The theropod ancestry of birds: new evidence from the late cretaceous of madagascar     

CA Forster  SD Sampson  LM Chiappe  DW Krause 《Science (New York, N.Y.)》1998,279(5358):1915-1919

A partial skeleton of a primitive bird, Rahona ostromi, gen. et sp. nov., has been discovered from the Late Cretaceous of Madagascar. This specimen, although exhibiting avian features such as a reversed hallux and ulnar papillae, retains characteristics that indicate a theropod ancestry, including a pubic foot and hyposphene-hypantra vertebral articulations. Rahona has a robust, hyperextendible second digit on the hind foot that terminates in a sicklelike claw, a unique characteristic of the theropod groups Troodontidae and Dromaeosauridae. A phylogenetic analysis places Rahona with Archaeopteryx, making Rahona one of the most primitive birds yet discovered.  相似文献   

Twin pregnancies following transfer of single embryos in three mares: A case report     

Patrick M. McCue DVM  PhD  Jill Thayer DVM  Edward L. Squires PhD  Steven P. Brinsko DVM  PhD  Dirk K. Vanderwall DVM  PhD 《Journal of Equine Veterinary Science》1998,18(12):832-834

Spontaneous development of identical or monozygotic twins is a rare event in the horse. Monozygotic twins develop after division of a single embryo. This report documents three cases in which twin embryos developed following surgical transfer of a single morula stage embryo into the uterus of a synchronized recipient mare.  相似文献   

Roles of bootstrap resampling,measure of central tendency,and method for calculating thermal units when developing phenology models for pest management     

DE Legg  SM Van Vleet  DW Ragsdale  RW Hansen  LC Skinner  TR Collier 《国际虫害防治杂志》2013,59(4):319-325

The successful development of phenology models from field studies depends on many factors, some of which are entirely under the control of pest managers. For example, one such factor is the choice of method for calculating thermal units. In this study, we have demonstrated that four methods for calculating thermal units provided for acceptable predictions of one phenological event of one insect species, while another method for calculating thermal units did not. The measure of central tendency (mean or median) that is used to estimate lower developmental temperatures and required thermal summations is another factor that pest managers can control when developing phenology models from field studies. Here, we show that predictions that were made when using phenology models based on median lower developmental temperatures and median required thermal summations were superior to predictions that were made when using phenology models based on mean lower developmental temperatures and mean required thermal summations. The use of bootstrap vs. non-bootstrap estimates of lower developmental temperatures and required thermal summations is yet another factor that pest managers can control when developing phenology models from field studies. In this study, we found that calculating and using bootstrap estimates of lower developmental temperatures and required thermal summations in phenology models did not improve the predictions of one phenological event for one insect species. The implications of these and other findings are discussed.  相似文献   

Long‐term Effects of Pyrethrin and Cyfluthrin,a Type II Synthetic Pyrethroid,Insecticide Applications on Bull Reproductive Parameters          下载免费PDF全文

JL Stewart  CF Shipley  FA Ireland  VL Jarrell  CL Timlin  DW Shike  TL Felix 《Reproduction in domestic animals》2016,51(5):680-687

The objectives of this study were to determine effects of cyfluthrin and pyrethrin spray products, used in combination with cyfluthrin topical and ear tag applications, on bull reproductive parameters over 18 weeks. Angus or Angus x Simmental bulls were randomly assigned to one of three treatment groups: (i) no exposure to pyrethrins/cyfluthrin (CONT; n = 10), (ii) cyfluthrin ear tag and topical applications (ET; n = 10), or (iii) cyfluthrin ear tag, topical, premise spray and pyrethrin fog spray applications (ET+S; n = 8). Bull body weight was measured every 3 week, and body condition score and scrotal circumference were recorded on weeks 0, 9 and 18. Semen and serum were collected every 3 weeks for sperm evaluation and testosterone measurement, respectively. There was a treatment × week interaction (p < 0.01) for sperm with primary defects; bulls in CONT group had a greater (p = 0.01) percentage of sperm with primary defects than bulls treated with insecticides at week 18. Overall and progressive sperm motility, normal sperm morphology, secondary sperm defects and serum testosterone concentrations changed (p < 0.01) over time in all bulls; however, treatment did not affect (p ≥ 0.13) any of these parameters. There were also no treatment effects (p ≥ 0.08) on bull body weight, body condition score or scrotal circumference. The use of pyrethrin‐ and cyfluthrin‐based insecticides, regardless of application, did not negatively affect reproductive parameters in beef bulls when administered over 18 weeks.  相似文献   

The first reported case of equine Nocardioform placentitis in New Zealand     

DW Hanlon  AD McLachlan  I Gibson 《New Zealand veterinary journal》2016,64(3):198-199

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Introduction of Radioactive Sulfur (S35) Into the Penicillin Molecule by Biosynthesis     

Howell SF  Thayer JD  Labaw LW 《Science (New York, N.Y.)》1948,107(2777):299-300

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The immune response and maternal antibody interference to a heterologous H1N1 swine influenza virus infection following vaccination   总被引：4，自引：0，他引：4  

Kitikoon P  Nilubol D  Erickson BJ  Janke BH  Hoover TC  Sornsen SA  Thacker EL 《Veterinary immunology and immunopathology》2006,112(3-4):117-128

This study investigated the efficacy of a bivalent swine influenza virus (SIV) vaccine in piglets challenged with a heterologous H1N1 SIV isolate. The ability of maternally derived antibodies (MDA) to provide protection against a heterologous challenge and the impact MDA have on vaccine efficacy were also evaluated. Forty-eight MDA(+) pigs and 48 MDA(-) pigs were assigned to 8 different groups. Vaccinated pigs received two doses of a bivalent SIV vaccine at 3 and 5 weeks of age. The infected pigs were challenged at 7 weeks of age with an H1N1 SIV strain heterologous to the H1N1 vaccine strain. Clinical signs, rectal temperature, macroscopic and microscopic lesions, virus excretion, serum and local antibody responses, and influenza-specific T-cell responses were measured. The bivalent SIV vaccine induced a high serum hemagglutination-inhibition (HI) antibody titer against the vaccine virus, but antibodies cross-reacted at a lower level to the challenge virus. This study determined that low serum HI antibodies to a challenge virus induced by vaccination with a heterologous virus provided protection demonstrated by clinical protection and reduced pneumonia and viral excretion. The vaccine was able to prime the local SIV-specific antibody response in the lower respiratory tract as well as inducing a systemic SIV-specific memory T-cell response. MDA alone were capable of suppressing fever subsequent to infection, but other parameters showed reduced protection against infection compared to vaccination. The presence of MDA at vaccination negatively impacted vaccine efficacy as fever and clinical signs were prolonged, and unexpectedly, SIV-induced pneumonia was increased compared to pigs vaccinated in the absence of MDA. MDA also suppressed the serum antibody response and the induction of SIV-specific memory T-cells following vaccination. The results of this study question the effectiveness of the current practice of generating increased MDA levels through sow vaccination in protecting piglets against disease.  相似文献   

Molecular detection and serotyping of infectious bronchitis virus from FTA filter paper     

Moscoso H  Raybon EO  Thayer SG  Hofacre CL 《Avian diseases》2005,49(1):24-29

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Data from 11 years of molecular typing infectious bronchitis virus field isolates     

Jackwood MW  Hilt DA  Lee CW  Kwon HM  Callison SA  Moore KM  Moscoso H  Sellers H  Thayer S 《Avian diseases》2005,49(4):614-618

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MyoD1: a nuclear phosphoprotein requiring a Myc homology region to convert fibroblasts to myoblasts   总被引：102，自引：0，他引：102  

S J Tapscott  R L Davis  M J Thayer  P F Cheng  H Weintraub  A B Lassar 《Science (New York, N.Y.)》1988,242(4877):405-411

Expression of a complementary DNA (cDNA) encoding the mouse MyoD1 protein in a variety of fibroblast and adipoblast cell lines converts them to myogenic cells. Polyclonal antisera to fusion proteins containing the MyoD1 sequence show that MyoD1 is a phosphoprotein present in the nuclei of proliferating myoblasts and differentiated myotubes but not expressed in 10T1/2 fibroblasts or other nonmuscle cell types. Functional domains of the MyoD1 protein were analyzed by site-directed deletional mutagenesis of the MyoD1 cDNA. Deletion of a highly basic region (residues 102 to 135) interferes with both nuclear localization and induction of myogenesis. Deletion of a short region (residues 143 to 162) that is similar to a conserved region in the c-Myc family of proteins eliminates the ability of the MyoD1 protein to initiate myogenesis but does not alter nuclear localization. Deletions of regions spanning the remainder of MyoD1 did not affect nuclear localization and did not inhibit myogenesis. Furthermore, expression of only 68 amino acids of MyoD1, containing the basic and the Myc similarity domains, is sufficient to activate myogenesis in stably transfected 10T1/2 cells. Genetic analysis maps the MyoD1 gene to mouse chromosome 7 and human chromosome 11.  相似文献