Assuntos
Imidazóis/química , Indóis/química , Complexo de Proteínas Formadoras de Poros Nucleares/antagonistas & inibidores , Proteínas de Ligação a RNA/antagonistas & inibidores , Animais , Apoptose/efeitos dos fármacos , Linhagem Celular , Meia-Vida , Humanos , Imidazóis/farmacologia , Indóis/farmacologia , Células Jurkat , Camundongos , Microssomos Hepáticos/metabolismo , Complexo de Proteínas Formadoras de Poros Nucleares/genética , Complexo de Proteínas Formadoras de Poros Nucleares/metabolismo , Proteínas de Ligação a RNA/genética , Proteínas de Ligação a RNA/metabolismoRESUMO
Ichthyophthirius multifiliis is a ciliated protozoan parasite that infects the skin and gills of freshwater fish. This report describes the unusual finding of I. multifiliis within the peritoneal cavities of experimentally infected channel catfish Ictalurus punctatus. Twenty catfish fingerlings were exposed to I. multifiliis theronts using a standardized protocol. Five infected fish and 2 control fish were killed at various time points after infection and their tissues examined. Formalin-fixed, paraffin embedded sections were processed for light microscopy and immunohistochemical detection of I. multifiliis immobilization antigen. Trophonts were observed in skin and gill sections of all exposed fish. Parasites were associated with epithelial hyperplasia, focal areas of cellular disruption and necrosis. In addition to these usual sites of infection, individual trophonts were unexpectedly found within the peritoneal cavities of 4 fish. Staining for parasite antigen facilitated their detection within abdominal adipose tissue or adjacent to intestines. This discovery is interesting as it suggests I. multifiliis may be found in tissues other than the skin and gills during the course of a normal infection.
Assuntos
Infecções por Cilióforos/veterinária , Cilióforos/isolamento & purificação , Doenças dos Peixes/parasitologia , Ictaluridae , Cavidade Peritoneal/parasitologia , Animais , Infecções por Cilióforos/parasitologia , Brânquias/parasitologia , Ictaluridae/parasitologia , Pele/parasitologiaRESUMO
For animal RNA viruses that replicate through an RNA intermediate, reported examples of bicistronic mRNAs with overlapping open reading frames in which one cistron is contained entirely within another have been made only for those with negative-strand or double-stranded genomes. In this report, we demonstrate for the positive-strand bovine coronavirus that an overlapping open reading frame potentially encoding a 23-kDa protein (names the I [for internal open reading frame] protein) and lying entirely within the gene for the 49-kDa nucleocapsid phosphoprotein is expressed during virus replication from a single species of unedited mRNA. The I protein was specifically immunoprecipitated from virus-infected cells with an I-specific antipeptide serum and was shown to be membrane associated. Many features of I protein synthesis conform to the leaky ribosomal scanning model for regulation of translation. This, to our knowledge, is the first example of a bicistronic mRNA for a cytoplasmically replicating, positive-strand animal RNA virus in which one cistron entirely overlaps another.
Assuntos
Capsídeo/genética , Coronaviridae/genética , Genes Virais/genética , RNA Mensageiro/genética , Proteínas do Core Viral/genética , Proteínas Virais/genética , Proteínas Estruturais Virais/genética , Animais , Sequência de Bases , Bovinos , Dados de Sequência Molecular , Processamento Pós-Transcricional do RNA , Fases de LeituraRESUMO
Milk was collected at 24 h intervals through 120 h after treatment from lactating dairy cows treated with antibiotics. Antibiotic residues were determined qualitatively by microbiological assays utilizing Bacillus stearothermophilus . Intrauterine infusion of antibiotics resulted in the lowest percentage of milk samples positive for residues. A high percentage of samples was positive for residues 24 and 48 h after intramuscular injection of antibiotics; however, most samples were negative by 72 h after treatment. Intramammary therapy resulted in a high proportion of samples positive for residues at 24 and 48 h after treatment, and some samples were positive 96 to 120 h after treatment. Samples from treated quarters were often positive when corresponding composite milk samples were negative. Treatment with more than one antibiotic by multiple routes resulted in the highest percentage of samples positive for residues for the longest time. Any variation of antibiotic dosage, duration of treatment, or use of multiple antibiotics should alert dairy producers of the probability of antibiotics being excreted in milk beyond recommended withdrawal times.
RESUMO
Bovine mammary glands were inoculated intracisternally with a streptomycin-resistant (SR) strain of Corynebacterium bovis to determine the number of colony-forming units (CFU) required to induce colonization and to maintain persistence of C bovis colonization throughout lactation and involution. Streptomycin resistance was used as a strain marker. Uninfected quarters in cows during midlactation were challenge exposed with successively higher numbers of SR C bovis until all quarters became colonized. Inoculum containing 790 CFU of SR C bovis established colonization in only 7 of 38 quarters. Colonization persisted in only 4 of these quarters by 23 days after inoculation. Eleven quarters were reinoculated with higher numbers of SR C bovis, and all became colonized by the time challenge-exposure inoculum contained 8 X 10(4) CFU. Colonization persisted throughout the 93-day experimental period. Somatic cell counts were significantly (P less than 0.01) higher in SR C bovis-colonized quarters after inoculation than before. Sixteen additional quarters were inoculated with a mean number of 8 X 10(4) CFU of SR C bovis 7 days before suppression of lactation. All quarters became colonized, and SR C bovis was shed during the experimental period; throughout the nonlactating and peripartum periods, high numbers of SR C bovis in pure culture were shed from 13 of 16 quarters.
