Effects of Feeding a Histidine-excess Diet and Subsequent Starvation on Liver and Muscle Glycogen,and on Serum Glucose

The effects of feeding with a histidine-excess diet and subsequent starvation on liver and muscle glycogen, and on serum glucose were investigated in young and adult rats.

Feeding with a histidine-excess diet resulted in the accumulation of liver glycogen in both young and adult rats. The hepatic glycogen continued to decrease during starvation, and the liver became almost totally depleted of glycogen after starvation for 48 hr. Glycogen in the liver of young rats starved for 24 hr after previous feeding with a histidine-excess diet was significantly higher than that of young rats starved for 24 hr after previous feeding with a basal diet.

Muscle glycogen after feeding and subsequent starvation was not affected by the types of diets fed previously, muscle glycogen during starvation showing a slight decrease in young rats and a slight increase in adult rats.

Feeding with a histidine-excess diet caused a significant decrease of serum glucose in young rats, but not in adult rats. Serum glucose in young rats was markedly reduced by starvation after previous feeding with a basal diet, but not after previous feeding with a histidine-excess diet. In adult rats, there were no changes in serum glucose between rats starved after feeding with either a basal diet or a histidine-excess diet, and serum glucose was decreased slightly by starvation after feeding with the test diets.

The overall results indicate that the maintenance of serum glucose in young rate even during starvation after previous feeding with a histidine-excess diet might be partially concerned with the export of glucose from the accumulated glycogen in the liver due to the diet.     

The mode of regulation of the corpus allatum activity during starvation in adult females of the Colorado potato beetle, Leptinotarsa decemlineata (Say)

When two-day-old female Leptinotarsa decemlineata were starved, their corpus allatum activity, as measured by the radiochemical in vitro assay, was significantly reduced after 24 hr. Such a reduction was not observed when the nerve connections between the central nervous system and the retrocerebral complex were severed and the beetles starved up to 5 days. In some experiments, the rate of juvenile hormone biosynthesis in vitro, was substantiated by measurement of the juvenile hormone titre in the haemolymph by physico-chemical methods. It is concluded that intact nervous connections between the central nervous system and the corpora allata are essential for restraining the juvenile hormone biosynthesis during the initial stages of starvation.Corpora allata from 1-day starved insects were considerably stimulated in vitro by farnesenic acid indicating that juvenile hormone synthesis is controlled enzymatically at a stage prior to the final two steps in the pathway. However, on day 5 of starvation, rate-limitation may occur after formation of this intermediate, since farnesenic acid stimulation was much less at this time.Corpora allata of adult females newly emerged from the soil were activated within 4 hr regardless of feeding.     

DOPA and tyrosine decarboxylase activity in tissues of Periplanet a americana in relation to cuticle formation and ecdysis

DOPA decarboxylase activity in haemolymph and integument was low in last instar and early pharate adult Periplaneta americana, but began to increase shortly before ecdysis. Decarboxylation rates of l-DOPA, about 10 times the larval level by the start of ecdysis, reached a peak about 6 hr afterward, coinciding with the main period of cuticular sclerotization. Activity decreased rapidly during the next 18 hr, then decreased gradually for several days. Haemolymph DOPA decarboxylase activity was about four times greater than the integument, based on tissue dry weights. The fat body and gut tissues had low DOPA decarboxylase activity in all ages tested, and this did not increase at ecdysis. Tyrosine decarboxylase activity was significant only in the haemolymph and at consistently low levels.DOPA decarboxylase, therefore, apparently plays a major rôle in production of catecholamine derivatives for cuticular sclerotization in P. americana, while tyrosine decarboxylation is minor. Both haemolymph and integument appear to be important sites of dopamine biosynthesis.     

Haemolymph osmolality,acid-base balance and shift of ammonotelic to ureotelic excretory pattern of Penaeus japonicus exposed to ambient ammonia

1. Urea-N and nitrite-N excretions of Penaeus japonicus (11.70 ± 2.30 g) increased, but ammonia-N excretion decreased with increased ambient ammonia-N, as they were exposed individually to 0.055 (control), 1.011, 5.121, 10.032 and 20.335 mg/l ammonia-N after 24 hr.2. Haemolymph pH, PCO₂ and osmolality of shrimp displayed an inverse linear relationship with concentration of ambient ammonia-N.3. Shrimp exposed to 10.032 mg/l ammonia-N after 24 hr significantly affected (P < 0.05) haemolymph PCO₂ and osmoregulatory capacity.4. Accumulated ammonia-N in the haemolymph of shrimp following exposure to ambient ammonia-N at 5.121 mg/l or greater caused a shift from an ammonotelic to a ureotelic pattern, and may cause catabolism of hemocyanin and protein to free amino acids to balance osmoregulation.     

Glycine incorporation during starvation in Bombyx mori. Relation to respiratory metabolism

The pattern of glycine incorporation was followed during 48 hr starvation in Bombyx mori larva, and it was shown that the incorporation rate decreases and reaches its lowest level after 24 hr although it never stops. Prior injection with cycloheximide causes a fall in the level of incorporation in well-fed silkworms, but it has no effect after 24 hr starvation.However cycloheximide decreases the respiratory rate and the decrease is smaller when the length of the previous starvation.period increases. The antibiotic has no effect on respiratory metabolism after 24 hr starvation. There is a high correlation between the inhibiting effect on metabolism due to cycloheximide and the proteosynthetic rate at the same time.It is concluded that the decrease in protein synthesis during starvation induces a reduction in the corresponding energy requirements; this reduction partly explains the decrease of respiratory metabolism.     

Studies in lipogenesis in vivo: Fatty acid and cholesterol synthesis during starvation and re-feeding

1. Lipogenesis in vivo has been studied in mice given a 250mg. meal of [U-¹⁴C]glucose (2·5μc) or given an intraperitoneal injection of 25μg. of [U-¹⁴C]glucose (2·0μc). 2. The ability to convert a [U-¹⁴C]glucose meal into fatty acid was not significantly depressed by 6–7hr. of starvation. In contrast, incorporation of ¹⁴C into fatty acid in the liver after the intraperitoneal dose of [¹⁴C]glucose was depressed by 80% and by more than 90% by 1 and 2hr. of starvation respectively. Carcass fatty acid synthesis from the [U-¹⁴C]glucose meal was not depressed by 12hr. of starvation, whereas from the tracer dose of [U-¹⁴C]glucose the depression in incorporation was 80% after 6hr. of starvation. 3. Re-feeding for 3 days, after 3 days' starvation, raised fatty acid synthesis and cholesterol synthesis in the liver fivefold and tenfold respectively above the levels in non-starved control mice. These increases were associated with an increased amount of both fatty acid and cholesterol in the liver. 4. After 18hr. of starvation incorporation of a [U-¹⁴C]glucose meal into carcass and liver glycogen were both increased threefold.     

Carbohydrate and fatty acid titres during flight of the migrant noctuid moth,Anticarsia gemmatalis Hübner

Haemolymph concentrations of total carbohydrate and fatty acids were determined in velvetbean caterpillar (Anticarsia gemmatalis Hübner, Lepidoptera: Noctuidae) adult females throughout a 4-hr period of tethered flight. Total carbohydrate concentration decreased from approx. 30 to 10 μg/μl during the first 45 min of flight. Total fatty acid concentration increased from approx. 20 to 40 μg/μl during the first 60 min of flight and then declined to and stabilized at preflight levels. The decrease in wet weight (from approx. 97 to 80 mg/moth) during flight was probably due to defecation since no change in dry weight or haemolymph volume occurred. After 4 hr of flight, no apparent change in whole body lipid content (approx. 12 mg/moth) was observed but the much smaller carbohydrate content was reduced approx. 80% (from approx. 0.6 to 0.1 mg/moth). Approximately equal amounts (approx. 360–550 μg) of carbohydrate and lipid were removed from the haemolymph during 4 hr of flight. Changes in the haemolymph concentrations of palmitic, oleic and linoleic acids correspond to the changes in total fatty acid concentration of the haemolymph, indicating that these are the major components of the lipid mobilized and utilized during flight of A. gemmatalis.     

Predation byXylocoris flavipes [Hem.: Anthocoridae]: Influence of stage,species and density of prey and of starvation and density of predator

When the efficacy of the predaceous bugXylocoris flavipes (Reuter) was tested in the laboratory as a biological control agent against stored-product insects, it attacked eggs more than larvae, pupae, or adults and early-stage larvae ofTribolium castaneum (Herbst) more than late-stage larvae. The predator also killed more larvae ofT. castaneum than larvae ofAttagenus megatoma (F.). The density of predator and prey regulated the capture rate of the predator. Predation byX. flavipes was uninfluenced by starvation for as much as 96 hr.     

Vitellogenic arrest in the cockroach, Blatta orientalis

Starvation stimulated vitellogenic arrest occurs in the cockroach Blatta orientalis after 5 days. This is characterized by cessation of yolk uptake and oöcyte growth.After 5 days of starvation, protein and RNA synthesis decrease, but some macromolecular synthesis continues during the entire starvation period. No oöcyte resorption occurs for up to 15 days of starvation. In contrast to starvation, injection of actinomycin-D results in resorption within 8 hr. The results suggest that B. orientalis copes with starvation by maintaining arrested oöcytes as an alternative to immediate resorption.     

Accumulation of urea in the haemolymph and ammonia excretion of Penaeus japonicus exposed to ambient nitrite

Penaeus japonicus (15.7 ± 1.4 g) were exposed individually in 30 ppt seawater to 0.01 (control), 5, 10, 20 and 50 mg/l nitrite-N for 24 hr. Haemolymph ammonia, urea, nitrite and whole shrimp ammonia-N excretion and nitrite-N uptake were then determined. Ammonia excretion of P. japonicus increased with increased ambient nitrite, and with a concomitant decrease of haemolymph ammonia, as occurring increased concentrations of nitrite. Concentrations of nitrite-N and urea-N in the haemolymph of shrimp increased with increased ambient nitrite-N. However, no urea-N excretion was observed for shrimp exposed to any nitrite treatments.     

Magnesium starvation of Aerobacter aerogenes. I. Changes in nucleic acid composition

Aerobacter aerogenes incubated in a medium containing all factors necessary for exponential growth except Mg⁺⁺ continued to synthesize nucleic acids and proteins for more than 70 hr, provided the major carbon source was in excess at all times. After 24 hr of Mg⁺⁺ starvation, deoxyribonucleic acid content in the culture had increased 10-fold. In contrast, the viable-cell count increased only about threefold during the first few hours and then remained approximately constant for the subsequent 70 hr. After specified intervals of Mg⁺⁺ starvation, extracts of the bacteria, or ribonucleic acid (RNA) purified from them, was centrifuged through gradients of sucrose to separate transfer RNA from ribosomal components. After correcting for losses, we obtained the following results. (i) There was a progressive rise in the content of transfer RNA competent to accept amino acids and during starvation it remained completely stable. (ii) In contrast, the contents of normally sedimenting ribosomal RNA and ribosomal subunits (30 and 50S) remained approximately constant for more than 24 hr. This did not result from stability of ribosomes made prior to starvation together with an inhibition of synthesis of new particles. Rather, ribosomes were continually breaking down and being replaced by an equivalent number of new ones. (iii) The breakdown of ribosomes appeared to be sequentially ordered; polysomes yielded 70S monomers, which then gave 30 and 50S particles, and these disintegrated to smaller units and finally to acid-soluble products. (iv) Furthermore, the particles derived from breakdown do not appear to exchange with subparticles on the path of assembly. Thus, ribosome decay was age-dependent and ribosomal RNA molecules had a minimal life expectancy of 90 min; however, some survived much longer.     

Biochemical and physiological studies of certain ticks (Ixodoidea): effects of relative humidity and starvation on the water balance and behavior of adult Argas (Persicargas) arboreus (Argasidae).

The effects of high (96%) and low (0%) relative humidities (RH) and starvation on the total body weight, water content, dry weight content, and humidity responses of unfed adult Argas (Persicargas) arboreus (Argasidae) were determined each 15 days for a period of 105 days. High RH caused an increase of 6.7% in females and 7.2% in males of total body weight after 15 days followed by very slow decrease reaching 4.5% in females and 5.4% in males of initial body weight after 105 days. Low RH caused continuous decrease to 46.2% in females and 53.7% in males of the initial body weight after 105 days. After 105-day starvation at 96% RH, the initial value of the water content increased by 3% in females and 5% in males; at 0% RH this value decreased by 52% in females and 59% in males. The initial value of the dry weight content decreased by 23% in females and 26% in males at 96% RH and by 33% in females and 43% in males at 0% RH. Newly molted adults were hygronegative and at 96% RH remained so. At 0% RH, the hygronegative reaction gradually decreased and changed to hygropositive after 60 days in females and 90 days in males. Survival of 80 control ticks after 105 days was 96% at 96% RH and 54% at 0% RH.     

Hormonal basis of adult eclosion in the gypsy moth (Lepidoptera: Lymantriidae)

Eclosion hormone was found to control the stereotypic adult eclosion behaviour of Lymantria dispar, the gypsy moth. A bioassay for hormonal activity was developed utilizing pharate adult females, and comparisons were made with the Manduca wing assay. The distribution of eclosion hormone activity was confined to the central nervous system tissues including the protocerebrum, corpora allata/corpora cardiaca complex, thoracic and the last abdominal ganglion. Haemolymph ecdysteroid titres were determined daily throughout pupal-adult development, and the peak activity period was found in 3–4 day pupae. Eclosion hormone activity in the brain and corpora allata/corpora cardiaca complex started to increase when the ecdysteroid titre dropped to background levels. Eclosion hormone in the brain peaked in the pharate adult stage, was released in the haemolymph 1 h prior to eclosion, which coincides with the depletion of activity in the retrocerebral complex, and fell to undetectable levels after the adult emerged.     

Early Changes in the Ultrastructure of Streptococcus faecalis After Amino Acid Starvation

Thin sections of Streptococcus faecalis (ATCC 9790) starved of one essential amino acid (threonine or valine) initially show rapid increases in (i) cell wall thickness, (ii) the apparent size of the central nucleoid region, and (iii) mesosomal membranes. The most rapid increases in all three variables occurred during the first 1 to 2 hr of starvation. After this initial period, the rates progressively decreased over the 20-hr observation period. During threonine starvation, the mesosomal membrane that accumulated in the first hour was subsequently degraded and reached a level similar to that found in exponential-phase cells after 20 hr. With valine starvation, mesosomal membrane continued to slowly accumulate over the entire 20-hr observation period. The mesosomes of the starved cells retained the same “stalked-bag” morphology of those in exponential-phase cells. These cytological observations agree with previously published biochemical data on membrane lipid and wall content after starvation.     

Neurosecretory protein synthesis in relation to starvation and feeding in adult male Locusta migratoria

An immunological approach has been used to assess the effects of starvation and subsequent feeding upon the synthesis of neurosecretory protein in adult male Locusta migratoria. Starvation (for 5 days) did not reduce the incorporation of radioactive cystine into neurosecretory protein. However, the rate of neurosecretory transport in starved insects was approximately half that in normal fed insects.Within 1 hr after the start of feeding the rate of neurosecretory protein synthesis more than doubled and the rate at which newly synthesized protein was transported to the CC increased approximately three-fold. The incorporation of cystine into specific (i.e. neurosecretory) protein was always higher, even in starved insects, than into the non-specific proteins (i.e. proteins other than those from the A-cells) of the brain. This difference was maximal at 4 hr after feeding when the incorporation into specific protein was more than 5 times that into non-specific protein.     

Toxic effects of mercury on the hard clam,Meretrix lusoria,in various salinities

1. The 96-hr lc₅₀ values for juvenile hard clams, Meretrix lusoria, were 328, 392 and 194 μg/l Hg in 10, 20 and 30 ppt salinities at 25 ± 1°C, respectively; for adult hard clams 341 and 140 μg/l Hg in 20 and 30 ppt salinities, respectively.2. Acclimatizing the adult clams to low salinity of 10 ppt lessened the toxicity of mercury. However, juvenile animals appeared to be more sensitive to mercury poisoning after 96 hr exposure in 10 ppt salinity.3. All embryos exposed to 40 μg/l Hg and above died within 30 hr. In the control, 44% of hatched embryos had developed into D-stage larvae, while those exposed to 20 μg/l Hg were still in the trochophore stage. Most of the retarded larvae developed into abnormal forms within 30 hr at 28°C in 15 ppt salinity.4. In order to maintain water quality and protect natural resources, the recommended safe level of mercury is 0.046 (0.039–0.053) μg/l Hg, based on the estimated 30-hr EC₅₀ for the clam embryos, with an application factor of 0.01.     

The effect of starvation and subsequent feeding on the reproductive potential of the grain aphid,Sitobion avenae

The short‐term starvation tolerance of alate and apterous morphs and the effect of periods of starvation on the longevity and fecundity of alate adults were evaluated in the grain aphid, Sitobion avenae (Fabricius) (Hemiptera: Aphididae). Alate adults exhibited a proportionally larger length of survival compared with apterous adults under continuous starvation conditions. Newly molted pre‐reproductive adults were starved for 0–96 h and their survival rate on the 1st day after recovering with food was not significantly different from that of control aphids. Starvation reduced lifetime fecundity, but increased the reproductive rate immediately after nutrition being improved. Fecundity and longevity after 24, 48, 72, and 96 h of starvation were significantly higher than after 120 or 144 h of starvation. However, no significant differences were observed for alate adults after 24, 48, 72, or 96 h of starvation. This study suggests that the ability of alatae to adapt to brief periods of starvation could be one of the important factors affecting the reproductive success of aphids during delays in locating host plants.     

CELL PROLIFERATION IN COMPLEX TISSUES: THE CONTROL OF THE MITOTIC CYCLE OF CELL POPULATIONS IN THE CULTURED ROOT MERISTEM OF SUNFLOWER (HELIANTHUS)

Experiments were performed with cultured primary root tips of sunflower (Helianthus annuus var. Russian Mammoth) to determine: (1) if progression in the mitotic cycle of meristematic cells was nutritionally controllable by carbohydrate starvation and replenishment; (2) where in the mitotic cycle control was effected; and (3) whether nutritional deprivation could be used to detect phenotypically different subpopulations in a complex tissue. Meristematic cells were rendered stationary by carbohydrate starvation, as indicated by the absence of cell division; this condition was reversed by carbohydrate provision. After 72 or 96 hr of starvation most cells stopped in G1 (80–90%) and G2 (10–20%), and a very few (“leaky” cells) continued to enter S. “Leaky” cells represent a small population with an S period of approximately 4.1 hr that either lack a principal control point in G1 or have an unusual metabolism whereby the control point requirements are met and have a carbohydrate dependence for mitosis. Though phenotypically different, no specific functions can be attributed to “leaky” cells at this time.     

Heat and starvation induced hormesis in longevity of Oomyzus sokolowskii (Kurdjumov) (Hymenoptera: Eulophidae) adult females

Oomyzus sokolowskii (Kurdjumov) (Hymenoptera: Eulophidae) is an important endoparasitoid of Plutella xylostella (Linnaeus) (Lepidoptera: Plutellidae) larvae and pupae. Previous studies have showed that environmental stress induced hormesis in a variety of organisms. In the present study, we investigated the effects of heat and starvation stress on the survival and induced hormesis in longevity of O. sokolowskii adult females under laboratory conditions. Results showed that temperature and exposure time significantly affected the survival rate of O. sokolowskii adult females with the extreme temperatures and/or longer durations proving to be more lethal. When O. sokolowskii adult females were heat-treated for 0.5, 1, 2, 4, and 8 h, LTemp₅₀ were >50.00, 43.24, 38.82, 38.32, and 38.17 °C, respectively. LTime₅₀ at the threshold temperature of 38 °C was 3.90 h. The sub-lethal temperature exposure for a certain time period reduced the survival numbers, but increased the longevity of survived adult females at the condition of starvation. The exposure for 2 h at 36 and 38 °C reduced the survival numbers by 26.67% and 46.67%, but extended the longevity of the survived adult females by 65.89% and 55.37% in comparison with those in the control, respectively. These results suggest O. sokolowskii adult female has the potential of thermal resistance, and its longevity will increase via heat and starvation treatment.