Species concepts and the determination of historic gene flow patterns in the Eulemur fulvus (Brown Lemur) complex

Eulmur fulvus , a complex comprising six subspecies, is a classic example of species status conferred through evolutionary taxonomy. We used the phylogcnctic species concept as an alternative method to the biological species concept for determining historic patterns of gene flow between the various E. julvus subspecies and for conferring species status. In this paper, we used population aggregation analysis to determine the proper species partitions and cladistic analysis to reconstruct the evolutionary relationships of the different populations in the Eulemur fulvus complex. We sequenced three mtDNA gene regions (d-loop, 12S, and cyt-b) and one nuclear region, casein kinase, for a total of 1247 bases. Through population aggregation analysis, we determined that the E. fulvus complex should be split into three units; one unit supported by six diagnostic sites comprising E.f. albocollans , one unit supported by three diagnostic sites comprising E.f. collaris , and one unit supported by two diagnostic sites comprising the four other subspecies. Although all six subspecies in the E. julvus complex share a common ancestor, we found in our cladistic analysis that E. J. collaris and E. j. albocollans share a common ancestor that more recently split off from the common ancestor of the four other E. fulvus subspecies.     

G Protein-Coupled Receptors in and on the Cell Nucleus: A New Signaling Paradigm?

Signaling from internalizing and endosomal receptors has almost become a classic GPCR paradigm in the last several years. However, it has become clear in recent years that GPCRs also elicit signals when resident at other subcellular sites including the endoplasmic reticulum, Golgi apparatus, and the nucleus. In this review we discuss the nature, function, and trafficking of nuclear GPCR signaling complexes, as well as potential sources of endogenous and exogenous ligands. Finally, we pose a series of questions that will need to be answered in the coming years to confirm and extend this as a new paradigm for GPCR signaling.     

Influence of the SNPs on the structural stability of CBS protein： Insight from molecular dynamics simulations

Cystathionine β-synthase is an essential enzyme of the trans-suifuration pathway that condenses serine with homocysteine to form cystathionine. Missense mutations in CBS are the major cause of inherited homocystinuria, and the detailed effect of disease associated amino acid substitutions on the structure and stability of human CBS is yet unknown. Here, we apply a unique approach in combining in silico tools and molecular dynamics simulation to provide structural and functional insight into the effect of SNP on the stability and activity of mutant CBS. In addition, principal component analysis and free energy landscape were used to predict the collective motions, thermodynamic stabilities and essential subspace relevant to CBS function. The obtained results indicate that C109R, E176K and D376N mutations have the diverse effect on dynamic behavior of CBS protein. We found that highly conserved D376N mutation, which is present in the active pocket, affects the protein folding mechanism. Our strategy may provide a way in near future to understand and study effects of functional nsSNPs and their role in causing homocystinuria.     

Addressing the influence of instrument surface heat exchange on the measurements of CO2 flux from open-path gas analyzers

There is a growing concern in the flux community that using the eddy covariance method with open‐path CO₂ analyzers often leads to measurements of an apparent ecosystem CO₂ uptake during off‐season periods, especially in cold climates. Such uptake has not been observed when measurements were made with closed‐path analyzers, chambers, or profile methods, suggesting it is an artifact due in some way to the use of open‐path analyzers. In this study, a series of laboratory tests and field experiments were conducted to determine the magnitude of the instrument surface heat exchange in the open path and its relationship with the measured CO₂ flux. Results showed that (1) the surface of an open‐path instrument became substantially warmer than ambient due to electronics and radiation load during daytime, while at night, radiative cooling moderated temperature increases in the path; (2) high‐frequency temperature measurements inside the path were correlated with vertical wind speed producing sensible heat flux inside the instrument path exceeding the ambient heat flux by up to 14%; (3) enclosing the open‐path instrument eliminated the sensible heat flux in the path, and caused measured CO₂ flux to match a closed‐path reference; (4) using sensible heat flux measured directly inside the open path in the WPL term instead of the ambient sensible heat flux also led to a match in CO₂ flux between open‐path instrument and closed‐path reference; and (5) correcting previously collected open‐path CO₂ flux data was possible by estimating the instrument heating effect with a semi‐empirical model using standard weather variables. Results showed that all proposed techniques led to a significant reduction in apparent CO₂ uptake during off‐season periods and to a reduction of the underestimation of CO₂ release in other periods. Close agreement between the open‐path measurements and closed‐path references was achieved in all cases.     

Neumann’s Warbler Hemitesia neumanni (Sylvioidea): the sole African member of a Palaeotropic Miocene avifauna

We present molecular evidence that Neumann’s Warbler Hemitesia neumanni is deeply nested within the Cettiidae. The species’ distribution in the Albertine Rift of East Africa is intriguing, as the family Cettiidae is principally an Asian radiation. This disjunct distribution could be a result of colonization of Africa by long‐distance dispersal, or the Cettiidae may at some point in the past have had a much larger geographical distribution that also covered parts of Africa.     

Metabolic Scaling: A New Perspective Based on Scaling of Glycolytic Enzyme Activities

The decline of mass specific aerobic metabolic rates with increasinganimal size has a long history of study in zoology. Attemptsto explain this phenomenon have generally been concerned onlywith aerobic metabolism and with estimators of muscle and skeletalstrength. Our finding of tremendous increases in mass-specificglycolytic enzyme activity in locomotory muscle with size insome species of pelagic fishes indicates that this approachhas been too narrow. It is necessary to consider total metabolicpower in any consideration of metabolic scaling in relationto skeletal strength or muscle power, since the anaerobic componentof muscle power is usually greater than the aerobic and oftenscales differently. We show that scaling of glycolytic powerappears to be much more variable among species than is scalingof aerobic power, and we suggest that the different glycolyticpower scaling patterns reflect selection for different sprintswimming abilities in fishes of different habits. The rathernarrow range of variation in aerobic scaling patterns suggeststhat they are the result of natural selection acting in thecontext of geometric constraints on maximum aerobic gas uptakeand transport. The glycolytic scaling data emphasize that therole of natural selection has usually been neglected in considerationsof scaling of metabolism while the role of the scaling of solidshas been overemphasized.