Juvenile hormone and reproduction in the cricket. II. Effect of rearing temperature on corpus allatum activity (in vitro) in adult females

Summary In the Mediterranean field cricket,Gryllus bimaculatus, reproduction is controlled by temperature and the corpus allatum (CA) hormone JH III. In CA of females reared at 24°12°C(168 h) (high reproduction rate) a first peak in JH III synthesis is reached about 4 days earlier than in those of 20°C females (low reproduction rate). Furthermore, in 20°C animals CA activity is low during the entire oviposition period, whereas at 24°12°C high CA activity is found during this period of adult life. The results indicate a stimulation of CA activity and reproduction by thermoperiods around a constant low temperature.Supported by the DFG (SFB 87 A 4).     

Cyclic activity of the corpus allatum related to gonotrophic cycles in adult femalePeriplaneta americana

Zusammenfassung Durch Inkorporation von¹⁴C-Methionin in die Corpora allata vonPeriplaneta americana werden während des Eireifungszyklus zwei Aktivitätsmaxima festgestellt und diese als Juvenilhormonsynthese interpretiert.     

Radiochemical assays of corpus allatum activity in adult female cockroaches following ovariectomy in the last nymphal instar

Summary Surgical removal of the ovaries from nymphalPeriplaneta americana results in lower than normal corpus allatum activity in the adult insect and an apparent absence of the manifestly cyclic pattern of juvenile hormone biosynthesis found in intact mated females. The results suggest that the presence of synchronously developing ovaries is necessary for the attainment of normal synthetic activity in the corpus allatum of this species.Acknowledgment. I thank Dr G. E. Pratt for his helpful advice and stimulating discussions on the subject.     

Control of corpus allatum activity inDiploptera punctata: roles of the pars intercerebralis and pars lateralis

Summary Control of the corpora allata (CA) ofDiploptera punctata is maintained by at least 2 factors. The glands are directly inhibited by an allatostatin arriving at the CA via the nervi corporis cardiaci I (NCC I). Destruction of the putative source (median neurosecretory cells, MNC) of the allatostatin by radio-frequency (RF) cautery relieved the inhibition imposed on the CA of virgin females, and the glands became active. Similarly, destruction of the lateral neurosecretory cells (LNC) also relieved the inhibition. We propose that the LNC stimulated the MNC to release allatostatin. RF-cautery did not result in the activation of CA of pregnant or ovariectomized females. Activation of the CA may therefore require not only absence of the inhibitory factor but also the presence of a stimulatory one (perhaps from the ovary).     

Delayed effects of juvenile hormone analogues on metamorphosis ofPyrrhocoris apterus are not mediated by the corpus allatum

Summary While it is clear that juvenile hormone analogues disturb metamorphosis, there is some controversy about their effect on the activity of the corpus allatum in the course of metamorphosis. The present experiments showed that juvenile hormone analogues applied to eggs did not prevent inactivation of the corpus allatum at the onset of the last larval instar ofPyrrhocoris apterus.     

Monoamine oxidase activity of the hypothalamus and pituitary: alterations after pinealectomy, changes in photoperiod, or additions of melatonin in vitro.

Rat pituitary MAO activity was reduced by constant darkness and by additions of melatonin in vitro and was increased by constant light and by pinealectomy. Hypothalamic MAO activity followed the same pattern but was less dramatically affected. The data suggest that MAO may be a target enzyme for melatonin.     

Effect of photoperiod on early changes in the neonatal rat pineal gland

Summary It is concluded that photoperiod has little direct effect on the mitotic activity or morphological development of the pineal parenchymal cell of the rat in the early postnatal period.     

Effect of photoperiod and all-female grouping on the estrous cycle of the bandicoot rat,Bandicota bengalensis

Summary Female bandicoot rats showing irregular cycles in 12L12D, were exposed to light-darkness cycles of 1L23D, 4L20D and 8L16D. Significant regularization of the estrous cycle was observed in 8L16D with most of the rats exhibiting a regular 3-day cycle and the regularity was further enhanced by all-female grouping (4/cage).     

Effect of pretreatment with prednisolone on the phagocytic activity of mouse peritoneal macrophages in vitro

Summary The phagocytic activity on in vitro cultured mouse peritoneal macrophages derived from animals treated with 6-alpha-methyl-prednisolone was examined. The statistical evaluation of results showed an increase of phagocytic activity of macrophages derived from treated animals in comparison with controls.     

Effect of hormones on adenyl cyclase activity of rabbit mammary gland in vitro

Summary Ovarian hormones namely-estradiol and progesterone were observed to stimulate the activity of adenyl cyclase of the mammary gland from pregnant rabbit in vitro, unlike the lactating tissue where it was inhibited. On the other hand, non-ovarian hormones like hydrocortisone, prolactin and insulin did not have a similar effect on this enzyme.Acknowledgement. We are indebted to Dr D. Sundaresan, for his kind encouragement in this study.     

Effect of hormones on adenyl cyclase activity of rabbit mammary gland in vitro

Ovarian hormones namely beta-estradiol and progesterone were observed to stimulate the activity of adenyl cyclase of the mammary gland from pregnant rabbit in vitro, unlike the lactating tissue where it was inhibited. On the other hand, non-ovarian hormones like hydrocortisone, prolactin and insulin did not have a similar effect on this enzyme.     

Effect of temperature on in vitro proliferative activity of human umbilical vein endothelial cells

Human umbilical vein endothelial cells, skin fibroblasts, and retinal pigment epithelial cells are cultivated in medium supplemented with 15 to 20% serum in our laboratory. The effects of various incubation temperatures on the proliferation of these cells was examined. Our study shows that the mitogenic response of the endothelial cells to a change of temperature differed markedly from that of the fibroblasts and epithelial cells. Cultivation of human umbilical vein endothelial at 37°C required seeding densities as high as 1–2×10⁴ cells/cm², and yet resulted in a low growth rate and premature senescence. However, under the same culture conditions, but at 33°C, the proliferative capacity of these endothelial cells was potentiated. The results were striking; at 33°C the cells grew actively and the life span was extended. The number of cumulative population doublings increased fourfold compared with that for the same cells cultivated at 37°C. The inoculum size could be reduced, since at 33°C the endothelial cells were able to replicate at seeding densities as low as 20 cells/cm². The cells serially subcultured at 33°C retained morphological features and specific immunological markers of endothelial cells.     

The clerid beetle,Thanasimus formicarius,is attracted to the pheromone of the ambrosia beetle,Trypodendron lineatum

Summary Sticky traps containing (+)-lineatin, the pheromone of the ambrosia beetle,Trypodendron lineatum, attracted the predatorThanasimus formicarius to about the same extent as traps baited with ipslure, the pheromone blend used for mass-trappingIps typographus. The results indicate thatT. lineatum is an important prey forT. formicarius early in the season before the main prey becomes active. Addition ofexo-brevicomin to ipslure and ethanol and/or -pinene to (+)-lineatin did not significantly influence the catches of the predator.