The Palaeoenvironmental Impact of Prehistoric Settlement and Proto-Historic Urbanism: Tracing the Emergence of the Oppidum of Corent,Auvergne, France

Early human societies and their interactions with the natural world have been extensively explored in palaeoenvironmental studies across Central and Western Europe. Yet, despite an extensive body of scholarship, there is little consideration of the environmental impacts of proto-historic urbanisation. Typically palaeoenvironmental studies of Bronze and Iron Age societies discuss human impact in terms of woodland clearance, landscape openness and evidence for agriculture. Although these features are clearly key indicators of human settlement, and characterise Neolithic and early to Middle Bronze Age impacts at Corent, they do not appear to represent defining features of a protohistoric urban environment. The Late Iron Age Gallic Oppidum of Corent is remarkable for the paucity of evidence for agriculture and strong representation of apophytes associated with disturbance. Increased floristic diversity – a phenomenon also observed in more recent urban environments – was also noted. The same, although somewhat more pronounced, patterns are noted for the Late Bronze Age and hint at the possibility of a nascent urban area. High percentages of pollen from non-native trees such as Platanus, Castanea and Juglans in the late Bronze Age and Gallic period also suggest trade and cultural exchange, notably with the Mediterranean world. Indeed, these findings question the validity of applying Castanea and Juglans as absolute chronological markers of Romanisation. These results clearly indicate the value of local-scale palaeoecological studies and their potential for tracing the phases in the emergence of a proto-historic urban environment.     

Identification of a plant gene encoding glutamate/aspartate-prephenate aminotransferase: the last homeless enzyme of aromatic amino acids biosynthesis

In all organisms synthesising phenylalanine and/or tyrosine via arogenate, a prephenate aminotransferase is required for the transamination of prephenate into arogenate. The identity of the gene encoding this enzyme in the organisms where this activity occurs is still unknown. Glutamate/aspartate-prephenate aminotransferase (PAT) is thus the last homeless enzyme in the aromatic amino acids pathway. We report on the purification, mass spectrometry identification and biochemical characterization of Arabidopsis thaliana prephenate aminotransferase. Our data revealed that this activity is housed by the prokaryotic-type plastidic aspartate aminotransferase (At2g22250). This represents the first identification of a gene encoding PAT.     

Trimethylation of Histone H3 Lysine 36 by Human Methyltransferase PRDM9 Protein

PRDM9 (PR domain-containing protein 9) is a meiosis-specific protein that trimethylates H3K4 and controls the activation of recombination hot spots. It is an essential enzyme in the progression of early meiotic prophase. Disruption of the PRDM9 gene results in sterility in mice. In human, several PRDM9 SNPs have been implicated in sterility as well. Here we report on kinetic studies of H3K4 methylation by PRDM9 in vitro indicating that PRDM9 is a highly active histone methyltransferase catalyzing mono-, di-, and trimethylation of the H3K4 mark. Screening for other potential histone marks, we identified H3K36 as a second histone residue that could also be mono-, di-, and trimethylated by PRDM9 as efficiently as H3K4. Overexpression of PRDM9 in HEK293 cells also resulted in a significant increase in trimethylated H3K36 and H3K4 further confirming our in vitro observations. Our findings indicate that PRDM9 may play critical roles through H3K36 trimethylation in cells.     

No longer locally extinct? Tracing the origins of a lion (<Emphasis Type="Italic">Panthera leo</Emphasis>) living in Gabon

Lions (Panthera leo) are of particular conservation concern due to evidence of recent, widespread population declines in what has hitherto been seen as a common species, robust to anthropogenic disturbance. Here we use non-invasive methods to recover complete mitochondrial genomes from single hair samples collected in the field in order to explore the identity of the Gabonese Plateaux Batéké lion. Comparison of the mitogenomes against a comprehensive dataset of African lion sequences that includes relevant geographically proximate lion populations from both contemporary and ancient sources, enabled us to identify the Plateaux Batéké lion as a close maternal relative to now extirpated populations found in Gabon and nearby Congo during the twentieth century, and to extant populations of Southern Africa. Our study demonstrates the relevance of ancient DNA methods to field conservation work, and the ability of trace field samples to provide copious genetic information about free-ranging animals.     

An NB-LRR protein required for HR signalling mediated by both extra- and intracellular resistance proteins

Tomato (Solanum lycopersicum) Cf resistance genes confer hypersensitive response (HR)-associated resistance to strains of the pathogenic fungus Cladosporium fulvum that express the matching avirulence (Avr) gene. Previously, we identified an Avr4-responsive tomato (ART) gene that is required for Cf-4/Avr4-induced HR in Nicotiana benthamiana as demonstrated by virus-induced gene silencing (VIGS). The gene encodes a CC-NB-LRR type resistance (R) protein analogue that we have designated NRC1 (NB-LRR protein required for HR-associated cell death 1). Here we describe that knock-down of NRC1 in tomato not only affects the Cf-4/Avr4-induced HR but also compromises Cf-4-mediated resistance to C. fulvum. In addition, VIGS using NRC1 in N. benthamiana revealed that this protein is also required for the HR induced by the R proteins Cf-9, LeEix, Pto, Rx and Mi. Transient expression of NRC1(D481V), which encodes a constitutively active NRC1 mutant protein, triggers an elicitor-independent HR. Subsequently, we transiently expressed this auto-activating protein in N. benthamiana silenced for genes known to be involved in HR signalling, thereby allowing NRC1 to be positioned in an HR signalling pathway. We found that NRC1 requires RAR1 and SGT1 to be functional, whereas it does not require NDR1 and EDS1. As the Cf-4 protein requires EDS1 for its function, we hypothesize that NRC1 functions downstream of EDS1. We also found that NRC1 acts upstream of a MAP kinase pathway. We conclude that Cf-mediated resistance signalling requires a downstream NB-LRR protein that also functions in cell death signalling pathways triggered by other R proteins.     

The state of the art of paleoparasitological research in the Old World

Paleoparasitology in the Old World has mainly concerned the study of latrine sediments and coprolites collected from mummified bodies or archaeological strata, mostly preserved by natural conditions. Human parasites recovered include cestodes, trematodes, and nematodes. The well preserved conditions of helminth eggs allowed paleoepidemiological approaches taking into account the number of eggs found by archaeological stratum. Tentatively, sanitation conditions were assessed for each archaeological period.     

Central nervous system myelin of teleosts: comparative electrophoretic analysis of its proteins by staining and immunoblotting

CNS myelin was isolated from 24 teleostean fishes and the proteins were analyzed by staining and immunoblotting. All species showed a 36 K protein, two or more glycosylated hydrophobic intermediate protein (IP) components and several myelin basic protein bands (BP). The 36 K protein was specific for teleostean fishes. The IP and BP components displayed substantial variations in their proportions as well as in molecular sizes when comparing the different teleosts. This contrasts with CNS myelin proteins which appear more stable in terrestrial vertebrates.     

Growth properties and biochemical characterization of mouse Schwann cells cultured in vitro

Purified secondary cultures of mouse Schwann cells (less than 5% fibroblast contamination) have been obtained by taking advantage of the differential adhesion of Schwann cells and fibroblasts during trypsinization. The growth properties of the purified subcultures changed with time in culture. Cells passaged after 5 days in vitro (DIV) divided rapidly (doubling time 22 h), whereas cells that had been in vitro for longer periods progressively decreased their growth rate, becoming quiescent after 20 or more days. Schwann cells lacked the Thy 1.2 surface antigen, but were positively stained with antigalactocerebroside antibodies after prefixation. Biochemical analyses showed Schwann cells to be enriched in the activities of enzymes characteristic of the myelin-forming cells: 2′3′-cyclic nucleotide 3′-phosphodiesterase (CNP), cerebroside sulfotransferase (CST) and UDP-galactose: ceramide galactosyltransferase (CGalT).