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At least 829 records · Page 46Linked to original sources
PubMed1999

Reexamination of hemocytes in brine shrimp (Crustacea, branchiopoda).

In 1941, a single type of hemocyte was described in the blood of the brine shrimp Artemia salina using light microscopy. This condition is unusual because most crustaceans examined using morphological, cytochemical, and functional methods have at least two types of hemoctyes. Upon examining A. franciscana, we found a single type of disk-shaped hemocyte, with a centrally located nucleus and about 15 large (6 microm diameter) granules. The granules stain for the presence of acid phosphatase and react with L-DOPA suggesting, respectively, that they are involved in degrading ingested material and possess the phenoloxidase system. Hemocytes require calcium for adhesion, bind together to mend small wounds in the body wall, and are able to phagocytose bacteria. Blood cells of A. franciscana are morphologically and functionally similar to those of the primitive chelicerate, Limulus polyphemus, and both forms have apparently given rise to more advanced taxa with multiple types of hemocytes. The major difference between the two species is the presence of the phenoloxidase system in the Crustacea and its apparent absence in the chelicerates.

Animals↗
PubMed1996

Fenestration in the myelin sheath of nerve fibers of the shrimp: a novel node of excitation for saltatory conduction.

Giant nerve fibers of the shrimp family Penaeidae conduct impulses at the velocity highest among all animal species (approximately 210 m/s; highest in mammals = 120 m/s). We examined these giant and other small nerve fibers morphologically using a differential interference contrast microscope as well as an electron microscope, and found a very specialized form of excitable membrane that functions as a node for saltatory conduction of the impulse. This node appeared under the light microscope as a characteristic pattern of concentrically aligned rings in a very small spot of the myelin sheath. The diameter of the innermost ring of the node was about 5 microns, and the distance between these nodes was as long as 12 mm. Via an electron microscope, these nodes were characterized by a complete lack of the myelin sheath, forming a fenestration that has a tight junction with an axonal membrane. Voltage clamp measurements by a sucrose gap technique demonstrated that the axonal membrane at these fenestration nodes is exclusively excitable and that the large submyelinic space is a unique conductive pathway for loop currents for saltatory conduction through such fenestration nodes.

Animals↗
PubMed1999

Cytotoxic activity of marine macro-algae on Artemia salina (brine shrimp).

A total of 22 ethanol extracts of seaweed species (13 brown, 6 green and 3 red) collected from the Karachi coast were investigated for brine shrimp cytotoxicity. Of all the species, only six namely Stoechospermum marginatum, Sargassum swartzii, S. binderi, Spatoglossum asperum, Stokeyia indica (brown) and Caulerpa racemosa (green) showed significant activity. n-Hexane-soluble fractions of the ethanol extract of S. marginatum and S. swartzii were found to be responsible for the activity, whereas the methanol-soluble fractions of S. asperum and S. binderi were most active. The water extract of S. indica and C. racemosa exhibited the most prominent activity (LC50 value below 70 micrograms/mL) when compared with the ethanol extracts and their fractions. Cytotoxic activity may be due to the compounds differing in polarity.

Animals↗
PubMed1997

Activity of insulin growth factors and shrimp neurosecretory organ extracts on a lepidopteran cell line.

Ecdysteroids, or molting hormones, have been proven to be key differentiation regulators for epidermal cells in the postembryonic development of arthropods. Regulators of cell proliferation, however, remain largely unknown. To date, no diffusible insect peptidic growth factors have been characterized. Molecules structurally related to insulin have been discovered in insects, as in other eucaryotes. We developed in vitro tests for the preliminary characterization of potential growth factors in arthropods by adapting the procedures designed to detect such factors in vertebrates to an insect cell line (IAL-PID2) established from imaginal discs of the Indian meal moth. We verified the ability of these tests to measure the proliferation of IAL-PID2 cells. We tested mammalian insulin and insulin-like growth factors (IGF-I, IGF-II). Following an arrest of cell proliferation by serum deprivation, IGF-I and IGF-II caused partial resumption of the cell cycle, evidenced by DNA synthesis. In contrast, the addition of 20-hydroxyecdysone arrested the proliferation of the IAL-PID2 cells. The cell line was then used in a test for functional characterization of potential growth factors originating from the penaeid shrimp, Penaeus vannamei. Crude extracts of neurosecretory and nervous tissues, eyestalks, and ventral neural chain compensated for serum deprivation and stimulated completion of mitosis. Arch.

Animals↗
PubMed2000

Interaction of shrimp ras protein with mammalian caveolin-1.

BALB/3T3 cells were transformed by transfection with DNA encoding the mutated ras(Q(61)K) from shrimp Penaeus japonicus (Huang and Chuang. 1999. J Exp Zool 283:510-521). The caveolin-1 in the membrane fraction extractable with 2% octyl glucoside was significant reduced, compared to untransformed cells. To understand this in more detail, the interaction of S-Ras with caveolin was investigated using caveolin-1 purified from rat lungs. The purified caveolin-1 binds c-Src, suppressing its autophosphorylation. It also binds to phosphatidylserine-cholesterol liposomes. These reconstituted caveolin-phosphatidylserine-cholesterol vesicles, which act as a model of caveolae, recruit both bacterially expressed S-Ras and rat K(B)-Ras proteins, as demonstrated on western blots with antibodies against caveolin-1 and Ras. Caveolin-1 suppressed the intrinsic GTPase activity of S-Ras, sustaining it in the active GTP bound form. By contrast, caveolin-1 enhanced the intrinsic GTPase activity of K(B)-Ras, to convert it into the inactive GDP-bound form. These events suggest that caveolin may act as a docking site for Ras proteins and may be able to either maintain or alter their activity state. These events may be associated with the ability of S-ras(Q(61)K) to successfully transform cells.

3T3 Cells↗
PubMed2006

Quantification of astaxanthin in shrimp waste hydrolysate by HPLC.

In the present study, a simple and rapid reversed-phase HPLC method for the determination of astaxanthin in shrimp waste hydrolysate has been developed and validated. The analytical procedure involves the direct extraction of astaxanthin from the lipid fraction with methanol. The analytical column, SS Exil ODS, was operated at 25C. The mobile phase consisted of a mixture of water:methanol:dichloromethane:acetonitrile (4.5:28:22:45.5 v/v/v/v) at a flow rate of 1.0 mL/min. Detection and identification were performed using a photodiode array detector (lambda(detection) = 476 nm). The proposed HPLC method showed adequate linearity, repeatability and accuracy.

Animals↗
PubMed1994

Optimization of the analytical performance of the magnetic sector mass spectrometer for the identification of residual chloramphenicol in shrimp.

Chemical noise limits mass spectrometric detection of chloramphenicol (CAP) with electron capture ionization at low resolution, and makes CAP identification at concentrations of 5 parts per billion (ppb) difficult. Increasing the resolution from 1000 to 3500, however, was sufficient to separate the analyte signals from the noise signals, and resulted in a 100 times higher analytical sensitivity. The introduction of sweep gas in the ion source decreased the scattering of the quantitative results on average by a factor of 7, and thereby improved the precision of the analyses to an acceptable level (CV < 10%). Under such conditions, CAP residues of 1.5 and 2.1 ppb in shrimp as determined by electron capture gas chromatography/mass spectrometry can readily be identified by monitoring four diagnostic ions.

Animals↗
PubMed1988

Remodeling of nerves during claw reversal in adult snapping shrimps.

Adult snapping shrimps, Alpheus heterochelis, undergo a reversal of their claw laterality following removal of the major claw, a process in which the existing minor claw transforms into a major and a new minor regenerates at the old major site. During such reversals the nerves to the ganglion are remodeled from one claw type to the other. Conversion of the nerves from the minor to the major type occurs within several days after removal of the contralateral major claw and involves the rapid addition of large numbers of sensory axons together with deletion of a few. Thus modeling of the nerves is essentially complete within the first intermolt in tandem with changes in the motoneurons but well ahead of changes in the muscle and external morphology. Conversion of the major nerves to the minor type is via massive degeneration of sensory axons during the first and second intermolts because of the loss of their peripherally located cell bodies. This is followed by proliferation of largely unmyelinated axons in the third intermolt, some of which become myelinated in the subsequent intermolts. Thus remodeling of the major nerves to minor, which is associated with the loss of a claw and the regeneration of a new minor claw, is a more traumatic and prolonged process compared to the remodeling of the minor nerves to major which is associated with the transformation of an existing claw.

Animals↗
PubMed1987

Total mercury and its distribution in blue crab and deep water pink shrimp from Alexandria coast.

Total mercury content and its distribution in muscles and viscera of male and female blue crab (Callinectes sapidus Rothbum) and deep water pink shrimp (Parapenacus longirostris) collected from the 3 main fishing grounds near the Alexandria coast in the Mediterranean sea was estimated. The results indicate that the mercury content in the muscles of both species differ according to fishing areas, size, sex, and species. More than 75% of total mercury were accumulated in the viscera of both species which indicates that the mercury entered in these organisms via the feed chain.

Animals↗
PubMed1984

The primary structure of elongation factor EF-1 alpha from the brine shrimp Artemia.

cDNA as well as amino acid sequencing has revealed the complete primary structure of elongation factor EF-1 alpha from the brine shrimp Artemia. A comparison with the published sequences of bacterial EF-Tu, mitochondrial EF-Tu and chloroplastic EF-Tu shows that distinct areas of these polypeptide chains are conserved in evolution. The evolutionary distance between prokaryotic and eukaryotic types of EF-Tu is larger than among bacterial and organellar EF- Tus . A number of regions present in both EF-Tu and EF-G from Escherichia coli are also found in EF-1 alpha from Artemia.

Amino Acid Sequence↗
PubMed1984

Neuromuscular relationships during claw regeneration in Californian snapping shrimp.

We have examined the innervation patterns of the two excitor axons to the closer muscle in the dimorphic (snapper and pincer) claws of Californian snapping shrimp (Alpheus californiensis). In both claws the fast-closer excitor (FCE) axon supplies all of the closer muscle fibers. The slow-closer excitor (SCE) axon, however, makes functional connections only with fibers on the dorsal and ventral margins, which are composed of slow-type fibers in the large snapper claw and of intermediate-type fibers in the smaller pincer claw. The central band of fast fibers in the pincer closer muscle is not innervated by the SCE. During claw regeneration, the closer muscle is initially composed of a population of fast fibers in the pincer and intermediate-type fibers in the snapper. The innervation patterns of the two excitatory motor axons in regenerating claws at this stage are the same as in fully developed claws. During the first intermolt period some fast-closer muscle fibers in the pincer claw differentiate into intermediate-type fibers, but the axon innervation patterns do not change. If the correlation between SCE axon innervation pattern and the regional distribution of different muscle fiber types is indicative of nerve-muscle interactions, the present data suggest that the trophic influence must proceed from nerve to muscle.

Animals↗
PubMed1984

Differences in phosphorylation of the two large subunits of brine shrimp Na,K-ATPase.

Analysis of purified Na,K-ATPase from brine shrimp nauplii revealed two molecular forms of the alpha subunit separable by sodium dodecyl sulfate-polyacrylamide gel electrophoresis [G.L. Peterson, R.D. Ewing, S.R. Hootman, and F.P. Conte (1978) J. Biol. Chem. 253:4762]. The molecular form with lower mobility is designated alpha 1 and the one with higher mobility, alpha 2, in a neutral or alkaline gel system. Differences in Na+-dependent, K+-sensitive phosphorylation of these two molecular forms have been investigated by directly measuring the radioactivity present in each phosphoprotein after separation of the two forms by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In the presence of Na+,Mg2+, and ATP, when the ATP concentration is above 1 microM, both alpha subunits are phosphorylated, although the phosphoprotein content of alpha 1 is considerably greater than that of alpha 2. Below 1 microM ATP, the phosphoprotein content of alpha 2 is even further reduced. These striking differences in phosphorylation at low ATP concentrations are not due to a greater instability of the alpha 2 phosphoprotein during the long electrophoresis times or during fixation, staining, and destaining. The proportion of total phosphoprotein content in alpha 2, as well as the relationship between phosphoprotein content and ATP concentration, is unchanged when the radioactive analysis is performed on frozen gels that have been electrophoresed for shorter times, even though the actual amount of phosphorylation is 15 times greater than with fixed gels. Since the concentration of alpha 1 and alpha 2 vary during development [G.L. Peterson, L. Churchill, J.A. Fisher, and L.E. Hokin (1982) J. Exp. Zool. 221:295], the differences in phosphorylation may be relevant to differences in Na,K-ATPase activity during different development stages.

Adenosine Triphosphate↗
PubMed1984

A reversal in relative mobility of the two large subunits of brine shrimp (Na+ + K+)-adenosinetriphosphatase.

The two large subunits of brine shrimp Na,K-ATPase can be resolved by sodium dodecyl sulfate-polyacrylamide gel electrophoresis at neutral pH and at acidic pH. These subunits appear to reverse their positions on the gel relative to each other when resolved at acidic pH relative to neutral pH. The migration of both subunits is apparently affected by charge, even in the presence of 2.5% sodium dodecyl sulfate.

Adenosine Triphosphate↗
PubMed1994

Ontogeny of cardiac function in the brine shrimp Artemia franciscana Kellogg 1906 (Branchiopoda: Anostraca).

In newly hatched brine shrimp (Artemia franciscana) cardiac organogenesis and function could only take place with the onset of segmentation. Consequently differences in age, body size and temperature (in the range 22-34 degrees C) affected the ontogeny of cardiac activity only indirectly, through their influence on developmental stage. Once present the frequency of cardiac activity (heart beat) increased with increasing body size and concomitant differentiation of cardiac tissue. At least initially, (dry body weight 11-16 micrograms) heart rate was independent of temperature and weight specific heart rate was independent of body size. When differentiation neared completion, and cardiac growth switched to elongation (dry body weight > 16 micrograms), there was a change in the pattern of cardiac function. There was now a decrease in heart beat with increasing body size and weight specific heart rate showed an inverse relationship with body weight. Heart rate also became temperature dependent, although it remained relatively insensitive. In conclusion it is suggested that the ontogeny of cardiac function in Artemia is constrained by an anamorphic (direct) pattern of development where segment formation occurs post hatch. Early cardiac functioning cannot be predicted on an allometric basis, as cardiovascular structure and function changes qualitatively during ontogeny.

Animals↗
PubMed2003

Interspecific variations in the morphology and ultrastructure of the rhabdoms of oplophorid shrimps.

Interspecific variations in rhabdom structure between various oplophorid shrimps are described and the differences are related to the light environment at different depths within the mesopelagic zone. The ultrastructure of the distal rhabdom in these species is described for the first time. Quantitative measurements show that the proportion of the rhabdom layer occupied by the distal rhabdom varies from 3.5-25% in the dorsoventral plane of the eye of Systellaspis debilis. The distal rhabdom occupies less than 1% of the rhabdoms in the eye of Acanthephyra pelagica, where it can only be seen by using the electron microscope. It is suggested that the rhabdoms of those species that remain within the photic zone (such as S. debilis) are adapted to maximize contrast, whereas in those whose depth ranges extend into the aphotic zone (such as A. pelagica) they are adapted for maximum sensitivity.

Adaptation, Biological↗
PubMed1992

Microbial degradation of shrimp-shell waste.

A total of 40 strains of bacteria were isolated and tested for their potentiality to degrade chitin and utilize shrimp-shell waste for the production of chitinase. The activity ratio, percentage of weight loss and enzyme activity were determined for cultures exhibiting highest chitinolytic activities. The most active organisms were identified as Alcaligenes denitrificans, Bacillus amyloliquefaciens, B. megaterium and B. subtilis. The potentiality of the first two organisms to degrade chitin was reported for the first time.

Alcaligenes↗
PubMed2007

Expression patterns of ubiquitin, heat shock protein 70, alpha-actin and beta-actin over the molt cycle in the abdominal muscle of marine shrimp Litopenaeus vannamei.

Crustacean muscle growth is discontinuous due to molt cycle. To characterize molt-related gene expression patterns, we studied the mRNA levels of molecular chaperone-ubiquitin and heat shock protein 70 (Hsp 70) in comparison with muscle protein alpha-actin and beta-actin in marine shrimp Litopenaeus vannamei. Total RNA from abdominal muscle was isolated from 3-month-old animals in six different molt stages. The mRNA levels of target genes were detected by reverse-transcriptase-multiplex PCR and expressed as the ratio to elongation factor-1alpha. Ubiquitin mRNA levels were relatively steady over all stages of the molt cycle. Hsp70 levels were not detectable in early postmolt and late premolt stages, but showed a progressive increase from late postmolt to intermolt stages. Expression levels of alpha-actin gene were lower during postmolt, reached a plateau in intermolt and remained relatively high in premolt stage. Levels of beta-actin increased progressively from postmolt to intermolt, reaching a maximum value in premolt. Therefore, the mRNAs encoding for ubiquitin and Hsp 70 in abdominal muscle did not increase significantly in premolt stages, which is typically associated with claw muscle degradation. Muscle structural alpha-actin and cytoskeletal beta-actin were increased during intermolt and premolt stages, suggesting high muscle growth during these stages in the abdominal muscle of the L. vannamei.

Abdominal Muscles↗