Chromosome structure and behaviour in Bursaphelenchus xylophilus (Nematoda: Parasitaphelenchidae) germ cells and early embryo

Chromosome structure and behaviour in both meiosis of the germ cells and mitosis of the embryo from fertilisation to the two-cell stage in Bursaphelenchus xylophilus were examined by DAPI staining and three-dimensional reconstruction of serial-section images from confocal laser-scanning microscopy. By this method, each chromosome’s shape and behaviour were clearly visible in early embryogenesis from fertilisation through the formation and fusion of the male and female pronuclei to the first mitotic division. The male pronucleus was bigger than that of the female, although the oocyte is larger and richer in nutrients than the sperm. From the shape of the separating chromosomes at anaphase, the mitotic chromosomes appeared to be polycentric or holocentric rather than monocentric. Each chromosome was clearly distinguishable in the male and female germ cells, pronuclei of the one-cell stage embryo, and the early embryonic nuclei. The haploid number of chromosomes (N) was six (2n = 12), and all chromosomes appeared similar. The chromosome pair containing the ribosomal RNA-coding site was visualised by fluorescence in situ hybridisation. Unlike the sex determination system in Caenorhabditis elegans (XX in hermaphrodite and XO in male), the system for B. xylophilus may consist of an XX female and an XY male.

Nicolau e Nicolina, 90 anos de travessuras

Tomámos a rubrica Diabruras de Nicolau, mais tarde Nicolau e Nicolina, do primeiro suplemento infantil de grande fôlego em Portugal – o Notícias Miudinho do Diário de Notícias, – e propusemo-nos criar cinco Livros- -de-Montar, um para cada fase do seu percurso, entre 1924 e 1933. Observámos o percurso das publicações infantis em Portugal, particularmente nas décadas dos nossos protagonistas, e tirámos ilações dos seus períodos áureos; pesquisámos suportes e mecanismos em papel recortado e todo o tipo de livros, no limiar do conceito. Tentámos perceber como poderíamos, sem recorrer a mão-de-obra estrangeira, criar livros pop-up em Portugal, a baixo custo, e contribuir para melhorar dois pontos fracos da cultura de hoje, que o nosso exercício na docência verifica diariamente: desenvolver competências ao nível da motricidade fina, perceção do espaço e gosto pela leitura; e fomentar momentos de partilha “analógica” entre gerações, cuja falta é hoje gritante; ABSTRACT: NICOLAU E NICOLINA, 90 years of pranks Taking as a starting Diabruras de Nicolau, later Nicolau e Nicolina, the first children’s supplement of grand success in Portugal – the Notícias Miudinho of Diario de Noticias, - we proposed to create five books to assemble, one for each phase of its course, between 1924 and 1933. We analysed the course of children’s publications in Portugal, particularly in the decades of our protagonists, taking conclusions of its golden periods; we searched for supports and mechanisms in cut paper and all kind of books, in the concept’s threshold. We tried to understand how we could create, without resorting to cheap labour from around the globe, pop-up books in Portugal, at low cost, and also to contribute to improving two weak points in today’s culture, that we as teachers face every day: to develop delicate motor skills, space perception and a taste for reading; and to encourage moments of analogical closeness between generations, whose absence is striking today.