Origin of life in a digital microcosm

While all organisms on Earth descend from a common ancestor, there is no consensus on whether the origin of this ancestral self-replicator was a one-off event or whether it was only the final survivor of multiple origins. Here we use the digital evolution system Avida to study the origin of self-replicating computer programs. By using a computational system, we avoid many of the uncertainties inherent in any biochemical system of self-replicators (while running the risk of ignoring a fundamental aspect of biochemistry). We generated the exhaustive set of minimal-genome self-replicators and analyzed the network structure of this fitness landscape. We further examined the evolvability of these self-replicators and found that the evolvability of a self-replicator is dependent on its genomic architecture. We studied the differential ability of replicators to take over the population when competed against each other (akin to a primordial-soup model of biogenesis) and found that the probability of a self-replicator out-competing the others is not uniform. Instead, progenitor (most-recent common ancestor) genotypes are clustered in a small region of the replicator space. Our results demonstrate how computational systems can be used as test systems for hypotheses concerning the origin of life.Comment: 20 pages, 7 figures. To appear in special issue of Philosophical Transactions of the Royal Society A: Re-Conceptualizing the Origins of Life from a Physical Sciences Perspectiv

Indirect study of 19Ne states near the 18F+p threshold

The early E < 511 keV gamma-ray emission from novae depends critically on the 18F(p,a)15O reaction. Unfortunately the reaction rate of the 18F(p,a)15O reaction is still largely uncertain due to the unknown strengths of low-lying proton resonances near the 18F+p threshold which play an important role in the nova temperature regime. We report here our last results concerning the study of the d(18F,p)19F(alpha)15N transfer reaction. We show in particular that these two low-lying resonances cannot be neglected. These results are then used to perform a careful study of the remaining uncertainties associated to the 18F(p,a)15O and 18F(p,g)19Ne reaction rates.Comment: 18 pages, 8 figures. Accepted in Nuclear Physics

Population mixing and incidence of cancers in adolescents and young adults between 1990 and 2013 in Yorkshire, UK

Purpose: Epidemiological evidence suggests a role for an infectious etiology for cancers in teenagers and young adults (TYAs). We investigated this by describing associations between infection transmission using the population mixing (PM) proxy and incidence of cancers in TYAs in Yorkshire, UK. Methods: We extracted cancer cases from the Yorkshire Specialist Register of Cancer in Children and Young People from 1990 to 2013 (n = 1929). Using multivariable Poisson regression models (adjusting for effects of deprivation and population density), we investigated whether PM was associated with cancer incidence. We included population mixing–population density interaction terms to examine for differences in effects of PM in urban and rural populations. Results: Nonsignificant IRRs were observed for leukemias (IRR 1.20, 95% CI 0.91–1.59), lymphomas (IRR 1.09, 95% CI 0.90–1.32), central nervous system tumors (IRR 1.06, 95% CI 0.80–1.40) and germ cell tumors (IRR 1.14, 95% CI 0.92–1.41). The association between PM and cancer incidence did not vary in urban and rural areas. Conclusions: Study results suggest PM is not associated with incidence of cancers among TYAs. This effect does not differ between rural and urban settings

Within-Season Homing Movements of Displaced Mature Sunapee Trout (Salvelinus Alpinus) in Floods Pond, Maine

Tagging, displacemenat nd recapture, and ultrasonict racking of displaced mature Sunapee trout (Salvelinusa Ipinus) in Floods Pond, Maine, demonstrated that rapid within-season homing occurs in this relict form of Arctic char. Of the trout displaced about 1.8 km from their spawning ground from 1972 to 1975, 9% to 32% were recaptured one to four times within the same spawning season in trap nets set on the spawning ground. Eight of 14 trout tracked ultrasonically in 1975 homed in 2.5 to 10.0 h. Movements of the homing fish were variable; some trout homed paralleling the shoreline, others homed in open water or used a combination of near-shore and open-water movements. Behavior was similar between the sexes and during day and night, although two fish did begin to move just at sundown. Swimming speeds ranged from 15 to 35 cm s- 1 and averaged about 0 .6 body lengths s -1•. Swimming directions were not influenced by wind and wave direction, nor were swimming speeds within individual tracks influenced by cloud cover, wave height, or water depth. Heavy overcast at night m&y have inhibited movement. Sunapee trout are apparently familiar with the entire lake and travel widely within it. Visual features are postulated as orientational cues, though use of such cues is not clearly demonstrated by our experiments

Negative emotional stimuli reduce contextual cueing but not response times in inefficient search

In visual search, previous work has shown that negative stimuli narrow the focus of attention and speed reaction times (RTs). This paper investigates these two effects by first asking whether negative emotional stimuli narrow the focus of attention to reduce the learning of a display context in a contextual cueing task and, second, whether exposure to negative stimuli also reduces RTs in inefficient search tasks. In Experiment 1, participants viewed either negative or neutral images (faces or scenes) prior to a contextual cueing task. In a typical contextual cueing experiment, RTs are reduced if displays are repeated across the experiment compared with novel displays that are not repeated. The results showed that a smaller contextual cueing effect was obtained after participants viewed negative stimuli than when they viewed neutral stimuli. However, in contrast to previous work, overall search RTs were not faster after viewing negative stimuli (Experiments 2 to 4). The findings are discussed in terms of the impact of emotional content on visual processing and the ability to use scene context to help facilitate search

A New Species of \u3ci\u3eCelastrina\u3c/i\u3e from the Northwestern United States and Southwestern Canada with a Lectotype Designation of \u3ci\u3eLycaena pseudargiolus\u3c/i\u3e var. \u3ci\u3enigrescens\u3c/i\u3e Fletcher (Lycaenidae: Polyommatinae)

A new western azure species, Celastrina asheri, is described from the northwestern United States and southwestern Canada. A lectotype is designated for Lycaena pseudargiolus var. nigrescens Fletcher, 1903 to secure the identity of that name. C. asheri broadly overlaps with the northeastern range of C. echo (W. H. Edwards, 1864) but is usually very distinct from that species. C. lucia (W. Kirby, 1837) is narrowly sympatric with C. asheri in British Columbia, the southwest corner of Alberta and along the Rocky Mountains in Montana. As far as is known, C. asheri uses only red osier dogwood (Cornus sericea) and possibly oceanspray (Holodiscus discolor) as larval foodplants, while C. echo and C. lucia use a wide variety of larval foodplants. A lack of past research and confusion as a “form” of C. echo obscured the identity of C. asheri

Neural correlates of enhanced visual short-term memory for angry faces: An fMRI study

Copyright: © 2008 Jackson et al.Background: Fluid and effective social communication requires that both face identity and emotional expression information are encoded and maintained in visual short-term memory (VSTM) to enable a coherent, ongoing picture of the world and its players. This appears to be of particular evolutionary importance when confronted with potentially threatening displays of emotion - previous research has shown better VSTM for angry versus happy or neutral face identities.Methodology/Principal Findings: Using functional magnetic resonance imaging, here we investigated the neural correlates of this angry face benefit in VSTM. Participants were shown between one and four to-be-remembered angry, happy, or neutral faces, and after a short retention delay they stated whether a single probe face had been present or not in the previous display. All faces in any one display expressed the same emotion, and the task required memory for face identity. We find enhanced VSTM for angry face identities and describe the right hemisphere brain network underpinning this effect, which involves the globus pallidus, superior temporal sulcus, and frontal lobe. Increased activity in the globus pallidus was significantly correlated with the angry benefit in VSTM. Areas modulated by emotion were distinct from those modulated by memory load.Conclusions/Significance: Our results provide evidence for a key role of the basal ganglia as an interface between emotion and cognition, supported by a frontal, temporal, and occipital network.The authors were supported by a Wellcome Trust grant (grant number 077185/Z/05/Z) and by BBSRC (UK) grant BBS/B/16178

Whole genome sequencing reveals high clonal diversity of Escherichia coli isolated from patients in a tertiary care hospital in Moshi, Tanzania

Abstract Background Limited information regarding the clonality of circulating E. coli strains in tertiary care hospitals in low and middle-income countries is available. The purpose of this study was to determine the serotypes, antimicrobial resistance and virulence genes. Further, we carried out a phylogenetic tree reconstruction to determine relatedness of E. coli isolated from patients in a tertiary care hospital in Tanzania. Methods E. coli isolates from inpatients admitted at Kilimanjaro Christian Medical Centre between August 2013 and August 2015 were fully genome-sequenced at KCMC hospital. Sequence analysis was done for identification of resistance genes, Multi-Locus Sequence Typing, serotyping, and virulence genes. Phylogeny reconstruction using CSI Phylogeny was done to ascertain E. coli relatedness. Stata 13 (College Station, Texas 77,845 USA) was used to determine Cohen’s kappa coefficient of agreement between the phenotypically tested and whole genome sequence predicted antimicrobial resistance. Results Out of 38 E. coli isolates, 21 different sequence types (ST) were observed. Eight (21.1%) isolates belonged to ST131; of which 7 (87.5.%) were serotype O25:H4. Ten (18.4%) isolates belonged to ST10 clonal complex; of these, four (40.0%) were ST617 with serotype O89:H10. Twenty-eight (73.7%) isolates carried genes encoding beta-lactam resistance enzymes. On average, agreement across all drugs tested was 83.9%. Trimethoprim/sulphamethoxazole (co-trimoxazole) showed moderate agreement: 45.8%, kappa =15% and p = 0.08. Amoxicillin-clavulanate showed strongest agreement: 87.5%, kappa = 74% and p = 0.0001. Twenty-two (57.9%) isolates carried virulence factors for host cells adherence and 25 (65.7%) for factors that promote E. coli immune evasion by increasing survival in serum. The phylogeny analysis showed that ST131 clustering close together whereas ST10 clonal complex had a very clear segregation of the ST617 and a mix of the rest STs. Conclusion There is a high diversity of E. coli isolated from patients admitted to a tertiary care hospital in Tanzania. This underscores the necessity to routinely screen all bacterial isolates of clinical importance in tertiary health care facilities. WGS use for laboratory-based surveillance can be an effective early warning system for emerging pathogens and resistance mechanisms in LMICs

How Emotion Strengthens the Recollective Experience: A Time-Dependent Hippocampal Process

Emotion significantly strengthens the subjective recollective experience even when objective accuracy of the memory is not improved. Here, we examine if this modulation is related to the effect of emotion on hippocampal-dependent memory consolidation. Two critical predictions follow from this hypothesis. First, since consolidation is assumed to take time, the enhancement in the recollective experience for emotional compared to neutral memories should become more apparent following a delay. Second, if the emotion advantage is critically dependent on the hippocampus, then the effects should be reduced in amnesic patients with hippocampal damage. To test these predictions we examined the recollective experience for emotional and neutral photos at two retention intervals (Experiment 1), and in amnesics and controls (Experiment 2). Emotional memories were associated with an enhancement in the recollective experience that was greatest after a delay, whereas familiarity was not influenced by emotion. In amnesics with hippocampal damage the emotion effect on recollective experience was reduced. Surprisingly, however, these patients still showed a general memory advantage for emotional compared to neutral items, but this effect was manifest primarily as a facilitation of familiarity. The results support the consolidation hypothesis of recollective experience, but suggest that the effects of emotion on episodic memory are not exclusively hippocampally mediated. Rather, emotion may enhance recognition by facilitating familiarity when recollection is impaired due to hippocampal damage

Biodiversity Studies for Sustainable Lagoon: Thermophilic and Tropical Fish Species vs. Endemic Commercial Species at Mellah Lagoon (Mediterranean, Algeria)

Lagoons play an important socio-economic role and represent a precious natural heritage at risk from fishing pressure and chemical and biological pollution. Our research focused on better understanding the discrimination of fish biodiversity, the detection of non-indigenous species, and the valorization of commercial indigenous species at Mellah lagoon (Algeria). Taxonomic characterization and barcoding for all fish species and Inkscape schematic drawings for the most common species are provided. A total of 20 families and 37 species were recorded. The thermophilic species Coris julis, Thalassoma pavo, and Aphanius fasciatus and tropical species such as Gambusia holbrooki and Parablennius pilicornis were identified. Numerous Mediterranean species of socio-economic importance are highlighted, and detailed information is summarized for the lagoon’s sustainability. This short-term evaluation goes hand in hand with long-term programs documenting the interaction between indigenous and non-indigenous species in the lagoon and will allow the development of a provisional relationship model for future studies. Thermophilic and tropical species patterns in the Mellah lagoon are presented. Taken together, we provide useful data that can guide future investigations and may become a potential management tool for achieving the Sustainable Development Goals and protecting species with large socio-economic roles from potential thermal stress impact