Dominant climate influences on North American bird distributions

Aim Geographic distributions of species are constrained by several factors acting at different scales, with climate assumed to be a major determinant at broad extents. Recent studies, however, have challenged this statement and indicated that climate may not dominate among the factors governing geographic distributions of species. Here, we argue that these results are misleading due to the lack of consideration of the geographic area that has been accessible to the species. Location North America. Methods We generated null distributions for 75 North American endemic and 19 non‐endemic bird species. For each species, climatic envelopes of observed and null distributions were modelled using neural networks and generalized linear models, and seven climatic predictors. Values of the area under the receiver–operating characteristic curve (AUC) based on models of observed distributions were compared with corresponding AUC values for the null distributions. Results More than 82% of the endemic species showed AUC higher for the observed than for the null distributions, while 63% of the non‐endemic species showed such a pattern. Main conclusions We demonstrate a dominant climatic signal in shaping North American bird distributions. Our results attest to the importance of climate in determining species distributions and support the use of climate‐envelope models for estimating potential distributional areas at the appropriate spatial scales.     

Striatal pre- and postsynaptic profile of adenosine A(2A) receptor antagonists

Striatal adenosine A(2A) receptors (A(2A)Rs) are highly expressed in medium spiny neurons (MSNs) of the indirect efferent pathway, where they heteromerize with dopamine D(2) receptors (D(2)Rs). A(2A)Rs are also localized presynaptically in cortico-striatal glutamatergic terminals contacting MSNs of the direct efferent pathway, where they heteromerize with adenosine A(1) receptors (A(1)Rs). It has been hypothesized that postsynaptic A(2A)R antagonists should be useful in Parkinson's disease, while presynaptic A(2A)R antagonists could be beneficial in dyskinetic disorders, such as Huntington's disease, obsessive-compulsive disorders and drug addiction. The aim or this work was to determine whether selective A(2A)R antagonists may be subdivided according to a preferential pre- versus postsynaptic mechanism of action. The potency at blocking the motor output and striatal glutamate release induced by cortical electrical stimulation and the potency at inducing locomotor activation were used as in vivo measures of pre- and postsynaptic activities, respectively. SCH-442416 and KW-6002 showed a significant preferential pre- and postsynaptic profile, respectively, while the other tested compounds (MSX-2, SCH-420814, ZM-241385 and SCH-58261) showed no clear preference. Radioligand-binding experiments were performed in cells expressing A(2A)R-D(2)R and A(1)R-A(2A)R heteromers to determine possible differences in the affinity of these compounds for different A(2A)R heteromers. Heteromerization played a key role in the presynaptic profile of SCH-442416, since it bound with much less affinity to A(2A)R when co-expressed with D(2)R than with A(1)R. KW-6002 showed the best relative affinity for A(2A)R co-expressed with D(2)R than co-expressed with A(1)R, which can at least partially explain the postsynaptic profile of this compound. Also, the in vitro pharmacological profile of MSX-2, SCH-420814, ZM-241385 and SCH-58261 was is in accordance with their mixed pre- and postsynaptic profile. On the basis of their preferential pre- versus postsynaptic actions, SCH-442416 and KW-6002 may be used as lead compounds to obtain more effective antidyskinetic and antiparkinsonian compounds, respectively.     

Mycobacterium tuberculosis lipolytic enzymes as potential biomarkers for the diagnosis of active tuberculosis

Background

New diagnosis tests are urgently needed to address the global tuberculosis (TB) burden and to improve control programs especially in resource-limited settings. An effective in vitro diagnostic of TB based on serological methods would be regarded as an attractive progress because immunoassays are simple, rapid, inexpensive, and may offer the possibility to detect cases missed by standard sputum smear microscopy. However, currently available serology tests for TB are highly variable in sensitivity and specificity. Lipolytic enzymes have recently emerged as key factors in lipid metabolization during dormancy and/or exit of the non-replicating growth phase, a prerequisite step of TB reactivation. The focus of this study was to analyze and compare the potential of four Mycobacterium tuberculosis lipolytic enzymes (LipY, Rv0183, Rv1984c and Rv3452) as new markers in the serodiagnosis of active TB.

Methods

Recombinant proteins were produced and used in optimized ELISA aimed to detect IgG and IgM serum antibodies against the four lipolytic enzymes. The capacity of the assays to identify infection was evaluated in patients with either active TB or latent TB and compared with two distinct control groups consisting of BCG-vaccinated blood donors and hospitalized non-TB individuals.

Results

A robust humoral response was detected in patients with active TB whereas antibodies against lipolytic enzymes were infrequently detected in either uninfected groups or in subjects with latent infection. High specifity levels, ranging from 93.9% to 97.5%, were obtained for all four antigens with sensitivity values ranging from 73.4% to 90.5%, with Rv3452 displaying the highest performances. Patients with active TB usually exhibited strong IgG responses but poor IgM responses.

Conclusion

These results clearly indicate that the lipolytic enzymes tested are strongly immunogenic allowing to distinguish active from latent TB infections. They appear as potent biomarkers providing high sensitivity and specificity levels for the immunodiagnosis of active TB.     

Multifunctionality and diversity in bacterial biofilms

Bacteria are highly diverse and drive a bulk of ecosystem processes. Analysis of relationships between diversity and single specific ecosystem processes neglects the possibility that different species perform multiple functions at the same time. The degradation of dissolved organic carbon (DOC) followed by respiration is a key bacterial function that is modulated by the availability of DOC and the capability to produce extracellular enzymes. In freshwater ecosystems, biofilms are metabolic hotspots and major sites of DOC degradation. We manipulated the diversity of biofilm forming communities which were fed with DOC differing in availability. We characterized community composition using molecular fingerprinting (T-RFLP) and measured functioning as oxygen consumption rates, the conversion of DOC in the medium, bacterial abundance and the activities of five specific enzymes. Based on assays of the extracellular enzyme activity, we calculated how the likelihood of sustaining multiple functions was affected by reduced diversity. Carbon source and biofilm age were strong drivers of community functioning, and we demonstrate how the likelihood of sustaining multifunctionality decreases with decreasing diversity.     

Fragmentation of contaminant and endogenous DNA in ancient samples determined by shotgun sequencing; prospects for human palaeogenomics

BACKGROUND: Despite the successful retrieval of genomes from past remains, the prospects for human palaeogenomics remain unclear because of the difficulty of distinguishing contaminant from endogenous DNA sequences. Previous sequence data generated on high-throughput sequencing platforms indicate that fragmentation of ancient DNA sequences is a characteristic trait primarily arising due to depurination processes that create abasic sites leading to DNA breaks. METHODOLOGY/PRINCIPALS FINDINGS: To investigate whether this pattern is present in ancient remains from a temperate environment, we have 454-FLX pyrosequenced different samples dated between 5,500 and 49,000 years ago: a bone from an extinct goat (Myotragus balearicus) that was treated with a depurinating agent (bleach), an Iberian lynx bone not subjected to any treatment, a human Neolithic sample from Barcelona (Spain), and a Neandertal sample from the El Sidrón site (Asturias, Spain). The efficiency of retrieval of endogenous sequences is below 1% in all cases. We have used the non-human samples to identify human sequences (0.35 and 1.4%, respectively), that we positively know are contaminants. CONCLUSIONS: We observed that bleach treatment appears to create a depurination-associated fragmentation pattern in resulting contaminant sequences that is indistinguishable from previously described endogenous sequences. Furthermore, the nucleotide composition pattern observed in 5' and 3' ends of contaminant sequences is much more complex than the flat pattern previously described in some Neandertal contaminants. Although much research on samples with known contaminant histories is needed, our results suggest that endogenous and contaminant sequences cannot be distinguished by the fragmentation pattern alone.     

Molecular mechanisms involved in the adenosine A and A receptor-induced neuronal differentiation in neuroblastoma cells and striatal primary cultures

Adenosine A1 receptors (A1Rs) and adenosine A(2A) receptors (A(2A)Rs) are the major mediators of the neuromodulatory actions of adenosine in the brain. In the striatum A1Rs and A(2A)Rs are mainly co-localized in the GABAergic striatopallidal neurons. In this paper we show that agonist-induced stimulation of A1Rs and A(2A)Rs induces neurite outgrowth processes in the human neuroblastoma cell line SH-SY5Y and also in primary cultures of striatal neuronal precursor cells. The kinetics of adenosine-mediated neuritogenesis was faster than that triggered by retinoic acid. The triggering of the expression of TrkB neurotrophin receptor and the increase of cell number in the G1 phase by the activation of adenosine receptors suggest that adenosine may participate in early steps of neuronal differentiation. Furthermore, protein kinase C (PKC) and extracellular regulated kinase-1/2 (ERK-1/2) are involved in the A1R- and A(2A)R-mediated effects. Inhibition of protein kinase A (PKA) activity results in a total inhibition of neurite outgrowth induced by A(2A)R agonists but not by A1R agonists. PKA activation is therefore necessary for A(2A)R-mediated neuritogenesis. Co-stimulation does not lead to synergistic effects thus indicating that the neuritogenic effects of adenosine are mediated by either A1 or A(2A) receptors depending upon the concentration of the nucleoside. These results are relevant to understand the mechanisms by which adenosine receptors modulate neuronal differentiation and open new perspectives for considering the use of adenosine agonists as therapeutic agents in diseases requiring neuronal repair.     

Zygospores as evidence of sexual reproduction in the genus Orphella

The presence of zygospores in the genus Orphella is newly described. We found zygospores in three species of the genus, O. catalaunica, O. coronata and O. helicospora, which are all the species of the genus known from the Iberian territory. Zygospores are associated with a heterothallic conjugating sexual process in O. coronata, whereas in O. catalaunica and O. helicospora, they form homothallically. In all instances, zygospores are consistently associated with an organized pattern of sterile cells, forming structures comparable to those present with asexual trichospores. We compare the ontogeny of Orphella zygospores with that found in the harpellid Genistellospora homothallica and discuss the possible close relationship of Orphella with Kickxellales (Zygomycetes). We report O. coronata in Spain for the first time, replacing all previous records of O. haysii. Results are supported with line drawings and photographs.