Browsing by Author "Laaksonen, Sauli"

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  • Suutari, Anniina; Hallikainen, Anja; Ruokojärvi, Päivi; Kiviranta, Hannu; Nieminen, Mauri; Laaksonen, Sauli (2012)
    Background: The aim of this study was to determine 17 Polychlorinated Dibenzo-p-dioxin and Dibenzofuran (PCDD/F) and 12 Dioxin-like Polychlorinated Biphenyl (DL-PCB) concentrations in the tissues of Finnish terrestrial herbivore species, semi-domesticated reindeer (Rangifer tarandus tarandus L.), and wild moose (Alces alces), investigate transfer and accumulation of PCDD/Fs and DL-PCBs in milk of the lactating reindeer hinds, and explore contaminant concentrations in stillborn reindeer calves exposed via placental transfer to PCDD/Fs and DL-PCBs. Methods: Reindeer and moose tissue sampling was focused in Finnish reindeer herding region. Reindeer milk samples were sampled in summer and autumn from reindeer hinds in experimental reindeer station in northern Finland. PCDD/Fs and DL-PCBs were analyzed using HRGC/HRMS method. The results are reported here as WHOTEQ upper bound concentrations and congener-specific lower bound concentrations. Results: WHO-PCDD/F- and PCB-TEQs in reindeer muscle and liver were generally higher in the calves than in adults. Concentrations in moose calves were lower than in reindeer calves, while in adult reindeer and moose the levels were equal. General PCDD/F congeners in reindeer muscle and liver were 23478-PeCDF, 123678-HxCDD and OCDD. In reindeer milk, the highest PCDD/F detected was OCDD, and it was common also in the moose muscle samples. A strong contribution of non-ortho-PCBs to WHO-TEQ was detected in all studied samples. The most dominating non-ortho-DL-PCB congener was PCB-126 in reindeer muscle, liver and milk. In moose muscle samples PCB-77 was the most abundant congener. Species-, individual- and tissue-specific accumulation of PCDD/Fs and DL-PCBs may be the result from varying extent and quality of exposure, and to some extent from different metabolic potential. Conclusions: PCDD/Fs showed partly similar profiles in reindeer and moose muscle, reindeer liver and milk samples - indicating equal mode of bioaccumulation. A strong contribution of non-ortho-PCBs to WHO-TEQ was detected, although there were some differences in frequency of particular congeners in these species. Due to the harmonized sampling method the study offers the way to determine and compare the levels of PCDD/Fs and DLPCBs in reindeer and moose tissues and examine the transfer and dynamics of dioxins and dioxin-like compounds in northern terrestrial food web.
  • Kynkäänniemi, Sanna-Mari; Kortet, Raine; Härkönen, Laura; Kaitala, Arja; Paakkonen, Tommi; Mustonen, Anne-Mari; Nieminen, Petteri; Härkönen, Sauli; Ylönen, Hannu; Laaksonen, Sauli (Finnish Zoological and Botanical Publishing Board, 2010)
    Range expansion of ectoparasites can cause parasites to attack new host species. In these cases it is important for the parasite to be able to adapt to the new environment and to reproduce on the host. For the host, it is crucial to hinder successfully the development of long-lasting parasitic relationship. The deer ked ( Lipoptena cervi) is a novel ectoparasite for northern cervids. We investigated of the deer ked can use the reindeer (Rangifer tarandus) as a host and, if it can, wether antiparsitic treatment against this parasite would be available. Three groups of reindeer were monitored: two groups of 6 reindeerr were infected with 300 flies per each individual; a control group comprised 6 animals. One of the infected groups was treated with subcutaneous ivermectin. At the end of the experiment the infextation rate of the infected animals was low. The reindeer in the non-treated group had both live and dead deer keds and also a single pupa while the ivermectin-treated reindeer had only dead deer keds. As some deer keds survided and reproduced, thedeer ked can potentially use the reindeer as a host but antiparasitic treatment may be effective agains this parasite.
  • Laaksonen, Sauli; Solismaa, Milla; Kortet, Raine; Kuusela, Jussi; Oksanen, Antti (BioMed Central, 2009)
    Background: Recent studies have revealed expansion by an array of Filarioid nematodes' into the northern boreal region of Finland. The vector-borne nematode, Setaria tundra, caused a serious disease outbreak in the Finnish reindeer population in 2003–05. The main aim of this study was to understand the outbreak dynamics and the rapid expansion of S. tundra in the sub arctic. We describe the vectors of S. tundra, and its development in vectors, for the first time. Finally we discuss the results in the context of the host-parasite ecology of S. tundra in Finland Results: Development of S. tundra to the infective stage occurs in mosquitoes, (genera Aedes and Anopheles). We consider Aedes spp. the most important vectors. The prevalence of S. tundra naturally infected mosquitoes from Finland varied from 0.5 to 2.5%. The rate of development in mosquitoes was temperature-dependent. Infective larvae were present approximately 14 days after a blood meal in mosquitoes maintained at room temperature (mean 21 C), but did not develop in mosquitoes maintained outside for 22 days at a mean temperature of 14.1 C. The third-stage (infective) larvae were elongated (mean length 1411 m (SD 207), and width 28 m (SD 2)). The anterior end was blunt, and bore two liplike structures, the posterior end slight tapering with a prominent terminal papilla. Infective larvae were distributed anteriorly in the insect's body, the highest abundance being 70 larvae in one mosquito. A questionnaire survey revealed that the peak activity of Culicidae in the reindeer herding areas of Finland was from the middle of June to the end of July and that warm summer weather was associated with reindeer flocking behaviour on mosquito-rich wetlands. Conclusion: In the present work, S. tundra vectors and larval development were identified and described for the first time. Aedes spp. mosquitoes likely serve as the most important and competent vectors for S. tundra in Finland. Warm summers apparently promote transmission and genesis of disease outbreaks by favouring the development of S. tundra in its mosquito vectors, by improving the development and longevity of mosquitoes, and finally by forcing the reindeer to flock on mosquito rich wetlands. Thus we predict that global climate change has the potential to promote the further emergence of Filarioid nematodes and the disease caused by them in subarctic regions.