Myrmeleon unifomis Malpighian tubules cells were analyzed under two aspects: chromatin structure and total protein quantification in the three larval phases (L1, L2 and L3) and in adults. This insect Malpighian tubules present polyploid tissue resultant from endoreduplication, which probably begins in the first larval phases.
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.
c-Jun N-terminal kinase (JNK) is an important member of the mitogen-activated protein kinase superfamily. The allotetraploid crucian carp is a product of distant hybridization of female red crucian carp with male common carp. It is the first natural case of an allotetraploid with stable genetic characters, including fertility of both female and male animals.
The grass Puccinellia maritima is an important saltmarsh ecosystem engineer exhibiting wide morphological variation, which is partially genetically determined. Nevertheless, nothing is known about its population genetics or how neutral genetic variation is distributed throughout its geographical range. Here, we describe 12 polymorphic microsatellites pooled into two multiplexes for this octoploid species. Assessment of 24 samples from three populations revealed 4 to 29 alleles per locus, with variation in allele presence and abundance between populations.
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.
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.
Most members of the subfamily Mimosoideae have pantropical distributions, variable habits, and a basic chromosome number x = 13. We examined karyotypic evolution of 27 species of this subfamily occurring principally in northeastern Brazil by examining chromosomes stained with Giemsa. All of the species had semi-reticulated interphase nuclei and early condensing segments in the proximal region of both chromosome arms.
Cassava is the most important staple crop in the Tropics and Subtropics. Apomixis may revolutionize its production due to various attributes. These potential advantages include production by true seed, maintaining cultivar superiority over generations without segregation, and avoiding contamination by bacteria and viruses. Historically, apomixis was initially observed by International Institute of Tropical Agriculture researchers, in the 1980s, in homogenous progeny of hybrid crosses.
Hypochaeris is an excellent system for studying different modes of chromosome evolution in plants. We carried out a cytogenetic analysis on populations of 2 Hypochaeris species, comprising 10 populations of H. catharinensis and 5 of H. lutea, to assess possible changes on chromosome organization in this interesting genus.
The land arthropod secretory system is formed by structures called Malpighian tubules. These tubules are extremely important in insects because they maintain osmoregulation. They are located in the body cavity and are either free or inserted in the rectum wall, forming an arrangement known as the cryptonephridial system. The Malpighian tubules may have morphologically different regions, with each one formed by a specific cell type.