Implantation Of Active Corpora Allata Research Articles

Hormonal control of egg maturation in the corn earworm, Heliothis zea

AbstractAt eclosion, the ovaries of female Corn earworm Heliothis zea do not contain mature eggs. Virgin‐unfed females produced approximately 400 mature eggs in 8 days; mating or feeding doubled this number, and mating plus feeding more than tripled it. Females allatectomized or decapitated at day 0 matured few eggs. Egg production was restored by implantation of active corpora allata (CA) or by treatment with the juvenile hormone (JH) analogue methoprene at day 0. 20‐Hydroxyecdysone, on the other hand, had no effect. Females in which the CA had been denervated or in which the median neurosecretory cells of the brain had been ablated at day 0 produced fewer eggs than sham‐operated animals. These results indicate that egg maturation is controlled by JH and that continuous input from the brain is required for sustained CA activity for maintaining a high rates of egg maturation.The rate of JH biosynthesis by CA in vitro was determined with a radiochemical assay. The major hormones produced were JH‐II and JH‐III with small quantities of JH‐I. The rates of JH synthesis were similar in all experimental groups which may indicate that the in vitro rate of JH synthesis does not reflect the actual state of CA activity in the female.

Corpus allatum control of sex pheromone production and calling in the female brown-banded cockroach, Supella longipalpa (F.) (Dictyoptera: Blattellidae)

The neural and endocrine regulation of pheromone production and release (calling) was investigated in adult female Supella longipalpa. Virgin adult females initiated pheromone production and calling at 4 and 6.15±0.91 days, respectively. Allatectomy of teneral females prevented pheromone production and calling. Both the production and release of pheromone were restored by implantation of active corpora allata or by treatment with a juvenile hormone analogue. Neither nymphal nor adult ovariectomy eliminated pheromone production or calling. The onset age of pheromone production was advanced significantly by both topical juvenile hormone analogue treatment and by transection of the nervi corporis allati I. Denervation of the corpora allata also advanced the onset age of calling. Hence, it is concluded that the corpora allata and juvenile hormone, either directly or indirectly, regulate the onset of both pheromone production and calling in female S. longipalpa.

The corpus allatum in relation to sexual behaviour and aggressiveness in male Supella supellectilium (Serville) (Blattoidea: Blattellidae)

Histological signs of the secretory cycle of the corpus allatum in the adult males of Supella supellectilium correlate well with sexual maturity, behaviour and aggressiveness. Cauterisation of the median neurosecretory cells, allatectomy and implantation of active corpora allata into the allatectomised and cauterised insects suggest that the corpus allatum is primarily responsible for normal sexual behaviour and aggressiveness in the male insect.

Critical period of sensitivity to juvenile hormone for the invagination of tracheoblasts into the developing flight muscle fibers of Locusta migratoria

The effect of juvenile hormone (JH) on the process of tracheolization of the dorsolongitudinal flight muscles of the migratory locust is studied during larval flight muscle development. The ratio of the number of interfibrillar tracheoles in a muscle fiber to the total area of this muscle fiber is used as a parameter for quantitative assessment of the invagination of tracheoblasts into the muscle fibers. Elevation of the hemolymph JH titer following implantation of active corpora allata (CA) during the period of Day 5 of the fourth larval stage up to and including (except in one case) Day 2 of the fifth larval instar results in a complete prevention of the invagination of tracheoblasts into the muscle fibers at the end of the fifth larval stage, whereas implantation of CA on Day 3 and Day 5 of the fifth larval instar results in a partial and decreasing inhibition of the invagination process. The amount of JH III per locust recovered 24 hr after CA implantation on Day 5 of the fifth instar (0.70 ng) is higher than after CA implantation on Day 1 of this instar (0.54 ng), pointing to the absence of a substantial increase in JH-specific esterases. Due to a rise in hemolymph volume, however, JH titer after CA implantation on Day 5 is lower; yet the lowering of the titer is not likely to be responsible for the time-dependent decrease in effect of CA implantation. Rather, because ecdysone titer fluctuates during the last larval instar, it would appear that exogenous JH must be administered before the initial increase in ecdysone titer in order to completely prevent invagination of tracheoblasts into the muscle fibers at the end of the fifth larval instar. It is suggested that JH acts by preventing the development of the tracheoblasts to an ecdysone-receptive state.

Le Contrôle endocrinien de la diapause imaginale des femelles de Tetrix undulata (Sowerby, 1806) (Orthoptere, Tetrigidae)

Imaginal diapause, which is a syndrome-like pseudoallatectomy, is terminated by implantation of active CA (corpora allata). When CA of dispausing females of Tetrix undulata (2 weeks old) are implanted in females also in diapause, vitellogenesis occurs. The same results are observed when CC-(corpora cardiaca) CA (under same conditions) are implanted or when the allatocardiac nerves are cut. But when the complex “brain-CC-CA” is implanted, no vitellogenesis is observed in oocytes. These experiments suggest that CA in diapausing females are inhibited by the brain by a nervous pathway. The cauterization of the pars intercerebralis area brings about vitellogenesis. These experiments suggest that the brain is the place of an inhibitory center which acts by a nervous pathway on the CA of diapausing females. When CA are implanted from females on the first day after the adult molt, or when the allatocardiac nerves are severed on the same day, the oocytes stay the same length as in the sham operation. Connection between the brain and CA are necessary in the beginning of adult life.

Tracheolization and the effects of implantation of corpora allata on the invagination of tracheoblasts into the developing flight muscle fibers of Locusta migratoria

The process of tracheolization of the flight muscle fibers of Locusta, essential for the specific metabolic properties of the adult muscles, occurs during the last part of the fifth larval instar. Several ultrastructural criteria of activity were recognized in the cytoplasm of the tracheoblasts which are concerned with the formation of both small tracheae and interfibrillar tracheoles. The small tracheae appear to originate from an extracellular lumen enclosed by intruding and invaginating tracheoblasts which probably secrete amorphous material used in the formation of an intima bordering the tracheal lumen. Cytoplasmic protrusions of tracheoblasts invaginate into the muscle fibers, enclosing the interfibrillar tracheoles; the exact mode of formation of the latter, however, remains as yet unknown. Connecting links between the small tracheae and the interfibrillar tracheoles probably emerge from evaginations of the plasma membrane of the tracheoblast(s) enclosing the developing small trachea. Implantation of active corpora allata into female locusts on the first day of the fifth larval instar results in a delay in the invagination of tracheoblasts into the muscle fibers till the end of an extra (sixth) larval stage. The relation between tracheoblast development and differentiation of flight muscle enzyme pattern, as well as influences of juvenile hormone and ecdysone on the developmental processes, are discussed.

Diapause of the southwestern corn borer, Diatraea grandiosella: Further evidence showing juvenile hormone to be the regulator

Further evidence is presented to demonstrate the involvement of juvenile hormone (JH) in regulating diapause in the final larval stage of the southwestern corn borer. Diatraea grandiosella. JH titres in the haemolymph were measured throughout the entire diapause period. Additional results showed that actively secreting corpora allata are necessary to maintain diapause because allatectomized larvae terminated diapause prematurely. A topical application of JH mimic 2 days after the allatectomy prevented this premature termination of diapause. Intact nervous connections between the brain and the corpora allata were necessary for the maintenance of JH secretion. Other surgical work showed that the brains of nondiapausing larvae exhibited a higher ecdysiotropic activity than those of pre-, early-or mid-diapausing larvae. A single application of a JH mimic was more effective in maintaining a diapause-like state in nondiapausing larvae than were repeated topical applications of C 18-JH or an implantation of active corpora allata, suggesting that JH was more rapidly metabolized than was the JH mimic. The oxygen consumption of diapausing larvae which had received repeated topical applications of JH mimic was not significantly elevated over that of the controls indicating that treated larvae maintained a low metabolic rate even though they reverted to the spotted morph. A single application of 0.03 μg JH mimic/larva was sufficient to prolong diapause, thereby confirming that JH is necessary for diapause maintenance.

Two-step photoperiodic and hormonal control of reproduction in the female beetle, Pterostichus nigrita

The carabid P. nigrita is a short-day/long-day insect. Short days with less than 15.0 hr of light per day induce pre-vitellogenesis. Vitellogenesis only takes place in subsequent long days with more than 13,1 hr of light. In the range from ld 13:11 to ld 16:8 egg production is possible without a change in photoperiod. Pre-vitellogenesis is induced by the corpus allatum hormone. Implantation of active corpora allata or injection of juvenile hormone substitutes for short-day photoperiods. Histological investigations and implantation experiments revealed that for vitellogenesis some neurosecretion is necessary. Ecdysterone cannot replace this neurosecretion.

Effects of electrocoagulation of cerebral neurosecretory cells and implantation of corpora allata on oöcyte development in Locusta migratoria

The implantation of active corpora allata into intact Locusta females during growth accelerates pre-vitellogenic oöcyte growth and vitellogenesis. Localised stimulation of yolk deposition follows the implantation of active corpora allata between the ovarioles demonstrating a gonadotrophic rôle for the corpus allatum hormone. Electrocoagulation of the median neurosecretory cells of the brain prevents vitellogenesis whilst pre-vitellogenic oöcyte growth occurs normally. Implantation of active corpora allata into females with ablated cerebral neurosecretory cells promotes vitellogenesis in a proportion of test animals although mature oöcytes are never produced. It is suggested that the rôle of the median neurosecretory cells during egg development in Locusta is primarily concerned with the activation and maintenance of activity of the corpora allata. The corpus allatum hormone acts both metabolically and gonadotrophically.

The relationships between corpora allata and fat body and haemolymph lipids in the adult female desert locust

Allatectomy of 1-day-old female desert locusts resulted in an accumulation of lipid in the fat body. This accumulation of lipid was due to the continuation of lipid deposition in the fat body after the period of somatic growth. Somatic growth and feeding activity were unaffected by allatectomy, and so could not be indirect causes of fat body lipid accumulation. Lipid accumulation in allatectomized locusts is more likely to be related directly to a lack of juvenile hormone. Implantation of active corpora allata into 1-day-old adult female locusts resulted in a premature development of oöcytes and a decrease in fat body lipid accumulation; somatic growth was not inhibited. Implantation of active corpora allata into old allatectomized locusts resulted in a decrease in the fat body lipid content and the onset of oöcyte development. The lipid synthetic activity of the fat body, measured by the incorporation of 14C-actate into total fat body lipid, was greatly increased in allatectomized locusts after the period of somatic growth. The protein synthetic activity of the fat body, measured by the incorporation of 3H-leucine into total fat body protein, remained low after the period of somatic growth in allatectomized insects. Juvenile hormone might thus have a dual effect on fat body metabolism, that is suppressing lipid synthesis and stimulating vitellogenic protein synthesis. Increased synthesis of lipid by the fat body would then account for the accumulation of lipid in the fat body after allatectomy. Inhibition of release of lipid from the fat body is unlikely to play a part in the accumulation as allatectomy had no effect on haemolymph lipid concentrations.

The metabolic effects of the corpus allatum hormone in the male desert locust. I. Lipid metabolism.

ABSTRACT An account is given of the normal pattern of total lipid content of male desert locusts from the time of adult emergence to the time the locusts are approaching senescence (18—25 days). Up to the seventh adult day, there is a rapid increase in the amount of body lipids ; thereafter, there is a progressive depletion of lipid reserves. Allatectomy of the locusts soon after adult emergence leads to considerable accumulation of lipids which becomes apparent when the locusts attain sexual maturity and persists thereafter. Gonadectomy or mere wounding has no such effects. Implantation of active corpora allata in previously allatectomized locusts reverses the tendency to lipid accumulation.

THE CORPUS ALLATUM AND OÖCYTE MATURATION IN ADELPHOCORIS LINEOLATUS (GOEZE) (HEMIPTERA: MIRIDAE)

The corpus allatum undergoes marked changes in volume and histological appearance during egg maturation in the adult female of Adelphacoris lineolatus (Goeze). The allatum is very active just before yolk is deposited in the developing oöcytes, but activity declines rapidly at oviposition. This activity in the corpus allatum cannot be correlated with cyclical activity in the cerebral neurosecretory cells. Experiments involving removal of the corpus allatum show that the gland is necessary for oöcyte growth. Implantation of active corpora allata into allatectomized females will not restore egg maturation, and the implanted glands lose their secretory ability. It seems that the corpus allatum in this insect must retain anatomical connection with the central nervous system to produce its hormone.

THE JUVENILE HORMONE. V. THE SENSITIVITY OF THE BUG, PYRRHOCORIS APTERUS, TO A HORMONALLY ACTIVE FACTOR IN AMERICAN PAPER-PULP

When reared in the Biological Laboratories at Harvard University, the European bug, Pyrrhocoris apterus L., failed to undergo normal metamorphosis. In the initial cultures, 1,215 individuals showed normal growth and moulting until the fifth larval instar. Then, instead of metamorphosing into adults, all except one individual underwent a supernumerary larval moult to form “?�perfect” sixth instar larvae or adultoid sixth instar larvae (Table I ) . All the perfect sixth instar larvae underwent yet another supernumerary moult to form even larger seventh instar larvae or seventh instar adultoid larvae. Of the entire group of 1,215 larvae, only one individual completed metamorphosis and attained sexual maturity. Among tens of thousands of Pyrrhocoris which one of us (K. S.) had cultured in Prague, the spontaneous formation of a sixth instar had never been encountered. Metamorphosis had always taken place at the end of the fifth larval stage—a result directly attributable to the inactivation of the corpora allata and the cessation of juvenile hormone secretion at the outset of the fifth instar (SlAima, 1962) . The formation of sixth stage larvae had been provoked only in experiments in which juvenile hormone was supplied by the implantation of active corpora allata (Novak and SlAima, 1961 ; SlAima, 1964a) . For these several reasons, it seemed certain that the Harvard cultures of Pyrrhocoris had access to some unknown source of juvenile hormone. One possibility was that some feature of the Harvard environment served to prevent the normal inactivation of the animal's own corpora ailata and that, in this indirect manner, metamorphosis was blocked by the prolonged and abnormal secretion of juvenile hormone. An alternative possibility was that the Harvard cultures were under the influence of an environmental factor which, in itself, possessed juvenile hormone activity. The present study initiates a detailed investigation of the phenomenon.

Biochemical Aspects of Juvenile Hormone Action in the Adult Locusta Migratoria by

Biochemical Aspects of Juvenile Hormone Action in the Adult Locusta Migratoria by

A correlation between feeding and the sexual cycle in Leucophaea maderae (Blattaria)

Females of Leucophaea maderae ate increased amounts of solid food after emergence and parturition prior to egg maturation. Allatectomized and virgin females ate similar amounts of food after emergence. Pregnant females ate little. The removal of the egg cases in pregnant females was followed by an increased food consumption correlated with egg maturation. Thus, a restriction of feeding in pregnant females was caused by the egg cases in the brood sacs. A slightly increased food intake was induced in pregnant females by the implantation of active corpora allata which caused egg maturation. In these animals feeding was still restricted by the egg cases in the brood sacs. Thus, egg maturation stimulated food intake if not enough food reserves were available for the completion of yolk deposition. Active corpora allata did not influence the feeding activity of the females. The restriction of feeding during pregnancy is most likely brought about via a pathway separate from that responsible for the inhibition of the corpora allata during pregnancy.