In Vitro Hepatic Assessment of Cineole and Its Derivatives in Common Brushtail Possums (Trichosurus vulpecula) and Rodents

Folivore marsupials, such as brushtail possum (Trichosurus Vulpecula) and koala (Phascolarctos cinereus), can metabolise higher levels of dietary terpenes, such as cineole, that are toxic to eutherian mammals. While the highly efficient drug metabolising enzymes, cytochrome P450 3A (CYP3A) and phase II conjugating enzymes (UDP-glucuronosyltransferase, UGT), are involved in the metabolism of high levels of dietary terpenes, evidence for inhibitory actions on these enzymes by these terpenes is scant. Thus, this study investigated the effect of cineole and its derivatives on catalytic activities of hepatic CYP3A and UGT in mice, rats, and possums. Results showed that cineole (up to 50 µM) and its derivatives (up to 25 µM) did not significantly inhibit CYP3A and UGT activities in mice, rats, and possums (both in silico and in vitro). Interestingly, basal hepatic CYP3A catalytic activity in the possums was ~20% lower than that in rats and mice. In contrast, possums had ~2-fold higher UGT catalytic activity when compared to mice and rats. Thus, these basal enzymatic differences may be further exploited in future pest management strategies.

Testing the behaviour of Australian brushtail possums (Trichosurus vulpecula) to candidate semiochemicals from conspecifics’ urine

<p>The Australian brushtail possum (Trichosurus vulpecula) is a prolific introduced mammalian pest. Current pest control methods involve traps and poisons, but are proving to be ineffective long term solutions. As semiochemical lures are thought to be more attractive than food-based lures at low densities, researchers are attempting to utilize semiochemicals for kill traps. The objectives of this thesis were to create a testing protocol for use in a research colony of possums and use that protocol to test the attractiveness of semiochemicals found in possum urine that had been positively associated with possum attraction and interest in urine.. I hypothesised that there would be an observer effect present in the colony due to the nature of the colony husbandry protocols. There was no statistically significant observer effect present in the colony for eating, interaction, sitting, grooming or enclosure use (front or back). However, there was a trend (across the colony) that sitting and grooming increased in the presence of an observer. From these results, I designed an active presentation protocol for testing semiochemicals. I predicted that the most attractive compounds would belong to the acids and alcohol chemical groups. Overall there was no statistically significant difference between the semiochemicals. However, when taken individually there was clear evidence that five of the semiochemicals (belonging to the ketone, alcohol and phenol chemical groups) were more attractive than their control and the standard lure. It has been shown in this thesis that the attractiveness of semiochemicals can be tested in a small research colony. However, limits on colony size greatly reduce statistical power. For future studies, I would recommend increasing the sample size or instead developing field-based bioassays capable of being repeated across a greater number of sites, populations and therefore, individual possums.</p>

Testing the behaviour of Australian brushtail possums (Trichosurus vulpecula) to candidate semiochemicals from conspecifics’ urine

<p>The Australian brushtail possum (Trichosurus vulpecula) is a prolific introduced mammalian pest. Current pest control methods involve traps and poisons, but are proving to be ineffective long term solutions. As semiochemical lures are thought to be more attractive than food-based lures at low densities, researchers are attempting to utilize semiochemicals for kill traps. The objectives of this thesis were to create a testing protocol for use in a research colony of possums and use that protocol to test the attractiveness of semiochemicals found in possum urine that had been positively associated with possum attraction and interest in urine.. I hypothesised that there would be an observer effect present in the colony due to the nature of the colony husbandry protocols. There was no statistically significant observer effect present in the colony for eating, interaction, sitting, grooming or enclosure use (front or back). However, there was a trend (across the colony) that sitting and grooming increased in the presence of an observer. From these results, I designed an active presentation protocol for testing semiochemicals. I predicted that the most attractive compounds would belong to the acids and alcohol chemical groups. Overall there was no statistically significant difference between the semiochemicals. However, when taken individually there was clear evidence that five of the semiochemicals (belonging to the ketone, alcohol and phenol chemical groups) were more attractive than their control and the standard lure. It has been shown in this thesis that the attractiveness of semiochemicals can be tested in a small research colony. However, limits on colony size greatly reduce statistical power. For future studies, I would recommend increasing the sample size or instead developing field-based bioassays capable of being repeated across a greater number of sites, populations and therefore, individual possums.</p>

Unrestricted gene flow between two subspecies of translocated brushtail possums (Trichosurus vulpecula) in Aotearoa New Zealand

Two lineages of brushtail possums (Trichosurus vulpecula) were historically introduced to Aotearoa New Zealand, and these two subspecies have different phenotypic forms. Despite over 100 years of potential interbreeding, they appear to retain morphological differences, which may indicate reproductive isolation. We examined this using population samples from a confined landscape and scored each specimen for phenotype using a number of fur colour traits. This resulted in a bimodal trait distribution expected for segregated grey and black lineages. We also sought evidence for genetic partitioning based on spatial and temporal effects. Genetic structure and rates of genetic mixing were determined using seven neutral, species-specific nuclear microsatellite markers and mitochondrial DNA control region sequence. Genotype analyses indicated high levels of variation and mtDNA sequences formed two major haplogroups. Pairwise tests for population differentiation of these markers found no evidence of subdivision, indicating that these brushtail possums behave as a single randomly mating unit. Despite maintenance of two main colour phenotypes with relatively few intermediates, previous inference of assortative mating and anecdotes of distinct races, our data indicate that New Zealand brushtail possums can freely interbreed, and that in some locations they have formed completely mixed populations where neutral genetic markers are unrelated to phenotype. This has implications for effective pest management towards eradication.

Comparative Study of Brain Ontogeny: Marsupials, Humans and Other Eutherians

The human brain is commonly considered unique in its growth pattern, especially in its fast growth in early infancy. Consequently, many researchers were encouraged to find peculiarities in the human brain and development which differentiated it from the brains of other animals. In this paper, we argue that the pattern of human brain growth is not different from that of other mammals, both marsupials and eutherians. Thus, our study, challenges the notion of the uniqueness of the human brain and its development indicating that specifically human mental abilities are not a result of brain morphology or size. In order to test our hypothesis we studied the ontogeny of brain weight relative to body weight using pouch young sample of 43 koalas (Phascolarctos cinereus), 28 possums (Trichosurus vulpecula), and 36 tammar wallabies (Macropus eugenii) preserved in a solution of 10 % buffered formalin. We also analysed the growth of brain vs. body size in all eutherian species falling into this group (humans, rhesus monkeys, dogs, cats, rats and mice).

Vulpeculin: a novel and abundant lipocalin in the urine of the common brushtail possum, Trichosurus vulpecula

Lipocalins are a family of secreted proteins. They are capable of binding small lipophilic compounds and have been extensively studied for their role in chemosignalling in rodent urine. Urine of the common brushtail possum ( Trichosurus vulpecula ) contains a prominent glycoprotein of 20 kDa, expressed in both sexes. We have isolated this protein and determined its primary sequence by mass spectrometry, including the use of metabolic labelling to resolve the leucine/isoleucine isobaric ambiguity. The protein sequence was identified as a lipocalin, and phylogenetic analysis grouped the protein with other marsupial lipocalin sequences in a phylogenetic clade distinct from established cross-species lipocalin sub-families. The pattern of expression in possum urine and the similarity in sequence and structure to other lipocalins suggests this protein may have a role in brushtail possum chemosignalling.