Phylogeographic variation among isolates of the Sirococcus conigenus P group     

H. Konrad  C. Stauffer  T. Kirisits  E. Halmschlager 《Forest Pathology》2007,37(1):22-39

In this study the phylogeographic variation among isolates of the Sirococcus conigenus P group and the phylogenetic relationships of S. conigenus with Sirococcus clavigignenti‐juglandacearum and other species previously placed in the genus Sirococcus were investigated. A collection of 33 isolates originating from Picea, Pinus and Larix in Europe, North America and Bhutan were characterized by sequence analyses of the internal transcribed spacer (ITS) region (including ITS1, 5.8S ribosomal DNA, ITS2) of the nuclear rDNA and a portion of the β‐tubulin gene. In phylogenetic analyses most isolates from pine, spruce and larch formed a distinct clade, representing the P group of S. conigenus, which was separated from the T group of this pathogen. Four isolates from Picea in Europe and Canada formed a third clade within S. conigenus and these isolates are referred to as the S group. The P group consisted of five distinct ITS haplotypes, which partly differed in their optimum growth temperature and their growth rates at 25°C on malt extract agar. Nested clade analysis resolved the five haplotypes into three distinct clades and revealed significant genetic/geographic associations for some of the haplotypes. Parsimony analysis of the small subunit (18S) ribosomal DNA sequences confirmed the phylogenetic affinities between S. conigenus and S. clavigignenti‐juglandacearum. In contrast, Godronia cassandrae and Hormococcus conorum, which formerly had been placed in the genus Sirococcus, were found to be only distantly related to S. conigenus and S. clavigignenti‐juglandacearum.  相似文献   

Effects of citrus agriculture on ridge lakes in Central Florida     

Robert E. Stauffer 《Water, air, and soil pollution》1991,59(1-2):125-144

The U.S. EPA sampled 149 lakes in Florida as part of the Eastern Lake Survey. The majority of peninsular survey lakes lying south of 29° latitude have been chemically altered by livestock operations, residential development, and especially citrus agriculture. The numerous doline lakes in citrus belts are highly enriched in K, Na, Mg, Ca, Cl, and SO, because of specific grove practices; here Gran alkalinities are moderately elevated above non-cultural ‘background’ because of liming with dolomite. Seepage lakes in citrus districts also reveal pronounced but erratic enrichment in nitrate, but not P. In Highlands County their trophic state is determined by P and is thus indistinguishable from hydraulically and morphometrically similar lakes lacking cultural influences. Chemical tracers of cultural origin can be used to help resolve the hydraulic properties of regional seepage lakes, and might find application in diagnosing best management practices in their terrestrial catchments.  相似文献   

High-resolution Greenland ice core data show abrupt climate change happens in few years   总被引：1，自引：0，他引：1  

Steffensen JP  Andersen KK  Bigler M  Clausen HB  Dahl-Jensen D  Fischer H  Goto-Azuma K  Hansson M  Johnsen SJ  Jouzel J  Masson-Delmotte V  Popp T  Rasmussen SO  Röthlisberger R  Ruth U  Stauffer B  Siggaard-Andersen ML  Sveinbjörnsdóttir AE  Svensson A  White JW 《Science (New York, N.Y.)》2008,321(5889):680-684

The last two abrupt warmings at the onset of our present warm interglacial period, interrupted by the Younger Dryas cooling event, were investigated at high temporal resolution from the North Greenland Ice Core Project ice core. The deuterium excess, a proxy of Greenland precipitation moisture source, switched mode within 1 to 3 years over these transitions and initiated a more gradual change (over 50 years) of the Greenland air temperature, as recorded by stable water isotopes. The onsets of both abrupt Greenland warmings were slightly preceded by decreasing Greenland dust deposition, reflecting the wetting of Asian deserts. A northern shift of the Intertropical Convergence Zone could be the trigger of these abrupt shifts of Northern Hemisphere atmospheric circulation, resulting in changes of 2 to 4 kelvin in Greenland moisture source temperature from one year to the next.  相似文献   

Genetic comparison of <Emphasis Type="Italic">Ips duplicatus</Emphasis> (Sahlberg, 1836) (Coleoptera: Curculionidae,Scolytinae) populations from Europe and Asia     

Ferenc Lakatos  Wojciech Grodzki  Qing-He Zhang  Christian Stauffer 《Journal of Forest Research》2007,12(5):345-349

The distribution of the double spined spruce engraver beetle Ips duplicatus ranges from Scandinavia and northeastern Europe to northern Asia. In Europe, I. duplicatus usually is associated with I. typographus on Picea abies, and due to morphological similarities and similar gallery constructions the damage and significance of I. duplicatus are often not recognised and thus underestimated. I. duplicatus has been recently reported from the southern part of Poland, the Czech Republic, Slovakia, northern parts of Austria and Germany; records are missing from many other central European countries (e.g., Hungary). The species became an important pest in some parts of central Europe, and continuous outbreaks of this bark beetle have been reported in Inner Mongolia, China, since the 1950s. The aim of this study was to compare I. duplicatus populations from Europe and Asia by genetic means using the analysis of the mitochondrial DNA. Individuals of I. duplicatus populations from China, Poland, the Czech Republic and Slovakia were collected, and 520 bp fragments of the cytochrome oxidase I (COI) gene were analysed. Four haplotypes were detected and a sequence divergence of 0.8% was found between the populations from China and Europe. These differences associate with behavioural differences in the pheromone bouquet and behavioural response of the two groups. Within Europe three haplotypes were found, but due to the small sample size no significant geographical distribution was demonstrated.  相似文献   

Cardiac dysrhythmias during anesthesia for cervical decompression in the dog     

J L Stauffer  R D Gleed  C E Short  H N Erb  Y H Schukken 《American journal of veterinary research》1988,49(7):1143-1146

In a retrospective study, the risk for cardiac dysrhythmias was evaluated in dogs undergoing ventral decompression and/or fenestration of the cervical spine (CERV) and compared with that for dogs undergoing dorsal laminectomy for decompression of the thoracic or lumbar spine (TL). The dogs in the CERV subset (48 dogs) tended to be heavier and older than the dogs in the TL subset (111 dogs). There was no apparent bias detected in treatment before anesthesia and surgery. The risk for dysrhythmias was 2.5 times greater in the CERV subset, compared with that in the TL subset (P less than 0.01). The risk for ventricular premature contraction was 3.5 times higher in the CERV group (P less than 0.05). Bradycardia was found in 6 dogs from the CERV subset and was not found in any dogs from the TL subset. A logistic model was derived from the data and may be used to evaluate the risk for dysrhythmias in similar patients undergoing similar surgery and anesthesia. This model uses age, preoperative heart rate, and site of surgery (CERV or TL) to estimate the risk.  相似文献   

Acetylcholine binding by a synthetic receptor: implications for biological recognition   总被引：25，自引：0，他引：25  

D A Dougherty  D A Stauffer 《Science (New York, N.Y.)》1990,250(4987):1558-1560

The neurotransmitter acetylcholine (ACh) is bound with 50-micromolar affinity by a completely synthetic receptor (host) comprising primarily aromatic rings. The host provided an overall hydrophobic binding site, but one that could recognize the positive charge of the quaternary ammonium group of ACh through a stabilizing interaction with the electron-rich pi systems of the aromatic rings (cation-pi interaction). Similar interactions may be involved in biological recognition of ACh and other choline derivatives.  相似文献   

Oil money and world money: conflict or confluence?     

Stauffer TR 《Science (New York, N.Y.)》1974,184(4134):321-325

  相似文献   

Sulfur vs. silica retention in oligotrophic lake sediments: Test of a simple residence time model     

Robert E. Stauffer 《Water, air, and soil pollution》1995,81(3-4):373-383

Limnologists have modeled solute retention (% of input) in lake sediments using the parameter: 100 k _s {(z:t _w +k _s}^?1, wherek _s is an empirical mass transfer coefficient or ‘sedimentation velocity’ (m yr^?1), z is lake mean depth (m), andt _w is lake hydraulic residence time (yr). This flushing or residence time model was tested against sulfate and silica concentrations in lakes of the northeastern and northcentral U.S.A., using data collected during the U.S. EPA's Eastern Lake Survey. This parameter failed to predict intra-regional variations in lake sulfate at fall turnover, but was consistently negatively correlated with silica in each of the regional lake populations. However, except in the western section of the Upper Peninsula of Michigan, lake sulfate was everywhere inversely dependent on DOC [mean slope=?0.020(SE=0.03) meq mM^?1]. Sulfur retention in aquatic environments appears more closely coupled to organic carbon and trophic state, than to variations in hydraulic residence time.  相似文献   

Behaviour: an important diagnostic tool for Lake Malawi cichlids     

Jay R Stauffer Jr    Kenneth R McKaye  & Ad F Konings 《Fish and Fisheries》2002,3(3):213-224

Historically, the cichlid fishes of Lake Malawi, which probably represent one of the best examples of rapid radiation of vertebrates, have been diagnosed with morphological and genetic data. Many of the populations once thought to be conspecific have been hypothesized to be separate species based on behavioural data. The use of behavioural data, as expressed in mate choice based on colour patterns or bower shapes, has been successfully used to diagnose both rock‐dwelling and sand‐dwelling cichlid species. Additionally, a combination of bower shapes and courtship patterns have been used as synapomorphies to diagnose genera within the Lake Malawi cichlid flock. It is concluded that taxonomists need to include behavioural data with morphological and genetic databases to diagnose species and to determine the phylogenetic relationships within this diverse assemblage of fishes.  相似文献   

An introduction to species concepts and speciation of fishes     

Renea A Ruffing  Patrick M Kocovsky  & Jay R Stauffer Jr 《Fish and Fisheries》2002,3(3):143-145

More than 22 different species concepts have been proposed. The concepts in general reflect the philosophical outlook, particular expertise, and the groups on which the authors are working. The full‐length papers in this special issue dedicated to species concepts relative to fishes are based on presentations by the authors at the 2001 annual meeting of the American Society of Ichthyologists and Herpetologists at University Park, Pennsylvania, USA and generated much discussion on the topic of what constitutes a species.  相似文献