Preliminary stabilisation of stormwater biofilters and loss of filter material.

Stabilisation affects performance of stormwater biofilters operating under intermittent wetting and drying, mainly due to wash-off of filter material. Understanding the dynamics of solids wash-off is crucial in designing stormwater biofilters. The current study analysed the dynamics of solids wash-off in stormwater biofilters and quantified the loss of solids from the filter. Four Perspex™ bioretention columns (94 mm internal diameter) were fabricated with a filter layer that contained 8% organic material and were fed with tap water with different numbers of antecedent dry days (0-40 day) at 100 mL/min. Samples were collected from the outflow and tested for particle size distribution and total solids and turbidity. Solids of particle size less than 50 microns were washed off from the filter during the stabilisation period, indicating that no sand particles were washed off. The very first event after commissioning the filter resulted in the highest wash-off of solids (approximately 75 g of fines) while a significant drop in wash-off followed from the second event. An empirical model fitted to the data showed that preliminary stabilisation of a filter occurs in the first three events, during which almost 25% of fines are lost from the filter.

Identification and Characterization of an Insulin-Like Receptor Involved in Crustacean Reproduction.

Sexual differentiation and maintenance of masculinity in crustaceans has been suggested as being regulated by a single androgenic gland (AG) insulin-like peptide (IAG). However, downstream elements involved in the signaling cascade remain unknown. Here we identified and characterized a gene encoding an insulin-like receptor in the prawn Macrobrachium rosenbergii (Mr-IR), the first such gene detected in a decapod crustacean. In mining for IRs and other insulin signaling-related genes, we constructed a comprehensive M. rosenbergii transcriptomic library from multiple sources. In parallel we sequenced the complete Mr-IR cDNA, confirmed in the wide transcriptomic library. Mr-IR expression was detected in most tissues in both males and females, including the AG and gonads. To study Mr-IR function, we performed long-term RNA interference (RNAi) silencing in young male prawns. Although having no effect on growth, Mr-IR silencing advanced the appearance of a male-specific secondary trait. The most noted effects of Mr-IR silencing were hypertrophy of the AG and the associated increased production of Mr-IAG, with an unusual abundance of immature sperm cells being seen in the distal sperm duct. A ligand blot assay using de novo recombinant Mr-IAG confirmed the existence of a ligand-receptor interaction. Whereas these results suggest a role for Mr-IR in the regulation of the AG, we did not see any sexual shift after silencing of Mr-IR, as occurred when the ligand-encoding Mr-IAG gene was silenced. This suggests that sexual differentiation in crustaceans involve more than a single Mr-IAG receptor, emphasizing the complexity of sexual differentiation and maintenance.

Systematics and biogeography of the Gondwanan Orthocladiinae (Diptera: Chironomidae).

Restrictions to effective dispersal and gene flow caused by the fragmentation of ancient supercontinents are considered to have driven diversification and speciation on disjunct landmasses globally. Investigating the role that these processes have played in the development of diversity within and among taxa is crucial to understanding the origins and evolution of regional biotas. Within the chironomid (non-biting midge) subfamily Orthocladiinae (Diptera: Chironomidae), a group of genera that are distributed across the austral continents (Australia, New Zealand, South America) have been proposed to represent a relict Gondwanan clade. We used a molecular approach to resolve relationships among taxa with the aim to determine the relative roles that vicariance and dispersal may have played in the evolution of this group. Continental biotas did not form monophyletic groups, in accordance with expectations given existing morphological evidence. Patterns of phylogenetic relationships among taxa did not accord with expected patterns based on the geological sequence of break-up of the Gondwanan supercontinent. Likewise, divergence time estimates, particularly for New Zealand taxa, largely post-dated continental fragmentation and implied instead that several transoceanic dispersal events may have occurred post-vicariance. Passive dispersal of gravid female chironomid adults is the most likely mechanism for transoceanic movement, potentially facilitated by West Wind Drift or anti-cyclone fronts. Estimated timings of divergence among Australian and South American Botryocladius, on the other hand, were congruent with the proposed ages of separation of the two continents from Antarctica. Taken together, these data suggest that a complex relationship between both vicariance and dispersal may explain the evolution of this group. The sampling regime we implemented here was the most intensive yet performed for austral members of the Orthocladiinae and unsurprisingly revealed several novel taxa that will require formal description.

Isolation and characterization of 15 polymorphic microsatellite DNA loci from Argyrosomus japonicus (mulloway), a new aquaculture species in Australia.

Fifteen microsatellite loci were isolated for population genetic studies of mulloway (Argyrosomus japonicus), a commercial/recreational fish species in Southern Australia. A genomic library was screened randomly for di- tri- and tetranucleotide repeats. Fifteen microsatellite marker loci were developed that were highly polymorphic (allele number ranged from four to 18). Observed and expected heterozygosities ranged from 0.17 to 1 and from 0.27 to 0.91, respectively. These markers have proven useful for estimating genetic variation and for evaluating population structure across the species' natural distribution. They also provide powerful tools for optimizing hatchery practices to conserve genetic diversity.

Population subdivision in Siamese mud carp Henicorhynchus siamensis in the Mekong River basin: implications for management.

A molecular approach was employed to investigate stock structure in Siamese mud carp Henicorhynchus siamensis populations collected from 14 sites across mainland south-east Asia, with the major focus being the lower Mekong River basin. Spatial analysis of a mitochondrial DNA fragment (ATPase 6 and 8) identified four stocks in the Mekong River basin that were all significantly differentiated from a population in the nearby Khlong River, Thailand. In the Mekong River basin, populations in northern Lao People's Democratic Republic and northern Thailand represent two independent stocks, and samples from Thai tributaries group with those from adjacent Mekong sites above the Khone Falls to form a third stock. All sites below the Khone Falls constituted a single vast stock that includes Cambodia and the Mekong Delta in Vietnam. While H. siamensis is considered currently to undertake extensive annual migrations across the Mekong River basin, the data presented here suggest that natural gene flow may occur over much more restricted geographical scales within the basin, and hence populations may need to be managed at finer spatial scales than at the whole-of-drainage-basin level.

Phylogeographic evidence for the existence of an ancient biogeographic barrier: the Isthmus of Kra Seaway.

Biogeographic boundaries are characterised by distinct faunal and floral assemblages restricted on either side, but patterns among groups of taxa often vary and may not be discrete. Historical biogeography as a consequence, while providing crucial insights into the relationship between biological diversity and earth history, has some limitations. Patterns of intraspecific molecular variation, however, may show unambiguous evidence for such historical divides, and can be used to test competing biogeographic hypotheses (often based on the dispersal-vicariance debate). Here, we utilise this method to test the hypothesis that a major biogeographic transition zone between the Sundaic and Indochinese biotas, located just north of the Isthmus of Kra in SE Asia, is the result of Neogene marine transgressions that breached the Isthmus in two locations for prolonged periods of time (>1 million year duration). Phylogeographic analyses of a freshwater decapod crustacean, the giant freshwater prawn Macrobrachium rosenbergii, strongly supports the historical existence of the more northerly postulated seaway. Results presented here highlight the power of utilising intraspecific molecular variation in testing biogeographical hypotheses.

High levels of extra-group paternity in a population of Australian magpies Gymnorhina tibicen: evidence from microsatellite analysis.

Breeding systems vary widely in birds, from monogamous pairs through to complex group systems where subordinates assist breeding individuals to rear young each season. The Australian magpie varies geographically both in plumage patterns and social organization. Some populations of both eastern and western plumage forms are plural breeders with group size varying from three to over 15 mature individuals. This study used variation at microsatellite loci to determine the level of extra-group paternity in a population of the western form near Perth in Western Australia. Extra-group paternity was the highest recorded for any bird species to date (82%) and indicates that few offspring within a territory are sired by the social partner of the female. In addition, the data indicated that nearly 10% of juveniles were not the genetic offspring of any female within their territory, suggesting some intraspecific brood parasitism. Taken together, these findings are remarkable considering the highly territorial nature of the species and the extent of territorial defence practised by all members of the group towards extra-group conspecifics during daylight hours.

Population genetic structure of Australian magpies: evidence for regional differences in juvenile dispersal behaviour.

Territorial group size in Australian magpies (Gymnorhina tibicen) ranges from monogamous pairs to groups of more than 20 individuals. It has been hypothesized that large territorial groups result from the retention of juveniles after a breeding effort. If this is true, local populations consisting of large groups are likely to exhibit the most genetic structure, because over time similar genotypes will tend to be confined to limited areas if juveniles are predominantly philopatric. The objective of the present study was to test this hypothesis using allozyme and mitochondrial DNA data to provide indirect estimates of regional gene flow (derived from hierarchical population subdivision analyses). These data were used in combination with estimates of group size to infer patterns of dispersal among magpie populations across mainland Australia. Territorial groups were significantly larger in the south-west compared to three eastern regions. Although inferred levels of gene flow were substantial for all four regions, a striking pattern emerged from both sets of genetic data: more differentiation was evident among populations in the south-western region than in any eastern region. We conclude that levels of juvenile dispersal influence group size in G. tibicen, because in the south-western region where groups were largest, populations were most genetically differentiated. Our results suggest that contrasting population genetic structures may develop within a single species as a result of differences in social system.

Patterns of differentiation among wild rabbit populations Oryctolagus cuniculus L. in arid and semiarid ecosystems of north-eastern Australia.

Feral rabbit populations in Australia have generally been managed using localized control procedures. While these procedures may result in local extinctions, persistence of populations will depend on the probability of recolonization. Genetic markers developed using temperature gradient gel electrophoresis (TGGE) combined with heteroduplex analysis (HA) of mitochondrial DNA (mtDNA) were used to characterize the degree of subdivision and extent of gene flow within and among rabbit populations distributed over large distances (up to 1000 km) in southern Queensland (QLD) and north-west New South Wales (NSW), Australia. TGGE analyses revealed significant heterogeneity in mtDNA control region haplotype frequencies. From heterogeneity chi 2 tests, it was evident that the differentiation observed was largely attributable to five sites which were located in the semiarid eastern region, whereas haplotype frequencies were homogeneous throughout the arid western region. These results suggest that there are independent population systems within the study area. The extent of gene flow among local populations within each system is related to the spatial configuration of acceptable habitat patches and the persistence of the populations is determined by the probability of recolonization following local extinction. These data suggest that to provide better overall control of rabbit populations, different management strategies may be necessary in arid and semiarid ecosystems. In arid south-west QLD and north-west NSW, where extensive gene flow occurs over large distances, rabbit populations should be managed at a regional level. In semiarid eastern QLD, where gene flow is restricted and populations are more isolated, localized control procedures may provide effective short-term relief. These results indicate that in nonequilibrium systems with patchy distribution of individuals, the interpretation of migration rate from estimates of gene flow obtained using existing genetic models must include an understanding of the spatial and temporal scales over which population processes operate.

Limited genetic differentiation among wild Oryctolagus cuniculus L. (rabbit) populations in arid eastern Australia.

A systems approach is necessary for effective control of feral rabbit (Oryctolagus cuniculus L.) populations in the arid environments of Australia. Localized control procedures may result in local extinctions, but the persistence of the overall population will depend on the probability of recolonization, and hence, the degree of isolation of each local population unit. Genetic markers obtained using allozyme electrophoresis, temperature gradient gel electrophoresis (TGGE) and heteroduplex analysis (HA) were used to characterize the degree of structuring and extent of gene flow among rabbit populations in arid Queensland, Australia. Allozyme allele frequency data showed that there was no significant differentiation among sites (average FST = 0.005) and no isolation-by-distance or environmental discontinuity effects. TGGE/HA results also revealed no significant differentiation in mitochondrial DNA Control Region haplotype frequencies among sites and low interpopulation nucleotide divergence estimates (NST = 0.013). Therefore, rabbit populations exhibited a high degree of gene flow over large geographical areas (1600 km2) and were essentially a single panmictic unit. Unpredictable environmental conditions together with the spatial configuration of habitats which possess different probabilities of extinction may have resulted in repeated local extinctions followed by recolonization and homogenizing gene flow. These data suggest that current rabbit control strategies based on individual warren management may not achieve effective control in arid Queensland.

Aldehyde reductase isozymes in the mouse: evidence for two new loci and localization of Ahr-3 on chromosome 7.

Evidence is presented for two new forms of mouse liver and kidney aldehyde reductase activity (designated AHR-3 and AHR-4) resolved using cellulose acetate electrophoresis zymogram techniques and stained by glyceraldehyde and NADPH as substrate and coenzyme, respectively. Activity variants were observed for those isozymes among inbred strains of mice and used in a genetic analyses to support a proposal for two new genetic loci (Ahr-3 and Ah-4) which control the activity phenotype for these isozymes. Segregation analysis indicated that these loci are separately localized on the mouse genome, with Ahr-3 positioned on the distal end of chromosome 7. Liver AHR-2 (or hexonate dehydrogenase) exhibited no detectable phenotypic variation among the 44 inbred strains of mice examined. The AHR-3 and AHR-4 isozymes were readily distinguished from AHR-1 [or aldehyde reductase A2, described previously by Duley and Holmes (Biochem. Genet. 20:1067, 1982)], hexonate dehydrogenase (AHR-2), and alcohol dehydrogenase A2 in terms of their differential substrate, coenzyme, and inhibitor specificities.

Gene markers for alcohol-metabolizing enzymes among recombinant inbred strains of mice with differential behavioural responses towards alcohol.

The genetic variability of alcohol dehydrogenase (C2 isozyme), aldehyde dehydrogenase (A2 isozyme) and aldehyde oxidase (A2 isozyme) has been examined among recombinant inbred strains of mice which have been previously studied concerning their differential behavioural responses towards alcohol. The results showed no correlation between biochemical phenotype for these loci and behavioural response.

Biochemical and genetic studies on mouse aldehyde dehydrogenases.

Aldehyde dehydrogenase (AHD) exists as isozymes which are differentially distributed among tissues and subcellular fractions of mouse tissues. Genetic variants for liver mitochondrial (AHD-1) and cytoplasmic (AHD-2) isozymes have been used to map the responsible loci (Ahd-1 and Ahd-2) on chromosomes 4 and 19 respectively. Evidence for a regulatory locus (Ahd-3r) controlling the inducibility of the mouse liver microsomal isozyme (AHD-3) has also been obtained. More recent studies have described genetic and biochemical evidence for three additional AHD isozymes: a stomach isozyme (AHD-4); another liver mitochondrial enzyme (AHD-5); and a testis isozyme (AHD-6). Genetic analyses have indicated that AHD-4 and AHD-6 are encoded by distinct but closely linked loci on the mouse genome (Ahd-4 and Ahd-6), which segregate independently of Ahd-1 and Ahd-2. Liver mitochondrial isozymes, AHD-1 and AHD-5, have been purified to homogeneity using affinity chromatography. The very high affinity of AHD-5 for acetaldehyde suggests that this enzyme is predominantly responsible for acetaldehyde oxidation in mouse liver mitochondria.

Biochemical genetics of aldehyde dehydrogenase isozymes in the mouse: evidence for stomach- and testis-specific isozymes.

Electrophoretic and activity variants have been observed for stomach and testis aldehyde dehydrogenases, respectively, among inbred strains of the house mouse (Mus musculus). Genetic evidence was obtained for two new loci encoding these isozymes (designated Ahd-4 and Ahd-6, respectively, for the stomach and testis isozymes) which segregated independently of a number of mouse gene markers, including Ahd-1 (encoding mitochondrial aldehyde dehydrogenase) on chromosome 4, ep (pale ears), a marker for chromosome 19, on which Ahd-2 (encoding liver cytosolic aldehyde dehydrogenase) has been previously localized, and Adh-3 (encoding the stomach-specific isozyme of alcohol dehydrogenase) on chromosome 3. Recombination studies have indicated, however, that Ahd-4 and Ahd-6 are distinct but closely linked loci on the mouse genome. An extensive survey of the distribution of Ahd-1, Ahd-2, Ahd-4, and Ahd-6 alleles among 56 strains of mice is reported. No variants have been observed, so far, for the microsomal (AHD-3) and mitochondrial/cytosolic (AHD-5) isozymes previously described. This study, in combination with previous investigations on mouse aldehyde dehydrogenases, provides evidence for six genetic loci for this enzyme.

Electrophoretic analyses of alcohol dehydrogenase, aldehyde dehydrogenase, aldehyde reductase, aldehyde oxidase and xanthine oxidase from horse tissues.

Cellulose acetate zymograms of alcohol dehydrogenase (ADH), aldehyde dehydrogenase (AHD), aldehyde reductase (AHR), aldehyde oxidase (AOX) and xanthine oxidase (XOX) extracted from horse tissues were examined. Five ADH isozymes were resolved: three corresponded to the previously reported class I ADHs (EE, ES and SS) (Theorell, 1969); a single form of class II ADH (designated ADH-C2) and of class III ADH (designated ADH-B2) were also observed. The latter isozyme was widely distributed in horse tissues whereas the other enzymes were found predominantly in liver. Four AHD isozymes were differentially distributed in subcellular preparations of horse liver: AHD-1 (large granules); AHD-3 (small granules); and AHD-2, AHD-4 (cytoplasm). AHD-1 was more widely distributed among the horse tissues examined. Liver represented the major source of activity for most AHDs. A single additional form of NADPH-dependent AHR activity (identified as hexonate dehydrogenase), other than the ADHs previously described, was observed in horse liver. Single forms of AOX and XOX were observed in horse tissue extracts, with highest activities in liver.

Aldehyde oxidase and alcohol dehydrogenase genetics in the mouse. New alleles for the Aox-2 and Adh-3 loci.

The genetic variability of one of the liver isozymes of aldehyde oxidase (AOX-B2 or AOX-2) and the stomach isozyme of alcohol dehydrogenase (ADH-C2) has been examined among strains of mice. Evidence is presented for a fourth allele of Aox-2 and a third allele of Adh-3. The hybrid allozyme pattern for mouse liver AOX was consistent with a dimeric subunit structure for this enzyme.