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961.
The ‘New Zealand flatworm’, Arthurdendyus triangulatus, is a native of the South Island of New Zealand, which has established in the UK, Ireland and the Faroe Islands. In its introduced range, it is a predator of lumbricid earthworms. To assess the impact of A. triangulatus on earthworm species, flatworm distributions were manipulated into ‘high’, control and ‘low’ densities within a replicated field experiment. Earthworm biomass in the ‘high’ flatworm density treatment was significantly lower than the control or ‘low’ treatments. This was due to a reduction in the anecic species Lumbricus terrestris and, to a lesser extent, Aporrectodea longa. There was little evidence of negative effects on other earthworm species, with even a weakly positive relationship between flatworm density and epigeic biomass. Principal components analysis showed a clear separation of anecic species from A. triangulatus, but the epigeic species Lumbricus festivus and Lumbricus rubellus grouped with A. triangulatus, suggesting that they could be benefitting from reduced intraguild competition. Flatworm densities of 0.8 per m2, comparable to natural infestations in grassland, were predicted to give a reduction in total earthworm biomass of c. 20 %. The bulk of this was comprised of a reduction in anecic species biomass. In particular, it is considered that A. triangulatus poses a serious risk to L. terrestris populations, with implications for soil functioning and indigenous earthworm-feeding wildlife. 相似文献
962.
Major quantitative trait loci affect resistance to infectious pancreatic necrosis in Atlantic salmon (Salmo salar) 总被引:1,自引:0,他引:1 下载免费PDF全文
Houston RD Haley CS Hamilton A Guy DR Tinch AE Taggart JB McAndrew BJ Bishop SC 《Genetics》2008,178(2):1109-1115
Infectious pancreatic necrosis (IPN) is a viral disease currently presenting a major problem in the production of Atlantic salmon (Salmon salar). IPN can cause significant mortality to salmon fry within freshwater hatcheries and to smolts following transfer to seawater, although challenged populations show clear genetic variation in resistance. To determine whether this genetic variation includes loci of major effect, a genomewide quantitative trait loci (QTL) scan was performed within 10 full-sib families that had received a natural seawater IPN challenge. To utilize the large difference between Atlantic salmon male and female recombination rates, a two-stage mapping strategy was employed. Initially, a sire-based QTL analysis was used to detect linkage groups with significant effects on IPN resistance, using two to three microsatellite markers per linkage group. A dam-based analysis with additional markers was then used to confirm and position any detected QTL. Two genomewide significant QTL and one suggestive QTL were detected in the genome scan. The most significant QTL was mapped to linkage group 21 and was significant at the genomewide level in both the sire and the dam-based analyses. The identified QTL can be applied in marker-assisted selection programs to improve the resistance of salmon to IPN and reduce disease-related mortality. 相似文献
963.
Cheng-Yu Hung Yi-Yen Chen Tsai-Wen Hsu Tsurng-Juhn Huang Tzen-Yuh Chiang 《Conservation Genetics》2008,9(5):1337-1339
Suzukia shikikunensis Kudo is an endemic plant in Taiwan and suffers habitat destruction caused by human overexploitation. In this study, we developed
12 microsatellite primer pairs for genetic study. These markers were screened for 24 samples collected from wild populations distributed in Taiwan, and for a sister species
S. luchuensis collected from Yonaguni and Lutao Islands. The number of alleles ranged from 5 to 14. The expected (H
E) and observed (H
O) heterozygosities were 0.65–0.922 and 0–0.625, respectively. All loci were significantly deviated from Hardy–Weinberg equilibrium
due to the heterozygote deficiency. These primers amplifying microsatellites in the two species may provide a useful tool
for population genetics to establish conservation strategy. 相似文献
964.
Cinco-Moroyoqui FJ Díaz-Malváez FI Alanís-Villa A Barrón-Hoyos JM Cárdenas-López JL Cortez-Rocha MO Wong-Corral FJ 《Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology》2008,150(2):153-160
Three isoamylases of Rhyzopertha dominica (termed RdA70, RdA79, and RdA90 according to their relative mobility in gel electrophoresis) were isolated by ammonium sulfate fractionation and hydrophobic interaction chromatography. RdA70 and RdA79 showed an optimal pH of 7.0, whereas for RdA90 the optimal pH was 6.5. The three isoamylases remained stable at 50 °C for 1 h, but at 60 °C, all lost 50% of their activity in 20 min and were completely inactivated in 1 h. RdA70 and RdA79 were inhibited by albumin extracts from wheat samples varying widely in amylase inhibitory activity; however, RdA90 was highly resistant to inhibition. β-Mercaptoethanol up to 30 mM increased the activity of the three isoamylases by 2.5-fold. The action pattern of the three isoamylases was typical of endoamylases; however, differences were observed on the hydrolytic efficiency rates measured as Vmax/Km ratio on starch, amylopectin, and amylose. The hydrolyzing action of RdA90 on starch and amylopectin (Vmax/Km = 90.4 ± 2.3 and 78.9 ± 6.6, respectively) was less efficient than that on amylose (Vmax/Km = 214 ± 23.2). RdA79 efficiently hydrolyzed both amylopectin and amylose (Vmax/Km = 260.6 ± 12.9 and 326.5 ± 9.4, respectively). RdA70 hydrolyzed starch and amylose at similar rates (Vmax/Km = 202.9 ± 5.5 and 215.9 ± 6.2, respectively), but amylopectin was a poor substrate (Vmax/Km = 124.2 ± 7.4). The overall results suggest that RdA70 and RdA79 appear to belong to a group of saccharifying isoamylases that breaks down long fragments of oligosaccharide chains produced by the hydrolytic action of RdA90. The simultaneous action of the three isoamylases on starch, aside from the high resistance of RdA90 to wheat amylase inhibitors, might allow R. dominica to feed and reproduce successfully on the wheat kernel. 相似文献
965.
Hybrid pathogenicity island PAGI-5 contributes to the highly virulent phenotype of a Pseudomonas aeruginosa isolate in mammals 总被引:1,自引:0,他引:1
Most known virulence determinants of Pseudomonas aeruginosa are remarkably conserved in this bacterium's core genome, yet individual strains differ significantly in virulence. One explanation for this discrepancy is that pathogenicity islands, regions of DNA found in some strains but not in others, contribute to the overall virulence of P. aeruginosa. Here we employed a strategy in which the virulence of a panel of P. aeruginosa isolates was tested in mouse and plant models of disease, and a highly virulent isolate, PSE9, was chosen for comparison by subtractive hybridization to a less virulent strain, PAO1. The resulting subtractive hybridization sequences were used as tags to identify genomic islands found in PSE9 but absent in PAO1. One 99-kb island, designated P. aeruginosa genomic island 5 (PAGI-5), was a hybrid of the known P. aeruginosa island PAPI-1 and novel sequences. Whereas the PAPI-1-like sequences were found in most tested isolates, the novel sequences were found only in the most virulent isolates. Deletional analysis confirmed that some of these novel sequences contributed to the highly virulent phenotype of PSE9. These results indicate that targeting highly virulent strains of P. aeruginosa may be a useful strategy for identifying pathogenicity islands and novel virulence determinants. 相似文献
966.
967.
Pott C Ren X Tran DX Yang MJ Henderson S Jordan MC Roos KP Garfinkel A Philipson KD Goldhaber JI 《American journal of physiology. Cell physiology》2007,292(2):C968-C973
In cardiac-specific Na+-Ca2+ exchanger (NCX) knockout (KO) mice, the ventricular action potential (AP) is shortened. The shortening of the AP, as well as a decrease of the L-type Ca2+ current (ICa), provides a critical mechanism for the maintenance of Ca2+ homeostasis and contractility in the absence of NCX (Pott C, Philipson KD, Goldhaber JI. Excitation-contraction coupling in Na+-Ca2+ exchanger knockout mice: reduced transsarcolemmal Ca2+ flux. Circ Res 97: 12881295, 2005). To investigate the mechanism that underlies the accelerated AP repolarization, we recorded the transient outward current (Ito) in patch-clamped myocytes isolated from wild-type (WT) and NCX KO mice. Peak Ito was increased by 78% and decay kinetics were slowed in KO vs. WT. Consistent with increased Ito, ECGs from KO mice exhibited shortened QT intervals. Expression of the Ito-generating K+ channel subunit Kv4.2 and the K+ channel interacting protein was increased in KO. We used a computer model of the murine AP (Bondarenko VE, Szigeti GP, Bett GC, Kim SJ, and Rasmusson RL. Computer model of action potential of mouse ventricular myocytes. Am J Physiol Heart Circ Physiol 287: 13781403, 2004) to determine the relative contributions of increased Ito, reduced ICa, and reduced NCX current (INCX) on the shape and kinetics of the AP. Reduction of ICa and elimination of INCX had relatively small effects on the duration of the AP in the computer model. In contrast, AP repolarization was substantially accelerated when Ito was increased in the computer model. Thus, the increase in Ito, and not the reduction of ICa or INCX, is likely to be the major mechanism of AP shortening in KO myocytes. The upregulation of Ito may comprise an important regulatory mechanism to limit Ca2+ influx via a reduction of AP duration, thus preventing Ca2+ overload in situations of reduced myocyte Ca2+ extrusion capacity. genetically altered mice; cardiac myocytes; short QT interval; transient outward current 相似文献
968.
Joseph B. Buchanan R. J. Gutiérrez Robert G. Anthony Tim Cullinan Lowell V. Diller Eric D. Forsman Alan B. Franklin 《Biological invasions》2007,9(6):679-691
The conservation of Spotted Owl (Strix occidentalis) populations has been one of the most controversial and visible issues in United States conservation history. Coincident
with declines in Spotted Owl populations over the last three decades has been the invasion of Barred Owls (Strix varia) throughout the range of the Northern Spotted Owl (S. o. caurina) and into the range of the California Spotted Owl (S. o. occidentalis). This invasion has confused the reasons behind recent Spotted Owl declines because anecdotal and correlative information
strongly suggests that Barred Owls are a new factor influencing the declines. There is great uncertainty about all aspects
of the invasion, and this has sparked discussion about appropriate management and research responses regarding the effects
of this invasion on Spotted Owls. We present a set of possible responses to address the issue, and we discuss the relative
merits of these with regard to their efficacy given the current state of knowledge. We recommend that research specifically
aimed at learning more about the interspecific relationships of these two owls throughout the range of sympatry should begin
immediately. Approaches that seem unlikely to be useful in the short-term either because they do not facilitate knowledge
acquisition, are relatively costly, or would be technically less feasible, should not be considered viable at this time. We
believe the consequences of the invasion are potentially dire for the Spotted Owl and that research and management actions,
including the use of adaptive management, are required to inform the near- and long-term decision-making process for conservation
of Spotted Owls. 相似文献
969.
An approach of combining flow cytometry (FCM) analysis with morphological and chemical profiling was used to assess the genetic
stability and bioactive compound diversity in a Scutellaria baicalensis Georgi (Huang-qin) germplasm collection that was clonally maintained in in vitro for a period of over 6 years. Based on the
FCM analysis of nuclei samples from young shoots, the nuclear DNA content of S. baicalensis was calculated as 0.84 pg/2C. FCM analysis showed no significant variation in the nuclear DNA contents and ploidy levels
in the long-term in vitro maintained germplasm lines. Germplasm lines, acclimatized to ex vitro conditions, exhibited distinctive
plant growth and bioactive compound production capacities. The high level of genetic stability observed in in vitro maintained
S. baicalensis lines opens up a variety of opportunities such as allowing long-term aseptic preservation and easy distribution of well-characterized
germplasm lines of this medicinal plant species. This study represents a novel approach for continuous maintenance, monitoring,
and production of medicinal plant tissues with specific chemistry. 相似文献