PREMATURE CONDENSATION OF SPERMATOGENIC CELL CHROMOSOMES

The technique of premature chromosome condensation (PCC) has been used primarily to study interphase chromosomes of somatic cells. In this study, mitotic cells were fused to cells from the mouse testes to examine the chromosomes of germ cells. The testes contain various types of cells, both germinal and nongerminal. In these initial studies, four types of PCC morphologies were observed. Chromosome morphology of the PCC and labeling experiments demonstrated the mouse cell origin of various PCC. Attempts were next made to determine the cell types producing the PCC. Spermatogonia, diplotene spermatocytes, secondary spermatocytes and round spermatids are proposed to be the origin of the PCC morphologies. Some PCC could be banded by G and C banding techniques and the mouse chromosomes identified.^ Studies were subsequently undertaken to evaluate this technique as a method of evaluating damage to germ cells. Testicular cells from irradiated mice were fused to mitotic cells and the PCC examined. Both round spermatids and secondary spermatocytes exhibited chromosome damage in the form of chromatid breaks. A linear correlation was found between the dose of irradiation and the number of breaks per cell. This technique may develop into a useful method for evaluating the clastogenic effect of agents on the germ cells. ^

Albert Einstein [Illustration] : nach einer Original-Radierung

Hermann Struck

Einstein

-tz.

Porträtbüste Professor Albert Einstein [Illustration]

Moshe Ziffer

Continuous condensation particle (CP) observations from 1984 through 2009 at Neumayer Station, Antacrtica

Continuous condensation particle (CP) observations were conducted from 1984 through 2009 at Neumayer Station under stringent contamination control. During this period, the CP concentration (median 258 1/cm**3) showed no significant long term trend but exhibited a pronounced seasonality characterized by a stepwise increase starting in September and reaching its annual maximum of around 10**3/cm**3 in March. Minimum values below 10**2/cm**3 were observed during June/July. Dedicated time series analyses in the time and frequency domain revealed no significant correlations between inter-annual CP concentration variations and atmospheric circulation indices like Southern Annular Mode (SAM) or Southern Ocean Index (SOI). The impact of the Pinatubo volcanic eruption and strong El Niño events did not affect CP concentrations. From thermodenuder experiments we deduced that the portion of volatile (at 125 °C) and semi-volatile (at 250 °C) particles which could be both associated with biogenic sulfur aerosol, was maximum during austral summer, while during winter non-volatile sea salt particles dominated. During September through April we could frequently observe enhanced concentrations of ultrafine particles within the nucleation mode (between 3 nm and 7 nm particle diameter), preferentially in the afternoon.