hohPublica :: Browsing by Subject "Genexpression"

Browsing by Subject "Genexpression"

Now showing 1 - 9 of 9

Analyse komplexer Merkmale beim Schwein mittels SNP-Chip Genotypen, Darmmikrobiota- und Genexpressionsdaten
(2017) Maushammer, Maria; Bennewitz, Jörn
In the present scientific research, SNP chip genotypes, gut microbiota and gene expression data were used for analysing complex traits in a Piétrain population. These data were collected from around 200 performance tested sows and were used for genetic and microbial analyses of complex trait as well as for structural and functional meat quality traits. The gut microbiome plays a major role in the immune system development, state of health and energy supply of the host. Quantitative-genetic methods were applied to analyse the interrelationship between pig gut microbiota compositions, complex traits (daily gain, feed conversion and feed intake) and pig genomes. The specific aims were to characterize the gut microbiota of the pigs, to analyse the effects of host genetics on gut microbial composition, and to investigate the role of gut microbial composition on the host’s complex traits. The pigs were genotyped with a standard 60K SNP chip. Microbial composition was characterized by 16S rRNA gene amplicon sequencing technology. Ten out of 51 investigated bacterial genera showed a significant host heritability, ranging from 0.32 to 0.57. Conducting genome wide association analysis showed associations of 22 SNPs and six bacterial genera. The potential candidate genes identified are involved in the immune system, mucosa structure and secretion of digestive juice. These results show, that parts of the gut microbiota are heritable and that the gut microbiome can be seen as quantitative trait. Microbial mixed linear models were applied to estimate the microbiota variance for each of the investigated traits. The fraction of phenotypic variance explained by the microbial variance was 0.28, 0.21, and 0.16 for daily gain, feed conversion, and feed intake, respectively. The SNP data and the microbiota data were used to predict the phenotypes of the traits using both, genomic best linear unbiased prediction (G-BLUP) and microbial best linear unbiased prediction (M-BLUP) methods. The prediction accuracies of G-BLUP were 0.35, 0.23, and 0.20 for daily gain, feed conversion, and feed intake, respectively. The corresponding prediction accuracies of M-BLUP were 0.41, 0.33, and 0.33. Thus, the gut microbiota can be seen as an explaining variable for complex traits like daily gain, feed conversion and feed intake. In addition, in combination with meat quality traits, transcript levels of muscle tissue were analysed at time of slaughtering. This study should give an insight into the biological processes involved in meat quality characteristics. The aims were to functionally characterise differentially expressed genes, to link the functional information with structural information obtained from GWAS, and to identify potential candidate genes based on these results. An important meat quality trait is the intramuscular fat content, since it affects the juiciness, the taste and the tenderness of the meat. Another important trait is drip loss which causes not only a loss of weight but also a loss of important proteins. Both traits have an impact on the consumer acceptance of fresh meat products. For each of the two traits, eight discordant sibling pairs were selected out of the Piétrain sample and were used for genome-wide gene expression analyses. Thirty five and 114 genes were identified as differentially expressed and trait correlated genes for intramuscular fat content and drip loss, respectively. On the basis of functional annotation, gene groups belonging to the energy metabolism of the mitochondria, the immune response and the metabolism of fat, were associated with intramuscular fat content. Gene groups associated with protein ubiquitination, mitochondrial metabolism, and muscle structural proteins were associated with drip loss. Furthermore, genome-wide association analyses were carried out for these traits and their results were linked to the genome-wide expression analysis by functional annotation. In this context, intramuscular fat was related to muscle contraction, transmembrane transport and nucleotide binding. Drip loss was characterized by the endomembrane system, the energy generation of cells, and phosphorus metabolic processes. Three and four potential candidate genes were identified for intramuscular fat content and drip loss, respectively.
Bioeffector products for plant growth promotion in agriculture : modes of action and the application in the field
(2021) Weber, Nino Frederik; Neumann, Günter
Modern agriculture faces a conflict between sustainability and the demand for a higher food production. This conflict is exacerbated by climate change and its influence on vegetation, ecology and human society. To reduce land use, the reduction of yield losses and food waste is crucial. Moreover a sustainable intensification is necessary to increase yields, while at the same time input of limited resources such as drinking water or fertilizer should be kept as low as possible. This might be achieved by improving nutrient recycling and plant resistance to abiotic or biotic stress. Bioeffectors (BE) comprise seaweed or plant extracts and microbial inoculums that may stimulate plant growth by phytohormonal changes and increase plant tolerance to abiotic stress (biostimulants), solubilize or mobilize phosphorus from sparingly soluble sources such as Al/Fe or Ca-phosphates in the soil, rock phosphates, recycling fertilizer or organic phosphorus sources like phytate (biofertilizer), or improve plant resistance against pathogens by induced-systemic resistance (ISR) or antibiosis (biocontrol). For this study, in total 18 BE products were tested in germination, pot and field experiments for their potential to improve plant growth, cold stress tolerance, nutrient acquisition and yield in maize and tomato. Additionally, a gene expression analysis in maize was performed using whole transcriptome sequencing (RNA-Seq) after the application of two potential plant growth promoting rhizobacteria (PGPR), the Pseudomonas sp. strain DSMZ 13134 “Proradix” and the Bacillus amyloliquefaciens strain FZB42. Seaweed products supplemented with high amounts of the micronutrients Zn and Mn were effective in reducing detrimental cold stress reactions in maize whereas microbial products and seaweed extracts without micronutrient supplementation failed under the experimental conditions. At optimal temperature the product containing the Pseudomonas sp. strain was repeatedly able to stimulate root and shoot growth of maize plants whereas in tomato only in heat-treated soil substrate significant effects were observed. Results indicate that the efficacy of the product was mainly attributed to stimulation or shifts in the soil microbial community. Additionally, the FZB42 strain was able to stimulate root and plant growth in some experiments whereas the effects were less reproducible and more sensitive to environmental conditions. Fungal BE products were less effective in plant growth stimulation and showed detrimental effects in some experiments. Under the applied experimental conditions BE-derived plant growth stimulation mainly was attributed to biostimulation but aspects of biofertilization or biocontrol cannot be excluded, as all experiments were conducted in non-sterile soil substrates. Root and shoot growth are stimulated in response to hormonal shifts. In the gene expression analysis only weak responses to BE treatments were observed, as previously reported from other studies conducted under non-sterile conditions. Nevertheless, some plant stress responses were observed that resembled in some aspects those reported for phosphorus (P) deficiency in others those reported for ISR/SAR. Especially the activation of plant defence mechanisms, such as the production of secondary metabolites, ethylene production and reception and the expression of several classes of stress-related transcription factors, including JA-responsive JAZ genes, was observed. It also seems probable that in plants growing in PGPR-drenched soils, especially at high application rates, a sink stimulation for assimilates triggers changes in photosynthetic activity and root growth leading to an improved nutrient acquisition. Nevertheless, due to the complexity of interactions in natural soil environments as well as under practice conditions, a designation of a distinct mode of action for plant growth stimulation by microbial BEs is not realistic. A comparison of the overall results with those reported in literature or other working groups in a common research project (“Biofector”) supported the often-reported low reproducibility of plant growth promotion effects by BE products under applied conditions. Factors that influenced BE efficacy were application time and rates, temperature, soil buffer capacity, phosphorus sources and nitrogen fertilization, light conditions and the soil microbial community. Results indicate that in maize cultivation seed treatment is the most economic application technique for microbial products whereas for vegetable or high-value crops with good economic benefit soil drenching is recommended. For seaweed extracts foliar application seems to be the most economic and efficient choice. Furthermore, results emphasize the importance of a balanced natural soil microflora for plant health and yield stability.
Mitochondrial haplotypes, gene expression and nuclear diversity in two strains of laying hens
(2021) Dreyling, Clara; Hasselmann, Martin
The domesticated chicken (Gallus gallus domesticus) is the most popular and widely spread domestic fowl worldwide, providing human with a stable source of protein in form of meat and eggs for centuries. The ongoing growth of human population increases the need for food and made poultry production one of the fasted growing sectors in the past decades. This need for food has resulted in several different strains which outperform their wild ancestors in terms of meat and egg production. During the past decades not only animal welfare gained importance but also ecological aspects such as global warming and the shortage of resources are becoming more important to society. One important resource for mankind which is becoming shortened is phosphorus (P), whose deposits in form of rock phosphate could be exhausted within the next 50-100 years. 90% of P supply is used in agriculture as fertilizer, whose demand will increase as well with growing population. This thesis focuses on the mitochondrial genetic background and mitochondrial related gene expression in the context of the productive life span and different diets in two contrasting high-yielding strains of laying hens, Lohmann Brown-Classic (LB) and Lohmann LSL-Classic (LSL). Mitochondria, which are commonly known as the powerhouse of the cell due to their role as the main producer of energy, play roles in other processes from cellular homeostasis to the process of ageing. The process of oxidative phosphorylation depends on the availability of P and thus, they become an important part of the complex framework of P utilization. In addition, mitochondrial haplotypes are known to affect physiological traits such as body weight in laying hens or important traits such as e.g. the metabolic capacity in dairy cows. It is known, that single mutations in the mitochondrial genome lead to a better adaptation to height in the Tibetan chicken or play a role in diseases from Alzheimer to obesity or lead to resistance to disease such as Marek’s disease in birds. This work provides insight into the whole mitochondrial genome of 180 laying hens of two commercial strains and links this information to physiological traits and genetic diversity. In addition, the first large-scaled gene expression analyses in the context of the productive life span and different P and Ca contents in laying hens is implemented. The analysis of mitochondrial haplotypes revealed a low level of genetic diversity with only three haplotypes within the LB strain while all LSL hens shared the same mitochondrial genome. Following from this observation, the nuclear genome was analysed based on genotyping data to reveal the whole genetic diversity of both strains. On the nuclear genetic level, both strains appeared as clearly distinct and equally diverse, while some individuals appear as strikingly close related. These individuals are mostly half-siblings sharing the same mitochondrial haplotype, underlining the need for more analyses about the genetic structure about the parental generation, especially the maternal background. Although there were no strong associations were found between the mitochondrial haplotypes and the analysed phenotypic traits (feed intake, body weight, P and Ca utilization), the differences between the strains indicate a potential involvement of the mitochondrial genetic background. The gene expression analyses revealed tissue type and point of the productive life span as the main influencers on gene expression while the influence of the strain is secondary. In addition, the expression of the gene GAPDH, which is frequently used as a reference gene for normalization in gene expression studies, was influenced by tissue and strain, leading to the decision to exclude it as a reference, that should be considered for in further studies. Further, no influence of the changes in dietary P and Ca on gene expression could be observed, suggesting that a reduction of 20% of both minerals is possible without the need to adapt gene expression. However, the results show, that a reduction of both minerals has less effect than a reduction of P alone, leading to an imbalance. In the context of the productive live span, mitochondrial and mitochondrial regulatory genes react contrary, illustrating the complexity of mitochondrial gene expression and regulation. In addition to the higher variance in the analysed phenotypic traits and mitochondrial genome in LB hens, they showed signs of increased oxidative stress compared to LSL hens. In the context of the productive life span, a potential higher demand for energy is suggested, since OXPHOS related gene expression is increasing. As a conclusion this work provides an insight into the mitochondrial genome and provides the first large scaled analysis of mitochondrial linked gene expression in two contrasting laying hen strains.
Molecular characterization of the interaction of lactobacilli with food environments and enterohemorrhagic Escherichia coli O157:H7
(2009) Hüfner, Eric; Hertel, Christian
The first part of this thesis focuses on the gene expression of Lactobacillus sakei and Lactobacillus reuteri in food fermentation using in vivo expression technology (IVET) and DNA microarray hybridization analysis, respectively. Both technologies allow the identification of regulated genes in a specific environment, which are likely to contribute to the ecological performance of the organism. Thus, the obtained results provide a basis for the development of new strategies to improve the fermentation process, as it was demonstrated by the development of an efficient method for the improvement of sausage fermentation using L. sakei. To obtain hygienically safe products, the function of starter cultures mostly relies on the ability to acidify and produce other antimicrobial principles. However, it was recently demonstrated that the interaction with pathogens also can take place on another level, apart from killing or growth inhibition. Lactobacilli have been shown to influence the virulence gene expression of enterohemorrhagic Escherichia coli (EHEC) via the bacterial communication system termed quorum sensing. The second part of the thesis explores the impact of quorum sensing between Lactobacillus reuteri strains and EHEC O157:H7 on EHEC virulence gene expression. By using a green fluorescent protein reporter gene assay, it was demonstrated for the first time that the transcription of the ler virulence regulator gene is significantly reduced by secreted substances of L. reuteri in a strain- and quorum sensing-dependent manner.
Nutritional regulation of DNA methylation and gene expression in maize
(2018) Mager, Svenja; Ludewig, Uwe
DNA methylation in plants plays a role in transposon silencing, genome stability and gene expression regulation. Environmental factors alter the methylation pattern of DNA and recently nutrient stresses, such as phosphate starvation, were shown to alter DNA methylation. DNA methylation had been frequently addressed in plants with notably small genomes that are poor in transposons. Here, part of the DNA methylome of nitrogen-, phosphorus- and zinc-deficient (-N, -P and -Zn, respectively) maize roots were compared by reduced representation sequencing and their relationship with gene expression under prolonged stresses analyzed. Tremendous DNA methylation loss was encountered in maize under nitrogen and zinc deficiency, but much less under phosphorus deficiency. This occurred only in the symmetrical cytosine contexts, predominantly in CG context, but also in the CHG context. In contrast to other plants, differential methylation in the more flexible CHH context was essentially absent. For each sample, specific nutrient deficiency-regulated genes were differentially expressed. In -Zn samples the lowest number of differentially expressed genes was found while -N and -P samples contained a similar number of differentially expressed genes. For all samples, differentially methylated regions (DMRs) were predominantly identified in transposable elements (TEs). A minor fraction of such DMRs was associated with altered gene expression of nearby genes in -N and -P. Interestingly, although these TEs were mostly hypomethylated, they were associated with both upand down-regulated gene expression. For -Zn, these associations were not found but a correlation between hypomethylation of gene bodies and expression of some genes. Here again, hypomethylation occurred with up- and downregulation of gene expression. The results suggested a different methylome regulation in maize compared to rice and Arabidopsis upon nutrient deficiencies indicating a nutrient- and species-specific association of genomic DNA methylation and gene expression. The limited correlation between differential DNA methylation and gene expression suggested that heritable regulation of the expression of nutrient deficiency-regulated genes was not the primary function of the methylation loss. Rather, the major function of the DNA methylation loss in this experiment may have been to increase the genetic diversity in the next generation by increased frequency of recombination events, mutations and transposable element movements.
Regulatory elements controlling the expression of OR37 genes
(2007) Zhang, Yongquan; Breer, Heinz
The genes of the OR37 family are clustered in two loci (cluster I and cluster II) on mouse chromosome 4. These genes encode distinct olfactory receptors (ORs) which are characterised by an insertion of six amino acids in the third extracellular loop and moreover, these receptor types are only expressed in cells which are segregated in a small patch on the central nasal turbinate. As first steps to unravel the molecular basis of this unique topographic expression pattern previous studies have led to the identification of highly conserved sequence motifs including an olf-1 site in the putative promoter region of these genes and subsequently several transcription factors were identified which did bind to these sites. However, it remained elusive if an interaction between the transcription factors and the putative promoter sites may have functional implications. Therefore, a heterologous system was employed to assess the consequence of an interaction between the putative promoters and the transcription factors. HEK 293 cells were cotransfected with a reporter gene under the control of putative mOR37 promoter regions and an expression vector based gene encoding the transcription factor. The expression rate of the reporter gene was monitored by measuring luciferase activity. It was found that the three O/E transcription factors (O/E-1, O/E-2 and O/E-4) induced significant activation of the mOR37 promoters; in addition, it was observed that the putative promoters of other OR genes were also activated, suggesting that the O/E proteins may play a general role in the regulation of OR gene expression. Mutagenesis experiments revealed that the effects of O/E proteins were dependent on the presence of an olf-1 site within the promoter region. For the transcription factor Lhx-2 it was found that not all but only promoters of distinct OR-genes were affected. For the mOR37 promoters a simultaneous action of O/E protein and Lhx-2 elicited an increase of reporter gene expression. The data indicate that the putative mOR37 promoters could drive gene expression in the presence of the crucial transcription factors in this heterologous system. In order to explore to what extent the promoter may contribute to the characteristic topographic expression pattern of the mOR37 genes in vivo, a mOR37C transgene which included the coding exon and the putative promoter, was randomly inserted into the mouse genome. Seven lines were obtained; in all lines the transgene was specifically expressed in olfactory sensory neurons (OSN). In six lines the transgene expression was restricted to the central patch of the olfactory turbinates, typical for the OR37 genes. In one line (line 7) the transgene was also expressed in OSNs ectopically positioned outside the patch within the medial zone. It was found that the transgene was expressed in a mutually exclusive manner and from only one allele. The axons of OSNs expressing the transgene co-converged in the same glomerulus with the axons from neurons expressing the endogenous gene. In line #7 the formation of ectopic glomeruli was observed. The number of OSNs expressing the transgene varied considerably among lines; these differences were independent from the copy number of the transgene. The data indicate that the short putative promoters, most likely the conserved motifs, were sufficient to drive the OR37 gene expression in a tissue specific way and most aspects of the OR37 gene expression were mimicked by the transgene; however, considerable differences between certain lines suggested additional regulatory elements, such as a locus control region (LCR). Since regulatory elements for gene transcription, such as promoters, enhancers and LCRs, appear to be conserved across species, a comparative approach was utilized to search for the LCR-like element for the OR37 locus by sequence alignment across distantly related mammals. A segment of 270 base pairs located 137 Kb upstream of OR37 cluster I was found to be highly conserved between mouse, human, dog and opossum. It was not associated with an exon of any known gene and was highly correlated with OR37 cluster I rather than with the neighboring genes, since the flanking genes did not show syntenic conservation in the opossum genome. A homologous counterpart for this segment was found downstream of the OR37 cluster II locus; an alignment of the cluster II sequence across species identified the conservation of this counterpart. Examination for relevant motifs in this segment and comparison with the conserved H element revealed two common transcription factor binding sites, at least one of them is known to be essential for generating DNase I hypersensitive sites in the LCR of the beta globin gene locus. Further studies are required to evaluate a possible role of this conserved segment in the regulation of the OR37 gene expression.
The genetic basis of heat tolerance in temperate maize (Zea mays L.)
(2016) Frey, Felix P.; Stich, Benjamin
The global mean temperature and probability of heat waves are expected to increase in the future, which has the potential to cause severe damages to maize production. To elucidate the genetic mechanisms of the response of temperate maize to heat stress and for the tolerance to heat stress, in a first experiment I applied gene expression profiling. Therewith, I investigated the transcriptomic response of temperate maize to linearly increasing heat levels. Further, I identified genes associated with heat tolerance in a set of eight genotypes with contrasting heat tolerance behavior. I identified 607 heat responsive genes, which elucidate the genetic pathways behind the response of maize to heat stress and can help to expand the knowledge of plant responses to other abiotic stresses. Further, I identified 39 genes which were differentially regulated between heat tolerant and heat susceptible inbreds and, thus, are putative heat tolerance candidate genes. Two of these candidate genes were located in genome regions which were associated with heat tolerance during seedling and adult stage that have been detected in QTL studies in the frame of this thesis. Their exact molecular functions, however, are still unknown. The statistical approach to identify heat tolerance genes, presented in my thesis, enables researchers to investigate the transcriptomic response of multiple genotypes to changing conditions across several experiments, considering their natural variation for a quantitative trait. In order to develop more heat tolerant cultivars, knowledge of natural variation for heat tolerance in temperate maize is indispensable. Therefore, heat tolerance was assessed in a set of intra- and interpool Dent and Flint populations on a multi-environment level. Usually, heat stress in temperate Europe occurs during the adult stage of maize. However, as maize is of increasing importance as a biogas crop, farmers can reduce the growth period by postponed sowing after the harvest of the winter cereals in early summer and, thus, sensitive maize seedlings can be exposed to heat stress. Therefore, I aimed to assess heat tolerance in six connected segregating Dent and Flint populations during both developmental stages considering besides multiple environments also multiple traits. At heat stress, I observed an average decrease of 20% of the shoot dry weight during seedling stage and an average of 50% of yield loss, when heat stress was present during adult stage. At the heat locations heat stress was present in the year, when the experiments were conducted as temperatures exceeded 32°C there for more than 400 hours during the growing period in contrast to less than 30 hours at the standard locations. This emphasizes that maize crop production can suffer with the increasing number and intensity of summer heat waves. Furthermore, the study revealed strong differences between genotypes, which was indispensable to differentiate between heat tolerant and heat susceptible inbred lines. The tested genotypes originating from the Flint pool turned out to possess higher heat tolerance during seedling stage, whereas the genotypes derived from the Dent pool possessed higher heat tolerance during adult stage. This fact could be exploited by the maintenance of two pools with contrasting heat tolerance and could be beneficial for hybrid breeding. A direct selection of more heat tolerant genotypes in terms of grain yield is expensive and time-consuming. To facilitate the selection process in order to develop more heat tolerant cultivars, breeders could make use of marker assisted selection. To lay the foundation for this technique, in my thesis, QTL for heat tolerance during adult and during seedling stage were identified with the previously mentioned populations. Two QTL explained 19% of the total variance for heat tolerance with respect to grain yield in a simultaneous fit. Furthermore each two QTL were identified for two principal components, which accounted for heat tolerance during seedling stage. They explained 14 and 12% of the respective variance. The results can be used by breeding companies to develop marker assays in order to select heat tolerant genotypes from their proprietary genetic material during both stages in an initial screening. This would reduce the field capacities considerably, which are needed to test heat tolerance on a field level.
Untersuchungen zur spezifischen Genexpression von enterohämorrhagischen Escherichia coli (EHEC) in der Lebensmittelmatrix
(2012) Kroj, Andrea; Schmidt, Herbert
Ground beef as a high risk food is known to be an cause of human infection with Shiga toxin-producing E. coli (STEC). The pathogens infect humans by the ingestion of undercooked ground meat and cause severe diseases like hemorrhagic colitis or the life-threatening hemolytic uremic syndrome. E. coli O157:H7 strain EDL933 as a representative of enterohemorrhagic E. coli (EHEC), a subgroup of STEC, was analysed for in vivo induced genes in ground beef with the help of the in vivo expression technology. It could be demonstrated that the promoter selection vector pKK232-8, which contains a promoterless chloramphenicol resistance gene, is not a suitable vector for a study of gene expression in this matrix. The detection of in vivo expressed genes using the alcohol-soluble and bacteriostatic antibiotic was not possible. Therefore, the promoter selection vector pAK-1 was developed. The new vector system was based on a water-soluble and bactericidal kanamycin resistance gene for selection. In the present study, the vector was established and used for analysis of the gene expression in ground meat. 20 in vivo induced genes that were expressed during growth in ground meat under elevated temperature conditions at 42°C could be detected. Eight genes were associated with energy and nucleotide metabolism, macromolecule synthesis, transport and stress response of the cell. The major part of 12 genes was attributed to a putative or unknown function. Predominantly, identified genes could not be associated with virulence or stress response of the cell. The results of this study, using the in vivo expression technology, showed that genes which are expressed under specific conditions in ground meat could be detected with the help of the chosen method. A first insight into the gene expression of strain EDL933 in ground beef could be acquired. During further investigations a comparison of the fitness of 23 E. coli strains belonging to serogroups O26, O103 and O157 was realized. The isolates originating from foods, patients with HUS and animals were compared in ground beef. The determined differences showed strain-specificity and temperature-specificty. The fitness of the strains varied dependent on the chosen temperatures at 15, 20 and 37 degrees. The analysis of the strains based on ten virulence factors showed that the observed differences could not be attributed to the presence or the number of virulence genes. A correlation between the fitness and the production of a bacteriocin could not be found.
Wirt-Virus Wechselwirkungen bei der Infektion durch Acanthocystis turfacea Chlorella Virus 1 : Regulation der Genexpression früher Gene und des Ubiquitin-Systems
(2021) Lindner, Kamila; Pfitzner, Artur J. P.
Acanthocystis turfacea Chlorella Virus 1 (ATCV-1) is a virus of the genus Chloroviruses that infects the unicellular green alga Chlorella heliozoae. The infection with ATCV-1 is lethal for the algae and requires the correct expression of the 860 hypothetical virus genes. These genes are divided into early, early/late and late genes which are expressed at different times, depending on their protein function. Gene expression is regulated by their corresponding viral promoters and can be controlled by viral or host-specific transcription factors. The stability of proteins is regulated by the host’s ubiquitin system. This study investigated the expression of early viral genes and the ubiquitin- mediated protein degradation regulated by ATCV-1. By investigating the promoters of the early genes of ATCV-1 Z174L, Z765R and Z798L respectively, consensus sequences were identified including a Hex motif and a TATA box that can be bound by viral, but most importanly, host transcription factors. By in vivo interactions with G-box binding factors, a direct regulation of the early promoters, including aforementioned Hex motif, could be demonstrated. Along with this new regulatory mechanism for the expression of early viral genes, evidence for additional mechanisms for the regulation of early genes with different consensus sequences, such as AATGACA, were found. In the second part of this study, three novel viral proteins were identified as proteins of the ubiquitin system: a viral ubiquitin (Z203L), a viral RING E3 ligase (Z292L) and a viral SKP1 protein (Z339L). Experiments have shown that ATCV-1 is able to interfere with the host’s ubiquitin system using these proteins. Although the E3 ligases are responsible for the specific ubiquitination of the target proteins (e.g. Z292L in the case of enolase), the additional expression of a viral ubiquitin ensures a sufficient amount of the signal protein is present. The results of this study demonstrate a wide range of host-virus interactions at the level of gene regulation and protein degradation. ATCV-1 can use host factors to initiate its own gene expression and, with the help of the components of the ubiquitin system encoded in the viral genome, reprogram the host’s protein degradation.

Browsing by Subject "Genexpression"

Results Per Page

Sort Options