Relationship between Hypoxia and Hypercapnia Tolerance and Life Expectancy.

The review discusses the potential relationship between hypoxia resistance and longevity, the influence of carbon dioxide on the mechanisms of aging of the mammalian organism, and intermittent hypercapnic-hypoxic effects on the signaling pathways of aging mechanisms. In the article, we focused on the potential mechanisms of the gero-protective efficacy of carbon dioxide when combined with hypoxia. The review summarizes the possible influence of intermittent hypoxia and hypercapnia on aging processes in the nervous system. We considered the perspective variants of the application of hypercapnic-hypoxic influences for achieving active longevity and the prospects for the possibilities of developing hypercapnic-hypoxic training methods.

Cognitive decline related to chronic kidney disease as an exclusion factor from kidney transplantation: results from an international survey.

Background and hypothesis: There seems to be a lack of consensus on the necessity and the modality of psychological and specifically cognitive assessment of candidates for kidney transplantation. Both points are often delegated to individual hospitals/centres, whereas international guidelines are inconsistent. We think it is essential to investigate professionals' opinions to advance towards a consistent clinical practice. Methods: This paper presents the results of an international survey among clinical professionals, mainly nephrologists from the CONNECT (Cognitive decline in Nephro-Neurology: European Cooperative Target) network and beyond (i.e. from personal contacts of CONNECT members). The survey investigated their opinions about the question of whether cognitive decline in patients with chronic kidney disease may affect their eligibility for kidney transplantation. Results: Our results show that most clinicians working with patients affected by chronic kidney disease think that cognitive decline may challenge their eligibility for transplantation despite data that suggest that, in some patients, cognitive problems improve after kidney transplantation. Conclusion: We conclude that three needs emerge as particularly pressing: defining agreed-on standards for a multifaceted and multifactorial assessment (i.e. including both clinical/medical and psychosocial factors) of candidates with chronic kidney disease to kidney transplantation; further investigating empirically the causal connection between chronic kidney disease and cognition; and further investigating empirically the possible partial reversibility of cognitive decline after kidney transplantation.

Green treasures: Investigating the biodiversity potential of equine yards through the presence and quality of landscape features in the Netherlands.

At a time of mounting ecological crises and biodiversity loss, there is an urgent need for nature-based solutions. Equestrian properties cover a considerable proportion of the European rural and peri-urban landscape and provide much potential for integrating ecosystem services, such as the inclusion of small landscape features. The aim of this study was to investigate the presence and quality of landscape features (LF) to help determine how the equine sector can contribute to the agro-ecological transition. Using a citizen science approach, 87 commercial and 420 private yard owners reported the type, frequency and geometric dimension of LFs and additional biodiversity enhancing features. A hierarchical multivariate regression was used to determine how equine property characteristics explain variation in the Percentage Property Coverage (PPC) of LFs. The model explained 47% of the variation of PPC. The variables that explained significant variation in PPC included Yard size, Number of LFs, Tree rows, Fruit orchard, Wild hedges, Flowering strips, Buffer strips, Embankments and Cluttered corners. Commercial yards are significantly larger with significantly more horses and on average only 9% (±13.87%) of the property was covered by LFs whilst private yards had significantly more coverage of LFs with on average 12% (±14.77%). These findings highlight the substantial yet untapped potential of equine yards in fostering biodiversity, suggesting that the equine sector could play an important role in the agro-ecological transition. To encourage more biodiverse-inclusive yard designs, tailored strategies should consider the diverse factors influencing equine yard design, including existing knowledge, client demands, financial considerations, and equine health and welfare.

The Role of microRNAs in Epigenetic Regulation of Signaling Pathways in Neurological Pathologies.

In recent times, there has been a significant increase in researchers' interest in the functions of microRNAs and the role of these molecules in the pathogenesis of many multifactorial diseases. This is related to the diagnostic and prognostic potential of microRNA expression levels as well as the prospects of using it in personalized targeted therapy. This review of the literature analyzes existing scientific data on the involvement of microRNAs in the molecular and cellular mechanisms underlying the development of pathologies such as Alzheimer's disease, cerebral ischemia and reperfusion injury, and dysfunction of the blood-brain barrier.

Blind fish have cells that see light.

Most animals on earth have evolved under daily light-dark cycles and consequently possess a circadian clock which regulates much of their biology, from cellular processes to behaviour. There are however some animals that have invaded dark ecosystems and have adapted to an apparently arrhythmic environment. One such example is the Mexican blind cavefish Astyanax mexicanus, a species complex with over 30 different isolated cave types, including the founding surface river fish. These cavefish have evolved numerous fascinating adaptations to the dark, such as loss of eyes, reduced sleep phenotype and alterations in their clock and light biology. While cavefish are an excellent model for studying circadian adaptations to the dark, their rarity and long generational time makes many studies challenging. To overcome these limitations, we established embryonic cell cultures from cavefish strains and assessed their potential as tools for circadian and light experiments. Here, we show that despite originating from animals with no eyes, cavefish cells in culture are directly light responsive and show an endogenous circadian rhythm, albeit that light sensitivity is relatively reduced in cave strain cells. Expression patterns are similar to adult fish, making these cavefish cell lines a useful tool for further circadian and molecular studies.

Strongly enhanced sensitivities of CMOS compatible plasmonic titanium nitride nanohole arrays for refractive index sensing under oblique incidence.

Titanium nitride (TiN) is a complementary metal-oxide-semiconductor (CMOS) compatible material with large potential for the fabrication of plasmonic structures suited for device integration. However, the comparatively large optical losses can be detrimental for application. This work reports a CMOS compatible TiN nanohole array (NHA) on top of a multilayer stack for potential use in integrated refractive index sensing with high sensitivities at wavelengths between 800 and 1500 nm. The stack, consisting of the TiN NHA on a silicon dioxide (SiO2) layer with Si as substrate (TiN NHA/SiO2/Si), is prepared using an industrial CMOS compatible process. The TiN NHA/SiO2/Si shows Fano resonances in reflectance spectra under oblique excitation, which are well reproduced by simulation using both finite difference time domain (FDTD) and rigorous coupled-wave analysis (RCWA) methods. The sensitivities derived from spectroscopic characterizations increase with the increasing incident angle and match well with the simulated sensitivities. Our systematic simulation-based investigation of the sensitivity of the TiN NHA/SiO2/Si stack under varied conditions reveals that very large sensitivities up to 2305 nm per refractive index unit (nm RIU-1) are predicted when the refractive index of superstrate is similar to that of the SiO2 layer. We analyze in detail how the interplay between plasmonic and photonic resonances such as surface plasmon polaritons (SPPs), localized surface plasmon resonances (LSPRs), Rayleigh Anomalies (RAs), and photonic microcavity modes (Fabry-Pérot resonances) contributes to this result. This work not only reveals the tunability of TiN nanostructures for plasmonic applications but also paves the way to explore efficient devices for sensing in broad conditions.

Changing Hearts and Minds in the Equestrian World One Behaviour at a Time.

Equestrianism is currently facing a range of pressing challenges. These challenges, which are largely based on evolving attitudes to ethics and equine wellbeing, have consequences for the sport's social licence to operate. The factors that may have contributed to the current situation include overarching societal trends, specific aspects of the equestrian sector, and factors rooted in human nature. If equestrianism is to flourish, it is evident that much needs to change, not the least, human behaviour. To this end, using established behaviour change frameworks that have been scientifically validated and are rooted in practice-most notably, Michie et al.'s COM-B model and Behaviour Change Wheel-could be of practical value for developing and implementing equine welfare strategies. This review summarises the theoretical underpinnings of some behaviour change frameworks and provides a practical, step-by-step approach to designing an effective behaviour change intervention. A real-world example is provided through the retrospective analysis of an intervention strategy that aimed to increase the use of learning theory in (educational) veterinary practice. We contend that the incorporation of effective behaviour change interventions into any equine welfare improvement strategy may help to safeguard the future of equestrianism.

Genome Announcement: The Draft Genome of the Carrot Cyst Nematode Heterodera Carotae.

Heterodera carotae, the carrot cyst nematode, is a significant pest affecting carrot globally. Here we present the draft genome of H. carotae, which was generated from short read libraries from Illumina HiSeq technology, and the corresponding genome annotation.

Neuropsychological evaluation of cognitive disorders in children after COVID-19.

The article presents the results of neuropsychological remote and face-to-face testing of 25 children aged 12 to 17 years in the nearest (during and 1-2 weeks after the treatment) and later period (2-12 months) after COVID-19 infection with predominant respiratory tract infection, organized in Ekaterinburg in the State Autonomous Institution "Children's Hospital № 8". Indication of family contact with patients with a new coronavirus infection was found in all patients, a positive nasopharyngeal swab for SARS-CoV-2 RNA by PCR was found in 58%, non-focal neurological complaints were found in 54% of children. The control group consisted of 25 pupils of Moscow comprehensive schools (14 girls and 11 boys) aged between 12 and 16 years who were examined before the pandemic. The methods included: investigation of the kinesthetic, spatial, dynamic, graphic praxis; auditory-motor coordination; visual, object-constructive gnosis; auditory-speech, visual memory; voluntary attention; thinking. Significant differences with the results of neuropsychological tests performed in children in the control group were found, allowing us to assert impairment of memory, attention, visual gnosis, visual-spatial function, kinesthetic and dynamic praxis, verbal and non-verbal component of thinking. According to A.R. Luria's theory, the topic of the disorders involves the temporo-parieto-occipital, mediobasal, frontotemporal parts of the brain, the reticular formation and limbic structures. This necessitates the development of corrective educational programs and an in-depth diagnostic algorithm that determines the morphological substrate of cognitive disorders in children, who have undergone COVID-19.

Transcriptional response of Meloidogyne incognita to non-fumigant nematicides.

There is limited research about the impacts of new nematicides, including fluazaindolizine, fluopyram, and fluensulfone, on the plant-parasitic nematode Meloidogyne incognita, despite it being a pervasive agricultural pest. In this study, M. incognita second-stage juveniles were exposed for 24-h to fluensulfone, fluazaindolizine, fluopyram, and oxamyl and total RNA was extracted and sequenced using next-generation sequencing to determine gene expression. The effects of nematicide exposure on cellular detoxification pathways, common differentially expressed (DE) genes, and fatty acid and retinol-binding genes were examined. Fluopyram and oxamyl had the smallest impacts on the M. incognita transcriptome with 48 and 151 genes that were DE, respectively. These compounds also elicited a weak response in the cellular detoxification pathway and fatty acid and retinol-binding (FAR) genes. Fluensulfone and fluazaindolizine produced robust transcriptional responses with 1208 and 2611 DE genes, respectively. These compounds had strong impacts on cellular detoxification, causing differential regulation of transcription factors and genes in the detox pathway. These compounds strongly down-regulated FAR genes between 52-85%. Having a greater understanding of how these compounds function at a molecular level will help to promote proper stewardship, aid with nematicide discovery, and help to stay a step ahead of nematicide resistance.

Risk Factors for Locomotive Crew Members Depending on Their Place of Work.

PURPOSE: The purpose of this study is to examine the prevalence of workplace exposure, behavior, and individual health conditions, along with resulting medical activity among locomotive crew members depending on their place of work. PATIENTS AND METHODS: Participants included 5585 train drivers and 3723 train drivers' assistants (7% of the total train operators in the Russian Federation). Measured height and weight were used to calculate body mass index (BMI), and waist circumference, pulse rate, and blood pressure were also measured. The risk assessment was conducted using the STEPS tool. The level of commitment to a Healthy Lifestyle was assessed based on World Health Organization recommendations. Occupational risk factors were surveyed. Morbidity was analyzed over the past year. RESULTS: The lowest frequency of work exposure risk factors was found for employees of the Trans-Baikal railway; the highest was among Krasnoyarsk, North, and South-East. The participants from the Far East and October Railways had the lowest self-reported frequency of behavioral risk factors. The participants from the Eastern Siberian, October, and Southern Urals railways had the lowest occurrence of individual health conditions. The participants from the East Siberian, Far East, Kuibyshev, and Sverdlovsk railways were the least likely to visit their doctor, take temporary disability leave, or be hospitalized. The total assessed Healthy Lifestyle commitment index was higher for participants from the Far Eastern and Southern Urals railways. The participants from the Moscow and October railways were the least committed to a Healthy Lifestyle. CONCLUSIONS: Significant differences exist between risk factors and Healthy Lifestyle commitment between railways. Future research should examine changes due to a new corporate health program introduced in 2020.

Transcriptional changes of biochemical pathways in Meloidogyne incognita in response to non-fumigant nematicides.

Meloidogyne incognita is a destructive and economically important agricultural pest. Similar to other plant-parasitic nematodes, management of M. incognita relies heavily on chemical controls. As old, broad spectrum, and toxic nematicides leave the market, replacements have entered including fluensulfone, fluazaindolizine, and fluopyram that are plant-parasitic nematode specific in target and less toxic to applicators. However, there is limited research into their modes-of-action and other off-target cellular effects caused by these nematicides in plant-parasitic nematodes. This study aimed to broaden the knowledge about these new nematicides by examining the transcriptional changes in M. incognita second-stage juveniles (J2) after 24-h exposure to fluensulfone, fluazaindolizine, and fluopyram as well as oxamyl, an older non-fumigant nematicide. Total RNA was extracted and sequenced using Illumina HiSeq to investigate transcriptional changes in the citric acid cycle, the glyoxylate pathway, [Formula: see text]-fatty acid oxidation pathway, oxidative phosphorylation, and acetylcholine neuron components. Observed transcriptional changes in M. incognita exposed to fluopyram and oxamyl corresponded to their respective modes-of-action. Potential targets for fluensulfone and fluazaindolizine were identified in the [Formula: see text]-fatty acid oxidation pathway and 2-oxoglutarate dehydrogenase of the citric acid cycle, respectively. This study provides a foundation for understanding how potential nematicide resistance could develop, identifies cellular pathways as potential nematicide targets, and determines targets for confirming unknown modes-of-action.

Rigorous coupled-wave analysis of a multi-layered plasmonic integrated refractive index sensor.

We apply the rigorous coupled-wave analysis (RCWA) to the design of a multi-layer plasmonic refractive index sensor based on metallic nanohole arrays integrated with a Ge-on-Si photodetector. RCWA simulations benefit from modularity, frequency-domain computation, and a relatively simple computational setup. These features make the application of RCWA particularly interesting in the case of the simulation and optimization of multi-layered devices in conjunction with plasmonic nanostructures, where other methods can be computationally too expensive for multi-parameter optimization. Our application example serves as a demonstration that RCWA can be utilized as a low-cost, efficient method for device engineering.

Lower pelvic tilt, lower pelvic incidence, and increased external rotation of the iliac wing in patients with femoroacetabular impingement due to acetabular retroversion compared to hip dysplasia.

AIMS: The effect of pelvic tilt (PT) and sagittal balance in hips with pincer-type femoroacetabular impingement (FAI) with acetabular retroversion (AR) is controversial. It is unclear if patients with AR have a rotational abnormality of the iliac wing. Therefore, we asked: are parameters for sagittal balance, and is rotation of the iliac wing, different in patients with AR compared to a control group?; and is there a correlation between iliac rotation and acetabular version? METHODS: A retrospective, review board-approved, controlled study was performed including 120 hips in 86 consecutive patients with symptomatic FAI or hip dysplasia. Pelvic CT scans were reviewed to calculate parameters for sagittal balance (pelvic incidence (PI), PT, and sacral slope), anterior pelvic plane angle, pelvic inclination, and external rotation of the iliac wing and were compared to a control group (48 hips). The 120 hips were allocated to the following groups: AR (41 hips), hip dysplasia (47 hips) and cam FAI with normal acetabular morphology (32 hips). Subgroups of total AR (15 hips) and high acetabular anteversion (20 hips) were analyzed. Statistical analysis was performed using analysis of variance with Bonferroni correction. RESULTS: PI and PT were significantly decreased comparing AR (PI 42° (SD 10°), PT 4° (SD 5°)) with dysplastic hips (PI 55° (SD 12°), PT 10° (SD 6°)) and with the control group (PI 51° (SD 9°) and PT 13° (SD 7°)) (p < 0.001). External rotation of the iliac wing was significantly increased comparing AR (29° (SD 4°)) with dysplastic hips (20°(SD 5°)) and with the control group (25° (SD 5°)) (p < 0.001). Correlation between external rotation of the iliac wing and acetabular version was significant and strong (r = 0.81; p < 0.001). Correlation between PT and acetabular version was significant and moderate (r = 0.58; p < 0.001). CONCLUSION: These findings could contribute to a better understanding of hip pain in a sitting position and extra-articular subspine FAI of patients with AR. These patients have increased iliac external rotation, a rotational abnormality of the iliac wing. This has implications for surgical therapy with hip arthroscopy and acetabular rim trimming or anteverting periacetabular osteotomy (PAO). Cite this article: Bone Jt Open 2021;2(10):813-824.

Alpha Carbonic Anhydrase 5 Mediates Stimulation of ATP Synthesis by Bicarbonate in Isolated Arabidopsis Thylakoids.

We studied bicarbonate-induced stimulation of photophosphorylation in thylakoids isolated from leaves of Arabidopsis thaliana plants. This stimulation was not observed in thylakoids of wild-type in the presence of mafenide, a soluble carbonic anhydrase inhibitor, and was absent in thylakoids of two mutant lines lacking the gene encoding alpha carbonic anhydrase 5 (αCA5). Using mass spectrometry, we revealed the presence of αCA5 in stromal thylakoid membranes of wild-type plants. A possible mechanism of the photophosphorylation stimulation by bicarbonate that involves αCA5 is proposed.

Posterior Extra-articular Ischiofemoral Impingement Can Be Caused by the Lesser and Greater Trochanter in Patients With Increased Femoral Version: Dynamic 3D CT-Based Hip Impingement Simulation of a Modified FABER Test.

BACKGROUND: Posterior extra-articular hip impingement has been described for valgus hips with increased femoral version (FV). These patients can present clinically with lack of external rotation (ER) and extension and with a positive posterior impingement test. But we do not know the effect of the combination of deformities, and the impingement location in early flexion is unknown. PURPOSE: To evaluate patient-specific 3-dimensional computed tomography (3D CT) scans of hips with increased FV and control hips for differences in range of motion, location and prevalence of osseous posterior intra- and extra-articular hip impingement. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Osseous 3D models based on segmentation of 3D CT scans were analyzed for 52 hips (38 symptomatic patients) with positive posterior impingement test and increased FV (>35°). There were 26 hips with an increased McKibbin instability index >70 (unstable hips). Patients were mainly female (96%), with an age range of 18 to 45 years. Of them, 21 hips had isolated increased FV (>35°); 22 hips had increased FV and increased acetabular version (AV; >25°); and 9 valgus hips (caput-collum-diaphyseal angle >139°) had increased FV and increased AV. The control group consisted of 20 hips with normal FV, normal AV, and no valgus (caput-collum-diaphyseal angle <139°). Validated 3D CT-based collision detection software for impingement simulation was used to calculate impingement-free range of motion and location of hip impingement. Surgical treatment was performed after the 3D CT-based impingement simulation in 27 hips (52%). RESULTS: Hips with increased FV had significantly (P < .001) decreased extension and ER at 90° of flexion as compared with the control group. Posterior impingement was extra-articular (92%) in hips with increased FV. Valgus hips with increased FV and AV had combined intra- and extra-articular impingement. Posterior hip impingement occurred between the ischium and the lesser trochanter at 20° of extension and 20° of ER. Impingement was located between the ischium and the greater trochanter or intertrochanteric area at 20° of flexion and 40° of ER, with a modification of the flexion-abduction-ER (FABER) test. CONCLUSION: Posterior extra-articular ischiofemoral hip impingement can be caused by the lesser and greater trochanter or the intertrochanteric region. We recommend performing the modified FABER test during clinical examination in addition to the posterior impingement test for female patients with high FV. In addition, 3D CT can help for surgical planning, such as femoral derotation osteotomy and/or hip arthroscopy or resection of the lesser trochanter.

Biochemical MRI With dGEMRIC Corresponds to 3D-CT Based Impingement Location for Detection of Acetabular Cartilage Damage in FAI Patients.

BACKGROUND: Anterior femoroacetabular impingement (FAI) is associated with labral tears and acetabular cartilage damage in athletic and young patients. Delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) is an imaging method for detecting early damage to cartilage. PURPOSE: We evaluated the following questions: (1) What is the sensitivity and specificity of morphological magnetic resonance imaging (MRI) and dGEMRIC for detecting cartilage damage? Do the mean acetabular and femoral dGEMRIC indices differ between (2) superior acetabular clock positions with and without impingement and (3) between cam- and pincer-type FAI? STUDY DESIGN: Cohort study (diagnosis); Level of evidence, 2. METHODS: This was a retrospective comparative study of 21 hips (20 patients with symptomatic anterior FAI) without osteoarthritis on anteroposterior radiographs. Morphological MRI and dGEMRIC (3.0-T, 3-dimensional [3D] T1 maps, dual-flip angle technique) of the same hip joint were compared. Intraoperative acetabular cartilage damage was assessed in patients who underwent surgical treatment. Computed tomography (CT)-based 3D bone models of the same hip joint were used as the gold standard for the detection of impingement, and dGEMRIC indices and zones of morphologic damage were compared with the CT-based impingement zones. RESULTS: Of the 21 hips, 10 had cam-type FAI and 8 had pincer-type FAI according to radiographs. The mean age was 30 ± 9 years (range, 17-48 years), 71% were female, and surgical treatment was performed in 52%. We found a significantly higher sensitivity (69%) for dGEMRIC compared with morphological MRI (42%) in the detection of cartilage damage (P < .001). The specificity of dGEMRIC was 83% and accuracy was 78%. The mean peripheral acetabular and femoral dGEMRIC indices for clock positions with impingement (485 ± 141 and 440 ± 121 ms) were significantly lower compared with clock positions without impingement (596 ± 183 and 534 ± 129 ms) (P < .001). Hips with cam-type FAI had significantly lower acetabular dGEMRIC indices compared with hips with pincer-type FAI on the anterosuperior clock positions (1 to 3 o'clock) (P = .018). CONCLUSION: MRI with dGEMRIC was more sensitive than morphological MRI, and lower dGEMRIC values were found for clock positions with impingement as detected on 3D-CT. This could aid in patient-specific diagnosis of FAI, preoperative patient selection, and surgical decision making to identify patients with cartilage damage who are at risk for inferior outcomes after hip arthroscopy.

Genomic Analyses of Globodera pallida, A Quarantine Agricultural Pathogen in Idaho.

Globodera pallida is among the most significant plant-parasitic nematodes worldwide, causing major damage to potato production. Since it was discovered in Idaho in 2006, eradication efforts have aimed to contain and eradicate G. pallida through phytosanitary action and soil fumigation. In this study, we investigated genome-wide patterns of G. pallida genetic variation across Idaho fields to evaluate whether the infestation resulted from a single or multiple introduction(s) and to investigate potential evolutionary responses since the time of infestation. A total of 53 G. pallida samples (~1,042,000 individuals) were collected and analyzed, representing five different fields in Idaho, a greenhouse population, and a field in Scotland that was used for external comparison. According to genome-wide allele frequency and fixation index (Fst) analyses, most of the genetic variation was shared among the G. pallida populations in Idaho fields pre-fumigation, indicating that the infestation likely resulted from a single introduction. Temporal patterns of genome-wide polymorphisms involving (1) pre-fumigation field samples collected in 2007 and 2014 and (2) pre- and post-fumigation samples revealed nucleotide variants (SNPs, single-nucleotide polymorphisms) with significantly differentiated allele frequencies indicating genetic differentiation. This study provides insights into the genetic origins and adaptive potential of G. pallida invading new environments.

Photonic-plasmonic mode coupling in nanopillar Ge-on-Si PIN photodiodes.

Incorporating group IV photonic nanostructures within active top-illuminated photonic devices often requires light-transmissive contact schemes. In this context, plasmonic nanoapertures in metallic films can not only be realized using CMOS compatible metals and processes, they can also serve to influence the wavelength-dependent device responsivities. Here, we investigate crescent-shaped nanoapertures in close proximity to Ge-on-Si PIN nanopillar photodetectors both in simulation and experiment. In our geometries, the absorption within the devices is mainly shaped by the absorption characteristics of the vertical semiconductor nanopillar structures (leaky waveguide modes). The plasmonic resonances can be used to influence how incident light couples into the leaky modes within the nanopillars. Our results can serve as a starting point to selectively tune our device geometries for applications in spectroscopy or refractive index sensing.

Daily rhythms in heartbeat rate are intrinsic to the zebrafish heart.

It is a well-established fact that different tissues within the body contain their own circadian clocks or pacemakers, where it is proposed that the clock controls the local, daily cell biology of that organ.1,2 In mammals, these peripheral clocks work in concert with and are entrained by rhythmic signals arising from the suprachiasmatic nucleus (SCN) in the hypothalamus of the animal, among other systemic cues.2 In the case of zebrafish, the circadian system appears to be highly decentralized with each tissue not only having an internal circadian clock, but also being directly light entrained.1 Several years ago, we showed that the zebrafish heart contains its own circadian pacemaker at the gene expression level.1 This is also the case in mammals, where the circadian clock controls approximately 10% of the genes expressed in the heart.3 However, heart rate itself is generally thought to be regulated by several well-described autonomic cues, neurotransmitters, and hormones. In this study, we report that, for larval zebrafish hearts, the daily change in heartbeat rate is not only clock-controlled in vivo, but that this rhythm also persists in vitro, indicating that the cardiac circadian clock itself can directly drive this major physiological oscillation.