Metabolic Activity of Isolated Leaf Cells of Phaseolus vulgaris in Relation to Leaf Development

Mesophyll cells were isolated from primary leaves of 5- to 21-day Phaseolus vulgaris plants. The rate of photosynthesis and respiration, and RNA, protein, and lipid synthesis was determined for these cells. Appropriate ¹⁴C substrates and product purification procedures were used for each process prior to liquid scintillation counting. The size of the leaves increased about 5-fold between days 5 and 11, and then remained relatively constant. The greatest increase in size occurred between days 5 and 6. The age of the leaf from which the cells were isolated had a pronounced effect on the rate of all of these processes. The largest changes occurred during the period of leaf expansion (days 5-11). Initially the rate of RNA, protein, and lipid synthesis increased rapidly, maintained a maximum rate for only 1 day (day 6 or day 7), and then declined. The rate of photosynthesis increased more slowly reaching a maximum at day 9, remained relatively constant until day 15, and then declined. The rate of respiration decreased during the first 4 days to low level which was maintained throughout the experiment. The time course patterns of these biochemical processes in isolated cells were similar to those which have been reported for intact leaves. It seems that isolation of leaf cells does not modify their metabolic activity.     

Offspring and sex ratio are independent of sperm management in Eupelmus orientalis females

Sperm stocks in both males and females of the parthenogenetic wasp Eupelmus orientalis were investigated at various points during reproduction and compared to the progeny of females in controlled conditions. One day-old virgin males had approximately 5500 sperm, and from a total of about 1697 sperm transferred per copulation, 21% are stored in the spermathecae by females 24 hours after mating. At the end of the egg-laying period (at least 42 days), 2/5 of the initial amount of sperm remained in this storage organ. This decrease (from approximately 350 to 150) occurred essentially during the first 21 days of egg-laying activity, indicating that the majority of sperm stored were used during this period. Between 21 days and the end of fertile life, the number of sperm remained constant. The mean offspring production throughout reproductive life after one mating was 153, with 56.5% of the daughters laid at the beginning of the laying activity. Sex ratio was entirely female biased during the first 15 days (mean=0.65), then it decreased and became nearly equal after 20 days. Present results propose that females maximize the production of daughters i.e. of inseminated eggs until the 20th day and after this time lay as many daughters and sons despite their still having stored sperm. Physiological constraints due to ageing are proposed to explain this phenomenon.     

Stability of enzymes in starving Arthrobacter crystallopoietes.

Cell-free extracts prepared from spherical and rod-shaped cells of Arthrobacter crystallopoietes were assayed for enzymes during various periods of starvation. The level of NADH oxidase dropped to 20 and 30%, respectively, in spherical and rod-shaped cells during the first 1 to 2 days of starvation and then remained constant for 9 days. Catalase activity decreased continuously and reached a low level in 9 days. Enzymes involved in glucose metabolism and the tricarboxylic acid cycle were stable for the duration of the experiment (about 1 week). Succinic dehydrogenase, fumarase and aconitase were stable during 21 days of starvation, which is the longest time enzymes have been shown to be stable in any bacterium under conditions of total starvation.     

Development of Microbodies in Sunflower Cotyledons and Castor Bean Endosperm during Germination

In cotyledons of sunflower seedlings glyoxysomal and peroxisomal enzymes exhibit different rates of development during germination. The total activity of isocitrate lyase, a glyoxysomal marker enzyme, rapidly increased during the first 3 days, and then decreased 89% by day 9. Exposure to light accelerated this decrease only slightly. The specific activity of glyoxysomal enzymes (malate synthetase, isocitrate lyase, citrate synthetase, and aconitase) in the microbody fraction from sucrose density gradients increased between days 2 and 4 about 2- to 3-fold, and thereafter it remained about constant in light or darkness.     

Blood dopamine beta-hydroxylase activity and noradrenaline levels in the developing white rat.

Dopamine beta-hydroxylase (DBH) (3,4-dihydroxyphenylethylamine, ascorbate:oxygen oxidoreductase (beta-hydroxylating) (EC 1.14.17.1) activity in serum of blood obtained by decapitation of white rats at 19, 20, and 21 days in utero, immediately after birth, and postnatally to 70 days, was measured. Noradrenaline (NA) and DBH in plasma from undisturbed, cannulated, postweaning rats were also assayed. During the last few days in utero and the first 2 postnatal days serum DBH activity tripled and then remained elevated during the suckling period. Upon weaning, serum DBH activity declined at first precipitously and then more slowly, until the adult level was reached around 70 days of age. This postweaning decrease in DBH activity was also observed with the cannulated animals. In contrast, plasma NA levels remained low and constant throughout the postweaning period. In suckling rats treated with 6-hydroxydopamine from 2 to 12 days of age, serum DBH activity decreased to less than half its initial value by day 8. It is suggested that the observed changes in serum DBH activity in fetal and postnatal rats reflect ontogenetic changes in sympathetic nerve terminals and that they are probably not correlated with release of NA.     

Utilization of body reserves for minim brood development by queens of the imported fire ant, Solenopsis invicta

Protein, glycogen, and lipid concentrations were followed in Solenopsis invicta queens, the imported fire ant, from egg deposition until the production of the first minim workers approximately 21 days later. During this time, the weight of the queens decreased from 14·7 to 7·5 mg. Immediately following egg deposition, total protein decreased by over 50 per cent for the first 6 days, then rose steadily for 9 days, then once again decreased markedly throughout the remainder of the study. Glycogen concentrations decreased rapidly from the 0·35 mg/ant found at oviposition until day 12. From this time until the end of the study, this polysaccharide remained constant at about 10 mg/ant. Lipid concentrations remained at 4·1 mg/ant for the first 9 days following oviposition, then steadily decreased to 2·3 mg/ant when the first minim workers were produced 12 days later.     

Dynamics in microbial immobilization and transformations of phosphorus in highly weathered subtropical soil following organic amendments

To improve knowledge on the role of microbial processes in phosphorus (P) transformations in highly weathered subtropical soil, dynamics in microbial biomass C (B_C) and P (B_P), and Olsen-P in a subtropical Ultisol following amendments with glucose at 2 g C kg⁻¹ soil (G2) and rice straw at 2 and 4 g C kg⁻¹ soil (RS2 and RS4) was studied during a 43-day incubation period at 25°C and 45% of soil water-holding capacity. By 3 days, the amount of soil B_C had increased about 3.2, 1.7, and 2.6 times for G2, RS2, and RS4, respectively. The amount of soil B_C significantly decreased between 3 and 7 days for G2 and 3 and 14 days for RS4, and thereafter remained almost steady throughout the 43-day incubation period, at levels about 1.6–2.4 times larger than for the control (no organic amendment; CK). The amount of soil B_P for G2 and RS4 almost doubled by 3 or 7 days, then remained relatively steady, and for RS2, maintained relatively constant (6.7–8.2 mg kg⁻¹ soil) throughout 43-day incubation period, whereas it declined by about 50% for CK. A significant decrease (3.5 mg kg⁻¹ soil) in Olsen-P occurred in G2 by 3 days; indicating a close response of available P to microbial immobilization. Also, the amounts of Al- and Fe-bound P in G2 and Fe-bound-P in RS4 decreased significantly, as determined at 43 days. In conclusion, organic amendment enhances microbial immobilization and transformations of P, but the turnover of B_P behaves in different patterns as B_C in highly weathered subtropical soil.     

Changes in proteolytic enzyme activities and transformation of nitrogenous compounds in the germinating seeds of kidney bean (Phaseolus vulgaris)

Summary Hydrolytic activity towards synthetic substrates and denatured proteins was measured in the extracts of the seeds of kidney bean at various stages of germination up to 16 days.Of the peptide hydrolases, chymotrypsin-type activity was stable for the first 7 days, then rapidly increased towards the end; leucine aminopeptidase activity decreased to a minimum (8th day) then slowly increased again; trypsin-type activity remained constant throughout.Proteolytic and autodigesting activities showed an optimum between pH 5.0 and 5.5. Both activities decreased slowly first, then rose to a sharp maximum at the 8th day. The haemoglobin-digesting activity after a minimum increased again at the 14th day. The autodigesting activity had an additional maximum.Concomitant with these changes, non-protein nitrogen increased twofold by the 5th day, remained constant up to the 12th day and then increased again. Protein content on the other hand decreased first, had a maximum at the 9th day after which it steadily decreased again. The amounts of albumins and globulins changed independently of each other: albumins decreased continuously with the exception of a steady period (5–9th days), while globulins were more stable except for a sharp minimum (6–7th days) and a steady decrease after the 13th day.The following abbreviations were used: BAPA, -N-benzoyl-L-arginine-p-nitroanilidine; N-CBZ-Tyr-PA, -N-carbobenzoxy-L-tyrosine-p-nitrophenyl ester; LPA, leucyl-p.nitroanilidine; BAEE, -N-benzoyl-L-arginine ethyl ester, TCA, trichloroacetic acid.     

Maturation and degeneration of the fat body in the Drosophila larva and pupa as revealed by morphometric analysis

Using morphometric and cytochemical techniques we have described changes taking place in the fat body cells during three different stages of development. The cell number remains constant at about 2200 cells during larval life and then decreases gradually and continuously throughout metamorphosis and the first 3 days of the adult stage until no more cells can be observed. Cell size increases rapidly during the larval period and decreases steadily during metamorphosis and adult stage. The size of the nuclei increases during the larval instars and decreases during the pupal interval. The change in nuclear size is correlated with the amount of DNA present throughout development implying the nuclear DNA is synthesized during the larval period and degraded gradually during metamorphosis. The cell size changes are due in large part to accumulation or loss of reserve substances: lipid droplets, glycogen deposits and protein granules. During metamorphosis the amount of lipid decreases slightly whereas glycogen experiences two loss cycles. The protein granules in the form of lysosomes continue to increase in amount during the first day of metamorphosis because of a short period of massive autophagy. Then the lysosomes decrease in amount throughout the remainder of metamorphosis. The lysosomes stain positively for lipofuscin.     

Steroidal regulation of hydrolyzing activity of the dietary carbohydrates in the silkworm, Bombyx mori

Blood sugar is an essential energy source for growth and development and is maintained at a constant level through precise regulation of formation and utilization. Sugars are produced from dietary carbohydrates by enzymatic hydrolysis in the digestive tract, which are under the homeostatic control of paracrine and prandial mechanisms in mammals. Here, we show that dietary carbohydrates hydrolyzing activity of the digestive tract is developmentally regulated by the steroid hormone ecdysone in the silkworm, Bombyx mori. The dietary carbohydrates hydrolyzing activity remained high throughout the last larval period and then decreased to negligible levels until the pupal period. However, dietary carbohydrates digestive activities were constitutively high when the steroidogenic organ, prothoracic glands were ablated. The prothoracic glands produced and released a large amount of ecdysone at the end of the larval period, suggesting that ecdysone is responsible for the decrease in dietary carbohydrates hydrolyzing activity. In fact, ecdysone decreased the activity to negligible levels in silkworms lacking the prothoracic glands. The present results indicate that the dietary carbohydrates hydrolyzing activity is regulated by ecdysone and that an increase in ecdysone titer decreases that activity at the end of the larval period, suggesting that ecdysone is essential for metabolic coordination during development.     

Effect of weaning on the activities of glycogen synthase and phosphorylase in rat liver

The effects of weaning on the level of glycogen and the activities of glycogen synthase and phosphorylase were determined in rat liver. Glycogen levels in rat liver increased at the start of the weaning period and reached a plateau on postnatal day 20. The active form of glycogen synthase increased until postnatal day 19 and then declined. Total glycogen synthase (active + inactive) remained high during the suckling period and declined to a new low level during the weaning period. The activity ratio (active/total) increased from day 16 to days 18-22 and then decreased to the same level as found during the suckling period. At the onset of weaning the active form of phosphorylase decreased, whereas total phosphorylase initially increased and then decreased after postnatal day 20. Both forms of phosphorylase increased again at the end of the weaning period. The activity ratio decreased at the start of weaning and remained low throughout the rest of the weaning period. The effects of premature weaning were similar to those observed in normally weaned animals, but the changes occurred sooner and were more pronounced.     

Calcium (45Ca) accumulation and transport in chicory (Cichorium intybus L.) root during bud development (forcing)

The lower part (4 cm) of the witloof chicory tap-root (15 cm) was immersed in a complete nutrient solution for 21 days, in the darkness at 18°C and at high RH. This process of forcing which leads to the emergence of an etiolated bud (chicon) was associated with a decrease in root dry weight. Although the amount of calcium in the root and the root cationic exchange capacity remained constant during forcing, the net uptake of calcium, negligible at the onset of forcing, progressively increased to a rate after ten days of 45 mol day^–1. Absorption of ⁴⁵Ca remained at a constant high rate, while the initially low upward migration of ⁴⁵Ca within the root and the chicon accelerated markedly. This upward migration was associated with a progressive decline in the release of newly absorbed ⁴⁵Ca. The data support the hypothesis that calcium acquisition by witloof chicory root is predominantly determined by calcium efflux. As the forcing progressed, the influx remained almost constant while a large decrease in the efflux led to a net uptake of calcium. Upward translocation was probably linked to the formation of new negative exchange sites within the growing chicon. The hypothesis that calcium movement occurred along a preferential pathway (xylem vessels) or involved a mass movement through the root is discussed.     

Alteration of α-Tocopherol Content in the Developing and Aging Peripheral Nervous System: Persistence of High Correlations with Total and Specific (n-6) Polyunsaturated Fatty Acids

In contrast to brain, the sciatic nerve concentration of vitamin E in rats increased rapidly during the postnatal period (approximately fivefold between days 1 and 8), then decreased dramatically (about twofold between days 8 and 30), and further decreased slowly between days 30 and 60 and remained constant up to 2 years. Although the sciatic nerve concentration of vitamin E decreased by 58% between days 8 and 30, the concentration of vitamin E in serum presented a marked decrease (approximately 75%). The vitamin E concentrations varied in a similar pattern in whole sciatic nerve and in endoneurium and showed a very close correlation (r = 0.94). The age-related changes in fatty acid concentration of the endoneurial fraction of the sciatic nerve were characterized by a large increase in content of saturated and monounsaturated fatty acids up to 6 months (twofold for saturated and fourfold for monounsaturated fatty acids). Then, up to 24 months, the amount of these fatty acids decreased very slowly. The content of (n-6) polyunsaturated fatty acids (PUFAs) decreased rapidly up to 1 year and slowly afterward. In contrast, during development the amount of (n-3) PUFA was relatively stable and decreased during aging. A highly significant correlation between vitamin E and (n-6) PUFA [18:2(n-6), 20:4(n-6), and total (n-6)] was observed but not between (n-3) PUFA and vitamin E. It is suggested that there may be a relationship between vitamin E and (n-6) PUFA in the PNS membranes during development and aging.     

Lytic enzyme activity in autolysing mycelium of Aspergillus niger

We have studied changes in the activity of some lytic enzymes contained in mycelium of Aspergillus niger in cultures relative to the autolytic phase of growth. Acid phosphatase, polygalacturonidase and alpha-amylase activity reached its highest level (40.7, and 8 U/sample, respectively) at the initiation of the autolytic phase of growth. 1.3-beta-Glucanase and beta-N-acetylglucosaminidase reached its highest level (3.5 and 2 U/sample, respectively) during the first days of autolysis. Alkaline phosphatase, cellulase, invertase, esterase, chitinase and proteolytic activity is also present in autolysing mycelium of A. niger, though comparatively low. Their maximum activity coincided with the beginning of the autolytic phase of growth. In all enzymes studied here, as autolyis proceeded, enzyme activity decreased by about 90%. Only esterase activity remained nearly constant throughout the whole period of autolysis described here.     

Why do rotifer populations present a typical sigmoid growth curve?

To determine the underlying processes to population growth in the rotifer Brachionus plicatilis, we conducted an experiment using 1.5 ml cultures for 70 days. All individuals were transferred daily to culture media containing algae, and the number of individuals, clutch sizes and number of deaths were counted. The population dynamics showed a typical sigmoid curve. The population density increased exponentially from 10 to 682 individuals during the first 7 days (exponential growth phase), and gradually up to about 1500 individuals during the next 30 days (post-exponential growth phase). The population density then remained at a constant level with small fluctuations during the rest of the experimental period (stationary phase). Mortalities appeared from the post-exponential growth phase and were almost constant at about 2% throughout the experimental period. The clutch size decreased from 5 to 1 during the first 5 days, and afterwards females laid only one egg each. The proportion of non-reproductive females increased from 30% (exponential growth phase) to 80% (post-exponential growth phase) to 90% (stationary phase). These results suggest that the exponential growth phase resulted from the imbalance between a high birth rate and a low death rate, while the stationary phase was maintained by the compensation between low birth and death rates.     

Hyaluronidase activity and hyaluronate content of the developing chick embryo heart.

Hyaluronidase activity and hyaluronate content were measured in the developing chick heart from embryonic day 3 through posthatching stages. High levels of both enzyme and substrate were found during the earliest stages examined. Hyaluronidase activity gradually declined to 63% of the initial (day 3) level by embryonic day 16. Enzyme activity decreased more sharply during the next 4 days to 30% of the initial level and remained constant through 2 weeks after hatching. Low levels of enzyme activity (about 10% initial levels) were still detectable in 10-week-old chicken hearts. The heart hyaluronidase is an endoglycosidase with an estimated molecular weight of 62,000, which degrades hyaluronate and, to a lesser extent, chondroitin sulfate at an acid pH optimum. Hyaluronate constituted approximately 50% of the total glycosaminoglycan content at embryonic day 5. Between embryonic days 5 and 12, the concentration of hyaluronate decreased to 25–30% of the initial level and remained constant thereafter. The level of other glycosaminoglycans decreased more gradually than hyaluronate and did not reach a constant level until hatching. This pattern of hyaluronidase activity and hyaluronate concentration presumably reflects the extensive tissue remodeling which transforms the developing heart from a thin-walled tube containing extensive regions of extracellular matrix to a compact, thick-walled myocardium having a limited extracellular compartment.     

The kinetics of the hypoferraemic response and changes in levels of alternative complement activity in diploid and triploid Atlantic salmon, following injection of lipopolysaccharide.

To study any possible effects of triploidy on the kinetics of the response of two non-specific disease factors, full sibling diploid and triploid Atlantic salmon were injected intraperitoneally with either lipopolysaccharide (1 mg kg(-1) body weight) or saline. Individually marked fish were repetitively blood sampled for up to 19 days. Total serum protein concentrations remained constant throughout the experiment indicating that the sampling regime did not cause haemodilution. The alternative complement pathway activity (measured by the titre of haemolytic activity against rabbit erythrocytes) in the serum of saline injected fish remained constant but in LPS-injected fish it fell to barely detectable levels 2 days after injection, but recovered to pre-treatment levels by about day 5. Triploid fish took slightly longer to reach full recovery levels than diploids. All groups of fish showed a hypoferraemic response, suggesting that the sampling regime was at least partially responsible. However, the response was more rapid and pronounced in the LPS-injected fish. In the latter, serum iron concentrations decreased to very low levels by day 2 post-injection in the diploid fish and by day 3 in the triploid fish. Pre-treatment iron levels were re-established by about 15 days post-injection in all groups. The data show only slight differences between the diploid and triploid fish, but the longer time taken for the triploids to recover complement activity and the slower onset of the hypoferraemic response following injection of LPS, suggest that they may be at a disadvantage compared with their diploid siblings in their defence against bacterial infections.     

Diurnal variations of nitrate reductase activity and stability in barley leaves

Diurnal variations of nitrate reductase (NR) activity and stability have been studied in leaves of barley seedlings ( Hordeum vulgare L. cv. Herta) grown in an 8 h light/16 h darkness regime. Stability (decay) of NR was tested both in the extracts and in the plants. In the morning, when the plants were transferred to light, NR activity increased rapidly during the first hour and then remained constant. After the photoperiod, activity decreased rapidly during the first hour of darkness and then remained fairly constant during the rest of the dark period. The high NR activity during the photoperiod was associated with low NR stability both in the extracts and in the plants. On the other hand the low NR activity during the dark period was associated with high stability in the extracts and in the plants.     

Lipid mobilization during starvation in the rainbow trout, Salmo gairdneri Richardson, with attention to fatty acids

Rainbow trout, Salmo gairdneri , were fed pelleted food ad libitum for 35 and 50 days. Lipid deposits were determined in the viscera, liver and muscle (epaxial and hypaxial). Most of the lipid accumulated in the viscera, but the lipid content of liver and epaxial muscle also increased. Hypaxial muscle lipid content remained the same throughout the feeding period. Upon starving the fish for 27 and 48 days following 50 days of feeding, visceral lipid contributed most to energy metabolism among the depots investigated. Muscle also contributed a considerable share while the absolute amount derived from the liver was much smaller.
Patterns of fatty acid mobilization during starvation were also investigated. Saturated acids were preferentially mobilized from the viscera, resulting in a rise in the percentage of monoenes and polyunsaturates. In liver, the percentage of saturates remained relatively constant whereas the percentage of monoenes declined and polyunsaturates increased. In muscle, a substantial increase in saturates was caused by a decline in monoenes; polyunsaturate content remained constant. As a result of these shifts in relative fatty acid composition the U/S (unsaturates to saturates) ratio rose in viscera and liver and decreased in muscle. The UI (unsaturation index) responded in essentially the same way. Possible explanations for preferential fatty acid utilization are discussed in terms of energetics and structural relationships.     

A Role for Glutamine Synthetase in the Remobilization of Leaf Nitrogen during Natural Senescence in Rice Leaves

Changes in the levels of cytosolic glutamine synthetase (GS1) and chloroplastic glutamine synthetase (GS2) polypeptides and of corresponding mRNAs were determined in leaves of hydroponically grown rice (Oryza sativa) plants during natural senescence. The plants were grown in the greenhouse for 105 days at which time the thirteenth leaf was fully expanded. This was counted as zero time for senescence of the twelfth leaf. The twelfth leaf blade on the main stem was analyzed over a time period of −7 days (98 days after germination) to +42 days (147 days after germination). Total GS activity declined to less than a quarter of its initial level during the senescence for 35 days and this decline was mainly caused by a decrease in the amount of GS2 polypeptide. Immunoblotting analyses showed that contents of other chloroplastic enzymes, such as ribulose-1,5-bisphosphate carboxylase/oxygenase and Fd-glutamate synthase, declined in parallel with GS2. In contrast, the GS1 polypeptide remained constant throughout the senescence period. Translatable mRNA for GS1 increased about fourfold during the senescence for 35 days. During senescence, there was a marked decrease in content of glutamate (to about one-sixth of the zero time value); glutamate is the major form of free amino acid in rice leaves. Glutamine, the major transported amino acid, increased about threefold compared to the early phase of the harvest in the senescing rice leaf blades. These observations suggest that GS1 in senescing leaf blades is responsible for the synthesis of glutamine, which is then transferred to the growing tissues in rice plants.