0000000000011098
AUTHOR
Franz Romer
DNA Content and Synthesis in Several Tissues and Variation of Moulting Hormone-Level in Gryllus bimaculatus DEG (Ensifera, Insecta)
The mode of growth of several tissues in Gryllus bimaculatus was investigated during postembryonic development by cytophotometric methods. In contrast to the situation in holo- metabolous insects, the tissues growing by endomitosis reach only moderate levels of polyploidy. In this case the growth of tissues is achieved by mitotic divisions of small cells with subsequent polyploidization. The time courses of DNA synthesis were measured within the 3rd and, for comparison, the 8th larval instar by incorporation of labelled thymidine followed by autoradiography. Hemocytes, cells of the regeneration crypts of the midgut, gonads and nervous tissue showed a continuous incorporation rate; by contra…
Biosynthesis of ecdysones in isolated prothoracic glands and oenocytes of Tenebrio molitor in vitro.
Abstract Isolated prothoracic glands from Tenebrio larvae synthesize in vitro α-ecdysone, but not β-ecdysone from 4-14C-cholesterol. Isolated abdominal oenocytes from the larvae synthesize mainly β-ecdysone, but only little α-ecdysone. When prothoracic glands and oenocytes are cultured together, the α-ecdysone derived from the prothoracic glands is oxidized by the oenocytes to β-ecdysone. The newly synthesized hormones are not stored in the cells, but are secreted into the medium if sufficient amounts of non-labelled hormones are present. If no unlabelled hormones are added to the culture medium, the newly formed hormones are converted to a large extent into polar conjugates.
Arachnid oenocytes: ecdysone synthesis in the legs of harvestmen (Opilionidae).
Cells measuring up to 130 microns have been found in the proximal segments of the femora of all four pairs of walking legs in various species of harvestmen (Phalangium opilio, Leiobonum limbatum, Opilio parietinus, and Opilio ravennae). These cells exhibit all the fine-structural characteristics of insect oenocytes, in particular the conspicuous agranular endoplasmic reticulum. Radioimmunoassay after in vitro incubation of these cells has demonstrated the synthesis of alpha- and beta-ecdysone. These ecdysteroids have been found in the ovaries and tergites of the opisthosoma as well as in the oenocytes.
Ultrastructural changes of the oenocytes of Gryllus bimaculatus DEG (Saltatoria, Insecta) during the moulting cycle
1. The oenocytes of Gryllus bimaculatus are characterized by an abundant smooth-surfaced ER (ATER). In spite of the great cell size the plasma membrane never shows extensive infoldings during the moulting cycle. In addition to mitochondria there are very large numbers of microbodies containing peroxidase but apparently not uricase. Within the second part of the instar the microbodies lie along the clefts which run through the whole cell. 2. The following changes are observed in the course of a moulting cycle: Immediately after hatching the ATER is scarcely developed, some liposomes are located within areas of ATER disappearing some hours later. 20 hours after emergence glycogen deposits app…
Secretion and Metabolism of Ecdysteroids by Oenocyte-Fat Body Complexes (OEFC) in Adult Males of Gryllus bimaculatus DEG (Insecta)
Extracts of whole adult males of Gryllus bimaculatus show distinct maxima of free ecdysteroids on the 8th, 12th and 14th day after imaginal moult at a breeding temperature of 25 °C. Isolated OEFC of 11 days old males secrete in vitro free as well as conjugated ecdysteroids, although the latter predominate. The bulk of free ecdysteroids seem s to consist of E and 20 E according to their retention times in two HPLC systems. Apart from the polar ones, apolar m etabolites appear during incubation. By esterase the apolar metabolites are mostly split into polar ones, partly into 20 E and E. Further treatment of the polar metabolites with helicase leads again to E and 20 E. OEFC transform [3H]E pr…
In Silico Analysis of the Novel Variant Q375R in the Phenylalanine Hydroxylase Gene
Background: Phenylketonuria is an inborn metabolic disorder inherited in an autosomal recessive pattern. The detection of pathogenic variations improves the power of at-risk carrier and prenatal detection. We previously found Q375R a novel phenylalanine hydroxylase variation in phenylketonuria patients from the south-west of Iran. Objectives: Here, we aimed to evaluate the rate of the pathogenicity of this novel variant and three other intron variants (IVS9 + 32insA, IVS11 + 163delC, and IVS12 + 30C>T). Methods: The pathogenicity and some structural features of Q375R were analyzed using bioinformatics tools including SIFT, PolyPhen, Mutpred, MutationTaster, nSSNP Analyzer, SNP effect, 3DLig…
Cuticle: Formation, Moulting and Control
The relative rigidity of the arthropod exoskeleton makes it impossible for body size to increase continuously during the postembryonic development of these animals. Once they have hatched from the egg, they grow in steps, passing through a variable number of (larval) stages (Fig. 1 a). Apart from a few exceptions, there are between 3 and 10 such stages in the arachnids, 3–20 in the crustaceans, and 3–10 in the insects. In many cases a metamorphosis stage intervenes (some crustaceans; holometabolous insects) (Fig. 9b, c).
Nachweis von h�utungsaktiven Stoffen in isolierten Prothorakaldr�sen und Oenocyten beiBombyx mori w�hrend des 5. Larvenstadiums
The content of moulting hormones has been determined in homogenates of isolated prothoracic glands and oenocytes during the 5th instar of the silkworm,Bombyx mori by means of the Calliphora bioassay. Prothoracic glands show variable activity in the production of moulting hormones, reaching a maximum near the end of the larval period. Comparable activities, but at higher levels, could be demonstrated in oenocytes. Controls with doubled quantities of tissue produced in a proportionate reaction in the bioassay. Fat bodies were inactive. Prothoracic glands and oenocytes incubated together resulted in a slower pupation index than would be expected from the sum of single determinations of oenocyt…
Morphology and ultrastructure of the larval oenocytes of Tenebrio molitor L. (Insecta, Coleoptera) within the larval, pupal and adult period
1. Die larvalen Oenocyten von Tenebrio liegen den lateralen Tracheerlangsstammen in einem schmalen Bandchen auf. Sie vermehren ihre Zahl wahrend der postembryonalen Entwicklung nicht, wachsen also durch Endopolyploidie. In 8 Tage alten Imagines sind sic immer noch vorhanden; sie werden also im Zuge der Metamorphose nicht abgebaut. 2. In ihrer Ultrastruktur zeigen sie die fur Oenocyten typischen Merkmale: ein sehr kraftig ausgebildetes ATER, das zwischen den Tubuli nur ganz wenig Platz fur das Grundcytoplasma haft. Die Mitochondriendichte ist relativ hoch, spezialisierte Mitochondrien kommen nicht vor. Ribosomen treten hauptsachlich als freie Ribosomen auf, daneben auch mit dem ER verbunden …
Morphogenesis of mechanoreceptor and epidermal cells of crickets during the last instar, and its relation to molting-hormone level.
(1) The fine structure of the cercal campaniform sensilla and epidermal cells of Gryllus bimaculatus Deg. (Saltatoria, Gryllidae) was examined, and the ecdysteroid level was monitored throughout the last larval instar. (2) The epidermal cells show changes in shape, cytoplasmic inclusions and differentiation of the apical cell membrane, coupled to the phases of buildup and breakdown of the (cercus) cuticle. (3) The imaginal epicuticle of the epidermal cells begins to form later (by about approximately 6h) than that of the campaniform sensilla. (4) The campaniform sensilla were studied with respect to (a) the morphogenesis of the cuticular apparatus, (b) the inclusion of phenol oxidases in th…
Structure and function of prothoracic glands and oenocytes in embryos and last larval instars of Oncopeltus fasciatus Dallas (Insecta, Heteroptera).
1. Active prothoracic glands and oenocytes of last larval stage are both characteristized by well-developed smooth and rough endoplasmic reticulum (ER). Prothoracic glands also show plasma membrane infoldings, but not oenocytes which contain a large number of pleomorphic vesicles. 2. The fine structure of embryonic oenocytes corresponds after blastokinesis with that of active larval and adult cells. Thus, an activity in the late embryo can be assumed. Embryonic prothoracic glands reveal no signs of activity: smooth and rough ER are absent. The subcellular structure resembles that of organ anlagen, i.e. not yet fully differentiated tissue. Hormone synthesis is not likely. 3. Ecdysone titer w…
Degeneration of moulting glands in male crickets
The degeneration of the prothoracic glands of the male cricket, Gryllus bimaculatus, was analyzed by using an in vitro assay for ecdysteroid release from the moulting glands in last instar nymphs as well as in adult animals, and correlated with light and transmission electron microscopy. Apoptosis was examined by the TUNEL-reaction. The ability to synthesize ecdysteroids reached a peak at the 8th day of the last larval instar, identified as the moulting peak. After adult ecdysis it decreased to barely measurable values. Prothoracic gland degeneration was initiated at the time of the moulting peak, characterized by TUNEL positive reactions, nuclear and cytoplasmatic condensation, a striking …
Die Prothorakaldr�sen der Larve vonTenebrio molitor L. (Tenebrionidae, Coleoptera) und ihre Ver�nderungen w�hrend eines H�utungszyklus
1. Die Ecdysialdrusen der Larve vonTenebrio liegen in 2 Bandern entlang der dorsalen Tracheenaste und deren Verzweigungen im Prothorax. 2. Mit histochemischen Methoden konnten in den Drusenzellen Glykogen, Cholesterin und Lipidtropfchen nachgewiesen werden. Versuche mit tritiummarkiertem Cholesterin zeigten, das dieses mit den Lipidtropfchen in die Zellen der Prothorakaldrusen gelangt. 3. Mit Hilfe der Methylenblaufarbung wurde eine Innervation der Prothorakaldrusen nachgewiesen, die vom Unterschlund- und vom Prothoraxganglion ausgeht. Elektronenmikroskopisch konnten Neurosekretgranula in Axonen, die in die Basalmembran und z. T. durch die Drusenzellen selbst ziehen, nachgewiesen werden. 4.…