Size constraints of telemeters in rats

This study was designed to determine themaximum-size subcutaneous telemeter that would enable long-term andmultichannel data collection in a 170-g rat for 90 days. Inphase 1, rats with implants weighing 5 (2.5 cm³), 15 (7.5 cm³), 25 (12.5 cm³), 35 (17.5 cm³), or 45 (22.5 cm³) g were compared withsham-operated (SOC) and nonoperated (NOC) control animals. Severe skinlesions, seromas, and lower growth rates were observed in rats havingimplants 35 g. Thus, in phase 2,rats implanted with 23.5 g (17.5 cm³; 11-g active telemeter and12.5-g implant) were compared with rats implanted with 11 g (6 cm³; telemeter only) and with theSOC and NOC groups. No differences were found among implanted groups inmean arterial pressure (MAP), heart rate (HR), subcutaneoustemperature, or spontaneous activity under standard housing conditions.All groups were more active and had a higher MAP during the dark thanthe light phase of the daily cycle. During 2 h of cold exposure(3°C), both telemetered groups exhibited similar changes in HR,MAP, temperature, and activity levels. Adrenal glands were larger inthe 23.5-g group (51 ± 1.6 mg) than in the SOC (46 ± 1.0 mg)and the NOC groups (41 ± 2.0 mg). No other significant differenceswere found in organ, muscle, or bone weights. These data verify thefeasibility of using 23.5-g (17.5 cm³) subcutaneous telemeters forchronic recordings in young adult rats.

     

Preparations and properties of tripodal and linear tetradentate N,S-Donor ligands and their complexes containing the MoO22+core

New linear and tripodal tetradentate ligands, LH₂, are reported and their syntheses are described. The new linear ligands L = HSCH₂CH₂SCH₂CH₂NRCH₂CR₂SH, R = H, CH₃) and the new tripodal ligands N(CH₂CH₂SH)₂CH₂Z, Z = CH₂NH₂, CH₂N(CH₃)₂, CH₂N(C₂H₅)₂, CH₂SCH₃ and CO₂^- were synthesized. The known linear ligands HSCH₂CH₂NCH₃(CH₂)_nNCH₃CH₂CH₂SH (n = 2, 3) and HSCR₂CH₂NHCH₂CH₂NHCH₂CR₂SH (R = H, CH₃) were also utilized. These ligands react with MoO₂(acac)₂ in CH₃OH to yield MoO₂L complexes in high yield. Infra-red and ¹H nmr spectra provide evidence to supplement X-ray crystallographic results reported elsewhere for selected numbers of the series. Octahedral structures with cis MoO₂²⁺ groupings are assigned. Solution ¹H nmr studies are consistent with a trans placement of the two thiolate donors in agreement with the X-ray studies.     

Autophosphorylation: a salient feature of protein kinases

Most protein kinases catalyze autophosphorylation, a process which is generally intramolecular and is modulated by regulatory ligands. Either serine/threonine or tyrosine serves as the phosphoacceptor, and several sites on the same kinase subunit are usually autophosphorylated. Autophosphorylation affects the functional properties of most protein kinases. Members of the protein kinase family exhibit diversity in the characteristics and functions of autophosphorylation, but certain common themes are emerging.     

Adaptive gene expression divergence inferred from population genomics

Detailed studies of individual genes have shown that gene expression divergence often results from adaptive evolution of regulatory sequence. Genome-wide analyses, however, have yet to unite patterns of gene expression with polymorphism and divergence to infer population genetic mechanisms underlying expression evolution. Here, we combined genomic expression data—analyzed in a phylogenetic context—with whole genome light-shotgun sequence data from six Drosophila simulans lines and reference sequences from D. melanogaster and D. yakuba. These data allowed us to use molecular population genetics to test for neutral versus adaptive gene expression divergence on a genomic scale. We identified recent and recurrent adaptive evolution along the D. simulans lineage by contrasting sequence polymorphism within D. simulans to divergence from D. melanogaster and D. yakuba. Genes that evolved higher levels of expression in D. simulans have experienced adaptive evolution of the associated 3′ flanking and amino acid sequence. Concomitantly, these genes are also decelerating in their rates of protein evolution, which is in agreement with the finding that highly expressed genes evolve slowly. Interestingly, adaptive evolution in 5′ cis-regulatory regions did not correspond strongly with expression evolution. Our results provide a genomic view of the intimate link between selection acting on a phenotype and associated genic evolution.     

Parallel Geographic Variation in Drosophila melanogaster

Drosophila melanogaster, an ancestrally African species, has recently spread throughout the world, associated with human activity. The species has served as the focus of many studies investigating local adaptation relating to latitudinal variation in non-African populations, especially those from the United States and Australia. These studies have documented the existence of shared, genetically determined phenotypic clines for several life history and morphological traits. However, there are no studies designed to formally address the degree of shared latitudinal differentiation at the genomic level. Here we present our comparative analysis of such differentiation. Not surprisingly, we find evidence of substantial, shared selection responses on the two continents, probably resulting from selection on standing ancestral variation. The polymorphic inversion In(3R)P has an important effect on this pattern, but considerable parallelism is also observed across the genome in regions not associated with inversion polymorphism. Interestingly, parallel latitudinal differentiation is observed even for variants that are not particularly strongly differentiated, which suggests that very large numbers of polymorphisms are targets of spatially varying selection in this species.     

Allosteric sites of phosphodiesterase-5 (PDE5). A potential role in negative feedback regulation of cGMP signaling in corpus cavernosum.

To date, relative cellular levels of cGMP and cGMP-binding proteins have not been considered important in the regulation of smooth muscle or any other tissue. In rabbit penile corpus cavernosum, intracellular cGMP was determined to be 18 +/- 4 nM, whereas the cGMP-binding sites of types Ialpha and Ibeta cGMP-dependent protein kinase (PKG) and cGMP-binding cGMP-specific phosphodiesterase (PDE5) were 58 +/- 14 nM and 188 +/- 6 nM, respectively, as estimated by two different methods for each protein. Thus, total cGMP-binding sites (246 nM) greatly exceed total cGMP. Given this excess of cGMP-binding sites and the high affinities of PKG and PDE5 for cGMP, it is likely that a large portion of intracellular cGMP is associated with these proteins, which could provide a dynamic reservoir for cGMP. Phosphorylation of PDE5 by PKG is known to increase the affinity of PDE5 allosteric sites for cGMP, suggesting the potential for regulation of a reservoir of cGMP bound to this protein. Enhanced binding of cGMP by phosphorylated PDE5 could reduce the amount of cGMP available for activation of PKG, contributing to feedback inhibition of smooth muscle relaxation or other processes. This introduces a new concept for cyclic nucleotide signaling.     

Biotic resistance to invasion is ubiquitous across ecosystems of the United States

The biotic resistance hypothesis predicts that diverse native communities are more resistant to invasion. However, past studies vary in their support for this hypothesis due to an apparent contradiction between experimental studies, which support biotic resistance, and observational studies, which find that native and non‐native species richness are positively related at broad scales (small‐scale studies are more variable). Here, we present a novel analysis of the biotic resistance hypothesis using 24 456 observations of plant richness spanning four community types and seven ecoregions of the United States. Non‐native plant occurrence was negatively related to native plant richness across all community types and ecoregions, although the strength of biotic resistance varied across different ecological, anthropogenic and climatic contexts. Our results strongly support the biotic resistance hypothesis, thus reconciling differences between experimental and observational studies and providing evidence for the shared benefits between invasive species management and native biodiversity conservation.     

AIR: A batch-oriented web program package for construction of supermatrices ready for phylogenomic analyses

Background  

Large multigene sequence alignments have over recent years been increasingly employed for phylogenomic reconstruction of the eukaryote tree of life. Such supermatrices of sequence data are preferred over single gene alignments as they contain vastly more information about ancient sequence characteristics, and are thus more suitable for resolving deeply diverging relationships. However, as alignments are expanded, increasingly numbers of sites with misleading phylogenetic information are also added. Therefore, a major goal in phylogenomic analyses is to maximize the ratio of information to noise; this can be achieved by the reduction of fast evolving sites.