310 research outputs found
A Neural Circuit of Appetite Control in C. elegans
Feeding behavior and its associated neural circuitry is complex and intricate in mammalian systems, however, a simple model organism, such as C. elegans provides a more basic approach to understand factors and molecules involved. The fruit-dwelling nematode provides a unique set of resources; it only consists of 959 cells, 302 of which are neurons. In addition, each neuronâs connectivity and position within the worm is known and consistent between animals. Conservation of neurotransmitters and biochemical processes add to this impressive list. These resources provide an excellent background to address feeding behavior and the neural structures governing it.
Feeding behavior in worms mimics feeding behavior in more complex organisms. They decide when to eat based on recent feeding behavior, current nutritional status, availability of food, and familiarity with the food available. Following starvation and refeeding worms enter a behavioral state similar to post-prandial sleep. The worms will stop eating and stop moving, in a state referred to as satiety quiescence. The ability to enter this state and maintain it is dependent on a pair of neurons in the head of C. elegans called ASI. Using calcium imaging and an automated satiety quiescence assay, our lab has found that this neuron pair is important for entering satiety quiescence and senses food. Feeding behavior, such as satiety quiescence, is regulated by numerous factors internal and external to the worm. Another pair of head neurons, ASH are capable of suppressing ASIâs activity in the presence of noxious stimuli and the presence of nutrients (potentially acting via ASI) can suppress ASHâs activation to noxious stimuli under starvation conditions.
The interaction between these two neuron pairs can be regulated by other signals from the rest of the worm. We identified an opioid signal that can modulate the response of ASI to noxious stimulus signaling from ASH under starvation conditions. Other signals were identified to influence satiety behavior and this circuit including serotonin, octopamine, glutamate, and adenosine. In addition to these signals, a group of transcription factors were identified that may play a role in conveying the status of fat storage within the worm to its nervous system. Nuclear hormone receptors were found to increase their expression during starvation then decrease their expression upon refeeding. Upon completion of this work, we have a reached a greater understanding of the internal and external conditions governing feeding and avoidance behaviors
Physical processes determine spatial structure in water temperature and residence time on a wide reef flat
Author Posting. © American Geophysical Union, 2020. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 125(12), (2020): e2020JC016543, https://doi.org/10.1029/2020JC016543.On coral reefs, flow determines residence time of water influencing physical and chemical environments and creating observable microclimates within the reef structure. Understanding the physical mechanisms driving environmental variability on shallow reefs, which distinguishes them from the open ocean, is important for understanding what contributes to thermal resilience of coral communities and predicting their response to future anomalies. In June 2014, a field experiment conducted at Dongsha Atoll in the northern South China Sea investigated the physical forces that drive flow over a broad shallow reef flat. Instrumentation included current and pressure sensors and a distributed temperature sensing system, which resolved spatially and temporally continuous temperature measurements over a 3âkm crossâreef section from the lagoon to reef crest. Spectral analysis shows that while diurnal variability was significant across the reef flatâa result expected from daily solar heatingâtemperature also varied at higher frequencies near the reef crest. These spatially variable temperature regimes, or thermal microclimates, are influenced by circulation on the wide reef flat, with spatially and temporally variable contributions from tides, wind, and waves. Through particle tracking simulations, we find the residence time of water is shorter near the reef crest (3.6 h) than near the lagoon (8.6 h). Tidal variability in flow direction on the reef flat leads to patterns in residence time that are different than what would be predicted from unidirectional flow. Circulation on the reef also determines the source (originating from offshore vs. the lagoon) of the water present on the reef flat.We thank S. Tyler, and J. Selker from the Center for Transformative Environmental Monitoring Programs (CTEMPs), funded by the National Science Foundation (EAR awards 1440596 and 1440506), for timely and effective provision of experimental design support, logistical support and equipment for the project. Support for S. Lentz is from NSF Grant No. OCEâ1558343. Support for A. Cohen from NSF Grant No. 1220529, by the Academia Sinica (Taiwan) through a thematic project grant to G. Wong and A. Cohen. Support for E. Reid and K. Davis is from National Science Foundation (NSF) Grant No. OCEâ1753317, and support to E. Reid from the Environmental Engineering Henry Samueli Endowed Fellowship and the UCI Oceans Graduate Fellowship.2021-05-2
Local diurnal windâdriven variability and upwelling in a small coastal embayment
The oceanic response to highâfrequency local diurnal wind forcing is examined in a small coastal embayment located along an understudied stretch of the central California coast. We show that local diurnal wind forcing is the dominant control on nearshore temperature variability and circulation patterns. A complex empirical orthogonal function (CEOF) analysis of velocities in San Luis Obispo Bay reveals that the firstâmode CEOF amplitude time series, which accounts for 47.9% of the variance, is significantly coherent with the local wind signal at the diurnal frequency and aligns with periods of weak and strong wind forcing. The diurnal evolution of the hydrographic structure and circulation in the bay is examined using both individual events and compositeâday averages. During the late afternoon, the local wind strengthens and results in a sheared flow with nearâsurface warm waters directed out of the bay and a compensating flow of colder waters into the bay over the bottom portion of the water column. This cold water intrusion into the bay causes isotherms to shoal toward the surface and delivers subthermocline waters to shallow reaches of the bay, representing a mechanism for smallâscale upwelling. When the local winds relax, the warm water mass advects back into the bay in the form of a buoyant plume front. Local diurnal winds are expected to play an important role in nearshore dynamics and local upwelling in other small coastal embayments with important implications for various biological and ecological processes
Psychometric Properties of the Hoarding Rating Scale-Interview
The present study tested the psychometric properties of an expanded version of the Hoarding Rating Scale (HRS-I), a semistructured interview for hoarding disorder (HD). Eighty-seven adults with HD and 44 healthy control (HC) participants were assessed using the HRS-I and completed a battery of self-report measures of HD severity, negative affect, and functional impairment. All interviews were audio recorded. From the HD participants, 21 were randomly selected for inter-rater reliability (IRR) analysis and 11 for test-retest reliability (TRR) analysis. The HRS-I showed excellent internal consistency (α = 0.87). IRR and TRR in the HD sample were good (intra-class coefficients = 0.81 and 0.85, respectively). HRS-I scores correlated strongly with scores on the self-report Saving Inventory-Revised (SI-R); partial correlations indicated that the HRS-I clutter, difficulty discarding, and acquiring items correlated significantly and at least moderately with corresponding SI-R subscales, when controlling for the other SI-R subscales. The HD group scored significantly higher on all items than did the HC group, with large effect sizes (d = 1.28â6.58). ROC analysis showed excellent sensitivity (1.00) and specificity (1.00) for distinguishing the HD and HC groups with a cutoff score of 11. Results and limitations are discussed in light of prior research
Fate of internal waves on a shallow shelf
Author Posting. © American Geophysical Union, 2020. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 125(5), (2020): e2019JC015377, doi:10.1029/2019JC015377.Internal waves strongly influence the physical and chemical environment of coastal ecosystems worldwide. We report novel observations from a distributed temperature sensing (DTS) system that tracked the transformation of internal waves from the shelf break to the surf zone over a narrow shelf slope region in the South China Sea. The spatially continuous view of temperature fields provides a perspective of physical processes commonly available only in laboratory settings or numerical models, including internal wave reflection off a natural slope, shoreward transport of dense fluid within trapped cores, and observations of internal rundown (nearâbed, offshoreâdirected jets of water preceding a breaking internal wave). Analysis shows that the fate of internal waves on this shelfâwhether transmitted into shallow waters or reflected back offshoreâis mediated by local water column density structure and background currents set by the previous shoaling internal waves, highlighting the importance of waveâwave interactions in nearshore internal wave dynamics.We are grateful for the support of the Dongsha Atoll Research Station (DARS) and the Dongsha Atoll Marine National Park, whose efforts made this research possible. The authors would also like to thank A. Hall, S. Tyler, and J. Selker from the Center for Transformative Environmental Monitoring Programs (CTEMPs) funded by the National Science Foundation (EAR awards 1440596 and 1440506), G. Lohmann from WHOI, A. Safaie from UC Irvine, G. Wong, L. Hou, F. Shiah, and K. Lee from Academia Sinica for providing logistical and field support, as well as E. Pawlak, S. Lentz, B. Sanders, and S. Grant for equipment, and B. Raubenheimer, S. Elgar, R. Walter and D. Lucas for informative discussions that improved this work. We acknowledge the US Army Research Laboratory DoD Supercomputing Resource Center for computer time on Excalibur, which was used for the numerical simulations in this work. Funding for this work supported by Academia Sinica and for K.D. and E.R. from NSFâOCE 1753317 and for O.F., J.R., and R.A. from ONR Grant 1182789â1âTDZZM. A portion of this work (R.A.) was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DEâAC52â07NA27344.2020-10-2
Cytonuclear discordance in the Florida Everglades invasive Burmese python (Python bivittatus) population reveals possible hybridization with the Indian python (P. molurus)
The invasive Burmese python (Python bivittatus) has been reproducing in the Florida Everglades since the 1980s. These giant constrictor snakes have caused a precipitous decline in small mammal populations in southern Florida following escapes or releases from the commercial pet trade. To better understand the invasion pathway and genetic composition of the population, two mitochondrial (mtDNA) loci across 1,398 base pairs were sequenced on 426 snakes and 22 microsatellites were assessed on 389 snakes. Concatenated mtDNA sequences produced six haplotypes with an average nucleotide and haplotype diversity of Ï = 0.002 and h = 0.097, respectively. Samples collected in Florida from morphologically identified P. bivittatus snakes were similar to published cytochrome oxidase 1 and cytochrome b sequences from both P. bivittatus and Python molurus and were highly divergent (genetic distances of 5.4% and 4.3%, respectively). The average number of microsatellite alleles and expected heterozygosity were NA = 5.50 and HE = 0.60, respectively. Nuclear Bayesian assignment tests supported two genetically distinct groups and an admixed group, not geographically differentiated. The effective population size (NE = 315.1) was lower than expected for a population this large, but reflected the low genetic diversity overall. The patterns of genetic diversity between mtDNA and microsatellites were disparate, indicating nuclear introgression of separate mtDNA lineages corresponding to cytonuclear discordance. The introgression likely occurred prior to the invasion, but genetic information on the native range and commercial trade is needed for verification. Our finding that the Florida python population is comprised of distinct lineages suggests greater standing variation for adaptation and the potential for broader areas of suitable habitat in the invaded range
Two spatial scales in a bleaching event : corals from the mildest and the most extreme thermal environments escape mortality
Author Posting. © Association for the Sciences of Limnology and Oceanography, 2013. This article is posted here by permission of Association for the Sciences of Limnology and Oceanography for personal use, not for redistribution. The definitive version was published in Limnology and Oceanography 58 (2013): 1531-1545, doi:10.4319/lo.2013.58.5.1531.In summer 2010, a bleaching event decimated the abundant reef flat coral Stylophora pistillata in some areas of the central Red Sea, where a series of coral reefs 100â300 m wide by several kilometers long extends from the coastline to about 20 km offshore. Mortality of corals along the exposed and protected sides of inner (inshore) and mid and outer (offshore) reefs and in situ and satellite sea surface temperatures (SSTs) revealed that the variability in the mortality event corresponded to two spatial scales of temperature variability: 300 m across the reef flat and 20 km across a series of reefs. However, the relationship between coral mortality and habitat thermal severity was opposite at the two scales. SSTs in summer 2010 were similar or increased modestly (0.5°C) in the outer and mid reefs relative to 2009. In the inner reef, 2010 temperatures were 1.4°C above the 2009 seasonal maximum for several weeks. We detected little or no coral mortality in mid and outer reefs. In the inner reef, mortality depended on exposure. Within the inner reef, mortality was modest on the protected (shoreward) side, the most severe thermal environment, with highest overall mean and maximum temperatures. In contrast, acute mortality was observed in the exposed (seaward) side, where temperature fluctuations and upper water temperature values were relatively less extreme. Refuges to thermally induced coral bleaching may include sites where extreme, high-frequency thermal variability may select for coral holobionts preadapted to, and physiologically condition corals to withstand, regional increases in water temperature.J.C.B.S. was partially supported by FundacžaËo para a CieËncia e
a Tecnologia (project PEst-C/MAR/LA0015/2011) and by the
European Regional Development Fund through the Operational
Competitiveness Programme (National Strategic Reference
Framework). Kristen Davis was partially supported by a Woods
Hole Oceanographic Institution postdoctoral scholarship. This research was supported by KAUST with awards USA 00002 and
KSA 00011
Assessing the within-person variability of internal and external sexual consent
Sexual consent is often conceptualized as an internal willingness to engage in sexual activity, which can be communicated externally to a sexual partner. Internal sexual consent comprises feelings of physical response, safety/comfort, arousal, agreement/want, and readiness; external sexual consent includes communication cues that may be explicit or implicit and verbal or nonverbal. Most previous research on sexual consent has focused on between-person differences; little attention has been devoted to examining the within-person variation of sexual consent across time. We conducted a 28-day experience sampling methodology (ESM) study with a sample of adults (N = 113) to assess fluctuations in internal and external sexual consent across a given personâs sexual events. We found that more than 50% and up to 80% of the variance in sexual consent scores could be accounted for by within-person variability. The type of sexual behavior participants engaged in during a sexual event predicted their internal and external consent. Further, internal consent feelings predicted external consent communication. Overall, our findings provided initial evidence regarding the extent that situational contexts are relevant for sexual consent. ESM study designs may be used to further investigate the potential contextual, intrapersonal, and interpersonal factors associated with internal and external sexual consent
Developing valid and feasible measures of sexual consent for experience sampling methodology
Preliminary evidence indicates that peopleâs sexual consent (i.e., their willingness to engage in sexual activity and communication of that willingness) varies across time and context. Study designs that assess sexual consent at multiple time points (e.g., experience sampling methodology [ESM]) are needed to better understand the within-person variability of sexual consent. However, extant validated measures of sexual consent are not appropriate for ESM studies, which require shorter assessments due to the increased burden this methodology has on participants. As such, the goal of the present study was to develop ESM measures of sexual consent based on items that have previously been validated for use in cross-sectional surveys. We selected items that balanced face validity as evidenced by cognitive interviews (n = 10) and content validity as evidenced by expertsâ ratings (n = 6). To assess the construct validity and feasibility of these items, we administered the selected ESM measures of sexual consent in a seven-day pilot study (n = 12). The results suggested that the ESM measures developed in the present study were a valid and feasible assessment of peopleâs experience-specific internal consent feelings and external consent communication. We conclude with recommendations for sex researchers interested in ESM
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