DNA-dependent RNA polymerases from Artemia salina. Characterization of a protein factor from developing embryos that stimulates artemia RNA polymerase II.
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Dinucleosidasetetraphosphatase in rat liver and Artemia salina.
A comparative study of an enzymatic activity present in Artemia salina and rat liver which specifically splits dinucleoside tetraphosphates is presented. All the purine and pyrimidine dinucleoside tetraphosphates tested, i.e. diadenosine, diguanosine, dixanthosine and diuridine tetraphosphates, were substrates of both enzymes with similar maximum velocities and Km values, (around 10 muM). The inhibition by nucleotides of the enzyme from the two sources is also similar. Particularly relevant is the strong inhibition caused by nucleoside tetraphosphates which have Ki values in the nanomolar range. The Artemia enzyme has a slightly lower molecular weight (17 500) than the liver enzyme (21 000) and is more resistant to acidic pH. Based on previous findings, the enzyme from Artemia salina was named diguanosinetetraphosphatase (EC 3.6.1.17) by the Enzyme Commission. The results presented in this paper show that the liver and Artemia enzymes are similar, and we propose to name this enzyme as dinucleosidetetraphosphatase or dinucleoside-tetraphosphate nucleotidehydrolase.
Adenine Nucleotides↗
DNA-dependent RNA polymerases from Artemia salina. IV. appearance of nuclear RNA polymerase activity during pre-emergence development of encysted embryos.
Dessicated and encysted gastrulae of the brine shrimp Artemia salina remain metabolically dormant until they are rehydrated. At this time development resumes, culminating in the hatching of free swimming nauplius larvae. The resumption of embryogenesis provides a convenient system for studying biochemical events which accompany development of a eukaryotic organism, and in particular Artemia has proven useful for studies of the transcriptional regulation of gene expression. Encysted gastrulae of Artemia yielded only trace amounts of DNA-dependent RNA polymerase activity when crude nuclear pellets were subjected to sonication at high ionic strength. Furthermore, when crude nuclear pellets from encysted gastrulae and developing nauplius larvae were mixed prior to sonication, subsequent solubilization of proteins from the mixture did not yield RNA polymerase activity; sonication of the pellet from nauplii alone resulted in the solubilization of large quantities of RNA polymerases I and II as we have previously found [1]. RNA polymerases I and II were detectable in sonicates of crude nuclear pellets after 1-h incubation of Artemia cysts in sea water. This presents the possibility that dormant gastrulae of the brine shrimp contain RNA polymerase which is inactive, and that the rapid appearance of nuclear enzymatic activity which accompanies the resumption of development may not require de novo synthesis of the polymerase.
Animals↗
Partial purification and characterization of the proteins from the 40-S ribosomes of Artemia salina and wheat germ.
The proteins were extracted from purified 40-S ribosomes derived from wheat germ and Artemia salina and separated by carboxymethylcellulose ion-exchange chromatography. Approximately four proteins from Artemia and four proteins from wheat germ were separated in a state of high purity. All proteins were identified by co-electrophoresis using a two-dimensional polyacrylamide gel system. A total of 30 unique proteins were found for Artemia and 32 proteins for wheat. The molecular weights of all proteins were estimated by sodium dodecylsulfate gel electrophoresis. Assuming each protein to be present in one copy per 40-S ribosome, the total protein molecular weight was estimated to be 560,000 associated with Artemia 40-S particles and 550,000 associated with wheat germ 40-S ribosomes.
Decapoda↗
Development capacity of artemia cysts and lettuce seeds flown in Cosmos 936 and directly exposed to cosmic rays.
Developmental capacity of Artemia cysts and chromosomal aberration frequency in lettuce seeds, flown aboard Cosmos 936 have been investigated. Biological objects were located inside or outside the spacecraft. Lettuce seeds were stuck on plastic plates and sandwiched in cellulose sheets in order to discriminate the objects hit by the cosmic heavy ions from the ones not hit. The absorbed dose inside the spacecraft was about 650 mrad. Biological objects were located at different levels in the "outside" container; absorbed doses were 1.5 rad for lettuce seeds and 30 rad for Artemia cysts. There was no change in hatch-ability of Artemia cysts located inside or outside the spacecraft when eggs were tested 2-4 months after recovery, but a marked decrease was observed in eggs 9 months after the space flight. Survival of larvae and adults was normal in "inside" eggs, but decreased in "outside" eggs. Space flight also resulted in a higher frequency of single chromosomal aberrations in cells developed from "inside and outside", hit and non-hit seeds. This highest percentage of multiple chromosomal aberrations occurred in seeds hit by the heavy ions.
Animals↗
[Influence of various physical factors on the developmental capacities of the ovum of Artemia salina].
Artemia salina dry eggs exhibit a great resistance to different physical factors: acceleration and vibration, low temperature, high vacuum and magnetic fields. Vibration test, alone or combined with acceleration test decreases the Artemia salina egg developmental capacity. Nevertheless, the differences are small and much lower than those observed in previous space experiments. The viability of Artemia eggs is not impaired by low temperature, high vacuum exposure and by high magnetic fields (15, 25 and 150 Koersted) or by earth magnetic field shielding.
Acceleration↗
Neuronal connectivity patterns in the compound eyes of Artemia salina and Daphnia magna (Crustacea: Branchiopoda).
The neuronal types and patterns in the visual system of the species Artemia salina and Daphina magna have been studied with the Golgi method and electron microscopy. The lamina contains five classes of neurons: photoreceptor axons, monopolar, centrifugal, tangential and amacrine neurons. The terminals of the receptor axons are distributed in two (A. salina) or three (D. magna) layers. The dilated terminals have an extensive and wide array of fine branches. One axon from each ommatidium bypasses the lamina and terminates in the medula in A. salina. A. salina has four types of monopolar neurons, two of which are stratified, whereas in D. magna only two types are found, one of which is bistratified. Tangential T-neurons connect the lamina with the protocerebrum. D. magna has in addition one tangential T-neuron connecting both the lamina and the medulla with the protocerebrum. In both species monopolar-type centrifugal neurons connect the medulla and the lamina, whereas that of A. salina has a wide laminar distribution. Both species also have amacrine cells in the lamina. The medulla contains, besides those shared with the lamina, transmedullary neurons (two types in A. salina), amacrine cells and neurons originating in the protocerebrum. "Cartridge"-type synaptic compartments are lacking in the investigated species, although a periodic arrangement is discernible in the distal portion of the lamina of A. salina. The receptors from three types of specialized contacts in Artemia, one of which involves a dyad. D. magna has only one-to-one synapses. Neurosecretory fibres are absent in A. salina.
Animals↗
Identification and characterization of a 19-S complex containing a 27 000-Mr protein in Artemia salina.
The cytoplasm of the cryptobiotic Artemia salina gastrula contains a large quantity of a unique 19-S complex. This particle is a specific aggregated form of a 27 000-Mr protein, having a molecular weight of 10(6) and an apparent buoyant density of 1.25 -- 1.26 g/cm3 in sucrose and 1.31 g/cm3 in CsCl. The relative quantity of this 19-S complex decreases significantly with respect to 80-S monoribosomes during the postgastrula development. Biochemical and immunological studies indicate that the 27 000-Mr protein is one of the RNA-binding proteins [Ovchinnikov et al., FEBS Lett. 88, 21 -- 26 (1978)] but is absent in the protein components associated with poly(A)-containing ribonucleoprotein complexes. The possibility is also suggested that the 27 000-Mr protein and Artemia elongation factor eEF-Ts might be related to each other on the basis of amino acid composition and immunological cross-reactivity.
Alkylation↗
Independent temporal expression of two N-substituted aminoacyl-tRNA hydrolases during the development of Artemia salina.
Encysted embryos of the crustacean Artemia salina contain an enzymatic activity which hydrolyzes N-acetylphenylalanyl-tRNA to N-acetylphenylalanine and tRNA. The enzyme apparently does not hydrolyze other free or N-substituted aminoacyl-tRNAs. The levels of this enzyme do not significantly change during embryonic and early larval development. In contrast, an unspecific hydrolase active on several N-substituted aminoacyl-tRNAs is practically absent in the encysted embryos and during embryogenesis and appears abruptly during larval development. The independent temporal expression of these two hydrolases during Artemia salina differentiation makes this organism siuitable for the study of the physiological role of these enzymes.
Animals↗
Short-term effects on Artemia salina of aponin and Gomphosphaeria aponina in unialgal cultures and in mixed cultures with gymnodinium breve.
Previous investigations showed that the natural marine substance aponin, produced by the blue-gree alga Gomphosphaeria sponina, was cytolytic towards Florida's red tide organism, Gymnodinium breve. As part of a study of the aponin-alga biological interactions, the effects of unialgal (G. aponina) and mixed cultures (G. aponina + G. breve) on the viability of artemia salina were investigated. Two contrasting effects were observed in mixed cultures: survival of A. salina was promoted in low G. aponina populations, while enhanced toxicity of G. breve to A. salina occurred at higher culture populations. Unialgal G. aponina cultures exerted no adverse effects on A. salina. The apparent protective effect is thought to result from the observed change in G. breve morphology (motile to sessile); toxicity was the result of enhanced toxin release by cytolyzed G. breve cells. In dose-response studies, aponin exhibited no adverse effect on A. salina at concentrations (1 unit) that were deleterious to G. breve. However, at higher applied levels (4--6 units), mortality was substantial (greater than 70%) after 48 hr of incubation. Probit analysis yielded an apparent LD50 of 2.3 units, where 1 unit was that amount required to cytolyze 50% of the G. breve cells (2000 cells/ml) after 20 hr of incubation.
Animals↗
Regular, rodlike, macromolecular structures in Artemia salina.
Artemia salina of different origins and in different developmental stages contains regular, rodlike, macromolecular structures. The particles were visualized by electron microscopy after negative staining. They can be purified from the postmitochondrial supernatant by sucrose gradient centrifugation in the presence of EDTA. Their size distribution has been measured from electron micrographs. The particles are probably nucleoprotein complexes.
Animals↗
Esterase and malate dehydrogenase isozyme polymorphisms in 15 Artemia populations.
1. Starch gel electrophoresis of adult brine shrimps from 15 populations revealed little intrapopulation polymorphism in NAD-dependent malate dehydrogenase (MDH) isozymes or in the two fastest esterases (demonstrated with alpha-naphthyl propionate as substrate). 2. Interpopulation differences could be summarized as three different electrophoresis band patterns for the five- to seven-banded MDH isozymes and another three patterns for the two fastest esterases. 3. These differences in electrophoresis patterns divide the 15 Artemia populations into four categories (each containing one to seven populations) which may be distinguished by isozyme content and which are congruent with categories established by the criterion of reproductive isolation in an earlier study.
Animals↗
Effects of 645 MeV and 9.2 GeV protons on Artemia eggs.
Developmental capacities of Artemia eggs have been studied after exposure to 645 MeV or 9.2 GeV protons. Effects of proton irradiation were studied in comparison with 60Co gamma ray irradiation, endpoints being emergence, hatching and 4-5 day old live nauplii percentages. Effectiveness of 645 MeV protons is greater than that of 9.2 GeV protons. R.b.e. values calculated for nauplius survival is 2.3 for 645 MeV protons and 1.5 for 9.2 GeV protons. These results can be taken into account in radiation hazard estimation during space flights.
Animals↗
Chromatin Landscape Is Associated With Sex-Biased Expression and Drosophila-Like Dosage Compensation of the Z Chromosome in Artemia franciscana.
The males and females of the brine shrimp Artemia franciscana are highly dimorphic, and this dimorphism is associated with substantial sex-biased gene expression in heads and gonads. How these sex-specific patterns of expression are regulated at the molecular level is unknown. A. franciscana also has differentiated ZW sex chromosomes, with complete dosage compensation, but the molecular mechanism through which compensation is achieved is unknown. Here, we conducted CUT&TAG assays targeting 7 post-translational histone modifications (H3K27me3, H3K9me2, H3K9me3, H3K36me3, H3K27ac, H3K4me3, and H4K16ac) in heads and gonads of A. franciscana, allowing us to divide the genome into 12 chromatin states. We further defined functional chromatin signatures for all genes, which were correlated with transcript level abundances. Differences in the occupancy of the profiled epigenetic marks between sexes were associated with differential gene expression between males and females. Finally, we found a significant enrichment of the permissive H4K16ac histone mark in the Z-specific region in both tissues of females but not males, supporting the role of this histone mark in mediating dosage compensation of the Z chromosome.
Animals↗
Non-polyadenylated 22 s ribonucleoprotein particle is insensitive to translational inhibitor RNA of cryptobiotic gastrulae of Artemia salina.
A free cytoplasmic 22 S ribonucleoprotein particle exhibiting a major template activity in rabbit reticulocyte system has been identified in the cryptobiotic gastrulae of Artemia salina. This particle contains non-polyadenylated 9 S messenger RNA which codes primarily for a non-histone basic protein with an apparent molecular weight of 26 000 daltons. We have previously demonstrated the presence of a translational inhibitor RNA which is apparently responsible for transforming polyadenylated messenger (Slegers et al., FEBS Letters 80, 390-394, 1977). This inhibitor RNA was found to be completely ineffective on the template activity of non-polyadenylated 22 S messenger ribonucleoprotein, confirming the specificity of this regulatory RNA for polyadenylate sequences.
Animals↗
Protein synthesis in brine shrimp embryos. Dormant and developing embryos of Artemia salina contain equivalent amounts of chain initiation factors 2.
Dormant and developing embryos of Artemia salina contain equivalent amounts of eIF-2, the eukaryotic initiation factor which forms a ternary complex with GTP and Met-tRNAf. The factor was purified from 0.5 M NH4Cl ribosomal washes by (NH4)2SO4 fractionation, followed by chromatography on heparin-Sepharose, DEAE-cellulose, hydroxyapatite and phosphocellulose. Purified preparations from dormant and developing embryos have similar specific activities and nucleotide requirements. The mobility of both proteins in dodecylsulfate gel electrophoresis is indistinguishable, and each contains three major polypeptide chains of molecular weight 52 000, 45 000 and 42 000. Both proteins are also immunologically identical, and each stimulates amino acid incorporation in a cell-free system of protein synthesis. The binding of [35S]Met-tRNAf to 40-S ribosomal subunits is catalyzed by eIF-2 isolated from dormant or developing embryos and is dependent upon GPT and AUG. Binding of [35S]Met-tRNAf to 40-S ribosomal subunits, and ternary complex formation with eIF-2, GTP, and [35S]Met-tRNAf is stimulated 2--3-fold by a factor present in the 0.5 M NH4Cl ribosomal wash and which elutes from DEAE-cellulose at 50 mM KCl. This protein does not exhibit GTP-dependent binding of [35S]Met-tRNAf. Binding of GDP and GTP was investigated with purified eIF-2 from developing embryos. The factor forms a binary complex with GDP or GTP, and eIF-2-bound [3H]GDP exchanges very slowly with free nucleotides. Our results suggest that eIF-2 does not limit resumption of embryo development following encystment, nor does it limit mRNA translation in extracts from dormant embryos.
Animals↗
Antennular sensilla of the brine shrimp, Artemia salina.
1. Scanning electron microscopy was used to characterize the external morphology of setae found on the antennules of adults and nauplii of the brine shrimp, Artemia salina (L.). The permeability of the antennular setae was studied by means of Slifer's crystal violet method. 2. Each antennule of an adult brine shrimp possessed a terminal cluster of sensory setae. Within a cluster there were two morphologically distinct kinds of sensilla, here designated type 1 and type 2. Three type 1 sensilla were observed on every antennule examined. The number of type 2 sensilla per antennule was usually four or five. 3. Type 1 sensilla of adults were 43 to 80 micrometer long and simple in external morphology. They were widest at the base, decreased in diameter gradually, and terminated as a finely tapered tip. No pores were resolved by scanning electron microscopy. 4. Type 2 sensilla of adults were shorter (shaft length, 12 to 23 micrometer) and displayed a single pore at the tip (average pore diameter, 0.4 micrometer). In thin section they were seen to possess a distinctive articular specialization of the cuticle at the base of the seta. 5. Dye penetration experiments indicated that type 2 sensilla were permeable to aqueous crystal violet, whereas type 1 sensilla were not. 6. The antennular setae of nauplii resembled type 1 sensilla in general shape, in being impermeable to crystal violet, and in lacking a terminal pore and basal articular specialization. Moreover, a total of three setae was normally present on each naupliar antennule, and the same number of type 1 sensilla was found on each adult antennule examined. If the three naupliar setae represent a developmental stage in the formation of three adult sensilla, available observations suggest that the larval setae are developmentally related to type 1, rather than to type 2 adult sensilla.
Animals↗
[Effect of cytochalasin B on the segmentation divisions of Artemia salina ova].
In the cleaving egg of Artemia salina, cytochalasin B not only inhibits cytodieresis, but interferes also with karyokinesis, while the division of the cell centres seems to progress normally.
Animals↗