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Babesia spp. are tick-borne protozoan parasites that have been reported in many European countries and are considered to be emerging pathogens. Several Babesia spp. have been identified in ticks in Latvia. Recently, canine babesiosis cases were diagnosed for the first time in Latvia; therefore, continued studies on the prevalence and occurrence of new species are warranted. In the present study, questing tick samples collected in 2005-2007 were screened for the presence of Babesia spp.; in total, 432 Ixodes ricinus and 693 Ixodes persulcatus ticks were analyzed. Babesia spp. were detected in 1.4% of the I. ricinus ticks and in 1.9% of I. persulcatus ticks. Sequencing revealed that ixodid ticks in Latvia contained Babesia microti, Babesia capreoli, and Babesia venatorum. Babesia microti was the most prevalent species, accounting for 58% of all positive samples; moreover, two distinct B. microti genotypes were identified. Phylogenetic analysis of the full-length 18S rRNA gene of two B. capreoli/B. divergens isolates indicated a closer relationship to the B. capreoli clade than B. divergens. This is the first report of B. venatorum in I. persulcatus ticks in Latvia. Our results suggest that both I. ricinus and I. persulcatus ticks play important roles in the epidemiology of these zoonotic pathogens in Latvia.

Variations of the nonrecombining Y-chromosomal region were investigated in 159 unrelated Baltic-speaking ethnic Latvians from four different geographic regions, using 28 biallelic markers and 12 short tandem repeats. Eleven different haplogroups (hgs) were detected in a regionally homogeneous Latvian population, among which N1c, R1a, and I1 cover more than 85% of its paternal lineages. When compared its closest geographic neighbors, the composition of the Latvian Y-chromosomal gene pool was found to be very similar to those of Lithuanians and Estonians. Despite the comparable frequency distribution of hg N1c in Latvians and Lithuanians with the Finno-Ugric-speaking populations from the Eastern coast of the Baltic Sea, the observed differences in allelic variances of N1c haplotypes between these two groups are in concordance with the previously stated hypothesis of different dispersal ways of this lineage in the region. More than a third of Latvian paternal lineages belong specifically to a recently defined R1a-M558 hg, indicating an influence from a common source within Eastern Slavic populations on the formation of the present-day Latvian Y-chromosome gene pool.

The shortening of telomeres with ageing is a well-documented observation; however, the reported number of nucleotides in telomeres varies between different laboratories and studies. Such variability is likely caused by ethnic differences between the populations studied. Until now, there were no studies that investigated the variability of telomere length in a senescent Latvian population of the most common mitochondrial haplogroups, defined as H (45%), U (25%), Y chromosomal N1c (40%) and R1a1 (40%). Telomere length was determined in 121 individuals in different age groups, including a control group containing individuals of 20-40 years old and groups of individuals between 60-70 years old, 71-80 years old, 81-90 years old, and above 90 years old. Telomere length was determined using the Southern blot telomeric restriction fragment assay (TRF). Decreased telomere length with ageing was confirmed, but a comparison of centenarians and individuals between 60-90 years of age did not demonstrate a significant difference in telomere length. However, significant variability in telomere length was observed in the control group, indicating probable rapid telomere shortening in some individuals that could lead up to development of health status decline appearing with ageing. Telomere length measured in mononuclear blood cells (MNC) was compared with the telomere length measured in whole peripheral white blood cells (WBC) using TRF. Telomere length in MNC was longer than in WBC for the control group with individuals 20 to 40 years old; in contrast, for the group of individuals aged 65 to 85 years old, measured telomere length was shorter in MNC when compared to WBC.

Anaplasma phagocytophilum has been detected in ticks in Latvia; however, this is the first study to investigate this pathogen in dogs in Latvia. The aims of this study were: (i) to determine A. phagocytophilum seroprevalence in dogs, (ii) to correlate A. phagocytophilum seroprevalence in dogs with the geographic distribution of the tick species Ixodes ricinus and Ixodes persulcatus, and (iii) to determine if seroprevalence for A. phagocytophilum is higher in dogs with clinical signs suggestive of canine granulocytic anaplasmosis (CGA). Peripheral venous blood samples were collected from 3 dog groups: (i) clinically healthy dogs (HD, n=400), (ii) clinically healthy hunting dogs (HHD, n=41), and (iii) dogs with a clinical suspicion of anaplasmosis (SD, n=29). Sampling was carried out in regions inhabited by I. ricinus (IR), I. persulcatus (IP), and in regions where both tick species were present (M). SNAP 4Dx test (IDEXX) was used to detect antibodies against A. phagocytophilum in the blood of all dogs; nested PCR was performed in selected dogs of the SD group. Seroprevalence for A. phagocytophilum was calculated and correlated with the prevalent tick species in the region. A. phagocytophilum seroprevalence was 11.0% in HD, 12% in HHD, and 17% in SD with no significant differences among groups. In the IR region, seroprevalence was 12.5% (34/272) while seroprevalence in the M region was 17% (13/76), and both were significantly higher than the seroprevalence of 2% in the IP region (2/93; p

Human Y chromosome is used as a tool in male infertility and population genetic studies. The aims of this research were to analyse the prevalence of Y chromosome microdeletions among infertile Latvian men, and to identify possible lineages of Y chromosome that may be at increased risk of developing infertility. A study encompassed 105 infertile men with different spermatogenic disturbances. Deletions on Y chromosome were detected in 5 out of 105 (∼5%) cases analysed in this study. Three of them carried deletion in AZFc region and two individuals had AZFa+b+c deletion. Study of Y chromosome haplogroups showed that N3a1 and R1a1 lineages were found less frequently in the infertile male group compared to ethnic Latvian group, however K* cluster was predominantly found in infertile male Y chromosomes. Conclusions: (1) Our study advocates running Y chromosome microdeletion analyses only in cases of severe form of infertility; (2) Ychromosome haplogroup analysis showed statistically significant tendencies that some haplogroups are more common in ethnic male group, but others are more common in infertile males.

We report the results of a study of the prevalences of three clinically relevant Borrelia burgdorferi sensu lato genospecies ( Borrelia burgdorferi sensu stricto, Borrelia afzelii , and Borrelia garinii ) in 1,040 questing Ixodes ticks from all regions of Latvia, where Lyme borreliosis is endemic. The prevalences of Borrelia in Ixodes ricinus and Ixodes persulcatus were 22.6 and 27.9%, respectively. Molecular typing of B. burgdorferi from infected ticks was performed by restriction fragment length polymorphism (RFLP) analysis of PCR-amplified fragments of the 16S-23S ( rrs-rrlA ) rRNA intergenic spacer by using species-specific primers and subsequent sequencing. The dominant Borrelia species in both Ixodes species was B. afzelii. In addition, different restriction patterns of B. garinii and B. afzelii were also identified. This study demonstrates that the 16S-23S rRNA PCR-RFLP typing method is simple, sensitive, and fast and that it allows one to differentiate among B. burgdorferi species and subspecies with various degrees of pathogenic potential directly in ticks. These features are important in monitoring Lyme disease.

To characterize the genetic basis of drug resistance in Mycobacterium tuberculosis in Latvia, mutations involved in rifampin ( rpoB gene) and isoniazid ( katG gene) resistance in DNA from 19 drug-susceptible and 51 multidrug-resistant M. tuberculosis complex isolates were analyzed. The most frequent rpoB gene mutations found by the Line Probe assay were the S531L (14 of 34 isolates), D516V (7 of 34), H526D (4 of 34), and D516Y plus P535S (4 of 34) mutations. Direct sequencing of seven isolates with unclear results from Line Probe assay showed the presence of the L533P mutation and the Q510H plus H526Y (1 of 34) and D516V plus P535S (4 of 34) double mutations, neither of which has been described previously. Single-strand conformation polymorphism analysis showed strand mobility differences between the rifampin-susceptible and -resistant samples for the D516V, H526D, and D516Y plus P535S mutations but not for the S531L mutation. Nucleotide substitution at codon 315 (AGC→ACC) of the katG gene was found in 48 of 51 multidrug-resistant samples by sequencing. Furthermore, katG gene restriction fragment length polymorphism analysis with endonuclease Aci I confirmed the nucleotide change in codon 315.

Variations of the nonrecombining Y-chromosomal region were investigated in 159 unrelated Baltic-speaking ethnic Latvians from four different geographic regions, using 28 biallelic markers and 12 short tandem repeats. Eleven different haplogroups (hgs) were detected in a regionally homogeneous Latvian population, among which N1c, R1a, and I1 cover more than 85% of its paternal lineages. When compared its closest geographic neighbors, the composition of the Latvian Y-chromosomal gene pool was found to be very similar to those of Lithuanians and Estonians. Despite the comparable frequency distribution of hg N1c in Latvians and Lithuanians with the Finno-Ugric-speaking populations from the Eastern coast of the Baltic Sea, the observed differences in allelic variances of N1c haplotypes between these two groups are in concordance with the previously stated hypothesis of different dispersal ways of this lineage in the region. More than a third of Latvian paternal lineages belong specifically to a recently defined R1a-M558 hg, indicating an influence from a common source within Eastern Slavic populations on the formation of the present-day Latvian Y-chromosome gene pool.

Mutations causing resistance to aminoglycosides, such as kanamycin (KAN), amikacin (AMK), and streptomycin, are not completely understood. In this study, polymorphisms of aminoglycoside resistance influencing genes such as rrs, eis, rpsL, and gidB in 41 drug-resistant and 17 pan-sensitive Mycobacterium tuberculosis clinical isolates in Latvia were analyzed. Mutation A1400G in rrs gene was detected in 92% isolates with high resistance level to KAN and diverse MIC level to AMK. Mutations in promoter region of eis were detected in 80% isolates with low-level MIC of KAN. The association of K43R mutation in rpsL gene, a mutation in the rrs gene at position 513, and various polymorphisms in gidB gene with distinct genetic lineages of M. tuberculosis was observed. The results of this study suggest that association of different controversial mutations of M. tuberculosis genes to the drug resistance phenotype should be done in respect to genetic lineages.

Migratory birds act as hosts and long-distance vectors for several tick-borne infectious agents. Here, feeding Ixodes ticks were collected from migratory birds during the autumn migration period in Latvia and screened for the presence of epidemiologically important non-viral pathogens. A total of 93 DNA samples of ticks (37 larvae and 56 nymphs) removed from 41 birds (order Passeriformes, 9 species) was tested for Lyme borreliosis spirochaetes, Anaplasma phagocytophilum, Rickettsia spp., and Babesia spp. Borrelia burgdorferi DNA was detected in 18% of the tick samples, and a majority of infected ticks were from thrush (Turdus spp.) birds. Among the infected ticks, Borrelia valaisiana was detected in 41% of cases, Borrelia garinii in 35%, and mixed Bo. valaisiana and Bo. garinii infection in 24%. Anaplasma phagocytophilum DNA was detected in 2% of ticks, R. helvetica in 12%, and Babesia spp. pathogens in 4% of ticks. Among these samples, 3 Babesia species were identified: Ba. divergens, Ba. microti, and Ba. venatorum. Coinfection with different pathogens that included mixed infections with different Borrelia genospecies was found in 20% of nymphal and 3% of larval Ixodes ticks. These results suggest that migratory birds may support the circulation and spread of medically significant zoonoses in Europe.

Borrelia burgdorferi, which is the causative agent of Lyme disease, is transmitted from infected Ixodes ticks to a mammalian host following a tick bite. Upon changing the host organism from an Ixodes tick to a warm-blooded mammal, the spirochete must adapt to very different conditions, which is achieved by altering the expression of several genes in response to a changing environment. Recently, considerable attention has been devoted to several outer surface proteins, including BBA73, that undergo dramatic upregulation during the transmission of B. burgdorferi from infected Ixodes ticks to mammals and that are thought to be important for the establishment and maintenance of the infection. These upregulated proteins could reveal the mechanism of pathogenesis and potentially serve as novel drug targets to prevent the transmission of the pathogenic bacteria. To promote effective treatments for Lyme disease and to gain better insight into B. burgdorferi pathogenesis, we have determined the crystal structure of the upregulated outer surface protein BBA73 at 2.0 A resolution. We observed that the BBA73 protein exists as a homodimer both in the crystal and in solution. The monomers interact with their N-terminal α-helices and form a cleft that could potentially serve as a ligand or receptor binding site. To confirm that the protein dimerizes through the interaction of the N-terminal regions, we produced an N-terminal deletion mutant of BBA73 to disrupt dimerization, and we determined the crystal structure of the truncated BBA73 protein at 1.9 A resolution. The truncated protein did not form a homodimer, and the crystal structure confirmed that the overall fold is identical to that of the native BBA73 protein. Notably, a paralogous protein CspA from B. burgdorferi with known crystal structure also forms a homodimer, albeit through an entirely different interaction between the monomers.

This is the first report of confirmed canine babesiosis in Latvia supporting the observed geographical expansion of this disease. Between 2009 and 2011 three dogs which have not traveled outside of Latvia were diagnosed with babesiosis. Hematological analysis and serological tests for granulocytic anaplasmosis, ehrlichiosis and borreliosis were negative (Idexx SNAP 4Dx test). Peripheral blood erythrocytes of the three dogs contained large Babesia that were identified as Babesia canis canis by PCR. Sequences of partial 18S rRNA gene were 98–100% similar to the sequences of B. canis canis isolated from dogs in other European countries. We conclude that these are the first autochthonous canine babesiosis cases reported from Latvia.

Lyme disease is a tick-borne infection caused by the transmission of Borrelia burgdorferi from infected Ixodes ticks to a mammalian host during the blood meal. Previous studies have shown that the expression of B. burgdorferi surface-localized lipoproteins, which include BBA64, is up-regulated during the process of tick feeding. Although the exact function of BBA64 is not known, this lipoprotein is critical for the transmission of the spirochete from the tick salivary glands to the mammalian organism after a tick bite. Since the mechanism of development of the disease and the functions of the surface lipoproteins associated with borrel­iosis are still poorly understood, the crystal structure of the B. burgdorferi outer surface lipoprotein BBA64 was solved at 2.4 A resolution in order to obtain a better insight into the pathogenesis of B. burgdorferi and to promote the discovery of novel potential preventive drugs against Lyme disease. In this study, the crystal structure of BBA64 was also compared with that of the paralogous protein CspA (also referred to as BbCRASP-1, CRASP-1 or BBA68). CspA is the complement regulator-acquiring surface protein-1 of B. burgdorferi; its structure is known, but its function apparently differs from that of BBA64. It is demonstrated that unlike the homologous CspA, BBA64 does not form a homodimer. Their differences in function could be explained by divergence in their amino-acid sequences, electrostatic surface potentials and overall tertiary structures. The C-terminal part of BBA64 has a different conformation to that of CspA; the conformation of this region is essential for the proper function of CspA.

Virus-like particles (VLPs) are created by the self-assembly of multiple copies of envelope and/or capsid proteins from many viruses, mimicking the conformation of a native virus. Such noninfectious nanostructures are mainly used as antigen-presenting platforms, especially in vaccine research; however, some of them recently were used as scaffolds in biotechnology to produce targeted nanoparticles for intracellular delivery. This study demonstrates the creation of fusion VLPs using hepatitis B core protein-based system maintaining a fibronectin-binding property from B. burgdorferi BBK32 protein, including the evidence of particles’ transmission to BHK-21 target cells via caveolae/rafts endocythosis. These results make this construct to be an attractive model in development of HBc-based nanoparticles for cellular targeting applications and highlights the fragment of B. burgdorferi BBK32 as a novel cellular uptake-promoting peptide., This work was supported by grant of Latvian Council of Science, Nr. 10.0029.3 and by ESF Project

International audience; Various studies have demonstrated that mitochondrial DNA (mtDNA) heteroplasmy tends to increase with age and that the observed frequency of heteroplasmy among populations mostly depends on the way it is measured. Therefore, we investigated age-related association on the presence of mtDNA heteroplasmy within the hypervariable segment 1 (HVS-I) in a selected study group. The study group consisted of 300 maternally unrelated Latvians ranging in age from 18 to over 90years. To determine the optimal method for mtDNA heteroplasmy detection, three approaches were used: (i) SURVEYORTM Mutation Detection Kit, (ii) sequencing and (iii) denaturing gradient-gel electrophoresis (DGGE). Among the studied individuals, 30.3% were found to be heteroplasmic. The distribution of heteroplasmy statistically significantly increased with individuals' age (17%; 95% confidence interval [CI] 0.095-0.244 in the 18-40year age group vs. 39%; [CI] 0.294-0.487 in the>90year age group). Heteroplasmy occurred in a total of 21 different positions within HVS-I, and was the most frequent at fast-mutated positions 16189, 16304 and 16311. The results indicate that heteroplasmy in HVS-I is relatively common and occurs in a broad spectrum of sites. The above is supported by evidence to eventual increase of the probability of heteroplasmy with age due to specific mitochondrial haplogroup background.

Latvia has one of the highest prevalence of isolated cleft lip with or without cleft palate (CL/P) in Europe. To clarify the genetic origins of the Latvian cleft population and establish a method for genetic mapping, mitochondrial DNA variation was studied in a population affected with clefting. One-hundred and seven subjects and 351 samples from unrelated healthy volunteers representing four anthropologically, archaeologically and ethno-linguistically different regions of Latvia were selected. The case group showed a higher frequency of haplogroups U4 (p=0.02) and U5 (p=0.0003) than in non-U haplogroups. We hypothesize that U4 and U5 mtDNA haplotype carriers may also carry susceptibility genes for clefts. Future studies will take into consideration these definitions based on mtDNA haplotypes when analyzing genetic variations and their possible contribution to CL/P susceptibility.

During the period of 1993-2002 an increase and the remarkable changes in the incidence of tick-borne encephalitis (TBE) and Lyme borreliosis (LB) as well as annual activities of vector species were noticed. The highest increase of TBE morbidity in Latvia has been observed in 1994 and 1995, and less expressed also in 1998 which was followed by a significant decrease during subsequent years. Whereas the highest peak of LB morbidity has been noticed in 1998 with only a minor decrease during subsequent years. Two epidemiologically significant Ixodes tick species are common in Latvia. Ixodes ricinus L. spread in the western and central part of Latvia; but rarely and in small numbers also in the eastern part. Ixodes persulcatus P. Sch. seems to dominate only in the eastern part of the country. The changes of seasonal and annual activities of I. ricinus were observed in two types of monitoring sites--sylvatic and peridomestic, located in the central part of Latvia. Observations of I. persulcatus were made in the eastern districts. Comparing geographically the Tick-borne diseases (TBD) incidence data for three tick distribution regions (I. ricinus dominated, I. persulcatus dominated and mixed regions), it was observed that the trend of annual changes in LB incidence during the last decade is almost of the same kind for all regions. Whereas TBE incidence extremes in 1994 and 1995 were observed almost only in I. ricinus dominated region. The annual field-collected adult tick infection rate with TBE virus (TBEV) from 1993 to 2002 for I. ricinus adults varied between 1.7% and 26.6% and for I. persulcatus--between 0% and 37.3%. The infection level in ticks removed from humans was much higher and from 1998 to 2002 surpassed 30%. TBEV investigations of removed adults and nymphs in 2002 discovered a high TBEV prevalence also in I. ricinus nymphs (43%). Typing of TBE virus isolated from ticks and patient serum samples in collaboration with German and Swedish virologists revealed that all three TBEV subtypes were co-circulating in Latvia. The mean annual tick infection rate with Borrelia burgdorferi s.l. analysed by means of a nested polymerase chain reaction of OspA gene fragment during the period of 1999-2001 was 18%-38% for I. ricinus adults and 25%-51% for I. persulcatus adults. Typing of Borrelia-positive DNA samples indicated that B. afzelii was dominant in Borrelia-positive I. ricinus (64.9%) and I. persulcatus (81.2%) followed by B. garinii (I. ricinus: 24.3%; in I. persulcatus: 14.5%). Investigations of Ehrlichia phagocytophila genogroup (by nested PCR targeted the 16S rRNA gene) revealed the presence of Ehrlichia sp. in I. ricinus from the central part of Latvia. Obtained data on TBD vectors and the epidemiological situation during the last decade indicates the complex impact of different factors influencing TBE and LB morbidity in Latvia.

In order to characterise molecular mechanisms of first-line drug resistance in Mycobacterium tuberculosis and to evaluate the use of molecular markers of resistance (gene point mutations), we analysed 66 multi-drug-resistant (MDR) isolates from Latvian tuberculosis patients. They were all resistant to rifampin (RIF), isoniazid (INH) and streptomycin (SM), and 33 were resistant to ethambutol (EMB). Enzymatic digestion by MboII and nucleotide sequencing of the rpsL gene fragment detected a single nucleotide substitution K43R in 40 (61%) of the 66 SM-resistant M. tuberculosis isolates. Of the other 26 SM-resistant isolates, 16 (24%) had mutations at positions 513A--C and 516C--T of the rrs gene and 10 (15%) had the wild-type sequence. The single-stranded DNA conformation polymorphism (SSCP) method was used to detect mutations in the embB gene associated with EMB resistance. Substitutions in the embB gene were found by SSCP analysis in 15 (45%) and by sequencing in 17 (52%) of the 33 EMB-resistant isolates. Surprisingly, SSCP revealed a nucleotide mutation at codon M306 in five (15%) of 33 in vitro EMB-susceptible MDR isolates.

Baumanis, V., I. Jansone, A. Skangals, I. Mandrika and V. Berzins. Synthesis of recombinant atrial natriuretic peptide (rANP) using hybrid fusion protein-phage fr coat/ANP (CP/ANP). Peptides 18(8) 1229–1235, 1997.—Recombinant atrial natriuretic peptide (rANP) was expressed in and isolated from E. coli. rANP was purified using HPLC. Amino acid analysis, partial sequencing, and molecular mass were determined. Fused protein was used to rise polyclonal antibodies and to develop of immunoenzymatic assays of rANP and CP/ANP. Experiments were designed to study rANP effects on isolated rabbit aortic strips and to examine hypotensive, diuretic, and natriuretic activity, as well as renal creatinine clearance, in an in vivo rat model. Identity of recombinant and commercial ANP has been confirmed. Physiological activity of CP/ANP has allowed the investigators to predict the conformation of CP/ANP, pro-ANP processing, and the method by which fusion protein interacts with ANP receptors.

Pyrazinamide (PZA) is an effective antituberculous agent ([1][1]) that becomes active when bacterial pyrazinamidase converts it to pyrazinoic acid, which is toxic to mycobacteria ([4][2]). In Mycobacerium tuberculosis , PZA resistance is associated with the loss of pyrazinamidase activity, mainly

The Escherichia coli RNA phage Q beta coat protein-encoding gene (C) was amplified from native Q beta RNA using a reverse transcription-PCR technique. Gene C contains sequences coding for both the 133-amino acid (aa) Q beta coat protein (CP) and the 329-aa read-through protein (A1) consisting of CP and an additional 196-aa C-terminal sequence, separated from CP within the C gene by an opal (UGA) stop codon. Primers ensuring the natural environment for gene C, especially within the ribosome-binding site, and supplying C with unique restriction sites at both ends have been prepared. An amplified 1062-bp PCR fragment was positioned under the control of the strong E. coli trp promoter (Ptrp) within a pGEM-derived plasmid. The synthesis of gene C products was confirmed electrophoretically and immunologically. An immunodiffusion test with anti-Q beta phage antibodies and electron microscopy evaluation of the purified recombinant products showed that when expressed, the Q beta C gene was responsible for high-level synthesis and correct self-assembly of Q beta CP monomers into capsids indistinguishable morphologically and immunologically from Q beta phage particles, which we plan to use as surface display vectors.

A synthetic DNA sequence coding for the 28 amino acid residues of alpha-human atrial natriuretic factor (alpha-hANF) and the N-terminal linker tripeptide Ile-Asp-Lys was inserted in the 3'-terminal part of the RNA bacteriophage fr coat protein gene. The cloned hybrid gene was isolated and placed into an expression vector under the control of the inducible E. coli tryptophan promoter and phage fr coat protein translation initiation region (TIR) sequence. In an appropriate host strain the expressed fusion protein accounts for at least 10% of the total cellular protein. In order to achieve high-cell density in a bioreactor while maintaining efficiency of alpha-hANF expression, improved cultivation conditions were selected using modified Shielach-Bauer's culture media containing glucose, yeast extract and bacto tryptone at an initial concentration of 2 g l-1 of each, adding concentrate of medium throughout the microbial growth and maintaining the dissolved oxygen in a range of 25-30%. At 13-14 h cultivation, the cell density reached 40 g cell dry weight per liter and the yield of fusion protein exceeded 45 mg g-1 cell dry weight. Fusion protein from solubilized E. coli cells was purified to homogeneity by ion exchange chromatography on DEAE-, CM-cellulose, QAE Sephadex A25 columns and selective precipitation.

Summary Mitochondrial DNA (mtDNA) variation was investigated in a sample of 299 Latvians, a Baltic-speaking population from Eastern Europe. Sequencing of the first hypervariable segment (HVS-I) in combination with analysis of informative coding region markers revealed that the vast majority of observed mtDNAs belong to haplogroups (hgs) common to most European populations. Analysis of the spatial distribution of mtDNA haplotypes found in Latvians, as well as in Baltic-speaking populations in general, revealed that they share haplotypes with all neighbouring populations irrespective of their linguistic affiliation. Hence, the results of our mtDNA analysis show that the previously described sharp difference between the Y-chromosomal hg N3 distribution in the paternally inherited gene pool of Baltic-speaking populations and of other European Indo-European speakers does not have a corresponding maternal counterpart.

The Saami are regarded as extreme genetic outliers among European populations. In this study, a high-resolution phylogenetic analysis of Saami genetic heritage was undertaken in a comprehensive context, through use of maternally inherited mitochondrial DNA (mtDNA) and paternally inherited Y-chromosomal variation. DNA variants present in the Saami were compared with those found in Europe and Siberia, through use of both new and previously published data from 445 Saami and 17, 096 western Eurasian and Siberian mtDNA samples, as well as 127 Saami and 2, 840 western Eurasian and Siberian Y-chromosome samples. It was shown that the "Saami motif" variant of mtDNA haplogroup U5b is present in a large area outside Scandinavia. A detailed phylogeographic analysis of one of the predominant Saami mtDNA haplogroups, U5b1b, which also includes the lineages of the "Saami motif, " was undertaken in 31 populations. The results indicate that the origin of U5b1b, as for the other predominant Saami haplogroup, V, is most likely in western, rather than eastern, Europe. Furthermore, an additional haplogroup (H1) spread among the Saami was virtually absent in 781 Samoyed and Ob-Ugric Siberians but was present in western and central European populations. The Y-chromosomal variety in the Saami is also consistent with their European ancestry. It suggests that the large genetic separation of the Saami from other Europeans is best explained by assuming that the Saami are descendants of a narrow, distinctive subset of Europeans. In particular, no evidence of a significant directional gene flow from extant aboriginal Siberian populations into the haploid gene pools of the Saami was found.

Elektroniskā versija nesatur pielikumus, Pliss L. 2007. Mitohondriālās DNS (mtDNS) polimorfismi latviešu etnoģenēzes pētījumos. Latvijas Universitāte, Rīga, 81 lpp. KOPSAVILKUMS Cilvēka mitohondriju genomu (mtDNS) šodien plaši lieto, lai aprakstītu cilvēka populācijas izcelsmi un migrācijas virzienus. Mitohondriālās DNS variāciju kartēšana Āzijā, Amerikā, Āfrikā un Eiropā dod ieskatu par cilvēka populācijas izplatīšanās virzieniem un izkliedi pasaulē. mtDNS īpatnības (maternālā pārmantošana, rekombināciju trūkums) ļauj pēc reģistrētajām mutācijām izsekot cilvēces vēstures ģenealoģiju. Šī ģenealoģija dod iespēju analizēt cilvēka populācijas vēsturi, pirmsvēsturi un prognozēt to attīstību. Liela mēroga Eiropas populāciju mtDNS daudzveidības pētījumi galvenokārt tika veikti tās Rietumu un Centrālās daļās. Tomēr, pēdējo gadu laikā sāka parādīties dati par mitohondriālo variantu dažādību Austrumu Eiropas un slāvu valodās runājošās populācijās. Līdz šim laikam, divās baltu valodās runājošās tautas – latviešos un lietuviešos - populāciju ģenētikas pētījumi tika veltīti pārsvarā tikai autosomālo jeb klasisko ģenētisko marķieru (piemēram, TF*DCH1, PI, LWb) analīzēm un Y hromosomas polimorfismu variācijām. Tādēļ, Latvijas populācijas mitohondriju ģenētiskā heterogenitāte, salīdzinot to ar citu Eiropas populāciju datiem, ir aktuāls ģenētisko pētījumu virziens. Šī darba galvenais mērķis bija atrast un analizēt iedzimto mtDNS variāciju sastopamību Latvijas populācijā un tās etnolingvistiskajās grupās, kā arī veikt daudzpusīgo filoģeogrāfisko analīzi inter- un intra – populāciju līmenī, lai izprastu mtDNS polimorfismu ģenētiskās daudzveidības izcelsmi un to raksturu Latvijas populācijā. Tādā veidā novērota maternālo līniju ģenētiskā struktūra var sniegt informāciju par Latvijas populācijas etnoģenēzi. Šai darbā tika veikta mtDNS variāciju analīze Latvijas populācijā un tās etnolingvistiskajās grupās (analizēto paraugu skaits – 351), pielietojot molekulārās bioloģijas metodes, statistiskās un filoģenētiskās analīzes. Populāciju salīdzinājuma analīzē tika izmantota dažādu Eirāzijas populāciju plašā mtDNS datu bāze (publicēto 11,236 tūkstošu paraugu un nepublicēto 4,732 tūkstošu paraugu mtDNS datu bāze). Balstoties uz vairāku analīžu datiem, iegūtā mtDNS variāciju izplatības biežuma sastopamība dažādos Latvijas reģionos tika salīdzināta ar lingvistisko un antropoloģisko pētījumu rezultātiem. Konstatēts mtDNS ģenētisko variantu iekšējais migrācijas virziens no Latvijas austrumu/dienvidaustrumu daļas (Latgales) uz ziemeļrietumu un centrālo daļu, un noskaidrotais ģenētisko variāciju plūsmas virziens ir saskaņā ar eksistējošiem arheoloģiskajiem datiem. Tika veikta Latvijas populācijā atrasto mtDNS variāciju plaša mēroga filoģeogrāfiskā analīze, kā arī aprakstīta ģenētiskā saistība ar citām Eiropas populācijām (gan indoeiropiešu valodās runājošajām, gan somu – ugru valodās runājošajām populācijām). Parādīts, ka, balstoties uz mtDNS „haplotipu – līdzības” analīzes rezultātiem starp baltu, ģermāņu, slāvu, un somu – ugru valodās runājošajām populācijām, lielākā novēroto mtDNS haplotipu daļa Latvijas populācijā ir līdzīga vai pat identiska ar konstatētajiem mtDNS variantiem citās Austrumu un Rietumu Eiropas populācijās neatkarīgi no populāciju ģeogrāfiskās vai lingvistiskās piederības. Iegūtie rezultāti liecina par kopīgu Eiropas populācijās eksistējošo mtDNS variantu izcelsmi. Izveidots priekšstats par Latvijas populācijā esošo mtDNS ģenētisko variabilitāti var kalpot kā papildus informācijas avots turpmākajiem ģenētisko asociāciju pētījumiem: dažādu fenotipisko izpausmju saistību ar mtDNS polimorfismiem, kā arī būs iespējams veikt ar mitohondriālo iedzimtību saistīto ģenētisko slimību (optiskā neiropātija, miopātija, encefalomiopātija u.c.) diagnostiku, kas Latvijā pagaidām netiek veikta. mtDNS mutāciju detektēšana dažādās vecuma grupās ļaus noskaidrot mitohondriālā genoma polimorfismu lomu novecošanās, kā arī to saistību ar mtDNS replikāciju un transkripciju. Promocijas darbs ir izst, Pliss L. 2007. Mitochondrial DNA (mtDNA) variation and its role in ethnogenesis of Latvians. 81 pp. SUMMARY Variation in the human mitochondrial genome is now routinely described and used to infer the origin and migration patterns in human populations as well as range of expansions and gene flow during the prehistory. Mapping of the variation in the modern mtDNA landscape of Asia, America and Europe is shedding the light on the patterns of colonization and dispersal of peoples in the world. Due to the mode of inheritance and mutation rate of mtDNA the mutations that have struck throughout human history trace the maternal genealogy. This genealogy can be used in attempt to make inferences about prehistoric processes of human populations. Large-scale studies of European mtDNA diversity have been mostly concentrated on Western and Central European populations. In the last few years, data on maternal lineages from Eastern European and Slavonic-speaking populations have started to emerge. So far, population genetic studies of the two extant Baltic-speaking populations – Latvians and Lithuanians, who form a separate branch of the Indo-European language family tree – have mostly touched on the variation of autosomal or classical genetic markers (e.g. TF*DCH1, PI, LWb) and the pattern of spread of Y-chromosomal variation. Therefore, genetic differentiation within the Latvian population and the relationships between it and other European populations are aspects that require further detailed study. The main goal of the present study was to obtain the knowledge about mtDNA variation in Latvia and its sub-populations, and further to perform a large-scale phylogeographic analysis at inter- and intra-population level in order to understand the origin and rise of the genetic diversity of Latvian mtDNA lineages. The analysis of the mtDNA variation in the Latvian population as a whole and it subpopulations (sample size – 351 individuals) has been performed using methods of molecular biology, statistical and phylogenetic approaches. For comparison, the mtDNA database of 11,236 individuals, consisting of published mtDNA data as well as unpublished mtDNA data from 4,732 individuals from different Eurasian populations were used as background information for the analysis. Based on results of the different analyses observed mtDNA variation distribution in Latvian regions was compared with linguistic and anthropological research data. The genetic trace of the forced internal migration movement from eastern/south-eastern region (Lettigalia) towards the north-western and central parts of the country can be seen based on mtDNA variation, and is in accordance with archaeological data. In order to find out genetic relationship with other European populations (Indo-European- and Finno-Ugric-speaking populations) the large-scale phylogeographic analysis of the revealed mtDNA variation distribution in Latvian population was undertaken. The HVS-I haplotype-sharing analysis among Baltic-, Germanic-, Slavonic-, and Finno-Ugric-speaking populations have showed that the vast majority of mtDNA haplotypes found among Latvians are identical to, or close derivatives of, those observed in other Eastern and Western European populations, irrespective of the linguistic affiliations of the latter. Pattern of mtDNA lineages and its variation distribution across Eastern European populations indicate on or most likely reflect an ancient and largely common heritage of European populations. Established notion of the Latvian mtDNA genetic variability further can be used in case-control association studies: possible connection of different phenotypical manifestations with mitochondrial variability in Latvian population (inherited mitochondrial disorders, e.g. Leber’s hereditary optic neuropathy (LHON) and chronic progressive external ophtalmoplegia (CPEO). In the future we can implement the association study on mtDNA variation spread and its molecular characteristics in two

Elektroniskā versija nesatur pielikumus, Anotacija Ixodidae dzimtas erces ir pasaule pazistamas ka daudzveidigu cilveku un dzivnieku patogenu cirkulacijas uzturetajas daba. Musu valsti noverotas vairakas Ixodidae dzimtas sugas, tomer epidemiologiska nozime lidz šim konstateta tikai divam Ixodidae dzimtas Ixodes gints ercem: Ixodes ricinus L., kas izplatita visa valsts teritorija, retak tas austrumdala, kur domine Ixodes persulcatus P. Sch. Latvija tiek registreta iedzivotaju saslimstiba ar tris šo ercu parnesatam infekcijas slimibam - ercu encefalitu, Laima boreliozem un ari ar erlihiozi (anaplazmozi). Ši petijuma galvenais merkis bija noskaidrot Ixodidae epidemiologiski nozimigo ercu sugu izplatibu, to parnesato infekcijas slimibu nozimi un molekularo epidemiologiju Latvija. Šeit apkopoti un analizeti ilggadigi statistikas dati un kopš 1995. gada praktiski izdaritie noverojumi ercu parnesto slimibu dabas pereklos, to saistiba ar saslimstibas tendencem, veikta Ixodes ercu aktivitates un izplatibas ilggadigas tendences ietekmejušo faktoru izpete, ka ari apskatiti atsevišku Ixodes ercu parnesto patogeno un neskaidras patogenitates mikroorganismu sugu molekularie petijumi ar merki noskaidrot to izplatibu un sastopamibu Latvija. Attistitas molekularas metodes Anaplasmataceae dzimtas prokariotu prevalences noteikšanai erces (divpakapju PCR, hibridizacijas un sekvencešanas), ar hibridizacijas metodi noskaidrota Babesia gints sugu prevalence abu dzimumu erces un geografiska izplatiba Latvija. Tika noskaidrots, ka ercu encefalita incidences ikgadejie maksimumi 1994. un 1995. gada bija saistiti galvenokart tikai ar I. ricinus aktivitati šis ercu sugas izplatibas rajonos Latvija. I. ricinus un I. persulcatus ikgadejai aktivitatei monitoringa vietas noverota lidziga tendence (r=0,72; p