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1.
Science ; 367(6480): 851-852, 2020 02 21.
Artigo em Inglês | MEDLINE | ID: mdl-32079759
2.
Biol Bull ; 237(2): 170-179, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31714852

RESUMO

Post-embryonic diapause in copepods is an adaptation that allows species in the copepod family Calanidae to thrive in high-latitude environments by transforming a short spring phytoplankton bloom into large numbers of lipid-rich individuals capable of surviving a long period of starvation. The copepods, with their high-energy lipid reservoirs, are a critical food source for higher trophic levels, making the Calanidae a key component of high-latitude marine ecosystems. The physiological ecology of the developmental program remains poorly understood. However, new studies using high-throughput RNA sequencing approaches are giving detailed access to physiological status by generating gene expression profiles for both field-collected and laboratory-incubated individuals. These are beginning to characterize the diapause phenotype, elucidate the transcriptional and physiological progression through the diapause program, and illustrate the effects of organism-environment interactions. This paper reviews gene expression profiling studies on the life cycle and diapause program of Neocalanus flemingeri Miller (1988) that were conducted as part of a long-term observation program in the northern Gulf of Alaska. It summarizes recent findings and relates them to the ecology of this species and to that of other calanids.


Assuntos
Copépodes , Diapausa , Animais , Ecossistema , Fitoplâncton , Transcriptoma
3.
Biol Bull ; 237(2): 76-89, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31714854

RESUMO

Diapause at depth is considered an integral part of the life cycle of Calanus copepods, but few studies have focused on the Arctic species Calanus glacialis and Calanus hyperboreus. By analyzing a large set of pan-arctic observational data compiled from multiple sources, we show that Arctic Calanus has a broad depth distribution in winter, indicating that diapause at depth is a facultative strategy. Both species' vertical distributions tend to deepen in winter and to be deeper and broader with increasing bottom depth, while individuals are aggregated closer to the sea floor in shallow areas. These results indicate that Arctic Calanus species pursue a relatively deep diapause habitat but are topographically blocked on the shelves. Interspecific differences in depth distribution during diapause suggest the importance of predation. The larger C. hyperboreus has a deeper diapause depth than C. glacialis, potentially to alleviate predation pressure or as a result of predation loss near the surface. Moreover, the mean depth of C. hyperboreus in winter is negatively associated with latitude, indicating a shoaling of the diapause population in the central Arctic Ocean where predation pressure is lower. Our results suggest a complex diapause behavior by Arctic Calanus, with implications for our view of the species' roles in Arctic ecosystems.


Assuntos
Copépodes , Diapausa , Animais , Regiões Árticas , Ecossistema , Estações do Ano
4.
Biol Bull ; 237(2): 180-191, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31714855

RESUMO

Dormancy and diapause are key adaptations in many organisms, enabling survival of temporarily or seasonally unsuitable environmental conditions. In this review, we examine how our understanding of programmed developmental and metabolic arrest during diapause intersects with the increasing body of knowledge about animal co-development and co-evolution with microorganisms. Host-microbe interactions are increasingly understood to affect a number of metabolic, physiological, developmental, and behavioral traits and to mediate adaptations to various environments. Therefore, it is timely to consider how microbial factors might affect the expression and evolution of diapause in a changing world. We examine how a range of host-microbe interactions, from pathogenic to mutualistic, may have an impact on diapause phenotypes. Conversely, we examine how the discontinuities that diapause introduces into animal host generations can affect the ecology of microbial communities and the evolution of host-microbe interactions. We discuss these issues as they relate to physiology, evolution of development, local adaptation, disease ecology, and environmental change. Finally, we outline research questions that bridge the historically distinct fields of seasonal ecology and host-microbe interactions.


Assuntos
Diapausa , Microbiota , Adaptação Fisiológica , Animais , Fenótipo , Simbiose
5.
Biol Bull ; 237(2): 90-110, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31714858

RESUMO

Calanus finmarchicus and Calanus glacialis are keystone zooplankton species in North Atlantic and Arctic marine ecosystems because they form a link in the trophic transfer of nutritious lipids from phytoplankton to predators on higher trophic levels. These calanoid copepods spend several months of the year in deep waters in a dormant state called diapause, after which they emerge in surface waters to feed and reproduce during the spring phytoplankton bloom. Disruption of diapause timing could have dramatic consequences for marine ecosystems. In the present study, Calanus C5 copepodites were collected in a Norwegian fjord during diapause and were subsequently experimentally exposed to the water-soluble fraction of a naphthenic North Sea crude oil during diapause termination. The copepods were sampled repeatedly while progressing toward adulthood and were analyzed for utilization of lipid stores and for differential expression of genes involved in lipid metabolism. Our results indicate that water-soluble fraction exposure led to a temporary pause in lipid catabolism, suggested by (i) slower utilization of lipid stores in water-soluble fraction-exposed C5 copepodites and (ii) more genes in the ß-oxidation pathway being downregulated in water-soluble fraction-exposed C5 copepodites than in the control C5 copepodites. Because lipid content and/or composition may be an important trigger for termination of diapause, our results imply that the timing of diapause termination and subsequent migration to the surface may be delayed if copepods are exposed to oil pollution during diapause or diapause termination. This delay could have detrimental effects on ecosystem dynamics.


Assuntos
Copépodes , Diapausa , Petróleo , Animais , Regiões Árticas , Ecossistema , Metabolismo dos Lipídeos
6.
PLoS Biol ; 17(10): e3000452, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31589601

RESUMO

Neurons have a lifespan that parallels that of the organism and are largely irreplaceable. Their unusually long lifespan predisposes neurons to neurodegenerative disease. We sought to identify physiological mechanisms that delay neuron aging in Caenorhabditis elegans by asking how neuron morphological aging is arrested in the long-lived, alternate organismal state, the dauer diapause. We find that a hormone signaling pathway, the abnormal DAuer Formation (DAF) 12 nuclear hormone receptor (NHR) pathway, functions cell-intrinsically in the dauer diapause to arrest neuron morphological aging, and that same pathway can be cell-autonomously manipulated during normal organismal aging to delay neuron morphological aging. This delayed aging is mediated by suppressing constitutive endocytosis, which alters the subcellular localization of the actin regulator T cell lymphoma Invasion And Metastasis 1 (TIAM-1), thereby decreasing age-dependent neurite growth. Intriguingly, we show that suppressed endocytosis appears to be a general feature of cells in diapause, suggestive that this may be a mechanism to halt the growth and other age-related programs supported by most endosome recycling.


Assuntos
Proteínas de Caenorhabditis elegans/genética , Caenorhabditis elegans/genética , Diapausa/genética , Longevidade/genética , Neurônios/metabolismo , Receptores Citoplasmáticos e Nucleares/genética , Proteína 1 Indutora de Invasão e Metástase de Linfoma de Células T/genética , Animais , Caenorhabditis elegans/crescimento & desenvolvimento , Caenorhabditis elegans/metabolismo , Proteínas de Caenorhabditis elegans/metabolismo , Senescência Celular/genética , Endocitose/genética , Endossomos/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Genótipo , Neurônios/citologia , Receptores Citoplasmáticos e Nucleares/metabolismo , Transdução de Sinais , Proteína 1 Indutora de Invasão e Metástase de Linfoma de Células T/metabolismo
7.
Exp Appl Acarol ; 79(1): 47-68, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31388896

RESUMO

We compared the life cycles and diapause attributes among three closely related spider mites, Oligonychus castaneae on Castanea crenata, and O. gotohi and O. amiensis on Lithocarpus edulis. The lower thermal thresholds from egg to egg were 10.5, 8.5 and 8.9 °C, respectively, and the thermal constants were 177.8, 229.5 and 232.5 degree-days, respectively. The cumulative hatching rates of diapause eggs of O. castaneae and O. gotohi increased as the season progressed in and after early-to-mid January, which indicates diapause termination. In contrast, O. amiensis showed higher hatching rates in December and January, but hatchability gradually decreased in and after February because some of the eggs died from the cold. Oligonychus castaneae and O. gotohi females produced diapause eggs in response to the short photoperiod in late September to early October and in early-to-late October, respectively, which corresponded to the times predicted by the critical photoperiods (at 15 °C) of 12 h 15 min and 11 h 15 min for the respective species. Oligonychus castaneae showed at least a single population peak over the 3-year observation period, but the time of peak population varied from mid-July to mid-September. The population of O. gotohi was higher between November and May when diapause eggs were present on host plants in early winter and the first-generation females laid eggs on leaves in spring. The population of O. amiensis, which is a non-diapause species, was only high between September and December, because eggs were laid on leaves in autumn to winter and then gradually disappeared and/or died during winter. Natural enemies were observed as the number of spider mites declined, and the density suppression effect by natural enemies was confirmed in the field.


Assuntos
Diapausa , Cadeia Alimentar , Fotoperíodo , Tetranychidae/fisiologia , Animais , Fagaceae , Feminino , Larva/crescimento & desenvolvimento , Larva/fisiologia , Masculino , Ninfa/crescimento & desenvolvimento , Ninfa/fisiologia , Óvulo/crescimento & desenvolvimento , Dinâmica Populacional , Estações do Ano , Especificidade da Espécie , Tetranychidae/crescimento & desenvolvimento
8.
Biol Lett ; 15(8): 20190398, 2019 08 30.
Artigo em Inglês | MEDLINE | ID: mdl-31409242

RESUMO

Diapause is a physiological arrest of development ahead of adverse environmental conditions and is a critical phase of the life cycle of many insects. In bees, diapause has been reported in species from all seven taxonomic families. However, they exhibit a variety of diapause strategies. These different strategies are of particular interest since shifts in the phase of the insect life cycle in which diapause occurs have been hypothesized to promote the evolution of sociality. Here we provide a comprehensive evaluation of this hypothesis with phylogenetic analysis and ancestral state reconstruction (ASR) of the ecological and evolutionary factors associated with diapause phase. We find that social lifestyle, latitude and voltinism are significant predictors of the life stage in which diapause occurs. ASR revealed that the most recent common ancestor of all bees likely exhibited developmental diapause and shifts to adult, reproductive, or no diapause have occurred in the ancestors of lineages in which social behaviour has evolved. These results provide fresh insight regarding the role of diapause as a prerequisite for the evolution of sociality in bees.


Assuntos
Diapausa , Animais , Abelhas , Estágios do Ciclo de Vida , Filogenia , Reprodução , Comportamento Social
9.
Zhongguo Xue Xi Chong Bing Fang Zhi Za Zhi ; 31(2): 160-164, 2019 May 07.
Artigo em Chinês | MEDLINE | ID: mdl-31184047

RESUMO

OBJECTIVE: To compare the difference of protein expression between the post-overwintering stage and the diapauses preparation stage in Culex pipiens pallens, so as to reveal the mechanisms underlying the overwintering diapause of Cx. pipienspallens. METHODS: A quantitative proteomic analysis was performed in Cx. pipiens pallens before and after overwintering diapause by using isobaric tags for relative and absolute quantification (iTRAQ) labeling. RESULTS: A total of 244 differentially expressed proteins were identified in Cx. pipiens pallens before and after overwintering diapause, including 126 up-regulated proteins and 118 down-regulated proteins. iTRAQ-based quantitative proteomic analysis revealed that these differentially expressed proteins were linked to function and energy production and conversion, lipid metabolism, remodeling of cytoskeleton, carbohydrate metabolism, protein transport, molecular chaperones, stress tolerance and metabolic enzymes. CONCLUSIONS: This is the first study to identify the overwintering diapause-related proteins in Cx. pipiens pallens using proteomics tools, which reveals KEGG pathways and GO terms associated with the overwintering diapauses of Cx. pipiens pallens. Our findings provide additional understandings pertaining to the mechanisms underlying the overwintering diapauses of Cx. pipiens pallens.


Assuntos
Culex , Proteômica , Animais , Culex/genética , Culex/metabolismo , Diapausa/genética , Perfilação da Expressão Gênica , Regulação da Expressão Gênica , Genes de Insetos/genética
10.
Biochem J ; 476(12): 1753-1769, 2019 06 26.
Artigo em Inglês | MEDLINE | ID: mdl-31189566

RESUMO

To cope with harsh environments, the Artemia shrimp produces gastrula embryos in diapause, a state of obligate dormancy, having cellular quiescence and suppressed metabolism. The mechanism behind these cellular events remains largely unknown. Here, we study the regulation of cell quiescence using diapause embryos of Artemia We found that Artemia DEK (Ar-DEK), a nuclear factor protein, was down-regulated in the quiescent cells of diapause embryos and enriched in the activated cells of post-diapause embryos. Knockdown of Ar-DEK induced the production of diapause embryos whereas the control Artemia released free-swimming nuaplii. Our results indicate that Ar-DEK correlated with the termination of cellular quiescence via the increase in euchromatin and decrease in heterochromatin. The phenomena of quiescence have many implications beyond shrimp ecology. In cancer cells, for example, knockdown of DEK also induced a short period of cellular quiescence and increased resistance to environmental stress in MCF-7 and MKN45 cancer cell lines. Analysis of RNA sequences in Artemia and in MCF-7 revealed that the Wnt and AURKA signaling pathways were all down-regulated and the p53 signaling pathway was up-regulated upon inhibition of DEK expression. Our results provide insight into the functions of Ar-DEK in the activation of cellular quiescence during diapause formation in Artemia.


Assuntos
Artemia/embriologia , Proteínas de Artrópodes/biossíntese , Diapausa/fisiologia , Embrião não Mamífero/enzimologia , Regulação da Expressão Gênica no Desenvolvimento , Regulação Enzimológica da Expressão Gênica , Receptores da Família Eph/biossíntese , Via de Sinalização Wnt/fisiologia , Animais , Artemia/genética , Proteínas de Artrópodes/genética , Aurora Quinase A/genética , Aurora Quinase A/metabolismo , Humanos , Células MCF-7 , Receptores da Família Eph/genética
11.
PLoS Genet ; 15(6): e1008158, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31194738

RESUMO

With the approach of winter, many insects switch to an alternative protective developmental program called diapause. Drosophila melanogaster females overwinter as adults by inducing a reproductive arrest that is characterized by inhibition of ovarian development at previtellogenic stages. The insulin producing cells (IPCs) are key regulators of this process, since they produce and release insulin-like peptides that act as diapause-antagonizing hormones. Here we show that in D. melanogaster two neuropeptides, Pigment Dispersing Factor (PDF) and short Neuropeptide F (sNPF) inhibit reproductive arrest, likely through modulation of the IPCs. In particular, genetic manipulations of the PDF-expressing neurons, which include the sNPF-producing small ventral Lateral Neurons (s-LNvs), modulated the levels of reproductive dormancy, suggesting the involvement of both neuropeptides. We expressed a genetically encoded cAMP sensor in the IPCs and challenged brain explants with synthetic PDF and sNPF. Bath applications of both neuropeptides increased cAMP levels in the IPCs, even more so when they were applied together, suggesting a synergistic effect. Bath application of sNPF additionally increased Ca2+ levels in the IPCs. Our results indicate that PDF and sNPF inhibit reproductive dormancy by maintaining the IPCs in an active state.


Assuntos
Proteínas CLOCK/genética , Proteínas de Drosophila/genética , Neuropeptídeos/genética , Reprodução/genética , Animais , Animais Geneticamente Modificados/genética , Encéfalo/metabolismo , Ritmo Circadiano/genética , Diapausa/genética , Diapausa/fisiologia , Drosophila melanogaster/genética , Drosophila melanogaster/crescimento & desenvolvimento , Regulação da Expressão Gênica/genética , Insulina/genética , Neurônios/metabolismo , Transdução de Sinais/genética
12.
Reprod Biol ; 19(2): 149-157, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31147267

RESUMO

Embryonic diapause in the European roe deer includes a period of five months from August to December in which embryonic development is extremely decelerated. Following exit from diapause, the embryo rapidly elongates and subsequently implants. In diapausing carnivores and marsupials, resumption of embryonic growth is regulated by ovarian steroid hormones. In the roe deer, the role of steroid hormones is not known to date. In the present study, progesterone (P4), estradiol-17ß (E2) and total estrogens (Etot) were determined in blood plasma and endometrium of roe deer shot in the course of regular huntings between September and December. Steroid hormone concentrations were correlated to the corresponding size of the embryo derived from ex vivo uterine flushing and to the date of sampling. The mean plasma concentrations of P4 (5.4 ± 0.2 ng/ml, mean ± SE, N = 87), E2 (24.3 ± 2.6 pg/ml, N = 86) and Etot (21.7 ± 2.6 pg/ml, N = 78) remained constant over the sampling period and were not correlated to embryonic size. Likewise, endometrial concentrations of P4 (66.1 ± 6.5 ng/ml), E2 (284.0 ± 24.43 pg/ml) and, Etot (440.9 ± 24.43 pg/ml) showed no changes over time. Therefore, it was concluded that ovarian steroid hormones do not play a determining role in resumption of embryonic growth following the period of diapause in the roe deer.


Assuntos
Cervos/fisiologia , Diapausa/fisiologia , Estradiol/sangue , Prenhez , Progesterona/sangue , Animais , Endométrio , Estrogênios/sangue , Feminino , Gravidez , Prenhez/fisiologia
13.
PLoS One ; 14(6): e0218265, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31194813

RESUMO

When C. elegans hermaphrodites are deprived of food during the mid-L4 larval stage and throughout adulthood, they enter an alternative stage termed "adult reproductive diapause (ARD)" in which they halt reproduction and extend their lifespan. During ARD, germ cell proliferation stops; oogenesis is slowed; and the gonad shrinks progressively, which has been described as the "oogenic germline starvation response". Upon refeeding, the shrunken gonad is regenerated, and animals recover fertility and live out their remaining lifespan. Little is known about the effects of ARD on oocyte quality after ARD. Thus, the aim of this study was to determine how oocyte quality is affected after ARD by measuring brood size and embryonic lethality as a reflection of defective oocyte production. We found that ARD affects reproductive capacity. The oogenic germline starvation response protects oogenic germ cells by slowing oogenesis to prevent prolonged arrest in diakinesis. In contrast to a previous report, we found that germ cell apoptosis is not the cause of gonad shrinkage; instead, we propose that ovulation contributes to gonad shrinkage during the oogenic germline starvation response. We show that germ cell apoptosis increases and continues during ARD via lin-35/Rb and an unknown mechanism. Although apoptosis contributes to maintain germ cell quality during ARD, we demonstrated that apoptosis is not essential to preserve animal fertility. Finally, we show that IIS signaling inactivation partially participates in the oogenic germline starvation response.


Assuntos
Apoptose , Caenorhabditis elegans/fisiologia , Diapausa , Células Germinativas , Gônadas/fisiopatologia , Oogênese , Animais , Reprodução
14.
J Insect Physiol ; 117: 103887, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31125550

RESUMO

Dormancy is a developmental arrest in arthropods, in response to unfavorable conditions in temporally varying environments. In Aedes aegypti, the supposed inability of eggs to inhibit hatching has been used to explain the restriction of this species to tropical and subtropical regions. However, the geographic range of Ae. aegypti is constantly expanding towards temperate regions. Thus, the aim of the present study was to assess the ability of Ae. aegypti individuals from a temperate region (Buenos Aires City, Argentina) to enter photoperiod induced dormancy. To this end, we exposed both the parental generation and the eggs to short-day (SD: 10L:14D) and long-day (LD: 14L:10D) photoperiods, and studied the temporal variation in egg hatching. The experiment consisted of 28 treatment combinations of three factors: parental photoperiod (SD or LD), egg storage photoperiod (SD or LD), and age of eggs (14, 28, 42, 56, 70, 91, and 112 days). The results showed a lower hatching response with the SD parental photoperiod, and a trend to higher hatching with longer egg storage time in all photoperiod treatment combinations. The egg storage photoperiod showed no effect on egg hatching. In both parental photoperiod treatments, egg replicates of most ages from different females showed a large variability, with some replicates with lowest hatching response and others with highest hatching response. Our results show the ability of Ae. aegypti to inhibit egg hatching in response to a short-day photoperiod, which could allow the further expansion of this species to regions with colder winters.


Assuntos
Aclimatação , Aedes/fisiologia , Aedes/embriologia , Animais , Diapausa , Feminino , Óvulo/fisiologia , Fotoperíodo
15.
Med Vet Entomol ; 33(3): 360-366, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-30883848

RESUMO

Determination of the ratios of natural stable isotopes (13 C/12 C and 15 N/14 N) in unfed Ixodes ricinus nymphs and adults, which, in their previous stage, fed on captive wild rodents (Apodemus sylvaticus and Myodes glareolus), wild birds (Parus major and Cyanistes caeruleus) or domestic ruminants (Ovis aries and Bos taurus), demonstrated that it is possible to identify each host category with confidence. First, the tick-blood spacing, which is the difference between values obtained from ticks and the blood of hosts that they had fed on in the previous stage, was consistent (152 spacings investigated from 15 host individuals in total). Second, potential confounding factors (tick age and sex) did not affect the discriminatory power of the isotope patterns, nor did different rearing conditions (room temperature vs. 4 °C) or the duration of development (maximum of 430 days). The findings that the tick-blood isotope spacings, across a diverse range of hosts, were similar and predictable, and that confounders had little or no effect on this, strongly support the usage of the isotope approach. Because each of the host categories has a different role in the population dynamics of I. ricinus and in tick-borne pathogen ecology, the method described here has great potential for the clarification of tick and tick-borne pathogen ecology in the field.


Assuntos
Aves/parasitologia , Isótopos de Carbono/análise , Interações Hospedeiro-Parasita , Ixodes/fisiologia , Mamíferos/parasitologia , Isótopos de Nitrogênio/análise , Animais , Diapausa , Feminino , Ixodes/crescimento & desenvolvimento , Larva/crescimento & desenvolvimento , Larva/fisiologia , Masculino , Ninfa/crescimento & desenvolvimento , Ninfa/fisiologia , Especificidade da Espécie , Temperatura Ambiente
16.
Parasit Vectors ; 12(1): 147, 2019 Mar 27.
Artigo em Inglês | MEDLINE | ID: mdl-30917854

RESUMO

BACKGROUND: West Nile virus (WNV) is a mosquito-borne virus that is mainly transmitted among birds by Culex pipiens mosquitoes. The species Cx. pipiens consists of two biotypes named pipiens and molestus, which together can form hybrids. One of the major distinctions between the biotypes is their overwintering behaviour. Adults of biotype pipiens diapause during winter, whereas biotype molestus remains actively blood-feeding. Diapausing may affect survival and vector competence of biotype pipiens. The aims of this study were therefore to identify the biotype composition of diapausing Cx. pipiens mosquitoes, to quantify survival throughout the autumn and winter months, and to determine effects of overwintering on vector competence of emerging Cx. pipiens mosquitoes for WNV. METHODS: Diapausing mosquitoes were collected at two typical overwintering locations in the Netherlands. A selection of Cx. pipiens mosquitoes was identified to biotype using real-time PCR. Survival of diapausing Cx. pipiens mosquitoes during autumn and winter was monitored by placing cages with either field-collected or laboratory-reared females in houses and sheds. Vector competence of field-collected (diapausing) and laboratory-reared (non-diapausing) Cx. pipiens mosquitoes was determined to gain insight in the effect of overwintering on WNV transmission. RESULTS: The majority (92%) of diapausing Cx. pipiens females were identified as biotype pipiens. More than 70% of diapausing Cx. pipiens mosquitoes was able to survive for more than four months in sheds, whereas diapausing in houses resulted in 100% mortality in that same period. In contrast, non-diapausing Cx. pipiens biotype pipiens mosquitoes reared in the laboratory died within a week in both houses and sheds. Vector competence of Cx. pipiens mosquitoes that had diapaused during the autumn and winter months was comparable to non-diapausing laboratory-reared mosquitoes. CONCLUSIONS: This study confirms that the majority of Cx. pipiens mosquitoes in their typical overwintering site belongs to the pipiens biotype. It shows that more than two-third of diapausing Cx. pipiens mosquitoes is able to survive winter under sheltered winter conditions. Finally, vector competence for WNV of mosquitoes that emerge from overwintering sites is not affected by their relatively old age.


Assuntos
Culex/classificação , Culex/fisiologia , Mosquitos Vetores/classificação , Mosquitos Vetores/fisiologia , Estações do Ano , Animais , Culex/virologia , Diapausa , Ecossistema , Feminino , Mosquitos Vetores/virologia , Países Baixos , Reação em Cadeia da Polimerase em Tempo Real , Especificidade da Espécie , Febre do Nilo Ocidental/transmissão , Vírus do Nilo Ocidental/fisiologia
17.
Poult Sci ; 98(7): 2977-2988, 2019 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-30915476

RESUMO

Blue-breasted quail has been recognized as a potential model animal. The aim of this study is to investigate the low-temperature-induced embryonic diapause in blue-breasted quail. To this end, the early embryonic staging in blue-breasted quail was briefly described and various incubation temperatures were tested. While the embryonic diapause in early blue-breasted quail embryos can be induced when the eggs were stored at 21°C, a lower temperature such as 16°C yielded a significantly better hatchability (P = 0.0231). Additionally, prolonged storage duration from 3, 7 to 14 d significantly reduced the hatchability (P < 0.0001). Visual examination on the unhatched eggs revealed that reduced hatchability in prolonged storage was significantly correlated with embryonic mortality during the first half of incubation period (R2 = 0.9999, P = 0.0055). High-throughput RNA sequencing with de novo assembly showed that a gene network cluster consisted of ND4, ND5, ND6, and COX3, which are components of mitochondrial respiratory complexes, was down-regulated in the cold-stored embryos, while a stress-responsive gene network cluster consisted of JUN, ATF3, and DUSP1 was up-regulated. Accordingly, cell death in the blastoderm was significantly increased as the storage duration prolonged from 3 to 10 d. Taken together, our study provided basic information on the temperature-induced embryonic diapause in blue-breasted quail. Furthermore, transcriptomic analysis sheds light for the molecular basis on how blastoderm cells respond to the prolonged cold-stress and stay diapause.


Assuntos
Temperatura Baixa , Coturnix/embriologia , Diapausa/fisiologia , Desenvolvimento Embrionário/fisiologia , Animais , Coturnix/genética , Coturnix/metabolismo , Diapausa/genética , Embrião não Mamífero/embriologia , Óvulo/fisiologia , Análise de Sequência de RNA , Estresse Fisiológico/genética , Estresse Fisiológico/fisiologia
18.
J Insect Physiol ; 114: 92-99, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30802445

RESUMO

The regulation of active and dormant stages of arthropods is critical for surviving unfavourable seasonal conditions, and for many species depends on the diapause intensity (DI). There is substantial information on diapause strategies of arthropods under winter conditions; however, most cases of summer diapause are poorly understood despite its importance in most geographic regions of the world. Here we show how complex interactions with the environment drive DI involving multiple summer diapause forms of the mite Halotydeus destructor. This invasive pest in Australia is only active in cooler months but enters diapause at the egg stage which can survive hot and dry summer conditions. Recent research points to two forms of diapause egg, a typical form with a thick chorion and a cryptic form without this chorion which is morphologically similar to non-diapause eggs. Compared with typical diapause eggs which are produced in late spring, cryptic diapause eggs could be produced together with non-diapause eggs earlier in the season with relatively cooler temperatures and shorter daylength, reflecting an advanced bet-hedging strategy. Fitness trade-offs in this strategy are investigated in this study as variability of DI of the typical and cryptic diapause forms under different environmental factors for incubating diapause eggs (temperature) and rearing parental mites (different daylength, temperature and soil moisture). With the exception of daylength, all factors impacted hatchability of diapause eggs. Higher mortality of cryptic diapause eggs indicated relatively shallower DI than typical diapause eggs, likely reflecting a fitness penalty of this bet-hedging strategy under some conditions. Hatchability of cryptic diapause eggs revealed thermal and moisture stresses have opposite and complementary effects between parental and filial generations. Although DI of filial eggs decreased in hot and dry summer conditions, parental mites reared in hotter and drier conditions increased the DI of offspring. A bet-hedging strategy involving cryptic diapause might be replaced by typical diapause under consistently stressful conditions because of higher survival, regardless of additional production costs that might be required. These findings highlight a complex set of plastic responses to summer conditions in H. destructor that undoubtedly contribute to the success of this invasive pest under a range of environments.


Assuntos
Diapausa , Ácaros/fisiologia , Animais , Meio Ambiente , Feminino , Masculino , Óvulo/fisiologia
19.
Cell Stress Chaperones ; 24(2): 385-392, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30701477

RESUMO

The crustacean, Artemia franciscana, displays a complex life history in which embryos either arrest development and undertake diapause as cysts or they develop into swimming nauplii. Diapause entry is preceded during embryogenesis by the synthesis of specific molecular chaperones, namely the small heat shock proteins p26, ArHsp21, and ArHsp22, and the ferritin homolog, artemin. Maximal synthesis of diapause-specific molecular chaperones is dependent on the transcription factor, heat shock factor 1 (Hsf1), found in similar amounts in cysts and nauplii newly released from females. This investigation was performed to determine why, if cysts and nauplii contain comparable amounts of Hsf1, only cyst-destined embryos synthesize diapause-specific molecular chaperones. Quantification by qPCR and immunoprobing of Western blots, respectively, demonstrated that hsf1 mRNA and Hsf1 peaked by day 2 post-fertilization in embryos that were developing into cysts and then declined. hsf1 mRNA and Hsf1 were present in nauplii-destined embryos on day 2 post-fertilization, but in much smaller amounts than in cyst-destined embryos, and they increased in quantity until release of nauplii from females. Immunofluorescent staining revealed that the amount of Hsf1 in nuclei was greatest on day 4 post-fertilization in cyst-destined embryos but could not be detected in nuclei of nauplius-destined embryos at this time. The differences in quantity and location of Hsf1 explain why embryos fated to become cysts and eventually enter diapause synthesize p26, ArHsp21, ArHsp22, and artemin, whereas nauplius-destined embryos do not produce these molecular chaperones.


Assuntos
Artemia/embriologia , Proteínas de Artrópodes/metabolismo , Diapausa , Embrião não Mamífero/metabolismo , Fatores de Transcrição de Choque Térmico/metabolismo , Animais , Artemia/metabolismo , Proteínas de Artrópodes/genética , Feminino , Regulação da Expressão Gênica no Desenvolvimento , Fatores de Transcrição de Choque Térmico/genética , Proteínas de Choque Térmico/genética , Proteínas de Choque Térmico/metabolismo , Oocistos/crescimento & desenvolvimento , Oocistos/metabolismo
20.
J Biol Chem ; 294(16): 6598-6611, 2019 04 19.
Artigo em Inglês | MEDLINE | ID: mdl-30765604

RESUMO

Cellular quiescence, a reversible state in which growth, proliferation, and other cellular activities are arrested, is important for self-renewal, differentiation, development, regeneration, and stress resistance. However, the physiological mechanisms underlying cellular quiescence remain largely unknown. In the present study, we used embryos of the crustacean Artemia in the diapause stage, in which these embryos remain quiescent for prolonged periods, as a model to explore the relationship between cell-membrane potential (V mem) and quiescence. We found that V mem is hyperpolarized and that the intracellular chloride concentration is high in diapause embryos, whereas V mem is depolarized and intracellular chloride concentration is reduced in postdiapause embryos and during further embryonic development. We identified and characterized the chloride ion channel protein cystic fibrosis transmembrane conductance regulator (CFTR) of Artemia (Ar-CFTR) and found that its expression is silenced in quiescent cells of Artemia diapause embryos but remains constant in all other embryonic stages. Ar-CFTR knockdown and GlyH-101-mediated chemical inhibition of Ar-CFTR produced diapause embryos having a high V mem and intracellular chloride concentration, whereas control Artemia embryos released free-swimming nauplius larvae. Transcriptome analysis of embryos at different developmental stages revealed that proliferation, differentiation, and metabolism are suppressed in diapause embryos and restored in postdiapause embryos. Combined with RNA sequencing (RNA-Seq) of GlyH-101-treated MCF-7 breast cancer cells, these analyses revealed that CFTR inhibition down-regulates the Wnt and Aurora Kinase A (AURKA) signaling pathways and up-regulates the p53 signaling pathway. Our findings provide insight into CFTR-mediated regulation of cellular quiescence and V mem in the Artemia model.


Assuntos
Artemia/embriologia , Membrana Celular/metabolismo , Regulador de Condutância Transmembrana em Fibrose Cística/metabolismo , Diapausa/fisiologia , Embrião não Mamífero/embriologia , Animais , Artemia/genética , Proteínas de Artrópodes/genética , Regulador de Condutância Transmembrana em Fibrose Cística/genética , Humanos , Células MCF-7
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