| developmental regulation of skull morphology ii: ontogenetic dynamics of covariance. | canalization may play a critical role in molding patterns of integration when variability is regulated by the balance between processes that generate and remove variation. under these conditions, the interaction among those processes may produce a dynamic structure of integration even when the level of variability is constant. to determine whether the constancy of variance in skull shape throughout most of postnatal growth results from a balance between processes generating and removing variatio ... | 2006 | 16409382 |
| do precocial mammals develop at a faster rate? a comparison of rates of skull development in sigmodon fulviventer and mus musculus domesticus. | variation in neonatal maturity among mammals is often explained by variation in gestation length, but species may also differ in developmental rate, a quantity that is difficult to measure because the conventional formalism makes two important and potentially unrealistic assumptions: (1) ontogeny of form can be described by a single line, and (2) species have the same ontogeny of form. we examine two species, one precocial (sigmodon fulviventer), the other altricial (mus musculus domesticus), an ... | 2003 | 14632234 |
| hiv type-1 infection of the cotton rat (sigmodon fulviventer and s. hispidus). | cotton rats (sigmodon hispidus and s. fulviventer) are susceptible to many viruses that infect humans (e.g., poliovirus, respiratory syncytial virus, influenza virus, adenovirus, and parainfluenza virus) and have been influential in developing therapeutic clinical intervention strategies for many viral infections of man. this study set out to determine whether cotton rats are susceptible to infection with hiv type 1 (hiv-1). results indicate that hiv-1 does infect the cotton rat and s. fulvivent ... | 1998 | 9826704 |
| semi-permissive replication and functional aspects of the immune response in a cotton rat model of human parainfluenza virus type 3 infection. | a cotton rat (sigmodon fulviventer) model of human parainfluenza virus type 3 (hpiv-3) infection was used to study patterns of hpiv-3 replication in naive and immune hosts. growth curves revealed that nasal and pulmonary tissues of naive animals were semi-permissive for virus replication, with amounts of progeny virus proportional to inoculating doses. in naive animals there was a total eclipse in nasal tissues beginning 4 h after inoculation. by contrast, there was only partial eclipse of virus ... | 1996 | 8760420 |
| developmental regulation of skull morphology. i. ontogenetic dynamics of variance. | in the absence of processes regulating morphogenesis and growth, phenotypic variance of a population experiencing no selective mortality should increase throughout ontogeny. to determine whether it does, we measure variance of skull shape using geometric morphometrics and examine its ontogenetic dynamics in the precocial cotton rat (sigmodon fulviventer) and the altricial house mouse (mus musculus domesticus). in both species, variance of shape halves between the two youngest samples measured (b ... | 2004 | 15099307 |
| the american cotton rat: a novel model for pulmonary tuberculosis. | several animal models are used to study mycobacterium tuberculosis (mtb) infections, but none is a fully ideal model of human disease. the american cotton rat is an excellent model for the study of several human viral and bacterial respiratory infectious diseases, but until now has not been reported to be a model with mtb infection. preliminary experiments were designed in which two species of cotton rats (sigmodon hispidus and sigmodon fulviventer) received respiratory challenges with m. tuberc ... | 2007 | 16973421 |
| evaluation of cotton rats as a model for severe acute respiratory syndrome. | experimental studies were conducted to evaluate two species of cotton rats, sigmodon hispidus and sigmodon fulviventer, as a model for severe acute respiratory syndrome (sars). blood and turbinate wash samples, and lung tissue were collected from each animal at different time points after sars coronavirus (cov) infection for determining the growth curve of virus, if any, by the standard infectivity assay in vero e6 cells. in addition, sections of the lung, liver, spleen, and kidney were taken an ... | 2008 | 18447621 |
| unilateral nasal infection of cotton rats with respiratory syncytial virus allows assessment of local and systemic immunity. | an in vivo model for the study of local and systemic effectors of immunity to respiratory syncytial virus (rsv) is described. cotton rats (sigmodon fulviventer) inoculated in one nostril with a small volume (2 microliters) of virus suspension contracted a unilateral nasal infection which did not extend to the contralateral nasal turbinates, nor to the lungs. immunity to subsequent rsv challenge could be induced by small priming doses ( < 10 p.f.u. per animal), but was dependent upon viral replic ... | 1996 | 8558116 |
| light microscopic observations on the behavior of silver-stained trivalents in pachytene cells of sigmodon fulviventer (rodentia, muridae) heterozygous for centric fusion. | silver-stained pachytene cells of male cotton rats, sigmodon fulviventer, heterozygous for a naturally occurring robertsonian fusion, were examined by light microscopy. silver staining clearly revealed synaptonemal complexes of all autosomal bivalents and of the translocation trivalent, as well as x-y conformations within the sex vesicle. the synaptonemal complex of the trivalent conforms closely in morphology to that observed by electron microscopy in hybrids of other species. in all cases, the ... | 1980 | 7389417 |
| robertsonian polymorphism in the cotton rat, sigmodon fulviventer. | | 1969 | 5362362 |
| pathogenesis of human parainfluenza virus 3 infection in two species of cotton rats: sigmodon hispidus develops bronchiolitis, while sigmodon fulviventer develops interstitial pneumonia. | human parainfluenza virus 3 replicates well in the noses and lungs of two species of cotton rats, sigmodon hispidus and sigmodon fulviventer. peak viral titers of nearly 10(6) pfu/g are reached 2 days after infection in both tissues, are maintained through day 5, and are equivalent in the two species. infectious virus is eliminated by day 8 after infection. both species produce a strong neutralizing antibody response with titers of 1:10,000 4 weeks after infection. viral replication in the nasal ... | 1991 | 1845878 |
| immunotherapy of respiratory syncytial virus infection in cotton rats (sigmodon fulviventer) using igg in a small-particle aerosol. | to determine whether aerosolized igg can be used effectively in the treatment of respiratory syncytial virus (rsv) infections, cotton rats were infected intranasally with rsv and treated 3 days later with human igg containing anti-rsv antibodies delivered in a small-particle aerosol. pulmonary histology and virus titers were determined 24 h after igg treatment. a single 15-min exposure to aerosolized igg did not exacerbate pulmonary pathology and effected a 50-fold reduction in pulmonary virus t ... | 1992 | 1431258 |
| ontogenetic variation in patterns of developmental and functional integration in skulls of sigmodon fulviventer. | patterns of variation and covariation within populations can influence how characters respond to natural selection and random genetic drift and so constrain the ability of natural selection to modify the phenotype. we examined several potential developmental and functional explanations of character covariation throughout ontogeny using known-age samples of the cotton rat (sigmodon fulviventer) to identify the causes of covariation and to assess the variability of patterns of covariation througho ... | 1989 | 28564197 |
| ontogeny of integrated skull growth in the cotton rat sigmodon fulviventer. | because development is epigenetic, diverse aspects of morphology are integrated during ontogeny. using the method of thin-plate splines, and the decomposition of these splines by their principal warps, we examine the ontogeny of integrated features of skull growth of the cotton rat, sigmodon fulviventer as observed in landmark locations in the ventral view. postnatal growth of the skull in sigmodon is not adequately described by the familiar contrast between relatively rapid facial elongation an ... | 1992 | 28564418 |