1,128 research outputs found
Phylogenetic position of hoop pine (Araucaria cunninghamii)
A variety of gymnosperms (13 species of conifer from 5 families and 2 species of non-conifer) were collected and the small ribosomal subunit (18s rRNA) was sequenced by direct sequencing. Fifteen species were examined in the study, which included widely separated provenances of Araucaria cunninghamii, to determine the phylogenetic relationship of these gymnosperms. Two of the four conifer families found in Australia that were included in the study (Araucariaceae and Podocarpaceae) separated as expected with further separation of genera and species within these families. Homologies between the gymnosperms varied from 89% to 98%. Four geographically distinct groups within A. cunninghamii were separated phylogenetically. This study suggests that A. cunninghamii was the most recent Araucaria species to evolve, with the Papua New Guinean provenances undergoing the fastest evolutionary changes. This type of analysis has provided molecular evidence to support the taxonomy of the Coniferales. It has shown, contrary to an established understanding in angiosperms, that sequence information of the 18S rRNA genes provides a useful means of studying phylogeny in the gymnosperms at the species and within-species levels
Organic carbon compounds associated with deep soil carbon stores
Aims
Organic carbon has been reported in deep regolithic profiles to depths of tens of metres, but the composition of the carbon compounds is unknown.
Methods
Residual carbon in the form of non-volatile low molecular weight compounds (LMWC) was characterised in three deep soil profiles to a depth of 19 m under farmland in south-western Australia following extraction with ethyl acetate and analysis by GC/MS. Pyrolysis and off-line thermochemolysis were used to characterise macromolecular organic carbon (MOC) to a depth of 29 m at a fourth site.
Results
Three compound classes occurred across the three different field locations: (1) terpenes, (2) fatty acids, amides and alcohols, and (3) plant steroids; indicating the influence of input of the past and present vegetation. Compounds related to fatty acids were the predominant residual carbon species in deep soils, and may be derived from plants and microorganisms. Biomarkers such as lignin, polysaccharides, proteins and terpenes at 0–0.1 m implied influences of vegetation, fire events and microorganisms. Pyrolysis found that polysaccharides were distributed mainly from 0 to 0.1 m, while aromatic compounds were consistently detected down to 29 m.
Conclusions
Carbon was stabilised in the form of aromatic compounds in deep soil, whereas other carbon sources such as cellulose, chitin, and N-containing compounds were confined to the surface soil. LMWC (Z)-docos-13-enamide and bis(6-methylheptyl) phthalate, were the main components throughout the soil profiles representing 53–81% of the LMWC, and were a greater proportion of the organic matter at depths of 18–19 m
Fast resolution of identification problems in seed production and plant breeding using molecular markers
Polymerase chain reaction (PCR) analysis with specific and arbitrary primers was used to identify germplasm from a barley breeding program. Through practical application of the technology, an F1 plant's identity was confirmed, the correct pedigrees of incorrectly labelled F2 populations were determined, confusion in the identity of seed lots of an advanced breeding line was resolved and off-type barley plants were identified in a seed increase block. This illustrated the value of PCR-based genotype analysis in plant breeding programs
Carotid arterial remodeling - A maladaptive phenomenon in type 2 diabetes but not in impaired glucose metabolism: The Hoorn Study
Background and Purpose-Deteriorating glucose tolerance is associated with an increased cardiovascular disease (CVD) risk. The underlying mechanisms remain unclear. Arterial remodeling is the change in structural properties through time in response to atherogenic and/or hemodynamic alterations and aims to maintain circumferential wall stress constant (
Mild renal insufficiency is associated with increased cardiovascular mortality: The Hoorn Study
Random walks on finite lattice tubes
Exact results are obtained for random walks on finite lattice tubes with a
single source and absorbing lattice sites at the ends. Explicit formulae are
derived for the absorption probabilities at the ends and for the expectations
that a random walk will visit a particular lattice site before being absorbed.
Results are obtained for lattice tubes of arbitrary size and each of the
regular lattice types; square, triangular and honeycomb. The results include an
adjustable parameter to model the effects of strain, such as surface curvature,
on the surface diffusion. Results for the triangular lattice tubes and the
honeycomb lattice tubes model diffusion of adatoms on single walled zig-zag
carbon nano-tubes with open ends.Comment: 22 pages, 4 figure
International, collaborative assessment of 146 000 prenatal karyotypes: expected limitations if only chromosome-specific probes and fluorescent in-situ hybridization are used
The development of chromosome-specific probes (CSP) and fluorescent in-situ hybridization (FISH) has allowed for very rapid identification of selected numerical abnormalities. We attempt here to determine, in principle, what percentage of abnormalities would be detectable if only CSP-FISH were performed without karyotype for prenatal diagnosis. A total of 146 128 consecutive karyotypes for prenatal diagnosis from eight centres in four countries for 5 years were compared with predicted detection if probes for chromosomes 13, 18, 21, X and Y were used, and assuming 100% detection efficiency. A total of 4163 abnormalities (2.85%) were found including 2889 (69.4%) (trisomy 21, trisomy 18, trisomy 13, numerical sex chromosome abnormalities, and triploidies) which were considered detectable by FISH. Of these, 1274 were mosaics, translocations, deletions, inversions, rings, and markers which would not be considered detectable. CSP-FISH is a useful adjunct to karyotype for high risk situations, and may be appropriate in low risk screening, but should not be seen as a replacement for karyotype as too many structural chromosome abnormalities will be misse
Deteriorating glucose tolerance status is associated with left ventricular dysfunction - the Hoorn Study
Background: Type 2 diabetes (DM2) is associated with a greater risk of heart failure. The mechanisms underlying this association remain controversial and include diabetes-associated hypertension and obesity, impaired small and large artery function, and a distinct metabolic cardiomyopathy related to hyperglycaemia/hyperinsulinaemia. The proximate causes of heart failure are left ventricular (LV) systolic dysfunction (SDF) and diastolic dysfunction (DDF). We investigated, in a population-based cohort (n=746), the association between glucose tolerance status and SDF and DDF. Methods and results: The study population consisted of 274 individuals with normal glucose metabolism (NGM), 174 with impaired glucose metabolism (IGM) and 298 with DM2 (mean age 68.5 years). All participants underwent an LV echocardiogram. SDF was defined as ejection fraction <55%. DDF was determined by a sum score of peak A velocity (abnormal, ≥97 cm/s), the difference between Apv and Amv duration (≥41 ms), and left atrial volume (≥57 ml), where cut-off values were based upon the 90th percentile in NGM. In addition, we analysed the ratio of early to late diastolic filling (E/A ratio) on a continuous scale using linear regression analyses. The age- and sex-standardised prevalences in NGM, IGM and DM2 were 13, 14 and 30% for SDF, and 26, 36 and 47% for DDF (P(trend) for both <0.001). After adjustment for sex, age, hypertension, body mass index, prior cardiovascular disease and (micro) albuminuria, DM2 was significantly associated with both SDF (odds ratio (95% CI) 2.04 (1.24 to 3.36)) and DDF (2.42 (1.63 to 3.60)) (90th percentile definition). This was also true for the analyses with the E/A ratio on a continuous scale (regression coefficient β (95% CI) -0.05 (-0.09 to -0.01). After adjustment for sex, age, hypertension, body mass index, prior cardiovascular disease and (micro) albuminuria IGM was not significantly associated with SDF (odds ratio (95% CI) 1.04 (0.58 to 1.88)) or DDF (1.33 (0.86 to 2.06)) using the definition based upon the 90th percentile. However, IGM was significantly associated with DDF if the E/A ratio was analysed on a continuous scale (regression coefficient β (95% CI) -0.05 (-0.10 to -0.01). Additional adjustment for brachial artery flow-mediated vasodilation or arterial stiffness, as measures of large artery function, did not materially alter the results. Hyperglycaemia and hyperinsulinaemia together explained ∼30% of the association of DM2 with SDF and ∼40% of that with DDF. Conclusion: DM2 is independently associated with a 2.0-fold greater risk of SDF and a 2.4-fold greater risk of DDF. IGM was not associated with SDF, and the association with DDF was limited to the E/A ratio. These observations may therefore explain the increased risk of systolic and diastolic heart failure in elderly individuals with DM2
Arterial stiffness increases with deteriorating glucose tolerance status - The Hoorn Study
Background - Type 2 diabetes (DM-2) and impaired glucose metabolism (IGM) are associated with an increased cardiovascular disease risk. In nondiabetic individuals, increased arterial stiffness is an important cause of cardiovascular disease. Associations between DM-2 and IGM and arterial stiffness have not been systematically investigated. Methods and Results - In a population-based cohort (n=747; 278 with normal glucose metabolism, 168 with IGM, and 301 with DM-2; mean age, 68.5 years), arterial stiffness was ultrasonically estimated by distensibility and compliance of the carotid, femoral, and brachial arteries and by the carotid elastic modulus. After adjustment for age, sex, and mean arterial pressure, DM-2 was associated with increased carotid, femoral, and brachial stiffness, whereas IGM was associated only with increased femoral and brachial stiffness. Carotid but not femoral or brachial stiffness increased from IGM to DM-2. Standardized βs (95% CI) for IGM and DM-2, compared with normal glucose metabolism, were -0.06 (-0.23 to 0.10) and -0.37 (-0.51 to -0.23) for carotid distensibility; -0.02 (-0.18 to 0.18) and -0.25 (-0.40 to -0.09) for carotid compliance; -0.05 (-0.23 to 0.13) and 0.25 (0.10 to 0.40) for carotid elastic modulus; -0.70 (-0.89 to -0.51) and -0.67 (-0.83 to -0.52) for femoral distensibility; and -0.62 (-0.80 to -0.44) and -0.79 (-0.94 to -0.63) for femoral compliance. The brachial artery followed a pattern similar to that of the femoral artery. Increases in stiffness indices were explained by decreases in distension, increases in pulse pressure, an increase in carotid intima-media thickness, and, for the femoral artery, a decrease in diameter. Hyperglycemia or hyperinsulinemia explained only 30% of the arterial changes associated with glucose tolerance. Adjustment for conventional cardiovascular risk factors did not affect these findings. Conclusions - IGM and DM-2 are associated with increased arterial stiffness. An important part of the increased stiffness occurs before the onset of DM-2 and is explained neither by conventional cardiovascular risk factors nor by hyperglycemia or hyperinsulinemia
Increased central artery stiffness in impaired glucose metabolism and type 2 diabetes - The Hoorn study
Impaired glucose metabolism (IGM) and type 2 diabetes (DM-2) are associated with high cardiovascular disease risk. Increases in peripheral and central artery stiffness may represent pathophysiologic pathways through which glucose tolerance status leads to cardiovascular disease. Peripheral artery stiffness increases with deteriorating glucose tolerance status, whereas this trend remains unclear for central artery stiffness. Therefore, we investigated the associations between glucose tolerance status and estimates of central arterial stiffness. We performed a population-based study of 619 individuals (normal glucose metabolism, n=261; IGM, n=170; and DM-2, n=188) and assessed central artery stiffness by measuring total systemic arterial compliance, aortic pressure augmentation index, and carotid-femoral transit time. After adjustment for sex, age, heart rate, height, body mass index, and mean arterial pressure, DM-2 was associated with decreased total systemic arterial compliance, increased aortic augmentation index, and decreased carotid-femoral transit time. IGM was borderline significantly associated with decreased total systemic arterial compliance. Respective regression coefficients (95% confidence intervals) for IGM and DM-2 compared with normal glucose metabolism were -0.05 (-0.11 to 0.01) and -0.13 (-0.19 to -0.07) mL/mm Hg for total system carterial compliance; 1.1 (-0.2 to 2.5) and 1.6 (0.2 to 3.0) percentage points for aortic augmentation index; and -0.85 (-5.20 to 3.49) and -4.95 (-9.41 to -0.48) ms for carotid-femoral transit time. IGM and DM-2 are associated with increased central artery stiffness, which is more pronounced in DM-2. Deteriorating glucose tolerance is associated with increased central and peripheral arterial stiffness, which may partly explain why both DM-2 and IGM are associated with increased cardiovascular risk
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