Should the teaching of biological evolution include the origin of life?

The development of mainstream research on the origin of life as an outcome of Darwinian evolution is discussed. It is argued that prebiotic evolution and the origin of life should not be excluded from the syllabus and should be part of classes on biological evolution, and that the transition from non-living to living matter is best understood when seen as part of evolutionary biology. The wide acceptance of evolutionary approaches to the study of the emergence of life in European and Latin American countries is discussed

Motor signatures of emotional reactivity in frontotemporal dementia

Automatic motor mimicry is essential to the normal processing of perceived emotion, and disrupted automatic imitation might underpin socio-emotional deficits in neurodegenerative diseases, particularly the frontotemporal dementias. However, the pathophysiology of emotional reactivity in these diseases has not been elucidated. We studied facial electromyographic responses during emotion identification on viewing videos of dynamic facial expressions in 37 patients representing canonical frontotemporal dementia syndromes versus 21 healthy older individuals. Neuroanatomical associations of emotional expression identification accuracy and facial muscle reactivity were assessed using voxel-based morphometry. Controls showed characteristic profiles of automatic imitation, and this response predicted correct emotion identification. Automatic imitation was reduced in the behavioural and right temporal variant groups, while the normal coupling between imitation and correct identification was lost in the right temporal and semantic variant groups. Grey matter correlates of emotion identification and imitation were delineated within a distributed network including primary visual and motor, prefrontal, insular, anterior temporal and temporo-occipital junctional areas, with common involvement of supplementary motor cortex across syndromes. Impaired emotional mimesis may be a core mechanism of disordered emotional signal understanding and reactivity in frontotemporal dementia, with implications for the development of novel physiological biomarkers of socio-emotional dysfunction in these diseases

EZH2 Depletion Blocks the Proliferation of Colon Cancer Cells

The Enhancer of Zeste 2 (EZH2) protein has been reported to stimulate cell growth in some cancers and is therefore considered to represent an interesting new target for therapeutic intervention. Here, we investigated a possible role of EZH2 for the growth control of colon cancer cells. RNA interference (RNAi)-mediated intracellular EZH2 depletion led to cell cycle arrest of colon carcinoma cells at the G1/S transition. This was associated with a reduction of cell numbers upon transient transfection of synthetic EZH2-targeting siRNAs and with inhibition of their colony formation capacity upon stable expression of vector-borne siRNAs. We furthermore tested whether EZH2 may repress the growth-inhibitory p27 gene, as reported for pancreatic cancer. However, expression analyses of colon cancer cell lines and colon cancer biopsies did not reveal a consistent correlation between EZH2 and p27 levels. Moreover, EZH2 depletion did not re-induce p27 expression in colon cancer cells, indicating that p27 repression by EZH2 may be cell- or tissue-specific. Whole genome transcriptome analyses identified cellular genes affected by EZH2 depletion in colon cancer cell lines. They included several cancer-associated genes linked to cellular proliferation or invasion, such as Dag1, MageD1, SDC1, Timp2, and Tob1. In conclusion, our results demonstrate that EZH2 depletion blocks the growth of colon cancer cells. These findings might provide benefits for the treatment of colon cancer

Nitrate deposition in northern hardwood forests and the nitrogen metabolism of Acer saccharum marsh

It is generally assumed that plant assimilation constitutes the major sink for anthropogenic Nitrate NO 3 − deposited in temperate forests because plant growth is usually limited by nitrogen (N) availability. Nevertheless, plants are known to vary widely in their capacity for NO 3 − uptake and assimilation, and few studies have directly measured these parameters for overstory trees. Using a combination of field and greenhouse experiments, we studied the N nutrition of Acer saccharum Marsh. in four northern hardwood forests receiving experimental NO 3 − additions equivalent to 30 kg N ha −1 year −1 . We measured leaf and fine-root nitrate reductase activity (NRA) of overstory trees using an in vivo assay and used 15 N to determine the kinetic parameters of NO 3 − uptake by excised fine roots. In two greenhouse experiments, we measured leaf and root NRA in A. saccharum seedlings fertilized with 0–3.5 g NO 3 − −N m −2 and determined the kinetic parameters of NO 3 − and NH 4 + uptake in excised roots of seedlings. In both overstory trees and seedlings, rates of leaf and fine root NRA were substantially lower than previously reported rates for most woody plants and showed no response to NO 3 − fertilization (range = non-detectable to 33 nmol NO 2 − g −1 h −1 ). Maximal rates of NO 3 − uptake in overstory trees also were low, ranging from 0.2 to 1.0 μmol g −1 h −1 . In seedlings, the mean V max for NO 3 − uptake in fine roots (1 μmol g −1 h −1 ) was approximately 30 times lower than the V max for NH 4 + uptake (33 μmol g −1 h −1 ). Our results suggest that A. saccharum satisfies its N demand through rapid NH 4 + uptake and may have a limited capacity to serve as a direct sink for atmospheric additions of NO 3 − .Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47695/1/442_2004_Article_BF00334659.pd

Symbols of Power: The Firearm Paintings of Madjedbebe (Malakunanja II)

Depictions of firearms in Australian Aboriginal rock art provide a unique opportunity to archaeologically explore the roles that this type of material culture played in times of culture contact. From the earliest interactions with explorers to the buffalo shooting enterprises of the twentieth century—firearms played complex and shifting roles in western Arnhem Land Aboriginal societies. The site of Madjedbebe (sometimes referred to as Malakunanja II in earlier academic literature) in Jabiluka (Mirarr Country), offers the opportunity to explore these shifting roles over time with an unprecedented 16 paintings of firearms spanning the nineteenth and twentieth centuries. This rock art provides evidence for early firearms as objects of curiosity and threat to local groups, as well as evidence for later personal ownership and use of such weaponry. Moreover, we argue that the rock art suggests increasing incorporation of firearms into traditional cultural belief and artistic systems over time with Madjedbebe playing a key role in the communication of the cultural meanings behind this new subject matter.Arts, Education & Law Group, School of Humanities, Languages and Social SciencesFull Tex

Device, system and method for the measurement of a vapor transmission rate through a film of permeable material

Abstract not available for NL200441