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At least 595 records · Page 33Linked to original sources
PubMed2005

An increase of uricogenesis in the Kuruma shrimp Marsupenaeus japonicus under nitrite stress.

Kuruma shrimp Marsupenaeus japonicus Bate, under the stress of 0.36 and 1.39 mM nitrite at 30 per thousand (parts per thousand, g kg(-1)) for 48 h, were examined for nucleotide-related compounds, specific activities of xanthine dehydrogenase (XDH), xanthine oxidase (XOD), and uricase. The levels of total nucleotide-related compounds, including xanthine and hypoxanthine, in the gill increased directly with ambient nitrite, whereas the levels of total nucleotide-related compounds, including xanthine and hypoxanthine, in the hepatopancreas were inversely related to ambient nitrite. Specific activity of XOD in the hepatopancreas increased directly with ambient nitrite, whereas no significant difference in uricase activity in the hepatopancreas was observed among three treatments. In another experiment, M. japonicus, following 48 h exposure to 0.36 and 1.39 mM nitrite, were examined for ammonia, urea, and urate levels in tissues. Hemolymph urea and exoskeleton urate levels increased directly with ambient nitrite, whereas hemolymph urate and exoskeleton urea levels were inversely related to ambient nitrite. It is concluded that M. japonicus exhibited uricogenesis and uricolysis, and an increase of uricogenesis occurred for the shrimp under nitrite stress. Urate produced in the hepatopancreas was transported and accumulated in the epidermis, and removed along with the exoskeleton at the time of molting.

Ammonia↗
PubMed2004

Modulation of gill Na+,K+-ATPase activity by ammonium ions: Putative coupling of nitrogen excretion and ion uptake in the freshwater shrimp Macrobrachium olfersii.

The effect of NH4+ ions on (Na+,K+)-ATPase hydrolytic activity was examined in a gill microsomal fraction from M. olfersii. In the absence of NH4+ ions, K+ ions stimulated ATP hydrolysis, exhibiting cooperative kinetics (nH=0.8), to a maximal specific activity of V=556.1+/-22.2 nmol.min(-1).mg(-1) with K(0.5)=2.4+/-0.1 mmol.L(-1). No further stimulation by K+ ions was observed in the presence of 50 mmol.L(-1) NH4+ ions. ATP hydrolysis was also stimulated by NH4+ ions obeying Michaelian kinetics to a maximal specific activity of V=744.8+/-22.3 nmol.min(-1).mg(-1) and KM=8.4+/-0.2 mmol.L(-1). In the presence of 10 mmol.L(-1) K+ ions, ATP hydrolysis was synergistically stimulated by NH4+ ions to V=689.8+/-13.8 nmol.min(-1).mg(-1) and K(0.5)=6.6+/-0.1 mmol.L(-1), suggesting that NH4+ ions bind to different sites than K+ ions. PNPP hydrolysis was also stimulated cooperatively by K+ or NH4+ ions to maximal values of V= 235.5+/-11.8 nmol.min(-1).mg(-1) and V=234.8+/-7.0 nmol.min(-1).mg(-1), respectively. In contrast to ATP hydrolysis, K(+)-phosphatase activity was not synergistically stimulated by NH4+ and K+ ions. These data suggest that at high NH4+ ion concentrations, the (Na+, K+)-ATPase exposes a new site; the subsequent binding of NH4+ ions stimulates ATP hydrolysis to rates higher than those for K+ ions alone. This is the first demonstration that (Na+, K+)-ATPase activity in a freshwater shrimp gill is modulated by ammonium ions, independently of K+ ions, an effect that may constitute a fine-tuning mechanism of physiological relevance to osmoregulatory and excretory processes in palaemonid shrimps.

Adenosine Triphosphate↗
PubMed2004

Influence of photoperiod and temperature on reproductive mode in the Brine shrimp, Artemia franciscana.

Brine shrimp, Artemia, exhibit two modes of reproduction: oviparity (diapause cyst production) and ovoviviparity (live larvae release). Environmental conditions determining these developmental routes are poorly understood, so we investigated the effects of photoperiod and temperature on reproductive mode. Nauplii of A. franciscana were hatched from cysts produced in the Great Salt Lake, Utah, and raised in 2% natural sea salt water under photoperiods of 24, 14, 12, or 10 h at 28 degrees or 20 degrees C. Mating pairs of mature shrimp were isolated and reared continuously under those conditions. The mode of reproduction shown by each pair was determined daily throughout their life span, and found to be greatly affected by photoperiod, and less influenced by temperature. The relative degree of oviparity increased as the photoperiod became shorter at both temperatures. In contrast, the degree of ovoviviparity was higher as the photoperiod became longer at both temperatures. The critical photoperiod appears to be between 12 and 14 h. For all photoperiods examined, the degree of oviparity was higher at 28 degrees C than at 20 degrees C, whereas the degree of ovoviviparity was greater at 20 degrees C than at 28 degrees C.

Animals↗
PubMed2006

Spermatozoal ultrastructure in three Atlantic solenocerid shrimps (Decapoda, Dendrobranchiata).

The spermatozoal ultrastructure in three solenocerid shrimps (Solenocera membranacea, S. africana, and Pleoticus muelleri) from different Atlantic locations was examined with the aim of increasing understanding of the phylogenetic relationships in the Dendrobranchiata. A considerable structural similarity between the sperm of these species and those of penaeid shrimps supports a close affinity between the Penaeidae and Solenoceridae. However, significant differences in the sperm morphology of the previously investigated sicyoniids (namely, a greater complexity of the acrosomal complex) suggest evolutionary separation of the Sicyoniidae from the assemblage Penaeidae-Solenoceridae. Two ultrastructural features distinguish the spermatozoa of the three studied solenocerids from penaeid sperm: 1) separation of the plasma and acrosome membranes at the base of the spike and anterior region of the cap, and 2) asymmetry of the acrosomal cap, which appears to be a synapomorphy of the group. No striking ultrastructural differences were found between the spermatozoa of the closely related species S. membranacea and S. africana, whereas a great number of morphological differences separate the spermatozoa of Pleoticus from those of Solenocera (e.g., shape of the acrosomal cap, structural arrangement of the contents of the whole acrosome vesicle, thickness and distribution of the cytoplasm, and external shape of the spike).

Animals↗
PubMed2006

Determination of chitin and protein contents during the isolation of chitin from shrimp waste.

Accurate determination of chitin and protein contents in crustacean biomass and the intermediate products during the industrial isolation of chitin cannot be made directly from the total nitrogen content, unless the appropriate corrections are applied. This method, however, is affected by the presence of other nitrogen-containing chemical species that are formed endogenously or by the action of microorganisms during the handling of the sample. Therefore, an alternative rapid method to estimate the contents of these components can be very useful both in research and in various fields of application. An original method has been developed to address this problem. The method consists of the development of a set of equations based on the stoichiometric contents of nitrogen of chitin and protein whereby the amounts of each component can be estimated from the value of the total nitrogen content, provided the rest of the proximate composition of the sample is accurately known. In order to validate the procedure, a set of model mixtures of pure chitin and protein concentrate in the solid state, both extracted from shrimp head waste, are used. Excellent agreement between the predicted and real values of chitin and protein are obtained (R2=0.98, slope=0.90). When the proposed method is tested in the analysis of real samples obtained from five different processing protocols of pretreatment of raw shrimp head, it is found that in general the values of protein and chitin contents throughout the various stages of the process vary as expected. [GRAPH: SEE TEXT] Variation of the measured total nitrogen versus calculated stoichiometric total nitrogen of the chitin-protein mixtures.

Animals↗
PubMed2006

Molecular characterization of a cDNA encoding vitellogenin in the banana shrimp, Penaeus (Litopenaeus) merguiensis and sites of vitellogenin mRNA expression.

In order to determine the primary structure of banana shrimp, Penaeus merguiensis, vitellogenin (Vg), we previously purified vitellin (Vt) from the ovaries of vitellogenic females, and chemically analyzed the N-terminal amino acid sequence of its 78 kDa subunit. In this study, a cDNA from this species encoding Vg was cloned based on the N-terminal amino acid sequence of the major 78 kDa subunit of Vt and conserved sequences of Vg/Vt from other crustacean species. The complete nucleotide sequence of Vg cDNA was achieved by RT-PCR and 5' and 3' rapid amplification of cDNA ends (RACE) approaches. The full-length Vg cDNA consisted of 7,961 nucleotides. The open reading frame of this cDNA encoding a precursor peptide was comprised of 2,586 amino acid residues, with a putative processing site, R-X-K/R-R, recognized by subtilisin-like endoproteases. The deduced amino acid sequence was obtained from the Vg cDNA and its amino acid composition showed a high similarity to that of purified Vt. The deduced primary structure, of P. merguiensis Vg was 91.4% identical to the Vg of Penaeus semisulcatus and was also related to the Vg sequences of six other crustacean species with identities that ranged from 86.9% to 36.6%. In addition, the amino acid sequences corresponding to the signal peptide, N-terminal region and C-terminal region of P. merguiensis Vg were almost identical to the same sequences of the seven other reported crustacean species. Results from RT-PCR analysis showed that Vg mRNA expression was present in both the ovary and hepatopancreas of vitellogenic females but was not detected in other tissues including muscle, heart, and intestine of females or in the hepatopancreas of mature males. These results indicate that the Vg gene may be expressed only by mature P. merguiensis females and that both the ovary and hepatopancreas are possible sites for Vg synthesis in this species of shrimp.

Amino Acid Sequence↗
PubMed1991

Ionic currents of the nodal membrane underlying the fastest saltatory conduction in myelinated giant nerve fibers of the shrimp Penaeus japonicus.

The myelinated giant nerve fiber of the shrimp, Penaeus japonicus, is known to have the fastest velocity of saltatory impulse conduction among all nerve fibers so far studied, owing to its long distances between nodal regions and large diameter. For a better understanding of the basis of this fast conduction, a medial giant fiber of the ventral nerve cord of the shrimp was isolated, and ionic currents of its presynaptic membrane (a functional node) were examined using the sucrose-gap voltage-clamp method. Inward currents induced by depolarizing voltage pulses had a maximum value of 0.5 microA and a reversal potential of 120 mV. These currents were completely suppressed by tetrodotoxin and greatly prolonged by scorpion toxin, suggesting that they are the Na current. Both activation and inactivation kinetics of the Na current were unusually rapid in comparison with those of vertebrate nodes. According to a rough estimation of the excitable area, the density of Na current reached 500 mA/cm2. In many cases, the late outward currents were induced only by depolarizing pulses larger than 50 mV in amplitude. The slope conductance measured from late currents were mostly smaller than that measured from the Na current, suggesting a low density of K channels in the synaptic membrane. These characteristics are in good harmony with the fact that the presynaptic membrane plays a role as functional node in the fastest impulse conduction of this nerve fiber.

Animals↗
PubMed2002

Antioxidant and cytotoxic activities of Hypericum sp. on brine shrimps and human cancer cell lines.

Ten different samples of five Hypericum sp. were tested on brine shrimps, human colon carcinoma and human hepatoma cell lines for their cytotoxic activities. H. triquetrifolium Turra. (Rafina) showed the highest activity (LC50 = 22 mg/mL) on brine shrimps, while the extracts of the other nine samples showed significant to moderate activities (LC50 from 37 to 107 mg/mL). H. empetrifolium Wild. (Parnon) showed the highest activity in human colon carcinoma and human hepatoma cell lines, with LC50 values 29 and 25.1 mg/mL, respectively, while the LC50 values of the other samples were more than 45 mg/mL. It is very interesting to observe that most Hypericum samples showed good antioxidant activity in vitro.

Animals↗
PubMed1998

Identification of one tachykinin- and two kinin-related peptides in the brain of the white shrimp, Penaeus vannamei.

This paper reports the purification of three myotropic neuropeptides from the white shrimp Penaeus vannamei. The central nervous systems of 3500 shrimps were extracted in an acidified solvent, after which four to five HPLC column systems were used to obtain pure peptides. A cockroach hindgut muscle contraction bioassay was used to monitor all collected fractions. The pure peptides were submitted to Edman degradation based automated microsequencing. Mass spectrometry and chemical synthesis confirmed the sequences. Ala-Pro-Ser-Gly-Phe-Leu-Gly-Met-Arg-NH2 (Pev-tachykinin, 934.1 Da) belongs to the tachykinin family with identified members in all vertebrate classes and some invertebrate classes: arthropods, annelids and molluscs. A very specific Pev-tachykinin antiserum was developed, which labels 4 neurosecretory cells in the brain. Ala-Ser-Phe-Ser-Pro-Trp-Gly-NH2 (Pev-kinin 1, 749.8 Da) and Asp-Phe-Ser-Ala-Trp-Ala-NH2 (Pev-kinin 2, 694.7 Da) are the first crustacean kinins. Pev-kinin 2 is the first kinin with a Trp-Ala-NH2 instead of a kinin-typical Trp-Gly-NH2 carboxyterminus.

Animals↗
PubMed2002

Effect of some organophosphorus pesticides on oxygen consumption of shrimp, Litopenaeus vannamei.

Oxygen consumption was measured in adult specimens of Litopenaeus vannamei shrimps from a coastal lagoon of Sinaloa, Mexico, during exposure to sublethal concentrations of the organophosphorus pesticides, Diazinon, Folidol, and Gusathion. Each individual was used as a control of itself, to avoid differences between treatments being masked by individual variability. In all three treatments with pesticides, respiration rate, measured by a polarographic electrode, was significantly lower than in controls. This may, at least partly, explain the decrease in shrimp production observed in recent years in the coastal lagoons of Sinaloa.

Animals↗
PubMed2000

Immunomodulation by dietary beta-1, 3-glucan in the brooders of the black tiger shrimp Penaeus monodon.

The present study evaluated the effectiveness of beta-1,3-glucan derived from Schizophyllum commune in enhancing shrimp survival as well as haemocyte phagocytosis and superoxide anion production in brooder Penaeus monodon. Pond-reared P. monodon adults (135 +/- 25 g) stocked in outdoor or indoor tanks were fed either a test diet containing beta-1,3-glucan (2.0 g kg(-1) or a glucan-free control diet for 40 days. Their survival was compared. The brooders reared in indoor tanks were analysed at days 0, 1, 3, 6, 12, 24, 30 and 40 for their haemocyte phagocytic activity and superoxide anion production. The results showed that regardless of indoor or outdoor rearing the survival rate of shrimp fed the glucan diet was significantly higher (P<0.001) than that of the control group. The brooders showed enhanced haemocyte phagocytic activity, cell adhesion and superoxide anion production when glucan was administered in their diets. The immunostimulatory enhancement peaked at day 24 after starting the dietary exposure and subsequently decreased to the pre-feeding level at the end of the 40 days feeding trial.

Adjuvants, Immunologic↗
PubMed2002

Generation of superoxide anion and SOD activity in haemocytes and muscle of American white shrimp (Litopenaeus vannamei) as a response to beta-glucan and sulphated polysaccharide.

Juvenile American white shrimp (Litopenaeus vannamei) were immersed in aerated beta-glucan and sulphated polysaccharide solutions for 1, 3 and 6 h. Superoxide anion and SOD activity in haemocytes and muscle were investigated to evaluate whether beta-glucan and sulphated polysaccharide induce any immunostimulatory activity. Haemocytes and muscle showed different levels of superoxide anion generation and SOD activity (2.0 and 14 times that of control, respectively) when shrimp were immersed for 6 h in aerated sea water containing beta-glucan and sulphated polysaccharide. Total haemocyte count (THC) decreased within the first 24 h after challenge with immunostimulants, but THC and total soluble haemocyte protein increased over normal values after 48-120 h. Single immunostimulation with beta-glucan and sulphated polysaccharide is capable of generating an increase in the respiratory burst of L. vannamei haemocytes.

Animals↗
PubMed1996

Cytopathology of Bay of Piran shrimp virus (BPSV), a new crustacean virus from the Mediterranean Sea.

A new picorna-like or parvo-like virus was found in the hepatopancreas of the shrimp Palaemon elegans from the Bay of Piran (Mediterranean Sea). Bay of Piran shrimp virus (BPSV) infects preferably the R-cells of the hepatopancreas and to a lesser extent the F-cells. In R-cells it is abundant in the cytoplasm and within membrane whorls. In lesser numbers it can also be present in cell organelles like the endoplasmic reticulum, autophagosomes, or mitochondria. Less contrasting virus-like particles are observed in the nucleoplasm, suggesting a nuclear replication of the virus and completion of assembly in the cytoplasm. In F-cells the virus is located mostly in cisternae of the Golgi bodies. Occasionally, there are also virus clusters in the cytoplasm. B-cells are only rarely infected. The virus seems to invade the host cells from the lumen of the hepatopancreatic tubules through the microvillous border. Mature viruses are released again into the hepatopancreatic lumen by discharge of lytic epithelial cells. Individual viruses can also penetrate through the basal cell membrane into the hemal space. Occasionally, fixed phagocytes are attached to the basal lamina of heavily infected hepatopancreas cells, indicating an activation of the immune defense system by the virus.

Animals↗
PubMed1997

Susceptibility to Taura Syndrome Virus of Some Penaeid Shrimp Species Native to the Gulf of Mexico and the Southeastern United States

Experimental studies demonstrated that Penaeus setiferus, but not Penaeus aztecus or Penaeus duorarum, could be killed by Taura syndrome virus (TSV). However, specimens of P. setiferus that survived infection and both P. aztecus and P. duorarum at least 79 days postexposure that did not demonstrate gross signs of infection were shown to harbor virus by bioassay using Penaeus vannamei, a highly susceptible target host. Consequently, all three of those penaeids native to the southeast United States can serve as carriers or reservoir hosts of TSV without necessarily exhibiting disease. Infections in P. setiferus took longer to cause mortality than in P. vannamei and killed a smaller percentage of that host. Also, histological lesions diagnostic of TSV infection were not always evident in sectioned tissue of infected P. setiferus, and they generally were more conspicuous during Days 4-7 postexposure compared with lesions that also occurred at both earlier and later days in tissues of P. vannamei. Infections could be produced by injection, ingestion, and incorporation of the infective material into dietary brine shrimp. There appeared to be a difference in susceptibility to TSV disease by different stocks of P. setiferus, but different experiments produced conflicting evidence regarding a relationship between age and predilection to mortality. Large and small specimens of equal-aged shrimp succumbed similarly to TSV infections for both P. vannamei and P. setiferus. The nonnative species P. chinensis demonstrated a high susceptibility to experimental TSV disease.

Journal Article↗
PubMed1998

Infectivity and pathogenicity of Baculovirus penaei (BP) in cultured larval and postlarval Pacific white shrimp, Penaeus vannamei, related to the stage of viral development.

The infectivity and pathogenicity of the penaeid shrimp virus, Baculovirus penaei (BP), is influenced by the stage of viral development. This study consisted of a preliminary experiment which showed that nonocculuded virus administered per os is infective, followed by two infectivity experiments. In the first phase of each infectivity experiment, mysis stage larvae of Penaeus vannamei were inoculated with BP and samples of infected tissue were collected at various times postinoculation (p.i.). These samples were then used to inoculate either mysis or postlarval stage P. vannamei in the second phase of each experiment. Viral inocula prepared from patently infected tissues consistently produced infections in both mysis and postlarval stage shrimp. Inocula prepared from prepatently infected tissue collected 12-18 h p.i. produced infections in some, but not all replicate cultures, while inocula prepared from tissues collected earlier than 12 h p.i. were not infective. Viral development in mysis stage larvae was substantially delayed and the mortality was significantly lower when the viral inocula were prepared from prepatently compared to patently infected tissues. BP appears to be most pathogenic to larvae that have been exposed to inocula prepared from tissues that had recently developed a high prevalence of patent infections or about 72 h p.i.

Animals↗
PubMed1999

Miocene radiation of deep-sea hydrothermal vent shrimp (Caridea: Bresiliidae): evidence from mitochondrial cytochrome oxidase subunit I.

The evolutionary history of deep-sea shrimp (Caridea: Bresiliidae) inhabiting deep-sea hydrothermal vent and hydrocarbon seep environments was assessed using the mitochondrial Cytochrome c Oxidase subunit I (COI) gene (600 bp). Phylogenetic analyses (parsimony, likelihood, and neighbor-joining) recovered three distinct clades (A, Rimicaris/Chorocaris/Opaepele; B, Alvinocaris; and C, Mirocaris) consistent with higher level taxonomy based on morphology. However, robust phylogenetic results suggested that Chorocaris is paraphyletic and that Mirocaris fortunata and M. keldyshi may not be genetically distinct. A Kishino-Hasegawa likelihood approach was used to test alternative phylogenetic hypotheses based on biogeography and morphology. Evolutionary relationships of vent-endemic shrimp species did not appear to be correlated either with their extant biogeographic distribution or with the history of sea floor spreading. Additionally, COI data suggested that these vent-endemic organisms are not remnants of a Mesozoic vent assemblage; instead, they radiated in the Miocene.

Animals↗
PubMed2000

Identification of two major virion protein genes of white spot syndrome virus of shrimp.

White Spot Syndrome Virus (WSSV) is an invertebrate virus, causing considerable mortality in shrimp. Two structural proteins of WSSV were identified. WSSV virions are enveloped nucleocapsids with a bacilliform morphology with an approximate size of 275 x 120 nm, and a tail-like extension at one end. The double-stranded viral DNA has an approximate size 290 kb. WSSV virions, isolated from infected shrimps, contained four major proteins: 28 kDa (VP28), 26 kDa (VP26), 24 kDa (VP24), and 19 kDa (VP19) in size, respectively. VP26 and VP24 were found associated with nucleocapsids; the others were associated with the envelope. N-terminal amino acid sequences of nucleocapsid protein VP26 and the envelope protein VP28 were obtained by protein sequencing and used to identify the respective genes (vp26 and vp28) in the WSSV genome. To confirm that the open reading frames of WSSV vp26 (612) and vp28 (612) are coding for the putative major virion proteins, they were expressed in insect cells using baculovirus vectors and analyzed by Western analysis. A polyclonal antiserum against total WSSV virions confirmed the virion origin of VP26 and VP28. Both proteins contained a putative transmembrane domain at their N terminus and many putative N- and O-glycosylation sites. These major viral proteins showed no homology to baculovirus structural proteins, suggesting, together with the lack of DNA sequence homology to other viruses, that WSSV may be a representative of a new virus family, Whispoviridae.

Amino Acid Sequence↗
PubMed2001

Cloning, characterization, and phylogenetic analysis of a shrimp white spot syndrome virus gene that encodes a protein kinase.

An open reading frame (ORF) that encodes a 715-amino-acid polypeptide was found in an 8421-bp EcoRI fragment of the shrimp white spot syndrome virus (WSSV) genome. The polypeptide shows significant homology to eukaryotic serine/threonine protein kinase (PK) and contains the major conserved subdomains for eukaryotic protein kinases. Coupled in vitro transcription and translation generated a protein having an apparent molecular mass of about 87 kDa according to sodium dodecyl sulfate-polyacrylamide gel electrophoresis. For transcriptional analysis of the pk gene, total RNA was isolated from WSSV-infected shrimp at different times after infection. Northern blot analysis with pk-specific riboprobe found a major and a minor transcript of 2.7 and 5.7 kb, respectively. Rapid amplification of the 5' cDNA ends of the major 2.7-kb pk transcript showed that there were two transcriptional initiation sites located at nucleotide residues -38(G) and -39(G) relative to the ATG translational start codon. Temporal expression analysis by RT-PCR indicated that the transcription of the pk gene started 2 h after infection and continued for at least 60 h. Phylogenetic analysis showed that WSSV protein kinase does not have any close relatives and does not fall into any of the major protein kinase groups.

3' Untranslated Regions↗