Meiotic behavior of a nonaploid accession endorses x = 6 for Brachiaria humidicola (Poaceae).

Brachiaria humidicola (Poaceae), originally from Africa, is an economically important pasture plant in tropical South America. An accession of B. humidicola (H038) collected from the wild African savanna (Mbeya, Tanzania) showed irregular microsporogenesis. This meiotic behavior was consistent with an allopolyploid origin. Multivalent chromosome association at diakinesis gave tri- to octavalents, associated with two nucleoli in some cells. Six non-congregated univalents in metaphase I and anaphase I, along with previous lines of evidence for x = 6 in B. humidicola, confirm H038 as a nonaploid accession, 2n = 9x = 54. Asynchrony in the genome during microsporogenesis also corroborated this assumption. Its putative origin could be a cross between two related species with different rhythms in meiosis. The meiotic behavior of this accession reinforces the hypothesis of the existence of a new basic chromosome number (x = 6) for Brachiaria. The use of this accession in the breeding of this important forage grass for the tropics is discussed

2n Gamete formation in the genus Brachiaria (Poaceae: Paniceae).

Microsporogenesis of several Brachiaria species of the Brazilian collection at Embrapa Beef Cattle has been analyzed in detail. This paper reports abnormal cytokinesis in three accessions of three different species (Brachiaria humidicola, 2n = 4x = 36, Brachiaria decumbens, 2n = 4x = 36, and Brachiaria dura, 2n = 6x = 54). Chromosomes paired in bi-, tri-, and quadrivalents in these accessions, whereas chromosome segregation at meiosis I was characterized by exclusion of laggards as micronuclei. In a high number of meiocytes, the first sign of cytokinesis appeared only in metaphase II and did not divide the meiocyte into a dyad. Total absence of cytokinesis was also detected among meiocytes in the second division. Since in both cases the two metaphase plates were very close, they favored the rejoining of chromosome sets after anaphase II and formed a restitutional nucleus in telophase II. Second cytokinesis occurred after telophase II in most meiocytes. Monads, dyads, and triads with n or 2n nuclei were observed among meiotic products. The 2n gametes observed correspond to the first division restitution (FDR). The number of affected cells in each accession was variable, but the number of microspores with restitutional nucleus, including those scored in tetrads and the released ones, did not exceed 9%. Although polyploidy is common in the genus Brachiaria, its origin is still unclear. Current results suggest that 2n gametes may have contributed to the evolutionary history of the genus.CNPGC

FindFoci: a focus detection algorithm with automated parameter training that closely matches human assignments, reduces human inconsistencies and increases speed of analysis

Accurate and reproducible quantification of the accumulation of proteins into foci in cells is essential for data interpretation and for biological inferences. To improve reproducibility, much emphasis has been placed on the preparation of samples, but less attention has been given to reporting and standardizing the quantification of foci. The current standard to quantitate foci in open-source software is to manually determine a range of parameters based on the outcome of one or a few representative images and then apply the parameter combination to the analysis of a larger dataset. Here, we demonstrate the power and utility of using machine learning to train a new algorithm (FindFoci) to determine optimal parameters. FindFoci closely matches human assignments and allows rapid automated exploration of parameter space. Thus, individuals can train the algorithm to mirror their own assignments and then automate focus counting using the same parameters across a large number of images. Using the training algorithm to match human assignments of foci, we demonstrate that applying an optimal parameter combination from a single image is not broadly applicable to analysis of other images scored by the same experimenter or by other experimenters. Our analysis thus reveals wide variation in human assignment of foci and their quantification. To overcome this, we developed training on multiple images, which reduces the inconsistency of using a single or a few images to set parameters for focus detection. FindFoci is provided as an open-source plugin for ImageJ

Implicações técnicas e ecossistêmicas do manejo inadequado da arborização urbana: o caso das podas drásticas em oitis na cidade de Ilha Solteira - SP

Oiti is a large species, recommended for urban afforestation. However, it is often implemented in inappropriate places, which can cause conflicts with some factors in cities and with the population in general. Thus, inadequate pruning is carried out, causing great damage to the plant and to public management. The objective of this work was to analyze the drastic pruning performed on Oiti trees used in urban afforestation in the municipality of Ilha Solteira - SP. Oiti specimens diagnosed with drastic pruning were diagnosed and data related to location, presence of electriclal cables and pruning order were collected from the City Hall. The reasons for pruning were listed, the trees were registered using digital photos, which were compared to images from Google Street View® prior to the pruning. It was concluded that Oiti trees received drastic pruning in several neighborhoods in the city of Ilha Solteira, which were carried out with no justification nor request/consent from the City Hall, resulting in some cases in the death of the tree and consequent loss of urban green.O Oiti é uma espécie de grande porte, recomendada para arborização urbana. Contudo, muitas vezes é implantada em locais inadequados, o que pode ocasionar conflitos com alguns fatores nas cidades e com a população em geral. Assim, podas inadequadas são realizadas, ocasionando grandes prejuízos na planta e para a gestão pública. O objetivo deste trabalho foi analisar as podas drásticas realizadas em árvores de Oiti utilizadas na arborização urbana no município de Ilha Solteira - SP. Foram diagnosticados exemplares de Oiti consideradas com poda drástica e coletados dados referentes à localização, presença de fiação e pedido de poda junto a Prefeitura Municipal. Foram elencados os motivos para a realização da poda, o registro das árvores por fotos digitais, que foram comparadas com imagens do Google Street View® anteriores à realização da poda. Concluiu-se que árvores de Oiti receberam poda drástica em diversos bairros da cidade de Ilha Solteira, sendo estas realizadas sem justificativa e solicitação/anuência da Prefeitura Municipal, resultando em alguns casos na morte da árvore e consequente perda do verde urbano