisher: Springer Science and Business Media LLC
Date: 18-03-2017
Publisher: The Company of Biologists
Date: 12-2007
DOI: 10.1242/JEB.009266
Abstract: The jeju is a teleost fish with bimodal respiration that utilizes a modified swim bladder as an air-breathing organ (ABO). Like all air-breathing fish studied to date, jeju exhibit pronounced changes in heart rate(fH) during air-breathing events, and it is believed that these may facilitate oxygen uptake (MO2) from the ABO. The current study employed power spectral analysis (PSA) of fH patterns, coupled with instantaneous respirometry, to investigate the autonomic control of these phenomena and their functional significance for the efficacy of air breathing. The jeju obtained less than 5%of total MO2(MtO2) from air breathing in normoxia at 26°C, and PSA of beat-to-beat variability in fHrevealed a pattern similar to that of unimodal water-breathing fish. In deep aquatic hypoxia (water PO2=1 kPa) the jeju increased the frequency of air breathing (fAB) tenfold and maintained MtO2 unchanged from normoxia. This was associated with a significant increase in heart rate variability (HRV),each air breath (AB) being preceded by a brief bradycardia and then followed by a brief tachycardia. These fH changes are qualitatively similar to those associated with breathing in unimodal air-breathing vertebrates. Within 20 heartbeats after the AB, however, a beat-to-beat variability in fH typical of water-breathing fish was re-established. Pharmacological blockade revealed that both adrenergic and cholinergic tone increased simultaneously prior to each AB, and then decreased after it. However, modulation of inhibitory cholinergic tone was responsible for the major proportion of HRV, including the precise beat-to-beat modulation of fH around each AB. Pharmacological blockade of all variations in fH associated with air breathing in deep hypoxia did not, however, have a significant effect upon fAB or the regulation of MtO2. Thus, the functional significance of the profound HRV during air breathing remains a mystery.
Publisher: Brill
Date: 2008
DOI: 10.1163/156853808786230505
Abstract: Over the diurnal cycle most reptiles show large changes in internal body temperature and heart rate (fH). The raising of fH, as the surface of a heliothermic reptile warms, increases cardiac output and facilitates in optimising the preferred daily body temperature (PDBT). In mammals, the fine tuning of cardiac output by the autonomic system can be observed through distinct oscillatory patterns in fH. This study examined Caiman latirostris (n = 6) to determine if similar oscillations in fH were present, and to assess if they exhibited a diurnal component associated with daily shifts in body temperature. A surgically implanted miniature datalogger recorded every heart beat and the dorsal surface temperature (Tds) of animals free-ranging in a semi-natural habitat. All C. latirostris exhibited rapid warming of Tds between 0700 and 1200. This was correlated with a rapid increase in fH, accompanied by erratic beat-to-beat oscillations in instantaneous fH. As Tds cooled, fH decreased and the short-term oscillations were abolished, resulting in a much slower rate of change in instantaneous fH. The two distinct fH rhythms may serve to optimise the PDBT over the diurnal cycle.
Publisher: Wiley
Date: 21-03-2015
DOI: 10.1111/AEC.13309
Abstract: Large‐bodied frugivores are essential to the ecological function of rainforest communities. The southern cassowary ( Casaurius casuarius johnsonii ) is the only large frugivore in the tropical rainforests of Australia. Here, we assessed whether cassowaries remain important to native plant seed dispersal in areas where the rainforest is highly fragmented, and exotic fruits are abundant. To do this, we developed a tri‐axial acceleration logger integrated with a motion sensor and VHF radio transmitter. The telemetry device was small enough to be hidden inside a native fruit. The cassowaries ingested it, transported it and defecated it up to 24 h later with the seeds from the fruits they had ingested during the tracking period. The telemetry device was then located by VHF radio and collected with the scat. The distance travelled, activity profile, consumed fruit ersity, and scat energy content were assessed for cassowaries inhabiting regions with different degrees of urbanization. We found that cassowaries inhabiting more urbanized areas consumed the greatest proportion of fruits from exotic plants (~30%) but still incorporated a significant proportion of fruits from native plants in their diet. These in iduals existed in higher states of activity and rested less than in iduals inhabiting more intact swathes of rainforest, actively moving between urban gardens and the rainforest. The study shows cassowaries have a flexible foraging strategy that has enabled them to persist in rainforest‐fragmented landscapes. They remain a significant disperser of seeds from native plants between rainforest patches, and as such, cassowaries remain essential in maintaining native plant ersity within these fragmented patches.
Publisher: The Royal Society
Date: 04-2022
Abstract: Supporting the recovery of large carnivores is a popular yet challenging endeavour. Estuarine crocodiles in Australia are a large carnivore conservation success story, with the population having extensively recovered from past heavy exploitation. Here, we explored if dietary changes had accompanied this large population recovery by comparing the isotopes δ 13 C and δ 15 N in bones of crocodiles s led 40 to 55 years ago (small population) with bones from contemporary in iduals (large population). We found that δ 13 C and δ 15 N values were significantly lower in contemporary crocodiles than in the historical cohort, inferring a shift in prey preference away from marine and into terrestrial food webs. We propose that an increase in intraspecific competition within the recovering crocodile population, alongside an increased abundance of feral ungulates occupying the floodplains, may have resulted in the crocodile population shifting to feed predominantly upon terrestrial food sources. The number of feral pigs consumed to sustain and grow crocodile biomass may help suppress pig population growth and increase the flow of terrestrially derived nutrients into aquatic ecosystems. The study highlights the significance of prey availability in contributing to large carnivore population recovery.
Publisher: Elsevier BV
Date: 11-2020
Publisher: Wiley
Date: 19-07-2011
No related grants have been discovered for Mariana Campbell.