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2.
Sci Total Environ ; 767: 145444, 2021 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-33636781

RESUMO

A developmental toxicity testing design was evaluated for larval and post-metamorphic Blanchard's cricket frogs (Acris blanchardi) raised in outdoor enclosures. Larvae were chronically exposed to 17ß-estradiol (0.0-2.3 µg/L E2) from free swimming (Gosner stage 26) until metamorphosis. Juvenile frogs were allowed to mature within the enclosures for 60 days to assess effects of larval exposure on development, including body mass, snout-vent length (SVL), sex ratio, gonad size, and gonadal histopathology. Forty-eight percent of the initial 600 animals were recovered at the end of the study. Recovery was not influenced by E2 exposure, but larval losses were negatively impacted by unusually high spring rain events that flooded some larval tanks, and heat-related mortality of late stage larvae during summer. All surviving larvae completed metamorphosis within an average of 47 days. Overall, E2 exposure did not influence sex ratio, or the body mass, SVL, or gonad size of either males or females. Development of testes was not influenced by E2 exposure, but oviduct development in males was 4.5-fold greater in the highest treatment. Oviduct and ovary development in females exposed to the two highest E2 treatments were half that of control females. Although not treatment related and despite ad-lib feeding, variation in terminal body mass and SVL within enclosures was pronounced, with minimum - maximum differences ranging from 207 to 1442 mg for body mass and 1 mm to 15 mm for SVL. This design allowed us to assess the effects of larval exposure to a contaminant on post-metamorphic development of a native amphibian in a semirealistic field environment. With modifications to decrease flooding or overheating, this enclosure design and species is a good test system for assessing contaminant effects on development of an amphibian from early larval stages through reproductive maturity.


Assuntos
Gryllidae , Animais , Anuros , Feminino , Gônadas , Larva , Masculino , Metamorfose Biológica
3.
Gene ; 780: 145522, 2021 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-33631243

RESUMO

Eye migration during flatfish metamorphosis is driven by asymmetrical cell proliferation. To figure out Prolactin (PRL) function in this process, the full-length cDNA of prl was cloned from Japanese flounder (Paralichthys olivaceus) in our study. The deduced PRL protein shares highly conserved sequence with other teleosts, but has several amino acids loss compared with higher vertebrates, including amphibians, reptiles, avian and mammals. Spatio-temporal expression of prl gene displayed its extensive expression in the early development stages, while the limited expression of prl was observed in the pituitary, brain, and intestine of adult fish. In situ hybridization showed the asymmetrical distribution patterns of prl gene around the eyes during metamorphosis, which was coincident with the cell proliferation signals. Colchicine inhibited cell proliferation and reduced the prl gene expression, which indicates that PRL was involved in cell proliferation in the suborbital area of the migrating eye. The treatment of methimazole and 9-cis-retinoic acid respectively led to a reduction in the number of proliferating cells and the downregulation of prl expression, suggesting PRL was regulated by thyroid hormone signaling pathway and retinoic acid related signaling pathways. The results gave us a basic understanding of PRL function during flatfish metamorphosis.


Assuntos
Olho/enzimologia , Proteínas de Peixes , Linguado , Regulação da Expressão Gênica no Desenvolvimento , Metamorfose Biológica , Prolactina , Animais , Proteínas de Peixes/biossíntese , Proteínas de Peixes/genética , Linguado/embriologia , Linguado/genética , Prolactina/biossíntese , Prolactina/genética
4.
Sci Total Environ ; 753: 141940, 2021 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-32890874

RESUMO

Environmental pollutants and especially endocrine disrupting chemicals (EDCs) are implicated as one of the drivers of the amphibian declines. To advance the understanding of the risks of EDCs to amphibians, methods to determine endocrine-linked adverse effects are needed. The aims were to 1) develop a partial life-cycle assay with the model frog Xenopus tropicalis to determine endocrine perturbation and adverse developmental effects, and 2) determine effects of propiconazole in this assay. Propiconazole is a pesticide with multiple endocrine modes of action in vitro. Its potential endocrine activity and adverse effects in amphibians remain to be elucidated. Tadpoles were exposed to 0, 33 and 384 µg propiconazole/L during critical developmental windows until completed metamorphosis. At metamorphosis, a sub-sample of animals was analysed for endpoints for disruption of estrogen/androgen (sex ratio, brain aromatase activity) and thyroid pathways (time to metamorphosis). The remaining individuals were kept unexposed for 2 months post-metamorphosis to analyze effects on sexual development including gonadal and Müllerian duct maturity and gametogenesis. At metamorphosis, brain aromatase activity was significantly increased in the high-dose group compared to control. In both propiconazole groups, an increased proportion of individuals reached metamorphosis faster than the mean time for controls, suggesting a stimulatory effect on the thyroid system. At 2 months post-metamorphosis, testis size, sperm and Müllerian duct maturity were reduced in the low-dose males, and the liver somatic index in males was increased in both propiconazole groups, compared with controls. In conclusion, our results show that propiconazole exposure caused endocrine perturbations and subsequent hepatic and reproductive effects evident at puberty, indicating persistent disruption of metabolism and male reproductive function. Our findings advance the development of methodology to determine endocrine and adverse effects of EDCs. Moreover, they increase the understanding of endocrine perturbations and consequent risk of adverse effects of azoles in amphibians.


Assuntos
Disruptores Endócrinos , Triazóis , Animais , Disruptores Endócrinos/toxicidade , Humanos , Larva , Masculino , Metamorfose Biológica , Reprodução , Triazóis/toxicidade , Xenopus
5.
Ecotoxicol Environ Saf ; 207: 111101, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-32905937

RESUMO

To regulate the presence of contaminants in Brazilian water, the Brazilian Environmental Council (CONAMA) promulgates regulations regarding the concentrations of given compounds that are supposed to be safe for aquatic life. Considering these regulations, this study tested the effects of considered safe levels of lithium (2.5 mgL-1) and selenium (0.01 mgL-1), isolated and mixed, on the American bullfrog (Lithobates catesbeianus) tadpoles. The evaluation was done through the use of biomarkers of larval development as total wet weight (TWW), snout-vent-length (SVL), hind-limb-length (HLL), activity level (AL), histologic evaluation of the thyroid gland and the mortality rate. The tadpoles were allocated into four groups (n = 20 each): a control group (CT); a group exposed to lithium (LI), a group exposed to selenium (SE), and a group exposed to both lithium and selenium (SELI). The whole assay was carried out over 21 days, with two rounds of data collection (on 7th and 21st day) to evaluate the responses over time. A statistical reduction in the AL was observed in the tadpoles from the LI and SELI groups after 7 days of exposure, the same pattern was observed after 21 days. Histological analyses of the thyroid gland showed signs of up-regulation (i.e. statistic reduction in number and area of the follicles, as well a significant reduction in the area of the gland) in all exposed groups, which represents an endocrine response as an adaptative strategy to deal with polluted aquatic environment. The stress triggered by the polluted medium is discussed.


Assuntos
Lítio/toxicidade , Metamorfose Biológica/efeitos dos fármacos , Rana catesbeiana/fisiologia , Selênio/toxicidade , Poluentes Químicos da Água/toxicidade , Aceleração , Animais , Bioensaio , Brasil , Poluentes Ambientais , Larva/fisiologia , Metamorfose Biológica/fisiologia , Glândula Tireoide , Estados Unidos
6.
Methods Mol Biol ; 2219: 49-68, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33074533

RESUMO

Here we describe methods for (a) collecting starfish during their breeding period; (b) maintaining adults with fully grown gonads in laboratory aquaria; (c) rearing fertilized eggs to brachiolaria larvae, and (d) inducing larvae to metamorphose into juveniles under laboratory conditions. Such protocols should facilitate various analyses of starfish development throughout the entire life cycle of these model organisms.


Assuntos
Asterina/crescimento & desenvolvimento , Animais , Aquicultura/instrumentação , Aquicultura/métodos , Asterina/embriologia , Desenho de Equipamento , Feminino , Larva/crescimento & desenvolvimento , Masculino , Metamorfose Biológica , Oócitos/citologia , Oogênese
7.
Sci Total Environ ; 762: 144170, 2021 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-33360465

RESUMO

Triclosan (TCS) is widely used as an antibacterial agent, but its residue in the environment poses a great threat. In this study, Drosophila melanogaster were treated with series concentrations of TCS and the effects on development, behavior, reproduction, and oxidative stress indicators were investigated. The results showed that high concentrations of TCS severely interfered with the metamorphosis, resulting in lower hatching rate and longer development time. The hatching rate was only 75.00% ± 4.08% in 0.80 mg/mL TCS group. TCS also showed dose-dependent damage to the fertility of flies, causing ovarian defects and decreased the number of offspring. Almost no offspring adults hatched when exposed to high concentrations of TCS (0.50 and 0.80 mg/mL), and the hatching rate was 0% in 0.80 mg/mL TCS group. Larvae crawling, adult climbing and anti-starvation ability were also affected to varying degrees and showed hormesis. TCS could damage larval intestinal cells in a dose-dependent manner, and injury was lightened with culture time prolonging to 30 h. It is noteworthy that TCS caused redox imbalance with an increase on catalase (CAT) activity and decrease on reactive oxygen species (ROS) level. Our results conclude that TCS elicits multiple impacts on Drosophila and its rational use should be strengthened.


Assuntos
Triclosan , Animais , Drosophila melanogaster , Larva , Metamorfose Biológica , Reprodução , Triclosan/toxicidade
8.
Biol Bull ; 239(3): 153-163, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-33347800

RESUMO

AbstractIn the ophioplutei of brittle stars, the posterior coeloms are commonly assumed to be produced by a transverse fission of the initially formed coeloms; but in ophioplutei of Ophiopholis aculeata, the posterior coeloms first appear separately as aggregations of mesenchyme-like cells near the base of the posterolateral arms. Initiation of posterior coeloms was similar in ophioplutei of another family and may be similar in diverse ophiuroids. Initiation is easily missed without frequent observations. Early interpretations that diagrammed a fission of the first-formed coeloms appear to have influenced later authors for more than a century. Growth of posterior coeloms from a small initial size facilitated observations of developmental plasticity in growth of coeloms relative to that of larval arms. This plasticity, as observed in echinoplutei of echinoids, is relatively greater growth of a ciliary band for food capture when food is scarce and relatively greater growth of juvenile structures that will function after metamorphosis when food is abundant; however, juvenile structures develop extensively as a rudiment within the echinopluteus prior to settlement and metamorphosis, whereas in ophioplutei there is little development of juvenile structures until metamorphosis. In ophioplutei there is, therefore, less scope for shifting growth to structures that gain function after metamorphosis. Nevertheless, we found that when ophioplutei were at higher concentrations of food, the growth of the posterior coeloms was greater relative to the growth of the larval arms. Developmental plasticity in allocation of growth to larval and postlarval equipment can occur despite disparate patterns of development.


Assuntos
Equinodermos , Metamorfose Biológica , Animais , Larva
10.
PLoS One ; 15(8): e0237737, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32822355

RESUMO

Individual growth rates are intrinsically related to survival and lifetime reproductive success and hence, are key determinants of population growth. Efforts to quantify age-size relationships are hampered by difficulties in aging individuals in wild populations. In addition, species with complex life-histories often show distinct shifts in growth that cannot be readily accommodated by traditional modelling techniques. Amphibians are often characterized by rapid larval growth, cessation of growth prior to metamorphosis, and resumption of growth in the adult stage. Compounding issues of non-linear growth, amphibian monitoring programs typically sample larval and adult populations using dissimilar methods. Here we present the first multistage growth model that combines disparate data collected across life-history stages. We model the growth of the endangered Reticulated Flatwoods Salamander, Ambystoma bishopi, in a Bayesian framework, that accounts for unknown ages, individual heterogeneity, and reconciles dip-net and drift fence sampling designs. Flatwoods salamanders achieve 60% of growth in the first 3 months of life but can survive for up to 13 years as a terrestrial adult. We find evidence for marked variability in growth rate, the timing and age at metamorphosis, and maximum size, within populations. Average size of metamorphs in a given year appeared strongly dependent on hydroperiod, and differed by >10mm across years with successful recruitment. In contrast, variation in the sizes of emerging metamorphs appeared relatively constant across years. An understanding of growth will contribute to the development of population viability analyses for flatwoods salamanders, will guide management actions, and will ultimately aid the recovery of the species. Our model formulation has broad applicability to amphibians, and likely any stage-structured organism in which homogenous data cannot be collected across life-stages. The tendency to ignore stage-structure or omit non-conforming data in growth analyses can no longer be afforded given the high stakes of management decisions, particularly for endangered or at-risk populations.


Assuntos
Ambystoma/crescimento & desenvolvimento , Urodelos/crescimento & desenvolvimento , Animais , Tamanho Corporal , Espécies em Perigo de Extinção , Larva/crescimento & desenvolvimento , Metamorfose Biológica , Modelos Biológicos
11.
PLoS Genet ; 16(8): e1008942, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32764744

RESUMO

To remodel functional neuronal connectivity, neurons often alter dendrite arbors through elimination and subsequent regeneration of dendritic branches. However, the intrinsic mechanisms underlying this developmentally programmed dendrite regeneration and whether it shares common machinery with injury-induced regeneration remain largely unknown. Drosophila class IV dendrite arborization (C4da) sensory neurons regenerate adult-specific dendrites after eliminating larval dendrites during metamorphosis. Here we show that the microRNA miR-87 is a critical regulator of dendrite regeneration in Drosophila. miR-87 knockout impairs dendrite regeneration after developmentally-programmed pruning, whereas miR-87 overexpression in C4da neurons leads to precocious initiation of dendrite regeneration. Genetic analyses indicate that the transcriptional repressor Tramtrack69 (Ttk69) is a functional target for miR-87-mediated repression as ttk69 expression is increased in miR-87 knockout neurons and reducing ttk69 expression restores dendrite regeneration to mutants lacking miR-87 function. We further show that miR-87 is required for dendrite regeneration after acute injury in the larval stage, providing a mechanistic link between developmentally programmed and injury-induced dendrite regeneration. These findings thus indicate that miR-87 promotes dendrite regrowth during regeneration at least in part through suppressing Ttk69 in Drosophila sensory neurons and suggest that developmental and injury-induced dendrite regeneration share a common intrinsic mechanism to reactivate dendrite growth.


Assuntos
Proteínas de Drosophila/genética , Metamorfose Biológica/genética , MicroRNAs/genética , Regeneração Nervosa/genética , Proteínas Repressoras/genética , Animais , Dendritos/genética , Dendritos/fisiologia , Drosophila melanogaster/genética , Regulação da Expressão Gênica no Desenvolvimento , Larva/genética , Larva/crescimento & desenvolvimento , Células Receptoras Sensoriais/metabolismo
12.
Oecologia ; 193(4): 879-888, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32740730

RESUMO

Size thresholds commonly underlie the induction of alternative morphological states. However, the respective importance of absolute and relative size to such thresholds remains uncertain. If absolute size governs expression, morph frequency should differ among environments that influence absolute sizes (e.g. resources, competition), and individuals of the same morph should have similar average sizes across environments. If relative size determines expression, the frequency of each morph may not differ among environments, but morphs within each environment should differ in size relative to one another. We tested these predictions in a salamander (Ambystoma talpoideum) that develops into either a terrestrial metamorph or an aquatic paedomorph. To generate size variation within and among environments, we reared individuals in mesocosm ponds across three conspecific densities. We found that morph frequency did not differ among density treatments, and the morphs were not similarly sized within each density treatment. Instead, within each environment, relatively larger individuals became metamorphs and relatively smaller individuals became paedomorphs. Relative size therefore determined morph development, highlighting the importance of an individual's social context to size-dependent morph induction.


Assuntos
Ambystoma , Urodelos , Ambystomatidae , Animais , Larva , Metamorfose Biológica
13.
Oecologia ; 193(3): 749-759, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32654046

RESUMO

Climate change is creating warmer, earlier springs, which are causing the phenology of many organisms to shift. Additionally, as temperatures increase, the body size of many ectotherms is decreasing. However, phenological and body size shifts are not occurring at the same rates across species, even in species that live in close proximity or have similar life history. Differing rates of phenological and body-size shifts may affect ecological interactions. We investigated whether shifts in phenology and body size had a predictable effect on interspecific competition. We tested three hypotheses. First, priority effects would indicate early arriving organisms gain a competitive advantage. Second, larger organisms would be competitively superior. Third, similarly sized organisms would compete more strongly. We manipulated aquatic larval conditions to create variation in wood frog (Rana sylvatica) size at and date of metamorphosis. Wood frogs were placed in terrestrial enclosures with unmanipulated juvenile American toads (Anaxyrus americanus) where we tracked amphibian growth over 3 months. Consistent with the size superiority hypothesis, initially smaller wood frogs did not compete as strongly with toads. However, the results of the phenological shift were the opposite of our priority effects prediction: early arrival by frogs increased toad mass. Our results could indicate that toads would experience fewer negative effects of competition with wood frogs that metamorphose earlier and smaller under climate change. Our study highlights the challenges of predicting how climate change will affect interspecific interactions and emphasizes the need to investigate the role of shifts in both phenology and body size.


Assuntos
Mudança Climática , Metamorfose Biológica , Animais , Tamanho Corporal , Bufonidae , Ranidae , Estações do Ano
14.
Proc Natl Acad Sci U S A ; 117(32): 19347-19358, 2020 08 11.
Artigo em Inglês | MEDLINE | ID: mdl-32723830

RESUMO

Bacterial intracellular symbiosis (endosymbiosis) is widespread in nature and impacts many biological processes. In holometabolous symbiotic insects, metamorphosis entails a complete and abrupt internal reorganization that creates a constraint for endosymbiont transmission from larvae to adults. To assess how endosymbiosis copes-and potentially evolves-throughout this major host-tissue reorganization, we used the association between the cereal weevil Sitophilus oryzae and the bacterium Sodalis pierantonius as a model system. S. pierantonius are contained inside specialized host cells, the bacteriocytes, that group into an organ, the bacteriome. Cereal weevils require metabolic inputs from their endosymbiont, particularly during adult cuticle synthesis, when endosymbiont load increases dramatically. By combining dual RNA-sequencing analyses and cell imaging, we show that the larval bacteriome dissociates at the onset of metamorphosis and releases bacteriocytes that undergo endosymbiosis-dependent transcriptomic changes affecting cell motility, cell adhesion, and cytoskeleton organization. Remarkably, bacteriocytes turn into spindle cells and migrate along the midgut epithelium, thereby conveying endosymbionts to midgut sites where future mesenteric caeca will develop. Concomitantly, endosymbiont genes encoding a type III secretion system and a flagellum apparatus are transiently up-regulated while endosymbionts infect putative stem cells and enter their nuclei. Infected cells then turn into new differentiated bacteriocytes and form multiple new bacteriomes in adults. These findings show that endosymbiosis reorganization in a holometabolous insect relies on a synchronized host-symbiont molecular and cellular "choreography" and illustrates an adaptive feature that promotes bacteriome multiplication to match increased metabolic requirements in emerging adults.


Assuntos
Enterobacteriaceae/fisiologia , Simbiose , Gorgulhos/crescimento & desenvolvimento , Gorgulhos/microbiologia , Animais , Fenômenos Fisiológicos Bacterianos , Evolução Biológica , Sistema Digestório/microbiologia , Endófitos/genética , Endófitos/isolamento & purificação , Endófitos/fisiologia , Enterobacteriaceae/genética , Enterobacteriaceae/isolamento & purificação , Feminino , Larva/crescimento & desenvolvimento , Larva/microbiologia , Larva/fisiologia , Masculino , Metamorfose Biológica , Gorgulhos/fisiologia
15.
Gene ; 760: 144998, 2020 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-32717304

RESUMO

The life cycle of holometabolous insects involves different stages and cathepsin plays an important role in insect metamorphosis. In the present study, we investigated the function of Bombyx mori cathepsin-L (Bm-CatL) during metamorphosis and analyzed their role in programmed cell death (PCD) of the fat body. The results showed that knockdown of Bm-CatL by RNA interference led to abnormal pupation and a delay in fat body degradation during metamorphosis. Furthermore, PCD inhibition was observed in the fat body after downregulation of Bm-CatL. To confirm this finding, PCD was induced in Bombyx mori embryonic (BmE) cells by ultraviolet ray irradiation. We found that the PCD of BmE cells was weakened after knocking down Bm-CatL. Moreover, overexpression of Bm-CatL in cells promoted PCD. Overall, our results showed that Bm-CatL is involved in the degradation of internal tissues and promotes the PCD of cells involved in the pupation of silkworms. Thus, this study provides us with a better understanding for function of cathepsin-L during metamorphosis.


Assuntos
Bombyx/fisiologia , Catepsina L/metabolismo , Tecido Adiposo/metabolismo , Animais , Apoptose/fisiologia , Bombyx/genética , Bombyx/metabolismo , Corpo Adiposo/metabolismo , Proteínas de Insetos/metabolismo , Metamorfose Biológica , Interferência de RNA
16.
BMC Evol Biol ; 20(1): 79, 2020 06 29.
Artigo em Inglês | MEDLINE | ID: mdl-32600301

RESUMO

BACKGROUND: Metamorphosis remains one of the most complicated and poorly understood processes in insects. This is particularly so for the very dynamic transformations that take place within the pupal sheath of holometabolous insects. Only few studies address these transformations especially with regard to cranial structures of those holometabolous species where the larval and adult forms have a similar diet. It thus remains unclear to what extent the internal structures undergo histolysis and rebuilding. Here, the development of the brain and skeleto-muscular system of the head of Chrysopa pallens (Rambur, 1838) is studied. This species is a predator of aphids in the larval and adult stage. RESULTS: We used micro-computed-tomography (µ-CT) to study the transformations of the larval, prepupal and pupal head within the cocoon. We first assessed the morphological differences and similarities between the stages. We then determined the point in time when the compound eyes appear and describe the re-orientation of the head capsule which transforms the prognathous larva into a hypognathous adult. The internal head muscles are distinctly more slender in larvae than adults. In addition, the adults have a significantly larger brain which is likely needed for the processing of the signals obtained by the adults vastly expanded sensory organs that are presumably needed for dispersal and mating. Our study shows that the histolysis and modification of the inner muscles and skeletal elements take place within the prepupa. The central nervous system persists throughout metamorphosis but its morphology changes significantly. CONCLUSION: Our study reveals that not only the inner structures, but also the outer morphology continues to change after the final larval moult. The adult cuticle and internal structures form gradually within the cocoon. The histolysis and rebuilding begin with the skeletal elements and is followed by changes in the central nervous system before it concludes with modifications of the musculature. This order of events is likely ancestral for Holometabola because it is also known from Hymenoptera, Diptera, Mecoptera, and Coleoptera.


Assuntos
Evolução Biológica , Cabeça/anatomia & histologia , Insetos/anatomia & histologia , Insetos/crescimento & desenvolvimento , Metamorfose Biológica , Animais , Cabeça/diagnóstico por imagem , Imageamento Tridimensional , Larva/anatomia & histologia , Larva/crescimento & desenvolvimento , Músculos/anatomia & histologia , Pupa/anatomia & histologia , Pupa/crescimento & desenvolvimento , Tomografia Computadorizada por Raios X
17.
Nat Commun ; 11(1): 3614, 2020 07 17.
Artigo em Inglês | MEDLINE | ID: mdl-32681015

RESUMO

Larval metamorphosis and recruitment represent critical life-history transitions for most teleost fishes. While the detrimental effects of anthropogenic stressors on the behavior and survival of recruiting fishes are well-documented, the physiological mechanisms that underpin these patterns remain unclear. Here, we use pharmacological treatments to highlight the role that thyroid hormones (TH) play in sensory development and determining anti-predator responses in metamorphosing convict surgeonfish, Acanthurus triostegus. We then show that high doses of a physical stressor (increased temperature of +3 °C) and a chemical stressor (the pesticide chlorpyrifos at 30 µg L-1) induced similar defects by decreasing fish TH levels and affecting their sensory development. Stressor-exposed fish experienced higher predation; however, their ability to avoid predation improved when they received supplemental TH. Our results highlight that two different anthropogenic stressors can affect critical developmental and ecological transitions via the same physiological pathway. This finding provides a unifying mechanism to explain past results and underlines the profound threat anthropogenic stressors pose to fish communities.


Assuntos
Peixes/crescimento & desenvolvimento , Larva/crescimento & desenvolvimento , Praguicidas/toxicidade , Glândula Tireoide/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Animais , Clorpirifos/toxicidade , Poluição Ambiental/efeitos adversos , Metamorfose Biológica/efeitos dos fármacos , Estresse Fisiológico/efeitos dos fármacos , Glândula Tireoide/metabolismo , Hormônios Tireóideos/metabolismo
18.
Hist Philos Life Sci ; 42(3): 31, 2020 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-32676894

RESUMO

Several problems with Hegel's conception of the organism in the Encyclopaedia are due to the separation between individual life in Nature and the universal life of the Concept. This discontinuity between ontogenesis and phylogenesis in his dialectics of organic life will be studied here by following his presentation of physiological development, especially reproduction, and by reconstructing the historical model he criticizes-Leibniz's organic machines and their development in Buffon's Natural History-a model that was also of crucial importance to the philosophy of nature of Schelling and his followers.


Assuntos
Metamorfose Biológica , História Natural/história , Reprodução , Evolução Biológica , História do Século XVIII , História do Século XIX
19.
Mar Environ Res ; 159: 104977, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32662430

RESUMO

Extensive research has shown that the early life stages of marine organisms are sensitive to ocean acidification (OA). Less is known, however, on whether larval settlement and metamorphosis may be affected, or by which mechanisms. These are key processes in the life cycle of most marine benthic organisms, since they mark the transition between the free swimming larval stage to benthic life. We investigated whether OA could affect the larval settlement success of the sea urchin Evechinus chloroticus, a key coastal species with ecological, economic and cultural importance in New Zealand. We performed four settlement experiments to test whether reduced seawater pH (ranging from 8.1 to 7.0, at an interval of ~0.2 pH units) alters larval settlement and metamorphosis success. Our results show that settlement success was not significantly reduced when the larvae were exposed to a range of reduced seawater pH treatments (8.1-7.0) at time of settlement (on direct effects). Similarly, when presented with crustose coralline algae (CCA) pre-conditioned in seawater pH of either pH 8.1 or 7.7 for 28 days, larval settlement success remained unaltered (on indirect effects). We conclude that competent larvae in this species are resilient to OA at time of settlement. Further research on a range of taxa that vary in settlement selectivity and behaviour is needed in order to fully understand the effects of OA on the life cycle of marine invertebrates and the consequences it might have for future coastal marine ecosystems.


Assuntos
Ecossistema , Ouriços-do-Mar , Água do Mar , Animais , Concentração de Íons de Hidrogênio , Larva , Metamorfose Biológica
20.
Nat Ecol Evol ; 4(8): 1129-1140, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32572219

RESUMO

Metamorphosis is widespread across the animal kingdom and induces fundamental changes in the morphology, habitat and resources used by an organism during its lifetime. Metamorphic species are likely to experience more dynamic selective pressures through ontogeny compared with species with single-phase life cycles, which may drive divergent evolutionary dynamics. Here, we reconstruct the cranial evolution of the salamander using geometric morphometric data from 148 species spanning the order's full phylogenetic, developmental and ecological diversity. We demonstrate that life cycle influences cranial shape diversity and rate of evolution. Shifts in the rate of cranial evolution are consistently associated with transitions from biphasic to either direct-developing or paedomorphic life cycle strategies. Direct-developers exhibit the slowest rates of evolution and the lowest disparity, and paedomorphic species the highest. Species undergoing complete metamorphosis (biphasic and direct-developing) exhibit greater cranial modularity (evolutionary independence among regions) than do paedomorphic species, which undergo differential metamorphosis. Biphasic and direct-developing species also display elevated disparity relative to the evolutionary rate for bones associated with feeding, whereas this is not the case for paedomorphic species. Metamorphosis has profoundly influenced salamander cranial evolution, requiring greater autonomy of cranial elements and facilitating the rapid evolution of regions that are remodelled through ontogeny. Rather than compounding functional constraints on variation, metamorphosis seems to have promoted the morphological evolution of salamanders over 180 million years, which may explain the ubiquity of this complex life cycle strategy across disparate organisms.


Assuntos
Metamorfose Biológica , Urodelos , Animais , Estágios do Ciclo de Vida , Filogenia , Crânio , Urodelos/genética
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