Publications by authors named "Gregory Jordan"

79 Publications

Diversity and abundance of soil microbial communities decline, and community compositions change with severity of post-logging fire.

Mol Ecol 2021 Mar 27. Epub 2021 Mar 27.

CSIRO, Hobart, Australia.

Understanding the effects of logging and fire on forest soil communities is integral to our knowledge of forest ecology and effective resource management. The resulting changes in soil biota have substantial impacts on forest succession and associated ecosystem processes. We quantified bacterial and fungal abundance, diversity and community composition across a logging and burn severity gradient, approximately one month after fire, in temperate wet eucalypt forests in Tasmania, Australia. Using amplicon sequencing and real-time quantitative PCR of the bacterial 16S rRNA gene and fungal ITS1 region, we demonstrate that (i) burn severity is a strong driver of soil microbial community composition, (ii) logging and high severity burning substantially reduce the biomass and diversity of soil bacteria and fungi, and (iii) the impacts of logging and burning on soil microbial communities are largely restricted to the top 10 cm of soil, with weak impacts on the subsoil. The impacts of disturbance on microbial community composition are greater than the effects of site-to-site edaphic differences. Fire also drives more divergence in community composition than logging alone. Key microbial taxa driving differences in severely burnt soils include bacterial genera implicated in plant-growth promotion and producing antifungal compounds as well as saprotrophic fungi that are also capable of forming ectomycorrhizal associations. Our research suggests that low-moderate severity burns are important for maintaining diversity and biomass in soil microbial communities but having a range of burn severities across a site contributes to the overall diversity of habitat conditions providing for both microbial and plant diversity.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/mec.15900DOI Listing
March 2021

A Novel Patient Values Tab for the Electronic Health Record: A User-Centered Design Approach.

J Med Internet Res 2021 02 17;23(2):e21615. Epub 2021 Feb 17.

Memorial Sloan Kettering Cancer Center, New York, NY, United States.

Background: The COVID-19 pandemic has shined a harsh light on a critical deficiency in our health care system: our inability to access important information about patients' values, goals, and preferences in the electronic health record (EHR). At Memorial Sloan Kettering Cancer Center (MSK), we have integrated and systematized health-related values discussions led by oncology nurses for newly diagnosed cancer patients as part of routine comprehensive cancer care. Such conversations include not only the patient's wishes for care at the end of life but also more holistic personal values, including sources of strength, concerns, hopes, and their definition of an acceptable quality of life. In addition, health care providers use a structured template to document their discussions of patient goals of care.

Objective: To provide ready access to key information about the patient as a person with individual values, goals, and preferences, we undertook the creation of the Patient Values Tab in our center's EHR to display this information in a single, central location. Here, we describe the interprofessional, interdisciplinary, iterative process and user-centered design methodology that we applied to build this novel functionality as well as our initial implementation experience and plans for evaluation.

Methods: We first convened a working group of experts from multiple departments, including medical oncology, health informatics, information systems, nursing informatics, nursing education, and supportive care, and a user experience designer. We conducted in-depth, semistructured, audiorecorded interviews of over 100 key stakeholders. The working group sought consensus on the tab's main content, homing in on high-priority areas identified by the stakeholders. The core content was mapped to various EHR data sources. We established a set of high-level design principles to guide our process. Our user experience designer then created wireframes of the tab design. The designer conducted usability testing with physicians, nurses, and other health professionals. Data validation testing was conducted.

Results: We have already deployed the Patient Values Tab to a pilot sample of users in the MSK Gastrointestinal Medical Oncology Service, including physicians, advanced practice providers, nurses, and administrative staff. We have early evidence of the positive impact of this EHR innovation. Audit logs show increasing use. Many of the initial user comments have been enthusiastically positive, while others have provided constructive suggestions for additional tab refinements with respect to format and content.

Conclusions: It is our challenge and obligation to enrich the EHR with information about the patient as a person. Realization of this capability is a pressing public health need requiring the collaboration of technological experts with a broad range of clinical leaders, users, patients, and families to achieve solutions that are both principled and practical. Our new Patient Values Tab represents a step forward in this important direction.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.2196/21615DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7929751PMC
February 2021

A Permeable Cuticle, Not Open Stomata, Is the Primary Source of Water Loss From Expanding Leaves.

Front Plant Sci 2020 23;11:774. Epub 2020 Jun 23.

Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN, United States.

High rates of water loss in young, expanding leaves have previously been attributed to open stomata that only develop a capacity to close once exposed to low humidity and high abscisic acid (ABA) levels. To test this model, we quantified water loss through stomata and cuticle in expanding leaves of . Stomatal anatomy and density were observed using scanning electron microscopy. Leaves of less than 5 days after emergence have no stomata; therefore, water loss from these leaves must be through the cuticle. Once stomata develop, they are initially covered in a cuticle and have no outer cuticular ledge, implying that the majority of water lost from leaves in this phase of expansion is through the cuticle. Foliar ABA levels are high when leaves first expand and decline exponentially as leaves expand. Once leaves have expanded to maximum size, ABA levels are at a minimum, an outer cuticular ledge has formed on most stomata, cuticular conductance has declined, and most water loss is through the stomata. Similar sequences of events leading to stomatal regulation of water loss in expanding leaves may be general across angiosperms.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fpls.2020.00774DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7325764PMC
June 2020

Accuracy of ancestral state reconstruction for non-neutral traits.

Sci Rep 2020 05 6;10(1):7644. Epub 2020 May 6.

School of Natural Sciences, University of Tasmania, Private Bag 55, Hobart, Tas, 7001, Australia.

The assumptions underpinning ancestral state reconstruction are violated in many evolutionary systems, especially for traits under directional selection. However, the accuracy of ancestral state reconstruction for non-neutral traits is poorly understood. To investigate the accuracy of ancestral state reconstruction methods, trees and binary characters were simulated under the BiSSE (Binary State Speciation and Extinction) model using a wide range of character-state-dependent rates of speciation, extinction and character-state transition. We used maximum parsimony (MP), BiSSE and two-state Markov (Mk2) models to reconstruct ancestral states. Under each method, error rates increased with node depth, true number of state transitions, and rates of state transition and extinction; exceeding 30% for the deepest 10% of nodes and highest rates of extinction and character-state transition. Where rates of character-state transition were asymmetrical, error rates were greater when the rate away from the ancestral state was largest. Preferential extinction of species with the ancestral character state also led to higher error rates. BiSSE outperformed Mk2 in all scenarios where either speciation or extinction was state dependent and outperformed MP under most conditions. MP outperformed Mk2 in most scenarios except when the rates of character-state transition and/or extinction were highly asymmetrical and the ancestral state was unfavoured.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41598-020-64647-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7203120PMC
May 2020

Links between environment and stomatal size through evolutionary time in Proteaceae.

Proc Biol Sci 2020 01 29;287(1919):20192876. Epub 2020 Jan 29.

Discipline of Biological Sciences, University of Tasmania, Private Bag 55, Hobart, Tasmania 7001, Australia.

The size of plant stomata (adjustable pores that determine the uptake of CO and loss of water from leaves) is considered to be evolutionarily important. This study uses fossils from the major Southern Hemisphere family Proteaceae to test whether stomatal cell size responded to Cenozoic climate change. We measured the length and abundance of guard cells (the cells forming stomata), the area of epidermal pavement cells, stomatal index and maximum stomatal conductance from a comprehensive sample of fossil cuticles of Proteaceae, and extracted published estimates of past temperature and atmospheric CO. We developed a novel test based on stochastic modelling of trait evolution to test correlations among traits. Guard cell length increased, and stomatal density decreased significantly with decreasing palaeotemperature. However, contrary to expectations, stomata tended to be smaller and more densely packed at higher atmospheric CO. Thus, associations between stomatal traits and palaeoclimate over the last 70 million years in Proteaceae suggest that stomatal size is significantly affected by environmental factors other than atmospheric CO. Guard cell length, pavement cell area, stomatal density and stomatal index covaried in ways consistent with coordinated development of leaf tissues.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1098/rspb.2019.2876DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7015321PMC
January 2020

Leaf hydraulic conductance is linked to leaf symmetry in bifacial, amphistomatic leaves of sunflower.

J Exp Bot 2020 05;71(9):2808-2816

School of Natural Sciences, University of Tasmania, Hobart, Tasmania, Australia.

The hydraulic implications of stomatal positioning across leaf surfaces and the impact on internal water flow through amphistomatic leaves are not currently well understood. Amphistomaty potentially provides hydraulic efficiencies if the majority of hydraulic resistance in the leaf exists outside the xylem in the mesophyll. Such a scenario would mean that the same xylem network could equally supply a hypostomatic or amphistomatic leaf. Here we examine leaves of Helianthus annuus to determine whether amphistomaty in this species is associated with higher hydraulic efficiency compared with hypostomatic leaves. We identified asymmetry in the positioning of minor veins which were significantly closer to the abaxial than the adaxial leaf surface, combined with lower Kleaf when transpiration was driven through the adaxial rather than the abaxial surface. We also identified a degree of coordination in stomatal behaviour driven by leaf hydraulics, where the hydraulic conditions experienced by an individual leaf surface affected the stomatal behaviour on the opposite surface. We found no advantage to amphistomaty based on efficiencies in construction costs of the venous system, represented by vein density:stomatal density, only limited hydraulic independence between leaf surfaces. These results suggest that amphistomaty does not substantially increase whole-leaf hydraulic efficiency.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/jxb/eraa035DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7210757PMC
May 2020

TRY plant trait database - enhanced coverage and open access.

Glob Chang Biol 2020 01 31;26(1):119-188. Epub 2019 Dec 31.

Arizona State University, Tempe, AZ, USA.

Plant traits-the morphological, anatomical, physiological, biochemical and phenological characteristics of plants-determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits-almost complete coverage for 'plant growth form'. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait-environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/gcb.14904DOI Listing
January 2020

Distinct Drimane Chemotypes in Tasmanian Mountain Pepper (): Differences in the Profiles of Pungent Leaf Phytochemicals Associated with Altitudinal Cline.

J Agric Food Chem 2020 Jan 18;68(1):315-322. Epub 2019 Dec 18.

This study assesses whether the distinct altitudinal cline in leaf morphology (decreased leaf width and length with increased altitude) in Tasmanian mountain pepper () is associated with changes in the leaf chemistry of wild populations from different ecological landscapes and altitudes. The presence of distinct pungent drimane sesquiterpenoid chemotypes was identified: subalpine woodland and wet sclerophyll forest chemotypes. Isolation studies and analysis of extracts revealed that wet sclerophyll forest populations featured polygodial as the principal terpenoid, with profiles similar to the commercial cultivars sampled. In contrast, the subalpine woodland populations contained the drimane sesquiterpenoids 1β-acetoxy-9-deoxyisomuzigadial and 3β-acetoxydrimenin and the conspicuous absence of the pungent principle polygodial.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.jafc.9b05703DOI Listing
January 2020

Nitric Oxide Generation On Demand for Biomedical Applications via Electrocatalytic Nitrite Reduction by Copper BMPA- and BEPA-Carboxylate Complexes.

ACS Catal 2019 Sep 15;9(9):7746-7758. Epub 2019 Jul 15.

Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, MI 48109.

Intravascular (IV) catheters are essential devices in the hospital that are used to monitor a patient's blood and for administering drugs or nutrients. However, IV catheters are also prone to blood clotting at the point of insertion and infection by formation of robust bacterial biofilms on their surface. Nitric oxide (NO) is ideally suited to counteract both of these problems, due to its antimicrobial properties and its ability to inhibit platelet activation/aggregation. One way to equip catheters with NO releasing properties is by electrocatalytic nitrite reduction to NO by copper complexes in a multi-lumen configuration. In this work, we systematically investigate six closely related Cu(II) BMPA- and BEPA-carboxylate complexes (BMPA = bis-(2-methylpyridyl)amine); BEPA = bis-(2-ethylpyridyl)amine), using carboxylate groups of different chain lengths. The corresponding Cu(II) complexes were characterized using UV-Vis, EPR spectroscopy, and X-ray crystallography. Using detailed cyclic voltammetry (CV) and bulk electrocatalyic studies (with real-time NO quantification), in aqueous buffer, pH 7.4, we are able to derive clear reactivity relations between the ligand structures of the complexes, their Faradaic efficiencies for NO generation, their turnover frequencies (TOFs), and their redox potentials. Our results show that the complex [Cu(BEPA-Bu)](OAc) is the best catalyst with a high Faradaic efficiency over large nitrite concentration ranges and the expected best tolerance to oxygen levels. For this species, the more positive redox potential suppresses NO disproportionation, which is a major Achilles heel of the (faster) catalysts with the more negative reduction potentials.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acscatal.9b01520DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6779156PMC
September 2019

Nitric Oxide Generation On Demand for Biomedical Applications via Electrocatalytic Nitrite Reduction by Copper BMPA- and BEPA-Carboxylate Complexes.

ACS Catal 2019 Sep 15;9(9):7746-7758. Epub 2019 Jul 15.

Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, MI 48109.

Intravascular (IV) catheters are essential devices in the hospital that are used to monitor a patient's blood and for administering drugs or nutrients. However, IV catheters are also prone to blood clotting at the point of insertion and infection by formation of robust bacterial biofilms on their surface. Nitric oxide (NO) is ideally suited to counteract both of these problems, due to its antimicrobial properties and its ability to inhibit platelet activation/aggregation. One way to equip catheters with NO releasing properties is by electrocatalytic nitrite reduction to NO by copper complexes in a multi-lumen configuration. In this work, we systematically investigate six closely related Cu(II) BMPA- and BEPA-carboxylate complexes (BMPA = bis-(2-methylpyridyl)amine); BEPA = bis-(2-ethylpyridyl)amine), using carboxylate groups of different chain lengths. The corresponding Cu(II) complexes were characterized using UV-Vis, EPR spectroscopy, and X-ray crystallography. Using detailed cyclic voltammetry (CV) and bulk electrocatalyic studies (with real-time NO quantification), in aqueous buffer, pH 7.4, we are able to derive clear reactivity relations between the ligand structures of the complexes, their Faradaic efficiencies for NO generation, their turnover frequencies (TOFs), and their redox potentials. Our results show that the complex [Cu(BEPA-Bu)](OAc) is the best catalyst with a high Faradaic efficiency over large nitrite concentration ranges and the expected best tolerance to oxygen levels. For this species, the more positive redox potential suppresses NO disproportionation, which is a major Achilles heel of the (faster) catalysts with the more negative reduction potentials.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acscatal.9b01520DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6779156PMC
September 2019

Extended differentiation of veins and stomata is essential for the expansion of large leaves in Rheum rhabarbarum.

Am J Bot 2018 12 26;105(12):1967-1974. Epub 2018 Nov 26.

Purdue Center for Plant Biology, Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN, 47907, USA.

Premise Of The Study: The densities of veins and stomata govern leaf water supply and gas exchange. They are coordinated to avoid overproduction of either veins or stomata. In many species, where leaf area is greater at low light, this coordination is primarily achieved through differential cell expansion, resulting in lower stomatal and vein density in larger leaves. This mechanism would, however, create highly inefficient leaves in species in which leaf area is greater at high light. Here we investigate the role of cell expansion and differentiation as regulators of vein and stomatal density in Rheum rhabarbarum, which produces large leaves under high light.

Methods: Rheum rhabarbarum plants were grown under full sunlight and 7% of full sunlight. Leaf area, stomatal density, and vein density were measured from leaves harvested at different intervals.

Key Results: Leaves of R. rhabarbarum expanded at high light were six times larger than leaves expanded at low light, yet vein and stomatal densities were similar. In high light-expanded leaves, minor veins were continuously initiated as the leaves expanded, while an extended period of stomatal initiation, compared to leaves expanded at low light, occurred early in leaf development.

Conclusions: We demonstrate that R. rhabarbarum adjusts the initiation of stomata and minor veins at high light, allowing for the production of larger leaves uncoupled from lower vein and stomatal densities. We also present evidence for an independent control of vein and stomatal initiation, suggesting that this adjustment must involve some unknown developmental mechanism.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/ajb2.1196DOI Listing
December 2018

The dimensionality of niche space allows bounded and unbounded processes to jointly influence diversification.

Nat Commun 2018 10 15;9(1):4258. Epub 2018 Oct 15.

Department of Botany, University of Otago, PO Box 56,, Dunedin, 9054, New Zealand.

There are two prominent and competing hypotheses that disagree about the effect of competition on diversification processes. The first, the bounded hypothesis, suggests that species diversity is limited (bounded) by competition between species for finite ecological niche space. The second, the unbounded hypothesis, proposes that innovations associated with evolution render competition unimportant over macroevolutionary timescales. Here we use phylogenetically structured niche modelling to show that processes consistent with both of these diversification models drive species accumulation in conifers. In agreement with the bounded hypothesis, niche competition constrained diversification, and in line with the unbounded hypothesis, niche evolution and partitioning promoted diversification. We then analyse niche traits to show that these diversification enhancing and inhibiting processes can occur simultaneously on different niche dimensions. Together these results suggest a new hypothesis for lineage diversification based on the multi-dimensional nature of ecological niches that can accommodate both bounded and unbounded evolutionary processes.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41467-018-06732-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6189034PMC
October 2018

Development of 15 nuclear EST microsatellite markers for the paleoendemic conifer (Podocarpaceae).

Appl Plant Sci 2018 Jun 26;6(6):e01160. Epub 2018 Jun 26.

School of Biological Sciences University of Tasmania Private Bag 55 Hobart Tasmania Australia.

Premise Of The Study: Nuclear microsatellite markers were developed for population genetic analysis of the threatened paleoendemic conifer (Podocarpaceae).

Methods And Results: Fifteen variable loci were identified showing one to 13 alleles per population, with seven loci displaying at least four alleles in all populations, and the average number of alleles per locus ranging from 4.80 to 5.93 per population. Levels of observed heterozygosity per locus varied from 0.00 to 0.91, while average heterozygosity across all loci varied from 0.54 to 0.63 between populations. All loci also amplified in the endangered congener , but only five of the loci had more than one allele.

Conclusions: These 15 loci are the first microsatellite markers developed in the genus . These loci will be useful for investigating the species' extant genetic diversity and structure, the impact of past environmental change, and the significance of asexual reproduction.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/aps3.1160DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6025810PMC
June 2018

Wheat leaves embolized by water stress do not recover function upon rewatering.

Plant Cell Environ 2018 11 24;41(11):2704-2714. Epub 2018 Aug 24.

School of Biological Sciences, University of Tasmania, Hobart, Tasmania, Australia.

New techniques now make it possible to precisely and accurately determine the failure threshold of the plant vascular system during water stress. This creates an opportunity to understand the vulnerability of species to drought, but first, it must be determined whether damage to leaf function associated with xylem cavitation is reparable or permanent. This question is particularly relevant in crop plants such as wheat, which may have the capacity to repair xylem embolism with positive root pressure. Using wheat (Triticum aestivum, Heron), we employed non-invasive imaging to find the water potential causing 50% xylem embolism (-2.87 ± 0.52 MPa) in leaves. Replicate plants were water-stressed to varying degrees to induce embolism ranging from minimal to substantial. Plants were then rewatered to determine the reversibility of xylem damage and photosynthetic inhibition in glasshouse conditions. Rewatering after drought-induced xylem cavitation did not induce visible refilling of embolized xylem, and embolized leaves showed photosynthetic impairment upon rewatering. This impairment was significant even after only 10-20% of leaf veins were embolized, and leaves accumulating >20% embolism died upon rewatering in 7/10 individuals. Photosynthetic damage and hydraulic decline occurred concurrently as wheat leaves dehydrated, and leaf shrinkage during drying was the best predictor of photosynthetic recovery.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/pce.13397DOI Listing
November 2018

Similar geometric rules govern the distribution of veins and stomata in petals, sepals and leaves.

New Phytol 2018 09 15;219(4):1224-1234. Epub 2018 May 15.

School of Natural Sciences, University of Tasmania, Private Bag 55, Hobart, Tasmania, 7001, Australia.

Investment in leaf veins (supplying xylem water) is balanced by stomatal abundance, such that sufficient water transport is provided for stomata to remain open when soil water is abundant. This coordination is mediated by a common dependence of vein and stomatal densities on cell size. Flowers may not conform to this same developmental pattern if they depend on water supplied by the phloem or have high rates of nonstomatal transpiration. We examined the relationships between veins, stomata and epidermal cells in leaves, sepals and petals of 27 angiosperms to determine whether common spacing rules applied to all tissues. Regression analysis found no evidence for different relationships within organ types. Both vein and stomatal densities were strongly associated with epidermal cell size within organs, but, for a given epidermal cell size, petals had fewer veins and stomata than sepals, which had fewer than leaves. Although our data support the concept of common scaling between veins and stomata in leaves and flowers, the large diversity in petal vein density suggests that, in some species, petal veins may be engaged in additional functions, such as the supply of water for high cuticular transpiration or for phloem delivery of water or carbohydrates.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/nph.15210DOI Listing
September 2018

Arbutin Derivatives Isolated from Ancient Proteaceae: Potential Phytochemical Markers Present in Bellendena, Cenarrhenes, and Persoonia Genera.

J Nat Prod 2018 05 1;81(5):1241-1251. Epub 2018 May 1.

School of Physical Sciences-Chemistry , University of Tasmania , Hobart , Tasmania 7001 , Australia.

Extensive phytochemical studies of the paleoendemic Tasmanian Proteaceae species Bellendena montana, Cenarrhenes nitida, and Persoonia gunnii were conducted employing pressurized hot water extraction. As part of these studies, six novel glycosides were isolated, including rare examples of glycoside-containing natural products featuring tiglic acid esters. These polar molecules may represent potential phytochemical markers in ancient Proteaceae.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.jnatprod.7b01038DOI Listing
May 2018

Ferns are less dependent on passive dilution by cell expansion to coordinate leaf vein and stomatal spacing than angiosperms.

PLoS One 2017 27;12(9):e0185648. Epub 2017 Sep 27.

School of Biological Sciences, University of Tasmania, Hobart, Tasmania, Australia.

Producing leaves with closely spaced veins is a key innovation linked to high rates of photosynthesis in angiosperms. A close geometric link between veins and stomata in angiosperms ensures that investment in enhanced venous water transport provides the strongest net carbon return to the plant. This link is underpinned by "passive dilution" via expansion of surrounding cells. However, it is not known whether this 'passive dilution' mechanism is present in plant lineages other than angiosperms and is another key feature of the angiosperms' evolutionary success. Consequently, we sought to determine whether the 'passive dilution' mechanism is; (i) exclusive to the angiosperms, (ii) a conserved mechanism that evolved in the common ancestor of ferns and angiosperms, or (iii) has evolved continuously over time. To do this we first we assessed the plasticity of vein and stomatal density and epidermal cell size in ferns in response to light environment. We then compared the relationships between these traits found among ferns with modelled relationships that assume vein and stomatal density respond passively to epidermal cell expansion, and with those previously observed in angiosperms. Vein density, stomatal density and epidermal cell size were linked in ferns with remarkably similar relationships to those observed in angiosperms, except that fern leaves had fewer veins per stomata. However, plasticity was limited in ferns and stomatal spacing was dependent on active stomatal differentiation as well as passive cell expansion. Thus, ferns (like angiosperms) appear to coordinate vein and stomatal density with epidermal cell expansion to some extent to maintain a constant ratio between veins and stomata in the leaf. The different general relationships between vein density and stomatal density in ferns and angiosperms suggests the groups have different optimum balances between the production of vein tissue dedicated to water supply and stomatal tissue for gas exchange.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0185648PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5617223PMC
October 2017

Amphistomatic leaf surfaces independently regulate gas exchange in response to variations in evaporative demand.

Tree Physiol 2017 07;37(7):869-878

School of Biological Sciences, University of Tasmania, Hobart, Tasmania 7001, Australia.

The occurrence of amphistomatic leaves (stomata on both surfaces) versus hypostomatic leaves (stomata limited to the lower or abaxial surface) has strong associations with environment. Amphistomy provides the advantage of higher conductance of CO2 for photosynthesis, however, unless the stomata on both leaf surfaces can be independently controlled in response to environmental cues, amphistomy may lead to inefficient gas exchange. While previous studies have found evidence that stomata can operate independently across and between surfaces of dorsiventral leaves, we investigate whether an independent stomatal response can be induced for isobilateral leaves by largely natural conditions. Here, we exposed surfaces of isobilateral, amphistomatic Eucalyptus globulus Labill. leaves to natural diurnal variation in differential evaporative demand, using leaf orientation to drive differences in irradiance and heat load on leaf surfaces. We identified preferential closure of stomata on the surface exposed to higher irradiation (and therefore evaporative demand) during the afternoon under natural conditions and similarly induced differential stomatal closure under experimental conditions in the laboratory. The differential response confirms that sufficient hydraulic isolation exists for independent stomatal response to occur between surfaces of amphistomatic, isobilateral leaves, and importantly, we show that natural conditions can induce surface-specific stomatal closure.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/treephys/tpx073DOI Listing
July 2017

Vein density is independent of epidermal cell size in Arabidopsis mutants.

Funct Plant Biol 2017 Apr;44(4):410-418

School of Biological Sciences, University of Tasmania, Private Bag 55, Hobart, Tas. 7001, Australia.

Densities of leaf minor veins and stomata are co-ordinated within and across vascular plants. This maximises the benefit-to-cost ratio of leaf construction by ensuring stomata receive the minimum amount of water required to maintain optimal aperture. A 'passive dilution' mechanism in which densities of veins and stomata are co-regulated by epidermal cell size is thought to facilitate this co-ordination. However, unlike stomata, veins are spatially isolated from the epidermis and thus may not be directly regulated by epidermal cell expansion. Here, we use mutant genotypes of Arabidopsis thaliana (L.) Heynh. with altered stomatal and epidermal cell development to test this mechanism. To do this we compared observed relationships between vein density and epidermal cell size with modelled relationships that assume veins and stomata are passively diluted by epidermal cell expansion. Data from wild-type plants were consistent with the 'passive dilution' mechanism, but in mutant genotypes vein density was independent of epidermal cell size. Hence, vein density is not causally linked to epidermal cell expansion. This suggests that adaptation favours synchronised changes to the cell size of different leaf tissues to coordinate veins and stomata, and thus balance water supply with transpirational demand.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1071/FP16299DOI Listing
April 2017

Barriers and Facilitators toward HIV Testing and Health Perceptions among African-American Men Who Have Sex with Women at a South Side Chicago Community Health Center: A Pilot Study.

Front Public Health 2016 3;4:286. Epub 2017 Jan 3.

Department of Urology, Northwestern University Feinberg School of Medicine , Chicago, IL , USA.

In the United States, African-Americans' (AAs) HIV infection rates are higher than any other racial group, and AA men who have sex with women (MSW) are a significant proportion of new cases. There is little research into AA MSW HIV/AIDS knowledge, barriers, and facilitators of HIV testing in Chicago. We enrolled a convenience sample of AA MSW from a community health clinic who completed self-administered surveys assessing HIV knowledge and testing-related barriers and facilitators. The survey was a combination of questions from several validated instruments, and additional questions were written based on key informant interviews with social scientists to tailor the questionnaire for AA men living on the South Side of Chicago. We recruited 20 AA MSW (mean age 47.4 years). Sixty-five percent had incomes <$10,000/year, 30% were insured, and 50% had post-secondary education. Despite low socioeconomic status, their HIV literacy was relatively high. The identified major barriers to testing were low perceived HIV risk, concerns over privacy, and external stigma at testing sites. Future efforts should focus on educating AA MSW on actual risk for HIV and address issues of privacy and stigma at testing sites.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fpubh.2016.00286DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5206579PMC
January 2017

Cell expansion not cell differentiation predominantly co-ordinates veins and stomata within and among herbs and woody angiosperms grown under sun and shade.

Ann Bot 2016 11 29;118(6):1127-1138. Epub 2016 Aug 29.

School of Biological Sciences, University of Tasmania, Hobart, TAS 7001, Australia

Background And Aims: It has been proposed that modification of leaf size, driven by epidermal cell size, balances leaf water supply (determined by veins) with transpirational demand (generated by stomata) during acclimation to local irradiance. We aimed to determine whether this is a general pattern among plant species with contrasting growth habits.

Methods: We compared observed relationships between leaf minor vein density, stomatal density, epidermal cell size and leaf size in four pairs of herbs and woody species from the same families grown under sun and shade conditions with modelled relationships assuming vein and stomatal densities respond passively to epidermal cell expansion. Leaf lignin content was also quantified to assess whether construction costs of herbaceous leaf veins differ from those of woody plants and the leaf mass fraction invested in veins.

Key Results: Modelled relationships accurately described observed relationships, indicating that in all species, co-ordinated changes to the density of minor veins and stomata were mediated by a common relationship between epidermal cell size, vein density and stomatal density, with little or no impact from stomatal index. This co-ordination was independent of changes in leaf size and is likely to be an adaptive process driven by the significant proportion of biomass invested in veins (13·1 % of sun leaf dry weight and 21·7 % of shade leaf dry weight). Relative costs of venation increased in the shade, intensifying selective pressure towards economizing investment in vein density.

Conclusions: Modulation of epidermal cell size appears to be a general mechanism among our experimental species to maintain a constant ratio between leaf anatomical traits that control leaf water fluxes independently of habit. We propose that this process may co-ordinate plasticity in hydraulic supply and demand in the majority of eudicot angiosperms.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/aob/mcw167DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5963197PMC
November 2016

Gondwanan conifer clones imperilled by bushfire.

Sci Rep 2016 Sep 26;6:33930. Epub 2016 Sep 26.

School of Biological Sciences, University of Tasmania, Private Bag 55, Hobart, Tas. 7001, Australia.

Global increases in fire frequency driven by anthropogenic greenhouse emissions and land use change could threaten unique and ancient species by creeping into long-term fire refugia. The perhumid and mountainous western half of Tasmania is a globally important refugium for palaeo-endemic, fire intolerant lineages, especially conifers. Reproductive strategy will be crucial to the resilience of these organisms under warmer, dryer and more fire prone climates. This study analysed clonal versus sexual reproduction in old growth plots dominated by the palaeo-endemic conifer Athrotaxis cupressoides (Cupressaceae), a species that lacks any traits to tolerate frequent landscape fire. Across most of the seven plots the amount of sexually derived individuals was lower than clonally derived with, on average, 60% of all stems belonging to the same multi-locus lineage (MLL) (i.e. were clonal). Some MLLs were large spanning over 10 s of metres and consisted of up to 62 stems. The high mortality after fire and the rarity of sexual regeneration means that the range of this fire-intolerant species is likely to contract under enhanced fire regimes and has a limited capacity to disperse via seed to available fire refugia in the landscape.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5036195PMC
http://dx.doi.org/10.1038/srep33930DOI Listing
September 2016

Reply to E. Roca et al.

J Clin Oncol 2016 Oct;34(30):3710-3711

University of Arizona, Tucson, AZ.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1200/JCO.2016.68.9299DOI Listing
October 2016

Linking changes in community composition and function under climate change.

Ecol Appl 2015 Dec;25(8):2132-41

Climate change is expected to directly alter the composition of communities and the functioning of ecosystems across the globe. Improving our understanding of links between biodiversity and ecosystem functioning across large spatial scales and rapid global change is a major priority to help identify management responses that will retain diverse, functioning systems. Here we address this challenge by linking projected changes in plant community composition and functional attributes (height, leaf area, seed mass) under climate change across Tasmania, Australia. Using correlative community-level modeling, we found that projected changes in plant community composition were not consistently related to projected changes in community mean trait values. In contrast, we identified specific mechanisms through which alternative combinations of projected functional and compositional change across Tasmania could be realized, including loss/replacement of functionally similar species (lowland grasslands/grassy woodlands) and loss of a small number of functionally unique species (lowland forests). Importantly, we demonstrate how these linked projections of change in community composition and functional attributes can be utilized to inform specific management actions that may assist in maintaining diverse, functioning ecosystems under climate change.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1890/14-2384.1DOI Listing
December 2015

Associations Between Serum Vitamin D and Adverse Pathology in Men Undergoing Radical Prostatectomy.

J Clin Oncol 2016 Apr 22;34(12):1345-9. Epub 2016 Feb 22.

Yaw A. Nyame, Cleveland Clinic, Cleveland, Ohio; Adam B. Murphy, Diana K. Bowen, Gregory Jordan, Michael Dixon, Stephanie Kielb, Joshua J. Meeks, and William J. Catalona, Northwestern University, Chicago; Courtney M.P. Hollowell, Cook County Health and Hospitals System; Peter H. Gann, Virgilia Macias, and Andre Kajdacsy-Balla, University of Illinois at Chicago, Chicago, IL; and Ken Batai and Rick Kittles, University of Arizona, Tucson, AZ.

Purpose: Lower serum vitamin D levels have been associated with an increased risk of aggressive prostate cancer. Among men with localized prostate cancer, especially with low- or intermediate-risk disease, vitamin D may serve as an important biomarker of disease aggression. The aim of this study was to assess the relationship between adverse pathology at the time of radical prostatectomy and serum 25-hydroxyvitamin D (25-OH D) levels.

Methods: This cross-sectional study was carried out from 2009 to 2014, nested within a large epidemiologic study of 1,760 healthy controls and men undergoing prostate cancer screening. In total, 190 men underwent radical prostatectomy in the cohort. Adverse pathology was defined as the presence of primary Gleason 4 or any Gleason 5 disease, or extraprostatic extension. Descriptive and multivariate analyses were performed to assess the relationship between 25-OH D and adverse pathology at the time of prostatectomy.

Results: Eighty-seven men (45.8%) in this cohort demonstrated adverse pathology at radical prostatectomy. The median age in the cohort was 64.0 years (interquartile range, 59.0 to 67.0). On univariate analysis, men with adverse pathology at radical prostatectomy demonstrated lower median serum 25-OH D (22.7 v 27.0 ng/mL, P = .007) compared with their counterparts. On multivariate analysis, controlling for age, serum prostate specific antigen, and abnormal digital rectal examination, serum 25-OH D less than 30 ng/mL was associated with increased odds of adverse pathology (odds ratio, 2.64; 95% CI, 1.25 to 5.59; P = .01).

Conclusion: Insufficiency/deficiency of serum 25-OH D is associated with increased odds of adverse pathology in men with localized disease undergoing radical prostatectomy. Serum 25-OH D may serve as a useful biomarker in prostate cancer aggressiveness, which deserves continued study.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1200/JCO.2015.65.1463DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4872348PMC
April 2016

Transient hybridization, not homoploid hybrid speciation, between ancient and deeply divergent conifers.

Am J Bot 2016 Feb 12;103(2):246-59. Epub 2016 Feb 12.

School of Biological Sciences, University of Tasmania, Private Bag 55, Hobart, Tasmania 7001, Australia +61 3 6226 1943.

Premise Of The Study: Homoploid hybrid speciation is receiving growing attention due the increasing recognition of its role in speciation. We investigate if individuals intermediate in morphology between the two species of the conifer genus Athrotaxis represent a homoploid hybrid species, A. laxifolia, or are spontaneous F1 hybrids.

Methods: A total of 1055 individuals of Athrotaxis cupressoides and A. selaginoides, morphologically intermediate individuals, and two putative hybrid swarms were sampled across the range of the genus and genotyped with 13 microsatellites. We used simulations to test the power of our data to identify the pure species, F1s, F2s, and backcross generations.

Key Results: We found that Athrotaxis cupressoides and A. selaginoides are likely the most divergent congeneric conifers known, but the intermediates are F1 hybrids, sharing one allele each from A. cupressoides and A. selaginoides at six loci with completely species specific alleles. The hybrid swarms contain wide genetic variation with stronger affinities to the locally dominant species, A. selaginoides and A. selaginoides backcrosses outnumbering A. cupressoides backcrosses. In addition, we observed evidence for isolated advanced generation backcrosses within the range of the pure species.

Conclusions: We conclude that, even though they can be large and long-lived, Athrotaxis hybrid swarms are on a trajectory of decline and will eventually be reabsorbed by the parental species. However, this process may take millennia and fossil evidence suggests that such events have occurred repeatedly since the early Quaternary. Given this timeline, our study highlights the many obstacles to homoploid hybrid speciation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3732/ajb.1500433DOI Listing
February 2016

Pliocene reversal of late Neogene aridification.

Proc Natl Acad Sci U S A 2016 Feb 8;113(8):1999-2004. Epub 2016 Feb 8.

School of Life and Environmental Sciences, Deakin University, Burwood, VIC, 3125, Australia.

The Pliocene epoch (5.3-2.6 Ma) represents the most recent geological interval in which global temperatures were several degrees warmer than today and is therefore considered our best analog for a future anthropogenic greenhouse world. However, our understanding of Pliocene climates is limited by poor age control on existing terrestrial climate archives, especially in the Southern Hemisphere, and by persistent disagreement between paleo-data and models concerning the magnitude of regional warming and/or wetting that occurred in response to increased greenhouse forcing. To address these problems, here we document the evolution of Southern Hemisphere hydroclimate from the latest Miocene to the middle Pliocene using radiometrically-dated fossil pollen records preserved in speleothems from semiarid southern Australia. These data reveal an abrupt onset of warm and wet climates early within the Pliocene, driving complete biome turnover. Pliocene warmth thus clearly represents a discrete interval which reversed a long-term trend of late Neogene cooling and aridification, rather than being simply the most recent period of greater-than-modern warmth within a continuously cooling trajectory. These findings demonstrate the importance of high-resolution chronologies to accompany paleoclimate data and also highlight the question of what initiated the sustained interval of Pliocene warmth.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1073/pnas.1520188113DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4776468PMC
February 2016

Fossil evidence for open, Proteaceae-dominated heathlands and fire in the Late Cretaceous of Australia.

Am J Bot 2015 Dec 7;102(12):2092-107. Epub 2015 Dec 7.

School of Biological Sciences, University of Adelaide, Adelaide, SA 5005, Australia Environment Institute, University of Adelaide, Adelaide, SA 5005, Australia.

Premise Of The Study: The origin of biomes is of great interest globally. Molecular phylogenetic and pollen evidence suggest that several plant lineages that now characterize open, burnt habitats of the sclerophyll biome, became established during the Late Cretaceous of Australia. However, whether this biome itself dates to that time is problematic, fundamentally because of the near-absence of relevant, appropriately aged, terrestrial plant macro- or mesofossils.

Methods: We recovered, identified, and interpreted the ecological significance of fossil pollen, foliar and other remains from a section of core drilled in central Australia, which we dated as Late Campanian-Maastrichtian.

Key Results: The sediments contain plant fossils that indicate nutrient-limited, open, sclerophyllous vegetation and abundant charcoal as evidence of fire. Most interestingly, >30 pollen taxa and at least 12 foliage taxa are attributable to the important Gondwanan family Proteaceae, including several minute, amphistomatic, and sclerophyllous foliage forms consistent with subfamily Proteoideae. Microfossils, including an abundance of Sphagnales and other wetland taxa, provided strong evidence of a fenland setting. The local vegetation also included diverse Ericaceae and Liliales, as well as a range of ferns and gymnosperms.

Conclusions: The fossils provide strong evidence in support of hypotheses of great antiquity for fire and open vegetation in Australia, point to extraordinary persistence of Proteaceae that are now emblematic of the Mediterranean-type climate southwestern Australian biodiversity hotspot and raise the profile of open habitats as centers of ancient lineages.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3732/ajb.1500343DOI Listing
December 2015

Living near the edge: Being close to mature forest increases the rate of succession in beetle communities.

Ecol Appl 2015 Apr;25(3):800-11

In increasingly fragmented landscapes, it is important to understand how mature forest affects adjacent secondary forest (forest influence). Forest influence on ecological succession of beetle communities is largely unknown. We investigated succession and forest influence using 235 m long transects across boundaries between mature and secondary forest at 15 sites, sampling a chronosequence of three forest age classes (5-10, 23- 29, and 42-46 years since clear-cutting) in tall eucalypt forest in Tasmania, Australia. Our results showed that ground-dwelling beetle communities showed strong successional changes, and in the oldest secondary forests, species considered indicators of mature forest had recolonized to abundance levels similar to those observed within adjacent mature forest stands. However, species composition also showed forest influence gradients in all age classes. Forest influence was estimated to extend 13 m and 20 m in the youngest and intermediate-aged secondary forests, respectively. However, the estimated effect extended to at least 176 m in the oldest secondary forest. Our environmental modeling suggests that leaf litter, microclimate, and soil variables were all important in explaining the spatial variation in beetle assemblages, and the relative importance of factors varied between secondary forest age classes. Mature-forest beetle communities can recolonize successfully from the edge, and our results provide a basis for land managers to build mature habitat connectivity into forest mosaics typical of production forests. Our results also indicate the importance of forest influence in determining potential conservation value of older secondary forest for beetles.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1890/14-0334.1DOI Listing
April 2015