Chromosome imbalances in oligodendroglial tumors detected by comparative genomic hybridization

Seven well-differentiated oligodendrogliomas, 16 anaplastic oligodendrogliomas and two cases of oligoastrocytomas were investigated by comparative genomic hybridization (CGH) on frozen tissue samples. The most frequent losses found involved 1p and 19q in 32% of cases. Loss of 9p was observed during malignant progression in 25% of anaplastic oligodendrogliomas. In two anaplastic oligodendrogliomas gain of 1q was found. The frequent losses of chromosome 16 and 22 have not been reported previously. These results underscore that CGH is a powerful tool for the classification of gliomas complementing the traditional histopathological approach.     

Increased thermostability of three mesophilic β-galactosidases under high pressure

High pressure (>200Mpa) or high temperature (>45°C) can both induce an irreversible inactivation of the -galactosidases of Aspergillus oryzae, Kluyveromyces lactis and Escherichia coli. Moderate pressures (50MPa-250 MPa) exerted a protective effect against thermal inactivation for the three -galactosidases investigated. High pressure could thus be used to carry out b-galactosidase catalysed reactions such as lactose hydrolysis, at higher temperatures.     

Male Song Stimulation of Female Reproduction in Canaries: Features Relevant to Sexual Displays are not Relevant to Nest-building or Egg-laying

Recent studies conducted in our laboratory have demonstrated that a special type of song phrase (‘sexy’ phrases) containing bipartite syllables composed of abrupt frequency falls and short silences stimulate female canaries to solicit for copulation. The study was undertaken to determine whether sexy phrases also facilitated other aspects of the reproductive activity of the female canary, namely, nest-building and egg-laying. During the first experiment, we studied the effect of sexy and non-sexy songs on copulation solicitation displays in 1-year-old females without reproductive experience and in mature females with previous reproductive experience. We confirmed that sexy songs elicited more sexual responses than did non-sexy songs in yearlings and in mature females. During the second experiment, we studied the effect of male songs on nest-building activities and egg-laying in 1-year-old inexperienced females, and in mature, experienced females. The songs of conspecific males significantly triggered and increased nest-building behaviour in female canaries whatever their age or reproductive experience. In contrast, song effects on egg-laying were only found in young females. One-year-old inexperienced females exposed to sexy or non-sexy songs laid more eggs and laid earlier than did 1-year-old inexperienced controls; no such differences were observed in mature, experienced females. The efficiency of songs in promoting nest-building or egg-laying appeared to be unrelated to their efficiency in eliciting sexual responses. No difference was found between females exposed to sexy songs and females exposed to non-sexy songs; differences were only found between control and the two groups of song-exposed females. This result demands further experiments in order to determine whether other song phrase types may account for the stimulating effects of male song on female nest-building and egg-laying.     

Discoidin domain receptor 1 controls linear invadosome formation via a Cdc42–Tuba pathway

Accumulation of type I collagen fibrils in tumors is associated with an increased risk of metastasis. Invadosomes are F-actin structures able to degrade the extracellular matrix. We previously found that collagen I fibrils induced the formation of peculiar linear invadosomes in an unexpected integrin-independent manner. Here, we show that Discoidin Domain Receptor 1 (DDR1), a collagen receptor overexpressed in cancer, colocalizes with linear invadosomes in tumor cells and is required for their formation and matrix degradation ability. Unexpectedly, DDR1 kinase activity is not required for invadosome formation or activity, nor is Src tyrosine kinase. We show that the RhoGTPase Cdc42 is activated on collagen in a DDR1-dependent manner. Cdc42 and its specific guanine nucleotide-exchange factor (GEF), Tuba, localize to linear invadosomes, and both are required for linear invadosome formation. Finally, DDR1 depletion blocked cell invasion in a collagen gel. Altogether, our data uncover an important role for DDR1, acting through Tuba and Cdc42, in proteolysis-based cell invasion in a collagen-rich environment.     

Comparative effects of a non-steroidal ecdysone agonist RH-5992 and 20-hydroxyecdysone in a lepidopteran cell line (IAL-PID2)

The non-steroidal ecdysone agonist, RH-5992, exhibits ecdysteroid activities in vivo as well as in vitro more effectively than 20-hydroxyecdysone (20E). Using the IAL-PID2 cells derived from imaginal wing discs of last larval instar of Plodia interpunctella, we investigated the action of RH-5992 in the control of cell growth. Its effects on the proliferative activity of IAL-PID2 cells, the induction level in G2/M arrest and on the expression rate of Plodia B cyclin (PcycB), ecdysone B1-isoform (PIEcR-B1) and Ultraspiracle-2 isoform (PIUSP-2) were examined. From these cellular and molecular assays, our results brought evidence that RH-5992, like 20E, induced an inhibition on cell proliferation by blocking IAL-PID2 cells in G2/M phase. Moreover, this G2/M arrest was preceded by a decrease in the expression level of PcycB and a high induction of PIEcR-B1, PIUSP-2 mRNAs. Dose-response experiments revealed that RH-5992 was even more potent than 20E. On these parameters, we therefore suggest that the differential observed in the expression level of USP and EcR by RH-5992 and 20E could contribute to the difference observed for the biological potency of these two compounds.     

TGFbeta1-induced aortic endothelial morphogenesis requires signaling by small GTPases Rac1 and RhoA

TGFbeta is a potent regulator of cell differentiation in many cell types. On aortic endothelial cells, TGFbeta1 displays angiogenic properties in inducing capillary-like tube formation in collagen I gels, in vitro. We investigated cytoskeletal changes that precede tube formation and related these alterations to the effects of TGFbeta1 on the activation state of members of the RhoGTPase family. TGFbeta1 promotes cell elongation and stress fiber formation in aortic endothelial cells. Using cell lines with inducible expression of Rac1 mutants, we show that these events are mimicked by expression of dominant-negative Rac1 whereas the constitutively active mutant prevents the TGFbeta1-mediated change of phenotype. Although TGFbeta1 induces an initial rise in the Rac1-GTP content, this phase is followed by a prolonged loss of the active form. In contrast, RhoA activity increases progressively and reaches a plateau when Rac1-GTP is no longer detectable. Prolonged inhibition of Rac1 appears necessary and sufficient for the increase in RhoA-GTP. In situ examination of Rho activity in TGFbeta1-treated cells provides evidence that active RhoA relocalizes to the tips of elongated cells. Inhibiting the Rho effector ROCK abrogates tube formation. Thus, Rac1 and RhoA are regulated by TGFbeta1 in the process of endothelial tube formation in collagen I gels.