Dessislava Staneva - Academia.edu (original) (raw)

Papers by Dessislava Staneva

Nanomaterials

Central focus in modern anticancer nanosystems is given to certain types of nanomaterials such as... more Central focus in modern anticancer nanosystems is given to certain types of nanomaterials such as graphene oxide (GO). Its functionalization with polyethylene glycol (PEG) demonstrates high delivery efficiency and controllable release of proteins, bioimaging agents, chemotherapeutics and anticancer drugs. GO–PEG has a good biological safety profile, exhibits high NIR absorbance and capacity in photothermal treatment. To investigate the bioactivity of PEGylated GO NPs in combination with NIR irradiation on colorectal cancer cells we conducted experiments that aim to reveal the molecular mechanisms of action of this nanocarrier, combined with near-infrared light (NIR) on the high invasive Colon26 and the low invasive HT29 colon cancer cell lines. During reaching cancer cells the phototoxicity of GO–PEG is modulated by NIR laser irradiation. We observed that PEGylation of GO nanoparticles has well-pronounced biocompatibility toward colorectal carcinoma cells, besides their different ma...

Mechanisms of ageing and development, Jan 17, 2018

Linker histones are major players in chromatin organization and per se are essential players in g... more Linker histones are major players in chromatin organization and per se are essential players in genome homeostasis. As the fifth class of histone proteins the linker histones not only interact with DNA and core histones but also with other chromatin proteins. These interactions prove to be essential for the higher levels of chromatin organization like chromatin loops, transcription factories and chromosome territories. Our recent results have proved that Saccharomyces cerevisiae linker histone - Hho1p, physically interacts with the actin-related protein 4 (Arp4) and that the abrogation of this interaction through the deletion of the gene for the linker histone in arp4 mutant cells leads to global changes in chromatin compaction. Here, we show that the healthy interaction between the yeast linker histone and Arp4p is critical for maintaining genome stability and for controlling cellular sensitivity to different types of stress. The abolished interaction between the linker histone and...

Background: Chromatin structure is an ambiguous player in the processes of cellular transformatio... more Background: Chromatin structure is an ambiguous player in the processes of cellular transformation and cancer propagation. Complex interactions exist among histones and chromatin modifying complexes. Any aberrations in these functional networks would potentially lead to chromatin rearrangements and changes in gene expression. An excellent model for chromatin structure and dynamics studies has always been the yeast - Saccharomyces cerevisiae. Our particular interests are set on Arp4 - an abundant yeast nuclear protein which is essential part of several chromatin remodeling complexes and Hho1p - the yeast linker histone. Methods: Gene cloning techniques led to development of double arp4 deltahho1 mutant yeast cells. Studies of cell growth have been performed under different stress conditions. The chromatin structure of the double mutant cells was studied by biochemical. The Yeast two hybrid system revealed the physical interactions among both proteins of interest. Results: The obtaine...

In all eukaryotic cells nuclear DNA is organized in a highly-ordered nucleoprotein complex called... more In all eukaryotic cells nuclear DNA is organized in a highly-ordered nucleoprotein complex called chromatin. Along with DNA, essential structural and functional components of chromatin are histone proteins: core histones and linker histones. The latter are involved in both the maintenance of higher chromatin structures and together with core histones in regulation of gene expression. It has to be mentioned, however, that both functions of linker histones are more presumed than proved and therefore are subject of disputes. The aim of the current research is to go in more details of the functions of linker histones. We have explored the yeast Kluyveromyces lactis as a model organism. In silico analysis revealed a single open reading frame (ORF) in K. lactis genome, with homology (around 48%) to linker histone genes of different organisms. The predicted amino acid sequence of the putative K. lactis H1 protein (KlH1p) showed 40% identity. Interestingly, an expression of mRNA from the gene was not detected. Knockout of KlH1 gene has not shown great impact on the cellular viability. In order to answer whether KlH1 is a true gene coding for a linker histone or it is a pseudogene several phenotypic features of KlH1 knockout cells were examined. Based on the obtained results we determined the significance of KlH1 for K. lactis.

Kluyveromyces lactis, also known as dairy yeast, has numerous applications in scientific research... more Kluyveromyces lactis, also known as dairy yeast, has numerous applications in scientific research and practice. It has been approved as a GRAS (Generally Recognized As Safe) organism, a probiotic, a biotechnological producer of important enzymes at industrial scale and a bioremediator of waste water from the dairy industry. Despite these important practical applications the sensitivity of this organism to genotoxic substances has not yet been assessed. In order to evaluate the response of K. lactis cells to genotoxic agents we have applied several compounds with well-known cyto- and genotoxic activity. The method of comet assay (CA) widely used for the assessment of DNA damages is presented here with new special modifications appropriate for K. lactis cells. The comparison of the response of K. lactis to genotoxins with that of Saccharomyces cerevisiae showed that both yeasts, although considered close relatives, exhibit species-specific sensitivity toward the genotoxins examined.

Epigenetics, the Environment, and Children’s Health Across Lifespans, 2016

Folia Microbiol Prague, 2007

A novel finding that genomic restriction fragments of symbiotic nitrogen fixer S. meliloti hybrid... more A novel finding that genomic restriction fragments of symbiotic nitrogen fixer S. meliloti hybridized with nifM gene probe of the free-living diazotroph Klebsiella pneumoniae is reported. When SmaI endonuclease was used to digest S. meliloti DNA, a unique hybridizing band was obtained.

FEMS Yeast Research, 2016

Linker histones are essential components of chromatin in eukaryotes. Through interactions with li... more Linker histones are essential components of chromatin in eukaryotes. Through interactions with linker DNA and nucleosomes they facilitate folding and maintenance of higher-order chromatin structures and thus delicately modulate gene activity. The necessity of linker histones in lower eukaryotes appears controversial and dubious. Genomic data have shown that Schizosaccharomyces pombe does not possess genes encoding linker histones while Kluyveromyces lactis has been reported to have a pseudogene. Regarding this controversy, we have provided the first direct experimental evidence for the existence of a functional linker histone gene, KlLH1, in K. lactis genome. Sequencing of KlLH1 from both genomic DNA and copy DNA confirmed the presence of an intact open reading frame. Transcription and splicing of the KlLH1 sequence as well as translation of its mRNA have been studied. In silico analysis revealed homology of KlLH1p to the histone H1/H5 protein family with predicted three domain structure characteristic for the linker histones of higher eukaryotes. This strongly proves that the yeast K. lactis does indeed possess a functional linker histone gene thus entailing the evolutionary preservation and significance of linker histones. The nucleotide sequences of KlLH1 are deposited in the GenBank under accession numbers KT826576, KT826577 and KT826578.

Isolation of Kluyveromyces lactis PSA1 gene was attempted using three different approaches, the s... more Isolation of Kluyveromyces lactis PSA1 gene was attempted using three different approaches, the successful one being complementation. A genomic clone of about 2.8 kb, containing the putative KlPSA1 gene, complemented the hypoosmotic instability of Saccharomyces cerevisiae srb1 mutant. Sequencing of the isolated genomic fragment revealed that it contains an ORF of 1083 bp, with 84% homology to ScPSA1 gene coding for a predicted polypeptide, Kl Psa1p, of 361 amino acids. Kl Psa1p showed high homology to yeasts’ GDP-mannose pyrophosphorylases. The nucleotide sequence of KlPSA1 has been deposited in the EMBL data bank under accession No. AJ551274.

Folia biologica

Malignant gliomas are the most common type of primary malignant brain tumours, characterized by e... more Malignant gliomas are the most common type of primary malignant brain tumours, characterized by extreme proliferation and aggressive invasion. There is evidence for over-expression of the YKL40 gene in high-grade gliomas. The high serum levels of the glycoprotein are associated with poor prognosis of various inflammatory and tumour processes. We investigated the YKL40 mRNA level and protein expression in the tumour site and in the serum of high-grade glioma patients. The YKL-40 expression in 36 patients with glial tumours (astrocytoma grade III, glioblastoma) and 33 age-matched healthy persons was measured by gene analysis, immunohistochemistry and ELISA. YKL-40 serum levels in high-grade glioma patients compared to healthy subjects were significantly increased (P <= 0.05). A wide range of variability in YKL40 mRNA expression was found. YKL-40 staining in situ was more abundant in glioblastoma tissue than in anaplastic astrocytoma, with the lowest level in normal brain tissue. Ou...

Biotechnology & Biotechnological Equipment, 2010

The information about the authenticity of newly or already established animal cell cultures is es... more The information about the authenticity of newly or already established animal cell cultures is essential. By using DNA analysis six cell lines has been investigated: ЗТЗ, HeLa, McCoy, HЕp-2, McCoy-Plovdiv and HEp-2-Plovdiv E. For the last four was made cytogenetic analysis confirmed that serum-free cell strains McCoy-Plovdiv and HЕp-2-Plovdiv E are originally derived from McCoy and HЕp-2 cell lines. PCR -analysis demonstrated that 3T3 cells are mouse originally, HeLa, HЕp-2 and HЕp-2-Plovdiv E are with the human origin and McCoy and McCoy-Plovdiv are hybrid cells carrying mouse and human genes in their genome.

The International Journal of Biochemistry & Cell Biology, 2015

Actin-related protein 4 (Arp4p) Chromatin higher-order chromatin structure Chromatin remodeling a... more Actin-related protein 4 (Arp4p) Chromatin higher-order chromatin structure Chromatin remodeling a b s t r a c t Chromatin structure promotes important epigenetic mechanisms that regulate cellular fate by organizing, preserving and controlling the way by which the genetic information works. Our understanding of chromatin and its functions is sparse and not yet well defined. The uncertainty comes from the complexity of chromatin and is induced by the existence of a large number of nuclear proteins that influence it. The intricate interaction among all these structural and functional nuclear proteins has been under extensive study in the recent years. Here, we show that Saccharomyces cerevisiae linker histone physically interacts with Arp4p (actin-related protein 4) which is a key subunit of three chromatin modifying complexes -INO80, SWR1 and NuA4. A single -point mutation in the actin -fold domain of Arp4p together with the knock-out of the gene for the linker histone in S. cerevisiae severely abrogates cellular and nuclear morphology and leads to complete disorganizing of the higher levels of chromatin organization. (G. Miloshev). of this histone in chromatin and propose future studies in order the exact molecular mechanisms underlying its functions to be fully understood.

Yeast, 2004

Phosphomannomutase (PMM) is a key enzyme, which catalyses one of the first steps in the glycosyla... more Phosphomannomutase (PMM) is a key enzyme, which catalyses one of the first steps in the glycosylation pathway, the conversion of D-mannose-6-phosphate to D-mannose-1-phosphate. The latter is the substrate for the synthesis of GDP-mannose, which serves as the mannosyl donor for the glycosylation reactions in eukaryotic cells. In the yeast Saccharomyces cerevisiae PMM is encoded by the gene SEC53 (ScSEC53) and the deficiency of PMM activity leads to severe defects in both protein glycosylation and secretion. We report here on the isolation of the Kluyveromyces lactis SEC53 (KlSEC53) gene from a genomic library by virtue of its ability to complement a Saccharomyces cerevisiae sec53 mutation. The sequenced DNA fragment contained an open reading frame of 765 bp, coding for a predicted polypeptide, KlSec53p, of 254 amino acids. The KlSec53p displays a high degree of homology with phosphomannomutases from other yeast species, protozoans, plants and humans. Our results have demonstrated that KlSEC53 is the functional homologue of the ScSEC53 gene. Like ScSEC53, the KlSEC53 gene is essential for K. lactis cell viability. Phenotypic analysis of a K. lactis strain overexpressing the KlSEC53 gene revealed defects expected for impaired cell wall integrity.

Folia Microbiologica, 2008

A 3.85-kb genomic fragment containing the KlPCL1 gene, with an open reading frame (ORF) of 1359 b... more A 3.85-kb genomic fragment containing the KlPCL1 gene, with an open reading frame (ORF) of 1359 bp, was isolated from Kluyveromyces lactis genomic library by heterologous colony hybridization using the Saccharomyces cerevisiae PRC1 (ScPRC1) gene as a probe. The KlPCL1 nucleotide sequence was identical to the KLLAOC17490g ORF of K. lactis and showed >55 % identity with S. cerevisiae YBR139w and PRC1 genes encoding carboxypeptidases. The deduced KlPcl1p amino acid sequence displayed strong similarities to yeast and higher eukaryotic carboxypeptidases. In silico analyses revealed that KlPcl1p contained several highly conserved regions characteristic of the serine-type carboxypeptidases, such as the catalytic triad in the active site and the LNGGPGCSS, FHIAGESYAGHYIP and ICNWLGN motifs involved in the substrate binding. All this suggests that the KlPCL1 gene product belongs to the serine carboxypeptidase family. Sporulation and ascus dissection of a diploid strain heterozygous for single-copy disruption of KlPCL1 revealed that this gene is not essential in K. lactis. Further analyses of haploid and diploid deletion mutants demonstrated that disruption of the KlPCL1 gene neither impaired sporulation nor affected growth abilities of K. lactis cells under a variety of physiological conditions, e.g., growth on different carbon sources, at various temperatures or pH of the medium, and under nitrogen depletion. Abbreviations CPY carboxypeptidase Y PCR polymerase chain reaction G418 geneticin PRC proteinase C Kl Kluyveromyces lactis SM synthetic medium ME malt extract (medium) Sc Saccharomces cerevisiae MM minimal medium YP yeast extract-peptone ORF open reading frame YPD yeast extract-peptone-dextrose PCL proteinase C-like 326 D. STANEVA et al. Vol. 53

Folia Microbiologica, 2007

FEMS Yeast Research, 2005

GDP-mannose is the mannosyl donor for the glycosylation reactions and is synthesized by GDP-manno... more GDP-mannose is the mannosyl donor for the glycosylation reactions and is synthesized by GDP-mannose pyrophosphorylase from GTP and D-mannose-1-phosphate; in Saccharomyces cerevisiae this enzyme is encoded by the PSA1/VIG9/SRB1 gene.

Biotechnology & Biotechnological Equipment, 2012

ABSTRACT Certain evidence has been collected about the imperative role of chromatin remodeling co... more ABSTRACT Certain evidence has been collected about the imperative role of chromatin remodeling complexes (CRCs) in the fine tuning of genome activity. One of the most abundant CRCs is INO80 which is evolutionary conserved from yeast to human. INO80 consists of several subunits, all of them playing important roles in its functioning. The actin-related protein -Arp4p, is one of these subunits. Although ARP4 gene is essential for the yeast cells certain arp4 mutants do exist, thus providing good opportunities for studying of INO80 roles in the higher-order building of chromatin. Using the advantages of S. cerevisiae we have traced the interaction between Arp4p and linker histones.