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Effect of nuclear matrix attachment regions on transgene expression in tobacco plants.

100%

Nowak W., Gawłowska0 M., Jarmołowski A., Augustyniak J.

Acta Biochimica Polonica

2001

vol. 48

issue 3

637-646

Matrix attachment regions (MARs) are thought to participate in the organization and segregation of independent chromosomal loop domains. Although there are several reports on the action of natural MARs in the context of heterologous genes in transgenic plants, in our study we tested a synthetic MAR (sMAR) with the special property of unpairing when under superhelical strain, for its effect on reporter gene expression in tobacco plants. The synthetic MAR was a multimer of a short sequence from the MAR 3' end of the immunoglobulin heavy chain (IgH) enhancer. This sMAR sequence was used to flank the β-glucuronidase (GUS) reporter gene within the T-DNA of the binary vector pBI121. Vectors with or without the sMARs were then used to transform tobacco plants by Agrobacterium tumefaciens. Transgenic plants containing the sMAR sequences flanking the GUS gene exhibited higher levels of transgene expression compared with transgenic plants which lacked the sMARs. This effect was observed independently of the position of the sMAR at the 5' side of the reporter gene. However, variation of the detected transgene expression was significant in all transformed plant populations, irrespective of the construct used. Most genes whose expression has been studied in transgenic plants are generally expressed in appropriate patterns. However, transgene expression can vary within an extremely wide range, often showing only a very low level [1, 2]. Variation in transgene expression is frequently attributed to corresponding variation in the transcription potential of different chromosomal insertion sites. DNA sequences called scaffold/matrix attachment regions (S/MARs) are involved in the structural and functional organization of all eukaryotic genomes. Evolutionarily, the structures of these sequences seem to be conserved. Typically, S/MARs are located every 5 to 200 kb of sequence and are known to bind specifically to components of the nuclear scaffold, therefore suggesting that they are responsible for loop domain base formation [3, 4].Of the MAR elements reported, many do not display extensive sequence homology. It is therefore reasonable to assume that the scaffold probably recognizes some structural features of the MAR DNA rather than a specific sequence [5].MARs appear to be functionally conserved, since animal MARs can bind to plant nuclear scaffolds and vice versa [6, 7].Most MARs have been generally characterized as AT-rich sequences. However, AT-richness per se is not a sufficient criterion for specific sequence recognition of MARs by specific binding proteins [7]. Their capacity to bind to the nuclear matrix is determined by the specific structure of DNA. A prominent structural characteristic of different MARs is their strong potential for extensive unpairing when subjected to superhelical strain [8, 9]. The ability to assume a stably unpaired conformation has been described for several MARs. For example, within the MAR 3' end of immunoglobulin heavy chain (IgH) enhancer there is an AATATATTT motif that is a nucleation site for DNA unwinding [10]. Concatamerized oligonucleotides containing seven repeats of this sequence exhibited a strong affinity for the nuclear scaffold and increased SV40 promoter activity in stably transformed mouse cells [11].In this paper we present results of our studies that concern the effect of a synthetic MAR on transgene expression in tobacco plants. The synthetic MAR sequences were used to flank the β-glucuronidase (GUS) gene whose transcription was under control of the 35S CaMV promoter in the binary vector pBI121. This construct was introduced into tobacco plants and the GUS reporter gene expression was monitored in stably transformed plants.

Adult stem cells: hopes and hypes of regenerative medicine

88%

Dulak J., Szade K., Szade A., Nowak W., Józkowicz A.

issue 3

329-337

Stem cells are self-renewing cells that can differentiate into specialized cell type(s). Pluripotent stem cells, i.e. embryonic stem cells (ESC) or induced pluripotent stem cells (iPSC) differentiate into cells of all three embryonic lineages. Multipotent stem cells, like hematopoietic stem cells (HSC), can develop into multiple specialized cells in a specific tissue. Unipotent cells differentiate only into one cell type, like e.g. satellite cells of skeletal muscle. There are many examples of successful clinical applications of stem cells. Over million patients worldwide have benefited from bone marrow transplantations performed for treatment of leukemias, anemias or immunodeficiencies. Skin stem cells are used to heal severe burns, while limbal stem cells can regenerate the damaged cornea. Pluripotent stem cells, especially the patient-specific iPSC, have a tremendous therapeutic potential, but their clinical application will require overcoming numerous drawbacks. Therefore, the use of adult stem cells, which are multipotent or unipotent, can be at present a more achievable strategy. Noteworthy, some studies ascribed particular adult stem cells as pluripotent. However, despite efforts, the postulated pluripotency of such events like "spore-like cells", "very small embryonic-like stem cells" or "multipotent adult progenitor cells" have not been confirmed in stringent independent studies. Also plasticity of the bone marrow-derived cells which were suggested to differentiate e.g. into cardiomyocytes, has not been positively verified, and their therapeutic effect, if observed, results rather from the paracrine activity. Here we discuss the examples of recent studies on adult stem cells in the light of current understanding of stem cell biology.

The relationship between CA repeat polymorphism of the IGF-1 gene and the structure of motor skills in young athletes

88%

Karpowicz K., Krych K., Karpowicz M., Nowak W., Gronek P.

Acta Biochimica Polonica

2018

vol. 65

issue 1

43-50

The map of candidate genes that can potentially affect physical fitness becomes larger every year, and they are associated with such aspects as respiratory and cardiovascular stability; body build and composition - especially muscle mass and strength; carbohydrate and lipid metabolism; response to training; and exercise intolerance.The aim of this study was to analyze the relationship between the CA repeat polymorphism of the P1 promoter of the IGF1 gene and the structure of motor skills in the two groups of Polish young athletes in 2007-2009. In this study, 350 young sportsmen representing different sports disciplines were examined (age = 15.5 ± 0.5 years), by genotyping the IGF1 gene and determining the structure of motor skills using the International Physical Fitness Test (IPFT) battery. The multiple stepwise regression was used to determine the impact of the investigated motor skills on the indicator of the overall physical fitness, measured by the total score of the International Physical Fitness Test (IPFT). The analysis showed some regularity related to the character of the IGF1 gene polymorphism. It can be concluded that the two groups of young boys athletes practicing various sports disciplines (kinds of physical exercise) displayed similar associations between CA repeat polymorphism of the P1 promoter of the IGF1 gene and the level of motor effects. Our results suggest that this polymorphism may be a genetic marker of the physical performance phenotype. We demonstrated that CA repeat polymorphism of the P1 promoter of the IGF1 gene was associated with strength predispositions in the homozygous and non-carriers groups. In the group who were heterozygous it was speed-strength aptitudes.

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Search results

Effect of nuclear matrix attachment regions on transgene expression in tobacco plants.

Adult stem cells: hopes and hypes of regenerative medicine

The relationship between CA repeat polymorphism of the IGF-1 gene and the structure of motor skills in young athletes