Abstract The grasshopper Rhammatocerus brasiliensis shows polymorphism of B chromosomes, but the magnitude of B-chromosome occurrence and the factors that may contribute to their dispersion in the species remain unknown thus far. The present study analyzed the occurrence and dispersion of B chromosomes in R. brasiliensis individuals from 21 populations widely distributed in the Brazilian Northeast. The genetic connectivity between 10 populations was verified through analysis of ISSR markers from 200 individuals. Of the 21 populations, 19 presented individuals with one B chromosome, three with two, and one with three B chromosomes. The B chromosome is of medium size and constitutive heterochromatin (CH) located in the pericentromeric region. A variant B chromosome was observed in three populations, similar in size to that of chromosome X, gap and CH, and located in the terminal region. B chromosome frequencies in different populations varied from 0% to 18,8%, mean 8,5%. The wide distribution of the B chromosome is likely a consequence of the positive gene flow among the analyzed populations. B-chromosome occurrence in populations of R. brasiliensis possibly follows the population genetic structure of the species and, owing to the existence of a variant, its origin may not be recent.

RESUMO Dez pacientes com queimaduras oculares unilaterais graves, oito por agentes químicos e dois por agentes térmicos, foram submetidos ao transplante de conjuntiva limbar autógena. A técnica cirúrgica consistiu em transferir dois retalhos da conjuntiva limbar do olho contralateral, para regiões comprometidas do olho acometido. O acompanhamento variou de 8 a 48 meses. Todos os pacientes apresentaram melhora da acuidade visual, estabilidade epitelial e regressão da neovascularização estromal. O transplante de conjuntiva limbar autógeno parece ser indicado para o tratamento de queimaduras oculares químicas ou térmicas severas, associadas à perda de células primordiais limbares.

SUMMARY Ten consecutive patients with severe unilateral ocular bum, chemical (8 patients) and thermal (2 patients) underwent limbal autograft transplantation. The surgical technique consisted on transplanting of free grafts of limbal tissue from the contralateral eye to the injured recipient eye. All the patients experienced improvement on visual acuity, regression of stromal neovascularization, no episodes of recurrent epithelial erosion or persistent epithelial defect. Limbal autograft transplantation appears to be effective as a treatment for severe ocular surface diseases related with chemical or thermal burns.