Subtropical drosophilids in Australia can be characterized by adult distribution across vegetation type and by height above forest floor

Understanding the pattern in which adult drosophilids of different species are distributed across and within different vegetation types is necessary for accurate interpretation of their local ecology and diversity. Such studies have been conducted mainly in temperate regions, and there is no basis for extrapolating their conclusions to tropical areas. This study describes the vertical distribution (0-20 m) of drosophilids attracted to banana baits in five different vegetation types in subtropical eastern Australia including open woodland, and rain-forest types. The distribution of most of the 15 common species could be characterized three-dimensionally by vegetation type and height above forest floor. Only one species, Scaptodrosophila lativittata, was common in all vegetation types and it was a canopy species in rain forests and a ground-level species in open woodland. Vertical distribution of some species clearly matched that of their larval hosts, but it did not in others. For example, the fungivore Leucophenga scutellata was mostly trapped well above the forest floor, yet it breeds at ground level, suggesting behavioural mode can influence vertical distributions. We conclude that the vertical dimension, although still poorly understood in relation to drosophilid habitats, needs to be taken into account when conducting and interpreting studies aimed at understanding drosophilid populations and communities in the subtropics.

Protein targeting to the plasma membrane of adult skeletal muscle fiber: An organized mosaic of functional domains

The plasma membrane of differentiated skeletal muscle fibers comprises the sarcolemma, the transverse (T) tubule network, and the neuromuscular and muscle-tendon junctions. We analyzed the organization of these domains in relation to defined surface markers, beta -dystroglycan, dystrophin, and caveolin-3, These markers were shown to exhibit highly organized arrays along the length of the fiber. Caveolin-3 and beta -dystroglycan/dystrophin showed distinct, but to some extent overlapping, labeling patterns and both markers left transverse tubule openings clear. This labeling pattern revealed microdomains over the entire plasma membrane with the exception of the neuromuscular and muscle-tendon junctions which formed distinct demarcated macrodomains. Our results suggest that the entire plasma membrane of mature muscle comprises a mosaic of T tubule domains together with sareolemmal caveolae and beta -dystroglycan domains. The domains identified with these markers were examined with respect to targeting of viral proteins and other expressed domain-specific markers, We found that each marker protein was targeted to distinct microdomains, The macrodomains were intensely labeled with all our markers. Replacing the cytoplasmic tail of the vesicular stomatitis virus glycoprotein with that of CD4 resulted in retargeting from one domain to another. The domain-specific protein distribution at the muscle cell surface may be generated by targeting pathways requiring specific sorting information but this trafficking is different from the conventional apical-basolateral division. (C) 2001 Academic Press.

Relationship of high energy expenditure and variation in dietary intake with reporting accuracy on 7 day food records and diet histories in a group of healthy adult volunteers

Objectives: To assess the accuracy of reporting from both a diet history and food record and identify some of the characteristics of more accurate reporters in a group of healthy adult volunteers for an energy balance study. Design: Prospective measurements in free-living people. Setting: Wollongong, Australia. Subjects: Fifteen healthy volunteers (seven male, eight female; aged 22 -59 y; body mass index (BMI) 19 - 33 kg/m(2)) from the local community in the city of Wollongong, Australia. Interventions: Measurement of energy intake via diet history interview and 7 day food records, total energy expenditure by the doubly labelled water technique over 14 days, physical activity by questionnaire, and body fat by dual-energy X-ray absorptiometry. Results: Increased misreporting of energy intake was associated with increased energy expenditure (r = 0.90, P < 0.0001, diet history; r(s)=0.79, P=0.0005, food records) but was not associated with age, sex, BMI or body fat. Range in number of recorded dinner foods correlated positively with energy expenditure (r(s)=0.63, P=0.01) and degree of misreporting (r(s)=0.71, P=0.003, diet history; r(s)=0.63, P=0.01, food records). Variation in energy intake at dinner and over the whole day identified by the food records correlated positively with energy expenditure (r=0.58, P = 0.02) and misreporting on the diet history (r=0.62, P=0.01). Conclusions: Subjects who are highly active or who have variable dietary and exercise behaviour may be less accurate in reporting dietary intake. Our findings indicate that it may be necessary to screen for these characteristics in studies where accuracy of reporting at an individual level is critical. Sponsorship: The study was supported in part by Australian Research Council funds made available through the University of Wollongong.

Genetic and environmental contributions to cannabis dependence in a national young adult twin sample

Background. This paper examines genetic and environmental contributions to risk of cannabis dependence. Method. Symptoms of cannabis dependence and measures of social, family and individual risk factors were assessed in a sample of 6265 young adult male and female Australian twins born 1964-1971. Results. Symptoms of cannabis dependence were common: 11(.)0% of sample (15(.)1% of men and 7(.)8% of women) reported two or more symptoms of dependence. Correlates of cannabis dependence included educational attainment, exposure to parental conflict, sexual abuse, major depression, social anxiety and childhood conduct disorder. However, even after control for the effects of these factors, there was evidence of significant genetic effects on risk of cannabis dependence. Standard genetic modelling indicated that 44(.)7% (95% CI = 15-72(.)2) of the variance in liability to cannabis dependence could be accounted for by genetic factors, 20(.)1% (95 CI = 0-43(.)6) could be attributed to shared environment factors and 35(.)3% (95% CI = 26(.)4-45(.)7) could be attributed to non-shared environmental factors. However, while there was no evidence of significant gender differences in the magnitude of genetic and environmental influences, a model which assumed both genetic and shared environmental influences on risks of cannabis dependence among men and shared environmental but no genetic influences among women provided an equally good fit to the data. Conclusions. There was consistent evidence that genetic risk factors are important determinants of risk of cannabis dependence among men. However, it remains uncertain whether there are genetic influences on liability to cannabis dependence among women.

The adult ventral nerve cord as a phylogenetic character in brachyceran Diptera

Insect ganglia are often composed of fused segmental units or neuromeres. We estimated the evolution of the ventral nerve cord (VNC) in higher Diptera by comparing the patterns of neuromere fusion among 33 families of the Brachycera. Variation within families is uncommon, and VNC architecture does not appear to be influenced by body shape. The outgroup pattern, seen in lower Diptera, is fusion of neuromeres belonging to thoracic segments 1 and 2 (T1 and T2), and fusion of neuromeres derived from T3 and abdominal segment 1 (A1). In the abdomen, neuromeres A7-10 are fused into the terminal abdominal ganglion (TAG). Increased neuromere fusion is a feature of the Brachycera. No brachyceran shows less fusion than the outgroups. We established six pattern elements; (1) fusion of T1 and T2, (2) fusion of T3 and A1, (3) fusion of the T1/T2 andT3/A1 ganglia, (4) increase in the number of neuromeres comprising the TAG, (5) anteriorward fusion of abdominal neuromeres, and (6) the complete fusion of thoracic and abdominal neuromeres into a synganglion. States 1 and 2 are present in the outgroup lower Diptera, and state 3 in the Xylophagomorpha, Stratiomyomorpha, Tabanomorpha and Cyclorrhapha. State 4 is a feature of all Eremoneura. State 5 is present in Cyclorrhapha only, and state 6, fusion into a synganglion, has evolved at least 4 times in the Eremoneura. Synapomorphies are provided for the Cyclorrhapha and Muscoidea, and a grouping of three basal brachyceran infraorders Xylophagomorpha, Stratiomyomorpha and Tabanomorpha. The patterns of fusion suggest that VNC architecture has evolved irreversibly, in accordance with Dollo's law.

Variation in coumarin 7-hydroxylase activity associated with genetic polymorphism of cytochrome P450 2A6 and the body status of iron stores in adult Thai males and females

The relationships between catalytic activity of cytochrome P450 2A6 (CYP2A6), polymorphism of CYP2A6 gene, gender and levels of body iron stores were analysed in a sample group of 202 apparently healthy Thais, aged 1947 years. Eleven individuals were found to have high activity of CYP2A6, judged by the relatively large amounts (11.2-14.6 mg) of 7-hydroyxcoumarin (7-OHC) excreted 3 h following administration of 15 mg of coumarin. Ten individuals, however, did not excrete any 7-OHC. Of these 10, four were found to have no CYP2A6 gene (whole gene deletion; CYP2A6*4 allele). The frequency of the CYP2A6 alleles; *1A, *1B and *4 in the whole sample group was 52, 40 and 8% while the frequency of the CYP2A6 gene types; *1A/* 1A, *1A/* 1B, *1B/* 1B, *1A/* 4, *1BI* 4, *4/* 4 was 29, 41, 16, 7, 5 and 2%. Subjects having CYP2A6* 1A/* 1B gene-type group were found to have higher rates of coumarin 7-hydroxylation compared with those of the CYP2A6* 1B/* 1B and CYP2A6* 1A/* 4 gene types. The inter-individual variability in CYP2A6 catalytic activity was therefore attributed in part to the CYP2A6 genetic polymorphism. Variation in CYP2A6 activity in this sample group was not associated with gender but, interestingly, it did show an inverse association with plasma ferritin; an indicator of body iron stores. Higher rates of coumarin 7-hydroxylation were found in individuals with low body iron stores (plasma ferritin < 20 μg/l) compared with subjects having normal body iron store status. Subjects (n = 16) with iron overload (plasma ferritin > 300 mug/l) also tended to have elevated rates of coumarin 7-hydroxylation. These results suggest an increased CYP2A6 expression in subjects who have excessive body iron stores. Further investigations into the underlying factors that may lead to increased expression of CYP2A6 in association with abnormal body iron stores are currently in progress in our laboratory. Pharmacogenetics 12:241-249 (C) 2002 Lippincott Williams Wilkins.

Surgical extraction of transplanted adult Dirofilaria immitis in cats

A jugular venotomy technique was developed to attempt extraction of Dirofilaria immitis in cats. Seven cats were first examined by cardiac ultrasound to establish the location of adult D. immitis that had been inserted by jugular venotomy. The efficiency of an extractor catheter in surgically removing filariae similarly inserted into 13 experimental cats was then assessed. A mean extraction success rate of 96% was achieved. This technique would seem to be worthy of clinical use provided the filariae are in the right atrial area.