Arctic life adaptation--II. The function of musk ox (Ovibos muschatos) hemoglobin

1. The hemoglobin system from musk ox (Ovibos muschatos) has been characterized from the functional point of view with special regard to the effect of organic phosphates and temperature. 2. The results are similar to those previously obtained in the case of reindeer and confirm that hemoglobins from arctic animals may display very low enthalpy change for the reaction with oxygen. 3. This finding is considered an example of molecular adaptation of respiratory pigments to extreme environmental conditions.     

Ca2+-mediated action of long-chain acyl-CoA on liver mitochondria energy-linked processes

The decrease of steady-state transmembrane potential (delta psi) and loss of accumulated Ca2+ are magnified if palmitoyl-CoA is added to rat liver mitochondria exposed to Ca2+ and phosphate. The extent of this damage increases with increasing concentration of long-chain acyl-CoA. Addition of L-carnitine with or without the addition of palmitoyl-CoA considerably delays the deenergization. In the latter case, there is a substantial decrease in the assayed endogenous long-chain acyl-CoA content. This protective action of L-carnitine is abolished by L-aminocarnitine, a powerful inhibitor of carnitine palmitoyl transferase (palmitoyl-CoA: L-carnitine O-palmitoyltransferase, EC 2.3.1.21.). The removal of Ca2+ by EGTA, or the inhibition of its uptake by Ruthenium red or Mg2+ further enhances the degree of protection.     

Identifying genetic traces of historical expansions: Phoenician footprints in the Mediterranean

The Phoenicians were the dominant traders in the Mediterranean Sea two thousand to three thousand years ago and expanded from their homeland in the Levant to establish colonies and trading posts throughout the Mediterranean, but then they disappeared from history. We wished to identify their male genetic traces in modern populations. Therefore, we chose Phoenician-influenced sites on the basis of well-documented historical records and collected new Y-chromosomal data from 1330 men from six such sites, as well as comparative data from the literature. We then developed an analytical strategy to distinguish between lineages specifically associated with the Phoenicians and those spread by geographically similar but historically distinct events, such as the Neolithic, Greek, and Jewish expansions. This involved comparing historically documented Phoenician sites with neighboring non-Phoenician sites for the identification of weak but systematic signatures shared by the Phoenician sites that could not readily be explained by chance or by other expansions. From these comparisons, we found that haplogroup J2, in general, and six Y-STR haplotypes, in particular, exhibited a Phoenician signature that contributed > 6% to the modern Phoenician-influenced populations examined. Our methodology can be applied to any historically documented expansion in which contact and noncontact sites can be identified.     

Benzodiazepines differently modulate EAAT1/GLAST and EAAT2/GLT1 glutamate transporters expressed in CHO cells.

It has been described recently that low concentrations of benzodiazepines stimulate the transport activity of the neuronal glutamate transporter EAAT3, whereas high concentrations inhibit it. The present study is aimed to investigate whether benzodiazepines have similar effects on the two glial glutamate transporter, EAAT1 and EAAT2. To this end, the transporters were transiently expressed in CHO cells and transport activity was determined by isotope fluxes using D-aspartate as non-metabolizable homologue of L-glutamate. At low D-aspartate concentrations (1 micromol/l) EAAT1-mediated uptake was reduced significantly by low concentrations of oxazepam (1 micromol/l) and diazepam (1 and 10 micromol/l). At 100 micromol/l D-aspartate oxazepam stimulated EAAT1-mediated uptake up to 150% in a dose dependent manner, whereas the inhibition by low concentrations of diazepam was attenuated. In contrast, a significant effect of diazepam on EAAT2-mediated uptake was only observed at 1000 micromol/l where uptake was inhibited by 60%. A similar inhibition was observed for EAAT1. These studies demonstrate a different modulation of EAAT1 and EAAT2 by benzodiazepines. Furthermore the glial transporters differ from the neuronal glutamate transporter. Thus, a complex in vivo response of the various transporters to benzodiazepines can be expected.     

Testing evolutionary hypotheses about species borders: patterns of genetic variation towards the southern borders of two rainforest Drosophila and a related habitat generalist

Several evolutionary hypotheses help explain why only some species adapt readily to new conditions and expand distributions beyond borders, but there is limited evidence testing these hypotheses. In this study, we consider patterns of neutral (microsatellite) and quantitative genetic variation in traits in three species of Drosophila from the montium species group in eastern Australia. We found little support for restricted or asymmetrical gene flow in any species. In rainforest-restricted Drosophila birchii, there was evidence of selection for increased desiccation and starvation resistance towards the southern border, and a reduction in genetic diversity in desiccation resistance at this border. No such patterns existed for Drosophila bunnanda, which has an even more restricted distribution. In the habitat generalist Drosophila serrata, there was evidence for geographic selection for wing size and development time, although clinal patterns for increased cold and starvation resistance towards the southern border could not be differentiated from neutral expectations. These findings suggest that borders in these species are not limited by low overall genetic variation but instead in two of the species reflect patterns of selection and genetic variability in key traits limiting borders.     

Articles by Latin American Authors in Prestigious Journals Have Fewer Citations

Background

The journal Impact factor (IF) is generally accepted to be a good measurement of the relevance/quality of articles that a journal publishes. In spite of an, apparently, homogenous peer-review process for a given journal, we hypothesize that the country affiliation of authors from developing Latin American (LA) countries affects the IF of a journal detrimentally.

Methodology/Principal Findings

Seven prestigious international journals, one multidisciplinary journal and six serving specific branches of science, were examined in terms of their IF in the Web of Science. Two subsets of each journal were then selected to evaluate the influence of author''s affiliation on the IF. They comprised contributions (i) with authorship from four Latin American (LA) countries (Argentina, Brazil, Chile and Mexico) and (ii) with authorship from five developed countries (England, France, Germany, Japan and USA). Both subsets were further subdivided into two groups: articles with authorship from one country only and collaborative articles with authorship from other countries. Articles from the five developed countries had IF close to the overall IF of the journals and the influence of collaboration on this value was minor. In the case of LA articles the effect of collaboration (virtually all with developed countries) was significant. The IFs for non-collaborative articles averaged 66% of the overall IF of the journals whereas the articles in collaboration raised the IFs to values close to the overall IF.

Conclusion/Significance

The study shows a significantly lower IF in the group of the subsets of non-collaborative LA articles and thus that country affiliation of authors from non-developed LA countries does affect the IF of a journal detrimentally. There are no data to indicate whether the lower IFs of LA articles were due to their inherent inferior quality/relevance or psycho-social trend towards under-citation of articles from these countries. However, further study is required since there are foreseeable consequences of this trend as it may stimulate strategies by editors to turn down articles that tend to be under-cited.     

Cupressus arizonica pollen wall zonation and in vitro hydration

The structure of Cupressus arizonica pollen at different degrees of hydration was examined by using cytochemical staining and light (LM) and scanning electron (SEM) microscopy. Most pollen grains are inaperturate and a minority are provided with an operculate pore enveloped by a concave annulus. Intine consists of: 1) a thin polysaccharidic outer layer, 2) a large polysaccharidic middle layer that is spongy and bordered by a mesh of large and branched fibrils, and 3) an inner cellulosic thick layer with callose concentrated on the inner side, which forms a shell around the protoplast. The protoplast is egg-shaped with PAS positive cytoplasm and prominent nucleus. Exine splits during hydration and is cast off according to three major steps: 1) the split opens like a mouth and the underlying intine is expelled by swelling like a balloon, 2) the protoplast enveloped by the inner intine is sucked in the outgrowing side, and 3) the backside of the intine gets rid of the exine shell. In water containing salts, exine is rapidly released and the middle intine may expand up to break the outer layer, with disgregation of the spongy material and release of the intine shell including the protoplast. In water lacking salts, the sporoderm hydration and breaking are negatively influenced by the population effect. Pollen when air dried after the exine release become completely flat owing to disappearance of the middle intine layer which may be restored by dipping pollen in water. The results are discussed in relation to the functional potentialities of the sporoderm.