Geographical patterns of deep mitochondrial differentiation in widespread Malagasy reptiles

Using sequences of the mitochondrial 16S rRNA gene, we reconstructed the phylogeography of six widely distributed Malagasy reptiles: two gekkonid lizard species, Phelsuma lineata and Hemidactylus mercatorius; two chameleons, the Calumma brevicorne complex, and Furcifer lateralis; and two skinks, Trachylepis gravenhorstii and Trachylepis elegans. Genetic differentiation among major haplotype lineages was high and in some cases indicates or confirms species status of the divergent populations. Maximum uncorrected sequence divergences were between 2.2% and 8.3% within the various species or species complexes. Haplotype lineages were exclusive to geographic regions, except in the commensal H. mercatorius where in three anthropogenic habitats coexistence of haplotype lineages was observed, possibly due to human translocation. The eastward flowing rivers Mangoro and Mananara may represent barriers to gene flow in the case of three species each. Some species sampled from humid eastern and arid western Madagascar showed no differentiation between populations from these two regions; instead the pattern observed was in several cases more concordant with a differentiation along a north-south axis.     

Azaspiracid-1, a potent,nonapoptotic new phycotoxin with several cell targets

This paper reports on potential cellular targets of azaspiracid-1 (AZ-1), a new phycotoxin that causes diarrhoeic and neurotoxic symptoms and whose mechanism of action is unknown. In excitable neuroblastoma cells, the systems studied were membrane potential, F-actin levels and mitochondrial membrane potential. AZ-1 does not modify mitochondrial activity but decreases F-actin concentration. These results indicate that the toxin does not have an apoptotic effect but uses actin for some of its effects. Therefore, cytoskeleton seems to be an important cellular target for AZ-1 effect. AZ-1 does not induce any modification in membrane potential, which does not support for neurotoxic effects. In human lymphocytes, cAMP, cytosolic calcium and cytosolic pH (pHi) levels were also studied. AZ-1 increases cytosolic calcium and cAMP levels and does not affect pHi (alkalinization). Cytosolic calcium increase seems to be dependent on both the release of calcium from intracellular Ca(2+) pools and the influx from extracellular media through Ni(2+)-blockable channels. AZ-1-induced Ca(2+) increase is negatively modulated by protein kinase C (PKC) activation, protein phosphatases 1 and 2A (PP1 and PP2A) inhibition and cAMP increasing agents. The effect of AZ-1 in cAMP is not extracellularly Ca(2+) dependent and insensitive to okadaic acid (OA).     

“On A Piece of Chalk”-Updated1

ABSTRACT. Many advances have been made in our knowledge of the biology of foraminifera over the past several decades. Fine structural, biophysical, and molecular biological studies have shown that the most prominent components of their distinctive bidirectional granuloreliculopods are bundles of micro tubules linked by crossbridges to each other, as well as to membrane-bound organelles and the plasma membrane. the microtubules ratchet past each other as dynein transduces the free energy of ATP to produce pseudopodal movements. In spite of the fact that there are over 40,000 described species of living and fossil species of foraminifera, there have been many recent exciting discoveries of new species and groups. New casting techniques are providing us with greater understanding of the complexities and functional aspects of form in the group. Significant advances are being made in understanding the distribution and energetics of deep-sea forms. Larger and planktonic foraminifera are the hosts for a particularly diverse range of endosymbiotic algae, including dinoflagellates, chlorophytes, unicellular rhodophytes, and diatoms. Chloroplast husbandry also occurs. Significant research effort has been expended yielding us considerable insight into various aspects of the endosymbiotic phenomenon. A unified conceptual framework has been drawn to help us understand the life cycle options found in foraminifera.     

Total antioxidant capacity – a novel early bio-chemical marker of oxidative stress in HIV infected individuals

Background  

Oxidative stress induced by the production of reactive oxygen species may play a critical role in the stimulation of HIV replication and the development of immunodeficiency. This study was conducted as there are limited and inconclusive studies on the significance of a novel early marker of oxidative stress which can reflect the total antioxidant capacity in HIV patients,     

A highly multiplexed quantitative phosphosite assay for biology and preclinical studies

Reliable methods to quantify dynamic signaling changes across diverse pathways are needed to better understand the effects of disease and drug treatment in cells and tissues but are presently lacking. Here, we present SigPath, a targeted mass spectrometry (MS) assay that measures 284 phosphosites in 200 phosphoproteins of biological interest. SigPath probes a broad swath of signaling biology with high throughput and quantitative precision. We applied the assay to investigate changes in phospho‐signaling in drug‐treated cancer cell lines, breast cancer preclinical models, and human medulloblastoma tumors. In addition to validating previous findings, SigPath detected and quantified a large number of differentially regulated phosphosites newly associated with disease models and human tumors at baseline or with drug perturbation. Our results highlight the potential of SigPath to monitor phosphoproteomic signaling events and to nominate mechanistic hypotheses regarding oncogenesis, response, and resistance to therapy.     

Evolution of cytochrome P-450 proteins [published erratum appears in Mol Biol Evol 1988 Mar;5(2):199]

Thirty-four cytochrome P-450 sequences from one bacterial and six vertebrate species have been aligned with the aid of a computer alignment algorithm. Phylogenetic trees were constructed using the unweighted-pair-group and neighbor-joining methods. The two trees differed at only a single branch point near the base of the tree. The cytochrome P-450 superfamily of proteins clustered into eight families and contained 16 gene-duplication events. The first gene duplication occurred approximately 1,360 Myr before the present (Mybp) and gave rise to cytochrome P-450s found in two different cellular organelles, the mitochondria and the endoplasmic reticulum. Both groups utilize cholesterol or its metabolites as substrates, implying that cholesterol existed greater than 1,360 Mybp. The fourth gene duplication (approximately 900 Mybp) gave rise to the drug-metabolizing P-450s. These proteins aid in the detoxification of foreign chemicals, as opposed to the metabolism of endogenous compounds. The importance of the capacity to metabolize drugs is reflected in 11 further gene duplications occurring in this lineage. The first occurred approximately 800 Mybp and gave rise to the two major P-450 families, the phenobarbital and 3-methylcholanthrene families. An apparent increase in the rate of cytochrome P-450 evolution is noted between the bird-mammal divergence (300 Mybp) and the mammalian radiation (75 Mybp).      

Interplay of metagenomics and in vitro compartmentalization

In recent years, the application of approaches for harvesting DNA from the environment, the so‐called, ‘metagenomic approaches’ has proven to be highly successful for the identification, isolation and generation of novel enzymes. Functional screening for the desired catalytic activity is one of the key steps in mining metagenomic libraries, as it does not rely on sequence homology. In this mini‐review, we survey high‐throughput screening tools, originally developed for directed evolution experiments, which can be readily adapted for the screening of large libraries. In particular, we focus on the use of in vitro compartmentalization (IVC) approaches to address potential advantages and problems the merger of culture‐independent and IVC techniques might bring on the mining of enzyme activities in microbial communities.     

Seasonal climatic niches diverge in migratory birds

Migratory birds occupy different geographical areas during breeding and non-breeding periods, and thus different factors may determine their range limits depending on each season. One such factor is the spatial climatic component of the niche, which is widely used to model species distributions, yet the temporal component is often neglected and is generally assumed to be constant. We tested the hypothesis that the climatic niche is conserved between breeding and non-breeding areas in 355 bird species migrating through Eurasian–African flyways. For this, we performed niche overlap analyses and compared niche differences between sister or phylogenetically closely related species, as well as linking the differences to migratory distances. For more than 80% of the species, there was no or very little overlap between their breeding and non-breeding climatic niches. For most closely related species, the degree of overlap of their breeding climatic niches was larger than the overlap observed within each species, but not for their wintering climatic niches, suggesting a phylogenetic conservation of breeding climatic niches. Finally, there was a clear negative relationship between migratory distances and climatic niche overlap within each species. Our results confirmed that the climatic niche of most Eurasian–African migratory species differs between both breeding and non-breeding ranges, suggesting distinctive seasonal climatic requirements. Given these results and the geographically uneven effects of climate change, the impact of global change is likely to have different effects in each seasonal range. Hence, both breeding and non-breeding climatic data need to be considered when using species distribution models.