We analyzed patterns of heterochromatic bands in the Neotropical stingless bee genus Melipona (Hymenoptera, Meliponini). Group I species (Melipona bicolor bicolor, Melipona quadrifasciata, Melipona asil6ae, Melipona marginata, Melipona subnitida) were characterized by low heterochromatic content. Group II species (Melipona capixaba, Melipona compressipes, Melipona crinita, Melipona seminigra fuscopilosa e Melipona scutellaris) had high heterochromatic content. All species had 2n =18 and n = 9. In species of Group I heterochromatin was pericentromeric and located on the short arm of acrocentric chromosomes, while in Group II species heterochromatin was distributed along most of the chromosome length. The most effective sequential staining was quinacrine mustard (QM)/distamycin (DA)/chromomycin A 3 (CMA 3 )/4-6-diamidino-2-phenylindole (DAPI). Heterochromatic and euchromatic bands varied extensively within Group I. In Group II species euchromatin was restricted to the chromosome tips and it was uniformly GC + . Patterns of restriction enzymes (EcoRI, DraI, HindIII) showed that heterochromatin was heterogeneous. In all species the first pair of homologues was of unequal size and showed heteromorphism of a GC + pericentromeric heterochromatin. In M. asil6ae (Group I) this pair bore NOR and in M. compressipes (Group II) it hybridized with a rDNA FISH probe. As for Group I species the second pair was AT + in M. subnitida and neutral for AT and GC in the remaining species of this group. Outgroup comparison indicates that high levels of heterochromatin represent a derived condition within Melipona. The pattern of karyotypic evolution sets Melipona in an isolated position within the Meliponini.

Tetragonisca angustula and Tetragonisca fiebrigi have recently been listed as valid species. This study aimed to cytogenetically investigate both species, emphasizing the new registry of B chromosomes in the tribe Meliponini. We analyzed colonies of T. angustula and T. fiebrigi collected at Tangará da Serra, Mato Grosso, Brazil, through conventional Giemsa staining, C-banding, and base-specific fluorochrome staining (CMA3/DAPI). T. angustula showed 2n = 34 chromosomes in females and n = 17 in males, with karyotype formula 2K = 34AM. T. fiebrigi showed numeric variation, with chromosome number varying from 2n = 34 to 2n = 36 in females and from n = 17 to n = 18 in males, with karyotype formula 2K = 32AM+2AMc and 2K = 32AM+2AMc + 1 or 2 B-chromosomes. The B chromosomes are heterochromatic. In T. fiebrigi, the CMA3/DAPI staining revealed four chromosomes with a CMA3 positive band. All individuals from the same colony showed the same number of B chromosomes. T. angustula and T. fiebrigi showed karyotype divergence, principally due to the presence of B chromosomes, which are found only in T. fiebrigi. Our data corroborate the status of valid species for both T. angustula and T. fiebrigi, as recently proposed.

Most Meliponini share a distinctive pattern of heterochromatin distribution in relation to other bees. In general, they present one euchromatic and one heterochromatic chromosome arm, a feature explained by minimum interaction theory, which involved centric fissions followed by heterochromatin addition. In this work, two Meliponini with a distinct pattern of heterochromatin distribution, Tetragonisca fiebrigi and Melipona rufiventris, were analyzed using chromosomal microdissection of the heterochromatin region followed by FISH (fluorescent in situ hybridization). Hybridization revealed FISH signals equivalent to location of the isolated fragment that were widespread over heterochromatic portions of other chromosomes. This result showed that the heterochromatic sequences were very similar among chromosomes in the same species. Cross-hybridization of each probe in M. rufiventris and T. fiebrigi yielded no signals, revealing that both species presented differentiated and non-homologous heterochromatin sequences.

Resumo Este estudo avalia o desempenho de fundos de investimento brasileiros em ações, comparando retornos reais e indicadores paramétricos e não paramétricos de performance. A estimativa de desempenho e classificação dos fundos foi realizada com base na observação dos retornos reais e dos alfas obtidos do modelo de regressão linear paramétrica, de Carhart. Os indicadores foram comparados com os scores de eficiência relativa da análise envoltória de dados, do modelo não paramétrico de Banker, Charnes e Cooper. Os alfas foram estimados considerando os impactos dos fatores de mercado, tamanho, valor e momento nos retornos reais de cada fundo e os scores, tendo como insumos risco sistêmico, recursos disponíveis, custos e risco total, e, como produto de análise, os retornos. Identificou-se queda de performance dos fundos, apontada pela literatura, alta correlação dos alfas com os retornos reais, baixa correlação dos scores com retornos e mais baixa correlação entre alfas e scores. Isso indica que a escolha da medida de avaliação a ser utilizada consiste em uma importante etapa da seleção de ativos. Montaram-se, ainda, carteiras teóricas pautadas na eficiência e alfas identificando-se performance superior das carteiras baseada na eficiência, sendo que nenhuma delas superou a carteira de mercado.