Isolated cell type corpora allata in adults of the loreyi leafworm,Leucania loreyi duponchel (Lepidoptera: Noctuidae)

The corpora allata in adult Loreyi leafworms Leucania loreyi (Lepidoptera: Noctuidae) exhibit sexual dimorphism. The male possesses right and left corpora allata of about the same size. Each gland is composed of a cluster of approximately 40 semi-transparent, spherical, isolated cells held together by fine tracheae and nerve fibers. The largest cell diameter found in male glands was 203 pm. In contrast, the female gland cells and clusters are much smaller. The largest dimensions of one whole female gland cluster were 452 μm in length and 280 μm in width. Using bilateral and unilateral larval allatectomy, we confirmed that the adult isolated cell type glands develop ontogenetically from larval capsular type glands. Ultrastructural study re- vealed many similarities between the subcellular structures of the isolated cell type glands of L. loreyi and the more common capsular gland reported by others. These similarities include very large numbers of mitochondria, abun- dant whorled smooth endoplasmic reticulum, irregularly shaped nuclei, Golgi bodies, and free ribosomes. Compared with the corpora allata of 3- to 9-day-old adults, the glands of 1-day-old adults possessed much less smooth endoplasmic reticulum. The gland cells in females usually have more neurosecretory nerve endings, less-abundant stacked smooth endoplasmic reticulum, and less- defined interdigitations than the gland cells in males. © 1995 Wiley-Liss, Inc.     

A new gland associated with the retrocerebral complex of the adult corn earworm, Helicoverpa zea

We report the discovery of a single-celled putative new gland associated with the retrocerebral complex in the adults of Helicoverpa zea. The gland was not observed in Manduca sexta and few other species of moths. The pair of glands, each 50.6+/-5.5 microm in diameter, is located on either side of the recurrent nerve. Each gland is connected on one end through a fine nerve to the nervus corporis cardiaci-3 (NCC-3) and at the opposite end to the corpora allata through a thin fiber. The gland is composed of a giant cell with a large nucleus. The cytoplasm has an abundance of mitochondria in addition to dense bodies, electron lucent spheres, concentric whorls of rough endoplasmic reticulum and few vacuoles. At this stage we have no idea as to the function of this new gland.     

Correlation between larval weights,endocrine gland activities and competence period during differentiation of workers and soldiers in Macrotermes michaelseni (Isoptera:Termitidae)

Correlations were established between corpora allata and prothoracic gland activities, changes in fresh weights and competence period for soldier formation in a higher termite species, Macrotermes michaelseni. There was a time-course differential increase in fresh weights observed in pairs of female third (final)-instar larvae of the same age previously adopted by a pair of female reproductives from incipient colonies. A bimodal distribution of these larvae according to weights was evident from the first day of the instar. Heavier larvae were associated with higher corpora allata and prothoracic gland volumes (activities), and differentiation into presoldiers, while lighter larvae had considerably less-active corpora allata and prothoracic glands and developed into workers. The peak in the activities of these glands in both cases marked the end of the competence period.The chain of events that may precede caste differentiation is discussed briefly and the significance of the findings outlined.     

Effect of endocrine glands on the unfixed total haemocyte counts of the bug Halys dentata

Changes in total haemocyte counts in relation to the endocrine glands have been studied in Halys dentata. Unfixed total haemocyte counts were taken after extirpation and implantation of three endocrine structures. It is concluded that haemocyte count decreases after the extirpation of the corpora allata in the early life span of adults, while an abrupt increase was noted after the 7th day. When both the corpora allata and corpora cardiaca are extirpated, the count was significantly decreased throughout the life span of adults. However, when only the corpora cardiaca were removed there was no significant variation up to the 7th day, but later on the count gradually decreased. The implantation of brain, corpora cardiaca and allata is followed by a significant rise in the haemocyte count throughout the life span. Total haemocyte count also fluctuated after the implantation of corpora allata and brain, separately. After implantation of corpora cardiaca of one-day-old adult insects there was no variation in the total haemocyte count while the corpora cardiaca of 6-day-old adults when implanted in one-day-old adults cause a significant rise in the total haemocyte count. Therefore, it is concluded that the corpora cardiaca influences the total haemocyte count after a critical period.     

Primer effect of queen pheromone on juvenile hormone biosynthesis in adult worker honey bees

Juvenile hormone synthesis in adult worker honey bees was measured by an in vitro corpora allata bioassay. Adult queenless workers exhibit higher rates of juvenile hormone biosynthesis than queenright workers. Hormone synthesis is not correlated with the volume of the glands. Extract of queen mandibular glands, applied to a dummy, reduces juvenile hormone biosynthesis in caged queenless workers to the level of queenright workers. The same result was obtained with synthetic (E)-9-oxo-2-decenoic acid, the principal component of the queen mandibular gland secretion. This pheromonal primer effect may function as a key regulating element in maintaining eusocial colony homeostasis. The presence of brood does not affect the hormone production of the corpora allata.Abbreviations BSA bovine serum albumin - CA Corpora allata - JH juvenile hormone - 9-ODA (E)-9-oxo-2-decnoic acid     

Developmental changes in the major inclusion bodies of polytene nuclei from larval tissues of the blowfly,Calliphora stygia

The major ribonucleoprotein inclusion bodies of the polytene nuclei from larval ventral nephrocytes, Malpighian tubules, pericardial cells, fat body and salivary glands of Calliphora stygia show characteristic developmental patterns at the light microscope level. Three morphologically and developmentally distinct classes of nuclear inclusions occur in these tissues. In fat body and salivary gland nuclei, morphological changes in the inclusion material can be correlated with the pattern of protein synthesis during the third larval instar, and with conspicuous changes in chromosome morphology. The appearance of cytologically diverse nuclear inclusions, in an ordered tissue-specific sequence, may thus reflect differential activation of the genome.     

The synthetic activity and glandular volume of the corpus allatum during ovarian maturation in the desert locust Schistocdrca gregaria.

We have compared, on an individual basis, the volume of the corpora allata with their ability to synthesize and release juvenile hormone (JH) using glands taken at daily intervals throughout the period of sexual maturation and the first two ovarian cycles in $\text{Schistocerca gregaria}$. A standard $\text{in vitro}$ radiochemical assay was used to measure the rates of both spontaneous JH biosynthesis from [methyl-¹⁴C]-methionine, and of JH biosynthesis stimulated by optimal concentrations of [C-2 ³H]-farnesenic acid. Computation of results showed that there are, during this period, changes of up to 250-fold in the rate of spontaneous JH biosynthesis per unit volume corpora allata. It is concluded that the volume of the corpora allata is of no value as an indicator of the spontaneous synthetic activity of the glands in this species, and that the overall rate of JH synthesis is regulated by mechanisms that do not involve large changes in the volume of the gland cells. However, in the presence of farnesenic acid, there is a corelation between stimulated JH synthesis and glandular volume, suggesting that the volume of the gland reflects the maximum activity of the final two stages in JH biosynthesis.     

Dosage of 5 S and ribosomal genes during oogenesis of Drosophila melanogaster

During growth, the Drosophila egg chamber increases its DNA content over a thousandfold, mainly by polyploidization of the nurse cell nuclei. We wanted to determine if 5 S and ribosomal genes are replicated to the same extent as the remaining DNA. Egg chambers were mass fractionated to represent different size classes and, therefore, different stages of oogenesis. Nucleic acids were extracted from each class of egg chambers, and after removal and quantitation of the RNA, the content of 5 S and ribosomal genes in the different DNA fractions was assayed by filter hybridization. Diploid DNA and DNA from polytene salivary gland cells served as references. It was concluded that: (1) Ribosomal genes become underreplicated as oogenesis proceeds, but to a much lower extent than in polytene chromosomes of salivary glands of the same organism. (2) By contrast, 5 S genes are equally replicated in egg chambers of all stages of oogenesis. (3) Notwithstanding the large increase in DNA content of egg chambers during oogenesis, the increase in total RNA content (mostly ribosomal RNA) is over 15 times as large.     

The effects of juvenile hormone, 20-hydroxyecdysone and precocene II on activity of corpora allata and the mode of negative-feedback regulation of these glands in the adult Colorado potato beetle

When the titre of juvenile hormone III in female Leptinotarsa decemlineata was elevated by the implantation of supernumerary corpora allata or by the injection of the hormone, the rate of endogenous hormone production by the host glands was significantly restrained, as determined by the short-term in vitro radiochemical assay. From denervation studies, it is suggested that during phases of elevated juvenile hormone titre, the corpus allatum activity is regulated via humoral as well as neural factors requiring intact nerve connections. Restrainment of gland activity appears to be mainly via the neural pathway. Isolated corpora allata were not influenced by 10^?5 M juvenile hormone III added to the incubation medium in vitro.Studies with farnesenic acid revealed that the final two enzymatic steps in the biosynthetic pathway of juvenile hormone are also diminished during prolonged neural inhibition of the corpora allata.20-Hydroxyecdysone and precocene II had no apparent effect on the corpus allatum activity of Leptinotarsa decemlineata.     

Histology of the hormone-producing glands in the damp-wood termite <Emphasis Type="Italic">Hodotermopsis sjostedti</Emphasis> (Isoptera,Termopsidae): A focus on soldier differentiation

Caste differentiation in termites depends on complex hormonal changes during postembryonic development. Juvenile hormone (JH) is a central player in this process. The present study examined histological changes in the main hormone-producing endocrine glands, the corpora allata and molt glands, in the Japanese dampwood termite Hodotermopsis sjostedti. We focused on the soldier caste differentiation pathway, which can be induced artificially using an analogue of JH. The corpora allata exhibited volumetric changes during soldier induction, reflecting variations in the quantity of cytoplasm. Corpora allata from alates and neotenics clearly showed differentiation accompanied by cell proliferation, preparing for the high-level JH production necessary for reproduction. However, the volume increase of corpora allata was not always correlated to high JH titers. In contrast, molt glands degenerated in the reproductive castes. The JH analogue induced hypertrophy of the molt glands, along with the formation of lacunae, possibly related to ecdysteroid production. The JH analogue effect, inducing soldier differentiation, was suggested to require both mimic of high JH titers and stimulation of the molt glands. Received 12 November 2007; revised 2 June 2008; accepted 14 July 2008.     

Structure-activity relationships in corpora allata of the cockroach Diploptera punctata: roles of mating and the ovary

Morphometric studies were made on corpora allata of the cockroach Diploptera punctata from animals in which increasing gland size is not coupled to hormone synthesis (ovariectomized mated females; last-instar larvae) and in which gland size is coupled to hormone synthesis (normal mated and virgin females; penultimate-instar larvae). Cell number, gland volume, and juvenile hormone synthesis were measured. From electron micrographs, nuclear, cytoplasmic, and extracellular volumes; and cell membrane area were calculated; and fine structure described. Low-activity glands of ovariectomized mated females resembled high-activity glands from mated females in high cell number, large overall and cytoplasmic volume, and low nuclear-cytoplasmic ratio; they differed in having organelles typical of low-activity glands, mitochondria with dense matrices and large whorls of smooth endoplasmic reticulum. Inactive lastinstar larval glands resembled mated ovariectomized, female glands in increased cell number and organelles characteristic of inactive glands; however, their nuclearcytoplasmic volume ratio was much higher. Penultimate cytoplasmic volume ratio was much higher. Penultimate larval glands with high activity per cell resembled active glands of normal mated females. Ovariectomy did not change morphometric parameters of virgin female glands; thus mating results in increase in size of adult female glands whereas the growing ovary is needed for changes in mitochondria and endoplasmic reticulum associated with high juvenile hormone synthesis.     

Improved conditions for culture of biosynthetically active cockroach corpora allata

Summary Currently, short-term culture of insect corpora allata is most often performed in TC199. We now show that L-15B, a medium widely used in arthropod tissue culture, is superior to TC199 for both short- and long-term culture of cockroach corpora allata. In 3-h and 48-h incubations, juvenile hormone biosynthesis by corpora allata from Diploptera punctata was significantly higher in L-15B than in TC199. In addition, in both media, corpora allata activity was significantly improved by flotation of glands at the medium surface. Characteristics of L-15B responsible for its superiority were examined by comparison of gland activities in several TC199 formulations that had been modified in different ways to be more similar to L-15B. Adjusting the osmotic pressure of TC199 (288 mOsm/l) to near that of L-15B (362 mOsm/l) and D. punctata hemolymph (360 mOsm/l) significantly improved gland activity during the second 12 h of a 36-h incubation. Increasing the concentrations of amino acids, sugars, and organic acids in TC199 to the same levels as in L-15B significantly improved gland activity during both the second and third 12-h intervals of a 36-h incubation. These results suggest that L-15B is superior to TC199 because L-15B is isoosmotic with D. punctata hemolymph and because L-15B, like cockroach hemolymph, contains a high level of organic constituents. It is therefore more appropriate to use L-15B than TC199 for short-term in vitro assays of juvenile hormone biosynthesis and for extended corpora allata culture.     

Characteristics of the endocrine system in Drosophila melanogaster 1 (2)gl mutants, differing in time of death]

A comparative study of the state of the endocrine system and one of the larval organs, the salivary gland, has been carried out in larvae homozygous for the 1(2)gl gene. They differ in time of death (death at the third larval instar--larval allele, and at the prepupal state--prepupal allele). It is shown that homozygotes for the larval and prepupal allele have underdeveloped prothoracal glands. Corpora allata in homozygotes for the larval allele does not differ from the norm. Corpora allata in homozygotes for the prepupal allele is decreased proportionally to the decrease of prothoracal glands. A decrease of gland size is due to a decrease of the volume of cell but not to their number; this decrease is accompanied by the decrease of their relative DNA content. Salivary glands in homozygotes are reduced and comprise 80% of the normal size in homozygotes for the prepupal allele and 50% for homozygotes for the larval allele. Polyteny level in the salivary gland nuclei is much decreased as compared with the normal level. DNA level is more reduced in larvae homozygous for the larval allele.     

Effects of ovariectomy and mating on the activity of the corpora allata in adult female Blattella germanica (L.) (Dictyoptera: Blattellidae)

In adult female cockroaches, the ovary greatly affects the synthesis of Juvenile Hormone (JH) by the corpora allata, and in females of some cockroach species, removal of the ovaries results in a permanent depression of JH synthesis. We report that the corpora allata in ovariectomised, adult virgins of the German cockroach, Blattella germanica (L.), increase and then decrease in activity, as they do in intact females. Moreover, the distal tubules in the left colleterial glands of ovariectomised females accumulate abundant protein, the production of which is regulated by JH. In both ovariectomised and sham‐operated females, the activity of the corpora allata more than tripled between days 1 and 4 of adulthood, during which the oöcytes of sham‐operated females grew considerably in length. The corpora allata of sham‐operated females produced even more JH on day 7, but very little on day 10, by which time all females had oviposited. The glands of ovariectomised females, by constrast, produced a similar amount of JH on day 7 as on day 4, but much less on day 10. Beginning on day 13, the activity of the corpora allata increased again in ovariectomised females, an increase that did not occur until day 22 in sham‐operated females. Mating of ovariectomised females on day 6 resulted in a significant increase in the activity of the corpora allata by day 10. We conclude that both the ovary and mating stimulate the synthesis of JH early in the reproductive cycle, but that neither is needed for the occurrence of a complete cycle of JH synthesis.     

Biological,radiochemical and physicochemical evidence for the low activity of disconnected corpora allata in locust

The rate of juvenile hormone biosynthesis by locust corpora allata after transection of the nervi corporis allati 1, was measured in vitro using both radiochemical assay and gas chromatography—mass spectroscopy analyses. Incubations in different culture media or in pure haemolymph result in a low rate of juvenile hormone biosynthesis by disconnected glands. In vivo studies using juvenile, chromatotropic and gonadotropic effects of the corpora allata confirm the low activity of the disconnected glands. Furthermore, animals with disconnected corpora allata appear to be more sensitive to corpora allata implantation than control hosts.     

Polytene chromosomes of Oxytricha: Biochemical and morphological changes during macronuclear development in a ciliated protozoan

After conjugation in the ciliated protozoan, Oxytricha, polytene chromosomes are formed during the development of a macronucleus from a micronucleus. Here we report a microscopic study of these chromosomes and an analysis of their DNA. The polytene chromosomes of Oxytricha bear a strong morphological resemblance to the polytene chromosomes of the Dipteran salivary gland. The nucleus of a developing macronuclear anlage contains 120±2 polytene chromosomes and each chromosome has an average of 81 bands; a total of about 10,000 bands per nucleus. At a later stage in development, the number of bands per chromosome is reduced by a factor of four, presumably due to fusion of adjacent bands. The polytene chromosomes then break up into their constituent bands, each of which is encased in a vesicle. There are about 2,700 vesicles per nucleus. — During the growth of polytene chromosomes, there is a change in the relative proportion of sequences in the DNA. The DNA from polytene nuclei has a buoyant density of 1.695 g/cc, significantly lighter than the density of the original micronuclear DNA (1.698 g/cc to 1.702 g/cc). We interpret this buoyant density change to be the result of differential replication of DNA sequences during polytene chromosome growth. A second change in DNA composition occurs after the polytene stage of development, shown by a shift in buoyant density to 1.701 g/cc in the DNA of the mature macronucleus. During this second process, the molecular weight of the DNA is reduced from greater than 50×10⁶ daltons to about 2×10⁶ daltons.This paper is No. VI in the series, DNA of Ciliated Protozoa.     

Feeding and activation of corpora allata in the cockroach Blattella germanica (L.) (Dictyoptera,Blattellidae)

Adult females of the cockroach Blattella germanica have clearly-defined feeding cycles related to oogenesis. In the first cycle, food ingestion precedes volumetric increase in the corpora allata, which in turn precedes juvenile hormone production, whereas starved females do not develop the corpora allata and produce very low amounts of juvenile hormone. When the second gonadotropic cycle is provoked by removing the ootheca, the first event observed is an increase in food consumption, followed by an increase in corpora allata volume and activity. However, this increase in corpora allata volume (and activity) does not occur if females are starved, thus indicating that the ootheca in the genital chamber inhibits primarily feeding, and indirectly corpora allata development and activity. Corpora allata volume in isolated heads from starved and decapitated females was able to increase to levels similar to fed controls, but this increase was abolished by allatostatin treatment. We suggest that a factor produced in the thoracico-abdominal compartment, which reaches the head mainly through a nervous pathway, is released during starvation and inhibits corpora allata development. This factor may stimulate allatostatin production or release, or may well be allatostatin itself.     

Histone synthesis in Rhynchosciara salivary glands. I. Site and timing of synthesis.

The site of histone synthesis was studied in polytene cells of the salivary glands of the Rhynchosciara americana (Diptera). It was found that, as is the case in non-polytene systems, these proteins are synthesized in the cytoplasm in a class of light polysomes which contain 3-4 ribosomes. This class of polyribosomes is most active at about 5 days before pupation when the nuclei are most active in DNA synthesis and the chromosomes of the gland show many open 'DNA puffs'.