Dispersal among populations of Caridina sp (Decapoda : Atyidae) in coastal lowland streams, south-eastern Queensland, Australia

Caridina sp. is an atyid shrimp occupying coastal streams in south-eastern Queensland and northern New South Wales. Shrimps from two geographic regions in south-eastern Queensland were examined. An analysis of 7 allozyme loci showed very high levels of genetic differentiation among catchments (F ST = 0.65) with much lower levels within catchments. This indicates extremely limited dispersal among catchments with greater levels within catchments. The levels of genetic differentiation were even greater than previously reported for two other atyid shrimp species occurring in upland rainforest streams. Populations from the Noosa River were more similar to those from the Glasshouse Mountains than to those from the geographically closer Tin Can Bay streams. This pattern was remarkably similar to that of a fish species occurring in the same streams and may reflect a recent confluence of streams from the Glasshouse Mountains and the Noosa River regions.Griffith Sciences, Griffith Institute for Drug DiscoveryNo Full Tex

Propafenone as potential AgoKir: exploration of long-term effects and mechanisms of propafenone on Kir2.1 channel

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Chinese Scholarship Council Background Inward rectifying potassium (Kir) channel expression and activity are tightly regulated within the heart. Kir channels play key roles in shaping cardiac action potentials, having a reduced conductance at depolarized potentials but contributing to the final stage of repolarization and resting membrane stability. The Kir2.1 channel protein has polyamine binding residues in both the transmembrane (D172) and the cytoplasmic domains (E224,E299), responsible for the process of inward rectification. A reduced functioning of Kir2.1 causes 1) Andersen-Tawil Syndrom and 2) is present in a subset of heart failure patients. Restoration of normal Kir2.1 function by agonists of Kir2.1 (AgoKirs) would be beneficial. The drug propafenone is identified as an AgoKir, but its long-term effects on Kir2.1 protein expression and subcellular localisation is unknown. Purpose To investigate propafenone's long-term effect on Kir2.1 expression and its underlying mechanisms in cell systems. Methods GFP, Dendra2 or non-tagged wildtype (WT) and mutant Kir2.1 expression constructs were transiently or stably (HEK-KWGF; CHO-KD cell lines) expressed in Human Embryonic Kidney and Chinese Hamster Ovary cells. Kir2.1 carried currents were measured by single cell patch clamp electrophysiology. Kir2.1 proteins expression levels were determined by Western blot analysis, whereas conventional immunofluorescence and advanced live-imaging microscopy were used to assess the subcellular localisation of Kir2.1 proteins. Propafenone was dissolved in DMSO,BaCl2 was used as Kir2.1 channel inhibitor. Results Acute administration of 0.1 and 0.5 µM propafenone increased Kir2.1 carried outward current confirming the drug's Agokir status. Propafenone dose-dependently increased WT Kir2.1 expression levels (2.63±0.40 fold increase at 25 µM and 2.75±0.56 fold increase at 50 µM, 24h) in a process that is independent of the E224, E299 and D172 polyamine binding sites, and the R312 residue which is adjacent to the proposed propafenone binding site. Propafenone (25, 50 µM, 24h) induced intracellular accumulation of WT and mutant Kir2.1 proteins in the late endosome/lysosome compartment (Figure). Channel inhibition by BaCl2 did not affect the propafenone responses on Kir2.1 expression levels or subcellular localisation. Conclusion Acute administration of propafenone at low concentrations increases Kir2.1 currents. Chronic propafenone treatment at only 25-100 times higher concentrations results in increased Kir2.1 protein expression levels and intracellular accumulation in late endosomes and/or lysosomes. Our data support the ability of propafenone at low concentrations to function as AgoKirs without disturbing Kir2.1 protein handing. </jats:sec

Mitochondrial DNA Signatures of Restricted Gene Flow Within Divergent Lineages of an Atyid Shrimp (Paratya Australiensis)

We measured spatial genetic structure within three previously described mitochondrial lineages of the atyid shrimp, Paratya australiensis, occurring in upland streams of two major catchments within the Sydney Water Supply Catchment, New South Wales, Australia. In all three lineages, there was significant spatial structuring of genetic variation between catchments. In two lineages, recurrent but restricted maternal gene flow has apparently predominated in shaping within-catchment genetic structure, although this framework may be overlaid with episodic contiguous/long-distance expansion events. In the third lineage, there was no evidence of spatial genetic structuring within one of the catchments, because one haplotype was both common and widespread throughout the sampled area. High-frequency haplotypes were also shared among subcatchments in the other two lineages, and we discuss both historical and contemporary processes that may have left these genetic signatures. Our results are generally concordant with previous reports of significant population structuring in P. australiensis, occurring in upland river reaches elsewhere in eastern Australia. We propose that restricted dispersal and gene flow among upland populations of P. australiensis is linked to dramatic architectural structuring within and among mountain streams.Griffith Sciences, Griffith School of EnvironmentNo Full Tex