Genetic basis of inosine triphosphate pyrophosphohydrolase (ITPA) deficiency

Inosine triphosphate pyrophosphohydrolase (ITPase) deficiency is a common inherited condition characterized by the abnormal accumulation of inosine triphosphate (ITP) in erythrocytes. The genetic basis and pathological consequences of ITPase deficiency are unknown. We have characterized the genomic structure of the ITPA gene, showing that it has eight exons. Five single nucleotide polymorphisms were identified, three silent (138GMA, 561GMA, 708GMA) and two associated with ITPase deficiency (94CMA, IVS2+21AMC). Homozygotes for the 94CMA missense mutation (Pro32 to Thr) had zero erythrocyte ITPase activity, whereas 94CMA heterozygotes averaged 22.5% of the control mean, a level of activity consistent with impaired subunit association of a dimeric enzyme. ITPase activity of IVS2+21AMC homozygotes averaged 60% of the control mean. In order to explore further the relationship between mutations and enzyme activity, we examined the association between genotype and ITPase activity in 100 healthy controls. Ten subjects were heterozygous for 94CMA (allele frequency: 0.06), 24 were heterozygotes for IVS2+21AMC (allele frequency: 0.13) and two were compound heterozygous for these mutations. The activities of IVS2+21AMC heterozygotes and 94CMA/IVS2+21AMC compound heterozygotes were 60% and 10%, respectively, of the normal control mean, suggesting that the intron mutation affects enzyme activity. In all cases when ITPase activity was below the normal range, one or both mutations were found. The ITPA genotype did not correspond to any identifiable red cell phenotype. A possible relationship between ITPase deficiency and increased drug toxicity of purine analogue drugs is proposed.

The Genetic Speciation of Archaeological Fish Bone: A Feasibility Study from Southeast Queensland

Current genetic methods enable highly specific identification of DNA from modern fish bone. The applicability of these methods to the identification of archaeological fish bone was investigated through a study of a sample from late Holocene southeast Queensland sites. The resultant overall success rate of 2% indicates that DNA analysis is, as yet, not feasible for identifying fish bone from any given site. Taphonomic issues influencing the potential of genetic identification methods are raised and discussed in light of this result.

Learning for fun: The unique contribution of educational leisure experiences

What do visitors want or expect from an educational leisure activity such as a visit to a museum, zoo, aquarium or other such experience? Is it to learn something or to experience learning? This paper uses the term 'learning for fun' to refer to the phenomenon in which visitors engage in a learning experience because they value and enjoy the process of learning itself. Five propositions regarding the nature of learning for fun are discussed, drawing on quantitative and qualitative data from visitors to a range of educational leisure activities. The commonalities between learning for fun and other theoretical constructs such as 'experience,' 'flow', 'intrinsic motivation', and 'curiosity' are explored. It is concluded that learning for fun is a unique and distinctive offering of educational leisure experiences, with implications for future research and experience design.

Environmental Risk Factors for Parkinson's Disease

Parkinson’s disease (PD) is a progressive, degenerative, neurological disease. The progressive disability associated with PD results in substantial burdens for those with the condition, their families and society in terms of increased health resource use, earnings loss of affected individuals and family caregivers, poorer quality of life, caregiver burden, disrupted family relationships, decreased social and leisure activities, and deteriorating emotional well-being. Currently, no cure is available and the efficacy of available treatments, such as medication and surgical interventions, decreases with longer duration of the disease. Whilst the cause of PD is unknown, genetic and environmental factors are believed to contribute to its aetiology. Descriptive and analytical epidemiological studies have been conducted in a number of countries in an effort to elucidate the cause, or causes, of PD. Rural residency, farming, well water consumption, pesticide exposure, metals and solvents have been implicated as potential risk factors for PD in some previous epidemiological studies. However, there is substantial disagreement between the results of existing studies. Therefore, the role of environmental exposures in the aetiology of PD remains unclear. The main component of this thesis consists of a case-control study that assessed the contribution of environmental exposures to the risk of developing PD. An existing, previously unanalysed, dataset from a local case-control study was analysed to inform the design of the new case-control study. The analysis results suggested that regular exposure to pesticides and head injury were important risk factors for PD. However, due to the substantial limitations of this existing study, further confirmation of these results was desirable with a more robustly designed epidemiological study. A new exposure measurement instrument (a structured interviewer-delivered questionnaire) was developed for the new case-control study to obtain data on demographic, lifestyle, environmental and medical factors. Prior to its use in the case-control study, the questionnaire was assessed for test-retest repeatability in a series of 32 PD cases and 29 healthy sex-, age- and residential suburb-matched electoral roll controls. High repeatability was demonstrated for lifestyle exposures, such as smoking and coffee/tea consumption (kappas 0.70-1.00). The majority of environmental exposures, including use of pesticides, solvents and exposure to metal dusts and fumes, also showed high repeatability (kappas >0.78). A consecutive series of 163 PD case participants was recruited from a neurology clinic in Brisbane. One hundred and fifty-one (151) control participants were randomly selected from the Australian Commonwealth Electoral Roll and individually matched to the PD cases on age (± 2 years), sex and current residential suburb. Participants ranged in age from 40-89 years (mean age 67 years). Exposure data were collected in face-to-face interviews. Odds ratios and 95% confidence intervals were calculated using conditional logistic regression for matched sets in SAS version 9.1. Consistent with previous studies, ever having been a regular smoker or coffee drinker was inversely associated with PD with dose-response relationships evident for packyears smoked and number of cups of coffee drunk per day. Passive smoking from ever having lived with a smoker or worked in a smoky workplace was also inversely related to PD. Ever having been a regular tea drinker was associated with decreased odds of PD. Hobby gardening was inversely associated with PD. However, use of fungicides in the home garden or occupationally was associated with increased odds of PD. Exposure to welding fumes, cleaning solvents, or thinners occupationally was associated with increased odds of PD. Ever having resided in a rural or remote area was inversely associated with PD. Ever having resided on a farm was only associated with moderately increased odds of PD. Whilst the current study’s results suggest that environmental exposures on their own are only modest contributors to overall PD risk, the possibility that interaction with genetic factors may additively or synergistically increase risk should be considered. The results of this research support the theory that PD has a multifactorial aetiology and that environmental exposures are some of a number of factors to contribute to PD risk. There was also evidence of interaction between some factors (eg smoking and welding) to moderate PD risk.

Development of a physical and genetic map of the virulent Wolbachia strain wMelPop

We report here the construction of a physical and genetic map of the virulent Wolbachia strain, wMelPop. This map was determined by ordering 28 chromosome fragments that resulted from digestion with the restriction endonucleases FseI, ApaI, SmaI, and AscI and were resolved by pulsed-field gel electrophoresis. Southern hybridization was done with 53 Wolbachia-specific genes as probes in order to determine the relative positions of these restriction fragments and use them to serve as markers. Comparison of the resulting map with the whole genome sequence of the closely related benign Wolbachia strain, wMel, shows that the two genomes are largely conserved in gene organization with the exception of a single inversion in the chromosome.

Control of vector-borne disease by genetic manipulation of insect populations: technological requirements and research priorities

The possibility of controlling vector-borne disease through the development and release of transgenic insect vectors has recently gained popular support and is being actively pursued by a number of research laboratories around the world. Several technical problems must be solved before such a strategy could be implemented: genes encoding refractory traits (traits that render the insect unable to transmit the pathogen) must be identified, a transformation system for important vector species has to be developed, and a strategy to spread the refractory trait into natural vector populations must be designed. Recent advances in this field of research make it seem likely that this technology will be available in the near future. In this paper we review recent progress in this area as well as argue that care should be taken in selecting the most appropriate disease system with which to first attempt this form of intervention. Much attention is currently being given to the application of this technology to the control of malaria, transmitted by Anopheles gambiae in Africa. While malaria is undoubtedly the most important vector-borne disease in the world and its control should remain an important goal, we maintain that the complex epidemiology of malaria together with the intense transmission rates in Africa may make it unsuitable for the first application of this technology. Diseases such as African trypanosomiasis, transmitted by the tsetse fly, or unstable malaria in India may provide more appropriate initial targets to evaluate the potential of this form of intervention.

Population subdivision in marine environments: the contributions of biogeography, geographic distance, and discontinuous habitat to genetic differentiation in a blennioid

The relative importance of factors that may promote genetic differentiation in marine organisms is largely unknown. Here, contributions to population structure from biogeography, habitat distribution, and isolation by distance were investigated in Axoclinus nigricaudus, a small subtidal rock reef fish, throughout its range in the Gulf of California. A 408 basepair fragment of the mitochondrial control region was sequenced from 105 individuals. Variation was significantly partitioned between many pairs of populations. Phylogenetic analyses, hierarchical analyses of variance, and general linear models substantiated a major break between two putative biogeographic regions. This genetic discontinuity coincides with an abrupt change in ecological characteristics (including temperature and salinity) but does not coincide with known oceanographic circulation patterns. Geographic distance and the nature of habitat separating populations (continuous habitat along a shoreline, discontinuous habitat along a shoreline, and open water) also contributed to population structure in general linear model analyses. To verify that local populations are genetically stable over time, one population was resampled on four occasions over eighteen months; it showed no evidence of a temporal component to diversity. These results indicate that having a planktonic life stage does not preclude geographically partitioned genetic variation over relatively small geographic distances in marine environments. Moreover, levels of genetic differentiation among populations of Axoclinus nigricaudus cannot be explained by a single factor, but are due to the combined influences of a biogeographic boundary, habitat, and geographic distance.

The contribution of classical (beta(1/2)-) and atypical beta-adrenoceptors to the stimulation of human white adipocyte lipolysis and right atrial appendage contraction by novel beta(3)-adrenoceptor agonists of differing selectivities

The role of beta(3)- and other putative atypical beta-adrenaceptors in human white adipocytes and right atrial appendage has been investigated using CGP 12177 and novel phenylethanolamine and aryloxypropanolamine beta(3)-adrenoceptor (beta(3)AR) agonists with varying intrinsic activities and selectivities for human cloned PAR subtypes. The ability to demonstrate beta(1/2)AR antagonist-insensitive (beta(3) or other atypical beta AR-mediated) responses to CGP 12177 was critically dependent on the albumin batch used to prepare and incubate the adipocytes. Four aryloxypropanolamine selective beta(3)AR agonists (SB-226552, SB-229432, SB-236923, SB-246982) consistently elicited beta(1/2)AR antagonist-insensitive lipolysis. However, a phenylethanolamine (SB-220646) that was a selective full beta(3)AR agonist elicited full lipolytic and inotropic responses that were sensitive to beta(1/2)AR antagonism, despite it having very low efficacies at cloned beta(1)- and beta(2)ARs. A component of the response to another phenylethanolamine selective beta(3)AR agonist (SB-215691) was insensitive to beta(1/2)AR antagonism in some experiments. Because novel aryloxypropanolamine had a beta(1/2)AR antagonist-insensitive inotropic effect, these results establish more firmly that beta(3)ARs mediate lipolysis in human white adipocytes, and suggest that putative 'beta(4)ARs' mediate inotropic responses to CGP 12177. The results also illustrate the difficulty of predicting from studies on cloned beta ARs which beta ARs will mediate responses to agonists in tissues that have a high number of beta(1)- and beta(2)ARs or a low number of beta(3)ARs.

Analysis of small signal stability margins using genetic optimization

Power system small signal stability analysis aims to explore different small signal stability conditions and controls, namely: (1) exploring the power system security domains and boundaries in the space of power system parameters of interest, including load flow feasibility, saddle node and Hopf bifurcation ones; (2) finding the maximum and minimum damping conditions; and (3) determining control actions to provide and increase small signal stability. These problems are presented in this paper as different modifications of a general optimization to a minimum/maximum, depending on the initial guesses of variables and numerical methods used. In the considered problems, all the extreme points are of interest. Additionally, there are difficulties with finding the derivatives of the objective functions with respect to parameters. Numerical computations of derivatives in traditional optimization procedures are time consuming. In this paper, we propose a new black-box genetic optimization technique for comprehensive small signal stability analysis, which can effectively cope with highly nonlinear objective functions with multiple minima and maxima, and derivatives that can not be expressed analytically. The optimization result can then be used to provide such important information such as system optimal control decision making, assessment of the maximum network's transmission capacity, etc. (C) 1998 Elsevier Science S.A. All rights reserved.

Genetic structure and evolution of species in the mangrove genus Avicennia (Avicenniaceae) in the Indo-West Pacific

Allozyme variation in species of the mangrove genus Avicennia was screened in 25 populations collected from 22 locations in the Indo-West Pacific and eastern North America using 11 loci. Several fixed gene differences supported the specific status of Avicennia alba, A. integra, A. marina, and A. rumphiana from the Indo-West Pacific, and A. germinans from the Atlantic-East Pacific. The three varieties of A. marina, var. marina, var. eucalyptifolia, and var. australasica, had higher genetic similarities (Nei's I) and no fixed gene differences, confirming their conspecific status. Strong genetic structuring was observed in A. marina, with sharp changes in gene frequencies at the geographical margins of varietal distributions. The occurrence of alleles found otherwise in only one variety, in only immediately adjacent populations of another variety, provided evidence of introgession between varieties. The varieties appear to have diverged recently in the Pleistocene and are apparently not of ancient Cretaceous origin, as suggested earlier. Despite evidence of high degrees of outcrossing, gene flow among populations was relatively low (N(e)m less than or equal to 1-2), except where populations were geographically continuous, questioning assumptions that these widespread mangrove species achieve high levels of long-distance dispersal.