Behavioral Analysis of Genetically Modified Mice Indicates Essential Roles of Neurosteroidal Estrogen

Aromatase in the mouse brain is expressed only in the nerve cells of specific brain regions with a transient peak during the neonatal period when sexual behaviors become organized. The aromatase-knockout (ArKO) mouse, generated to shed light on the physiological functions of estrogen in the brain, exhibited various abnormal behaviors, concomitant with undetectable estrogen and increased androgen in the blood. To further elucidate the effects of neurosteroidal estrogens on behavioral phenotypes, we first prepared an brain-specific aromatase transgenic (bsArTG) mouse by introduction of a human aromatase transgene controlled under a −6.5 kb upstream region of the brain-specific promoter of the mouse aromatase gene into fertilized mouse eggs, because the −6.5 kb promoter region was previously shown to contain the minimal essential element responsible for brain-specific spatiotemporal expression. Then, an ArKO mouse expressing the human aromatase only in the brain was generated by crossing the bsArTG mouse with the ArKO mouse. The resulting mice (ArKO/bsArTG mice) nearly recovered from abnormal sexual, aggressive, and locomotive (exploratory) behaviors, in spite of having almost the same serum levels of estrogen and androgen as the adult ArKO mouse. These results suggest that estrogens locally synthesized in the specific neurons of the perinatal mouse brain directly act on the neurons and play crucial roles in the organization of neuronal networks participating in the control of sexual, aggressive, and locomotive (exploratory) behaviors

Genome-Wide Expression Analysis Identifies a Modulator of Ionizing Radiation-Induced p53-Independent Apoptosis in Drosophila melanogaster

Tumor suppressor p53 plays a key role in DNA damage responses in metazoa, yet more than half of human tumors show p53 deficiencies. Therefore, understanding how therapeutic genotoxins such as ionizing radiation (IR) can elicit DNA damage responses in a p53-independent manner is of clinical importance. Drosophila has been a good model to study the effects of IR because DNA damage responses as well as underlying genes are conserved in this model, and because streamlined gene families make loss-of-function analyses feasible. Indeed, Drosophila is the only genetically tractable model for IR-induced, p53-independent apoptosis and for tissue regeneration and homeostasis after radiation damage. While these phenomenon occur only in the larvae, all genome-wide gene expression analyses after irradiation to date have been in embryos. We report here the first analysis of IR-induced, genome-wide gene expression changes in wild type and p53 mutant Drosophila larvae. Key data from microarrays were confirmed by quantitative RT-PCR. The results solidify the central role of p53 in IR-induced transcriptome changes, but also show that nearly all changes are made of both p53-dependent and p53-independent components. p53 is found to be necessary not just for the induction of but also for the repression of transcript levels for many genes in response to IR. Furthermore, Functional analysis of one of the top-changing genes, EF1a-100E, implicates it in repression of IR-induced p53-independent apoptosis. These and other results support the emerging notion that there is not a single dominant mechanism but that both positive and negative inputs collaborate to induce p53-independent apoptosis in response to IR in Drosophila larvae

Molecular doping effect in bottom-gate, bottom-contact pentacene thin-film transistors

A bottom-gate, bottom-contact (BGBC) organic thin-film transistor (OTFT) with carrier-doped regions over source-drain electrodes was investigated. Device simulation with our originally developed device simulator demonstrates that heavily doped layers (p+ layers) on top of the source-drain contact region can compensate the deficiency of charge carriers at the source-channel interface during transistor operation, leading to the increase of the drain current and the apparent field-effect mobility. The phenomena expected with the device simulation were experimentally confirmed in typical BGBC pentacene thin-film transistors. The 5-nm-thick p+ layers, located 10 nm (or 20 nm) over the source-drain electrodes, were prepared by coevaporation of pentacene and 2, 3, 5, 6-tetrafluoro-7, 7, 8, 8-tetracyanoquinodimethane as an acceptor dopant. Since the molecular doping in this study can increase the drain current without positive shift of threshold voltage, p+ layers were formed precisely on top of the source-drain regions. This study shows that common inferior characteristics of bottom-contact OTFT devices mainly derive from the supply shortage of charge carriers to the channel region. The importance of reliable molecular doping techniques or heavily doped semiconductor materials for improving OTFT device performance is clearly suggested

ヒトLFA-3(CD58)におけるゲノム構造と選択的スプライシングによるバリアントmRNAの産生

細胞表面glycoproteinであるLFA-3には,glycosyl phosphatidyl inosito1(GPI)結合型および膜貫通型など,いくつかの固有のmRNA分子種の存在が証明されている.このLFA-3の多様な転写特性とmRNA産生のメカニズムを明らかにするために,我々はゲノムクローニングに引き続き構造および機能の解析を行なった.LFA-3geneは少なくとも41.1kbの大きさを持ち,6つのエキソンにより構成されていた.2つの主なmRNA種は第5エキソンにおける選択的スプライシングacceptor selectionにより産生されており,2つのマイナーなものは,第3エキソンの選択的スプライシングdonor selectionおよびエキソンスキップによる部分的および完全な欠失により産生されていた.プライマー伸長法による解析では,一連の転写開始部位が観察され,それはTATAおよびCAT boxの欠如によるものであると考えられた.1.3kbの5\u27上流の隣接配列は配向依存性にCAT reporter遺伝子の発現を促進できたが,その転写活性は低かった.LFA-3と他の2つの関連分子CD2およびCD48の遺伝子進化がそれらのゲノム構造から推測された.Several distinct mRNA species have been demonstrated for lymphocyte function-associated antigen-3 (LFA-3, CD58), a cell-surface glycoprotein anchored either through glycosyl phosphatidyl inositol (GPI)-linkage or by a transmembrane domain. We obtained a genomic clone for the LFA-3 gene and performed structural and functional analyses. The LFA-3 gene is at least 41.1 kb in length and consists of 6 exons. Two major mRNA species are generated by alternative splicing acceptor selection in exon 5, and two other minor ones by partial or entire elimination of exon 3 as a result of alternative splice donor selection or exon-skip. Primer extension analysis revealed that transcription may be initiated at a series of sites, probably because of the absence of TATA and CAAT box sequences. A 1.3-kb 5\u27-upstream flanking region was able to drive the expression of a reporter gene in an orientation-dependent manner, but only at a low level. The evolutionary relation-ship of LFA-3 with other two related molecules, CD2 and CD48, was also discussed on the basis of genomic structure