Male Blaberus Discoidalis Research Articles

Intracellular transduction of trehalose synthesis by hypertrehalosemic hormone in the fat body of the tropical cockroach blaberus discoidalis

Fat body of adult male Blaberus discoidalis cockroaches exposed to B. discoidalis hypertrehalosemic hormone (HTH) in vitro showed a decline in tissue glycogen as carbohydrate increased in the medium In vivo HTH injections increased hemolymph carbohydrate and fat body glycogen phosphorylase activity >2-fold compared to controls. In vivo trehalose synthesis was unaffected by agents that enhance intracellular levels of cyclic nucleotides including: dibutyryl cAMP, dibutyryl cGMP, forskolin (adenylyl cyclase activator) and isobutyl methylxanthine (IBMX) or theophylline (cAMP phosphodiesterase inhibitors). DbcAMP + IBMX stimulated trehalose biosynthesis of fat body in vitro and had additive effects with a minimally stimulatory HTH concentration. However, adenyl cyclase activity was unaffected by HTH either with isolated fat body or fat body membrane preparations. We conclude that cAMP is not a second messenger for HTH, but cAMP can stimulate trehalose production independent of HTH through actions on common regulatory events related to trehalose biosynthesis. Dibutyryl cGMP and phorbol esters and diacyglycerol (activators of protein kinase C) also failed to stimulate trehalose biosynthesis in vitro. Extracellular Ca 2+ enhanced HTH-dependent phosphorylase activity, glycogenolysis and hypertrehalosemia and maintained basal levels of phosphorylase a at twice those observed in the absence of Ca 2+ However, Ca 2+ entry by Ca 2+ ionophore (A23187) did not mimic HTH effects. Results of these studies demonstrated that extracellular Ca 2+ is important for HTH-dependent trehalose biosynthesis but cAMP and cGMP are not involved.

Hypertrehalosemic hormone effects on transcriptional activity in the fat body of the cockroach, Blaberus discoidalis

Gene expression was examined in the fat body of adult male Blaberus discoidalis cockroaches in response to the hypertrehalosemic hormone (HTH). HTH regulates a natural peak of heme synthesis in the fat body at day 4 of adult life. Inhibition of transcriptional activity by α-amanitin suppressed both the natural increase in heme biosynthesis at day 4, and the increase that was induced in decapitated animals by HTH administration. In contrast, the regimen of α-amanitin treatments that suppressed HTH-responsive heme biosynthesis had no effect on the ability of HTH to increase hemolymph carbohydrate. HTH administration to decapitated animals produced a 25% increase in total fat body RNA and a 3-fold increase in [ 3H]uridine incorporation. In vitro translation of fat body RNA showed that HTH increased the synthesis of polypeptides at 24, 60 and 77 kDa. The results suggest that HTH affects fat body heme synthesis through gene expression, and evidence was obtained for three polypeptides that increase in the fat body in response to HTH.

Properties of an in vitro bioassay for hypertrehalosemic hormone of Blaberus discoidalis cockroaches

The ability of the fat body to respond to the hypertrehalosemic action of corpora cardiaca-allata (CC + CA) extracts was measured in vitro with tissue from adult, male Blaberus discoidalis cockroaches. Only trehalose increased in the hemolymph when gland extracts were injected in vivo; likewise, only trehalose levels responded when fat bodies were exposed to gland extracts in vitro. Although fat bodies from 0-day-old animals gave the least response to gland extracts, all animals 5 or more days old showed elevated responses. A linear dose-response occurred between 0.02 and 0.08 CC + CA pair. Fat bodies did not show an in vitro, hypertrehalosemic response to insulin, glucagon, proctolin, dopamine, epinephrine, norepinephrine, serotonin, octopamine, or tyramine. A strong hypertrehalosemic response was found to both synthetic adipokinetic hormone and red-pigment concentrating hormone; however, reversed-phase, thin-layer chromatography of CC + CA extracts and adipokinetic hormone indicated that the hypertrehalosemic effect and the adipokinetic hormone were separate. This in vitro system comprises a relatively rapid, simple, and accurate bioassay for the hypertrehalosemic neurohormone of insects.

Development and endocrine effects on the synthesis of mitochondrial proteins in the fat body of the cockroach, Blaberus discoidalis

The pattern of mitochondrial protein synthesis was observed in the fat body during postemergence maturation of adult male Blaberus discoidalis cockroaches. The incorporation rate of [ 14C]-leucine into mitochondrial proteins was high between days 0 and 4 of adult life then decreased by about 40% to a lower, stable rate between days 6 and 30. Cycloheximide-insensitive, intramitochondrial protein synthesis paralleled this pattern. The half life of [ 14C-guanidino]-arginine was 36.2 days in mitochondrial proteins which suggests that the mitochondria are stable organelles in the fat body. Cervical ligation lowered the rate of mitochondrial protein synthesis by 60%, but attempts to return the synthetic rate to normal by injections of corpora cardiaca extracts were inconclusive.

Cytochromogenic factor: a newly discovered neuroendocrine agent stimulating mitochondrial cytochrome synthesis in the insect fat body.

Abstract Evidence is presented for a neurohormone that stimulated by fivefold the synthesis of cytochromes aa 3 + b in the fat body of young, adult, male Blaberus discoidalis cockroaches. This newly discovered agent is designated as the “cytochromogenic factor” (CGF). CGF was concentrated in the corpora cardiaca (CC). A CGF bioassay was developed with decapitated animals that had a threshold response at 0.01 CC pair and showed a linear dose response up to a maximum of 0.08 CC pair. A 24- to 48-hr latent period was needed for the maximum in vivo response to CGF. CGF activity was heat labile and was inactivated by chymotrypsin; partially inactivated by carboxypeptidases A and Y and aminopeptidase M; but not by trypsin. Other hormones such as juvenile hormone (III), 20-hydroxyecdysone, proctolin, and triiodothyronine failed to elicit the cytochromogenic response.

Age and endocrine effects on fat body metabolite composition in adult male Blaberus discoidalis cockroaches

AbstractEndocrine‐and age‐related changes in metabolite contents were used as a measure of fat body development and function in adult male Blaberus discoidalis cockroaches. Fat body dry weight, protein, glycogen, and lipid levels coordinately decreased at days two to three of adult life, increased at day four, then declined to lower stable levels by days six to seven. The metabolite contents remained stable from days seven through ten and were still at this level on day 30. Long‐term endocrine deficiencies resulting from corpora cardiaca‐allata extirpation did not change the amounts of metabolites present at 30 days of age. The fat body DNA content remained constant regardless of age or endocrine balance. Unlike other metabolites, the RNA content increased to twice its original level during the first six days of adult life and was unaffected by either age or endocrine balance thereafter. The findings suggest that the adult fat body changes from a storage function at the time of the nymphal‐adult molt to a biosynthetic function by day six. The transition is independent of endocrine control by the corpora cardiaca‐allata complex.

Development and endocrine regulation of mitochondrial cytochrome biosynthesis in the insect fat body: δ-[ 14C]aminolevulinic acid incorporation

The rate of incorporation of [ 14C]aminolevulinic acid (ALA) into cytochrome hemes was used to measure mitochondrial cytochrome synthesis in the fat body of adult male Blaberus discoidalis cockroaches. The hemes of cytochromes aa 3+ b and c+ c 1, were chemically separated to observe differential rates in their synthesis and regulation. [ 14C]ALA was linearly incorporated into cytochrome hemes for at least 8 h. No significant pool of endogenous ALA was detected relative to the amount of administered [ 14C]ALA. Peak cytochrome synthesis occurred 4 to 6 days after adult emergence. Endocrine disruption by corpora cardiaca-corpora allata extirpation or cervical ligation eliminated the 4-day developmentally related increase in the rate of cytochrome aa 3+ b synthesis but had no effect on the production of cytochromes c+ c 1. Injections of corpora cardiaca extracts into cervically ligated animals stimulated the rate of production of cytochromes aa 3+ b by 2.5 times but did not affect cytochromes c+ c 1. By comparison, juvenile hormone injections did not affect the rate of synthesis of either cytochrome fraction. These findings indicate that a neurohormone regulates the rate of synthesis of cytochromes a+ b in insect fat body mitochondria.

Development and endocrine regulation of mitochondrial cytochrome biosynthesis in the insect fat body: δ-Aminolevulinic acid synthase

Aminolevulinic acid (ALA) synthase activity was measured in fat body mitochondria from adult male Blaberus discoidalis cockroaches. The enzyme reached its maximum activity at 4 to 6 days of adult age and then dropped to a minimal level which was maintained throughout the remainder of the study period. ALA synthase activity was doubled by allylisopropylacetamide and showed a half-life of about 6 h at 25 °C. Enzyme activity was depressed by long-term allatectomy. However, juvenile hormone administration in vivo did not significantly stimulate the enzyme relative to appropriate controls, and endocrine regulation of fat body ALA synthase remains inconclusive. Hemin inhibited ALA synthase activity, suggesting that fat body heme synthesis could be regulated by end-product inhibition.

Development and endocrine regulation of cytochrome levels in fat body mitochondria of the cockroach, Blaberus discoidalis

Cytochromes aa 3 , b, c, and c 1 each showed distinct developmental patterns in fat body mitochondria of adult, male Blaberus discoidalis cockroaches. Cytochrome b content reached a maximum by day 2 of adult life; whereas, the other cytochromes reached their maxima by day 6. Once developed, the quantities of all the measured cytochromes remained constant through 30 days of age. Endocrine deficiencies changed the cytochrome levels relative to sham operated controls. Alletectomy increased cytochromes aa 3 and b, somewhat decreased cytochrome c 1 and left cytochrome c unchanged. Cardiacectomy-allatectomy significantly reduced the levels of cytochromes c and c 1 but had little effect on cytochromes a and b.

Neuroendocrine deficiency effects on trophic metabolism and water balance in the cockroach, Blaberus discoidalis

Unoperated, sham-operated (SO) and allatectomized (CA −) adult, male Blaberus discoidalis lost ca. 300 mg of live weight (LW) during the first 10 days after ecdysis. This decrease resulted from losses in both dry weight (DW) and water. An additional 100 mg LW loss was found in allatectomized-cardiacectomized (CA −+CC −) animals as a result of increased water loss. The LWs of operated and unoperated controls remained nearly constant between 10 and 30 days of age as DW increased and water decreased in comparable amounts. However, the LW of 30-day-old CA −+CC − animals was 100 mg greater than the controls due to increased water retention. Compared to controls, food consumption and faecal production were reduced by 50 per cent in CA − and CA −+CC −animals, but the percentage of food digested was unchanged. Efficiency of converting food to DW in CA −+CC −animals was twice that of SO and CA − animals and four times that of the unoperated controls. These results indicate that extirpation of the retrocerebral complex decreases food intake but not digestion. Nutrient storage or conversion to body matter is apparently enhanced by neuroendocrine deficiency. Therefore, a gross nutritional deficiency is unlikely in CA −+CC −animals. The LW changes occurring after neuroendocrine deficiency were related to changes in water content. DW changes were comparable in all control and experimental groups. The results indicate both diuretic and antidiuretic effects by the neuroendocrine system depending on the age of the animals.

Feeding effects on the neuroendocrine regulated development of fat body mitochondria in the cockroach Blaberus discoidalis

Fat body mitochondria in male Blaberus discoidalis showed a stepwise three-fold development in succinoxidase activity during the first 10 days of adult life. Long-term corpora cardiaca deficiency or prevention of feeding by oral blockage prevented the third step in succinoxidase development. Starvation alone did not prevent the complete development. Administration of corpora cardiaca extracts to orally blocked animals stimulated the final development of succinoxidase activity. It is speculated that the mechanical acts of feeding stimulate neurosecretory activity which increases the metabolic capacity of the fat body through effects on mitochondriogenesis.

Biogenesis of mitochondria: Neuroendocrine effects on the development of respiratory functions in fat body mitochondria of the cockroach, Blaberus discoidalis

Fat body mitochondria from male Blaberus discoidalis cockroaches underwent a hormone-independent respiratory development during the first 5 days of adult life followed by a neurohormone-dependent development during the next 5 days. Increases of two- to threefold were shown for oxygen uptake and for succinate-cytochrome c reductase and cytochrome c oxidase activities during this period. Also, an increased capacity for respiratory control by ADP was evident. No further respiratory changes occurred between 10 and 30 days of adult age. Respiratory enzyme activities and respiratory control failed to develop beyond the 5 day level after disruption of neurosecretory functions by extirpation of the corpora cardiaca. Conversely, daily administration of corpora cardiaca extracts stimulated precocious 10 day levels of respiration by 5 days of adult age. Uncoupling with 2,4-DNP indicated electron transport as the rate-limiting process of respiratory activity. Total incorporation of 14Camino acids into fat body mitochondria increased twofold during the first 5 days of adult life. This level of amino acid incorporation was maintained thereafter and corpora cardiaca removal had no effect. The fat body of Blaberus appears useful for studies on the hormonal regulation of mitochondrial development in higher eucaryotic animals.

Circadian rhythmicity and capacity for enforced activity in the cockroach, Blaberus discoidalis, after cardiacectomy-allatectomy

The capacity for enforced activity in response to electrical stimulus and circadian locomotor activity were recorded for adult male Blaberus discoidalis after long-term cardiacectomy-allatectomy (CC −+CA −). CC −+CA − cockroaches showed longer periods of exhaustion during shock stimulated activity than either normal or CA − animals. However, actograph studies revealed no differences between normal and CC −+CA − cockroaches in either circadian rhythmicity or the intensity of activities. These results suggest the cockroach corpora cardiaca do not influence normal activity patterns but maintain metabolic processes at levels sufficient to meet emergency demands.

Endocrine effects on the biochemical properties of fat body mitochondria from the cockroach, Blaberus discoidalis

The respiratory rates for fat body mitochondria isolated from adult, male Blaberus discoidalis were determined following long-term cardiacectomy (CC −), allatectomy (CA −), and cardiacectomy-allatectomy (CC − + CA −). All results point to ca. 30 per cent decrease in O 2 uptake following CC − with no effect from CA −. This result was reflected by the activities of the electron transport systems: succinate-cytochrome c reductase and cytochrome c oxidase, which were also reduced 30 per cent following CC − + CA −. Oxidative phosphorylation, respiratory control, and the amount of fat body mitochondrial protein were unaffected by CC − + CA −. Gland extracts had no direct effect on O 2 uptake by fat body mitochondria from CC − + CA − animals. CC − at any time after adult ecdysis resulted in a depressed respiratory rate suggesting the glands exert a continuous effect on the fat body mitochondria. These results indicate the brain-corpora cardiaca neurosecretory complex affects the capacity of fat body mitochondria for respiratory and electron transport activity although respiratory control by ADP and the efficiency of oxidative phosphorylation remain normal. The lack of direct stimulus by corpora cardiaca extracts on O 2 uptake suggests the neurosecretory factors act indirectly on mitochondrial electron transport activities via other biochemical systems and over a relatively long time period. The response of insect fat body mitochondria to long-term CC − is compared to the response of vertebrate mitochondria to thyroidectomy and suggests the neurosecretory factor may have an analogous physiological action.

Insect hormones: Evidence for a neuroendocrine factor affecting respiratory metabolism

Gland extirpation studies on adult, male Blaberus discoidalis cockroaches provide new evidence for the hormonal regulation of respiratory metabolism in insects. These studies indicate the active agent is a brain neurosecretion stored and released by the c. cardiaca which affects the respiratory capacity of fat body mitochondria. The depressed Q 02 of fat body mitochondria from cardiacectomized-allatectomized cockroaches is returned to normal by daily injections of c. cardiaca extracts although the extracts have no direct action on oxygen uptake when added to fat body mitochondria in vitro .

Corpus cardiacum as a metabolic regulator in Blaberus discoidalis serville (Blattidae) : I. Long-term effects of cardiatectomy on whole body and tissue respiration and on trophic metabolism

By using manometric measurements it has been shown that removal of the corpora cardiaca depresses respiratory metabolism in adult, male Blaberus discoidalis. This effect is seen within 10 days after the operation and does not change over the next 20 days. Studies on dry body weights indicate that 30-day cardiatectomized-allatectomized animals are equivalent to control animals with respect to dry matter and water content. Therefore, it is concluded that cardiatectomized-allatectomized animals are trophically normal at this time, and that lowered respiration rates have a more fundamental origin. Manometric studies on intact, excised tissues indicate that fat body of the 30-day cardiatectomized-allatectomized roach has an endogenous respiratory rate significantly lower (47%) than controls. Addition of glucose does not stimulate a return to normal respiratory levels. Muscle tissue does not show respiratory differences between cardiatectomized-allatectomized and control animals. Added glucose causes a significant decrease in muscle respiration similar to a Crabtree effect. The implications of these results relative to a mechanism of metabolic control are discussed.