Showing papers by "University of Adelaide published in 1992"

Polycystic Ovary Syndrome

Abstract: Polycystic ovary syndrome is a heterogeneous endocrine disorder that affects about one in 15 women worldwide. The major endocrine disruption is excessive androgen secretion or activity, and a large proportion of women also have abnormal insulin activity. Many body systems are affected in polycystic ovary syndrome, resulting in several health complications, including menstrual dysfunction, infertility, hirsutism, acne, obesity, and metabolic syndrome. Women with this disorder have an established increased risk of developing type 2 diabetes and a still debated increased risk of cardiovascular disease. The diagnostic traits of polycystic ovary syndrome are hyperandrogenism, chronic anovulation, and polycystic ovaries, after exclusion of other conditions that cause these same features. A conclusive definition of the disorder and the importance of the three diagnostic criteria relative to each other remain controversial. The cause of polycystic ovary syndrome is unknown, but studies suggest a strong genetic component that is affected by gestational environment, lifestyle factors, or both.

Climate Modes of the Phanerozoic

Abstract: Preface Introduction 1. The early Cambrian to late Ordovician warm mode 2. The late Ordovician to early Silurian cool mode 3. The late Silurian to early Carboniferous warm mode 4. The early Carboniferous to late Permian cool mode 5. The late Permian to middle Jurassic warm mode 6. The middle Jurassic to early Cretaceous cool mode 7. The late Cretaceous to early Tertiary warm mode 8. The Cenozoic cool mode: early Eocene - late Miocene 9. The Cenozoic cool mode: late Miocene - Holocene 10. Causes and chronology of climate change Bibliography Index.

Aspects of the chemical structure of soil organic materials as revealed by solid-state 13C NMR spectroscopy

Abstract: Solid-state cross-polarisation/magic-angle-spinning3C nuclear magnetic resonance (CP/MAS13C NMR) spectroscopy was used to characterise semi-quantitatively the organic materials contained in particle size and density fractions isolated from five different mineral soils: two Mollisols, two Oxisols and an Andosol The acquired spectra were analysed to determine the relative proportion of carboxyl, aromatic, O-alkyl and alkyl carbon contained in each fraction Although similar types of carbon were present in all of the fractions analysed, an influence of both soil type and particle size was evident The chemical structure of the organic materials contained in the particle size fractions isolated from the Andosol was similar; however, for the Mollisols and Oxisols, the content of O-alkyl, aromatic and alkyl carbon was greatest in the coarse, intermediate and fine fractions, respectively The compositional differences noted in progressing from the coarser to finer particle size fractions in the Mollisols and Oxisols were consistent with the changes noted in other studies where CP/MAS13C NMR was used to monitor the decomposition of natural organic materials Changes in the C:N ratio of the particle size fractions supported the proposal that the extent of decomposition of the organic materials contained in the fine fractions was greater than that contained in the coarse fractions The increased content of aromatic and alkyl carbon in the intermediate size fractions could be explained completely by a selective preservation mechanism; however, the further accumulation of alkyl carbon in the clay fractions appeared to result from both a selective preservation and anin situ synthesis The largest compositional differences noted for the entire organic fraction of the five soils were observed between soil orders The differences within orders were smaller The Mollisols and the Andosol were both dominated by O-alkyl carbon but the Andosol had a lower alkyl carbon content The Oxisols were dominated by both O-alkyl and alkyl carbon A model describing the oxidative decomposition of plant materials in mineral soils is proposed and used to explain the influence of soil order and particle size on the chemical composition of soil organic matter in terms of its extent of decomposition and bioavailability

The role of calcium in salt toxicity

Abstract: Salt toxicity comprises osmotic and ionic components both of which can severely affect root and shoot growth. Uptake of Na+ across the plasma membrane is very fast resulting in physiological effects on extracellular as well as intracellular sites. Sodium reduces binding of Ca2+ to the plasma membrane, inhibits influx while increasing efflux of Ca2+, and depletes the internal stores of Ca2+ from endomembranes. These changes in the cell Ca2+ homeostasis are suggested here to be the primary responses to salt stress that are perceived by root cells. Salt would almost instantly reduce the amount of Ca2+ being transferred to the leaf cells, with Ca2+ activity dropping and Na+ activity rising in the apoplasm of leaf cells. This Ca2+ signal would be transported to leaves together with, if not preceding, the signal of limited water supply. Hormonal signals are likely to be secondary in nature and caused by the Na+-related disturbance of the root cell Ca2+ homeostasis. Ameliorative effects of supplemental Ca2+ on salt stress are exerted through preventing Na+-related changes in the cell Ca2+ homeostasis.

Fluctuating asymmetry: a biological monitor of environmental and genomic stress.

Abstract: Increased fluctuating asymmetry (FA) of morphological traits occurs under environmental and genomic stress Such conditions will therefore lead to a reduction in developmental homeostasis Based upon temperature extreme experiments, relatively severe stress is needed to increase FA under field conditions Increasing asymmetry tends, therefore, to occur in stressed marginal habitats Genetic perturbations implying genomic stress include certain specific genes, directional selection, inbreeding, and chromosome balance alterations It is for these reasons that transgenic organisms may show increased FA As there is evidence that the effects of genomic and environmental stress are cumulative, organisms in a state of genomic stress may provide sensitive biological monitors of environmental stress

Small catalytic RNAs.

Abstract: PERSPECTIVES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 641 ROLLING CIRCLE REPLICATION REQUIRES SPECIFIC RNA CLEAVAGE . . . . . . . 643 SELF-CLEAVAGE OF RNA VIA THE HAMMERHEAD STRUCTURE.. . . . . . . . . . . . . . . 645 Double Hammerhead Structure .... . . . . . . . . . .. . . . . . . . . . . . . . .. .. . . . . .... . . . . ... . . . . . . . . .... . . . . . 645 Hammerhead Self-Cleavage in Trans . . .... . . . .. .... . . . ....... . . . . . . .. . . . . . . . . . . . .. . . . . .. . . . . . 647 Mutagenesis A nalysis oj the Hammerhead Reaction . ....... . . . . ...... . . . . . ..... . 649 What is the Tertiary Structure of the Hammerhead? . ... .. . . . .... .. . . . .. ..... . . .. .... . . . . . 651 What is the Mechanism of Self-Cleavage? . . .... . . . .. ... . . . .... . . . . . .. . . . . . . . . . .... . .. . ..... . 652 Ribozymes Targetting RNA Molecules . . . .. . . . . . . ... . . . . . . . . . . . . . ... . . . . . . . . . .... 655 Hammerhead Ribozymes to Manipulate Gene Expression ... . . . . ....... . . . . .. ... . . . . . .... 656 MINUS sTRSV SELF-CLEAVES VIA A DIFFERENT MECHANISM THAN PLUS sTRSV ... . . . ...... . . . . ..... . . . . .... . . . . ... . . . . . . . . .... . . . . ...... . . ...... . 659 Self-Cleavage of Minus sTRSV . . . . . . . . . . ....... . .. .... . . . .... . . . . ....... . . . . . . ... . . ..... . . . . . . . 660 Self-Cleavage in Trans and Mutagenesis.. . . ..... . . . . . . .... . . ...... . . . . .... .. . . . . .... . . . . . ... 661 HEPATITIS DELTA VIRUS PLUS AND MINUS RNAs SELF-CLEAVE. . . . . . . . . . . . . . . 662 RNAs FROM NEUROSPORA MITOCHONDRIAL PLASMIDS SELF-CLEAVE. . . . . . . 665 HOW COMMON ARE SELF-CLEAVAGE REACTIONS IN NATURE?. . . .. . . . . . . . . . . 665 Lead-Catalyzed Cleavage of Yeast Phe-tRNA . . . ... . ... . . . . . . . . . . . . ... . . . . . . . .. . . . . . . . .. . . . . 666 A Simple Mn2+ -Catalyzed Reaction . . . .... . . . .... . . . . .... . .. . . . . . . . ....... . . . ...... . ......... . 666 Are in Trans Cleavage Reactions Common in Vivo? .... . ... . .. . . . . . . ... . . . ...... . . . ...... 667

Motivational Readiness, self-efficacy and decision-making for exercise

Abstract: Exercise has important health benefits, but a large proportion of the population is physically inactive. We examined the prevalence of stages of readiness to exercise and their relationship to self-efficacy and to the costs and benefits of exercising in samples of 1093 employees in and around Providence, Rhode Island, and 801 employees in Adelaide, Australia. In both samples, 40.6% of respondents had not yet begun to take action (not thinking about starting to exercise or thinking about it but not doing it), while 59.4% were at some phase of action (exercising some, starting to exercise regularly, exercising regularly). Scores on self-efficacy items and cost-and-benefit items significantly differentiated employees at extreme stages. In contrast with those who exercised regularly, employees who had not yet begun to exercise had little confidence in their ability to exercise and saw exercising as having nearly as many costs as it had benefits. There is the potential to enhance the impact of exercise interventions by targeting them so as to address factors related to these different stages of readiness to exercise.

Selecting zinc-efficient cereal genotypes for soils of low zinc status

Abstract: Deficiencies of zinc are well known in all cereals and cereal-growing countries. From physiological evidence reported elsewhere, it would appear that a critical level for zinc is required in the soil before roots will either grow into it or function effectively; it is likely the requirement is frequently not met in deep sandy, infertile profiles widespread in southern Australia. Because fertilizing subsoils is impractical, this paper presents arguments for breeding cereal varieties with root systems better able to mobilise zinc from soil sources of low availability. Other agronomic arguments are presented in support of breeding for zinc efficiency.

Role of calcium in aluminium toxicity

Abstract: summary Aluminium is the most important growth-limiting factor in many acid soils throughout the world. Physiological effects of Al toxicity and mechanisms of tolerance are not well understood. An initial uptake of Al is confined to the apoplasm. Aluminium complexes (whose exact identification is beyond current experimental techniques) enter the cytosol slowly and only after prolonged exposure. Electrochemical properties of the cell wall Donnan free space as well as the plasma membrane of root cells are altered by the presence of Al ions that are polyvalent cations in acidic environments. The primary Al effects are very fast (taking only seconds to several minutes to develop) and may therefore occur while Al is still in the Donnan free space and on the apoplasmic side of the plasma membrane. Resumption of root growth upon removal of Al ions supports such a claim. Aluminium affects membrane permeability for both electrolytes and non-electrolytes; it reduces accumulation of divalent cations (especially Ca and Mg) by interfering with the membrane transport. Aluminium alters the pattern of Ca2+ fluxes across the plasma membrane, thus supposedly disturbing symplasmic Ca2+ homeostasis. Supplemental Ca2+ can greatly alleviate deleterious Al effects. Frequently observed changes in the secretory activity of root cells exposed to Al are mediated through altered cell Ca2+ homeostasis; they result in cessation of cell wall growth and stoppage of root elongation. Involvement of calmodulin in the Al-related phenomena is suggested to be indirect, at least in the initial stages of the Al treatment when Al is likely to be confined to the apoplasm. The role of growth substances, at least auxins and cytokinins, in the Al toxicity syndrome appears to be related to the Ca-Al interactions that may alter the pattern of auxin transport as well as cytokinin biosynthesis and transport. Disturbance of the cell Ca2+ homeostasis appears to be an important feature of ion-related environmental stresses in general (salt, heavy metals, aluminium).

Linear dichroism spectroscopy of nucleic acids.

Abstract: This review will consider solution studies of structure and interactions of DNA and DNA complexes using linear dichroism spectroscopy, with emphasis on the technique of orientation by flow. The theoretical and experimental background to be given may serve, in addition, as a general introduction into the state of the art of linear dichroism spectroscopy, particularly as it is applied to biophysical problems.

Multiple diagnoses in posttraumatic stress disorder in the victims of a natural disaster

Abstract: A population of the fire fighters who had been exposed to a natural disaster were screened using the General Health Questionnaire 4, 11, and 29 months after a natural disaster. On the basis of these data, a high-risk group of subjects who had scored as cases and probable cases and a symptom-free comparison group were interviewed using the Diagnostic Interview Schedule 42 months after the disaster. The prevalence of posttraumatic stress disorder (PTSD), affective disorders, and anxiety disorders was examined. Only 23% of the 70 subjects who had developed a PTSD did not attract a further diagnosis, with major depression being the most common concurrent disorder. Comorbidity appeared to be an important predictor of chronic PTSD, especially with panic disorder and phobic disorders. The subjects who had only a PTSD appeared to have had the highest exposure to the disaster. Adversity experienced both before and after the disaster influenced the onset of both anxiety and affective disorders.

Impaired motor skill (clumsiness) in otherwise normal children: a review.

Abstract: Some children, who are otherwise normal, experience unusual difficulties with the acquisition and performance of motor skills. These children are commonly described as being clumsy. Impaired performance of motor skills, to the degree experienced by clumsy children, is unlikely to present a serious problem. However, a review of the literature suggests that significant associated and secondary emotional problems are common. In particular, such problems are likely to result in children not achieving their full potential. Therefore, it is important that the cause of affected children's impaired motor skills be recognized early so that these problems can be avoided, or at least minimized, by a sympathetic understanding of their difficulties. The problem is that, whilst severely affected children can be readily recognized, identification of mildly and moderately clumsy children is difficult.

Annular tears and disc degeneration in the lumbar spine. A post-mortem study of 135 discs.

Abstract: We studied 135 lumbar discs from 27 spines removed post-mortem from subjects of an average age of 31.5 years. Defects of the annulus fibrosus were classified as peripheral, circumferential or radiating; the nucleus pulposus as normal, moderately or severely degenerate. Peripheral tears were more frequent in the anterior annulus, except in the L5-S1 disc. Circumferential tears were equally distributed between the anterior and the posterior annulus. Almost all the radiating tears were in the posterior annulus, and closely related to the presence of severe nuclear degeneration. Histology suggested that peripheral tears were due to trauma rather than biochemical degradation, and that they developed independently of nuclear degeneration. The association of peripheral annular lesions with low back pain is uncertain but our study suggests that they may have a role in the pathogenesis of discogenic pain.

Influence of root diameter on the penetration of seminal roots into a compacted subsoil

Abstract: A field experiment was conducted to evaluate the influence of root diameter on the ability of roots of eight plant species to penetrate a compacted subsoil below a tilled layer. The soil was a fine sandy loam red-brown earth with a soil strength of about 3.0 MPa (at water content of 0.13 kg kg-1, corresponding to 0.81 plastic limit) at the base of a tilled layer. Relative root diameter (RRD), which was calculated as the ratio of the mean diameters of roots of plants grown in compacted soil to the mean diameters of those from uncompacted soil, was used to compare the sensitivity of roots to thicken under mechanical stress.

Genomic in situ hybridization to identify alien chromosomes and chromosome segments in wheat.

Abstract: Genomic in situ hybridization was used to identify alien chromatin in chromosome spreads of wheat, Triticum aestivum L., lines incorporating chromosomes from Leymus multicaulis (Kar. and Kir.) Tzvelev and Thinopyrum bessarabicum (Savul. and Rayss) Love, and chromosome arms from Hordeum chilense Roem. and Schult, H. vulgare L. and Secale cereale L. Total genomic DNA from the introgressed alien species was used as a probe, together with excess amounts of unlabelled blocking DNA from wheat, for DNA:DNA in-situ hybridization. The method labelled the alien chromatin yellow-green, while the wheat chromosomes showed only the orange-red fluorescence of the DNA counterstain. Nuclei were screened from seedling root-tips (including those from half-grains) and anther wall tissue. The genomic probing method identified alien chromosomes and chromosome arms and allowed counting in nuclei at all stages of the cell cycle, so complete metaphases were not needed. At prophase or interphase, two labelled domains were visible in most nuclei from disomic lines, while only one labelled domain was visible in monosomic lines. At metaphase, direct visualization of the morphology of the alien chromosome or chromosome segment was possible and allowed identification of the relationship of the alien chromatin to the wheat chromosomes. The genomic in-situ hybridization method is fast, sensitive, accurate and informative. Hence it is likely to be of great value for both cytogenetic analysis and in plant breeding programmes.

Some geodynamic and compositional constraints on postorogenic magmatism

Abstract: Postorogenic magmatic suites are common to many orogens, in many cases apparently just postdating the cessation of deformation. They differ from preceding orogenic suites in that they have higher temperatures, more primitive isotopic signatures, and bimodal natures, and thus are compositionally similar to suites found in extensional regimes. We propose that thinning of the lithospheric mantle, which may be an automatic response to orogenic lithospheric thickening, is responsible for these magmatic suites. Mantle lithospheric thinning moves the asthenospheric-lithospheric thermal boundary higher in the lithospheric column, thereby raising the overall thermal budget of the orogen and the likelihood of basaltic magmatism. This removal of much of the dense, lithospheric mantle root of the orogen also invokes uplift capable of producing horizontal orogenic buoyancy forces that will oppose and potentially terminate deformation. Extreme fractionation of the magmas is promoted by high temperatures and a noncompressional or tensional lithospheric stress regime to produce accompanying felsic (A-type) magmas. This model explains why the cessation of deformation is coincident with high-temperature bimodal magmatism and inferred uplift, as well as the long-noted similarity and confusion between "postorogenic" and extensional magmatic suites. This arises because both reflect thinning of the lithospheric mantle, not because both reflect extensional tectonics. We suggest that these magmatic episodes may be important in transferring lithospheric mantle material and its compositional signatures into the crust.

Uterine epithelial cells synthesize granulocyte-macrophage colony-stimulating factor and interleukin-6 in pregnant and nonpregnant mice.

Abstract: Cytokine secretion by endometrial cells from estrous and mated mice was measured using specific bioassays. The granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-6 (IL-6) contents of uterine intraluminal fluid were elevated greater than 20-fold and 250-fold respectively following mating, and both cytokines were synthesized in abundance in vitro by uterine cells harvested at estrus and on Day 1 of pregnancy. Synthesis was not impaired in genetically lymphocyte-deficient nude, SCID, or beige mice. To determine the cellular origin of the cytokines, a panning technique employing monoclonal antibodies against a range of leukocyte and other lineage markers was used to isolate uterine cell subsets in vitro. These experiments identified glandular and/or luminal epithelial cells as the major source of GM-CSF and IL-6 in estrous and pregnant uteri. Stromal fibroblasts also synthesized IL-6, as did macrophages in mated mice. Epithelial cells harvested from midgestation uteri secreted GM-CSF and IL-6 in quantities similar to those of cells from estrous and mated mice. Bioactivities of both cytokines derived from epithelial cells were neutralized by specific antibodies, and size-exclusion chromatography of conditioned media from uterine cells revealed peaks of GM-CSF and IL-6 bioactivity with M(r) 23,000 and 23,000-26,000, respectively. Bioassay of luminal fluids and culture supernatants were negative for the cytokines interleukin-1, interleukin-2, interleukin-3, and tumor necrosis factor-alpha. These studies identify murine uterine epithelium as a potent source of the cytokines GM-CSF and IL-6, which we postulate have potentially important functions in pregnancy through actions on target cells in both the uterus and the conceptus.

Avoidance and intrusion in posttraumatic stress disorder

Abstract: Longitudinal data from 290 firefighters who had completed questionnaires 4, 11, and 29 months after exposure to a natural disaster were used to examine the role of intrusive and distressing memories in the etiology of posttraumatic stress disorder. At 42 months, all those who were at risk of having developed a psychiatric disorder (N = 113) and a randomly selected comparison group (N = 34) who had never developed symptoms were interviewed using the Diagnostic Interview Schedule. The intrusion subscale score of the Impact of Events Scale accounted solely for the etiological link between the disaster and posttraumatic disorders. Avoidance had no direct relationship with the onset of symptoms and appeared to be a defensive strategy to contain the distress generated by the re-experiencing of the disaster, indicating the importance of separating these phenomena from disorder mood and arousal in posttraumatic stress disorder. An information processing model was validated using three different data sets, which suggests its robustness. Using cross-lagged panel correlations, a bidirectional relationship was demonstrated between disorder and intrusive recollections, suggesting that the intensity of recurring memories of a traumatic experience is as indicative of a disturbance of mood and arousal as the exposure to the trauma.

Risk factors for tumors of the brain and meninges: Results from the Adelaide adult brain tumor study

Abstract: A population-based case-control study of incident primary brain tumors in adults was carried out in Adelaide, Australia in the period 1987 through 1990. It included 110 subjects with newly diagnosed primary glioma, 60 subjects with meningioma and 417 controls selected from the Australian Electoral Roll and frequency-matched to cases for age (within 2 years), sex and postal code. Some interesting new associations were found: (1) an increased risk of glioma in women who reported working with cathode-ray tubes (relative risk = 4.1, 95% confidence interval: 1.3-13.2); (2) a decreased risk of glioma in those with a history of allergic diseases (relative risk = 0.5, 95% confidence interval: 0.3-0.9); and (3) an increased risk of meningioma in those exposed to passive smoking from a spouse, especially amongst females (relative risk = 2.7, 95% confidence interval: 1.2-6.1). A pooled analysis of the multi-center group of studies to which the present study belongs should allow more confident claims concerning risk factors for brain tumors.

Development of melatonin production in infants and the impact of prematurity.

Abstract: The development of rhythmic 6-sulfatoxymelatonin excretion in urine was studied in healthy full-term and premature infants during the first 12 months of life. There was little evidence of rhythmic 6-sulfatoxymelatonin excretion before 9 to 12 weeks of age in full-term infants. Over this period, excretion increased five to six times compared to the excretion at 6 weeks (08 +/- 103 vs. 2973 +/- 438 pmol/24 h) with the major proportion of the hormone metabolite being excreted between 0200-1000 h. At 24 weeks of age, total 6-sulfatoxymelatonin excretion was 25% of adult levels. Premature infants (51 +/- 4 days premature) had a delay in the appearance of rhythmic 6-sulfatoxymelatonin of approximately 9 weeks. Even after correcting for gestational age or length of time at home, the premature infants were found to have a 2-3 week delay in the development of 6-sulfatoxymelatonin rhythmicity compared to full-term infants. These results provide evidence that neural centers responsible for rhythm generation and/or the pineal gland fail to accelerate their development after premature delivery. This may be due to the environment the infants are exposed to during their stay in hospital, particularly the pattern and intensity of lighting.

Serotype conversion in Vibrio cholerae O1.

Abstract: Vibrio cholerae O1 exists as two major serotypes, Inaba and Ogawa, which are associated with the O antigen of the lipopolysaccharide and are capable of unequal reciprocal interconversion. The 20-kilobase rfb regions encoding O-antigen biosynthesis in strains 569B (Inaba) and O17 (Ogawa) have been cloned in Escherichia coli K-12 and the nucleotide sequences have been determined. Besides several base substitutions and a small deletion in the 569B sequence relative to O17, there is a single nucleotide change resulting in a TGA stop codon within the gene for the 32-kDa RfbT protein. We have demonstrated that rfbT is responsible for serotype conversion (Inaba to Ogawa). The construction of a specific rfbT mutation in the Ogawa strain O17, and the ability of the gene from O17 to complement Inaba strains to Ogawa, confirmed rfbT as the gene required for the Ogawa serotype. By Southern hybridization and sequencing of PCR products of a number of strains, we have shown that the changes observed in one Inaba strain (569B) are not conserved in other Inaba strains. This may explain why some Inaba strains are able to convert to Ogawa whereas others are not. The protein encoded by rfbT has been identified and expressed in E. coli K-12 using a phage T7 expression system. Amino-terminal analysis of partially purified protein has identified the translational start of the protein. Primer extension studies have enabled the 5' end of the mRNA to be defined. It exists as a separate transcript from the rest of the rfb region, and the distinctive G + C content of rfbT suggests that it has been acquired from a non-Vibrio source.

Functional and Ecological Aspects of Ediacaran Assemblages

Abstract: Reference to fossil imprints of soft-bodied Ediacaran metazoans made by Hill and Bonney (1877, p. 757) recorded two of “those curious arrangements of concentric rings which have been supposed to be organisms” present on one of the bedding faces of the North Quarry, Woodhouse Eaves in Charnwood, Forest, Leicestershire, England (see Ford, 1958, 1963); the markings were dismissed as being “accidental ... (and) inorganic.” Early this century, P. Range and H. Schneiderhohn collected fossil remains of equivalent age at Kuibis Farm in South West Africa (Namibia), and the organic nature of this material was confirmed by Gurich (1929, 1933). The history of discovery of such fossils during the mid part of the century (Sprigg, 1947, 1949; Ford, 1958, 1963, 1968, 1979a,b, 1981; Anderson and Misra, 1968) and the subsequent finding of similar materials widely sited about the globe are well known (e.g., Glaessner, 1984; Hofmann, 1987).

Social Support and Psychological Well-Being in Young Adults: The Multi-Dimensional Support Scale

Abstract: A large sample (N = 483) of community-living adults (M age = 23.6 years) responded to questions about the frequency and adequacy of emotional, practical, and informational support during the past month from three sources-confidants, peers, and supervisors-using the Multi-Dimensional Support Scale. Factor analysis was used to distinguish meaningful regularities in item responses, and the resulting five scales have high internal reliability. Scores correlated significantly with measures of self-esteem, depressive affect, and psychological disturbance according to the General Health Questionnaire. To investigate what contribution support measures could make to the prediction of psychological well-being, hierarchical regression analyses were carried out with stressors entered first and support scores entered second. As expected, respondents' psychological well-being was related to their level of life stress; however, the addition of social support measures doubled the explained variance in measures of psychological well-being. The support measure with the strongest association with well-being was the frequency of supportive behaviors toward the respondent by close family and friends.

Modern carbonate and terrigenous clastic sediments on a cool water, high energy, mid‐latitude shelf: Lacepede, southern Australia

Abstract: The wide Lacepede Shelf and narrow Bonney Shelf are contiguous parts of the south-eastern passive continental margin of Australia. The shelves are open, generally deeper than 40 m, covered by waters cooler than 18°C and swept by oceanic swells that move sediments to depths of 140 m. The Lacepede Shelf is proximal to the ‘delta’of the River Murray and the Coorong Lagoon. Shelf and upper slope sediments are a variable mixture of Holocene and late Pleistocene quartzose terrigenous clastic and bryozoa-dominated carbonate particles. Bryozoa grow in abundance to depths of 250 m and are conspicuous to depths of 350 m. They can be grouped into four depth-related assemblages. Coralline algae, the only calcareous phototrophs, are important sediment producers to depths of 70 m. Active benthic carbonate sediment production occurs to depths of 350 m, but carbonate sediment accumulation is reduced on the open shelf by continuous high energy conditions. The shelf is separated into five zones. The strandline is typified by accretionary sequences of steep shoreface, beach and dune carbonate/siliciclastic sediments. Similar shoreline facies of relict bivalve/limestone cobble ridges are stranded on the open shelf. The shallow shelf, c.40–70 m deep, is a wide, extremely flat plain with only subtle local relief. It is a mosaic of grainy, quartzose, palimpsest facies which reflect the complex interaction of modern bioclastic sediment production (dominated by bryozoa and molluscs), numerous highstands of sea level over the last 80 000 years, modern mixing of sediments from relatively recent highstands and local introduction of quartz-rich sediments during lowstands. The middle shelf, c.70–140 m deep, is a gentle incline with subtle relief where Holocene carbonates veneer seaward-dipping bedrock clinoforms and local lowstand beach complexes. Carbonates are mostly modern, uniform, clean, coarse grained sands dominated by a diverse suite of robust to delicate bryozoa particles produced primarily in situ but swept into subaqueous dunes. The deep shelf edge, c. 140–250 m deep, is a site of diverse and active bryozoa growth. Resulting accumulations are characteristically muddy and distinguished by large numbers of delicate, branching bryozoa. The upper slope, between 250 and 350 m depth, contains the deepest platform-related sediments, which are very muddy and contain a low diversity suite of delicate, branching cyclostome bryozoa. This study provides fundamental environmental information critical for the interpretation of Cenozoic cool water carbonates and the region is a good model for older mixed carbonate-terrigenous clastic successions which were deposited on unrimmed shelves.

Resistance to Acetolactate Synthase-Inhibiting Herbicides in Annual Ryegrass (Lolium rigidum) Involves at Least Two Mechanisms.

Abstract: WLR1, a biotype of Lolium rigidum Gaud. that had been treated with the sulfonylurea herbicide chlorsulfuron in 7 consecutive years, was found to be resistant to both the wheat-selective and the nonselective sulfonylurea and imidazolinone herbicides. Biotype SLR31, which became cross-resistant to chlorsulfuron following treatment with the aryloxyphenoxypropionate herbicide diclofop-methyl, was resistant to the wheat-selective, but not the nonselective, sulfonylurea and imidazolinone herbicides. The concentrations of herbicide required to reduce in vitro acetolactate synthase (ALs) activity 50% with respect to control assays minus herbicide for biotype WLR1 was greater than those for susceptible biotype VLR1 by a factor of >30, >30, 7,4, and 2 for the herbicides chlorsulfuron, sulfometuron-methyl, imazapyr, imazathapyr, and imazamethabenz, respectively. ALS activity from biotype SLR31 responded in a similar manner to that of the susceptible biotype VLR1. The resistant biotypes metabolized chlorsulfuron more rapidly than the susceptible biotype. Metabolism of 50% of [phenyl-U-14C]chlorsulfuron in the culms of two-leaf seedlings required 3.7 h in biotype SLR31, 5.1 h in biotype WLR1, and 7.1 h in biotype VLR1. In all biotypes the metabolism of chlorsulfuron in the culms was more rapid than that in the leaf lamina. Resistance to ALS inhibitors in L. rigidum may involve at least two mechanisms, increased metabolism of the herbicide and/or a herbicide-insensitive ALS.