William S. Herman

Characterization of a second peptide with adipokinetic and red pigment-concentrating activity from the locust corpora cardiaca

Abstract A new peptide with both adipokinetic activity in the locust and red pigment-concentrating activity in the shrimp, can be readily separated from the adipokinetic hormone in extracts of corpora cardiaca (CC) from Schistocerca americana gregaria by the use of gel chromatography and the Leander adspersus bioassay. The new peptide accounts for 20% of the total biological activity in locust CC, and it is located principally in the CC glandular lobe. The amino acid composition of the pure peptide is: Asp, Thr, Ser, Glu, Gly, Leu, Phe, Trp. This composition is similar to, but not identical with the red pigment-concentrating hormone of the shrimp.

Effect of photoperiod and temperature on reproduction of the monarch butterfly, Danaus plexippus☆

Abstract Optimal posteclosion ovarian development in monarch butterflies occurs at about 28°C. Higher and lower temperatures appear progressively inhibitory. Reproductive gland development in males follows a similar pattern. Juvenile hormone injections stimulate oocyte maturation in animals held at 20 and 35°C but are most effective at the higher temperature. Juvenile hormone injections are ineffective at 10 and 15°C. The stimulatory effect of increasing photophase on ovarian development was most apparent at optimal temperature. The possible significance of our findings to monarch migration is discussed.

Homocellular and heterocellular gap junctions in Limulus: A thin-section and freeze-fracture study

Gap junctions between three different cell combinations in Limulus are studied with thin-section, lanthanum-tracer, and freeze-fracture techniques. Midgut epithelial (E) cells form E—E gap junctions. Reserve (R) cells adjacent to the outer surface of the midgut form R—R gap junctions. E—R junctions are formed when R-cell processes extend through a basement membrane and contact E-cells. All junctions possess parallel membranes with 30 A gaps, polygonal substructure when treated with lanthanum and sectioned en face , and electron-dense 25 A dots in subunit centers. In freeze-fracture replicas only E—E and R—R junctions can be identified. All junctions possess aggregates of 125 A particles in each membrane. Particles are observed only on outer fracture faces and, like the complementary pits, are not highly patterned. In both particle centers and pits, 30 A spots of platinum are seen. The substructure of gap junctions between cells of the same type appears indistinguishable from that between different cell types.

STUDIES ON THE ADULT REPRODUCTIVE DIAPAUSE OF THE MONARCH BUTTERFLY, DANAUS PLEXIPPUS

Monarch butterflies obtained at monthly intervals during the annual adult cycle were held in summer conditions for 5, 10, and 20 days. Examination of these revealed in both sexes an adult reproductive diapause characterized by depressed growth of those reproductive organs sensitive to juvenile hormone. Diapause began for both sexes in late August or early September; female diapause ended in December while male diapause ended in November. Diapause intensity, maximal in September-October, appeared to be greatest in females. In summer conditions, reproductive tract growth in postdiapause females, but not males, was comparable to that observed in prediapause animals. Previously mated postdiapause, but not diapause, females showed a greater response to summer conditions than did virgins. Storing prediapause monarchs in winter conditions for up to 5 months did not induce diapause, indicating that diapause may be induced in a preadult stage. Diapause monarchs of both sexes responded to juvenile hormone with pron...

Endocrine regulation of posteclosion enlargement of the male and female reproductive glands in Monarch butterflies

The colleterial glands of female Monarch butterflies, and the accessory glands, tubular glands, and ejaculatory ducts of male Monarchs, exhibit considerable enlargement after eclosion in summer adults. Experiments using neck-ligatures and allatectomies, with or without injections of compounss with high juvenile hormone activity, show that the normal posteclosion hypertrophy of these organs is stimulated by juvenile hormone.

Regulation of oogenesis, female specific protein production, and male and female reproductive gland development by juvenile hormone in the butterfly,Nymphalis antiopa

SummaryThe role of the juvenile hormone (JH) in the regulation of oogenesis and the development of the male and female reproductive glands in the butterflyNymphalis antiopa was examined by means of classical endocrine methodology. The use of neck ligatures and allatectomies, with or without injections of compounds with high JH activity, demonstrated that JH is required for: 1) oogenesis and colleterial gland development in posteclosion adult females, and 2) tubular gland-ejaculatory duct and accessory gland enlargement in posteclosion adult males. Additionally, disc gel electrophoretic studies of hemolymph from males and females in several different physiological states, and of homogenates of mature oocytes indicated that JH is required for the normal presence in gravid female hemolymph of an apparent vitellogenin.

Hormonal regulation of hemolymph lipid concentration in the Monarch Butterfly, Danaus plexippus☆

Abstract Selective elevation of hemolymph lipid can be demonstrated in flying Monarch Butterflies. In addition, the low levels of hemolymph lipid characteristic of wild-caught postmigratory Monarchs remain low in winter conditions but are rapidly elevated when winter animals are placed in summer conditions. Abdominal, but not neck, ligatures prevent the elevation of hemolymph lipid characteristic of postmigratory animals placed at summer conditions. Injection of extracts of known cephalic neuroendocrine centers cause specific elevation of hemolymph lipid in both intact animals and isolated abdomens. Hormone-like dose-response and time-course curves and elevation of hemolymph diglycerides occur in response to injection of active extracts. Monarch head, brain, corpora cardiaca-corpora allata, thoracic nerve cord extracts, and Tenebrio head extracts all contain material acting to significantly elevate Monarch hemolymph lipids. By contrast, extracts of Monarch abdominal nerve cords, or Apis or Periplaneta heads, and synthetic crustacean red pigment concentrating hormone are without effect. The active factor in Monarch heads is sensitive to proteolytic enzymes, but resistant to heat and hydrogen peroxide.

Endocrine biology of the Painted Lady butterfly Vanessa cardui

Abstract Experiments dealing with the role of juvenile hormone, adipokinetic hormone and diuretic hormone in the Painted Lady butterfly Vanessa cardui are reported. The results demonstrate an important role of JH in the regulation of ovarian and colleterial gland development in females, and in the regulation of accessory gland, tubular gland and ejaculatory duct development in males. In addition, the presence of an adult reproductive diapause, characterized by decreased effective juvenile hormone haemolymph titres, is suggested. Evidence for the existence of both adipokinetic and diuretic hormones in the Painted Lady is also presented, as is data indicating that both hormones may be similar or identical to those previously described in Monarch butterflies. Owing to the above results, and the existence of an artificial diet suitable for mass rearing in the laboratory, the Painted Lady appears to be an excellent species for studies on adult lepidopteran neuroendocrinology.

The regulation of post-eclosion and post-feeding diuresis in the Monarch butterfly, Danaus plexippus

Abstract Both post-eclosion and post-feeding diuresis can be demonstrated in adult Monarch butterflies; and both these processes are significantly inhibited by neck-ligature. The post-eclosion response is restored in neck-ligatured animals by injection of whole head, brain, ventral nerve cord, and corpora cardiaca-corpora allata extracts, and the effect is dose dependent. The active substance appears to be a water soluble, heat stable, trypsin and protease sensitive, polypeptide, with a molecular weight estimated from gel filtration of approx. 3000, that is localized principally in the brain. The amount of active substance present in the head decreases during post-eclosion diuresis, when activity seems to be present in the haemolymph. However, diuretic activity can be demonstrated from heads obtained from Monarchs that are several days or weeks old. In the Monarch, post-eclosion diuresis appears to be under hormonal regulation. By contrast, extracts of whole heads and/or known endocrine organs do not significantly alter post-feeding diuresis in intact or neck-ligatured Monarchs. In addition, although diuresis in response to injections of large volumes of insect saline can be demonstrated in Monarchs, extracts of known endocrine organs do not affect the rate of post-injection diuresis in either neck-ligatured or intact animals. Such experiments, and others involving surgical interruption of the ventral nerve cord, indicate that the eclosion diuretic hormone does not play a major role in the regulation of post-feeding diuresis in this species.

EVIDENCE FOR AN ADIPOKINETIC FUNCTION OF THE RPCH ACTIVITY PRESENT IN THE DESERT LOCUST NEUROENDOCRINE SYSTEM

1. Red pigment concentrating hormone-like activity (RPCA) has been demonstrated and quantified in the head or cephalic neuroendocrine system of several insects. Schistocerca gregaria adults contained the highest levels of RPCA.2. RPCA was found in all post-embryonic life cycle stages of S. gregaria, and seems to be present in equal quantities in both males and females. Adult locusts contain significantly more RPCA than do immature animals.3. RPCA is concentrated in the locust CC glandular lobe hut is also present in the CC storage lobe, brain and hemolymph of both mature and immature animals. Significant variations in CC RPCA content have been demonstrated in both mature and immature stages.4. Synthetic red pigment concentrating hormone (RPCH) is adipokinetic in both intact and neck-ligatured S. gregaria adults and in intact immature animals. Doses of about 6 ng and 50 ng, respectively, result in minimal and maximal adipokinetic responses. RPCH selectively elevates hemolymph 1.2-diglycerides.5. RPCH in la...