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

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

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2004262117 ◽

2020 ◽

Vol 117 (26) ◽

pp. 15293-15304 ◽

Cited By ~ 2

Author(s):

Antoine Abrieux ◽

Yongbo Xue ◽

Yao Cai ◽

Kyle M. Lewald ◽

Hoang Nhu Nguyen ◽

...

Keyword(s):

Molecular Mechanisms ◽

Environmental Changes ◽

Genetic Manipulation ◽

Physiological Responses ◽

Day Length ◽

Short Photoperiod ◽

Eyes Absent ◽

Temperature Changes ◽

Winter Conditions ◽

Timing Mechanisms

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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Differential Morpho-Physiological and Transcriptomic Responses to Heat Stress in Two Blueberry Species

International Journal of Molecular Sciences ◽

10.3390/ijms22052481 ◽

2021 ◽

Vol 22 (5) ◽

pp. 2481

Author(s):

Jodi Callwood ◽

Kalpalatha Melmaiee ◽

Krishnanand P. Kulkarni ◽

Amaranatha R. Vennapusa ◽

Diarra Aicha ◽

...

Keyword(s):

Heat Stress ◽

Molecular Mechanisms ◽

Stomatal Closure ◽

Enrichment Analysis ◽

Leaf Size ◽

Vaccinium Corymbosum ◽

Climatic Conditions ◽

Differentially Expressed ◽

Transcriptomic Changes ◽

Go Terms

Blueberries (Vaccinium spp.) are highly vulnerable to changing climatic conditions, especially increasing temperatures. To gain insight into mechanisms underpinning the response to heat stress, two blueberry species were subjected to heat stress for 6 and 9 h at 45 °C, and leaf samples were used to study the morpho-physiological and transcriptomic changes. As compared with Vaccinium corymbosum, Vaccinium darrowii exhibited thermal stress adaptation features such as small leaf size, parallel leaf orientation, waxy leaf coating, increased stomatal surface area, and stomatal closure. RNAseq analysis yielded ~135 million reads and identified 8305 differentially expressed genes (DEGs) during heat stress against the control samples. In V. corymbosum, 2861 and 4565 genes were differentially expressed at 6 and 9 h of heat stress, whereas in V. darrowii, 2516 and 3072 DEGs were differentially expressed at 6 and 9 h, respectively. Among the pathways, the protein processing in the endoplasmic reticulum (ER) was the highly enriched pathway in both the species: however, certain metabolic, fatty acid, photosynthesis-related, peroxisomal, and circadian rhythm pathways were enriched differently among the species. KEGG enrichment analysis of the DEGs revealed important biosynthesis and metabolic pathways crucial in response to heat stress. The GO terms enriched in both the species under heat stress were similar, but more DEGs were enriched for GO terms in V. darrowii than the V. corymbosum. Together, these results elucidate the differential response of morpho-physiological and molecular mechanisms used by both the blueberry species under heat stress, and help in understanding the complex mechanisms involved in heat stress tolerance.

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Discovering the drivers of clonal hematopoiesis

10.1101/2020.10.22.350140 ◽

2020 ◽

Cited By ~ 1

Author(s):

Oriol Pich ◽

Iker Reyes-Salazar ◽

Abel Gonzalez-Perez ◽

Nuria Lopez-Bigas

Keyword(s):

Positive Selection ◽

Molecular Mechanisms ◽

Somatic Mutations ◽

Cancer Genomics ◽

Variant Calling ◽

Selective Advantage ◽

Cancer Genes ◽

Driver Genes ◽

Hematopoietic Stem ◽

Clonal Hematopoiesis

AbstractMutations in genes that confer a selective advantage to hematopoietic stem cells (HSCs) in certain conditions drive clonal hematopoiesis (CH). While some CH drivers have been identified experimentally or through epidemiological studies, the compendium of all genes able to drive CH upon mutations in HSCs is far from complete. We propose that identifying signals of positive selection in blood somatic mutations may be an effective way to identify CH driver genes, similarly as done to identify cancer genes. Using a reverse somatic variant calling approach, we repurposed whole-genome and whole-exome blood/tumor paired samples of more than 12,000 donors from two large cancer genomics cohorts to identify blood somatic mutations. The application of IntOGen, a robust driver discovery pipeline, to blood somatic mutations across both cohorts, and more than 24,000 targeted sequenced samples yielded a list of close to 70 genes with signals of positive selection in CH, available at http://www.intogen.org/ch. This approach recovers all known CH genes, and discovers novel candidates. Generating this compendium is an essential step to understand the molecular mechanisms of CH and to accurately detect individuals with CH to ascertain their risk to develop related diseases.

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Effects of Life-form and Plants Functional Traits on Carbon, Nitrogen and Sulfur Distributed in Different Parts in Dry Region of Western India

10.21203/rs.3.rs-230054/v1 ◽

2021 ◽

Author(s):

Genda Singh ◽

Bilas Singh

Keyword(s):

Functional Traits ◽

Life Form ◽

Life Forms ◽

Climatic Conditions ◽

Western India ◽

High Concentration ◽

N Content ◽

Medicinal Uses ◽

Leguminous Species ◽

C And N

Abstract Background: Plants adapt to adverse environmental conditions accumulate varying concentrations of carbon (C), nitrogen (N) and sulfur (S) compounds to cope up with adverse climatic conditions. Carbon, N and S concentrations were determined in roots, stem and leaves of 33 species of trees/shrubs with objectives to observe the effects of life-form and plants functional traits, and select species with high concentration of these elements for their utilization in afforestation and medicinal uses. Results: Concentrations of C, N, and S and C: N and N: S ratio varied (P<0.05) between species, organs, life-forms and functional traits (legume vs non-legume). These variables were higher (except C in roots and stem) in trees than shrubs, and in leguminous than non-leguminous species. Non-leguminous species showed high S content and low N: S ratio. Antagonistic and synergistic relations were observed between C and N, and N and S concentration respectively. Species showed varying potential in assimilating carbon by regulating uptake and accumulation of these elements in different organs making them adapt to the habitats affected by drought and salinity. We observed strong plant size/life-form effects on C and N content and C: N and N: S ratios and of function on S content. Conclusions: Life-form/size and varying functions of the species determined C: nutrient ratio and elemental composition and helped adapting varying environmental stresses. This study assist in selecting species of high carbon, nitrogen and S content to utilize them in afforesting the areas affected by water and salt stresses, increased carbon storage and species with high S/N content in medicinal uses.

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Bryophytes on the devastated territories of sulphur deposits and their role in restoration of dump substrate

Biosystems Diversity ◽

10.15421/011850 ◽

2018 ◽

Vol 26 (4) ◽

pp. 339-353

Author(s):

I. V. Rabyk ◽

O. V. Lobachevska ◽

N. Y. Kyyak ◽

O. I. Shcherbachenko

Keyword(s):

Plant Cover ◽

Photosynthetic Apparatus ◽

Life Forms ◽

Climatic Conditions ◽

Projective Cover ◽

Biogenic Elements ◽

Moisture Regime ◽

Moss Species ◽

Vegetative Period ◽

Specific Composition

Bryophytes possess a wide ecological diapason allowing them to populate substrates of technogenic origins which are scarcely suitable or completely unsuitable for viability of vascular plants. 49 bryophyte species, which belong to 2 divisions, 3 classes, 8 orders, 17 families, and 33 genera have been found on the dump territory of sulphur extraction of the mining-chemical enterprise “Sirka” (Yavoriv district, Lviv region). Seven transects, three on the north slope (base, slope, top), three on the south slope and one on the plateau were laid for sample selections. 20 investigated 0.5 × 0.5 m plots located 2 m apart were analyzed within each 10 × 10 m transect. Specific composition, life forms, projective cover, biomass of bryophytes, numbers of male, female and sterile plants, moisture content in the turfs, pH and physiological investigation of mosses were determined on each plot. The quantitative analysis of the biomorphological structure allowed us to establish the dependence of the spread of life forms on exposition and slope height; essential variability of the projective cover and moss biomass. Bryophyte cover plays an essential part in optimization of the moisture regime and surface layer temperature of technogenic substrates, improving the conditions of growth localities. We established that on the dump the dominant moss species are dioecious with a high level of reproductive effort (sexual and sexless), with short ontogenesis and age of first reproduction, which provides the chance to produce the maximum number of progeny in the minimum period and to form a complete moss cover. The analysis of seasonal moss photosynthesis dynamics has demonstrated the adaptability of moss photosynthetic apparatus to contrasting climatic conditions and the ability to support the intensity of photosynthetic processes on a rather stable level during the vegetative period. Our research showed that bryophytes play an important role in productivity of plant cover on the post-technogenic territories of sulphur extraction. It was found that bryophytes play a role in accumulation of organic carbon and biogenic elements in the substrate of the sulphur extraction dump . Carrying out research of specific composition dynamics and species activity is the precondition for revealing the essence of the dynamic processes taking place in the structure of the bryophyte communities on devastated territories and the influence of these processes on the formation of vegetation on dump complexes.

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Light effects on circadian timing system of a diurnal primate, the squirrel monkey

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1985.249.2.r274 ◽

1985 ◽

Vol 249 (2) ◽

pp. R274-R280 ◽

Cited By ~ 6

Author(s):

T. M. Hoban ◽

F. M. Sulzman

Keyword(s):

Squirrel Monkey ◽

Response Curve ◽

Phase Response Curve ◽

Phase Response ◽

Day Length ◽

Circadian Timing ◽

Subjective Night ◽

Timing System ◽

Circadian Timing System ◽

Light Effects

We examined light effects on the circadian timing system of the squirrel monkey. A phase-response curve to 1-h pulses of light was constructed for the drinking rhythm of six animals. The phase-response curve was the same type as that exhibited by nocturnal rodents, with phase delays occurring early in the subjective night and phase advances late in the subjective night. The range of entrainment of 10 monkeys to days with 1 h light and x h dark was determined. Five monkeys used to generate the phase-response curve were also used in the range of entrainment determination. For short light-dark cycles the range of entrainment was smaller than that expected, with no monkey entraining to a day length of less than 23.5 h.

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Haemoglobin function in aquatic animals: molecular adaptations to environmental challenge

Marine and Freshwater Research ◽

10.1071/mf99034 ◽

1999 ◽

Cited By ~ 12

Author(s):

Rufus M. G. Wells

Keyword(s):

Molecular Mechanisms ◽

Population Studies ◽

Selective Advantage ◽

Oxygen Binding ◽

Binding Properties ◽

Diverse Range ◽

Physiological Adaptations ◽

Aquatic Vertebrates ◽

Oxygen Tensions ◽

Adaptive Nature

The adaptive nature of haemoglobin function in a diverse range of aquatic ectothermic vertebrates is demonstrated by its intrinsic oxygen-binding properties and by erythrocyte cofactor modulation of Hb function. The selective advantage of heterogeneous isohaemoglobins and polymorphic expression of functionally distinct components is considered in relation to environmental oxygen tensions and temperature. The difficulty of comparing physiological adaptations in divergent species is emphasized. Recent population studies suggest that relatively minor differences in environmental conditions, particularly temperature, direct the expression of functionally heterogeneous haemoglobins, although the thresholds for expression have not been established. Regulatory mechanisms underpinning the molecular mechanisms for hypoxic induction of Hb in aquatic vertebrates are not well understood.

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Measuring Food Anticipation in Mice

Clocks & Sleep ◽

10.3390/clockssleep1010007 ◽

2018 ◽

Vol 1 (1) ◽

pp. 65-74

Author(s):

Tomaz Martini ◽

Jürgen Ripperger ◽

Urs Albrecht

Keyword(s):

Body Temperature ◽

Gene Function ◽

Metabolic Disorders ◽

Genetic Alterations ◽

Circadian System ◽

Physiological Adaptation ◽

Pharmacological Intervention ◽

Feeding Time ◽

Evolutionary Advantage ◽

Internal Body

The interplay between the circadian system and metabolism may give animals an evolutionary advantage by allowing them to anticipate food availability at specific times of the day. Physiological adaptation to feeding time allows investigation of animal parameters and comparison of food anticipation between groups of animals with genetic alterations and/or post pharmacological intervention. Such an approach is vital for understanding gene function and mechanisms underlying the temporal patterns of both food anticipation and feeding. Exploring these mechanisms will allow better understanding of metabolic disorders and might reveal potential new targets for pharmacological intervention. Changes that can be easily monitored and that represent food anticipation on the level of the whole organism are a temporarily restricted increase of activity and internal body temperature.

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Nickel Promotes Biofilm Formation by Escherichia coli K-12 Strains That Produce Curli

Applied and Environmental Microbiology ◽

10.1128/aem.02171-08 ◽

2009 ◽

Vol 75 (6) ◽

pp. 1723-1733 ◽

Cited By ~ 40

Author(s):

Claire Perrin ◽

Romain Briandet ◽

Gregory Jubelin ◽

Philippe Lejeune ◽

Marie-Andrée Mandrand-Berthelot ◽

...

Keyword(s):

Escherichia Coli ◽

Biofilm Formation ◽

Molecular Mechanisms ◽

Selective Advantage ◽

Bacterial Survival ◽

Toxic Compounds ◽

E Coli ◽

Transcriptional Effect ◽

K 12 ◽

Encoding Genes

ABSTRACT The survival of bacteria exposed to toxic compounds is a multifactorial phenomenon, involving well-known molecular mechanisms of resistance but also less-well-understood mechanisms of tolerance that need to be clarified. In particular, the contribution of biofilm formation to survival in the presence of toxic compounds, such as nickel, was investigated in this study. We found that a subinhibitory concentration of nickel leads Escherichia coli bacteria to change their lifestyle, developing biofilm structures rather than growing as free-floating cells. Interestingly, whereas nickel and magnesium both alter the global cell surface charge, only nickel promotes biofilm formation in our system. Genetic evidence indicates that biofilm formation induced by nickel is mediated by the transcriptional induction of the adhesive curli-encoding genes. Biofilm formation induced by nickel does not rely on efflux mechanisms using the RcnA pump, as these require a higher concentration of nickel to be activated. Our results demonstrate that the nickel-induced biofilm formation in E. coli is an adaptational process, occurring through a transcriptional effect on genes coding for adherence structures. The biofilm lifestyle is obviously a selective advantage in the presence of nickel, but the means by which it improves bacterial survival needs to be investigated.

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