| 1. |
- Alfonso, Julieta, et al.
(författare)
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Analysis of gene expression in the rat hippocampus using Real Time PCR reveals high inter-individual variation in mRNA expression levels
- 2002
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Ingår i: Journal of Neuroscience Research. - : Wiley. - 0360-4012 .- 1097-4547. ; 67:2, s. 225-34
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Tidskriftsartikel (refereegranskat)abstract
- In mammals, gene transcription is a step subjected to tight regulation mechanisms. In fact, changes in mRNA levels in the central nervous system (CNS) can account for numerous phenotypic differences in brain function. We performed a high-resolution analysis of mRNA expression levels for 37 genes selected from a normal rat hippocampus cDNA library. mRNA amounts were quantified using a Real Time PCR SYBR Green assay. We found that, in general, individuals from an inbred rat population (n = 20) have shown 2-3 times differences in the basal level of expression of the genes analyzed. Up to several fold differences among individuals were observed for certain genes. These inter-individual differences were obtained after correction for the different amounts of mRNA in each sample. Power calculations were performed to determine the number of individuals required to detect reliable differences in expression levels between a control and an experimental group. These data indicated that, depending on the variability of the candidate gene selected, it was necessary to analyze from five to 135 individuals in each group to detect differences of 50% in the levels of mRNA expression between two groups investigated. The comparison of mRNA abundance from different genes revealed a wide range of expression levels for the 37 genes, showing a 26,000-fold difference between the highest and lowest expressed gene.
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| 2. |
- Balciuniene, Jorune, et al.
(författare)
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Alpha-tectorin involvement in hearing disabilities : One gene-two phenotypes
- 1999
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Ingår i: Human Genetics. - : Springer Science and Business Media LLC. - 0340-6717 .- 1432-1203. ; 105:3, s. 211-216
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Tidskriftsartikel (refereegranskat)abstract
- The human alpha-tectorin (TECTA) gene has recently been cloned and proposed to be involved in autosomal dominant non-syndromic hearing impairment (NSHI) in two families linked to the DFNA12 locus. We have studied a Swedish pedigree with autosomal dominant NSHI with possible digenic inheritance of the disease, involving locus DFNA12 in chromosome 11 and locus DFNA2 in chromosome 1. Mutation analysis of the TECTA gene in this family has identified eight nucleotide substitutions indicating that TECTA is highly polymorphic. One of the changes results in a cysteine to serine (C 1057 S) mutation, in the zonadhesin domain of TECTA; this segregates with the disease haplotype on chromosome 11 and is not present in a control population. The mutation results in the replacement of a cysteine in one of the repeats of the zonadhesin/Von Willebrand domain of the protein and might cause a change in the crosslinking of the polypeptide. These findings add support to the involvement of TECTA in hearing disabilities. However, the three families carrying different TECTA mutations also show phenotypic differences: the hearing loss ranges from prelingual to progressive with late onset. The explanation for the different phenotypes and some clues regarding the functions of TECTA may lie in the localization of the mutations in the different modules of the protein. Another possibility is that the phenotype in the Swedish family is the result of two defective genes.
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| 3. |
- Balciuniene, Jorune, et al.
(författare)
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Evidence for digenic inheritance of nonsyndromic hereditary hearing loss in a Swedish family
- 1998
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Ingår i: American Journal of Human Genetics. - : Elsevier BV. - 0002-9297 .- 1537-6605. ; 63:3, s. 786-93
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Tidskriftsartikel (refereegranskat)abstract
- We investigated a Swedish family with nonsyndromic progressive bilateral sensorineural hearing loss. Thirteen candidate loci for autosomal dominant nonsyndromic hearing loss were tested for linkage in this family. We found significant LOD scores (>3) for markers at candidate locus DFNA12 (11q22-q24) and suggestive LOD scores (>2) for markers at locus DFNA2 (1p32). Our results for markers on chromosome 11 narrowed down the candidate region for the DFNA12 locus. A detailed analysis of the phenotypes and haplotypes shared by the affected individuals supported the notion that two genes segregated together with hearing impairment in the family. Severely affected family members had haplotypes linked to the disease allele on both chromosomes 1 and 11, whereas individuals with milder hearing loss had haplotypes linked to the disease allele on either chromosome 1 or chromosome 11. These observations suggest an additive effect of two genes, each gene resulting in a mild and sometimes undiagnosed phenotype, but both together resulting in a more severe phenotype.
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| 4. |
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| 5. |
- Björnerfeldt, Susanne, 1975-
(författare)
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Consequences of the Domestication of Man’s Best Friend, The Dog
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The dog was the first animal to be domesticated and the process started at least 15 000 years ago. Today it is the most morphologically diverse mammal, with a huge variation in size and shape. Dogs have always been useful to humans in several ways, from being a food source, hunting companion, guard, social companion and lately also a model for scientific research. This thesis describes some of the changes that have occurred in the dog’s genome, both during the domestication process and later through breed creation. To give a more comprehensive view, three genetic systems were studied: maternally inherited mitochondrial DNA, paternally inherited Y chromosome and biparental autosomal chromosomes. I also sequenced complete mitochondrial genomes to view the effect new living conditions might have had on dogs’ genes after domestication. Finally, knowledge of the genetic structure in purebred dogs was used to test analytic methods usable in other species or in natural populations where little information is available. The domestication process appears to have caused a relaxation of the selective constraint in the mitochondrial genome, leading to a faster rate of accumulation of nonsynonymous changes in the mitochondrial genes. Later, the process of breed creation resulted in genetically separated breed groups. Breeds are a result from an unequal contribution of males and females with only a few popular sires contributing and a larger amount of dams. However, modern breeder preferences might lead to disruptive selective forces within breeds, which can result in additional fragmentation of breeds. The increase in linkage disequilibrium that this represents increases the value of purebred dogs as model organisms for the identification and mapping of diseases and traits. Purebred dogs’ potential for these kinds of studies will probably increase the more we know about the dog’s genome.
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| 6. |
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| 7. |
- Castensson, Anja, et al.
(författare)
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Decrease of serotonin receptor 2C in schizophrenia brains identified by high-resolution mRNA expression analysis
- 2003
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Ingår i: Biological Psychiatry. - 0006-3223 .- 1873-2402. ; 54:11, s. 1212-1221
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: RNA expression profiling can provide hints for the selection of candidate susceptibility genes, for formulation of hypotheses about the development of a disease, and/or for selection of candidate gene targets for novel drug development. We measured messenger RNA expression levels of 16 candidate genes in brain samples from 55 schizophrenia patients and 55 controls. This is the largest sample so far used to identify genes differentially expressed in schizophrenia brains. METHODS: We used a sensitive real-time polymerase chain reaction methodology and a novel statistical approach, including the development of a linear model of analysis of covariance type. RESULTS: We found two genes differentially expressed: monoamine oxidase B was significantly increased in schizophrenia brain (p =.001), whereas one of the serotonin receptor genes, serotonin receptor 2C, was significantly decreased (p =.001). Other genes, previously proposed to be differentially expressed in schizophrenia brain, were invariant in our analysis. CONCLUSIONS:The differential expression of serotonin receptor 2C is particularly relevant for the development of new atypical antipsychotic drugs. The strategy presented here is useful to evaluate hypothesizes for the development of the disease proposed by other investigators.
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| 8. |
- Castensson, Anja, et al.
(författare)
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Decrease of serotonin receptor 2C in schizophrenia brains identified by high-resolution mRNA expression analysis
- 2003
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Ingår i: Biological Psychiatry. - : Elsevier BV. - 0006-3223 .- 1873-2402. ; 54:11, s. 1212-1221
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Tidskriftsartikel (refereegranskat)abstract
- Background: RNA expression profiling can provide hints for the selection of candidate susceptibility genes, for formulation of hypotheses about the development of a disease, and/or for selection of candidate gene targets for novel drug development. We measured messenger RNA expression levels of 16 candidate genes in brain samples from 55 schizophrenia patients and 55 controls. This is the largest sample so far used to identify genes differentially expressed in schizophrenia brains.Methods: We used a sensitive real-time polymerase chain reaction methodology and a novel statistical approach, including the development of a linear model of analysis of covariance type.Results: We found two genes differentially expressed: monoamine oxidase B was significantly increased in schizophrenia brain (p = .001), whereas one of the serotonin receptor genes, serotonin receptor 2C, was significantly decreased (p = .001). Other genes, previously proposed to be differentially expressed in schizophrenia brain, were invariant in our analysis.Conclusions: The differential expression of serotonin receptor 2C is particularly relevant for the development of new atypical antipsychotic drugs. The strategy presented here is useful to evaluate hypothesizes for the development of the disease proposed by other investigators.
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| 9. |
- Castensson, Anja, et al.
(författare)
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High-resolution quantification of specific mRNA levels in human brain autopsies and biopsies
- 2000
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Ingår i: Genome Research. - : Cold Spring Harbor Laboratory. - 1088-9051 .- 1549-5469. ; 10:8, s. 1219-29
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Tidskriftsartikel (refereegranskat)abstract
- Quantification of mRNA levels in human cortical brain biopsies and autopsies was performed using a fluorogenic 5' nuclease assay. The reproducibility of the assay using replica plates was 97%-99%. Relative quantities of mRNA from 16 different genes were evaluated using a statistical approach based on ANCOVA analysis. Comparison of the relative mRNA levels between two groups of samples with different time postmortem revealed unchanged relative expression levels for most genes. Only CYP26A1 mRNA levels showed a significant decrease with prolonged time postmortem (p = 0.00004). Also, there was a general decrease in measured mRNA levels for all genes in autopsies compared to biopsies; however, on comparing mRNA levels after adjusting with reference genes, no significant differences were found between mRNA levels in autopsies and biopsies. This observation indicates that studies of postmortem material can be performed to reveal the relative in vivo mRNA levels of genes. Power calculations were done to determine the number of individuals necessary to detect differences in mRNA levels of 1.5-fold to tenfold using the strategy described here. This analysis showed that samples from at least 50 individuals per group, patients and controls, are required for high-resolution ( approximately twofold changes) differential expression screenings in the human brain. Experiments done on ten individuals per group will result in a resolution of approximately fivefold changes in expression levels. In general, the sensitivity and resolution of any differential expression study will depend on the sample size used and the between-individual variability of the genes analyzed.
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| 10. |
- Castensson, Anja, 1971-
(författare)
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High-resolution Studies of mRNA Expression in Brain : A Search for Genes Differently Expressed in Schizophrenia
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Gene expression differences between patients and controls can be used to find susceptibility genes and drug targets for a disease. High-resolution strategies are required because the differences between the investigated groups may be small and numerous factors may affect the mRNA quantity. This thesis is based on the use of real-time RT-PCR combined with a new statistical approach, developed to detect small differences between patients and controls and differences due to patient subgroups. Comparisons between human brain biopsy and autopsy samples showed that post-mortem tissue can be used to make conclusions on the relative mRNA levels in the living brain. Power analysis based on human brain mRNA expression from 14 genes adjusted with two reference genes, revealed that a sample size of 50 patients and 50 controls was required to detect a 2-fold difference with a power and a confidence of 95%. A similar study in rats revealed that approximately the same sample size was required for rat brain mRNA expression studies. The mRNA levels of several genes were studied in 55 schizophrenia and 55 control prefrontal brain autopsies, using a novel and more powerful statistical analysis. The serotonin receptor 2C gene (HTR2C) showed a significant 1.5-fold decrease in the patients as compared to controls, and the monoamine oxidase B gene (MAOB) a 1.2-fold increase. The mechanism behind the decrease of HTR2C mRNA levels was investigated by studying the correlation of drug treatment and HTR2C promoter polymorphisms to the HTR2C expression levels. The observed decrease was present in untreated patients, suggesting that the HTR2C mRNA decrease is correlated with the disease and not the treatment. There was no association between promoter polymorphisms and HTR2C expression levels. Thus, the molecular mechanism for the decreased expression remains unclear. Nevertheless, the results support a role for monoaminergic synapses in schizophrenia.
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