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Molting cycle

About: Molting cycle is a research topic. Over the lifetime, 406 publications have been published within this topic receiving 9846 citations.


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01 Oct 2001
TL;DR: Adaptive traits of decapod larvae are the principal subject of this volume, and early ontogenetic adaptations to extreme or unpredictable ecological conditions are important in the evolutionary transitions from marine to limnic or terrestrial environments.
Abstract: About 90% of the extant species of the Decapoda live in oceans and adjacent coastal and estuarine regions, and most of them pass through a complex life history comprising a benthic (juvenile-adult) and a planktonic (larval) phase. The larvae show a wide array of adaptations to the pelagic environment, including modifications in functio-nal morphology, anatomy, the molting cycle, nutrition, growth, chemical composi-tion, meta-bo-lism, energy partitioning, ecology, and behavior. Due to these adaptive traits, which are the principal subject of this volume, decapod larvae are more like unrelat-ed holoplanktonic organisms rather than resembling the conspecific benthic juveniles and adults. Emphasis is here on the lesser known anatomical, bioenergetic, and ecophysiologi-cal aspects of larval life, because morphology has already extensively been documented in the literature. Changes in biological parameters (e.g. rates of feeding, growth, metabolism) are shown in successive developmental stages, within individual stages, and as repsonses to environmental factors. Particular attention is paid to interrelationships between intrinsic phenomena (molting cycle, organogenesis, growth) and the overlaying effects of extrinsic factors (e.g. food, temperature, salinity, pollution). Concluding from the available data, we may identify major bias and gaps in our present knowledge of larval biology. For instance, biochemical, physiological, and anatomical aspects have been investigated much less than larval morphology, ecology, and behavior, and bioenergetic parameters have large-ly been studied as isolated physio-lo-gi-cal traits rather than attempting to quantify the overall partition-ing of chemical energy. Little is known also about intraspecific variability within or between separate populations. This remains a major challenge for larval biologist, because knowledge of phenotypic plasticity and genetical divergence, e.g. in larval morphology or stress tolerance, is of utmost importance for the understanding of evolutionary adaptation and speciation. In particular, early ontogenetic adaptations to extreme or unpredictable ecological conditions are important in the evolutionary transitions from marine to limnic or terrestrial environments. We also need more compari-sons between field and laboratory observations in order to "calibrate" data from the field with those obtained under controlled conditions; inversely, those comparisons should help to identify "domestication effects" and other artifacts that are potentially pertinent to laboratory data. Furthermore, future research should increasingly consider effects which persist through successive life-history phases, e.g. those of embryonic acclimatization on larval stress tolerance, or the significance of larval condition for later settlement and recruit-ment success.

484 citations

Journal ArticleDOI
07 Apr 1989-Cell
TL;DR: In this paper, the authors examine how four genes interact to control a particular stage-specific event of the lateral hypodermal cell lineages, termed the larva-to-adult switch.

362 citations

Journal ArticleDOI
TL;DR: It is shown that inactivation of particular genes abrogates expression of the green fluorescent protein reporter genes, revealing regulatory networks that might couple the expression of genes essential for molting to endocrine cues.
Abstract: Although the molting cycle is a hallmark of insects and nematodes, neither the endocrine control of molting via size, stage, and nutritional inputs nor the enzymatic mechanism for synthesis and release of the exoskeleton is well understood. Here, we identify endocrine and enzymatic regulators of molting in C. elegans through a genome-wide RNA-interference screen. Products of the 159 genes discovered include annotated transcription factors, secreted peptides, transmembrane proteins, and extracellular matrix enzymes essential for molting. Fusions between several genes and green fluorescent protein show a pulse of expression before each molt in epithelial cells that synthesize the exoskeleton, indicating that the corresponding proteins are made in the correct time and place to regulate molting. We show further that inactivation of particular genes abrogates expression of the green fluorescent protein reporter genes, revealing regulatory networks that might couple the expression of genes essential for molting to endocrine cues. Many molting genes are conserved in parasitic nematodes responsible for human disease, and thus represent attractive targets for pesticide and pharmaceutical development.

292 citations

Journal ArticleDOI
TL;DR: The integumental tissues from the branchial region of an intermolt spiny lobster (late Stage C) are bordered by an outer and an inner integument, which is composed of columnar epidermal cells and a sub-epidermal connective tissue of a loose spongy type.
Abstract: 1. The integumental tissues from the branchial region of an intermolt spiny lobster (late Stage C) are bordered by an outer and an inner integument. The outer integument consists of four layers: a thin epicuticle, the pigmented layer, the principal layer, and the membranous layer. Both the epicuticle and pigmented layer are formed before molt. The inner integument, about 1/20 the thickness of the outer integument, is composed of two layers, a very thin epicuticle and a uniformly staining endocuticle.2. The integumental tissues are composed of columnar epidermal cells and a sub-epidermal connective tissue of a loose spongy type. Large oval reserve cells constitute by far the most predominant type of cells in this tissue. These cells store abundant amounts of carbohydrate, lipid and calcium at various stages throughout the molting cycle; they are also found in the hepatopancreas.3. Within the tubular epithelium of the hepatopancreas are two major types of cells, secretory and absorptive. The former are swol...

279 citations

Journal ArticleDOI
TL;DR: The molting cycle of Penaeus vannamei ju veniles was characterized by distinct and predictable changes in the setae of pleopods, and the relative concentrations of two polypeptides changed during the molting cycles.
Abstract: The molting cycle of Penaeus vannamei ju veniles was characterized by distinct and predictable changes in the setae of pleopods. The molt pattern was diecdysic with a relatively short intermolt period (40%) and a long proecdysial period (>53%). The levels of both total protein and ecdysteroids increased in the hemo lymph during proecdysis, whereas the level of hemo lymph glucose was low at metecdysis and proecdysis and maximal during anecdysis. As revealed by SDS-PAGE, the relative concentrations of two polypeptides (32 kD; 175 kD) changed during the molting cycle.

219 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20221
202112
202017
201912
201810
201714