G1 cell cycle progression and the expression of G1 cyclins are regulated by PI3K/AKT/mTOR/p70S6K1 signaling in human ovarian cancer cells

Ovarian cancer is one of the most common cancers among women. Recent studies demonstrated that the gene encoding the p110alpha catalytic subunit of phosphatidylinositol 3-kinase (PI3K) is frequently amplified in ovarian cancer cells. PI3K is involved in multiple cellular functions, including proliferation, differentiation, antiapoptosis, tumorigenesis, and angiogenesis. In this study, we demonstrate that the inhibition of PI3K activity by LY-294002 inhibited ovarian cancer cell proliferation and induced G(1) cell cycle arrest. This effect was accompanied by the decreased expression of G(1)-associated proteins, including cyclin D1, cyclin-dependent kinase (CDK) 4, CDC25A, and retinoblastoma phosphorylation at Ser(780), Ser(795), and Ser(807/811). Expression of CDK6 and beta-actin was not affected by LY-294002. Expression of the cyclin kinase inhibitor p16(INK4a) was induced by the PI3K inhibitor, whereas steady-state levels of p21(CIP1/WAF1) were decreased in the same experiment. The inhibition of PI3K activity also inhibited the phosphorylation of AKT and p70S6K1, but not extracellular regulated kinase 1/2. The G(1) cell cycle arrest induced by LY-294002 was restored by the expression of active forms of AKT and p70S6K1 in the cells. Our study shows that PI3K transmits a mitogenic signal through AKT and mammalian target of rapamycin (mTOR) to p70S6K1. The mTOR inhibitor rapamycin had similar inhibitory effects on G(1) cell cycle progression and on the expression of cyclin D1, CDK4, CDC25A, and retinoblastoma phosphorylation. These results indicate that PI3K mediates G(1) progression and cyclin expression through activation of an AKT/mTOR/p70S6K1 signaling pathway in the ovarian cancer cells.     

Infraciliature and myoneme system of Campanella umbellaria (Protozoa, Ciliophora, Peritrichida)

The infraciliature and myoneme system of Campanella umbellaria were revealed using the protargol impregnation technique. The main characteristics of the infraciliature are the peristomial ciliary rows (haplokinety and polykineties), which make four and a half turns around the peristomial disc before plunging into the infundibulum, and the aboral infraciliature, which is made up of the aboral ciliary wreath (trochal band) and the scopula. The myoneme system is composed of: 1) longitudinal fibers, which include 60-84 (mean 72.3) short longitudinal fibers, 40-56 (mean 45.8) medium-length longitudinal fibers, and numerous long longitudinal fibers; and 2) circular fibers, which include 8-12 (mean 9.3) peristomial ring fibers, linking fibers, support fibers, and peristomial disc fibers. The various fibers in C. umbellaria are interconnected to form a single myoneme system that may act as a cell skeleton as well as providing the mechanism by which the zooid contracts and relaxes.     

Signaling from Nucleotide Receptors to Protein Kinase Cascades in Astrocytes

In the CNS, extracellular ATP can function as an excitatory neurotransmitter as well as a trophic factor. These short-term and long-term actions are mediated by nucleotide receptors. Extracellular ATP can also act as a co-mitogen in conjunction with polypeptide growth factors such as basic fibroblast growth factor (FGF2). Cellular proliferation, differentiation and survival are regulated by signaling cascades composed of protein kinases, including extracellular signal regulated protein kinase (ERK) and protein kinase B (also called Akt). Here we summarize recent studies on nucleotide receptor signaling to ERK and Akt in astrocytes and the role of protein kinase cascades in mediating the trophic actions of extracellular ATP, alone or together with FGF2. Because extracellular ATP and FGF2 contribute to the hyperplastic and hypertrophic response of astrocytes to CNS injuries, an understanding of their protein kinase signaling mechanisms may lead to novel therapeutic approaches for neurological conditions that involve gliosis and the generation of reactive astrocytes, such as trauma, stroke, seizure and neurodegenerative and demyelinating disorders.Special issue dedicated to Lawrence F. Eng.     

FRIL蛋白体外维持脐血造血干/祖细胞的作用及细胞周期调控基因的表达

为探讨新的豆类凝集素(Flt3 receptor-interacting lectin,FRIL)体外维持脐血CD34^ 细胞的作用以及维持过程中细胞周期调控基因HTm4及HTm4S mRNA的表达及意义,我们利用FRIL维持培养脐血CD34^ 细胞,对其增殖曲线、细胞周期及集落形成能力进行常规分析,并用半定量RT—PCR法分别测定FRIL体外维持不同时间后脐血CD34^ 细胞中周期调控基因HTm4及HTm4S mRNA的表达变化。结果显示,FRIL培养的CD34^ 造血干／祖细胞的增殖趋势平缓,整个培养期间细胞增殖倍数不超过起始的3倍：14d之前,FRIL培养细胞的高增殖潜能集落形成细胞(HPP—CFC)形成集落数与FL组无差别,其后则维持高于FL的情况。细胞周期分析则显示,在28d的培养过程内,利用FRIL培养的细胞始终有80％以上维持在G0期;而周期调控基因HTm4及HTm4S在刚分离的脐血CD34^ 细胞中的表达水平较高;但培养1d后,几乎检测不到HTm4基因的表达;培养3～14d,该基因的表达回升并持续维持在高水平。而HTm4S基因的表达在第7d达最高水平,其余时间基本呈稳定表达。转染HTm4和HTm4S,亚细胞定位结果显示HTm4主要定位于核周围,而HTm4S则定位于整个胞浆,由此可能导致它们功能的区别。以上结果提示,长期培养体现出FRIL在维持造血干／祖细胞多能性上的优势;细胞周期调控基因HTm4及其新剪接子参与了FRIL体外长期维持脐血造血干／祖细胞处于静息状态的过程。     

Pre-germinated conidia of Coniothyrium minitans enhances the foliar biological control of Sclerotinia sclerotiorum

The relatively slow germination rate of Coniothyrium minitans limits its control efficiency against Sclerotinia sclerotiorum. Pre-germinated conidia of C. minitans enhanced its efficiency significantly: in foliar experiments with oilseed rape, hyphal extension of S. sclerotiorum was inhibited by 68%, while formation of sclerotia was completely inhibited when pre-germinated conidia were applied.     

Mathematical modeling for prediction of endo-xylanase activity and arabinoxylans concentration during mashing of barley malts for brewing

A mathematical model describing the degradation of arabinoxylans by endo-xylanase during mashing process was developed. Endo-xylanase activities and arabinoxylans concentrations in laboratory scale mashing process at different temperature profiles were measured and then used for identifying the model parameters for Harrington barley malt. The modeling errors range for the final concentration of arabinoxylans in wort was -4% to +11.9%. The model developed was also used for predicting the other three different malts mashing processes in laboratory scale, and the prediction errors ranged from -9.5% to +13.6%. The model prediction accuracy for industrial scale mashing process was lower than that in laboratory scale. The simulation results showed that, a lower concentration of arabinoxylans could be achieved when maintaining the mashing-in at 45 degrees C and prolonging the mashing-in time.     

Dot-blot hybridization and RT-PCR detection of extra small virus (XSV) associated with white tail disease of prawn Macrobrachium rosenbergii

The availability of specific and reliable detection methods is essential for monitoring the health status of farmed species, particularly for viral diseases. Extra small virus (XSV), a virus-like particle, is associated with Macrobrachium rosenbergii Noda virus (MrNV) in white tail disease (WTD) of M. rosenbergii. We developed 2 genome-based detection methods for the identification of XSV, namely dot-blot hybridization and a single-step RT-PCR. Detection limits were established and are ca. 2.5 pg and 5 fg of viral RNA for dot-blot hybridization and RT-PCR, respectively. Application of the methods to field samples indicated that some animals positively diagnosed with MrNV did not contain XSV, at least within the detection limit of the methodology. This raises the question of the actual role of XSV and its interactions with MrNV in WTD of M. rosenbergii.     

Establishment of a continuous embryonic cell line from Japanese flounder Paralichthys olivaceus for virus isolation

A continuous cell line, the flounder embryonic cell line (FEC), was established from gastrula-stage embryos of a marine cultured fish, the Japanese flounder Paralichthys olivaceus and cultured for more than 200 d with more than 60 passages. FEC cells were cultured in Dulbecco's Modified Eagle's Medium (DMEM) supplemented with antibiotics, fetal bovine serum (FBS), sea perch serum (SPS), and basic fibroblast growth factor (bFGF). The cells were small and round, and grew actively and stably in culture. The effect of temperature, FBS concentration and bFGF on FEC cell growth was examined. Cells grew well between 24 and 30 degrees C, but had a reduced growth rate below 18 degrees C. The growth rate of FEC cells in medium containing 15% FBS was higher than that in medium containing 7.5% FBS. Addition of bFGF to the medium also significantly increased the growth rate. Chromosome analysis revealed that FEC cells have a normal diploid karyotype with 2n = 48. High survival rate was obtained after cryopreservation of cell cultures. The susceptibility of the cell line to piscine viruses was examined. Two viruses tested were shown to induce CPE (cytopathic effect) on FEC cells. FEC cell culture infected with fish iridovirus was further elucidated by electron microscopy. Many virus particles were found in the cytoplasm of the virus-infected FEC cells. These results indicated that the FEC cell line could be potentially used to isolate and study fish viruses.