Salina Cysts Research Articles

Effect of plant ribosome-inactivating proteins on ribosomes from various metazoan species

1. 1. Ribosomes from various metazoan species [ Dendrocoelum lacteum (planaria), Musca domestica (house fly) larvae, Artemia salina (brine shrimp) cysts, Salmo gairdneri (rainbow trout) liver, Rana esculenta (frog) liver, Numida Meleagris (guinea-fowl) liver and Cuniculus cuniculus (rabbit) reticulocytes] were isolated and their susceptibility to the action of several ribosome-inactivating proteins from plants was tested. 2. 2. Ribosomes from the species examined were affected by ribosome-inactivating proteins to a different extent, without correlation with the position in the evolutionary scale. 3. 3. Considerable differences between the effect of the various ribosome-inactivating proteins on ribosomes of a given species were observed.

Effects of Heavy Metals on the Hatching Rates of Brine Shrimp Artemia salina Cysts

AbstractThe effects of heavy metals (Hg2+, Cd2+, Co2+, Cr3+, Pb2+, Cu2+, Fe2+. Ni2+, Zn2+, Mn7+, Mn4+ and Mn2+) on the relative hatching percentage of brine shrimp, Artemia salina were assessed. Artemia salina cysts (San Francisco Bay Brand) hatched in seawater containing various heavy metal concentrations. After 48 hours, the number of hatched nauplii were counted. A negative linear relationship between hatching rate of Ariemia salina cysts and heavy metal concentration occurred, except copper which conformed to a cubic model. The relative toxicities of heavy metals on Artemia salina cysts were as follows (Cu2+, most toxic; Mn2+, least toxic): Cu2+ > Zn2+ > Ni2+ > Co2+ > Mn7+ > Cr3+ > Cd2+ > Fe2+ > Hg2+ > Mn4+ > Pb2+ > Mn2+.

Accumulation of Heavy Metals in the Nauplii of Artemia salina

Abstract Artemia salina cysts (San Francisco Bay Brand) were exposed in seawater containing multiple concentrations of either a single heavy metal (Hg, Cu, Zn, Pb, Cd, Co, Ni, Cr, Mn and Fe) or combination of heavy metals. The heavy metal accumulation in Artemia nauplii increased linearly with an increase in the heavy metal concentration in water. The metals could be detected in nauplii exposed to a single heavy metal at dosages of 5 μg/L for Hg, Zn, Mn, Fe and Cu; 25 μg/L for Cd and Cr; 50 μg/L for Co; 100 mUg/L for Ni; and 250 μg/L for Pb. Cysts exposed to several heavy metal combinations had minimum effective dosages equal to or lower than the single heavy metals‐ 5 μg/L for Cu, Cr, Zn, Mn and Fe; 25 μg/L for Cd and Ni; 50 μg/L for Co; and 250 μg/L for Pb. The accumulation of Cu, Ni and Co by Artemiu nauplii did not differ for animals exposed to single or combined heavy metal solutions. Cr, Zn and Pb had a synergistic effect of heavy metal uptake in combined heavy metal element solutions, however, Fe, Cd and Mn had an antagonistic effect.

Quantitative structure-toxicity relationships with osmotically stressed Artemia salina nauplii

Aquatic animals subjected to osmotic stress may show an increased toxicity response to water contaminants. Artemia salina cysts were hatched and raised in 50% or 25% artificial seawater at 19°C and the resulting Stage II nauplii were exposed to various organic chemicals to determine immobilisation concentrations (IC 50.24h). Simple linear regressions were used to compare the IC 50 values at both salinities to n-octanaol/water partition coefficients. The fundamental equation is described by log 1/C 50 = a + b × log P. Positive linear regressions were observed at both salinities indicating a nonspecific-type toxicity. The regression and correlation parameters were not significantly different between the two relationships. As the salinity was decreased, however, the intercepts increased and the slopes decreased in a slight but consistent fashion. The present quantitative model appears to be relatively insensitive to changes in the toxicity of organic chemicals to osmotically stressed A. salina nauplii.

Sequence homology between EF-1α, the α-chain of elongation factor 1 from Artemia salina and elongation factor EF-TU from Escherichia coli

In the course of a structural analysis of the α-chain of elongation factor 1 from Artemia salina cysts, we present four amino acid sequences comprising together half of the polypeptide chain. A comparison of these sequences with the primary structure of elongation factor EF-Tu from Escherichia coli reveals a clear correspondence between the eukaryotic and prokaryotic protein throughout their polypeptide chains. The results support a basic conservation of the structure of the aminoacyl-tRNA carrying enzyme in evolution. The occurrence, in the eukaryotic factor, of several ϵ-trimethyllysine residues, is remarkable.

Partial Purification of the Messenger RNA for Eukaryotic Elongation Factor Tu from Artemia salina

Polyadenylated RNA from developing Artemia salina cysts was fractionated by centrifugation through a sucrose gradient containing methylmercuric hydroxide (CH3HgOH). Aliquots of each fraction were directly added to a rabbit reticulocyte lysate to program protein synthesis in vitro. The translation products were assayed for eukaryotic elongation factor Tu (eEF-Tu) by immunoprecipitation with an antibody raised in rabbits and purified by affinity chromatography. The immunoprecipitated radioactivity was analyzed by polyacrylamide gel electrophoresis in the presence of sodium dodecylsulphate. Sequences coding for eEF-Tu sediment in the 20-S region of the gradient and form a major component of the poly(A)-containing RNA. The mRNA of the 20-S region, comprising about 10% of the poly(a)-containing RNA fractionated on the gradient, has been translated in vitro and 30% of the translation products represent immunoprecipitable eEF-Tu protein chains with an Mr of 50000.

Flow of informational RNA from cytoplasmic poly(A)-containing particles to polyribosomes in Artemia salina cysts at early stages of development

When Artemia salina cysts are incubated at 28°C in artificial seawater, the pool of cytoplasmic mRNA as measured by the [ 3H]poly(U) hybridization technique is depleted, and a parallel increase in the polysome bound mRNA is observed. The shift of informational RNA from subribosomal particles to polyribosomes occurs without a significant increase in the amount of poly(A)-containing RNA per embryo, at least during the first hours of development. In order to ascertain whether resumption of development is due mainly to utilization of preformed mRNA, the polypeptides synthesized in a wheat germ lysate under the direction of cyst cytoplasmic mRNA were compared with those obtained using polysomal mRNA from developed embryos (1 and 4 hr). The complex pattern of proteins synthesized in vitro was resolved into 70–80 radioactive spots by two-dimensional gel electrophoresis and was shown to be almost identical in unincubated and incubated cysts, except for a few novel spots. Our results do not exclude that early transcription of a few mRNA species could play a role in the activation of metabolic processes which occur when development is resumed.

Distribution of the low molecular weight form of eukaryotic elongation factor 1 in various tissues.

Since it was shown that the low molecular weight form of the eukaryotic polypeptide chain elongation factor 1 (EF-1alpha) is highly unstable but could be stabilized by the addition of 25% (v/v) glycerol to all the buffer solutions (Nagata, S., Iwasaki, K., & Kaziro, Y. (1976) Arch. Biochem, Biophys, 172, 168-177), its distribution in several tissues has been investigated under conditions where it is stabilized. The results obtained indicate that EF-1alpha is present as a predominant species in all the tissues examined, such as pig liver, rat liver, rabbit reticulocytes, and Artemia salina cysts. Furthermore, it is suggested that the high molecular weight form of the elongation factor 1 contains a new elongation factor, EF-1beta, in addition to EF-1alpha, while the low molecular weight form contains little EF-1beta.

Intracellular distribution, sedimentation values and template activity of polyadenylic acid-containing RNA stored in Artemia salina cysts

The post-mitochondrial supernatant of Artemia salina cysts has been fractionated by high speed centrifugation into three components: supernatant, membrane and free ribosomes. Messenger RNA is stored in these fractions as poly(A)-containing particles with sedimentation values ranging from 80 S to 4 S. Poly(A)-containing RNA derived from subcellular fractions has been submitted to sucrose density centrifugation and identified by its capacity to hybridize with 3H-poly(U) and to stimulate protein synthesis in a wheat germ lysate. Poly(A)-containing RNA from membrane and free ribosomes shows a heterogeneous distribution with S values ranging from 28 S to 4 S. Poly(A)-containing RNA from supernatant is found only in the lighter region of the gradient (18-4 S). RNA fractions of different S values can be efficiently translated in a wheat germ lysate with the formation of a characteristic pattern of proteins (8000 to 40,000 mol. wt.).

Cryptic form of mRNA in dormant artemia salina cysts

Dormant Artemia salina cysts are almost devoid of polysomal structures but contain appreciable quantities of mRNA that sediments mainly as a 40S complex in sucrose gradients. The mRNA can be isolated from this complex and efficiently translated in a wheat germ cell-free system, although the 40S complex itself is inactive. During rehydration of the cysts, mRNA becomes increasingly involved in polysomal complexes which can be actively translated in the cell-free system.

The ribosomes of encysted embryos of Artemia salina during cryptobiosis and resumption of development

Summary Commercially availableArtemia salina cysts contain embryos arrested at the gastrula stage. A correlated biochemical and electron optical study was made of the ribosomes from such cysts and from rehydrated cysts during their resumption and completion of embryonic development. 1. Protein synthesis increased slowly and continuously from shortly after hydration throughout the period studied (until more than 50% of the larvae had hatched). 2. Electron micrographs from sectioned cysts and cyst fractions and UV absorption data from cyst fractions showed that the cytoplasm of unincubated cysts was packed with ribosomes, virtually all of which were monomeric and not attached to membranes. 3. During development the proportion of polysomes increased at the expense of the monosomes. However, at all incubation times the great majority of ribosomes existed as free monosomes. 4. The failure of detergent or trypsin treatments to increase incorporation activity significantly in the nonincubated material led to the conclusion that the initiation of protein synthesis inArtemia is due not to the release of preprogrammed particles, but to a gradual programming of free monosomes. 5. That the monosomes constituted a pool of unprogrammed ribosomes was demonstrated by their very low amino acid incorporation activity and by the marked stimulation of this activity by artificial mRNA (polyuridylic acid). These studies, together with electron optical studies of negatively stained preparations of ribosomes and data on the K+ and Mg++ optima of the ribosomes indicate that the structure and conditions for function in these particles apparently are the same as those for ribosomes from most other materials. Therefore, commercially availableArtemia cysts provide a convenient source for unprogrammed ribosomes for studying messenger functions.