Effect of α- and β-ecdysone on DNA synthesis inAeshna cyanea (Insecta,Odonata) midgut

Summary InAeshna cyanea larvae, - and -ecdysone stimulate DNA synthesis in the midgut regenerative cells. In last larval instar, the number of cells obtained after the imaginal epithelium genesis is greater after - than after -ecdysone supply. Such a result should be compared with the imaginal epithelium differentiation which occurs earlier after -ecdysone injection.     

Neuer Beitrag zur Determination der Imaginalscheiben beiDrosophila

Summary The temperature effective period for the formation of double antennæ and palpi in the gene-combinationsc ec ct; Dfd ^r-L ends with the second half of the third larval stage. The t.e.p. of the mutantsaristopedia andproboscipedia ends with puparium formation. Thus we have another proof that the imaginal discs ofDrosophila are not definitely determined in the last larval stage.     

Haemolymph ecdysteroids level following the injection of ecdysone or ecdysterone; its relation with tegument and midgut response inAeshna cyanea (Insecta,Odonata)

Summary The haemolymph ecdysteroid level after injection of ecdysone or ecdysterone inAeshna cyanea larvae has been determined by a radioimmunoassay method. The rate of excretion appears to be dependent on both the ecdysteroid injected and the time of injection. In case of ecdysone injection, the secretion of the epidermis cuticle and the differentiation of the imaginal midgut epithelium occur when the ecdysteroid level remains low for many days.     

Chromosome arrangement throughout mitosis and interphase inAllium sativum (Liliaceae)

Summary Allium sativum (garlic) root-tip chromosomes were subjected to a C-banding procedure. In addition to the nucleolar bands reported previously in this species, bands which are telomeric or close to the telomeres have been detected in some pairs. This has allowed us to analyze the arrangement of chromosomes during interphase.     

Magnesium und Calcium enthaltende Einschlusskörper in den Mitteldarmzellen von Aphiden

Summary Granules in the midgut cells ofMegoura viciae Buckt. are described and found to consist of magnesium-phosphate and -carbonate; calcium may also be present. These granules are absent only in new-born larvae, but appear soon after the first uptake of food and accumulate during the four larval stages, being particularly striking in adults. The granules also occur in 25 other species of aphids, indicating that this phenomenon may be characteristic of aphids.     

Tissue distribution of juvenile hormone hydrolytic activity inGalleria mellonella larvae

Summary Juvenile hormone (JH) hydrolytic activity was determined in different tissues of day-4 last instar larva ofGalleria mellonella. Midgut, gonad, imaginal wing discs and fat body contain higher JH hydrolytic activity than hemolymph, while silk gland and body wall have lower activity. JH esterase activity in imaginal wing discs exhibits a pattern of age-related changes different from that of the hemolymph.We acknowledge the support of this research by the National Institutes of Health (GM 22429) and the Johnson Wax Foundation. Address to which reprint requests may be sent.     

The effect of DDT on DNA replication in the larval salivary gland cells ofDrosophila melanogaster

Summary The inhibitory effect of DDT on the initial stage of the DNA replication process in polytene chromosomes of larval salivary gland cells ofDrosophila melanogaster was investigated and possible mechanisms for the inhibition are discussed.     

Predominant regulators of tubulin monomer–polymer partitioning and their implication for cell polarization

The microtubule-system organizes the cytoplasm during interphase and segregates condensed chromosomes during mitosis. Four unrelated conserved proteins, XMAP215/Dis1/TOGp, MCAK, MAP4 and Op18/stathmin, have all been implicated as predominant regulators of tubulin monomer–polymer partitioning in animal cells. However, while studies employing the Xenopus egg extract model system indicate that the partitioning is largely governed by the counteractive activities of XMAP215 and MCAK, studies of human cell lines indicate that MAP4 and Op18 are the predominant regulators of the interphase microtubule-array. Here, we review functional interplay of these proteins during interphase and mitosis in various cell model systems. We also review the evidence that MAP4 and Op18 have interphase-specific, counteractive and phosphorylation-inactivated activities that govern tubulin subunit partitioning in many mammalian cell types. Finally, we discuss evidence indicating that partitioning regulation by MAP4 and Op18 may be of significance to establish cell polarity.     

Polytäne Chromosomen im Bereiche der Prothoracal-dorsal-Imaginalscheibe vonDrosophila melanogaster

Summary Polytene chromosomes have been found in a cell complex associated with the humerus imaginal disc ofDrosophila melanogaster.

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Wir danken unserem Lehrer, Herrn Prof. Dr. E.Hadorn, herzlich für die Anregung zu dieser Arbeit und die kritische Durchsicht des Manuskripts. Zu Dank verpflichtet sind wir auch Fräulein M.Staub, die uns bei der Herstellung der mikroskopischen Präparate geholfen hat.     

Sporulation and δ-endotoxin synthesis by Bacillus thuringiensis

Bacillus thuringiensis is distinguished from the very closely related Bacillus cereus and Bacillus anthracis by the presence of several plasmid-encoded δ-endotoxin genes. These δ-endotoxins, synthesized as protoxins, are produced in large quantities during sporulation and are packaged into intracellular inclusions. Ingestion of the inclusions by insect larvae leads to protoxin solubilization and conversion to toxins each specific for one of several orders of insects. The toxins form cation-selective channels in the membrane of cells lining the larval midgut with subsequent lethality. In most cases, δ-endotoxin synthesis and sporulation are closely coupled. The latter process in B. thuringiensis is probably virtually identical to that in Bacillus subtilis with the additional use of mother cell sporulation forms of RNA polymerase for the synthesis of the δ-endotoxins. There are other more subtle plasmid-encoded functions or plasmid interactions related to regulating protoxin synthesis. Consideration of both plasmid and chromosomal genes is thus critical for defining this organism.     

Invertase activity in the gut of 6th instar larvae ofSpodoptera mauritia Boisd. (Noctuidae,Lepidoptera)

Summary Invertase activity has been studied in the fore-, mid- and hindgut of the 6th instar larva ofSpodoptera mauritia. The highest activity was in the midgut except during the early hours of the larval period when the foregut showed comparatively increased activity. The hindgut invertase activity may be from the voiding of enzyme along with the undigested food.Acknowledgments. The authors wish to thank the Department of Zoology, for providing the facilities for this work. The senior author gratefully acknowledges the junior research fellowship from the University of Calicut.     

Ontogenetische Änderungen im Gehalt an Isoxanthopterin bei verschiedenen Genotypen vonDrosophila melanogaster

Summary The content of isoxanthopterine in different developmental stages and different genotypes ofDrosophila melanogaster has been investigated. In male pupae of the red eyed wild type the isoxanthopterine reaches a high concentration which is maintained during the whole period of imaginal life. It could be shown that the mutantsw (white) andbw (brown) though they are unable to synthesize the red eye pigment do nonetheless accumulate considerable quantities of isoxanthopterine during metamorphosis. This isoxanthopterine, however, disappears gradually from the body ofw andbw during the first 3 days of imaginal life till nothing of it is left in adult flies. The transitory appearance of isoxanthopterine in the two mutants, sets new problems with regard to the pleiotropic effect of thew- andbw-loci in pigment synthesis.     

Possible target of Abelson virus phosphokinase in cell transformation

By fusing interphase cells to cells undergoing mitosis, the interphase chromosomes can be visualized. When analyzed in this way, chromosomes of normal mouse cells show characteristic undercondensed centromeric regions. We have found that the centromeric regions of chromosomes from Abelson virus-transformed cells are fully condensed. Abelson virus transforms mouse cells by introducing into them a virally encoded phosphokinase that is expressed constitutively. Thus, we propose that the condensation of centromeric chromatin is a result of overphosphorylation by the Abelson virus phosphokinase, and that the centromeric region is the relevant target of overphosphorylation in transformed cell growth.     

Effects of the adenylate cyclase activator forskolin and its inactive derivative 1,9-dideoxyforskolin on insect cytochrome P-450 dependent steroid hydroxylase activity

The adenylate cyclase activator forskolin and its pharmacologically inactive derivative 1,9-dideoxyforskolin were found to inhibit in a dose-dependent fashion the ecdysone 20-monooxygenase activity associated with wandering stage larvae ofDrosophila melanogaster and fat body and midgut from last instar larvae of the tobacco hornworm,Manduca sexta. The concentrations of these labdane diterpenes required to elicit a 50% inhibition of the cytochrome P-450 dependent steroid hydroxylase activity in the insect tissues ranged from approximately 5×10^–6 to 5×10^–4 M.     

Immunocytochemical reaction of a haemocyanin antibody in the midgut gland ofNautilus (Cephalopoda,Tetrabranchiata)

The branchial gland of the dibranchiate cephalopods is described as the site of haemocyanin synthesis. Because there is no equivalent to this organ in tetrabranchiate cephalopods the localization of haemocyanin synthesis remained unknown for a long time. In this study we could confirm the conclusions from prelimnary investigations concerning the copper content of the midgut gland ofNautilus, which gave the first indications for a possible localization of haemocyanin synthesis in this organ. We developed a polyclonal antibody againstNautilus haemocyanin, tested its specificity, and used it on ultra-thin sections of the tissue of the midgut gland. It could be shown that there is a clear imunogold precipitation only on the triangular basal cells in the terminal alveoli. All the other types of cell in this organ were free of any immunoreactivity. It can be supposed that the triangular basal cells in the terminal alveoli of the midgut gland are the sites of haemocyanin synthesis inNautilus.     

Ecdysteroid receptors in the neuroendocrine-endocrine axis of a moth

With a combination of thaw-mount autoradiography using a tritiated 20-hydroxyecdysone agonist, ponasterone A, and immunocytochemistry with a monoclonal antibody to 29 K-prothoracicotropic hormone, high affinity binding sites for ecdysteroids were identified in the tissues of the neuroendocrine-endocrine axis inManduca sexta larvae. At specific times during larval-pupal development in fifth stadium larvae, nuclear ecdysteroid binding sites were present in the cerebral prothoracicotropes, the corpora allata and prothoracic glands, the main axis for the regulation and production of ecdysteroids. A stage-specific appearance of ecdysteroid receptors also occurred in cells of fat body, midgut and Malpighian tubules, tissues which convert ecdysone into 20-hydroxyecdysone. Our data identify new target tissues for ecdysteroids and suggest that ecdysteroids could affect their own production at the genomic level via long and short feedback loops.     

Über die Entstehung von Mehrfachbildungen der Flügelimaginalscheibe bei Großschmetterlingen

Summary The latent potency of organ development in a normally functionless evagination on the upper border of the imaginal disc, causes double forms of the presumptive wingleaf of caterpillars in lepidoptera. Triple forms of the wing-leaf consist of one double form and one simple form of the original imaginal disc of the wing and one regenerate, orvice versa.     

Analysis of <Emphasis Type="Italic">Dictyostelium</Emphasis> TACC reveals differential interactions with CP224 and unusual dynamics of <Emphasis Type="Italic">Dictyostelium</Emphasis> microtubules

We have localized TACC to the microtubule-nucleating centrosomal corona and to microtubule plus ends. Using RNAi we proved that Dictyostelium TACC promotes microtubule growth during interphase and mitosis. For the first time we show in vivo that both TACC and XMAP215 family proteins can be differentially localized to microtubule plus ends during interphase and mitosis and that TACC is mainly required for recruitment of an XMAP215-family protein to interphase microtubule plus ends but not for recruitment to centrosomes and kinetochores. Moreover, we have now a marker to study dynamics and behavior of microtubule plus ends in living Dictyostelium cells. In a combination of live cell imaging of microtubule plus ends and fluorescence recovery after photobleaching (FRAP) experiments of GFP-α-tubulin cells we show that Dictyostelium microtubules are dynamic only in the cell periphery, while they remain stable at the centrosome, which also appears to harbor a dynamic pool of tubulin dimers.     

Synthesis of a ubiquitously present new HSP60 family protein is enhanced by heat shock only in the Malpighian tubules ofDrosophila

A homologue of the chaperonin protein of the HSP60 family has not been shown so far inDrosophila. Using an antibody specific to HSP60 family protein in Western blotting and immunocytochemistry, we showed that a 64-kDa polypeptide, homologous to the HSP60, is constitutively present in all tissues ofDrosophila melanogaster throughout the life cycle from the freshly laid egg to all embryonic, larval and adult stages. A 64-kDa polypeptide reacting with the same antibody in Western blots is present in all species ofDrosophila examined. Using Western blotting in conjunction with³⁵S-methionine labeling of newly synthesized proteins and immuno-precipitation of the labeled proteins with HSP60-specific antibody, it was shown that synthesis of the 64-kDa homologue of HSP60 is appreciably increased by heat shock only in the Malpighian tubules, which are already known to lack the common HSPs.     

Absorption of glycine,L-alanine and L-phenylalanine in the midgut of the larvae ofBombyx mori

Summary A net absorption of glycine, L-alanine and L-phenylalanine occurs across the isolated midgut of the larvae ofBombyx mori. Although glycine and L-phenylalanine are not metabolized, L-alanine is converted by the midgut and has a metabolic effect on the transepithelial electrical potential difference of the tissue.Acknowledgments. We are very much indebted to Prof. V. Capraro for helpful advice and criticism. We are also grateful to Prof. G. Reali for his interest and support of this research.