Transthoracic echocardiographic measurement of patent ductus arteriosus in dogs     

Schneider M  Hildebrandt N  Schweigl T  Wehner M 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2007,21(2):251-257

BACKGROUND: Patent ductus arteriosus (PDA) size and morphology influence the selection of the kind and the size of the embolization device used to effect shunt closure. HYPOTHESIS: That echocardiographic measurement of PDA in dogs is accurate. ANIMALS: Forty-five client-owned dogs with PDA. METHODS: Prospective observational study. Echocardiographic and angiographic data were compared. RESULTS: Measurement of the ductus in color Doppler echocardiography (CD-E) and 2-dimensional echocardiography (2D-E) was achieved from left parasternal views in 43 of 45 unsedated dogs (96%). In these 43 dogs, the angiographic minimal PDA diameter was 3.72 +/- 1.59 mm, and the diameter of the PDA ampulla was 8.46 +/- 3.01 mm. The CD-E minimal PDA diameter ranged from 2.3 to 9.5 mm (median, 4.0 mm). There was a significant mean difference to the angiographic measurements (1.15 +/- 0.95 mm; P < .0001). An agreement in a 1-mm range was found in 21 of 43 dogs (48%). The 2D-E minimal PDA diameter was 3.73 +/- 1.78 mm, and the mean difference to the angiographic measurements was not significant (0.00 +/- 0.72 mm; P = .98). An agreement in a 1-mm range was found in 31 of 43 dogs (72%). The 2D-E measurement of the PDA ampulla revealed a significant mean difference to the angiographic data (1.95 +/- 2.43 mm, P < .0001). An agreement in a 2-mm range was found in 21 of 43 dogs (49%). CONCLUSIONS AND CLINICAL IMPORTANCE: The 2D-E from the left cranial parasternal view is an excellent noninvasive method to estimate the PDA minimal diameter before doing catheter intervention.  相似文献   

Maximum foraging ranges in solitary bees: only few individuals have the capability to cover long foraging distances   总被引：2，自引：0，他引：2  

Antonia Zurbuchen  Jeannine Klaiber  Silke Hein 《Biological conservation》2010,143(3):669-361

To preserve populations of endangered bee species, sound knowledge of their maximum foraging distance between nest and host plants is crucial. Previous investigations predicted maximum foraging distances of 100-200 m for small bee species and up to 1100 m for very large species based on mainly indirect methods. The present study applied a new and direct approach to experimentally investigate maximum foraging distances in solitary bees. One endangered and two common species of different body sizes, all of which restrict pollen foraging to a single plant genus, were established in a landscape lacking their specific host plants. Females were forced to collect pollen on potted host plants that were successively placed in increasing distance from fixed nesting stands. The maximum foraging distance recorded for the small Hylaeus punctulatissimus was 1100 m, for the medium sized Chelostoma rapunculi 1275 m and for the large Hoplitis adunca 1400 m, indicating that maximum foraging distances at species level have been underestimated. However, the capability to use resources on such a large spatial scale applied only to a small percentage of individuals as 50% of the females of H. punctulatissimus and H. adunca did not forage at distances longer than 100-225 m and 300 m, respectively. This finding suggests that a close neighbourhood of nesting and foraging habitat within few hundred meters is crucial to maintain populations of these species, and that threshold distances at which half of the population discontinues foraging are a more meaningful parameter for conservation practice than the species specific maximum foraging distances.  相似文献   

Plant pathogen protection by arbuscular mycorrhizas: A role for fungal diversity?     

Jeannine Wehner 《Pedobiologia》2010,53(3):197-201

Arbuscular mycorrhizal (AM) fungi can confer protection to host plants against some root pathogens, and several mechanisms for these phenomena have been proposed. If AM fungal taxa vary in the ways that they limit the negative effects of pathogens on host plants, additive and/or synergistic interactions among members of diverse AM fungal assemblages and communities may result in a greater pathogen protection than is currently predicted. However, in a review of the literature on interactions between AM and pathogenic fungi, we found few examples that compared the effectiveness of single- and multi-species AM fungal assemblages. Here, we briefly recount the generally recognized mechanisms of pathogen protection by AM fungi and present evidence, where appropriate, for functional diversity among AM fungal taxa with regard to these mechanisms. We propose that functional complementarity of AM fungal taxa in interactions with pathogens could mimic, or even be the cause of, previously observed relationships between AM fungal diversity and plant productivity.  相似文献   

Effect of inbreeding on horticultural performance of lines developed from an open-pollinated pickling cucumber population     

David B. Rubino  Todd C. Wehner 《Euphytica》1986,35(2):459-464

Summary The effect of self-pollination of cucumber (Cucumis sativus L.) for 6 generations in lines developed from the North Carolina Medium Base Pickle population was determined by regression of trait expression for each generation on Wright's coefficient of inbreeding. Two yield traits (total and marketable), earliness and 3 fruit quality traits (shape, color and seedcell size) were evaluated in 2 environments (spring and summer, 1983). The regression did not result in significant negative slopes, indicating that inbreeding depression was not important in the population for the traits studied. Midparent heterosis was found for most traits in many hybrids obtained from crossing S₆ lines with the gynoecious inbred line, Gy 14A.  相似文献   

Responses     

Silva AJ  Paylor R  Wehner JM  Tonegawa S 《Science (New York, N.Y.)》1993,262(5134):761-762

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Requirement of Cks2 for the first metaphase/anaphase transition of mammalian meiosis     

Spruck CH  de Miguel MP  Smith AP  Ryan A  Stein P  Schultz RM  Lincoln AJ  Donovan PJ  Reed SI 《Science (New York, N.Y.)》2003,300(5619):647-650

We generated mice lacking Cks2, one of two mammalian homologs of the yeast Cdk1-binding proteins, Suc1 and Cks1, and found them to be viable but sterile in both sexes. Sterility is due to failure of both male and female germ cells to progress past the first meiotic metaphase. The chromosomal events up through the end of prophase I are normal in both CKS2-/- males and females, suggesting that the phenotype is due directly to failure to enter anaphase and not a consequence of a checkpoint-mediated metaphase I arrest.  相似文献   

Homing in the ant Cataglyphis bicolor     

R Wehner  R Menzel 《Science (New York, N.Y.)》1969,164(876):192-194

Cataglyphis bicolor, an ant widely distributed in North Africa and the Near East, orient to the sun as well as to visual patterns of the environment. These two mechanisms can be separated. Foraging ants (hunters) orient to terrestrial cues as long as possible, and only after these have become ineffective do they switch over to the menotactical sun orientation. In the digging individuals, however, the visual knowledge of locality is significantly inferior to that of the hunters. Diggers vary considerably in size, but hunters belong to the largest size group. In addition, the largest and smallest individuals orient differently toward black and white areas and stripe patterns.  相似文献   

Organic-geochemical Differentiation of Petroleum-type Pollutants and Study of Their Fate in Danube Alluvial Sediments and Corresponding Water (Pančevo Oil Refinery, Serbia)     

Branimir Jovančićević  Miroslav Vrvić  Jan Schwarzbauer  Hermann Wehner  Georg Scheeder  Dragomir Vitorović 《Water, air, and soil pollution》2007,183(1-4):225-238

A review is given in this paper of the up-to-date results observed in differentiation and transformation studies on petroleum-type pollutants in underground and surface waters. Water and particulate matter derived from the locality of Pan?evo Petroleum Refinery, Serbia (River Danube alluvial formations). It was shown that distributions of n-alkanes, steranes and triterpanes, and δ¹³C_PDB values of n-alkanes may successfully be used for qualitatively differentiating the petroleum-type pollutants from native organic matter in recent sedimentary formations. In underground waters, a petroleum-type pollutant is exposed to microbiological degradation which is manifested through relatively fast degradation of n-alkanes. Following an almost complete degradation of crude oil n-alkanes in underground water, the biosynthesis of novel, even carbon-number C₁₆–C₃₀ n-alkanes may be observed. It is shown that the n-alkane distribution observed in a petroleum-type pollutant may depend on the intensity of its previous interaction with water. The fate of petroleum-type pollutants in environmental waters may be predicted through laboratory simulative microbiological degradation experiments by using microorganism consortiums similar to those observed under relevant natural conditions, as well as on corresponding nutrient base.  相似文献   

Genetic diversity among watermelon (Citrullus lanatus and Citrullus colocynthis) accessions     

Amnon Levi  Claude E. Thomas  Anthony P. Keinath  Todd C. Wehner 《Genetic Resources and Crop Evolution》2001,48(6):559-566

Genetic diversity was estimated among 42 U.S. PlantIntroduction (PI) accessions of the genusCitrullus (of these, 34 PIs are reported tohave disease resistance), and 5 watermelon cultivars, using 30RAPD primers. These primers produced 662 RAPD markers that could berated with high confidence. Based on these markers, geneticsimilarity coefficients were calculated and a dendrogram wasconstructed using the unweighted pair-group method witharithmetic average (UPGMA). The analysis delineated threemajor clusters. The first cluster consisted of a group of fivewatermelon cultivars, a group of C.lanatus var. lanatusaccessions, and a group of C.lanatus var. lanatusaccessions that contained some C.lanatus var. citroidesgenes. The second cluster consisted of the C.lanatus var. citroidesaccessions, while the third cluster consisted of theC. colocynthis accessions.The two C. lanatus clustersdifferentiated from each other and from the C.colocynthis cluster at the level of 58.8%and 38.9% genetic similarity, respectively. Assessment ofgenetic diversity among accessions that have been reported to havedisease resistance indicated that resistance to either anthracnose,downy mildew, powdery mildew, or watermelon mosaic virus is foundamong all major groups of Citrullus PIs.Additionally, resistance to gummy stem blight or Fusarium wilt mayexist among C. lanatus var.citroides PIs. This study demonstrates thatmolecular markers can be useful in assessing genetic diversity, andin sorting Citrullus PIs into phylogeneticgroups prior to their evaluation for disease or pestresistance.  相似文献   

Tularemia: emergence/re-emergence     

Petersen JM  Schriefer ME 《Veterinary research》2005,36(3):455-467

Francisella tularensis is a gram-negative coccobacillus and the etiologic agent of the zoonotic disease tularemia. First described in 1911 in Tulare County, California, it has since been reported throughout the Northern Hemisphere, with natural infections reported among an unusually wide range of vertebrates and invertebrates. In recent years, tularemia has emerged in new geographic locations, populations, and settings. This review will serve to highlight mechanisms contributing to the recent emergence of tularemia as well as a repertoire of diagnostic tools useful for detecting and diagnosing disease.  相似文献