Can spatial sorting associated with spawning migration explain evolution of body size and vertebral number in Anguilla eels?

Spatial sorting is a process that can contribute to microevolutionary change by assembling phenotypes through space, owing to nonrandom dispersal. Here we first build upon and develop the “neutral” version of the spatial sorting hypothesis by arguing that in systems that are not characterized by repeated range expansions, the evolutionary effects of variation in dispersal capacity and assortative mating might not be independent of but interact with natural selection. In addition to generating assortative mating, variation in dispersal capacity together with spatial and temporal variation in quality of spawning area is likely to influence both reproductive success and survival of spawning migrating individuals, and this will contribute to the evolution of dispersal‐enhancing traits. Next, we use a comparative approach to examine whether differences in spawning migration distance among 18 species of freshwater Anguilla eels have evolved in tandem with two dispersal‐favoring traits. In our analyses, we use information on spawning migration distance, body length, and vertebral number that was obtained from the literature, and a published whole mitochondrial DNA‐based phylogeny. Results from comparative analysis of independent contrasts showed that macroevolutionary shifts in body length throughout the phylogeny have been associated with concomitant shifts in spawning migration. Shifts in migration distance were not associated with shifts in number of vertebrae. These findings are consistent with the hypothesis that spatial sorting has contributed to the evolution of more elongated bodies in species with longer spawning migration distances, or resulted in evolution of longer migration distances in species with larger body size. This novel demonstration is important in that it expands the list of ecological settings and hierarchical levels of biological organization for which the spatial sorting hypothesis seems to have predictive power.     

New Type of Papillomavirus and Novel Circular Single Stranded DNA Virus Discovered in Urban Rattus norvegicus Using Circular DNA Enrichment and Metagenomics

Rattus norvegicus (R. norvegicus) are ubiquitous and their presence has several effects on the human populations in our urban areas on a global scale. Both historically and presently, this close interaction has facilitated the dissemination of many pathogens to humans, making screening for potentially zoonotic and emerging viruses in rats highly relevant. We have investigated faecal samples from R. norvegicus collected from urban areas using a protocol based on metagenomic enrichment of circular DNA genomes and subsequent sequencing. We found a new type of papillomavirus, with a L1 region 82% identical to that of the known R. norvegicus Papillomavirus 2. Additionally, we found 20 different circular replication associated protein (Rep)-encoding single stranded DNA (CRESS-DNA) virus-like genomes, one of which has homology to the replication-associated gene of Beak and feather disease virus. Papillomaviruses are a group of viruses known for their carcinogenic potential, and although they are known to infect several different vertebrates, they are mainly studied and characterised in humans. CRESS-DNA viruses are found in many different environments and tissue types. Both papillomaviruses and CRESS-DNA viruses are known to have pathogenic potential and screening for novel and known viruses in R. norvegicus could help identify viruses with pathogenic potential.     

A Longitudinal Study of Disability,Cognition and Gray Matter Atrophy in Early Multiple Sclerosis Patients According to Evidence of Disease Activity

New treatment options may make “no evidence of disease activity” (NEDA: no relapses or disability progression and no new/enlarging MRI lesions, as opposed to “evidence of disease activity” (EDA) with at least one of the former), an achievable goal in relapsing-remitting multiple sclerosis (RRMS). The objective of the present study was to determine whether early RRMS patients with EDA at one-year follow-up had different disability, cognition, treatment and gray matter (GM) atrophy rates from NEDA patients and healthy controls (HC). RRMS patients (mean age 34 years, mean disease duration 2.2 years) were examined at baseline and one-year follow-up with neurological (n = 72), neuropsychological (n = 56) and structural MRI (n = 57) examinations. Matched HC (n = 61) were retested after three years. EDA was found in 46% of RRMS patients at follow-up. EDA patients used more first line and less second line disease modifying treatment than NEDA (p = 0.004). While the patients groups had similar disability levels at baseline, they differed in disability at follow-up (p = 0.010); EDA patients progressed (EDSS: 1.8–2.2, p = 0.010), while NEDA patients improved (EDSS: 2.0–1.7, p<0.001). Cognitive function was stable in both patient groups. Subcortical GM atrophy rates were higher in EDA patients than HC (p<0.001). These results support the relevance of NEDA as outcome in RRMS and indicate that pathological neurodegeneration in RRMS mainly occur in patients with evidence of disease activity.     

Metabolites in Blood for Prediction of Bacteremic Sepsis in the Emergency Room

A metabolomics approach for prediction of bacteremic sepsis in patients in the emergency room (ER) was investigated. In a prospective study, whole blood samples from 65 patients with bacteremic sepsis and 49 ER controls were compared. The blood samples were analyzed using gas chromatography coupled to time-of-flight mass spectrometry. Multivariate and logistic regression modeling using metabolites identified by chromatography or using conventional laboratory parameters and clinical scores of infection were employed. A predictive model of bacteremic sepsis with 107 metabolites was developed and validated. The number of metabolites was reduced stepwise until identifying a set of 6 predictive metabolites. A 6-metabolite predictive logistic regression model showed a sensitivity of 0.91(95% CI 0.69–0.99) and a specificity 0.84 (95% CI 0.58–0.94) with an AUC of 0.93 (95% CI 0.89–1.01). Myristic acid was the single most predictive metabolite, with a sensitivity of 1.00 (95% CI 0.85–1.00) and specificity of 0.95 (95% CI 0.74–0.99), and performed better than various combinations of conventional laboratory and clinical parameters. We found that a metabolomics approach for analysis of acute blood samples was useful for identification of patients with bacteremic sepsis. Metabolomics should be further evaluated as a new tool for infection diagnostics.     

Metabolism of carbon tetrachloride to phosgene

Aerobic incubation of hepatic microsomal fractions in the presence of carbon tetrachloride, NADPH and cysteine resulted in the formation of phosgene which was identified by gas chromatography/mass spectrometry as the adduct, 2-oxothiazolidine-4-carboxylic acid, formed by its reaction with cysteine. [¹³C]-Carbon tetrachloride was metabolized to 2-[¹³C]-oxothiazolidine-4-carboxylic acid the , when carbon tetrachloride was incubated in the presence of [¹⁸O]-O₂, 2- [¹⁸O]-oxothiazolidine-4-carboxylic acid was formed. The reaction was inhibited by carbon monoxide showing the involvement of the cytochrome P-450-dependent mixed function oxidase system. The metabolism of carbon tetrachloride to phosgene may play a role in the production of hepatotoxicity by this compound.     

Recognition of influenza virus hemagglutinin by subtype-specific and cross-reactive proliferative T cells: contribution of HA1 and HA2 polypeptide chains

The recognition of influenza virus hemagglutinin (HA) by T lymphocytes was examined by assaying the T cell proliferative response of influenza virus-primed T cells to purified HA of different influenza A subtypes or to isolated heavy (HA1) or light (HA2) polypeptide chains of the HA molecule. The proliferative response to HA was dependent on the activation of an Ly-1+2- subset of T cells and required the presence of nylon wool-adherent, radiation-resistant accessory cells. T cells from mice primed by infection with one strain of type A influenza virus cross-reacted with other purified HA not only of the same subtype as the priming virus but also of serologically distinct subtypes of influenza A (but not B) virus. The response of virus-primed T cells to the homologous HA or to HA of the same subtype was shown to involve recognition of determinants on both the HA1 and the HA2 chains. The recognition of HA of different subtype by cross-reactive T cells appeared to be directed predominantly to determinants on HA2. Because the antibody response to influenza virus HA is not cross-reactive between subtypes and is directed predominantly to determinants on HA1, the present results indicate that at least some of the determinants on HA recognized by T cells are different from those recognized by B cells and that the HA2 chain may be involved primarily in stimulation of T cell rather than B cell immunity.     

Chromosomal location and cloning of the gene (trmD) responsible for the synthesis of tRNA (m1G) methyltransferase in Escherichia coli K-12

Summary The trmD gene, which governs the formation of 1-methyl-guanosine (m¹G) in transfer ribonucleic acid (tRNA), has been located by phage P1 transduction at 56 min on the chromosomal map of Escherichia coli. Cotransduction to tyrA at 56 min is 80%. From the Clarke and Carbon collection a ColE1-tyrA ⁺ hybrid plasmid was isolated, which carried the trmD ⁺ gene and was shown to over-produce the tRNA (m¹G)methyltransferase. By subcloning restriction enzyme fragments in vitro, the trmD ⁺ gene was located to a 3.4 kb DNA fragment 6.5 kb clockwise from the tyrA ⁺ gene. The mutation trmD1, which renders the tRNA (m¹G) methyltransferase temperaturesensitive both in vivo and in vitro could be complemented by trmD ⁺ plasmids. These results suggest that the gene trmD ⁺ is the structural gene for the tRNA (m¹G)methyltransferase (EC 2.1.1.3.1).