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Gern, Lise

Nom
Gern, Lise
Affiliation principale
Fonction
Ancien.ne collaborateur.trice
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https://libra.unine.ch/handle/123456789/303

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  • Publication
    Métadonnées seulement
    An experimental study on the influence of tick infestations on nestling performance in great tits (Parus major)
    (2008)
    Gallizzi, Katharina
    ;
    Bischoff, Linda L
    ;
    Gern, Lise 
    ;
    Richner, Heinz
    Parasite defense is costly, and the detrimental effects of parasites, which call be measured in terms of parasite virulence, are thought to be influenced by the resources available to the host and, ultimately, by environmental conditions. Hence, if conditions are good, hosts call tolerate a certain number of parasites without suffering severe effects. In addition, the presence of other, parasites call influence the virulence of a focal parasite either positively or negatively. We tested whether an experimental tick infestation reduced nestling performance in Great Tits (Parus major) and whether the effect was altered by a maternal response induced by Hell Fleas (Ceratophyllus gallinae) that is known to protect nestlings against flea infestations (i.e., we tested whether one parasite call alter the virulence of another parasite across [lost generations). We induced the maternal effect by experimentally infesting half the birds' nests with fleas during egg laying. After hatching, nestlings were cross-fostered into broods that then contained both nestlings with and without the maternal effect. Half of these broods were infested with five tick larvae per nestling. This resulted in tick infestation levels similar to levels found in natural populations. The tick infestation did not affect nestling mass, tarsus length, or time until fledging. Thus, all effect of the flea-induced maternal effect on tick virulence was not detectable. From these results, we concluded that either tick larvae do not affect nestlings, or nestlings or their parents can compensate for the negative consequences of tick infestations in numbers similar to those that occur in nature. Received 18 October 2007 accepted 11 April 2008.
  • Publication
    Métadonnées seulement
    Detection and identification of Ehrlichia spp. in ticks collected in Tunisia and Morocco
    (2005)
    Sarih, M'Hammed
    ;
    M'Ghirbi, Youmna
    ;
    Bouattour, Ali
    ;
    Gern, Lise 
    ;
    Baranton, Guy
    ;
    Postic, Danièle
    A broad-range 16S rRNA gene PCR assay followed by partial sequencing of the 16S rRNA gene was used for the detection of members of the family Anaplasmataceae in ticks in North Africa. A total of 418 questing Ixodes ricinus ticks collected in Tunisia and Morocco, as well as 188 Rhipicephalus ticks from dogs and 52 Hyalomma ticks from bovines in Tunisia, were included in this study. Of 324 adult L ricinus ticks, 16.3% were positive for Ehrlichia spp., whereas only 3.4 and 2.8% of nymphs and larvae, respectively, were positive. A large heterogeneity was observed in the nucleotide sequences. Partial sequences identical to that of the agent of human granulocytic ehrlichiosis (HGE) were detected in L ricinus and Hyalomma detritum, whereas partial sequences identical to that of Anaplasma platys were detected in Rhipicephalus sanguineus. However, variants of Anaplasma, provisionally designated Anaplasma-like, were predominant in the L ricinus tick population in Maghreb. Otherwise, two variants of the genus Ehrlichia were detected in L ricinus and H. detritum. Surprisingly, a variant of Wolbachia pipientis was evidenced from L ricinus in Morocco. These results emphasized the potential risk of tick bites for human and animal populations in North Africa.
  • Publication
    Métadonnées seulement
    Coinoculation of Borrelia spp. with tick salivary gland lysate enhances spirochete load in mice and is tick species-specific
    (2002)
    Zeidner, Nordin S
    ;
    Schneider, Bradley S
    ;
    Nuncio, Maria S
    ;
    Gern, Lise 
    ;
    Piesman, Joseph
    C3H/HeN mice were inoculated with 10(6) spirochetes, either Borrelia burgdorferi strain N40 or the Portuguese strain of B. lusitaniae, PotiB2. Mice receiving spirochetes comoculated with salivary gland lysate (SGL) demonstrated significantly higher spirochete loads in target organs as measured by quantitative real-time polymerase chain reaction. This effect was tick dependent. in that Ixodes ricinus SGL specifically enhanced B. lusitaniae load, whereas I. scapidaris SGL specifically increased B. burgdorferi N40 load, but did not significantly affect the dissemination of B. lusitaniae. Protein profile analysis indicated at least 5 major protein differences between I. scapiularis and I. ricinus SGL, which can possibly account for this specific tick-spirochete interaction.
  • Publication
    Métadonnées seulement
    Expression of outer surface proteins A and C of Borrelia afzelii in Ixodes ricinus ticks and in the skin of mice
    (1998)
    Leuba-Garcia, S
    ;
    Martinez, R
    ;
    Gern, Lise 
    Several studies have described changes in the expression of proteins, especially of OspA and OspC, of B. burgdorferi sensu stricto during tick feeding. In this study, the expression of OspA and OspC of B. afzelii in unfed and feeding I. ricinus nymphs and in the subsequent adults was followed by means of the immunofluorescence test. Spirochaetes expressing OspA and OspC were observed in 70% and 80%, respectively of the unfed nymphs. In feeding and in fully engorged ticks, spirochaetes expressed OspC, while OspA disappeared 24 hours after the beginning of the blood meal. Spirochaetes expressing OspC in salivary glands were observed in one engorged tick. After molting, in unfed adults spirochaetes again expressed OspA and OspC but did so less frequently (6% and 13%, respectively). The mouse strain (AKR/N or BALB/C) on which ticks had their infectious blood meal influenced OspC expression in the following tick stage. In the skin of AKR/N mice, at the tick feeding site, B. afzelii expressed OspC only, as was shown by immunostaining.