An automated technique for monitoring carbon dioxide respired by insects*

ABSTRACT. A non-dispersive infrared gas analyser equipped with a Luft-type sonic detector and flow-through reference cell was automated to monitor the total volume of carbon dioxide (CO₂) respired by single insects or groups of insects. The infrared analyser was interfaced with an integrator for quantification, a microprocessor to control intermittent air flow through the insect respiration chambers, and a microcomputer for data storage and reduction. This technique has been used to monitor the CO₂ Output of diapausing and non-diapausing mature fifth instar larvae and of developing pupae of the codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae). The resulting data were accurate, quantitative and reproducible.     

Respiration in the sexuals of the ant Lasius flavus

ABSTRACT. Gynes and males of Lasius flavus Fab. were taken from the nest as they eclosed, and at intervals thereafter until the mating flight, and their respiration was measured. After the mating flight respiration was measured in gynes at various stages of colony foundation. Respiration in gynes rose rapidly to a peak as they began to accumulate food reserves for colony foundation. Subsequently, the respiratory rate declined and remained at a low level until the mating flight and during the claustral phase of colony foundation. Once the colony was well established and the queen actively laying, the respiratory rate returned to that at the beginning of maturation. Males showed smaller changes in their respiratory rates, which were generally higher than those of the gynes. The variation in respiration in males seemed to be due to increasing restlessness as the time of the mating flight approached.     

The NADH Dehydrogenase Nde1 Executes Cell Death after Integrating Signals from Metabolism and Proteostasis on the Mitochondrial Surface

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Ecological significance of individual variability in copepod bioenergetics

High interstage variability in body length and mass, reproductive state, and metabolic activity is characteristic of copepod populations from the Barents Sea and coastal waters in Sweden and Norway. The dry weight of a given copepodite stage, sampled at a given time from a homogeneous water mass, may vary by a factor of 4–5 between extreme individuals, protein and particularly lipid content being even more variable. Similarly, high variability in gut fullness and grazing rate within defined copepodite stages typically occurs at all times of the year, both when measured as in situ rate or experimentally determined rate, using homogeneous food suspensions. In accordance with this, maturation state (measured as length of gonads) and spawning (measured as rate of egg production over 24 h) are highly variable factors at the individual level. Since all these factors also influence the metabolic rate of the animals the respiratory rate (measured as ETS activity) of comparable individuals may vary by a factor of 5 or more. The results indicate that high individual variability in size and activity parameters is universal. This can not be explained by existing models of feeding behaviour, growth and development, and calls for new models, in which the nutritional history of the individual may play an important role.     

Fine structural localization of alkaloid synthesis in endoplasmic reticulum of submergedClaviceps purpurea

Cyanide-insensitive mitochondria from Saccharomycopsis lipolytica possess an exogenous NADH dehydrogenase, located outside the inner mitochondrial membrane, and linked to coupling site II. These mitochondria are able to oxidize exogenous NADH via two pathways: (1) a cyanide- and antimycin-sensitive pathway, or cytochrome pathway, and (2) a cyanide- and antimycin-insensitive pathway, or alternative pathway. Although the oxidation of exogenous NADH through the cytochrome pathway occurs with an ATP/0 ratio tending to 2, it proceeds, per molecule of NADH oxidized, with the apparent ejection in the outer medium of only 3 protons instead of 4 protons, as is the case with glycerol 3-phosphate as control substrate, but leaves 1 hydroxyl ion in the outer medium after decay of the protonmotive force. These properties were used to demonstrate the non electrogenic function of the alternative pathway. Indeed, the oxidation of exogenous NADH via the alternative pathway proceeds without apparent ejection of protons, although this oxidation generates an electron flux in the alternative pathway as demonstrated by the net appearance in the outer medium of 1 hydroxyl ion per atom of oxygen reduced, appearance which proves sensitive to benhydroxamic acid, a specific inhibitor of the alternative pathway. The non electrogenicity of the alternative pathway is accompanied by the absence of ATP synthesis as expected from Mitchell's chemiosmotic model. The absence of energy conservation when the electron transfer proceeds via the alternative pathway is not the result of an uncoupling property of an active alternative pathway, as the oxidation of malate plus pyruvate via coupling site I and the alternative pathway occurs with an ATP/0 ratio tending to 1.     

RADIOTAGGING STUDIES OF BELUKHA WHALES (DELPHINAPTERUS LEUCAS) IN BRISTOL BAY, ALASKA

Research was conducted in Bristol Bay, Alaska, to determine the applicability of radiotagging to studies of behavior, distribution and movements of belukha whales. Backpack-style VHF transmitters were attached to two belukhas by pinning through the dorsal ridge. Both packages were shed after about 2 wk due to migration of the pin through the tissue. Movements of radio-tagged whales were essentially local within Kvichak Bay. Three basic respiration patterns were identified: surfacings that were grouped into breathing periods separated by longer dives; surfacings that did not occur during restricted breathing periods; and long-to-very-long surfacings separated by short-to-very-short dives. These patterns were interpreted as representing traveling, feeding and feeding or resting in very shallow water. Surface and dive interval data were used to calculate a correction factor of 2.75, which could then be applied to aerial survey counts to estimate the total number of belukha whales in the study area. Modifications to radio packages are necessary in order to increase retention time.     

Degradation of Machine Oil by Nocardioform Bacteria

Gas liquid chromatography (GLC) was used for the first time to screen for machine oil–degrading microorganisms. Oil degradation was evaluated from the microorganism respiratory activity during the utilization of oil as the sole carbon and energy source. The results are consistent with those obtained by the conventional weighing method. Substrate specificity of the active strains with respect to different machine oils was studied. Bacterial communities exhibited the highest activity, whereas a Rhodococcus erythropolisstrain was the most active among pure cultures. Various stages of bacterial interaction with oil drops were followed by means of fluorescent microscopy.     

Translocation - A key factor limiting the efficiency of nitrogen fixation in legume nodules

A hypothesis is presented that the availability of water for export of nitrogenous products from legume nodules is a major factor limiting the efficiency of symbiotic nitrogen fixation. Water for export of solutes in the xylem probably depends largely on the import of water and reduced carbon in the phloeum, and one function of respiration may be to dispose of reduced carbon in order to increase the supply of water. A second hypothesis presented is that control of gas diffusion in soybean nodules is largely restricted to the cortex nearby the vascular bundles, thus making possible the linkage of solute balances in xylem and phloem with resistance to diffusion. These concepts are used in a re-examination of literature on manipulations of nodules and nodulated plants such as lowering of light levels, water stress, defoliation, stem girdling, and alteration of oxygen supply. The concept of translocation as a major factor limiting efficiency of symbiotic fixation is consistent with the failure of superior rhizobial isolates to improve N input significantly, and this limitation could also prevent exploitation of superior bacterial symbionts in the future