首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 171 毫秒
1.
Brains of young (newly emerged) adult female locusts (Locusta migratoria migratorioides) and of mature (> 9 days old) locusts contain an extractable allatotropic factor, soluble in 100% methanol and in distilled water. This factor stimulates juvenile hormone III (JH III) synthesis and release from corpora allata (CA) that have been excised from donor locusts and then incubated with (radiolabeled methyl)-methionine in vitro in its presence. In addition to JH III, which is the major product synthesized by the CA, other hexanesoluble, radiolabeled compounds–-more polar than JH III–-are also released when CA are incubated in vitro. The activation of CA by the allatotropic factor is rapid and quickly declines when the factor is removed from the medium. Corpora allata excised from young females are marginally active and can be activated by brain allatotropic factor to less of an extent than CA of mature locusts. The content of allatotropic factor in brains of mature locusts is higher than that ascertained in brains of young females. Allatotropic factor is also present in the corpora cardiaca.  相似文献   

2.
Both allatotropic and allatostatic activities were found in crude extracts of brain from adult and larval Eri silkworm, Samia cynthia ricini, but it seems that allatotropic activity dominates in each stage. There was a high level of allatotropic activity in the crude extract of brain from newly emerged female adults, but allatostatic activity appeared in the bioassay when excessive amounts of crude extracts of brain were added. Crude extracts of brain from premoulting fourth‐instar larvae and from newly ecdysed fifth‐instar larvae exhibited allatotropic activities, whereas extracts of brain from the second and third day of the fifth‐instar larvae inhibited juvenile hormone (JH) release slightly. Allatotropic activity from the brains of adults and larvae stimulated both adult and larval corpora allata (CA) to synthesize JH. Manduca sexta allatotropin (AT) (Mas‐AT) and M. sexta allatostatin (AST) (Mas‐AST) also stimulated and inhibited both adult and larval S. cynthia ricini CA to synthesize JH, respectively. Higher concentrations of Mas‐AT (10?4 or 10?3 M) showed an inhibitory effect on adult CA. CA from newly emerged female adults were the most sensitive to inhibition by Mas‐AST, whereas CA from female pharate adults at about 6 h before adult emergence were the most sensitive to stimulation by Mas‐AT and S. cynthia ricini brain allatotropic activity. An extract of brain and Mas‐AT induced some of the non‐active female pharate adult CA at 12 h before emergence to synthesize a small amount of JH.  相似文献   

3.
Newly emerged adult holometabolous insects must still complete considerable morphological, metabolic, and neural maturation. Despite this, adults have frequently been documented to fly prior to finishing maturation and attaining peak physiological capacity. In some species, flight is limited by the unfurling of the wing, while in other species it may be limited by biochemical capacity. We charted maturation trajectories of adult bumblebee workers (Bombus impatiens) for both morphological and flight muscle metabolic capacities, and compared these to the first age at flight. Workers began regular flights as soon as two days after emergence. The unfurling of the wings was completed well before first flights and before any other studied factor, suggesting this did not initially limit flight. Wing beat frequencies, measured as a struggling response to grasping the hindlegs, were about 90% mature by two days old, and did not significantly change after three days. Conversely, by the initiation of flight, the mean enzyme maturation was only 63% completed relative to adult enzyme capacity, though specific enzyme profiles ranged from 42% to 73%. Maximum ADP-stimulated mitochondrial respiratory activity on pyruvate and proline matured along a similar time frame to glycolytic capacity, reaching its maximum three days after emergence. Bumblebees, as other adult insects, thus begin flights prior to fully maturing.  相似文献   

4.
A Togari  K Kojima  T Nagatsu 《Life sciences》1985,37(17):1605-1611
Newly synthesized tyrosine hydroxylase (TH) induced by reserpine was compared with the enzyme in control rats in terms of the molecular and physiological properties. When repeated doses of reserpine were given at daily intervals for three days, the enzyme activity measured in homogenates of the adrenal glands was increased 3-fold. Furthermore, when TH in the adrenal glands from both control and reserpine-treated rats was purified, both total activity of the enzyme and the enzyme protein content purified from reserpine-treated rats were also about 3-fold higher than those of the control rats. The two purified enzymes revealed similar properties; a single subunit with a Mr of 60,000 was observed by SDS polyacrylamide gel electrophoresis, and the Km value for a pterin cofactor, 6-methyl-tetrahydropterin was about 300 microM. In contrast, in situ TH activity measured under physiological conditions at pH 7.2 in adrenal tissue slices was elevated 6-fold by reserpine pretreatment for 3 days, and was stimulated by carbachol (0.1 mM) and elevated K+ (52 mM) in a roughly proportional rather than additive way relative to slices from untreated rats. These results indicate that newly synthesized TH induced by reserpine in rat adrenal gland had similar properties as the enzyme in control rats and that reserpine increased not only the amount of TH molecules but also the in situ activity of TH. Since reserpine also increases the biosynthesis of tetrahydrobiopterin as demonstrated by Viveros and co-workers, this 6-fold increase in in situ TH activity may depend both upon the 3-fold increase in the amount of enzyme molecules and upon the increase of the physiologically available tetrahydrobiopterin in the adrenal gland.  相似文献   

5.
Allatotropic activity is found in methanolic extracts of the brain–suboesophageal ganglion (SOG)–corpora cardiaca (CC) complex from virgin males of Mythimna loreyi Duponchel (Lepidoptera, Noctuidae). Corpora allata (CA) from 6‐day‐old virgin males exhibit low rates of release of Juvenile Hormone (JH) acid (JHA) in vitro. Release of JHA can be activated by the addition of an extract of brain–SOG–CC complex in a dose‐dependent manner, and this allatotropic activation can be sustained consistently in the continuous presence of such extracts. Based on its trypsin sensitivity and heat stability, the allatotropic factor is most likely a peptide. The allatotropic activity is dependent on the concentration of calcium ions in the medium, with the highest activation achieved beyond 2 m m . The results of nerve transection experiments suggest that both nervi corporis allati I (NCA I) and NCA II are involved in mediating the allatotropic control of CA in vitro. Isolated CA alone show significantly higher rates of release of JHA than the intact brain–SOG–CC–CA complex during the first 3 h of incubation, but the release of JHA reaches almost the same range in both groups by the end of the fourth hour of incubation.  相似文献   

6.
7.
We assessed the effects of age and mating status on in vitro juvenile hormone (JH) biosynthesis, oocyte growth, egg production and vitellogenin (Vg) accumulation in the tortricid moths, Choristoneura fumiferana and C. rosaceana. To determine whether vitellogenesis is dependent on the presence of JH, we also examined the effects of decapitation and JH analog treatments on egg production. In both species, the corpora allata (CA) of adult females released fmol quantities of JH, with JH II being the major homolog produced. The CA began producing detectable quantities of JH around the time of emergence. Full activation of the CA was observed a few hours sooner in C. fumiferana than in C. rosaceana. In pharate adults and young virgin females of both species, growth of the basal oocyte reflected changes in CA activity. Decapitation of newly emerged females significantly reduced egg production, but treatment of decapitated females with the JH analog methoprene resulted in egg production that was similar to (C. fumiferana) or greater than (C. rosaceana) that of controls, indicating that JH is required for oocyte maturation. Vg was first observed in the hemolymph before the presumptive time of CA activation, suggesting that the synthesis of this protein is not dependent on JH. The presence of normal quantities of Vg in the hemolymph of pupae decapitated before CA activation confirmed this hypothesis. The Vg titer underwent a transient decline following CA activation and was significantly lower in mated than in virgin females of both species 3 and 5 days after copulation. Since CA activation at emergence and mating are both expected to cause a rise in the JH titer, we suggest that the declines in the levels of Vg result from JH-enhanced Vg uptake by the developing oocytes. Mating induced a significant increase in egg production but had no measurable impact on rates of JH biosynthesis in vitro.  相似文献   

8.
Studies were undertaken to determine whether adult males of Heliothis virescens transfer juvenile hormone (JH) to females during copulation, and an in vitro radiochemical assay was used to determine whether mating causes an allatotropic effect, i.e., stimulation of JH biosynthesis by corpora allata (CA). In vitro, CA from 3-day-old mated females synthesized and released approximately 2.5 times total JH as that of CA from comparably aged virgin females. Of the homologues, JH II exhibited significant increase in mated females; JH I also increased but not significantly. JH III remained similar to that of virgin females. This is the first demonstration of an allatotropic effect of mating in moths. In contrast to the female, CA of virgin males did not produce any JH, but accessory sex glands (ASG) in 3-day-old males synthesized small amounts of JH. Immediately after adult emergence, male ASG contained approximately 1.5 ng JH I and II, which increased by 12 h after emergence and remained at this high level up to 54 h after emergence. JH III was barely detected in ASG. JH in ASG of mated male immediately after uncoupling was depleted almost completely, and 24 h later recovered to levels comparable to that of 54-h-old virgin male. Virgin female bursa copulatrix did not contain any JH, but mated female bursa, immediately after uncoupling, had JH at levels comparable to that observed in virgin male ASG. By 6 h after uncoupling, JH levels decreased dramatically in mated female bursa. These data suggest the transfer of JH to females by the male. Arch. Insect Biochem. Physiol. 38:100–107, 1998. © 1998 Wiley-Liss, Inc.  相似文献   

9.
Juvenile hormone (JH) titers must be modulated to permit the normal progress of development and reproduction in mosquitoes. In adult female Aedes aegypti, JH levels are low at adult eclosion, elevated in sugar-fed females and low again after a blood meal. Although degradation plays a role, JH titer is fundamentally determined by the rate of biosynthesis in the corpora allata gland (CA). CA from newly eclosed females (0-1 h after emergence) exhibit a very low basal JH biosynthetic activity, Aedes-allatotropin stimulates the CA in newly emerged females to produce JH. There is a correlation between nutritional reserves at adult emergence (teneral reserves) and CA activity. JH synthesis is significantly reduced in teneral females that emerge with low nutritional reserves. Taking a blood meal results in a reduction of CA activity. The biosynthetic activity of Ae. aegypti CA is significantly inhibited by factors present in the head, as well as by Anopheles gambiae PISCF-allatostatin. Nutritional signals affect the release of allatotropin and allatostatins by the brain resulting in the activation or inhibition of JH synthesis. JH is therefore an important part of a transduction mechanism that connects changes in the nutritional status with activation of specific physiological events during reproduction.  相似文献   

10.
Allatotropic activity was found in the methanolic extract of the suboesophageal ganglia (SOG) and the corpora cardiaca (CC) of the Mythimna loreyi virgin males. No allatotropic activity was observed in the extract of brain or corpora allata (CA). Although CA can be activated by the SOG and CC extract, respectively, CC extract inhibited the response to the SOG extract. A significant in vitro allatotropic effect was exerted by the SOG and CC extract within 10 and 15 min, respectively, and this effect can be sustained for several hours even after transferring to fresh medium without extracts. The time course pattern of the CA activation ratio in both the SOG and CC extract-treated group is very similar to, but with significantly higher level than, that in the control group, suggesting the existence of an intrinsic pacemaker or an in vitro effect that controls the fluctuation of the CA biosynthetic activity. Synthetic Manduca sexta allatotropin had no significant effect on the M. loreyi CA. The results of treatment with the adenylate cyclase activator forskolin, the phosphodiesterase inhibitor IBMX, and the cAMP analogue dibutyryl-cAMP did not indicate that cAMP might be involved in the allatotropic control of CA. Arch.  相似文献   

11.
ABSTRACT. Female P. americana, reared with males from the time of adult emergence, mated on the 4th–5th day after metamorphosis, produced the first ootheca on the 8th or 9th day, and then produced successive oothecae at intervals of 3.0 days, whereas, only 50% of virgin females had produced their first ootheca by the 28th day after adult emergence. Examination of the ovaries indicated that oocyte development is normal in virgins until shortly after the time when they first become receptive to males. When mating was not allowed there was a dramatic reduction in the rate of vitellogenic growth of the terminal batch of oocytes which persisted until mating was allowed, and was often accompanied by resorption of a percentage of the oocytes. Short-term, in vitro, radiochemical assay of juvenile hormone (JH III) biosynthesis by corpora allata (CA) showed that, in females reared with males, the cycles of ovarian development are accompanied by regular pulses of CA activity. There is a small, possibly preparatory peak of JH III biosynthesis before vitellogenesis of the first wave of oocytes, followed by a larger peak of JH III production during vitellogenesis of this batch of eggs and one peak of CA activity between ovulation of each subsequent wave of oocytes. Activities as low as 0.25 pmol C16JH/CA pair/h and as high as 48.38 pmol/CA pair/h were observed in CA from mated females after the onset of cyclic activity. Stimuli received during mating are somehow responsible for the cyclic activity of the CA, for when females were subjected to enforced virginity the first small peak was normal but the second peak was not fully realized and there was then a gradual decline in CA activity until approximately 2 weeks post-emergence. Thereafter the glands exhibited a more or less constant rate of JH biosynthesis (mean = 3.45 ± 0.32 pmol/CA pair/h.) When females were mated after 21 days of enforced virginity the activity of the CA was enhanced. By 48 h after mating the mean glandular activity was at least four times that found in virgins of the same age, and by 72 h rates as high as 40 pmol/CA pair/h were observed. This was followed by normal cyclic activity of the CA. The increase in rate of JH biosynthesis appears to result in a recommencement of oocyte development in these ‘delayed-mated’ females.  相似文献   

12.
The effects of NeemAzal-T/S®, a commercial neem product, on different life development stages of the common greenhouse whitefly Trialeurodes vaporariorum Westwood (Hom., Aleyrodidae) were tested in laboratory and greenhouse experiments. Treatment of eggs of T. vaporariorum did not affect either larval emergence or the time until larval emergence. However, the proportion of pupal formation (based on the numbers of emerged larvae) was significantly reduced after a treatment of the eggs 3, 5 and 7 days after oviposition, respectively. The proportion of emerged adults (based on the number of formed pupae) was only significantly reduced when eggs had been treated 5 and 7 days after oviposition. In all neem treatments the time until adult emergence was significantly delayed. A neem treatment of early larval instars of T. vaporariorum resulted in a significantly reduced proportion of pupal formation, but subsequent adult emergence (based on the number of formed pupae) was not affected. Treating early larval instars of T. vaporariorum significantly prolonged the time until adult emergence. A neem treatment of T. vaporariorum pupae significantly reduced the proportion of emerged adults but had no effect on the time until adult emergence. Exposing female whiteflies to fresh, 24-h-old and 72-h-old residues of NeemAzal-T/S® had no effect on the mortality of the insects, though the number of eggs laid per female was significantly reduced in T. vaporariorum exposed to fresh neem residues. These findings are discussed within the context of integrated control of whiteflies in the greenhouse environment.  相似文献   

13.
ABSTRACT. The medial neurosecretory cells (MNC), corpus allatum (CA) and ovaries of Lucilia sericata Mg. are quiescent in mature flies fed on a diet of sugar and water, but these tissues rapidly respond to the ingestion of a protein meal. The present study revealed that after oogenesis, virgin flies synthesized and stored neurosecretory material, but this activity declined as they grew older. At the same time, the CA, following a decrease in size during the latter stages of oogenesis, became enlarged again. This is interpreted as denoting synthesis but not release of CA hormone. In meat-fed mated flies, cycles of oviposition and oogenesis were reflected in the rise and fall in activity of the MNC and CA. The MNC and CA of male flies also responded to the ingestion of a protein meal, and the activity of these tissues persisted for several days before it declined. The similar response of the MNC and CA in both males and females demonstrates the importance of a meat meal to reproduction in this species: in females it is required for oogenesis, but its ingestion by both sexes is necessary for overall reproductive success.  相似文献   

14.
In Phormia regina, the rate of juvenile hormone (JH) synthesis rises rapidly after the ingestion of an adequate protein meal. In a previous publication we have localized the neurons containing Manduca sexta allatotropin (Mas-AT)-like substances in the brain of P. regina and demonstrated the allatotropic effect of synthetic Mas-AT in sugar-fed flies in vitro. In this current study, we examined the possible role of the brain of P. regina after the fly received a protein meal. In vitro studies showed that the brain releases, at 8 h after a protein meal, a factor(s) with a strong allatotropic effect. This factor(s) stimulates the corpus allatum (CA) to produce 6.9 times more juvenile hormones (JHs) than the control CA. Time course studies showed that the release of this allatotropic factor(s) is temporally controlled. Only the brains collected from flies at 6 and 8 h after the onset of a liver meal release allatotropic factor(s). Injection of anti-Mas-AT antiserum partially suppressed the fly follicle development in vivo. Presence of anti-Mas-AT antiserum decreased the allatotropic effect of the brain released allatotropic factor(s) in vitro. In addition to a Mas-AT-like substance, it is possible that the brains of liver-fed P. regina females may synthesize other allatotropic factors that are chemically unrelated or partially related to Mas-AT, which cannot be recognized/neutralized by our anti-Mas-AT antiserum.  相似文献   

15.
ABSTRACT. Effects of egg availability on daily ovipositional activity were determined for Coccophagus atratus Compere (Hymenoptera: Aphelinidae). Females were observed for 6 h per day for their entire adult lives. Observed ovipositional activity was analysed in relation to egg maturation before and after emergence, egg depletion during oviposition and egg replenishment after oviposition. Ovipositional activity, including oviposition, inconsequential probes and searching for hosts, occurred predominantly in the first 30 min of exposure to hosts on the 2nd, 4th, 7th, 10th and 13th days after emergence. The remaining time was spent on non-ovipositional activities (preening, drinking honeydew and sitting on the glass of the experimental arena). Peaks of ovipositional activity were associated with high numbers of mature eggs in the ovaries. Eggs that remained in the ovaries after a bout of oviposition were apparently not mature even though they had attained their maximum size. Non-ovipositional activity continued until females had built up a reserve of about eighteen mature eggs. After each successive bout of oviposition, the rate of oogenesis slowed down. Consequently females took longer to accumulate a supply of eggs and periods of non-ovipositional activity increased.
We conclude that (1) the availability of eggs and the tendency of females to store mature eggs influences ovipositional activity, (2) full-sized eggs are not necessarily mature, (3) future experiments with C.atratus could be restricted to days of high ovipositional activity, and (4) the terms syn- and pro-ovigenic formulated by Flanders (1950) to describe apparent differences in oogenesis between various parasitic Hymenoptera do not apply to C. atratus and are therefore not universally applicable.  相似文献   

16.
ABSTRACT. Of sixty-seven adult female Periplaneta americana (L.) isolated when less than 8h old and kept without food at 25–30°C in LD 12:12, only six produced oothecae during 25–35 days. Growth of the basal oocytes was retarded, and maximal oocyte volume, only one-third of that in fed virgins, was achieved after about 12 days. By day 14, 60% of the basal oocytes were being resorbed in the starved females, and corpora lutea were usually all that remained beyond day 20. Oocyte growth was potentiated in starved, virgin females by severing either of the two nervi corporis allati 1 (NCA 1), and oothecae were then produced in 45–80% of cases. Sham-operated controls oviposited in fewer than 27% of the trials. Because oocyte maturation was prevented by extirpating both corpora allata (CA), but not when the glands were replaced, and because the juvenile hormone analogue, ZR 515, was highly effective in causing the starved cockroaches to produce oothecae, the starvation-induced reproductive failure probably reflects diminished hormone production by the CA. The most likely consequence of severing NCA 1 is de-repression of juvenile hormone production. The directness of the neural influence was shown by removing the one denervated CA, in which case stimulation of oogenesis was minimal even though the contralateral innervated gland was present. The incidence of ootheca production was not enhanced by transecting the NCA 2, which suggests that the CA of starved cockroaches are not inhibited via this pathway.  相似文献   

17.
Food utilization was measured in female fifth instar larvae and adults of the migratory locust by following the weight of food ingested, the weight of faeces produced, and the increase in body weight. These parameters were measured in normally developing locusts, in locusts that had been implanted with a pair of active corpora allata (CA) in the beginning of the fifth instar period, and in allatectomized locusts, operated on the first day after adult ecdysis.A high titre of corpus allatum hormone results in a considerably higher water content of the insects; allatectomy reduces this content. The dry weight of the locusts is not essentially influenced by excess or absence of juvenile hormone.Food consumption in corpora-allata-implanted locusts does not differ from that in normally developing insects. Within each developmental period the digestive capacity remains constant, but the absolute value of this capacity may differ between the two developmental periods. The approximate digestibility is somewhat higher after CA-implantation and lower after allatectomy. The efficiency of conversion of digested food into body substance is greater in normally developing larvae than in adults. CA-implantation lowers this efficiency in developing larvae. Allatectomy slightly raises the efficiency of conversion in adult locusts.In the second half period of larval development, CA-implantation raises the respiratory rate, as estimated by measuring oxygen consumption. During adult development no significant influence of CA-implantation on respiration was established. Relations between the amount of food digested, the efficiency of conversion of digested food into body substance, and the respiratory activity are discussed.  相似文献   

18.
Application of precocene II, either topically or by contact method, to newly emerged adult females of O. fasciatus inhibits egg maturation and induces degeneration of the corpus allatum (CA). Seven days after precocene-treatment the CA were very small. Ultrastructural studies revealed a number of disintegrating nuclei, degenerating mitochondria, lysosome-like bodies and autophagic vacuoles. Fifteen days after precocene treatment the CA showed further reduction in the size and number of cells, and the degenerative changes were much more pronounced. It appears that the effect of prococene on the CA is irreversible.  相似文献   

19.
Field observations on the relationship between male mating success and emergence timing in the funnel-web spider,Agelena limbata, were conducted.Agelena limbata is an annual species and adult males appear slightly earlier than adult females in July. As males deposit a copulatory plug at the female epigynum after copulation, copulation with virgin females is important to males. The number of copulations in males with virgin females, which strongly correlates with the longevity of males and the number of females that males courted, did not correlate with the emergence timing of males. Early emerged males and females were significantly larger in size than later ones, but the correlation coefficient between the emerged date and the cephalothorax width was not strong. Males that emerged earlier did not have any advantage in copulating with larger and more fecund females. Furthermore, virgin females first copulated on average 7.9 days after their final molt and the mortality rate of adult males increased after the final molt. These factors may favor the smaller degree of protandry in male emergence timing inA. limbata.  相似文献   

20.
Regulation of mitochondrial functions in vivo by catecholamines was examined indirectly by depleting the catecholamines stores by reserpine treatments of the experimental animals. Reserpine treatment resulted in decreased respiratory activity in liver and brain mitochondria with the two NAD+-linked substrates: glutamate and pyruvate + malate with succinate ATP synthesis rate decreased in liver mitochondria only. With ascorbate + TMPD system, the ADP/O ratio and ADP phosphorylation rate decreased in brain mitochondria. For the heart mitochondria, state 3 respiration rates decreased for all substrates. In the liver mitochondria basal ATPase activity decreased by 51%, but in the presence of Mg2+ and/or DNP increased significantly. In the brain and heart mitochondria ATPase activities were unchanged. The energy of activation in high temperature range increased liver mitochondrial ATPase while in brain mitochondria reserpine treatment resulted in abolishment in phase transition. Total phospholipid (TPL) content of the brain mitochondria increased by 22%. For the heart mitochondria TPL content decreased by 19% and CHL content decreased by 34%. Tissue specific differential effects were observed for the mitochondrial phospholipid composition. Liver mitochondrial membranes were more fluidized in the reserpine-treated group. The epinephrine and norepinephrine contents in the adrenals decreased by 68 and 77% after reserpine treatment.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号