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Biomedical subjects

H Oberlander

Publications and source records attributed to H Oberlander.

At least 19 recordsLinked to original sources
PubMed2000

Rhythmic autocrine activity in cultured insect epidermal cells.

It is now well established that ecdysteroids can be produced in insects in the absence of prothoracic glands. In this respect, it has been shown that cells in culture can produce ecdysteroids. Our aims were: (1) to determine whether ecdysteroid target cells of epidermal origin could also be the source of ecdysteroids; (2) to monitor more accurately the kinetics of ecdysteroid production; and (3) to check for possible relationships between this synthetic activity and dynamics of cell division. An insect cell line (IAL-PID2) established from imaginal discs of the Indian meal moth, Plodia interpunctella, with wild-type sensitivity to ecdysteroids was used in our study. Our results showed that the Plodia cell line exhibited autocrine activity. When division of IAL-PID2 cells was synchronized, a rhythmic production of ecdysteroids was observed. However, further experiments indicated that this rhythmicity could be cell autonomous. This led us to anticipate the existence of two cell subpopulations that would be able to produce ecdysteroids rhythmically, a minor one that would be cell cycle serum-independent population, and a major population that would need serum growth factors to proliferate and produce ecdysteroids. Qualitative study of the ecdysteroid content of the media clearly showed that ecdysone was the major immunoreactive product. Taken together, our findings clearly show that an insect cell line of epidermal origin is capable of rhythmic autocrine production of ecdysteroids. These results support the hypothesis that alternate sites for ecdysteroid production in vivo may exist and could play a role in local regulation of development. We now plan to determine the cellular basis of this rhythmic autocrine activity and to confirm the existence of growth factor-autonomous cells in the culture as well as the potent role played by ecdysteroids in the cross-talk between various cell subpopulations.

Animals↗
PubMed2000

Juvenile hormone and juvenile hormone mimics inhibit proliferation in a lepidopteran imaginal disc cell line.

The action of juvenile hormone (JH) and JH mimics have been examined in vitro by utilizing the imaginal disc-derived cell line, IAL-PID2. We have discovered that the cell line was responsive to JH and a variety of JH mimics. The most consistent response obtained in our studies was inhibition of cell proliferation, in the absence of 20-hydroxyecdysone (20E), which characteristically reduces cell proliferation in its own right in this cell line. JH-I, JH-III, methoprene, fenoxycarb, and farnesol significantly inhibited cell proliferation after 3 days of exposure of the cells in vitro to each of the compounds. Linoleic acid controls had no effect on proliferation in the cultures. The cell proliferation assay demonstrates the JH responsiveness of this cell line, but the concentrations of JH required were high compared to the concentrations of 20E needed for inhibition of proliferation in these cells.

Journal Article↗
PubMed1997

Activity of insulin growth factors and shrimp neurosecretory organ extracts on a lepidopteran cell line.

Ecdysteroids, or molting hormones, have been proven to be key differentiation regulators for epidermal cells in the postembryonic development of arthropods. Regulators of cell proliferation, however, remain largely unknown. To date, no diffusible insect peptidic growth factors have been characterized. Molecules structurally related to insulin have been discovered in insects, as in other eucaryotes. We developed in vitro tests for the preliminary characterization of potential growth factors in arthropods by adapting the procedures designed to detect such factors in vertebrates to an insect cell line (IAL-PID2) established from imaginal discs of the Indian meal moth. We verified the ability of these tests to measure the proliferation of IAL-PID2 cells. We tested mammalian insulin and insulin-like growth factors (IGF-I, IGF-II). Following an arrest of cell proliferation by serum deprivation, IGF-I and IGF-II caused partial resumption of the cell cycle, evidenced by DNA synthesis. In contrast, the addition of 20-hydroxyecdysone arrested the proliferation of the IAL-PID2 cells. The cell line was then used in a test for functional characterization of potential growth factors originating from the penaeid shrimp, Penaeus vannamei. Crude extracts of neurosecretory and nervous tissues, eyestalks, and ventral neural chain compensated for serum deprivation and stimulated completion of mitosis. Arch.

Animals↗
PubMed1995

Multicellular-vesicle-promoting polypeptide from Trichoplusia ni: tissue distribution and N-terminal sequence.

An N-terminal amino acid sequence of a 16.9 kDa hemolymph polypeptide, "Vesicle Promoting Factor" (VPF) from Trichoplusia ni, revealed a high sequence homology (70%) with Manduca sexta apolipophorin-III. A polyclonal antibody developed against VPF, however, was not immunoreactive with either purified M. sexta or T. ni apolipophorin-III. Immunoblots of tissue homogenates of T. ni indicated that VPF was present in imaginal wing discs, central nervous system (CNS), silk glands, midgut and hemocytes from fifth instar larvae, and also in the IAL-TND1 cell line which can grow as either fluid-filled multicellular vesicles or multicellular aggregates. VPF was also detected immunologically in the hemolymph of adults of T. ni, and in hemolymph of adults and larvae of Galleria mellonella and Heliothis virescens. Testes, midgut, hemocytes, and wing discs, but not Malpighian tubules, of T. ni released VPF into tissue culture medium during a 3 h incubation period.

Amino Acid Sequence↗
PubMed1994

Factors that influence the development of cultured neurons from the brain of the moth Manduca sexta.

During metamorphic adult development, neurons and glial cells in the developing olfactory (antennal) lobes of the moth undergo characteristic and extensive changes in shape. These changes depend on an interplay among these two cell types and ingrowing sensory axons. All of the direct cellular interactions occur against a background of changing steroid hormone titers. Antennal-lobe (AL) neurons dissociated from stage-5 (of 18 stages) metamorphosing animals survive at least 3 wk in primary cell culture. We describe here the morphological influences on AL neurons of (1) exposure to the steroid hormone 20-hydroxyecdysone, (2) exposure to sensory axons, and (3) interactions among the AL neurons. Cultured AL neurons respond only weakly, if at all, to 20-hydroxyecdysone. They do, however, show greater total outgrowth and branching when they had been exposed in vivo to sensory axons. Because there is no direct contact between some of the neuronal types and the sensory axons at the time of dissociation, the increase in outgrowth must have been mediated via a diffusible factor(s). When AL cells (neurons and glia) are plated at high density in low volumes of medium, or when the cells are plated at low density but in the presence of medium conditioned by high-density cultures, neurite outgrowth and cell survival are increased. Nerve growth factor (NGF), epidermal growth factor (EGF), fibroblast growth factor-basic (bFGF), transforming growth factor-beta (TGF beta) and insulin-like growth factor (ILGF) had no obvious effect on neuronal morphology and thus are unlikely to underlie these effects. Our results suggest that the mature shape of AL neurons depends on developmental interactions among a number of diffusible factors.

Animals↗
PubMed1994

Roles for insulin and ecdysteroids in differentiation of an insect cell line of epidermal origin.

During postembryonic development of insects, molting cycles affect epidermal cells with alternate periods of proliferation and differentiation. Cells of the cell line established from imaginal discs of the Indian meal moth (IAL-PID2) differentiate under the action of the molting hormone, 20-hydroxyecdysone, in a manner that is meaningful in terms of the development of the tissue from which they were derived. In particular, the hormone caused an accumulation of the cells in the G2 phase of their cycle and induced the formation of epithelial-like aggregates and the synthesis of specific proteoglycans. Recent discovery of members of the insulin superfamily in insects and the role of growth factors played by this family of molecules in vertebrates led us to check for their potential effects on IAL-PID2 cell cycle regulation. On the one hand, our results showed that insulin was involved in partial resumption of the cell cycle after an arrest caused by serum deprivation, but that other growth factors present in fetal calf serum were needed for full completion of mitosis. On the other hand, the cytostatic effect of 20-hydroxyecdysone was reversible, and, prior exposure of the cells to the hormone allowed the cells to complete one cell cycle in serum-free medium. These results suggest that the production of autocrine growth factors induced by ecdysteroids could circumvent the absence of serum. This cell culture model provides potential for further study of interactions between ecdysteroids and growth factor homologs during differentiation of insect epidermal cells.

Animals↗
PubMed1994

Embryonic development of an endoparasitoid, Microplitis croceipes (Hymenoptera: Braconidae) in cell line-conditioned media.

Embryos of the parasitoid Microplitis croceipes develop from pregerm band stage to first larval instar in cell culture medium conditioned by a cell line (IPLB-LdFB) derived from fat body from an atypical host Lymantria dispar. However, the percentage of eggs that develop normally to the first larval instar stage is significantly less than for those maintained in IPL-52B medium conditioned with host fat body tissue. Therefore, we examined the capacity of five insect cell lines to promote growth and development of pregerm band eggs in five media, IPL-52B, TC-199, TC-100, Grace's, and ExCell 400. The developmental response of M. croceipes was dependent both on the cell line and the cell culture medium used. TC-100, TC-199, and Grace's media promoted development to the germ band stage without the need for conditioning with host tissue. IPL-52B supported development to the germ band stage when a defined lipid concentrate was added. In IPL-52B medium, the IPLB-LdFB cell line promoted a significantly higher number of eggs developing to germ band relative to the other cell lines; however, none of the cell line-conditioned IPL-52B medium significantly stimulated egg hatch relative to the control medium. None of the cell line-conditioned Grace's media had a significant effect on eggs attaining germ band stage compared with the Grace's control medium. However, Grace's medium conditioned with the IAL-TND1 and IPLB-LdFB cell lines promoted development beyond germ band, resulting in a significantly higher percentage of hatching eggs than the Grace's control medium.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Ecdysteroid-stimulated synthesis and secretion of an N-acetyl-D-glucosamine-rich glycopeptide in a lepidopteran cell line derived from imaginal discs.

Hormone-regulated processing of N-acetyl-D-glucosamine was studied in an insect cell line derived from imaginal wing discs of the Indian meal moth, Plodia interpunctella (Hübner). The cell line, IAL-PID2, responded to treatment with 20-hydroxyecdysone with increased incorporation of GlcNAc into glycoproteins. Cycloheximide and tunicamycin counteracted the action of the hormone. In particular, treatment with 20-hydroxyecdysone resulted in the secretion of a 5,000 dalton N-acetyl-D-glucosamine-rich glycopeptide by the IAL-PID2 cells. Accumulation of this peptide was prevented by the use of teflubenzuron, a potent chitin synthesis inhibitor. A glycopeptide of similar molecular weight was observed in imaginal discs of P. interpunctella treated with 20-hydroxyecdysone in vitro, under conditions that induce chitin synthesis. Although the function of the 5,000 dalton glycopeptide is not known, we believe that the PID2 cell line is a promising model for molecular analysis of ecdysteroid-regulated processing of aminosugars by epidermal cells during insect development.

Acetylglucosamine↗
PubMed1991

Stimulation of embryonic development in Microplitis croceipes (Braconidae) in cell culture media preconditioned with a fat body cell line derived from a nonpermissive host, gypsy moth, Lymantria dispar.

A cell culture medium, IPL-52B, was preconditioned with host fat body and two insect cell lines to determine if they would support embryonic development of Microplitis croceipes in vitro. The medium was preconditioned with the cell line IPL-LdFB, derived from fat body of the gypsy moth, Lymantria dispar, cell line IAL-TND1, derived from imaginal discs of the cabbage looper, Trichoplusia ni, and whole fat body tissue from host Helicoverpa zea. A second cell culture medium, Excell 400, was preconditioned with only the cell line, IPL-LdFB. Pregerm band eggs were dissected from third instar host larvae and incubated in the conditioned medium for 20 h. Newly laid parasitoid eggs did not develop in unconditioned IPL-52B, but did develop to germ band stage in unconditioned Excell 400. The IPL-52B medium conditioned with both cell lines induced germ band formation, but only the L. dispar cell line (IPL-LdFB) promoted significant development to eclosion comparable to host far body tissue. Excell 400 medium preconditioned with the cell line, IPL-LdFB also supported development to eclosion.

Animals↗
PubMed1991

Growth factors in invertebrate in vitro culture.

An increasing number of polypeptide growth factors have been identified that have proven essential in the development of defined cell culture media for mammalian cell culture. The development of defined mammalian cell culture media, in turn, has provided an environment for studying cell lines in an experimentally manageable unit for studying the action of cellular regulators and genes that determine the properties of cells. Evidence that vertebrate growth factors may be present in insects is based on DNA sequences that encode epidermal growth factor and transforming growth factor-beta. However, research on the influence of commercially available vertebrate growth factors is very limited. Although the majority of insect growth-promoting substances studied were isolated directly from insect hemolymph, few of these have been purified to the extent that they could be tested in insect cell, tissue, and endoparasite cultures. Research is needed in both of these areas to aid in developing defined insect culture systems, and to understand better the regulation of postembryonic growth and development in insects.

Animals↗
PubMed1989

Neural regulation of sex pheromone biosynthesis in Heliothis moths.

Pheromone biosynthesis in females of Heliothis zea is regulated endogenously by a neuropeptide produced in the subesophageal ganglion. We have found that the ventral nerve cord must be intact for normal induction of pheromone biosynthesis and that pheromonotropic activity is associated with extracts of the abdominal nerve cord, but only during the period when pheromone is produced. We did not find evidence of pheromonotropic activity in hemolymph obtained from females that were producing pheromone. Extracts of the brain-subesophageal ganglion complex, which contain pheromone biosynthesis activating neuropeptide (PBAN), induced pheromone biosynthesis when applied to the terminal abdominal ganglion only if nerves from this ganglion to the pheromone gland were intact. Brain-subesophageal ganglion extracts did not induce biosynthesis when applied directly to the pheromone glands in vitro. From our results, we conclude that the target site of PBAN is not the pheromone gland but the terminal abdominal ganglion, and we hypothesize that the abdominal nerve cord transports PBAN to the terminal abdominal ganglion.

Journal Article↗
PubMed1982

Establishment of a cell line from lepidopteran wing imaginal discs: Induction of newly synthesized proteins by 20-hydroxyecdysone.

A cell line has been developed from the imaginal wing discs of the lepidopteran insect Trichoplusia ni (Hübner). The cells grow in suspension as fluid-filled, multicellular vesicles. The cell line has been designated IAL-TND1. Two-dimensional electrophoresis (isoelectric focusing and sodium dodecyl sulfate/polyacrylamide gels) of [(35)S]methionine-labeled proteins revealed similar patterns for IAL-TND1 cells and whole T. ni wing imaginal discs. Additionally, exposure to the insect steroid hormone 20-hydroxyecdysone stimulated the synthesis of the same new proteins in both whole wing discs and IAL-TND1 cell vesicles.

Journal Article↗
PubMed1978

Protein synthesis in imaginal disks of Plodia interpunctella during development in vivo and in vitro.

Wing imaginal disks were dissected from larvae of Plodia interpunctella (Hübner) at various stages during the larval-pupal transformation. The wing-disk proteins separated by electrophoresis and scanned with a densitometer changed quantitatively but not qualitatively during development in vivo. Treatment of wing disks in vitro with beta-ecdysone resulted in a 2-fold increase in synthesis of proteins after only 2 hr incubation. The maximum rate of protein synthesis was reached 16 hr after treatment with hormone. The pattern of proteins separated by electrophoresis of wing disks that were incubated in vitro with beta-ecdysone did not change qualitatively. The major features of protein synthesis during wing-disk development in vivo were similar to those observed during beta-ecdysone-induced development in vitro.

Culture Techniques↗
PubMed1976

Hormonal control of growth and differentiation of insect tissues cultured in vitro.

This paper reviews the effects of insect hormones on lepidopteran imaginal discs cultured in vitro. Beta-ecdysone showed that RNA and protein synthesis was required for evagination and cuticle deposition. In particular, studies with actinomycin D and cycloheximide (at nontoxic levels) showed that RNA and protein synthesis during the ecdysone-dependent period was essential for subsequent development. These findings support the hypothesis that stimulation of macromolecular synthesis is fundamental to the action of ecdysone on imaginal discs. The influence of beta-ecdysone on chitin synthesis was also examined. Beta-ecdysone stimulated uptake and incorporation of tritiated-glucosamine by cultured P.interpunctella wing discs. Addition of hexosamines to the culture medium had no influence on ecdysone-induced cuticle deposition, but inhibition of glucose-uptake by cytochalasin B prevented the formation of cuticle. The action of ecdysone on particular enzymes in the chitin pathway remains to be elucidated.timulated both evatination and cuticle deposition of wing discs of Plodia interpunctella(Hubner). However, evagination required a shorter exposure to ecdysone than did cuticle deposition. Cuticle deposition was obtained under the following conditions: (a) a 24-hour pulse of beta-ecdysone (0.5-5.0 mug/ml); (b) continuous treatment with 0.2 mug/ml beta-ecdysone; or (c) continuous treatment with 0.5 to 50.0 mug/ml beta-ecdysone in medium conditioned with larval fat body...

Acetylglucosamine↗