Low temperature inhibits plant growth despite the fact that considerable rates of photosynthetic activity can be maintained. Instead of lower rates of photosynthesis, active inhibition of cell division and expansion is primarily responsible for reduced growth. This results in sink limitation and enables plants to accumulate carbohydrates that act as compatible solutes or are stored throughout t...

The yeast Saccharomyces cerevisiae contains two ras homologues, RAS1 and RAS2, whose products have been shown to modulate the activity of adenylate cyclase encoded by the CYR1 gene. To isolate temperature-sensitive mutations in the RAS2 gene, we constructed a plasmid carrying a RAS2 gene whose expression is under the control of the galactose-inducible GAL1 promoter. A ras1 strain transformed wi...

A proximate, biophysical model is proposed describing temperature-modulated variation in growth rate and differentiation rate in ectotherms, based upon the Sharpe–Schoolfield equation connecting enzyme kinetics and biological rates. Like the Sharpe-Schoolfield equation, the model assumes (1) that growth rate and differentiation rate can be described as controlled by one rate-limiting enzyme; in...

Advances in understanding the molecular regulation of longitudinal growth have led to development of novel drug therapies for growth plate disorders. Despite progress, a major unmet challenge is delivering therapeutic agents to avascular-cartilage plates. Dense extracellular matrix and lack of penetrating blood vessels create a semipermeable "barrier," which hinders molecular transport at the v...

The Hb (hemoglobin) content of Paramecium has been known to maintain a constant level even when the cells are exposed to different conditions. However, the relative concentrations of the Hb components in the stocks of P. caudatum, P. multimicronucleatum and P. jenningsi were found to change during cell growth from logarithmic young phase to stationary growth phase even when the culture was main...