Fine structure of Drosophila larval salivary gland ducts as revealed by laser confocal microscopy and SEM

The functions of the larval salivary glands (SGs) of Drosophila are traditionally associated with the production of a massive secretion during puparium formation; it is exocytosed into a centrally located lumen and subsequently expectorated via ducts, the pharynx and mouth. This so-called proteinace...

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Autores principales:	Denisa BEŇOVÁ-LISZEKOVÁ, Milan BEŇO, Robert FARKAŠ
Formato:	article
Lenguaje:	EN
Publicado:	Institute of Entomology, Biology Centre, Czech Academy of Science 2021
Materias:	diptera drosophilidae drosophila larval salivary glands secretory glue salivary duct taenidia ultrastructure Zoology QL1-991
Acceso en línea:	https://doaj.org/article/caf9b19bde3144298b7e71a5f7f1a136
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spelling	oai:doaj.org-article:caf9b19bde3144298b7e71a5f7f1a1362021-11-05T15:23:15ZFine structure of Drosophila larval salivary gland ducts as revealed by laser confocal microscopy and SEM1210-57591802-882910.14411/eje.2021.013https://doaj.org/article/caf9b19bde3144298b7e71a5f7f1a1362021-04-01T00:00:00Zhttps://www.eje.cz/artkey/eje-202101-0013_fine_structure_of_drosophila_larval_salivary_gland_ducts_as_revealed_by_laser_confocal_microscopy_and_sem.phphttps://doaj.org/toc/1210-5759https://doaj.org/toc/1802-8829The functions of the larval salivary glands (SGs) of Drosophila are traditionally associated with the production of a massive secretion during puparium formation; it is exocytosed into a centrally located lumen and subsequently expectorated via ducts, the pharynx and mouth. This so-called proteinaceous glue serves as an adhesive to attach the puparial case to a solid substrate. Great attention has been paid to the secretory cells of SGs, which are famous for their giant polytene chromosomes. However, substantially less attention has been devoted to individual or common ducts that form the most proximal portion of the SG organ via which the glue is released into the pharynx. In the present paper, we describe the organization and fine structure of the taenidia, highly specialized circumferential ring-like extracellular (cuticular) components on the internal side of these tubes. Two chitin-specific probes that have previously been used to recognize taenidia in Drosophila tracheae, Calcofluor White M2R (also known as Fluorescent Brightener 28) and the novel vital fluorescent dye SiR-COOH, show positively stained ductal taenidia in late larval SGs. As seen using scanning electron microscopy (SEM), the interior of the ductal tube contains regular and densely-arranged ridge-like circumferential rings which represent local thickenings of the cuticle in various geometries. The microtubular arrays that optically colocalize with taenidia in both the trachea and SG ducts are specifically and strongly recognized by fluorescently-conjugated colchicine as well as anti-tubulin antibody. In contrast to taenidia in the tracheae, the analogous structures in SG ducts cannot be detected by fluorescently-labeled phalloidin or even actin-GFP fusion protein, suggesting that the ducts lack a cortical network made of filamentous actin. We speculate that these taenidia may serve to reinforce the duct during the secretory processes that SGs undergo during late larval and late prepupal stages.Denisa BEŇOVÁ-LISZEKOVÁMilan BEŇORobert FARKAŠInstitute of Entomology, Biology Centre, Czech Academy of Sciencearticledipteradrosophilidaedrosophilalarval salivary glandssecretory gluesalivary ducttaenidiaultrastructureZoologyQL1-991ENEuropean Journal of Entomology, Vol 118, Iss 1, Pp 123-134 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	diptera drosophilidae drosophila larval salivary glands secretory glue salivary duct taenidia ultrastructure Zoology QL1-991
spellingShingle	diptera drosophilidae drosophila larval salivary glands secretory glue salivary duct taenidia ultrastructure Zoology QL1-991 Denisa BEŇOVÁ-LISZEKOVÁ Milan BEŇO Robert FARKAŠ Fine structure of Drosophila larval salivary gland ducts as revealed by laser confocal microscopy and SEM
description	The functions of the larval salivary glands (SGs) of Drosophila are traditionally associated with the production of a massive secretion during puparium formation; it is exocytosed into a centrally located lumen and subsequently expectorated via ducts, the pharynx and mouth. This so-called proteinaceous glue serves as an adhesive to attach the puparial case to a solid substrate. Great attention has been paid to the secretory cells of SGs, which are famous for their giant polytene chromosomes. However, substantially less attention has been devoted to individual or common ducts that form the most proximal portion of the SG organ via which the glue is released into the pharynx. In the present paper, we describe the organization and fine structure of the taenidia, highly specialized circumferential ring-like extracellular (cuticular) components on the internal side of these tubes. Two chitin-specific probes that have previously been used to recognize taenidia in Drosophila tracheae, Calcofluor White M2R (also known as Fluorescent Brightener 28) and the novel vital fluorescent dye SiR-COOH, show positively stained ductal taenidia in late larval SGs. As seen using scanning electron microscopy (SEM), the interior of the ductal tube contains regular and densely-arranged ridge-like circumferential rings which represent local thickenings of the cuticle in various geometries. The microtubular arrays that optically colocalize with taenidia in both the trachea and SG ducts are specifically and strongly recognized by fluorescently-conjugated colchicine as well as anti-tubulin antibody. In contrast to taenidia in the tracheae, the analogous structures in SG ducts cannot be detected by fluorescently-labeled phalloidin or even actin-GFP fusion protein, suggesting that the ducts lack a cortical network made of filamentous actin. We speculate that these taenidia may serve to reinforce the duct during the secretory processes that SGs undergo during late larval and late prepupal stages.
format	article
author	Denisa BEŇOVÁ-LISZEKOVÁ Milan BEŇO Robert FARKAŠ
author_facet	Denisa BEŇOVÁ-LISZEKOVÁ Milan BEŇO Robert FARKAŠ
author_sort	Denisa BEŇOVÁ-LISZEKOVÁ
title	Fine structure of Drosophila larval salivary gland ducts as revealed by laser confocal microscopy and SEM
title_short	Fine structure of Drosophila larval salivary gland ducts as revealed by laser confocal microscopy and SEM
title_full	Fine structure of Drosophila larval salivary gland ducts as revealed by laser confocal microscopy and SEM
title_fullStr	Fine structure of Drosophila larval salivary gland ducts as revealed by laser confocal microscopy and SEM
title_full_unstemmed	Fine structure of Drosophila larval salivary gland ducts as revealed by laser confocal microscopy and SEM
title_sort	fine structure of drosophila larval salivary gland ducts as revealed by laser confocal microscopy and sem
publisher	Institute of Entomology, Biology Centre, Czech Academy of Science
publishDate	2021
url	https://doaj.org/article/caf9b19bde3144298b7e71a5f7f1a136
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Fine structure of Drosophila larval salivary gland ducts as revealed by laser confocal microscopy and SEM

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