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1.
PLoS Genet ; 16(8): e1008976, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32866141

RESUMO

Neural circuitry for mating and reproduction resides within the terminal segments of central nervous system (CNS) which express Hox paralogous group 9-13 (in vertebrates) or Abdominal-B (Abd-B) in Drosophila. Terminal neuroblasts (NBs) in A8-A10 segments of Drosophila larval CNS are subdivided into two groups based on expression of transcription factor Doublesex (Dsx). While the sex specific fate of Dsx-positive NBs is well investigated, the fate of Dsx-negative NBs is not known so far. Our studies with Dsx-negative NBs suggests that these cells, like their abdominal counterparts (in A3-A7 segments) use Hox, Grainyhead (Grh) and Notch to undergo cell death during larval development. This cell death also happens by transcriptionally activating RHG family of apoptotic genes through a common apoptotic enhancer in early to mid L3 stages. However, unlike abdominal NBs (in A3-A7 segments) which use increasing levels of resident Hox factor Abdominal-A (Abd-A) as an apoptosis trigger, Dsx-negative NBs (in A8-A10 segments) keep the levels of resident Hox factor Abd-B constant. These cells instead utilize increasing levels of the temporal transcription factor Grh and a rise in Notch activity to gain apoptotic competence. Biochemical and in vivo analysis suggest that Abdominal-A and Grh binding motifs in the common apoptotic enhancer also function as Abdominal-B and Grh binding motifs and maintains the enhancer activity in A8-A10 NBs. Finally, the deletion of this enhancer by the CRISPR-Cas9 method blocks the apoptosis of Dsx-negative NBs. These results highlight the fact that Hox dependent NB apoptosis in abdominal and terminal regions utilizes common molecular players (Hox, Grh and Notch), but seems to have evolved different molecular strategies to pattern CNS.


Assuntos
Apoptose/genética , Proteínas de Ligação a DNA/genética , Proteínas de Drosophila/genética , Receptores Notch/genética , Fatores de Transcrição/genética , Abdome/crescimento & desenvolvimento , Animais , Sistema Nervoso Central/crescimento & desenvolvimento , Drosophila melanogaster/genética , Drosophila melanogaster/crescimento & desenvolvimento , Feminino , Regulação da Expressão Gênica no Desenvolvimento/genética , Larva/genética , Larva/crescimento & desenvolvimento , Masculino , Células-Tronco Neurais/metabolismo , Sequências Reguladoras de Ácido Nucleico/genética
2.
Nat Commun ; 11(1): 4505, 2020 09 09.
Artigo em Inglês | MEDLINE | ID: mdl-32908148

RESUMO

Evidence for transgenerational inheritance of epigenetic information in vertebrates is scarce. Aberrant patterns of DNA methylation in gametes may set the stage for transmission into future generations. Here, we describe a viable hypomorphic allele of dnmt1 in zebrafish that causes widespread demethylation of CpG dinucleotides in sperm and somatic tissues. We find that homozygous mutants are essentially normal, with the exception of drastically impaired lymphopoiesis, affecting both larval and adult phases of T cell development. The phenotype of impaired larval (but not adult) T cell development is transmitted to subsequent generations by genotypically wildtype fish. We further find that about 200 differentially methylated regions in sperm DNA of transmitting and non-transmitting males, including hypermethylated sites associated with runx3 and rptor genes, whose reduced activities are associated with impaired larval T cell development. Our results indicate a particular sensitivity of larval T cell development to transgenerationally inherited epimutations.


Assuntos
Diferenciação Celular/genética , Genes Recessivos , Larva/crescimento & desenvolvimento , Linfopoese/genética , Linfócitos T/fisiologia , Alelos , Animais , Animais Geneticamente Modificados , Subunidade alfa 3 de Fator de Ligação ao Core/genética , DNA (Citosina-5-)-Metiltransferase 1/genética , DNA (Citosina-5-)-Metiltransferase 1/metabolismo , Metilação de DNA , Epigênese Genética , Feminino , Genética , Larva/citologia , Masculino , Mutação , Proteína Regulatória Associada a mTOR/genética , Espermatozoides/metabolismo , Peixe-Zebra/genética , Proteínas de Peixe-Zebra/genética , Proteínas de Peixe-Zebra/metabolismo
3.
PLoS Genet ; 16(8): e1008942, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32764744

RESUMO

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


Assuntos
Proteínas de Drosophila/genética , Metamorfose Biológica/genética , MicroRNAs/genética , Regeneração Nervosa/genética , Proteínas Repressoras/genética , Animais , Dendritos/genética , Dendritos/fisiologia , Drosophila melanogaster/genética , Regulação da Expressão Gênica no Desenvolvimento , Larva/genética , Larva/crescimento & desenvolvimento , Células Receptoras Sensoriais/metabolismo
4.
PLoS One ; 15(8): e0236509, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32785243

RESUMO

Knowledge about population genetic structure and dispersal capabilities is important for the development of targeted management strategies for agricultural pest species. The apple fruit moth, Argyresthia conjugella (Lepidoptera, Yponomeutidae), is a pre-dispersal seed predator. Larvae feed on rowanberries (Sorbus aucuparia), and when rowanberry seed production is low (i.e., inter-masting), the moth switches from laying eggs in rowanberries to apples (Malus domestica), resulting in devastating losses in apple crops. Using genetic methods, we investigated if this small moth expresses any local genetic structure, or alternatively if gene flow may be high within the Scandinavian Peninsula (~850.000 km2, 55o - 69o N). Genetic diversity was found to be high (n = 669, mean He = 0.71). For three out of ten tetranucleotide STRs, we detected heterozygote deficiency caused by null alleles, but tests showed little impact on the overall results. Genetic differentiation between the 28 sampling locations was very low (average FST = 0.016, P < 0.000). Surprisingly, we found that all individuals could be assigned to one of two non-geographic genetic clusters, and that a third, geographic cluster was found to be associated with 30% of the sampling locations, with weak but significant signals of isolation-by-distance. Conclusively, our findings suggest wind-aided dispersal and spatial synchrony of both sexes of the apple fruit moth over large areas and across very different climatic zones. We speculate that the species may recently have had two separate genetic origins caused by a genetic bottleneck after inter-masting, followed by rapid dispersal and homogenization of the gene pool across the landscape. We suggest further investigations of spatial genetic similarities and differences of the apple fruit moth at larger geographical scales, through life-stages, across inter-masting, and during attacks by the parasitoid wasp (Microgaster politus).


Assuntos
Genética Populacional , Repetições de Microssatélites/genética , Mariposas/genética , Oviposição/fisiologia , Animais , Frutas/genética , Fluxo Gênico , Variação Genética , Larva/genética , Larva/crescimento & desenvolvimento , Malus/crescimento & desenvolvimento , Malus/parasitologia , Mariposas/patogenicidade , Mariposas/fisiologia , Oviposição/genética , Dispersão de Sementes/genética , Sorbus/genética , Sorbus/parasitologia
5.
Mol Genet Genomics ; 295(6): 1517-1528, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32803300

RESUMO

Increasing studies have revealed strong links among gut microbiota, health status, and shrimp development, but they mainly focus on the microbiota of Pacific white shrimp, Penaeus vannamei, during life stages from juveniles to adults. Little is known about shrimp microbiota dynamics at early developmental stages. In this study, with an aim to profile shrimp microbiota and its dynamics at stages nauplius, zoea, mysis, and early postlarva, we conducted a survey for the successful breeding processes in a commercial hatchery in China, sampled 33 samples including larval/postlarval shrimp, suspended substance in rearing water (SSRW), and nutrition supplements (i.e., algae and brine shrimp larvae) at stages N5, Z2, M2, and P2. The associated bacterial communities were sequenced and comparatively analyzed using high-throughput sequencing of bacterial 16S rRNA genes. Our case study results showed that bacterial community structures and compositions were strikingly different at stages N5, Z2, and P2, indicating the shift of microbiota at the three stages. Many taxa within Gamma-, Alphaproteobacteria, and Flavobacteriia classes were observed to be stage-specifically abundant and identified as taxonomic biomarkers potentially used to differentiate among shrimp at different early developmental stages. Summing up, these results shed light on larval/postlarval microbiota and its dynamics at different early developmental stages, highlighting the potential roles of shrimp development in microbiota formation and shifting.


Assuntos
Bactérias/classificação , Bactérias/genética , Larva/microbiologia , Microbiota/genética , Penaeidae/microbiologia , RNA Ribossômico 16S/análise , Animais , Bactérias/isolamento & purificação , Sequenciamento de Nucleotídeos em Larga Escala , Larva/crescimento & desenvolvimento , Metagenômica , Penaeidae/crescimento & desenvolvimento , Tanques , RNA Ribossômico 16S/genética
6.
PLoS One ; 15(8): e0238154, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32853236

RESUMO

Black soldier fly (BSF) (Hermetia illucens L.) is one of the most efficient bio-waste recyclers. Although, waste substrate amendments with biochar or gypsum during composting process are known to enhance nutrient retention, their impact on agro-industrial waste have not been documented. Hence, this study focuses on a comparative effect of agro-industrial waste amended with biochar and gypsum on BSF larval performance, waste degradation, and nitrogen (N) and potassium retention in frass fertilizer. Brewery spent grain was amended with biochar or gypsum at 0, 5, 10, 15 and 20% to determine the most effective rates of inclusion. Amending feedstock with 20% biochar significantly increased wet (89%) and dried (86%) larval yields than the control (unamended feedstock). However, amendment with 15% gypsum caused decrease in wet (34%) and dried (30%) larval yields but conserved the highest amount of N in frass. Furthermore, the inclusion of 20% biochar recorded the highest frass fertilizer yield and gave a 21% increase in N retention in frass fertilizer, while biomass conversion rate was increased by 195% compared to the control. Feedstock amendment with 5% biochar had the highest waste degradation efficiency. Potassium content in frass fertilizer was also significantly enhanced with biochar amendment. At maturity, frass compost with more than 10% inclusion rate of biochar had the highest cabbage seed germination indices (>100%). The findings of this study revealed that initial composting of biochar amended feedstocks using BSF larvae can significantly shorten compost maturity time to 5 weeks with enhanced nutrient recycling compared to the conventional composting methods.


Assuntos
Carvão Vegetal/química , Larva/crescimento & desenvolvimento , Simuliidae/crescimento & desenvolvimento , Animais , Biomassa , Compostagem/métodos , Fertilizantes , Resíduos Industriais , Nitrogênio/química , Solo/química
7.
Parasitol Res ; 119(10): 3285-3296, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32812144

RESUMO

The taxonomy of Hysterothylacium genus in Mediterranean waters remains incomplete and unresolved. The aim of the current study was to investigate the morphological and molecular identification of selected species of Hysterothylacium larvae in marine fish from the Tunisian Mediterranean coasts. A total of 192 marine fish samples were examined. In total, thirty-seven third-stage larvae of Hysterothylacium were morphologically identified as Hysterothylacium type V. In the present study, representatives of this type from the Mediterranean Sea were genetically characterized for the first time by sequencing the rDNA ITS (ITS1-5.8S-ITS2) regions and mtDNA cox2 gene. This study represents the first report of Hysterothylacium type V from the Mediterranean Sea. We also report Mullus barbatus, M. surmuletus, and Pagellus erythrinus as new hosts for this larval type. Based upon molecular and phylogenetic analyses considering the rDNA ITS regions, the Hysterothylacium type V described here was classified as a new genotype, named Genotype B. The valid genetic data of the described Hysterothylacium type V in the present study can be used to establish the phylogenetic relationships among Hysterothylacium species from the Mediterranean Sea and worldwide for future research.


Assuntos
Infecções por Ascaridida/veterinária , Ascaridoidea/classificação , Ascaridoidea/crescimento & desenvolvimento , Doenças dos Peixes/parasitologia , Peixes/parasitologia , Animais , Infecções por Ascaridida/parasitologia , Ascaridoidea/anatomia & histologia , Ascaridoidea/genética , DNA Mitocondrial/genética , DNA Espaçador Ribossômico/genética , Peixes/classificação , Genes de Helmintos/genética , Genótipo , Larva/anatomia & histologia , Larva/classificação , Larva/genética , Larva/crescimento & desenvolvimento , Mar Mediterrâneo , Filogenia
8.
PLoS One ; 15(8): e0235912, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32776931

RESUMO

Small heat shock proteins (sHsps) function in the response of insects to abiotic stress; however, their role in response to biotic stress has been under-investigated. Mythimna separata, the oriental armyworm, is polyphenetic and exhibits gregarious and solitary phases in response to high and low population density, respectively. In this study, three genes were identified encoding sHsps, namely MsHsp19.7, MsHsp19.8 and MsHsp21.4, and expression levels in solitary and gregarious M. separata were compared. The deduced protein sequences of the three MsHsps had molecular weights of 19.7, 19.8 and 21.4 kDa, respectively, and contained a conserved α-crystalline domain. Real-time PCR analyses revealed that the three sHsps were transcribed in all developmental stages and were dramatically up-regulated at the 6th larval stage in gregarious individuals. Expression of the three MsHsps was variable in different tissues of 6th instar larvae, but exhibited consistent up- and down-regulation in the hindgut and Malpighian tubules of gregarious individuals, respectively. In addition, MsHsp19.7 and MsHsp19.8 were significantly induced when solitary forms were subjected to crowding for 36 h, but all three MsHsps were down-regulated when gregarious forms were isolated. Our findings suggest that population density functions as a stress factor and impacts MsHsps expression in M. separata.


Assuntos
Proteínas de Choque Térmico Pequenas/genética , Proteínas de Insetos/genética , Mariposas/genética , Animais , Aglomeração , Regulação da Expressão Gênica , Larva/genética , Larva/crescimento & desenvolvimento , Mariposas/crescimento & desenvolvimento
9.
PLoS One ; 15(7): e0237094, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32735582

RESUMO

Western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), is a major pest of corn in the United States. Transgenic corn expressing insecticidal proteins derived from the bacterium Bacillus thuringiensis (Bt) is an important tool used to manage rootworm populations. However, field-evolved resistance to Bt threatens this technology. In areas where resistance is present, resistant individuals may travel from one field to a neighboring field, spreading resistance alleles. An important question that remains to be answered is the extent to which greater-than-expected root injury (i.e., >1 node of injury) to Cry3Bb1 corn from western corn rootworm is associated with rootworm abundance, root injury, and levels of resistance in neighboring fields. To address this question, fields with a history of greater-than-expected injury to Cry3Bb1 corn (focal fields) and surrounding fields (< 2.2 km from focal fields) were examined to quantify rootworm abundance, root injury, and resistance to Cry3Bb1 corn. Additionally, use of Bt corn and soil insecticide use for the previous six years were quantified for each field. Resistance to Cry3Bb1 was present in all fields assayed, even though focal fields had grown more Cry3 corn and less non-Bt corn than surrounding fields. This finding implies that some movement of resistance alleles had occurred between focal fields and surrounding fields. Overall, our data suggest that resistance to Cry3Bb1 in the landscape has been influenced by both local rootworm movement and field-level management tactics.


Assuntos
Endotoxinas/genética , Resistência a Inseticidas/genética , Zea mays/genética , Animais , Bacillus thuringiensis/genética , Bacillus thuringiensis/metabolismo , Besouros/crescimento & desenvolvimento , Produtos Agrícolas/genética , Genes Bacterianos , Larva/crescimento & desenvolvimento , Controle Biológico de Vetores , Raízes de Plantas , Plantas Geneticamente Modificadas
10.
PLoS One ; 15(8): e0237259, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32760156

RESUMO

Spent mushroom substrate is made from the waste remaining after the harvest of mushrooms. Here, we evaluated the potential of five spent edible fungi (Auricularia cornea, Lentinus edodes, Pleurotus eryngii, P. citrinopileatus and P. ostreatus) substrates as feed sources for Tenebrio molitor larvae. Young larvae did not survive on any substrate except the spent L. edodes substrate (36.7%). The survival rates in young larvae were similar among the different diets in which wheat bran or rice bran was replaced with 0, 20, 30, 40, 50, or 60% spent L. edodes substrate. The weights of the surviving larvae were decreased only when 70% of wheat bran and > 40% of rice bran was replaced with spent L. edodes substrate. In addition, the middle-aged larvae fed wheat bran only were significantly larger than those fed diets with 30~60% spent L. edodes substrate in dry feed, but the larvae of all treatments failed to pupate. Whereas the green feed was added in dry feed, there were no significant differences in pupal weight, pupation rate, pupal duration, adult emergence, or deformed adults among the three treatments in middle-aged larvae that were fed on diets containing 0, 30, or 40% spent L. edodes substrate. Collectively, these results suggest that spent L. edodes substrate has considerable potential to be used as a partial replacement (< 40%) of conventional feed for T. molitor, and spent mushroom substrate waste may be recycled as feed material for resource insects.


Assuntos
Agaricales/metabolismo , Ração Animal , Tenebrio/fisiologia , Ração Animal/microbiologia , Fenômenos Fisiológicos da Nutrição Animal , Animais , Larva/crescimento & desenvolvimento , Larva/fisiologia , Tenebrio/crescimento & desenvolvimento
11.
PLoS One ; 15(8): e0237167, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32764780

RESUMO

The zebrafish Danio rerio is a valuable and common model for scientists in the fields of genetics and developmental biology. Since zebrafish are also amenable to genetic manipulation, modelling of human diseases or behavioral experiments have moved into the focus of zebrafish research. Consequently, gene expression data beyond embryonic and larval stages become more important, yet there is a dramatic knowledge gap of gene expression beyond day four of development. Like in other model organisms, the visualization of spatial and temporal gene expression by whole mount in situ hybridization (ISH) becomes increasingly difficult when zebrafish embryos develop further and hence the growing tissues become dense and less permeable. Here we introduce a modified method for whole mount ISH, which overcomes these penetration and detection problem. The method is an all in one solution that enables the detection and visualization of gene expression patterns up to the late larval stage in a 3D manner without the need for tissue sectioning and offers a valuable extension for whole mount ISH by immunohistochemistry in the zebrafish field.


Assuntos
Biologia do Desenvolvimento/métodos , Desenvolvimento Embrionário/genética , Regulação da Expressão Gênica no Desenvolvimento , Peixe-Zebra/crescimento & desenvolvimento , Animais , Embrião não Mamífero , Imuno-Histoquímica , Hibridização In Situ , Larva/genética , Larva/crescimento & desenvolvimento , Modelos Animais , Peixe-Zebra/genética
12.
PLoS One ; 15(8): e0237737, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32822355

RESUMO

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


Assuntos
Ambystoma/crescimento & desenvolvimento , Urodelos/crescimento & desenvolvimento , Animais , Tamanho Corporal , Espécies em Perigo de Extinção , Larva/crescimento & desenvolvimento , Metamorfose Biológica , Modelos Biológicos
13.
PLoS One ; 15(8): e0237662, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32822370

RESUMO

The larvae of Drosophila melanogaster grow rapidly through use of a highly truncated cell cycle in which mitosis is entirely eliminated. The Drosophila homolog of the protooncogene transcription factor Myc plays a major role in promoting this endopolyploid (EP) growth. We have previously determined that the gene jim lovell (lov), which encodes a member of the BTB/POZ (Bric-a-brac, Tramtrack, Broad/Pox virus zinc finger) domain family of transcription factors, is also required for EP growth in one larval tissue, the trachea. Here we show that lov promotes EP growth in three further tissues indicating a fundamental role in this process. However, epistasis experiments revealed heterogeneity in lov's action in these tissues. Whereas in the tracheae and salivary glands lov acts downstream of Myc, in the fat body, reduced expression of lov does not impede the action of Myc, indicating an upstream action for the gene. We show here that lov's regulation of the gene uninflatable (uif) in the tracheae is a component of this difference. uif is required for tracheal EP growth downstream of Myc and lov but has no equivalent role in the fat body. Although Uif is a transmembrane component of the plasma membrane in the tracheae, its action downstream of Myc suggests an intracellular role for the protein in the tracheae. In addition to regulating uif expression in some tissues we also show that lov locates to the nucleolus, indicating it can function in both polymerase I and polymerase II transcriptional events. Our major finding is that tissue-specific mechanisms can interact with universal growth promotion by Myc to generate the individual endopolyploid organs of the larvae.


Assuntos
Proteínas de Drosophila/metabolismo , Drosophila melanogaster/metabolismo , Fatores de Transcrição/metabolismo , Animais , Proteínas de Drosophila/análise , Proteínas de Drosophila/genética , Drosophila melanogaster/genética , Drosophila melanogaster/crescimento & desenvolvimento , Epistasia Genética , Larva/genética , Larva/crescimento & desenvolvimento , Larva/metabolismo , Proteínas de Membrana/análise , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Poliploidia , Fatores de Transcrição/análise , Fatores de Transcrição/genética
14.
Ecotoxicol Environ Saf ; 204: 111052, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32739675

RESUMO

Transgenerational effects on sensitivity to pesticides are poorly studied. This study investigated the transgenerational influences of maternal body mass in the major pest moth Spodoptera littoralis, with a focus on sensitivity to chlorpyrifos pesticide. In 147 clutches of a laboratory strain of S. littoralis, we compared larval mortality between control larvae and larvae treated with chlorpyrifos. Because of the classic positive relationships between offspring size and maternal size and between offspring size and offspring quality, sensitivity to chlorpyrifos was predicted to be lower in larvae of larger mothers. Surprisingly, we found the opposite result, with higher pesticide toxicity in larvae of larger mothers. This result is partly explained by the lack of a relationship between larval mass and larval sensitivity to chlorpyrifos. This means that another offspring characteristic linked to maternal size should have affected larval sensitivity to chlorpyrifos. More generally, knowledge of the effects of the traits and ecological environments of mothers on offspring sensitivity to pesticides remains limited. Ecotoxicologists should pay more attention to such maternal effects on sensitivity to pesticides, both in pests and non-target species.


Assuntos
Clorpirifos/toxicidade , Epigênese Genética , Resistência a Inseticidas/genética , Inseticidas/toxicidade , Spodoptera/efeitos dos fármacos , Animais , Peso Corporal/efeitos dos fármacos , Feminino , Larva/efeitos dos fármacos , Larva/genética , Larva/crescimento & desenvolvimento , Longevidade/efeitos dos fármacos , Exposição Materna , Spodoptera/genética , Spodoptera/crescimento & desenvolvimento
15.
Ecotoxicol Environ Saf ; 204: 111034, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32758695

RESUMO

Trehalose is the major blood sugar in insects; it not only serves as an energy source but also plays important roles in physiological responses to adverse conditions. However, only a few studies have explored the effects of heavy metal exposure stress on trehalose metabolism in insects. Therefore, in this study, we examined the effects of cadmium stress on changes in trehalose metabolism in Aedes albopictus. Three concentrations of cadmium (0.005, 0.01, and 0.1 mg/L) were selected for evaluation of long-term stress in Ae. albopictus (from eggs to adults); Ae. albopictus in double-distilled water was used as the control group. The trehalose and glucose contents, trehalase activity, and trehalose metabolism-related gene expression were determined. The effects of long-term cadmium exposure on growth, development, and reproduction were also assessed. Trehalose contents were increased, whereas glucose contents and trehalase activity were decreased in Ae. albopictus following long-term exposure to low concentrations of cadmium compared with those in untreated individuals. Moreover, the expression of trehalose-6-phosphate synthase was upregulated, and that of trehalase was downregulated, indicating that Ae. albopictus may enhance trehalose synthesis to resist cadmium stress. Cadmium exposure also caused Ae. albopictus individuals to become smaller with a longer developmental duration, whereas both reproduction and hatching rates of the offspring were decreased compared with those in the control group. Our findings demonstrated that cadmium exposure affected the morphology, physiology, and biochemistry of Ae. albopictus. These findings also confirmed the role of trehalose in the response of Ae. albopictus to cadmium stress, providing insights into the effects of heavy metal stress on trehalose metabolism in an insect model.


Assuntos
Aedes/efeitos dos fármacos , Cádmio/efeitos adversos , Trealose/metabolismo , Poluentes Químicos da Água/efeitos adversos , Aedes/crescimento & desenvolvimento , Aedes/metabolismo , Animais , Feminino , Larva/efeitos dos fármacos , Larva/crescimento & desenvolvimento , Larva/metabolismo , Óvulo/efeitos dos fármacos , Óvulo/crescimento & desenvolvimento , Óvulo/metabolismo , Pupa/efeitos dos fármacos , Pupa/crescimento & desenvolvimento , Pupa/metabolismo
16.
PLoS Negl Trop Dis ; 14(8): e0008415, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32804951

RESUMO

Basic and translational research on loiasis, a filarial nematode infection of medical importance, is impeded by a lack of suitable Loa loa infection models and techniques of obtaining and culturing life cycle stages. We describe the development of a new method for routine production of infective third-stage larvae (L3) of L. loa from the natural intermediate arthropod vector host, Chrysops silacea, following experimental infection with purified microfilariae. At 14-days post-infection of C. silacea, the fly survival rate was 43%. Survival was significantly higher in flies injected with 50 mf (55.2%) than those that received 100 mf (31.0%). However, yield per surviving fly and total yield of L3 was markedly higher in the group of flies inoculated with 100 mf (3474 vs 2462 L3 produced). The abdominal segment hosted the highest percentage recovery of L3 (47.7%) followed by head (34.5%) and thorax (17.9%). L. loa larval survival was higher than 90% after 30 days of in vitro culture. The in vitro moulting success rate to the L4 larval stage was 59.1%. After experimental infection of RAG2-/-IL-2γc-/-mice, the average L. loa juvenile adult worm recovery rate was 10.5% at 62 dpi. More than 87% of the worms were recovered from the muscles and subcutaneous tissues. Worms recovered measured an average 24.3 mm and 11.4 mm in length for females (n = 5) and males (n = 5), respectively. In conclusion, L. loa mf injected into C. silacea intrathoracically develop into infective larvae that remain viable and infective comparable to L3 obtained through natural feeding on the human host. This technique further advances the development of a full laboratory life cycle of L. loa where mf derived from experimentally-infected animals may be utilized to passage life cycle generations via intrathoracic injections of wild-caught vector hosts.


Assuntos
Dípteros/parasitologia , Vetores de Doenças , Larva/parasitologia , Loa/isolamento & purificação , Loíase/parasitologia , Animais , Modelos Animais de Doenças , Feminino , Humanos , Larva/crescimento & desenvolvimento , Estágios do Ciclo de Vida , Loa/citologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Microfilárias , Taxa de Sobrevida
17.
Rev Bras Parasitol Vet ; 29(2): e022819, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32609247

RESUMO

The aim of this study was to evaluate the efficiency of different substrates for larval development of Ctenocephalides felis felis during its biological cycle. Eight hundred eggs of C. felis felis from a flea maintenance colony were used. Different diets were formulated, in which the main substrates were meat flour, powdered milk, sugar, lyophilized bovine blood, tick metabolites and lyophilized egg. The flea eggs were placed in test tubes (10 per tube) and approximately 2 g of the diet to be tested was added to each tube. There were 10 replicates for each substrate. After 28 days, each tube was evaluated individually for the presence of pupae and emerged adults. The following percentages of the larvae completed the cycle to the adult stage: 67% in diets containing tick metabolites; 55%, meat flour; 39%, dehydrated bovine blood; 14%, powdered milk; and less than 1% in diets containing sugar, lyophilized bovine blood, lyophilized egg or wheat bran. It was concluded that among the diets tested, the one constituted by tick metabolites as the substrate was shown to be the most satisfactory for maintaining a laboratory colony of C. felis felis, followed by the one containing meat flour.


Assuntos
Ctenocephalides , Técnicas de Cultura , Animais , Gatos , Ctenocephalides/crescimento & desenvolvimento , Técnicas de Cultura/métodos , Larva/crescimento & desenvolvimento
18.
PLoS Genet ; 16(7): e1008907, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32667927

RESUMO

Holometabolous insects have distinct larval, pupal, and adult stages. The pupal stage is typically immobile and can be subject to predation, but cocoon offers pupal protection for many insect species. The cocoon provides a space in which the pupa to adult metamorphosis occurs. It also protects the pupa from weather, predators and parasitoids. Silk protein is a precursor of the silk used in cocoon construction. We used the silkworm as a model species to identify genes affecting silk protein synthesis and cocoon construction. We used quantitative genetic analysis to demonstrate that ß-1,4-N-acetylglucosaminidase 1 (BmGlcNase1) is associated with synthesis of sericin, the main composite of cocoon. BmGlcNase1 has an expression pattern coupled with silk gland development and cocoon shell weight (CSW) variation, and CSW is an index of the ability to synthesize silk protein. Up-regulated expression of BmGlcNase1 increased sericin content by 13.9% and 22.5% while down-regulation reduced sericin content by 41.2% and 27.3% in the cocoons of females and males, respectively. Genomic sequencing revealed that sequence variation upstream of the BmGlcNase1 transcriptional start site (TSS) is associated with the expression of BmGlcNase1 and CSW. Selective pressure analysis showed that GlcNase1 was differentially selected in insects with and without cocoons (ω1 = 0.044 vs. ω2 = 0.154). This indicates that this gene has a conserved function in the cocooning process of insects. BmGlcNase1 appears to be involved in sericin synthesis and silkworm cocooning.


Assuntos
Acetilglucosaminidase/genética , Bombyx/genética , Cruzamento , Domesticação , Animais , Bombyx/fisiologia , Feminino , Regulação da Expressão Gênica/genética , Larva/genética , Larva/crescimento & desenvolvimento , Masculino , Biossíntese de Proteínas/genética , Seda/genética
19.
Nat Commun ; 11(1): 3614, 2020 07 17.
Artigo em Inglês | MEDLINE | ID: mdl-32681015

RESUMO

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


Assuntos
Peixes/crescimento & desenvolvimento , Larva/crescimento & desenvolvimento , Praguicidas/toxicidade , Glândula Tireoide/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Animais , Clorpirifos/toxicidade , Poluição Ambiental/efeitos adversos , Metamorfose Biológica/efeitos dos fármacos , Estresse Fisiológico/efeitos dos fármacos , Glândula Tireoide/metabolismo , Hormônios Tireóideos/metabolismo
20.
BMC Evol Biol ; 20(1): 79, 2020 06 29.
Artigo em Inglês | MEDLINE | ID: mdl-32600301

RESUMO

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


Assuntos
Evolução Biológica , Cabeça/anatomia & histologia , Insetos/anatomia & histologia , Insetos/crescimento & desenvolvimento , Metamorfose Biológica , Animais , Cabeça/diagnóstico por imagem , Imageamento Tridimensional , Larva/anatomia & histologia , Larva/crescimento & desenvolvimento , Músculos/anatomia & histologia , Pupa/anatomia & histologia , Pupa/crescimento & desenvolvimento , Tomografia Computadorizada por Raios X
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