Biomedical subjects

Juha Laakkonen

Publications and source records attributed to Juha Laakkonen.

5 recordsLinked to original sources

PubMed2006

Morphological and molecular characterisation of Paranoplocephala buryatiensis n. sp. and P. longivaginata Chechulin & Gulyaev, 1998 (Cestoda: Anoplocephalidae) in voles of the genus Clethrionomys.

A new species, Paranoplocephala buryatiensis n. sp. (Cestoda:Anoplocephalidae), is described from the grey-sided vole Clethrionomys rufocanus (Sundevall) in the Republic of Buryatia (Russian Federation) and compared with P. longivaginata Chechulin & Gulyaev, 1998, a parasite of the red vole C. rutilus (Pallas) in the same region. P. buryatiensis n. sp. and P. longivaginata both have an exceptionally long vagina and cirrus, unique features among known species of Paranoplocephala Lühe, 1910. The new species differs from P. longivaginata primarily by its wider and more robust body, lower length/width ratio of mature proglottides, tendency of testes to occur in two separate groups, seminal receptacle of a different shape and the position of the cirrus-sac with respect to the ventral longitudinal osmoregulatory canal. The cytochrome oxidase subunit I (COI) sequence data support the independent status of these species, and show that they form a monophyletic assemblage within Paranoplocephala (sensu lato). Assuming cospeciation, an indirect calibration using host speciation dates estimated a rate of mtDNA substitution of 1.0-1.7% pairwise (0.5-0.85% per lineage) sequence divergence per million years. A faunistic review of Paranoplocephala species in C. rufocanus and C. rutilus in the Holarctic region is presented.

Animals↗

PubMed2006

Genetic analysis of Thailand hantavirus in Bandicota indica trapped in Thailand.

Sixty one tissue samples from several rodent species trapped in five provinces of Thailand were examined for the presence of hantaviral markers by enzyme-immunoassay and immunoblotting. Four samples, all from the great bandicoot rat Bandicota indica, were confirmed positive for the hantaviral N-antigen. Two of them were trapped in Nakhon Pathom province, the other two in Nakhon Ratchasima province, approximately 250 km from the other trapping site. When analysed by RT-nested PCR, all four rodents were found positive for the hantaviral S- and M-segment nucleotide sequences. Genetic analysis revealed that the four newly described wild-type strains belong to Thailand hantavirus. On the phylogenetic trees they formed a well-supported cluster within the group of Murinae-associated hantaviruses and shared a recent common ancestor with Seoul virus.

Animals↗

PubMed2006

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Journal Article↗

PubMed2005

Significant morphological but little molecular differences between Trypanosoma of rodents from Alaska.

We examined blood smears of 173 rodents and 33 shrews captured at 4 sites in the Gates of the Arctic National Park, northern Alaska, in summer 2002. Trypanosoma spp. were detected in the plasma of 5 Microtus oeconomus, 4 Microtus miurus, and 1 Lemmus trimucronatus. The trypomastigote morphology from different individuals of M. oeconomus caught at the same site and of M. miurus from different sites varied significantly. The 4 DNA sequences obtained from the blood smear positive samples contained 2 different haplotypes very similar to each other and to that of Trypanosoma microti. Of possible vectors of blood parasites, the flea Amalaraeus dissimilis was collected from M. miurus.

Alaska↗

PubMed2003

Microparasite assemblages of conspecific shrew populations in southern California.

The microparasite component communities of 2 species of shrews, Notiosorex crawfordi and Sorex ornatus, were investigated for the first time in 2 isolated and 3 continuous landscapes in southern California. With microscopical examination, a total of 6 parasite species was found in N. crawfordi and 8 species in S. ornatus. The highest number (5) of parasite species was detected in the lungs. The corrected estimate of parasite species richness did not significantly correlate with the host abundance in either shrew species. Altitude, and also latitude in N. crawfordi, appeared to be significantly positively associated with the parasite species richness, but this could be due to a false association because of the rare occurrence of some of the parasites or the small altitude range (or both). No other landscape variable analyzed (location, size of the study site, disturbance) was significantly associated with the parasite species richness of the shrews. The parasite assemblages of the 2 shrew species were similar despite the fact that N. crawfordi has a lower metabolic rate than S. ornatus.

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