Bisulfite compounds as metabolic inhibitors: nonspecific effects on membranes

Bisulfite compounds are shown to be nonspecific inhibitors ofphotosynthetic processes and of ion transport in green tissues.CO₂ fixation and light-dependent transient changes in externalpH are inhibited about 50% by 5x10^–4 M glyoxal-Na-bisulfite.Chloride uptake in the light and in the dark is inhibited tothe same extent at this concentration. At 5x10^–3 M theinhibitor reduces ATP levels in the light and in the dark, andeffects on glycolate oxidase and PEP carboxylase are observed.The extent of inhibition is dependent on time of treatment withglyoxal-Na-bisulfite and freshly prepared NaHSO₃ is equallyas effective as the addition compound. Possible explanations of the bisulfite effects and the relationshipsto SO₂ effects on photosynthesis are discussed. (Received September 1, 1971; )     

When to start and when to stop: Effects of climate on breeding in a multi‐brooded songbird

Climate warming has been shown to affect the timing of the onset of breeding of many bird species across the world. However, for multi‐brooded species, climate may also affect the timing of the end of the breeding season, and hence also its duration, and these effects may have consequences for fitness. We used 28 years of field data to investigate the links between climate, timing of breeding, and breeding success in a cooperatively breeding passerine, the superb fairy‐wren (Malurus cyaneus). This multi‐brooded species from southeastern Australia has a long breeding season and high variation in phenology between individuals. By applying a “sliding window” approach, we found that higher minimum temperatures in early spring resulted in an earlier start and a longer duration of breeding, whereas less rainfall and more heatwaves (days > 29°C) in late summer resulted in an earlier end and a shorter duration of breeding. Using a hurdle model analysis, we found that earlier start dates did not predict whether or not females produced any young in a season. However, for successful females who produced at least one young, earlier start dates were associated with higher numbers of young produced in a season. Earlier end dates were associated with a higher probability of producing at least one young, presumably because unsuccessful females kept trying when others had ceased. Despite larger scale trends in climate, climate variables in the windows relevant to this species’ phenology did not change across years, and there were no temporal trends in phenology during our study period. Our results illustrate a scenario in which higher temperatures advanced both start and end dates of individuals’ breeding seasons, but did not generate an overall temporal shift in breeding times. They also suggest that the complexity of selection pressures on breeding phenology in multi‐brooded species may have been underestimated.     

Size at birth, fat-free mass and resting metabolic rate in adult life.

Resting metabolic rate is an important predictor of obesity and is closely related to fat-free mass. There is evidence that fat-free mass may be partly determined during critical periods of growth before and after birth. The objective of this study was to examine the relationship between size at birth, childhood growth and fat-free mass and resting metabolic rate in adult life. 318 men and women with detailed records of body size at birth and growth during school years participated in the study. Fat-free mass correlated positively with birth weight among both sexes (r = 0.264, p < 0.001). Those having a higher birth weight had a higher fat-free mass at any adult BMI. Fat-free mass among men increased by 2.2 kg (95 % Cl 0.5 to 3.9; p = 0.01) for every kg increase in birth weight and by 1.5 kg (95 % Cl 1.3 to 1.7, p < 0.0001) for every kg/m(2) BMI in adult life. In women, fat-free mass increased by 2.7 kg (95 % Cl 1.6 - 3.9; p < 0.001) for every kg increase in birth weight and by 0.8 kg (95 % CI 0.7 to 1.0, p < 0.001) for every kg/m(2) of BMI in adult life. Height, weight and body mass index at each age from 7 to 15 years were also strongly, positively associated with fat-free mass. A negative correlation between birth weight and resting metabolic rate expressed per unit of fat-free mass (r = - 0.158; p < 0.001) was found. Fat-free mass may be determined during critical periods of muscle growth in utero and during childhood. The muscle tissue of people who had a lower birth weight is more metabolically active than those with a higher birth weight. This may protect them from the increased risk of obesity associated with low fat-free mass.