Effects Of Endogenous Hormones Research Articles

Prenatal Stress and Endo-crine Disrupting Chemical Exposure: Hypothalamic-Pituitary-Adrenal Axis Dysregulation as a Mecha-nism for the Health Conse-quences of Both

During the past several decades there has been increasing attention to the risks of exposure to endocrine disrupting chemicals, agents that mimic or block the effects of endogenous hormones. Previous research demonstrates that there may be critical periods of development where factors such as prenatal stress and endocrine disrupting chemical exposure can result in endocrine system dysregulation which manifests both immediately and later in life. This review describes the types of common endocrine disrupting chemicals and routes of exposure, the structure and functions of the hypothalamic-pituitary-adrenal axis and its role in the physiological response to stress, and highlights the current evidence showing that endocrine disrupting chemicals may alter normal hypothalamic-pituitary-adrenal axis functions. These topics are unified upon discussion of evidence indicating that prenatal endocrine disrupting chemical exposure has many of the same effects as prenatal stress on the hypothalamic-pituitary-adrenal axis, leading to long-term dysregulation of the axis and subsequent alterations in physiological responses to stress. We further suggest that prenatal endocrine disrupting chemical exposure in combination with prenatal stress may result in additive, if not synergistic effects on the hypothalamic-pituitary-adrenal axis-mediated stress response. Finally, we discuss vulnerable populations at an elevated risk for dual stress and endocrine disrupting chemical exposure and emphasize critical areas for future research.

Current challenges faced by transgender and gender-diverse patients and providers in anesthesiology.

Current challenges faced by transgender and gender-diverse patients and providers in anesthesiology.

Seasonally Related Disruption of Metabolism by Environmental Contaminants in Male Goldfish (Carassius auratus).

Endocrine disrupting chemicals mimic or disrupt action of the natural hormones, adversely impacting hormonal function as well as cardiovascular, reproductive, and metabolic health. Goldfish are seasonal breeders with an annual reproductive cycle regulated by neuroendocrine signaling which involves allocation of metabolic energy to sustain growth and reproduction. We hypothesize that seasonal changes in physiology alter overall vulnerability of goldfish to metabolic perturbation induced by environmental contaminants. In this study, we assess effects of endogenous hormones, individual contaminants and their mixture on metabolism of goldfish at different reproductive stages. Exposure effects were assessed using 1H-NMR metabolomics profiling of male goldfish midbrain, gonad and liver harvested during early recrudescence (October), mid-recrudescence (February) and late recrudescence (June). Compounds assessed include bisphenol A, nonylphenol, bis(2-ethylhexyl) phthalate, fucosterol and a tertiary mixture (DEHP + NP + FS). Metabolome-level responses induced by contaminant exposure across tissues and seasons were benchmarked against responses induced by 17β-estradiol, testosterone and thyroid hormone (T3). We observe a clear seasonal dependence to metabolome-level alteration induced by hormone or contaminant exposures, with February (mid-recrudescence) the stage at which male goldfish are most vulnerable to metabolic perturbation. Responses induced by contaminant exposures differed from those induced by the natural hormones in a season-specific manner. Exposure to the tertiary mixture induced a functional gain at the level of biochemical pathways modeling over responses induced by individual components in select tissues and seasons. We demonstrate the importance of seasonally driven changes in physiology altering overall vulnerability of goldfish to metabolic perturbation induced by environmental contaminants, the relevance of which likely extends to other seasonally-breeding species.

Ozonolysis of Permethrin in the Atmosphere: Mechanism, Kinetics, and Evaluation of Toxicity.

Pyrethroid, a pesticide widely used worldwide, could mimic, block, or synergize the effects of endogenous hormones in humans or mammals after entering into the atmosphere and after being sprayed and applied in large quantities. This research aims to study the mechanism, kinetics, and eco-toxicity evaluation of the ozonolysis of permethrin (PER)-one of the typical pyrethroid (type I) pesticides. Existing experimental studies only predicted that ozonolysis of PER could generate a cycloperoxy analogue of PER (IM13-1-11), and the reaction mechanism has not yet been completed. To make up for the lack of experimental results, the 13 primary reaction pathways of PER and ozone, as well as the subsequent reactions of Criegee intermediates with small molecules such as NOx, COx, SO2, and O2, have been studied to propose new reaction paths by quantum chemical calculations in this work. We calculated the total reaction rate constant of PER and ozone at 298 K and 1 atm based on the calculated thermodynamic data and the transition state theory (TST), which was compared with the experimental values to prove the reliability of our results. Based on the quantitative structure and activity relationship, we predicted the acute and chronic toxicity of PER and its products of ozonolysis to three representative organisms-fish, daphnia, and green algae to avoid animal experiments. The results show that ozonolysis products of PER are still extremely harmful to the environment and should be taken seriously, although the products have less toxicity than PER.

Effects of Endogenous Hormones and Sugars on Fruit Size Driven by Cell Division between Korla Fragrant Pear and Its Bud Mutation

Large-fruit bud mutations are important factors in fruit tree breeding. However, little is known about the differences between varieties and bud mutations. The ploidy identification of Korla fragrant pear (Pyrus sinkiangensis Yu) and its large bud mutation Zaomeixiang pear showed that the large-fruit characteristic was not caused by chromosome doubling. By counting mesocarp cells at different stages, we found that the number of cells increased continuously after pollination, and the difference was the greatest at 28 days after full bloom (DAFB), and was about 9.4 × 106. After 28 days, the difference in cell volume became bigger and bigger, so both the cell volume and cell number caused the difference in fruit size between Korla fragrant pear and Zaomeixiang pear. To obtain more insights into the differences in fruit size driven by cell division, we analyzed the endogenous hormones [indole ascetic acid (IAA), zeatin riboside (ZR), gibberellic acid (GA), and abscisic acid (ABA)], and the main sugars (glucose, fructose, sucrose, and sorbitol). The ZR content of Zaomeixiang pear was always greater than that of Korla fragrant pear at all stages. The ABA content was the opposite except for at 7 DAFB during cell division; the greatest difference was 30.87 ng/g, which appeared at 28 DAFB. ABA and ZR correlated negatively with cell number. After 7 DAFB, the ratio of IAA/ABA, ZR/ABA, and GA/ABA in Zaomeixiang pear was always greater than that for Korla fragrant pear at 28 DAFB. The difference in glucose content at 21 DAFB was the greatest, at 4.80 ng/g. Large amounts of sorbitol accumulated during whole-cell division. Glucose and sorbitol correlated positively with cell numbers. In summary, the data suggest that the different contents of glucose, sorbitol, ZR, and ABA, and the ratio of endogenous hormones might be related to cell division in Korla fragrant pear and Zaomeixiang pear. The result provides a theoretical basis for the large-size fruit’s high-quality production and genetic breeding of Korla fragrant pear and its bud mutation.

Should Exogenous Estrogens Be Stopped for Surgery in Transgender Women?

Should Exogenous Estrogens Be Stopped for Surgery in Transgender Women?

Effect of endogenous hormones, antisperm antibody and oxidative stress on semen quality of crossbred bulls

The present study was designed to evaluate the effect of factors like hormones, antisperm antibody (ASA), and oxidative stress and its relation with semen quality in crossbred bulls. Ejaculates from two bulls were categorized into good (n = 12) and poor (n = 12) based on initial progressive motility, that is, ≥70% and ≤50%, respectively. The level of hormones like Testosterone (p < 0.05) and PGE2 (p < 0.01) was significantly higher in good-quality ejaculates compared to poor-quality ejaculates; however, estradiol (p < 0.05), progesterone, oxidative stress, and ASAs were significantly higher (p < 0.01) in poor-quality ejaculates compared to good-quality ejaculates. Therefore, it could be concluded that oxidative stress and hormonal imbalance might have resulted in high number of dead and defective spermatozoa which was ultimately responsible for poor quality semen ejaculates.

Epigenetics, estrogenic endocrine-disrupting chemicals (EDCs), and the brain.

Endocrine-disrupting chemicals (EDCs) are a major public health concern, yet there are gaps in knowledge about the mechanisms for their effects. The brain is incredibly sensitive to small changes in the hormonal environment during early development, with natural sex differences in gonadal hormones shaping the organization of sex-specific neural circuits early in life. EDC exposure during these periods can lead to lifelong impacts on neurobiological health outcomes. Recently, epigenetic mechanisms have been proposed as a potential molecular mechanism for effects of endogenous hormones on the organization of developing brain circuits, leading to speculation that these mechanisms may underlie the long-term impacts of EDC exposure. Of these mechanisms, DNA methylation, associated with gene suppression, and histone marks, associated with gene suppression or activation, will be discussed. We review the evidence for hormones and their role in brain sexual differentiation; underlying epigenetic mechanisms; and how two classes of estrogenic EDCs, BPA and PCBs, may interfere with these processes to change brain structure and function.

Genome-wide analysis of lncRNA and mRNA expression and endogenous hormone regulation during tension wood formation in Catalpa bungei

BackgroundPhytohormones are the key factors regulating vascular development in plants, and they are also involved in tension wood (TW) formation. Although the theory of hormone distribution in TW formation is widely supported, the effects of endogenous hormones on TW formation have not yet been assessed. In this study, TW formation was induced in Catalpa bungei by artificial bending. The phytohormone content of TW, opposite wood (OW) and normal wood (NW) was determined using liquid chromatography-mass spectrometry (LC-MS), and transcriptome sequencing was performed. The hormone content and related gene expression data were comprehensively analyzed.ResultsThe results of analyses of the plant hormone contents indicated significantly higher levels of cis-zeatin (cZ), indoleacetic acid (IAA) and abscisic acid (ABA) in TW than in OW. Genes involved in the IAA and ABA synthesis pathways, such as ALDH (evm.model.group5.1511) and UGT (evm.model.scaffold36.20), were significantly upregulated in TW. and the expression levels of ARF (evm.model.group5.1332), A-ARR (evm.model.group0.1600), and TCH4 (evm.model.group2.745), which participate in IAA, cZ and Brassinolide (BR) signal transduction, were significantly increased in TW. In particular, ARF expression may be regulated by long noncoding RNAs (lncRNAs) and the HD-ZIP transcription factor ATHB-15.ConclusionsWe constructed a multiple hormone-mediated network of C. bungei TW formation based on hormone levels and transcriptional expression profiles were identified during TW formation.

Bisphenol Exposure and Type 2 Diabetes: New Evidence for a Potential Risk Factor

Bisphenol Exposure and Type 2 Diabetes: New Evidence for a Potential Risk Factor

The value of central regulators of the immune response in the development of autoimmune thyroid diseases

The specific relationship between the endocrine and immune systems is represented by a numerous number of factors and mechanisms that form the structure and ensure the function of each of the two systems. For example, immunocompetent cells can produce immunologically active substances, as well as some hormones. On the other hand, immune cells are available to the effects of endogenous hormones. Currently, the so-called cross-regulation of endocrine and immune mechanisms in an equilibrium of pro-and anti-inflammatory responses has not been sufficiently studied. Among other autoimmune lesions, autoimmune thyreopathy occupies a significant place. The development of an autoimmune lesion of the thyroid gland is a complex process, which is the result of the interaction of infiltrating lymphocyte and thyrocyte tissue that can express a wide range of molecules involved in the immune response. Immunological and immunogenetic factors play a major role in the pathogenesis of autoimmune thyroid diseases, such as autoimmune thyroiditis and Graves disease. Despite the fact that more than 100 years have passed since the first description of autoimmune thyroiditis and Graves disease has been known for many centuries, the mechanisms of these pathologies are still not fully understood.

MELATONİNİN KORTİ ORGANI OTOTOKSİSİTESİ ÜZERİNE OLASI KORUYUCU ETKİSİ

Introduction: Endocrine disruptors or hormone-like chemicals in our environment compromise metabolism by suppressing the effects of endogenous hormones. One of them Nonylphenol (NFA) as a result of bioaccumulation in living tissues to form oxidative stress. This causes damage to lipids, proteins and DNA structure, cellular reactions&nbsp;and&nbsp;formation in the body. Melatonin released from the pineal gland at night has an important function in circadian rhythm and functions as a protector against oxidative stress caused by reactive oxygen species. Objective: To determine the possible protective effect of melatonin, which is antioxidant, against the autotoxicity that Nonylphenol will cause in the&nbsp;corti&nbsp;organ. Method: Wistar albino female rats were divided into 3 groups (Control group, Nonylphenol group, Nonylphenol + Melatonin group). No treatment was applied to the control group. Nonylphenol group was given by gavage by dissolving a single dose of 50μl Nonylphenol in 100μl corn oil on the 16th day. In the Nonylphenol + Melatonin group, 10mg / kg melatonin was injected intraperitoneally for 15 days, and on the 16th day, a single dose of 50μl Nonylphenol was dissolved in 100μl corn oil and administered via gavage. The following day,&nbsp;cocheal&nbsp;tissues were removed under anesthesia and fixed in 10% formaldehyde. After&nbsp;decalcified&nbsp;process step, following after routine tissue was stained with hematoxylin and eosin and Masson's Trichrome. Histopathological and morphometric evaluations were made in line with the previously determined criteria. Results: It was determined that the lengths of tectorial and basilar membranes in the basal, media&nbsp;and&nbsp;apex regions of the cochleae belonging to nonylphenol treated groups occurred but were not statistically significant (p&gt; 0.05). It was determined that nonylphenol application affects the outer and inner hair cells located in the apex of the cochlea and the shortened cell lengths and this shortening was statistically significant (p &lt;0.05). outer hair cells in the basal region of the cochlea there was&nbsp;significant&nbsp;difference in the level between all groups when evaluated statistically significant (p &lt;0.05). It was also among the morphometric findings that nonylphenol application caused a narrowing of the width of the&nbsp;citria&nbsp;vascularis&nbsp;in all turns of the cochlea. Conclusion: on the cochlear application of Nonylphenol brought ototoxicity was determined to occur and also the protective effect of melatonin within antioxidant.

Subjective response to intranasal nicotine administration in oral contraceptive users and naturally-cycling women

IntroductionApproximately half of premenopausal women who smoke cigarettes also use hormonal contraceptives, with most using oral contraceptives (OCs). While research on the effects of endogenous hormones on smoking-related outcomes continues to expand, little is known about the influence of OCs on similar outcomes. We sought to explore differences in the subjective response to nicotine by OC use after stratifying by testing condition (e.g., smoking status). MethodsParticipants were regular (≥5 cigarettes/day) smokers, classified into OC and naturally cycling (NC) groups. All participants completed four total lab sessions by smoking status (ad libitum smoking, acute smoking abstinence) and anticipated progesterone level (low progesterone week (LPW), high progesterone week (HPW)). Each lab session included self-administration of intranasal nicotine (Time 0 min), assessment of subjective response via the Subjective State Scale (−30 and + 5 min). ResultsCompared to the NC group (n = 28), the OC group (n = 14) was younger (26.2 ± 1.1 versus 24.2 ± 1.1; p < 0.001) and had a lower Fagerström Test for Nicotine Dependence score (3.4 ± 0.5 versus 2.6 ± 0.5; p = 0.011). Progesterone-to-estradiol ratios varied significantly by group at three of the four time points (p < 0.05). During ad libitum smoking, the OC group had significantly lower craving after nicotine administration than the NC group (1.93 ± 0.33 versus 2.89 ± 0.23; p = 0.024). No other significant differences in subjective response were identified. ConclusionsDespite significantly different hormone levels, group differences in subjective response to nicotine were relatively few. Additional research is needed to elucidate the mechanisms involved in these observations, as well as explore how they may influence cessation in women.

Autism spectrum disorders, endocrine disrupting compounds, and heavy metals in amniotic fluid: a case-control study

BackgroundEvidence has indicated that some non-inherited factors such as exposure to environmental pollutants are associated with neurodevelopment disorders like autism spectrum disorder (ASD). Studies report that endocrine disrupting compounds (EDCs), including polychlorinated biphenyls, organochlorine pesticides, perfluoroalkyl substances (PFAS), and some metals, have adverse effects on the fetal neurodevelopment. The aim of this study was to measure the amniotic fluid (AF) levels of EDCs and metals as well as the receptor transactivities induced by AF and investigate the possible link between prenatal exposure to EDCs and heavy metals and ASD risk.MethodsIn this case-control study, we included AF samples of 75 ASD cases and 135 frequency-matched controls and measured the levels of the endogenous sex hormones, PFAS, and elements including heavy metals. The combined effect of endogenous hormones and EDCs on the receptor of estrogen (ER), androgen (AR), aryl hydrocarbon (AhR), and thyroid hormone-like activity were also determined and expressed as receptor ligand equivalents. We assessed the associations of AF levels of chemicals, sex hormones, and receptor activities with ASD risk using unconditional logistical regression analyses. To control for multiple comparisons, the false discovery rate (FDR) was used and q values less than 0.25 were designated as statistical significance.ResultsPFAS and metals were detectable in AF samples. The ASD cases had significantly lower AF levels of PFAS than controls, and the adjusted odds ratio (OR) was 0.410 (95% CI 0.174, 0.967; p = 0.042; FDR qvalue = 0.437) for perfluorooctane sulfonate (PFOS). The principal component, including PFAS congeners, copper, iron, and estrogenic activity, was significantly inversely associated with ASD risk (adjusted OR = 0.100; 95% CI 0.016, 0.630; p = 0.014; FDR qvalue = 0.098).Testosterone level in AF weakly associated with ASD risk (adjusted OR = 1.002; 95% CI 1.000, 1.004; p = 0.05). However, after multiple comparison correction, the association was not significant (FDR qvalue = 0.437). No significant associations between AF-induced receptor transactivities and ASD risk were observed. The adjusted OR was 2.176 (95%CI 0.115, 41.153) for the ratio of the combined androgenic activity to combined estrogenic activity.ConclusionsThe presence of PFAS and heavy metals in AF indicates that they can cross the placenta. The inverse association between levels of PFAS congeners in AF and ASD risk might relate to the weak estrogenic activities and anti-androgenic activities of PFAS.The observed tendency of positive association between the ratio of combined androgenic effect to the combined estrogenic effect and ASD risk needs further studies to explore whether EDCs together with endogenous hormones play a role in the development of ASD.

The effect of endogenous hormones on plant morphology and fruit quality of tomato under difference between day and night temperature

The difference between day and night temperature (DIF) was reported to influence plant morphology and fruit quality, but the mechanism was poorly known. Therefore, controlled-environment experiments were carried out to investigate the mechanism of DIF influenced plant morphology and fruit quality attributes of tomato during fruit stage. Five day/night temperature regimes 16/34, 19/31, 25/25, 31/19 and 34/16°C with respective DIFs of –18, –12, 0, +12 and +18 at a common 25°C mean daily temperature were used. The results showed that gibberellin 3, indoleacetic acid and zeatin content of stem tip were enhanced significantly by positive DIF and inhibited by negative DIF, while abscisic acid was not significantly influenced by DIF. Plant height, stem diameter, fruit diameter and leaf area were enhanced significantly by positive DIF regimes and inhibited by negative DIF regimes. The soluble sugars, vitamin C and soluble protein content increased under positive DIF while decreased under negative DIF. Both plant morphology and fruit quality of tomato were significantly related to endogenous hormones.

Proandrogenic and Antiandrogenic Progestins in Transgender Youth: Differential Effects on Body Composition and Bone Metabolism.

Progestins can be used to attenuate endogenous hormonal effects in late-pubertal transgender (trans) adolescents (Tanner stage B4/5 and G4/5). Currently, no data are available on the effects of progestins on the development of bone mass or body composition in trans youth. To study prospectively the evolution of body composition and bone mass in late-pubertal trans adolescents using the proandrogenic or antiandrogenic progestins lynestrenol (L) and cyproterone acetate (CA), respectively. Forty-four trans boys (Tanner B4/5) and 21 trans girls (Tanner G4/5) were treated with L or CA for 11.6 (4 to 40) and 10.6 (5 to 31) months, respectively. Anthropometry, grip strength, body composition, and bone mass, size, and density were determined by dual-energy X-ray absorptiometry and peripheral quantitative computed tomography before the start of progestin and before addition of cross-sex hormones. Using L, lean mass [+3.2 kg (8.6%)] and grip strength [+3 kg (10.6%)] significantly increased, which coincided with a more masculine body shape in trans boys. Trans girls showed loss of lean mass [-2.2 kg (4.7%)], gain of fat mass [+1.5 kg (9.4%)], and decreased grip strength Z scores. CA limited normal bone expansion and impeded pubertal bone mass accrual, mostly at the lumbar spine [Z score: -0.765 to -1.145 (P = 0.002)]. L did not affect physiological bone development. Proandrogenic and antiandrogenic progestins induce body composition changes in line with the desired appearance within 1 year of treatment. Bone health, especially at the lumbar spine, is of concern in trans girls, as bone mass accrual is severely affected by androgen suppressive therapy.

Exposure to endocrine disruptors 17alpha-ethinylestradiol and estradiol influences cytochrome P450 1A1-mediated genotoxicity of benzo[a]pyrene and expression of this enzyme in rats

Endocrine disruptors (EDs) are compounds that interfere with the balance of the endocrine system by mimicking or antagonising the effects of endogenous hormones, by altering the synthesis and metabolism of natural hormones, or by modifying hormone receptor levels. The synthetic estrogen 17α-ethinylestradiol (EE2) and the environmental carcinogen benzo[a]pyrene (BaP) are exogenous EDs whereas the estrogenic hormone 17β-estradiol is a natural endogenous ED. Although the biological effects of these individual EDs have partially been studied previously, their toxicity when acting in combination has not yet been investigated. Here we treated Wistar rats with BaP, EE2 and estradiol alone or in combination and studied the influence of EE2 and estradiol on: (i) the expression of cytochrome P450 (CYP) 1A1 and 1B1 in rat liver on the transcriptional and translational levels; (ii) the inducibility of these CYP enzymes by BaP in this rat organ; (iii) the formation of BaP-DNA adducts in rat liver in vivo; and (iv) the generation of BaP-induced DNA adducts after activation of BaP with hepatic microsomes of rats exposed to BaP, EE2 and estradiol and with recombinant rat CYP1A1 in vitro. BaP acted as a strong and moderate inducer of CYP1A1 and 1B1 in rat liver, respectively, whereas EE2 or estradiol alone had no effect on the expression of these enzymes. However, when EE2 was administered to rats together with BaP, it significantly decreased the potency of BaP to induce CYP1A1 and 1B1 gene expression. For EE2, but not estradiol, this also correlated with a reduction of BaP-induced CYP1A1 enzyme activity in rat hepatic microsomes. Further, while EE2 and estradiol did not form covalent adducts with DNA, they affected BaP-derived DNA adduct formations in vivo and in vitro. The observed decrease in BaP-DNA adduct levels in rat liver in vivo resulted from the inhibition of CYP1A1-mediated BaP bioactivation by EE2 and estradiol. Our results indicate that BaP genotoxicity mediated through its activation by CYP1A1 in rats in vivo is modulated by estradiol and its synthetic derivative EE2.

Plant growth regulator interactions in physiological processes for controlling plant regeneration and in vitro development of Tulbaghia simmleri

The endogenous auxin and cytokinin contents of in vitro regenerated Tulbaghia simmleri maintained on applied plant growth regulators in Murashige and Skoog (MS) medium were investigated using UHPLC–MS analysis. The highest number of shoots (27.6 per leaf) were produced in MS medium supplemented with 2.5 μM thidiazuron. A higher number of these shoots were rooted with 10 μM 6-(2-hydroxy-3-methylbenzylamino) purine (PI-55, cytokinin antagonist). Production of somatic embryos (SEs: 16.4–4.6, globular to cotyledonary stages) improved significantly with liquid MS medium containing 2.5 μM picloram, 2.5 μM phloroglucinol (PG) and 1.5 μM gibberellic acid or 1.5 μM PI-55 and 1.0 μM trans-zeatin. SEs (torpedo and cotyledonary stages) germinated (100%) in plant growth regulator free MS medium. The plantlets were acclimatized and all survived in the greenhouse. Higher levels of endogenous auxin, 2-oxindole-3-acetic acid (oxIAA, 371.52 pmol/g DW) and indole-3-acetylaspartate (IAAsp, 141.56 pmol/g DW) were detected in shoots from PG treatments. The roots of garden-grown mother plants possessed the highest level of indole-3-acetic acid (IAA, 630.54 pmol/g DW) and oxIAA (515.26 pmol/g DW). Cytokinins [CKs: trans-zeatin-O-glucoside (tZOG), cis-zeatin (cZ) and N6-isopentenyladenosine-5′-monophosphate (iPRMP)] levels were relatively high in shoots and roots of plantlets in vitro. However, PI-55 treatments influenced the development of plantlets promoting a higher biosynthesis level of iPRMP (418.06 pmol/g DW in root) and cZRMP (904.61 pmol/g DW in roots and 1427.83 pmol/g DW in shoots). The presented protocols offer organogenesis and somatic organogenesis systems for rapid plant regeneration of T. simmleri. In addition, the importance of exogenous and endogenous hormonal effects on in vitro plant growth and development as well as endogenous hormone metabolism signalling and transport related to the physiological processes of CK metabolism and transport are illustrated for in vitro development of T. simmleri.

Effects of endogenous hormones on variation of shoot branching in a variety of non-heading Chinese cabbage and related gene expression

Shoot branching (tillering) primarily determines plant shoot architecture and has been studied in many plants. Shoot branching is an important trait in non-heading Chinese cabbage (Brassica rapa ssp. chinensis Makino). The B. rapa ssp. chinensis var. multiceps exhibits unique and multiple shoot branching characteristics. Here, we analyzed the variation in shoot branching between ‘Maertou,’ with multiple shoot branching, and ‘Suzhouqing,’ a common variety. The levels of endogenous indole-3-acetic acid (IAA), zeatin riboside and active gibberellins in the shoot meristem tissues of the two cultivars were quantified by enzyme-linked immunosorbent assay during the vegetative growth stage. High levels of IAA maintained axillary bud dormancy and repressed axillary bud outgrowth allowing shoot branching to form in the vegetative stage in ‘Suzhouqing.’ In contrast, low levels of IAA did not inhibit axillary buds in ‘Maertou,’ while a high level of cytokinin promoted axillary bud growth and branch shoot development. Exogenous hormone (rac-GR24 and 6-benzylaminopurine) treatment showed that ‘Maertou’ was relatively sensitive to cytokinin, because the fold changes of cytokinin-responsive genes in ‘Maertou’ were significantly more frequent than those in ‘Suzhouqing’. Cytokinin was the direct regulator for axillary bud growth of ‘Maertou’. Compared with ‘Suzhouqing’, ‘Maertou’ was sensitive to cytokinin and this weakened the strigolactone–cytokinin branching pathway.

Neuroendocrine disruption of organizational and activational hormone programming in poikilothermic vertebrates

ABSTRACTIn vertebrates, sexual differentiation of the reproductive system and brain is tightly orchestrated by organizational and activational effects of endogenous hormones. In mammals and birds, the organizational period is typified by a surge of sex hormones during differentiation of specific neural circuits; whereas activational effects are dependent upon later increases in these same hormones at sexual maturation. Depending on the reproductive organ or brain region, initial programming events may be modulated by androgens or require conversion of androgens to estrogens. The prevailing notion based upon findings in mammalian models is that male brain is sculpted to undergo masculinization and defeminization. In absence of these responses, the female brain develops. While timing of organizational and activational events vary across taxa, there are shared features. Further, exposure of different animal models to environmental chemicals such as xenoestrogens such as bisphenol A-BPA and ethinylestradiol-EE2, gestagens, and thyroid hormone disruptors, broadly classified as neuroendocrine disrupting chemicals (NED), during these critical periods may result in similar alterations in brain structure, function, and consequently, behaviors. Organizational effects of neuroendocrine systems in mammals and birds appear to be permanent, whereas teleost fish neuroendocrine systems exhibit plasticity. While there are fewer NED studies in amphibians and reptiles, data suggest that NED disrupt normal organizational-activational effects of endogenous hormones, although it remains to be determined if these disturbances are reversible. The aim of this review is to examine how various environmental chemicals may interrupt normal organizational and activational events in poikilothermic vertebrates. By altering such processes, these chemicals may affect reproductive health of an animal and result in compromised populations and ecosystem-level effects.