scholarly journals The Neuropeptide PDF Is Crucial for Delaying the Phase of Drosophila’s Evening Neurons Under Long Zeitgeber Periods

2021 ◽  
Vol 36 (5) ◽  
pp. 442-460
Author(s):  
Koustubh M. Vaze ◽  
Charlotte Helfrich-Förster
Keyword(s):  
Activity Rhythm ◽  
Fruit Fly ◽  
Neuronal Firing ◽  
Day Length ◽  
Wild Type ◽  
Total Delay ◽  
Pigment Dispersing Factor ◽  
Activity Phase ◽  
Precise Understanding ◽  
Wide Range

Circadian clocks schedule biological functions at a specific time of the day. Full comprehension of the clock function requires precise understanding of their entrainment to the environment. The phase of entrained clock is plastic, which depends on different factors such as the period of endogenous oscillator, the period of the zeitgeber cycle (T), and the proportion of light and darkness (day length). The circadian clock of fruit fly Drosophila melanogaster is able to entrain to a wide range of T-cycles and day lengths. Here, we investigated the importance of the neuropeptide Pigment-Dispersing Factor (PDF) for entrainment by systematically studying locomotor activity rhythms of Pdf 0 mutants and wild-type flies under different T-cycles (T22 to T32) and different day lengths (8, 12, and 16 hour [h]). Furthermore, we analysed PERIOD protein oscillations in selected groups of clock neurons in both genotypes under T24 and T32 at a day length of 16 h. As expected, we found that the phase of Drosophila’s evening activity and evening neurons advanced with increasing T in all the day lengths. This advance was much larger in Pdf 0 mutants (~7 h) than in wild-type flies causing (1) pronounced desynchrony between morning and evening neurons and (2) evening activity to move in the morning instead of the evening. Most interestingly, we found that the lights-off transition determines the phase of evening neurons in both genotypes and that PDF appears necessary to delay the evening neurons by ~3 h to their wild-type phase. Thus, in T32, PDF first delays the molecular cycling in the evening neurons, and then, as shown in previous studies, delays their neuronal firing rhythms to produce a total delay of ~7 h necessary for a wild-type evening activity phase. We conclude that PDF is crucial for appropriate phasing of Drosophila activity rhythm.

scholarly journals Neuroendocrine Regulation of Reproductive Dormancy in the Fruit Fly Drosophila melanogaster: A Review of Juvenile Hormone-Dependent Regulation

2021 ◽  
Vol 9 ◽  
Author(s):  
Yoshitomo Kurogi ◽  
Yosuke Mizuno ◽  
Eisuke Imura ◽  
Ryusuke Niwa
Keyword(s):  
Drosophila Melanogaster ◽  
Juvenile Hormone ◽  
Environmental Conditions ◽  
Fruit Fly ◽  
Reproductive Organs ◽  
Corpus Allatum ◽  
Corpora Allata ◽  
Day Length ◽  
Control Mechanisms ◽  
Wide Range

Animals can adjust their physiology, helping them survive and reproduce under a wide range of environmental conditions. One of the strategies to endure unfavorable environmental conditions such as low temperature and limited food supplies is dormancy. In some insect species, this may manifest as reproductive dormancy, which causes their reproductive organs to be severely depleted under conditions unsuitable for reproduction. Reproductive dormancy in insects is induced by a reduction in juvenile hormones synthesized in the corpus allatum (pl. corpora allata; CA) in response to winter-specific environmental cues, such as low temperatures and short-day length. In recent years, significant progress has been made in the study of dormancy-inducing conditions dependent on CA control mechanisms in Drosophila melanogaster. This review summarizes dormancy control mechanisms in D. melanogaster and discusses the implications for future studies of insect dormancy, particularly focusing on juvenile hormone-dependent regulation.

scholarly journals Natural Zeitgebers Under Temperate Conditions Cannot Compensate for the Loss of a Functional Circadian Clock in Timing of a Vital Behavior in Drosophila

2021 ◽  
pp. 074873042199811
Author(s):  
Franziska Ruf ◽  
Oliver Mitesser ◽  
Simon Tii Mungwa ◽  
Melanie Horn ◽  
Dirk Rieger ◽  
...  
Keyword(s):  
Molecular Clock ◽  
Time Window ◽  
Fruit Fly ◽  
Diel Activity ◽  
Wild Type ◽  
Statistical Measures ◽  
Clock Mutant ◽  
Full Complement ◽  
The Right

The adaptive significance of adjusting behavioral activities to the right time of the day seems obvious. Laboratory studies implicated an important role of circadian clocks in behavioral timing and rhythmicity. Yet, recent studies on clock-mutant animals questioned this importance under more naturalistic settings, as various clock mutants showed nearly normal diel activity rhythms under seminatural zeitgeber conditions. We here report evidence that proper timing of eclosion, a vital behavior of the fruit fly Drosophila melanogaster, requires a functional molecular clock under quasi-natural conditions. In contrast to wild-type flies, period01 mutants with a defective molecular clock showed impaired rhythmicity and gating in a temperate environment even in the presence of a full complement of abiotic zeitgebers. Although period01 mutants still eclosed during a certain time window during the day, this time window was much broader and loosely defined, and rhythmicity was lower or lost as classified by various statistical measures. Moreover, peak eclosion time became more susceptible to variable day-to-day changes of light. In contrast, flies with impaired peptidergic interclock signaling ( Pdf01 and han5304 PDF receptor mutants) eclosed mostly rhythmically with normal gate sizes, similar to wild-type controls. Our results suggest that the presence of natural zeitgebers is not sufficient, and a functional molecular clock is required to induce stable temporal eclosion patterns in flies under temperate conditions with considerable day-to-day variation in light intensity and temperature. Temperate zeitgebers are, however, sufficient to functionally rescue a loss of PDF-mediated clock-internal and -output signaling

scholarly journals Genotype-Specific Signal Generation Based on Digestion of 3-Way DNA Junctions: Application to KRAS Variation Detection

2006 ◽  
Vol 52 (10) ◽  
pp. 1855-1863 ◽  
Author(s):  
Giulia Amicarelli ◽  
Daniel Adlerstein ◽  
Erlet Shehi ◽  
Fengfei Wang ◽  
G Mike Makrigiorgos
Keyword(s):  
Nucleic Acid ◽  
Concordance Rate ◽  
Signal Generation ◽  
Sequence Variants ◽  
Wild Type ◽  
Specific Signal ◽  
Novel Technology ◽  
Dna Junctions ◽  
Wide Range ◽  
Kras Codon

Abstract Background: Genotyping methods that reveal single-nucleotide differences are useful for a wide range of applications. We used digestion of 3-way DNA junctions in a novel technology, OneCutEventAmplificatioN (OCEAN) that allows sequence-specific signal generation and amplification. We combined OCEAN with peptide-nucleic-acid (PNA)-based variant enrichment to detect and simultaneously genotype v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) codon 12 sequence variants in human tissue specimens. Materials and Methods: We analyzed KRAS codon 12 sequence variants in 106 lung cancer surgical specimens. We conducted a PNA-PCR reaction that suppresses wild-type KRAS amplification and genotyped the product with a set of OCEAN reactions carried out in fluorescence microplate format. The isothermal OCEAN assay enabled a 3-way DNA junction to form between the specific target nucleic acid, a fluorescently labeled “amplifier”, and an “anchor”. The amplifier-anchor contact contains the recognition site for a restriction enzyme. Digestion produces a cleaved amplifier and generation of a fluorescent signal. The cleaved amplifier dissociates from the 3-way DNA junction, allowing a new amplifier to bind and propagate the reaction. Results: The system detected and genotyped KRAS sequence variants down to ∼0.3% variant-to-wild-type alleles. PNA-PCR/OCEAN had a concordance rate with PNA-PCR/sequencing of 93% to 98%, depending on the exact implementation. Concordance rate with restriction endonuclease-mediated selective-PCR/sequencing was 89%. Conclusion: OCEAN is a practical and low-cost novel technology for sequence-specific signal generation. Reliable analysis of KRAS sequence alterations in human specimens circumvents the requirement for sequencing. Application is expected in genotyping KRAS codon 12 sequence variants in surgical specimens or in bodily fluids, as well as single-base variations and sequence alterations in other genes.

Disrupted circadian rhythms in VIP- and PHI-deficient mice

2003 ◽  
Vol 285 (5) ◽  
pp. R939-R949 ◽  
Author(s):  
Christopher S. Colwell ◽  
Stephan Michel ◽  
Jason Itri ◽  
Williams Rodriguez ◽  
J. Tam ◽  
...  
Keyword(s):  
Circadian Rhythms ◽  
Wheel Running ◽  
Activity Rhythm ◽  
Activity Patterns ◽  
Circadian System ◽  
Diurnal Rhythms ◽  
Constant Darkness ◽  
Light Cycle ◽  
Wild Type ◽  
Deficient Mice

The related neuropeptides vasoactive intestinal peptide (VIP) and peptide histidine isoleucine (PHI) are expressed at high levels in the neurons of the suprachiasmatic nucleus (SCN), but their function in the regulation of circadian rhythms is unknown. To study the role of these peptides on the circadian system in vivo, a new mouse model was developed in which both VIP and PHI genes were disrupted by homologous recombination. In a light-dark cycle, these mice exhibited diurnal rhythms in activity which were largely indistinguishable from wild-type controls. In constant darkness, the VIP/PHI-deficient mice exhibited pronounced abnormalities in their circadian system. The activity patterns started ∼8 h earlier than predicted by the previous light cycle. In addition, lack of VIP/PHI led to a shortened free-running period and a loss of the coherence and precision of the circadian locomotor activity rhythm. In about one-quarter of VIP/PHI mice examined, the wheel-running rhythm became arrhythmic after several weeks in constant darkness. Another striking example of these deficits is seen in the split-activity patterns expressed by the mutant mice when they were exposed to a skeleton photoperiod. In addition, the VIP/PHI-deficient mice exhibited deficits in the response of their circadian system to light. Electrophysiological analysis indicates that VIP enhances inhibitory synaptic transmission within the SCN of wild-type and VIP/PHI-deficient mice. Together, the observations suggest that VIP/PHI peptides are critically involved in both the generation of circadian oscillations as well as the normal synchronization of these rhythms to light.

Modifications of Seizure Susceptibility inDrosophila

2000 ◽  
Vol 83 (2) ◽  
pp. 998-1009 ◽  
Author(s):  
Daniel Kuebler ◽  
Mark A. Tanouye
Keyword(s):  
Idiopathic Epilepsy ◽  
Seizure Susceptibility ◽  
Wild Type ◽  
Physiological Basis ◽  
Seizure Disorders ◽  
Spontaneous Seizures ◽  
Wide Range ◽  
Symptomatic Seizures ◽  
Type Strains ◽  
Over Time

In a given population, certain individuals are much more likely to have seizures than others. This increase in seizure susceptibility can lead to spontaneous seizures, such as seen in idiopathic epilepsy, or to symptomatic seizures that occur after insults to the nervous system. Despite the frequency of these seizure disorders in the human population, the genetic and physiological basis for these defects remains unclear. The present study makes use of Drosophila as a potentially powerful model for understanding seizure susceptibility in humans. In addition to the genetic and molecular advantages of using Drosophila, it has been found that seizures in Drosophila share much in common with seizures seen in humans. However, the most powerful aspect of this model lies in the ability to accurately measure seizure susceptibility across genotypes and over time. In the current study seizure susceptibility was quantified in a variety of mutant and wild-type strains, and it was found that genetic mutations can modulate susceptibility over an extremely wide range. This genetic modulation of seizure susceptibility apparently occurs without affecting the threshold of individual neurons. Seizure susceptibility also varied depending on the experience of the fly, decreasing immediately after a seizure and then gradually increasing over time. A novel phenomenon was also identified in which seizures are suppressed after certain high-intensity stimuli. These results demonstrate the utility of Drosophila as a model system for studying human seizure disorders and provide insights into the possible mechanisms by which seizure susceptibility is modified.

scholarly journals Virulence and Metabolic Characteristics of Salmonella enterica Serovar Enteritidis Strains with DifferentsefDVariants in Hens

2012 ◽  
Vol 78 (18) ◽  
pp. 6405-6412 ◽  
Author(s):  
Cesar A. Morales ◽  
Jean Guard ◽  
Roxana Sanchez-Ingunza ◽  
Devendra H. Shah ◽  
Mark Harrison
Keyword(s):  
Salmonella Enterica ◽  
Egg Production ◽  
The Body ◽  
Wild Type ◽  
Salmonella Enterica Serovar Enteritidis ◽  
Blood Calcium ◽  
Content Type ◽  
Metabolic Characteristics ◽  
Wide Range ◽  
Metabolic Properties

ABSTRACTSalmonella entericaserovar Enteritidis is one of a fewSalmonella entericaserotypes that has SEF14 fimbriae encoded by thesefoperon, which consists of 4 cotranscribed genes,sefABCD, regulated bysefR. A parental strain was used to construct asefDmutant and its complement, and all 3 strains were compared for gene expression, metabolic properties, and virulence characteristics in hens. Transcription ofsefDby wild type was suppressed at 42°C and absent for the mutant under conditions where the complemented mutant had 103times higher transcription. Growth of the complemented mutant was restricted in comparison to that of the mutant and wild type. Hens infected with the wild type and mutant showed decreased blood calcium and egg production, but infection with the complemented mutant did not. Thus, the absence ofsefDcorrelated with increased metabolic capacity and enhanced virulence of the pathogen. These results suggest that any contribution thatsefDmakes to egg contamination is either unknown or would be limited to early transmission from the environment to the host. Absence ofsefD, either through mutation or by suppression of transcription at the body temperature of the host, may contribute to the virulence ofSalmonella entericaby facilitating growth on a wide range of metabolites.

Genetic characterization of Rhizobium sp. strain TAL1145 that nodulates tree legumes

1994 ◽  
Vol 40 (3) ◽  
pp. 208-215 ◽  
Author(s):  
M. L. C. George ◽  
J. P. W. Young ◽  
D. Borthakur
Keyword(s):  
Rhizobium Leguminosarum ◽  
Genetic Characterization ◽  
Rhizobium Meliloti ◽  
Wild Type ◽  
Tree Legumes ◽  
Wide Range ◽  
The Common ◽  
Rrna Sequences ◽  
Rhizobium Sp

Rhizobium sp. strain TALI 145 nodulates Leucaena ieucocephaia and Phaseolus vulgaris, in addition to a wide range of tropical tree legumes. Six overlapping clones that complemented nodulation defects in leucaena and bean rhizobia were isolated and a 40-kb map of the symbiosis region was constructed. The common nod and nifA genes were situated approximately 17 kb apart, with the nodlJ genes in between. These clones enabled a derivative of TAL1145 carrying a partially deleted pSym to form ineffective nodules on both leucaena and bean, and a similar derivative of Rhizobium etli TAL182 to form ineffective nodules on bean. When two representative clones, pUHR9 and pUHR114, were each transferred to wild-type rhizobial strains, they allowed ineffective nodulation by Rhizobium meliloti on both leucaena and bean and by Rhizobium leguminosarum bv. viciae on bean. Transconjugants of R. leguminosarum bv. trifolii formed effective nodules on leucaena and ineffective nodules on bean. Tn5 mutagenesis of the symbiosis region resulted in a variety of nodulation and fixation phenotypes on leucaena and bean. On the basis of 16S rRNA sequences, TAL1145 was found to be distinct from both R. tropici and NGR234, the two groups of leucaena symbionts that were previously described.Key words: Rhizobium, Leucaena leucocephala, nodulation, nitrogen fixation.

Mice lacking neuronal nicotinic acetylcholine receptor β4-subunit and mice lacking both α5- and β4-subunits are highly resistant to nicotine-induced seizures

2004 ◽  
Vol 17 (2) ◽  
pp. 221-229 ◽  
Author(s):  
Merav Kedmi ◽  
Arthur L. Beaudet ◽  
Avi Orr-Urtreger
Keyword(s):  
Nicotinic Acetylcholine Receptors ◽  
Acetylcholine Receptors ◽  
Mutant Mice ◽  
Wild Type ◽  
Nicotinic Acetylcholine ◽  
Nocturnal Frontal Lobe Epilepsy ◽  
Wide Range ◽  
High Doses ◽  
Dose Dependent ◽  
Rate Of Response

Nicotine, the main addictive component of tobacco, evokes a wide range of dose-dependent behaviors in rodents, and when administrated in high doses, it can induce clonic-tonic seizures. Nicotine acts through the nicotinic acetylcholine receptors (nAChRs). Mutations in the human α4- and the β2-nAChR subunit genes cause autosomal dominant nocturnal frontal lobe epilepsy. Using transgenic mice with mutations in nAChR subunits, it was demonstrated previously that the α4-, α5-, and α7-subunits are involved in nicotine-induced seizures. To examine the possibility that the β4-subunit is also involved in this phenotype, we tested mice with homozygous β4-subunit deficiency. The β4 null mice were remarkably resistant to nicotine-induced seizures compared with wild-type and α5 null mice. We also generated mice with double deficiency of both α5- and β4-nAChR subunits and demonstrated that they were more resistant to nicotine’s convulsant effect than either the α5 or the β4 single mutant mice. In addition, the single α5 mutants and the double α5β4-deficient mice exhibited a significantly shorter latency time to seizure than that of the wild-type mice. Our results thus show that β4-containing nAChRs have a crucial role in the pathogenesis of nicotine-induced seizures. Furthermore, by comparing multiple mutant mice with single and double subunit deficiency, we suggest that nicotinic receptors containing either α5- or β4-subunits are involved in nicotine-induced seizures and that receptors containing both subunits are likely to contribute to this phenomena as well. However, the α5-subunit, but not the β4-subunit, regulates the rate of response to high doses of nicotine.

scholarly journals Genetic variation in the social environment affects behavioral phenotypes of oxytocin receptor mutants in zebrafish

2020 ◽  
Author(s):  
D. Ribeiro ◽  
A.R. Nunes ◽  
M.C. Teles ◽  
S. Anbalagan ◽  
J. Blechman ◽  
...  
Keyword(s):  
Social Behavior ◽  
Social Environment ◽  
Oxytocin Receptor ◽  
The Other ◽  
Wild Type ◽  
Knock Out ◽  
The Social ◽  
Wide Range ◽  
Knockout Line ◽  
Genetically Modified Animals

AbstractOxytocin-like peptides have been implicated in the regulation of a wide range of social behaviors across taxa. On the other hand, the social environment, which is composed of conspecifics genotypes, is also known to influence the development of social behavior, creating the possibility for indirect genetic effects. Here we used a knockout line for the oxytocin receptor in zebrafish to investigate how the genotypic composition of the social environment (Es) interacts with the oxytocin genotype (G) of the focal individual in the regulation of its social behavior. For this purpose, we have raised wild-type or knock-out zebrafish in either wild-type or knock-out shoals and tested different components of social behavior in adults. GxEs effects were detected in some behaviors, highlighting the need to control for GxEs effects when interpreting results of experiments using genetically modified animals, since the social environment can either rescue or promote phenotypes associated with specific genes.

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