Timing Of Sexual Maturation Research Articles

Acrylamide exposure, sex hormones, and pubertal status in Japanese adolescents

ABSTRACT Acrylamide may affect sex hormone levels and the timing of sexual maturation. The present study cross-sectionally examined interrelationship between the urinary metabolite of acrylamide exposure, serum sex hormone levels, and pubertal status in 408 Japanese adolescents aged 13–14 years. Their caregivers completed a questionnaire concerning the health status of their children, including pubertal maturation, and the lifestyles of children and parents. Pubertal status was queried by the Pubertal Development Scale. A major metabolite of acrylamide, N-acetyl-S-(2-carbamoylethyl)-cysteine (AAMA) in first-void urine samples. In male students, urinary AAMA was significantly inversely associated with testosterone, puberty stage, and facial hair growth after controlling for covariates. Serum testosterone and DHEAS were significantly positively associated with puberty stage. In female students, urinary AAMA was not associated with puberty stage, the indices, or any measured hormones. The data suggest that exposure to acrylamide may impact the pubertal development of boys through the effects on testosterone level.

Effect of long-term temperature-controlled rearing on growth traits and sexual maturity of common carp (Cyprinus carpio)

Many economically important fish have a long sexual maturation cycle, with the first sexual maturation time exceeding four years, which poses a long-term challenge for the cultivation of excellent varieties of these fish. Gonadal development and reproductive timing of fish are closely related to changes in environmental temperature. This study used the common carp as an economic fish model and set up three aquaculture modes for a one-month old common carp population: constant temperature test group (CTTG), normal temperature control group (NTCG), and variable temperature control group (VTCG). A long-term (approximately 11 months), temperature-controlled aquaculture experiment was conducted. The results of growth traits and gonadal development tests showed that at 10 months, the body length and weight of the CTTG were significantly higher than those of the other two groups. At seven months, the gonadosomatic index (GSI) value of CTTG was also significantly higher than that of the other two groups; At 10 months, the serum estradiol (E2) concentration of CTTG was significantly higher than that of the other two groups, while the testosterone (T) levels of VTCG and CTTG were significantly higher than those of NTCG, and only the 11-ketotestosterone (11-KT) concentration of VTCG was significantly higher than that of the other two groups. Simultaneously, qPCR analysis of sex hormone regulatory genes revealed that the expression of Cyp19a1a in CTTG ovaries was significantly higher than that in NTCG and VTCG ovaries, whereas the expression of Cyp11b and Hsd11b2 in VTCG ovaries was significantly higher than that in NTCG and CTTG ovaries. At 12 months, artificial reproduction revealed that only fish from the CTTG (66.67%) successfully laid eggs and fertilized normally. The results indicate that long-term constant temperature cultivation at 28 °C starting from the juvenile stage is not only beneficial for the body growth of common carp, but also promotes their gonadal development. This may be due to the conversion of T into E2 by Cyp19a1a in the common carp, ultimately facilitating the functional development of gonadal tissue under hypothalamus-pituitary-gonadal (HPG) axis regulation, normal egg laying, and fertilization. This study reduced the normal first sexual maturation time of common carp by at least 50% and provides a reference for the rapid cultivation of excellent varieties of other economically important fishes.

Effect of Photostimulation Age on Egg Quality and Hatching Traits in Japanese Quail

The timing of sexual maturity in birds is crucial for reproductive success and is significantly influenced by light exposure. This study aimed to investigate the effect of age at photostimulation on egg quality and hatching traits in quails. A total of 300 quails (75 males and 225 females) were divided into 15 replicates and randomly assigned to one of three treatments (age at photostimulation: 30, 35, and 40 days). The birds were housed in specially designed cages and received 16 hours of light stimulation at the respective ages. Egg quality and hatching traits were evaluated from the 5th to the 12th week of age. Results showed no significant differences in egg weight, shell thickness, or Haugh unit scores among the different ages of light stimulation. Fertile egg production and hatchability were also not significantly affected by the age of photostimulation. However, significant differences were observed in the occurrence of dead embryos and hatchling weights among the different age groups exposed to light stimulation. Birds stimulated at the 35th day had a lower incidence of dead embryos and higher hatchling weights compared to those stimulated at the 30th and 40th days.

Relationship between reproductive indicators and sound structure in broiler breeder roosters

Domestic chickens commonly have two types of calls: loud calls (e.g., crowing) for attracting attention effectively over a long distance, and soft or light calls (e.g., squawking) for communication over a short distance. The emergence of secondary sexual characteristics, such as vocalization at the time of sexual maturation, is due to testicular hormone (i.e., testosterone) secretion. Luteinizing hormone (LH) and follicle-stimulating hormone are gonadotropins. These hormones along with semen parameters are essential reproductive indicators of reproductive health and performance of broiler breeder roosters. The objective of this study was to investigate the relationship between the reproductive indicators and sound structure for broiler breeder roosters. Seventy Ross 308 broiler breeder roosters at 50 weeks of age were divided into two groups (high or low), based on the performance of two sexual hormones of testosterone and LH and four semen parameters of semen volume, sperm concentration, sperm viability, and sperm total motility. Two types of rooster sounds (crowing and squawking) were recorded separately from the two groups. Acoustic signals were decomposed by wavelet transformation and correlated with the reproductive indicators. The results indicate that certain features (e.g., entropy and standard deviation) of crowing and squawking sounds from the roosters were significantly correlated with the testosterone and LH concentrations (P<0.05). Crowing roosters had significantly lower values of sperm viability (P<0.01) and sperm total motility (P<0.05) compared with non-crowing ones. Therefore, sound signals can be direct and noninvasive indicators of the reproductive performance of individual broiler breeder roosters.

28 Melanocortin 3 Receptor in Neural Circuits Linking Metabolic State with Reproduction and Growth

Abstract Metabolic state must be communicated to the brain to regulate behavior, growth, nutrient partitioning and development to meet energetic demands. While it is clearly evident that reproduction and energy balance are closely intertwined, the neural circuits integrating these two processes are poorly understood. Recent functional data suggests the melanocortin 3 receptor (MC3R) mediates the exchange of information between reproductive and metabolic state. Additionally, females exhibit uniquely aberrant metabolic and reproductive phenotypes after deletion of MC3R. In this work, we aimed to characterize the role of MC3R neural circuits in linking metabolic state with reproduction and growth in females. We found that MC3R is expressed in brain regions known to have a role in the control of reproductive and metabolic state, including the anteroventral periventricular nucleus (AVPV) and arcuate nucleus (ARH). In the ARH of female mice, significant differences in overall levels of Mc3r mRNA were not observed at postnatal day 16 (P16), P28 or P48, nor did the percentage of ARH Kiss1, Esr1, Sst, Pomc or Agrp neurons doubly-labeled for Mc3r appear to change during postnatal development. However, the percentage of ARH Ghrh neurons labeled for Mc3r significantly increased from P16 to P48. Thus, MC3R in the ARH may play a potential role in conveying metabolic signals critical for growth during development. In the AVPV of female mice, overall abundance of Mc3r mRNA was low at P16, but increased significantly by P28, and was further elevated in mature mice (P48). Additionally, the percentage of Kiss1- and Esr1-expressing neurons in the AVPV labeled for Mc3r increased significantly between P16 and P48, suggesting that Mc3r may have an important role in the timing of sexual maturation. In addition to the direct regulatory action of MC3R expressed in KISS1 neurons in the AVPV, the impact of MC3R signaling may also be transmitted transynaptically via direct neural projections from MC3R neurons to KISS1 neurons in the AVPV, or to GnRH neurons in the rostral preoptic area. Clearly labeled MC3R terminals were observed in close apposition to both KISS1 neurons in the AVPV, and GnRH neurons in the rostral medial preoptic area. Although both the GnRH and KISS1 neuronal populations appeared heavily innervated by MC3R neurons, the density of MC3R terminals onto KISS1 neurons appeared to be substantially greater than that onto GnRH neurons, suggesting that inputs to AVPV neurons may be particularly impactful on reproduction. Thus, MC3R may not only regulate the activity of KISS1 neurons in the AVPV directly, but may also function transynaptically as an important neurobiological substrate for coordination of metabolic state with sexual maturation and reproductive function.

Loss of plasticity in maturation timing after ten years of captive spawning in a delta smelt conservation hatchery.

Adaptation to captivity in spawning programs can lead to unintentional consequences, such as domestication that results in reduced fitness in the wild. The timing of sexual maturation has been shown to be a trait under domestication selection in fish hatcheries, which affects a fish's access to mating opportunities and aligning their offspring's development with favorable environmental conditions. Earlier maturing fish may be favored in hatchery settings where managers provide artificially optimal growing conditions, but early maturation may reduce fitness in the wild if, for example, there is a mismatch between timing of reproduction and availability of resources that support recruitment. We investigated patterns of maturation timing in a delta smelt (Hypomesus transpacificus) conservation hatchery by quantifying changes to the median age at maturity since the captive spawning program was initiated in 2008. Over the span of a decade, we observed a small, but significant increase in age at maturity among broodstock by 2.2 weeks. This trait had low heritability and was largely controlled by phenotypic plasticity that was dependent on the time of year fish were born. Fish that were born later in the year matured faster, potentially a carryover from selection favoring synchronous spawning in the wild. However, higher DI (domestication index) fish showed a loss of plasticity, we argue, as a result of hatchery practices that breed individuals past peak periods of female ripeness. Our findings suggest that the hatchery setting has relaxed selection pressures for fish to mature quickly at the end of the year and, consequently, has led to a loss of plasticity in age at maturity. Hatchery fish that are re-introduced in the wild may not be able to align maturation with population peaks if their maturation rates are too slow with reduced plasticity, potentially resulting in lower fitness.

Tilapia, a good model for studying reproductive endocrinology

The Nile tilapia (Oreochromis niloticus), with a system of XX/XY sex determination, is a worldwide farmed fish with a shorter sexual maturation time than that of most cultured fish. Tilapia show a spawning cycle of approximately 14 days and can be artificially propagated in the laboratory all year round to obtain genetically all female (XX) and all male (XY) fry. Its genome sequence has been opened, and a perfect gene editing platform has been established. With a moderate body size, it is convenient for taking enough blood to measure hormone level. In recent years, using tilapia as animal model, we have confirmed that estrogen is crucial for female development because 1) mutation of star2, cyp17a1 or cyp19a1a (encoding aromatase, the key enzyme for estrogen synthesis) results in sex reversal (SR) due to estrogen deficiency in XX tilapia, while mutation of star1, cyp11a1, cyp17a2, cyp19a1b or cyp11c1 affects fertility due to abnormal androgen, cortisol and DHP levels in XY tilapia; 2) when the estrogen receptors (esr2a/esr2b) are mutated, the sex is reversed from female to male, while when the androgen receptors are mutated, the sex cannot be reversed; 3) the differentiated ovary can be transdifferentiated into functional testis by inhibition of estrogen synthesis, and the differentiated testis can be transdifferentiated into ovary by simultaneous addition of exogenous estrogen and androgen synthase inhibitor; 4) loss of male pathway genes amhy, dmrt1, gsdf causes SR with upregulation of cyp19a1a in XY tilapia. Disruption of estrogen synthesis rescues the male to female SR of amhy and gsdf but not dmrt1 mutants; 5) mutation of female pathway genes foxl2 and sf-1 causes SR with downregulation of cyp19a1a in XX tilapia; 6) the germ cell SR of foxl3 mutants fails to be rescued by estrogen treatment, indicating that estrogen determines female germ cell fate through foxl3. This review also summarized the effects of deficiency of other steroid hormones, such as androgen, DHP and cortisol, on fish reproduction. Overall, these studies demonstrate that tilapia is an excellent animal model for studying reproductive endocrinology of fish.

Edukasi Bahaya Napza (Narkotika, Psikotropika, dan Zat Adiktif) bagi Remaja SMA Muhammadiyah Sumbawa

Adolescence is a transitional period between childhood and adulthood, which begins at the time of sexual maturity between the ages of 11 or 12 years to 20 years. The stages of adolescent development have tasks that must be completed. Drug abuse is becoming a problem that is increasingly concerning and a huge concern for all parties, including the academic community, government, and parents. Cases of narcotics abuse among high school youth have entered a critical stage, for this reason it is necessary to take preventive measures in the form of education. The purpose of this community service is to increase and develop youth knowledge about the dangers of drug abuse for health. The planned outcome is to increase the knowledge, understanding and awareness of adolescents about the dangers of drug abuse for adolescents.&#x0D; &#x0D;

Precocious puberty under stressful conditions: new understanding and insights from the lessons learnt from international adoptions and the COVID-19 pandemic.

Neuro-biological variations in the timing of sexual maturation within a species are part of an evolved strategy that depend on internal and external environmental conditions. An increased incidence of central precocious puberty (CPP) has been described in both adopted and "covid-19 pandemic" children. Until recently, it was hypothesised that the triggers for CPP in internationally adopted children were likely to be better nutrition, greater environmental stability, and improved psychological wellbeing. However, following data collected during and after the coronavirus (COVID-19) global pandemic, other possibilities must be considered. In a society with high levels of child wellbeing, the threat to life presented by an unknown and potentially serious disease and the stressful environment created by lockdowns and other public health measures could trigger earlier pubertal maturation as an evolutionary response to favour early reproduction. The main driver for increased rates of precocious and rapidly progressive puberty during the pandemic could have been the environment of "fear and stress" in schools and households. In many children, CPP may have been triggered by the psychological effects of living without normal social contact, using PPE, being near adults concerned about financial and other issues and the fear of getting ill. The features and time of progression of CPP in children during the pandemic are similar to those observed in adopted children. This review considers the mechanisms regulating puberty with a focus on neurobiological and evolutionary mechanisms, and analyses precocious puberty both during the pandemic and in internationally adopted children searching for common yet unconsidered factors in an attempt to identify the factors which may have acted as triggers. In particular, we focus on stress as a potential factor in the early activation of the hypothalamic-pituitary-gonadal axis and its correlation with rapid sexual maturation.

Changes in Sexual Maturity (Puberty): A Narrative Literature Review

The process of sexual maturation, or puberty, is marked by the development of secondary sexual characteristics, rapid body growth, and, ultimately, the ability to reproduce. Various congenital and endocrine disorders can interfere with the timing of sexual maturation, causing delayed puberty or precocious puberty. This literature review aimed to describe puberty and its disorders and influencing factors. The age of puberty is multifactorial, involving genetic and environmental components. Delayed puberty is a physiological (constitutional) delay in which hormonal levels are normal, and the hypothalamic-pituitary-gonadal (HPG) axis is intact, but maturation occurs slowly. Precocious puberty can be partial, complete, or mixed type and can be further categorized into central (GnRH dependent) and peripheral (GnRH dependent). In conclusion, congenital and endocrine disorders can interfere with the timing of sexual maturation, causing delayed puberty or precocious puberty.

Untargeted Metabolomics Revealed Potential Biomarkers of Small Yellow Follicles of Chickens during Sexual Maturation

Sexual maturation provides economically important traits in poultry production. Research on the initiation mechanism of sexual maturity is of great significance for breeding high-yield laying hens. However, the underlying mechanisms are not fully clear. Here, one hundred and fifty Chahua No. 2 laying hens (the CH2 group, which has precocious puberty) and one hundred and fifty Wu Liang Shan black-bone laying hens (the WLS group, a late-maturing chicken breed) with similar weights and ages were randomly selected. ELISA was used to determine the secretion levels of luteinizing hormone (LH), estradiol (E2), and progesterone (P4) in 150-day-old serum and small yellow follicle (SYF) tissues. A histology examination, immunohistochemistry, and quantitative real-time PCR (qPCR) were used to explore the molecular mechanism of how some genes related to oxidative stress affect sexual maturation. The results showed that the secretion levels of LH, E2, and P4 in the CH2 group serum and SYF were higher than those in the WLS group. The results of the real-time PCR of all genes showed that the expression levels of cytochrome P450 family 11 subfamily A member 1, steroidogenic acute regulatory protein, follicle-stimulating hormone receptor, and cytochrome P450 family 19 subfamily A member 1 in the CH2 group were significantly higher than those in the WLS groups (p < 0.001). Untargeted metabolomics combined with multivariate statistical analysis was used to identify biomarkers of SYF tissues in the CH2 and WLS groups. A trajectory analysis of the principal component analysis (PCA) results showed that the samples within the group were clustered and that the samples were dispersed between the CH2 and the WLS groups, indicating that the results of the measured data were reliable and could be used for further research. Further analysis showed that a total of 319 metabolites in small yellow follicles of the CH2 and WLS groups were identified, among which 54 downregulated differential metabolites were identified. These 54 metabolites were found as potential CH2 biomarkers compared with WLS at 150 days, and the different expressions of L-arginine, L-prolinamide, (R)-4-hydroxymandelate, glutathione, and homovanillic acid were more significant. Twenty metabolic pathways were found when significantly differential metabolites were queried in the KEGG database. According to the impact values of the metabolic pathways, eighteen differential metabolites belonged to the mTOR signaling pathway, glutathione metabolism, ABC transporters, the cell ferroptosis pathway, and D-arginine and D-ornithine metabolism. Interestingly, we identified that the cell ferroptosis pathway played an important role in chicken follicle selection for the first time. The histology and immunohistochemistry of SYF showed that the number of granulosa cells increased in the CH2 groups and the expression levels of glutathione peroxidase 4, tumor protein p53, ribosomal protein S6 kinase, and sterol regulatory element binding protein 1 in the granulosa cell layer were upregulated in the CH2 group at the time of sexual maturation. Furthermore, we also speculated that the antioxidant system may play an indispensable role in regulating sexual maturity in chickens. Overall, our findings suggest differentially expressed metabolites and metabolic pathways between CH2 and WLS chickens, providing new insights into the initiation mechanism of sexual maturation.

Обзор данных по биологии нельмы Stenodus leucichthys nelma (Pallas, 1773)

Nelma (Stenodus leucichthys nelma (Pallas, 1773)) is one of the biggest predators and a prominent representative of the whitefish family. It is a poorly studied valuable commercial species. The rate of growth and sexual maturation of this fish is very high compared to other whitefishes. Within the vast range of white salmon populations living in different geographical zones there can be found variability in meristic and size-weight characteristics. There are also differences in the time of sexual maturity of species in different rivers. Some negative limiting factors impact the nelma populations: pollution of water bodies, poaching, and transformation of the flows of large rivers (building the hydroelectric power stations, reservoirs, etc.). There have been presented the review of the published literature on nelma biology and the data of the proper research. Comparative analysis of the meristic, size-weight and physiological characteristics of nelma populations from different rivers within the geographical range has been made. From the review of available literary sources it follows that today the populations of nelma are characterized by a radical decline and rejuvenation of the spawning stock in almost all rivers of its habitat. There is found reducing the spawning areas of the species due to the regulation of the flows of large rivers. Studying biology and ecology of nelma as a valuable and endangered species is important today.

The Role of Pediatric Nutrition as a Modifiable Risk Factor for Precocious Puberty.

Puberty is a critical phase of growth and development characterized by a complex process regulated by the neuroendocrine system. Precocious puberty (PP) is defined as the appearance of physical and hormonal signs of pubertal development at an earlier age than is considered normal. The timing of puberty has important public health, clinical, and social implications. In fact, it is crucial in psychological and physical development and can impact future health. Nutritional status is considered as one of the most important factors modulating pubertal development. This narrative review presents an overview on the role of nutritional factors as determinants of the timing of sexual maturation, focusing on early-life and childhood nutrition. As reported, breast milk seems to have an important protective role against early puberty onset, mainly due to its positive influence on infant growth rate and childhood overweight prevention. The energy imbalance, macro/micronutrient food content, and dietary patterns may modulate the premature activation of the hypothalamic–pituitary–gonadal axis, inducing precocious activation of puberty. An increase in knowledge on the mechanism whereby nutrients may influence puberty will be useful in providing adequate nutritional recommendations to prevent PP and related complications.

MC3R links nutritional state to childhood growth and the timing of puberty.

The state of somatic energy stores in metazoans is communicated to the brain, which regulates key aspects of behaviour, growth, nutrient partitioning and development1. The central melanocortin system acts through melanocortin 4 receptor (MC4R) to control appetite, food intake and energy expenditure2. Here we present evidence that MC3R regulates the timing of sexual maturation, the rate of linear growth and the accrual of lean mass, which are all energy-sensitive processes. We found that humans who carry loss-of-function mutations in MC3R, including a rare homozygote individual, have a later onset of puberty. Consistent with previous findings in mice, they also had reduced linear growth, lean mass and circulatinglevels of IGF1. Mice lacking Mc3r had delayed sexual maturation and an insensitivity of reproductive cycle length to nutritional perturbation. The expression of Mc3r is enriched in hypothalamic neurons that control reproduction and growth, and expression increases during postnatal development in a manner that is consistent with a role in theregulation of sexual maturation. These findings suggest a bifurcating model of nutrient sensing by the central melanocortin pathway with signalling through MC4R controlling the acquisition and retention of calories, whereas signalling through MC3R primarily regulates the dispositionof calories into growth, lean mass and the timing of sexual maturation.

Jejunal transcriptomic profiling of two layer strains throughout the entire production period

The jejunum plays crucial roles for the digestion and absorption of nutrients and minerals and for barrier functions that are essential for a healthy, productive life cycle of farm animals, including laying hens. Accordingly, knowledge of the molecular pathways that emerge in the intestine during development, and particularly at the beginning of laying activity, will help to derive strategies for improving nutrient efficiency in laying hens. In this study, jejunal samples were obtained from two high-yielding layer strains at five developmental stages (weeks 10, 16, 24, 30 and 60 of life) for RNA-sequencing, alongside the profiling of blood plasma parameters to approximate the dynamics of mineral homeostasis. The results reflected a marked distinction between the pre-laying and laying phase as inferred from levels of parathyroid hormone, triiodothyronine, estradiol, vitamin D, and calcium. Moreover, the expression patterns of the intestinal mucosa responded directly to the changing metabolic and nutritional profiles at the beginning of the laying phase in maturing high-yielding strains of laying hens. These comprise signaling events namely RANK/RANKL signaling and cellular senescence. Taken together, the timing of sexual maturity of laying hens demands closer examination to unravel metabolic requirements and associated endogenous mechanisms.

Precocious puberty in male wild boars: a possible explanation for the dramatic population increase in Germany and Europe.

BackgroundThe wild boar population in Europe is steadily growing, one of the reasons for this increase probably being the high reproductive potential of this large mammal. Population management is important to stabilise wild boar numbers and a great deal of attention is focusing on the reasons, which might contribute to the high reproductive rates. Understanding the timing of puberty attainment provides information required for proper management practices. Knowledge of the earliest expected time of sexual maturation in male wild boars is limited, research being mostly focused on females. Previous hunting references indicate that sexual maturity in males occurs in the second year after birth. In contrast, male domestic pigs become sexually mature from about seven months of age. Thus, aims of this study were to investigate (1) whether there is a physiological ability for reproduction also in male wild boars of a younger age and (2) whether the body weight of wild boar males has a more important role than age in driving the maturation of the testis.MethodsMale wild boar individuals were sampled during hunting drives in the eastern part of Lower Saxony in Germany. Testes with epididymides from 74 males were collected and prepared for histological examination and immunohistochemistry. The reproductive status could be ascertained based on development/occurrence of different germ cell populations using histology and based on the immunohistochemical detection of the anti-Müllerian hormone and androgen receptor.ResultsIn this study, male wild boars aged nine to ten months already passed puberty and were able to reproduce if they had reached the appropriate body condition of about 29 kg dressed weight. Immunopositivity to the anti-Müllerian hormone in Sertoli cells was evident only in prepubertal animals and decreased with the onset of puberty. No immunoreaction was evident at postpuberty. The androgen receptor was detected in Sertoli cells, peritubular cells and Leydig cells, surprisingly already in Sertoli cells of prepubertal wild boars as well depending on body weight. Moreover, two-thirds of young males aged about ten months were precociously reproductively mature, showing histologically the presence of spermatozoa in testes and epididymides.ConclusionsAs piglets are mostly born in spring, also these young male individuals could target the heat of female wild boars in the winter months, resulting in the observed population increase. Therefore, a reduction in wild boar numbers should also focus on piglets of both sexes.

Effects of Roxithromycin on Reproduction,Growth, and Anti-oxidation System of Daphnia magna

Roxithromycin (ROX) is widespread in the water environment and has been reported to have ecotoxicological effects on aquatic organisms. To improve our understanding of these effects, we selected Daphnia magna as a test organism to study acute and chronic ROX toxicity on reproduction, growth, and antioxidant systems. The acute ROX toxicity was low, with 48 h-LC50 and 96h-LC50ROX values of 60.26 mg·L-1 and 39.81 mg·L-1, respectively. Furthermore, ROX concentrations of 0.5 μg·L-1 and 50 μg·L-1 significantly increased the frequency of egg laying, total number of eggs, and number of eggs per fetus. In the early exposure stages, ROX altered the sexual maturation time of Daphnia magna, affecting the frequency of egg laying and the number of eggs per fetus to cope with environmental stress. The intrinsic growth rate was also significantly increased by 50 μg·L-1 ROX. In both treatment groups, Daphnia magna had a shorter body length, abnormal heart rate, and inhibited swimming activity. Moreover, 50 μg·L-1 ROX inhibited the activities of POD, CAT, and GSH-Px by approximately 50% and induced MDA by more than 100%, resulting in the accumulation of reactive oxygen species in the body, which could potentially damage the cell membrane. In the 50 μg·L-1 ROX treatment, per 06 was up-regulated, enhancing the immune response of Daphnia magna. In contrast. gst and gst-theta were down-regulated, suggesting that ROX could weaken the detoxification effect of Daphnia magna. jhe, ecra, ecrb, rxr, vg1, vg2, and vit-2 were also down-regulated. ROX affected the secretion of juvenile and thyroid hormones, inhibiting the synthesis of vitellogenin. Finally, ROX also affected the growth and disturbed the population stability of Daphnia magna. This study provides a reference for the effects of ROX on the reproduction and growth of aquatic organisms and their responses at protein and gene levels.

Cross-resistance and lack of fitness costs occurred in the cyantraniliprole-resistant oriental fruit fly

The oriental fruit fly, Bactrocera dorsalis (Hendel), is one of the most globally important insect pests that have evolved resistance to various groups of insecticides. To clarify the relationships between a novel and widely used anthranilic diamide insecticide (cyantraniliprole) and other regular insecticides used to effectively control B. dorsalis, its cross-resistance and fitness costs to various insecticides were determined. Bioassays with cyantraniliprole-resistant and cyantraniliprole-susceptible strains indicated moderate levels of cross-resistance to both of the spinosyn compounds, Spinosad (1.59-fold) and Spinetoram (1.54-fold), the organophosphate (Trichlorphon, 0.66-fold), and beta-cypermethrin (2.41-fold), one of the pyrethroids compounds. Most of the tested biological parameters of B. dorsalis were negatively affected by cyantraniliprole resistance. Compared with the susceptible strain, prolonged larval duration, higher pupa weight, longer timing of sexual maturation, were observed in the cyantraniliprole-resistant strain. Pupa duration, oviposition, and male remating inhibition on the fifth day were significantly lower for the cyantraniliprole-resistant strain than those of the susceptible strain. Moreover, there was no fitness costs associated with resistance to cyantraniliprole. Morderate levels of cross-resistance were observed between cyantraniliprole and four other selected insecticides (Spinosad, Spinetoram, Trichlorphon, and Beta-cypermethrin). However, the lack of fitness costs in the cyantraniliprole-resistant strain of B. dorsalis could promote the rapid development of resistance to cyantraniliprole. Thus, the results obtained here were useful for the application and resistance management of cyantraniliprole against B. dorsalis.

The Role of Fetal, Infant, and Childhood Nutrition in the Timing of Sexual Maturation.

Puberty is a crucial developmental stage in the life span, necessary to achieve reproductive and somatic maturity. Timing of puberty is modulated by and responds to central neurotransmitters, hormones, and environmental factors leading to hypothalamic-pituitary-gonadal axis maturation. The connection between hormones and nutrition during critical periods of growth, like fetal life or infancy, is fundamental for metabolic adaptation response and pubertal development control and prediction. Since birth weight is an important indicator of growth estimation during fetal life, restricted prenatal growth, such as intrauterine growth restriction (IUGR) and small for gestational age (SGA), may impact endocrine system, affecting pubertal development. Successively, lactation along with early life optimal nutrition during infancy and childhood may be important in order to set up timing of sexual maturation and provide successful reproduction at a later time. Sexual maturation and healthy growth are also influenced by nutrition requirements and diet composition. Early nutritional surveillance and monitoring of pubertal development is recommended in all children, particularly in those at risk, such as the ones born SGA and/or IUGR, as well as in the case of sudden weight gain during infancy. Adequate macro and micronutrient intake is essential for healthy growth and sexual maturity.

Ecdysone Quantification from Whole Body Samples of Drosophila melanogaster Larvae.

Steroid hormones strictly control the timing of sexual maturation and final body size both in vertebrates and invertebrates. In insects, the steroid hormone ecdysone controls the timing of the molts between larval instars as well as the transition to metamorphosis. Growth during the final instar accounts for over 80% of the increase in final mass in insects, and the duration of this growth period is driven by a sequence of small ecdysone pulses that ultimately induce metamorphosis. Historically the biologically active form of ecdysone, 20-hydroxyecdysone (20E), was quantified using radio-immunoassays, bioassays, or chromatography assays. However, these assays are methodologically complicated and often time consuming. Furthermore, collecting samples for precise measurements of ecdysone concentrations using these assays is limited in small insects like Drosophila melanogaster. Here, we describe an accurate and sensitive method to collect carefully-staged third instar larvae suitable for preparing samples for ecdysone quantification using a commercially-available 20E enzyme immunoassay (EIA). Because we resynchronize larval development at the molt to the final instar, collect large samples, and weigh each sample, we are able to detect a small ecdysone peak early in the final instar known as the critical weight ecdysone peak. This method detects peaks as low as 6 pg 20E/mg larval sample, allowing us to quantify other small ecdysone peaks in flies - the necessary prerequisite for eventually determining their regulation and function.