Short-term effects of irradiance (0-1560 micromol photons m(-2) s(-1)), temperature (10-25 degrees C), and salinity (40-160) on oxygenic photosynthesis and oxygen consumption in a hypersaline mat (Salin-de-Giraud, France) were investigated with microsensors under controlled laboratory conditions. Dark O(2) consumption rates were mainly regulated by the mass transfer limitations imposed by the d...

The photosynthetic apparatus of higher plants and algae is composed of plastid- and nuclear-encoded components, therefore the expression of photosynthesis genes needs to be highly coordinated. Expression is regulated by various factors, one of the most important of which is light. Photosynthesis functions as a sensor for such light signals, and the redox state of photosynthetic electron transpo...

The N-use efficiency for photosynthesis was higher in a C(4) plant, maize, than in a C(3) plant, rice, including rbcS antisense rice with optimal ribulose-1,5-bisphosphate carboxylase (Rubisco) content for CO(2)-saturated photosynthesis, even when photosynthesis was measured under saturating CO(2) conditions. The N cost for the C(4) cycle enzymes in maize was not large, and the lower amount of ...

Photosynthesis is a rather complicated process (Figure 1). Along the pathway, there are a series of energy transformations, redox reactions, and entry and exit points, any of which could influence the rate of the overall process. However, physiological measurements yield surprisingly simple relationships among a few environmental factors such as light and CO2 availability and overall rates of p...

Dramatic changes have been shown to occur in lake ecosystems exposed to the same intensities of UV-B as those found in eastern Canada today. These changes are caused by UV-B's ability to inhibit photosynthesis in floating plants down to depths of several meters. In other words, the photosynthesis of floating plants (phytoplankton) is reduced by increasing UV-B. The deeper the UV-B penetrates in...

1. Respiration changes as a result of illumination. 2. In the absence of glucose or other supply of substrate, respiration decays in the dark showing at least two types-a fast decay in a few minutes and a slow decay lasting hours. 3. Respiratory response to illumination is delayed. 4. Intermittent illumination (in the absence of glucose, etc.) produces a periodic variation in respiration with a...

Photosynthesis in warm-climate plants is substantially reduced after chilling. Tropical and subtropical species offer the opportunity to study the effects of low temperature on photosynthetic processes undisguised by the myriad of protective responses observed in temperate species. In this article, we highlight the primary components of photosynthesis that are affected by a short chill, in both...

limited number of mutually specific cohesive sites implied thereby suggests a specialized biological function, one that remains to be identified. Summary.-The DNA of phage lambda undergoes reversible transitions from linear to characteristically folded molecules, and from linear monomers to open polymers. Some conditions favoring one state or another have been defined. It may be surmised that e...