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291.
Fire is a dominant process shaping the Australian landscape and in many regions the frequency and severity of wildfires are predicted to increase under climate change. The primary impact of fire on fauna is typically indirect through habitat change. In particular, in mesic forests different animal species are favoured at different times since fire as habitat complexity increases with vegetation recovery. However, this will not necessarily be the case in habitats with low complexity such as many of those occurring in arid and semi-arid regions. Here, we investigate the relationship between fire history and ant diversity and composition in semi-arid mallee of south-eastern Australia. We surveyed ants at 11 sites in the Little Desert National Park and nearby private land that last burnt 0.5, 6 or 40 years ago. We found no relationship between time since fire and either ant diversity or composition, and this can be explained by a lack of relationship between time since fire and vegetation cover. Our findings contrast with those for mallee bird species, which show clear successional patterns following fire, but are likely to be typical of ground-foraging fauna that lack specialized habitat requirements.  相似文献   
292.
Conservation management cannot proceed in the absence of the basic ecological data necessary to develop conservation strategies for a species. Species considered Data Deficient and possibly extinct are poorly known, and are often overlooked in conservation planning. This is despite a growing body of evidence indicating that Data Deficient species are more likely to be threatened by extinction compared to well-studied taxa. Hence, there is an immediate need to resolve data deficiency, and to search for species that are possibly extinct. Here, we conducted the first systematic search for a Data Deficient Australian skink, Lampropholis elongata (long sunskink), which prior to our study, had not been seen for approximately 9 years. A combination of pitfall trapping and active searches was used in attempt to detect the species. We rediscovered L. elongata at four sites within its known distribution on the southern edge of the New England Tablelands Bioregion in New South Wales, Australia. Our findings suggest that the species can be detected relatively easily using active survey methods, especially by inspecting tussock bases. We further highlight that areas of high canopy openness and high cover of Poa sieberiana (grey tussock-grass) appear to be key habitat for the species.  相似文献   
293.
The first step in the biosynthesis of allylglucosinolate from methionine in Brassica is thought to be the transamination of methionine to 2-keto-4-methylthiobutyrate. By using Q-Sepharose and Red Agarose, followed by high resolution anion exchange chromatography and chromatofocussing, a methionine:glyoxylate aminotransferase (MGAT) was purified to homogeneity from leaves of Brassica carinata var R-4218, and approximately 5000-fold from leaves of Brassica napus var Topas. The final purification was accomplished using nondenaturing polyacrylamide gel electrophoresis. The enzyme has a pl of 4.3, a native molecular mass of 230 to 290 kilodaltons, and a subunit molecular mass of approximately 50 kilodaltons. Four isozymes of the enzyme were identified in the six species of Brassica commonly cultivated. Nonglucosinolate producing species had only low levels of MGAT or an MGAT isozyme which was distinctly different from that in Brassica.  相似文献   
294.
To gain insight into the number of loci of large effect that underlie variation in cattle, a quantitative trait locus (QTL) scan for 14 economically important traits was performed in two commercial Angus populations using 390 microsatellites, 11 single nucleotide polymorphisms (SNPs) and one duplication loci. The first population comprised 1769 registered Angus bulls born between 1955 and 2003, with Expected Progeny Differences computed by the American Angus Association. The second comprised 38 half‐sib families containing 1622 steers with six post‐natal growth and carcass phenotypes. Linkage analysis was performed by half‐sib least squares regression with gridqtl or Bayesian Markov chain Monte Carlo analysis of complex pedigrees with loki . Of the 673 detected QTL, only 118 have previously been reported, reflecting both the conservative approach to QTL reporting in the literature, and the more liberal approach taken in this study. From 33 to 71% of the genetic variance and 35 to 56% of the phenotypic variance in each trait was explained by the detected QTL. To analyse the effects of 11 SNPs and one duplication locus within candidate genes on each trait, a single marker analysis was performed by fitting an additive allele substitution model in both mapping populations. There were 53 associations detected between the SNP/duplication loci and traits with ?log10Pnominal≥ 4.0, where each association explained 0.92% to 4.4% of the genetic variance and 0.01% to 1.86% of the phenotypic variance. Of these associations, only six SNP/duplication loci were located within 8 cM of a QTL peak for the trait, with two being located at the QTL peak: SST_DG156121:c.362A>G for ribeye muscle area and TG_X05380:c.422C>T for calving ease. Strong associations between several SNP/duplication loci and trait variation were obtained in the absence of any detected linked QTL. However, we reject the causality of several commercialized DNA tests, including an association between TG_X05380:c.422C>T and marbling in Angus cattle.  相似文献   
295.
The New Zealand skink fauna has proven to be an ideal taxonomic group in which to examine the impact of climatic and geological processes on the evolution of the New Zealand biota since the Pliocene. Here we examine the phylogeography of McCann's skink (Oligosoma maccanni) in order to gain insight into the relative contribution of Pliocene and Pleistocene processes on patterns of genetic structure in the South Island biota, and investigate the phylogeography of the brown skink (O. zelandicum) to examine whether Cook Strait landbridges facilitated geneflow between the North and South Islands in the late-Pleistocene. We obtained mitochondrial DNA sequence data (ND2 and ND4; 1282bp) from across the range of both species. We examined the phylogeographic patterns evident in each species using Neighbour-Joining, Maximum Likelihood and Bayesian methods. We found substantial phylogeographic structure within O. maccanni, with seven distinct clades identified. Divergences among clades are estimated to have occurred during the Pliocene. Populations in the Otago/Southland region (south of the Waitaki River valley) formed a well-supported lineage within O. maccanni. A substantial genetic break was evident between populations in east and west Otago, either side of the Nevis-Cardrona fault system, while north-south genetic breaks were evident within the Canterbury region. Within-clade divergences in O. maccanni appear to have occurred during the mid- to late-Pleistocene. Shimodaira-Hasegawa topology tests indicated that the 'Garston' skink is not genetically distinct from O. maccanni. There was only relatively minor phylogeographic structure within O. zelandicum, with divergences among populations occurring during the mid- to late-Pleistocene. Our genetic data supports a single colonisation of the North Island by O. zelandicum from the South Island, with the estimated timing of this event (0.46mya) consistent with the initial formation of Cook Strait.  相似文献   
296.
Australia is in the midst of an extinction crisis, having already lost 10% of terrestrial mammal fauna since European settlement and with hundreds of other species at high risk of extinction. The decline of the nation''s biota is a result of an array of threatening processes; however, a comprehensive taxon‐specific understanding of threats and their relative impacts remains undocumented nationally. Using expert consultation, we compile the first complete, validated, and consistent taxon‐specific threat and impact dataset for all nationally listed threatened taxa in Australia. We confined our analysis to 1,795 terrestrial and aquatic taxa listed as threatened (Vulnerable, Endangered, or Critically Endangered) under Australian Commonwealth law. We engaged taxonomic experts to generate taxon‐specific threat and threat impact information to consistently apply the IUCN Threat Classification Scheme and Threat Impact Scoring System, as well as eight broad‐level threats and 51 subcategory threats, for all 1,795 threatened terrestrial and aquatic threatened taxa. This compilation produced 4,877 unique taxon–threat–impact combinations with the most frequently listed threats being Habitat loss, fragmentation, and degradation (n = 1,210 taxa), and Invasive species and disease (n = 966 taxa). Yet when only high‐impact threats or medium‐impact threats are considered, Invasive species and disease become the most prevalent threats. This dataset provides critical information for conservation action planning, national legislation and policy, and prioritizing investments in threatened species management and recovery.  相似文献   
297.
Electropermeabilization of Clostridium cellulolyticum was optimized using ATP leakage assays. Electrotransformation was then performed under optimized conditions (6 to 7.5 kV cm−1 field strength applied during 5 ms to a mixture containing methylated plasmids and late exponential phase cell suspensions (10 molecules:1 cell) in a sucrose-containing buffer). Transformants were only obtained when 7 or 7.5 kV cm−1 pulses were applied. Transformation efficiencies evaluated from the growth curves of transformed cells were between 105 and 107 transformants per microgram of plasmid DNA for five different replicon-based plasmids. Restriction nuclease digestion patterns of pJIR418 purified from transformed Clostridia and Escherichia coli were indistinguishable, indicating that heterologous DNA was structurally stable in the Clostridium strain. Copy numbers of 130, 70 and 10 were estimated from purification yield for pCTC1, pKNT19 and pJIR418, respectively. Journal of Industrial Microbiology & Biotechnology (2001) 27, 271–274. Received 12 September 2000/ Accepted in revised form 25 November 2000  相似文献   
298.

Background  

What people believe about their illness may affect how they cope with it. It has been suggested that such beliefs stem from those commonly held within society . This study compared the beliefs held by people with angina, regarding causation and coping in angina, with the beliefs of their friends who do not suffer from angina.  相似文献   
299.
M Ruegger  C Chapple 《Genetics》2001,159(4):1741-1749
The products of phenylpropanoid metabolism in Arabidopsis include the three fluorescent sinapate esters sinapoylglucose, sinapoylmalate, and sinapoylcholine. The sinapoylmalate that accumulates in cotyledons and leaves causes these organs to appear blue-green under ultraviolet (UV) illumination. To find novel genes acting in phenylpropanoid metabolism, Arabidopsis seedlings were screened under UV for altered fluorescence phenotypes caused by changes in sinapoylmalate content. This screen identified recessive mutations at four Reduced Epidermal Fluorescence (REF) loci that reduced leaf sinapoylmalate content. Further analyses showed that the ref mutations affected other aspects of phenylpropanoid metabolism and some led to perturbations in normal plant development. A second class of mutations at the Bright Trichomes 1 (BRT1) locus leads to modest reductions in sinapate ester content; however, the most notable phenotype of brt1 mutants is the development of hyperfluorescent trichomes that appear to contain elevated levels of sinapate esters when compared to the wild type. These results indicate that at least five new loci affecting the developmentally regulated accumulation of phenylpropanoid secondary metabolites in Arabidopsis, and the cell specificity of their distribution, have been identified by screening for altered UV fluorescence phenotypes.  相似文献   
300.
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