2,817 research outputs found
Neurospora from natural populations: Population genomics insights into the Life history of a model microbial Eukaryote
The ascomycete filamentous fungus Neurospora crassa played a historic role in experimental biology and became a model system for genetic research. Stimulated by a systematic effort to collect wild strains initiated by Stanford geneticist David Perkins, the genus Neurospora has also become a basic model for the study of evolutionary processes, speciation, and population biology. In this chapter, we will first trace the history that brought Neurospora into the era of population genomics. We will then cover the major contributions of population genomic investigations using Neurospora to our understanding of microbial biogeography and speciation, and review recent work using population genomics and genome-wide association mapping that illustrates the unique potential of Neurospora as a model for identifying the genetic basis of (potentially adaptive) phenotypes in filamentous fungi. The advent of population genomics has contributed to firmly establish Neurospora as a complete model system and we hope our review will entice biologists to include Neurospora in their research
Development and Validation of the Behavioral Tendencies Questionnaire
At a fundamental level, taxonomy of behavior and behavioral tendencies can be described
in terms of approach, avoid, or equivocate (i.e., neither approach nor avoid). While there are
numerous theories of personality, temperament, and character, few seem to take advantage
of parsimonious taxonomy. The present study sought to implement this taxonomy by
creating a questionnaire based on a categorization of behavioral temperaments/tendencies
first identified in Buddhist accounts over fifteen hundred years ago. Items were developed
using historical and contemporary texts of the behavioral temperaments, described as
“Greedy/Faithful”, “Aversive/Discerning”, and “Deluded/Speculative”. To both maintain
this categorical typology and benefit from the advantageous properties of forced-choice
response format (e.g., reduction of response biases), binary pairwise preferences for items
were modeled using Latent Class Analysis (LCA). One sample (n1 = 394) was used to estimate
the item parameters, and the second sample (n2 = 504) was used to classify the participants
using the established parameters and cross-validate the classification against
multiple other measures. The cross-validated measure exhibited good nomothetic span
(construct-consistent relationships with related measures) that seemed to corroborate the
ideas present in the original Buddhist source documents. The final 13-block questionnaire
created from the best performing items (the Behavioral Tendencies Questionnaire or BTQ)
is a psychometrically valid questionnaire that is historically consistent, based in behavioral
tendencies, and promises practical and clinical utility particularly in settings that teach and
study meditation practices such as Mindfulness Based Stress Reduction (MBSR)
"May I Buy a Pack of Marlboros, Please?" A Systematic Review of Evidence to Improve the Validity and Impact of Youth Undercover Buy Inspections
Most smokers become addicted to tobacco products before they are legally able to pur- chase these products. We systematically reviewed the literature on protocols to assess underage purchase and their ecological validity. We conducted a systematic search in May 2015 in PubMed and PsycINFO. We independently screened records for inclusion. We con- ducted a narrative review and examined implications of two types of legal authority for proto- cols that govern underage buy enforcement in the United States: criminal (state-level
laws prohibiting sales to youth) and administrative (federal regulations prohibiting sales to youth). Ten studies experimentally assessed underage buy protocols and 44 studies assessed the association between youth characteristics and tobacco sales. Protocols that mimicked real-world youth behaviors were consistently associated with substantially greater likelihood of a sale to a youth. Many of the tested protocols appear to be designed for compliance with criminal law rather than administrative enforcement in ways that limited ecological validity. This may be due to concerns about entrapment. For administrative enforcement in particular, entrapment may be less of an issue than commonly thought. Commonly used underage buy protocols poorly represent the reality of youths' access to tobacco from retailers. Compliance check programs should allow youth to present them- selves naturally and attempt to match the community’s demographic makeup
Genetic Interactions between Chromosomes 11 and 18 Contribute to Airway Hyperresponsiveness in Mice
We used two-dimensional quantitative trait locus analysis to identify interacting genetic loci that contribute to the native airway constrictor hyperresponsiveness to methacholine that characterizes A/J mice, relative to C57BL/6J mice. We quantified airway responsiveness to intravenous methacholine boluses in eighty-eight (C57BL/6J X A/J) F2 and twenty-seven (A/J X C57BL/6J) F2 mice as well as ten A/J mice and six C57BL/6J mice; all studies were performed in male mice. Mice were genotyped at 384 SNP markers, and from these data two-QTL analyses disclosed one pair of interacting loci on chromosomes 11 and 18; the homozygous A/J genotype at each locus constituted the genetic interaction linked to the hyperresponsive A/J phenotype. Bioinformatic network analysis of potential interactions among proteins encoded by genes in the linked regions disclosed two high priority subnetworks - Myl7, Rock1, Limk2; and Npc1, Npc1l1. Evidence in the literature supports the possibility that either or both networks could contribute to the regulation of airway constrictor responsiveness. Together, these results should stimulate evaluation of the genetic contribution of these networks in the regulation of airway responsiveness in humans
Rethinking Serious Games Design in the Age of COVID-19: Setting the Focus on Wicked Problems
We live in a complex world, in which our existence is defined by forces that we cannot fully comprehend, predict, nor control. This is the world of wicked problems, of which the situation triggered by the COVID-19 pandemic is a notable example. Wicked problems are complex scenarios defined by the interplay of multiple environmental, social and economic factors. They are everchanging, and largely unpredictable and uncontrollable. As a consequence, wicked problems cannot be definitively solved through traditional problem-solving approaches. Instead, they should be iteratively managed, recognizing and valuing our connectedness with each other and the environment, and engaging in joint thinking and action to identify and pursue the common good. Serious games can be key to foster wicked problem management abilities. To this end, they should engage players in collective activities set in contexts simulating real-world wicked problem scenarios. These should require the continuous interpretation of changing circumstances to identify and pursue shared goals, promoting the development of knowledge, attitudes and skill sets relevant to tackle real-world situations. In this paper we outline the nature, implications and challenges of wicked problems, highlighting why games should be leveraged to foster wicked problem management abilities. Then, we propose a theory-based framework to support the design of games for this purpose
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Localisation and origin of the bacteriochlorophyll-derived photosensitizer in the retina of the deep-sea dragon fish Malacosteus niger
Most deep-sea fish have a single visual pigment maximally sensitive at short wavelengths, approximately matching the spectrum of both downwelling sunlight and bioluminescence. However, Malcosteus niger produces far-red bioluminescence and its longwave retinal sensitivity is enhanced by red-shifted visual pigments, a longwave reflecting tapetum and, uniquely, a bacteriochlorophyllderived photosensitizer. The origin of the photosensitizer, however, remains unclear. We investigated whether the bacteriochlorophyll was produced by endosymbiotic bacteria within unusual structures adjacent to the photoreceptors that had previously been described in this species. However, microscopy, elemental analysis and SYTOX green staining provided no evidence for such localised retinal bacteria, instead the photosensitizer was shown to be distributed throughout the retina. Furthermore, comparison of mRNA from the retina of Malacosteus to that of the closely related Pachystomias microdon (which does not contain a bacterichlorophyll-derived photosensitzer) revealed no genes of bacterial origin that were specifically up-regulated in Malacosteus. Instead up-regulated Malacosteus genes were associated with photosensitivity and may relate to its unique visual ecology and the chlorophyll-based visual system. We also suggest that the unusual longwave-reflecting, astaxanthin-based, tapetum of Malacosteus may protect the retina from the potential cytotoxicity of such a system
Lack of effect of lowering LDL cholesterol on cancer: meta-analysis of individual data from 175,000 people in 27 randomised trials of statin therapy
<p>Background: Statin therapy reduces the risk of occlusive vascular events, but uncertainty remains about potential effects on cancer. We sought to provide a detailed assessment of any effects on cancer of lowering LDL cholesterol (LDL-C) with a statin using individual patient records from 175,000 patients in 27 large-scale statin trials.</p>
<p>Methods and Findings: Individual records of 134,537 participants in 22 randomised trials of statin versus control (median duration 4.8 years) and 39,612 participants in 5 trials of more intensive versus less intensive statin therapy (median duration 5.1 years) were obtained. Reducing LDL-C with a statin for about 5 years had no effect on newly diagnosed cancer or on death from such cancers in either the trials of statin versus control (cancer incidence: 3755 [1.4% per year [py]] versus 3738 [1.4% py], RR 1.00 [95% CI 0.96-1.05]; cancer mortality: 1365 [0.5% py] versus 1358 [0.5% py], RR 1.00 [95% CI 0.93–1.08]) or in the trials of more versus less statin (cancer incidence: 1466 [1.6% py] vs 1472 [1.6% py], RR 1.00 [95% CI 0.93–1.07]; cancer mortality: 447 [0.5% py] versus 481 [0.5% py], RR 0.93 [95% CI 0.82–1.06]). Moreover, there was no evidence of any effect of reducing LDL-C with statin therapy on cancer incidence or mortality at any of 23 individual categories of sites, with increasing years of treatment, for any individual statin, or in any given subgroup. In particular, among individuals with low baseline LDL-C (<2 mmol/L), there was no evidence that further LDL-C reduction (from about 1.7 to 1.3 mmol/L) increased cancer risk (381 [1.6% py] versus 408 [1.7% py]; RR 0.92 [99% CI 0.76–1.10]).</p>
<p>Conclusions: In 27 randomised trials, a median of five years of statin therapy had no effect on the incidence of, or mortality from, any type of cancer (or the aggregate of all cancer).</p>
Magnetotransport in an aluminum thin film on a GaAs substrate grown by molecular beam epitaxy
Magnetotransport measurements are performed on an aluminum thin film grown on a GaAs substrate. A crossover from electron- to hole-dominant transport can be inferred from both longitudinal resistivity and Hall resistivity with increasing the perpendicular magnetic field B. Also, phenomena of localization effects can be seen at low B. By analyzing the zero-field resistivity as a function of temperature T, we show the importance of surface scattering in such a nanoscale film
A Relationship between Carotenoid Accumulation and the Distribution of Species of the Fungus Neurospora in Spain
The ascomycete fungus Neurospora is present in many parts of the world, in particular in tropical and subtropical areas, where it is found growing on recently burned vegetation. We have sampled the Neurospora population across Spain. The sampling sites were located in the region of Galicia (northwestern corner of the Iberian peninsula), the province of Cáceres, the city of Seville, and the two major islands of the Canary Islands archipelago (Tenerife and Gran Canaria, west coast of Africa). The sites covered a latitude interval between 27.88° and 42.74°. We have identified wild-type strains of N. discreta, N. tetrasperma, N. crassa, and N. sitophila and the frequency of each species varied from site to site. It has been shown that after exposure to light Neurospora accumulates the orange carotenoid neurosporaxanthin, presumably for protection from UV radiation. We have found that each Neurospora species accumulates a different amount of carotenoids after exposure to light, but these differences did not correlate with the expression of the carotenogenic genes al-1 or al-2. The accumulation of carotenoids in Neurospora shows a correlation with latitude, as Neurospora strains isolated from lower latitudes accumulate more carotenoids than strains isolated from higher latitudes. Since regions of low latitude receive high UV irradiation we propose that the increased carotenoid accumulation may protect Neurospora from high UV exposure. In support of this hypothesis, we have found that N. crassa, the species that accumulates more carotenoids, is more resistant to UV radiation than N. discreta or N. tetrasperma. The photoprotection provided by carotenoids and the capability to accumulate different amounts of carotenoids may be responsible, at least in part, for the distribution of Neurospora species that we have observed across a range of latitudes
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