Highly repeated DNA sequences as phylogenetic markers among the galaginae

Highly repeated DNA sequences were investigated as potential phylogenetic indicators among five species of galagines. One lorisine, one cheirogaleid, and two lemurid species were also investigated as progressively more distant outgroups. The lorisids displayed strong conservatism with regard to these sequences, to the point where the galegine species proved difficult to differentiate. When restriction fragment differences were observed, the galagine species fell into two groups: one containing the greater galagos and G. alleni and the other comprising the lesser galagos. The sequences of the cheirogaleid Microcebus murinus were found to be highly species-specific, bearing little resemblance to those of the galagines or the lemurids. Common sequences detected between M. murinus and G. senegalensis may be ancient sequences shared by all strepsirhines. © 1994 Wiley-Liss, Inc.     

Targeting the mTOR regulatory network in hepatocellular carcinoma: Are we making headway?

The mechanistic target of rapamycin (mTOR) pathway coordinates organismal growth and homeostasis in response to growth factors, nutrients, and cellular energy stage. The pathway regulates several major cellular processes and is implicated in various pathological conditions, including hepatocellular carcinoma (HCC). This review summarizes recent advances of the mTOR pathway, highlights the potential of the mTOR pathway as a therapeutic target, and explores clinical trials targeting the mTOR pathway in HCC. Although the review focuses on the mTOR pathway involved in HCC, more comprehensive discussions (eg, developing a rational design for future trials targeting the mTOR pathway) are also applicable to other tumors.     

Structural Analysis of Cholesterol Binding and Sterol Selectivity by ABCG5/G8

The ATP-binding cassette (ABC) sterol transporters are responsible for maintaining cholesterol homeostasis in mammals by participating in reverse cholesterol transport (RCT) or transintestinal cholesterol efflux (TICE). The heterodimeric ABCG5/G8 carries out selective sterol excretion, preventing the abnormal accumulation of plant sterols in human bodies, while homodimeric ABCG1 contributes to the biogenesis and metabolism of high-density lipoproteins. A sterol-binding site on ABCG5/G8 was proposed at the interface of the transmembrane domain and the core of lipid bilayers. In this study, we have determined the crystal structure of ABCG5/G8 in a cholesterol-bound state. The structure combined with amino acid sequence analysis shows that in the proximity of the sterol-binding site, a highly conserved phenylalanine array supports functional implications for ABCG cholesterol/sterol transporters. Lastly, in silico docking analysis of cholesterol and stigmasterol (a plant sterol) suggests sterol-binding selectivity on ABCG5/G8, but not ABCG1. Together, our results provide a structural basis for cholesterol binding on ABCG5/G8 and the sterol selectivity by ABCG transporters.     

Restriction Enzyme-Resistant High Molecular Weight Telomeric DNA Fragments in Tobacco

Restriction endonuclease-resistant high-molecular-weight (HMW)DNA fragments were isolated from nuclear DNA fragments in tobacco.The size of the fragments produced by EcoRI, HindIII, AfaI,and HaeIII ranged from 20 kb to over 166 kb. The kinetics ofdigestion by Bal31 nuclease showed that most of the HMW fragmentsare chromosome ends. The consensus sequence for tobacco telomererepeats was determined to be CCCTAAA by genomic sequencing usingthe HMW fragments and by sequencing after cloning. Besides thetelomere sequence, 9 tandem repeats of a 45-bp sequence wereidentified, in which a 35-bp unit sequence (AGTCAGCATTAGGGTTTTAAACCCTAAACTGAACT)formed a stem structure. The front of the stem is composed ofa palindrome of the telomere repeats. This highly conservedunit is surrounded by less conserved internal sequences thatare around 10–11 bp in size and contain a TTTT stretch.The internal sequences resemble the 10–11 bp consensusfor the scaffold attachment regions found in yeast and drosophila.The characteristic 45-bp sequence was abundant on the ends ofchromosomes. The shortest distance between the repeats containingtelomeric stem and the telomere was less than 20 kb. This architectureof the tobacco chromosome end region resembles the end regionof yeast chromosomes in which autonomous replication sequencesare present frequently.     

Significant Dreams: Bizarre or Beautiful?

The literature on highly significant dreams is filled with references to the bizarreness of their content. On the other hand, the concept of beauty is rarely if ever mentioned in relation to these dreams. Grounded in archetypal psychology's tenet that psychological life is aesthetic life, this article argues that the enduring, even life-long, influence some dreams have on the dreamer's life may be better approached through the idea of beauty than through the idea of bizarreness. The argument builds on Hunt's (1989, 1995) theoretical model of the nature of consciousness and dream multiplicity with its emphasis on cross-modal synesthesia as well as on insights provided by Scarry's (1999) recent essay on beauty. A detailed account of how one composer's work was profoundly influenced by his most significant dream is presented to illustrate this aesthetic approach to understanding the on-going significance of significant dreams.     

Knock-in of the duck retinoic acid-inducible gene I (RIG-I) into the Mx gene in DF-1 cells enables both stable and immune response-dependent RIG-I expression

Waterfowls, such as ducks, are natural hosts of avian influenza virus (AIV) and can genetically limit the pathogenicity. On the other hand, some AIV strains cause severe pathogenicity in chickens. It is suggested that differences in the pathogenicity of AIV infection between waterfowls and chickens are related to the expression of retinoic acid-inducible gene I (RIG-I), a pattern recognition receptor that chickens evolutionally lack. Here, we knocked-in the duck RIG-I bearing the T2A peptide sequence at the 3′ region of the Mx, an interferon-stimulated gene (ISG), in chicken embryo fibroblast cells (DF-1) using the precise integration into target chromosome (PITCh) system to control the duck RIG-I expression in chickens. The expression patterns of the duck RIG-I were then analyzed using qPCR. The knocked-in DF-1 cells expressed RIG-I via the stimulation of IFN-β and poly(I:C) in a dose-dependent manner. Moreover, poly(I:C) stimulation in the knocked-in DF-1 cells upregulated RIG-I-like receptor (RLR) family signaling pathway-related genes IFN-β, OASL, and IRF7. The IFN-β-dependent expression of RIG-I and upregulation of IFN-β in the poly(I:C) stimulation demonstrated a positive-feedback loop via RIG-I, usually evident in ducks. Overall, this novel strategy established RIG-I-dependent immune response in chickens without overexpression of RIG-I and disruption of the host genes.     

利用滚环扩增鉴别同源家族miRNAs

滚环扩增（rolling circle amplification, RCA）是一种基于病毒DNA复制而发明的新技术。近些年，RCA技术已经被广泛应用于微小核糖核酸（micro ribonucleic acid, miRNA）的检测。在miRNA检测研究领域中，鉴别高度同源的家族miRNAs成为该研究领域的瓶颈。本研究引入新型的RCA技术来增加鉴别的灵敏度和特异性，进一步提高家族miRNA鉴别的灵敏度，滚环扩增的程度用相对荧光强度来表示。研究结果显示，T4 RNA连接酶2可在RCA的环化过程中实现最大的环化效率，从而提高RCA的检测特异性。本文利用优化的RCA技术，实现对let 7高度同源的家族miRNAs高灵敏度的鉴别，灵敏度可达5 fmol。let 7a的滚环探针对Let 7a这一miRNA扩增后的相对荧光强度为1 550，而对其他的家族miRNA相对荧光强度仅为260。其他的家族miRNA探针在鉴别时相对荧光强度也显示了较大的差异。而依靠传统的RT-qPCR方法的鉴别灵敏度是4 pmol，与本研究相比，灵敏度低了近1 000倍。本研究的结果表明，利用RCA技术鉴别高度同源性miRNAs是高效灵敏的，此前未见相关研究的报道。RCA技术可能被应用于miRNA高灵敏度检测和鉴别的相关研究中。     

The evolution of punishment and apology: an iterated prisoner's dilemma model

Recently, behaviors that seem to function as punishment or apology have been reported among non-human primates as well as humans. Such behaviors appear to play an important role in maintaining cooperation between individuals. Therefore, the evolution of these behaviors should be examined from the viewpoint of the evolution of cooperation. The iterated prisoner's dilemma (IPD) game is generally considered to be a standard model for the evolution of cooperation. In the present study, strategies accompanied by punishment-like attacks or apology-like behavior were introduced into the common IPD simulation. Punishment and apology were represented by the P signal and the AS signal given immediately after defection. A strategy with the P and AS signals, named the pPAS strategy, was proved to be an evolutionarily stable strategy under certain conditions. Numerical simulations were carried out according to different assigned values of the costs of punishment and apology. The simulations showed that pPAS could dominate the population (1) when the cost of giving P is relatively small, (2) when the cost of receiving P is relatively large, or (3) when the cost of giving AS is relatively large. The relative cost of giving AS had the clearest effect on the success of pPAS. pPAS can dominate the population even when a dominance asymmetry of the costs between two players was introduced. The present results suggest the possible evolution of social behaviors like punishment or apology as a means of maintaining cooperation. This revised version was published online in November 2006 with corrections to the Cover Date.