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1.
Development ; 148(18)2021 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-34344024

RESUMO

How dermis maintains tissue homeostasis in cyclic growth and wounding is a fundamental unsolved question. Here, we study how dermal components of feather follicles undergo physiological (molting) and plucking injury-induced regeneration in chickens. Proliferation analyses reveal quiescent, transient-amplifying (TA) and long-term label-retaining dermal cell (LRDC) states. During the growth phase, LRDCs are activated to make new dermal components with distinct cellular flows. Dermal TA cells, enriched in the proximal follicle, generate both peripheral pulp, which extends distally to expand the epithelial-mesenchymal interactive interface for barb patterning, and central pulp, which provides nutrition. Entering the resting phase, LRDCs, accompanying collar bulge epidermal label-retaining cells, descend to the apical dermal papilla. In the next cycle, these apical dermal papilla LRDCs are re-activated to become new pulp progenitor TA cells. In the growth phase, lower dermal sheath can generate dermal papilla and pulp. Transcriptome analyses identify marker genes and highlight molecular signaling associated with dermal specification. We compare the cyclic topological changes with those of the hair follicle, a convergently evolved follicle configuration. This work presents a model for analyzing homeostasis and tissue remodeling of mesenchymal progenitors.


Assuntos
Galinhas/fisiologia , Derme/fisiologia , Células Epidérmicas/fisiologia , Plumas/fisiologia , Folículo Piloso/fisiologia , Regeneração/fisiologia , Células-Tronco/fisiologia , Animais , Diferenciação Celular/fisiologia , Proliferação de Células/fisiologia , Cabelo/fisiologia , Muda/fisiologia , Transdução de Sinais/fisiologia
2.
Proc Natl Acad Sci U S A ; 118(27)2021 07 06.
Artigo em Inglês | MEDLINE | ID: mdl-34183412

RESUMO

The daily rhythm of adult emergence of holometabolous insects is one of the first circadian rhythms to be studied. In these insects, the circadian clock imposes a daily pattern of emergence by allowing or stimulating eclosion during certain windows of time and inhibiting emergence during others, a process that has been described as "gating." Although the circadian rhythm of insect emergence provided many of the key concepts of chronobiology, little progress has been made in understanding the bases of the gating process itself, although the term "gating" suggests that it is separate from the developmental process of metamorphosis. Here, we follow the progression through the final stages of Drosophila adult development with single-animal resolution and show that the circadian clock imposes a daily rhythmicity to the pattern of emergence by controlling when the insect initiates the final steps of metamorphosis itself. Circadian rhythmicity of emergence depends on the coupling between the central clock located in the brain and a peripheral clock located in the prothoracic gland (PG), an endocrine gland whose only known function is the production of the molting hormone, ecdysone. Here, we show that the clock exerts its action by regulating not the levels of ecdysone but that of its actions mediated by the ecdysone receptor. Our findings may also provide insights for understanding the mechanisms by which the daily rhythms of glucocorticoids are produced in mammals, which result from the coupling between the central clock in the suprachiasmatic nucleus and a peripheral clock located in the suprarenal gland.


Assuntos
Envelhecimento/fisiologia , Relógios Circadianos/fisiologia , Drosophila melanogaster/crescimento & desenvolvimento , Drosophila melanogaster/fisiologia , Metamorfose Biológica/fisiologia , Animais , Ecdisona/metabolismo , Modelos Biológicos , Muda/fisiologia , Receptores de Esteroides/metabolismo , Transdução de Sinais , Fatores de Tempo , Asas de Animais/fisiologia
3.
Sci Rep ; 11(1): 13331, 2021 06 25.
Artigo em Inglês | MEDLINE | ID: mdl-34172785

RESUMO

Phenological shifts are among the most obvious biological responses to environmental change, yet documented responses for Southern Ocean marine mammals are extremely rare. Marine mammals can respond to environmental changes through phenological flexibility of their life-history events such as breeding and moulting. Southern elephant seals (Mirounga leonina) undergo an obligatory annual moult which involves the rapid shedding of epidermal skin and hair while seals fast ashore. We quantified the timing (phenology) and duration (the time from arrival ashore to departure) of the moult haulout of 4612 female elephant seals at Marion Island over 32 years. Using linear mixed-effects models, we investigated age, breeding state and environmental drivers of moult timing and haulout duration. We found no clear evidence for a temporal shift in moult phenology or its duration. Annual variation in moult arrival date and haulout duration was small relative to age and breeding effects, which explained more than 90% of the variance in moult arrival date and 25% in moult haulout duration. All environmental covariates we tested explained minimal variation in the data. Female elephant seals moulted progressively later as juveniles, but adults age 4 and older had similar moult start dates that depended on the breeding state of the female. In contrast, moult haulout duration was not constant with age among adults, but instead became shorter with increasing age. Moulting is energetically expensive and differences in the moult haulout duration are possibly due to individual variation in body mass and associated metabolizable energy reserves, although other drivers (e.g. hormones) may also be present. Individual-based data on moult arrival dates and haulout duration can be used as auxiliary data in demographic modelling and may be useful proxies of other important biological parameters such as body condition and breeding history.


Assuntos
Muda/fisiologia , Focas Verdadeiras/fisiologia , Animais , Cruzamento/métodos , Feminino
4.
J Insect Physiol ; 132: 104262, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-34029609

RESUMO

Moulting is a cornerstone of arthropods development. It can be determined by numerous factors such as body mass, temperature, and immunity. However, the effects of these factors can be dependent on each other, so that it is often difficult to predict whether and how they shape moulting, and whether their effects are additive or interactive. In this study, we addressed these questions by testing the effects of body mass, ambient temperature, fungal infection and their interaction on intermoult duration and survival in starved juveniles of the European earwig Forficula auricularia. We recorded the date of moult and death of a total of 207 earwig juveniles that were weighed, exposed to different doses of the entomopathogenic fungus Metarizium brunneum and then maintained at either 20 °C or 24 °C. Our results first reveal that juveniles moulted earlier when they were heavy compared to light on the day of exposure, as well as earlier when maintained at 24 °C compared to 20 °C. By contrast, pathogen exposure did not affect the moulting date. We also found that nymphs died faster when they were light compared to heavy on the day of exposure, when they were exposed to high (106 and 107 spores/ml) compared to low (104, 105 and 0 spores/ml) pathogen concentrations, and when they were maintained at 24 °C compared to 20 °C. We detected no sign of interaction between temperature, fungal infection and body mass on both moulting and survival. Overall, these findings shed light on the limited importance of infection on moulting in starved juveniles, and reveal that weight, temperature, and infection have additive effects on their survival. More generally, this study emphasizes that the three tested factors do not necessarily interact to shape key physiological processes in an insect.


Assuntos
Insetos , Muda/fisiologia , Animais , Tamanho Corporal , Insetos/crescimento & desenvolvimento , Insetos/microbiologia , Insetos/fisiologia , Metarhizium , Micoses , Temperatura
5.
Physiol Biochem Zool ; 94(3): 152-161, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33710938

RESUMO

AbstractHarbor seals (Phoca vitulina) live in cold temperate or polar seas and molt annually, renewing their fur over a period of approximately 4 wk. Epidermal processes at this time require a warm skin; therefore, to avoid an excessive energy cost at sea during the molt, harbor seals and many other pinnipeds increase the proportion of time they are hauled out on land. We predicted that metabolic rate during haul-out would be greater during the molt to sustain an elevated skin temperature in order to optimize skin and hair growth. To examine this, we measured post-haul-out oxygen consumption (V˙O2) in captive harbor seals during molt and postmolt periods. We recorded greater V˙O2 of seals while they were molting than when the molt was complete. Post-haul-out V˙O2 increased faster and reached a greater maximum during the first 40 min. Thereafter, V˙O2 decreased but still remained greater, suggesting that while metabolic rate was relatively high throughout haul-outs, it was most pronounced in the first 40 min. Air temperature, estimated heat increment of feeding, and mass also explained 15.5% of V˙O2 variation over 180 min after haul-out, suggesting that the environment, feeding state, and body size influenced the metabolic rate of individual animals. These results show that molting seals have greater metabolic rates when hauled out, especially during the early stages of the haul-out period. As a consequence, human disturbance that changes the haul-out behavior of molting seals will increase their energy costs and potentially extend the duration of the molt.


Assuntos
Metabolismo Energético/fisiologia , Muda/fisiologia , Phoca/fisiologia , Animais , Comportamento Alimentar , Masculino , Consumo de Oxigênio/fisiologia , Estações do Ano
6.
Dev Biol ; 473: 71-79, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-33571487

RESUMO

Metamorphic transition in some tenebrionid beetles is dependent on population density. This phenomenon is useful for pupae that are vulnerable to cannibalism. The physiological mechanism of this adaptive developmental phenomenon remains unclear. In Zophobas atratus, which show density-dependent metamorphosis, larval isolation can induce metamorphosis. We herein demonstrated that the return of isolated larvae to a crowded condition (re-crowding) inhibited their metamorphosis. The timing of metamorphic initiation was slightly extended according to the duration of re-crowding experienced by the isolated larvae. Therefore, the re-crowding induced physiological changes needed for metamorphic inhibition. We investigated whether hormone-related genes involved in signaling of metamorphic inhibitor (juvenile hormone, JH) and molting hormone (ecdysteroid) responded to the re-crowding. An expression analysis showed that gene expression of ecdysteroid signaling was maintained at low levels under the re-crowded condition. Actually, ecdysteroid levels decreased responding to re-crowding. Ecdysteroid injections induced metamorphosis in re-crowded larvae. In contrast, the JH signaling gene showed little fluctuation in both isolated and re-crowded conditions, and knockdown of JH signaling factors did not affect inhibition of metamorphosis under the re-crowded condition. The present study suggests that regulation of ecdysteroid level rather than JH is more crucial in the density dependent metamorphosis in Z. atratus.


Assuntos
Ecdisteroides/metabolismo , Ecdisteroides/fisiologia , Metamorfose Biológica/fisiologia , Animais , Besouros/metabolismo , Regulação da Expressão Gênica no Desenvolvimento/genética , Proteínas de Insetos/genética , Larva/metabolismo , Muda/fisiologia , Densidade Demográfica , Pupa/metabolismo , Tenebrio/metabolismo
7.
PLoS One ; 16(1): e0236536, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33444336

RESUMO

Oxygen, hydrogen, carbon and nitrogen stable isotopes were measured on a comprehensive sampling of feathers from two spring Hooded Warblers (Setophaga citrina) in Texas to evaluate isotopic variability between feathers and during molt. Isotopic homogeneity within each bird was found across all four isotopic systems, supporting the hypothesis that molt in these neotropical migrants is fully completed on the breeding grounds. This homogeneity suggests that the isotopic composition of a single feather is may be representative of the whole songbird. However, each bird was found to have one or two outlier feathers, which could signify regrowth of lost feathers after prebasic molt.


Assuntos
Plumas/química , Plumas/fisiologia , Isótopos/química , Passeriformes/fisiologia , Aves Canoras/fisiologia , Migração Animal/fisiologia , Animais , Geografia/métodos , Muda/fisiologia , Estações do Ano , Texas
8.
Arthropod Struct Dev ; 61: 101013, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33517027

RESUMO

It has been a traditionally held view that winged insects stop molting after they reach adulthood. We observed a fascinating phenomenon of a post-imago molt occurring in the neotenic females of a firefly species in Taiwan over the last two years. By rearing Lamprigera minor larvae to adults, four out of the five unmated females studied were found undergoing an extra molt 8-18 days after adult eclosion. They were reproductively mature when the post-imago molt occurred, as evidenced by the eggs inside their bodies. The four females died without oviposition whereas the only normal female laid eggs. A comparison of exuviae of different stages confirmed the existence of post-imago ecdysis. The adult skin differed from the pupal one mainly in the mouthparts and leg structures. No mix of pupal and adult traits was seen in the adult skin. The females retained the same morphology after the extra molt. A close examination of the post-imago molting females revealed that their oviduct openings were all blocked by larval or pupal skin and thus unable to lay eggs. The reproductive stress may invoke an endocrine disorder and lead to an extra molt. We propose that L. minor females retain their prothoracic glands even as adults, allowing them to molt as adults under certain environmental or physiological conditions. Thus, neoteny of L. minor is reflected in both the external morphology as well as the internal physiology. The possible developmental changes associated with the evolution of neoteny are discussed.


Assuntos
Vaga-Lumes , Muda , Animais , Sistema Endócrino/fisiologia , Feminino , Vaga-Lumes/crescimento & desenvolvimento , Muda/fisiologia , Estresse Fisiológico
9.
Vet Res ; 52(1): 6, 2021 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-33413587

RESUMO

Inorganic pyrophosphatase (PPase) participates in energy cycle and plays a vital role in hydrolysis of inorganic pyrophosphate (PPi) into inorganic phosphate (Pi). The aim of this study was to investigate the biological properties of a Trichinella spiralis PPase (TsPPase) and its role in larval molting and developmental process. The predicted TsPPase consisted of 367 amino acids with a molecular mass of 41.48 kDa and a pI of 5.76. Amino acid sequence alignment and phylogenetic analysis showed that the TsPPase gene encodes a functional family I soluble PPase with the same characteristics as prokaryotic, plant and animal/fungal soluble PPase. The rTsPPase was expressed and purified, it has the activity to catalyze the hydrolysis of PPi to Pi, and the activity was dependent on Mg2+, pH and temperature. The enzymatic activity of rTsPPase was significantly inhibited after its metal binding sites mutation. TsPPase was transcribed and expressed in all T. spiralis phases, especially in muscle larvae (ML) and intestinal infective larvae (IIL). Immunofluorescence assay (IFA) revealed that TsPPase was mainly located in cuticle and stichosome. When the ML and IIL were treated with TsPPase-specific siRNA-279, TsPPase expression and enzymatic activity were obviously reduced, the larval molting and development were also impeded. Intestinal IIL as well as AW burden, IIL molting rates from mice infected with siRNA-treated ML were obviously suppressed. The results indicated that rTsPPase possesses the enzymatic activity of native inorganic pyrophosphatase, and TsPPase plays an important role in development and molting process of intestinal T. spiralis larval stages.


Assuntos
Pirofosfatase Inorgânica/fisiologia , Trichinella spiralis/crescimento & desenvolvimento , Animais , Western Blotting , Eletroforese em Gel de Poliacrilamida , Feminino , Imunofluorescência , Pirofosfatase Inorgânica/genética , Pirofosfatase Inorgânica/metabolismo , Larva , Camundongos , Camundongos Endogâmicos BALB C , Muda/fisiologia , Mutagênese Sítio-Dirigida , Filogenia , Reação em Cadeia da Polimerase em Tempo Real , Alinhamento de Sequência , Trichinella spiralis/enzimologia , Trichinella spiralis/genética , Trichinella spiralis/fisiologia , Triquinelose/parasitologia , Triquinelose/veterinária
10.
Naturwissenschaften ; 108(1): 6, 2021 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-33415456

RESUMO

Sexual size dimorphism (SSD), commonly observed in snakes, may arise from a different growth rate between the sexes. This indicates a sex-specific resource intake that is in fact observable in free-living snakes. It is not so well known whether the sexes can express differential feeding rates under conditions unconstrained by spatial accessibility, competition, etc. Here, I studied sex-specific variation in growth, its correlate-moulting frequency, and feeding rate in a captive group of sexually dimorphic banded water snakes (Nerodia fasciata) with access to food unconstrained by predation, competition or space. I showed that the sexes did indeed differ in relative mass growth in that females grew faster than males (p = 0.02), but such differences were not apparent in the moulting rate (p = 0.19). Such differential growth was mirrored in the sex-specific feeding rate, with females ingesting a larger number of meals than males (p = 0.004). Such variation in feeding rate may be governed by an individual's energy expenditure and can be interpreted as a behavioural tendency that contributes to SSD development, independently of other behavioural characteristics. Sex-specific resource demands may drive the differential effects of increasing resource scarcity on both sexes.


Assuntos
Comportamento Alimentar/fisiologia , Muda/fisiologia , Caracteres Sexuais , Serpentes/crescimento & desenvolvimento , Animais , Tamanho Corporal/fisiologia , Feminino , Masculino
11.
Horm Behav ; 127: 104884, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33171133

RESUMO

Corticosterone affects physiology and behavior both during normal daily processes but also in response to environmental challenges and is known to mediate life history trade-offs. Many studies have investigated patterns of corticosterone production at targeted times of year, while ignoring underlying annual profiles. We aimed to understand the annual regulation of hypothalamic-pituitary-adrenal (HPA) axis function of both migrant (Zonotrichia leucophrys gambelii; n = 926) and resident (Z. l. nutalli; n = 688) subspecies of white-crowned sparrow and how it is influenced by environmental conditions - wind, precipitation, and temperature. We predicted that more dramatic seasonal changes in baseline and stress-induced corticosterone would occur in migrants to precisely time the onset of breeding and cope with environmental extremes on their arctic breeding grounds, while changes in residents would be muted as they experience a more forgiving breeding schedule and comparatively benign environmental conditions in coastal California. During the course of a year, the harshest conditions were experienced the summer breeding grounds for migrants, at which point they had higher corticosterone levels compared to residents. For residents, the winter months coincided with harshest conditions at which point they had higher corticosterone levels than migrants. For both subspecies, corticosterone tended to rise as environmental conditions became colder and windier. We found that the annual maxima in stress-induced corticosterone occurred prior to egg lay for all birds except resident females. Migrants had much higher baseline and acute stress-induced corticosterone during breeding compared to residents; where in a harsher environment the timing of the onset of reproduction is more critical because the breeding season is shorter. Interestingly, molt was the only stage within the annual cycle in which subspecies differences were absent suggesting that a requisite reduction in corticosterone may have to be met for feather growth. These data suggest that modulation of the HPA axis is largely driven by environmental factors, social cues, and their potential interactions with a genetic program.


Assuntos
Córtex Suprarrenal/fisiologia , Migração Animal/fisiologia , Estações do Ano , Pardais/fisiologia , Animais , Regiões Árticas , Corticosterona/metabolismo , Feminino , Sistema Hipotálamo-Hipofisário/fisiologia , Masculino , Muda/fisiologia , Sistema Hipófise-Suprarrenal/fisiologia , Reprodução/fisiologia , Estresse Fisiológico/fisiologia , Temperatura
12.
Insect Mol Biol ; 30(3): 241-252, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-33368728

RESUMO

In Drosophila melanogaster, ecdysis triggering hormone (ETH) is the key factor triggering ecdysis behaviour and promoting trachea clearance. However, whether ETH plays the dual roles in non-dipteran insects is unknown. In this survey, we found that Ldeth mRNA levels were positively correlated with circulating 20-hydroxyecdysone (20E) titers in Leptinotarsa decemlineata. Ingestion of an ecdysteroid agonist halofenozide or 20E stimulated the transcription of Ldeth, whereas RNA interference (RNAi) of ecdysteroidogenesis (LdPTTH or LdSHD) or 20E signalling (LdEcR, LdUSP or LdFTZ-F1) genes inhibited the expression, indicating ETH acts downstream of 20E. RNAi of Ldeth at the final instar stage impaired pupation. More than 80% of the Ldeth-depleted beetles remained as prepupae, completely wrapped in the old larval cuticles. These prepupae became withered, dried and darkened gradually, and finally died in soil. The remaining Ldeth hypomorphs pupated and emerged as abnormal adults, bearing smaller and wrinkle elytrum and hindwing. Moreover, the tracheae in the Ldeth hypomorphs were full of liquid. We accordingly proposed that the failure of trachea clearance disenabled air-swallowing after pupa-adult ecdysis and impacted wing expansion. Our results suggest that ETH plays the dual roles, initiation of ecdysis and motivation of trachea clearance, in a coleopteran.


Assuntos
Benzoatos/administração & dosagem , Besouros/crescimento & desenvolvimento , Ecdisterona/administração & dosagem , Hidrazinas/administração & dosagem , Muda/fisiologia , Interferência de RNA , Animais , Ecdisterona/antagonistas & inibidores , Inseticidas/administração & dosagem , Larva/crescimento & desenvolvimento , Pupa/crescimento & desenvolvimento
13.
Curr Biol ; 31(1): 207-213.e4, 2021 01 11.
Artigo em Inglês | MEDLINE | ID: mdl-33125864

RESUMO

Ecdysis or molting evolved ∼535 mya in Ecdysozoa, the most diverse and species-rich animal superphylum.1 A cascade of ecdysis-related neuropeptides (ERNs) controls the innate behavioral programs required for cuticle shedding in some ecdysozoan lineages (e.g., arthropods)2-12 but is lacking in others (e.g., nematodes).13 We recently reported on the surprisingly ancient bilaterian origin of key ERNs, such as eclosion hormone (EH), crustacean cardioactive neuropeptide (CCAP), myoinhibitory peptide (MIP), bursicon alpha (Bursα), and bursicon beta (Bursß).13,14 Thus, ERNs far predate the emergence of ecdysis, but the question as to their ancestral functions remains unresolved. Here, we compare the ERN toolkits and temporal expression profiles of six ecdysozoans (tardigrades, crustaceans, and insects), eight lophotrochozoans (planarians, annelids, and mollusks), and five deuterostomes (crinoids, sea urchins, and hemichordates). Our results show that the major, coordinated upregulation of ERNs always coincides with a transition between key life history stages, such as hatching in direct developers and metamorphosis in indirect developers. This implies that ERNs already played an ancestral role in the switch from embryonic or larval ontogeny to juvenile maturation in the last common ancestor of Nephrozoa. Consequently, the transcriptional signature of invertebrate life cycle transitions presented here was already in place in the Precambrian and was only secondarily co-opted into regulating the molting process at the dawn of Ecdysozoa.


Assuntos
Evolução Biológica , Estágios do Ciclo de Vida/fisiologia , Muda/fisiologia , Neuropeptídeos/metabolismo , Animais
14.
Commun Biol ; 3(1): 745, 2020 12 08.
Artigo em Inglês | MEDLINE | ID: mdl-33293660

RESUMO

Modern flying birds molt to replace old and worn feathers that inhibit flight performance, but its origins are unclear. We address this by presenting and evaluating a ~150 million year old record of molting in a feathered dinosaur from the early bird Archaeopteryx. Laser-Stimulated Fluorescence revealed feather sheaths that are otherwise invisible under white light. These are separated by one feather and are not in numerical sequential order and are mirrored in both wings. This indicates that a sequential center-out molting strategy was already present at the origins of flight, which is used in living falcons to preserve maximum flight performance. This strategy would have been a welcome advantage for early theropod flyers that had poor flight capabilities. This discovery provides important insights into how birds refined their early flight capabilities before the appearance of the keeled sternum, pygostyle and triosseal canal.


Assuntos
Aves/fisiologia , Plumas/fisiologia , Voo Animal/fisiologia , Fósseis , Muda/fisiologia , Animais , Evolução Biológica , Aves/genética , Muda/genética
15.
Am Nat ; 196(6): 775-784, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-33211563

RESUMO

AbstractComplex features, such as vision, limbs, and flight, have been lost by many groups of animals. Some groups of birds are more prone to loss of flight than others, but few studies have investigated possible reasons for this variation. I tested the hypothesis that a rare strategy of flight feather replacement is involved in rate variation in the evolution of flightlessness in birds. This strategy involves a simultaneous molt of the flight feathers of the wing, resulting in a temporary flightless condition during molt. I hypothesized that adaptations for this flightless period may serve as preadaptations for permanent flightlessness under conditions that favor permanent loss of flight. I found an elevated rate of loss of flight in lineages with simultaneous wing molt compared with loss of flight in lineages without simultaneous wing molt. This may indicate that birds with simultaneous molt are more prepared to adjust quickly to open niches that do not require flight, such as terrestrial niches on island habitats. These results illustrate how molt strategies can influence the long-term evolutionary trajectories of birds and provide insight into how phenotypic precursors may act as a mechanism of rate variation in the loss of complex traits.


Assuntos
Evolução Biológica , Aves/fisiologia , Voo Animal/fisiologia , Muda/fisiologia , Animais , Aves/classificação , Plumas/fisiologia , Filogenia , Asas de Animais
16.
Nat Commun ; 11(1): 6051, 2020 11 27.
Artigo em Inglês | MEDLINE | ID: mdl-33247126

RESUMO

Antarctic krill play an important role in biogeochemical cycles and can potentially generate high-particulate organic carbon (POC) fluxes to the deep ocean. They also have an unusual trait of moulting continuously throughout their life-cycle. We determine the krill seasonal contribution to POC flux in terms of faecal pellets (FP), exuviae and carcasses from sediment trap samples collected in the Southern Ocean. We found that krill moulting generated an exuviae flux of similar order to that of FP, together accounting for 87% of an annual POC flux (22.8 g m-2 y-1). Using an inverse modelling approach, we determined the krill population size necessary to generate this flux peaked at 261 g m-2. This study shows the important role of krill exuviae as a vector for POC flux. Since krill moulting cycle depends on temperature, our results highlight the sensitivity of POC flux to rapid regional environmental change.


Assuntos
Ciclo do Carbono , Carbono/metabolismo , Euphausiacea/fisiologia , Muda/fisiologia , Animais , Biomassa , Geografia , Sedimentos Geológicos/química , Oceanos e Mares , Material Particulado/análise , Dinâmica Populacional , Estações do Ano
17.
BMC Dev Biol ; 20(1): 24, 2020 11 24.
Artigo em Inglês | MEDLINE | ID: mdl-33234135

RESUMO

BACKGROUND: Molting is an essential biological process occurring characteristic times throughout the life cycle of holometabolous insects. However, it is not clear how insects determine the direction of molting to remain status quo or to initiate metamorphosis. To explore the functional factors that determine the direction of molts, liquid chromatography-mass spectrometry was used to identify the molecules involved in larval and metamorphic molting, and the differentially expressed proteins (DEPs) were compared in the two processes. RESULTS: There were 321 and 1140 DEPs identified in larval and metamorphic molting process, respectively. Bioinformatics analyses show that the amino sugar pathway was up-regulated in both processes. The up-regulated protease contributed to the metamorphosis. In addition, several proteins with different expression patterns in larval-larval and larval-pupal transitions, including Endochitinase, GRIM-19 (Genes associated with retinoid-IFN-induced mortality-19), IDE (Insulin-degrading enzyme), Sorcin (Soluble resistance related calcium binding protein), OBP (Odorant-binding protein-2 precursor), TRAP1(Tumor necrosis factor receptor associated protein-1), etc., were further identified by parallel reaction monitoring, which may play diverse functions in larval-larval and larval-pupal transitions. CONCLUSIONS: These results provide a proteomic insight into molecules involved in larval and metamorphic molts, and will likely improve the current understanding of determination of direction of molts.


Assuntos
Larva/metabolismo , Lepidópteros/metabolismo , Muda/fisiologia , Animais , Regulação da Expressão Gênica no Desenvolvimento , Proteínas de Insetos/genética , Proteínas de Insetos/metabolismo , Larva/crescimento & desenvolvimento , Lepidópteros/crescimento & desenvolvimento , Metamorfose Biológica/fisiologia , Proteômica , Pupa/crescimento & desenvolvimento , Pupa/metabolismo , Reprodutibilidade dos Testes
18.
Sci Rep ; 10(1): 18322, 2020 10 27.
Artigo em Inglês | MEDLINE | ID: mdl-33110141

RESUMO

Ecdysis, the process of extensive cell covering rearrangement, represents a remarkable physiological trait of dinoflagellates. It is involved in the regulation of the population and bloom dynamics of these microorganisms, since it is required for the formation of their thin-walled cysts. This study presents laboratory data on ecdysis in Prorocentrum cordatum, a harmful dinoflagellate species of high environmental significance. We studied external stressors triggering this process and changes in the cell ultrastructure accompanying it. Our experiments showed that mass ecdysis and formation of cysts in P. cordatum could be induced by centrifugation, temperature decrease, changes in salinity, and treatment by 2,6-dichlorobenzonitrile, whereas temperature increase, changes in pH and treatment by tetracycline did not have this effect. Obtained cysts of P. cordatum did not contain the pellicular layer and were formed in the end of the first stage of this process, i.e. removal of the plasma membrane and the outer amphiesmal vesicle membrane, whereas its second stage, removal of theca, represented excystment. Based on our findings, we conclude that such cysts can be attributed to thecate cysts and suggest P. cordatum as a promising model organism for the investigation of cellular and molecular aspects of ecdysis in dinoflagellates.


Assuntos
Dinoflagelados/fisiologia , Muda/fisiologia , Dinoflagelados/ultraestrutura , Microscopia Eletrônica de Transmissão , Estresse Fisiológico/fisiologia
19.
Zoology (Jena) ; 143: 125833, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-33059306

RESUMO

Stages of the moult cycle of the amphipod Gammarus pulex have been previously characterised based on the examination of either apolysis of the 3rd dactyl, or the whole body and eye appearance. In the current study the aim was to compare these two established moult staging techniques with a novel X-ray micro-computed tomography (micro-CT) scan method. The micro-CT provides information on the degree of calcification of the external integument and of the internal structures, such as the gastric mill. The degree of calcification is predicted to change during the moult cycle. Successful micro-CT scans were obtained from 80 G. pulex specimens and the radiological appearance of the 28 specimens immediately immersed in 4 % PFA were not different to the 52 specimens stored in 4 % PFA for at least 28 days prior to scanning. These specimens could be classified into moult stages A, B, C, early D or late D based on the degree of calcification. Good agreement was obtained between all three methods of moult stage classification if fresh specimens were used, but if specimens had been preserved in 4% Paraformaldehyde (PFA) for more than 24 hours the loss of colour from the whole body and eye meant these methods were not suitable. This is the first time that a micro-CT method has been used to study G. pulex and shows that this method of moult staging is accurate and reliable.


Assuntos
Anfípodes/fisiologia , Muda/fisiologia , Microtomografia por Raio-X/métodos , Animais
20.
Sci Rep ; 10(1): 17197, 2020 10 14.
Artigo em Inglês | MEDLINE | ID: mdl-33057047

RESUMO

In order to understand the cutaneous water loss in the desert-adapted and venomous lizard Heloderma suspectum, the microscopic structure and lipid composition of epidermal molts have been examined using microscopic, spectroscopic and chemical analysis techniques. The molt is formed by a variably thick, superficial beta-layer, an extensive mesos-region and few alpha-cells in its lowermost layers. The beta-layer contains most corneous beta proteins while the mesos-region is much richer in lipids. The proteins in the mesos-region are more unstructured than those located in the beta-layer. Most interestingly, among other lipids, high contents of cholesteryl-ß-glucoside and cholesteryl sulfate were detected, molecules absent or present in traces in other species of squamates. These cholesterol derivatives may be involved in the stabilization and compaction of the mesos-region, but present a limited permeability to water movements. The modest resistance to cutaneous water-loss of this species is compensated by adopting other physiological strategies to limit thermal damage and water transpiration as previous eco-physiological studies have indicated. The increase of steroid derivatives may also be implicated in the heat shock response, influencing the relative behavior in this desert-adapted lizard.


Assuntos
Adaptação Fisiológica/fisiologia , Colesterol/metabolismo , Epiderme/metabolismo , Metabolismo dos Lipídeos/fisiologia , Lagartos/metabolismo , Muda/fisiologia , Animais , Lipídeos , Permeabilidade , Peçonhas/metabolismo , Água/metabolismo
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