Somatic Growth Research Articles

Development of external genitalia during mini-puberty: Is it related to somatic growth or pubertal hormones?

Although hypothalamic-pituitary-gonadal axis activation and hormone levels in mini-puberty are similar to the pubertal period1, its role in human development and reproduction has not been fully elucidated2. We aimed to evaluate the effects of somatic growth and reproductive hormones on the development of external genitalia during mini-puberty

Loss of function in somatostatin receptor 5 has no impact on the growth of medaka fish due to compensation by the other paralogs

Somatic growth in vertebrates is regulated endocrinologically by the somatotropic axis, headed by the growth hormone (GH) and the insulin growth factor-I (IGF-I). Somatostatin (Sst), a peptide hormone synthesized in the hypothalamus, modulates GH actions through its receptors (Sstr). Four Sstr subtypes (Sstr 1–3 and 5) have been identified in teleosts. However, little is known about whether they have a specific function or tissue expression. The aim of this study was to determine the role of sstr2 and sstr5 in the growth of the medaka (Oryzias latipes). The assessed expression pattern across diverse tissues highlighted greater prevalence of sstr1 and sstr3 in brain, intestine and muscle than in pituitary or liver. The expression of sstr2 was high in all the tissues tested, while sstr5 was predominantly expressed in the pituitary gland. A CRISPR/Cas9 sstr5 mutant with loss of function (sstr5-/-) was produced. Assessment of sstr5-/- indicated no significant difference with the wild type regarding growth parameters such as standard length, body depth, or peduncle depth. Furthermore, the functional loss of sstr5 had no impact on the response to a nutritional challenge. The fact that several sstr subtypes were upregulated in different tissues in sstr5-/- medaka suggests that in the mutant fish, there may be a compensatory effect on the different tissues, predominantly by sstr1 in the liver, brain and pituitary, with sstr2 being upregulated in pituitary and liver, and sstr3 only presenting differential expression in the brain. Analysis of the sstr subtype and the sstr5-/- fish showed that sstr5 was not the only somatostatin receptor responsible for Sst-mediated Gh regulation.

Food quality shapes gradual phenotypic plasticity in ectotherms facing temperature variability.

Organisms exhibit reversible physiological adjustments as a response to rapidly changing environments. Yet such plasticity of the phenotype is gradual and may lag behind environmental fluctuations, thereby affecting long-term average performance of the organisms. By supplying energy and essential compounds for optimal tissue building, food determines the range of possible phenotypic changes and potentially the rate at which they occur. Here, we assess how differences in the dietary supply of essential lipids modulate the phenotypic plasticity of an ectotherm facing thermal fluctuations. We use three phytoplankton strains to create a gradient of polyunsaturated fatty acid and sterol supply for Daphnia magna under constant and fluctuating temperatures. We used three different fluctuation periodicities to unravel the temporal dynamics of gradual plasticity and its long-term consequences for D. magna performance measured as juvenile somatic growth rate. In agreement with gradual plasticity theory, we show that in D. magna, fluctuation periodicity determines the differential between observed growth rates and those expected from constant conditions. Most importantly, we show that diet modulates both the size and the direction of the growth rate differential. Overall, we demonstrate that the nutritional context is essential for predicting ectotherm consumers' performance in fluctuating thermal environments.

Identification of Insulin-like Growth Factor (IGF) Family Genes in the Golden Pompano, Trachinotus ovatus: Molecular Cloning, Characterization and Gene Expression.

Insulin-like growth factors (IGFs) are hormones that primarily stimulate and regulate animal physiological processes. In this study, we cloned and identified the open reading frame (ORF) cDNA sequences of IGF family genes: the insulin-like growth factor 1 (IGF1), insulin-like growth factor 2 (IGF2), and insulin-like growth factor 3 (IGF3). We found that IGF1, IGF2, and IGF3 have a total length of 558, 648, and 585 base pairs (bp), which encoded a predicted protein with 185, 215, and 194 amino acids (aa), respectively. Multiple sequences and phylogenetic tree analysis showed that the mature golden pompano IGFs had been conserved and showed high similarities with other teleosts. The tissue distribution experiment showed that IGF1 and IGF2 mRNA levels were highly expressed in the liver of female and male fish. In contrast, IGF3 was highly expressed in the gonads and livers of male and female fish, suggesting a high influence on fish reproduction. The effect of fasting showed that IGF1 and mRNA expression had no significant difference in the liver but significantly decreased after long-term (7 days) fasting in the muscles and started to recover after refeeding. IGF2 mRNA expression showed no significant difference in the liver but had a significant difference in muscles for short-term (2 days) and long-term fasting, which started to recover after refeeding, suggesting muscles are more susceptible to both short-term and long-term fasting. In vitro incubation of 17β-estradiol (E2) was observed to decrease the IGF1 and IGF3 mRNA expression level in a dose- (0.1, 1, and 10 μM) and time- (3, 6, and 12 h) dependent manner. In addition, E2 had no effect on IGF2 mRNA expression levels in a time- and dose-dependent manner. The effect of 17α-methyltestosterone (MT) in vitro incubation was observed to significantly increase the IGF3 mRNA expression level in a time- and dose-dependent manner. MT had no effect on IGF2 mRNA but was observed to decrease the IGF1 mRNA expression in the liver. Taken together, these data indicate that E2 and MT may either increase or decrease IGF expression in fish; this study provides basic knowledge and understanding of the expression and regulation of IGF family genes in relation to the nutritional status, somatic growth, and reproductive endocrinology of golden pompano for aquaculture development.

Height best predicts the optimal insertion length of orotracheal tubes in children

IntroductionAccurate formulae to predict the optimal insertion length of endotracheal tubes (ETT) are necessary for safe care and have been based on height, weight, age, and ETT size. We believe height best reflects the somatic growth of the trachea. Our goal is to compare a formula generated using height for optimal initial insertion length of ETT to previously published formulae based on height, weight, age, and ETT size.MethodsWe retrospectively reviewed chest radiographs over a two-year period where the head was assured in midline and midposition. We excluded children with conditions altering tracheal dimensions or stature, and scoliosis. We chose 2 cm above the carina to be the optimal insertion length of the ETT which was then correlated to height. We created linear regression equations and Bland-Altman plots.ResultsTwo hundred three orotracheally intubated children were included. The optimal ETT insertion length using the formula Height (cm)/8 + 3.4 had a high association with linear regression and Bland-Altman plots had the narrowest 95% limits of agreement as compared to previously published formulae.ConclusionsWe found optimal insertion length = Height (cm)/8 + 3.4 is more accurate as compared to commonly used formulae that are based on weight, age, or ETT size. This formula places the ETT 2 cm above the carina which should be safe until a chest radiograph is obtained. We find that the use of formulae that divide the height by 10 overestimates the depth of insertion in younger, smaller children and underestimates the depth of insertion in older children.

Storage cell proliferation during somatic growth establishes that tardigrades are not eutelic organisms.

Tardigrades, microscopic ecdysozoans known for extreme environment resilience, were traditionally believed to maintain a constant cell number after completing embryonic development, a phenomenon termed eutely. However, sporadic reports of dividing cells have raised questions about this assumption. In this study, we explored tardigrade post-embryonic cell proliferation using the model species Hypsibius exemplaris. Comparing hatchlings to adults, we observed an increase in the number of storage cells, responsible for nutrient storage. We monitored cell proliferation via 5-ethynyl-2'-deoxyuridine (EdU) incorporation, revealing large numbers of EdU+ storage cells during growth, which starvation halted. EdU incorporation associated with molting, a vital post-embryonic development process involving cuticle renewal for further growth. Notably, DNA replication inhibition strongly reduced EdU+ cell numbers and caused molting-related fatalities. Our study is the first to demonstrate using molecular approaches that storage cells actively proliferate during tardigrade post-embryonic development, providing a comprehensive insight into replication events throughout their somatic growth. Additionally, our data underscore the significance of proper DNA replication in tardigrade molting and survival. This work definitely establishes that tardigrades are not eutelic, and offers insights into cell cycle regulation, replication stress, and DNA damage management in these remarkable creatures as genetic manipulation techniques emerge within the field.

AI-based pipeline for early screening of lung cancer: integrating radiology, clinical, and genomics data

The prognosis of lung carcinoma has changed since the discovery of molecular targets and their specific drugs. Somatic Epidermal Growth Factor Receptor (EGFR) mutations have been reported in lung carcinoma, and these mutant proteins act as substrates for targeted therapies. However, in a resource-constrained country like India, panel-based next-generation sequencing cannot be made available to the population at large. Additional challenges such as adequacy of tissue in case of lung core biopsies and locating suitable tumour tissues as a result of innate intratumoral heterogeneity indicate the necessity of an AI-based end-to-end pipeline capable of automatically detecting and learning more effective lung nodule features from CT images and predicting the probability of the EGFR-mutant. This will help the oncologists and patients in resource-limited settings to achieve near-optimal care and appropriate therapy. The EGFR gene sequencing and CT imaging data of 2277 patients with lung carcinoma were included from three cohorts in India and a White population cohort collected from TCIA. Another cohort LIDC-IDRI was used to train the AIPS-Nodule (AIPS-N) model for automatic detection and characterisation of lung nodules. We explored the value of combining the results of the AIPS-N with the clinical factors in the AIPS-Mutation (AIPS-M) model for predicting EGFR genotype, and it was evaluated by area under the curve (AUC). AIPS-N achieved an average AP50 of 70.19% in detecting the location of nodules within the lung region of interest during validation and predicted the score of five lung nodule properties. The AIPS-M machine learning (ML) and deep learning (DL) models achieved AUCs ranging from 0.587 to 0.910. The AIPS suggests that CT imaging combined with a fully automated lung-nodule analysis AI system can predict EGFR genotype and identify patients with an EGFR mutation in a cost-effective and non-invasive manner. This work was supported by a grant provided by Conquer Cancer Foundation of ASCO [2021IIG-5555960128] and Pfizer Products India Pvt. Ltd.

Daily age, growth rate, and pelagic larval duration of commercially important snapper species in Abrolhos National Marine Park.

The age and daily growth of fish are registered through the deposition of increments in their otoliths, which are concretions formed by the precipitation of substances present in the endolymphatic fluid, mainly calcium carbonate (CaCO3). Faced with the need to fill some of the gaps in the knowledge on the occurrence and duration of the initial stages of snapper species' life cycles in the Abrolhos Bank, this study aimed to describe the growth rates, age, and period of pelagic larval duration (PLD) of three snapper species during the larval pre-settlement phase, in the Abrolhos Bank region. The post-larvae were captured using light traps. Otoliths were removed from 117 samples of snapper species; however, only 69 were viable for age estimation, of which 15 were Lutjanus analis, 25 were Lutjanus jocu, and 29 were Lutjanus synagris. Together, the samples presented individuals with total lengths ranging from 16.14 to 24.76 mm and ages from 21 to 39 days. Settlement marks were found for all three species, and the average PLD was ~25 days. The somatic growth of the snapper species was positively correlated with otolith growth. L. jocu presented the greatest daily growth compared to the other species. The three species use the Abrolhos Bank as a larval settlement site, demonstrating plasticity by using different habitats throughout their lives.

Early-Life Fecal Transplantation from High Muscle Yield Rainbow Trout to Low Muscle Yield Recipients Accelerates Somatic Growth through Respiratory and Mitochondrial Efficiency Modulation.

Previous studies conducted in our lab revealed microbial assemblages to vary significantly between high (ARS-FY-H) and low fillet yield (ARS-FY-L) genetic lines in adult rainbow trout. We hypothesized that a high ARS-FY-H donor microbiome can accelerate somatic growth in microbiome-depleted rainbow trout larvae of the ARS-FY-L line. Germ-depleted larvae of low ARS-FY-L line trout reared in sterile environments were exposed to high- or low-fillet yield-derived microbiomes starting at first feeding for 27 weeks. Despite weight-normalized diets, somatic mass was significantly increased in larvae receiving high fillet yield microbiome cocktails at 27 weeks post-hatch. RNA-seq from fish tails reveals enrichment in NADH dehydrogenase activity, oxygen carrier, hemoglobin complex, gas transport, and respiratory pathways in high fillet yield recolonized larvae. Transcriptome interrogation suggests a relationship between electron transport chain inputs and body weight assimilation, mediated by the gut microbiome. These findings suggest that microbiome payload originating from high fillet yield adult donors primarily accelerates juvenile somatic mass assimilation through respiratory and mitochondrial input modulation. Further microbiome studies are warranted to assess how increasing beneficial microbial taxa could be a basis for formulating appropriate pre-, pro-, or post-biotics in the form of feed additives and lead to fecal transplantation protocols for accelerated feed conversion and fillet yield in aquaculture.

A case study of congenital adrenal hyperplasia

Congenital adrenal hyperplasia (CAH) is a rare condition with a variety of symptoms. The most serious “salt losing” scenario is a medical emergency. A lack of 21 a-hydroxylase causes more than 90% of cases of CAH (21aOH). The adrenals produce excess sex hormones rather than cortisol. The vast majority of patients are unable to produce enough aldosterone. Girls are virilized, there is rapid somatic growth with the early epiphyseal fusion in both sexes, and there is even life-threatening hyponatremic dehydration. The following case report evaluates the clinical features, signs, and symptoms of CAH. A 1-day-old baby was admitted to the Neonatal Intensive Care Unit at the Department of Pediatrics, New Civil Hospital, Surat, for ambiguous genitalia. Various studies were conducted, and karyotyping suggestive of 46xx 17OH progesterone decreased. The sodium level was 114.64 mmol and the potassium level was 4.81 mmol on electrolyte analysis. CAH is an autosomal recessive disorder, in which 21-hydroxylase deficiency is the most common cause. In children, hydrocortisone is the preferred treatment.

Temperature and hypoxia‐driven shifts in Daphnia interspecific competition

AbstractPrevious research has shown that elevated temperature and environmental hypoxia are associated with a reduced representation of larger‐bodied species in communities of ectotherms, suggesting their competitive disadvantage resulting from increased oxygen demands and limited oxygen availability. To investigate this, we conducted a comparative analysis of two pairs of competing zooplankton species: Daphnia galeata (smaller‐bodied) and Daphnia pulex (larger‐bodied), as well as D. pulex (smaller‐bodied) and Daphnia magna (larger‐bodied). We monitored their population dynamics under different oxygen concentrations and temperatures, and additionally measured hemoglobin concentration in the latter pair. Contrary to expectations, the results demonstrated that the larger‐bodied species outcompeted the smaller‐bodied ones in all experimental treatments involving the first pair of species. In the second pair, elevated temperature favored the smaller‐bodied species, while environmental hypoxia had the opposite effect. The competitive advantage of D. pulex under elevated temperature likely stemmed from their ability to allocate energy from somatic growth to reproduction, as indicated by the increased number of reproducing females. Conversely, the competitive advantage of D. magna under environmental hypoxia may be attributed to their ability to reallocate energy from reproduction to somatic growth, as indicated by lower reproductive effort and greater plasticity in hemoglobin production. These findings indicate that elevated temperature and hypoxia can independently and jointly influence interspecific competitive abilities by impacting the pace of life. However, the numerical dominance of smaller‐sized species in warm and hypoxic zooplankton communities cannot be explained by their enhanced competitive abilities resulting from a more favorable oxygen supply demand balance.

Automatic detection of fish scale circuli using deep learning.

Teleost fish scales form distinct growth rings deposited in proportion to somatic growth in length, and are routinely used in fish ageing and growth analyses. Extraction of incremental growth data from scales is labour intensive. We present a fully automated method to retrieve this data from fish scale images using Convolutional Neural Networks (CNNs). Our pipeline of two CNNs automatically detects the centre of the scale and individual growth rings (circuli) along multiple radial transect emanating from the centre. The focus detector was trained on 725 scale images and achieved an average precision of 99%; the circuli detector was trained on 40678 circuli annotations and achieved an average precision of 95.1%. Circuli detections were made with less confidence in the freshwater zone of the scale image where the growth bands are most narrowly spaced. However, the performance of the circuli detector was similar to that of another human labeller, highlighting the inherent ambiguity of the labelling process. The system predicts the location of scale growth rings rapidly and with high accuracy, enabling the calculation of spacings and thereby growth inferences from salmon scales. The success of our method suggests its potential for expansion to other species.

Prediction of deciduous teeth eruption in Brazilian children: A cross-sectional study nested in a prospective birth cohort (BRISA)

BackgroundDental eruption is part of a set of children´s somatic growth phenomena. The worldwide accepted human dental eruption chronology is still based on a small sample of European children. However, evidence points to some population variations with the eruption at least two months later in low-income countries, and local standards may be useful. So, this study aimed to predict deciduous teeth eruption from 12 months of age in a Brazilian infant population.MethodsWe developed a cross-sectional study nested in four prospective cohorts – the Brazilian Ribeirão Preto and São Luís Cohort Study (BRISA) – in a sample of 3,733 children aged 12 to 36 months old, corrected by gestational age. We made a reference curve with the number of teeth erupted by age using the Generalized Additive Models for location, scale, and shape (GAMLSS) technique. The explanatory variable was the corrected children´s age. The dependent variable was the number of erupted teeth, by gender, evaluated according to some different outcome distributional forms. The generalized Akaike information criterion (GAIC) and the model residuals were used as the model selection criterion.ResultsThe Box-Cox Power Exponential method was the GAMLSS model with better-fit indexes. Our estimation curve was able to predict the number of erupted deciduous teeth by age, similar to the real values, in addition to describing the evolution of children’s development, with comparative patterns. There was no difference in the mean number of erupted teeth between the sexes. According to the reference curve, at 12 months old, 25% of children had four erupted teeth or less, while 75% had seven or fewer and 95% had 11 or fewer. At 24 months old, 5% had less than 12, and 75% had 18 or more. At 36 months old, around 50% of the population had deciduous dentition completed (20 teeth).ConclusionThe adjusted age was an important predictor of the number of erupted deciduous teeth. This outcome can be a variable incorporated into children’s growth and development curves, such as weight and height curves for age to help dentists and physicians in the monitoring the children’s health.

Exploring Growth, Maturity, and Age as Injury Risk Factors in High-Level Youth Football.

Rapid somatic growth and biological maturity status may affect injury patterns in youth football, yet firm conclusions cannot be drawn from the existing research. We aimed to explore growth velocity, maturity, and age as injury risk factors in 95 academy players (11.9-15.0 years), using anthropometric (height and body mass), maturity (skeletal age), injury, and football exposure data collected prospectively over three seasons (2016/17-2018/19). We compared the relative quality of mixed-effects logistic regression models with growth velocity for 223 growth intervals (average 113 days) included as fixed effects and adjusted for age (chronological or skeletal) plus load (hours/week). Associations were considered practically relevant based on the confidence interval for odds ratios, using thresholds of 0.90 and 1.11 to define small beneficial and harmful effects, respectively. We observed harmful effects of older age on overall (OR: 2.61, 95% CI: 1.15-5.91) and sudden onset (1.98, 1.17-3.37) injury risk. Significant associations (p<0.05) were observed for higher body mass change and greater maturity on sudden onset injuries, and for higher hours/week on gradual onset, bone tissue, and physis injuries. Future studies should include larger samples, monitoring athletes from pre-adolescence through maturation, to enable within-subject analyses and better understand the relationship between growth, maturation, and injuries.

Antidepressants – The new endocrine disruptors? The case of crustaceans

Antidepressants are high-volume pharmaceuticals that accumulate to concentrations in the μg·L−1 range in surface waters. The release of peptide hormones via neurosecretory cells appears as a natural target for antidepressants. Here I review research that suggests that antidepressants indeed disrupt endocrine signalling in crustaceans, by acting on the synthesis and release of neurohormones, such as crustacean hyperglycaemic hormone, moult inhibiting hormone and pigment dispersing hormone in decapods, as well as methyl farnesoate in Daphnids. Hence, antidepressants can affect hormonal regulation of physiological functions: increase in energy metabolism and activity, lowered ecdysteroid levels, potentially disrupting moult and somatic growth, reducing colour change capacity and compromising camouflage, as well as induction of male sex determination. Several studies further suggest effects of antidepressants on crustacean reproduction, but the hormonal regulation of these effects remains elusive. All things considered, a body of evidence strongly suggests that antidepressants are endocrine disrupting compounds in crustaceans.

Behavioral mechanisms underlying trait-mediated survival in a coral reef fish

Fast growth and large size generally increase survivorship in organisms with indeterminate growth. These traits frequently covary, but where they do not, trade-offs often exist in the behavioral choices of organisms. Juvenile bicolor damselfish Stegastes partitus that settle on coral reefs at larger sizes generally experience enhanced survivorship but have slower juvenile growth rates. We hypothesized that differences in behavior may mediate this trade-off. To test whether it is trait-related behaviors or the traits themselves that enhance early survival, we combined individual behavioral observations with otolith (ear stone)-based daily growth measurements for juvenile S. partitus in the Florida Keys. Foraging, sheltering, and chasing behaviors of 256 fish were measured during 5 different months (2008–2009), and patterns of differential survival were similar to those from a 6-year (2003–2008) recruitment time series. We found a trade-off between sheltering and foraging that significantly explained patterns in size-at-settlement: damselfish that settled at larger sizes spent less time sheltered and more time feeding high in the water column. Juvenile growth rates were unrelated to any of the sheltering–foraging behaviors but instead were inversely related to adult conspecific density. Damselfish that settled near higher densities of conspecifics were subjected to increased territorial chasing. Chasing intensity interacted with settlement size such that large juveniles who were chased more frequently exhibited slower growth rates, whereas smaller settlers did not experience this energetic cost. Thus, the dominant survival strategy of S. partitus is to settle at a large size and spend more time foraging high in the water column while dodging conspecifics at an energetic cost to their growth rates. Size-at-settlement is determined during the larval period and after settlement, this trait is key to subsequent behaviors and the strength of trait-mediated survival. Understanding how somatic growth, body size, and survival are intertwined in early life is necessary to help explain population dynamics.

Ingestion Rate, Prey Selectivity, and Growth of Larval Vieja zonata (Teleostei: Cichlidae) Co‐Fed Rotifers with Cladocerans

The study of fish larval nutrition is important as dietary requirements change significantly with growth. Vieja zonata is a cichlid species that is endemic to Mexico. In this study, we investigated the ingestion rate, prey selectivity, and growth of V. zonata larvae that were fed on prey cultured with and without probiotics. We conducted three experiments to test the acceptability of the prey offered, determine the optimal density of the prey items, and observe the effect of probiotics on the larvae’s growth. The first experiment tested the acceptability of the prey offered to 5 days post‐hatched (dph) V. zonata larvae, and the second experiment determined the optimal density of the prey items. In the third experiment, we individually placed 5 dph larvae (SL = 5.97 ± 0.13 mm; 8.5 ± 0.25 mg) and fed them for 10 days with three different prey items: two rotifer species (Brachionus angularis and Plationus patulus at a density of 20 ind/mL) and a cladoceran species (Moina cf. macrocopa at 1 ind/mL), both cultures with and without probiotics. We counted the prey items consumed daily and provided fresh media with new prey at the above density. We determined the total counts, ingestion rates, and Manly’s selectivity index (αi) and measured and weighed the larvae at the beginning and end of the experiment. The endogenous feeding period with the yolk sac lasted until 5 dph, a mixed period with endogenous and exogenous feeding occurred from 5 to 7 dph, and an exogenous feeding period in which they fed on zooplankton was observed from day 7 to 15 dph. Brachionus angularis and Plationus patulus were accepted as prey after 5 dph, and Moina cf. macrocopa was accepted on 11 dph. During the first days of feeding, the preferred prey item was P. patulus, which later switched to M. cf. macrocopa on day 11. We found that the use of prey produced with NanoCrusta probiotics resulted in a significant increase in the somatic growth and weight of V. zonata. Our findings suggest that probiotics may potentially enhance the nutritional value of prey items and promote the growth of V. zonata larvae.

Tissue explants as tools for studying the epigenetic modulation of the GH-IGF-I axis in farmed fish.

Somatic growth in vertebrates is mainly controlled by the growth hormone (GH)/insulin-like growth factor I (IGF-I) axis. The role of epigenetic mechanisms in regulating this axis in fish is far from being understood. This work aimed to optimize and evaluate the use of short-term culture of pituitary and liver explants from a farmed fish, the gilthead seabream Sparus aurata, for studying epigenetic mechanisms involved in GH/IGF-I axis regulation. Our results on viability, structure, proliferation, and functionality of explants support their use in short-term assays. Pituitary explants showed no variation in gh expression after exposure to the DNA methylation inhibitor decitabine (5-Aza-2'-deoxycytidine; DAC), despite responding to DAC by changing dnmt3bb and tet1 expression, and TET activity, producing an increase in overall DNA hydroxymethylation. Conversely, in liver explants, DAC had no effects on dnmt s and tet s expression or activity, but modified the expression of genes from the GH-IGF-I axis. In particular, the expression of igfbp2a was increased and that of igfbp4, ghri and ghrii was decreased by DAC as well as by genistein, which is suggestive of impaired growth. While incubation of liver explants with S-adenosylmethionine (SAM) produced no clear effects, it is proposed that nutrients must ensure the methylation milieu within the liver in the fish to sustain proper growth, which need further in vivo verification. Pituitary and liver explants from S. aurata can be further used as described herein for the screening of inhibitors or activators of epigenetic regulators, as well as for assessing epigenetic mechanisms behind GH-IGF-I variation in farmed fish.

Embryonic temperature has long-term effects on muscle circRNA expression and somatic growth in Nile tilapia.

Embryonic temperature has a lasting impact on muscle phenotype in vertebrates, involving complex molecular mechanisms that encompass both protein-coding and non-coding genes. Circular RNAs (circRNAs) are a class of regulatory RNAs that play important roles in various biological processes, but the effect of variable thermal conditions on the circRNA transcriptome and its long-term impact on muscle growth plasticity remains largely unexplored. To fill this knowledge gap, we performed a transcriptomic analysis of circRNAs in fast muscle of Nile tilapia (Oreochromis niloticus) subjected to different embryonic temperatures (24°C, 28°C and 32°C) and then reared at a common temperature (28°C) for 4months. Nile tilapia embryos exhibited faster development and subsequently higher long-term growth at 32°C compared to those reared at 28°C and 24°C. Next-generation sequencing data revealed a total of 5,141 unique circRNAs across all temperature groups, of which 1,604, 1,531, and 1,169 circRNAs were exclusively found in the 24°C, 28°C and 32°C groups, respectively. Among them, circNexn exhibited a 1.7-fold (log2) upregulation in the 24°C group and a 1.3-fold (log2) upregulation in the 32°C group when compared to the 28°C group. Conversely, circTTN and circTTN_b were downregulated in the 24°C groups compared to their 28°C and 32°C counterparts. Furthermore, these differentially expressed circRNAs were found to have multiple interactions with myomiRs, highlighting their potential as promising candidates for further investigation in the context of muscle growth plasticity. Taken together, our findings provide new insights into the molecular mechanisms that may underlie muscle growth plasticity in response to thermal variation in fish, with important implications in the context of climate change, fisheries and aquaculture.

Early Life Interventions: Impact on Aging and Longevity.

Across mammals, lifespans vary remarkably, spanning over a hundredfold difference. Comparative studies consistently reveal a strong inverse relationship between developmental pace and lifespan, hinting at the potential for early-life interventions (ELIs) to influence aging and lifespan trajectories. Focusing on postnatal interventions in mice, this review explores how ELIs influence development, lifespan, and the underlying mechanisms. Previous ELI studies have employed a diverse array of approaches, including dietary modifications, manipulations of the somatotropic axis, and various chemical treatments. Notably, these interventions have demonstrated significant impacts on aging and lifespan in mice. The underlying mechanisms likely involve pathways related to mitochondrial function, mTOR and AMPK signaling, cellular senescence, and epigenetic alterations. Interestingly, ELI studies may serve as valuable models for investigating the complex regulatory mechanisms of development and aging, particularly regarding the interplay among somatic growth, sexual maturation, and lifespan. In addition, prior research has highlighted the intricacies of experimental design and data interpretation. Factors such as timing, sex-specific effects, administration methods, and animal husbandry practices must be carefully considered to ensure the reliability and reproducibility of results, as well as rigorous interpretation. Addressing these factors is essential for advancing our understanding of how development, aging, and lifespan are regulated, potentially opening avenues for interventions that promote healthy aging.