Biology of Francisella tularensis Subspecies holarctica Live Vaccine Strain in the Tick Vector Dermacentor variabilis

Background: The c-proteobacterium Francisella tularensis is the etiologic agent of seasonal tick-transmitted tularemia epizootics in rodents and rabbits and of incidental infections in humans. The biology of F. tularensis in its tick vectors has not been fully described, particularly with respect to its quanta and duration of colonization, tissue dissemination, and transovarial transmission. A systematic study of the colonization of Dermacentor variabilis by the F. tularensis subsp. holarctica live vaccine strain (LVS) was undertaken to better understand whether D. variabilis may serve as an inter-epizootic reservoir for F. tularensis. Methodology/Principal Findings: Colony-reared larva, nymph, and adult D. variabilis were artificially fed LVS via glass capillary tubes fitted over the tick mouthparts, and the level of colonization determined by microbial culture. Larvae and nymphs were initially colonized with 8.860.8610 1 and 1.160.03610 3 CFU/tick, respectively. Post-molting, a significant increase in colonization of both molted nymphs and adults occurred, and LVS persisted in 42 % of molted adult ticks at 126 days post-capillary tube feeding. In adult ticks, LVS initially colonized the gut, disseminated to hemolymph and salivary glands by 21 days, and persisted up to 165 days. LVS was detected in the salivary secretions of adult ticks after four days post intra-hemocoelic inoculation, and LVS recovered from salivary gland was infectious to mice with an infectious dose 50 % of 3 CFU. LVS in gravid female ticks colonized via the intra-hemocoelic route disseminated to the ovaries and then t

Innateness as genetic adaptation: Lorenz redivivus (and revised)

In 1965, Konrad Lorenz grounded the innate–acquired distinction in what he believed were the only two possible sources of information that can underlie adaptedness: phylogenetic and individual experience. Phylogenetic experience accumulates in the genome by the process of natural selection. Individual experience is acquired ontogenetically through interacting with the environment during the organism's lifetime. According to Lorenz, the adaptive information underlying innate traits is stored in the genome. Lorenz erred in arguing that genetic adaptation is the only means of accumulating information in phylogenetic (i.e., intergenerational) experience. Cultural adaptation also occurs over a phylogenetic time scale, and cultural tradition is a third source from which adaptive information can be extracted. This paper argues that genetic adaptation can be distinguished from individual and cultural adaptation in a species like Homo sapiens, in which even adaptations with a genetic component require cultural inputs and scaffolding to develop and be expressed. Examination of the way in which innateness is used in science suggests that scientists use the term, as Lorenz suggested, to designate genetic adaptations. The search for innate traits plays an essential role in generating hypotheses in ethology and psychology. In addition, designating a trait as innate establishes important facts that apply at the information-processing level of description