scholarly journals Fine structure of the silk spinning system in the caddisworm, Hydatophylax nigrovittatus (Trichoptera: Limnephilidae)

2020 ◽  
Author(s):  
Hyo-Jeong KIM ◽  
Yan SUN ◽  
Myung-Jin Moon
Keyword(s):  
Secretory Granules ◽  
Aquatic Insect ◽  
Cellular Level ◽  
Silk Fibers ◽  
Silk Production ◽  
Terrestrial Arthropods ◽  
Transport Vesicles ◽  
Caddis Flies ◽  
Silk Glands ◽  
Silk Spinning

Abstract Silk is produced by a variety of insects, but only silk made by terrestrial arthropods has been examined in detail. To fill the gap, this study was designed to understand the silk spinning system of aquatic insect. The larvae of caddis flies, Hydatophylax nigrovittatus produce silk through a pair of labial silk glands and use raw silk to protect themselves in the aquatic environment. The result of this study clearly shows that although silk fibers are made under aquatic conditions, the cellular silk production system is quite similar to that of terrestrial arthropods. Typically, silk production in caddisworm has been achieved by two independent processes in the silk glands. This includes the synthesis of silk fibroin in the posterior region, the production of adhesive glycoproteins in the anterior region, which are ultimately accumulated into functional silk dope and converted to a silk ribbon coated with gluey substances. At the cellular level, each substance of fibroin and glycoprotein is specifically synthesized at different locations, and then transported from the rough ER to the Golgi apparatus as transport vesicles, respectively. Thereafter, the secretory vesicles gradually increase in size by vesicular fusion, forming larger secretory granules containing specific proteins. It was found that these granules eventually migrate to the apical membrane and are exocytosed into the lumen by a mechanism of merocrine secretion.

scholarly journals Fine structure of the silk spinning system in the caddisworm, Hydatophylax nigrovittatus (Trichoptera: Limnephilidae)

2020 ◽  
Author(s):  
Hyo-Jeong Kim ◽  
Yan Sun ◽  
Myung-Jin Moon
Keyword(s):  
Secretory Granules ◽  
Aquatic Insect ◽  
Cellular Level ◽  
Silk Fibers ◽  
Silk Production ◽  
Terrestrial Arthropods ◽  
Transport Vesicles ◽  
Caddis Flies ◽  
Silk Glands ◽  
Silk Spinning

Abstract Silk is produced by a variety of insects, but only silk made by terrestrial arthropods has been examined in detail. To fill the gap, this study was designed to understand the silk spinning system of aquatic insect. The larvae of caddis flies, Hydatophylax nigrovittatus produce silk through a pair of labial silk glands and use raw silk to protect themselves in the aquatic environment. The result of this study clearly shows that although silk fibers are made under aquatic conditions, the cellular silk production system is quite similar to that of terrestrial arthropods. Typically, silk production in caddisworm has been achieved by two independent processes in the silk glands. This includes the synthesis of silk fibroin in the posterior region, the production of adhesive glycoproteins in the anterior region, which are ultimately accumulated into functional silk dope and converted to a silk ribbon coated with gluey substances. At the cellular level, each substance of fibroin and glycoprotein is specifically synthesized at different locations, and then transported from the rough ER to the Golgi apparatus as transport vesicles, respectively. Thereafter, the secretory vesicles gradually increase in size by vesicular fusion, forming larger secretory granules containing specific proteins. It was found that these granules eventually migrate to the apical membrane and are exocytosed into the lumen by a mechanism of merocrine secretion.

scholarly journals Shifts in morphology, gene expression, and selection underlie web loss in Hawaiian Tetragnatha spiders

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Cory A. Berger ◽  
Michael S. Brewer ◽  
Nobuaki Kono ◽  
Hiroyuki Nakamura ◽  
Kazuharu Arakawa ◽  
...  
Keyword(s):  
Genetic Basis ◽  
Adaptive Traits ◽  
Deep Time ◽  
Selective Pressures ◽  
Silk Production ◽  
Silk Glands ◽  
Genetic Mechanisms ◽  
Orb Web ◽  
Short Time ◽  
Web Building

Abstract Background A striking aspect of evolution is that it often converges on similar trajectories. Evolutionary convergence can occur in deep time or over short time scales, and is associated with the imposition of similar selective pressures. Repeated convergent events provide a framework to infer the genetic basis of adaptive traits. The current study examines the genetic basis of secondary web loss within web-building spiders (Araneoidea). Specifically, we use a lineage of spiders in the genus Tetragnatha (Tetragnathidae) that has diverged into two clades associated with the relatively recent (5 mya) colonization of, and subsequent adaptive radiation within, the Hawaiian Islands. One clade has adopted a cursorial lifestyle, and the other has retained the ancestral behavior of capturing prey with sticky orb webs. We explore how these behavioral phenotypes are reflected in the morphology of the spinning apparatus and internal silk glands, and the expression of silk genes. Several sister families to the Tetragnathidae have undergone similar web loss, so we also ask whether convergent patterns of selection can be detected in these lineages. Results The cursorial clade has lost spigots associated with the sticky spiral of the orb web. This appears to have been accompanied by loss of silk glands themselves. We generated phylogenies of silk proteins (spidroins), which showed that the transcriptomes of cursorial Tetragnatha contain all major spidroins except for flagelliform. We also found an uncharacterized spidroin that has higher expression in cursorial species. We found evidence for convergent selection acting on this spidroin, as well as genes involved in protein metabolism, in the cursorial Tetragnatha and divergent cursorial lineages in the families Malkaridae and Mimetidae. Conclusions Our results provide strong evidence that independent web loss events and the associated adoption of a cursorial lifestyle are based on similar genetic mechanisms. Many genes we identified as having evolved convergently are associated with protein synthesis, degradation, and processing, which are processes that play important roles in silk production. This study demonstrates, in the case of independent evolution of web loss, that similar selective pressures act on many of the same genes to produce the same phenotypes and behaviors.

scholarly journals Exon Splice Enhancer Mutation (GH-E32A) Causes Autosomal Dominant Growth Hormone Deficiency

2007 ◽  
Vol 92 (11) ◽  
pp. 4427-4435 ◽  
Author(s):  
Vibor Petkovic ◽  
Didier Lochmatter ◽  
James Turton ◽  
Peter E. Clayton ◽  
Peter J. Trainer ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Autosomal Dominant ◽  
Secretory Granules ◽  
Cellular Level ◽  
Hormone Deficiency ◽  
Mutant Form ◽  
Splice Enhancer ◽  
Exon Splice ◽  
Microscopy Analysis ◽  
Derived Data

Abstract Context and Objective: Alteration of exon splice enhancers (ESE) may cause autosomal dominant GH deficiency (IGHD II). Disruption analysis of a (GAA) (n) ESE motif within exon 3 by introducing single-base mutations has shown that single nucleotide mutations within ESE1 affect pre-mRNA splicing. Design, Setting, and Patients: Confirming the laboratory-derived data, a heterozygous splice enhancer mutation in exon 3 (exon 3 + 2 A→C) coding for GH-E32A mutation of the GH-1 gene was found in two independent pedigrees, causing familial IGHD II. Because different ESE mutations have a variable impact on splicing of exon 3 of GH and therefore on the expression of the 17.5-kDa GH mutant form, the GH-E32A was studied at the cellular level. Interventions and Results: The splicing of GH-E32A, assessed at the protein level, produced significantly increased amounts of 17.5-kDa GH isoform (55% of total GH protein) when compared with the wt-GH. AtT-20 cells coexpressing both wt-GH and GH-E32A presented a significant reduction in cell proliferation as well as GH production after forskolin stimulation when compared with the cells expressing wt-GH. These results were complemented with confocal microscopy analysis, which revealed a significant reduction of the GH-E32A-derived isoform colocalized with secretory granules, compared with wt-GH. Conclusion: GH-E32A mutation found within ESE1 weakens recognition of exon 3 directly, and therefore, an increased production of the exon 3-skipped 17.5-kDa GH isoform in relation to the 22-kDa, wt-GH isoform was found. The GH-E32A mutant altered stimulated GH production as well as cell proliferation, causing IGHD II.

Suppression of Synaptotagmin II restrains phorbolester-induced downregulation of protein kinase Cα by diverting the kinase from a degradative pathway to the recycling endocytic compartment

2002 ◽  
Vol 115 (15) ◽  
pp. 3083-3092 ◽  
Author(s):  
Ze Peng ◽  
Elena Grimberg ◽  
Ronit Sagi-Eisenberg
Keyword(s):  
Plasma Membrane ◽  
Protein Kinase ◽  
Phorbol Esters ◽  
Secretory Granules ◽  
Critical Factor ◽  
Cellular Level ◽  
Endocytic Compartment ◽  
Early Endosomes ◽  
Protein Kinase Cα ◽  
Rbl Cells

Downregulation of protein kinase Cα (PKCα) following long-term exposure to phorbol esters such as TPA is traffic dependent and involves delivery of the active, membrane-associated PKCα to endosomes. In this study, we show that synaptotagmin II (Syt II), a member of the Syt family of proteins, is required for TPA-induced degradation of PKCα. Thus, whereas the kinase half-life in TPA-treated cultured mast cells (the mast cell line rat basophilic leukemia RBL-2H3) is 2 hours, it is doubled in RBL-Syt II- cells, in which the cellular level of Syt II is reduced by>95% by transfection with Syt II antisense cDNA. We demonstrate that in TPA-treated RBL cells, PKCα travels from the cytosol to the plasma membrane, where it is delivered to early endosomes on its route to degradation. By contrast, in TPA-treated RBL-Syt II- cells,PKCα is diverted to recycling endosomes and remains distributed between the plasma membrane and the perinuclear recycling endocytic compartment. Notably, in both RBL and RBL-Syt II- cells, a fraction of PKCα is delivered and maintained in the secretory granules (SG). These results implicate Syt II as a critical factor for the delivery of internalized cargo for degradation. As shown here, one consequence of Syt II suppression is a delay in PKCα downregulation, resulting in its prolonged signaling.

Regulation of renin processing and secretion: chemiosmotic control and novel secretory pathway

1993 ◽  
Vol 265 (2) ◽  
pp. C305-C320 ◽  
Author(s):  
J. A. King ◽  
D. J. Lush ◽  
J. C. Fray
Keyword(s):  
Secretory Pathway ◽  
Secretory Granules ◽  
Surface Membrane ◽  
Water Flux ◽  
Cellular Level ◽  
Macula Densa ◽  
Secretory Proteins ◽  
Juxtaglomerular Cells ◽  
Cl Channels ◽  
Health And Disease

The renin-angiotensin-aldosterone system (RAAS) plays an important role in cardiovascular and electrolyte regulation in health and disease. Juxtaglomerular cells in the kidney regulate endocrine RAAS by physiologically controlling conversion of prorenin and secretion of renin. The classical baroceptor, neurogenic, and macula densa mechanisms regulate renin expression at the cellular level by Ca2+, adenosine 3',5'-cyclic monophosphate (cAMP), and chemiosmotic forces (K+, Cl-, and water flux coupled to H+ movement). The baroceptor mechanism (through Ca2+) activates K+ and Cl- channels in the surface membrane and deactivates a KCl-H+ exchange chemiosmotic transporter in the secretory granular membrane. The neurogenic mechanism (through cAMP) promotes prorenin processing to renin. The macula densa mechanism (through K+ and Cl-) involves the processing of prorenin to renin. Ca2+, by inhibiting the KCl-H+ exchange transporter, prevents secretory granules from engaging in chemiosmotically mediated exocytosis. cAMP, on the other hand, by stimulating H+ influx, provides the acidic granular environment for prorenin processing to renin. It is concluded that, in the presence of a favorable chemiosmotic environment, prorenin is processed to renin, which may then be secreted by regulative degranulation or divergence translocation, a novel secretory pathway used by several secretory proteins, including renin.

AQUATIC INSECTS OF PEATLANDS AND MARSHES IN CANADA: INTRODUCTION

1987 ◽  
Vol 119 (S140) ◽  
pp. 1-4 ◽  
Author(s):  
David M. Rosenberg ◽  
H.V. Danks
Keyword(s):  
Aquatic Insects ◽  
Current Knowledge ◽  
Aquatic Insect ◽  
Freshwater Wetlands ◽  
Background Information ◽  
Insect Fauna ◽  
Structure And Dynamics ◽  
Biological Survey ◽  
Terrestrial Arthropods ◽  
Wetland Habitats

AbstractIn general, the aquatic insects of freshwater wetlands have been inadequately studied despite their apparent importance in wetland habitats, especially in energy and nutrient transfer. The Biological Survey of Canada (Terrestrial Arthropods) recognized the deficiencies in knowledge of taxonomy and ecology of insect species in wetland habitats and sponsored a "Conference on the aquatic insects of peatlands and marshes" in St. Andrews, New Brunswick, on 3 October, 1984. The Conference summarized current knowledge on the systematics and ecology of aquatic insects of Canadian peatlands and marshes, the wetland habitats chosen for emphasis, and sought to identify needs for research on the structure and dynamics of aquatic insect faunas in these habitats. The proceedings of the Conference are published here. The first two papers provide background information on the habitats under consideration and the interactions among invertebrates and vertebrates in these habitats. A second group of papers considers features of the Hydracarina, Ephemeroptera, Odonata, Hemiptera, Trichoptera, Coleoptera, and Diptera in peatlands and marshes. A final paper summarizes data on the occurrence of aquatic insects in bogs, fens, and marshes, addresses broader questions related to the nature of the insect fauna, and identifies needs for further research. By making accessible systematic and ecological information on aquatic insects of Canadian peatlands and marshes, the proceedings should support and encourage further work in these habitats.

A Multiscale Characterization of Two Tropical Embiopteran Species: Nano- and Microscale Features of Silk, Silk-Spinning Behavior, and Environmental Correlates of their Distributions

2020 ◽  
Vol 49 (5) ◽  
pp. 1242-1251
Author(s):  
Samantha Shenoy ◽  
Keilyn Ing ◽  
Richard P Barber ◽  
Edward C Rooks ◽  
Janice S Edgerly
Keyword(s):  
The Other ◽  
Tropical Island ◽  
Silk Fibers ◽  
Body Form ◽  
Environmental Correlates ◽  
Unique Ability ◽  
Silk Spinning

Abstract Embioptera display the unique ability to spin silk with their front feet to create protective domiciles. Their body form is remarkably uniform throughout the order, perhaps because they all live within the tight confines of silken tubes. This study contributes to an understanding of the ecology of Embioptera, an order that is rarely studied in the field. We conducted a census to quantify the habitats of two species with overlapping distributions on the tropical island of Trinidad in a search for characteristics that might explain their distinct ecologies. One species, Antipaluria urichi (Saussure) (Embioptera: Clothodidae), lives in larger colonies with more expansive silk in habitats throughout the island, especially in the rainforest of the Northern Range Mountains. The other, Pararhagadochir trinitatis (Saussure) (Embioptera: Scelembiidae), was found only in lowland locations. We quantified silk-spinning behavior and productivity of the two species and found that A. urichi spins thicker silk sheets per individual and emphasizes spin-steps that function to create a domicile that is more expansive than that produced by P. trinitatis. Their silks also interact differently when exposed to water: the smaller-diameter silk fibers of P. trinitatis form more continuous films on the surface of the domicile after being wetted and dried than that seen in A. urichi silk. This tendency gives P. trinitatis silk a shiny appearance in the field compared to the more cloth-like silk of A. urichi. How these silks function in the field and if the differences are partially responsible for the distinct distributions of the two species remain to be determined.

INTRODUCTION

1987 ◽  
Vol 119 (140) ◽  
pp. 1-4
Author(s):  
David M. Rosenberg ◽  
H.V. Danks
Keyword(s):  
Aquatic Insects ◽  
Current Knowledge ◽  
Aquatic Insect ◽  
Freshwater Wetlands ◽  
Background Information ◽  
Insect Fauna ◽  
Structure And Dynamics ◽  
Biological Survey ◽  
Terrestrial Arthropods ◽  
Wetland Habitats

In general, the aquatic insects of freshwater wetlands have been inadequately studied despite their apparent importance in wetland habitats, especially in energy and nutrient transfer. The Biological Survey of Canada (Terrestrial Arthropods) recognized the deficiencies in knowledge of taxonomy and ecology of insect species in wetland habitats and sponsored a "Conference on the aquatic insects of peatlands and marshes" in St. Andrews, New Brunswick, on 3 October, 1984. The Conference summarized current knowledge on the systematics and ecology of aquatic insects of Canadian peatlands and marshes, the wetland habitats chosen for emphasis, and sought to identify needs for research on the structure and dynamics of aquatic insect faunas in these habitats. The proceedings of the Conference are published here. The first two papers provide background information on the habitats under consideration and the interactions among invertebrates and vertebrates in these habitats. A second group of papers considers features of the Hydracarina, Ephemeroptera, Odonata, Hemiptera, Trichoptera, Coleoptera, and Diptera in peatlands and marshes. A final paper summarizes data on the occurrence of aquatic insects in bogs, fens, and marshes, addresses broader questions related to the nature of the insect fauna, and identifies needs for further research. By making accessible systematic and ecological information on aquatic insects of Canadian peatlands and marshes, the proceedings should support and encourage further work in these habitats.

The Behaviour in vitro of Dissociated Embryonic Pituitary Tissue

Development ◽  
1958 ◽  
Vol 6 (3) ◽  
pp. 518-526
Author(s):  
H. Sobel
Keyword(s):  
Secretory Granules ◽  
Anterior Lobe ◽  
Cellular Level ◽  
Chick Embryos ◽  
Histological Differentiation ◽  
Limb Buds ◽  
Discrete State ◽  
Viable Cells ◽  
Cultivation In Vitro

It was previously reported (A. Moscona & H. Moscona, 1952) that the tissues of limb-buds and mesonephroi of early chick embryos can be dissociated into suspensions of discrete viable cells which, under certain conditions of cultivation in vitro, reaggregate into clusters and re-establish a tissue-like association. Upon further cultivation in vitro these primary cellular associations became transformed into organized tissue patterns, the development of which proceeds to the level of typical histological differentiation. Owing to the nature of the experimental material studied so far, it has mainly been the capacity of the aggregates for re-establishing typical intercellular relationship that has come prominently into view. The present observations were aimed at examining the capacity of cells, aggregated from a discrete state, to resume and complete differentiation on the cellular level, e.g. to achieve a cytologically characteristic secretory status. The normally developed cells of the anterior lobe of the pituitary carry a distinct mark of their state of differentiation—the secretory granules.

scholarly journals Reconstitution of constitutive secretion using semi-intact cells: regulation by GTP but not calcium.

1991 ◽  
Vol 112 (1) ◽  
pp. 39-54 ◽  
Author(s):  
S G Miller ◽  
H P Moore
Keyword(s):  
Plasma Membrane ◽  
Cell Surface ◽  
G Protein ◽  
Secretory Granules ◽  
Intact Cells ◽  
Transport Reaction ◽  
Permeabilized Cells ◽  
Transmembrane Glycoprotein ◽  
Transport Vesicles ◽  
Constitutive Secretion

Regulated exocytosis in many permeabilized cells can be triggered by calcium and nonhydrolyzable GTP analogues. Here we examine the role of these effectors in exocytosis of constitutive vesicles using a system that reconstitutes transport between the trans-Golgi region and the plasma membrane. Transport is assayed by two independent methods: the movement of a transmembrane glycoprotein (vesicular stomatitis virus glycoprotein [VSV G protein]) to the cell surface; and the release of a soluble marker, sulfated glycosaminoglycan (GAG) chains, that have been synthesized and radiolabeled in the trans-Golgi. The plasma membrane of CHO cells was selectively perforated with the bacterial cytolysin streptolysin-O. These perforated cells allow exchange of ions and cytosolic proteins but retain intracellular organelles and transport vesicles. Incubation of the semi-intact cells with ATP and a cytosolic fraction results in transport of VSV G protein and GAG chains to the cell surface. The transport reaction is temperature dependent, requires hydrolyzable ATP, and is inhibited by N-ethylmaleimide. Nonhydrolyzable GTP analogs such as GTP gamma S, which stimulate the fusion of regulated secretory granules, completely abolish constitutive secretion. The rate and extent of constitutive transport between the trans-Golgi and the plasma membrane is independent of free Ca2+ concentrations. This is in marked contrast to fusion of regulated secretory granules with the plasma membrane, and transport between the ER and the cis-Golgi (Beckers, C. J. M., and W. E. Balch. 1989. J. Cell Biol. 108:1245-1256; Baker, D., L. Wuestehube, R. Schekman, and D. Botstein. 1990. Proc. Natl. Acad. Sci. USA. 87:355-359).

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