Research Article

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12/08/2006
Allopolyploidy; Brachiaria brizantha; Forage grass; Microsporogenesis; Pollen viability

In the hexaploid (2n = 6x = 54) accession B176 of Brachiaria brizantha, one cytological characteristic differentiated it from the other accessions previously analyzed with the same ploidy level. Nearly 40% of meiocytes displayed the chromosome set arranged at two metaphase plates at the poles of the cell, close to the membrane. In these cells, both metaphase plates were ... more

C. Risso-Pascotto; D.V. Mendes; N. Silva; M.S. Pagliarini; C.B. Valle
01/15/2008
Adaptation; Evolution; Natural habitat; Wild cassava

A total of 98 Manihot species have been recognized in the genus. All of them are native to the tropics of the New World, particularly Brazil and Mexico. The cultigen, Manihot esculenta Crantz (cassava), grows throughout the lowland tropics. Wild species vary in growth habit from acaulescent or short shrubs to tree-like. Because of their adaptations to different conditions, ... more

N.M.A. Nassar; D.Y.C. Hashimoto; S.D.C. Fernandes
07/15/2013
45S rDNA; AgNOR-banding; Anura; chromosome; Evolution

Chromosome numbers, morphology, and nucleolus organizer region (NOR) locations are useful cytological characters for taxonomic and evolutionary studies. In this study, we provide the first cytogenetic analysis of Phyllomedusa bahiana and Phasmahyla spectabilis, and report new cytogenetic data on variation in NOR numbers and positions in Phyllomedusa rohdei and ... more

A. Barth; V.A. Souza; M. Solé; M.A. Costa
12/19/2014
Evolution; Grasshoppers; Meiotic chromosomes; Period gene; Permanent in situ hybridization (PISH)

The single-copy gene Period was located in five grasshopper species belonging to the Acridomorpha group through permanent in situ hybridization (PISH). The mapping revealed one copy of this gene in the L1 chromosome pair in Ommexecha virens, Xyleus discoideus angulatus, Tropidacris collaris, Schistocerca pallens, and Stiphra ... more

T.E. Souza; D.L. Oliveira; J.F. Santos; T.T. Rieger
11/07/2014
BMP4; Evolution; Mature domain region

Bone morphogenetic protein 4 (BMP4) regulates skeletogenesis, osteoblastic differentiation, and the induction of hair follicles. Its protein-coding region contains a signal peptide, prodomain (which regulates post-translational synthesis), and a mature domain (which mediates gene function). Previous studies considered this gene to be conserved. By reanalyzing the coding region of ... more

D.J. Zhang; J.H. Wu; G. Husile; H.L. Sun; W.G. Zhang
10/20/2014
Brazilwood; Caesalpinieae; Cytogenetics; Evolution

With the purpose of addressing the pattern of karyotype evolution in Caesalpinia species, chromosome morphology was characterized in five species from Brazil, and karyotypic asymmetry was analyzed in 14 species from South America. All accessions had the chromosome number 2n = 24, which was first described here for Caesalpinia laxiflora Tul. and Cenostigma ... more

P.S. Rodrigues; M.M. Souza; R.X. Corrêa
03/06/2014
BIMLR; Cass; Evolution; Phylogenetic network; QuickCass

Developing appropriate methods for constructing phylogenetic networks from tree sets is an important problem, and much research is currently being undertaken in this area. BIMLR is an algorithm that constructs phylogenetic networks from tree sets. The algorithm can construct a much simpler network than other available methods. Here, we introduce an improved version of the BIMLR algorithm ... more

J. Wang
02/21/2014
Anguilliformes; Chromosome number; cytotaxonomy; Evolution

Cytogenetic studies in Gymnothorax funebris revealed a diploid chromosome number 2n = 42 (6 metacentrics, 4 submetacentrics, and 32 acrocentrics, FN = 52). The results obtained are novel and similar to those previously described for species belonging to Muraenidae family. The conventional karyotype is also novel and divergent from other species of the genus Gymnothorax, ... more

M.A.O. Alves; J.E. Monteiro-Junior; C.A.M. Oliveira; R.M. Silveira; I.R. Costa; R. Maggioni
08/11/2006
Apomixis; Interspecific crosses; Polyploidy

A new species was synthesized artificially by chromosome doubling in a hybrid. The ensuing polyploid type exhibits an apomictic nature and maintains its morphological characteristics in the progeny. It showed a frequency of multiembryonic sacs of 29% in the ovules examined, whereas sacs were absent in the diploid type.

*In honor of deceased Professor Vieira who dedicated a part ... more

N.M.A. Nassar
06/22/2006
Chromosomal size evolution; Genome size evolution; Incongruent patterns; Oryza sativa; Polyploidy

To investigate genome size evolution, it is usually informative to compare closely related species that vary dramatically in genome size. A whole genome duplication (polyploidy) that occurred in rice (Oryza sativa) about 70 million years ago has been well documented based on current genome sequencing. The presence of three distinct duplicate blocks from the polyploidy, of ... more

X. Guo; G. Xu; Y. Zhang; X. Wen; W. Hu; L. Fan

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