(n.) A piece of DNA, usually circular, functioning as part of the genetic material of a cell, not integrated with the chromosome and replicating independently of the chromosome, but transferred, like the chromosome, to subsequent generations. In bacteria, plasmids often carry the genes for antibiotic resistance; they are exploited in genetic engineering as the vehicles for introduction of extraneous DNA into cells, to alter the genetic makeup of the cell. The cells thus altered may produce desirable proteins which are extracted and used; in the case of genetically altered plant cells, the altered cells may grow into complete plants with changed properties, as for example, increased resistance to disease.
Example Sentences:
(1) When micF was cloned into a high-copy-number plasmid it repressed ompF gene expression, whereas when cloned into a low-copy-number plasmid it did not.
(2) These eight large plasmids had indistinguishable EcoRI restriction patterns.
(3) The combined analysis of pathogenesis and genetics associated with the salmonella virulence plasmids may identify new systems of bacterial virulence and the genetic basis for this virulence.
(4) On removal of selective pressure, the His+ phenotype was lost more readily than the Ura+ Trp+ markers, with a corresponding decrease in plasmid copy number.
(5) The data on mapping the episomal plasmid integration sites in yeast chromosomes I, III, IV, V, VII, XV are presented.
(6) A beta-adrenergic receptor cDNA cloned into a eukaryotic expression vector reliably induces high levels of beta-adrenergic receptor expression in 2-12% of COS cell colonies transfected with this plasmid after experimental conditions are optimized.
(7) By hybridization studies, three plasmids in two forms (open circular and supercoiled) were detected in the strain A24.
(8) It should be noted that about a half of the plasmids (11 out of 21) belonged to the incompatibility group P-7 which up to the present time was conditional, since was represented by a single plasmid Rms 148.
(9) Since the plasmid-cured strains did not contain DNA sequences homologous to plasmid DNA, the gene for the free-inclusion protein must be encoded in the chromosome.
(10) A total of 28 cell lines were selected for Geneticin - resistance and inoculated into the footpads of syngeneic animals following co-transfection with pSV2neo and genomic DNA, or transfection with plasmid constructs containing neo and the activated Ha-ras oncogene.
(11) Since resistance is mainly mediated by R plasmids, we undertook to investigate the characteristics of R plasmid-determined beta-lactamase in 6 Gram-negative rods.
(12) The 6.6-kb DNA Bam HI fragment containing the resistance gene was cloned with the plasmid vector pIJ699.
(13) Only one E. coli strain, containing two plasmids that encode endo-pectate lyases, exo-pectate lyase, and endo-polygalacturonase, caused limited maceration.
(14) Plasmids containing the inverted repeat alone bound ER, though less efficiently than did plasmids containing the entire sequence.
(15) The plasmid pMucAMucB, constructed from the Haemophilus influenzae vector pDM2, and a similar plasmid, constructed from pBR322, increased the survival after UV irradiation of Escherichia coli AB1157 with the umu-36 mutation and also caused UV-induced mutation in the E. coli strain.
(16) The 105 000 X g supernatant of the reaction mixture, which contained more than 85% of the thiobarbituric acid-reactive substances, did not inactivate the plasmid DNA.
(17) The remainder of the plasmid appeared to be associated with five positioned nucleosomes and two nonnucleosomal, partially protected regions on the bulk of the molecules.
(18) The fifth plasmid contains sequences which are repeated in the yeast genome, but it is not known whether any or all of the ribosomal protein gene on this clone contains repetitive DNA.
(19) Plasmid profiling was used to distinguish strains of lactobacilli inhabiting the digestive tract of piglets and the feces of sows.
(20) One mutant, BS260, was completely noninvasive on HeLa cells and mapped to a region on the 220-kb virulence plasmid in which we had previously localized several avirulent temperature-regulated operon fusions (A.E.
Plastid
Definition:
(n.) Alt. of Plastide
Example Sentences:
(1) Steady state levels of chloroplast mRNA encoding the core PSII polypeptides remain nearly constant in the light or the dark and are not affected by the developmental stage of the plastid.
(2) These results are discussed in terms of the role of contaminants in the observed synthesis, the "normalcy" of Acetabularia chloroplasts, the synthetic pathways for amino acids in plastids, and the implications of these observations for cell compartmentation and chloroplast autonomy.
(3) Chaperonins (Cpn) are implicated in the folding and assembly of multimeric proteins in plastids and mitochondria of eukaryotes and in prokaryotes.
(4) The N-terminal end of the coding region shows features typical of a stromal-targeting plastid-transit peptide.
(5) However, identification of the methionine bristle domain suggests that chloroplast HSPs also have unique functions or substrates within the special environment of the chloroplast or other plastids.
(6) An in vitro translation system using lysed etioplasts was developed to test if the accumulation of plastid-encoded chlorophyll a apoproteins is dependent on the de novo synthesis of chlorophyll a.
(7) Sperm cells within pollen grains and pollen tubes of alfalfa (Medicago sativa L.) were observed at the ultrastructural level, and their plastid DNA was detected by DAPI (4,6-diamidino-2-phenylindole) staining.
(8) Short pulses of red light induce in etiolated barley seedlings an enhanced synthesis of plastidic benzoquinones and vitamin K1, which can be reverted by subsequent irradiation with short pulses of far-red.
(9) Thus, homologies in the rbcS gene indicate a close phylogenetic relationship between rhodoplasts and the plastids of Chromophyta.
(10) The plastid thylakoid polypeptide patterns obtained from various dark-grown mutants, making large but abnormal chloroplasts, show a correlation between the amount of chlorophyll formed and the amount of a plastid thylakoid polypeptide thought to be associated wtth one of the pigment-protein light-harvesting complexes.
(11) An imperfect association of plastid replication and nucleic acid synthesis is suggested by the lack of stimulation of DNA synthesis by light during plastid replication in the first 8 h of incubation.
(12) Duplicated genes for both the plastid and cytosolic isozymes were localized to genomic regions that possess numerous other redundant sequences.
(13) In contrast, in plastids of dark-grown plants, the 15- to 25-kDa translation intermediates were converted into a 23-kDa polypeptide previously suggested to be a proteolytic product of D1.
(14) All plastid thylakoid bands seen in dark-growing wild-type cells and in mutant W3BUL in which plastid DNA is undetectable, are observed to increase in amount during plastid development.
(15) Pulse-labeling assays revealed a population of short-lived proteins in plastids of dark-grown plants.
(16) The difference in rates of amino acid incorporation between etioplasts and chloroplasts is correlated with the state of development of the plastids.
(17) Distinctive features include a complex cytoskeleton which defines the cell organization and interconnects cell components; trichocysts which resemble those in other cryptoprotists; and two non-photosynthetic plastids.
(18) Somatic hybridization of plants by fusions of protoplasts or by uptake of nuclei and other organelles (plastids, mitochondria) or pure nucleic acids is another useful method.
(19) The alga, normally tentoxin-resistant, was rendered tentoxin-sensitive by mutagenesis of its plastid atpB gene at codon 83.
(20) This clearly indicated a close phylogenetic relationship between the plastids of Rhodophyta and Chromophyta which seem to have evolved independently from the chloroplasts (polyphyletic origin).