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1.
PLoS One ; 15(10): e0237201, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33119606

RESUMO

Temperature varies on a daily and seasonal scale and thermal fluctuations are predicted to become even more pronounced under future climate changes. Studies suggest that plastic responses are crucial for species' ability to cope with thermal stress including variability in temperature, but most often laboratory studies on thermal adaptation in plant and ectotherm organisms are performed at constant temperatures and few species included. Recent studies using fluctuating thermal regimes find that thermal performance is affected by both temperature mean and fluctuations, and that plastic responses likely will differ between species according to life strategy and selective past. Here we investigate how acclimation to fluctuating or constant temperature regimes, but with the same mean temperature, impact on heat stress tolerance across a plant (Arabidopsis thaliana) and two arthropod species (Orchesella cincta and Drosophila melanogaster) inhabiting widely different thermal microhabitats and with varying capability for behavioral stress avoidance. Moreover, we investigate the underlying metabolic responses of acclimation using NMR metabolomics. We find increased heat tolerance for D. melanogaster and A. thaliana exposed to fluctuating acclimation temperatures, but not for O. cincta. The response was most pronounced for A. thaliana, which also showed a stronger metabolome response to thermal fluctuations than both arthropods. Generally, sugars were more abundant across A. thaliana and D. melanogaster when exposed to fluctuating compared to constant temperature, whereas amino acids were less abundant. This pattern was not evident for O. cincta, and generally we do not find much evidence for similar metabolomics responses to fluctuating temperature acclimation across species. Differences between the investigated species' ecology and different ability to behaviorally thermoregulate may have shaped their physiological responses to thermal fluctuations.


Assuntos
Arabidopsis/crescimento & desenvolvimento , Artrópodes/crescimento & desenvolvimento , Regulação da Temperatura Corporal , Drosophila melanogaster/crescimento & desenvolvimento , Resposta ao Choque Térmico , Metaboloma , Animais , Arabidopsis/metabolismo , Artrópodes/metabolismo , Drosophila melanogaster/metabolismo , Masculino
2.
Arthropod Struct Dev ; 57: 100948, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32416473

RESUMO

Here we describe in detail the late post-embryonic development of the common European scolopendromorph centipede Cryptops parisi. Canonical variate analyses of two groups of external morphological characters, viz., cephalic capsule characters (head length, length of the anterior and posterior paramedian cephalic sutures) and coxopleuron surface characters (number of pores in the coxal pore-field, number of setae on the posterior coxopleuron edge, their number on the coxal pore-field, and their number posterior to the coxal pore-field) were conducted on a large sample of specimens collected from two localities in Serbia. Ten free-living stages are recognized: three pre-adult stages (adolescens I, II, and III) and seven adult stages (one maturus junior stage, four maturus, and two maturus senior stages). The fourth late post-embryonic stage is the first mature stage in both sexes. Sexual dimorphism in the aforementioned characters was not observed. Morphological variation of coxopleuron characters was more informative for the discrimination of developmental stages in Cryptops than the morphological variation of cephalic capsule characters.


Assuntos
Artrópodes/crescimento & desenvolvimento , Animais , Artrópodes/anatomia & histologia , Feminino , Masculino , Sérvia
3.
Arthropod Struct Dev ; 56: 100930, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32200289

RESUMO

Terrestrial arthropods often colonized and became important in freshwater ecosystems, but did so less often and with little consequence in marine habitats. This pattern cannot be explained by the physical properties of water alone or by limitations of the terrestrial arthropod body plan alone. One hypothesis is that transitions among terrestrial, aquatic and marine ecosystems are unlikely when well-adapted incumbent species in the recipient realm collectively resist entry by initially less well adapted newcomers. I evaluated and modified this hypothesis by examining the properties of donor and recipient ecosystems and the roles that insects play or do not play in each. I argue that the insularity and diminished competitiveness of most freshwater ecosystems makes them vulnerable to invasion from land and sea, and largely prevent transitions from freshwater to terrestrial and marine habitats by arthropods. Small terrestrial arthropods emphasize high locomotor performance and long-distance communication, traits that work less well in the denser, more viscous medium of water. These limitations pose particular challenges for insects colonizing highly escalated marine ecosystems, where small incumbent species rely more on passive than on active defences. Predatory insects are less constrained than herbivores, wood-borers, filter-feeders, sediment burrowers and social species.


Assuntos
Artrópodes/anatomia & histologia , Artrópodes/crescimento & desenvolvimento , Evolução Biológica , Ecossistema , Animais , Oceanos e Mares
4.
Sci Rep ; 10(1): 5572, 2020 03 27.
Artigo em Inglês | MEDLINE | ID: mdl-32221344

RESUMO

Disturbances are intrinsic drivers of structure and function in ecosystems, hence predicting their effects in forest ecosystems is essential for forest conservation and/or management practices. Yet, knowledge regarding belowground impacts of disturbance events still remains little understood and can greatly vary by taxonomic and functional identity, disturbance type and local environmental conditions. To address this gap in knowledge, we conducted a survey of soil-dwelling Protura, across forests subjected to different disturbance regimes (i.e. windstorms, insect pest outbreaks and clear-cut logging). We expected that the soil proturan assemblages would differ among disturbance regimes. We also hypothesized that these differences would be driven primarily by variation in soil physicochemical properties thus the impacts of forest disturbances would be indirect and related to changes in food resources. To verify that sampling included two geographically distant subalpine glacial lake catchments that differed in underlying geology, each having four different types of forest disturbance, i.e. control, bark beetle outbreak (BB), windthrow + BB (wind + BB) and clear-cut. As expected, forest disturbance had negative effects on proturan diversity and abundance, with multiple disturbances having the greatest impacts. However, differences in edaphic factors constituted a stronger driver of variability in distribution and abundance of proturans assemblages. These results imply that soil biogeochemistry and resource availability can have much stronger effects on proturan assemblages than forest disturbances.


Assuntos
Artrópodes/crescimento & desenvolvimento , Animais , Biodiversidade , Besouros/crescimento & desenvolvimento , Conservação dos Recursos Naturais , Ecossistema , Florestas , Lagos , Solo , Árvores/fisiologia
5.
Sci Rep ; 9(1): 17002, 2019 11 18.
Artigo em Inglês | MEDLINE | ID: mdl-31740690

RESUMO

Ecdysteroids (arthropod molting hormones) play an important role in the development and sexual maturation of arthropods, and they have been shown to have anabolic and "energizing" effect in higher vertebrates. The aim of this study was to assess ecdysteroid diversity, levels according to bird species and months, as well as to observe the molting status of hard ticks (Acari: Ixodidae) infesting the birds. Therefore, blood samples and ticks were collected from 245 birds (244 songbirds and a quail). Mass spectrometric analyses showed that 15 ecdysteroids were regularly present in the blood samples. Molting hormones biologically most active in insects (including 20-hydroxyecdysone [20E], 2deoxy-20E, ajugasterone C and dacryhainansterone) reached different levels of concentration according to bird species and season. Similarly to ecdysteroids, the seasonal presence of affected, apolytic ticks peaked in July and August. In conclusion, this study demonstrates the presence of a broad range and high concentrations of ecdysteroids in the blood stream of wild-living passerine birds. These biologically active, anabolic compounds might possibly contribute to the known high metabolic rate of songbirds.


Assuntos
Animais Selvagens/sangue , Ecdisona/sangue , Ecdisteroides/sangue , Aves Canoras/sangue , Animais , Animais Selvagens/parasitologia , Artrópodes/crescimento & desenvolvimento , Artrópodes/metabolismo , Ecdisona/química , Ecdisteroides/química , Ecdisterona/análogos & derivados , Ecdisterona/sangue , Ecdisterona/química , Ecdisterona/metabolismo , Interações Hospedeiro-Parasita , Ixodidae/crescimento & desenvolvimento , Ixodidae/fisiologia , Estrutura Molecular , Muda , Estações do Ano , Aves Canoras/classificação , Aves Canoras/parasitologia , Especificidade da Espécie
6.
Proc Biol Sci ; 286(1912): 20191881, 2019 10 09.
Artigo em Inglês | MEDLINE | ID: mdl-31575373

RESUMO

Segmentation is fundamental to the arthropod body plan. Understanding the evolutionary steps by which arthropods became segmented is being transformed by the integration of data from evolutionary developmental biology (evo-devo), Cambrian fossils that allow the stepwise acquisition of segmental characters to be traced in the arthropod stem-group, and the incorporation of fossils into an increasingly well-supported phylogenetic framework for extant arthropods based on genomic-scale datasets. Both evo-devo and palaeontology make novel predictions about the evolution of segmentation that serve as testable hypotheses for the other, complementary data source. Fossils underpin such hypotheses as arthropodization originating in a frontal appendage and then being co-opted into other segments, and segmentation of the endodermal midgut in the arthropod stem-group. Insights from development, such as tagmatization being associated with different modes of segment generation in different body regions, and a distinct patterning of the anterior head segments, are complemented by palaeontological evidence for the pattern of tagmatization during ontogeny of exceptionally preserved fossils. Fossil and developmental data together provide evidence for a short head in stem-group arthropods and the mechanism of its formation and retention. Future breakthroughs are expected from identification of molecular signatures of developmental innovations within a phylogenetic framework, and from a focus on later developmental stages to identify the differentiation of repeated units of different systems within segmental precursors.


Assuntos
Artrópodes/anatomia & histologia , Evolução Biológica , Padronização Corporal , Fósseis/anatomia & histologia , Animais , Artrópodes/crescimento & desenvolvimento , Paleontologia , Filogenia
7.
Sci Rep ; 9(1): 13631, 2019 09 20.
Artigo em Inglês | MEDLINE | ID: mdl-31541146

RESUMO

One of the most important cellular events in arthropods is the moulting of the cuticle (ecdysis). This process allows them to grow until they reach sexual maturity. Nevertheless, during this stage, the animals are highly exposed to pathogens. Consequently, it can be assumed that arthropods counter with an efficient anti-infective strategy that facilitates their survival during ecdysis. Herein, we characterized a novel antimicrobial peptide called Pinipesin, present in the exuviae extract of the centipede Scolopendra subspinipes subspinipes. The antimicrobial activity of Pinipesin was tested. The haemolytic activity of the peptide was evaluated and its possible mechanism of action was investigated. Identification was carried out by mass spectrometry analysis. Pinipesin displayed potent antimicrobial effects against different microorganisms and showed low haemolytic effects against human erythrocytes at high concentrations. It has a monoisotopic mass of 1213.57 Da, its sequence exhibited high similarity with some cuticular proteins, and it might act intracellularly by interfering with protein synthesis. Our data suggest that Pinipesin might be part of a prophylactic immune response during the ecdysis process of centipedes. Therefore, it is a promising candidate for the development of non-conventional antibiotics that could help fight infectious diseases and represents an exciting discovery for this taxon.


Assuntos
Anti-Infecciosos/metabolismo , Peptídeos Catiônicos Antimicrobianos/metabolismo , Artrópodes/crescimento & desenvolvimento , Bactérias/efeitos dos fármacos , Eritrócitos/citologia , Fungos/efeitos dos fármacos , Animais , Anti-Infecciosos/química , Anti-Infecciosos/farmacologia , Peptídeos Catiônicos Antimicrobianos/química , Peptídeos Catiônicos Antimicrobianos/farmacologia , Proteínas de Artrópodes/química , Proteínas de Artrópodes/metabolismo , Proteínas de Artrópodes/farmacologia , Artrópodes/metabolismo , Bactérias/crescimento & desenvolvimento , Células Cultivadas , Dicroísmo Circular , Eritrócitos/efeitos dos fármacos , Hemólise , Humanos , Testes de Sensibilidade Microbiana , Peso Molecular , Muda
8.
Elife ; 82019 07 03.
Artigo em Inglês | MEDLINE | ID: mdl-31266593

RESUMO

Ecdysis (moulting) is the defining character of Ecdysoza (arthropods, nematodes and related phyla). Despite superficial similarities, the signalling cascade underlying moulting differs between Panarthropoda and the remaining ecdysozoans. Here, we reconstruct the evolution of major components of the ecdysis pathway. Its key elements evolved much earlier than previously thought and are present in non-moulting lophotrochozoans and deuterostomes. Eclosion hormone (EH) and bursicon originated prior to the cnidarian-bilaterian split, whereas ecdysis-triggering hormone (ETH) and crustacean cardioactive peptide (CCAP) evolved in the bilaterian last common ancestor (LCA). Identification of EH, CCAP and bursicon in Onychophora and EH, ETH and CCAP in Tardigrada suggests that the pathway was present in the panarthropod LCA. Trunk, an ancient extracellular signalling molecule and a well-established paralog of the insect peptide prothoracicotropic hormone (PTTH), is present in the non-bilaterian ctenophore Mnemiopsis leidyi. This constitutes the first case of a ctenophore signalling peptide with homology to a neuropeptide.


Assuntos
Artrópodes/crescimento & desenvolvimento , Artrópodes/genética , Evolução Biológica , Muda , Transdução de Sinais , Animais
9.
Environ Toxicol Chem ; 38(10): 2111-2120, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31211447

RESUMO

The use of neonicotinoids in agriculture is a critical environmental protection issue. Although there has been considerable research on pollinator exposure and aquatic toxicological effects, few studies have investigated the chronic impacts on soil-dwelling species. Given the application of neonicotinoids into soil systems, there is the potential for risk to soil invertebrates. The toxicity of 2 commercial formulations containing the active ingredients (a.i.) thiamethoxam (Actara® 240SC) or clothianidin (Titan™) was investigated using 3 soil invertebrate species: Oppia nitens, Eisenia andrei, and Folsomia candida. No adverse effects were observed for O. nitens at the highest tested concentrations (≥92 mg a.i./kg dry soil) after a 28-d exposure. Exposure to clothianidin resulted in a 28-d median inhibitory concentration (IC50) of 0.069 (95% confidence limits: 0.039-0.12) mg/kg dry soil for F. candida, and a 56-d IC50 of 0.26 (0.22-3.2) mg a.i./kg dry soil for E. andrei. Exposure to thiamethoxam was less toxic, with IC50s of 0.36 (0.19-0.66) and 3.0 (2.2-4.0) mg a.i./kg dry soil for F. candida and E. andrei reproduction, respectively. The observed toxicity for F. candida adult survival and reproduction and for E. andrei reproduction occurred at environmentally relevant concentrations. However, because clothianidin is a degradation product of thiamethoxam, and detection of clothianidin rose to levels of concern in the thiamethoxam-amended soils over time, the observed toxicity may be partly attributed to the presence of clothianidin. Environ Toxicol Chem 2019;38:2111-2120. © 2019 Crown in the right of Canada. Published by Wiley Periodicals Inc. on behalf of SETAC.


Assuntos
Guanidinas/toxicidade , Neonicotinoides/toxicidade , Poluentes do Solo/toxicidade , Tiametoxam/toxicidade , Tiazóis/toxicidade , Animais , Artrópodes/efeitos dos fármacos , Artrópodes/crescimento & desenvolvimento , Guanidinas/química , Inseticidas/química , Inseticidas/toxicidade , Neonicotinoides/química , Oligoquetos/efeitos dos fármacos , Oligoquetos/crescimento & desenvolvimento , Reprodução/efeitos dos fármacos , Poluentes do Solo/química , Tiametoxam/química , Tiazóis/química , Testes de Toxicidade
10.
Environ Toxicol Chem ; 38(7): 1486-1494, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-30945337

RESUMO

The present study examined the effects of soil physical and chemical properties on the toxicity of lead (Pb) to earthworms (Eisenia fetida) and collembolans (Folsomia candida), and on bioaccumulation of Pb by earthworms, in soils amended with Pb salts. Toxicity tests were conducted in 7 soils varying in soil properties (pH 4.7-7.4, effective cation exchange capacity [eCEC] 4-42 cmolc /kg, organic carbon 10-50 g C/kg) that were leached and pH corrected after spiking with PbCl2 . The median effect concentrations (EC50s) based on total soil Pb concentrations ranged from 35 to 5080 mg Pb/kg for earthworms and 389 to >7190 mg/kg for Collembola. Significant positive correlations were observed between log (EC50) for earthworm reproduction and log (eCEC, total C, exchangeable Ca and Mg, or clay content), but no significant correlations were observed between Pb toxicity to Collembola and soil properties. Expressing Pb dose as either the free ion (Pb2+ ) activity in porewater or as the measured dissolved porewater concentration of Pb did not explain differences in toxicity among soils. The bioaccumulation factors (BAFs) for Pb in earthworms ranged up to >10-fold across 6 soil treatments, with a median of 0.16, and the BAF was significantly correlated with eCEC (p = 0.038, r = -0.84), but not with any other soil properties. Soil properties related to eCEC (total C, exchangeable Ca and Mg, clay content) had a significant effect on Pb toxicity and bioaccumulation in earthworms, but no relationship was found for Collembola. As a major soil property affecting the bioavailability of Pb, CEC should be incorporated into any soil hazard assessment of Pb as a modifying factor of toxicity and bioaccumulation for earthworms. Environ Toxicol Chem 2019;38:1486-1494. © 2019 SETAC.


Assuntos
Chumbo/metabolismo , Poluentes do Solo/metabolismo , Solo/química , Animais , Artrópodes/efeitos dos fármacos , Artrópodes/crescimento & desenvolvimento , Bioacumulação , Carbono/química , Troca Iônica , Chumbo/toxicidade , Oligoquetos/efeitos dos fármacos , Oligoquetos/crescimento & desenvolvimento , Reprodução/efeitos dos fármacos , Poluentes do Solo/química , Poluentes do Solo/toxicidade , Testes de Toxicidade
11.
Insect Mol Biol ; 28(5): 716-727, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-30953580

RESUMO

Haemocyanins constitute a group of copper-containing respiratory proteins, and hexamerins were derived from hexapod haemocyanin but lost the ability to transport oxygen and serve as storage proteins. Although hexamerins have been reported in most insect species, none of them has been identified in Collembola, one of the most primitive hexapod lineages, thereby preventing us from exploring relevant evolutionary scenarios regarding the origin and evolution of hexamerins in hexapods. Here we report on collembolan hexamerins for the first time, and investigated the temporal expression profiles of hexamerin and haemocyanin in the collembolan Folsomia candida. Haemocyanin was expressed over the entire life cycle, with higher expression at the embryonic stage than at other stages, whereas hexamerin expression was restricted to embryos, unlike insect hexamerins, which are generally expressed from larval to adult stages. A phylogenetic analysis and molecular clock estimation suggested that all investigated hexapod hexamerins have a single and ancient origin (~423 Ma), coincident with the rise of atmospheric oxygen levels in the Silurian-Devonian period, indicating a physiological link between molecular evolution and Palaeozoic oxygen changes.


Assuntos
Artrópodes/metabolismo , Hemocianinas/metabolismo , Proteínas de Insetos/metabolismo , Sequência de Aminoácidos , Animais , Proteínas de Artrópodes/genética , Proteínas de Artrópodes/metabolismo , Artrópodes/genética , Artrópodes/crescimento & desenvolvimento , Evolução Molecular , Hemocianinas/genética , Proteínas de Insetos/genética , Larva/genética , Larva/metabolismo , Filogenia , Transcriptoma
12.
Sci Rep ; 9(1): 5709, 2019 04 05.
Artigo em Inglês | MEDLINE | ID: mdl-30952888

RESUMO

Moulting is a fundamental component of the ecdysozoan life cycle, but the fossil record of this strategy is susceptible to preservation biases, making evidence of ecdysis in soft-bodied organisms extremely rare. Here, we report an exceptional specimen of the fuxianhuiid Alacaris mirabilis preserved in the act of moulting from the Cambrian (Stage 3) Xiaoshiba Lagerstätte, South China. The specimen displays a flattened and wrinkled head shield, inverted overlap of the trunk tergites over the head shield, and duplication of exoskeletal elements including the posterior body margins and telson. We interpret this fossil as a discarded exoskeleton overlying the carcass of an emerging individual. The moulting behaviour of A. mirabilis evokes that of decapods, in which the carapace is separated posteriorly and rotated forward from the body, forming a wide gape for the emerging individual. A. mirabilis illuminates the moult strategy of stem-group Euarthropoda, offers the stratigraphically and phylogenetically earliest direct evidence of ecdysis within total-group Euarthropoda, and represents one of the oldest examples of this growth strategy in the evolution of Ecdysozoa.


Assuntos
Artrópodes/crescimento & desenvolvimento , Fósseis , Muda , Exoesqueleto , Animais , Artrópodes/genética , Evolução Biológica , China , Filogenia
15.
Sci Rep ; 9(1): 10, 2019 01 09.
Artigo em Inglês | MEDLINE | ID: mdl-30626881

RESUMO

Organism size and growth curves are important biological characteristics. Current methods to measure organism size, and in particular growth curves, are often resource intensive because they involve many manual steps. Here we demonstrate a method for automated, high-throughput measurements of size and growth in individual aquatic invertebrates kept in microtiter well-plates. We use a spheroid counter (Cell3iMager, cc-5000) to automatically measure size of seven different freshwater invertebrate species. Further, we generated calibration curves (linear regressions, all p < 0.0001, r2 >=0.9 for Ceriodaphnoa dubia, Asellus aquaticus, Daphnia magna, Daphnia pulex; r2 >=0.8 for Hyalella azteca, Chironomus spec. larvae and Culex spec. larvae) to convert size measured on the spheroid counter to traditional, microscope based, length measurements, which follow the longest orientation of the body. Finally, we demonstrate semi-automated measurement of growth curves of individual daphnids (C. dubia and D. magna) over time and find that the quality of individual growth curves varies, partly due to methodological reasons. Nevertheless, this novel method could be adopted to other species and represents a step change in experimental throughput for measuring organisms' shape, size and growth curves. It is also a significant qualitative improvement by enabling high-throughput assessment of inter-individual variation of growth.


Assuntos
Artrópodes/crescimento & desenvolvimento , Água Doce , Larva/crescimento & desenvolvimento , Animais
16.
Ecotoxicol Environ Saf ; 169: 207-215, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30448703

RESUMO

Mancozeb is a fungicide widely used in agriculture, mostly against the pathogen Glomerella cingulata responsible for the rot of ripe grape, but presents high toxicity. Strategies are sought to reduce the toxicity of this fungicide and alternative treatments are welcome. An alternative could be the use of clove oil, which has Eugenol as its major compound, and has antifungal potential against G. cingulata, however, Eugenol is susceptible to degradation processes which may compromise its efficacy. The nanoencapsulation of Mancozeb and Eugenol is a possible strategy to overcome the limitations of toxicity, solubility and instability of these compounds. Therefore, the objective of this study is to develop nanoemulsions containing Mancozeb (0.1 mg/mL) and Eugenol (33 mg/mL), isolated or associated, and evaluate the safety of these formulations through cytotoxicity, genotoxicity and ecotoxicity tests. Nanoemulsions were developed by the spontaneous emulsification method, cytotoxicity and genotoxicity were evaluated in healthy human cells through MTT, Dichlorofluorescein diacetate and Picogreen tests, and ecotoxicity assessment was carried out using the chronic toxicity test in springtails. After preparation, the physicochemical characterization of the nanoemulsions were performed which presented mean particle size between 200 and 300 nm, polydispersity index less than 0.3, negative zeta potential and acid pH. The nanoencapsulation was able to avoid the reduction of the cell viability caused by Mancozeb, while Eugenol was shown to be safe for cell use in both free and nanostructured forms, however the association of the two active compounds showed toxicity in the higher doses of Mancozeb. In the ecotoxicity tests, both free Mancozeb and Eugenol forms presented high toxic potential for soil, whereas the nanoencapsulation of these compounds did not cause a reduction in number of springtails. Therefore, from the tests performed, it was possible to observe that nanoencapsulation of Mancozeb and Eugenol is a safe alternative for the application of these compounds mainly in agriculture.


Assuntos
Artrópodes/efeitos dos fármacos , Dano ao DNA , Eugenol/toxicidade , Fungicidas Industriais/toxicidade , Maneb/toxicidade , Nanocápsulas/toxicidade , Zineb/toxicidade , Animais , Artrópodes/crescimento & desenvolvimento , Sobrevivência Celular/efeitos dos fármacos , Sinergismo Farmacológico , Emulsões , Eugenol/química , Fungicidas Industriais/química , Humanos , Leucócitos Mononucleares/efeitos dos fármacos , Maneb/química , Nanocápsulas/química , Tamanho da Partícula , Phyllachorales/efeitos dos fármacos , Solo/química , Testes de Toxicidade , Zineb/química
17.
Arthropod Struct Dev ; 48: 20-34, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30367936

RESUMO

Arachnids and their relatives (Chelicerata) range in body length from tens of centimetres in horseshoe crabs down to little more than 80-200 µm in several groups of mites. Spiders (Araneae) show the widest range within a given Bauplan - the largest species being ca. 270 times longer than the smallest - making them excellent models to investigate scaling effects. The two mite clades (Parasitiformes and Acariformes) are the main specialists in being small. Miniaturisation, and its consequences, is reviewed for both fossil and extant chelicerates. Morphological changes potentially related to miniaturisation, or adapting to the ecological niches that small size allows, include reduction in the length and number of legs, loss of prosomal arteries (and eventually also the heart), replacement of book lungs by tracheae, or even loss of all respiratory organs. There may also be evolutionary novelties, such as the acquisition of structures by which some mites attach themselves to larger hosts. The observed character distributions suggest a fairly fundamental division between larger pulmonate (lung-bearing) arachnids and smaller, non-pulmonate, groups which could reflect a phylogenetic dichotomy. However, it is worth noting that lineages of tiny spiders were originally fully pulmonate, but have acquired some typically non-pulmonate features, while camel spiders (Soli-fugae) can be large but have a Bauplan suggestive of smaller, non-pulmonate, ancestors.


Assuntos
Artrópodes/anatomia & histologia , Evolução Biológica , Animais , Aracnídeos/anatomia & histologia , Aracnídeos/crescimento & desenvolvimento , Artrópodes/crescimento & desenvolvimento , Tamanho Corporal
18.
BMC Evol Biol ; 18(1): 147, 2018 09 29.
Artigo em Inglês | MEDLINE | ID: mdl-30268090

RESUMO

BACKGROUND: Extended parental care is a complex reproductive strategy in which progenitors actively look after their offspring up to - or beyond - the first juvenile stage in order to maximize their fitness. Although the euarthropod fossil record has produced several examples of brood-care, the appearance of extended parental care within this phylum remains poorly constrained given the scarcity of developmental data for Palaeozoic stem-group representatives that would link juvenile and adult forms in an ontogenetic sequence. RESULTS: Here, we describe the post-embryonic growth of Fuxianhuia protensa from the early Cambrian Chengjiang Lagerstätte in South China. Our data demonstrate anamorphic post-embryonic development for F. protensa, in which new tergites were sequentially added from a posterior growth zone, the number of tergites varies from eight to 30. The growth of F. protensa is typified by the alternation between segment addition, followed by the depletion of the anteriormost abdominal segment into the thoracic region. The transformation of abdominal into thoracic tergite is demarcated by the development of laterally tergopleurae, and biramous walking legs. The new ontogeny data leads to the recognition of the rare Chengjiang euarthropod Pisinnocaris subconigera as a junior synonym of Fuxianhuia. Comparisons between different species of Fuxianhuia and with other genera within Fuxianhuiida suggest that heterochrony played a prominent role in the morphological diversification of fuxianhuiids. Functional analogy with the flexible trunk ontogeny of Cambrian and Silurian olenimorphic trilobites suggests an adaptation to sporadic low oxygen conditions in Chengjiang deposits for F. protensa. Finally, understanding the growth of F. protensa allows for the interpretation of an exceptional life assemblage consisting of a sexually mature adult alongside four ontogenetically coeval juveniles, which constitutes the oldest occurrence of extended parental care by prolonged cohabitation in the panarthropod fossil record. CONCLUSIONS: Our findings constitute the most detailed characterization of the post-embryonic development in a soft-bodied upper stem-group euarthropod available to date. The new ontogeny data illuminates the systematics, trunk segmentation and palaeoecology of F. protensa, offers insights on the macroevolutionary processes involved in the diversification of this clade, and contributes towards an improved understanding of complex post-embryonic reproductive ecology in Cambrian euarthropods.


Assuntos
Artrópodes/crescimento & desenvolvimento , Fósseis , Animais , Artrópodes/anatomia & histologia , Artrópodes/classificação , China , Fatores de Tempo
19.
Arthropod Struct Dev ; 47(6): 655-661, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30273712

RESUMO

In Arthropoda, the ovary is classified into Chelicerata-type and Mandibulata-type, based on the oocyte-growth position within the ovary. By contrast, oocytes of Diplopoda and Chilopoda grow within the hemocoelic space. However, as the position of oocyte-growth in Symphyla and Pauropoda has not been confirmed, whether the hemocoelic nature of oocyte-growth is common among myriapods remains ambiguous. This study described the ovarian structure of Hanseniella caldaria to reveal the oocyte-growth position in Symphyla. The oocyte is surrounded by the follicle epithelium, and the inner surface of the follicle epithelium, i.e., the space between follicle cells and oocytes, is lined with a basement membrane. The follicle epithelial layer continues to the ovarian epithelium via the follicle extension with a continuous layer of basement membrane. Data on the architecture of the follicle suggest that the follicle pouch opens to the hemocoel. Hence, the oocyte of H. caldaria grows within the hemocoelic space. Based on our findings in H. caldaria and previous studies in a millipede and in centipedes, the hemocoelic nature of oocyte-growth is considered as a common feature among myriapods and a synapomorphy of the Myriapoda for which morphological synapomorphies have been ambiguous.


Assuntos
Artrópodes/crescimento & desenvolvimento , Oócitos/crescimento & desenvolvimento , Animais , Artrópodes/citologia , Artrópodes/ultraestrutura , Feminino , Microscopia , Microscopia Eletrônica de Transmissão , Oócitos/citologia , Oócitos/ultraestrutura , Ovário/citologia , Ovário/crescimento & desenvolvimento , Ovário/ultraestrutura , Filogenia
20.
Proc Natl Acad Sci U S A ; 115(44): E10397-E10406, 2018 10 30.
Artigo em Inglês | MEDLINE | ID: mdl-30322922

RESUMO

A number of studies indicate that tropical arthropods should be particularly vulnerable to climate warming. If these predictions are realized, climate warming may have a more profound impact on the functioning and diversity of tropical forests than currently anticipated. Although arthropods comprise over two-thirds of terrestrial species, information on their abundance and extinction rates in tropical habitats is severely limited. Here we analyze data on arthropod and insectivore abundances taken between 1976 and 2012 at two midelevation habitats in Puerto Rico's Luquillo rainforest. During this time, mean maximum temperatures have risen by 2.0 °C. Using the same study area and methods employed by Lister in the 1970s, we discovered that the dry weight biomass of arthropods captured in sweep samples had declined 4 to 8 times, and 30 to 60 times in sticky traps. Analysis of long-term data on canopy arthropods and walking sticks taken as part of the Luquillo Long-Term Ecological Research program revealed sustained declines in abundance over two decades, as well as negative regressions of abundance on mean maximum temperatures. We also document parallel decreases in Luquillo's insectivorous lizards, frogs, and birds. While El Niño/Southern Oscillation influences the abundance of forest arthropods, climate warming is the major driver of reductions in arthropod abundance, indirectly precipitating a bottom-up trophic cascade and consequent collapse of the forest food web.


Assuntos
Artrópodes/crescimento & desenvolvimento , Clima Tropical/efeitos adversos , Animais , Biodiversidade , Biomassa , Aves/crescimento & desenvolvimento , Ecossistema , El Niño Oscilação Sul/efeitos adversos , Cadeia Alimentar , Florestas , Porto Rico , Floresta Úmida , Árvores/crescimento & desenvolvimento
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