Abstract The genus Melipona is subdivided into four subgenera based on morphological characteristics, and two groups based on cytogenetic patterns. The cytogenetic information on this genus is still scarce, therefore, the goal of this study was to characterize Melipona paraensis, Melipona puncticollis, and Melipona seminigra pernigra using the following techniques: C-banding, DAPI/CMA3 fluorochromes, and FISH with an 18S rDNA probe. Melipona paraensis (2n=18) and M. seminigra pernigra (2n=22) were classified as high heterochromatin content species (Group II). Their euchromatin is restricted to the ends of the chromosomes and is CMA3+; the 18S rDNA probe marked chromosome pair number 4. Melipona puncticollis (2n=18) is a low heterochromatin content species (Group I) with chromosome pair number 1 marked with CMA3 and 18S rDNA. Low heterochromatin content is a putative ancestral karyotype in this genus and high content is not a monophyletic trait (Melikerria presents species with both patterns). Differences concerning the karyotypic characteristics can be observed among Melipona species, revealing cytogenetic rearrangements that occurred during the evolution of this genus. Studies in other species will allow us to better understand the processes that shaped the chromatin evolution in Melipona.

Abstract Two retrotransposons from the superfamilies Copia and Gypsy named as Copia-LTR_SS and Gypsy-LTR_SS, respectively, were identified in the genomic bank of Sclerotinia sclerotiorum. These transposable elements (TEs) contained direct and preserved long terminal repeats (LTR). Domains related to codified regions for gag protein, integrase, reverse transcriptase and RNAse H were identified in Copia-LTR_SS, whereas in Gypsy-LTR_SS only domains for gag, reverse transcriptase and RNAse H were found. The abundance of identified LTR-Solo suggested possible genetic recombination events in the S. sclerotiorum genome. Furthermore, alignment of the sequences for LTR elements from each superfamily suggested the presence of a RIP (repeat-induced point mutation) silencing mechanism that may directly affect the evolution of this species.

Sementes poliembriônicas são caracterizadas pelo desenvolvimento de mais de um embrião na mesma semente, que podem ser zigóticos ou nucelares. Neste trabalho, objetivou-se identificar a origem genética, se zigótica ou nucelar, de plântulas oriundas de sementes poliembriônicas de mangueira 'Ubá', utilizando-se marcadores moleculares ISSR, relacionando-a com o vigor das plântulas. Para isto, coletaram-se mangas, em Visconde do Rio Branco (acesso 102) e Ubá (acessos 112, 138, 152 e 159), das quais as sementes foram germinadas, em bandejas plásticas, com areia lavada. Cinquenta dias após a semeadura foram analisadas plântulas de cinco sementes, de cada um dos acessos 102, 112, 138 e 159 e de 10 sementes do acesso 152. As plântulas foram caracterizadas e avaliadas quanto à altura, à circunferência do caule e à massa fresca da parte aérea e considerou-se a plântula mais vigorosa aquela que apresentasse pelo menos duas destas medidas superiores às das demais plântulas da semente. Folhas foram coletadas para extração de DNA genômico, que foi amplificado com sete primers ISSR, previamente selecionados com base no perfil de amplificação e considerando-se o número e a resolução dos fragmentos. Observou-se a presença de plântulas zigóticas em 18 sementes, que foram as mais vigorosas em seis sementes. Isso evidencia a existência de variabilidade em pomares que utilizam mudas oriundas de sementes, pois o produtor rural normalmente utiliza a plântula mais vigorosa, considerando que esta seja de origem nucelar. Esses resultados indicam que a plântula mais vigorosa nem sempre é a nucelar, pois, em 20 % das sementes avaliadas, a plântula zigótica foi a mais vigorosa.

Polyembryonic seeds are characterized by the development of over one embryo in the same seed, which can be zygotic and nucellar. The objective of this work was to identify the genetic origin, whether zygotic or nucellar, of seedlings of polyembryonic seeds of 'Ubá' mango tree using ISSR markers, and relating them with the vigor of the seedlings. Thus, mangos were harvested in Visconde do Rio Branco (accession 102) and Ubá (accessions 112, 138, 152 and 159), whose seeds were germinated in plastic trays filled with washed sand. Fifty days after sowing, seedlings from five seeds of each one of the accessions 102, 112, 138, 159 and from 10 seeds of the accession 152, were analyzed. These sseedlings were characterized and evaluated for plant height, stem circumference and mass of fresh aerial part and the most vigorous seedling was the one displaying at least two of these traits higher than the other seedlings from seed. Leaves were collected for genomic DNA extraction, which was amplified using seven ISSR primers previously selected based on the amplification profile and considering the number and resolution of fragments. Zygotic seedlings were found in 18 seeds, which were the most vigorous in six seeds. The results evidenced the existence of genetic variability in orchards using seedlings grown from seeds, because the farmer usually uses the most vigorous ones, assuming that this is of nucellar origin. These results also indicate that the most vigorous seedling are not always nucellar, inasmuch as of 20% of the total seeds evaluated, the zygotic seedling was the most vigorous.

The genetic diversity and structure of the ant Atta robusta were assessed by ISSR (inter-simple sequence repeats) in 72 colonies collected from 10 localities in the Brazilian states of Espírito Santo (48 colonies) and Rio de Janeiro (24 colonies). The ISSR pattern included 67 bands, 51 of them (76.1%) polymorphic. Analysis of molecular variance (AMOVA) revealed a high level (57.4%) of inter-population variation, which suggested a high degree of genetic structure that was confirmed by UPGMA (unweighted pair-group method using an arithmetic average) cluster analysis. The significant correlation between genetic and geographic distances (r = 0.64, p < 0.05) indicated isolation that reflected the distance between locations. Overall, the populations were found to be genetically divergent. This finding indicates the need for management plans to preserve and reduce the risk of extinction of A. robusta.

Partamona is a Neotropical genus of stingless bees that comprises 33 species distributed from Mexico to southern Brazil. These bees are well-adapted to anthropic environments and build their nests in several substrates. In this study, 66 colonies of Partamona helleri from five localities in the Brazilian state of Minas Gerais (São Miguel do Anta, Teixeiras, Porto Firme, Viçosa and Rio Vermelho) were analyzed using nine microsatellite loci in order to assess their genetic variability. Low levels of observed (Ho = 0.099-0.137) and expected (He = 0.128-0.145) heterozygosity were encountered and revealed discrete genetic differentiation among the populations (F ST =0.025). AMOVA further showed that most of the total genetic variation (94.24%) in P. helleri was explained by the variability within local populations.

Four colonies of the stingless bee Partamona cupira (Hymenoptera: Apidae) were cytogenetically analyzed using conventional staining and the fluorochromes CMA3 e DAPI. The females have 2n = 34 chromosomes (2K=32<img border=0 src="../../../../../../../img/revistas/gmb/2010nahead/ah06a04CarM.gif" align=absmiddle>+2<img border=0 src="../../../../../../../img/revistas/gmb/2010nahead/ah06a04CarA.gif" align=absmiddle>). Some females, however, presented an additional large B acrocentric chromosome, to a total of 2n = 35. Chromosome B and the chromosomal pairs 2, 9 and 10 showed CMA3+ bands, indicating an excess of CG base-pairs. A clear association was verified between the P. helleri B chromosome SCAR marker and the presence of a B chromosome in P. cupira. The data obtained suggests that B chromosomes in P. helleri and P. cupira share a common origin.

Due to their high degree of polymorphism, microsatellites are considered useful tools for studying population genetics. Nevertheless, studies of genetic diversity in stingless bees by means of these primers have revealed a low level of polymorphism, possibly the consequence of the heterologous primers used, since in most cases these were not specifically designed for the species under consideration. Herein we compared the number of polymorphic loci and alleles per locus, as well as observed heterozygosity in Melipona rufiventris and M. mondury populations, using specific and heterologous primers. The use of specific primers placed in evidence the greater frequency of polymorphic loci and alleles per locus, besides an expressive increase in observed heterozygosity in M. rufiventris and M. mondury, thereby reinforcing the idea that populational studies should be undertaken by preferably using species-specific microsatellite primers.

Allozyme, microsatellite and random amplified polymorphic DNA (RAPD) molecular markers were used to investigate the within and between population genetic variability and between population genetic differentiation of the Brazilian stingless bee uruçu amarela (nominally Melipona rufiventris Lepeletier, 1836) present in savanna and Atlantic forest habitats of the Brazilian state of Minas Gerais (MG). We found low levels of within population variability, although there were a large number of private alleles that specifically characterized these populations. The F ST values indicated a high level of genetic diversity between populations. Analysis of molecular variance (AMOVA) showed a high degree of population differentiation between the savanna and Atlantic forest habitats, confirmed by population pairwise F ST data. Principal coordinates analysis and unweighted pair-group method using an arithmetic average (UPGMA) dendrograms also confirmed that in Minas Gerais the savanna populations (M. rufiventris) were genetically distinct from those present in the Atlantic forest (M. mondury). In addition, populations from locations near the towns of Dom Bosco and Brasilândia de Minas were genetically different from those collected in other localities in the savanna. Our data indicate that populations of uruçu amarela found in the savanna and Atlantic forest habitats of Minas Gerais state should be treated separately for conservation purposes and that special attention should be given to the populations found in the region of Dom Bosco and Brasilândia de Minas until their taxonomic status is clarified.

A eficiência do programa de melhoramento de cacau incrementará pela seleção de cruzamentos superiores entre clones divergentes. Foram estimadas as distâncias genéticas (GD), com dados de RAPD, e de Mahalanobis (MD), com dados de componentes de produção, entre cinco clones. Os clones foram avaliados em um dialelo, por cinco componentes de produção, durante cinco anos. Um total de 130 bandas RAPD foram avaliadas. GD e MD foram utilizadas para cálculo da correlação entre distâncias entre clones e a performance de seus híbridos. A correlação entre GD e MD foi de 0.67 (P=0.03). Ambas as distâncias foram correlacionadas à performance heterótica dos híbridos para peso de sementes frescas/planta e peso de sementes frescas/fruto. A performance híbrida média para os mesmos componentes de produção foi correlacionada somente com MD. Assim, distâncias genéticas medidas por RAPD e componentes de produção podem ser usadas como um guia para a escolha de cruzamentos superiores.

The efficiency of cacao breeding program can be increased by choosing superior crosses to be made between divergent clones. We assessed the genetic distance among five clones with RAPD data (genetic distance - GD) and with yield component data (Mahalanobis distance - MD). The clones were evaluated in a diallel, during five years, for five yield components. A total of 130 RAPD bands were scored. GD and MD were used to determine the correlation between genetic distances among clones and the performance of their hybrids. The correlation between GD and MD was 0.67 (P=0.03). Both distances were related to heterotic performance of hybrids for wet seed weight/plant and wet seed weight/fruit. The average hybrid performance for the same two yield components was correlated with only MD. Hence, genetic distances measured by RAPD and yield components can be used as a guide to the choice of the superior crosses.

O objetivo deste trabalho foi o de testar três protocolos de extração de DNA utilizados para Apis, plantas e fungos, visando determinar um que seja eficiente para extração de DNA de Melipona quadrifasciata. Esses métodos diferem nas concentrações de componentes específicos do tampão de extração. Os resultados obtidos mostraram que a metodologia recomendada para extração de DNA de Apis não é adequada para a extração de DNA de M. quadrifasciata. Entretanto, com pequenas modificações, este método, bem como aquele utilizado para a extração de DNA de plantas e fungos, mostrou-se eficiente para a extração de DNA desta abelha sem ferrão, tanto de indivíduos adultos como de larvas

The objective of the present study was to test three different procedures for DNA extraction of Melipona quadrifasciata based on existing methods for DNA extraction of Apis, plants and fungi. These methods differ in the concentrations of specific substances in the extraction buffer. The results demonstrate that the method used for Apis is not adequate for DNA extraction from M. quadrifasciata. On the other hand, with minor modifications this method and the methods for plants and fungi were adequate for DNA extraction of this stingless bee, both for adults and larvae