Representing Representation: Integration between the Temporal Lobe and the Posterior Cingulate Influences the Content and Form of Spontaneous Thought

When not engaged in the moment, we often spontaneously represent people, places and events that are not present in the environment. Although this capacity has been linked to the default mode network (DMN), it remains unclear how interactions between the nodes of this network give rise to particular mental experiences during spontaneous thought. One hypothesis is that the core of the DMN integrates information from medial and lateral temporal lobe memory systems, which represent different aspects of knowledge. Individual differences in the connectivity between temporal lobe regions and the default mode network core would then predict differences in the content and form of people’s spontaneous thoughts. This study tested this hypothesis by examining the relationship between seed-based functional connectivity and the contents of spontaneous thought recorded in a laboratory study several days later. Variations in connectivity from both medial and lateral temporal lobe regions was associated with different patterns of spontaneous thought and these effects converged on an overlapping region in the posterior cingulate cortex. We propose that the posterior core of the DMN acts as a representational hub that integrates information represented in medial and lateral temporal lobe and this process is important in determining the content and form of spontaneous thought.     

Family trees representing the finitely proliferative nature of cultured rat liver cells

Family trees of rat liver epithelial-like cells in primary culture were obtained by cinemicrographic analysis. With few exceptions the proliferative profiles reconstituted from these family trees showed limited proliferation. This limitation was not due to post-confluence inhibition of proliferation or to nutritional deprivation during time lapse cinemicrography, but to the finite potential of clonal proliferation. In these family trees a cell entered mitosis, incomplete division, death, or a long interphase with no detectable termination. These family trees successfully related the life phases of the individual cells that compose the population to the limited nature of proliferative potential as observed in clonal cell populations.     

Induction of SOS responses in Escherichia coli by Panfuran-S, 3-di(hydroxymethyl)amino-6-(5-nitro-2-furylethenyl)-1,2,4-triazine

The inducibility of SOS responses by Panfuran-S, which has been used as an antimicrobial medicine in Japan, was studied in Escherichia coli cells having different DNA-repair capacities for UV lesions. Panfuran-S induced mutations at high frequencies in uvrA and the wild-type strains, and significant killing effects of Panfuran-S were detected in DNA-repair-deficient strains, uvrA and recA. The effective prophage induction was detected in two kinds of lambda-lysogenized cells treated with Panfuran-S. The expression of the umuC+ gene was apparently induced in uvrA and the wild-type strains, but not induced in lexA and recA strains. In particular, high inducibility of the gene expression was detected in uvrA strain as compared with the wild-type strain. From these results, we conclude that Panfuran-S is a DNA-damaging agent and may induce the error-prone SOS responses.     

A novel sperm-specific hypomethylation sequence is a demethylation hotspot in human hepatocellular carcinomas.

Certain human DNA regions are strikingly undermethylated at CpG sites in sperm compared to adult somatic tissues. These sperm-specific hypomethylation sequences are thought to function early in embryogenesis or gametogenesis. By using the restriction landmark genomic scanning (RLGS) cloning method, we have isolated a novel sperm-specific hypomethylation sequence, the status of which changes during spermatogenesis, embryonal growth and differentiation. This sequence is a part of a new 'NotI repeat' consisting of a 1.4 kb repetitive unit sequence named DE-1. The sequence is GC-rich and has high homology to a CpG DNA clone that was isolated by a methyl CpG protein binding column, indicating that it was normally highly methylated. We investigated the methylation status of this sequence. In the normal genome the sequence was methylated, but in the human hepatocellular carcinoma (HCC) genome, the target sequence was demethylated at the cytosine residue of the CpG dinucleotides with high frequency (75% in the previous study). These data suggest that this regional DNA hypomethylation may play a role in both cell differentiation and hepatocarcinogenesis.     

Effects of tannic acid and its related compounds upon Chikungunya virus.

The present report describes not only the effects of tannic acid (TA; belonging to hydrolyzable tannins) and its related compounds upon the infectivity of Chikungunya virus (CHIKV) but also the mechanism involved in this phenomenon. Our data show that TA inactivates CHIKV in vitro. Since the inactivating effect turned out to be pH-dependent and was suppressed by bovine serum albumin, it is most probable that the virus-inactivating capacity of TA is attributable to its preferential binding to proteins of virus particles. Examination on the virus-inactivating capacities of some TA-related compounds and comparison of their structures indicated that the active site of TA and its analogues might be the phenolic hydroxyl groups in their molecules. It seems that the active groups interact with the proteins of virus particles, resulting in a reduction or loss of viral infectivity. Discussion is made on the specificity of the actions of tannins and the possibility of application thereof to chemicals which are useful to investigate the nature and properties of viral proteins.