Changes in respiration of mitochondria isolated from cotyledons of ethylene-treated pea seedlings

Treatment of intact, germinating pea (Pisum sativum L. cv. Homesteader) seedlings with ethylene enhanced the cyanide-resistant respiration of mitochondria isolated from the cotyledons. The level of enhancement depended on the concentration of ethylene. Thus, exposure to 0.9 μl·l(-1) of ethylene in air for days 4-6 of germination had little effect on cyanide-resistant respiration, while exposure to 130 μl·l(-1) increased it from 10 to 50 nmol O2·min(-1)·(mg protein)(-1). The length of exposure to ethylene also affected the degree of enhancement. According to some literature data, lipoxygenase (EC 1.13.11.12) activity can be mistaken for cyanide-resistant respiration, but in our preparations of purified pea mitochondria ethylene had no effect on lipoxygenase activity, nor did the gas disrupt the outer mitochondrial membrane. Bahr and Bonner plots of respiration in the presence of salicylhydroxamic acid (SHAM) indicated that ethylene did not affect respiration proceeding via the cytochrome pathway. Thus, increases in total respiration in mitochondria from cotyledons of ethylene-treated pea seedlings reflect increases in cyanide-resistant respiration.

Reproductive behavior of female rats treated with ethanol on postnatal days 1-7 or 8-14

Effects of postnatal administration of ethanol upon adult reproductive behavior of female rats was investigated in the two studies reported here. Ethanol, in a nutriment vehicle, was administered by intragastric intubation to avoid confounding effects of underfeeding. Estrous cycles appeared typical in all animals. Treatment groups did not differ in fertility nor with respect to litter sizes or sex ratios of subsequent litters.

Ultrastructure of aesthetasc innervation and external morphology of the lateral antennule setae of the spiny lobster Panulirus interruptus (Randall)

Six types of setae and one type of cuticular depression were examined on the lateral antennule of the spiny lobster Panulirus interruptus using scanning electron microscopy. The organization and ultrastructure of the innervation of the most numerous setal type, the aesthetasc, were investigated using light- and transmission electron microscopy. Each aesthetasc is innervated by approximately 300 bipolar neurons whose sensory dendrites penetrate the hair and extend toward the tip, and whose axons project towards the central nervous system. The neuronal somata and two types of glia form a cluster within the antennular lumen. The inner sheath-cell somata encircle the dendritic tract distal to the sensory somata. These cells appear to extend distal processes which wrap the dendritic tract to the base of the aesthetasc. Elongate outer sheath cells are interposed between the glia-wrapped dendritic tract and the hypodermis which underlies the antennule cuticle. A continuous investment of neural lamella separates the hypodermis, the entire cluster of somata, and sensillar nerve from the antennule lumen. The organization of the neuronal somata and their association with outer and inner sheath cells in this marine species appear similar to those of crustaceans from freshwater and terrestrial habitats.

Fever in infants less than two months of age: spectrum of disease and predictors of outcome

Four hundred thirty-four febrile infants two months of age or younger were evaluated in the emergency departments of five major teaching hospitals over a one-year period. A culture-proven bacterial infection was present in 3.5% of the infants; bacteremia was detected in 3.3%. Bacterial meningitis was present in 2.4%, and aseptic meningitis was noted in 13.4%. Twenty-one percent had clinically apparent serious disease including pneumonia, otitis media, and gastroenteritis with dehydration. Six variables (age less than 1 month, lethargy, no contact with an ill individual, breast-feeding, total polymorphonuclear greater than or equal to 10,000/mm3 and band count greater than or equal to 500/mm3) were correlated with bacterial infection by step-wise discriminant analysis. However, these findings were neither sensitive nor specific enough to be clinically useful. Management varied, and 62% of the infants were hospitalized. Fifty-four percent, some of whom were managed as outpatients, received antibiotics. Febrile infants two months of age or younger require a comprehensive emergency department assessment, including appropriate laboratory studies (CBC, differential, urinalysis and culture, lumbar puncture, and blood culture), since 3.5% have bacterial infection that may be life-threatening. Hospitalization is warranted if the infant appears ill, laboratory studies indicate serious infection, or follow-up care is uncertain.

A strategy of malaria control

A field investigation was designed to determine the feasibility of a single annual application of DDT which could fulfil the objectives of malaria control. The concept of a single spraying cycle would eliminate the risks and disadvantages associated with the standard methodology of two spraying cycles, and would result in logistic and economic gains to the country. The timing of the spraying cycle in this modified control methodology is based on the determination of the malaria season solely from entomological data. Details of the field investigation for the years 1974 and 1975, the parameters for calculation of vectorial capacity, estimates of the relative malaria receptivity within the study area, and determination of the malaria season of six months' duration have already been published. The present paper applies the concept of a single spraying cycle to the findings of the investigation and discusses the implementation of the strategy.

Reverse salt gradient chromatography of tRNA on unsubstituted agarose. I. Variations in elution profile and evidence for two fractionation mechanisms

E. coli tRNA was fractionated by the application of ammonium sulphate reverse gradients to Sepharose 4B. Variations in elution profile were partly attributable to differences between batches of Sepharose. The profile also varied with column length and gradient parameters. This suggests the existence of two distinct mechanisms which do not separate different tRNAs in the same sequence. The first mechanisms, believed to be interfacial precipitation, releases tRNAs progressively as the salt concentration is reduced. A second mechanism introduces adsorptive retardation in which molecules lag behind the solvent. This process, widely believed not to be important in the chromatography of macromolecules with multiple binding sites, is in the present case mainly responsible for the improved resolution of peaks on passage down a long column. Isocratic (constant-salt) fractionation is also feasible. The Sepharose batch variation affects the second mechanism more than the first.

Reverse salt gradient chromatography of tRNA on unsubstituted agarose. II. Further study of binding mechanisms

The existence of two mechanisms in the fractionation of tRNA on Sepharose 4B, using reverse gradients of ammonium sulphate, was confirmed by comparing yeast and E. coli tRNAs, and by extending the range of conditions used. The difference in elution range between the two kinds of tRNA is attributable mainly to variations in tight binding rather than adsorptive retardation. Variations of pH or of temperature produce not only changes in peak distribution, but overall shifts in the elution profile. The shifts correlate closely with changes in the solubility of tRNA in free solution, confirming that tight binding is associated with interfacial precipitation. On the other hand the degree of adsorptive retardation, as indicated by the difference between elution profiles from long and short columns, is quite similar under all conditions. It is if anything slightly greater at 25 degrees C than at 5 degrees C, implying a binding mechanism analogous to hydrophobic bonding. Binding-equilibrium studies suggest that the effect is related to the formation of a monolayer of tRNA on the agarose threads of matrix. Experiments with hydroxyapatite also demonstrate adsorptive retardation, comparable in degree to that observed with Sepharose. This indicates that the effect may be much more important in ion-exchange chromatography than is normally assumed.

Reverse salt gradient chromatography of tRNA on unsubstituted agarose. III. Physical and chemical properties of different batches of Sepharose 4B

Four batches of Sepharose 4B, which gave differing elution profiles in reverse salt gradient chromatography of tRNA, were analysed by a number of techniques. Charged groups were estimated from infrared spectra, and gave 0.04-0.05 sulphates and 0.18-0.27 carboxyls per disaccharide. Nuclear magnetic resonance showed the presence of 0.21-0.23 6-O-methyl substituents per disaccharide. The mass concentrations of the beads in aqueous suspension (including agarose-bound water) ranged from 4.7 to 5.0%. High-resolution scanning electron microscopy demonstrated a three-dimensional network of threads with diameters between 2 and 20 nm. None of these properties varied appreciably between batches. There was, however, a variation in the size distribution of beads. In two batches which induced a high degree of adsorptive retardation during chromatography, very few beads exceeded 100 micrometers in diameter; two other batches which gave inferior retardation had a preponderance of somewhat larger beads. The significance of this observation remains unclear.

The effect of polybrominated biphenyl on infants and young children

The effects of PBB on 33 children born between September 1, 1973, and December 31, 1975, were evaluated in September, 1977. These children, born to families who lived on quarantined farms, were compared to 20 children who were not exposed to PBB. The birthdate interval was selected to obtain children who were exposed in utero or in early infancy or both, the two time periods when damage to developing tissues and organ systems should have been maximal. The results of these studies failed to identify any effects on physical growth, physical examination, or neurologic assessment, although the parents indicated by historical review that the exposed children had had more illnesses, especially respiratory, than had the control children. There were some indications of an inverse relationship between PBB fast level and performance on selected developmental tests.

Interparticle effects in low-angle x-ray and neutron diffraction from chromatin

Published diffraction data are critically reviewed, and replotted in a new way to show the variation with concentration of the 8- to 25- nm diffraction maximum. Most of the early data are found to be consistent with a single model for a liquid-type array of mutually repulsive particles, whose molecular weight is calculated to be that of a nucleosome or possibly a dimer. The data for all but the highest concentrations, where distortion due to dehydration is possible, support no particular model for the higher-order coiling of chains of nucleosomes, and cannot be used to support models for "native" chromatin. Only in the presence of excess salts or after isolation with polyamines is there aggregation in solution of nucleosomes, which then give peaks at 11 and 5.5 nm that do not change much with concentration. Recent work by the authors confirms that under some conditions nucleosome undergo a transition to a state whose diffraction is consistent with hexagonal packing of extended DNA to which histones are still attached. This state is probably responsible for much of the strong 2.7-nm peak previously obtained from certain samples, which was in some cases assigned to nucleosome structure. Only the peak at 3.7 nm is clearly attributable to the form factor of the isolated native nucleosome.

An octacalcium phosphate intermediate in the synthesis of chromatographic hydroxyapatite

In the laboratory synthesis of hydroxyapatite for liquid column chromatography different procedures give varying amounts of a transient intermediate, identified by X-ray diffraction as octacalcium phosphate. The intermediate is most abundant in a recently-developed method involving conversion from brushite at neutral pH; well-crystallized hydroxyapatite is then produced without the boiling previously found necessary. The results are relevant to hydroxyapatite biosynthesis, where a similar intermediate has been postulated. Methods are described for the laboratory synthesis of octacalcium phosphate.

ATPase Activity of Pea Cotyledon Submitochondrial Particles: ACTIVATION, SUBSTRATE SPECIFICITY, AND ANION EFFECTS

Submitochondrial particles freshly prepared by sonication from pea cotyledon mitochondria showed low ATPase activity. Activity increased 20-fold on exposure to trypsin. The pea cotyledon submitochondrial particle ATPase was also activated by "aging" in vitro. At pH 7.0 addition of 1 millimolar ATP prevented the activation. ATPase of freshly prepared pea cotyledon submitochondrial particles had a substrate specificity similar to that of the soluble ATPase from pea cotyledon mitochondria, with GTPase > ATPase. "Aged" or trypsin-treated particles showed equal activity with the two substrates. NaCl and NaHCO(3), which stimulate the ATPase but not the GTPase activity of the soluble pea enzyme, were stimulatory to both the ATPase and GTPase activities of freshly prepared submitochondrial particles. However, they were stimulatory only to the ATPase activity of trypsin-treated or "aged" submitochondrial particles. In contrast, the ATPase activity of rat liver submitochondrial particles was stimulated by HCO(3) (-), but inhibited by Cl(-), indicating that Cl(-) stimulation is a distinguishing property of the pea mitochondrial ATPase complex.

Biting prevalence and malaria transmission patterns in the Anopheles punctulatus complex (Diptera: Culicidae) in Papua New Guinea

Seasonal prevalence and malaria transmission patterns of Anopheles farauti, An. punctulatus and An. koliensis were studied in two coastal and two inland villages in the Madang district of northern Papua New Guinea. The monthly manbiting rates (average biting density of vector mosquitoes per man per night) were observed over a two-year period to establish typical seasonal prevalence patterns. Observations on the frequency of feeding and the human blood index were combined to derive the manbiting habit. A daily survival rate was determined from the dissection of mosquito ovaries by Polovodova's age-grading method. The extrinsic cycle in the mosquito was not observed, and the value for this parameter was extracted from the literature. All parameters were combined to estimate the monthly variations in vectorial capacity of each of the vector species, and the vectorial capacities of the individual species were added together to give a total monthly vectorial capacity of the punctulatus complex in each locality. The results showed that malaria transmission can be perennial, with a period of more intense transmission between August and January in the southern area, and between September and February in the northern. A period of very low transmission can be expected between February/March and July/August.

Oxidative phosphorylation in pea cotyledon submitochondrial particles

Mitochondria and submitochondrial particles (SMP) from pea cotyledons were shown to catalyze oxidative phosphorylation as measured by (32)Pi uptake into phosphate esters. ATP synthesis was sensitive to the electron transport inhibitor KCN, the uncoupler carbonyl cyanide m-chlorophenylhydrazone, and the coupling factor inhibitor oligomycin. Experiments with the adenine nucleotide translocator inhibitor atractyloside indicated the SMP were inside-out. Mersalyl completely inhibited ATP synthesis by SMP, and a separate experiment indicated that mersalyl has a direct effect on the ATPase complex. The kinetics of ATP synthesis indicated a high affinity for phosphate (K(m) = 0.18 millimolar). ADP kinetics gave a biphasic curve with K(m) values of about 4.8 and 160 micromolar. O(2) uptake and ATP synthesis had a pH maximum of 7.6 while the ratio of micromoles phosphate esterified to microatoms O(2) taken up was highest at pH 7.2. Sodium chloride inhibited both ATP synthesis and O(2) uptake but stimulated the ATPase reaction. The SMP also catalyzed a slow ATP-phosphate exchange reaction.

Open evaluation of labetalol in the treatment of angina pectoris occurring in hypertensive patients

1 In nine hypertensive subjects with angina pectoris, labetalol diminished the incidence of chest pain occurring spontaneously or induced by exercise. 2 Labetalol lowered BP in all subjects. 3 Exercise tolerance at maximum levels was increased by labetalol. 4 Improved cardiac function by labetalol may be related to decreased afterload on the left ventricle, and diminished oxygen utilization by the myocardium.

Evolution of ethylene by Saccharomyces cerevisiae as influenced by the carbon source for growth and the presence of air

Effects of the carbon source and oxygen on ethylene production by the yeast Saccharomyces cerevisiae have been studied. The amounts of ethylene evolved by the yeast culture were less than those detected in the blank (an equal volume of uninoculated medium), suggesting a net absorption of ethylene by the yeast cells. Addition of glucose to the lactate-grown yeast culture induced ethylene production. This glucose-induced stimulation of ethylene production was inhibited to a great extent by cycloheximide. Results suggested that the yeast cells in the presence of glucose synthesized an ethylene precursor and passed it into the medium. The conversion of this precursor to ethylene might be stimulated by oxygen. The fact that ethylene was produced by the yeast growing anaerobically and also by respiration-deficient mutants isolated from the wild-type yeast suggested that mitochondrial ATP synthesis was not an absolute requirement for ethylene biogenesis.

Oligomycin-sensitive ATPase of Submitochondrial Particles from Corn

To test the hypothesis (Plant Physiology 59: 155-157) that monocotyledons contain a unique oligomycin-insensitive ATPase, we prepared submitochondrial particles and a soluble fraction from sonicated corn mitochondria (Zea mays L. cv. Earliking). Although the ATPase activity of the whole sonicate was relatively insensitive to oligomycin, the corn submitochondrial particles possessed an ATPase activity that was nearly completely inhibited by oligomycin, and was activated by trypsin. This ATPase is similar to that from other sources (plants, animals, and microorganisms). The soluble fraction also contained an active ATPase, which was inhibited by azide and stimulated by sodium chloride and trypsin. The soluble fraction differed from other F(1)-ATPases in that it was cold-stable.

Effects of ethylene on the metabolism of Saccharomyces cerevisiae

Supply of exogenous ethylene to lactate-grown yeast initially accelerated the rate of ethanol production from glucose, but later reduced the rate, with the overall effect being to reduce the total ethanol production. The rate of ethanol production by ethylene-treated yeast was not changed by removal of metabolic carbon dioxide. However, if CO2 was allowed to build up in the absence of applied ethylene, the ethanol production decreased. Ethylene increased the activities of a number of pentose phosphate and glycolytic pathway enzymes. The largest increase in activity was observed for phosphofructokinase (EC 2.7.1.11), regulatory enzyme of the glycolytic pathway. After an initial stimulation, glucose (and also 3-O-methyl glucose) uptake was reduced by ethylene. Ethylene appears to inhibit non-competitively the glucose transport system.

L-methionine as an ethylene precursor in Saccharomyces cerevisiae

L-Methionine induced production of ethylene by Saccharomyces cerevisiae growing in lactate medium. The production induced by L-methionine was inhibited by pyruvate, and elevated by glucose. Labeled ethylene was produced when L-[U-14C]methionine, but not [U-14C]glucose, was fed to the yeast. The mutant S. cerevisiae G1332 (ade-, met-) did not produce significant amounts of ethylene unless L-methionine was added. Thus L-methionine acts as a precursor of ethylene in S. cerevisiae. The role of glucose appears to be other than as a precursor.

Optimum pH and ionic strength for the assay of cytochrome c oxidase from pea cotyledon mitochondria

Cytochrome c oxidase (EC 1.9.3.1) has been solubilized by use of the nonionic detergents were determined for the oxidation of ferrocytochrome c in air. The results indicate that the plant cytochrome c oxidase resembles mammalian preparations in its sensitivity towards ionic strength and pH of the assay buffer.

Partial characterization of a soluble ATPase from pea cotyledon mitochondria

A partially purified soluble ATPase (ATP phosphohydrolase, EC 3.6.1.3) from pea cotyledon mitochondria was characterized. Inhibition patterns with azide, NaF, and cold, and a stimulation by 2,4-dinitrophenol were typical of F1-ATPases from mammalian mitochondria. The enzyme hydrolysed GTP, ITP, and ATP, but not CTP, UTP, ADP, or IDP. ATPase and ITPase activities were strongly inhibited by ADP and to a lesser extent by IDP. Distinctive properties of the pea mitochondrial enzyme were activation by high concentrations of CaCl2 and stimulation by NaCl.

Characteristics of potassium ion transport in pea cotyledon mitochondria isolated by a zonal technique

Methodology was developed for measurement of K+ transport in pea cotyledon mitochondria isolated by zonal centrifugation. The valinomycin-mediated transport process required respiratory energy from Krebs cycle intermediates and was completely reversible in the absence of oxygen. The rate and extent of uptake were dependent on the presence of proton-conducting anions (with acetate plus phosphate being most effective), well-coupled mitochondria, and on the K+ concentration.

Relationship of potassium ion transport and ATP synthesis in pea cotyledon mitochondria

Simultaneous monitoring of ATP synthesis and K+ movements across pea mitochondrial membranes revealed information about the competition of the two processes for mitochondrial energy. In the presence of valinomycin and at low extramitochondrial K+ concentration, ADP could be phosphorylated rapidly. This occurred with a decrease in net potassium ion uptake. At higher external K+ concentrations respiratory energy was unavailable for ATP synthesis and only a portion of added ADP could be phosphorylated within a reasonable time. Magnesium ions were shown to have an inhibitor effect on the K+ uptake, and stimulated a greater rate of ATP synthesis. When valinomycin and ADP were added simultaneously so that phosphorylation of the ADP and enhancement of K+ uptake could complete for mitochondrial energy, K+ uptake was preferred over ATP synthesis.

Computer interviewing of patients with epilepsy

Epilepsy histories obtained by the computer interview were similar in substance and detail to histories recorded by house staff and attending physicians. In general, more information was obtained by the computer, and negative findings were consistently recorded by the computer. For potentially embarrassing questions, the computer may obtain more accurate information (Slack and Van Cura, 1968b). This might explain the contradictions concerning incontinence and medication. This preliminary study suggests that computer interviewing can provide a reliable method for obtaining epilepsy histories. The study also pointed out where changes in question wording and branching logic would improve the computer interview. These changes are being incorporated into the second version of the epilepsy interview. We hope computer-based interviewing will prove useful to patients and physicians in the diagnosis, treatment, and study of epilepsy.

Exaggerated phosphaturic response to circulating parathyroid hormone in patients with familial X-linked hypophosphatemic rickets

To determine whether the phosphaturic response to circulating parathyroid hormone (PTH) is exaggerated in patients with familial x-linked hypophosphatemic vitamin D-resistant rickets (FHR), we examined the phosphaturic response to parathyroid extract (PTE) (administered intravenously in the posthypercalcemic state) in two unrelated adult hemizygotes with FHR. In these two patients whose plasma concentration of PTH was normal (determined by radioimmunoassay). neither vitamin D nor phosphate therapy had been given during the past 10 yr. Two normal men and a hypophosphatemic man with intestinal malabsorption, hypocalcemia, and osteomalacia served as control subjects. In all subjects, calcium gluconate was adminstered intravenously from 6 p.m. to 12 midnight at a rate that maintained the concentration of serum calcium at 13-15 mg/100 ml during the administration of calcium. When normocalcemia had recurred the next morning, and the plasma PTH concentration and urinary excretion of cyclic 3', 5'-AMP were reduced. PTE was administered intravenously at successively increasing rates of 0.1, 0.4, and 0.8 U/kg per h, each rate lasting 90 min. Minutes after the initiation of PTE in the affected hemizygotes, fractional excretion of filtered phosphate increased from negligible values to values strikingly greater than those of similarly studied control subjects and plateaued at strikingly greater values throughout further administration of PTE. This phenomenon of exaggerated phosphaturia could not be attributed to volume expansion, decreases in serum concentration of calcium during the study, differences in percent of administered calcium retained, or hemodynamic changes. Only the phosphaturic response to PTE appeared to be exaggerated. At any cumulative dose of PTE, urinary excretion of cyclic 3', 5'-AMP in the hemizogytes was indistinguishable from that of control subjects. The findings in this study suggest that in patients with FHR, circulating PTH is required for the genetically transmitted abnormality to be physiologically expressed as a reduction in net renal reabsorption of phosphate, and that this physiological expression of the genetic abnormality is expressed fully at normal or nearly normal circulating levels of PTH.

Effects of ethylene, carbon dioxide, and ethylene - carbon dioxide mixtures on the activities of "membrane-containing" and "highly purified" preparations of adenosine triphosphatase from pea-cotyledon mitochondria

From pea-cotyledon mitochondria two types of adenosine triphosphatase (ATP phosphohydrolase) were prepared, "membrane-bound" and "highly purified." Activities of both enzyme preparations were dependent on Mg2+ and were stimulated by Na+ and K+. Ethylene had no effect on the activity of either the "membrane-bound" or the "highly purified" enzyme. Ethylene – carbon dioxide – air mixtures stimulated the activity of the "membrane-bound" but not the "highly purified" ATPase, when Na+ and K+ were present. When these ions were absent, the gas mixture greatly increased the activities of both enzyme preparations. The work shows a direct action of ethylene on an enzyme (mitochondrial ATPase), its dependence on the presence of certain levels of CO2, and the augmentation of the ethylene–CO2 effects by the presence of phospholipids.

Food additives

Food additives are discussed from the food technology point of view. The reasons for their use are summarized:

(1) to protect food from chemical and microbiological attack;

(2) to even out seasonal supplies;

(3) to improve their eating quality;

(4) to improve their nutritional value.

The various types of food additives are considered, e.g. colours, flavours, emulsifiers, bread and flour additives, preservatives, and nutritional additives. The paper concludes with consideration of those circumstances in which the use of additives is (a) justified and (b) unjustified.

Preparation and properties of purified (Na+ plus K+)-stimulated mitochondrial ATPase from germinating pea seeds

An ATPase preparation from pea cotyledon mitochondria was purified by protamine sulfate, ammonium sulfate precipitations, and preparative gel electrophoresis. The ATPase activity was dependent upon Mg2+ and stimulated by Na+ + K+. The optimum pH of the enzyme was 8.0. A ratio of 5 to 1 between Na+ and K+ must be maintained to show maximum ATPase activity. Although no detectable amounts of phospholipids were found to be associated with the purified enzyme, it was activated by Na+ and K+ ions. Addition of phosphatidylserme and phosphatidylinositol resulted in increased activity of the (Na+ + K+)-stimulated enzyme, suggesting that the purified enzyme has probably lost most of the membrane complement during purification.

Structural Development during Germination of Different Populations of Mitochondria from Pea Cotyledons

The crude mitochondrial fraction from pea cotyledons can, from days 1 to 7 of germination, be separated into three fractions by sucrose density gradient centrifugation. When seeds were grown in water (control) or cycloheximide (120 micrograms per milliliter of medium) for 4 days, the originally different populations of mitochondria acquired a uniform density and separated together in band 1 (density, 1.205 grams per milliliter). The oxidative and phosphorylative activities of mitochondria obtained from 4-day-old control and 4-day-old cycloheximide-treated pea seeds were the same. However, mitochondria from pea seeds that were grown in d-threo-chloramphenicol (1.5 milligrams per milliliter of medium) or erythromycin (0.5 milligram per milliliter of medium) for 4 days separate into three bands (fully developed mitochondria in the top band [band 1] and partially developed mitochondria in the lower two bands [bands 2 and 3]). Separation patterns and oxidative and phosphorylative activities were the same for mitochondria separated from 4-day-old cotyledons treated with d-threo-chloramphenicol or erythromycin and from 1-day-old cotyledons grown in water. This indicated that these inhibitors prevented the partially developed mitochondria originally in bands 2 and 3 from developing further. In contrast, cycloheximide did not seem to interfere with the mitochondrial structural development. These results along with those obtained from the experiments on the effects of d-threo-chloramphenicol, erthromycin, and cycloheximide on (14)C-leucine incorporation into mitochondrial membrane proteins suggest that the increase in mitochondrial activity during germination may be a result of structural development (membrane synthesis) in pre-existing mitochondria.