Compensatory Response Research Articles

Plumage color degradation indicates reproductive effort: an experiment

Plumage color has traditionally been regarded as a static ornamental trait, but evidence is accumulating for significant color changes without molt that typically reduce the conspicuousness of ornamentation. In some species, the social partner seems to increase its reproductive investment if the color trait is experimentally enhanced, suggesting that color change could act as a signal. However, the information content of this signal is so far unclear. For example, birds in poor condition or making greater effort may deteriorate more severely. We used brood size manipulations to alter the reproductive effort of male and female collared flycatchers Ficedula albicollis. Both sexes showed less severe decline in some reflectance attribute of their white breast when their brood was experimentally reduced. In each sex, greater deterioration of the reflectance trait affected by the manipulation was accompanied by increased feeding rate by the partner. These feeding patterns do not prove, but are consistent with, a compensatory response by the partner to induced degradation. The manipulation effects on color change we detected confirm for the first time that plumage color deterioration can indicate current reproductive effort, thereby providing a potential fitness advantage to social partners that react to such deterioration.

Climate warming and bumble bee declines: the need to consider sub-lethal heat, carry-over effects, and colony compensation.

Global declines in abundance and diversity of insects are now well-documented and increasingly concerning given the critical and diverse roles insects play in all ecosystems. Habitat loss, invasive species, and anthropogenic chemicals are all clearly detrimental to insect populations, but mounting evidence implicates climate change as a key driver of insect declines globally. Warming temperatures combined with increased variability may expose organisms to extreme heat that exceeds tolerance, potentially driving local extirpations. In this context, heat tolerance limits (e.g., critical thermal maximum, CTmax) have been measured for many invertebrates and are often closely linked to climate regions where animals are found. However, temperatures well below CTmax may also have pronounced effects on insects, but have been relatively less studied. Additionally, many insects with out-sized ecological and economic footprints are colonial (e.g., ants, social bees, termites) such that effects of heat on individuals may propagate through or be compensated by the colony. For colonial organisms, measuring direct effects on individuals may therefore reveal little about population-level impacts of changing climates. Here, we use bumble bees (genus Bombus) as a case study to highlight how a limited understanding of heat effects below CTmax and of colonial impacts and responses both likely hinder our ability to explain past and predict future climate change impacts. Insights from bumble bees suggest that, for diverse invertebrates, predicting climate change impacts will require a more nuanced understanding of the effects of heat exposure and additional studies of carry-over effects and compensatory responses by colonies.

191 Recovery of Growth and Body Composition in 10-kg Pigs after a 6-Week Growth Attenuation by Ammonium Chloride Additions to Feed

Abstract This project aimed to develop nutritional strategies to reduce pig growth > 50% for 2 to 6 weeks during crisis management. Previously growth was attenuated by 2.0% NH4Cl additions to hold growth (HG) diets. Compensatory growth was evident after withdrawal of NH4Cl. However, tissue composition was not quantified. The HG diets were formulated to reduce lysine, P, and K and increase Cl. Assumptions were that excess Cl interacts with limited K to create an “apparent” K deficiency, which limits protein accretion. The current experiment assessed body composition responses during recovery from HG diets with 2.0% NH4Cl (HGCL) by feeding control (Ctl) diets or Ctl diets fortified with 150% of lysine, P, and K requirements (+Lys+P+K). At 10 kg, 34 barrows were individually housed and randomly assigned to 1 of 4 dietary treatments with free access to assigned diets and water throughout the trial. During the HG phase pigs were fed either Ctl or HGCL diets until 25 kg; 6 weeks for pigs fed HGCl diets. An additional diet was included to validate K and Cl interactions (0.29:1 K:Cl ratio) in growth attenuation. Potassium bicarbonate was added to the HGCl diet (HGCl+K) to restore a 1.26:1 K:Cl ratio. At 25 kg BW, pigs were fed either Ctl or +Lys+P+K diets until 45 kg body weight (BW). Pig, feed weights, and body composition derived from whole-body DXA scans during the hold (HG, 10 to 25 kg) and recovery (Rec, 25 to 45 kg) phases allowed calculations of BW gain, nutrient intake, and measurements of whole-body bone mineral, fat, and lean gain. Growth of pigs fed HGCl diets was reduced (P < 0.01) by approximately 50% compared with Ctl pigs during the HG phase (Table 1). Pigs fed HGCl diets required 23 more days to grow from 10 to 25 kg. Similar reductions (P < 0.01) in bone mineral and lean gain, but not fat gain, were detected in pigs fed HGCl diets during the HG phase. Addition of K to the HGCl diet partially restored gain, bone, and lean gain (P < 0.01). Compensatory responses in weight, bone, fat, and lean gain were evident in HG pigs fed Ctl diets during Rec. Pigs previously fed HGCl diets compensated and only required 14 extra days to reach 45 kg compared with Ctl. Additions of lysine, P, and K allowed greater (P < 0.01) compensation in BW, bone, and lean, but not fat gain over a 20 kg recovery phase. These results confirm a successful strategy to hold pigs during crisis management with potential benefits of compensatory growth and improved body composition during recovery. Whether the improved lean gain was attributed to the additional lysine, P, or K was not determined in this experiment.

Differential effects of Western diet and traumatic muscle injury on skeletal muscle metabolic regulation in male and female mice.

This study was designed to develop an understanding of the pathophysiology of traumatic muscle injury in the context of Western diet (WD; high fat and high sugar) and obesity. The objective was to interrogate the combination of WD and injury on skeletal muscle mass and contractile and metabolic function. Male and female C57BL/6J mice were randomized into four groups based on a two-factor study design: (1) injury (uninjured vs. volumetric muscle loss [VML]) and (2) diet (WD vs. normal chow [NC]). Electrophysiology was used to test muscle strength and metabolic function in cohorts of uninjured+NC, uninjured+WD, VML+NC and VML+WD at 8weeks of intervention. VML-injured male and female mice both exhibited decrements in muscle mass (-17%, P<0.001) and muscle strength (-28%, P<0.001); however, VML+WD females had a 28% greater muscle mass compared to VML+NC females (P=0.034), a compensatory response not detected in males. VML-injured male and female mice both had lower carbohydrate- and fat-supported muscle mitochondrial respiration (JO2 ) and less electron conductance through the electron transport system (ETS); however, male VML-WD had 48% lower carbohydrate-supported JO2 (P=0.014) and 47% less carbohydrate-supported electron conductance (P=0.026) compared to male VML+NC, and this diet-injury phenotype was not present in females. ETS electron conductance starts with complex I and complex II dehydrogenase enzymes at the inner mitochondrial membrane, and male VML+WD had 31% less complex I activity (P=0.004) and 43% less complex II activity (P=0.005) compared to male VML+NC. This was a diet-injury phenotype not present in females. Pyruvate dehydrogenase (PDH), β-hydroxyacyl-CoA dehydrogenase, citrate synthase, α-ketoglutarate dehydrogenase and malate dehydrogenase metabolic enzyme activities were evaluated as potential drivers of impaired JO2 in the context of diet and injury. There were notable male and female differential effects in the enzyme activity and post-translational regulation of PDH. PDH enzyme activity was 24% less in VML-injured males, independent of diet (P<0.001), but PDH enzyme activity was not influenced by injury in females. PDH enzyme activity is inhibited by phosphorylation at serine-293 by PDH kinase 4 (PDK4). In males, there was greater total PDH, phospho-PDHser293 and phospho-PDH-to-total PDH ratio in WD mice compared to NC, independent of injury (P≤0.041). In females, PDK4 was 51% greater in WD compared to NC, independent of injury (P=0.025), and was complemented by greater phospho-PDHser293 (P=0.001). Males are more susceptible to muscle metabolic dysfunction in the context of combined WD and traumatic injury compared to females, and this may be due to impaired metabolic enzyme functions.

Impact of COVID-19 pandemic on healthy of children and families in Italy. Qualitative EPaS-ISS study

Abstract Background This study is the qualitative component of a national research carried out in collaboration with the WHO/Europe Childhood Obesity Surveillance Initiative. The aim was to explore the COVID-19 pandemic effects on health behaviours, needs, and psychosocial resources of children and their family in Italy. Methods According to the convergent parallel mixed-method, this qualitative study was carried out simultaneously with the quantitative one. Purposeful sampling was used to recruit parents, teachers, key respondents and children. The data were collected by online focus groups (FG) except the FG with children. FGs transcriptions were analysed through a categorical approach using NVivo. Results Six FGs were conducted between April-May 2022 (65 adults; 14 children). Participants highlight how the pandemic had consequences at multiple levels: individual, family, community and social. At the individual level, data showed how thinning out interpersonal relationships and emotional experiences affected children's psychosocial well-being and learning. As for nutrition, it was observed that food was used as both an emotional comfort (e.g. snack consumption) and an opportunity for family aggregation. The ban on going out and social distancing penalized movement and sport. The lack of physical activity and changes in daily routines also affected sleeping. The screen exposure increased due to distance learning and video calls; parents reported excessive use of video games and a difficulty in limiting screen time. The impact of the closures on foreign children and from deprived backgrounds, including school dropouts, was also an issue. Creative play, care of plants and animals, and activities with the family were some of the resources emerging. Conclusions Qualitative perspective enriches research on changes in children and families’ habits during the pandemic, showing needs and difficulties and suggesting some necessary actions for the health and education systems. Key messages • The COVID-19 pandemic had an impact on children that might persist beyond the pandemic period. • Health and education policies must offer a compensatory response to the children and families’ needs.

Thermal Preconditioning Alters the Stability of Hump-Snout Whitefish (Coregonus fluviatilis) and Its Hybrid Form, Showing Potential for Aquaculture.

One of the little-studied ways that climate warming or temperature increases in aquaculture could affect aquatic animals is through accelerated aging. This study is dedicated to understanding the principles of molecular and cellular aging in the target tissues of juvenile whitefishes (Yenisei hump-snout whitefish and its hybrid) under the influence of acute heat stress (up to 26 °C), and the effects of thermal preconditioning as pre-adaptation. Non-adapted stressed hump-snout whitefish showed a higher induction threshold for functionally active mitochondria in the blood and a decrease in telomerase activity in the liver after heat shock exposure as a long-term compensatory response to prevent telomere shortening. However, we observed heat-induced telomere shortening in non-adapted hybrids, which can be explained by a decrease in mitochondrial membrane stability and a gradual increase in energy demand, leading to a decrease in protective telomerase activity. The pre-adapted groups of hump-snout whitefish and hybrids showed a long-term or delayed response of telomerase activity to heat shock, which served as a therapeutic mechanism against telomere shortening. We concluded that the telomerase and telomere responses to thermal stress demonstrate plasticity of tolerance limits and greater stability in hump-snout whitefish compared with hybrids.

Silencing suppressor of cytokine signaling 3 induces apoptosis and activates the p-STAT3/NF-κB pathway in hypoxic cultivated H9c2 cells.

Suppressor of cytokine signaling 3 (SOCS3) plays a significant role in the process of myocardial adaptation to chronic hypoxia. SOCS3 finely regulates cell signaling cross-talk that occurs between NF-κB and STAT3 during the compensatory protective response. However, the role and mechanism of SOCS3 in hypoxic cardiomyocytes are not fully understood. In the study, we investigated the effect of SOCS3 on the p65 and STAT3 signaling pathways and further examined the potential molecular mechanism involved in regulating apoptosis. Our data showed that SOCS3 silencing could upregulate Ac-p65, p-p65, and p-STAT3 expression in nuclear extracts of H9c2 cells that received hypoxic treatment for 24, 48, and 72 h. SOCS3 silencing also remarkably increased the DNA-binding activity of the p65 motif in hypoxic cultivated H9c2 cells. We also found that SOCS3 knockdown increased cleaved-caspase-3, Bax, and PUMA expression and decreased cleaved PARP and Bcl-2 in expression in hypoxic H9c2 cells. Silencing of SOCS3 caused an increase in LDH leakage from injured cardiomyocytes and reduced cell viability under conditions of hypoxic stress. Furthermore, SOCS3 silencing enhanced the apoptosis of H9c2 cells at 72 h of hypoxia. These findings suggest that knockdown of SOCS3 leads to excessive activation of the NF-κB pathway, which, in turn, might promote apoptosis under conditions of chronic hypoxia.

Do Not Cut Off Your Tail: A Mega-Analysis of Responses to Auditory Perturbation Experiments.

The practice of removing "following" responses from speech perturbation analyses is increasingly common, despite no clear evidence as to whether these responses represent a unique response type. This study aimed to determine if the distribution of responses to auditory perturbation paradigms represents a bimodal distribution, consisting of two distinct response types, or a unimodal distribution. This mega-analysis pooled data from 22 previous studies to examine the distribution and magnitude of responses to auditory perturbations across four tasks: adaptive pitch, adaptive formant, reflexive pitch, and reflexive formant. Data included at least 150 unique participants for each task, with studies comprising younger adult, older adult, and Parkinson's disease populations. A Silverman's unimodality test followed by a smoothed bootstrap resampling technique was performed for each task to evaluate the number of modes in each distribution. Wilcoxon signed-ranks tests were also performed for each distribution to confirm significant compensation in response to the perturbation. Modality analyses were not significant (p > .05) for any group or task, indicating unimodal distributions. Our analyses also confirmed compensatory reflexive responses to pitch and formant perturbations across all groups, as well as adaptive responses to sustained formant perturbations. However, analyses of sustained pitch perturbations only revealed evidence of adaptation in studies with younger adults. The demonstration of a clear unimodal distribution across all tasks suggests that following responses do not represent a distinct response pattern, but rather the tail of a unimodal distribution. https://doi.org/10.23641/asha.24282676.

Macromolecular condensation buffers intracellular water potential

Optimum protein function and biochemical activity critically depends on water availability because solvent thermodynamics drive protein folding and macromolecular interactions1. Reciprocally, macromolecules restrict the movement of ‘structured’ water molecules within their hydration layers, reducing the available ‘free’ bulk solvent and therefore the total thermodynamic potential energy of water, or water potential. Here, within concentrated macromolecular solutions such as the cytosol, we found that modest changes in temperature greatly affect the water potential, and are counteracted by opposing changes in osmotic strength. This duality of temperature and osmotic strength enables simple manipulations of solvent thermodynamics to prevent cell death after extreme cold or heat shock. Physiologically, cells must sustain their activity against fluctuating temperature, pressure and osmotic strength, which impact water availability within seconds. Yet, established mechanisms of water homeostasis act over much slower timescales2,3; we therefore postulated the existence of a rapid compensatory response. We find that this function is performed by water potential-driven changes in macromolecular assembly, particularly biomolecular condensation of intrinsically disordered proteins. The formation and dissolution of biomolecular condensates liberates and captures free water, respectively, quickly counteracting thermal or osmotic perturbations of water potential, which is consequently robustly buffered in the cytoplasm. Our results indicate that biomolecular condensation constitutes an intrinsic biophysical feedback response that rapidly compensates for intracellular osmotic and thermal fluctuations. We suggest that preserving water availability within the concentrated cytosol is an overlooked evolutionary driver of protein (dis)order and function.

Increased peripheral of brain-derived neurotrophic factor levels in phenylketonuric patients treated with l-carnitine

Phenylketonuria (PKU) is the most common inherited metabolic disorders caused by severe deficiency or absence of phenylalanine hydroxylase activity that converts phenylalanine (Phe) to tyrosine. PKU patients were treated with a Phe restricted diet supplemented with a special formula containing l-carnitine (L-car), well-known antioxidant compound. The lack of treatment can cause neurological and cognitive impairment, as severe mental retardation, neuronal cell loss and synaptic density reduction. Although Phe has been widely demonstrated to be involved in PKU neurotoxicity, the mechanisms responsible for the CNS injury are still not fully known. In this work, we evaluated markers of neurodegeneration, namely BDNF (brain-derived neurotrophic factor), PAI-1 total (Plasminogen activator inhibitor-1 total), Cathepsin D, PDGF AB/BB (platelet-derived growth factor), and NCAM (neuronal adhesion molecule) in plasma of PKU patients at early and late diagnosis and under treatment. We found decreased Phe levels and increased L-car concentrations in PKU patients treated with L-car compared to the other groups, indicating that the proposed treatment was effective. Furthermore, we found increased BDNF levels in the patients under treatment compared to patients at early diagnosis, and a positive correlation between BDNF and L-car and a negative correlation between BDNF and Phe. Our results may indicate that in PKU patients treated with L-car there is an attempt to adjust neuronal plasticity and recover the damage suffered, reflecting a compensatory response to brain injury.

Accentuated Paralimbic and Reduced Mesolimbic D2/3-Impulsivity Associations in Parkinson's Disease.

Impulsivity is a behavioral trait that is elevated in many neuropsychiatric disorders. Parkinson's disease (PD) patients can exhibit a specific pattern of reward-seeking impulsive-compulsive behaviors (ICBs), as well as more subtle changes to generalized trait impulsivity. Prior studies in healthy controls (HCs) suggest that trait impulsivity is regulated by D2/3 autoreceptors in mesocorticolimbic circuits. While altered D2/3 binding is noted in ICB+ PD patients, there is limited prior assessment of the trait impulsivity-D2/3 relationship in PD, and no prior direct comparison with patterns in HCs. We examined 54 PD (36 M; 18 F) and 31 sex- and age-matched HC (21 M; 10 F) subjects using [18F]fallypride, a high-affinity D2/3 receptor ligand, to measure striatal and extrastriatal D2/3 nondisplaceable binding potential (BPND). Subcortical and cortical assessment exclusively used ROI or exploratory-voxelwise methods, respectively. All completed the Barratt Impulsiveness Scale, a measure of trait impulsivity. Subcortical ROI analyses indicated a negative relationship between trait impulsivity and D2/3 BPND in the ventral striatum and amygdala of HCs but not in PD. By contrast, voxelwise methods demonstrated a positive trait impulsivity-D2/3 BPND correlation in ventral frontal olfactocentric-paralimbic cortex of subjects with PD but not HCs. Subscale analysis also highlighted different aspects of impulsivity, with significant interactions between group and motor impulsivity in the ventral striatum, and attentional impulsivity in the amygdala and frontal paralimbic cortex. These results suggest that dopamine functioning in distinct regions of the mesocorticolimbic circuit influence aspects of impulsivity, with the relative importance of regional dopamine functions shifting in the neuropharmacological context of PD.SIGNIFICANCE STATEMENT The biological determinants of impulsivity have broad clinical relevance, from addiction to neurodegenerative disorders. Here, we address biomolecular distinctions in Parkinson's disease. This is the first study to evaluate a large cohort of Parkinson's disease patients and age-matched healthy controls with a measure of trait impulsivity and concurrent [18F]fallypride PET, a method that allows quantification of D2/3 receptors throughout the mesocorticolimbic network. We demonstrate widespread differences in the trait impulsivity-dopamine relationship, including (1) loss of subcortical relationships present in the healthy brain and (2) emergence of a new relationship in a limbic cortical area. This illustrates the loss of mechanisms of behavioral regulation present in the healthy brain while suggesting a potential compensatory response and target for future investigation.

CTRP13 ablation improves systemic glucose and lipid metabolism

ObjectiveTissue crosstalk mediated by secreted hormones underlies the integrative control of metabolism. We previously showed that CTRP13/C1QL3, a secreted protein of the C1q family, can improve glucose metabolism and insulin action in vitro and reduce food intake and body weight in mice when centrally delivered. A role for CTRP13 in regulating insulin secretion in isolated islets has also been demonstrated. It remains unclear, however, whether the effects of CTRP13 on cultured cells and in mice reflect the physiological function of the protein. Here, we use a loss-of-function mouse model to address whether CTRP13 is required for metabolic homeostasis. MethodsWT and Ctrp13 knockout (KO) mice fed a standard chow or a high-fat diet were subjected to comprehensive metabolic phenotyping. Transcriptomic analyses were carried out on visceral and subcutaneous fat, liver, and skeletal muscle to identify pathways altered by CTRP13 deficiency. RNA-seq data was further integrated with the Metabolic Syndrome in Man (METSIM) cohort data. Adjusted regression analysis was used to demonstrate that genetic variation of CTRP13 expression accounts for a significant proportion of variance between differentially expressed genes (DEGs) in adipose tissue and metabolic traits in humans. ResultsContrary to expectation, chow-fed Ctrp13-KO male mice had elevated physical activity, lower body weight, and improved lipid handling. On a high-fat diet (HFD), Ctrp13-KO mice of either sex were consistently more active and leaner. Loss of CTRP13 reduced hepatic glucose output and improved glucose tolerance, insulin sensitivity, and triglyceride clearance, though with notable sex differences. Consistent with the lean phenotype, transcriptomic analyses revealed a lower inflammatory profile in visceral fat and liver. Reduced hepatic steatosis was correlated with the suppression of lipid synthesis and enhanced lipid catabolism gene expression. Visceral fat had the largest number of DEGs and mediation analyses on the human orthologs of the DEGs suggested the potential causal contribution of CTRP13 to human metabolic syndrome. ConclusionsOur results suggest that CTRP13 is a negative metabolic regulator, and its deficiency improves systemic metabolic profiles. Our data also suggest the reduction in circulating human CTRP13 levels seen in obesity and diabetes may reflect a compensatory physiologic response to counteract insulin resistance.

Disturbed white matter integrity on diffusion tensor imaging in young children with epilepsy

To evaluate whether abnormalities in white matter (WM) integrity are present in young children with epilepsy. Twelve children (3-6 years old) with epilepsy and six matched healthy controls were recruited for brain diffusion tensor imaging (DTI). Track-based spatial statistics (TBSS) was used to analyse and compare DTI indices of mean diffusivity (MD), fractional anisotropy (FA), axial and radial diffusivity (AD/RD) between patients and controls, and correlations between clinical variables and DTI parameters were analysed. Compared with controls, patients showed increased FA in the left superior corona radiata and increased AD in the bilateral superior corona radiata. In children with generalised epilepsy, FA was increased in the left external capsule, while AD was decreased in the body of the corpus callosum, the left external capsule and the left superior longitudinal fasciculus. In those with focal epilepsy, FA was increased in the genu and body of the corpus callosum, and RD was decreased in the genu of the corpus callosum and left external capsule. Compared with partial epilepsy, generalised epilepsy was associated with increased FA in the right anterior corona radiata and decreased RD in the right anterior corona radiata and the genu and body of the corpus callosum. No significant correlations were observed between clinical variables and DTI parameters. The results of this study indicate that the microstructure of the white matter is disturbed by epileptic discharges and a compensatory response occurs during early brain development.

Compensation for exposure to increased environmental temperatures is costly in a montane, desert lizard

Extreme weather events will increase in frequency and intensity with climate change. Physiological and behavioral modulation during these extreme climatic events will likely facilitate persistence of ectothermic species, but these compensatory responses may be costly. We transplanted greater short-horned lizards (Phrynosoma hernandesi) from a cool, high-elevation site to a warm, low-elevation site to quantify the costs of acute temperature increases. We predicted that transplanting lizards to the warmer environment would increase mass loss relative to Control lizards by increasing DEE, thermal tolerance, and circulating CORT and altering spatial ecology and basking behavior. We found that transplanted lizards experienced a significant decline in mass, but this decline was not a result of increased energetic expenditure or circulating CORT. Rather, this loss appeared to be driven by changes in basking behavior and space use. Our data suggest changes in thermoregulatory behavior alleviated the direct effects of a greater environmental thermal load. However, these behavioral changes were associated with their own costs, likely due to limitations on resource acquisition resulting from decreases in basking and foraging activities. Our research suggests compensation for increased temperatures does not necessarily eliminate the costs of rapid environmental change.

OR12-02 NRF2 Is Essential For Expanding Pancreatic Beta-Cell Mass During Pregnancy

Abstract Disclosure: S. Baumel-Alterzon: None. A. Garcia-Ocana: None. D.K. Scott: None. The late stages of the mammalian pregnancy are accompanied with increased insulin resistance due to the increased glucose demand of the growing fetus. Therefore, as a compensatory response, in order to maintain the maternal normal blood glucose levels, maternal beta-cell mass expands leading to increased insulin release. Beta-cell proliferation, beta-cell neogenesis, and decreased beta-cell apoptosis, are major contributors for the beta-cell adaptive response during pregnancy. Defects in these cellular processes can lead to gestational diabetes mellitus (GDM). GDM, which occurs in ∼7-8% of the total pregnancy cases within the U.S, results in adverse outcomes for both the mother and newborn. This highlights the urgent need for exploring the yet undefined intracellular mechanisms that regulate functional beta-cell mass expansion during pregnancy. GWAS analysis revealed several mutations in the Nrf2 antioxidant pathway that are associated with diabetes. Additionally, we previously found that Nrf2 is required for adaptive beta-cell expansion after high fat feeding via stimulation of beta-cell proliferation, increased beta-cell survival, and maintenance of beta-cell identity. Interestingly, Nrf2 expression levels are increased by 4.3-fold (+/- 6.60, p&amp;lt;0.05, n=3-4) in maternal beta-cells during pregnancy, peaking at gestational day (GD)19, while returning to normal levels postpartum. Based on these observations, we hypothesize that Nrf2 might play an important role in expanding beta-cell mass during pregnancy and that disruption of Nrf2 expression or function might lead to GDM. In order to test our hypothesis, we generated tamoxifen (Tam)-induced beta cell-specific deletion of Nrf2 in female mice by crossing MIP-CreERTTAM with Nrf2lox/lox mice (βNrf2KO). In order to exclude any effect of Tam on pregnancy outcomes, females mice were injected with Tam (or vehicle control) a month before gestation. Pancreata were harvested at GD15 or GD19 and immunolabeled with Ki67 and insulin (proliferation assay), TUNEL and insulin (apoptotic assay) or insulin alone (beta-cell mass analysis). Our results show that βNrf2KO mice exhibit 70% reduction (+/- 0.25, p&amp;lt;0.01, n=4-6) in beta-cell proliferation and a 0.13% increase in beta-cell death (+/- 0.03, p&amp;lt;0.05, n=4-6) at GD15 compared to littermate controls. Importantly, βNrf2KO pregnant mice display a remarkable decrease in beta-cell mass at GD19 (50%) (+/- 0.68, p&amp;lt;0.05, n=4) compared with control mice, accompanied by a trending decrease in plasma insulin and increase in blood glucose. No changes were observed in the average number of embryos between βNrf2KO and control pregnant mice. We conclude that Nrf2 is required for beta-cell mass expansion during pregnancy by controlling beta-cell proliferation and survival and alterations in Nrf2 action could potentially lead to development of GDM. Presentation: Friday, June 16, 2023

SAT075 Beta Cells Adapt To Insulin Resistance Via Posttranslational Modification Of The Translation Factor eIF5A

Abstract Disclosure: C. Anderson: None. A. Kulkarni: None. B. Maier: None. S.A. Tersey: None. R. Anderson: None. R.G. Mirmira: None. Prior to type 2 diabetes onset, β cells adapt to insulin resistance through compensation—a process that maintains insulin secretion and glucose homeostasis. Our lab has previously shown that β cell compensation requires the activity of deoxyhypusine synthase (DHPS), which post-translationally catalyzes the formation of the amino acid hypusine at Lys50 of eukaryotic initiation factor eIF5A. Although hypusinated eIF5A is required for β cell compensation, it is unclear if unhypusinated eIF5A limits this compensatory response. To identify the role of unhypusinated eIF5A, we used the following animal and cell-based models: RNAi knockdown and transgenic zebrafish; inducible, β cell-specific knockout mice fed a high fat diet; and cultured HEK-293 cells. Zebrafish embryos injected with morpholinos to reduce global DHPS (and accumulate unhypusinated eIF5A) showed stunted exocrine pancreas growth at 3 days post-fertilization. Although, those injected with anti-eIF5A morpholinos (to deplete all eIF5A) showed normal pancreas growth. Transgenic overexpression of a mutant eIF5A incapable of hypusination resulted in reduced pancreas size in zebrafish. Although a unique function of unhypusinated eIF5A has not yet been documented, these findings suggest that the presence of unhypusinated eIF5A may be the major driver of altered pancreas phenotypes. Similarly, following 4 weeks of high fat diet feeding and obesity, mice lacking total eIF5A in β cells had improved glucose tolerance compared to mice lacking DHPS in β cells, despite similar weight gain and insulin sensitivity. To clarify the molecular mechanisms behind the damaging role of unhypusinated eIF5A, we performed polyribosome profiling to measure translation in lysates from HEK-293 cells in which either DHPS or total eIF5A were depleted by RNAi. Whereas loss of total eIF5A slightly reduced mRNA translation elongation, loss of DHPS (and accumulation of unhypusinated eIF5A) reduced mRNA translation initiation. Further experiments in HEK-293 cells suggest that unhypusinated eIF5A increases levels of phosphorylated eIF2α (an inhibitor of global mRNA translation) by specifically interacting with the kinase GCN2. Taken together, our data provide evidence that DHPS deficiency and obesity conditions impair β cell function, in part, from the accumulation of the unhypusinated form of eIF5A. Our studies reveal a mechanism in which β cells respond to obesity by regulating mRNA translation through the balance between hypusinated and unhypusinated forms of eIF5A. Presentation: Saturday, June 17, 2023

FRI424 Allopregnanolone Levels Are Elevated in the Follicular Phase and Predict Premenstrual Depression and Anxiety Symptom Severity in Women with Menstrually Related Mood Disorder

Abstract Disclosure: A. Kimball: None. J. Bourassa: None. M. Chicote: None. A.V. Gerweck: None. L.E. Dichtel: Other; Self; Dr. Dichtel is a Mass General Brigham (MGB) Innovation Fellow hosted by Third Rock Ventures. Financial interests were reviewed and are managed by MGH and MGB in accordance with their COI policies. K.K. Miller: None. Menstrually related mood disorder (MRMD), which includes premenstrual dysphoric disorder (PMDD) and subthreshold PMDD, is marked by severe psychiatric impairment in the late luteal phase of the menstrual cycle, but little is known about the mechanisms responsible. Allopregnanolone is a neuroactive metabolite of progesterone and a potent GABAA receptor allosteric activator with antidepressant and anxiolytic properties. We have shown that allopregnanolone levels increase, while the allopregnanolone/progesterone ratio decreases, from the follicular to luteal phase in healthy women. We hypothesized that allopregnanolone levels would decrease in association with the increase in depression severity experienced in the late luteal phase by women with MRMD. We studied 23 women with regular menses [MRMD (n=9) and healthy controls with no premenstrual symptoms or psychiatric history (HC) (n=14)] in the mid-follicular (cycle day 6-10), mid-luteal (5-9 days after LH surge), and late luteal (9-13 days after LH surge) phases. No subjects took gonadal steroids or psychotropic medications. The Daily Record of Severity of Problems was used to diagnosed PMDD (≥5 symptoms) and subthreshold PMDD (1-4 symptoms). Depression and anxiety symptom severity were assessed using the Quick Inventory of Depressive Symptomatology and Generalized Anxiety Disorder 7-item Scale, respectively. Fasting plasma hormone levels were measured by GC/MS. Data are presented as median(95% CI). Normal ranges were calculated as the 95% CI of HC. Median age [30(28,33) years] and BMI [23.8(22.9,29.0) kg/m2] were similar between groups. Depression severity was greater in MRMD vs HC [7(3,13) vs 2(1,4), p=0.005) in the late luteal phase only, as expected. In the follicular phase, the median allopregnanolone level was higher in MRMD vs HC [86(40,148) vs 29(24,73) pg/mL, p=0.05] and frankly elevated in 6 of 9 (67%) MRMD women. The median allopregnanolone/progesterone ratio in the follicular phase was higher in MRMD vs HC [0.8(0.4,2.2) vs 0.4 (0.3,0.8), p=0.03] and elevated in 4 of 9 (44%) MRMD women. There were no differences in neuroactive steroid levels between groups during the luteal phase. Higher allopregnanolone levels in the follicular phase were associated with greater depression severity in the mid-luteal (r=0.51, p=0.01) and late luteal (r=0.54, p=0.007) phase and greater anxiety severity in the late luteal phase (r=0.41, p=0.05). Conclusion: Contrary to our hypothesis, we found that levels of neuroactive steroids, which have antidepressant effects, were higher in the follicular phase in women with MRMD – who experience depression in the late luteal phase – compared with HC. This suggests that increased conversion of progesterone to allopregnanolone in the follicular phase, resulting in elevated allopregnanolone levels, may be a compensatory response to premenstrual depression and anxiety in some women with MRMD. Presentation Date: Friday, June 16, 2023

Identification of methylation-regulated genes modulating microglial phagocytosis in hyperhomocysteinemia-exacerbated Alzheimer’s disease

BackgroundHyperhomocysteinemia (HHcy) has been linked to development of Alzheimer’s disease (AD) neuropathologically characterized by the accumulation of amyloid β (Aβ). Microglia (MG) play a crucial role in uptake of Aβ fibrils, and its dysfunction worsens AD. However, the effect of HHcy on MG Aβ phagocytosis remains unstudied.MethodsWe isolated MG from the cerebrum of HHcy mice with genetic cystathionine-β-synthase deficiency (Cbs−/−) and performed bulk RNA-seq. We performed meta-analysis over transcriptomes of Cbs−/− mouse MG, human and mouse AD MG, MG Aβ phagocytosis model, human AD methylome, and GWAS AD genes.ResultsHHcy and hypomethylation conditions were identified in Cbs−/− mice. Through Cbs−/− MG transcriptome analysis, 353 MG DEGs were identified. Phagosome formation and integrin signaling pathways were found suppressed in Cbs−/− MG. By analyzing MG transcriptomes from 4 AD patient and 7 mouse AD datasets, 409 human and 777 mouse AD MG DEGs were identified, of which 37 were found common in both species. Through further combinatory analysis with transcriptome from MG Aβ phagocytosis model, we identified 130 functional-validated Aβ phagocytic AD MG DEGs (20 in human AD, 110 in mouse AD), which reflected a compensatory activation of Aβ phagocytosis. Interestingly, we identified 14 human Aβ phagocytic AD MG DEGs which represented impaired MG Aβ phagocytosis in human AD. Finally, through a cascade of meta-analysis of transcriptome of AD MG, functional phagocytosis, HHcy MG, and human AD brain methylome dataset, we identified 5 HHcy-suppressed phagocytic AD MG DEGs (Flt1, Calponin 3, Igf1, Cacna2d4, and Celsr) which were reported to regulate MG/MΦ migration and Aβ phagocytosis.ConclusionsWe established molecular signatures for a compensatory response of Aβ phagocytosis activation in human and mouse AD MG and impaired Aβ phagocytosis in human AD MG. Our discoveries suggested that hypomethylation may modulate HHcy-suppressed MG Aβ phagocytosis in AD.

Voice quality alteration and its potential implications for voice therapy

Modulating a speaker’s auditory feedback is a valuable technique for investigating vocal motor control. In auditory feedback alteration (AFA) experiments, participants receive real-time perturbed feedback of their voice through earphones while producing vocalizations into a microphone. Previous studies primarily focused on pitch and amplitude alterations, which typically result in compensatory vocal responses. The purpose of this study is to present a voice resynthesis system, called VQ-Synth, designed for real-time auditory feedback alteration of the speaker’s voice quality in terms of hoarseness. While an initial version of VQ-Synth was implemented using Matlab, the system has now been enhanced in a real-time framework written in ANSI-C to achieve effective voice quality resynthesis with minimal delay. Additionally, a graphical user interface (GUI) was implemented to guide participants through the experiment. This work presents the technical architecture of VQ-Synth and its intended application in AFA experiments involving both healthy and dysphonic speakers. Furthermore, we discuss the potential implications of the system in the context of auditory cognition and voice therapy. We hope that the novel capabilities of VQ-Synth open up exciting possibilities for investigating how alterations in voice quality affect vocal motor control and how this knowledge can be applied in therapeutic settings.

Lipid Profile of the Muscle Tissue of Some Mesopelagic Fish Species of the Families Stomiidae and Myctophidae from Different Depths of the Irminger Sea, North Atlantic

For the first time the qualitative and quantitative lipid profile (total lipids and polar and nonpolar lipids) of the muscle tissue of six mesopelagic fish species, which are representatives of two deep-sea families widespread in the World Ocean: Stomiidae and Myctophidae were studied. It was found the species specificity of lipid accumulation for the studied fishes, which indicates differences in the mechanisms of compensatory responses. Triacylglycerols are the main form of lipid storage in the studied species. However, an accumulation of cholesterol esters and waxes (lipid characteristic of vertical migrants) has also been recorded in Borostomias antarcticus. The revealed distinctive features of Myctophidae and Stomiatidae, related to the accumulation of cholesterol and variations in the content of different phospholipid fractions, indicate that the fishes of these families use different mechanisms for regulating and maintaining the physicochemical state (permeability and fluidity) of biological membranes under conditions of change in a set of environmental factors (temperature, salinity, hydrostatic pressure, and specific photoperiod) with increase in the habitat depth.