Search results for "moult"

Fine structure of sensilla during moulting inNeomysis integer (Leach) (Crustacea, Mysidacea)

1980

During the moulting cycle the sensory cells and the newly formed hair shaft remain connected to the old cuticular receptive apparatus of the sensillum by the elongated outer segments of the dendrites, which run through the exuvial space. A surface coat covering the outer dendritic segments protects them against the chemical influences of the exuvial fluid. The findings suggest that the receptors remain functional until ecdysis. This moulting type is considered to be a transitional form between the moulting types so far known.

Moulting hormone content in prothoracic glands and oenocytes ofTenebrio molitor within a moulting cycle

1973

An isolierten und homogenisierten Prothorakaldrusen und Oenocyten vonTenebrio wurde der Gehalt an Hautungshormonen mit Hilfe des Calliphoratests bestimmt. Dabei stellte sich heraus, dass sowohl Prothorakaldrusen als auch Oenocyten wahrend des gesamten Hautungszyklus verpuppungsaktive Stoffe, wenn auch in unterschiedlicher Menge, enthalten. Die Ergebnisse werden mit jenen verglichen, bei denen der Hormontiter durch Extraktion ganzer Tiere bestimmt wurde. In Verbindung damit wurde das Zusammenspiel von Synthese und Abbau der Hormone diskutiert.

Shipping noise affecting immune responses of European spiny lobster (Palinuruselephas)

2015

Marine crustaceans are influenced by numerous environmental factors. Environmental stress from pollutants seems to affect their metabolism, growth, moulting, survival, and immune defence. Recently, it has become clear that there is an impact of the global increase in sea noise levels due to shipping traffic on crustacean welfare. Considering the ecological and commercial importance of the European spiny lobster (Palinurus elephas (Fabricius, 1787)) in most parts of the Mediterranean coastal area, in the present study we investigated whether shipping noise pollution contribute to changing the immune parameters of stress in the European spiny lobster. The animals were exposed to a mix of nois…

Effect of sublethal exposure to mercury in the biochemical composition of hepatopancreas in Procambarus clarkii during the recovery after starvation

1993

Abstract Freshwater crayfish undergo seasonal periods of starvation. The hepatopancreas is the main energetic-storage organ in this animal. An adequate replenishment of energetic reserves after these periods of fasting is critical for the proper growth and reproduction in this species. Mercury compounds enter the biological environment from natural discharges and anthropogenic sources. Mercuric chloride is one of the most toxic metallic salts found in polluted waters. In these studies, we report the effect of mercuric chloride in the biochemical composition of crayfish hepatopancreas during the recovery period after prolonged starvation. Adult intermolt crayfish (P. clarkii) were kept starv…

Variability of ecdysteroid-induced cell cycle alterations in Drosophila Kc sublines.

1987

. The cell cycle of two lines isolated from Drosophila Kc cells was followed by flow cytofluorometry and cell counting. The first line is the 8-9K clone which grew in a medium supplemented with 5% serum; the second, named subline Kc0, grew in a serum-free medium. The stationary phase is characterized by a G2 cell accumulation: 73% in the 8-9K clone and 50% in the Kc0 subline. When the medium was supplemented with the steroid moulting hormone 20-hydroxyecdysone, more than 90% of 8-9K cells and 65% of Kc0 cells were progressively arrested in G2. In the continuous presence of 20-hydroxyecdysone, most of the 8-9K cells remain G2-arrested; no massive G2 release into M was observed and only a few…

Characterization of two new cuticular genes specifically expressed during the post-ecdysial molting period in Tenebrio molitor

1998

Abstract In a previous study, we have isolated a cDNA, TM-ACP17 , coding for a post-ecdysial adult protein of Tenebrio molitor . After screening of a genomic library with TM-ACP17 , we report isolation and sequencing of TM-ACP17 gene and a new gene, TM-LPCP29 , coding for a larval–pupal protein. These two genes exhibit a common sequence of 15 nucleotides and a characteristic of most cuticular protein genes so far described: an intron interrupting the signal peptide. The deduced aa sequence of TM-LPCP29 exhibits a high percentage of Ala (26.5%) and Val (17.5%) and is highly hydrophobic. In the N-terminal part, the motif VAAPV is repeated ten times. Numerous histidine residues are present in …

Reading Victory Garden : Competing Interpretations and Loose Ends

2000

Biomineralizations: insights and prospects from crustaceans.

2011

19 pages; International audience; For growing, crustaceans have to molt cyclically because of the presence of a rigid exoskeleton. Most of the crustaceans harden their cuticle not only by sclerotization, like all the arthropods, but also by calcification. All the physiology of crustaceans, including the calcification process, is then linked to molting cycles. This means for these animals to find regularly a source of calcium ions quickly available just after ecdysis. The sources of calcium used are diverse, ranging from the environment where the animals live to endogenous calcium deposits cyclically elaborated by some of them. As a result, crustaceans are submitted to an important and energ…

Nucleotide sequence of an adult-specific cuticular protein gene from the beetle Tenebrio molitor: effects of 20-hydroxyecdysone on mRNA accumulation.

1993

0962-1075 (Print) Journal Article Research Support, Non-U.S. Gov't; The accumulation of transcripts from two adult-specific cuticular genes (ACP-20 and ACP-22) is shown to be modified after addition of exogenous 20-hydroxyecdysone. In the continuous presence of high levels of the hormone, the expression of ACP-20 gene is significantly weaker than that of untreated controls, while ACP-22 expression is 2.5-fold increased. During active synthesis of the ACP messages, a 0.5 microg 20-hydroxyecdysone injection causes a rapid 2-fold increase in ACP-22 mRNA and is not able to repress ACP-20 mRNA accumulation. We conclude that these genes whose transcripts appear in an almost coordinated manner in …

Nachweis von h�utungsaktiven Stoffen in isolierten Prothorakaldr�sen und Oenocyten beiBombyx mori w�hrend des 5. Larvenstadiums

1977

The content of moulting hormones has been determined in homogenates of isolated prothoracic glands and oenocytes during the 5th instar of the silkworm,Bombyx mori by means of the Calliphora bioassay. Prothoracic glands show variable activity in the production of moulting hormones, reaching a maximum near the end of the larval period. Comparable activities, but at higher levels, could be demonstrated in oenocytes. Controls with doubled quantities of tissue produced in a proportionate reaction in the bioassay. Fat bodies were inactive. Prothoracic glands and oenocytes incubated together resulted in a slower pupation index than would be expected from the sum of single determinations of oenocyt…