scholarly journals Localized epigenetic silencing of a damage-activated WNT enhancer limits regeneration in mature Drosophila imaginal discs

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Robin E Harris ◽  
Linda Setiawan ◽  
Josh Saul ◽  
Iswar K Hariharan
Keyword(s):  
Larval Instar ◽  
Cellular Responses ◽  
Imaginal Discs ◽  
Epigenetic Silencing ◽  
Regenerative Capacity ◽  
The Third ◽  
Multiple Genes ◽  
Gene Functions

Many organisms lose the capacity to regenerate damaged tissues as they mature. Damaged Drosophila imaginal discs regenerate efficiently early in the third larval instar (L3) but progressively lose this ability. This correlates with reduced damage-responsive expression of multiple genes, including the WNT genes wingless (wg) and Wnt6. We demonstrate that damage-responsive expression of both genes requires a bipartite enhancer whose activity declines during L3. Within this enhancer, a damage-responsive module stays active throughout L3, while an adjacent silencing element nucleates increasing levels of epigenetic silencing restricted to this enhancer. Cas9-mediated deletion of the silencing element alleviates WNT repression, but is, in itself, insufficient to promote regeneration. However, directing Myc expression to the blastema overcomes repression of multiple genes, including wg, and restores cellular responses necessary for regeneration. Localized epigenetic silencing of damage-responsive enhancers can therefore restrict regenerative capacity in maturing organisms without compromising gene functions regulated by developmental signals.

scholarly journals Interactions and developmental effects of mutations in the Broad-Complex of Drosophila melanogaster.

Genetics ◽  
1988 ◽  
Vol 118 (2) ◽  
pp. 247-259
Author(s):  
I Kiss ◽  
A H Beaton ◽  
J Tardiff ◽  
D Fristrom ◽  
J W Fristrom
Keyword(s):  
Drosophila Melanogaster ◽  
X Chromosome ◽  
Genetic Locus ◽  
Larval Instar ◽  
Imaginal Discs ◽  
Functional Domains ◽  
Developmental Processes ◽  
The Third ◽  
Developmental Effects ◽  
Broad Complex

Abstract The 2B5 region on the X chromosome of Drosophila melanogaster forms an early ecdysone puff at the end of the third larval instar. The region contains a complex genetic locus, the Broad-Complex (BR-C) composed of four groups of fully complementing (br, rbp, l(1)2Bc, and l(1)2Bd) alleles, and classes of noncomplementing (npr 1) and partially noncomplementing l(1)2Bab alleles. BR-C mutants prevent metamorphosis, including the morphogenesis of imaginal discs. Results are presented that indicate that the BR-C contains two major functional domains. One, the br domain is primarily, if not exclusively, involved in the elongation and eversion of appendages by imaginal discs. The second, the l(1)2Bc domain, is primarily involved in the fusion of discs to form a continuous adult epidermis. Nonetheless, the two domains may encode products with related functions because in some situations mutants in both domains appear to affect similar developmental processes.

scholarly journals Damage-responsive, maturity-silenced enhancers regulate multiple genes that direct regeneration in Drosophila

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Robin E Harris ◽  
Michael J Stinchfield ◽  
Spencer L Nystrom ◽  
Daniel J McKay ◽  
Iswar K Hariharan
Keyword(s):  
Imaginal Discs ◽  
Direct Regeneration ◽  
Regenerative Capacity ◽  
Multiple Loci ◽  
Multiple Genes ◽  
Chromatin Regulator ◽  
Sex Combs ◽  
Ability To Regenerate ◽  
Reducing Activity

Like tissues of many organisms, Drosophila imaginal discs lose the ability to regenerate as they mature. This loss of regenerative capacity coincides with reduced damage-responsive expression of multiple genes needed for regeneration. We previously showed that two such genes, wg and Wnt6, are regulated by a single damage-responsive enhancer that becomes progressively inactivated via Polycomb-mediated silencing as discs mature (Harris et al., 2016). Here we explore the generality of this mechanism and identify additional damage-responsive, maturity-silenced (DRMS) enhancers, some near genes known to be required for regeneration such as Mmp1, and others near genes that we now show function in regeneration. Using a novel GAL4-independent ablation system we characterize two DRMS-associated genes, apontic (apt), which curtails regeneration and CG9752/asperous (aspr), which promotes it. This mechanism of suppressing regeneration by silencing damage-responsive enhancers at multiple loci can be partially overcome by reducing activity of the chromatin regulator extra sex combs (esc).

scholarly journals Regenerative capacity in Drosophila imaginal discs is controlled by damage-responsive, maturity-silenced enhancers

2019 ◽  
Author(s):  
Robin E. Harris ◽  
Michael J. Stinchfield ◽  
Spencer L. Nystrom ◽  
Daniel J. McKay ◽  
Iswar K. Hariharan
Keyword(s):  
Imaginal Discs ◽  
Tissue Ablation ◽  
Regenerative Capacity ◽  
Multiple Loci ◽  
Multiple Genes ◽  
Chromatin Regulator ◽  
Sex Combs ◽  
Ability To Regenerate ◽  
Reducing Activity

SummaryLike tissues of many organisms, Drosophila imaginal discs lose the ability to regenerate as they mature. This loss of regenerative capacity coincides with reduced damage-responsive expression of multiple genes needed for regeneration. Our previous work showed that two such genes, wg and Wnt6, are regulated by a single damage-responsive enhancer, which becomes progressively inactivated via Polycomb-mediated silencing as discs mature. Here we explore the generality of this mechanism, and identify numerous damage-responsive, maturity-silenced (DRMS) enhancers, some near genes known to be required for regeneration such as Mmp1, as well as near genes that we now show function in regeneration. Using a novel GAL4-independent tissue ablation system we characterize two DRMS-associated genes, apontic (apt), which curtails regeneration and CG9752/asperous (aspr), which promotes it. This mechanism of suppressing regeneration by silencing damage-responsive enhancers at multiple loci can be partially overcome by reducing activity of the chromatin regulator extra sex combs (esc).

The Post-embryonic Development of the Tracheal System in Drosophila melanogaster

1957 ◽  
Vol s3-98 (41) ◽  
pp. 123-150
Author(s):  
JOAN M. WHITTEN
Keyword(s):  
Drosophila Melanogaster ◽  
Adult Stage ◽  
Larval Instar ◽  
Pupal Stage ◽  
Tracheal System ◽  
True Nature ◽  
The Third ◽  
Air Sacs ◽  
Abdominal Region ◽  
Pupal Cuticle

The fate of the tracheal system is traced from the first larval instar to the adult stage. The basic larval pattern conforms to that shown for other Diptera Cyclorrhapha (Whitten, 1955), and is identical in all three instars. According to previous accounts the adult system directly replaces the larval: the larval system is partly shed, partly histolysed, and the adult system arises from imaginal cell clusters independently of the preceding larval system. In contrast, it is shown here that in the cephalic, thoracic, and anterior abdominal region there is a definite continuity in the tracheal system, from larval, through pupal to the adult stage, whereas in the posterior abdominal region the larval system is histolysed, and the adult system is independent of it in origin. Moreover, in the pupal stage this region is tracheated by tracheae arising from the anterior abdominal region and belonging to a distinct pupal system. Moulting of the tracheal linings is complete at the first and second larval ecdyses, but incomplete at the third larval-pupal and pupal-adult ecdyses. In consequence, in both pupal and adult systems there are tracheae which are secreted around preexisting tracheae, others formed as new ‘branch’ tracheae, and those which have been carried over from the previous instar. In the adult the newly formed tracheae of the posterior abdominal region fall into a fourth category. Most of the adult thoracic air sacs correspond to new ‘branch’ tracheae of other instars. The pre-pupal moult and instar are discussed with reference to the tracheal system and tentative suggestions are made concerning the true nature of the pre-pupal cuticle. There is no pre-pupal tracheal system. Events traced for Drosophila would seem to be general for Cyclorrhapha, both Acalypterae and Calypterae. The separate fates of the anterior and posterior abdom inal systems, in contrast with the straightforward development in Dipterc Nematocera, would appear to mark a distinct step in the evolution of the system in Diptera.

scholarly journals Production of germ-free mosquitoes via transient colonisation allows stage-specific investigation of host-microbiota interactions

2019 ◽  
Author(s):  
Ottavia Romoli ◽  
Johan Claes Schönbeck ◽  
Siegfried Hapfelmeier ◽  
Mathilde Gendrin
Keyword(s):  
Larval Development ◽  
Emerging Adults ◽  
Larval Instar ◽  
Bacterial Colonisation ◽  
Germ Free ◽  
Functional Studies ◽  
The Third ◽  
Novel Approach ◽  
Folate Biosynthesis ◽  
Vector Borne

AbstractThe mosquito microbiota impacts the physiology of its host and is essential for normal larval development, thereby influencing transmission of vector-borne pathogens. Germ-free mosquitoes generated with current methods show larval stunting and developmental deficits. Therefore, functional studies of the mosquito microbiota have so far mostly been limited to antibiotic treatments of emerging adults. In this study, we developed a novel approach to produce germ-free Aedes aegypti mosquitoes. It is based on reversible colonisation with bacteria genetically modified to allow complete decolonisation at any developmental stage. We show that, unlike germ-free mosquitoes previously produced using sterile diets, reversibly colonised mosquitoes show no developmental retardation and reach the same size as control adults. This allowed us to uncouple the study of the microbiota in larvae and adults. In adults, we detected no impact of bacterial colonisation on mosquito fecundity or longevity. In larvae, we performed a transcriptome analysis and diet supplementation experiments following decolonisation during the third larval instar. Our data suggest that bacteria support larval development by contributing to folate biosynthesis and by enhancing energy storage. Our study establishes a novel tool to study the microbiota in insects and deepens our knowledge on the metabolic contribution of bacteria to mosquito development.

scholarly journals Efficacy of Bacillus thuringiensis (Berliner) isolates on fig moth, Ephestia cautella (Walker) Larvae

2014 ◽  
Vol 11 (2) ◽  
pp. 943-951
Author(s):  
Baghdad Science Journal
Keyword(s):  
Bacillus Thuringiensis ◽  
Larval Stage ◽  
Filter Paper ◽  
Larval Instar ◽  
Ephestia Cautella ◽  
Larval Stages ◽  
The Third ◽  
Total Percentage ◽  
First Instar ◽  
Paper Method

The following dilution 5×10-1, 10-1, 10?2 , 10-3 gm/L for the indigenous isolate of Bacillus thuringiensis bacteria and the commercially isalate were used for experiments against the different stages of fig moth of E.cautella which exposed by filter paper method. The results showed that mortality of larval stages was increased with the increasing concentration of the biocide, in addition to increase in the mortality of the larval stages reached to the highest percentage in the third days of treatment of the larval stage in comparison with the first and second days of exposure. The results also showed that the sensitivity of larval stages was increased in first and second instars while reduced in the last instars .The high percentage of first instar mortality for the indigenous isolate in the concentration of 5×10-1 was 72.8% , while the low percentage of mortality showed in the concentration of 5×10-1 for the fifth instar larvae which was 13.3% in third days of treatment while a high percentage of mortality was showed for the first instar larvae for the commercially isulate in the concentration of 5×10-1 was 59.4% Furthermore, low percentage of mortality was shown in the concentration of 5×10-1 in fifth instar larval which was 8.3% in the third days of treatment. The results also showed that the indigenous isolated was more effective than the commercially produced bacteria for killing larval instars of fig moth E.cautella .The total percentage of larval instar mortality reached to 44.5 % after the third days of treatment in concentration 5×10-1 in the indigenous isolate , and it was 33.8 % in the commercially produced bacteria .

Photoperiodic control of development in the pitcher-plant mosquito, Wyeomyia smithii

1972 ◽  
Vol 50 (6) ◽  
pp. 713-719 ◽  
Author(s):  
William E. Bradshaw ◽  
L. Philip Lounibos
Keyword(s):  
Larval Instar ◽  
Pitcher Plant ◽  
Photoperiodic Control ◽  
Wyeomyia Smithii ◽  
Diapause Termination ◽  
Environmental Consequences ◽  
The Third ◽  
Short Day ◽  
Critical Daylength ◽  
Short Days

Wyeomyia smithii diapause in the third larval instar. Long days avert or terminate and short days promote or maintain diapause. Diapause occurs early in the third instar and may be terminated by photoperiodic stimuli without the intervention of chilling or other factors. Fifty percent termination of diapause requires about 3 long days and another [Formula: see text] days are consumed in the third instar for postdiapause development. The critical daylength is identical for both the initiation and termination of diapause, 14.75 h of light per day. But, the photoperiodic clock monitoring diapause decisions is several times as accurate during initiation as in termination, reflecting the more drastic environmental consequences of development misdirection in the fall than in the spring. This accuracy is further enhanced by a prolongation of the second instar under short-day conditions. The doubling in the duration of the second instar exhibits the same critical daylength properties as diapause determination.The third instar is divisible into four distinct developmental periods: prediapause, diapause, termination of diapause, and postdiapause. Methods for quantifying these periods are presented. Similar manipulations could be employed for other diapausing arthropods, regardless of the stage at which dormancy occurs or the cues used in its regulation.

Development and differentiation in vitro of Drosophila imaginal disc cells from dissociated early embryos

Development ◽  
1975 ◽  
Vol 33 (2) ◽  
pp. 487-498
Author(s):  
Andreas Dübendorfer ◽  
Glen Shields ◽  
James H. Sang
Keyword(s):  
Imaginal Disc ◽  
Larval Instar ◽  
Cell Types ◽  
The Third ◽  
Early Embryos ◽  
Disc Cells ◽  
Development And Differentiation ◽  
Pattern Specification

Embryos of Drosophila melanogaster, 6–8 h after oviposition, were dissociated and the cells cultured in vitro. Besides larval cell types, imaginal disc cells, assembled and growing in bloated monolayered vesicles, were obtained. The cells of these vesicles become competent to differentiate adult structures when treated with α-ecdysone or ecdysterone in vitro. Recognizable patterns of the adult fly are not formed though. If metamorphosis of imaginal cell vesicles from in vitro-cultures is induced in vivo by transplantation into host larvae of various ages within the third larval instar, recognizable patterns can differentiate provided the host larva does not metamorphose prior to 2 days after transplantation. The frequency of specific patterns in the implants can be increased by providing 9 days of culture in vivo (adult host flies) before metamorphosis. Passage through the third larval instar is not essential for these cells to produce identifiable patterns since culture in adult flies alone can achieve this. The quality of the differentiated pattern is not correlated with the extent of cell proliferation in the cultured tissues. The problem of pattern specification in vitro and in vivo is discussed.

scholarly journals Functional Response of Chrysoperla carnea (Neuroptera: Chrysopidae) Larvae on Saissetia oleae (Olivier) (Hemiptera: Coccidae): Implications for Biological Control

Agronomy ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1511
Author(s):  
Abdelkader Meni Mahzoum ◽  
María Villa ◽  
Jacinto Benhadi-Marín ◽  
José Alberto Pereira
Keyword(s):  
Functional Response ◽  
Attack Rate ◽  
Larval Instar ◽  
Food Resource ◽  
Handling Time ◽  
Scale Insects ◽  
Chrysoperla Carnea ◽  
Larval Stages ◽  
The Third ◽  
Saissetia Oleae

Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae) is a voracious predator of soft-bodied insects such as juveniles of scale insects and the black scale Saissetia oleae (Olivier) (Hemiptera: Coccidae) is an important pest of several crops, such as the olive tree. However, the predatory efficiency of C. carnea on S. oleae has been unstudied yet. The present work aimed to study the functional response of larvae of C. carnea fed on S. oleae nymphs. In a controlled laboratory environment, increasing densities of S. oleae second and third nymph stages were offered to newly emerged specimens of the three larvae instars of C. carnea. After 24 h, the number of killed S. oleae was recorded and the functional response of C. carnea was assessed. The three larval stages of C. carnea displayed a type-II functional response, i.e., killed prey increased with higher S. oleae densities up to a maximum limited by the handling time. The attack rate did not significantly differ among the three instars while the maximum attack rate was significantly higher for the third instar. The handling time of the first larval instar of C. carnea was higher than that of the third instar. Our results demonstrated that S. oleae could act as a food resource for all larval stages of C. carnea. Furthermore, the third larval stage of the predator was the most efficient in reducing S. oleae densities. These results suggest that C. carnea larvae could contribute to S. oleae control in sustainable agriculture.

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