A system for screening natural immunosuppressors

Criteria for directed screening of antibiotics with immunosuppressive action were defined. The first stage included screening of cultures producing antiaspergillous antibiotics. At the second stage, the antibiotics whose antifungal activity decreases in the presence of insulin (at the background of calcium salts) and erythromycin and increases in the presence of verapamil were selected. The screening of antibiotic-producing cultures among 123 strains of mycelial fungi and 181 strains of actinomycetes resulted in isolation of 3 fungal cultures and 2 actinomycetes which produced antibiotics corresponding to cyclosporine A as evidenced by thin-layer and high performance liquid chromatographies.     

Effect of cyclosporin on tumor xenotransplantation under the renal capsule in mice

Stimulating effect of cyclosporine on growth and invasiveness of tumor xenographts was studied on a model of rat solid sarcoma M-1 transplanted under the kidney capsule in mice. Cyclosporine was administered subcutaneously in a dose of 25 or 75 mg/kg on days 1-7. The stimulating effect of cyclosporine was directly associated with the immunodepressant dose and accompanied by a decrease in the thymus weight. With using cyclosporine the model of xenographts under the kidney capsule can be of value in screening cytostatics and immunomodulators.     

Ca2+ Regulates Reactive Oxygen Species Production and pH during Mechanosensing in Arabidopsis Roots

Mechanical stimulation of plants triggers a cytoplasmic Ca²⁺ increase that is thought to link the touch stimulus to appropriate growth responses. We found that in roots of Arabidopsis thaliana, external and endogenously generated mechanical forces consistently trigger rapid and transient increases in cytosolic Ca²⁺ and that the signatures of these Ca²⁺ transients are stimulus specific. Mechanical stimulation likewise elicited an apoplastic alkalinization and cytoplasmic acidification as well as apoplastic reactive oxygen species (ROS) production. These responses showed the same kinetics as mechanically induced Ca²⁺ transients and could be elicited in the absence of a mechanical stimulus by artificially increasing Ca²⁺ concentrations. Both pH changes and ROS production were inhibited by pretreatment with a Ca²⁺ channel blocker, which also inhibited mechanically induced elevations in cytosolic Ca²⁺. In trichoblasts of the Arabidopsis root hair defective2 mutant, which lacks a functional NADPH oxidase RBOH C, touch stimulation still triggered pH changes but not the local increase in ROS production seen in wild-type plants. Thus, mechanical stimulation likely elicits Ca²⁺-dependent activation of RBOH C, resulting in ROS production to the cell wall. This ROS production appears to be coordinated with intra- and extracellular pH changes through the same mechanically induced cytosolic Ca²⁺ transient.     

A Sec14p-nodulin domain phosphatidylinositol transfer protein polarizes membrane growth of Arabidopsis thaliana root hairs

Phosphatidylinositol (PtdIns) transfer proteins (PITPs) regulate signaling interfaces between lipid metabolism and membrane trafficking. Herein, we demonstrate that AtSfh1p, a member of a large and uncharacterized Arabidopsis thaliana Sec14p-nodulin domain family, is a PITP that regulates a specific stage in root hair development. AtSfh1p localizes along the root hair plasma membrane and is enriched in discrete plasma membrane domains and in the root hair tip cytoplasm. This localization pattern recapitulates that visualized for PtdIns(4,5)P2 in developing root hairs. Gene ablation experiments show AtSfh1p nullizygosity compromises polarized root hair expansion in a manner that coincides with loss of tip-directed PtdIns(4,5)P2, dispersal of secretory vesicles from the tip cytoplasm, loss of the tip f-actin network, and manifest disorganization of the root hair microtubule cytoskeleton. Derangement of tip-directed Ca2+ gradients is also apparent and results from isotropic influx of Ca2+ from the extracellular milieu. We propose AtSfh1p regulates intracellular and plasma membrane phosphoinositide polarity landmarks that focus membrane trafficking, Ca2+ signaling, and cytoskeleton functions to the growing root hair apex. We further suggest that Sec14p-nodulin domain proteins represent a family of regulators of polarized membrane growth in plants.     

TP53 mutations,tetraploidy and homologous recombination repair defects in early stage high-grade serous ovarian cancer

To determine early somatic changes in high-grade serous ovarian cancer (HGSOC), we performed whole genome sequencing on a rare collection of 16 low stage HGSOCs. The majority showed extensive structural alterations (one had an ultramutated profile), exhibited high levels of p53 immunoreactivity, and harboured a TP53 mutation, deletion or inactivation. BRCA1 and BRCA2 mutations were observed in two tumors, with nine showing evidence of a homologous recombination (HR) defect. Combined Analysis with The Cancer Genome Atlas (TCGA) indicated that low and late stage HGSOCs have similar mutation and copy number profiles. We also found evidence that deleterious TP53 mutations are the earliest events, followed by deletions or loss of heterozygosity (LOH) of chromosomes carrying TP53, BRCA1 or BRCA2. Inactivation of HR appears to be an early event, as 62.5% of tumours showed a LOH pattern suggestive of HR defects. Three tumours with the highest ploidy had little genome-wide LOH, yet one of these had a homozygous somatic frame-shift BRCA2 mutation, suggesting that some carcinomas begin as tetraploid then descend into diploidy accompanied by genome-wide LOH. Lastly, we found evidence that structural variants (SV) cluster in HGSOC, but are absent in one ultramutated tumor, providing insights into the pathogenesis of low stage HGSOC.     

Primary cell cultures of leukosis P-388 as a possible model for the screening of antitumor substances]

A substrain of the ascitic leucosis P-388 was obtained as a result of interchanging passages of P-388 leucosis cells in the primary cultures and abdominal cavity of mice. The tumor cells of the ascitic leucosis P-388 multiplied in the primary suspended culutres as well as in vivo. The substrain lost its hemorrhagic properties. The content of DNA and RNA in the primary cultures of P-388 doubled every 16-18 hours and the number of the cells doubled every 24-26 hours. The cells of the adapted substrain of P-388 grew also in the semiliquid agarized medium forming compact colonies by the 4th-5th day of cultivation. The primary suspended cultures of P-388 were highly sensitive to cytostatics and in particular to vinblastin and kolchamine (alkaloids). In this connection they were recommended for prescreening antitumor compounds.