SciCombinator

Discover the most talked about and latest scientific content & concepts.

78

The variation of microbial communities associated with the human body can be the cause of many factors, including the human genetic makeup, diet, age, surroundings, and sexual behavior. In this study, we investigated the effects of intimate kissing on the oral microbiota of 21 couples by self-administered questionnaires about their past kissing behavior and by the evaluation of tongue and salivary microbiota samples in a controlled kissing experiment. In addition, we quantified the number of bacteria exchanged during intimate kissing by the use of marker bacteria introduced through the intake of a probiotic yoghurt drink by one of the partners prior to a second intimate kiss.

Concepts: Genetics, Archaea, Bacteria, Microbiology, Escherichia coli, Human body, Human sexual behavior, Personal life

41

Questions surrounding the effects of chronic marijuana use on brain structure continue to increase. To date, however, findings remain inconclusive. In this comprehensive study that aimed to characterize brain alterations associated with chronic marijuana use, we measured gray matter (GM) volume via structural MRI across the whole brain by using voxel-based morphology, synchrony among abnormal GM regions during resting state via functional connectivity MRI, and white matter integrity (i.e., structural connectivity) between the abnormal GM regions via diffusion tensor imaging in 48 marijuana users and 62 age- and sex-matched nonusing controls. The results showed that compared with controls, marijuana users had significantly less bilateral orbitofrontal gyri volume, higher functional connectivity in the orbitofrontal cortex (OFC) network, and higher structural connectivity in tracts that innervate the OFC (forceps minor) as measured by fractional anisotropy (FA). Increased OFC functional connectivity in marijuana users was associated with earlier age of onset. Lastly, a quadratic trend was observed suggesting that the FA of the forceps minor tract initially increased following regular marijuana use but decreased with protracted regular use. This pattern may indicate differential effects of initial and chronic marijuana use that may reflect complex neuroadaptive processes in response to marijuana use. Despite the observed age of onset effects, longitudinal studies are needed to determine causality of these effects.

Concepts: Central nervous system, Neuroanatomy, Brain, Neuroimaging, Magnetic resonance imaging, Cerebrum, Cerebellum, Psychoactive drug

25

Context Spinal cord injury (SCI) causes disruption of the efferent input to and afferent input from respiratory muscles, which impairs respiratory motor and sensory functions, respectively. This disturbs the injured individual’s ability to respond to ventilatory loads and may alter the respiratory perceptual sensitivity of applied loads. Acute intermittent hypoxia with elevated CO2 (AIH treatment) has been shown to induce ventilatory long-term facilitation in individuals with chronic SCI. This study evaluated the effect of ten days of AIH treatment on ventilatory load compensation and respiratory perceptual sensitivity to inspiratory resistive loads (IRL), in an individual with chronic, incomplete cervical SCI. Methods Case report and literature review. Findings We report a case of a 55-year-old female with a C4 chronic, incomplete SCI (American Spinal Injury Association Impairment Scale D). The subject underwent evaluation at four time-points: Baseline, Post Sham, AIH Day 1 and AIH Day 10. Significant improvements in airflow generated in response to applied IRL were found after AIH treatment compared to Baseline. There were no significant changes in the respiratory perceptual sensitivity to applied IRL after AIH treatment. Clinical relevance Rehabilitative interventions after SCI demand restoration of the respiratory motor function. However, they must also ensure that the respiratory perceptual sensitivity of the injured individual does not hinder their capability to compensate to ventilatory challenges.

Concepts: Spinal cord, Carbon dioxide, Medical terms, Sense, Spinal cord injury, Motor skill, Physical trauma, Compensation

23

Lightning plays an important role in atmospheric chemistry and in the initiation of wildfires, but the impact of global warming on lightning rates is poorly constrained. Here we propose that the lightning flash rate is proportional to the convective available potential energy (CAPE) times the precipitation rate. Using observations, the product of CAPE and precipitation explains 77% of the variance in the time series of total cloud-to-ground lightning flashes over the contiguous United States (CONUS). Storms convert CAPE times precipitated water mass to discharged lightning energy with an efficiency of 1%. When this proxy is applied to 11 climate models, CONUS lightning strikes are predicted to increase 12 ± 5% per degree Celsius of global warming and about 50% over this century.

Concepts: Energy, Earth, United States, Lightning, Precipitation, Climate, Climate change, Global warming

15

We have purified and reconstituted human transient receptor potential (TRP) subtype A1 (hTRPA1) into lipid bilayers and recorded single-channel currents to understand its inherent thermo- and chemosensory properties as well as the role of the ankyrin repeat domain (ARD) of the N terminus in channel behavior. We report that hTRPA1 with and without its N-terminal ARD (Δ1-688 hTRPA1) is intrinsically cold-sensitive, and thus, cold-sensing properties of hTRPA1 reside outside the N-terminal ARD. We show activation of hTRPA1 by the thiol oxidant 2-((biotinoyl)amino)ethyl methanethiosulfonate (MTSEA-biotin) and that electrophilic compounds activate hTRPA1 in the presence and absence of the N-terminal ARD. The nonelectrophilic compounds menthol and the cannabinoid Δ(9)-tetrahydrocannabiorcol (C16) directly activate hTRPA1 at different sites independent of the N-terminal ARD. The TRPA1 antagonist HC030031 inhibited cold and chemical activation of hTRPA1 and Δ1-688 hTRPA1, supporting a direct interaction with hTRPA1 outside the N-terminal ARD. These findings show that hTRPA1 is an intrinsically cold- and chemosensitive ion channel. Thus, second messengers, including Ca(2+), or accessory proteins are not needed for hTRPA1 responses to cold or chemical activators. We suggest that conformational changes outside the N-terminal ARD by cold, electrophiles, and nonelectrophiles are important in hTRPA1 channel gating and that targeting chemical interaction sites outside the N-terminal ARD provides possibilities to fine tune TRPA1-based drug therapies (e.g., for treatment of pain associated with cold hypersensitivity and cardiovascular disease).

Concepts: Protein, Protein structure, Receptor, Action potential, Ion channel, Lipid, Electrophile, Transient receptor potential channel

14

Populations of at least 20 asteroid species on the Northeast Pacific Coast have recently experienced an extensive outbreak of sea-star (asteroid) wasting disease (SSWD). The disease leads to behavioral changes, lesions, loss of turgor, limb autotomy, and death characterized by rapid degradation (“melting”). Here, we present evidence from experimental challenge studies and field observations that link the mass mortalities to a densovirus (Parvoviridae). Virus-sized material (i.e., <0.2 μm) from symptomatic tissues that was inoculated into asymptomatic asteroids consistently resulted in SSWD signs whereas animals receiving heat-killed (i.e., control) virus-sized inoculum remained asymptomatic. Viral metagenomic investigations revealed the sea star-associated densovirus (SSaDV) as the most likely candidate virus associated with tissues from symptomatic asteroids. Quantification of SSaDV during transmission trials indicated that progression of SSWD paralleled increased SSaDV load. In field surveys, SSaDV loads were more abundant in symptomatic than in asymptomatic asteroids. SSaDV could be detected in plankton, sediments and in nonasteroid echinoderms, providing a possible mechanism for viral spread. SSaDV was detected in museum specimens of asteroids from 1942, suggesting that it has been present on the North American Pacific Coast for at least 72 y. SSaDV is therefore the most promising candidate disease agent responsible for asteroid mass mortality.

Concepts: AIDS, Epidemiology, Diseases and disorders, Death, Vaccination, Solar System, Mars, Jupiter

14

Male mammals often kill conspecific offspring. The benefits of such infanticide to males, and its costs to females, probably vary across mammalian social and mating systems. We used comparative analyses to show that infanticide primarily evolves in social mammals in which reproduction is monopolized by a minority of males. It has not promoted social counterstrategies such as female gregariousness, pair living, or changes in group size and sex ratio, but is successfully prevented by female sexual promiscuity, a paternity dilution strategy. These findings indicate that infanticide is a consequence, rather than a cause, of contrasts in mammalian social systems affecting the intensity of sexual conflict.

Concepts: Human, Male, Reproduction, Female, Gender, Sex, Gamete, Hermaphrodite

14

Little is known about the genetic changes that distinguish domestic cat populations from their wild progenitors. Here we describe a high-quality domestic cat reference genome assembly and comparative inferences made with other cat breeds, wildcats, and other mammals. Based upon these comparisons, we identified positively selected genes enriched for genes involved in lipid metabolism that underpin adaptations to a hypercarnivorous diet. We also found positive selection signals within genes underlying sensory processes, especially those affecting vision and hearing in the carnivore lineage. We observed an evolutionary tradeoff between functional olfactory and vomeronasal receptor gene repertoires in the cat and dog genomes, with an expansion of the feline chemosensory system for detecting pheromones at the expense of odorant detection. Genomic regions harboring signatures of natural selection that distinguish domestic cats from their wild congeners are enriched in neural crest-related genes associated with behavior and reward in mouse models, as predicted by the domestication syndrome hypothesis. Our description of a previously unidentified allele for the gloving pigmentation pattern found in the Birman breed supports the hypothesis that cat breeds experienced strong selection on specific mutations drawn from random bred populations. Collectively, these findings provide insight into how the process of domestication altered the ancestral wildcat genome and build a resource for future disease mapping and phylogenomic studies across all members of the Felidae.

Concepts: DNA, Gene, Genetics, Natural selection, Evolution, Genome, Cat, Felidae

14

Synthetic devices for traceless remote control of gene expression may provide new treatment opportunities in future gene- and cell-based therapies. Here we report the design of a synthetic mind-controlled gene switch that enables human brain activities and mental states to wirelessly programme the transgene expression in human cells. An electroencephalography (EEG)-based brain-computer interface (BCI) processing mental state-specific brain waves programs an inductively linked wireless-powered optogenetic implant containing designer cells engineered for near-infrared (NIR) light-adjustable expression of the human glycoprotein SEAP (secreted alkaline phosphatase). The synthetic optogenetic signalling pathway interfacing the BCI with target gene expression consists of an engineered NIR light-activated bacterial diguanylate cyclase (DGCL) producing the orthogonal second messenger cyclic diguanosine monophosphate (c-di-GMP), which triggers the stimulator of interferon genes (STING)-dependent induction of synthetic interferon-β promoters. Humans generating different mental states (biofeedback control, concentration, meditation) can differentially control SEAP production of the designer cells in culture and of subcutaneous wireless-powered optogenetic implants in mice.

Concepts: DNA, Gene, Genetics, Cell nucleus, Gene expression, Cell, Bacteria, Organism

13

Trust in others' honesty is a key component of the long-term performance of firms, industries, and even whole countries. However, in recent years, numerous scandals involving fraud have undermined confidence in the financial industry. Contemporary commentators have attributed these scandals to the financial sector’s business culture, but no scientific evidence supports this claim. Here we show that employees of a large, international bank behave, on average, honestly in a control condition. However, when their professional identity as bank employees is rendered salient, a significant proportion of them become dishonest. This effect is specific to bank employees because control experiments with employees from other industries and with students show that they do not become more dishonest when their professional identity or bank-related items are rendered salient. Our results thus suggest that the prevailing business culture in the banking industry weakens and undermines the honesty norm, implying that measures to re-establish an honest culture are very important.

Concepts: Bond, Finance, Bank, Interest rate, Cheque, Financial services, Private banking, Overdraft