Estimation of turgor pressure through comparison between single plant cell and pressurized shell mechanics.

While plant growth is well known to rely on turgor pressure, it is challenging to quantify the contribution of turgor pressure to plant cell rheology. Here we used a custom-made micro-rheometer to quantify the viscoelastic behavior of isolated plant cells while varying their internal turgor pressure. To get insight into how plant cells adapt their internal pressure to the osmolarity of their medium, we compared the mechanical behavior of single plant cells to that of a simple, passive, pressurized shell: a soccer ball.

Effects of daytime and nighttime stress on Fos-like immunoreactivity in the paraventricular nucleus of the hypothalamus, the habenula, and the posterior paraventricular nucleus of the thalamus.

Circadian effects on basal and stress-induced Fos-like immunoreactivity (IR) in the paraventricular nucleus of the hypothalamus (PVN), the habenula (Hab) and the posterior paraventricular nucleus of the thalamus (PVN-Thal) were examined. Stress induced a significant increase in the number of Fos-like IR cells within all 3 brain regions. In the Hab, expression was localized specifically to the medial region of the lateral Hab.

Immobilisation stress induces a paradoxical sleep rebound in rat.

An immobilisation stress (IS) of 2 h applied to rats at the beginning of the dark period (12 h), i.e. when the animals are more active, induces during the 10 consecutive h a significant rebound (+92%) of paradoxical sleep (PS) while slow-wave sleep state (SWS) is poorly affected.

Detection of vasopressin mRNA in the neurointermediate lobe of the rat pituitary.

A messenger ribonucleic acid (mRNA) homologous to the transcript that encodes vasopressin (VP) was detected in the neurointermediate lobe (NIL) of the rat pituitary. The abundance of this transcript is approximately 1/100th the amount detected in the hypothalamus. In rats drinking 2% NaCl-water for 0,2,4, or 10 days, or for 10 days and then tap water for 14 days, the levels of VP mRNA in the NIL were altered in a fashion that paralleled changes in the hypothalamus.