EYES ABSENT and TIMELESS integrate photoperiodic and temperature cues to regulate seasonal physiology inDrosophila

Organisms possess photoperiodic timing mechanisms to detect variations in day length and temperature as the seasons progress. The nature of the molecular mechanisms interpreting and signaling these environmental changes to elicit downstream neuroendocrine and physiological responses are just starting to emerge. Here, we demonstrate that, inDrosophila melanogaster, EYES ABSENT (EYA) acts as a seasonal sensor by interpreting photoperiodic and temperature changes to trigger appropriate physiological responses. We observed that tissue-specific genetic manipulation ofeyaexpression is sufficient to disrupt the ability of flies to sense seasonal cues, thereby altering the extent of female reproductive dormancy. Specifically, we observed that EYA proteins, which peak at night in short photoperiod and accumulate at higher levels in the cold, promote reproductive dormancy in femaleD. melanogaster. Furthermore, we provide evidence indicating that the role of EYA in photoperiodism and temperature sensing is aided by the stabilizing action of the light-sensitive circadian clock protein TIMELESS (TIM). We postulate that increased stability and level of TIM at night under short photoperiod together with the production of cold-induced and light-insensitive TIM isoforms facilitate EYA accumulation in winter conditions. This is supported by our observations thattimnull mutants exhibit reduced incidence of reproductive dormancy in simulated winter conditions, while flies overexpressingtimshow an increased incidence of reproductive dormancy even in long photoperiod.

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EYES ABSENT and TIMELESS integrate photoperiodic and temperature cues to regulate seasonal physiology in Drosophila

10.1101/2020.03.05.979682 ◽

2020 ◽

Cited By ~ 1

Author(s):

Antoine Abrieux ◽

Yongbo Xue ◽

Yao Cai ◽

Kyle M. Lewald ◽

Hoang Nhu Nguyen ◽

...

Keyword(s):

Circadian Clock ◽

Molecular Mechanisms ◽

Environmental Changes ◽

Physiological Responses ◽

Day Length ◽

Short Photoperiod ◽

Eyes Absent ◽

Winter Conditions ◽

Clock Protein

AbstractOrganisms possess photoperiodic timing mechanisms to anticipate variations in day length and temperature as the seasons progress. The nature of the molecular mechanisms interpreting and signaling these environmental changes to elicit downstream neuroendocrine and physiological responses are just starting to emerge. Here, we demonstrate that in Drosophila melanogaster, EYES ABSENT (EYA) acts as a seasonal sensor by interpreting photoperiodic and temperature changes to trigger appropriate physiological responses. We observed that tissue-specific genetic manipulation of eya expression is sufficient to disrupt the ability of flies to sense seasonal cues, thereby altering the extent of female reproductive dormancy. Specifically we observed that EYA proteins, which peak at night in short photoperiod and accumulate at higher levels in the cold, promote reproductive dormancy in female D. melanogaster. Furthermore, we provide evidence indicating that the role of EYA in photoperiodism and temperature sensing is aided by the stabilizing action of the light-sensitive circadian clock protein TIMELESS (TIM). We postulate that increased stability and level of TIM at night under short photoperiod together with the production of cold-induced and light-insensitive TIM isoforms facilitate EYA accumulation in winter conditions. This is supported by our observations that tim null mutants exhibit reduced incidence of reproductive dormancy in simulated winter conditions, while flies overexpressing tim show an increased incidence of reproductive dormancy even in long photoperiod.Significance StatementExtracting information on calendar time from seasonal changes in photoperiod and temperature is critical for organisms to maintain circannual cycles in physiology and behavior. Here we found that in flies, EYES ABSENT (EYA) protein act as a seasonal sensor by adjusting its abundance and circadian phase in response to changes in photoperiod and temperature. We show that the manipulation of EYA levels is sufficient to impair the ability of female Drosophila to regulate seasonal variation in reproductive dormancy. Finally, our results suggest an important role of the circadian clock protein TIMELESS (TIM) in modulating EYA level through its ability to measure night length, linking the circadian clock to seasonal timing.

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Evolution of time-keeping mechanisms: early emergence and adaptation to photoperiod

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2010.0409 ◽

2011 ◽

Vol 366 (1574) ◽

pp. 2141-2154 ◽

Cited By ~ 102

Author(s):

R. A. Hut ◽

D. G. M. Beersma

Keyword(s):

Molecular Mechanisms ◽

Selective Advantage ◽

Life Forms ◽

Climatic Conditions ◽

Circadian System ◽

Day Length ◽

Physiological Adaptation ◽

Length Variation ◽

Circadian Timing ◽

Timing Mechanisms

Virtually all species have developed cellular oscillations and mechanisms that synchronize these cellular oscillations to environmental cycles. Such environmental cycles in biotic (e.g. food availability and predation risk) or abiotic (e.g. temperature and light) factors may occur on a daily, annual or tidal time scale. Internal timing mechanisms may facilitate behavioural or physiological adaptation to such changes in environmental conditions. These timing mechanisms commonly involve an internal molecular oscillator (a ‘clock’) that is synchronized (‘entrained’) to the environmental cycle by receptor mechanisms responding to relevant environmental signals (‘ Zeitgeber ’, i.e. German for time-giver). To understand the evolution of such timing mechanisms, we have to understand the mechanisms leading to selective advantage. Although major advances have been made in our understanding of the physiological and molecular mechanisms driving internal cycles ( proximate questions), studies identifying mechanisms of natural selection on clock systems ( ultimate questions) are rather limited. Here, we discuss the selective advantage of a circadian system and how its adaptation to day length variation may have a functional role in optimizing seasonal timing. We discuss various cases where selective advantages of circadian timing mechanisms have been shown and cases where temporarily loss of circadian timing may cause selective advantage. We suggest an explanation for why a circadian timing system has emerged in primitive life forms like cyanobacteria and we evaluate a possible molecular mechanism that enabled these bacteria to adapt to seasonal variation in day length. We further discuss how the role of the circadian system in photoperiodic time measurement may explain differential selection pressures on circadian period when species are exposed to changing climatic conditions (e.g. global warming) or when they expand their geographical range to different latitudes or altitudes.

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Osmotic adjustment and plant adaptation to environmental changes related to drought and salinity

Environmental Reviews ◽

10.1139/a10-014 ◽

2010 ◽

Vol 18 (NA) ◽

pp. 309-319 ◽

Cited By ~ 144

Author(s):

Hui Chen ◽

Jian-Guo Jiang

Keyword(s):

Osmotic Adjustment ◽

Molecular Mechanisms ◽

Environmental Changes ◽

Genetic Manipulation ◽

Compatible Solutes ◽

Inorganic Ions ◽

Research Field ◽

Transport Processes ◽

Organic Solutes ◽

Extracellular Ions

The salinization and water deficit of soil are widespread environmental problems in limiting plant survival, growth, and productivity. However, some plants could adopt some strategies to resist salinity and drought stresses. Among these strategies, the mechanism of osmotic adjustment could help plants and algae to avoid ion toxicity and maintain water uptake in both stresses by accumulating large quantities of osmolytes. Two types of osmolytes, organic solutes and inorganic ions, play a key role in osmotic adjustment. Different osmolytes and their osmotic adjustment actions are different according to their distribution in different plants. Organic solutes, known as compatible solutes, include amino acids, glycerol, sugars, and other low molecular weight metabolites, serve a function in cells to lower or balance the osmotic potential of intracellular and extracellular ions in resistance to osmotic stresses. Inorganic ions for osmotic adjustment are mainly Na+, K+, Ca2+, and Cl–. Inorganic ions make great contribution in osmotic adjustment by ion transport processes with related ion antiporters and ion channels. The aim of this review is to integrate recent data on the mechanisms of osmotic adjustment by osmolytes in plants and algae, and to illustrate the variety of related molecular mechanisms, to introduce new concepts and techniques into this research field. Genetic manipulation including the application of transgenic techniques in plants provides promising strategies to elevate the tolerance capability of plants under osmotic stress conditions.

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Modernized Tools for Streamlined Genetic Manipulation and Comparative Study of Wild and Diverse Proteobacterial Lineages

mBio ◽

10.1128/mbio.01877-18 ◽

2018 ◽

Vol 9 (5) ◽

Cited By ~ 24

Author(s):

Travis J. Wiles ◽

Elena S. Wall ◽

Brandon H. Schlomann ◽

Edouard A. Hay ◽

Raghuveer Parthasarathy ◽

...

Keyword(s):

Comparative Study ◽

Molecular Mechanisms ◽

Genetic Manipulation ◽

Functional Characterization ◽

Symbiotic Bacteria ◽

Bacterial Isolates ◽

Major Barrier ◽

Allelic Exchange ◽

Genetic Techniques

ABSTRACTCorrelating the presence of bacteria and the genes they carry with aspects of plant and animal biology is rapidly outpacing the functional characterization of naturally occurring symbioses. A major barrier to mechanistic studies is the lack of tools for the efficient genetic manipulation of wild and diverse bacterial isolates. To address the need for improved molecular tools, we used a collection of proteobacterial isolates native to the zebrafish intestinal microbiota as a testbed to construct a series of modernized vectors that expedite genetic knock-in and knockout procedures across lineages. The innovations that we introduce enhance the flexibility of conventional genetic techniques, making it easier to manipulate many different bacterial isolates with a single set of tools. We developed alternative strategies for domestication-free conjugation, designed plasmids with customizable features, and streamlined allelic exchange using visual markers of homologous recombination. We demonstrate the potential of these tools through a comparative study of bacterial behavior within the zebrafish intestine. Live imaging of fluorescently tagged isolates revealed a spectrum of distinct population structures that differ in their biogeography and dominant growth mode (i.e., planktonic versus aggregated). Most striking, we observed divergent genotype-phenotype relationships: several isolates that are predicted by genomic analysis andin vitroassays to be capable of flagellar motility do not display this trait within living hosts. Together, the tools generated in this work provide a new resource for the functional characterization of wild and diverse bacterial lineages that will help speed the research pipeline from sequencing-based correlations to mechanistic underpinnings.IMPORTANCEA great challenge in microbiota research is the immense diversity of symbiotic bacteria with the capacity to impact the lives of plants and animals. Moving beyond correlative DNA sequencing-based studies to define the cellular and molecular mechanisms by which symbiotic bacteria influence the biology of their hosts is stalling because genetic manipulation of new and uncharacterized bacterial isolates remains slow and difficult with current genetic tools. Moreover, developing tools de novo is an arduous and time-consuming task and thus represents a significant barrier to progress. To address this problem, we developed a suite of engineering vectors that streamline conventional genetic techniques by improving postconjugation counterselection, modularity, and allelic exchange. Our modernized tools and step-by-step protocols will empower researchers to investigate the inner workings of both established and newly emerging models of bacterial symbiosis.

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Transcriptome changes reveal the genetic mechanisms of the reproductive plasticity of workers in lower termites

BMC Genomics ◽

10.1186/s12864-019-6037-y ◽

2019 ◽

Vol 20 (1) ◽

Author(s):

Chenxu Ye ◽

Humaira Rasheed ◽

Yuehua Ran ◽

Xiaojuan Yang ◽

Lianxi Xing ◽

...

Keyword(s):

Gene Expression ◽

Signal Transduction ◽

Molecular Mechanisms ◽

Environmental Changes ◽

Mapk Pathway ◽

Specific Expression ◽

Expression Of Genes ◽

Genetic Mechanisms ◽

Ecological Success ◽

Reproductive Plasticity

Abstract Background The reproductive plasticity of termite workers provides colonies with tremendous flexibility to respond to environmental changes, which is the basis for evolutionary and ecological success. Although it is known that all colony members share the same genetic background and that differences in castes are caused by differences in gene expression, the pattern of the specific expression of genes involved in the differentiation of workers into reproductives remains unclear. In this study, the isolated workers of Reticulitermes labralis developed into reproductives, and then comparative transcriptomes were used for the first time to reveal the molecular mechanisms underlying the reproductive plasticity of workers. Results We identified 38,070 differentially expressed genes and found a pattern of gene expression involved in the differentiation of the workers into reproductives. 12, 543 genes were specifically upregulated in the isolated workers. Twenty-five signal transduction pathways classified into environmental information processing were related to the differentiation of workers into reproductives. Ras functions as a signalling switch regulates the reproductive plasticity of workers. The catalase gene which is related to longevity was up-regulated in reproductives. Conclusion We demonstrate that workers leaving the natal colony can induce the expression of stage-specific genes in the workers, which leads to the differentiation of workers into reproductives and suggests that the signal transduction along the Ras-MAPK pathway crucially controls the reproductive plasticity of the workers. This study also provides an important model for revealing the molecular mechanism of longevity changes.

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A simple Agrobacterium-mediated stable transformation technique for the hornwort model Anthoceros agrestis

10.1101/2021.01.07.425778 ◽

2021 ◽

Author(s):

Eftychios Frangedakis ◽

Manuel Waller ◽

Tomoaki Nishiyama ◽

Hirokazu Tsukaya ◽

Xia Xu ◽

...

Keyword(s):

Molecular Mechanisms ◽

Genetic Manipulation ◽

Fluorescent Proteins ◽

Land Plant ◽

Plant Evolution ◽

Stable Transformation ◽

35S Promoter ◽

Low Light ◽

Transformation Technique ◽

High Transformation

We have developed a simple Agrobacterium-mediated method for the stable transformation of the hornwort Anthoceros agrestis, the fifth bryophyte species for which a genetic manipulation technique becomes available. High transformation efficiency was achieved by using thallus tissue grown under low-light conditions. We generated a total of 216 transgenic A. agrestis lines expressing the β-Glucuronidase (GUS), cyan, green, and yellow fluorescent proteins under the control of the CaMV 35S promoter and several endogenous promoters. Nuclear and plasma membrane localization with multiple color fluorescent proteins was also confirmed. The transformation technique described here should pave the way for detailed molecular and genetic studies of hornwort biology, providing much needed insight into the molecular mechanisms underlying symbiosis, carbon-concentrating mechanism, RNA editing, and land plant evolution in general.

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Intracellular survival ofBurkholderia cepaciacomplex in phagocytic cells

Canadian Journal of Microbiology ◽

10.1139/cjm-2015-0316 ◽

2015 ◽

Vol 61 (9) ◽

pp. 607-615 ◽

Cited By ~ 23

Author(s):

Miguel A. Valvano

Keyword(s):

Burkholderia Cepacia ◽

Molecular Mechanisms ◽

Inflammatory Responses ◽

Genetic Manipulation ◽

Intracellular Survival ◽

Burkholderia Cenocepacia ◽

Burkholderia Cepacia Complex ◽

Host Responses ◽

Current View ◽

Phagocytic Cells

Burkholderia cepacia complex (Bcc) species are a group of Gram-negative opportunistic pathogens that infect the airways of cystic fibrosis patients, and occasionally they infect other immunocompromised patients. Bcc bacteria display high-level multidrug resistance and chronically persist in the infected host while eliciting robust inflammatory responses. Studies using macrophages, neutrophils, and dendritic cells, combined with advances in the genetic manipulation of these bacteria, have increased our understanding of the molecular mechanisms of virulence in these pathogens and the molecular details of cell-host responses triggering inflammation. This article discusses our current view of the intracellular survival of Burkholderia cenocepacia within macrophages.

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Single-cell RNA-seq analysis revealed long-lasting adverse effects of tamoxifen on neurogenesis in prenatal and adult brains

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1918883117 ◽

2020 ◽

Vol 117 (32) ◽

pp. 19578-19589 ◽

Cited By ~ 2

Author(s):

Chia-Ming Lee ◽

Liqiang Zhou ◽

Jiping Liu ◽

Jiayu Shi ◽

Yanan Geng ◽

...

Keyword(s):

Adverse Effects ◽

Single Cell ◽

Molecular Mechanisms ◽

Genetic Manipulation ◽

Lineage Tracing ◽

In Vitro Assays ◽

Fetal Mortality ◽

Neural Lineage ◽

Cortical Neurogenesis

The CreER/LoxP system is widely accepted to track neural lineages and study gene functions upon tamoxifen (TAM) administration. We have observed that prenatal TAM treatment caused high rates of delayed delivery and fetal mortality. This substance could produce undesired results, leading to data misinterpretation. Here, we report that administration of TAM during early stages of cortical neurogenesis promoted precocious neural differentiation, while it inhibited neural progenitor cell (NPC) proliferation. The TAM-induced inhibition of NPC proliferation led to deficits in cortical neurogenesis, dendritic morphogenesis, synaptic formation, and cortical patterning in neonatal and postnatal offspring. Mechanistically, by employing single-cell RNA-sequencing (scRNA-seq) analysis combined with in vivo and in vitro assays, we show TAM could exert these drastic effects mainly through dysregulating the Wnt-Dmrta2 signaling pathway. In adult mice, administration of TAM significantly attenuated NPC proliferation in both the subventricular zone and the dentate gyrus. This study revealed the cellular and molecular mechanisms for the adverse effects of TAM on corticogenesis, suggesting that care must be taken when using the TAM-induced CreER/LoxP system for neural lineage tracing and genetic manipulation studies in both embryonic and adult brains.

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Feedback regulation of COOLAIR expression controls seed dormancy and flowering time

Science ◽

10.1126/science.aar7361 ◽

2018 ◽

Vol 360 (6392) ◽

pp. 1014-1017 ◽

Cited By ~ 32

Author(s):

Min Chen ◽

Steven Penfield

Keyword(s):

Flowering Time ◽

Seed Dormancy ◽

Feedback Regulation ◽

Day Length ◽

Developmental Transitions ◽

Temperature Changes ◽

Plant Uses ◽

Seasonal Signals ◽

Flowering Locus ◽

Response To Temperature

Plants integrate seasonal signals, including temperature and day length, to optimize the timing of developmental transitions. Seasonal sensing requires the activity of two proteins, FLOWERING LOCUS C (FLC) and FLOWERING LOCUS T (FT), that control certain developmental transitions in plants. During reproductive development, the mother plant uses FLC and FT to modulate progeny seed dormancy in response to temperature. We found that for regulation of seed dormancy, FLC and FT function in opposite configuration to how those same genes control time to flowering. For seed dormancy, FT regulates seed dormancy through FLC gene expression and regulates chromatin state by activating antisense FLC transcription. Thus, in Arabidopsis the same genes controlled in opposite format regulate flowering time and seed dormancy in response to the temperature changes that characterize seasons.

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