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Otis D. R. Jr; Johnson M.; Pedley T. J.; Kamm R. D. 《Journal of applied physiology》1993,75(3):1323-1333
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The inactivation kinetics of bacteriophage f2 were studied by using ozone under controlled laboratory conditions. The phage were rapidly inactivated during the first 5 s of the reaction by 5 and 7 logs at ozone concentrations of 0.09 and 0.8 mg/liter, respectively. During the next 10 min, the phage were further inactivated at a slower rate in both treatments. The [3H]uridine-labeled f2 phage and its ribonucleic acid (RNA) were examined to elucidate the mechanism of ozone inactivation, utilizing adsorption to host bacteria, sucrose density gradient analysis, and electron microscopy. The specific adsorption of the phage was reduced by ozonation in the same pattern as plaque-forming unit reduction. RNA was released from the phage particles during ozonation, although it had reduced infectivity for spheroplasts. Electron microscopic examination showed that the phage coat was broken by ozonation into many protein subunit pieces and that the specific adsorption of the phage to host pili was inversely related to the extent of phage breakage. The RNA enclosed in the phage coat was inactivated less by ozonation than were whole phage, but inactivated more than naked RNA. These findings suggest that ozone breaks the protein capsid into subunits, liberating RNA and disrupting adsorption to the host pili, and that the RNA may be secondarily sheared by a reduction with and/or without the coat protein molecules, which have been modified by ozonation. 相似文献
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Chronological ages of Alouattaon Barro Colorado Island (BCI) were estimated from longitudinal dental wear. Combining these data with visual censuses, we
approximated the study population’s age profile. A stable model was then constructed; from it we derived agespecific mortality
rates. Mortality of immature animals is high, with 88% of the males and 65% of the females dying before 5 years. Adult mortality
is low until 11 years, when it accelerates. The average adult life span is 16.6 years for males and 15.5 for females. The
maximum life span is over 20 years. A pubertal male growth spurt occurs from 3 to 5 years, at which time females are primiparous.
Sexual size differences develop primarily during this time. The 1976 age profile had anomalously few animals aged 7 years
and males aged 8–9 and 15–16 years. With corroborating evidence, we hypothesize that these deficits resulted from excessive
rainfall in 1963 and 1971, which reduced the fall fruit crop and led to a high juvenile mortality. Within half of our study
troops, some adult males have nearly identical ages, suggesting an active process of agemate coalition. We hypothesize a form
of kin selection, wherein peripheral male cohorts from the same natal troop have greater survival and social success than
solitary animals. The stable model suggests an annual growth rate of 1.5% during the 1970s. Estimates of 16.7 and 4% for the
previous two decades, following a yellow-fever epidemic, imply that the BCI population is becoming stationary. A very different
age structure existed on neighboring Orchid Island in 1976, suggesting general food limitation. By contrast, the lowered,
but continuing growth on BCI suggests a less drastic limiting mechanism. We hypothesize that intratroop social competition
limits population growth by regulating subadult survival rates during food scarcity cycles. 相似文献
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Honey bee larvae are frequently inspected and, sometimes, provided with food by adult workers, but the stimuli that elicit the important task of food provisioning have never been investigated. Larvae with their food experimentally deprived received more frequent inspection and feeding visits from nurse bees than normally fed larvae, suggesting that there could be a hunger signal. Food-deprived larvae with artificially supplied larval food received the same rate of feeding visits from nurse bees as did normally fed larvae but still received more inspection visits. These results suggest that stimuli eliciting feeding are different from those for inspection. They also support the hypothesis that worker bees deposit food in a larval cell only when the quantity of food is below a certain minimum threshold that is perceived during larval inspections. A model is presented regarding the stimuli from larvae that result in worker feeding behavior. 相似文献
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E. coli chromosomal DNA wastreated with various Pt co-ordiantion compounds and then used as donor DNA in E. coli transformation. Genetic analysis of transformants obtained with Pt-treated DNA showed effects of cis-diamminedichloroplatinum(II) (cis-Pt(II)) and cis-dimethyl-1,3-diaminopropane CL4 (cis-Pt(IV) (DMDAP) on the processing of DNA. With trans-diamminedichloroplatinum(II) (trans-Pt(II)) appllied in similar concentrations no effects were found.The effects of cis-Pt(II) and cis-Pt(IV) (DMDAP) on the genetic processing were different. The effects of cis-Pt(II) could be explained by assuming intra-strand crosslinks as an important lesion. 相似文献