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281.
A terrestrial talitrid crustacean is recorded for the first time from subantarctic Macquarie Island. The species, Puhuruhuru patersoni, is native to the southern part of the South Island of New Zealand. Its distribution on Macquarie Is. is restricted to a single locality near the ANARE station on the Isthmus. All mature females collected in December were carrying eggs; females appeared to be less mobile than males. It seems likely that the species has been transported accidentally from New Zealand, perhaps by the same means that introduced the isopod, Styloniscus otakensis, also from southern New Zealand. 相似文献
282.
Claire L Curl Catherine J Bellair Trudi Harris Brendan E Allman Peter J Harris Alastair G Stewart Ann Roberts Keith A Nugent Lea M D Delbridge 《Cytometry. Part A》2005,65(1):88-92
BACKGROUND: The refractive index (RI) of cellular material provides fundamental biophysical information about the composition and organizational structure of cells. Efforts to describe the refractive properties of cells have been significantly impeded by the experimental difficulties encountered in measuring viable cell RI. In this report we describe a procedure for the application of quantitative phase microscopy in conjunction with confocal microscopy to measure the RI of a cultured muscle cell specimen. METHODS: The experimental strategy involved calculation of cell thickness by using confocal optical sectioning procedures, construction of a phase map of the same cell using quantitative phase microscopy, and selection of cellular regions of interest to solve for the cell RI. RESULTS: Mean cell thickness and phase values for six cell regions (five cytoplasmic and one nuclear) were determined. The average refractive index calculated for cytoplasmic and nuclear regions was 1.360 +/- 0.004. The uncertainty in the final RI value represents the technique measurement error. CONCLUSIONS: The methodology we describe for viable cell RI measurement with this prototype cell has broad generic application in the study of cell growth and functional responses. The RI value we report may be used in optical analyses of cultured cell structure and morphology. 相似文献
283.
Ian Oliver Alan Ede Wendy Hawes Alastair Grieve 《Ecological Management & Restoration》2005,6(3):197-205
Summary In 2002 the Environmental Services Scheme (ESS) was launched in New South Wales, Australia. Its aim was to pilot a process to provide financial incentives to landholders to undertake changes in land use or land management that improved the status of environmental services (e.g. provision of clean water, healthy soils, biodiversity conservation). To guide the direction of incentive funds, metrics were developed for use by departmental staff to score the benefits of land use or land management changes to a range of environmental services. The purpose of this paper is to (i) report on the development of one of these metrics – the biodiversity benefits index; (ii) present the data generated by field application of the metric to 20 properties contracted to the ESS; and (iii) discuss the lessons learned and recent developments of the metric that aim to make it accessible to a wider range of end-users and applications. 相似文献
284.
Everard J. Edwards David G. Benham† Louise A. Marland Alastair H. Fitter 《Global Change Biology》2004,10(2):209-227
Accurate knowledge of the response of root turnover to a changing climate is needed to predict growth and produce carbon cycle models. A soil warming system and shading were used to vary soil temperature and received radiation independently in a temperate grassland dominated by Holcus lanatus L. Minirhizotrons allowed root growth and turnover to be examined non‐destructively. In two short‐term (8 week) experiments, root responses to temperature were seasonally distinct. Root number increased when heating was applied during spring, but root death increased during autumnal heating. An experiment lasting 12 months demonstrated that any positive response to temperature was short‐lived and that over a full growing season, soil warming led to a reduction in root number and mass due to increased root death during autumn and winter. Root respiration was also insensitive to soil temperature over much of the year. In contrast, root growth was strongly affected by incident radiation. Root biomass, length, birth rate, number and turnover were all reduced by shading. Photosynthesis in H. lanatus exhibited some acclimation to shading, but assimilation rates at growth irradiance were still lower in shaded plants. The negative effects of shading and soil warming on roots were additive. Comparison of root data with environmental measurements demonstrated a number of positive relationships with photosynthetically active radiation, but not with soil temperature. This was true both across the entire data set and within a shade treatment. These results demonstrate that root growth is unlikely to be directly affected by increased soil temperatures as a result of global warming, at least in temperate areas, and that predictions of net primary productivity should not be based on a positive root growth response to temperature. 相似文献
285.
Direct and indirect effects of nursery habitats on coral‐reef fish assemblages,grazing pressure and benthic dynamics
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Alastair R. Harborne Ivan Nagelkerken Nicholas H. Wolff Yves‐Marie Bozec Martijn Dorenbosch Monique G. G. Grol Peter J. Mumby 《Oikos》2016,125(7):957-967
Migrating species are common within seascapes, but the potential for these movements to alter the populations and functional roles of non‐migrating species (e.g. by increasing predation) is rarely investigated. This study considers whether the presence of nursery habitats (mangroves and seagrass) simply enhances the abundance of nursery‐using parrotfishes and piscivores on nearby coral reefs, or also affects other parrotfishes. Data from 131 reef sites and multiple seascape configurations across 13 degrees of latitude were used to model correlations between biophysical variables, including nursery habitat connectivity, and the abundance and grazing pressure of both nursery‐using species and other parrotfishes and piscivore biomass. Connectivity to mangroves and dense seagrass was positively correlated with the biomass of nursery‐using species, but was also negatively correlated with non‐nursery parrotfish populations. This reduction may be caused indirectly by nursery habitats increasing confamilial competition and predation by nursery‐using piscivores, particularly affecting small parrotfishes settling directly onto reefs. As key reef grazers, parrotfishes affect coral demographics. Consequently, a spatial simulation model predicted the impacts after five years of changes in grazing pressure because of nursery habitat connectivity. The model demonstrated that high nursery connectivity was correlated to changes in grazing pressure on nearby reefs that could potentially lead to differences in coral cover of ~3–4% when compared to low connectivity reefs. However, the direction of this change depended on the seascapes’ characteristics. Historically, large‐bodied, nursery‐using parrotfish would have increased grazing in all nursery‐rich seascapes. Overfishing means that nursery availability may have spatially variable impacts on coral cover, influencing reserve design. This study suggests that nursery availability may directly and indirectly modify an ecological process, and alter an ecological cascade (migrating species increase predator and competitor abundances, affecting other grazers and consequently corals). Therefore, elucidating the multi‐species impacts of animal movements is required to better understand ecosystem functioning. 相似文献
286.
287.
288.
Characterization of a Deep‐Branching Heterolobosean,Pharyngomonas turkanaensis n. sp., Isolated from a Non‐Hypersaline Habitat,and Ultrastructural Comparison of Cysts and Amoebae Among Pharyngomonas Strains
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An unusual heterolobosean amoeba, isolate LO, was isolated recently from a sample with a salinity of ~4‰, from Lake Turkana in East Africa. 18S rDNA phylogenies confirm that isolate LO branches among halophilic amoeboflagellates assigned to Pharyngomonas. We examined the ultrastructure of the amoeba and cyst stages of isolate LO, as well as the amoebae and cysts of Pharyngomonas kirbyi (isolates AS12B and SD1A). The amoebae of all three isolates lacked discrete dictyosomes and had discoidal/flattened mitochondrial cristae, but the mitochondria were not enrobed by rough endoplasmic reticulum. The cysts of all three isolates showed a thick, bipartite cyst wall, and lacked cyst pores. The cysts of isolate LO were distinct in that the ectocyst was very loose‐fitting, and could contain “crypts”. No flagellate form of isolate LO has been observed to date, and a salinity‐for‐growth experiment showed that isolate LO can grow at 15–100‰ salinity, indicating that it is halotolerant. By contrast, other studied Pharyngomonas isolates are amoeboflagellates and true halophiles. Therefore, we propose isolate LO as a new species, Pharyngomonas turkanaensis n. sp. It is possible that P. turkanaensis descended from halophilic ancestors, and represents a secondary reestablishment of a physiology adapted for moderate salinity. 相似文献
289.
Maria Aamelfot Debes H. Christiansen Ole Bendik Dale Alastair McBeath Sylvie L. Benestad Knut Falk 《PloS one》2016,11(3)
Infectious salmon anaemia (ISA) is an important, systemic viral disease of farmed Atlantic salmon, Salmo salar L. Endothelial cells are the main target cells for highly virulent HPR-deleted ISA virus (ISAV) types. Here we examine the pathogenesis of non-virulent ISAV HPR0 infections, presenting evidence of an epithelial tropism for this virus type, including actual infection and replication in the epithelial cells. Whereas all HPR0 RT-qPCR positive gills prepared for cryosection tested positive by immunohistochemistry (IHC) and immunofluorescent labelling, only 21% of HPR0 RT-qPCR positive formalin-fixed paraffin-embedded gills were IHC positive, suggesting different methodological sensitivities. Only specific epithelial cell staining was observed and no staining was observed in endothelial cells of positive gills. Furthermore, using an ISAV segment 7 RT-PCR assay, we demonstrated splicing of HPR0, suggesting initial activation of the replication machinery in the epithelial gill cells. Immunological responses were investigated by the expression of interferon-related genes (e.g. Mx and γIP) and by ELISA for presence of anti-ISAV antibodies on samples taken sequentially over several months during an episode of transient HPR0 infection. All fish revealed a variable, but increased expression of the immunological markers in comparison to normal healthy fish. Taken together, we conclude that HPR0 causes a localized epithelial infection of Atlantic salmon. 相似文献
290.
Saba M. Lambert Digafe T. Alembo Shimelis D. Nigusse Lawrence K. Yamuah Stephen L. Walker Diana N. J. Lockwood 《PLoS neglected tropical diseases》2016,10(4)