Disturbance and species composition drive canopy structure and distribution of large trees in Olympic rainforests,USA     

Kramer  Russell D.  Sillett  Stephen C.  Kane  Van R.  Franklin  Jerry F. 《Landscape Ecology》2020,35(5):1107-1125

Landscape Ecology - Western Olympic valley bottoms, disturbed by alluvial processes, are dominated by Picea sitchensis and isolated cohorts of Pseudotsuga menziesii, while upland contexts,...  相似文献   

Habitat selection by spotted owls after a megafire reflects their adaptation to historical frequent-fire regimes     

Jones  Gavin M.  Kramer  H. Anu  Whitmore  Sheila A.  Berigan  William J.  Tempel  Douglas J.  Wood  Connor M.  Hobart  Brendan K.  Erker  Tedward  Atuo  Fidelis A.  Pietrunti  Nicole F.  Kelsey  Rodd  Gutiérrez  R. J.  Peery  M. Zachariah 《Landscape Ecology》2020,35(5):1199-1213

Context

Climate and land-use change have led to disturbance regimes in many ecosystems without a historical analog, leading to uncertainty about how species adapted to past conditions will respond to novel post-disturbance landscapes.

Objectives

We examined habitat selection by spotted owls in a post-fire landscape. We tested whether selection or avoidance of severely burned areas could be explained by patch size or configuration, and whether variation in selection among individuals could be explained by differences in habitat availability.

Methods

We applied mixed-effects models to GPS data from 20 spotted owls in the Sierra Nevada, California, USA, with individual owls occupying home ranges spanning a broad range of post-fire conditions after the 2014 King Fire.

Results

Individual spotted owls whose home ranges experienced less severe fire (<?5% of home range severely burned) tended to select severely burned forest, but owls avoided severely burned forest when more of their home range was affected (~ 5–40%). Owls also tended to select severe fire patches that were smaller in size and more complex in shape, and rarely traveled?>?100-m into severe fire patches. Spotted owls avoided areas that had experienced post-fire salvage logging but the interpretation of this effect was nuanced. Owls also avoided areas that were classified as open and/or young forest prior to the fire.

Conclusions

Our results support the hypothesis that spotted owls are adapted to historical fire regimes characterized by small severe fire patches in this region. Shifts in disturbance regimes that produce novel landscape patterns characterized by large, homogeneous patches of high-severity fire may negatively affect this species.

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Virus-induced gene silencing as a tool for functional analyses in the emerging model plant Aquilegia (columbine, Ranunculaceae)     

Billie Gould  Elena M Kramer 《Plant methods》2007,3(1):6

Background  

The lower eudicot genus Aquilegia, commonly known as columbine, is currently the subject of extensive genetic and genomic research aimed at developing this taxon as a new model for the study of ecology and evolution. The ability to perform functional genetic analyses is a critical component of this development process and ultimately has the potential to provide insight into the genetic basis for the evolution of a wide array of traits that differentiate flowering plants. Aquilegia is of particular interest due to both its recent evolutionary history, which involves a rapid adaptive radiation, and its intermediate phylogenetic position between core eudicot (e.g., Arabidopsis) and grass (e.g., Oryza) model species.  相似文献   

Potential Risk Factors Associated with Bovine Spongiform Encephalopathy in Cattle from Schleswig‐Holstein,Germany     

C. Pottgießer  A. Ovelhey  M. Ziller  M. Kramer  T. Selhorst  F. J. Conraths 《Zoonoses and public health》2006,53(7):306-311

Since the first detection of bovine spongiform encephalopathy (BSE) in homebred cattle in Germany on 26 November 2000, 382 cases have been confirmed until 30 September 2005. Thirty‐two of these cases were reported from the Federal State of Schleswig‐Holstein (SH). There are hypotheses on the routes of infection for German cattle, but only few efforts have been made to assess potential risk factors by epidemiological studies. The purpose of this study was to identify potential risk factors at the farm level for the occurrence of BSE in cattle in SH. By applying the method of indirect standardization, the prevalence of various structural and management parameters of BSE‐affected farms in SH was compared with the prevalence of these parameters in a standard population of cattle farms from SH. The data describing the standard population were obtained by a cross‐sectional study performed in SH in 2003. Data of the BSE case population were available from the central German BSE case database. A possible association of the occurrence of BSE with the feeding of milk replacers to calves was observed. There was a clear indication that the occurrence of BSE was associated with the presence of pigs and/or poultry on the farm. This finding suggests that cross‐contamination of feed or cross‐exposition may have occurred in SH. The results obtained using the indirect standardization analysis were validated by multiple logistic regression. This study indicates that the feedborne path has been the principal route of transmission for the BSE agent in SH.  相似文献   

Feline heartworm infection: serological survey of asymptomatic cats living in northern Italy.     

L Kramer  C Genchi 《Veterinary parasitology》2002,104(1):43-50

Heartworm infection is now recognized as a potential cause of serious disease in cats. Epidemiological studies indicate that in locations where the infection is endemic in the dog, cats are at risk. The aim of this work was to carry out a serological survey for the presence of anti-Dirofilaria immitis antibodies in privately owned, predominantly asymptomatic cats living in different areas of northern Italy in order to determine the distribution of the parasite and the risk of infection in this species. Serum samples from 1045 cats were evaluated using a commercial antibody (Ab) detection kit (Heska Solo Step Filariosi Felina, Heska Corporation) and results were analyzed together with information obtained by questionnaire. Results showed that 16% of all tested cats were positive for anti-D. immitis antibodies, with values ranging from 9 to 27%, depending on location. Male cats and outdoor cats appeared to be at greater risk, with a significantly higher number of positive antibody tests. The results of this study suggest that the risk of exposure with D. immitis in cats is high in northern Italy and suggest that the use of preventive drugs would be advisable in this area endemic for canine heartworm disease.  相似文献   

A von Willebrand's factor genomic nucleotide variant and polymerase chain reaction diagnostic test associated with inheritable type-2 von Willebrand's disease in a line of german shorthaired pointer dogs     

Kramer JW  Venta PJ  Klein SR  Cao Y  Schall WD  Yuzbasiyan-Gurkan V 《Veterinary pathology》2004,41(3):221-228

Heritable, type-2 von Willebrand's disease (vWD) was studied in a line of German Shorthaired Pointers (GSPs) in which some members had a nucleotide variant in exon 28 of the von Willebrand factor (VWF) gene. A polymerase chain reaction (PCR) diagnostic test for the nucleotide variant was developed to establish the disorder's mode of inheritance and to eliminate it from the line. Thirty-six of the 49 GSPs in the line, 14 unrelated GSP controls, and 71 unrelated dogs of various breeds were tested for the presence of the variant nucleotide. All the dogs with a vWF antigen deficiency (<70% of normal) were either homozygous or heterozygous for the nucleotide variant. The variant was not located in any tested dog in the line or outside of the line with a vWF antigen value greater than 68%. Of the GSPs in the line tested, two were homozygous for the variant, 15 were heterozygous, and 19 were variant free. The collective evidence of this and other studies is consistent with the variant nucleotide being the cause of the type-2 vWD in this line of GSPs and German Wirehaired Pointers. The PCR diagnostic test for the variant nucleotide was successfully used to select and produce progeny that were variant free and vWD free. This test should be effective in the subsequent elimination of this same variant from other lines of dogs.  相似文献   

Detection of spinal ataxia in horses using fuzzy clustering of body position uncertainty     

Keegan KG  Arafat S  Skubic M  Wilson DA  Kramer J  Messer NM  Johnson PJ  O'Brien DP  Johnson G 《Equine veterinary journal》2004,36(8):712-717

REASONS FOR PERFORMING STUDY: Subjective neurological evaluation in horses is prone to bias. An objective method of spinal ataxia detection is not subject to these limitations and could be of use in equine practice and research. HYPOTHESIS: Kinematic data in the walking horse can differentiate normal and spinal ataxic horses. METHODS: Twelve normal and 12 spinal ataxic horses were evaluated by kinematic analysis walking on a treadmill. Each body position signal was reduced to a scalar measure of uncertainty then fuzzy clustered into normal or ataxic groups. Correct classification percentage (CCP) was then calculated using membership values of each horse in the 2 groups. Subsequently, a guided search for measure combinations with high CCP was performed. RESULTS: Eight measures of body position resulted in CCP > or = 70%. Several combinations of 4-5 measures resulted in 100% CCP. All combinations with 100% CCP could be obtained with one body marker on the back measuring vertical and horizontal movement and one body marker each on the right fore- and hindlimb measuring vertical movement. CONCLUSIONS AND POTENTIAL RELEVANCE: Kinematic gait analysis using simple body marker combinations can be used objectively to detect spinal ataxia in horses.  相似文献   

Soil biological properties in multistrata successional agroforestry systems and in natural regeneration     

Raul Matias Cezar  Fabiane Machado Vezzani  Daniel Kramer Schwiderke  Sérgio Gaiad  George Gardner Brown  Carlos Eduardo Sícoli Seoane  Luís Cláudio Maranhão Froufe 《Agroforestry Systems》2015,89(6):1035-1047

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Wistar rats from different suppliers have a different response in an acute myocardial infarction model     

B.A. Naaijkens  A. van Dijk  E. Meinster  K. Kramer  O. Kamp  P.A.J. Krijnen  H.W.M. Niessen  L.J.M. Juffermans 《Research in veterinary science》2014

The Wistar rat is a commonly used strain for experimental animal models. Recently it was shown that results vary between studies using Wistar rats of different suppliers. Therefore we studied whether Wistar rats obtained from Harlan Laboratories (Ha, n = 24) and Charles River (CR, n = 22) had a different outcome in an acute myocardial infarction (AMI) model. AMI was induced in both Ha and CR Wistar rats by one operator. This resulted in a significantly higher survival rate for Ha (79.2 ± 10.2%) compared with CR rats (54.2 ± 10.2%, p < 0.05). Furthermore, CR rats had lost significantly more weight after 7 days (−5.9 ± 3.1%) compared with Ha rats (−0.8 ± 1.7%; p < 0.001), indicating a worse health status of the CR rats. Paradoxically, the induced infarct was smaller in CR rats (7.3 ± 3.6% of the heart) compared with Ha rats (12.1 ± 4.7%, p < 0.05). This indicates that CR rats were less sensitive for the cardiomyocyte damage subsequent to AMI induction, but remarkably showed more clinical side effects indicating that Wistar rats from two suppliers had a different response within the same AMI model.  相似文献   

Systemic Immunosuppression by Methylprednisolone and Pregnancy Rates in Goats Undergoing the Transfer of Cloned Embryos     

C Feltrin  CA Cooper  N Mohamad‐Fauzi  VHV Rodrigues  LH Aguiar  S Gaudencio‐Neto  LT Martins  CEM Calderón  AS Morais  IS Carneiro  TM Almeida  ING Silva  JL Rodrigues  EA Maga  JD Murray  AB Libório  LR Bertolini  M Bertolini 《Reproduction in domestic animals》2014,49(4):648-656

The presence of the zona pellucida has been perceived as a requirement for the oviductal transfer of cloned embryos at early stages of development while protecting the embryo from an immune system response. We hypothesized that steroid hormone therapy could reduce a potential cellular immune response after the transfer of zona‐free cloned embryos into the oviduct of recipient female goats. In Experiment 1, seven does were used to study the systemic immunosuppressant effect of the methylprednisolone administration (for 3 days) on blood cell counts. Whole blood was collected prior to treatment with methyprednisolone and then on Days 1, 2, 3, 4, 7, 14, 21 and 28 after the first dose of methylprednisolone for the analysis of haematological parameters. Methylprednisolone treatment significantly reduced circulating white blood cells and neutrophils in comparison with pre‐treatment levels, demonstrating a systemic immunosuppressant effect. In Experiment 2, a group of 58 does were used as recipient females to study the effect of administration of methylprednisolone for 3 days on the establishment of pregnancies after the transfer of zona‐free cloned embryos into the oviducts. No effects on pregnancy rates on Day 30 were observed regarding the distinct treatment groups (control vs. methylprednisolone), the source of oocytes (in vivo‐ vs in vitro‐matured) or the presence or absence of the zona pellucida in embryos. In summary, methylprednisolone was effective at inducing a systemic immunosuppressed state in goats, but the treatment prior to embryo transfer did not affect pregnancy rates. Moreover, pregnancy rates were similar between zona‐free and zona‐intact goat cloned embryos.  相似文献