Gender differences in physical and psychological stress responses among college judoists undergoing weight reduction

Gender-related differences in anthropometry, blood biochemistry, psychological parameters, and energy intake during prematch weight reduction were studied in 22 men and 7 women college judoists who lost weight by combining judo training, restricting food and fluid, and sweating. Body weight (BW) decreased significantly by 2.2±1.4 kg in men and 2.0±1.4 kg in women 2 weeks after weight reduction started — not significandy different. Body fat, relative body fat and total energy intake also decreased significandy in both groups 2 weeks after weight reduction started. Lean body mass decreased significandy 2 weeks after weight reduction started only in men. Men had significantly decreased blood lipids, immunoglobulins, complements, hematocrit, white blood cell count, and serum electrolytes, and significant increases in blood uric nitrogen, creatinine, and hemoglobin, while women showed no such changes. The score for vigor in the Profile of Mood States (POMS) decreased in both groups 2 weeks after weight reduction started, but with no statistically gender difference. In women, scores for anxiety in the State-Trait Anxiety Inventory (STAI) and confusion in POMS increased significandy. Although the men and women had the same BW reduction, significant physical stress response was seen only in men, and psychological stress due to weight reduction and mental pressure of an upcoming competition were seen more in women

Ecophysiology of photosynthesis in macroalgae

Macroalgae occur in the marine benthos from the upper intertidal to depths of more than 200 m, contributing up to 1 Pg C per year to global primary productivity. Freshwater macroalgae are mainly green (Chlorophyta) with some red (Rhodophyta) and a small contribution of brown (Phaeophyceae) algae, while in the ocean all three higher taxa are important. Attempts to relate the depth distribution of three higher taxa of marine macroalgae to their photosynthetic light use through their pigmentation in relation to variations in spectral quality of photosynthetically active radiation (PAR) with depth (complementary chromatic adaptation) and optical thickness (package effect) have been relatively unsuccessful. The presence (Chlorophyta, Phaeophyceae) or absence (Rhodophyta) of a xanthophyll cycle is also not well correlated with depth distribution of marine algae. The relative absence of freshwater brown algae does not seem to be related to their photosynthetic light use. Photosynthetic inorganic carbon acquisition in some red and a few green macroalgae involves entry of CO2 by diffusion. Other red and green macroalgae, and brown macroalgae, have CO2 concentrating mechanisms; these frequently involve acid and alkaline zones on the surface of the alga with CO2 (produced from HCO3-) entering in the acid zones, while some macroalgae have CCMs based on active influx of HCO3-. These various mechanisms of carbon acquisition have different responses to the thickness of the diffusion boundary layer, which is determined by macroalgal morphology and water velocity. Energetic predictions that macroalgae growing at or near the lower limit of PAR for growth should rely on diffusive CO2 entry without acid and alkaline zones, and on NH 4+ rather than NO3- as nitrogen source, are only partially borne out by observation. The impact of global environmental change on marine macroalgae mainly relates to ocean acidification and warming with shoaling of the thermocline and decreased nutrient flux to the upper mixed layer. Predictions of the impact on macroalgae requires further experiments on interactions among increased inorganic carbon, increased temperature and decreased nitrogen and phosphorus supply, and, when possible, studies of genetic adaptation to environmental change. © 2012 Springer Science+Business Media B.V

Photosynthesis and metabolism of seagrasses

© Springer International Publishing AG, part of Springer Nature 2018. Seagrasses have a unique leaf morphology where the major site for chloroplasts is in the epidermal cells, stomata are absent and aerenchyma is present inside the epidermis. This means that the major site for photosynthesis is in the epidermis. Furthermore the lack of stomata means that the route for carbon uptake is via inorganic carbon (C i ) uptake across the vestigial cuticle and through the outer plasma membranes. Since the leaf may at times be in an unstirred situation diffusion through an unstirred layer outside the leaf may be a large obstacle to carbon uptake. The existence of a carbon concentrating mechanism is discussed, but its existence to date is not proven. Active bicarbonate uptake across the plasmalemma does not seem to operate; an external carbonic anhydrase and an extrusion of protons seem to play a role in enhancing CO 2 uptake. There is some evidence that a C4 mechanism plays a role in carbon fixation but more evidence from "omics" is required. Photorespiration certainly occurs in seagrasses and an active xanthophyll cycle is present to cope with damaging high light, but both these biochemical mechanisms need further work. Finally, epiphytes pose a problem which impedes the uptake of C i and modifies the light environment inside the leaves