Molecular cloning and characterization of ribosomal RNA genes from a blue-green alga, Anacystis nidulans

Summary Two PstI fragments (5.3x10⁶ and 4.3x10⁶ daltons) coding for Anacystis nidulans rRNA genes were cloned. The cloned rDNAs were characterized by restriction endonuclease mapping, DNA-RNA hybridization analysis and the R-loop technique. The results indicated that both fragments contained 16S, 23S and 5S rRNA genes in this order. A tRNA gene(s) was detected in the spacer region between 16S and 23S rRNA genes. The organization of A. nidulans rRNA genes resembles those of E. coli and of Euglena chloroplasts rather than those of higher plant chloroplasts.     

The complete nucleotide sequence of a 16S ribosomal RNA gene from a blue-green alga, Anacystis nidulans

The complete nucleotide sequence of a 16S ribosomal RNA gene from a blue-green alga, Anacystis nidulans, has been determined. Its coding region is estimated to be 1,487 base pairs long, which is nearly identical to those reported for chloroplast 16S rRNA genes and is about 4% shorter than that of the Escherichia coli gene. The 16S rRNA sequence of A. nidulans has 83% homology with that of tobacco chloroplast and 74% homology with that of E. coli. Possible stem and loop structures of A. nidulans 16S rRNA sequences resemble more closely those of chloroplast 16S rRNAs than those of E. coli 16S rRNA. These observations support the endosymbiotic theory of chloroplast origin.     

Isolation and initial characterization of a uracil auxotroph of the blue-green alga Anacystis nidulans.

A uracil-requiring auxotroph of Anacystis nidulans was isolated after treatment with N-methyl-N'-nitrosoguanidine. Neither precursors in the de novo pyrimidine pathway nor compounds of "salvage" or degradative pathways could replace the uracil requirement. The reversion frequency for mutation to a nonuracil requirement for growth was 2.0 times 10(-8). The calculated average rate of uracil utilization was 1.1 times 10(-17) mol of uracil per unit cell mass/h. The amount of uracil required for the synthesis of a unit cell mass was 3.8 times 10(-17) mol of uracil.     

The characterization of the RNAs and aminoacyl-tRNA synthetases of the blue-green alga, Anacystis nidulans

The tRNA and aminoacyl-tRNA synthetases of the blue-green alga, Anacystis nidulans have been isolated and studied. The distribution of some algal tRNA species on BD-cellulose chromatography has been determined. One tRNA^Met species has been isolated in 80% purity by a single chromatography on a BD-cellulose column developed with a modified salt gradient. The number of different tRNA isoacceptors for Met, Ser, and Leu has been ascertained by RPC-5 chromatography. The recognition of algal tRNAs by the homologous algal synthetase preparation as well as the heterologous Escherichia coli preparation was studied by the aminoacylation tests. Since all of the isoaccepting species of the tRNAs tested behaved almost identically in presence of the two enzyme preparations, a conservation of the recognition site during the evolutionary divergence of bacteria and algae is strongly suggested.     

Evidence for genetic transformation in blue-green alga Anacystis nidulans

Summary Evidence has been presented that blue-green alga Anacystic nidulans can undergo genetic transformation. DNA from erythromycin-, streptomycin-resistant of filamentous strains has been found to transform appropriate markers to a wild type or some other recipients. Favourable conditions for transformation have been described with respect to the revealing of transformants, the concentration of DNA and the competence of cells.     

Fluorescence from sensitizing phycobilin chromophores in the blue-green alga Anacystis nidulans

Regeneration of the pigment system of Anacystis nidulans was studied following nitrate starvation. Three new, distinct fluorescence bands, at 596, 615 and 636 nm attributed to sensitizing phycobilin chromophores were detected. They each possess a separate excitation band at 425, 395 and 410 nm, respectively.     

Resonance Raman spectra of phycocyanin, allophycocyanin and phycobilisomes from blue-green alga Anacystis nidulans

Resonance Raman spectra of native C-phycocyanin, allophycocyanin and whole, intact phycobilisomes from the blue-green alga Anacystis nidulans (Synechococcus 6301) are reported. A tentative assignment for the more prominent resonance Raman bands is suggested. The possibly sensitive regions for inter-chromophore interactions in the case of phycobilisomes are also discussed.     

Molecular cloning and characterization of ribosomal RNA genes from the brine shrimp

A library of genomic DNA from the brine shrimp, Artemia, has been constructed with the Charon 4A phage vector, utilizing EcoRI passenger fragments. Screening this library with purified Xenopus laevis cloned rDNA genes has resulted in the identification and plaque purification of a recombinant containing a complete Artemia (18 S + 26 S) rDNA repeat unit. A physical map derived from the analysis of restriction endonuclease digests of the repeat unit, which measures 13.9 kilobase pairs, is similar to the map derived from genomic DNA. In common with several other species, the 26 S rRNA gene terminates with a HindIII recognition site.     

Fluorescence from sensitizing phycobilin chromophores in the blue-green alga Anacystis nidulans.

Regeneration of the pigment system of Anacystis nidulans was studied following nitrate starvation. Three new, distinct fluorescence bands, at 596, 615 and 636 nm attributed to sensitizing phycobilin chromophores were detected. They each possess a separate excitation band at 425, 395 and 410 nm, respectively.     

Mutations arising during transformation in the blue-green alga Anacystis nidulans

Summary Genetic transformation experiments have been performed in Anacystis nidulans using donor material from two sources, namely chemically extracted DNA and extracellular nucleic acids. A high proportion of the transformants became mutant at sites which were wild type in both parental strains. Linkage was less extensive in transformation mediated by chemically extracted DNA, and this increased frequency of recombination was associated with enhanced mutation frequencies. The frequencies of recombination and mutation were varied to the same extent by changing the DNA concentration, and both processes were prevented by pretreatment of donor DNA with DNase. Mutational events are, therefore, closely associated with recombination in A. nidulans.     

Synchronous growth and genome replication in the blue-green alga Anacystis nidulans

Summary Following the induction of synchronous growth of Anacystis nidulans by light and CO₂ deprivation, cell mass and RNA and DNA content during two cell cycles were measured. Both RNA and DNA synthesis were discontinuous and marked variation in survival to ultraviolet light was related to the state of replication. A model is presented which accounts for the proportion of cells (66%) induced into synchronous genome replication which is also related to the state of replication at the onset of pre-synchrony treatment.     

Particle aggregation in photosynthetic membranes of the blue-green alga Anacystis nidulans

Freeze-fracture electron microscopy demonstrates that in photosynthetic membranes of the blue-green alga Anacystis nidulans quenched from a temperature below growth temperature, areas devoid of membrane particles occur. We suggest that this phenomenon is related to phase transitions in the photosynthetic membrane.