Recovery of burrowing behavior after spinal cord injury in the larval sea lamprey

© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Katz, H. R., Fouke, K. E., Losurdo, N. A., & Morgan, J. R. Recovery of burrowing behavior after spinal cord injury in the larval sea lamprey. Biological Bulletin, 239(3), (2020): 174-182, doi:10.1086/711365.Following traumatic spinal cord injury, most mammalian species are unable to achieve substantial neuronal regeneration and often experience loss of locomotor function. In contrast, larval sea lampreys (Petromyzon marinus) spontaneously recover normal swimming behaviors by 10–12 weeks post-injury, which is supported by robust regeneration of spinal axons. While recovery of swimming behavior is well established, the lamprey’s ability to recover more complex behaviors, such as burrowing, is unknown. Here we evaluated the lamprey’s ability to burrow into a sand substrate over the typical time course of functional recovery (1–11 weeks post-injury). Compared to uninjured control lampreys, which burrow rapidly and completely, spinal-transected animals did not attempt burrowing until 2 weeks post-injury; and they often did not succeed in fully covering their entire body in the sand. Burrowing behavior gradually improved over post-injury time, with most animals burrowing partially or completely by 9–11 weeks post-injury. Burrowing behavior has two components: the initial component that resembles swimming with propagated body undulations and the final component that pulls the tail under the sand. While the duration of the initial component did not differ between control and spinal-transected animals across the entire recovery period, the duration of the final component in spinal-transected animals was significantly longer at all time points measured. These data indicate that, after spinal cord injury, lampreys are able to recover burrowing behaviors, though some deficits persist.We thank Eduardo Guadarrama for performing lamprey transection surgeries and Dr. Eric D. Tytell (Tufts University) for valuable discussion and feedback, as well the Marine Biological Laboratory for providing funding support. NAL was funded in part by a National Science Foundation-sponsored Research Experiences for Undergraduates (REU) program at the Marine Biological Laboratory: “Biological Discovery in Woods Hole” (grant 1659604; PIs: A. Mensinger, V. Martinez Acosta)

Regulation of endometrial regeneration; mechanisms contributing to repair and restoration of tissue integrity following menses

The human endometrium is a dynamic, multi-cellular tissue that lines the inside of the uterine cavity. During a woman’s reproductive lifespan the endometrium is subjected to cyclical episodes of proliferation, angiogenesis, differentiation/decidualisation, shedding (menstruation), repair and regeneration in response to fluctuating levels of oestrogen and progesterone secreted by the ovaries. The endometrium displays unparalleled, tightly regulated, tissue remodelling resulting in a healed, scar-free tissue following menses or parturition. Mechanisms responsible for initiation of menses have been well documented: following progesterone withdrawal there is an increase in inflammatory mediators, focal hypoxia and induction and activation of matrix-degrading enzymes. In contrast, the molecular and cellular changes responsible for rapid, regulated, tissue repair at a time when oestrogen and progesterone are low are poorly understood. Histological studies using human menstrual phase endometrium have revealed that tissue destruction and shedding occur in close proximity to re-epithelialisation/repair. It has been proposed that re-epithelialisation involves proliferation of glandular epithelial cells in the remaining basal compartment; there is also evidence for a contribution from the underlying stroma. A role for androgens in the regulation of apoptosis of endometrial stromal cells has been proposed but the impact of androgens on tissue repair has not been investigated. Studies using human xenografts and primates have been used to model some aspects of the impact of progesterone withdrawal but simultaneous shedding (menses) and repair have not been modelled in mice; the species of choice for translational biomedical research. In the course of the studies described in this thesis, the following aims have been addressed: 1. To establish a model of menses in the mouse which mimics menses in women, namely; simultaneous breakdown and repair, overt menstruation, immune cell influx, tissue necrosis and re-epithelialisation. 2. To use this model to determine if the stromal cell compartment contributes to endometrial repair. 3. To examine the impact of androgens on the regulation of menses (shedding) and repair. An informative mouse model of endometrial breakdown that was characterised by overt menses, as well as rapid repair, was developed. Immunohistological evidence for extensive tissue remodelling including active angiogenesis, transient hypoxia, epithelial cell-specific proliferation and re-epithelialisation were obtained by examining uterine tissues recovered during an “early window of breakdown and repair” (4 to 24 hours after progesterone withdrawal). Novel data included identification of stromal cells that expressed epithelial cell markers, close to the luminal surface following endometrial shedding, suggesting a role for mesenchymal to epithelial transition (MET) in re-epithelialisation of the endometrium. In support of this idea, array and qRTPCR analyses revealed dynamic changes in expression of mRNAs encoded by genes known to be involved in MET during the window of breakdown and repair. Roles for hypoxia and tissue-resident macrophages in breakdown and tissue remodelling were identified. Treatment of mice with dihydrotestosterone to mimic concentrations of androgens circulated in women at the time of menses had an impact on the timing and duration of endometrial breakdown. Array analysis revealed altered expression of genes implicated in MET and angiogenesis/inflammation highlighting a potential, previously unrecognised role for androgens in regulation of tissue turnover during menstruation. In summary, using a newly refined mouse model new insights were obtained, implicating androgens and stromal MET in restoration of endometrial tissue homeostasis during menstruation. These findings may inform development of new treatments for disorders associated with aberrant repair such as heavy menstrual bleeding and endometriosis

A Large-Scale Pattern of Ontogenetic Shape Change in Ray-Finned Fishes.

Fishes exhibit a remarkable diversity of body shape as adults; however, it is unknown whether this diversity is reflected in larval stage morphology. Here we investigate the relationship between larval and adult body shape as expressed by body elongation. We surveyed a broad range of ray-finned fish species and compared body shape at larval and adult stages. Analysis shows that the vast majority of fish are more elongate at the larval stage than at the adult stage, and that adults display greater interspecies variation than larvae. We found that the superorder Elompomorpha is unique because many species within the group do not follow the observed elongation trends. These results indicate that much of the diversity observed in adults is achieved in post-larval stages. We suggest that larval morphology is subject to common constraints across the phylogeny

A Large-Scale Pattern of Ontogenetic Shape Change in Ray-Finned Fishes

Fishes exhibit a remarkable diversity of body shape as adults; however, it is unknown whether this diversity is reflected in larval stage morphology. Here we investigate the relationship between larval and adult body shape as expressed by body elongation. We surveyed a broad range of ray-finned fish species and compared body shape at larval and adult stages. Analysis shows that the vast majority of fish are more elongate at the larval stage than at the adult stage, and that adults display greater interspecies variation than larvae. We found that the superorder Elompomorpha is unique because many species within the group do not follow the observed elongation trends. These results indicate that much of the diversity observed in adults is achieved in post-larval stages. We suggest that larval morphology is subject to common constraints across the phylogeny

Comparison of larval and adult elongation ratios.

<p>(a) The distribution of larval (blue) and adult (red) elongation ratios. The number of species (x-axis) observed for a given elongation ratio (y-axis). (b) Larval elongation ratio plotted against adult elongation ratio. Each point represents a single species and colors correspond to the orders as presented in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0150841#pone.0150841.g001" target="_blank">Fig 1</a>. The regression line is plotted for species that demonstrated a decrease in elongation ratio through ontogeny (circles) as well as for those species that demonstrated an increase in elongation ratio (triangles). Colors correspond to the orders as presented in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0150841#pone.0150841.g001" target="_blank">Fig 1</a>.</p

Individual larval and adult elongation ratios.

<p>A phylogeny of all species utilized in this study assembled for visualization purposes: orders are indicated in different colors with arbitrary branch lengths. Genus and species name for every species measured in this study with corresponding larval (filled circle) and adult (open circle) elongation ratios (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0150841#pone.0150841.s001" target="_blank">S1 Table</a> for exact values). The measurements plotted are the same as those used for statistical analyses (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0150841#sec002" target="_blank">methods</a> section for selection criteria). Colors correspond to the orders from which the species were selected.</p

Activating transcription factor 3 (ATF3) is a highly conserved pro-regenerative transcription factor in the vertebrate nervous system

© The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Katz, H. R., Arcese, A. A., Bloom, O., & Morgan, J. R. Activating transcription factor 3 (ATF3) is a highly conserved pro-regenerative transcription factor in the vertebrate nervous system. Frontiers in Cell and Developmental Biology, 10, (2022): 824036, https://doi.org/10.3389/fcell.2022.824036.The vertebrate nervous system exhibits dramatic variability in regenerative capacity across species and neuronal populations. For example, while the mammalian central nervous system (CNS) is limited in its regenerative capacity, the CNS of many other vertebrates readily regenerates after injury, as does the peripheral nervous system (PNS) of mammals. Comparing molecular responses across species and tissues can therefore provide valuable insights into both conserved and distinct mechanisms of successful regeneration. One gene that is emerging as a conserved pro-regenerative factor across vertebrates is activating transcription factor 3 (ATF3), which has long been associated with tissue trauma. A growing number of studies indicate that ATF3 may actively promote neuronal axon regrowth and regeneration in species ranging from lampreys to mammals. Here, we review data on the structural and functional conservation of ATF3 protein across species. Comparing RNA expression data across species that exhibit different abilities to regenerate their nervous system following traumatic nerve injury reveals that ATF3 is consistently induced in neurons within the first few days after injury. Genetic deletion or knockdown of ATF3 expression has been shown in mouse and zebrafish, respectively, to reduce axon regeneration, while inducing ATF3 promotes axon sprouting, regrowth, or regeneration. Thus, we propose that ATF3 may be an evolutionarily conserved regulator of neuronal regeneration. Identifying downstream effectors of ATF3 will be a critical next step in understanding the molecular basis of vertebrate CNS regeneration.This work was supported by: a Morton Cure Paralysis Fund Research Grant (to HK); a NIH/NINDS R03 Research Grant (No. 1R03NS078519) and the New York State Spinal Cord Injury Research Board (to OB); and the Marine Biological Laboratory Eugene Bell Center Endowment, Rowe Endowment for Regenerative Biology, and Charles Evans Research Development award (to JM)

Refining Low Physical Activity Measurement Improves Frailty Assessment in Advanced Lung Disease and Survivors of Critical Illness

RationaleThe frail phenotype has gained popularity as a clinically relevant measure in adults with advanced lung disease and in critical illness survivors. Because respiratory disease and chronic illness can greatly limit physical activity, the measurement of participation in traditional leisure time activities as a frailty component may lead to substantial misclassification of frailty in pulmonary and critical care patients.ObjectivesTo test and validate substituting the Duke Activity Status Index (DASI), a simple 12-item questionnaire, for the Minnesota Leisure Time Physical Activity (MLTA) questionnaire, a detailed questionnaire covering 18 leisure time activities, as the measure of low activity in the Fried frailty phenotype (FFP) instrument.MethodsIn separate multicenter prospective cohort studies of adults with advanced lung disease who were candidates for lung transplant and older survivors of acute respiratory failure, we assessed the FFP using either the MLTA or the DASI. For both the DASI and MLTA, we evaluated content validity by testing floor effects and construct validity through comparisons with conceptually related factors. We tested the predictive validity of substituting the DASI for the MLTA in the FFP assessment using Cox models to estimate associations between the FFP and delisting/death before transplant in those with advanced lung disease and 6-month mortality in older intensive care unit (ICU) survivors.ResultsAmong 618 adults with advanced lung disease and 130 older ICU survivors, the MLTA had a substantially greater floor effect than the DASI (42% vs. 1%, and 49% vs. 12%, respectively). The DASI correlated more strongly with strength and function measures than did the MLTA in both cohorts. In models adjusting for age, sex, comorbidities, and illness severity, substitution of the DASI for the MLTA led to stronger associations of the FFP with delisting/death in lung transplant candidates (FFP-MLTA hazard ratio [HR], 1.42; 95% confidence interval [CI], 0.55-3.65; FFP-DASI HR, 2.99; 95% CI, 1.03-8.65) and with mortality in older ICU survivors (FFP-MLTA HR, 2.68; 95% CI, 0.62-11.6; FFP-DASI HR, 5.71; 95% CI, 1.34-24.3).ConclusionsThe DASI improves the construct and predictive validity of frailty assessment in adults with advanced lung disease or recent critical illness. This simple questionnaire should replace the more complex MLTA in assessing the frailty phenotype in these populations