NILTON CESAR PIRES BIONE¹, MARIA SUELY PAGLIARINI², LEONES ALVES DE ALMEIDA³

BIOCELL, Vol.29, No.2, pp. 177-181, 2005, DOI:10.32604/biocell.2005.29.177

Abstract A spontaneous male-sterile, female-fertile mutation affecting bivalent arrangement at the metaphase plate and cytokinesis was detected in line BR98-197 of the soybean breeding program developed by Embrapa – National Soybean Research Centre. Untill diakinesis, meiosis was normal with chromosome pairing as bivalents. From this phase, in several meiocytes, bivalents were not able to organize a single metaphase plate and remained scattered in the cytoplasm in a few or several groups. In these meiocytes, chromosomes segregated in both divisions giving rise to several micronuclei. However, the main cause of male sterility was the absence of cytokinesis More >

MARÍA ESTHER DIUPOTEX-CHONG¹, NÉSTOR J. CAZZANIGA², ALEJANDRA HERNÁNDEZ-SANTOYO³, JOSÉ MIGUEL BETANCOURT-RULE⁴

BIOCELL, Vol.28, No.3, pp. 279-285, 2004, DOI:10.32604/biocell.2004.28.279

Abstract Mitotic chromosomes of the freshwater snail Pomacea patula catemacensis (Baker 1922) were analyzed on gill tissue of specimens from the type locality (Lake Catemaco, Mexico). The diploid number of chromosomes is 2n = 26, including nine metacentric and four submetacentric pairs; therefore, the fundamental number is FN = 52. No sex chromosomes could be identified. The same chromosome number and morphology were already reported for P. flagellata, i.e., the other species of the genus living in Mexico. The basic haploid number for family Ampullariidae was reported to be n° =°14 in the literature; so, its reduction to More >

C. Luna, P. Sansberro*, L. Mroginski, J. Tarragó

BIOCELL, Vol.27, No.2, pp. 205-212, 2003, DOI:10.32604/biocell.2003.27.205

Abstract Micropropagation of Ilex dumosa var. dumosa R. (“yerba señorita”) from nodal segments containing one axillary bud was investigated. Shoot regeneration from explants of six-year-old plants was readily achieved in ¹/₄ strength Murashige and Skoog medium (¹/₄ MS) plus 30 gr·L^-1 sucrose and supplemented with 4.4 µM BA. Further multiplication and elongation of the regenerated shoots were obtained by subculture in a fresh medium of similar composition with 1.5 gr·L^-1 sucrose. Rooting induction from shoots were achieved in two steps: 1) 7 days in ¹/₄ MS (30 gr·L^-1 sucrose, 0.25 % Phytagel^®) with 7.3 µM IBA and 2) 21 days in More >

M. Iura¹, Y. Suetake², S. N. Atluri³

CMES-Computer Modeling in Engineering & Sciences, Vol.4, No.2, pp. 249-258, 2003, DOI:10.3970/cmes.2003.004.249

Abstract An accuracy of finite element solutions for 3-D Timoshenko's beams, obtained using a co-rotational formulation, is discussed. The co-rotational formulation has often been used with an assumption that the relative deformations are small. A fundamental question, therefore, has been raised as to whether or not the numerical solutions obtained approach the solutions of the exact theory. In this paper, from theoretical point of view, we investigate the accuracy of the co-rotational formulation for 3-D Timoshenko's beam undergoing finite strains and finite rotations. It is shown that the use of the conventional secant coordinates fails to More >