Meiosis

Chromosome stickiness impairs meiosis and influences reproductive success in Panicum maximum (Poaceae) hybrid plants

C. Pessim, Pagliarini, M. S., Silva, N., and Jank, L., “Chromosome stickiness impairs meiosis and influences reproductive success in Panicum maximum (Poaceae) hybrid plants”, vol. 14, pp. 4195-4202, 2015.

Chromosome stickiness has been studied in several species of higher plants and is characterized by sticky clumps of chromatin resulting in sterility. Chromosome stickiness was recorded in Panicum maximum hybrid plants that were cultivated in the field. In the meiocytes affected, chromosomes clumped into amorphous masses that did not orient themselves on the equatorial plate, and anaphase I disjunction failed to occur. After a normal cytokinesis, the masses of chromatin were divided between both daughter cells.

Complete asynapsis resulting in 2n pollen formation in Paspalum jesuiticum Parodi (Poaceae)

R. A. Bernardo Filho, Santos, A. C. C., Souza, F. H. D., Valls, J. F. M., and Pagliarini, M. S., “Complete asynapsis resulting in 2n pollen formation in Paspalum jesuiticum Parodi (Poaceae)”, vol. 13, pp. 255-261, 2014.

Cytological investigation revealed complete asynapsis during microsporogenesis in 2 wild accessions of Paspalum jesuiticum collected in distinct Brazilian regions. Both accessions were hexaploid (2n = 6x = 60) and 60 univalents could be counted at diakinesis. In this phase, the majority of meiocytes exhibited univalents with both chromatids. After alignment at the metaphase plate, the chromatids segregated to the poles. Only 1 meiotic division (equational) occurred, and after cytokinesis, a dyad with 2n microspores was formed.

Cytomixis and meiotic abnormalities during microsporogenesis are responsible for male sterility and chromosome variations in Houttuynia cordata

J. - Z. Guan, Wang, J. - J., Cheng, Z. - H., Liu, Y., and Li, Z. - Y., “Cytomixis and meiotic abnormalities during microsporogenesis are responsible for male sterility and chromosome variations in Houttuynia cordata”, vol. 11, pp. 121-130, 2012.

Houttuynia cordata (Saururaceae) is a leaf vegetable and a medicinal herb througout much of Asia. Cytomixis and meiotic abnormalities during microsporogenesis were found in two populations of H. cordata with different ploidy levels (2n = 38, 96). Cytomixis occurred in pollen mother cells during meiosis at high frequencies and with variable degrees of chromatin/chromosome transfer. Meiotic abnormalities, such as chromosome laggards, asymmetric segregation and polyads, also prevailed in pollen mother cells at metaphase of the first division and later stages.

Abnormal male meiosis explains pollen sterility in the polyploid medicinal plant Pinellia ternata (Araceae)

Y. Liu, Hui, R. - K., Deng, R. - N., Wang, J. - J., Wang, M., and Li, Z. - Y., “Abnormal male meiosis explains pollen sterility in the polyploid medicinal plant Pinellia ternata (Araceae)”, vol. 11, pp. 112-120, 2012.

Pinellia ternata is an important traditional Chinese medicinal plant. Its different populations in China have various ploidy levels, based on x = 13, as well as extensive aneuploid series. The microsporogenesis process was observed in specimens from three populations from three regions of Hubei Province; they were characterized by normal and abnormal meiotic divisions in pollen mother cells (PMCs) at all stages simultaneously.

Spermatogenesis of riffle bugs, Rhagovelia whitei and Rhagovelia sp (Veliidae), and backswimmers Martarega sp (Notonectidae)

M. M. U. Castanhole, Pereira, L. L. V., de Souza, H. V., and Itoyama, M. M., “Spermatogenesis of riffle bugs, Rhagovelia whitei and Rhagovelia sp (Veliidae), and backswimmers Martarega sp (Notonectidae)”, vol. 11, pp. 2003-2020, 2012.

We examined the course of spermatogenesis and the meiotic chromosome complements in aquatic species of true bugs, Heteroptera. The chromosome complement of the Veliidae species was 2n = 39 (38A + X0) and 23 (22A + X0) in Rhagovelia whitei and Rhagovelia sp, respectively, and in the species of the Notonectidae (Martarega sp) it was 26 (22A + 2m + XY); all collected from the region of São José do Rio Preto, SP, Brazil.

Karyotype and spermatogenesis in Triatoma lenti (Hemiptera: Triatominae), a potential Chagas vector

K. C. C. Alevi, Mendonça, P. P., Succi, M., Pereira, N. P., Rosa, J. A., and Azeredo-Oliveira, M. T. V., “Karyotype and spermatogenesis in Triatoma lenti (Hemiptera: Triatominae), a potential Chagas vector”, vol. 11, pp. 4278-4284, 2012.

All species of Triatominae are susceptible to infection by Trypanosoma cruzi (Kinetoplastida: Trypanosomatidae) and consequently, potential insect vectors of Chagas disease. Currently, there are 140 known species of triatomine bugs, which can be grouped into specific species complexes. The species Triatoma lenti (Hemiptera: Triatominae) is found only in Brazil and is considered a potential vector of Chagas disease. We karyotyped male T. lenti and examined its spermatogenesis in detail.

Effect of forest fragmentation on microsporogenesis and pollen viability in Eugenia uniflora, a tree native to the Atlantic Forest

D. J. de Almeida, Faria, M. V., and da Silva, P. R., “Effect of forest fragmentation on microsporogenesis and pollen viability in Eugenia uniflora, a tree native to the Atlantic Forest”, vol. 11, pp. 4245-4255, 2012.

Habitat fragmentation, caused by the expansion of agriculture in natural areas, may be one of the strongest impacts humans have on the ecosystem. These changes can decrease the number of individuals in a population, leading to endogamy. In allogamous species, endogamy can have a negative effect on reproductive capacity. In this study, we analyzed the effects of forest fragmentation on microsporogenesis and pollen viability in Eugenia uniflora L., a tree species native to the Atlantic Forest.

Chromosome number, microsporogenesis, microgametogenesis, and pollen viability in the Brazilian native grass Mesosetum chaseae (Poaceae)

L. A. C. Silva, Pagliarini, M. S., Santos, S. A., Silva, N., and Souza, V. F., “Chromosome number, microsporogenesis, microgametogenesis, and pollen viability in the Brazilian native grass Mesosetum chaseae (Poaceae)”, vol. 11, pp. 4100-4109, 2012.

The genus Mesosetum is a primarily South American genus with 42 species. Mesosetum chaseae, regionally known as ‘grama-do-cerrado’, is abundant in the Pantanal Matogrossense (Brazil); it is a valuable resource for livestock and for environmental conservation. We collected specimens from the Nhecolandia sub-region of the Brazilian Pantanal, located in Corumbá, Mato Grosso do Sul, Brazil. We examined chromosome number, ploidy level, meiotic behavior, microgametogenesis, and pollen viability of 10 accessions.

Mitotic and meiotic behavior of rye chromosomes in wheat - Psathyrostachys huashanica amphiploid x triticale progeny

Q. Xie, Kang, H., Sparkes, D. L., Tao, S., Fan, X. M., Xu, L., Fan, X., Sha, L., Zhang, H., Wang, Y., Zeng, J., and Zhou, Y., “Mitotic and meiotic behavior of rye chromosomes in wheat - Psathyrostachys huashanica amphiploid x triticale progeny”, vol. 12, pp. 2537-2548, 2013.

The dynamics of rye chromosomes during mitosis and meiosis was analyzed in a subset comprising 33 F3 lines from the cross of wheat, Psathyrostachys huashanica amphiploid (AABBDDNsNs) and hexaploid triticale (AABBRR), as visualized by genomic in situ hybridization. The results indicated that 31 of the total lines contained 4-14 rye chromosomes. Twenty-eight combinations had more rye chromosomes than the F1 hybrids, suggesting the occurrence of spontaneous quantitative increment. No P.

Spermatogenesis in Triatoma melanocephala (Hemiptera: Triatominae)

K. C. C. Alevi, Mendonça, P. P., Pereira, N. P., Rosa, J. A., and Azeredo-Oliveira, M. T. V., “Spermatogenesis in Triatoma melanocephala (Hemiptera: Triatominae)”, vol. 12. pp. 4944-4947, 2013.

Triatoma melanocephala is a rare species of Hemiptera. It belonged to the Brasiliensis subcomplex and presents morphological characteristics very close to those of Triatoma vitticeps. We investigated spermatogenesis of T. melanocephala and compared it with that of T. vitticeps in order to determine whether these organisms have similar cytogenetic characteristics. Lacto-acetic orcein staining was used to observe all stages of meiosis.

Pages

Subscribe to Meiosis