bluuebunny/crossref_metadata_2025 huggingface dataset:
Elevated CO2 and warming impacts on flowering phenology in a southern Australian grassland are related to flowering time but not growth form, origin or longevity
Authors: Hovenden Mark J. , Williams Amity L. , Pedersen Jane Kongstad , Vander Schoor Jacqueline K. , Wills Karen E.
Published: February 2009

Flowering is a critical stage in plant life cycles, and changes in phenology might alter processes at the species, community and ecosystem levels. Therefore, likely flowering-time responses to global-change drivers are needed for predictions of global-change impacts on natural and managed ecosystems. Predicting responses of species to global changes would be simplified if functional, phylogenetic or biogeographical traits contributed substantially to a species’ response. Here we investigate the role of growth form (grass, graminoid, forb, subshrub), longevity (annual, perennial), origin (native, exotic) and flowering time in determining the impact of elevated [CO2] (550 μmol mol−1) and infrared warming (mean warming of +2°C) on flowering times of 31 co-occurring species of a range of species-types in a temperate grassland in 2004, 2005 and 2007. Warming reduced time to first flowering by an average of 20.3 days in 2004, 2.1 days in 2005 and 7.6 days in 2007; however, the response varied among species and was unrelated to growth form, origin or longevity. Elevated [CO2] did not alter flowering times; neither was there any [CO2] by species-type interaction. However, both warming and elevated [CO2] tended to have a greater effect on later-flowering species, with time to first flowering of later-flowering species being reduced by both elevated [CO2] (P < 0.001) and warming (P < 0.001) to a greater extent than that of earlier-flowering species. These results have ramifications for our predictions of community and ecosystem interactions in native grasslands in response to global change.
An experimental study of fire and moisture stress on the survivorship of savanna eucalypt seedlings
Authors: Fensham R. J. , Fairfax R. J. , Buckley Y. M.
Published: February 2009

Eucalyptus melanophloia and E. populnea dominate large areas of savanna in eastern Australia. Under aboriginal management, fires probably occurred under a broad range of conditions, but under pastoral management, burning is avoided when soil moisture is low. This experiment subjected E. melanophloia and E. populnea seedlings to burning and moisture stress, to examine whether this change in burning regime could affect seedling survivorship. The findings suggest survivorship rates are 87–93% for unstressed seedlings with relatively large lignotubers (>12 mm2 plan area) and 56–66% for unstressed seedlings with small lignotubers. There was no substantial interactive effect between moisture stress and burning for E. melanophloia, but such an interaction was apparent for E. populnea, such that moisture stress multiplied the effect of burning. The timing of burning in relation to soil-moisture conditions may have an enduring effect on woodland structure where E. populnea is dominant. E. melanophloia seedlings are more resistant to burning, especially with moisture stress, and fire may not be limiting structural development in woodlands where this species dominates. However, a more detailed understanding of species demography is required, including the conditions required for germination, causes of seedling mortality and the time taken for seedlings to develop fire resistance in the field.
Adaptations to winter-wet ironstone soils: a comparison between rare ironstone Hakea (Proteaceae) species and their common congeners
Authors: Poot Pieter , Bakker Roy , Lambers Hans
Published: February 2009

In south-western Australia, a rare plant community is found on shallow, winter-wet ironstone soils, which occur on coastal plains as isolated islands in a matrix of surrounding deeper sandy soils. To test for local adaptation of species endemic to these communities and potential inhibitory effects of ironstone soils on other species, we compared two rare ironstone Hakea species with four of their common congeners. The common congeners were chosen from nearby winter-wet habitats on deeper sandy soils and from non-wetland woodland habitats (i.e. two species in each habitat group). Seedlings of all species were grown on ironstone soil and subjected to waterlogging in a glasshouse experiment. Significant habitat-related differences emerged only when seedlings were waterlogged. When compared with their controls, shoot and root growth rates of ironstone endemics were less affected by waterlogging than those of their common congeners. This was partly associated with their large accumulation of leaf starch, and their substantial adventitious-root formation. Leaves of ironstone endemics also exhibited consistently higher concentrations of Cu and Zn. In contrast to the effect of waterlogging in the glasshouse experiment, natural waterlogging of seedlings transplanted into ironstone communities led to high mortality, but only in the non-wetland Hakea species. Mortality was strongly associated with the intensity of flooding events, with very small differences in inundation level (10–15 mm) strongly influencing seedling survival. Our results suggest that the chemistry of the waterlogged ironstone soil, and species adaptations to it, are important for understanding distribution patterns of these Hakea species.
Luminescent Lanthanide Complexes with 1,2-Bis(ethylsulfinyl)ethane: Structural Dependences on Reacting Solvent, Ratio, and Co-Ligand
Authors: Li Jian-Rong , Zhang Ruo-Hua , Bu Xian-He
Published: February 2009

The present paper reports our sequential efforts to investigate the structures and properties of flexible disulfoxide–lanthanide complexes. Combining our reported results, on the basis of changing synthesis conditions and using a co-ligand, six new complexes, [Ln(meso-L)4](ClO4)3(H2O)
n
(n = 0.5, Ln = Eu (1), Gd (2); n = 0, Ln = Tb (3)) and [Ln(meso-L)2(phen)2](ClO4)3(CHCl3)2 (Ln = Eu (4), Gd (5), and Tb (6)) (herein, L = 1,2-bis(ethylsulfinyl)ethane, phen = 1,10-phenanthroline) were synthesized, and their structures were characterized by IR spectroscopy, elemental analysis, and X-ray single-crystal diffraction. The dependence of the formation of 1–3 on the solvents used and reaction ratios in the preparation was confirmed. Complexes 1–3 are isomorphous ionic complexes, and the coordination cation is chiral and has a mononuclear structure, in which the LnIII atom is eight-coordinated by four L ligands. Complexes 4–6 are also isomorphous mononuclear ionic complexes, and in each complex cation, the central LnIII atom is eight-coordinated by two L ligands and two phen molecules. In 1–6, all the L ligands exhibit the meso configuration and bis-monodentate chelating coordination mode. Further, the absorption and luminescent spectra of L, phen and complexes 4–6 in solution were investigated at room temperature. The absorption spectra show that only a very slight shift of the absorption band occurred for the ligands L and phen when coordinating to metal ions, being consistent with their origin. The photoluminescence of 4 and 6 exhibits the usual metal-centred emission spectra arising from ligand-to-metal energy transfer and the emission of π → π* transitions from the phen ligand; the latter is also seen in the emission spectrum of 5.
Alum-Catalyzed One-Pot Solventless Synthesis of 1,5-Benzodiazepines
Authors: Mahajan Deepali , Naqvi Tahira , Sharma Rattan Lal , Kapoor Kamal K.
Published: February 2009

Alum [KAl(SO4)2∙12H2O] was found to be an efficient, non-toxic, cheap, and environmentally benign catalyst for the synthesis of 1,5-benzodiazepines, in good to excellent yields, from the condensation of 1 mole of o-phenylenediamine with 2 moles of ketone under solvent-free conditions.
Studies Towards the Stereoselective α-Hydroxylation of Flavanones. Biosynthetic Significance
Authors: Border Zola-Michéle , Marais Charlene , Bezuidenhoudt Barend C. B. , Steenkamp Jacobus A.
Published: February 2009

The enolates of various propiophenones, chromanones, and also analogues of naturally occurring flavanones were stereoselectively hydroxylated at the α-position, by employing commercially available enantiopure oxaziridines, to afford the desired α-hydroxylated target molecules in good to exceptional stereoselectivities and in moderate to good chemical yields. A mechanistic rationale is presented to account for the stereoselectivities achieved. These in vitro results were tentatively related to the stereoselective biosynthesis of enantio-enriched dihydroflavonols while questions were raised about the authenticity of certain natural compounds.
The Chemoenzymatic Total Synthesis of Phellodonic Acid, a Biologically Active and Highly Functionalized Hirsutane Derivative Isolated from the Tasmanian Fungus Phellodon melaleucus
Authors: Reekie Tristan A. , Austin Kerrie A. B. , Banwell Martin G. , Willis Anthony C.
Published: February 2009

A total synthesis of the title natural product, 1, has been achieved using the cis-1,2-dihydrocatechol 7 as starting material. Compound 7 is readily obtained in large quantity and in an enantiomerically pure form through the whole-cell biotransformation of toluene using the genetically engineered microorganism E. coli JM109 (pDTG601) that overexpresses the enzyme toluene dioxygenase (TDO). Three key chemical steps were employed in the synthesis, the first of which was the microwave-promoted Diels–Alder cycloaddition reaction between diene 8 and cyclopent-1-en-2-one to give adduct 9. The second key step was the photochemically promoted oxa-di-π-methane rearrangement of the bicyclo[2.2.2]octenone derivative 15 of 9 to give the epimers 16 and 17, and the third key step was the reductive cleavage of the last pair of compounds so as to afford the linear triquinane 19. Elaboration of compound 19 to target 1 followed established procedures. Single-crystal X-ray analyses were carried out on compounds 11 and 19.
Vault Isomerization and its Application to the Synthesis of a Dideoxydysoxysulfone Precursor
Authors: Andrews Christopher G. , Langler Richard F.
Published: February 2009

Novel silica-induced controlled disproportionation of α-mercaptosulfones produces α-mercapto α′-sulfonyl sulfides. Its discovery and exploitation, as the heart of a new process – vault isomerization – permits the elaboration of a more efficient synthesis of a previously described synthetic precursor.
Synthesis, Characterization, DNA Binding, and Photocleavage of [Ru(bpy)2(MFIP)]2+ and [Ru(phen)2(MFIP)]2+
Authors: Tan Lifeng , Zhang Sheng , Liu Xiaohua , Xiao Yue
Published: February 2009

The new ligand 2-(5-methyl-furan-2-yl)imidazo[4,5-f][1, 10]phenanthroline (MFIP) and its complexes [Ru(bpy)2(MFIP)]2+ 1 (bpy = 2,2′-bipyridine) and [Ru(phen)2(MFIP)]2+ 2 (phen = 1,10-phenanthroline) were synthesized and characterized by elemental analysis, mass spectrometry, and 1H NMR spectroscopy. The DNA binding properties of the two complexes were investigated by different spectrophotometric methods and viscosity measurements. The results suggest that both complexes bind to calf thymus DNA (CT-DNA) through intercalation, and both complexes can enantioselectively interact with CT-DNA. The Λ enantiomers of both complexes are slightly predominant for binding to CT-DNA over the Δ enantiomer. When irradiated at 400 nm, the two complexes promote the photocleavage of pBR322 DNA, and complex 2 cleaves DNA more effectively than complex 1 under comparable experimental conditions. Furthermore, mechanism studies reveal that singlet oxygen (1O2) plays a significant role in the photocleavage.
Dynamics and Orientation of Parathion Dissolved in a Discotic Nematic Lyomesophase
Authors: Vera Alejandra , Ahumada Hernán , Bahamonde Victor , Montecinos Rodrigo , Araya-Maturana Ramiro , Muñoz Daniel , Weiss-López Boris E.
Published: February 2009

Parathion, an organophosphorous pesticide, presents serious hazards to the environment and health. It inhibits acetylcholinesterase, an enzyme incorporated in the cell membrane. A study on the behaviour of parathion in a lipid environment is interesting from environmental cleaning and biological perspectives. 2H NMR quadrupole splittings (ΔνQ) and longitudinal relaxation times (T1) of parathion-d4, dissolved in a nematic discotic lyomesophase made of tetradecyltrimethylammonium chloride/decanol (10% 1,1-dideuterodecanol)/water (0.1% D2O)/NaCl, have been measured. ΔνQ and T1 from DHO and 1,1-dideuterodecanol were also obtained. For a detailed understanding of the experimental results, a 19 ns molecular dynamics (MD) simulation of a bilayer fragment including three parathion molecules was calculated. Parathion is strongly attached to the aggregate and the solubilization increases the alignment of the interface components. Calculated densities show that parathion is located in the hydrophobic core, near the interface, and experiences an electrostatic interaction with the ammonium headgroups. On average, the molecule orients with the ring plane containing the bilayer normal.
Theoretical Study of the Adsorption of Carbon Monoxide on Pristine and Silicon-Doped Boron Nitride Nanotubes
Authors: Wang Ruoxi , Zhang Dongju
Published: February 2009

In order to explore the novel application of boron nitride nanotubes (BNNTs), we investigate reactivities of pristine and silicon-doped (Si-doped) (8,0) single-walled BNNTs towards the CO molecule by performing density functional theory calculations. Compared with weak physisorption on the pristine BNNT, the CO molecule presents strong chemical interaction with the Si-doped BNNT, as indicated by the calculated geometrical structures and electronic properties for these systems. It is suggested that doping BNNTs with silicon is expected to be a suitable strategy for adjusting the properties of BNNTs, and that Si-doped BNNTs are expected to find novel applications in nanotechnology.
A New Synthetic Route of 2-Aroyl- and 2-Benzyl-Benzofurans and their Application in the Total Synthesis of a Metabolite Isolated from Dorstenia gigas
Authors: Correa Christian , Cruz María del Carmen , Jiménez Fabiola , Zepeda L. Gerardo , Tamariz Joaquín
Published: February 2009

The Lewis acid-catalyzed cyclization of the (Z)-3-(dimethylamino)-2-aryloxy-1-arylprop-2-en-1-ones 4a–h leads to a regioselective and short synthesis of 2-aroylbenzofurans 2a–h. The Wolff–Kishner reduction of the latter yielded a series of substituted 2-benzylbenzofurans 3a–h. This methodology was applied in the first total synthesis of the metabolite 2-(4-hydroxybenzyl)-6-methoxybenzofuran 1, which was isolated from the tropical plant Dorstenia gigas, and obtained through a six-step route and in a 24% overall yield.
Iodination of Organic Compounds with Elemental Iodine in the Presence of Hydrogen Peroxide in Ionic Liquid Media
Authors: Pavlinac Jasminka , Laali Kenneth K. , Zupan Marko , Stavber Stojan
Published: February 2009

Iodo-transformations using the reagent system I2/H2O2 were studied in the water miscible ionic liquid (IL) 1-butyl-3-methyl imidazolium tetrafluoroborate (bmimBF4) and in water immiscible IL, 1-butyl-3-methyl imidazolium hexafluorophosphate (bmimPF6). Two different forms of H2O2 as mediators of iodination were investigated, namely 30% aq. H2O2 and urea-H2O2 (UHP) in solid form. The role of the oxidant during the course of a reaction could be distinguished based on the amount of reagent required for the most efficient transformation. Two types of iodo-functionalizations through an electrophilic process were observed depending on the structure of the substrates. Whereas ring iodination took place in the case of dimethoxy- and trimethoxy-benzenes, with arylalkyl ketones the alkyl group α to the carbonyl was regioselectively iodinated. The results were further evaluated in comparison with iodination using the reagent system I2/H2O2 in water as medium, and under solvent-free reaction conditions, in terms of efficiency, selectivity, mechanism, and the ‘green’ aspects. The reusability/recycling of water immiscible bmimPF6 was investigated for 1,3,5-trimethoxy benzene (1b), which required a 1/0.5/0.6 molar ratio of substrat/I2/oxidant, and for 1,2,3-trimethoxy benzene (1f), which required a 1/1/1 ratio for complete iodine introduction. In addition, the efficiency of iodination was tested by varying the substrates, and employing the recycled hydrophobic IL bmimPF6.
Synthesis and Characterization of Some Metal Complexes of 4,5-Diazafluoren-9-one and their Biological Effects on Human Carcinoma Cells
Authors: Lu Guo-Liang , Ho Cheuk-Lam , Wang Qiwei , Wong Wai-Yeung , Chui Chung-Hin , Wong Raymond Siu-Ming , Gambari Roberto , Lau Fung-Yi , Yuen Marcus Chun-Wah , Tong Cindy Sze-Wai , Chan Andrew Kit-Wah , Tang Johnny Cheuk-On , Ho Kwok-Ping , Cheng Gregory Yin-Ming
Published: February 2009

Three new transition metal complexes of 4,5-diazafluoren-9-one, [(DAFO)PdCl2], [(DAFO)PtCl2], and [(DAFO)ZnCl2], were prepared in good yields by the reactions between appropriate metal chloride precursors and 4,5-diazafluoren-9-one under ambient conditions. The structures of these metal complexes were established by spectroscopic (Fourier-transform IR, NMR, and fast-atom bombardment mass spectrometry) techniques. The possible biological activity of these compounds on three human cancer cell lines including Hep3B, MDAMB-231, and SKHep-1 was investigated. The results obtained showed that both zinc- and platinum-containing compounds exhibit a similar growth inhibitory effect on these three cancer cell lines when compared with the prototypical cis-platin. In contrast, the corresponding palladium congener is virtually biologically inactive in these trials.
Differential Pulse Anodic Stripping Voltammetric Determination of Cadmium(II) at a Glassy Carbon Electrode Modified with a Nano-TiO2/Chitosan Composite Film
Authors: Xie Zhimin , Fei Junjie , Huang Meihua
Published: February 2009

A simple and effective chemically modified electrode for the determination of cadmium(ii) was developed. The chemically modified electrode was prepared by modifying nano-TiO2/chitosan (nano-TiO2/CS) composite film onto a glassy carbon (GC) electrode. Compared with a bare GC electrode and a CS film-modified GC electrode, the nano-TiO2/CS composite film-coated GC electrode significantly improved the sensitivity of determining CdII. The effects of experimental parameters such as modifier composition in the GC electrode, pH of supporting electrolyte, accumulation potential and time were studied for analytical application. Under the optimized working conditions, the peak currents were linear with concentration over the range from 1.0 × 10–9 to 1.0 × 10–6 mol L–1 for CdII. The limit of detection is 2.0 × 10–10 mol L–1 CdII for 180-s accumulation. The application for the assay of trace levels of CdII in real water samples indicates that it is an economical and potent method.
X-Ray Structural Analysis of Ester and Ether Derivatives of 4,5-endo,endo-9,10-Dimethanonaphthalene-11-ol: Evidence for π - σCO* Participation in the Ground State
Authors: Jackson Wesley , White Jonathan M.
Published: February 2009

Application of the variable oxygen probe to the polycyclic alcohol 11 and its crystalline ester and ether derivatives provides evidence for a weak interaction between the neighbouring homo-allylic π-system and the C–OR bond; there is no evidence for interaction with the remote π-system. Analysis of the carbon–carbon bond distances in 11–14 reveals structural effects consistent with the manifestation of one of the two possible retro-Diels–Alder reactions in the ground state.
Changes in proportions of arsenic species within an Ecklonia radiata food chain
Authors: Foster Simon , Maher William , Krikowa Frank
Published: February 2009

Environmental context. The present study examines arsenic species in kelp and associated grazing animals of an Ecklonia radiata food chain. The study focusses on the changes in proportions of arsenoribosides obtained from E. radiata and mechanisms are proposed to explain the transformations of arsenoribosides observed in the organisms that graze on it.
Abstract. Total arsenic and arsenic species in the tissues of three growth stages of the macroalgae Ecklonia radiata and within organisms that feed on it are reported. Arsenic concentrations in E. radiata tissues varied from 40 to 153 μg g–1. Growth stage did not influence arsenic concentrations or arsenic species. E. radiata contained glycerol arsenoriboside (1–8.5%), phosphate arsenoriboside (10–22%) and sulfonate arsenoriboside (73–91%). Arsenic concentrations varied significantly among animal species and between tissues (5–123 μg g–1). Animals contained variable quantities of arsenobetaine (14–83%). Haliotis rubra tissues contained high concentrations of glycerol trimethylarsonioriboside (0.7–22%) and the fish Odax cyanomelas contained large quantities of phosphate arsenoriboside (25–64%) with little arsenobetaine (1.5–15%).
Arsenoribosides consumed from macroalgae are substantially converted or differentially accumulated as glycerol and phosphate arsenoribosides in animal tissues. In all animals, phosphate arsenoriboside would appear to be conserved or synthesised de novo. In gastropods, glycerol trimethylarsonioriboside and thio arsenic species are formed in the digestive system. Thus, the intermediate arsenic species that form a plausible pathway for the formation of arsenobetaine from dimethylarsenoribosides are present.
Assessment of caudal fin clip as a non-lethal technique for predicting muscle tissue mercury concentrations in largemouth bass
Authors: Ryba S. A. , Lake J. L. , Serbst J. R. , Libby A. D. , Ayvazian S.
Published: February 2009

Environmental context. In the development of fish consumption advisories, fisheries biologists routinely sacrifice fish and analyse muscle fillets in order to determine the extent of mercury contamination. Such lethal techniques may not be suitable for endangered species or limited fish populations from smaller-sized water bodies. We compared the measured total mercury concentrations in tail fin clips to that of muscle fillets and illustrated that tail fin clips may be used as an accurate tool for predicting mercury in muscle tissue. This is the first study on the use of tail fin clips to predict mercury levels in the muscle tissue of largemouth bass with minimal impact on the fish.
Abstract. The statistical relationship between total mercury (Hg) concentration in clips from the caudal fin and muscle tissue of largemouth bass (Micropterus salmoides) from 26 freshwater sites in Rhode Island, USA was developed and evaluated to determine the utility of fin clip analysis as a non-lethal and convenient method for predicting mercury concentrations in tissues. The relationship of total Hg concentrations in fin clips and muscle tissue showed an r2 of 0.85 and may be compared with an r2 of 0.89 for Hg concentrations between scales and muscle tissue that was determined in a previous study on largemouth bass. The Hg concentration in fin clip samples (mean = 0.261 μg g–1 (dry)) was more than a factor of twenty greater than in the scale samples (mean = 0.012 μg g–1 (dry)). Therefore, fin clips may be a more responsive non-lethal predictor of muscle-Hg concentrations than scale in fish species which may have reduced Hg concentrations.
N,N-Diethyl-p-phenylenediamine effectiveness in analysis of polysulfides and polythionates in water
Authors: Kariuki Stephen , Babady-Bila Philippe , Duquette Breanna
Published: February 2009

Environmental context. The importance of hydrogen sulfide as well as some of the reduced sulfur species such as polysulfides as environmental pollutants is a result of their toxicity, unpleasant odour, and their reactivity with metals and metallic ions found in various environmental samples. Although known to be popular, the effectiveness of N,N-diethyl-p-phenylenediamine and other related compounds in the spectrophotometric analysis of such sulfur compounds in water as well as in other environmental samples has not been fully investigated. Our results show that although the quantification of simple sulfides in the environmental samples may be easily accomplished spectrophotometrically by using N,N-diethyl-p-phenylenediamine, the level of difficulty in analysing such compounds may increase with their increasing sulfur chain.
Abstract. The analysis of polysulfides, polythionates and other sulfur species likely to be found in poorly aerated environmental samples such as water is presented. In-depth spectrophotometric testing carried out using N,N-diethyl-p-phenylenediamine shows that the well known acidification-and-purge method is not sufficiently suitable for the analysis of polysulfides and other low oxidation-state sulfur compounds that contain a sulfur chain longer than two. Further, this study finds that the use of chromium(II) which acts as a reducing agent to the sulfur-containing compounds improves the spectrophotometric analysis of the polysulfides and polythionates in water, but only slightly. The extent of reduction of polysulfides and polythionates to sulfide by chromium appears dependent upon the oxidation state of sulfur as well as the chain length in the polysulfidic compounds.
Sexual difficulties and help-seeking among mature adults in Australia: results from the Global Study of Sexual Attitudes and Behaviours
Authors: Moreira Edson D. , Glasser Dale B. , King Rosie , Duarte Fernanda Gross , Gingell Clive , Group for the GSSAB Investigators'
Published: February 2009

Background: The Global Study of Sexual Attitudes and Behaviours was a survey of 27 500 men and women in 29 countries. Here we report the sexual activity, the prevalence of sexual difficulties and related help-seeking behaviour among participants in Australia. Methods: A telephone survey was conducted in Australia in 2001–2002, with interviews based on a standardised questionnaire. A total of 1500 individuals (750 men and 750 women) aged 40 to 80 years completed the survey. The questionnaire covered demographic information, overall health, and sexual behaviours, attitudes and beliefs. Results: Overall, 83% of men and 74% of women had engaged in sexual intercourse during the 12 months preceding the interview, and 38% of all men and 29% of all women engaged in sexual intercourse more than once a week. Early ejaculation (23%), erectile difficulties (21%) and a lack of sexual interest (18%) were the most common male sexual difficulties. The most frequently reported female sexual difficulties were: lack of sexual interest (33%), lubrication difficulties (26%) and an inability to reach orgasm (25%). Older age was a significant predictor of male erectile difficulties and of lubrication difficulties in women. Only a minority of men and women had sought help for their sexual difficulty(ies) from a health professional. Conclusions: Many middle-aged and older adults in Australia report continued sexual interest and sexual activity. Several sexual difficulties are highly prevalent in this population, but those experiencing these difficulties rarely seek medical help. This may be because they do not perceive such difficulties as serious or sufficiently upsetting.
Sexually transmissible infection management practices among primary care physicians in Singapore
Authors: Chan Roy K. W. , Tan Hiok Hee , Chio Martin T. W. , Sen Priya , Ho Kar Woon , Wong Mee Lian
Published: February 2009

Background: Primary care physicians manage a significant number of sexually transmissible infections (STI); however, there has not been a survey to assess the standard of medical care, completeness of notifications, provision of counselling and contact tracing by primary care physicians in Singapore. Methods: An anonymous postal survey was conducted in which 1557 questionnaires were mailed out to general practitioners (GP), and government primary care and emergency department doctors. Results: In all, 736 questionnaires (47.3%) were returned, and the majority of respondents were graduates from the local medical school, worked in solo or group practices and were males. One hundred and thirty doctors (17.7%) indicated they had received training attachments or postings in dermato-venereology departments. Almost one-third (30.8%) had been working as doctors for fewer than 10 years and 87.8% reported that they managed STI in their practice. Almost half did not investigate genital discharge patients, and one-third would still use ciprofloxacin to treat discharges. In the management of ulcers, over half indicated that they would order syphilis serology, and a significant minority would use parenteral penicillin. Most doctors provided history taking, screening for other STI, testing for HIV infection and STI counselling. A small minority of doctors undertook contact tracing, and there was incomplete notification of many STI. Conclusions: Overall medical management of STI by primary care physicians was acceptable. Skills in contact tracing and reminders on disease notification are areas that need particular attention.
New therapeutic agents in the management of HIV: an overview of darunavir for clinicians
Authors: Rotty Jessica , Hoy Jennifer
Published: February 2009

This overview will provide the reader with summarised information about darunavir, a new protease inhibitor licenced for the treatment of drug resistant HIV-infection. Darunavir is a promising new drug with good clinical efficacy data and safety profile. In this overview clinicians will be updated on clinical efficacy data, side-effects, resistance profile and drug interactions. The overview should give clinicians a sound understanding of when and how to use this new protease inhibitor in the treatment of HIV-infection.
Are printed sexually transmissible infection materials for patients appropriate? A physician perspective
Authors: Khan Asaduzzaman , Plummer David
Published: February 2009

The data from a postal survey of 409 general practitioners (GPs) practicing in New South Wales are analysed to explore GPs’ concerns, if any, about available printed information materials on sexually transmissible infections (STI) for patients. Just over half (55%) of GPs considered the materials for patients to be inadequate and/or inappropriate with 18% considering the materials as too technical for many patients and 13% considering the materials mostly out of date. Over a fifth reported that either STI materials were not available in their clinic or they did not know where to get those materials.
Holocene vegetation and fire regimes in subalpine and mixed conifer forests, southern Rocky Mountains, USA
Authors: Anderson R. S. , Allen C. D. , Toney J. L. , Jass R. B. , Bair A. N.
Published: February 2009

Our understanding of the present forest structure of western North America hinges on our ability to determine antecedent forest conditions. Sedimentary records from lakes and bogs in the southern Rocky Mountains of Colorado and New Mexico provide information on the relationships between climate and vegetation change, and fire history since deglaciation. We present a new pollen record from Hunters Lake (Colorado) as an example of a high-elevation vegetation history from the southern Rockies. We then present a series of six sedimentary records from ~2600 to 3500-m elevation, including sites presently at the alpine–subalpine boundary, within the Picea engelmannii–Abies lasiocarpa forest and within the mixed conifer forest, to determine the history of fire in high-elevation forests there. High Artemisia and low but increasing percentages of Picea and Pinus suggest vegetation prior to 13 500 calendar years before present (cal yr BP) was tundra or steppe, with open spruce woodland to ~11 900 cal yr BP. Subalpine forest (Picea engelmannii, Abies lasiocarpa) existed around the lake for the remainder of the Holocene. At lower elevations, Pinus ponderosa and/or contorta expanded 11 900 to 10 200 cal yr BP; mixed conifer forest expanded ~8600 to 4700 cal yr BP; and Pinus edulis expanded after ~4700 cal yr BP. Sediments from lake sites near the alpine–subalpine transition contained five times less charcoal than those entirely within subalpine forests, and 40 times less than bog sites within mixed conifer forest. Higher fire episode frequencies occurred between ~12 000 and 9000 cal yr BP (associated with the initiation or expansion of south-west monsoon and abundant lightning, and significant biomass during vegetation turnover) and at ~2000–1000 cal yr BP (related to periodic droughts during the long-term trend towards wetter conditions and greater biomass). Fire episode frequencies for subalpine–alpine transition and subalpine sites were on average 5 to 10 fire events/1000 years over the Holocene, corresponding to one fire event every ~100 to 200 years. (5) Our Holocene-length sedimentary charcoal records provide additional evidence for the anomalous nature of the 20th-century fire regime, where fires were largely suppressed as a national policy.
Tadpoles of invasive cane toads (Bufo marinus) do not respond behaviourally to chemical cues from tadpoles of four species of Australian frogs
Authors: Hagman Mattias , Shine Richard
Published: February 2009

In previous work, we have shown that tadpoles of invasive cane toads (Bufo marinus) strongly avoid scent cues from crushed conspecific tadpoles. Thus, identifying the identity of the chemical involved may provide novel approaches to toad control, by manipulating the behaviour of toad tadpoles. A first step in the search for that chemical is to see whether toad tadpoles are similarly repelled by chemical cues from crushed tadpoles of other species. Our experimental trials with four native Australian frogs (three hylids, one myobatrachid) show that toads do not respond to chemical cues from these taxa. Hence, the specific chemicals that induce avoidance cannot be generic ones (e.g. body fluids, tissue fragments) but instead, must reflect some underlying chemical divergence in body composition between the tadpoles of cane toads versus the other anurans that we have tested.
Geographic variation in the advertisement call of Crinia signifera (Anura:Myobatrachidae) on Kangaroo Island and across southern south-eastern Australia
Authors: Littlejohn Murray J.
Published: February 2009

The male advertisement call of anuran amphibians has a major role in mate choice, and regional variation in this attribute can act as an indicator of speciation and a marker for genetic differentiation. As part of a regional study of geographic variation in the male advertisement call of Crinia signifera across south-eastern Australia and adjacent larger continental islands, samples of advertisement calls from two populations on Kangaroo Island and two populations on the adjacent Fleurieu Peninsula were compared. Four call attributes were considered: pulse number, call duration, pulse rate and dominant frequency. Pulse number is considered the most reliable for comparative purposes because it is not influenced by effective temperature or audio recording and analysis. The two island populations (central and eastern, ~24 km apart) differ significantly in pulse number, with contact but no overlap of interquartile ranges. The eastern sample differs markedly from those on the nearby Fleurieu Peninsula – which are both similar to the more distant central island sample. Geographic variation in pulse number in these four samples and 11 others from two recent publications is then interpreted in the light of land bridges and lower temperatures of the late Pleistocene and early Holocene.
Movements and distribution of dugongs (Dugong dugon) in a macro-tidal environment in northern Australia
Authors: Whiting Scott D.
Published: February 2009

A combination of aerial surveys, community sightings and satellite tracking revealed distribution, habitat, relative densities and spatial use of individual dugongs in the Darwin region of the Northern Territory. Aerial surveys in both the wet and dry seasons estimated relatively low densities of dugongs. Most group sightings (73% of all sightings) and densities up to 0.54 dugongs km−2 occurred in one of the four blocks surveyed. This block contained the Vernon Islands and large macro-tidal algal rocky reefs. Two dugongs tracked using satellite transmitters were captured above these reefs and kept a close association with similar reef types during most of their tracking periods of 53 and 154 days. Tracking revealed that dugongs used multiple and distinct areas for periods of several days to over 80 days and utilised coastal sections of up to 300 km in length. This indicates that dugong management in the Darwin region requires the consideration of large spatial scales, multiple habitat types and rocky reef habitat. Community sightings were an important information source and revealed locations of dugongs not identified with either the aerial surveys or satellite tracking.
Male copulation frequency, sperm competition and genital damage in the golden orb-web spider (Nephila plumipes)
Authors: Schneider Jutta M. , Herberstein Marie E. , Bruce Matthew J. , Kasumovic Michael M. , Thomas Melissa L. , Elgar Mark A.
Published: February 2009

Copulation in many sexually cannibalistic spiders is associated with a loss of function of the male reproductive organs and, as a consequence, males that survive sexual cannibalism may nevertheless be unable to subsequently copulate successfully. Sexual cannibalism is common in the Australian golden orb-web spider (Nephila plumipes), in which the tip of the conductor typically breaks during copulation. Thus, male mating frequency may be physiologically limited to two females, irrespective of the male’s ability to avoid cannibalism or the opportunity to locate and court additional, receptive females. Laboratory experiments revealed that the likelihood of the conductor breaking depends upon the copulatory history of the female insemination duct: males were more likely to break their conductor if they inseminated a ‘virgin’ rather than ‘mated’ insemination duct. However, the choice of insemination duct did not influence the duration of copulation or quantity of sperm transferred. In field populations, the proportion of males with both conductors broken increased during the course of the mating season, but while males with broken conductors did not copulate successfully with virgin females, they were nevertheless observed on the webs of immature females. We suggest that male N. plumipes with broken conductors on the webs of females are most likely mate guarding, as this appears to be the most effective mechanism of securing paternity.
Laser photogrammetry to determine dorsal fin size in a population of bottlenose dolphins from Doubtful Sound, New Zealand
Authors: Rowe Lucy E. , Dawson Stephen M.
Published: February 2009

Laser photogrammetry (also known as laser-metrics) can provide valuable morphological data but the measurement error associated with the technique has not been quantified. Here laser-metrics were used to measure the dorsal fins of an entire resident population of bottlenose dolphins (Tursiops truncatus) from Doubtful Sound, New Zealand. Dorsal fin base length, height and surface area were measured from dorsal fin photographs. Sources of measurement error were estimated by repeatedly measuring multiple photographs of dorsal fins of known individuals. Measurement error accounted for less than 6% of the total variation in dorsal fin base length and height, indicating that the technique was repeatable. Adults were the only age-class to express sexual dimorphism, with males significantly larger than females in all measurements. The relationship between dorsal fin height and base length was significantly different between male and female adults: dorsal fins of males were proportionately taller. Laser photogrammetry is an inexpensive and non-invasive measurement technique that can provide valuable size data when used in conjunction with routine dorsal fin photo-identification studies.
Growth and development of an araneophagic assassin bug, Stenolemus bituberus (Heteroptera:Reduviidae)
Authors: Wignall Anne E. , Taylor Phillip W.
Published: February 2009

Stenolemus bituberus Stål is an araneophagic Australian assassin bug (i.e. it preys on web-building spiders). As a step towards more thoroughly understanding the behaviour and predatory biology of this species, here we provide baseline information about development. During its development, there are 5 instars, with the 4th instar being the longest. The length of the 4th instar was consistent with this species’ phenology in the field and corresponds to the winter months. Mortality during the 4th instar was higher than in any other instar. Sexes were similar in size until the 5th instar (width across eyes was greater for males than for females, a pattern continued into the adult stage). Overall, adult females tended to be larger than males. The growth rate between instars varied according to instar, although the transition from 5th instar to adult was generally associated with a decrease in growth rate compared with other transitions. Width across the eyes was the only metric that exhibited a sex difference in growth rate, with males growing more than females during the transition from 4th to 5th instar.
Sensitive dependence of the motion of a legged robot on granular media
Authors: Li Chen , Umbanhowar Paul B. , Komsuoglu Haldun , Koditschek Daniel E. , Goldman Daniel I.
Published: February 2009

Legged locomotion on flowing ground (e.g., granular media) is unlike locomotion on hard ground because feet experience both solid- and fluid-like forces during surface penetration. Recent bioinspired legged robots display speed relative to body size on hard ground comparable with high-performing organisms like cockroaches but suffer significant performance loss on flowing materials like sand. In laboratory experiments, we study the performance (speed) of a small (2.3 kg) 6-legged robot, SandBot, as it runs on a bed of granular media (1-mm poppy seeds). For an alternating tripod gait on the granular bed, standard gait control parameters achieve speeds at best 2 orders of magnitude smaller than the 2 body lengths/s (≈60 cm/s) for motion on hard ground. However, empirical adjustment of these control parameters away from the hard ground settings restores good performance, yielding top speeds of 30 cm/s. Robot speed depends sensitively on the packing fraction φ and the limb frequency ω, and a dramatic transition from rotary walking to slow swimming occurs when φ becomes small enough and/or ω large enough. We propose a kinematic model of the rotary walking mode based on generic features of penetration and slip of a curved limb in granular media. The model captures the dependence of robot speed on limb frequency and the transition between walking and swimming modes but highlights the need for a deeper understanding of the physics of granular media.
Maize AMEIOTIC1 is essential for multiple early meiotic processes and likely required for the initiation of meiosis
Authors: Pawlowski Wojciech P. , Wang Chung-Ju Rachel , Golubovskaya Inna N. , Szymaniak Jessica M. , Shi Liang , Hamant Olivier , Zhu Tong , Harper Lisa , Sheridan William F. , Cande W. Zacheus
Published: February 2009

Molecular mechanisms that initiate meiosis have been studied in fungi and mammals, but little is known about the mechanisms directing the meiosis transition in other organisms. To elucidate meiosis initiation in plants, we characterized and cloned the
ameiotic1
(
am1
) gene, which affects the transition to meiosis and progression through the early stages of meiotic prophase in maize. We demonstrate that all meiotic processes require
am1
, including expression of meiosis-specific genes, establishment of the meiotic chromosome structure, meiosis-specific telomere behavior, meiotic recombination, pairing, synapsis, and installation of the meiosis-specific cytoskeleton. As a result, in most
am1
mutants premeiotic cells enter mitosis instead of meiosis. Unlike the genes involved in initiating meiosis in yeast and mouse,
am1
also has a second downstream function, whereby it regulates the transition through a novel leptotene–zygotene checkpoint, a key step in early meiotic prophase. The
am1
gene encodes a plant-specific protein with an unknown biochemical function. The AM1 protein is diffuse in the nucleus during the initiation of meiosis and then binds to chromatin in early meiotic prophase I when it regulates the leptotene–zygotene progression.
Hippocampal theta rhythm and its coupling with gamma oscillations require fast inhibition onto parvalbumin-positive interneurons
Authors: Wulff Peer , Ponomarenko Alexey A. , Bartos Marlene , Korotkova Tatiana M. , Fuchs Elke C. , Bähner Florian , Both Martin , Tort Adriano B. L. , Kopell Nancy J. , Wisden William , Monyer Hannah
Published: February 2009

Hippocampal theta (5–10 Hz) and gamma (35–85 Hz) oscillations depend on an inhibitory network of GABAergic interneurons. However, the lack of methods for direct and cell-type-specific interference with inhibition has prevented better insights that help link synaptic and cellular properties with network function. Here, we generated genetically modified mice (PV-Δγ
2
) in which synaptic inhibition was ablated in parvalbumin-positive (PV+) interneurons. Hippocampal local field potential and unit recordings in the CA1 area of freely behaving mice revealed that theta rhythm was strongly reduced in these mice. The characteristic coupling of theta and gamma oscillations was strongly altered in PV-Δγ
2
mice more than could be accounted for by the reduction in theta rhythm only. Surprisingly, gamma oscillations were not altered. These data indicate that synaptic inhibition onto PV+ interneurons is indispensable for theta- and its coupling to gamma oscillations but not for rhythmic gamma-activity in the hippocampus. Similar alterations in rhythmic activity were obtained in a computational hippocampal network model mimicking the genetic modification, suggesting that intrahippocampal networks might contribute to these effects.
Reduction of cholesterol synthesis in the mouse brain does not affect amyloid formation in Alzheimer's disease, but does extend lifespan
Authors: Halford Rebekkah W. , Russell David W.
Published: February 2009

Alterations in cellular cholesterol synthesis or content in cultured neurons affect the cleavage of amyloid precursor protein to amyloidogenic Aβ
40
and Aβ
42
peptides characteristic of Alzheimer's disease. To determine whether a decrease in cholesterol synthesis affects amyloid precursor protein processing in vivo, we crossed cholesterol 24-hydroxylase knockout mice, which exhibit a 50% reduction in brain sterol synthesis, with transgenic mice [B6.Cg-Tg(APPswe, PSEN1E9)85Dbo/J] that develop Alzheimer's disease-like pathology. Amyloid precursor protein expression and amyloid plaque deposition in the cortex and hippocampus of male and female Alzheimer's disease mice between the ages of 3 to 15 months were similar in the presence and absence of cholesterol 24-hydroxylase. A modest but statistically significant decline in insoluble Aβ
42
peptide levels was detected in the hippocampus of 12-month-old knockout/Alzheimer's disease males. The levels of insoluble Aβ
40
and Aβ
42
peptides in 15-month-old knockout/Alzheimer's disease females were also reduced slightly. Although amyloid plaque accumulation did not affect brain sterol or fatty acid synthesis rates in 24-hydroxylase WT or knockout mice, loss of one or both cholesterol 24-hydroxylase alleles increased longevity in Alzheimer's disease mice. These studies suggest that reducing de novo cholesterol synthesis in the brain will not substantially alter the course of Alzheimer's disease, but may confer a survival advantage.