57 research outputs found
Potential Diurnal Variation in Dual X-ray Absorptiometry Collected Skeletal Muscle Mass Measures: A Pilot Study
No full textSkeletal muscle mass (SKMM) is ~30 to ~40 % of total body weight. Measuring SKMM is an important assessment for both exercise and nutritional research. There is biological variation in dual X-ray absorptiometry (DXA) estimates related to subject presentation, changes in tissue hydration, as well as GI tract contents. The consumption of water alone may increase lean mass estimates. PURPOSE: The purpose of this study is to examine how normal daily activities (e.g. eating, sleeping, exercise) may influence SKMM measures using DXA. METHODS: (Mean ± SEM; n = 8; ht: 170.2 ± 8.1 cm; wt: 70.6 ± 5.1 kg; body fat 22.7 ± 3.0 %; appendicular lean soft tissue (ALST): 24.94 ± 2.9 kg). Each participant underwent an AM (0600-0800 h) and PM (1800-2000 h) DXA (Lunar Prodigy; GE Healthcare, Madison, WI) and BIA (720; InBody, Cerriritos, CA) scan, and completed a 3-day dietary recall using Myfitnesspal. RESULTS: No differences were found between AM and PM on lean body mass (LBM; kg), ASLT (kg), SKMM (kg), body fat (kg), total body water (kg), extracellular body water (kg), and intracellular body water (kg). However, carbohydrate (CHO) and Kcal intake were different (p = .04, respectively). CONCLUSION: Currently, it appears that in college aged participants, there is minimal change in SKMM from normal daily activities between the morning and evening DXA body composition measures, which may be due to an inconsistency in daily dietary CHO intake
Salivary Cortisol and Testosterone Responses to a Farmer’s Walk
No full textIt is quite common that numerous populations must often carry large amounts of weight while moving (military, law enforcement, firefighters, farmers, and laborers) and/or benefit from the physiological stresses imposed on the body during competition. An exercise, such as the Farmer’s Walk (FW), may provide beneficial results for these individuals by supplementing the demands encountered during the completion of these tasks within a training environment. Limited information is available concerning the hormonal responses associated with performing the FW and the amount of physiological stress that may occur as a result of repeated efforts has not been investigated. PURPOSE: The purpose of the study is to investigate the impact of the FW on cortisol and testosterone measures when compared to an individual’s unloaded walking pattern. METHODS: Fourteen subjects (mean age ± SE = 21.6 yrs. ± 0.45; height = 172.53 cm ± 2.34; weight = 81.80 kg ± 4.01; body fat percentage = 28.80% ± 2.10; 1RM deadlift = 121.24 kg ± 9.42) participated in two exercise sessions consisting of a 20-meter FW carrying 70% of their 1-RM deadlift (Farmer’s walk condition; FWC) or a normal (unweighted) walk condition (NWC) for 5-sets of 2-repetitions. Saliva samples were collected before the exercise protocol, immediately and one-hour after exercise, and at 24-hour intervals for three days post-exercise. RESULTS: Significant differences between conditions for cortisol (F = 25.1, p = .001) and testosterone to cortisol (T/C) ratio (F = 11.16, p = .04) were shown, but no significant differences for testosterone were observed. CONCLUSION: Cortisol and the T/C ratios were significantly different between the FWC and NWC, however this appears to be a result of increased psychological stress due to midterm and final exams rather than from physiological perturbations
Lateral line sensitivity in free-swimming toadfish Opsanus tau
No full textAuthor Posting. © The Company of Biologists, 2019. This article is posted here by permission of Company of Biologists for personal use, not for redistribution. The definitive version was published in Journal of Experimental Biology 222(2) (2019): jeb190587, doi:10.1242/jeb.190587.A longstanding question in aquatic animal sensory physiology is the impact of self-generated movement on lateral line sensitivity. One hypothesis is that efferent modulation of the sensory hair cells cancels self-generated noise and allows fish to sample their surroundings while swimming. In this study, microwire electrodes were chronically implanted into the anterior lateral line nerve of oyster toadfish and neural activity was monitored during forward movement. Fish were allowed to freely swim or were moved by a tethered sled. In all cases, neural activity increased during movement with no evidence of efferent modulation. The anterior lateral line of moving fish responded to a vibrating sphere or the tail oscillations of a robotic fish, indicating that the lateral line also remains sensitive to outside stimulus during self-generated movement. The results suggest that during normal swim speeds, lateral line neuromasts are not saturated and retain the ability to detect external stimuli without efferent modulation.Funding was provided by National Science Foundation grants IOS 1354745 and DBI 1359230 and 1659604.2020-01-2
Mitochondrial genotype influences the response to cold stress in the European green crab Carcinus maenas
No full textAuthor Posting. © Company of Biologists, 2019. This article is posted here by permission of Company of Biologists for personal use, not for redistribution. The definitive version was published in Journal of Experimental Biology 222(17), (2019):jeb.20352, doi: 10.1242/jeb.203521.Hybrid zones provide natural experiments in recombination within and between genomes that may have strong effects on organismal fitness. On the East Coast of North America, two distinct lineages of the European green crab (Carcinus maenas) have been introduced in the last two centuries. These two lineages with putatively different adaptive properties have hybridized along the coast of the eastern Gulf of Maine, producing new nuclear and mitochondrial combinations that show clinal variation correlated with water temperature. To test the hypothesis that mitochondrial or nuclear genes have effects on thermal tolerance, we first measured the response to cold stress in crabs collected throughout the hybrid zone, then sequenced the mitochondrial CO1 gene and two nuclear single nucleotide polymorphisms (SNPs) representative of nuclear genetic lineage. Mitochondrial haplotype had a strong association with the ability of crabs to right themselves at 4.5°C that was sex specific: haplotypes originally from northern Europe gave male crabs an advantage while there was no haplotype effect on righting in female crabs. By contrast, the two nuclear SNPs that were significant outliers in a comparison between northern and southern C. maenas populations had no effect on righting response at low temperature. These results add C. maenas to the shortlist of ectotherms in which mitochondrial variation has been shown to affect thermal tolerance, and suggest that natural selection is shaping the structure of the hybrid zone across the Gulf of Maine. Our limited genomic sampling does not eliminate the strong possibility that mito-nuclear co-adaptation may play a role in the differences in thermal phenotypes documented here. Linkage between mitochondrial genotype and thermal tolerance suggests a role for local adaptation in promoting the spread of invasive populations of C. maenas around the world.We would like to thank T. Suskiewicz and L. Johnson for help collecting crabs from Halifax, NS, and Robin Seeley for collections from the Isle of Shoals. We thank Timothy Fuller for designing and testing the SMC primers. We thank Mark Murray for facilitating a productive stay on Kent Island, and Nick Keeney for assistance with animal care at the Schiller Coastal Studies Center. This is publication no. 5 from the Bowdoin Marine Laboratory.2020-07-0
Intra-Day Variation in Lean Body Mass and Skeletal Muscle Mass Measures: A Pilot Study
No full textLean body mass (LBM) and its estimated measure of skeletal muscle mass (SKMM) is ~30 to ~40 % of total body weight. Measuring SKMM is an important assessment for both exercise and nutritional research. There is biological variation in dual X-ray absorptiometry (DXA) estimates related to subject presentation, changes in tissue hydration, as well as GI tract contents. PURPOSE: The purpose of this study is to examine how normal activities (e.g. eating, sleeping, exercise) influence LBM and SKMM measures using DXA in college students. METHODS: (Mean ± SEM; n = 42; Age: 26.9 ± 0.4 y; ht: 169.2 ± 1.3 cm; wt: 73.0 ± 2.5 kg; body fat 27.0 ± 1.5 %; LBM: 51.3 ± 1.7 kg; appendicular lean soft tissue (ALST): 23.9 ± 0.9 kg). Each participant underwent an AM (0600-0800 h) and PM (1800-2000 h) DXA (Lunar Prodigy; GE Healthcare, Madison, WI), BIA (720; InBody, Cerriritos, CA) scan, Ultrasonography (LOGIQ e, GE Healthcare, Wauwtosa, WI) of the right vastus lateralis (VL), and completed a 3-day dietary recall using Myfitnesspal. RESULTS: Differences were found between AM and PM in LBM (+275.2 ± 89.6 g; p = .003), ASLT (+226.1 ± 65.7 g; p = .001), SKMM (+274.8 ± 78.9 g). No difference was found in muscle thickness measures (MT). There was an increase found in extracellular body water (+176 ± 86.2 g; p = .04) Daily carbohydrate (CHO) intake (-47.5 ± 13.5 g; p = .001), fat (FAT) intake (-15.23 ± 3.8 g; p = .0004), protein (PRO) intake (-22.2 ± 5.3 g; p = .0002), and Kcal intake (-413.3 ± 85.5 g; p = \u3c.00001) were found less on assessment day. CONCLUSION: Currently, our results suggest that there may be minimal increases in SKMM and LBM indices during intra-day composition assessments, which can not be explained by Kcalorie intake
Psychological Impact of Strongman Training
No full textHigh intensity exercise has been shown to decrease stress and tension, increase energy and generally show greater improvements in mood when compared to lower intensity exercise. However, these findings have primarily been shown to occur as a result of longer duration aerobic exercise, while the impact of resistance training has had more mixed results. Purpose: The purpose of this study is to investigate the after the effect of a Strongman-type exercise (Farmers walk) on measures of anxiety, perceived exertion, and affect. Methods: Fourteen subjects (mean age ± SE = 21.6 yrs. ± 0.45; height = 172.53 cm ± 2.34; weight = 81.80 kg ± 4.01; body fat percentage = 28.80% ± 2.10; 1RM deadlift = 121.24 kg ± 9.42) participated in two counter-balanced exercise sessions consisting of a 20-meter Farmer’s walk carrying 70% of their 1-RM deadlift (Farmer’s walk condition; FWC) or a normal (unweighted) walk condition (NWC) for 5-sets of 2-repetitions. Participants responded to the Activation-Deactivation Adjective Check List (AD-ACL), State Anxiety Inventory (SAI), prior to and immediately after completing the exercise protocol and also reported their Rating of Perceived Exertion (RPE) after each exercise repetition. Results:RPE scores demonstrated a significant time by condition interaction (F9, 108= 28.42, p \u3c .001), with participants reporting greater exertion in the FWC. While there were no differences between conditions for anxiety scores, AD-ACL scores revealed significant interaction effects for tiredness (F1, 14= 5.71, p = 0.03) and tension (F1, 14= 14.28, p = 0.02). Additionally, a main effect for condition was seen for the AD-ACL energy subscale (F1, 14= 5.13, p = 0.04), with the FWC eliciting greater affective measures of energy. Conclusion:The FWC resulted in increased RPE values, along with energy and tension compared with the NWC. Measures of tiredness decreased in both conditions, but the amount of decrease was larger in the FWC condition. Further, measures of tension increased in the FWC, but decreased in the NWC. This suggests that a Strongman type exercise, such as the Farmer’s walk, can have beneficial psychological effects for an exerciser
Potential role of the anterior lateral line in sound localization in toadfish (Opsanus tau)
No full textAuthor Posting. © The Company of Biologists, 2018. This article is posted here by permission of The Company of Biologists for personal use, not for redistribution. The definitive version was published in Journal of Experimental Biology 221 (2018): jeb180679, doi:10.1242/jeb.180679.Male oyster toadfish (Opsanus tau) acoustically attract females to
nesting sites using a boatwhistle call. The rapid speed of sound
underwater combined with the close proximity of the otolithic organs
makes inner ear interaural time differences an unlikely mechanism to
localize sound. To determine the role that the mechanosensory lateral
line may play in sound localization, microwire electrodes were
bilaterally implanted into the anterior lateral line nerve to record
neural responses to vibrational stimuli. Highest spike rates and
strongest phase-locking occurred at distances close to the fish and
decreased as the stimulus was moved further from the fish. Bilateral
anterior lateral line neuromasts displayed differential directional
sensitivity to incoming vibrational stimuli, which suggests the
potential for the lateral line to be used for sound localization in the
near field. The present study also demonstrates that the spatially
separated neuromasts of the toadfish may provide sufficient time
delays between sensory organs for determining sound localization
cues. Multimodal sensory input processing through both the inner ear
(far field) and lateral line (near field) may allow for effective sound
localization in fish.This study was funded by the National Science Foundation (IOS 1354745 to A.F.M.).
C.A.R. was funded through a Rutherford Discovery Fellowship from the Royal
Society of New Zealand and a Marine Biological Laboratory fellowship.2019-05-2
Inge Revsbech wins The Journal of Experimental Biology’s Outstanding Paper Prize 2013
No full textThe Editors of The Journal of Experimental Biology are pleased to announce that Inge Revsbech from Aarhus University, Denmark, is the winner of this year’s JEB Outstanding paper prize. The prize is awarded in memory of Bob Boutillier (JEB Editor-in-Chief 1994–2003) to a junior author who has made the most significant contribution to an outstanding paper. ‘The prize aims to promote and reward the hard work that individual young scientists have put into solving different riddles of any particular species using ingenuity, perseverance and sound technology and methodology’, explains Hans Hoppeler, Editor-In-Chief.
Revsbech was the first author on the paper ‘Hemoglobin function and allosteric regulation in semi-fossorial rodents (family Sciuridae) with different altitudinal ranges’ (Revsbech et al., 2013). Reflecting on the paper, Hoppeler says, ‘This year’s winner stands out because it integrates mechanistic molecular understanding of a physiological process, in this case the conditions for oxygen transfer in hemoglobin, and relates this understanding to an ecological context. Because of the novel insight provided, this manuscript received top ratings and was therefore shortlisted for the prize, and in the final selection the majority of the editors felt that this particular manuscript represented the kind of research that JEB would like to promote.’
Prize is for: Revsbech, I. G., Tufts, D. M., Projecto-Garcia, J., Moriyama, H., Weber, R. E., Storz, J. F. and Fago, A. (2013). Hemoglobin function and allosteric regulation in semifossorial rodents (family Sciuridae) with different altitudinal ranges. J. Exp. Biol. 216, 4264-4271.
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Once in Nebraska, Revsbech found herself hitting the ground running: ‘The day I arrived in Lincoln, we went out to a cemetery where the largest nearby population [of thirteen-lined ground squirrels] was. It had been drizzling all day and these ground squirrels didn’t want to come out. So we hid, and as soon as we saw one come out we’d put out traps with peanut butter, so everything smelt of peanut butter – it was a great start.
The Gini Index in Algebraic Combinatorics and Representation Theory
No full textThe Gini index is a number that attempts to measure how equitably a resource is distributed throughout a population, and is commonly used in economics as a measurement of inequality of wealth or income. The Gini index is often defined as the area between the "Lorenz curve" of a distribution and the line of equality, normalized to be between zero and one. In this fashion, we will define a Gini index on the set of integer partitions and prove some combinatorial results related to it; culminating in the proof of an identity for the expected value of the Gini index. These results comprise the principle contributions of the author. We will then discuss symmetric polynomials, and show that the Gini index can be understood as the degrees of certain Kostka-foulkes polynomials. This identification yields a generalization whereby we may define a Gini index on the irreducible representations of a finite group generated by reflections, or a connected reductive linear algebraic group
Dynamic biosonar adjustment strategies in deep-diving Risso's dolphins driven partly by prey evasion
No full textAuthor Posting. © Company of Biologists, 2019. This article is posted here by permission of Company of Biologists for personal use, not for redistribution. The definitive version was published in Journal of Experimental Biology 223 (2019): jeb.216283, doi: 10.1242/jeb.216283.Toothed whales have evolved flexible biosonar systems to find, track and capture prey in diverse habitats. Delphinids, phocoenids and iniids adjust inter-click intervals and source levels gradually while approaching prey. In contrast, deep-diving beaked and sperm whales maintain relatively constant inter-click intervals and apparent output levels during the approach followed by a rapid transition into the foraging buzz, presumably to maintain a long-range acoustic scene in a multi-target environment. However, it remains unknown whether this rapid biosonar adjustment strategy is shared by delphinids foraging in deep waters. To test this, we investigated biosonar adjustments of a deep-diving delphinid, the Risso's dolphin (Grampus griseus). We analyzed inter-click interval and apparent output level adjustments recorded from sound recording tags to quantify in situ sensory adjustment during prey capture attempts. Risso's dolphins did not follow typical (20logR) biosonar adjustment patterns seen in shallow-water species, but instead maintained stable repetition rates and output levels up to the foraging buzz. Our results suggest that maintaining a long-range acoustic scene to exploit complex, multi-target prey layers is a common strategy amongst deep-diving toothed whales. Risso's dolphins transitioned rapidly into the foraging buzz just like beaked whales during most foraging attempts, but employed a more gradual biosonar adjustment in a subset (19%) of prey approaches. These were characterized by higher speeds and minimum specific acceleration, indicating higher prey capture efforts associated with evasive prey. Thus, tracking and capturing evasive prey using biosonar may require a more gradual switch between multi-target echolocation and single-target tracking.F.H.J. was supported by an AIAS-COFUND fellowship from Aarhus Institute of Advanced Studies under the FP7 program of the EU Seventh Framework Programme (agreement no. 609033). F.V. was supported by the Office of Naval Research (ONR) (grants N00014-15-1-2341 and N00014-17-1-2715) and the Dutch Research Council (award number 016.Veni.181.086). P.L.T. was supported by ONR (grants N00014-15-1-2553 and N00014-18-1-2062) and acknowledges the support of the MASTS pooling initiative (The Marine Alliance for Science and Technology for Scotland) in the completion of this study. MASTS is funded by the Scottish Funding Council (grant reference HR09011) and contributing institutions.2020-12-1
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