The clinical meaning and significance of OVEMP morphology.

PURPOSE: While some OVEMP recordings are morphologically straightforward, some are poor in appearance, which can create a challenge, as they often require a "second look" by another experienced assessor. Even OVEMPs in normal subjects are sometimes poorly formed, but we wondered if the morphological assessment of the OVEMP response might provide some additional diagnostic information. METHODS: A single experienced assessor evaluated the OVEMP recordings of 60 patients referred sequentially to a tertiary care centre, and categorized them as "easy to assess" (i.e. obvious to a minimally trained assessor) or "difficult to assess", often requiring a second look by another experienced assessor. RESULTS: In 48 patients, the results were easy to assess (regardless of the actual clinical results) while 12 were classified as "difficult". This figure reflected the rate of morphologically poor responses we found in our population of normative data. CONCLUSION: Our clinical concern is that many centres have given up relying on OVEMP assessment because the morphology of the wave may be challenging to interpret. OVEMP assessment often calls for a "second look", requiring a collaboration between two experienced assessors. It seems that this feature may not be diagnostically useful and poor OVEMP morphology may present a challenge in interpretation, but this should not be used as a reason to defer OVEMP testing.

How well do connectivity tools agree over the full life cycle? A case study of Irish Sea plaice Pleuronectes platessa Linnaeus, 1758.

Adult plaice in the Irish Sea have distinct traits that reflect the spawning locations that could suggest a number of different populations. However, do connectivity pathways support this concept? Different tools are directed at measuring exchange or connectivity between different life-history stages, and the challenge is to integrate the signals to obtain full life-cycle estimates. Collectively, the different methods reveal stable connectivity between known spawning and nursery grounds, with sufficient exchange to maintain a single population with weak genetic structure.

A nitrogen isotopic shift in fish otolith-bound organic matter during the Late Cretaceous.

The nitrogen isotopes of the organic matter preserved in fossil fish otoliths (ear stones) are a promising tool for reconstructing past environmental changes. We analyzed the 15N/14N ratio (δ15N) of fossil otolith-bound organic matter in Late Cretaceous fish otoliths (of Eutawichthys maastrichtiensis, Eutawichthys zideki and Pterothrissus sp.) from three deposits along the US east coast, with two of Campanian (83.6 to 77.9 Ma) and one Maastrichtian (72.1 to 66 Ma) age. δ15N and N content were insensitive to cleaning protocol and the preservation state of otolith morphological features, and N content differences among taxa were consistent across deposits, pointing to a fossil-native origin for the organic matter. All three species showed an increase in otolith-bound organic matter δ15N of ~4‰ from Campanian to Maastrichtian. As to its cause, the similar change in distinct genera argues against changing trophic level, and modern field data argue against the different locations of the sedimentary deposits. Rather, the lower δ15N in the Campanian is best interpreted as an environmental signal at the regional scale or greater, and it may be a consequence of the warmer global climate. A similar decrease has been observed in foraminifera-bound δ15N during warm periods of the Cenozoic, reflecting decreased water column denitrification and thus contraction of the ocean's oxygen deficient zones (ODZs) under warm conditions. The same δ15N-climate correlation in Cretaceous otoliths raises the prospect of an ODZ-to-climate relationship that has been consistent over the last ~80 My, applying before and after the end-Cretaceous mass extinction and spanning changes in continental configuration.

Travelling in Microphis (Teleostei: Syngnathidae) Otoliths with Two-Dimensional X-ray Fluorescence Maps: Twists and Turns on the Road to Strontium Incorporation.

Indo-Pacific tropical island streams are home to freshwater pipefish (Microphis spp., Syngnathidae). Otoliths were used to uncover life history traits in four species, including a New Caledonian endemic. All four species present the same methodological challenge: their otoliths are small, fragile and mute for growth marks using basic observation tools. Strontium (Sr) is calcium substituent in the mineral lattice, driven by salinity conditions, and thus useful to study diadromous migrations. Synchrotron-based scanning X-ray fluorescence 2D high-resolution mapping allowed us to tackle the global and hyperfine strontium (Sr) distribution. We developed analytical imaging processes to retrieve biological information from otoliths from the data generated via synchrotron analysis. We uncovered plasticity in the life cycle: all species were amphidromous, apart from some freshwater residents from New Caledonia. Understanding life cycle modalities is crucial to categorize species distribution limits and to implement adapted conservation measures, especially when endemic species are at stake. 2D fine-scale images outlined the heterogeneity of Sr distribution: in addition to the trivial Sr incorporation driven by environmental ionic conditions, there is an unusual mosaic arrangement of Sr distribution and we hypothesize that biological control, especially growth during the early life stages, may sometimes overrule stoichiometry. This shows that it is worth studying otolith formation and element integration at imbricated scales, and our methods and results provide a strong basis for future works and prospects in otolith science.

A New Perspective to Interpret How the Vestibular Efferent System Correlates the Complexity of Routine Balance Maintenance with Management of Emergency Fall Prevention Strategies.

Bipedalism is unique among mammals. Until modern times, a fall and resulting leg fracture could be fatal. Balance maintenance after a destabilizing event requires instantaneous decision making. The vestibular system plays an essential role in this process, initiating an emergency response. The afferent otolithic neural response is the first directionally oriented information to reach the cortex, and it can then be used to initiate an appropriate protective response. Some vestibular efferent axons feed directly into type I vestibular hair cells. This allows for rapid vestibular feedback via the striated organelle (STO), which has been largely ignored in most texts. We propose that this structure is essential in emergency fall prevention, and also that the system of sensory detection and resultant motor response works by having efferent movement information simultaneously transmitted to the maculae with the movement commands. This results in the otolithic membrane positioning itself precisely for the planned movement, and any error is due to an unexpected external cause. Error is fed back via the vestibular afferent system. The efferent system causes macular otolithic membrane movement through the STO, which occurs simultaneously with the initiating motor command. As a result, no vestibular afferent activity occurs unless an error must be dealt with.

Weighing the impact of microgravity on vestibular and visual functions.

Numerous technological challenges have been overcome to realize human space exploration. As mission durations gradually lengthen, the next obstacle is a set of physical limitations. Extended exposure to microgravity poses multiple threats to various bodily systems. Two of these systems are of particular concern for the success of future space missions. The vestibular system includes the otolith organs, which are stimulated in gravity but unloaded in microgravity. This impairs perception, posture, and coordination, all of which are relevant to mission success. Similarly, vision is impaired in many space travelers due to possible intracranial pressure changes or fluid shifts in the brain. As humankind prepares for extended missions to Mars and beyond, it is imperative to compensate for these perils in prolonged weightlessness. Possible countermeasures are considered such as exercise regimens, improved nutrition, and artificial gravity achieved with a centrifuge or spacecraft rotation.

Age and growth assessment of the near-threatened fish Rita rita (Siluriformes: Bagridae) in the Ganges basin

Introduction: Rita rita is a freshwater catfish under threat of extinction, mainly from loss of breeding and nursing grounds. A reliable method for age and growth estimation is needed by fishery managers. Objective: To identify the best body structure for age and growth estimation. Methods: We assessed estimates precision based on Average Percent Error (APE), Coefficient Variation (CV), and Percent Agreement (PA) between readers separately analyzed each calcified structure. We used 390 fish samples from three rivers, Ganga, Yamuna and Ramganga, from September 2018 to August 2019. Results: The three indicators favored the use of vertebrae for age estimation; the growth band seems to be annual and formed from May to September. The growth equations were Lt = 90.19(1-e-0.145(t+0.51)) for Ganga; Lt = 91.19 (1-e-0.14(t+0.59)) for Yamuna and Lt = 89.63 (1-e-0.15(t+0.68)) for Ramganga. Conclusion: This species reaches moderate growth in these rivers, where vertebrae are the recommended age estimation structure, followed, in case of need, by sectioned otoliths, whole otoliths and opercular bones. Pectoral spines should be avoided, especially in older fish.

Introducción: Rita rita es un pez de agua dulce bajo amenaza de extinción, principalmente por la pérdida de sitios de reproducción y crianza. Un método fiable para las estimaciones de edad y crecimiento es necesario para los administradores de recursos pesqueros. Objetivo: Identificar la mejor estructura corporal para estimaciones de edad y crecimiento. Métodos: Evaluamos la precisión de las estimaciones mediante el Porcentaje de Error Promedio (APE), Coeficiente de Variación (CV), y Porcentaje de Acuerdo (PA) entre lecturas para cada estructura calcificada. Usamos 390 muestras de peces de tres ríos, Ganga, Yamuna y Ramganga, de setiembre 2018 hasta agosto 2019. Resultados: Los tres indicadores favorecieron el uso de vértebras para la estimación de edad; la banda de crecimiento parece ser anual y se forma entre mayo y setiembre. Las ecuaciones de crecimiento fueron Lt = 90.19(1-e-0.145(t+0.51)) para Ganga; Lt = 91.19 (1-e-0.14(t+0.59)) para Yamuna y Lt = 89.63 (1-e-0.15(t+0.68)) para Ramganga. Conclusión: La especie alcanza un crecimiento moderado en estos ríos, dónde las vértebras son la estructura de estimación etaria recomendada, seguido de, en caso de ser necesario, los otolitos segmentados, otolitos enteros y huesos operculares. Debe evitarse el uso de espinas pectorales, especialmente en peces de mayor edad.

Head-centric computing for vestibular stimulation under head-free conditions.

Background: The vestibular end organs (semicircular canals, saccule and utricle) monitor head orientation and motion. Vestibular stimulation by means of controlled translations, rotations or tilts of the head represents a routine manoeuvre to test the vestibular apparatus in a laboratory or clinical setting. In diagnostics, it is used to assess oculomotor postural or perceptual responses, whose abnormalities can reveal subclinical vestibular dysfunctions due to pathology, aging or drugs. Objective: The assessment of the vestibular function requires the alignment of the motion stimuli as close as possible with reference axes of the head, for instance the cardinal axes naso-occipital, interaural, cranio-caudal. This is often achieved by using a head restraint, such as a helmet or strap holding the head tightly in a predefined posture that guarantees the alignment described above. However, such restraints may be quite uncomfortable, especially for elderly or claustrophobic patients. Moreover, it might be desirable to test the vestibular function under the more natural conditions in which the head is free to move, as when subjects are tracking a visual target or they are standing erect on the moving platform. Here, we document algorithms that allow delivering motion stimuli aligned with head-fixed axes under head-free conditions. Methods: We implemented and validated these algorithms using a MOOG-6DOF motion platform in two different conditions. 1) The participant kept the head in a resting, fully unrestrained posture, while inter-aural, naso-occipital or cranio-caudal translations were applied. 2) The participant moved the head continuously while a naso-occipital translation was applied. Head and platform motion were monitored in real-time using Vicon. Results: The results for both conditions showed excellent agreement between the theoretical spatio-temporal profile of the motion stimuli and the corresponding profile of actual motion as measured in real-time. Conclusion: We propose our approach as a safe, non-intrusive method to test the vestibular system under the natural head-free conditions required by the experiential perspective of the patients.

Angular and Linear Accelerations, Ear, and the Skeletal Muscle.

The ear serves two vital functions of hearing and maintaining balance. It achieves these roles within three major compartments: the outer, the middle, and the inner ear. Embryological development of the ear and its associated structures have been studied in some animal models. Yet, the role of skeletal muscle in ear development and its related structures is largely unknown. Research suggests the outer ear and parts of the inner ear may require skeletal muscle for normal embryogenesis. Here, we describe the role of skeletal muscle in the development of the ear and its associated structures. Moreover, we report the possible consequences of defect in the skeletal muscle of the ear and the clinical correlates of such consequences.

Vestibular Testing-New Physiological Results for the Optimization of Clinical VEMP Stimuli.

Both auditory and vestibular primary afferent neurons can be activated by sound and vibration. This review relates the differences between them to the different receptor/synaptic mechanisms of the two systems, as shown by indicators of peripheral function-cochlear and vestibular compound action potentials (cCAPs and vCAPs)-to click stimulation as recorded in animal studies. Sound- and vibration-sensitive type 1 receptors at the striola of the utricular macula are enveloped by the unique calyx afferent ending, which has three modes of synaptic transmission. Glutamate is the transmitter for both cochlear and vestibular primary afferents; however, blocking glutamate transmission has very little effect on vCAPs but greatly reduces cCAPs. We suggest that the ultrafast non-quantal synaptic mechanism called resistive coupling is the cause of the short latency vestibular afferent responses and related results-failure of transmitter blockade, masking, and temporal precision. This "ultrafast" non-quantal transmission is effectively electrical coupling that is dependent on the membrane potentials of the calyx and the type 1 receptor. The major clinical implication is that decreasing stimulus rise time increases vCAP response, corresponding to the increased VEMP response in human subjects. Short rise times are optimal in human clinical VEMP testing, whereas long rise times are mandatory for audiometric threshold testing.

Utility of body and otolith morphometry to discriminate cryptic juveniles of two sympatric red snappers (Perciformes: Lutjanidae).

The sympatric red snappers, Lutjanus erythropterus and Lutjanus malabaricus, are highly valued by commercial and recreational fishers along the tropical northern coasts of Australia and throughout their distribution. Studies on the life history and ecology of these congeners are confounded by difficulties in distinguishing the cryptic juveniles of each species (i.e., < 200 mm total length). This study aimed to validate a robust and cost-effective method to discriminate these juveniles using body and/or otolith morphometric data in a multivariate analysis. Juvenile samples were collected from the northwest (n = 71) and northeast (n = 19) coasts of Australia, and species identification was confirmed using DNA barcoding. The most parsimonious multivariate models achieved accurate species prediction rates of 98.8%, which consisted of just three body variables (dorsal fin length, the distance from the snout to the anterior edge of the eye, and either jaw length or distance from the snout to the preoperculum). The high level of discrimination for these cryptic juveniles highlights the robustness of this morphometric approach. The slightly lower rate of discrimination using otolith morphology (84.9%) was associated with greater regional variation in L. malabaricus between the northwest and northeast coasts. Slight variations in otolith shape are typically used to determine stock structure, which highlights the potential need to collect samples over a broader area of a species geographic range when using an otolith morphometric discrimination model. The method outlined in this study could be applied to distinguish other cryptic congeneric fish species, including from archived otolith collections. Moreover, this method has the potential to be utilized in assessing species compositions using body measurements from in situ stereo-video.

Rearing in strontium-enriched water induces vaterite otoliths in the Japanese rice fish, Oryzias latipes.

Sagittal otoliths, typically composed of aragonite, are frequently laid down rather as vaterite during growth in hatchery-reared fish populations. Sagittal vateritization is believed to impair individual hearing/balancing abilities, but the causal mechanism remains unclear. Here we experimentally demonstrated that rearing in Sr-rich water induces sagittal vateritization in the HdrR-II1 inbred strain of the Japanese rice fish, Oryzias latipes. Both sagittae were partly vateritized in 70% of individuals subjected to the Sr2+ treatment (n = 10), whereas fish reared in normal tap water showed no sagittal vateritization (n = 8). Our result is consistent with the theoretical prediction that vaterite becomes thermodynamically more stable than aragonite as the Sr2+ concentration in solution increases. A vateritic layer develops surrounding the original aragonitic sagitta in vateritized otoliths, some of which take on a comma-like shape. Electron probe microanalysis demonstrates that the vateritized phase is characterized by lower Sr2+ and higher Mg2+ concentrations than the aragonitic phase. It is unlikely that increased environmental Sr2+ is responsible for the sagittal vateritization in farmed fish. However, our findings likely help to establish an in vivo assay using O. latipes to understand the physiological process underlying the sagittal vateritization in farmed fish.

Biological clocks as age estimation markers in animals: a systematic review and meta-analysis.

Various biological attributes associated with individual fitness in animals change predictably over the lifespan of an organism. Therefore, the study of animal ecology and the work of conservationists frequently relies upon the ability to assign animals to functionally relevant age classes to model population fitness. Several approaches have been applied to determining individual age and, while these methods have proved useful, they are not without limitations and often lack standardisation or are only applicable to specific species. For these reasons, scientists have explored the potential use of biological clocks towards creating a universal age-determination method. Two biological clocks, tooth layer annulation and otolith layering have found universal appeal. Both methods are highly invasive and most appropriate for post-mortem age-at-death estimation. More recently, attributes of cellular ageing previously explored in humans have been adapted to studying ageing in animals for the use of less-invasive molecular methods for determining age. Here, we review two such methods, assessment of methylation and telomere length, describing (i) what they are, (ii) how they change with age, and providing (iii) a summary and meta-analysis of studies that have explored their utility in animal age determination. We found that both attributes have been studied across multiple vertebrate classes, however, telomere studies were used before methylation studies and telomere length has been modelled in nearly twice as many studies. Telomere length studies included in the review often related changes to stress responses and illustrated that telomere length is sensitive to environmental and social stressors and, in the absence of repair mechanisms such as telomerase or alternative lengthening modes, lacks the ability to recover. Methylation studies, however, while also detecting sensitivity to stressors and toxins, illustrated the ability to recover from such stresses after a period of accelerated ageing, likely due to constitutive expression or reactivation of repair enzymes such as DNA methyl transferases. We also found that both studied attributes have parentally heritable features, but the mode of inheritance differs among taxa and may relate to heterogamy. Our meta-analysis included more than 40 species in common for methylation and telomere length, although both analyses included at least 60 age-estimation models. We found that methylation outperforms telomere length in terms of predictive power evidenced from effect sizes (more than double that observed for telomeres) and smaller prediction intervals. Both methods produced age correlation models using similar sample sizes and were able to classify individuals into young, middle, or old age classes with high accuracy. Our review and meta-analysis illustrate that both methods are well suited to studying age in animals and do not suffer significantly from variation due to differences in the lifespan of the species, genome size, karyotype, or tissue type but rather that quantitative method, patterns of inheritance, and environmental factors should be the main considerations. Thus, provided that complex factors affecting the measured trait can be accounted for, both methylation and telomere length are promising targets to develop as biomarkers for age determination in animals.

Tilt perception is different in the pitch and roll planes in human.

Neurophysiological tests probing the vestibulo-ocular, colic and spinal pathways are the gold standard to evaluate the vestibular system in clinics. In contrast, vestibular perception is rarely tested despite its potential usefulness in professional training and for the longitudinal follow-up of professionals dealing with complex man-machine interfaces, such as aircraft pilots. This is explored here using a helicopter flight simulator to probe the vestibular perception of pilots. The vestibular perception of nine professional helicopter pilots was tested using a full flight helicopter simulator. The cabin was tilted six times in roll and six times in pitch (-15°, -10°, -5°, 5°, 10° and 15°) while the pilots had no visual cue. The velocities of the outbound displacement of the cabin were kept below the threshold of the semicircular canal perception. After the completion of each movement, the pilots were asked to put the cabin back in the horizontal plane (still without visual cues). The order of the 12 trials was randomized with two additional control trials where the cabin stayed in the horizontal plane but rotated in yaw (-10° and +10°). Pilots were significantly more precise in roll (average error in roll: 1.15 ± 0.67°) than in pitch (average error in pitch: 2.89 ± 1.06°) (Wilcoxon signed-rank test: p < 0.01). However, we did not find a significant difference either between left and right roll tilts (p = 0.51) or between forward and backward pitch tilts (p = 0.59). Furthermore, we found that the accuracies were significantly biased with respect to the initial tilt. The greater the initial tilt was, the less precise the pilots were, although maintaining the direction of the tilt, meaning that the error can be expressed as a vestibular error gain in the ability to perceive the modification in the orientation. This significant result was found in both roll (Friedman test: p < 0.01) and pitch (p < 0.001). However, the pitch trend error was more prominent (gain = 0.77 vs gain = 0.93) than roll. This study is a first step in the determination of the perceptive-motor profile of pilots, which could be of major use for their training and their longitudinal follow-up. A similar protocol may also be useful in clinics to monitor the aging process of the otolith system with a simplified testing device.

Otolin-1, an otolith- and otoconia-related protein, controls calcium carbonate bioinspired mineralization.

BACKGROUND: Otoliths and otoconia are calcium carbonate biomineral structures that form in the inner ear of fish and humans, respectively. The formation of these structures is tightly linked to the formation of an organic matrix framework with otolin-1, a short collagen-like protein from the C1q family as one of its major constituents. METHODS: In this study, we examined the activity of recombinant otolin-1 originating from Danio rerio and Homo sapiens on calcium carbonate bioinspired mineralization with slow-diffusion method and performed crystals characterization with scanning electron microscopy, two-photon excited fluorescence microscopy, confocal laser scanning microscopy and micro-Raman spectroscopy. RESULTS: We show that both proteins are embedded in the core of CaCO3 crystals that form through the slow-diffusion mineralization method. Both of them influence the morphology but do not change the polymorphic mineral phase. D.rerio otolin-1 also closely adheres to the crystal surface. GENERAL SIGNIFICANCE: The results suggest, that otolin-1 is not a passive scaffold, but is directly involved in regulating the morphology of the resulting calcium carbonate biocrystals.

The Impact of the Angular Head Movement's Velocity during Diagnostic Maneuvers on Proper Benign Positional Paroxysmal Vertigo Diagnosis and Therapy.

Based on the current state of the BPPV field, there are no guidelines that specify an angular head movement's velocity (AHMV) during diagnostic maneuvers of BPPV. The aim of this study was to evaluate the impact of AHMV during diagnostic maneuvers on proper BPPV diagnosis and therapy. The analysis covered the results obtained in 91 patients with a positive result of the Dix-Hallpike (D-H) maneuver or the roll test. The patients were divided into four groups based on values of AHMV (high 100-200°/s and low 40-70°/s) and the BPPV type (posterior: PC-BPPV or horizontal: HC-BPPV). The parameters of the obtained nystagmuses were analyzed and compared to AHMV. There was a significant negative correlation between AHMV and latency of nystagmus in all study groups. Furthermore, there was a significant positive correlation between AHMV and both maximum slow phase velocity and average frequency of nystagmus in the PC-BPPV groups, whereas it was not observed in the HC-BPPV patients. Complete relief of symptoms was reported after 2 weeks and was better in patients diagnosed with maneuvers performed with high AHMV. High AHMV during the D-H maneuver allows the nystagmus to be more visible, increasing the sensitivity of diagnostic tests and is crucial for a proper diagnosis and therapy.

Otolith mineralogy affects otolith shape asymmetry: a comparison of hatchery and natural origin Coho salmon (Oncorhynchus kisutch).

Many aspects of natural and hatchery origin salmonid genetics, physiology, behaviour, anatomy and life histories have been compared due to the concerns about what effects domestication and hatchery rearing conditions have on fitness. Genetic and environmental stressors associated with hatchery rearing could cause greater developmental instability (DI), and therefore a higher degree of fluctuating asymmetry (FA) in various bilaterally paired characters, such as otoliths. Nonetheless, to appropriately infer the effects of DI on otolith asymmetry, otolith mineralogy must be accounted for. Vateritic otoliths differ substantially from aragonitic otoliths in terms of mass and shape and can artificially inflate any measurement of FA if not properly accounted for. In this study, measurements of otolith asymmetry between hatchery and natural origin Coho salmon Oncorhynchus kisutch from three different river systems were compared to assess the overall differences in asymmetry when the calcium carbonate polymorph accounted for 59.3% of otoliths from hatchery origin O. kisutch was vateritic compared to 11.7% of otoliths from natural origin O. kisutch. Otolith mineralogy, rather than origin, was the most significant factor influencing the differences in asymmetry for each shape metric. When only aragonitic otoliths were compared, there was no difference in absolute asymmetry between hatchery and natural origin O. kisutch. The authors recommend other researchers to assess otolith mineralogy when conducting studies regarding otolith morphometrics and otolith FA.

Fish otoliths as biological dosimeter: internal dose calculation.

Otoliths are organs used by fish for hearing and keeping balance. They consist of biogenic crystals of hydroxyapatite and do not contain any living cells. Upon exposure to ionizing radiation, otolith hydroxyapatite accumulates radiation-induced stable CO2- radicals whose amount is proportional to absorbed dose. In electron paramagnetic resonance (EPR) dosimetry, carbonate ions are registered and, hence, the total accumulated dose in the fish otolith can be quantified. Therefore, otoliths can be used as individual fish dosimeters to support radiobiological and radioecological studies. An important aspect of otolith-based EPR dosimetry on fish from contaminated water bodies is the potential presence of bone-seeking 90Sr. Consequently, cumulative absorbed doses measured with EPR in otoliths may reflect the superposition of internal exposure to 90Sr/90Y and external exposure due to radionuclides circulating in soft tissue of the fish as well as due to environmental contamination. The objective of the present study was to develop a method that allows for an assessment of the contribution of 90Sr to the total dose in otolith. The method has been tested using otoliths from seven fish taken from reservoirs located in the Southern Urals contaminated with radionuclides including 90Sr. It has been shown that dose to otoliths is largely determined by 90Sr in the hydroxyapatite. The internal dose component can be calculated using activity concentration-to-dose conversion factors, which vary slightly in the range of 2.0-2.8 × 10-3 Gy year-1 per Bq g-1 depending on fish species and age. Internal doses to fish from water bodies with different levels of 90Sr contamination were calculated in the range from 2 mGy to ~ 200 Gy. External dose contribution was derived for two fish only to be about 100 and 40 Gy. It is concluded that EPR dosimetry on fish otoliths is a promising tool when external exposure prevails or is comparable to internal exposure due to 90Sr.

Electrodermal and postural responses in dizzy adults: Diagnostic indicators of vestibular migraine.

INTRODUCTION: No reliable biometric measurement of vestibular involvement with migraine is currently available. OBJECTIVE: Measures of autonomic nervous system and postural responses could serve as quantifiable indicators of vestibular involvement with migraine. METHODS: A convenience sample of 22 young healthy adults (34±9 years old) and 23 young adults (34±8 years old) diagnosed with vestibular migraine (VM) participated. A rod and frame test and clinical outcome measures of dizziness and mobility were administered. Participants stood on foam while viewing two dynamic virtual environments. Trunk acceleration in three planes and electrodermal activity (EDA) were assessed with wearable sensors. Linear mixed models were used to examine magnitude and smoothness of trunk acceleration and tonic and phasic EDA. A Welch's t-test and associations between measures were assessed with a Pearson Correlation Coefficient. Effect sizes of group mean differences were calculated using Cohen's d. RESULTS: Visual dependence was present in 83% of the VM population. Individuals with VM exhibited lower baseline EDA (t(4.17) = -7.2, p = 0.001) and greater normalized trunk accelerations in the vertical (t(42.5) = 2.861, p = 0.006) and medial (t(46.6) = 2.65, p = 0.01) planes than healthy participants. Tonic EDA activity increased significantly across the period of the trial (F (1,417) = 23.31, p = 0.001) in the VM group. Significant associations appeared between vertical trunk acceleration and EDA, Dizziness Handicap Inventory, and Activities of Balance Confidence tools. CONCLUSIONS: Higher tonic EDA activity in healthy adults results in more accurate postural reactions. Results support the supposition that EDA activity and postural acceleration are significantly different between VM and healthy individuals when accommodating for postural instability and visual-vestibular conflict.

Stranding of Mesopelagic Fishes in the Canary Islands.

Most mesopelagic fishes perform large diel vertical migrations from the deep-sea zone to the surface. Although there is a trade-off between a higher food availability at the upper layers and an energy cost and predation risk, incursion towards the surface also implies a transport by currents, where the fish are exposed to a stranding risk on the coast. Here, we reported the first documented stranding of mesopelagic fishes along the southeast shore of Gran Canaria Island. Our study hypothesized that (1) the influence of the Canary Current, (2) the dominant incidence of the Trade Winds during summer, and (3) the presence of an upwelling filament coupled with an anticyclonic eddy south of Gran Canaria Island were the causative mechanisms of the strandings. Diaphus dumerilii (Myctophidae family) was the main species found as observed from an external morphological analysis using traditional taxonomy. The otolith contour analysis suggested the presence of other Diaphus spp. and Lobianchia dofleini. Nevertheless, the otolith morphological features described in the literature suggested that all the specimens were actually D. dumerelii. Errors in the identification were mainly due to the high intraspecific variability found in the otolith morphology. Even so, two patterns of oval and elliptic shapes were described with significant differences in its morphometry.