EchidnaCSI is a citizen science project that combines field ecology and molecular biology for echidna conservation.
The project aims to:
establish the first Australia wide detailed echidna distribution map. Integration of historic data and in-depth analysis in specific areas (e.g. revegetated, agricultural and urbanised) will provide valuable information about variation in echidna numbers and how they are affected by our changing environment.
utilise the collection and molecular analysis of echidna scat samples from captive and wild populations to provide novel insight into fundamental aspects of echidna biology (e.g. diet, stress, breeding) and their role in natural or cultivated environments.
use EchidnaCSI as an outreach and engagement platform via traditional (media, seminars, flyers, videos) and social (e.g. phone app, Facebook, Twitter, email) media to educate and enthuse the community about biodiversity, environmental awareness and the value of interdisciplinary research for application in conservation and animal biology, and to foster change in behaviour to help protect and preserve biodiversity.
The project has now been running for a year and we have more than 5000 users with over 2800 sightings recorded and 200 scats sent in. This provides interested students to do projects on the data and molecular analysis of these unique samples.
Echidna trains can be observed during breeding season where several mature males follow one female. Which of the males is mating successfully? This is one of the questions we address by using a combination of radio tracking and molecular genetics on echidnas at Monarto Zoo. In this project we also investigate other general aspects of echidna ecology, population genetics and development.
The platypus genome was published in 2008 and provided fundamental new information about monotreme biology and mammalian evolution. The echidna genome has been sequenced and we are part of a small international team helping with the assembly and carrying out analysis on the genome for the Echidna genome publication (which will also feature a much improved Platypus genome). This is a great opportunity for students to take part in an international collaboration, which will provide the first echidna genome assembly and carries out analysis of the echidna genome to better understand the fascinating biology of these animals.
Monotremes feature an extraordinarily complex sex chromosome system that consists of 5X and 5Y chromosomes in platypus and 5X and 4Y chromosomes in echidna. At the first meiotic division the ten sex chromosomes in male platypus (nine in echidna) assemble into a sex chromosomes chain. Over the past five years we have been able to identify these sex chromosomes and show how they are arranged in the chain. We have also shown how they commence pairing in prophase I, how they segregate at anaphase I, and where they reside in mature sperm. Our current work investigates the composition of the synaptonemal complex (formed by proteins that hold chromosomes together at meiosis I). We also investigate if the monotreme sex chromosome complex undergoes sex chromosome inactivation as in other mammals. In addition, we investigate the pattern of meiotic recombination on monotreme sex chromosomes.
Sex determination is one of the most puzzling aspects of monotreme biology. They have an extraordinary complex sex chromosomes system that consists of ten sex chromosomes in platypus and nine in echidna. In contrast to sex chromosomes in other mammals, platypus sex chromosomes show extensive homology to bird sex chromosomes.
In addition the mammalian sex determining gene SRY is missing in platypus. We are investigating candidate sex determining genes (know mammalian sex determination genes) and we are identifying and characterising new genes on the Y specific parts of the five Y chromosomes in platypus to get insight into how sex is determined in these animals. This will also potentially identify new sex determination and spermatogenesis genes in other mammals including humans.
Monotremes present a unique biological challenge in the context of MSCI formation as their sex chromosome complement far exceeds that of most therians due to their remarkable 10 sex chromosomes (platypus). A significantly greater amount of unpaired DNA is therefore present in spermatocytes at meiosis and an increased number of genes are potentially impacted by any enforced silencing. This project aims to establish whether the platypus and echidna sex chromosome DNA undergoes equivalent epigenetic modifications and gene silencing to that observed in mouse.
During spermatogenesis in mammals, the X and Y sex chromosomes undergo a complex series of epigenetic modifications to effect genetic silencing, termed meiotic sex chromosome inactivation (MSCI). Accompanying these changes is the event of ‘sex body’ formation at male meiotic prophase I, a process in which the sex chromosomes undergo chromatin condensation and are clearly visible at the nuclear periphery, separate from the synapsed autosomes.
In mammals a sex chromosome system has evolved where males have one X chromosome and a very gene poor Y chromosome and females have two copies of the X chromosome. This means females have two copies of many X-linked genes while males have only one copy. In order to compensate for the difference in gene dosage in females one X chromosome is inactivated in all somatic cells. This inactivation is initiated through expression of the Xist gene from the inactive X. In addition, epigenetic modifications such as DNA methylation, histone deacetylation and histone variants like macroH2A play an important role in the transcriptional silencing of one of the X chromosomes.
It has recently been shown that the Xist gene has evolved only recently in the eutherian lineage. So far nothing is known about dosage compensation and X inactivation in monotremes but it is particularly interesting to investigate this in monotremes as they feature five pairs of X chromosomes in females and in males one copy of each of these X chromosomes and five Y chromosomes in platypus and four Y chromosomes in echidna. We investigate if X inactivation occurs by combination of immunostaining with antibodies and fluorescence in situ hybridisation with X-specific DNA probes on fibroblast cell lines and western blotting to detect epigenetic changes on the X chromosomes in females. This will reveal whether or not dosage compensation and X inactivation occurs in female monotremes.
Function and Evolution of Genes Involved in Sex Determination and Placentation in Mammals
The reproductive biology is one of the most puzzling aspects of monotremes. They are the only egg-laying mammal but they do have a simple placenta which supports the embryo for a short period of time. Monotremes have an extraordinary complex sex chromosomes system that consists of ten sex chromosomes in platypus and nine in echidna. In contrast to sex chromosomes in other mammals, platypus sex chromosomes show extensive homology to bird sex chromosomes. In addition the mammalian sex determining gene SRY is missing in platypus. As the most distant mammalian relative to humans monotremes can provide valuable insights into the evolution of sex determination and placentation genes. We identify and further characterise genes that are involved in these fascinating aspects of reproduction in monotremes, mouse and humans.
The inflammatory response pathway in humans involves four caspases, caspase-1, -4, -5 and caspase-12. Caspase-1 is activated in response to many bacterial pathogens through inflammasome formation, similar to apoptosome assembly, which leads to caspase-9 activation. Active caspase-1 targets and cleaves the proinflammatory cytokines IL-1 and IL-18 leading to their secretion by the cell to produce an inflammatory response. Specific bacterial or fungal pathogens can initiate distinct inflammatory responses in regard to the mode of caspase-1 activation and a major question is how response specificity is determined.
To date we have no information about the molecular mechanism underlying the inflammatory response in platypus. This project aims to characterise the dynamics of the inflammatory response in a monotreme cell culture system established in our laboratory. In addition to unravelling a basic biological pathway in platypus we will use this to investigate the inflammatory response to a potentially lethal fungal infection that effects platypus in Tasmania.
In inter- and intra-specific hybrids different genomes are combined and forced to interact. We hypothesise that novel genetic and epigenetic interactions in hybrid genomes cause major differences in gene regulation and gene expression. In collaboration with Prof. S. Hiendleder, we use hybrid embryos of the commonly bred Angus (Bos p. taurus) and Brahman (Bos p. indicus) cattle to study the genetic and epigenetic basis of hybrid phenotypes.