| 11. |
- Strand, Tanja, 1978-
(författare)
-
European Black Grouse : MHC Genetic Diversity and Population Structure
- 2011
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Black grouse Tetrao tetrix is a bird species composed of large, continuous as well as severely reduced and fragmented populations, making it an optimal species to investigate how genetic diversity is affected by habitat fragmentation. I have focused on genetic diversity in the Major Histocompatibility Complex (MHC) to measure the ability of the black grouse to respond to environmental changes. I partly characterized MHC class II in black grouse and found striking similarities with chicken MHC class II. I demonstrated that black grouse possess a similar compact MHC as chicken with few MHC class II B (BLB) and Y (YLB) loci. I did not find evidence of balancing selection in YLB so I concentrated further studies on BLB. I developed a PCR-based screening method for amplifying and separating expressed BLB alleles in European black grouse populations. Small fragmented populations had lost neutral genetic diversity (based on microsatellites and SNPs) compared to samples from the historical distribution and contemporary large populations. There was also a trend, albeit less pronounced, for reduced MHC diversity in these populations. Neutral markers in small isolated populations were affected by increased levels of genetic drift and were therefore genetically differentiated compared to other populations. MHC markers on the other hand, were not subjected to genetic drift to the same extent probably due a long historic process of balancing selection. Inferences of heterozygosity and evolutionary patterns as well as detailed correlations to reproductive success and diseases cannot be performed until MHC can be amplified in a locus-specific manner. Therefore, I developed a single locus sequence-based typing method for independently amplifying MHC class II B loci (BLB1 and BLB2). I found that BLB1 and BLB2 were duplicated in a common ancestor to chickens and black grouse and that these loci are subjected to homogenizing concerted evolution due to inter-genetic exchange between loci after species divergence. I could also verify that both BLB1 and BLB2 were transcribed in black grouse and under balancing selection. This collection of work has significance for future conservation of black grouse as well as research and management of zoonotic diseases.
|
|
| 12. |
|
|
| 13. |
- Strand, Tanja, et al.
(författare)
-
Evolutionary history of black grouse major histocompatibility complex class IIB genes revealed through single locus sequence-based genotyping
- 2013
-
Ingår i: BMC Genetics. - : Springer Science and Business Media LLC. - 1471-2156. ; 14, s. 29-
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Gene duplications are frequently observed in the Major Histocompatibility Complex (MHC) of many species, and as a consequence loci belonging to the same MHC class are often too similar to tell apart. In birds, single locus genotyping of MHC genes has proven difficult due to concerted evolution homogenizing sequences at different loci. But studies on evolutionary history, mode of selection and heterozygosity correlations on the MHC cannot be performed before it is possible to analyse duplicated genes separately. In this study we investigate the architecture and evolution of the MHC class IIB genes in black grouse. We developed a sequence-based genotyping method for separate amplification of the two black grouse MHC class IIB genes BLB1 and BLB2. Based on this approach we are able to study differences in structure and selection between the two genes in black grouse and relate these results to the chicken MHC structure and organization. Results: Sequences were obtained from 12 individuals and separated into alleles using the software PHASE. We compared nucleotide diversity measures and employed selection tests for BLB1 and BLB2 to explore their modes of selection. Both BLB1 and BLB2 are transcribed and display classic characteristics of balancing selection as predicted for expressed MHC class IIB genes. We found evidence for both intra- and interlocus recombination or gene conversion, as well as indication for positive but differential selection at both loci. Moreover, the two loci appear to be linked. Phylogenetic analyses revealed orthology of the black grouse MHC class IIB genes to the respective BLB loci in chicken. Conclusions: The results indicate that the duplication of the BLB gene occurred before the species divergence into black grouse, chicken and pheasant. Further, we conclude that BLB1 and BLB2 in black grouse are subjected to homogenizing concerted evolution due to interlocus genetic exchange after species divergence. The loci are in linkage disequilibrium, which is in line with the theory of tightly coevolving genes within the MHC under the minimal essential MHC hypothesis. Our results support the conclusion that MHC form and function in birds derived from studies on the domesticated chicken are not artefacts of the domestication process.
|
|
| 14. |
- Strand, Tanja, 1978-, et al.
(författare)
-
Leptospira Status in Sweden during the Past Century, Neglected and Re-Emerging?
- 2023
-
Ingår i: Microorganisms. - : MDPI. - 2076-2607. ; 11:8
-
Forskningsöversikt (refereegranskat)abstract
- We compiled data on notified cases of leptospirosis in animals and humans in Sweden. Published studies on leptospirosis in humans and animals from the beginning of the 20th century onwards are summarized. During the Second World War, hundreds of leptospirosis cases in humans were reported in Sweden, but since then, there have been only a few severe cases. Surveillance of leptospirosis in domestic animals demonstrates that the pathogen is still occurring. The occurrence of Leptospira in humans and animals in the other Nordic countries resembles that in Sweden. Leptospirosis is an underdiagnosed and underreported disease globally, both in animals and humans, partly due to the lack of simple, rapid diagnostic tools but possibly also due to the lack of awareness among physicians, veterinarians and nurses. Traditionally, leptospirosis has been mostly diagnosed by serology, but development of molecular methodshas improved the capability for correct diagnosis. As of today, leptospirosis is regarded as a relatively uncommon disease in the Nordic countries, but in some other countries, it is considered a neglected zoonosis or a (re-)emerging disease that may become more common in the future. Possible factors that could contribute to an increase in incidence are discussed in this review. Active surveillance of humans and domestic and wild animals and stringent rodent control in society and animal farms are of outmost importance for prevention.
|
|
| 15. |
- Strand, Tanja M., 1978-, et al.
(författare)
-
Detection of Leptospira in Urban Swedish Rats : Pest Control Interventions as a Promising Source of Rats Used for Surveillance
- 2019
-
Ingår i: Vector Borne and Zoonotic Diseases. - : Mary Ann Liebert Inc. - 1530-3667 .- 1557-7759. ; 19:6, s. 414-420
-
Tidskriftsartikel (refereegranskat)abstract
- Rat carcasses obtained from pest control interventions can potentially be used for an efficient surveillance of zoonotic diseases such as leptospirosis. To evaluate the performance of different laboratory methods for detection of pathogenic Leptospira spp., heart and kidney samples from wild Norway rats were analyzed by microscopic agglutination test (MAT, the gold standard), a commercial IgG enzyme-linked immunosorbent assay, and by an optimized quantitative PCR (secY qPCR, followed by sequencing). We found secY qPCR to be as sensitive as MAT for screening of Leptospira infection in pest control rats and selected secY qPCR for a larger screening of rats from urban and rural areas in central and southern Sweden. We identified secY qPCR positive rats from the cities Stockholm, Gothenburg, and Malmö, which were further confirmed by sequencing.
|
|
| 16. |
- Strand, Tanja M., 1978-, et al.
(författare)
-
Genotyping of black grouse MHC class II B using Reference Strand-Mediated Conformational Analysis (RSCA)
- 2011
-
Ingår i: BMC Research Notes. - : Springer Science and Business Media LLC. - 1756-0500. ; 4:183
-
Tidskriftsartikel (refereegranskat)abstract
- Background The Major Histocompatibility Complex (MHC) is a cluster of genes involved in the vertebrate immune system and includes loci with an extraordinary number of alleles. Due to the complex evolution of MHC genes, alleles from different loci within the same MHC class can be very similar and therefore difficult to assign to separate loci. Consequently, single locus amplification of MHC genes is hard to carry out in species with recently duplicated genes in the same MHC class, and multiple MHC loci have to be genotyped simultaneously. Since amplified alleles have the same length, accurate genotyping is difficult. Reference Strand-Mediated Conformational Analysis (RSCA), which is increasingly used in studies of natural populations with multiple MHC genes, is a genotyping method capable to provide high resolution and accuracy in such cases. Findings We adapted the RSCA method to genotype multiple MHC class II B (BLB) genes in black grouse (Tetrao tetrix), a non-model galliform bird species, using a 96-Capillary Array Electrophoresis, the MegaBACE™ 1000 DNA Analysing System (GE Healthcare). In this study we used fluorescently labelled reference strands from both black grouse and hazel grouse and observed good agreement between RSCA and cloning/sequencing since 71 alleles were observed by cloning/sequencing and 76 alleles by RSCA among the 24 individuals included in the comparison. At the individual level however, there was a trend towards more alleles scored with RSCA (1-6 per individual) than cloning/sequencing (1-4 per individual). In 63% of the pair-wise comparison, the identical allele was scored in RSCA as in cloning/sequencing. Nine out of 24 individuals had the same number of alleles in RSCA as in cloning/sequencing. Our RSCA protocol allows a faster RSCA genotyping than presented in many other RSCA studies. Conclusions In this study, we have developed the RSCA typing method further to work on a 96-Capillary Array Electrophoresis (MegaBACE™ 1000). Our RSCA protocol can be applied to fast and reliable screening of MHC class II B diversity of black grouse populations. This will facilitate future large-scale population studies of black grouse and other galliformes species with multiple inseparable MHC loci.
|
|
| 17. |
- Strand, Tanja M, et al.
(författare)
-
Highly Pathogenic Leptospira Found in Urban Brown Rats (Rattus norvegicus) in the Largest Cities of Sweden
- 2015
-
Ingår i: Vector-Borne and Zoonotic Diseases. - : Mary Ann Liebert Inc. - 1530-3667 .- 1557-7759. ; 15:12, s. 779-781
-
Tidskriftsartikel (refereegranskat)abstract
- Leptospirosis is an emerging zoonosis of global concern; however, its contemporary occurrence in Sweden, a European country partly located north of the Arctic Circle, is poorly known. Four out of 30 brown rats, captured within urban districts in Sweden, were found to be positive for antibodies to Leptospira interrogans serovar Icterohaemorrhagiae. This serovar causes Weil's disease in humans, a severe infection with jaundice, renal failure, and hemorrhage. Our study is the first finding of this highly pathogenic serovar in Swedish rats since the 1930s.
|
|
| 18. |
- Strand, Tanja, et al.
(författare)
-
The MHC class II of the Black grouse (Tetrao tetrix) consists of low numbers of B and Y genes with variable diversity and expression
- 2007
-
Ingår i: Immunogenetics. - : Springer Science and Business Media LLC. - 0093-7711 .- 1432-1211. ; 59:9, s. 725-734
-
Tidskriftsartikel (refereegranskat)abstract
- We found that the Black grouse (Tetrao tetrix) possess low numbers of Mhc class II B (BLB) and Y (YLB) genes with variable diversity and expression. We have therefore shown, for the first time, that another bird species (in this case, a wild lek-breeding galliform) shares several features of the simple Mhc of the domestic chicken (Gallus gallus). The Black grouse BLB genes showed the same level of polymorphism that has been reported in chicken, and we also found indications of balancing selection in the peptide-binding regions. The YLB genes were less variable than the BLB genes, also in accordance with earlier studies in chicken, although their functional significance still remains obscure. We hypothesize that the YLB genes could have been under purifying selection, just as the mammal Mhc-E gene cluster.
|
|
| 19. |
- Tydén, Tanja, 1949-, et al.
(författare)
-
Effects of specially tailored information on Swedish university students' sexual behavior.
- 1994
-
Ingår i: Journal of American College Health. - : Informa UK Limited. - 0744-8481 .- 1940-3208. ; 43:2, s. 75-9
-
Tidskriftsartikel (refereegranskat)abstract
- In independent surveys concerning sexual behavior among university students in Uppsala, Sweden, in 1989 and 1990, we found that condoms were infrequently used and that up to 25% of the sexually experienced students had a history of having had at least one sexually transmitted disease (STD). We targeted an information campaign toward the same students (approximately 20,000) in 1990. Our aims were (1) to increase the knowledge of STDs and alert the students to the high frequency of STDs in the student population, (2) to encourage students to have an STD checkup at the local STD clinic, and (3) to induce a positive attitude toward condoms. We evaluated the effects of the campaign, using before and after classroom surveys, a separate survey of students who attended the STD clinic, and a focus group analysis. Although the information campaign was successful, in that students became more aware of STDs and showed increased knowledge about the high frequency of STDs in their own population, fewer than 1% of the target population went for an STD checkup at the local STD clinic. Overall, the campaign was well received by the students but failed to induce any measurable changes in attitudes during the short observation period.
|
|
| 20. |
- Tydén, Tanja, 1949-, et al.
(författare)
-
Evaluation of an STD-prevention program for Swedish university students.
- 1998
-
Ingår i: Journal of American College Health. - : Informa UK Limited. - 0744-8481 .- 1940-3208. ; 47:2, s. 70-5
-
Tidskriftsartikel (refereegranskat)abstract
- The authors evaluated a sexually transmitted disease (STD)-prevention program that combined a mass media campaign with peer education. The program was designed to increase Swedish university students' knowledge about STDs, improve attitudes toward condom use, and tell students where to get an STD checkup. Preintervention and postintervention postal questionnaires wer used with an intervention group and two types of control groups. Responses ranged from 32% to 67% for the randomly selected students and from 93% to 99% for classroom and clinic participants. The intervention was noticed by a majority of the students (85-98%) and discussed by 43% to 57%; more women than men observed and discussed the campaign. Knowledge about STDs, where to turn for STD checkups, and the intention of having an STD checkup increased. Attitudes toward condom use were equally positive before and after the intervention. Although it was successful in attracting attention and leading to discussion of STD prevention, the campaign did not encourage students to have an STD checkup.
|
|
