Synthesis and cytotoxic activities of estrone and estradiol cis-dichloroplatinum(II) complexes

Sixteen platinum(II) complexes of estrone and estradiol were synthesized in this work to evaluate their cytotoxic activity against several cancer cell lines including estrogen dependent and independent ones. The synthesis of all the complexes was done in three steps. The reaction of steroids with dibromoalkanes was followed by a reaction of the bromoalkyl steroids with 2-(aminomethyl)pyridine or 2-(2-aminoethyl)pyridine. The last step was a reaction of steroidal diamino ligands with potassium tetrachloroplatinate to obtain the desired platinum(II) complexes. Cytotoxicity assays showed that most of the complexes prepared are active against the cancer cell lines used—CEM, U-2 OS, MCF7, MCF7 AL, MDA-MB-468, BT-474, BT-549, and BJ fibroblasts. The six-membered platinum complexes are more active than five-membered ones.     

Genotoxicity of 7H-dibenzo[c,g]carbazole and its methyl derivatives in human keratinocytes

Differences between tissues in the expression of drug-metabolizing enzymes may substantially contribute to tissue-specificity of chemical carcinogens. To verify this hypothesis, the spontaneously immortalized human keratinocytes HaCaT were used, in order to evaluate the genotoxic potential of 7H-dibenzo[c,g]carbazole (DBC), a known hepatocarcinogen and sarcomagen, and its synthetic tissue-specific derivatives, 5,9-dimethyl-DBC (DiMeDBC) and N-methyl-DBC (N-MeDBC), which manifest specific tropism to the liver and skin, respectively. HaCaT cells mainly express cytochrome P4501A1 (CYP1A1), which is involved in metabolism of DBC and N-MeDBC, but not DiMeDBC [10]. Both DBC and the sarcomagen N-MeDBC induced significant levels of DNA strand-breaks, micronuclei, and DNA adducts followed by the phosphorylation of the p53 protein and histone H2AX in HaCaT cells. In contrast, the specific hepatocarcinogen DiMeDBC was devoid of any significant genotoxic activity in this cell line. Our study demonstrates that the absence of drug-metabolizing enzyme(s) involved in DiMeDBC metabolism may contribute substantially to the tissue-specific genotoxicity of this hepatocarcinogen.     

Protein homeostasis and aging: role of ubiquitin protein ligases

Protein homeostasis is fundamental in normal cellular function and cell survival. The ubiquitin-proteasome system (UPS) plays a central role in maintaining the protein homeostasis network through selective elimination of misfolded and damaged proteins. Impaired function of UPS is implicated in normal aging process and also in several age-related neurodegenerative disorders that are characterized by increased accumulation oxidatively modified proteins and protein aggregates. Growing literature also indicate the potential role of various ubiquitin protein ligases in the regulation of aging process by enhancing the degradation of either central lifespan regulators or abnormally folded and damaged proteins. This review mainly focuses on our current understanding of the importance of UPS function in the regulation of normal aging process.     

Effects of different ectomycorrhizal fungi on somatic embryogenesis of <Emphasis Type="Italic">Abies cephalonica</Emphasis> Loud

The effects of ectomycorrhizal (ECM) fungi, including Laccaria bicolor (Maire) Orton, Laccaria laccata (Scop., Fr.) Berk. and Br., along with two strains of Pisolithus tinctorius (Pers.) Coker and Couch, on the proliferation and subsequent maturation of two embryogenic cell lines of Abies cephalonica Loud., designated lines 6 and 8, were investigated. In the presence of these ECM fungi, the proliferation of both embryogenic cell lines was inhibited. L. bicolor and P. tinctorius strain 2 resulted in the highest inhibition rates. On the other hand, cultivation of embryogenic cultures along with ECM fungi, termed a dual culture, increased radial growth of both P. tinctorius strains; whereas, L. bicolor and L. laccata did not grow as well in the presence of embryogenic cell masses. The dual culture during the proliferation period of embryogenic cells, however, enhanced the subsequent embryo formation and maturation of A. cephalonica; i.e. the capability of embryogenic cell lines to form somatic embryos as well as increasing the mean number of somatic embryos per 1 g fresh weight of embryogenic cell mass. However, levels of responses were highly dependent on the interaction between the specific embryogenic cell line and fungal strain.     

Proteins of higher fungi--from forest to application

Mushrooms are rapidly becoming recognized as a promising source of novel proteins. Several proteins showing unique features have been isolated, including lectins, lignocellulolytic enzymes, protease inhibitors and hydrophobins. They can offer solutions to several medical and biotechnological problems such as microbial drug resistance, low crop yields, and demands for renewable energy. Large-scale production and industrial application of some fungal proteins proves their biotechnological potential and establishes higher fungi as a valuable, although relatively unexplored, source of unique proteins. This review provides the first comprehensive overview of known proteins from mushrooms, describes the process of acquiring a new bioactive protein, and provides an overview of current and anticipated applications of these proteins across biotechnology, medicine and agriculture.     

Surprising spectra of root-associated fungi in submerged aquatic plants

Similarly to plants from terrestrial ecosystems, aquatic species harbour wide spectra of root-associated fungi (RAF). However, comparably less is known about fungal diversity in submerged roots. We assessed the incidence and diversity of RAF in submerged aquatic plants using microscopy, culture-dependent and culture-independent techniques. We studied RAF of five submerged isoetid species collected in four oligotrophic freshwater lakes in Norway. Levels of dark septate endophytes (DSE) colonization differed among the lakes and were positively related to the organic matter content and negatively related to pH. In total, we identified 41 fungal OTUs using culture-dependent and culture-independent techniques, belonging to Mucoromycotina, Chytridiomycota, Glomeromycota, Ascomycota as well as Basidiomycota. Sequences corresponding to aquatic hyphomycetes (e.g. Nectria lugdunensis, Tetracladium furcatum and Varicosporium elodeae) were obtained. Eight arbuscular mycorrhizal taxa belonging to the orders Archaeosporales, Diversisporales and Glomerales were also detected. However, the vast majority of the fungal species detected (e.g. Ceratobasidium sp., Cryptosporiopsis rhizophila, Leptodontidium orchidicola, and Tuber sp.) have previously been known only from roots of terrestrial plants. The abundance and phylogenetic distribution of mycorrhizal as well as nonmycorrhizal fungi in the roots of submerged plants have reshaped our views on the fungal diversity in aquatic environment.     

Teratology on the crossroads: historical aspects and modern approaches

Teratology is the science of congenital developmental disorders (CDDs), overt or latent defects of the organism resulting from the effect of internal and external factors on developmental processes. In this article the significance and position of present-day teratology is discussed in the context of development of this branch of science and related disciplines. The authors present an updated overview of the most important milestones and stages of the development of teratology. Based on the analysis of the historical development of theses and theories that represent a decisive contribution to this field, we present a survey of the fundamental principles of experimental and clinical teratology. The aim of observing these principles is to get insight into developmental relations and to understand mechanisms of action on the level of cell populations (elementary morphogenetic processes), tissues and organs. It is important to realize that any negative intervention into the normal course of these processes, either on genetic or non-genetic basis, inevitably leads to a sequence of subsequent changes resulting in the development of congenital developmental disorders. Despite modern approaches of molecular biology and genetics, along with top diagnostic techniques, we are still not able to identify the actual cause in more than 50% of all congenital defects. One-half of the unidentified cases are referred to as "multifactorial", a term that is rather ambiguous. It either means that some of the basic principles of teratogenesis still escape our attention, or the interpretation of some of the well known principles might be misleading. A third possibility is rather pessimistic. The development of the individual is so sophisticated and dependent on a delicate network of a multitude of factors mutually affecting each other that it is extremely prone to give rise to a plethora of spontaneous errors which are unpredictable and impossible to prevent. Nevertheless, the long and complicated history of scientific endeavour has yielded considerable present-day knowledge on causes and mechanisms of CDDs, a history whose beginnings date back to antiquity.     

Cwc2 and its human homologue RBM22 promote an active conformation of the spliceosome catalytic centre

RNA-structural elements play key roles in pre-mRNA splicing catalysis; yet, the formation of catalytically competent RNA structures requires the assistance of spliceosomal proteins. We show that the S. cerevisiae Cwc2 protein functions prior to step 1 of splicing, and it is not required for the Prp2-mediated spliceosome remodelling that generates the catalytically active B complex, suggesting that Cwc2 plays a more sophisticated role in the generation of a functional catalytic centre. In active spliceosomes, Cwc2 contacts catalytically important RNA elements, including the U6 internal stem-loop (ISL), and regions of U6 and the pre-mRNA intron near the 5' splice site, placing Cwc2 at/near the spliceosome's catalytic centre. These interactions are evolutionarily conserved, as shown by studies with Cwc2's human counterpart RBM22, indicating that Cwc2/RBM22-RNA contacts are functionally important. We propose that Cwc2 induces an active conformation of the spliceosome's catalytic RNA elements. Thus, the function of RNA-RNA tertiary interactions within group II introns, namely to induce an active conformation of domain V, may be fulfilled by proteins that contact the functionally analogous U6-ISL, within the spliceosome.