Drosophila EcR-B ecdysone receptor isoforms are required for larval molting and for neuron remodeling during metamorphosis

Development ◽  
1998 ◽  
Vol 125 (11) ◽  
pp. 2053-2062 ◽  
Author(s):  
M. Schubiger ◽  
A.A. Wade ◽  
G.E. Carney ◽  
J.W. Truman ◽  
M. Bender

During the metamorphic reorganization of the insect central nervous system, the steroid hormone 20-hydroxyecdysone induces a wide spectrum of cellular responses including neuronal proliferation, maturation, cell death and the remodeling of larval neurons into their adult forms. In Drosophila, expression of specific ecdysone receptor (EcR) isoforms has been correlated with particular responses, suggesting that different EcR isoforms may govern distinct steroid-induced responses in these cells. We have used imprecise excision of a P element to create EcR deletion mutants that remove the EcR-B promoter and therefore should lack EcR-B1 and EcR-B2 expression but retain EcR-A expression. Most of these EcR-B mutant animals show defects in larval molting, arresting at the boundaries between the three larval stages, while a smaller percentage of EcR-B mutants survive into the early stages of metamorphosis. Remodeling of larval neurons at metamorphosis begins with the pruning back of larval-specific dendrites and occurs as these cells are expressing high levels of EcR-B1 and little EcR-A. This pruning response is blocked in the EcR-B mutants despite the fact that adult-specific neurons, which normally express only EcR-A, can progress in their development. These observations support the hypothesis that different EcR isoforms control cell-type-specific responses during remodeling of the nervous system at metamorphosis.

Genetics ◽  
1990 ◽  
Vol 126 (4) ◽  
pp. 1033-1044 ◽  
Author(s):  
T Watanabe ◽  
D R Kankel

Abstract Previous genetic studies have shown that wild-type function of the l(1)ogre (lethal (1) optic ganglion reduced) locus is essential for the generation and/or maintenance of the postembryonic neuroblasts including those from which the optic lobe is descended. In the present study molecular isolation and characterization of the l(1)ogre locus was carried out to study the structure and expression of this gene in order to gain information about the nature of l(1)ogre function and its relevance to the development of the central nervous system. About 70 kilobases (kb) of genomic DNA were isolated that spanned the region where l(1)ogre was known to reside. Southern analysis of a l(1)ogre mutation and subsequent P element-mediated DNA transformation mapped the l(1)ogre+ function within a genomic fragment of 12.5 kb. Northern analyses showed that a 2.9-kb message transcribed from this 12.5-kb region represented l(1)ogre. A 2.15-kb portion of a corresponding cDNA clone was sequenced. An open reading frame (ORF) of 1,086 base paris was found, and a protein sequence of 362 amino acids with one highly hydrophobic segment was deduced from conceptual translation of this ORF.


Genetics ◽  
2000 ◽  
Vol 155 (2) ◽  
pp. 733-752 ◽  
Author(s):  
Salim Abdelilah-Seyfried ◽  
Yee-Ming Chan ◽  
Chaoyang Zeng ◽  
Nicholas J Justice ◽  
Susan Younger-Shepherd ◽  
...  

Abstract The Drosophila adult external sensory organ, comprising a neuron and its support cells, is derived from a single precursor cell via several asymmetric cell divisions. To identify molecules involved in sensory organ development, we conducted a tissue-specific gain-of-function screen. We screened 2293 independent P-element lines established by P. Rørth and identified 105 lines, carrying insertions at 78 distinct loci, that produced misexpression phenotypes with changes in number, fate, or morphology of cells of the adult external sensory organ. On the basis of the gain-of-function phenotypes of both internal and external support cells, we subdivided the candidate lines into three classes. The first class (52 lines, 40 loci) exhibits partial or complete loss of adult external sensory organs. The second class (38 lines, 28 loci) is associated with increased numbers of entire adult external sensory organs or subsets of sensory organ cells. The third class (15 lines, 10 loci) results in potential cell fate transformations. Genetic and molecular characterization of these candidate lines reveals that some loci identified in this screen correspond to genes known to function in the formation of the peripheral nervous system, such as big brain, extra macrochaetae, and numb. Also emerging from the screen are a large group of previously uncharacterized genes and several known genes that have not yet been implicated in the development of the peripheral nervous system.


Author(s):  
N. J. Berrill

Ciona intestinalis (L.) is probably the most cosmopolitan species of ascidians and has long been of general interest. The adult morphology has been well described in monographic form by Roule (1884), the physiology of the heart and circulation by Heine (1902), Enriques (1904) and Wolf (1932), of the nervous system by Magnus (1902), Hecht (1918, 1926), Cate (1928), Haffner (1933), and Bacq & Florkin (1935), and of the digestive system by Yonge (1925). Developmental studies include that of the early embryology by Conklin (1905), problems of fertilization by Morgan (1945) and Damas (1899,1900). In no work, however, has there been a presentation of the entire Ciona organism from the tadpole stage through the critical post-larval stages to the young cionid ascidian. The present account portrays this period of development, together with a discussion of some significant but relatively obscure aspects of adult structure.Eggs and theRearing ofCiona intestinalisWhile ascidians in general are difficult to rear to maturity under laboratory conditions, Ciona is relatively easy, and together with Botryllus schlosseri (Pallas) and Diplosoma gelatinosum (M.-Edw.) is liable to appear more or less spontaneously in large aquaria into which tadpoles may have been brought. Artificial fertilization is readily accomplished, and at almost any time of the year, since Ciona is sexually mature above a certain size and reproduction is seasonal only to the extent of the rhythm of the growth cycle. Normally eggs are set free spontaneously at dawn, although individuals kept in the laboratory may accumulate eggs and the oviduct become swollen.


1990 ◽  
Vol 38 (2) ◽  
pp. 171-178 ◽  
Author(s):  
D B Zimmer ◽  
M A Magnuson

We used immunohistochemical techniques to analyze the cell distribution of phosphoenolpyruvate carboxykinase (PEPCK) in adult and developing mouse tissues. PEPCK immunoreactivity was detected in many tissues, including some that had not been previously reported to contain PEPCK enzyme activity (bladder, stomach, ovary, vagina, parotid gland, submaxillary gland, and eye). In some multicellular tissues, PEPCK immunoreactivity was observed in multiple cell types. Several tissues (spleen, thyroid, and submaxillary gland) contained no detectable PEPCK immunoreactivity. During development, PEPCK immunoreactivity was associated with the developing nervous system and somites in 15-day embryos. At prenatal day 18, PEPCK immunoreactivity was detected only in the nervous system. At prenatal day 20, PEPCK immunoreactivity was observed in many of the tissues that contain PEPCK in the adult, with the exception of liver, lung, and stomach. PEPCK immunoreactivity was detected in liver at postnatal day 1, lung at postnatal day 7, and stomach after postnatal day 21. The only tissue in which PEPCK immunoreactivity decreased during development was the pancreas, where PEPCK immunoreactivity was detected at prenatal day 20 and was present until postnatal day 21. These results suggest that PEPCK expression is cell-type specific, more widespread than previously thought, and differentially expressed during development.


Parasitology ◽  
1995 ◽  
Vol 110 (2) ◽  
pp. 143-153 ◽  
Author(s):  
D. J. A. Brownlee ◽  
I. Fairweather ◽  
C. F. Johnston ◽  
M. C. Thorndyke ◽  
P. J. Skuce

SUMMARYThe localization and distribution of SALMFamide immunoreactivity (IR), SI(GFNSALMFamide), in the nervous system of both the adult and larval stages of the trematode Schistosoma mansoni has been determined by an indirect immunofluorescent technique in conjunction with confocal scanning laser microscopy (CSLM). Immunostaining was widespread in the nervous system of adult male and female S. mansoni. In the central nervous system (CNS), IR was evident in nerve cells and fibres in the anterior ganglia, cerebral commissure and dorsal and ventral nerve cords. In the peripheral nervous system (PNS), IR was apparent in nerve plexuses associated with the subtegmental musculature, oral and ventral suckers, the lining of the gynaecophoric canal, and in fine nerve fibres innervating the dorsal tubercles of the male worm. In the reproductive system of male and female worms, Sl-IR was only observed around the ootype/Mehlis' gland complex in the female. Immunostaining was also evident in the nervous system of both miracidium and cercarial larval stages. A post-embedding, IgG-conjugated colloidal gold immunostaining technique was employed to examine the subcellular distribution of SALMFamide-IR in the CNS of S. mansoni. Gold labelling of peptide was localized over dense-cored vesicles within nerve cell bodies and fibres constituting the neuropile of the anterior ganglia, cerebral commissure and nerve cords of the CNS. Antigen pre-absorption studies indicated that the results obtained do suggest S1-like immunostaining and not cross-reactivity with other peptides, in particular FMRFamide.


1971 ◽  
Vol 61 (2) ◽  
pp. 309-313 ◽  
Author(s):  
Ian McLure

Fifth-instar nymphs of Rhodnius prolixus Stålwere exposed to the vapours of 11 volatile drugs: acetone, bromobenzene, bromoform, carbon tetrachloride, chloral hydrate, chloroform, dioxane, ethanol, ethyl ether, isopropanol and paraldehyde. Bromobenzene, bromoform, carbon tetrachloride, chloroform and ether induced reversible anaesthesia. For each of these five, the insects exhibited a different andspecific pattern of motor responses before becoming totally immobile; these responses are described. The responses to carbon tetrachloride are similar to the normal feeding responses of this insect. The other six drugs did not induce anaesthesia, but instead, a commonand stereotyped pattern of cleaning responses, suggesting irritation of the sensory organs. It is proposed that the agent-specific responses to the anaesthesiainducing drugs are due to their differential action upon specific portions of the insect central nervous system.


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