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Bianca Colonna Maria Bernardini Gioacchino Micheli Francesco Maimone Mauro Nicoletti Mariassunta Casalino 《Plasmid》1988,20(3):221-231
Tn1935, a 23.5-kb transposon mediating resistance to ampicillin, kanamycin, mercury, spectinomycin, and sulfonamide was isolated from pZM3, an IncFIme virulence plasmid from Salmonella wien. Tn1935 possesses the entire sequence of Tn21 and contains two additional DNA segments of 0.95 and 2.7 kb carrying the ampicillin and kanamycin resistance genes, respectively. The latter is part of a composite element since it is flanked by two IS15-like insertion sequences (IS1936) in direct orientation. IS1936 is about 800 bp long and is closely related to IS15 delta, IS26, IS46, IS140, and IS176. Functional analysis of IS1936-mediated cointegrates shows that both insertion sequences are active and able to form cointegrates at the same frequency. Resolution of the cointegrates requires the presence of the host Rec system. The presence of the composite IS1936-element within Tn1935 supports the hypothesis that multidrug resistance transposons evolved by insertion of antibiotic determinants which are themselves transposable. 相似文献
3.
V Micheli A Taddeo A L Vanni L Pecciarini M Massone M G Ricci 《Bollettino della Società italiana di biologia sperimentale》1984,60(3):665-671
Differences in erythrocyte distribution on Ficoll-Sodium Metrizoate discontinuous density gradient were evaluated between adult males and females. Testosterone and androstenedione plasma levels were tested in males, oestradiol, progesterone and prolactin in both males and females. Female group showed a much higher proportion of lighter younger erythrocytes than males, while males showed higher proportion of denser older cells. Positive correlation was found between young cell percent and oestradiol level, both in males and females, but no correlation was found with androgen hormones. 相似文献
4.
Four diploid and three phylogenetically tetraploid Cyprinidae (Ostariophysi) have been characterized as for nuclear DNA content, modal chromosome number and DNA reassociation kinetics (hydroxyapatite chromatography). Among the diploid species nuclear DNA content (10(-12) g DNA/2C) was 1.62 for Tinca tinca, 1.87 for Scardinius erythrophthalmus, 2.53 for Leuciscus cephalus and 2.75 for Alburnus alburnus, while the phylogenetically tetraploid species Carassius auratus, Barbus barbus and Cyprinus carpio attained 3.40, 3.66 and 3.80 respectively. Modal chromosome number was 2n = 48-50 for diploid individuals and 2n = 100-104 for phylogenetically tetraploid ones. In all the species 5--8% of the genome is represented by highly repetitive and foldback DNA. In DNA reassociation kinetics of phylogenetically tetraploid Cyprinidae a distinct plateau separates an intermediate reassociating sequence fraction (about 22% of the genome; with average repetition frequencies between 1,000 and 1,400) from a slow reassociating one (unique DNA; about 72% of the genome). These two genome fractions are not clearly distinguishable from each other in Cot curves of the diploid Cyprinidae, where a similar plateau is not evident. Since simple ploidy changes are not expected to affect DNA reassociation kinetics we suggest a different evolution in the genome organization of the two ploidy groups. Some possible hypotheses are discussed. 相似文献
5.
The effect of variation in the concentration of inorganic phosphate and of the pyridine precursors nicotinamide (NAm) and nicotinic acid (NA) on pyridine nucleotide synthesis was studied using intact human erythrocytes. A wide range of incubation times was employed. The results showed that under physiological conditions the rate of synthesis of NAD from NAm exceeded that from NA twofold, while the reverse situation pertained at higher and unphysiological substrate levels. The two pathways had different regulation points. For NAm the rate-limiting factor was the initial step, namely its conversion into the mononucleotide, while for NA it lay at the second step, conversion of NA mononucleotide (NAMN) to its adenine dinucleotide. At physiological substrate levels the uptake of NA and conversion to NAMN were rapid, while the uptake and conversion of NAm were time dependent. This process was stimulated significantly by inorganic phosphate only for NAm. These results indicate that while NA is the predominant precursor of human erythrocyte NAD at high (unphysiological) substrate and phosphate levels, NAm is more efficient as an NAD precursor under physiological conditions, suggesting an important and hitherto unrecognized role for nicotinamide in NAD synthesis in vivo. 相似文献
6.
Evidence for a quadruplex structure in the polymorphic hs1.2 enhancer of the immunoglobulin heavy chain 3’ regulatory regions and its conservation in mammals 下载免费PDF全文
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Irene C Maciariello C Micheli G Theis JF Newlon CS Fabiani L 《Molecular genetics and genomics : MGG》2007,277(3):287-299
Eukaryotic chromosomal DNA replication is initiated by a highly conserved set of proteins that interact with cis-acting elements on chromosomes called replicators. Despite the conservation of replication initiation proteins, replicator
sequences show little similarity from species to species in the small number of organisms that have been examined. Examination
of replicators in other species is likely to reveal common features of replicators. We have examined a Kluyeromyces lactis replicator, KARS12, that functions as origin of DNA replication on plasmids and in the chromosome. It contains a 50-bp region with similarity
to two other K. lactis replicators, KARS101 and the pKD1 replication origin. Replacement of the 50-bp sequence with an EcoRI site completely abrogated the ability of KARS12 to support plasmid and chromosomal DNA replication origin activity, demonstrating this sequence is a common feature of K. lactis replicators and is essential for function, possibly as the initiator protein binding site. Additional sequences up to 1 kb
in length are required for efficient KARS12 function. Within these sequences are a binding site for a global regulator, Abf1p, and a region of bent DNA, both of which
contribute to the activity of KARS12. These elements may facilitate protein binding, protein/protein interaction and/or nucleosome positioning as has been proposed
for other eukaryotic origins of DNA replication. 相似文献
9.
Lucarini Elena Micheli Laura Di Cesare Mannelli Lorenzo Ghelardini Carla 《Phytochemistry Reviews》2022,21(2):647-665
Phytochemistry Reviews - Investigation into glucosinolates (GLs) therapeutic effects boasts a long history, which began with the evidence that their hydrolysis-derived isothiocyanates (ITCs) could... 相似文献
10.
Goldberg E. Grace Raab Ted K. Desalles Paul Briggs Amy A. Dunbar Robert B. Millero Frank J. Woosley Ryan J. Young Hillary S. Micheli Fiorenza Mccauley Douglas J. 《Coral reefs (Online)》2019,38(2):347-357
Coral Reefs - Bolbometopon muricatum are ecologically unique mega-consumers in coral reef ecosystems. They primarily divide their dietary intake between living scleractinian corals and coral rock,... 相似文献