Landscape structure influences tree density patterns in fragmented woodlands in semi-arid eastern Australia.

Landscape and local-scale influences are important drivers of plant community structure. However, their relative contribution and the degree to which they interact remain unclear. We quantified the extent to which landscape structure, within-patch habitat and their confounding effects determine post-clearing tree densities and composition in agricultural landscapes in eastern subtropical Australia. Landscape structure (incorporating habitat fragmentation and loss) and within-patch (site) features were quantified for 60 remnant patches of Eucalyptus populnea (Myrtaceae) woodland. Tree density and species for three ecological maturity classes (regeneration, early maturity, late maturity) and local site features were assessed in one 100 × 10 m plot per patch. All but one landscape characteristic was determined within a 1.3-km radius of plots; Euclidean nearest neighbour distance was measured inside a 5-km radius. Variation in tree density and composition for each maturity class was partitioned into independent landscape, independent site and joint effects of landscape and site features using redundancy analysis. Independent site effects explained more variation in regeneration density and composition than pure landscape effects; significant predictors were the proportion of early and late maturity trees at a site, rainfall and the associated interaction. Conversely, landscape structure explained greater variation in early and late maturity tree density and composition than site predictors. Area of remnant native vegetation within a landscape and patch characteristics (area, shape, edge contrast) were significant predictors of early maturity tree density. However, 31% of the explained variation in early mature tree differences represented confounding influences of landscape and local variables. We suggest that within-patch characteristics are important in influencing semi-arid woodland tree regeneration. However, independent and confounding effects of landscape structure resulting from previous vegetation clearing may have exerted a greater historical influence on older cohorts and should be accounted for when examining woodland dynamics across a broader range of environments.

The stock structure of grey mackerel Scomberomorus semifasciatus in Australia as inferred from its parasite fauna

The scombrid Scomberomorus semifasciatus is an important component of inshore fisheries in tropical Australia. Data on the parasite fauna of 593 fish from areas off northern and eastern Australia were examined for evidence of discrete fish populations. The parasites used were juveniles of Pterobothrium pearsoni, Callitetrarhynchus gracilis, Anisakis simplex (sensu latu) and Terranova sp. Tukey Kramer pairwise comparisons gave significant differences in the abundances of two or more parasites between fish from the east coast, the eastern Gulf of Carpentaria and the remainder of northern Australia. Multivariate analysis gave further evidence of differences and the results suggest that at least 4 populations or stocks of grey mackerel occur along the northern and eastern coastline of Australia.

Population structure of South African and Australian Pyrenophora teres isolates.

There are two recognized forms of the disease net blotch of barley: the net form caused by Pyrenophora teres f. teres (PTT) and the spot form caused by P. teres f. maculata (PTM). In this study, amplified fragment length polymorphism analysis was used to investigate the genetic diversity and population structure of 60 PTT and 64 PTM isolates collected across Australia (66 isolates) and in the south-western Cape of South Africa (58 isolates). For comparison, P. tritici-repentis, Exserohilum rostratum and Bipolaris sorokiniana samples were also included in the analyses. Both distance-and model-based cluster analyses separated the PTT and PTM isolates into two strongly divergent genetic groups. Significant variation was observed both among the South African and Australian populations of PTT and PTM and among sampling locations for the PTT samples. Results suggest that sexual reproduction between the two forms is unlikely and that reproduction within the PTT and PTM groups occurs mainly asexually.

Biophysical Characterization of Oxidized Phospholipids : Implications for Altered Membrane Structure and Function

The present study aims to elucidate the modifications in the structure and functionality of the phospholipid matrix of biological membranes brought about by free radical-mediated oxidative damage of its molecular constituents. To this end, the surface properties of two oxidatively modified phospholipids bearing an aldehyde or carboxyl function at the end of truncated sn-2 acyl chain were studied using a Langmuir balance. The results obtained reveal both oxidized species to have a significant impact on the structural dynamics of phospholipid monolayers, as illustrated by the progressive changes in force-area isotherms with increasing mole fraction of the oxidized lipid component. Moreover, surface potential measurements revealed considerable modifications in the electric properties of oxidized phospholipid containing monolayers during film compression, suggesting a packing state-controlled reorientation of the intramolecular electric dipoles of the lipid headgroups and acyl chains. Based on the above findings, a model describing the conformational state of oxidized phospholipid molecules in biological membranes is proposed, involving the protrusion of the acyl chains bearing the polar functional groups out from the hydrocarbon phase to the surrounding aqueous medium. Oxidative modifications alter profoundly the physicochemical properties of unsaturated phospholipids and are therefore readily anticipated to have important implications for their interactions with membrane-associating molecules. Along these lines, the carboxyl group bearing lipid was observed to bind avidly the peripheral membrane protein cytochrome c. The binding was reversed following increase in ionic strength or addition of polyanionic ATP, thus suggesting it to be driven by electrostatic interactions between cationic residues of the protein and the deprotonated lipid carboxyl exposed to the aqueous phase. The presence of aldehyde function bearing oxidized phospholipid was observed to enhance the intercalation of four antimicrobial peptides into phospholipid monolayers and liposomal bilayers. Partitioning of the peptides to monolayers was markedly attenuated by the aldehyde scavenger methoxyamine, revealing it to be mediated by the carbonyl moiety possibly through efficient hydrogen bonding or, alternatively, formation of covalent adduct in form of a Schiff base between the lipid aldehydes and primary amine groups of the peptide molecules. Lastly, both oxidized phospholipid species were observed to bind with high affinity three small membrane-partitioning therapeutic agents, viz. chlorpromazine, haloperidol, and doxorubicin. In conclusion, the results of studies conducted using biomimetic model systems support the notion that oxidative damage influences the molecular architecture as well as the bulk physicochemical properties of phospholipid membranes. Further, common polar functional groups carried by phospholipids subjected to oxidation were observed to act as molecular binding sites at the lipid-water interface. It is thus plausible that oxidized phospholipid species may elicit cellular level effects by modulating integration of various membrane-embedded and surface-associated proteins and peptides, whose conformational state, oligomerization, and functionality is known to be controlled by highly specific lipid-protein interactions and proper physical state of the membrane environment.

Temporal genetic structure patterns in tropical maize populations under reciprocal recurrent selection.

In order to investigate the effect of long term recurrent selection on the pattern of gene diversity, thirty randomly-selected individuals from the progenitors (p) and four selection cycles (C0, C3, C6 and C11) were sampled for DNA analysis from the tropical maize (Zea mays L.) breeding populations, Atherton 1 (AT1) and Atherton 2 (AT2). Fifteen polymorphic Simple Sequence Repeat markers amplified a total of 284 and 257 alleles in AT1 and AT2 populations, respectively. Reductions in the number of alleles were observed at advanced selection cycles. About 11 and 12% of the alleles in AT1 and AT2 populations respectively, were near to fixation. However, a higher number of alleles (37% in AT1 and 33% in AT2) were close to extinction. Fisher's exact test and analysis of molecular variance (AMOVA) showed significant population differentiations. Gene diversity estimates and AMOVA revealed increased genetic differentiations at the expense of loss of heterozygosity. Population differentiations were mainly due to fixation of complementary alleles at a locus in the two breeding populations. The estimates of effective population at an advanced selection cycle were close to the population size predicted by the breeding method.

Population structure, effective population size and adverse effects of stocking in the endangered Australian eastern freshwater cod Maccullochella ikei

Microsatellite markers were used to examine spatio-temporal genetic variation in the endangered eastern freshwater cod Maccullochella ikei in the Clarence River system, eastern Australia. High levels of population structure were detected. A model-based clustering analysis of multilocus genotypes identified four populations that were highly differentiated by F-statistics (FST = 0· 09 − 0· 49; P < 0· 05), suggesting fragmentation and restricted dispersal particularly among upstream sites. Hatchery breeding programmes were used to re-establish locally extirpated populations and to supplement remnant populations. Bayesian and frequency-based analyses of hatchery fingerling samples provided evidence for population admixture in the hatchery, with the majority of parental stock sourced from distinct upstream sites. Comparison between historical and contemporary wild-caught samples showed a significant loss of heterozygosity (21%) and allelic richness (24%) in the Mann and Nymboida Rivers since the commencement of stocking. Fragmentation may have been a causative factor; however, temporal shifts in allele frequencies suggest swamping with hatchery-produced M. ikei has contributed to the genetic decline in the largest wild population. This study demonstrates the importance of using information on genetic variation and population structure in the management of breeding and stocking programmes, particularly for threatened species.

Evidence for extensive population structure in the white-spotted eagle ray within the Indo-Pacific inferred from mitochondrial gene sequences

The white-spotted eagle ray Aetobatus narinari is a species complex that occurs circumglobally throughout warm-temperate waters. Aetobatus narinari is semi-pelagic and large (up to 300 cm disc width), suggesting high dispersal capabilities and gene flow on a wide spatial scale. Sequence data from two mitochondrial genes, cytochrome b (cytb) and NADH dehydrogenase subunit 4 (ND4), were used to determine the genetic variability within and among 18 sampling locations in the central Indo-Pacific biogeographical region. Populations in the Indo-Pacific were highly genetically structured with c. 70% of the total genetic variation found among three geographical regions (East China Sea, Southeast Asia and Australia). FST was 0.64 for cytb and 0.53 for ND4, with φST values being even larger, that is, 0.78 for cytb and 0.65 for ND4. This high-level genetic partitioning provides strong evidence against extensive gene flow in A. narinari. The degree of genetic population structuring in the Indo-Pacific was similar to that found on a global scale. Global FST was 0.63 for cytb and 0.57 for ND4, and global φST values were 0.94 for cytb and 0.82 for ND4. This suggests that the A. narinari complex may be more speciose than the two or three species proposed to date. Further sampling and genetic analyses are likely to uncover the ‘evolutionarily significant’ and ‘management’ units that are critical to determine the susceptibilities of individual populations to regional fishing pressures and to provide advice on management options. Network analyses showed a close genetic relationship between haplotypes from the central Indo-Pacific and South Africa, providing support for a proposed dispersal pathway from the possible centre of origin of the A. narinari species complex in the Indo-Pacific into the Atlantic Ocean.

Population genetic structure and genetic diversity of three critically endangered Pristis sawfishes in Australian waters.

Northern Australia is considered to be one of the last strongholds for three critically endangered sawfishes, Pristis zijsron, Pristis clavata, and Pristis microdon, making these populations of global significance. Population structure and levels of genetic diversity were assessed for each species across northern Australia using a portion of the mitochondrial control region. Statistically significant genetic structure was detected in all three species, although it was higher in P. microdon (F-ST = 0.811; N = 149) than in either P. clavata (F-ST = 0.419; N = 73) or P. zijsron (F-ST = 0.202; N = 49), possibly due to a much higher and/or localized level of female philopatry in P. microdon. The overall levels of haplotype diversity in P. zijsron (h = 0.555), P. clavata (h = 0.489), and P. microdon (h = 0.650) were moderate, although it appears to be reduced in the assemblages of P. zijsron and P. clavata in the Gulf of Carpentaria (h = 0.342 and h = 0.083, respectively). Since female migration (replenishment) between regions is unlikely, conservation plans should strive to maintain current levels of diversity and abundances in the regional assemblages of each species.

Stock structure of exploited shark species in north-eastern Australia

The project has provided management and other stakeholders with information necessary to make informed decisions about the management of four of the key exploited shark species caught in the Queensland inshore net fishery and northern New South Wales line fishery. The project has determined that spatial management of milk sharks within Queensland, and scalloped hammerhead, common black tip and Australian black tip sharks within Queensland and New South Wales is appropriate. The project has determined that both black tip shark species are likely to require co-operative management arrangements between Queensland and New South Wales. For scalloped hammerheads separate stocks between the two jurisdictions were identified from the fisheriesdependent samples, however genetic exchange across borders is likely to be facilitated by movement of adult females and perhaps larger males to a lesser extent. This information will greatly assist compliance with the Commonwealth Environment Protection and Biodiversity Conservation Act (1999) for shark fisheries in north-eastern Australia by providing the necessary basis for robust assessment of the status of stocks of the study species, thereby helping to deliver their sustainable harvest. It also helps to achieve objectives of the Australian National Shark Plan. The project provides the appropriate spatial framework for future monitoring and assessment of the study species. This is at a time when shark fisheries are receiving close attention from all sectors and when monitoring programs are being implemented, aimed at better assessment of stock status. This project has provided the crucial information for developing an appropriate monitoring design as well as the necessary basis for making statements about stock status. The project has addressed research priorities identified by the Queensland Fisheries Research Advisory Board, Great Barrier Reef Marine Park Authority and Queensland Fisheries. Previously management has assumed a single stock for each species on the east coast of Queensland, and management of shark fisheries in New South Wales (NSW) and Queensland has been independent of one another. The project has been able to enhance and develop links between research, management and industry. Strong positive relationships with commercial fishers were crucial in the collection of samples throughout the study area and fisheries managers were part of the project team throughout the study period. During the project the study area was extended to include both Queensland and NSW waters, creating mutualistic and positive links between the States’ research and management agencies. Extension of project results included management representatives from NSW and Queensland, as well as the Northern Territory where similar shark fisheries operate and similar species are targeted. The project was able to provide significant human capital development opportunities providing considerable value to the project outcomes. Use of vertebral microchemistry and life history characteristics as stock determination methods provided material for two PhD students based at James Cook University: Ron Schroeder, vertebral chemistry; and Alastair Harry, life history characteristic. The project has developed novel research methods that have great capacity for future application, including: • Development of a simple and rapid genetic diagnostic tool (RT-HRM-PCR assay) for differentiating among the black tip shark species, for which no simple morphological identifier exists; and • Development of laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) methods for analysing and interpreting microchemical composition of shark vertebrae. The study has provided further confirmation of the effectiveness of using a holistic approach in stock structure studies and justifies investment into such studies.

Structure of (6S,13bR)-1,2,3,5,6,13b-hexahydro-6-isopropyl-8H-pyrrolo[1',2':1,2]pyrazino[3,4,-b]quinazoline-5,8-dione

C17H19N302, monoclinic, P21, a = 5.382 (1), b = 17.534(4), c = 8.198(1)/L ,8 = 100.46(1) °, Z= 2, d,, = 1.323, dc= 1.299 Mg m-3, F(000) = 316, /~(Cu .Ka) = 0.618 mm -1. R = 0.052 for 1284 significant reflections. The proline-containing cispeptide unit which forms part of a six-membered ring deviates from perfect planarity. The torsion angle about the peptide bond is 3.0 (5) ° and the peptide bond length is 1.313 (5)A. The conformation of the proline ring is Cs-Cf~-endo. The crystal structure is stabilized by C-H... O interactions.

Properties of intramuscular connective tissue in pork and poultry with reference to weakening of structure

The most common connective tissue research in meat science has been conducted on the properties of intramuscular connective tissue (IMCT) in connection with eating quality of meat. From the chemical and physical properties of meat, researchers have concluded that meat from animals younger than physiological maturity is the most tender. In pork and poultry, different challenges have been raised: the structure of cooked meat has weakened. In extreme cases raw porcine M. semimembranosus (SM) and in most turkey M. pectoralis superficialis (PS) can be peeled off in strips along the perimysium which surrounds the muscle fibre bundles (destructured meat), and when cooked, the slices disintegrate. Raw chicken meat is generally very soft and when cooked, it can even be mushy. The overall aim of this thesis was to study the thermal properties of IMCT in porcine SM in order to see if these properties were in association with destructured meat in pork and to characterise IMCT in poultry PS. First a 'baseline' study to characterise the thermal stability of IMCT in light coloured (SM and M. longissimus dorsi in pigs and PS in poultry) and dark coloured (M. infraspinatus in pigs and a combination of M. quadriceps femoris and M. iliotibialis lateralis in poultry) muscles was necessary. Thereafter, it was investigated whether the properties of muscle fibres differed in destructured and normal porcine muscles. Collagen content and also solubility of dark coloured muscles were higher than in light coloured muscles in pork and poultry. Collagen solubility was especially high in chicken muscles, approx. 30 %, in comparison to porcine and turkey muscles. However, collagen content and solubility were similar in destructured and normal porcine SM muscles. Thermal shrinkage of IMCT occurred at approximately 65 °C in pork and poultry. It occurred at lower temperature in light coloured muscles than in dark coloured muscles, although the difference was not always significant. The onset and peak temperatures of thermal shrinkage of IMCT were lower in destructured than in normal SM muscles, when the IMCT from SM muscles exhibiting ten lowest and ten highest ultimate pH values were investigated (onset: 59.4 °C vs. 60.7 °C, peak: 64.9 °C vs. 65.7 °C). As the destructured meat was paler than normal meat, the PSE (pale, soft, exudative) phenomenon could not be ruled out. The muscle fibre cross sectional area (CSA), the number of capillaries per muscle fibre CSA and per fibre and sarcomere length were similar in destructured and normal SM muscles. Drip loss was clearly higher in destructured than in normal SM muscles. In conclusion, collagen content and solubility and thermal shrinkage temperature vary between porcine and poultry muscles. One feature in the IMCT could not be directly associated with weakening of the meat structure. Poultry breast meat is very homogenous within the species.

Solvent effects on the structure of N-methylpyrrole as studied by nmr in nematic solvents

The proton NMR spectra of N-methylpyrrole oriented in the nematic phases of liquid crystals with positive and negative diamagnetic anisotropies and their mixtures are reported. Geometrical parameters derived from the spectra at the critical point in the mixture of liquid crystals with positive and negative diamagnetic anisotropies, where macroscopic diamagnetic anisotropy vanishes, are similar to those obtained in the solvent with negative diamagnetic anisotropy. However, significant distortions in the molecular structure attributed to solvent effects have been observed in liquid crystals with positive diamagnetic anisotropy. The minimum energy conformation has one C---H of the methyl perpendicular to the ring.

Study of the structure and function of the sheath of tropically adapted bulls and risk factors for preputial eversion and preputial prolapse

Preputial prolapse is an obvious condition affecting bulls from many breeds. Unfortunately, the losses in production and welfare concerns associated with preputial prolapse can remain undetected for long periods of time in the extensive beef areas of northern Australia where the bulls are not inspected regularly. Thus, there is a critical need to identify the structural factors predisposing to preputial prolapse in young bulls so that they can be culled early. Despite there being no firm scientific evidence of an association between preputial eversion and preputial prolapse, it seems logical that the increased exposure of the sensitive prepuce as a consequence of preputial eversion may increase the risk of bulls developing preputial pathology, in particular preputial prolapse. This may be particularly relevant in Bos indicus bulls as they have a more pendulous sheath and thus eversion of the prepuce may be associated with a greater risk of injury to the prepuce compared to that in Bos taurus bulls. Further, studies of preputial eversion in Bos taurus bulls have concluded that there is an association between polledness and increased prevalence and severity (length of everted prepuce and duration of eversion) of preputial eversion due primarily to the absence or poor development of the caudal preputial muscles. No similar definitive work in Bos indicus bulls has been conducted and thus anatomical studies reported in this thesis were conducted to determine if a similar association occurred in Bos indicus bulls. A survey of a sample of large beef breeding herds in northern Australia found that preputial prolapse is a significant problem in Bos indicus and Bos indicus derived bulls and affected both young and older bulls. The importance of preputial prolapse confirmed the value of further research into the causes of this problem. A series of anatomical studies confirmed that preputial eversion in Bos indicus derived bulls was not more prevalent in polled bulls than horned bulls and was not associated with deficiency of the caudal preputial muscles as was established in Bos taurus bulls. An anatomical study of Bos indicus derived bulls with preputial prolapse found that preputial prolapse occurred in horned bulls of varying ages and these bulls did not have any evidence of deficiency in the caudal preputial muscles. However, preputial prolapse was observed in young polled bulls that had poorly developed or absent caudal preputial muscles. It was concluded that deficiency of the caudal preputial muscles in polled Bos indicus derived bulls may predispose to preputial prolapse at an early age, but no predisposing anatomical factors were found for horned Bos indicus derived bulls. In these studies, preputial eversion and preputial prolapse were found in horned Bos indicus derived bulls that did not have any preputial muscle deficiency and it was noted that preputial eversion was not related to the length of the prepuce. Further studies confirmed that preputial eversion was linearly and consistently associated with position of the glans penis within the sheath in Bos indicus derived bulls, and movement of the glans penis towards the preputial orifice consistently resulted in preputial eversion in these bulls. A method to objectively measure the relationship between movement of the glans penis within the sheath and preputial eversion was developed. Studies in humans have linked function of some abdominal muscles to function of the pelvic organs. This relationship was investigated in Bos indicus derived bulls to determine whether the function of specific abdominal muscles affected position of the penis in the sheath. Using the method developed to objectively measure the relationship between penis movement and preputial eversion, the abdominal muscles that potentially were associated with movement of the glans penis or preputial eversion were examined but no significant relationships were observed. In the anatomical study of Bos indicus derived bulls not affected with preputial prolapse a more pendulous sheath was associated with increased prevalence of preputial eversion. This relationship was confirmed for horned and polled bulls in the penis movement studies. Bos indicus derived bulls with more pendulous sheaths evert their prepuces more than bulls with less pendulous sheaths thus increasing the risk of damage to the prepuce either from the environment, other bulls, or from them inadvertently stepping on the everted prepuce when they get to their feet. Culling Bos indicus derived bulls with more pendulous sheaths should reduce the incidence of preputial eversion and possibly preputial prolapse. The anatomical study of Bos indicus derived bulls that did not have preputial prolapse demonstrates that there are herds of bulls where the polled bulls do not have any evidence of deficiency of the caudal preputial iv muscles. There is a need to develop a practical and cost effective test to identify polled Bos indicus bulls that have a deficiency in their caudal preputial muscles.

Variation in leaf structure of the invasive Madeira vine (Anredera cordifolia, Basellaceae) at different light levels

Madeira vine (Anredera cordifolia (Ten.) Steenis) is a climber in the angiosperm family Basellaceae. It is native to South America and has naturalised in Australia. It is regarded as a serious environmental weed because of the structural damage it causes to native vegetation. The present study, for the first time, documents anatomical and morphological traits of the leaves of A. cordifolia and considers their implications for its ecology and physiology. Plants were grown under three different light levels, and anatomical and morphological leaf characters were compared among light levels, among cohorts, and with documented traits of the related species, Basella alba L. Stomata were present on both the adaxial and abaxial sides of the leaf, with significantly more stomata on the abaxial side and under high light. This may account for the ability of this species to fix large amounts of carbon and rapidly respond to light gaps. The leaves had very narrow veins and no sclerenchyma, suggesting a low construction cost that is associated with invasive plants. There was no significant difference in any of the traits among different cohorts, which agrees with the claim that A. cordifolia primarily propagates vegetatively. The anatomy and morphology of A. cordifolia was similar to that of B. alba.

Structure and conformation of an anti-depressant drug, nitroxazepine hydrochloride monohydrate

CIsH20N3Oa+.C1-.H2 O, M r = 395, orthorhombic, Pn21a, a = 7.710 (4), b = 11.455 (3), c -- 21.199 (3)/k, Z = 4, V = 1872.4/k 3, D m = 1.38, D C = 1.403 g cm -3, F(000) = 832, g(Cu Kct) = 20.94 cm -l. Intensities for 1641 reflections were measured on a Nonius CAD-4 diffractometer; of these, 1470 were significant. The structure was solved by direct methods and refined to an R index of 0.045 using a blockdiagonal least-squares procedure. The angle between the least-squares planes through the benzene rings is 125.0 (5) ° and the side chain is folded similarly to one of the independent molecules of imipramine hydrochloride.