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.     

Correlation between oxidative Stress and Alteration of Intracellular Calcium Handling in Isoproterenol-Induced Myocardial Infarction

Myocardial Ca²⁺ overload and oxidative stress are well documented effects associated to isoproterenol (ISO)-induced myocardial necrosis, but information correlating these two issues is scarce. Using an ISO-induced myocardial infarction model, 3 stages of myocardial damage were defined: pre-infarction (0–12 h), infarction (12–24 h) and post-infarction (24–96 h). Alterations in Ca²⁺ homeostasis and oxidative stress were studied in mitochondria, sarcoplasmic reticulum and plasmalemma by measuring the Ca²⁺ content, the activity of Ca²⁺ handling proteins, and by quantifying TBARs, nitric oxide (NO) and oxidative protein damage (changes in carbonyl and thiol groups). Free radicals generated system, antioxidant enzymes and oxidative stress (GSH/GSSG ratio) were also monitored at different times of ISO-induced cardiotoxicity. The Ca²⁺ overload induced by ISO was counterbalanced by a diminution in the ryanodine receptor activity and the Na⁺-Ca⁺² exchanger as well as by the increase in both calcium ATPases activities (vanadate- and thapsigargine-sensitive) and mitochondrial Ca²⁺ uptake during pre-infarction and infarction stages. Pro-oxidative reactions and antioxidant defences during the 3 stages of cardiotoxicity were observed, with maximal oxidative stress during the infarction. Significant correlations were found among pro-oxidative reactions with plasmalemma and sarcoplasmic reticulum Ca²⁺ ATPases, and ryanodine receptor activities at the onset and development of ISO-induced infarction. These findings could be helpful in the design of antioxidant therapies in this pathology.     

Expression and activation of ephexin is altered after spinal cord injury

Failure of axon regeneration after traumatic spinal cord injury (SCI) is attributable in part to the presence of inhibitory molecular interactions. Recent evidence demonstrates that activation of Eph signaling pathways leads to modulation of growth cone dynamics and repulsion through the activation of ephexin, a novel guanine nucleotide exchange factor (GEF). However, little is known about the expression and modulation of Eph molecular targets in the injured spinal cord. In this study, we determined the expression profile of ephexin after a moderate spinal cord contusion at thoracic level (T10) in young adult rats. Western-blot studies showed increased protein expression in injured rats at 4 and 7 days postinjury (DPI) when compared with control animals. The protein levels returned to normal at 14 DPI and remained steady until 28 DPI. However, immunoprecipitation studies of the phosphorylated ephexin demonstrated that this protein is activated by day 2 until 14 DPI. Expression of ephexin was noticeable in neurons, axons, microglia/macrophages, and reactive astrocytes, and co-localized with EphA3, A4, and A7. These results demonstrate the presence of ephexin in the adult spinal cord and its activation after SCI. Therefore, we show, for the first time, the spatiotemporal pattern of ephexin expression and activation after contusive SCI. Collectively, our data support our previous findings on the putative nonpermissive roles of Eph receptors after SCI and the possible involvement of ephexin in the intracellular cascade of events.     

Trophic basis of production in tropical headwater streams,Puerto Rico: an assessment of the importance of allochthonous resources in fueling food webs

The relative importance of allochthonous and autochthonous resources in fueling tropical headwater streams remains an open topic. We combined estimates of secondary production and assessment of its trophic basis to determine which resources were responsible for animal production. We studied benthic insect assemblages in two streams in the Luquillo Experimental Forest, Puerto Rico. Habitat-weighted production estimates were similar in both streams (528.5 and 591.5 mg m⁻² year⁻¹), but production was over twice as high in pool versus riffle habitats. The mayfly Neohagenulus (Leptophlebiidae) was a major contributor to total production (259.1 and 352.2 mg m⁻² year⁻¹). All taxa relied heavily on amorphous detritus and plant tissue. Aquatic insect production was similar to that reported for shrimp assemblages in the same study area, but low relative to temperate region estimates. The trophic basis of production appears to be allochthonous organic matter, which agrees with the small size and closed canopy cover over the study streams. This is the first study quantifying the production and trophic basis of the non-shrimp macroinvertebrate assemblage in tropical island streams. We also provide support for the importance of riparian vegetation as the main energy sources for stream tropical stream food webs.

     

Winter survival of North American grassland birds is driven by weather and grassland condition in the Chihuahuan Desert

Populations of grassland birds that overwinter in the Chihuahuan Desert are declining more rapidly than other grassland birds, and survival during the non‐breeding season may have a strong influence on population trends of these species. Habitat loss and deterioration due to desertification may be contributing to these declines, and the winter ecology of grassland birds under these changing environmental conditions remains relatively unexplored. To fill this information gap, we estimated the survival of two grassland‐obligate sparrows, Baird's Sparrows (Ammodramus bairdii) and Grasshopper Sparrows (A. savannarum), on their wintering grounds in the Chihuahuan Desert, and investigated the role of habitat structure and weather on survival rates. We deployed radio‐transmitters on Baird's (N = 49) and Grasshopper (N = 126) sparrows near Janos, Chihuahua, and tracked birds from November to March during the winters of 2012–2013 and 2013–2014. Causes of mortality included avian predators, mammals, and possibly weather. We estimated an overall weekly winter survival probability of ? = 92.73% (95% CI[s] = 88.63–95.44%) for Baird's Sparrows in 2012–2013. We estimated a weekly winter survival probability of ? = 93.48% (95% CI[s] = 90.29–96.67%) and ? = 98.78% (95% CI[s] = 97.88–99.68%) for Grasshopper Sparrow in 2012–2013 and 2013–2014, respectively. Weekly winter survival was lower with colder daily minimum temperatures for both species and in areas with taller shrubs for Grasshopper Sparrows, with the shrubs potentially increasing predation risk by providing perches for Loggerhead Shrikes (Lanius ludovicianus). Our results highlight the need to maintain healthy grass structure in wintering areas to provide birds with food, protection from predators, and adequate cover from inclement weather. Our results also demonstrate that the presence of shrubs can lower winter survival, and suggest that shrub encroachment into the winter habitat of these sparrows may be an important driver of their population declines. Shrub removal could increase survival of wintering sparrows in the Chihuahuan Desert by reducing availability of perches for avian predators, thus reducing predation risk.     

A continuous peptide epitope reacting with pandemic influenza AH1N1 predicted by bioinformatic approaches

Computational identification of potential epitopes with an immunogenic capacity challenges immunological research. Several methods show considerable success, and together with experimental studies, the efficiency of the algorithms to identify potential peptides with biological activity has improved. Herein, an epitope was designed by combining bioinformatics, docking, and molecular dynamics simulations. The hemagglutinin protein of the H1N1 influenza pandemic strain served as a template, owing to the interest of obtaining a scheme of immunization. Afterward, we performed enzyme‐linked immunosorbent assay (ELISA) using the epitope to analyze if any antibodies in human sera before and after the influenza outbreak in 2009 recognize this peptide. Also, a plaque reduction neutralization test induced by virus‐neutralizing antibodies and the IgG determination showed the biological activity of this computationally designed peptide. The results of the ELISAs demonstrated that the serum of both prepandemic and pandemic recognized the epitope. Moreover, the plaque reduction neutralization test evidenced the capacity of the designed peptide to neutralize influenza virus in Madin‐Darby canine cells. Copyright © 2015 John Wiley & Sons, Ltd.     

Involvement of a plasmid in Escherichia coli envelope alterations.

A plasmid-containing wild-type Escherichia coli strain was treated with two plasmid-curing agents, sodium dodecyl sulfate and ethidium bromide. Plasmid elimination was accompanied by drastic changes in the morphology of the colonies. Analysis of the cured strain by scanning and transmission electron microscopy showed important alterations in size and morphology of the cells. Metabolic differences were also found between the wild-type and cured cells.     

Effects of flower dimorphism and light environment on arbuscular mycorrhizal colonisation in a cleistogamous herb

Although it is known that floral dimorphism contributes to the maintenance of mixed breeding systems, the consequences of producing progeny of a contrasting genetic background and seeds with differential resource allocation has been practically ignored regarding establishment of belowground organisms–plant interactions. This article evaluates the combined effect of floral dimorphism with cross type and light environment on interactions between Ruellia nudiflora and arbuscular mycorrhizal fungi (AMF). R. nudiflora produces cleistogamous (CL) flowers that exhibit obligate self‐pollination and chasmogamous (CH) flowers with facultative self‐ (CHs) or cross‐ (CHc) pollination. We evaluated the establishment of the plant–AMF interaction in progeny derived from each floral type, under two light conditions (shaded versus open). We established different scenarios depending on the existence of inbreeding depression (ID) and whether the differential resource allocation (DRA) to CH and CL flowers affected the R. nudiflora–AMF interaction. We predicted that under shaded light conditions there might be an intensification of ID, having a negative effect on AMF colonisation. The percentages of hyphae and vesicles in the harvested roots was significantly higher in the shaded plants (F ≥ 4.11, P < 0.05), while progeny of CHc and CHs presented a higher percentage of hyphae and vesicle colonisation compared to CL progeny (F = 15.26, P < 0.01). The results show that DRA to CH flowers and light availability both determines the establishment of R. nudiflora–AMF interaction. The results also suggest that even under stressful light conditions, endogamy does not affect this interaction, which may explain the success of R. nudiflora as an invasive species.