Genetic characterization of adenovirus strains isolated from patients with acute conjunctivitis in the city of São Paulo, Brazil.

Genome analysis was carried out on adenovirus strains isolated from patients with acute follicular conjunctivitis in the city of São Paulo, Brazil. Eighteen conjunctival scrapings, collected between December 1993 and March 1994, were analyzed by two methods: a combination of polymerase chain reaction with restriction fragment length polymorphism and viral DNA restriction analysis, carried out using 10 restriction endonucleases: BamHI, BglI, BglII, HindIII, KpnI, SacI, SalI, SmaI, XbaI, and XhoI. Among 11 adenovirus detected by cell culture isolation, nine were Ad8, and two were Ad7. By restriction analysis the Ad8 isolates were typed as two new variants-Ad8/D11 (seven of nine samples) and Ad8/D12 (two of nine samples). Ad7 isolates were identified as a subtype of the widespread genome type Ad7b and the virulent type Ad7h, a predominant genome type circulating in Argentina, Chile, and Uruguay but absent in Brazil until 1991.

The comparative DNA content of 19 species of placental mammals, reptiles, and birds

With the Deeley integrating microdensitometer incorporating a crushing condenser, the Feulgen stain content of 19 species of placental mammals, birds and reptiles was determined. Arranging the species as a series of pairs, comparative DNA values were obtained which are by and large in good agreement with previous results obtained from two-dimensional measurements of chromosome area. 1. Placental mammals as a whole constitute one uniform group with regard to total genetic content. There was no significant difference in DNA values between man, the horse, the dog, the golden hamster and the mouse. The creeping vole with the extremely low diploid chromosome number had a DNA value 10 per cent lower, regarded as a reflection of the loss of centromeric heterochromatin which accompanied a drastic decrease in diploid chromosome number. 2. Four representatives of the class Aves also constitute one uniform group with the DNA value 44 to 59 per cent of that of placental mammals. 3. The class Reptilia falls into two fairly discrete groups. Six representatives of the order Squamata have a DNA value 60 to 67 per cent of that for placental mammals, while three species representing the order Crocodylia and Chelonia have 80 to 89 per cent.

Close karyological kinship between the reptilian suborder serpentes and the class aves

In contrast to the situation found in two classes of warm-blooded vertebrates, mammals and birds, the class Reptilia is not uniform with regard to total genetic content; rather, it contains two distinct categories. The close cytological kinship between snakes and birds was revealed. Both are almost identical in total genetic content, which is about 50 per cent that of placental mammals. Both have microchromosomes, as well as Z-chromosomes very similar in absolute size, comprising nearly 10 per cent of the homogametic haploid (AZ) set. This leads to the implication that snakes and birds originated from the same lineage, and that their Z-chromosomes have not changed substantially since the Jurassic period of the Mesozoic era, about 180 million years ago. Within the reptilian suborder Serpentes, the step-by-step differentiation from the primitive ZW pair to the grossly heteromorphic ZW pair could be observed. In the ancient family Boidae, the sex chromosomes were still homomorphic to each other. In the family Colubridae, the beginning of heteromorphism was manifested in two ways. In some species, a pericentric inversion on the W caused it to differ from the Z; in others, duplication of the W occurred. In the family Crotalidae, the W had apparently achieved its very specialized status; it was a distinctly smaller element.