The Effect of Temperature on the Lipid Composition of the Green Alga Botryococcus

The lipid composition of the green alga Botryococcus was studied at three different cultivation temperatures: suboptimal (18°C), optimal (25°C), and supraoptimal (32°C). Cultivation at the supraoptimal temperature was found to considerably inhibit the synthesis of nearly all intracellular lipids, except for triacylglycerides, and to influence their fatty acid composition. In particular, the content of trienoic fatty acids was significantly lower at the supraoptimal than at the optimal cultivation temperature. At the same time, the fatty acid composition of the extracellular lipids of the alga virtually did not depend on cultivation temperature.     

IFN-gamma regulation of vacuolar pH, cathepsin D processing and autophagy in mammary epithelial cells

In this study we examined the ability of interferon-gamma (IFN-gamma) to regulate mammary epithelial cell growth and gene expression, with particular emphasis on two genes: Maspin (a member of serine protease inhibitor superfamily), and the lysosomal aspartyl endopeptidase cathepsin D (CatD). The protein products of these genes are critically involved in regulation of multitude of biological functions in different stages of mammary tissue development and remodeling. In addition, the expression of Maspin is down-regulated in primary breast cancer and is lost in metastatic disease, while CatD is excessively produced and aberrantly secreted by breast cancer cells. We report that IFN-gamma receptors are expressed in mammary epithelial cells, and receptor engagement by IFN-gamma transduces the IFN-gamma signal via Stat-1 resulting in decreased vacuolar pH. This change in vacuolar pH alters CatD protein processing and secretion concurrent with increased Maspin secretion. In addition, IFN-gamma exerts a suppressive effect on cell growth and proliferation, and induces morphological changes in mammary epithelial cells. Our studies also reveal that breast cancer cells, which are devoid of Maspin, are refractory to IFN-gamma with respect to changes in vacuolar pH and CatD. However, Maspin transfection of breast cancer cells partially sensitizes the cells to IFN-gamma's effect, thus providing new therapeutic implications.     

Cleavage of Histone 3 by Cathepsin D in the Involuting Mammary Gland

The post-lactational regression of mammary gland is a complex multi-step process designed to conserve the biological function of the gland for next pregnancy. This developmental stage is a biological intrigue with great relevance to breast cancer research, and thus has been the subject of intensive scrutiny. Multipronged studies (microarray, proteomics profiling, animal knock-out models) have provided a repertoire of genes critical to involution. However, the caveat of these approaches remains in their failure to reveal post-translational modification(s), an emerging and critical aspect of gene regulation in developmental processes and mammary gland remodeling. The massive surge in the lysosomal enzymes concurrent with the onset of involution has been known for decades, and considered essential for “clearance” purposes. However, functional significance of these enzymes in diverse biological processes distinct from their proteolytic activity is just emerging. Studies from our laboratory had indicated specific post-translational modifications of the aspartyl endopeptidase Cathepsin D (CatD) at distinct stages mammary gland development. This study addresses the biological significance of these modifications in the involution process, and reveals that post-translational modifications drive CatD into the nucleus to cleave Histone 3. The cleavage of Histone 3 has been associated with cellular differentiation and could be critical instigator of involution process. From functional perspective, deregulated expression and increased secretion of CatD are associated with aggressive and metastatic phenotype of breast cancer. Thus unraveling CatD’s physiological functions in mammary gland development will bridge the present gap in understanding its pro-tumorigenic/metastatic functions, and assist in the generation of tailored therapeutic approaches.     

Diet and locomotion of the armadillo Peltephilus: a new view

The Santacrucian armadillos Peltephilus (Mammalia, Dasypodidae, Peltephilinae) are reanalysed in order to test the traditional hypothesis that they were the most cursorial and active hunters of the dasypodids. The masticatory musculature is reconstructed, the form and distribution of teeth are studied, and a model of the jaw movements is proposed. Furthermore, the limb anatomy as well as their index of fossorial ability are compared with those of other armadillos. It is concluded that Peltephilus , and very likely other peltephilines, are poorly designed as carnivorous, actively cursorial mammals. An alternative habit is proposed, in which Peltephilus and the other peltephilines are viewed as having the conservative armadillo structure of diggers, feeding on soft but tough items, probably plant material of underground origin.     

Synthesis of 3-hydroxybutyrate-CO-4-hydroxybutyrate copolymers by hydrogen-oxidizing bacteria

Synthesis of 3- and 4-hydroxybutyrate copolymer (3HB-co-4HB), the most promising member of the biodegradable polyhydroxyalkanoate (PHA) family, has been studied. Cultivation conditions of naturally occurring strains of hydrogen-oxidizing bacteria Ralstonia eutropha B5786 and Cupriavidus eutrophus B10646 have been optimized to ensure efficient synthesis of the 3HB-co-4HB copolymer. A set of highly pure samples of the 3HB-co-4HB copolymer with 4HB content varying from 8.7 to 24.3 mol% has been obtained. Incorporation of 4HB into the copolymer was shown to cause a more pronounced decrease in polymer crystallinity than the incorporation of 3-hydroxyvalerate or 3-hydroxyhexanoate; samples with a degree of crystallinity below 30% have been obtained. The weight average molecular mass of the 3HB-co-4HB copolymers was shown to be independent on the monomer ratio and to vary broadly (from 540 to 1110 kDa).     

Degradation of polyhydroxyalkanoates and the composition of microbial destructors under natural conditions

The degradation dynamics of polyhydroxyalkanoates of different composition has been studied in an eutrophic storage reservoir for two seasons. It has been shown that the biodegradation of polymers under natural conditions depends not only on their structure and physicochemical properties but also, to a great extent, on a complex of weather-climatic conditions affecting the state of the reservoir ecosystem. The molecular genetic analysis of 16S rRNA has revealed bacterial species (clones) probably involved in the degradation of polyhydroxyalkanoates in a model storage reservoir.