Food Resource Characteristics in Two Nocturnal Lemurs with Different Social Behavior: Avahi occidentalis and Lepilemur edwardsi

I present results from a comparative field study on the feeding behavior of the gregarious Avahi occidentalis and the solitary-but-social Lepilemur edwardsi to evaluate hypotheses relating to social organization and food resources. While Avahi and Lepilemur are both nocturnal, have comparable body weights and positional behaviors, and are both folivorous, they differ in their social organization. Therefore, they present an ideal model for assessing food resource characteristics through comparisons of food selection in both species with regard to forest composition. The monogamous Avahi tend to select under-represented resources. They are repeatedly exploited, which suggests that their location must be known. It is worthwhile and probably imperative to defend those resources. Such defense imposes ranging limitations on male Avahi. Females may prefer familiar mates that will share their knowledge of resource location and defend the resources. A stable monogamous pattern could be the optimal strategy. In contrast, food selection by Lepilemur is based on common resources to a higher degree, but they show a lower degree of exploitation. Lepilemur males would be less restricted and could potentially opt for a different strategy, e.g., a dispersed harem. It is unclear whether this strategy is realized or not. I discuss other possible correlates of monogamy—infanticide protection, predation avoidance—but the gregarious pattern in Avahi may best be seen as a retention, and its nocturnal activity as a secondary adaptation.     

Nitrogen Metabolism in Senescing Leaves

Leaf senescence is a highly organized process and not a passive decay. Photosynthesizing mesophyll cells lose their functions in an early phase, while the epidermal layer with the stomates and the phloem remains functional throughout senescence. The subcellular compartmentation is maintained and allows the cooperation of different organelles in the remobilization of constituents. Nitrogen metabolism changes at the onset of senescence from assimilation to remobilization. Enzymes involved in nitrate reduction are lost, while some enzymes of intermediary nitrogen metabolism are maintained longer, and some catabolic enzymes reach highest activities during senescence. Chloroplasts are dismantled early, but mitochondria remain active and may fuel remobilization processes. Chloroplast proteins are degraded, and this nitrogen fraction can be translocated via the phloem from senescing leaves to sinks within the same plant. In contrast, chlorophyll is degraded, fragments produced reach the vacuole, and catabolites accumulate there. Nuclear DNA is maintained until a very late phase. The export of nitrogen from senescing plant parts is important for the economic use of this macronutrient. The regulation of senescence at the whole plant level as well as at the molecular level is only rudimentarily known, although interesting new aspects have been presented recently.     

Tidal exhaled nitric oxide in healthy, unsedated newborn infants with prenatal tobacco exposure.

Tidal fractional exhaled nitric oxide (FE(NO)) changes were investigated in healthy, unsedated infants with or without prenatal tobacco exposure. Tidal flow (V), FE(NO), and CO(2) were measured in 20 healthy, unsedated infants [age: 25-58 days, length: 56.5 +/- 2.5 (SE) cm]. NO output (VNO) was calculated (VNO = FE(NO) x V). Two approaches were used to investigate within-breath changes of FE(NO) and VNO. First, we identified phases II and III from the expiratory capnogram. Second, we divided expiration into time-based quartiles. Tidal FE(NO) (range: 14.5 +/- 1.6 to 17.6 +/- 2.1 parts/billion: quartile 4 and phase II, respectively) was not different between portions and exhibited significant negative V dependence. VNO was significantly dependent on the expiratory portion, with quartile 4 being significantly lower than the remaining expiratory portions. Infants exposed to prenatal cigarette smoke (n = 7) exhibited significantly lower FE(NO) and VNO compared with nonexposed (n = 13) infants. We conclude that tidal FE(NO) is V dependent and that VNO may be a more suitable outcome parameter in variable V conditions. Prenatal tobacco exposure resulted in a decreased FE(NO) and VNO in infants.     

Requirements for the light-stimulated degradation of stromal proteins in isolated pea (Pisum sativum L.) chloroplasts

Chloroplasts from 17-d-old pea leaves (Pisum sativum L.) wereisolated to elucidate the requirements for the light-induceddegradation of stromal proteins. The influence of electron transportthrough the thylakoids and the influence of ATP on protein degradationwere investigated. When chloroplasts were incubated in the light(45 µmol m^–2s^–1), glutamine synthetase, thelarge subunit of ribulose-1,5-bisphosphate carboxylase and glutamatesynthase were degraded, whereas phosphoribulokinase, ferredoxin-NADP⁺reductase and the 33 kDa protein of photosystem II remainedmore stable. Major protein degradation was not observed over240 mm in darkness. The electron transport inhibitor dichlorophenyldimethylureareduced protein degradation in the light over several hours,whereas dibromothymoquinone was less effective. Inhibiting theproduction of ATP with tentoxin or by destroying the