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1.
Zool Res ; 42(5): 637-649, 2021 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-34472225

RESUMO

The insect brain is the central part of the neurosecretory system, which controls morphology, physiology, and behavior during the insect's lifecycle. Lepidoptera are holometabolous insects, and their brains develop during the larval period and metamorphosis into the adult form. As the only fully domesticated insect, the Lepidoptera silkworm Bombyx mori experienced changes in larval brain morphology and certain behaviors during the domestication process. Hormonal regulation in insects is a key factor in multiple processes. However, how juvenile hormone (JH) signals regulate brain development in Lepidoptera species, especially in the larval stage, remains elusive. We recently identified the JH receptor Methoprene tolerant 1 ( Met1) as a putative domestication gene. How artificial selection on Met1 impacts brain and behavioral domestication is another important issue addressing Darwin's theory on domestication. Here, CRISPR/Cas9-mediated knockout of Bombyx Met1 caused developmental retardation in the brain, unlike precocious pupation of the cuticle. At the whole transcriptome level, the ecdysteroid (20-hydroxyecdysone, 20E) signaling and downstream pathways were overactivated in the mutant cuticle but not in the brain. Pathways related to cell proliferation and specialization processes, such as extracellular matrix (ECM)-receptor interaction and tyrosine metabolism pathways, were suppressed in the brain. Molecular evolutionary analysis and in vitro assay identified an amino acid replacement located in a novel motif under positive selection in B. mori, which decreased transcriptional binding activity. The B. mori MET1 protein showed a changed structure and dynamic features, as well as a weakened co-expression gene network, compared with B. mandarina. Based on comparative transcriptomic analyses, we proposed a pathway downstream of JH signaling (i.e., tyrosine metabolism pathway) that likely contributed to silkworm larval brain development and domestication and highlighted the importance of the biogenic amine system in larval evolution during silkworm domestication.


Assuntos
Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Bombyx/metabolismo , Proteínas de Insetos/metabolismo , Hormônios Juvenis/metabolismo , Sequência de Aminoácidos , Animais , Sequência de Bases , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Bombyx/crescimento & desenvolvimento , Encéfalo/crescimento & desenvolvimento , Encéfalo/metabolismo , Sistemas CRISPR-Cas , Deleção de Genes , Regulação da Expressão Gênica no Desenvolvimento , Genótipo , Proteínas de Insetos/genética , Tegumento Comum/fisiologia , Larva/crescimento & desenvolvimento , Larva/metabolismo , Filogenia , Conformação Proteica
2.
Zool Res ; 42(5): 614-619, 2021 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-34402607

RESUMO

Butterflies are diverse in virtually all aspects of their ontogeny, including morphology, life history, and behavior. However, the developmental regulatory mechanisms underlying the important phenotypic traits of butterflies at different developmental stages remain unknown. Here, we investigated the developmental regulatory profiles of butterflies based on transposase accessible chromatin sequencing (ATAC-seq) at three developmental stages in two representative species ( Papilio xuthus and Kallima inachus). Results indicated that 15%-47% of open chromatin peaks appeared in associated genes located 3 kb upstream (i.e., promoter region) of their transcription start site (TSS). Comparative analysis of the different developmental stages indicated that chromatin accessibility is a dynamic process and associated genes with differentially accessible (DA) peaks show functions corresponding to their phenotypic traits. Interestingly, the black color pattern in P. xuthus 4th instar larvae may be attributed to promoter peak-related genes involved in the melanogenesis pathway. Furthermore, many longevity genes in 5th instar larvae and pupae showed open peaks 3 kb upstream of their TSS, which may contribute to the overwintering diapause observed in K. inachus adults. Combined with RNA-seq analysis, our data demonstrated that several genes enriched in the melanogenesis and longevity pathways also exhibit higher expression, confirming that the expression of genes may be closely related to their phenotypic traits. This study offers new insights into larval cuticle color and adult longevity in butterflies and provides a resource for investigating the developmental regulatory mechanisms underlying butterfly ontogeny.


Assuntos
Borboletas/fisiologia , Cromatina/metabolismo , Pigmentação/genética , Pigmentos Biológicos/metabolismo , Transcriptoma , Animais , Borboletas/anatomia & histologia , Regulação da Expressão Gênica no Desenvolvimento/fisiologia , Tegumento Comum/fisiologia , Larva/anatomia & histologia , Larva/fisiologia , Pigmentação/fisiologia
3.
Zoolog Sci ; 38(3): 252-258, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-34057350

RESUMO

Holothuria atra is a black sea cucumber commonly found on the sandy bottom of Okinawan coral reefs. The body surface of H. atra is usually covered with sand; however, sand never covers the body of another black congener, Holothuria leucospilota, which is sympatrically distributed with H. atra. The epidermal structures were examined in these two species by means of transmission electron microscopy to determine how sand adheres to the surface of H. atra. While the epidermis was basically composed of support cells bearing microvilli and vacuolated cells probably corresponding to mucus cells, two types of granular cells, type 1 and 2, were also found at the tip of the tube feet. These granular cells were closely similar in structure to secretory cells that have been supposed to secrete adhesive substances in other holothurians. Type 1 granular cells were also found in the dorsal epidermis of H. atra but not in H. leucospilota. Therefore, adhesive secretion by type 1 granular cells probably enables the attachment of sand to the H. atra body.


Assuntos
Holothuria/anatomia & histologia , Areia , Animais , Ecossistema , Holothuria/fisiologia , Tegumento Comum/anatomia & histologia , Tegumento Comum/fisiologia
4.
Proc Natl Acad Sci U S A ; 118(5)2021 02 02.
Artigo em Inglês | MEDLINE | ID: mdl-33468629

RESUMO

Many small animals use springs and latches to overcome the mechanical power output limitations of their muscles. Click beetles use springs and latches to bend their bodies at the thoracic hinge and then unbend extremely quickly, resulting in a clicking motion. When unconstrained, this quick clicking motion results in a jump. While the jumping motion has been studied in depth, the physical mechanisms enabling fast unbending have not. Here, we first identify and quantify the phases of the clicking motion: latching, loading, and energy release. We detail the motion kinematics and investigate the governing dynamics (forces) of the energy release. We use high-speed synchrotron X-ray imaging to observe and analyze the motion of the hinge's internal structures of four Elater abruptus specimens. We show evidence that soft cuticle in the hinge contributes to the spring mechanism through rapid recoil. Using spectral analysis and nonlinear system identification, we determine the equation of motion and model the beetle as a nonlinear single-degree-of-freedom oscillator. Quadratic damping and snap-through buckling are identified to be the dominant damping and elastic forces, respectively, driving the angular position during the energy release phase. The methods used in this study provide experimental and analytical guidelines for the analysis of extreme motion, starting from motion observation to identifying the forces causing the movement. The tools demonstrated here can be applied to other organisms to enhance our understanding of the energy storage and release strategies small animals use to achieve extreme accelerations repeatedly.


Assuntos
Besouros/fisiologia , Elasticidade , Dinâmica não Linear , Animais , Fenômenos Biomecânicos , Besouros/anatomia & histologia , Metabolismo Energético/fisiologia , Tegumento Comum/fisiologia , Movimento (Física) , Raios X
5.
Sci Rep ; 10(1): 20484, 2020 11 24.
Artigo em Inglês | MEDLINE | ID: mdl-33235272

RESUMO

In social species, the presence of several reproductive individuals can generate conflict. In social insects, as queen number increases, individual oviposition rate may decrease because of direct and indirect behavioural and/or chemical interactions. Understanding the factors that mediate differences in queen fecundity should provide insight into the regulation and maintenance of highly polygynous insect societies, such as those of the invasive Argentine ant (Linepithema humile). In this study, we investigated (1) whether differences in the oviposition rates of Argentine ant queens exposed to polygynous conditions could result from interactions among them; (2) whether such differences in fecundity stemmed from differences in worker attention; and (3) whether polygynous conditions affected the cuticular hydrocarbon profiles of queens (CHCs). We found that differences in queen fecundity and CHC profiles observed under polygynous conditions disappeared when queens were exposed to monogynous conditions, suggesting some form of reproductive inhibition may exist when queens cohabit. These differences did not seem to arise from variation in worker attention because more fecund queens were not more attractive to workers. Levels of some CHCs were higher in more fecund queens. These CHCs are associated with greater queen productivity and survival. Our findings indicate that such compounds could be multifunctional queen pheromones.


Assuntos
Formigas/fisiologia , Comportamento de Nidação/fisiologia , Animais , Análise Discriminante , Feminino , Fertilidade/fisiologia , Hierarquia Social , Hidrocarbonetos/metabolismo , Tegumento Comum/fisiologia , Ovário/fisiologia , Óvulo/fisiologia , Reprodução/fisiologia
6.
Insect Mol Biol ; 29(5): 452-465, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32654295

RESUMO

The silkworm is an economically important insect producing plentiful silk fibre in the silk gland. In this study, we reported a cross-talk between the fat body, silk gland and midgut through a glycine-serine biosynthetic pathway in the silkworm. Amino acid sequence and functional domains of glycine transporter gene BmGT1-L were mapped. Our results indicated that BmGT1-L was specifically expressed in the midgut microvilli and persistently expressed during the feeding stages. RNA interference of BmGT1-L activated glycine biosynthesis, and BmGT1-L overexpression facilitated serine biosynthesis in the BmN4-SID1 cell. In addition, silkworms after FibH gene knock-out or silk gland extirpation showed markedly decreased BmGT1-L transcripts in the midgut and disturbed glycine-serine biosynthesis as silk yield decreased. Finally, BmGT1-L ectopic expression in the posterior silk gland promoted glycine biosynthesis, and enhanced silk yield via increasing fibroin synthesis. These results suggested that cross-talk between tissues can be used for enhancing silk yield in the silkworm.


Assuntos
Bombyx/metabolismo , Expressão Ectópica do Gene , Proteínas de Insetos/genética , Seda/biossíntese , Sequência de Aminoácidos , Animais , Animais Geneticamente Modificados/genética , Animais Geneticamente Modificados/crescimento & desenvolvimento , Animais Geneticamente Modificados/metabolismo , Bombyx/genética , Bombyx/crescimento & desenvolvimento , Glândulas Exócrinas/metabolismo , Proteínas de Insetos/química , Proteínas de Insetos/metabolismo , Tegumento Comum/fisiologia , Larva/genética , Larva/crescimento & desenvolvimento , Larva/metabolismo , Alinhamento de Sequência , Seda/genética
7.
J Anat ; 237(3): 404-426, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32458532

RESUMO

Scaly-tailed squirrels, the most poorly known group of gliding mammals, hold the record for variety of remarkable integument peculiarities. One of the most striking of these features is the scales on the tail, which apparently allow them to reduce energy costs when positioning themselves on a tree trunk. No less interesting is a peculiar spur that supports the flying membrane: the unciform element ('spur'). Despite the peculiarity of such elements, their nature has not yet been studied. Using anatomical, histological methods and scanning electron microscopy we studied the structure of the skin and its derivatives in five of the six species from both genera of extant gliding scaly-tailed squirrels (Anomaluridae, Rodentia): Idiurus macrotis, Idiurus zenkeri, Anomalurus beecrofti, Anomalurus pusillus and Anomalurus derbianus. In addition to the common mammalian skin structures, such as hair, vibrissae, sebaceous glands, meibomian glands of eyelids and eccrine sweat glands of the palmar and plantar pads, these animals have unique species-specific skin derivatives (the tail scaly organ and its specific glands, vibrissae of the withers, patagium and its hair brush) that play a significant role in their adaptation to gliding and to their environment in general. The structure of the elbow spur is also described and hypotheses on its evolutionary origin from the tendon of the triceps muscle are presented.


Assuntos
Adaptação Fisiológica/fisiologia , Tegumento Comum/anatomia & histologia , Locomoção/fisiologia , Roedores/anatomia & histologia , Animais , Tegumento Comum/fisiologia , Roedores/fisiologia , Especificidade da Espécie
8.
Molecules ; 25(7)2020 Mar 29.
Artigo em Inglês | MEDLINE | ID: mdl-32235326

RESUMO

Phosphine resistance is a worldwide issue threatening the grain industry. The cuticles of insects are covered with a layer of lipids, which protect insect bodies from the harmful effects of pesticides. The main components of the cuticular lipids are hydrocarbon compounds. In this research, phosphine-resistant and -susceptible strains of two main stored-grain insects, T. castaneum and R. dominica, were tested to determine the possible role of their cuticular hydrocarbons in phosphine resistance. Direct immersion solid-phase microextraction followed by gas chromatography-mass spectrometry (GC-MS) was applied to extract and analyze the cuticular hydrocarbons. The results showed significant differences between the resistant and susceptible strains regarding the cuticular hydrocarbons that were investigated. The resistant insects of both species contained higher amounts than the susceptible insects for the majority of the hydrocarbons, sixteen from cuticular extraction and nineteen from the homogenized body extraction for T. castaneum and eighteen from cuticular extraction and twenty-one from the homogenized body extraction for R. dominica. 3-methylnonacosane and 2-methylheptacosane had the highest significant difference between the susceptible and resistant strains of T. castaneum from the cuticle and the homogenized body, respectively. Unknown5 from the cuticle and 3-methylhentriacontane from the homogenized body recorded the highest significant differences in R. dominica. The higher hydrocarbon content is a key factor in eliminating phosphine from entering resistant insect bodies, acting as a barrier between insects and the surrounding phosphine environment.


Assuntos
Alcanos/isolamento & purificação , Besouros/efeitos dos fármacos , Resistência a Inseticidas/fisiologia , Inseticidas/farmacologia , Fosfinas/farmacologia , Tribolium/efeitos dos fármacos , Alcanos/química , Alcanos/classificação , Animais , Besouros/química , Besouros/fisiologia , Misturas Complexas/química , Grão Comestível/parasitologia , Cromatografia Gasosa-Espectrometria de Massas , Tegumento Comum/fisiologia , Microextração em Fase Sólida , Tribolium/química , Tribolium/fisiologia , Triticum/parasitologia
9.
Int J Mol Sci ; 21(7)2020 Mar 31.
Artigo em Inglês | MEDLINE | ID: mdl-32244312

RESUMO

The skin of the frog Xenopus laeevis is protected from microbial infections by a mucus barrier that contains frog integumentary mucins (FIM)-A.1, FIM-B.1, and FIM-C.1. These gel-forming mucins are synthesized in mucous glands consisting of ordinary mucous cells and one or more cone cells at the gland base. FIM-A.1 and FIM-C.1 are unique because their cysteine-rich domains belong to the trefoil factor family (TFF). Furthermore, FIM-A.1 is unusually short (about 400 amino acid residues). In contrast, FIM-B.1 contains cysteine-rich von Willebrand D (vWD) domains. Here, we separate skin extracts by the use of size exclusion chromatography and analyze the distribution of FIM-A.1 and FIM-C.1. Two mucin complexes were detected, i.e., a high-molecular-mass Complex I, which contains FIM-C.1 and little FIM-A.1, whereas Complex II is of lower molecular mass and contains the bulk of FIM-A.1. We purified FIM-A.1 by a combination of size-exclusion chromatography (SEC) and anion-exchange chromatography and performed first in vitro binding studies with radioactively labeled FIM-A.1. Binding of 125I-labeled FIM-A.1 to the high-molecular-mass Complex I was observed. We hypothesize that the presence of FIM-A.1 in Complex I is likely due to lectin interactions, e.g., with FIM-C.1, creating a complex mucus network.


Assuntos
Tegumento Comum/fisiologia , Mucinas/metabolismo , Muco/metabolismo , Fatores Trefoil/metabolismo , Proteínas de Xenopus/metabolismo , Xenopus laevis/metabolismo , Animais , Glândulas Exócrinas , Mucinas/química , Pele/metabolismo , Proteínas de Xenopus/química
10.
Sci Rep ; 10(1): 6663, 2020 04 20.
Artigo em Inglês | MEDLINE | ID: mdl-32313020

RESUMO

Cylindrical silk gland (CY) spigots distinguish a large clade of modern spiders, the CY spigot clade, which includes all entelegyne spiders and their closest relatives. Following a widespread paradigm, CYs and their spigots are only known to occur in female spiders and they produce silk used in the construction of egg sacs. Here we report the occurrence of a CY spigot or CY nubbin on each posterior median spinneret (PMS) in males (5th stadium and later) of the spider Australomimetus maculosus. Late juvenile males had a CY spigot on each PMS, whereas adult males either had a CY spigot or, more often, a non-functional CY nubbin. This indicates that potential CY use by males is at least largely limited to late juvenile instars and is not involved with egg sac construction. Despite the presence of CY spigots in both sexes, sexual dimorphism with respect to CYs was still evident since males lacked the CY spigot on each posterior lateral spinneret present in late juvenile and adult females, and CY spigots of males never had the wide shaft and opening of adult females. This study adds to our knowledge of spinning apparatus variability in modern spiders and demonstrates an exception to the paradigm that, in the CY spigot clade, such spigots are restricted to female spiders.


Assuntos
Tegumento Comum/fisiologia , Caracteres Sexuais , Seda/biossíntese , Aranhas/fisiologia , Animais , Feminino , Tegumento Comum/anatomia & histologia , Masculino , Microscopia Eletrônica de Varredura , Aranhas/anatomia & histologia , Aranhas/ultraestrutura
11.
Acta Biomater ; 101: 414-421, 2020 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-31669541

RESUMO

In many cases, strong friction reduction is critical for success of both living organisms and engineering systems. Some arthropods exhibit good antifriction abilities in their specific living environments and have inspired many innovations for solving industry challenges. However, the current literature mainly focused on terrestrial insects, such as beetles, grasshoppers and katydids. The antifriction mechanisms in amphibious arthropods are still unknown, even if their surfaces are optimized for both air and water environments. Herein the tribological properties of the cuticle surface of the sandhopper Talitrus saltator were studied using a universal microtribometer. Further investigations were developed to identify the microstructural, compositional, wettability, and mechanical properties of the sandhopper shell cuticles. It was found that increasing normal force can significantly reduce the coefficient of friction of the shell cuticle, especially for the alive and rewet sandhopper shells. The shell consists of bottle-like nano-caves in its exocuticle, nano-tubes in its mesocuticle, and gauze-like multilayers in its endocuticle. Under physiological conditions, glycoprotein-like fluid fillings exist in both the bottle-like caves and the nano-tubes below and cover on the shell surface. More importantly, a new antifriction mechanism of lubricant-squeezing nano-porous system was established for the sandhopper shell. This work can deepen our understanding in antifriction surfaces of amphibiotic crustaceans, and provide a potential approach to resolve the friction challenge in micro-machines, especially for the applications under aqueous condition. STATEMENT OF SIGNIFICANCE: Friction regulation is one of the critical mechanisms for animal locomotion in natural environments. However, not much is known about the mechanism of amphibious arthropods to reduce friction between their body and diverse environments, particularly achieving adaption under both air and aqueous conditions. We quantitatively study the microstructural, compositional and mechanical properties of the sandhopper (Talitrus saltator) shell cuticle and tribological behaviors under different conditions. Our results reveal the nano-porous system with fluid fillings for the sandhopper's shell and demonstrate the potential antifriction mechanism of this amphibious animal. We anticipate this work will inspire some effective antifriction designs for micro-machines, especially for their applications in complex environment like human body.


Assuntos
Anfípodes/anatomia & histologia , Anfípodes/fisiologia , Fricção , Tegumento Comum/anatomia & histologia , Tegumento Comum/fisiologia , Anfípodes/ultraestrutura , Exoesqueleto/anatomia & histologia , Exoesqueleto/ultraestrutura , Animais , Módulo de Elasticidade , Modelos Lineares , Reologia , Propriedades de Superfície , Molhabilidade
12.
J Exp Zool A Ecol Integr Physiol ; 333(1): 20-28, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31647615

RESUMO

It is well known that repeated loading cycles can reduce the strength of a material and cause eventual failure by the gradual build-up of damage. Previous work has shown that mammalian bone is able to extend its life almost indefinitely by continuously repairing microdamage, preventing the development of macroscopic cracks. However, no study has been conducted until now to investigate repair of microdamage in any other biological material. We applied cyclic bending loads to the hind tibiae of desert locusts (Schistocerca gregaria). We observed a significant decrease in the elastic stiffness (Young's modulus) of the cuticle during the five applied loading cycles, indicating that microdamage had been induced. The tibiae were then left to rest for various time periods: 1 hr, 24 hr, 1 week, and 4 weeks. When tested again after up to 24 hr, there was still a significant decrease in stiffness, showing that some microdamage remained. However, in the samples left for 1 week or 4 weeks before retesting, this decrease in stiffness had disappeared, indicating that the microdamage had been repaired. This is the first ever indication that insects are capable of repairing microdamage. It is a highly significant finding-insects such as locusts rely on the stiffness and strength of their hind legs for jumping. This study suggests that, within a time period of order of a few days, the insect can fully restore the mechanical function of an overloaded leg and thus return to normal activities.


Assuntos
Gafanhotos/fisiologia , Tegumento Comum/fisiologia , Animais , Fenômenos Biomecânicos , Pressão , Estresse Mecânico , Resistência à Tração
13.
Funct Integr Genomics ; 20(2): 223-235, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31478115

RESUMO

The diversity markings and pigment patterns in insects are outcomes of adaptive evolution. The elucidation of the molecular mechanism underlying variations in pigment patterns may improve our understanding of the origin and evolution of these spectacular diverse phenotypes. Melanin, ommochrome, and pteridine are the three main types of insect pigments, and the genes that directly participate in pigment biosynthesis have been extensively studied. However, available information on gene interactions and the whole pigment regulatory network is limited. In this study, we performed integument transcriptome sequencing to analyze three larval marking allelic mutants, namely, multi lunar (L), LC, and LCa, which have similar twin-spot markings on the dorsal side of multiple segments. Further analysis identified 336 differentially expressed genes (DEGs) between L and Dazao (wild type which exhibits normal markings), 68 DEGs between LC/+ and +LC/+LC, and 188 DEGs between LCa/+ and +LCa/+LCa. Gene Ontology (GO) analysis indicated a significant DEG enrichment of the functional terms catalytic activity, binding, metabolic process, and cellular process. Furthermore, three mutants share six common enriched KEGG pathways. We finally identified eight common DEGs among three pairwise comparisons, including Krueppel-like factor, TATA-binding protein, protein patched, UDP-glycosyltransferase, an unknown secreted protein, and three cuticular proteins. Microarray-based gene expression analysis revealed that the eight genes are upregulated during molting, which coincides with marking formation, and are significantly differentially expressed between marking and non-marking regions. The results suggest that the eight common genes are involved in the construction of the multiple twin-spot marking patterns in the three mutants.


Assuntos
Alelos , Bombyx/genética , Tegumento Comum/fisiologia , Mutação , Transcriptoma , Animais , Padronização Corporal , Perfilação da Expressão Gênica , Biblioteca Gênica , Genes de Insetos , Proteínas de Insetos/genética , Larva , Fenótipo , Pigmentos Biológicos/biossíntese , RNA-Seq , Pele/metabolismo
14.
J Evol Biol ; 32(11): 1186-1193, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31420906

RESUMO

A role for sexual selection in the evolution of insect cuticular hydrocarbons (CHCs) is suggested by observations of selection acting on male CHCs during female mate choice. However, evidence that CHCs evolve in response to sexual selection is generally lacking, and there is a need to extend our understanding beyond well-studied taxa. Experimental evolution offers a powerful approach to investigate the effect of sexual selection on the evolution of insect CHCs. We conducted such an experiment using the dung beetle, Onthophagus taurus. After six, 12 and 21 generations of experimental evolution, we measured the CHCs of beetles from three populations subject to sexual selection and three populations within which sexual selection had been removed via enforced monogamy. We found that the male CHC profile responded to the experimental removal of sexual selection. Conversely, the CHC profile of females responded to the presence of sexual selection but not to its removal. These results show that sexual selection can be an important mechanism affecting the evolution of insect CHCs and that male and female CHCs can evolve independently.


Assuntos
Evolução Biológica , Besouros/genética , Besouros/fisiologia , Hidrocarbonetos/metabolismo , Tegumento Comum/fisiologia , Preferência de Acasalamento Animal/fisiologia , Animais , Feminino , Masculino
15.
Insect Mol Biol ; 28(6): 850-861, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31125161

RESUMO

Fatty acid synthase is a multifunctional enzyme involved in the formation of fatty acids. Despite the role of fatty acids in cell signalling and energy metabolism, and as precursors to pheromones and hydrocarbons that waterproof the cuticle, the insect fatty acid synthases have been scarcely studied. Here we perform the molecular characterization of three fatty acid synthase genes (fatty acid synthase RPRC000123, RPRC000269 and RPRC002909) in the Chagas disease vector, Rhodnius prolixus. Gene expression screening by reverse transcription quantitative PCR showed that RPRC000123 and RPRC002909 are expressed almost exclusively in the integument tissue whilst RPRC000269 is mostly expressed in the fat body and also in several body organs. Phylogenetic analysis, together with gene expression results, showed that RPRC000269, RPRC002909 and RPRC000123 are orthologues of Drosophila melanogaster fatty acid synthase 1 (FASN1), FASN2 and FASN3 genes, respectively. After RNA interference-mediated knockdown of RPRC000123, insects died immediately after moulting to the next developmental stage. However, mortality was prevented by placing the insects under saturated humidity conditions, suggesting that dehydration might play a role in the insects' death. Lipid analyses in RPRC000123-silenced insects showed reduced amounts of integument fatty acids and methyl-branched hydrocarbons, compared to controls. These data support an important role for FASN3 in the biosynthesis of the precursors to hydrocarbons that waterproof the insect cuticle.


Assuntos
Ácido Graxo Sintases/genética , Proteínas de Insetos/genética , Água/metabolismo , Animais , Ácido Graxo Sintases/metabolismo , Proteínas de Insetos/metabolismo , Tegumento Comum/fisiologia , Ninfa/crescimento & desenvolvimento , Ninfa/fisiologia , Filogenia , Rhodnius , Perda Insensível de Água
16.
PLoS One ; 14(3): e0213796, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30870522

RESUMO

Differences in the timing of exoskeleton melanization and sclerotization are evident when comparing eusocial and solitary bees. This cuticular maturation heterochrony may be associated with life style, considering that eusocial bees remain protected inside the nest for many days after emergence, while the solitary bees immediately start outside activities. To address this issue, we characterized gene expression using large-scale RNA sequencing (RNA-seq), and quantified cuticular hydrocarbon (CHC) through gas chromatography-mass spectrometry in comparative studies of the integument (cuticle plus its underlying epidermis) of two eusocial and a solitary bee species. In addition, we used transmission electron microscopy (TEM) for studying the developing cuticle of these and other three bee species also differing in life style. We found 13,200, 55,209 and 30,161 transcript types in the integument of the eusocial Apis mellifera and Frieseomelitta varia, and the solitary Centris analis, respectively. In general, structural cuticle proteins and chitin-related genes were upregulated in pharate-adults and newly-emerged bees whereas transcripts for odorant binding proteins, cytochrome P450 and antioxidant proteins were overrepresented in foragers. Consistent with our hypothesis, a distance correlation analysis based on the differentially expressed genes suggested delayed cuticle maturation in A. mellifera in comparison to the solitary bee. However, this was not confirmed in the comparison with F. varia. The expression profiles of 27 of 119 genes displaying functional attributes related to cuticle formation/differentiation were positively correlated between A. mellifera and F. varia, and negatively or non-correlated with C. analis, suggesting roles in cuticular maturation heterochrony. However, we also found transcript profiles positively correlated between each one of the eusocial species and C. analis. Gene co-expression networks greatly differed between the bee species, but we identified common gene interactions exclusively between the eusocial species. Except for F. varia, the TEM analysis is consistent with cuticle development timing adapted to the social or solitary life style. In support to our hypothesis, the absolute quantities of n-alkanes and unsaturated CHCs were significantly higher in foragers than in the earlier developmental phases of the eusocial bees, but did not discriminate newly-emerged from foragers in C. analis. By highlighting differences in integument gene expression, cuticle ultrastructure, and CHC profiles between eusocial and solitary bees, our data provided insights into the process of heterochronic cuticle maturation associated to the way of life.


Assuntos
Abelhas/genética , Epiderme/metabolismo , Epiderme/ultraestrutura , Hidrocarbonetos/análise , Proteínas de Insetos/genética , Tegumento Comum/fisiologia , Transcriptoma , Animais , Abelhas/crescimento & desenvolvimento , Feminino , Metamorfose Biológica
17.
Insect Biochem Mol Biol ; 108: 24-31, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30885802

RESUMO

Cuticle tanning occurs in insects immediately after hatching or molting. During this process, the cuticle becomes dark and rigid due to melanin deposition and protein crosslinking. In insects, different from mammals, melanin is synthesized mainly from dopamine, which is produced from DOPA by the enzyme DOPA decarboxylase. In this work, we report that the silencing of the RpAadc-2 gene, which encodes the putative Rhodnius prolixus DOPA decarboxylase enzyme, resulted in a reduction in nymph survival, with a high percentage of treated insects dying during the ecdysis process or in the expected ecdysis period. Those treated insects that could complete ecdysis presented a decrease in cuticle pigmentation and hardness after molting. In adult females, the knockdown of AADC-2 resulted in a reduction in the hatching of eggs; the nymphs that managed to hatch failed to tan the cuticle and were unable to feed. Despite the failure in cuticle tanning, knockdown of the AADC-2 did not increase the susceptibility to topically applied deltamethrin, a pyrethroid insecticide. Additionally, our results showed that the melanin synthesis pathway did not play a major role in the detoxification of the excess (potentially toxic) tyrosine from the diet, an essential trait for hematophagous arthropod survival after a blood meal.


Assuntos
Dopa Descarboxilase/fisiologia , Proteínas de Insetos/fisiologia , Tegumento Comum/fisiologia , Rhodnius/enzimologia , Rhodnius/crescimento & desenvolvimento , Animais , Dopa Descarboxilase/farmacologia , Feminino , Inativação Metabólica , Proteínas de Insetos/farmacologia , Inseticidas , Melaninas/metabolismo , Muda/fisiologia , Nitrilas , Pigmentação/fisiologia , Piretrinas , Reprodução , Rhodnius/genética , Tirosina/metabolismo
18.
J Therm Biol ; 80: 178-189, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30784484

RESUMO

Climatic factors, such as temperature variation, interfere with the survival of insects. To respond to these variations, insects have some specific characteristics. These include water content of the body, thickness of the lipid layer, as well as the qualitative and quantitative characteristics of cuticular chemical components. This study hypothesizes that different ant species respond to temperature changes in different ways and that such differences may be associated with cuticle hydrocarbons (CHCs) and fatty acids. As model ant species, Atta sexdens, Odontomachus bauri and Ectatomma brunneum were used for experimental analyses. Ants were submitted to a water bath for 5 h at different temperatures, and their CHCs and fatty acids were identified and quantified, followed by correlating these chemical compounds with temperature variations and the survival. Temperatures below 30 °C did not affect the survival of the three species. E. brunneum had a higher percentage of survival at temperatures above 30 °C. O. bauri was the most sensitive species with 100% mortality at 40 °C. Survival was found to be unrelated to any of the identified fatty acids. However, CHCs underwent significant quantitative and qualitative variation, as shown by an increased percentage of CHCs with longer chain length of linear alkanes at temperatures above 30 °C. These increase enables these ants to maintain the integrity of their cuticle and survive at temperatures above 30 °C. It can be concluded that the forager ants studied respond differently to temperature variation and that changes in the conformation of CHCs are in line with the ecological characteristics of the different studied species because, they vary in terms of diurnal/nocturnal foraging and types of environments foraged. Among the three species, E. brunneum foragers were found to be more active under adverse conditions and more tolerant to temperature variation with the correspondingly appropriate changes in CHCs composition.


Assuntos
Formigas/fisiologia , Hidrocarbonetos/análise , Tegumento Comum/fisiologia , Termotolerância , Animais , Ácidos Graxos/análise , Especificidade da Espécie , Temperatura
19.
Pest Manag Sci ; 75(7): 1808-1818, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30740870

RESUMO

BACKGROUND: Vector control is the main intervention in malaria control and elimination strategies. However, the development of insecticide resistance is one of the major challenges for controlling malaria vectors. Anopheles arabiensis populations in Ethiopia showed resistance against both DDT and the pyrethroid deltamethrin. Although an L1014F target-site resistance mutation was present in the voltage gated sodium channel of investigated populations, the levels of resistance indicated the presence of additional resistance mechanisms. In this study, we used genome-wide transcriptome profiling by RNAseq to assess differentially expressed genes between three deltamethrin and DDT resistant An. arabiensis field populations - Asendabo, Chewaka and Tolay - and two susceptible strains - Sekoru and Mozambique. RESULTS: Both RNAseq analysis and RT-qPCR showed that a glutathione-S-transferase, gstd3, and a cytochrome P450 monooxygenase, cyp6p4, were significantly overexpressed in the group of resistant populations compared to the susceptible strains, suggesting that the enzymes they encode play a key role in metabolic resistance against deltamethrin or DDT. Furthermore, a gene ontology enrichment analysis showed that expression changes of cuticle related genes were strongly associated with insecticide resistance. Although this did not translate in increased thickness of the procuticle, a higher cuticular hydrocarbon content was observed in a resistant population. CONCLUSION: Our transcriptome sequencing of deltamethrin and DDT resistant An. arabiensis populations from Ethiopia suggests non-target site resistance mechanisms and paves the way for further investigation of the role of cuticle composition in insecticide resistance of malaria vectors. © 2019 Society of Chemical Industry.


Assuntos
Anopheles/genética , Anopheles/metabolismo , DDT/farmacologia , Resistência a Inseticidas/genética , Nitrilas/farmacologia , Piretrinas/farmacologia , Animais , Sistema Enzimático do Citocromo P-450/efeitos dos fármacos , Sistema Enzimático do Citocromo P-450/metabolismo , Etiópia , Perfilação da Expressão Gênica , Glutationa Transferase/efeitos dos fármacos , Glutationa Transferase/metabolismo , Inativação Metabólica/genética , Inseticidas/metabolismo , Inseticidas/farmacologia , Tegumento Comum/fisiologia , Mosquitos Vetores/efeitos dos fármacos
20.
Elife ; 82019 01 08.
Artigo em Inglês | MEDLINE | ID: mdl-30616714

RESUMO

Changes of body color have important effects for animals in adapting to variable environments. The migratory locust exhibits body color polyphenism between solitary and gregarious individuals, with the former displaying a uniform green coloration and the latter having a prominent pattern of black dorsal and brown ventral surface. However, the molecular mechanism underlying the density-dependent body color changes of conspecific locusts remain largely unknown. Here, we found that upregulation of ß-carotene-binding protein promotes the accumulation of red pigment, which added to the green color palette present in solitary locusts changes it from green to black, and that downregulation of this protein led to the reverse, changing the color of gregarious locusts from black to green. Our results provide insight that color changes of locusts are dependent on variation in the red ß-carotene pigment binding to ßCBP. This finding of animal coloration corresponds with trichromatic theory of color vision.


Assuntos
Gafanhotos/fisiologia , Proteínas de Insetos/metabolismo , Pigmentação/fisiologia , beta Caroteno/metabolismo , Animais , Comportamento Animal/fisiologia , Cor , Gafanhotos/genética , Gafanhotos/ultraestrutura , Proteínas de Insetos/genética , Tegumento Comum/fisiologia , Densidade Demográfica
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