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Pavel Jedlička, Ulrich R Ernst, Alena Votavová, Robert Hanus, Irena Valterová
Understanding the social evolution leading to insect eusociality requires, among other, a detailed insight into endocrine regulatory mechanisms that have been co-opted from solitary ancestors to play new roles in the complex life histories of eusocial species. Bumblebees represent well-suited models of a relatively primitive social organization standing on the mid-way to highly advanced eusociality and their queens undergo both, a solitary and a social phase, separated by winter diapause. In the present paper, we characterize the gene expression levels of major endocrine regulatory pathways across tissues, sexes, and life-stages of the buff-tailed bumblebee, Bombus terrestris, with special emphasis on critical stages of the queen's transition from solitary to social life...
2016: Frontiers in Physiology
Olga I Kubrak, Lucie Kučerová, Ulrich Theopold, Sören Nylin, Dick R Nässel
Insects are known to respond to seasonal and adverse environmental changes by entering dormancy, also known as diapause. In some insect species, including Drosophila melanogaster, dormancy occurs in the adult organism and postpones reproduction. This adult dormancy has been studied in female flies where it is characterized by arrested development of ovaries, altered nutrient stores, lowered metabolism, increased stress and immune resistance and drastically extended lifespan. Male dormancy, however, has not been investigated in D...
2016: Frontiers in Physiology
Mykola Mylenko, Sebastian Boland, Sider Penkov, Julio L Sampaio, Benoit Lombardot, Daniela Vorkel, Jean-Marc Verbavatz, Teymuras V Kurzchalia
The free-living soil nematode Caenorhabditis elegans adapts its development to the availability of food. When food is scarce and population density is high, worms enter a developmentally arrested non-feeding diapause stage specialized for long-term survival called the dauer larva. When food becomes available, they exit from the dauer stage, resume growth and reproduction. It has been postulated that compound(s) present in food, referred to as the "food signal", promote exit from the dauer stage. In this study, we have identified NAD+ as a component of bacterial extract that promotes dauer exit...
2016: PloS One
Adam Glazaczow, David Orwin, Michał Bogdziewicz
We analyzed the impact of increased water temperature on the late-season phenology of the mayfly (Baetis liebenauae). The River Gwda, unlike two other examined rivers (controls), has reservoirs along its length and thus, higher water temperature. Elevated water temperature prolonged summer diapause of the mayfly and shifted its life cycle to the later autumn: the last generation of mayflies started development later in the Gwda than in the control rivers. This translated into terrestrial stages (subimagos) of the insect being more abundant at the water surface in the late autumn in the Gwda river than in the control rivers...
December 1, 2016: Scientific Reports
Sean F Ryan, Patti Valella, Gabrielle Thivierge, Matthew L Aardema, J Mark Scriber
A key adaptation in insects for dealing with variable environmental conditions is the ability to diapause. The tiger swallowtail butterflies, Papilio glaucus and P. canadensis are ideal species to explore the genetic causes and population genetic consequences of diapause because divergence in this trait is believed to be a salient factor in maintaining a hybrid zone between these species. Yet little is known about the factors that influence diapause induction in this system. Here we explored how spatial (latitudinal), environmental (temperature) and genetic (hybridization) factors affect diapause induction in this system...
November 29, 2016: Insect Science
Ryo Kitta, Marina Kuwamoto, Yumi Yamahama, Keisuke Mase, Hiroshi Sawada
To elucidate the mechanism for embryonic diapause or the breakdown of diapause in Bombyx mori, we biochemically analyzed nitric oxide synthase (NOS) during the embryogenesis of B. mori. The gene expression and enzyme activity of B. mori NOS (BmNOS) were examined in diapause, non-diapause, and HCl-treated diapause eggs. In the case of HCl-treated diapause eggs, the gene expression and enzyme activity of BmNOS were induced by HCl treatment. However, in the case of diapause and non-diapause eggs during embryogenesis, changes in the BmNOS activity and gene expressions did not coincide except 48-60 h after oviposition in diapause eggs...
November 29, 2016: Development, Growth & Differentiation
Yuta Shimizu, Ayumu Mukai, Shin G Goto
Insects enter diapause to synchronise their life cycle with biotic and abiotic environmental conditions favourable for their development, reproduction, and survival. One of the most noticeable characteristics of diapause is the blockage of ontogeny. Although this blockage should occur with the cessation of cellular proliferation, i.e. cell cycle arrest, it was confirmed only in a few insect species and information on the molecular pathways involved in cell cycle arrest is limited. In the present study, we investigated developmental and cell cycle arrest in diapause larvae of the jewel wasp Nasonia vitripennis...
November 25, 2016: Journal of Insect Physiology
Aydan Bulut-Karslioglu, Steffen Biechele, Hu Jin, Trisha A Macrae, Miroslav Hejna, Marina Gertsenstein, Jun S Song, Miguel Ramalho-Santos
Cultured pluripotent stem cells are a cornerstone of regenerative medicine owing to their ability to give rise to all cell types of the body. Although pluripotent stem cells can be propagated indefinitely in vitro, pluripotency is paradoxically a transient state in vivo, lasting 2-3 days around the time of blastocyst implantation. The exception to this rule is embryonic diapause, a reversible state of suspended development triggered by unfavourable conditions. Diapause is a physiological reproductive strategy widely employed across the animal kingdom, including in mammals, but its regulation remains poorly understood...
December 1, 2016: Nature
G C P Diyes, R S Rajakaruna
Otobius megnini infests mainly domesticated and wild animals and occasionally humans. It has been identified as an agent of human and horse otoacariasis in Sri Lanka. The number of nymphal stages in the life cycle of O. megnini varies from one to three in different geographic regions. The present study determined the life cycle of O. megnini infesting the racehorses in Nuwara Eliya. A tick colony was initiated from fully engorged nymphs collected from horses and maintained at 10°C, 22°C and 28°C. Immature stages were reared on New Zealand rabbits...
November 18, 2016: Acta Tropica
Kévin Tougeron, Cécile Le Lann, Jacques Brodeur, Joan van Baaren
Temperature is both a selective pressure and a modulator of the diapause expression in insects from temperate regions. Thus, with climate warming, an alteration of the response to seasonal changes is expected, either through genetic adaptations to novel climatic conditions or phenotypic plasticity. Since the 1980s in western France, the winter guild of aphid parasitoids (Hymenoptera: Braconidae) in cereal fields has been made up of two species: Aphidius rhopalosiphi and Aphidius matricariae. The recent activity of two other species, Aphidius avenae and Aphidius ervi, during the winter months suggests that a modification of aphid parasitoid overwintering strategies has taken place within the guild...
November 21, 2016: Oecologia
Koustubh M Vaze, Charlotte Helfrich-Förster
Insects inhabiting the temperate zones measure seasonal changes in day or night length to enter the overwintering diapause. Diapause induction occurs after the duration of the night exceeds a critical night length (CNL). Our understanding of the time measurement mechanisms is continuously evolving subsequent to Bünning's proposal that circadian systems play the clock role in photoperiodic time measurement (Bünning, 1936). Initially, the photoperiodic clocks were considered to be either based on circadian oscillators or on simple hour-glasses, depending on 'positive' or 'negative' responses in Nanda-Hamner and Bünsow experiments (Nanda & Hammer, 1958; Bünsow, 1960)...
December 2016: Physiological Entomology
A E Romo-Curiel, O Sosa-Nishizaki, J C Pérez-Jiménez, M C Rodríguez-Medrano
Samples of the shovelnose guitarfish Pseudobatos productus were collected on board a vessel and at landings of artisanal commercial fisheries in the Gulf of California from May 2004 to June 2007. Samples of 650 females, 2047 embryos and 484 uterine eggs were examined. The reproductive cycle is annual, ovulation and parturition occur in July, the uterine eggs are in diapause for 9 months (July-March) before an accelerated growth of embryos of 3 months. Histological analyses of the uterine wall of pregnant females suggested that no secretions were used for embryo nourishment...
November 10, 2016: Journal of Fish Biology
James Chang, Jugeshwar Singh, Sungshil Kim, William C Hockaday, Cheolho Sim, Sung Joon Kim
Culex pipiens is the mosquito that vectors West Nile Virus and other human-pathogenic flavivruses in North America. In response to shortened day length and lower temperatures, female Cx. pipiense prepares for the diapause by actively feeding on carbohydrates to increase the biosynthesis of glycogen and lipid to store energy for overwintering. The effect of feeding different carbohydrates on glycogen and lipid biosynthesis in diapausing mosquitoes was investigated in vivo using 13C solid-state NMR. Diapause-destined adult females and nondiapausing counterparts after adult eclosion were fed with three different carbohydrate sources for 7 days: 1) 10% sucrose, 2) 10% D-[(13)C6]glucose, and 3) 1% D-[(13)C6]glucose co-provisioned with 10% sucrose...
November 17, 2016: Scientific Reports
M K Dhillon, F Hasan, A K Tanwar, A S Bhadauriya
Determination of critical threshold for induction and termination of diapause (hibernation) are important for better understanding the bio-ecology and population dynamics of Chilo partellus (Swinhoe) under varying climatic conditions. We studied initiation and termination of hibernation under five temperature and photoperiod regimes viz., 27°C + 12L:12D, 22°C + 11.5L:12.5D, 18°C + 11L:13D, 14°C + 10.5L:13.5D and 10°C + 10L:14D under fixed and ramping treatments, and the observations were recorded on various phenological and developmental characteristics at weekly intervals...
November 10, 2016: Bulletin of Entomological Research
Y Tan, X-R Zhou, B-P Pang
Quantitative real-time PCR (qRT-PCR) has been used extensively to analyze gene expression and decipher gene function. To obtain the optimal and stable normalization factors for qRT-PCR, selection and validation of reference genes should be conducted in diverse conditions. In insects, more and more studies confirmed the necessity and importance of reference gene selection. In this study, eight traditionally used reference genes in Galeruca daurica (Joannis) were assessed, using qRT-PCR, for suitability as normalization genes under different experimental conditions using four statistical programs: geNorm, Normfinder, BestKeeper and the comparative ΔC t method...
November 7, 2016: Bulletin of Entomological Research
Mark F Baumgartner, Ann M Tarrant
Diapause is a type of dormancy that requires preparation, typically precedes the onset of unfavorable conditions, and necessitates a period of arrest before development can proceed. Two ecologically important groups of copepods have incorporated diapausing stages into their life histories. In freshwater, estuarine, and coastal environments, species within the Centropagoidea superfamily can produce resting eggs containing embryos that may be quiescent, diapausing, or in some intermediate state. Resting eggs sink into the sediments, remain viable over months to years, and form a reservoir from which the planktonic population is reestablished...
October 28, 2016: Annual Review of Marine Science
Marcelo B Labruna, Monize Gerardi, Felipe S Krawczak, Jonas Moraes-Filho
Recent studies have shown that the taxon Rhipicephalus sanguineus sensu lato (s.l.) is represented in Latin America by two distinct species, designated as 'tropical species' (distributed from Mexico to Brazil) and 'temperate species' (restricted to the southern cone of South America). Since both tropical and temperate species of R. sanguineus s.l. are parasites primarily of domestic dogs, the reasons for their distinct geographical distribution in South America could be related to particular requirements of abiotic conditions for off-host development...
January 2017: Ticks and Tick-borne Diseases
Yue-Kun Wu, Chao Zou, Dao-Meng Fu, Wan-Na Zhang, Hai-Jun Xiao
Heat shock proteins (Hsps) have been linked to stresses and winter diapause in insects, but whether they are components of summer diapause is still unknown. In this study, cDNAs of Hsp90 from Pieris melete, Pieris rapae and Pieris canidia named PmHsp90, PrHsp90 and PcHsp90, respectivele, were cloned and sequenced. The deduced amino acid sequence consisted of 718 amino acid residues with a putative molecular mass of 82.6, 82.6, 82.7 kDa respectively. The amino acid sequences contained all of the five conserved signature motifs in the Hsp90 family and a bHLH protein folding activity region...
October 28, 2016: Insect Science
Xiaofeng Zheng, Pengyi Yang, Brad Lackford, Brian D Bennett, Li Wang, Hui Li, Yu Wang, Yiliang Miao, Julie F Foley, David C Fargo, Ying Jin, Carmen J Williams, Raja Jothi, Guang Hu
Poly(A) tail length and mRNA deadenylation play important roles in gene regulation. However, how they regulate embryonic development and pluripotent cell fate is not fully understood. Here we present evidence that CNOT3-dependent mRNA deadenylation governs the pluripotent state. We show that CNOT3, a component of the Ccr4-Not deadenylase complex, is required for mouse epiblast maintenance. It is highly expressed in blastocysts and its deletion leads to peri-implantation lethality. The epiblast cells in Cnot3 deletion embryos are quickly lost during diapause and fail to outgrow in culture...
November 8, 2016: Stem Cell Reports
Vittoria Roncalli, Jefferson T Turner, David Kulis, Donald M Anderson, Petra H Lenz
Inshore and offshore waters of the Gulf of Maine (USA) have spring/summer harmful algal blooms (HABs) of the toxic dinoflagellate Alexandrium fundyense, which is responsible for paralytic shellfish poisoning (PSP) in humans. The calanoid copepod Calanus finmarchicus co-occurs with A. fundyense during the seasonal blooms. At that time, C. finmarchicus population abundances are high, dominated by immature copepods preparing for diapause, and by actively-reproducing adults. High survival has been reported for copepods exposed to toxic A...
January 2016: Harmful Algae
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