Annette Koenders

Cryptic species of the Eucypris virens species complex (Ostracoda, Crustacea) from Europe have invaded Western Australia.

Eucypris virens, an ostracod with mixed reproduction and Holarctic distribution, forms a species complex with more than 35 cryptic species in Europe. Here, we analysed COI and LSU DNA sequence data from Western Australian E. virens to distinguish between the possibilities that vicariant processes have led to the formation of Australian E. virens species or that these ostracods have been introduced into Western Australia. Phylogenetic reconstructions, genetic networks and estimates of genetic distances all show clearly that Western Australian and European E. virens are very closely related. Some haplotypes are identical, others are only separated by one or two mutational steps. Among the Western Australian representatives of E. virens, three phylogenetic clades can be distinguished. We identified three European cryptic species as ancestors for two of the Western Australian clades and one close relative to the third Western Australian clade. We therefore conclude that E.virens has been introduced into Western Australia, most likely from western Europe, and did not diverge in Australia. In Europe, E. virens shows a typical pattern of geographic parthenogenesis while we found only asexual populations in Western Australia.

Pax genes in myogenesis: alternate transcripts add complexity.

Pax3 and Pax7 are powerful myogenic inducers and hence play a critical role in skeletal muscle development and regeneration. In this paper we discuss the role of Pax3 and Pax7 in dorsal patterning of the somite with subsequent determination of myogenic precursor cells for muscle formation within the developing embryo and in adult muscle. Recent evidence of the ability of stem cells to contribute to muscle regeneration in adult tissues, and the role of Pax7 in conversion of multipotent stem cells to the myogenic lineage are also discussed. Several tissue specific Pax7 transcripts that encode isoforms with different DNA binding characteristics and potentially distinct transactivation specificities are identified. The expression of a range of transcripts in the determination of different tissue lineages and distinct cell populations both in the embryo and in the adult indicates an extraordinary level of complexity. A detailed understanding of these molecules and their functions during embryogenesis and adult muscle formation is imperative for future stem cell therapies.

Relationship between antibiotic resistance genes and metals in residential soil samples from Western Australia

Increasing drug-resistant infections have drawn research interest towards examining environmental bacteria and the discovery that many factors, including elevated metal conditions, contribute to proliferation of antibiotic resistance (AR). This study examined 90 garden soils from Western Australia to evaluate predictions of antibiotic resistance genes from total metal conditions by comparing the concentrations of 12 metals and 13 genes related to tetracycline, beta-lactam and sulphonamide resistance. Relationships existed between metals and genes, but trends varied. All metals, except Se and Co, were related to at least one AR gene in terms of absolute gene numbers, but only Al, Mn and Pb were associated with a higher percentage of soil bacteria exhibiting resistance, which is a possible indicator of population selection. Correlations improved when multiple factors were considered simultaneously in a multiple linear regression model, suggesting the possibility of additive effects occurring. Soil-metal concentrations must be considered when determining risks of AR in the environment and the proliferation of resistance.

Assessing practical laboratory skills in undergraduate molecular biology courses

This study explored a new strategy of assessing laboratory skills in a molecular biology course to improve: student effort in preparation for and participation in laboratory work; valid evaluation of learning outcomes; and students’ employment prospects through provision of evidence of their skills. Previously, assessment was based on written laboratory reports and examinations, not on the demonstration of practical skills per se. This action research project involved altering the assessment design so that a greater proportion of the marks was allocated to active participation and learning in the laboratory, partially replacing a single examination with direct observation of student participation and learning over a prolonged period of weekly laboratory sessions. We ascertained staff and students’ perceptions of the new assessment processes by means of a Likert scale questionnaire, student focus group and individual staff interviews. Overall, students and staff evaluated the new assessment structure positively, citing fairness, authenticity and reward for effort. Results also revealed the need for specific training of staff in this form of assessment and indicated staff–student ratios made assessment burdensome. Four out of five students reported that an increased awareness of the importance of practical laboratory skills stimulated them to greater efforts to achieve.

Understanding subterranean variability: the first genus of Bathynellidae (Bathynellacea, Crustacea) from Western Australia described through a morphological and multigene approach

Abstract. The number of subterranean taxa discovered in the north of Western Australia has substantially increased due to the requirements for environmental surveys related to mining development. Challenges in estimating subterranean biodiversity and distributions are related to lack of knowledge of taxa with convergent morphological characters in a largely unobservable ecosystem setting. An integrated approach is warranted to understand such complexity. Bathynellidae occur in most Australian aquifers, but only one species has been described so far, and the group lacks a reliable taxonomic framework. A new genus and one new species from the Pilbara region of Western Australia, Pilbaranella ethelensis, gen. et sp. nov., is described using both morphological and molecular data. Three additional species of Pilbaranella are defined through mitochondrial and nuclear genes, using Automatic Barcode Gap Discovery and Poisson Tree Processes species delimitation methods. A comparison of morphology and 18S rRNA sequences between Pilbaranella, gen. nov. and known lineages provides the evidentiary basis for the decision to establish a new genus. This study provides a morphological and molecular framework to work with Bathynellidae, especially in Australia where a highly diverse fauna remains still undescribed.

Genetic and morphological analysis of multi-stemmed plants of tuart (Eucalyptus gomphocephala)

The tuart–banksia woodlands of the Swan Coastal Plain in Western Australia are characteristic vegetation communities of this coastal region, and Eucalyptus gomphocephala DC. (Myrtaceae; tuart) is an iconic tree of these communities. The species primarily occurs as a tall single-stemmed tree, but at the northern end of the distribution, it also occurs in a multi-stemmed form. Growth habit is frequently used as a taxonomic character in eucalypts, with many complexes having tree and mallee forms, although the genetic characterisation of growth habit in eucalypts has been limited. We investigated the genetic and morphological differentiation among populations of tree and multi-stemmed forms of tuart at the northern end of its distribution. Although the populations showed moderate levels of genetic diversity on the basis of microsatellite markers, as might be expected from populations on the periphery of the distribution, there was no evidence of genetic differentiation associated with the tree and multi-stemmed forms. Morphometric analysis showed some differences in the size of buds and fruits among the populations. Our analysis is consistent with environmentally induced variation in tuart in near-coastal populations where plants grow on poor soils and form may be affected by wind and salt exposure. This result adds to other evidence from pines and Nothofagus of environmental rather than genetic influences on growth form, particularly in stressful environments.

Isolation and expression analysis of a Pax group III gene from the crustacean Cherax destructor

Pax genes encode transcription factors that are critical regulators of key developmental processes in evolutionarily diverse animal phyla. Here we report the first isolation of a Pax gene from a crustacean: a Pax group III gene we have termed CdpaxIII that contains highly conserved DNA-binding domains, the paired domain and homeodomain. CdpaxIII is expressed in the embryo, in adult limb muscle during both quiescence and regeneration, and during the distinct process of epimorphic limb regeneration. Interestingly, CdpaxIII is expressed as two distinct alternate transcripts, one of which is novel in lacking a large portion of its paired domain.

Microorganisms facilitate uptake of dissolved organic nitrogen by seagrass leaves

Microorganisms play a critical role in nitrogen cycling by mineralising dissolved organic nitrogen (DON) compounds into bioavailable inorganic forms (DIN). Although DIN is crucial for seagrass growth, the hypothesis that seagrass leaf associated-microorganisms could convert DON to forms available for plant uptake has never been tested. We conducted a laboratory-based experiment in which seagrass (Posidonia sinuosa) leaves were incubated with 15N-amino acids (aa), with and without associated microorganisms. Samples were collected after 0.5, 2, 6 and 12 h. Both bulk stable isotope and nanoscale secondary ion mass spectrometry (NanoSIMS) analysis showed high accumulation of 15N within seagrass leaf tissues with an associated microbiota, but not in plants devoid of microorganisms. These results significantly change our understanding of the mechanisms of seagrass nitrogen use and provide evidence that seagrass microbiota increase nitrogen availability for uptake by seagrass leaves by mineralising aa, thus enhancing growth and productivity of these important coastal ecosystems.

Global Networks of Symbiodinium-Bacteria Within the Coral Holobiont

Scleractinian corals form the framework of coral reefs and host abundant and diverse microbial communities that are fundamental to their success. A very limited number of studies have examined the co-occurrence of multiple partners within the coral ‘holobiont’ and their pattern of specificity over different geographical scales. In this study, we explored two molecular sequence datasets representing associations between corals and dinoflagellates in the genus Symbiodinium and between corals and bacteria, across the globe. Through a network theory approach, we characterised patterns of co-occurrences between bacteria and Symbiodinium with 13 coral genera across six water basins. The majority of the bacteria-Symbiodinium co-occurrences were specific to either a coral genus or water basin, emphasising both coral host and environment as important factors driving the diversity of coral assemblages. Yet, results also identified bacteria and Symbiodinium that were shared by multiple coral genera across several water basins. The analyses indicate that shared co-occurrences are independent of the phylogenetic and biogeographic relationship of coral hosts.

Research and stakeholders: Bathynellidae (Bathynellacea, Crustacea) case studies in mining areas. New genera from Australia and the enigma of the “cosmopolitan” Bathynella genus

It seems obvious to say that research can provide benefits to multiple stakeholders and that stakeholder involvement is more often than not essential for research to proceed. Concrete examples of these mutual dependencies are valuable, where industry, government agencies and biological studies increase each others’ potential and efficiencies. In the past 20 years the number of subterranean taxa discovered in Australia, especially in the Pilbara bioregion, has increased consistently thanks to environmental and biological surveys, often associated with mining development, but the investment on research needed to understand this vast biodiversity is far from what is required. The family Bathynellidae (Crustacea) occur in most Australian aquifers, but collecting them is not simple and their study and identification are very difficult due to their small and fragile bodies and their conservative morphology. Additionally, the poor and incomplete ‡,§ | § ‡ ‡