Pluripotency and differentiation in embryos and stem cells - Pavia, 17-18 January 2008

Each year many scientific meetings are held on stem cells to appraise the state of knowledge on their potency, differentiation and applications. So why did we hold another meeting? Because we thought one aspect was not adequately addressed in the others. When thinking of how our body is derived from a single fertilized egg, it is self-evident that the embryo is the ‘mother’ of all stem cells. This fact is probably overlooked because it is so remote (decades back in our lives!) and because embryonic stem cells do not exist as such in the embryo. However, this also tends to be ignored on purpose in many stem cell meetings because working on (human) embryos brings up substantial ethical concerns that bear on the scientific undertaking like nothing else. The origin of stem cells has become even more of a sensitive issue since the discovery in 2006 that embryonic stem (ES) cell-like cells can be generated in a petri dish straight from somatic cells by retrovirus-mediated transfer of selected genes. These new cells have been named ‘induced pluripotent stem‘ (iPS) cells and have been obtained without any egg or embryo consumption (Takahashi and Yamanaka, 2006). This leads to the first topic of our meeting: natural and induced pluripotency..

Macrobiotus pseudohufelandi Iharos as a model for cytotaxonomic study in populations of eutardigrades (Tardigrada).

The paper illustrate a cytophotometric approach able to furnish cytotaxonomic information regarding Macrobiotus pseudohufelandi Iharos (Tardigrada)

Some parameters for a cell cycle cytotopochemical study.

With the Feulgen-Naphthol Yellow double reaction we dosed, simultaneously on a cell, [1] the DNA nuclear content (as Feulgen positive material), [2] the protein cell content and [3] the Feulgen chromatin area; the degree of condensation is expressed by the ratio [1]/[3]. The evolution of the lymphocytes culture at different times of PHA stimulation was in this way studied with the aim of defining the existence of cell subpopulations pertaining at different phases or subphases of the cycle

New data on the nuclear DNA content in some species of tardigrades.

In the chapter the Feulgen DNA content was evlauted in several species of tardigrades. A small genome size and poliploidy was confirmed

Mouse embryonic stem cells that survive γ-rays exposure maintain pluripotent differentiation potential and genome stability.

This study aimed to investigate the cell cycle, apoptosis, cytogenetics and differentiation capacity of mouse embryonic stem cells (mESCs) that survived a single dose of 2 or 5 Gy g-rays during a period of up to 96 h of culture. After 2Gy irradiation and 24 h ulture, compared to control, a significant majority of cells was blocked at the G2/M phase and a massive apoptosis was recorded. Between 48 and 72 h post-irradiation, the parameters used to describe the cell cycle and apoptosis returned similar to those of control samples. When mESCs were irradiated with 5 Gy, a small fraction of cells, even after 96 h of culture, still presented clear evidences of a G2/M block and apoptosis. The cytogenetic analysis performed at 96 h showed that the structural stability of the aberrations did not change significantly when comparing control and 2 or 5 Gy-treated populations. However, the chromosomal damage observed in the progeny of the survived cells after 5Gy exposure is significantly higher than that observed in control samples, although it is mostly of the stable and transmissible type. Ninety-six hours after irradiation, the survived mESCs maintained their undifferentiated status and capability to differentiate into the three germ layers. Overall, these results indicate a commitment of mESCs to maintain pluripotency and genome stability

Quantitative variation of LINE-1 sequences in five species and three subspecies of the subgenus Mus and in five Robertsonian races of Mus musculus domesticus

Abstract The quantitative variation of a conserved region of the LINE-1 ORF2 sequence was determined in eight species and subspecies of the subgenus Mu