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D F de Almeida

Publications and source records attributed to D F de Almeida.

27 records · Page 2Linked to original sources
PubMed1978

Morphological changes of Herpetomonas samuelpessoai.

The promastigote form of Herpetomonas samuelpessoai is modified into a paramastigote-like form during incubation at 28 C in high osmolarity complex media obtained through the addition of various concentrations of KCl, NaCl or glycerol. Morphological changes accompanying this modification include an increase in cell volume during exponential growth, a deep invagination of the cell membrane at the bottom of the flagellar pocket into the cytoplasm, and a prominent bulging at the emergence of the flagellum.

Animals↗
PubMed1977

Timing of cold-sensitive stages in the cell division cycle of Escherichia coli K12.

Synchornous cultures obtained by selection at division were used to investigate the occurrence of cold-sensitive stages during the division cycle of Escherichia coli (lambdaind--). There are two such stages within the 50 min cycle: one (early) at 10 to 20 min and the other (late) at 40 to 45 min. Similar results were obtained from calculations based both on the age frequency distribution of cells in exponential growth and on the size of the populations which accumulate as a result of a single change of temperature. Times of about 17 and 44 min were found for the early and the late stages, respectively. It is concluded that the two-step doubling of E. coli K12 cultures synchronized by a single cold shock is due to two cold-sensitive stages in the division cycle.

Cell Division↗
PubMedDate not supplied

Characterization of enterotoxigenic Escherichia coli by random amplification of polymorphic DNA.

Two enterotoxigenic Escherichia coli (ETEC) strains (H10407 and 4011-1) were characterized by random amplification of polymorphic DNA (RAPD) profiles using 10-mer oligonucleotides with diverse GC content. All tested primers yielded arrays of amplified DNA products ranging in size from 200 to 3000 bp. The effects of annealing temperature, template concentration and GC content of the primers were evaluated and an optimal reaction procedure was established. Application of the RAPD analysis to ten ETEC strains belonging to five different serotypes showed that strains of the same serotype shared identical or almost identical band profiles, suggesting a similar genetic composition. The use of RAPD profiles as a tool in epidemiological analysis of ETEC is discussed.

Child↗
PubMedDate not supplied

[Genetic analysis of lactose-fermenting Salmonella typhimurium isolated in Rio de Janeiro].

Lactose fermenting Salmonella typhimurium are endemic in São Paulo, but not in Rio de Janeiro Two isolations are described from the latter city. These Rio de Janeiro strains have a plasmid of 7.4 megadaltons. These plasmids were not auto-transferable, were thermostable and were not eliminated by acridine orange. One of these strains arose from a plasmid that had the lactose operon repressed, leading us to speculate about the evolution of the lactose fermenting character in Brazilian Salmonella.

Brazil↗