Les Néandertaliens d’El Sidrón (Asturies,Espagne). Actualisation d’un nouvel échantillon

This paper synthesizes and updates the information coming from the El Sidrón (Asturias, Northern Spain) neandertal site. Since 2000, a new sample of Homo neanderthalensis dated to at least 49,000 years old is being systematically recovered at the El Sidrón cave site. The bone assemblage is located in a secondary position, and certainly derives from a close location. The sample is almost exclusively composed of human remains. There is a moderate number of Middle Paleolithic stone tools (n ≈ 415) and very few macro-faunal remains. All skeletal parts are preserved, including some rare bones such as the hyoid bone. Teeth are abundant (n = 213), cranial and postcranial remains are also well represented, but fragmentary, with a special presence of foot and hand bones. A minimum number of thirteen individuals has been identified, comprising different developmental stages from infancy to adulthood: one infant, two juveniles, three adolescents, and seven adults. Paleobiology of the El Sidrón humans fits the pattern found in other neandertal samples: a high incidence of dental hypoplasia and interproximal grooves, yet no serious traumatic lesions are present. Moreover, unambiguous evidence of human-induced modifications (cannibalism) was found on the human remains: cut marks, percussion pitting, conchoidal scars and adhering flakes. Individuals seem to have been treated differentially. Morphologically, the El Sidrón humans show a large number of neandertal lineage-derived features even though certain traits place the sample at the limits of neandertal variation. Integrating the El Sidrón human mandibles and occipital bones into the larger neandertal sample reveals a possible geographic patterning, with southern Neandertals showing broader faces with increased lower facial heights. Ancient DNA analyses have been carried out, developing an anti-contamination protocol of excavation for minimizing the risk of modern human DNA contamination. As a result both mitochondrial and nuclear DNA have been extracted from dental and osteological remains. Curiously, mtDNA comparative analyses suggest a population affinity of Iberian Peninsula Neandertals with Central European Neandertals. Nuclear DNA analyses have permitted the identification of some functional genes such as the melanocortin 1 receptor (MC1R), which regulates hair and skin pigmentation; the FOXP2, a gene involved in the development of language; and the gene involved in the ABO blood group system. Nowadays the large El Sidrón sample is the most significant neandertal sample from the Iberian Peninsula, and augments the European evolutionary lineage fossil record, supporting ecogeographical variability across neandertal populations.     

Isolation of the New Antiplasmodial Butanolide,Malleastrumolide A,from Malleastrum sp. (Meliaceae) from Madagascar

An extract of Malleastrum sp. (Meliaceae) collected in Madagascar by the Madagascar International Cooperative Biodiversity Group was found to have antimalarial activity, with an IC ₅₀ value between 2.5 and 5 μg ml^?1. After purification by liquid‐liquid partition, chromatography on a Diaion open column, C ₁₈ SPE and C ₁₈ reversed phase HPLC , the new butanolide, malleastrumolide A, was isolated. The structure of malleastrumolide A was determined by mass spectrometry, NMR , and ECD . The double bond position was determined by cross‐metathesis and mass spectrometry. The compound has antiproliferative activity against the A2780 ovarian cancer cell line with an IC ₅₀ value of 17.4 μm and antiplasmodial activity against the drug‐resistant Dd2 strain of Plasmodium falciparum with an IC ₅₀ value of 2.74 μm .     

16S rRNA gene-based characterization of bacteria potentially associated with phosphate and carbonate precipitation from a granular autotrophic nitrogen removal bioreactor

Applied Microbiology and Biotechnology - A bench-scale granular autotrophic nitrogen removal bioreactor (completely autotrophic nitrogen removal over nitrite (CANON) system) used for the treatment...     

Interactions of an arbuscular mycorrhizal fungus with free or co-encapsulated cells of Rhizobium trifoli and Yarowia lipolytica inoculated into a soil-plant system

Four times higher nodule number was observed when Glomus deserticola (an arbuscular mycorrhizal fungus) was introduced into a soil-plant system as compared to the control inoculated only with Rhizobium trifoli. This symbiotic parameter was further enhanced by Yarowia lipolytica together with an increase in root mycorrhizal infection of about 14%. Soil inoculation with co-encapsulated R. trifoli and Y. lipolytica provoked a 10-fold increase in root nodulation and led to 55% mycorrhization of the test plant.     

Extracellular products as mediators of the formation and detachment of Pseudomonas fluorescens biofilms

Pseudomonas fluorescens B52 produces substantial biofilms at the air/liquid/solid interface of glass coverslips clamped vertically and partly submerged in liquid medium at 21°C. Biofilm formation was maximal ca. 20–50 h after inoculation of the liquid medium and, as indicated by environmental scanning electron microscopy (ESEM), contained large numbers of bacterial cells that were embedded within an extensive exopolymeric matrix. Incubation beyond 50 h led to reductions in biofilm which ESEM related primarily to losses of exopolymer. Both biofilm formation and the subsequent decline in exopolymer deposition was more rapid, and occurred to greater extents, when supernatants from two-day old cultures of B52 were used as the initial growth media. The addition of N-acyl-hexanoyl homoserine lactone to fresh growth medium had a similar effect upon biofilm formation as using spent culture medium. Homoserine lactones could not be demonstrated in spent culture supernatants by an Agrobacterium tumefaciens bioassay. An exopolysaccharide lyase was detected in spent culture media taken from dense biofilm cultures whose action was specifically directed towards biofilm exopolysaccharide. Results suggest that (i) cell-cell signals such as homoserine lactones are associated with the formation of P. fluorescens biofilms, (ii) the enzymic degradation of exopolymers has a specific role in the detachment of cells under starvation conditions, and (iii) whilst short chain (C₆) exogenous homoserines can trigger such responses in P. fluorescens, its own signal substance is likely to possess a longer (>C₈) fatty acyl chain.     

Mutation of an Arabidopsis NatB N-Alpha-Terminal Acetylation Complex Component Causes Pleiotropic Developmental Defects

N-α-terminal acetylation is one of the most common, but least understood modifications of eukaryotic proteins. Although a high degree of conservation exists between the N-α-terminal acetylomes of plants and animals, very little information is available on this modification in plants. In yeast and humans, N-α-acetyltransferase complexes include a single catalytic subunit and one or two auxiliary subunits. Here, we report the positional cloning of TRANSCURVATA2 (TCU2), which encodes the auxiliary subunit of the NatB N-α-acetyltransferase complex in Arabidopsis. The phenotypes of loss-of-function tcu2 alleles indicate that NatB complex activity is required for flowering time regulation and for leaf, inflorescence, flower, fruit and embryonic development. In double mutants, tcu2 alleles synergistically interact with alleles of ARGONAUTE10, which encodes a component of the microRNA machinery. In summary, NatB-mediated N-α-terminal acetylation of proteins is pleiotropically required for Arabidopsis development and seems to be functionally related to the microRNA pathway.