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It has been proposed that much of conceptual knowledge is acquired through situated conceptualization, such that both external (e.g., agents, objects, events) and internal (e.g., emotions, introspections) environments are considered important (Barsalou, 2003). To evaluate this proposal, we characterized two dimensions by which situated conceptualization may be measured and which should have different relevance for abstract and concrete concepts; namely, emotional experience (i.e., the ease with which words evoke emotional experience; Newcombe, Campbell, Siakaluk, & Pexman, 2012) and context availability (i.e., the ease with which words evoke contexts in which their referents may appear; Schwanenflugel & Shoben, 1983). We examined the effects of these two dimensions on abstract and concrete word processing in verbal semantic categorization (VSCT) and naming tasks. In the VSCT, emotional experience facilitated processing of abstract words but inhibited processing of concrete words, whereas context availability facilitated processing of both types of words. In the naming task in which abstract words and concrete words were not blocked by emotional experience, context availability facilitated responding to only the abstract words. In the naming task in which abstract words and concrete words were blocked by emotional experience, emotional experience facilitated responding to only the abstract words, whereas context availability facilitated responding to only the concrete words. These results were observed even with several lexical (e.g., frequency, age of acquisition) and semantic (e.g., concreteness, arousal, valence) variables included in the analyses. As such, the present research suggests that emotional experience and context availability tap into different aspects of situated conceptualization and make unique contributions to the representation and processing of abstract and concrete concepts.

X-inactivation, the molecular mechanism enabling dosage compensation in mammals, is tightly controlled during mouse early embryogenesis. In the morula, X-inactivation is imprinted with exclusive silencing of the paternally inherited X-chromosome. In contrast, in the post-implantation epiblast, X-inactivation affects randomly either the paternal or the maternal X-chromosome. The transition from imprinted to random X-inactivation takes place in the inner cell mass (ICM) of the blastocyst from which embryonic stem (ES) cells are derived. The trigger of X-inactivation, Xist, is specifically downregulated in the pluripotent cells of the ICM, thereby ensuring the reactivation of the inactive paternal X-chromosome and the transient presence of two active X-chromosomes. Moreover, Tsix, a critical cis-repressor of Xist, is upregulated in the ICM and in ES cells where it imposes a particular chromatin state at the Xist promoter that ensures the establishment of random X-inactivation upon differentiation. Recently, we have shown that key transcription factors supporting pluripotency directly repress Xist and activate Tsix and thus couple Xist/Tsix control to pluripotency. In this manuscript, we report that Rnf12, a third X-linked gene critical for the regulation of X-inactivation, is under the control of Nanog, Oct4 and Sox2, the three factors lying at the heart of the pluripotency network. We conclude that in mouse ES cells the pluripotency-associated machinery exerts an exhaustive control of X-inactivation by taking over the regulation of all three major regulators of X-inactivation: Xist, Tsix, and Rnf12. Electronic supplementary material The online version of this article (doi:10.1007/s00439-011-0998-5) contains supplementary material, which is available to authorized users.

Polycomb-repressive complex 1 (PRC1) and PRC2 maintain repression at many developmental genes in mouse embryonic stem cells and are required for early development. However, it is still unclear how they are targeted and how they function. We show that the ability of RING1B, a core component of PRC1, to ubiquitinate histone H2A is dispensable for early mouse embryonic development and much of the gene repression activity of PRC1. Our data support a model in which PRC1 and PRC2 reinforce each other's binding but suggest that the key functions of PRC1 lie beyond the enzymatic capabilities of RING1B.

Of particular interest in biology is how different chromatin states contribute to the complex regulation of gene transcription that is necessary to establish and maintain multi-cellular organisms. This is because (with few exceptions) each cell within an organism contains the same genomic sequence, meaning that the diversity of expression states is not due to variability in the underlying genetic sequence but could result from differences in chromatin landscape. This area of research comes under the umbrella of ‘epigenetics’, which is concerned with molecular processes involved in regulating gene expression that are transmittable and independent of changes in DNA sequence. However, perhaps owing to the ambiguity of this definition, the term often means different things to different people. A more precise definition of 'epigenetic' mechanisms is 'the structural adaptation of chromosomal regions so as to register, signal or perpetuate altered activity states' (Bird, 2007). Differentiated cells are said to have an 'epigenetic memory' imparted by epigenetic processes that can maintain a pattern of gene transcription through time and cell divisions. Understanding the mechanisms involved in setting up and maintaining these processes is an exciting area of research investigation.

Relationships between forest structure and avian communities have been documented in many northern temperate and tropical studies. This study tests the applicability of conclusions from those studies to New Zealand forest bird communities. For 29 months from September 1982 to February 1985 we monitored the bird community in part of the Ruamahanga Ecological Area, Tararua State Forest Park. We used a modified 5 min bird count to determine the relative abundances of each bird species. The modification consisted of separating the counts into birds near to ( 20 m) the observer. The near/far ratio proved useful in assessing the distribution of common bird species but was inadequate for rarer species. Twenty‐nine bird species were seen, 21 of which probably bred within the study area. Eleven forest bird species were seen with sufficient frequency to apply the near/far ratio. Principal component analysis was used as a graphical tool to describe the inter‐relationships of bird specie...

Edmund R. Leach. Culture and Communication: The Logic by Which Symbols Are Connected. An Introduction to the Use of Structuralist Analysis in Social Anthropology. Cambridge: Cambridge University Press. 1976. 105 pp. Dan Sperber. Rethinking Symbolism. Translator, Alice L. Morton. Cambridge: Cambridge University Press. 1975. xiii + 153 pp.