Applicability of RAPD markers on silver-stained polyacrylamide gels to ascertain genetic diversity in Peripatus acacioi (Peripatidae; Onychophora)

RAPD (random amplification of polymorphic DNA) molecular markers can be utilized for analyzing genetic variability in populations for which only a few or no molecular markers are available. They were used in a study of an endangered species, Peripatus acacioi, found in the Tripuí Ecological Station, in Ouro Preto, MG, Brazil. The ecological station was specifically created to protect this velvet worm species, the first of this group found in Brazil. For an initial evaluation of the genetic diversity of this species, DNA samples from the lobopods of four individuals, collected at random, were analyzed using RAPD. Each reaction was run with a different primer (Operon RAPD 10-mer Kits), totaling 13 primers (OPC2, OPC3, OPC4, OPC6, OPC8, OPC10, OPC11, OPL2, OPL7, OPL11, OPL13, OPL18, and OPL19). Due to the low amplification yield, RAPD fragments were separated in polyacrylamide gels and stained with silver nitrate. Numerous bands were observed. Fifty-five of the amplified bands proved to be reproducible, both in terms of presence and intensity. Among these, 27 were variable and 28 were constant. The average number of bands per gel was 4.2. Nine of the 13 primers tested allowed the identification of constant and variable bands among these four individuals. RAPD analysis of genetic variation using silver-stained polyacrylamide gel electrophoresis provided measures of band sharing among the individuals, and therefore could be used in population genetics studies of P. acacioi.

Genetic diversity and structure of natural populations of Plathymenia reticulata (Mimosoideae), a tropical tree from the Brazilian Cerrado.

Plathymenia reticulata is a tropical tree native to the Brazilian Cerrado, one of the most important and endangered ecosystems in Brazil. This species presents high-quality wood and potential for recovery of degraded areas. Despite its importance, almost nothing is known about its genetic or ecological features. Random amplified polymorphic DNA (RAPD) markers were used to investigate the genetic diversity and structure of six natural populations of P. reticulata. DNAs from 117 adult individuals were amplified with 10 random primers and Shannon's index and amova were used to evaluate the levels of genetic diversity within and among populations. Through 72 markers, 70.8% of which were polymorphic, it was possible to obtain 117 unique RAPD phenotypes. The levels of genetic variability found in the six populations of P. reticulata were considerable and most of the genetic variation was found between individuals within populations, although pairwise PH(ST) values indicated significant divergence between populations. The among-population component accounted for, respectively, 12.3% and 16% of the genetic variation, according to amova and Shannon's index. These results were compared with other genetic studies on plant species and such a level of differentiation among populations corresponds to that which has usually been observed for outcrossing plants. The importance of maintenance of the P. reticulata populations and implications of the analysis of adult individuals, considering the longevity of this species and the relatively recent Cerrado fragmentation, are discussed.

Estudo do comportamento dos linfocitos derivados do timo em pacientes com penfigo foliaceo na presenca de levamisol. / Behaviour of T - lymphocytes in patients with foliaceus pemphigus at the presence of levamisole

Foram estudados linfocitos T de pacientes portadores de penfigo foliaceo em relacao a sua capacidade de formar rosaceas "E", diante de concentracoes do imunopotenciador levamisol. O levamisol e uma substancia que estimula formacao de rosaceas de linfocitos T ativos em individuos normais: Os linfocitos de pacientes antes da corticoterapia sistemica nao responderam ao levamisol ja os linfocitos de pacientes em tratamento com corticoides tiveram inibida sua capacidade de formar rosaceas. Esses achados sugerem altecao no metabolismo celular dos linfocitos de pacientes penfigosos devido provavelmente a alguma falha no sistema enzimatico dessas celulas envolvendo a fosfodiesterase do AMPc