Conserved patterns of nuclear compartmentalization are not observed in the chordate Oikopleura.

Background Information: Recent results from a limited number of eukaryotic model organisms suggest that major principles governing spatial organization of the genome in functionally distinct nuclear compartments are conserved through evolution.

Results: We examined the in situ spatial organization of major nuclear components and nuclear patterns of gene loci with strictly defined expression patterns in endocycling cells of the transparent urochordate Oikopleura dioica, a complex metazoan with a very compact genome. Endocycling cells with different functions and similar DNA content displayed distinct topologies of nuclear components.

Trend towards varying combinatorial centromere association in morphologically identical clusters in Purkinje neurons.

Neurons with similar morphology and neurotransmitter content located at a specific brain region may be part of the same or functionally separate networks. To address the question whether morphologically similar neurons have similar structural architecture at the chromosomal level, we studied Purkinje neurons in the cerebellum. Previous studies have shown that in Purkinje neurons centromeres of several chromosomes form clusters and that the number and size of these clusters remain stable in the adult brain.

Cell-type specific proximity of centromeric domains of one homologue each of chromosomes 2 and 11 in nuclei of cerebellar Purkinje neurons.

In Purkinje neurons of the mouse cerebellum, the centromeres of several chromosomes are placed in close proximity to form a distinct pattern of clusters and exhibit reproducible spatial redistributions during development. In granule neurons, an adjacent cell type in the cerebellum, the pattern, size, and number of centromeric aggregations are different from those of Purkinje neurons. The present work was undertaken to test the hypothesis that the same chromosomes form part of one aggregate in a cell-type-specific manner.

A survey of genetic diversity and reproductive biology of Puya raimondii (Bromeliaceae), the endangered queen of the Andes.

Puya raimondii Harms is an outstanding giant rosette bromeliad found solely around 4000 m above sea level in the Andes. It flowers at the end of an 80 - 100-year or even longer life cycle and yields an enormous (4 - 6 m tall) spike composed of from 15,000 to 20,000 flowers. It is endemic and currently endangered, with populations distributed from Peru to the north of Bolivia.

Organotypic slices in vitro: repeated, same-cell, high-resolution tracking of nuclear and cytoplasmic fluorescent signals in live, transfected cerebellar neurons by confocal microscopy.

The culture of organotypic slices for the purposes of tracking dynamic cellular events within the same live cell at high resolution, as a function of development in vitro has not been previously reported. The present study was undertaken to define the conditions most suitable for both the in vitro organotypic development of Purkinje neurons in cerebellar slices of neonatal mice, and the repeated visualization of nuclear signals within such cells. Slices of cerebella were maintained on 25 mm diameter, collagen-coated Anodisc membranes, placed in six-well plates and raised to the air-medium interface by use of glass fibre filter supports.