Gene Expression Profiling Reveals a Novel Regulatory Role for Sox21 Protein in Mouse Trophoblast Stem Cell Differentiation

Appropriate self-renewal and differentiation of trophoblast stem cells (TSCs) are key factors for proper placental development and function and, in turn, for appropriate in utero fetal growth. To identify novel TSC-specific genes, we performed genome-wide expression profiling of TSCs, embryonic stem cells, epiblast stem cells, and mouse embryo fibroblasts, derived from mice of the same genetic background. Our analysis revealed a high expression of Sox21 in TSCs compared with other cell types. Sox21 levels were high in undifferentiated TSCs and were dramatically reduced upon differentiation. In addition, modulation of Sox21 expression in TSCs affected lineage-specific differentiation, based on both marker analysis and functional assessment. Our results implicate Sox21 specifically in the promotion of spongiotrophoblast and giant cell differentiation and establish a new mechanism through which trophoblast sublineages are specified.     

Investigation of the use of Pulse Tube in cell cryopreservation systems

In order to obtain an acceptable rate of survival of the frozen cells, they must be first cooled in programmable freezers, while controlling the cooling rate, and then stored in maintenance freezers. Different solutions are already used to preserve cells at cryogenic temperatures without liquid nitrogen, while this is not true for controlling the cooling rate.A Pulse Tube (PT) cryorefrigeration system type, can be used in the automatic freezing if combined with a system that monitors and “drives” the temperature generated on the cold part (cold head).To make the Pulse Tube system a suitable one for freezing processes, the cooling curve must be “corrected” in a linear one with a slope given by requested cooling rate. The temperature regulation is obtained with the use of a power dissipator based on Joule effect.In this study, the power to be dissipated is calculated individualizing the trend of temperature on the Pulse Tube cold head and inside the cell test tubes. The control system is not based on an historical series of data so it can be used in different operative conditions. The obtained temperature curve is in good agreement with the theoretical values, with errors within those accepted by commercial systems.The Pulse Tube cryorefrigerator may represent a valid alternative solution to programmable liquid nitrogen freezer, especially where nitrogen’s supply is difficult or extremely expensive.     

Transcription levels of a noncoding RNA orchestrate opposing regulatory and cell fate outcomes in yeast

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Outdoor cultivation ofArthrospira platensis during autumn and winter in temperate climates

Arthrospira (Spirulina) platensis M2 was grown outdoors in 50-mm diameter tubular reactors under the climatic conditions of central Italy (Florence) from September to December 1995 and in March 1996. Except for September, the cultures temperature was regulated. Mean productivities of 0.83, 0.44 and 0.61 g dry wt L^–1 d^–1 were achieved in autumn (September–October), winter (November–December) and March, respectively. In autumn and winter, the photosynthetic efficiency of the cultures and the degree of correlation between productivity and solar irradiance were significantly greater than in summer. The effect of cell density and aeration rate on productivity was evaluated in September. The productivity of cultures operated at high supra-optimal population density was about 30% less at high aeration rate (1.0 LL^–1 min^–1), and 50% less at standard aeration rate (0.17 LL^–1 min^–1), than that of control cultures kept at optimal population density and standard aeration rate. The reduction of productivity in high-density cultures was due to lower daylight output rates and higher night biomass losses (the latter were particularly relevant under standard aeration conditions). The main factor limiting productivity in closed reactors during autumn was the night temperature. Heating the cultures during daylight hours on sunny days did not cause any significant increase of the yields, since under sunlight the unheated cultures also reached the optimal temperature for growth early in the morning. On cloudy days, the day-time temperature of the unheated cultures remained well below the optimum, however this had only a limited effect on productivity since algal growth was mainly light-limited.     

Effect of subchronic treatment with mercury chloride on NTPDase, 5′-nucleotidase and acetylcholinesterase from cerebral cortex of rats

The aim of the present investigation was to evaluate the effect of a subchronic treatment (30 days/30 doses) with subcutaneous injections (0.1 mg/kg) of HgCl₂ on NTPDase (E.C. 3.6.1.5), 5′-nucleotidase (E.C. 3.1.3.5) and acetylcholinesterase (AChE, E.C. 3.1.1.7) activities in brain from adult rats. NTPDase and 5′-nucleotidase were measured in cortical synaptosomal fraction and AChE was measured in the homogenate of cerebral cortex and hippocampus. After the subchronic treatment (30 days), NTPDase activity was enhanced approximately 35% (p < 0.05) with ATP and ADP as substrates and no difference was observed in 5′-nucleotidase activity (AMP hydrolysis). In addition, AChE activity was enhanced in the cerebral cortex (22%, p < 0.05) and hippocampus (26%, p < 0.05) after the subchronic treatment. Mercury deposited in brain was measured by cold vapor (atomic absorption spectrometry) and no difference between the control and the subchronically treated group was observed. Here we showed for the first time that exposure to low levels of Hg²⁺, which resembles occupational exposure to low levels of mercury, caused a marked increase in NTPDase and AChE activities. The relationship of these alterations with the neurotoxicity of inorganic mercury deserves further studies.     

As integrated culture system for outdoor production of microalgae and cyanobacteria

Cultivation of microalgae in closed photobioreactors suffers from high temperatures, whereas in open raceway ponds the optimal temperature is seldom reached. With an integrated device coupling a raceway pond with a suitably sized and positioned closed system (alveolar panel), the heat accumulated in the panel was efficiently transferred to the pond and a near-optimum temperature regimen for Arthrospira platensis was maintained, with no need for any additional cooling device. The productivity obtained in the integrated system was higher than the sum of the productivities (g reactor⁻¹ day⁻¹) of the pond and panel systems operating separately. This revised version was published online in September 2006 with corrections to the Cover Date.