Peak Of Respiration Research Articles

Normal ripening cultivars of Pyrus serotina are either climacteric or non-climacteric

The climacteric status has been investigated in two cultivars of Pyrus serotina (Rehder). Both cultivars are chance seedlings. The fruit displayed a high respiration rate early in development that declined as fruit matured. Both ripened, as seen by skin degreening and softening, at similar times after flowering. Yet only in cultivar ‘Chojuro’ were the ripening changes associated with increased rates of ethylene and carbon dioxide production. In cultivar ‘Nijisseiki’ ethylene and carbon dioxide did not increase as fruit ripened. Continuous exposure of fruit to propylene accelerated skin degreening in cultivar ‘Nijisseiki’ but did not induce ethylene production or a climacteric peak of respiration. Whereas, in ‘Chojuro’, skin degreening, and ethylene and carbon dioxide production were all advanced after exposure to propylene. We conclude that although fruit development and ripening of both cultivars are similar, ‘Chojuro’ ripens with an associated respiratory climacteric, whereas ‘Nijisseiki’ does not.

Involvement of Wound and Climacteric Ethylene in Ripening Avocado Discs

Avocado (Persea americana Mill. cv Hass) discs (3 mm thick) ripened in approximately 72 hours when maintained in a flow of moist air and resembled ripe fruit in texture and taste. Ethylene evolution by discs of early and midseason fruit was characterized by two distinct components, viz. wound ethylene, peaking at approximately 18 hours, and climacteric ethylene, rising to a peak at approximately 72 hours. A commensurate respiratory stimulation accompanied each ethylene peak. Aminoethoxyvinyl glycine (AVG) given consecutively, at once and at 24 hours following disc preparation, prevented wound and climacteric respiration peaks, virtually all ethylene production, and ripening. When AVG was administered for the first 24 hours only, respiratory stimulation and softening (ripening) were retarded by at least a day. When AVG was added solely after the first 24 hours, ripening proceeded as in untreated discs, although climacteric ethylene and respiration were diminished. Propylene given together with AVG led to ripening under all circumstances. 2,5-Norbornadiene given continuously stimulated wound ethylene production, and it inhibited climacteric ethylene evolution, the augmentation of ethylene-forming enzyme activity normally associated with climacteric ethylene, and ripening. 2,5-Norbornadiene given at 24 hours fully inhibited ripening. When intact fruit were pulsed with ethylene for 24 hours before discs were prepared therefrom, the respiration rate, ethylene-forming enzyme activity buildup, and rate of ethylene production were all subsequently enhanced. The evidence suggests that ethylene is involved in all phases of disc ripening. In this view, wound ethylene in discs accelerates events that normally take place over an extended period throughout the lag phase in intact fruit, and climacteric ethylene serves the same ripening function in discs and intact fruit alike.

Relationship between the nitrogenase activity and dark respiration rate ofSynechococcusRF-1

There appears to be a close association between the nitrogenase activity peaks and dark respiration peaks of a Synechococcus RF-1 culture in which an endogenous nitrogenase activity rhythm has been induced. The rise in the respiration rate usually precedes that of the nitrogenase activity by a few hours. Although there does not appear to be a fixed relationship between the size of the nitrogenase activity and respiration peaks occuring together, no convincing evidence was obtained to suggest that the periodicity of the two processes are independent.

Surface coagulation and microbial respiration in response to local advection and sea state in the North Atlantic

Microbial respiration in the upper ocean is enhanced by the coagulation of colloidal dissolved organic carbon on bubble surfaces. This large and transient enhancement of respiration by surface coagulation is typical of both coastal and oceanic waters, but is also affected by smaller-scale factors such as sea state and the local advection of water masses. These 2 factors were in evidence during bubbling experiments carried out at 40 and 44N in the western North Atlantic. At the beginning of a time series of experiments, natural bubbling associated with relatively high sea states (2 to 4.5 m swells under winds of 12 to 22 m S-') allowed only a limited potential for the enhancement of respiration by bubbling in a glass column. At lower sea states later in the time series, the advection of water with different biological characteristics produced results that were similar to those from earlier studies in bubbling columns, i.e. the induction of strong and transient peaks of microbial respiration. When rebubbling experiments were carried out after the initial time series, there appeared to be no further enhancement of respiration by bubbling once the initial, transient peak of respiration was generated. Together, the times series and rebubbling experiments suggest that sea state and local advection may be closely linked in their regulation of microbial respiration in the upper ocean.

Tomato Fruit Cell Wall Synthesis during Development and Senescence

The pedicel of tomato fruit (Lycopersicon esculentum Mill., cv ;Rutgers') of different developmental stages from immature-green (IG) to red was injected on the vine with 7 microcuries [(14)C(U)]sucrose and harvested after 18 hours. Cell walls were isolated from outer pericarp and further fractionated yielding ionically associated pectin, covalently bound pectin, hemicellulosic fraction I, hemicellulosic fraction II, and cellulosic fraction II. The dry weight of the total cell wall and of each cell wall fraction per gram fresh weight of pericarp tissue decreased after the mature-green (MG) stage of development. Incorporation of radiolabeled sugars into each fraction decreased from the IG to MG3 (locules jellied but still green) stage. Incorporation in all fractions increased from MG3 to breaker and turning (T) and then decreased from T to red. Data indicate that cell wall synthesis continues throughout ripening and increases transiently from MG4 (locules jellied and yellow to pink in color) to T, corresponding to the peak in respiration and ethylene synthesis during the climacteric. Synthesis continued at a time when total cell wall fraction dry weight decreased indicating the occurrence of cell wall turnover. Synthesis and insertion of a modified polymer with removal of other polymers may produce a less rigid cell wall and allow softening of the tissue integrity during ripening.

Expression and transport of cellulase in avocado mesocarp during ripening

Cellulase localization in the mesocarp of ripening avocado fruits (Persea americana Mill. cv. Hass) was studied by a variety of immunological methods. As localized by immunodetection on whole fruit tissue blots, cellulase first appeared near the stylar end of the fruit during the late portion of the rise in climacteric respiration. Cellulase appearance subsequently expanded outward and upward, reaching the peduncle end of the fruit by the day after the climacteric peak. Cellulase expression in cells surrounding vascular bundles was delayed relative to expression in the adjacent mesocarp. Immuno-labeled frozen sections, viewed with the light microscope, showed that cellulase appeared in both parenchyma and oil cells concom-mitantly with wall breakdown. Immunogold detection of cellulase by electron microscopy revealed labeling associated with the endoplasmic reticulum, plasmodesmata, and cell wall during the period between the late portion of the climacteric rise and the day after the climacteric peak. Cellulase appeared in the nucleus during all stages of ripening after the early portion of the climacteric rise. Immunoblot analysis of organelle fractions, isolated from avocado fruit at the climacteric peak of respiration, revealed three molecular weight forms of cellulase; a light and a heavy form found in endoplasmic reticulum-enriched fractions, and an intermediate form found in Golgi and plasma membrane-enriched fractions.

Fate and effects of sewage sludge in the coastal marine environment: a mesocosm experiment

A mesocosm experiment to assess the fate and effects of sewage sludge in the coastal marine environment was conducted over 4 mo during the summer of 1984 with 9 different treatments of sewage sludge and nutrient addtions. Evidence from setthng rate studes, accumulahons of carbon and pollutant organics and rahos of in the sediment indicated up to 83 O/O of the sludge particulate inputs settled to the bottom and up to 51 % accumulated there. While no toxicity due to organics or metals was apparent, prolonged hypoxia and even anoxia occurred in upper treatment levels. At summer temperatures, sludge particulate inputs in excess of 1 g C m-2 d-' caused these hypoxic conditions. In contrast to low primary production in low and medium sludge treatments during the last 2 mo of the experiment, the highest sludge treatment had high production. We attribute these patterns to excessive grazing pressure from zooplankton and benthlc fauna in the lower 2 treatments and hypoxia-retarded grazing in the upper treatment. In the upper treatments, peaks of produchon stimulated peaks of excessive respiration suggesting that respiration of sludge particulates was enhanced or CO-metabolized with the production of fresh organic material.

Metabolism and Metal Binding by Surface-Colonizing Bacteria: Results of Microgradient Measurements

Short-term (65-h) bacterial colonization of 0.2-mum (pore size) filters submerged in water from Lake Charlotte, Nova Scotia, was characterized by a well-defined succession of cell types, in which small cocci gave way to larger, rod-shaped cells. This succession agrees with the concept of attachment as a strategy for survival, in which inactive cocci can attach to a surface and grow into larger, rod-shaped cells by using endogenous nutrients and the nutrients accumulated at the solid-liquid interface. Analyses of oxygen and CO(2) microgradients above colonized surfaces indicated that a peak of respiration accompanied the succession of rods from cocci. CO(2) fixation then became apparent as the rods began to bind manganese and iron to their surfaces. This means that survival by attachment may not be just the province of heterotrophs. It could also be a strategy adopted by metal-oxidizing chemoautotrophs. Long-term (34-day) colonization of similar filters indicated that, while a succession of attached cell types may indeed be a natural occurrence, other factors (such as the selective grazing of larger cells) tend to obscure the development of this succession.

The influence of microtopographic heterogeneity on carbon dioxide efflux from a subarctic bog

Soil carbon dioxide efflux was measured in hummock and hollow niicrohabitals of a subarctic peat bog near Fairbanks, Alaska, during the 1983 growing season. Regardless of the presence of permafrost, hummocks showed a late June or early July peak in soil respiration followed by a gradual decrease. Hollows and wet Carex Lawns showed a gradual increase in soil respiration with no mid‐season peaks. Regression equations using soil temperature and soil moisture as independent variables explained 76% of the variance associated with soil carbon dioxide efflux. Sucrose (100 g m−2) applied to a field plot caused a significant increase in soil respiration but nitrogen (5 g m−2) did not. Sequential effects of nitrogen and phosphorus on peat respiration were demonstrated in a laboratory experiment.

Seasonal Patterns of CO2Exchange in the Shoot and Root of Loblolly Pine Seedlings

Seedlings of six full-sib families of loblolly pine were grown outdoors in clay pots for two growing seasons. Dark respiration of shoot and root and CO2 exchange of the shoot in the light were measured periodically over a temperature range bracketing ambient conditions. Both shoot and root showed different physiological responses as seasonal temperature changed, but differences among crosses were not apparent. Optimum temperatures for net photosynthesis shifted with seasonal temperatures from a high of nearly 25 C in midsummer to a low of 10 C in midwinter. Root respiration was higher at 30 C in the summer than at 30 C any time after August and higher at 0 C in the winter than during summer. Dark shoot respiration was high during initial shoot elongation and second-year bud break but fell thereafter. Rates of net photosynthesis remained high for a longer period of time before declining. A peak in root respiration occurred in October of the second year following a steady decline throughout the growing season. A period of rapid root growth in late autumn appeared to follow summer shoot growth.

Respiration and Ethylene Production of the Developing ‘Kerman’ Pistachio Fruit1

Abstract Respiration rate of whole ‘Kerman’ pistachio (Pistacia vera L.) fruit increased progressively during seed growth and development and gradually declined after the completion of seed growth. Blank (seedless) fruit, on the other hand, respired at a constant rate which was 5 to 6 times lower than that of fruit with seeds. There was no indication of a climacteric peak in respiration of fruit with seeds. Ethylene evolution from seeded fruit was not significantly different from that of blank fruit. Constant low levels of ethylene were maintained throughout the period of shell and hull dehiscence, as well as fruit maturation, indicating that this hormone is probably not involved in those processes.

Avocado Pectinmethylesterase Activity in Relation to Temperature, Ethylene, and Ripening1

Abstract Investigation of optimum conditions for extraction, titrimetric assay and activity of avocado (Persea americana Mill cvs. Fuerte, Hass) pectinmethylesterase (PME) showed maximum extraction was obtained from lyophilized mesocarp using 0.4 m NaCl. Best assay conditions required a substrate of 0.5% pectin in 0.1 m NaCl. The enzyme was released from the tissue by salt but not by nonionic detergents. The Arrhenius plot between 3 and 32°C was a straight line which indicates no involvement with membrane lipid. Incubation with air or ethylene did not affect the enzyme. PME activity declined rapidly as ripening was initiated and reached a minimum shortly before the peak in respiration and ethylene production.

ブドウ果粒の発育, 特に成熟に伴う光合成および呼吸の変化

The relationship between berry growth and changes in respiratory rate and photosynthetic CO2-assimilation rate during the development of grape berries and seeds was studied in relation to their ripening.(1) The respiratory rate of berries in terms of dry weight basis became high at an early part of Stage I and thereafter decreased rapidly. When expressed on a single berry basis, the respiratory re ate increased rapidly during Stage I through Stage III, but there was a sudden drop at veraison.(2) The rate of gross-photosynthesis expressed on a dry weight basis showed its peak during the early part of Stage I and decreased rapidly thereafter. When expressed on a single berry basis, the rate of gross-photosynthesis showed two peaks, i.e., later part of Stage I and early part of Stage III.(3) The respiratory rate per seed showed its peak at the onset of Stage II. While, the rate of respiration on a dry weight basis was highest at Stage I and rapidly decreased thereafter.These results led to an assumption that the photosynthetic activity of berries may affect their development markedly at early stages of growth, and the second peak of respiration and gross-photosynthesis may play an important physiological role in controlling the onset of their ripening.

Changes in phosphoenolpyruvate carboxylase and ribulose-biphosphate carboxylase activities during the photoheterotrophic growth of Nicotiana tabacum (CV xanthi) cell suspensions

The capacities (in vitro ∗ ∗ in vitro experiments related in this report are enzymatic capacities measurements performed with cell-free preparations studied in optimal conditions of pH and in excess of enzyme substrate. measurements) of phosphoenolpyruvate carboxylase (PEPCase) and ribulose-biphosphate carboxylase (RuBPCase) have been studied in photoheterotrophically growing cell suspensions of Nicotiana tabacum L. (cv Xanthi). The most significant observation was the different behaviour of the two carboxylases. The PEPCase capacity expressed on a g dry wt. basis rises from an initial day O value of 200–300 μmol of CO 2 fixed to 600–800 μmol during the exponential phase and then returns to the initial value during the post-exponential and stationary phases. The RuBPCase capacity was nearly constant (90–140 μmol of CO 2 fixed) throughout the growth cycle. The peak of respiration and the high PEPCase capacity during the exponential growth phase were concomitant with an active process of soluble protein synthesis. After electrophoresis of cell-free extracts, two bands of PEPCase activity (forms I and II with R m values of 0.23 and 0.38 respectively)_and one band of RuBPCase activity ( R m of 0.27) were localized on polyacrylamide gels. The densitometric profiles of soluble proteins showed a marked enrichment of PEPCase form II band during the active phase of cell division as compared to that of cells in the stationary phase of growth. Moreover, the 2-fold increase of the specific activity (μmol CO 2 fixed/h and/mg of soluble proteins) of the PEPCase during the exponential phase suggested that the enhancement of the catalytic power of this enzyme could be due to de novo protein synthesis. The biosynthesis pattern of PEPCase was essentially that of peak enzyme in contrast with RuBPCase which showed only slight variations over the growth cycle.

異なる温度での白肉桃の追熟生理

To study the postharvest physiology of white peaches, “Okubo” and “Hakuho” peaches were held at 10°C, 15°C, 20°C, 25°Cand 30°C, respectively. Respiration, ethylene evolution, firmness, readiness of peeling, sugars, edible quality and other components of ripening were determined during ripening.1. A more rapid increase and a higher peak in ethylene evolution, an earlier peak in respiration and a more rapid attaining of readiness of peeling were observed in “Okubo” peaches ripened at 20°C than in those ripened at 25°C, whereas softening proceeded at 20°Cas rapidly as at 25°C. A few days after the respiratory climacteric peak, “Okubo” peaches ripened at 20°Cand 25°C showed a peak in ethylene evolution, followed by a rapid decline. At the respiratory climacteric peak, “Okubo” peaches were fully ripe at 20°Cand over-ripe at 25°C.2. Higher rates of ethylene evolution on the first day after harvest and a more rapid rate of softening were observed in “Hakuho” peaches than in “Okubo” peaches. An earlier peak in respiration and a more rapid rate of softening were observed in “Hakuho” peaches ripened at 25°C than in those ripened at 20°C, whereas ethylene evolution increased at 25°C as rapidly as at 20°C.3. Gradual increases in respiration and ethylene evolution and delayed softening and attaining of readiness of peeling were observed in peaches ripened at 10°C and 15°C. “Okubo” peaches ripened at 10°C and 15°C attained about the same rates of ethylene evolution and the same degrees of softening and peeling as those ripened at 25°C, while poor flavor developed at 10°C. The rates of ethylene evolution at 15°C remained relatively constant for a long period after the respiratory climacteric peak, as compared with those at 25°C. Full ripening required about three times at 10°C and two times at 15°C as much time as at 25°C.4. Ethylene evolution was suppressed and tended to decrease during ripening at 30°C. Although the respiratory climacteric failed to develope at 30°C, softening proceeded in “Hakuho” peaches as rapidly as at 25°C and it proceeded in “Okubo” peaches at a slightly slower rate than at 25°C for a few days after harvest and subsequently at approximately the same rate.5. The reducing sugar content increased gradually at 30°C during ripening. The increase in soluble pectin content seemed to be significantly related to the degree of softening.6. These data suggest the following. The ripening temperature influenced flesh color, rates of ethylene evolution and softening, and certain other ripening phenomena. Ethylene stimulated an occurrence of a respiration climacteric and other ripening reactions such as softening and readiness of peeling. Respiration, ethylene evolution, softening, readiness of peeling and other ripening reactions proceeded relating to each other during ripening, but these interrelations were influenced by factors such as variety and ripening temperature.

メロン果実の貯蔵に関する研究 (第2報)

The changes of respiration rate and ethylene production of melon fruits in the course of ripening after harvest were investigated with reference to cultivars and harvest maturity. Four cultivars of melon fruits of Raifu, Prince, Elizabeth, and Honey King were harvested at different stages of maturity and stored at 20°C.1. All of the Raifu melons harvested at three different ages of 28, 32, and 34 days after anthesis showed a typical climacteric pattern of respiration. Ethylene production changed in parallel with respiration rate during the course of the climacteric, and the time of the peaks of both coincided, however, a little but definite increase of ethylene production was detected prior to the onset of respiration rise. The older the age at harvest time became, the sooner the peaks of ethylene and respiration appeared, and the greater the magnitude of ethylene peak became.2. Prince melon did not show the typical and complete climacteric pattern of respiration, but there was a rise of ethylene production without corresponding rise of respiration. The early-harvested fruits, 21 days after anthesis, showed a climacteric-like rise of respiration, but the time of the increase did not coincide with that of ethylene production. The fruits harvested 24 days after anthesis showed a trend of gradual decrease of respiration, but did a rise of ethylene production shortly after harvest.3. Elizabeth melons showed a similar change to those of Prince melons, that is, while respiration rate decreased gradually throughout the experimental period, ethylene production exhibited a peak 3-4 days after harvest.4. In Honey King melons, the respiratory pattern was a monotonous drift downwards. Ethylene production in the fruits harvested 40 days after artificial pollination was slightly detected only when the fruits reached to a senescent stage, and that in the fruits harvested 55 days after pollination occurred at a very low level through approximately 10 days after harvest, and did not at progressive stage of over-ripe. Abnormally softened fruit called as “fermented fruits” showed a rise of respiration rate with a corresponding rise of ethylene production and tissue breakdown.5. It is supposed that the striking difference among cultivars in the respiratory pattern of harvested fruits would relate to the ripening characteristics and the storage life of these fruits. Prince, Elizabeth, and Honey King melons have a comparatively good shelf life and they attain ripening gradually without an appreciable respiratory peak, while in Raifu melon having poor shelf life ripening occurs rapidly with a climacteric rise of respiration.

Method for Simultaneous Measurement of Radioactive and Inactive CO2 Evolved from Soil Samples During Incubation with Labeled Substrates

An apparatus is described which allows the simultaneous, continuous, and highly sensitive analysis of inactive and radioactive CO(2) evolved from C-supplemented soils or other materials. The apparatus consists of a control unit, a commercially available conductometric CO(2) analyzer, and fraction collector. A number of model experiments were conducted to demonstrate the potentials of the apparatus. These included analysis of the time course of priming action, when C-glucose was added to soil, separation of CO(2) respiration peaks caused by simultaneous degradation of radioactive and inactive soil supplements, and study of the effects of a fungicide, Benomyl, on degradation of C-labeled glucose. In the last experiment, partial degradation of the fungicide could also be followed.

Trypanosoma lewisi: Oxygen uptake by whole cells and trypanosomal mitochondria

1. 1. Three experimental protocols were completed to compare the respiratory activity of mitochondria and whole cells of Trypanosoma iewisi. 2. Oxygen uptake was measured endogenously and with the substrates, glucose, glutamate, and lactate. 3. Mitochondria in general respired less as compared to the living cells. The peak of respiration was observed around day 10. Mitochondria utilized glucose and glutamate starting on day 7 and day 11 respectively. 4. No statistically significant differences over the endogenous rates were obtained with lactate, although small differences were obtained throughout the periods of observation. 5. Whole cells gave a better response both endogenously and with the substrates. The response to glucose and glutamate started early in the infection and continued through day 14. Lactate responses were similar to those observed with mitochondria. 6. Simultaneously, trypanosome populations were enumerated. The populations showed a steady increase from day a, reaching a crisis on day 10. This was followed by a gradual decline until day 30, when no trypanosomes were seen in the host blood.

The Climacteric in Ripening Tomato Fruit

Phosphofructokinase is identified as the regulator reaction activated at the onset of the climacteric rise in respiration of the ripening tomato fruit (Lycopersicon esculentum Mill). The concentration of ATP in the fruit increases to a maximum value after the climacteric peak of respiration is past. Orthophosphate is proposed as the most probable activator of phosphofructokinase in the ripening fruit.Fifteen hours after infiltrating tomato fruit with orthophosphate, the rate of respiration increased and remained high until the end of the experiment, 45 hours after infiltration. In experiments where tomato plants were grown at various nutrient levels of P, the rate of respiration when fruit harvested at the mature-green stage reached the respiratory climacteric was correlated with the concentration of orthophosphate in the fruit at the end of the experiment. These results are consistent with the hypothesis that stimulation of phosphofructokinase through increasing concentration of orthophosphate in the cytoplasm of the fruit contributes to the climacteric rise in respiration.

Respiratory Climacteric and Chemical Changes in the Mango Fruit, Mangifera indica L.1

Abstract The parameters for optimum maturity of fruit of ‘Pairi’ variety mango, harvested near Mysore from 1964 to 1969, have been found to be 260 ± 20 g in weight, olive green surface color, and outgrown shoulders. In addition, pH and color of the pulp in terms of chromaticity coordinate x were useful indices. Other parameters were not consistent. Respiration climacteric maximum was delayed in immature fruits and advanced in over-mature fruits. Fruits of optimal maturity recorded the climacteric maximum on the 9th day ± 1 at ambient storage of 26 ± 2°C and 45–65% RH. Sugar accumulation was maximum at about the time of the climacteric peak in respiration and sucrose was predominant. The chemical composition of the fruit was more or less similar over several seasons and harvests.