Juvenile hormone increases ouabain-binding capacity of microsomal preparations from vitellogenic follicle cells

1983 ◽  
Vol 61 (7) ◽  
pp. 826-831 ◽  
Author(s):  
T. T. Ilenchuk ◽  
K. G. Davey
Keyword(s):  
Juvenile Hormone ◽  
Binding Capacity ◽  
Follicle Cell ◽  
Follicle Cells ◽  
Follicular Epithelium ◽  
Curvilinear Relationship ◽  
Scatchard Analysis ◽  
Ouabain Binding ◽  
Binding Characteristics ◽  
Brain Microsomes

A comparison has been made of the effects of juvenile hormone (JH) on the binding characteristics for ouabain of microsomes prepared from brain and from cells of the follicular epithelium surrounding previtellogenic or vitellogenic oocytes in Rhodnius. JH has no effect on the binding of ouabain to brain microsomes and decreases the Kd, but does not alter the Bmax for previtellogenic follicle cells. For vitellogenic follicle cells, Scatchard analysis reveals a curvilinear relationship, which is interpreted as indicating that a new population of JH-sensitive ouabain-binding sites develops as the follicle cell enters vitellogenesis. These results are related to earlier data obtained on the effect of JH on ATPase activity, volume changes in isolated follicle cells, and the development of spaces between the cells of the follicular epithelium.

Hymenolepis diminuta-induced fecundity reduction may be caused by changes in hormone binding to Tenebrio molitor ovaries

Parasitology ◽  
1995 ◽  
Vol 110 (5) ◽  
pp. 565-571 ◽  
Author(s):  
T. J. Webb ◽  
H. Hurd
Keyword(s):  
Juvenile Hormone ◽  
Binding Sites ◽  
Post Infection ◽  
Protein A ◽  
Follicle Cell ◽  
Tenebrio Molitor ◽  
Hymenolepis Diminuta ◽  
Follicle Cells ◽  
Scatchard Analysis ◽  
Hormone Binding

SUMMARYAspects of vitellogenesis, known to be controlled by juvenile hormone, are adversely affected by Hymenolepis diminuta infection of Tenebrio molitor, in spite of circulating titres of the hormone remaining unchanged. It has therefore been proposed that juvenile hormone binding is disrupted at the tissue site level. Juvenile hormone III binding sites were located in the nuclear, microsomal and post-microsomal supernatant fractions of the follicle cells of Tenebrio molitor. When JH-III binding was quantified for both control and Hymenolepis diminuta-infected beetles, binding in the nucleus and cytosol were found to be largely unaffected. However, microsomal binding was severely disrupted; on days 3 and 6 post-infection, binding was greatly diminished, on day 9 post-infection, binding was slightly reduced and, by day 15, binding was ‘restored’ to that of control insects. Using follicle cell microsomes at day 3 post-infection, previous Scatchard analysis revealed the presence of at least two JH-III binding sites. The first is of higher affinity, Kd = 5·3 x 10·5 x 10−11 mol/mg protein and the second of lower affinity Kd = 7·7 x 10−7 M, Bmax = 9·75 x 10−11 mol/mg protein. A comparison with microsomal binding parameters of follicle cells from non-infected Tenebrio indicated that although the Bmax values were unchanged, the Kd value of the higher affinity site was increased by approximately 5-fold. These data are indicative of a parasite-induced competitive binding inhibitor.

Two actions of juvenile hormone on the follicle cells of Rhodnius prolixus Stål

1975 ◽  
Vol 53 (8) ◽  
pp. 1187-1188 ◽  
Author(s):  
Randa Abu-Hakima ◽  
K. G. Davey
Keyword(s):  
Juvenile Hormone ◽  
Developmental Stages ◽  
Normal Animal ◽  
Rhodnius Prolixus ◽  
Follicle Cells ◽  
Follicular Epithelium ◽  
Intercellular Spaces

The follicular epithelium of vitellogenic oocytes from allatectomized females of Rhodnius fails to develop large intercellular spaces when exposed to juvenile hormone (JH) in vitro. This suggests that in the normal animal, the follicle cells require JH at two developmental stages. Differentiation of the cells in the presence of JH represents one requirement, and only those cells which have undergone this initial priming are fully competent to exhibit the second response, the development of intercellular spaces.

Patterning of the follicle cell epithelium along the anterior-posterior axis during Drosophila oogenesis

Development ◽  
1998 ◽  
Vol 125 (15) ◽  
pp. 2837-2846 ◽  
Author(s):  
A. Gonzalez-Reyes ◽  
D. St Johnston
Keyword(s):  
Follicle Cell ◽  
Cell Types ◽  
Follicle Cells ◽  
Follicular Epithelium ◽  
Axis Formation ◽  
Main Body ◽  
Drosophila Oogenesis ◽  
Egfr Mutant ◽  
Anterior Posterior ◽  
Anterior Posterior Axis

Gurken signals from the oocyte to the adjacent follicle cells twice during Drosophila oogenesis; first to induce posterior fate, thereby polarising the anterior-posterior axis of the future embryo and then to induce dorsal fate and polarise the dorsal-ventral axis. Here we show that Gurken induces two different follicle cell fates because the follicle cells at the termini of the egg chamber differ in their competence to respond to Gurken from the main-body follicle cells in between. By removing the putative Gurken receptor, Egfr, in clones of cells, we show that Gurken signals directly to induce posterior fate in about 200 cells, defining a terminal competence domain that extends 10–11 cell diameters from the pole. Furthermore, small clones of Egfr mutant cells at the posterior interpret their position with respect to the pole and differentiate as the appropriate anterior cell type. Thus, the two terminal follicle cell populations contain a symmetric prepattern that is independent of Gurken signalling. These results suggest a three-step model for the anterior-posterior patterning of the follicular epithelium that subdivides this axis into at least five distinct cell types. Finally, we show that Notch plays a role in both the specification and patterning of the terminal follicle cells, providing a possible explanation for the defect in anterior-posterior axis formation caused by Notch and Delta mutants.

Downregulation of hepatocyte P2-purinoceptor binding capacity after trauma-hemorrhage/resuscitation

1994 ◽  
Vol 266 (6) ◽  
pp. R1804-R1809
Author(s):  
M. S. Mahmoud ◽  
P. Wang ◽  
S. R. Hootman ◽  
S. S. Reich ◽  
I. H. Chaudry
Keyword(s):  
Dissociation Constants ◽  
Binding Capacity ◽  
Isolated Hepatocytes ◽  
Scatchard Analysis ◽  
Midline Laparotomy ◽  
Binding Characteristics ◽  
Shed Blood ◽  
P2 Purinoceptors ◽  
Altered Glucose ◽  
Affinity Receptor

Although P2-purinoceptors play an important role in the regulation of liver metabolism under normal conditions, it is not known if trauma-hemorrhage and resuscitation have any effects on such receptors. To study this, we performed a 5-cm midline laparotomy (i.e., trauma induced) on rats and then bled them to and maintained them at a mean arterial pressure of 40 mmHg until 40% of maximum bleedout volume was returned in the form of Ringer lactate (RL). The animals were then resuscitated with 3x the volume of shed blood with RL over 45 min followed by 2x RL over 95 min. Hepatocytes were isolated at the time of maximum bleedout or at 0, 4, 17, and 27 h after the completion of crystalloid resuscitation. P2-purinoceptor binding characteristics were determined in the isolated hepatocytes by using [alpha-35S]ATP. Scatchard analysis revealed high- and low-affinity components of P2-purinoceptors in hepatocytes from sham-operated as well as hemorrhaged and resuscitated animals. The maximum binding capacity (Bmax) of the high-affinity receptor component decreased at the time of maximum bleedout and at 4, 17, and 27 h after resuscitation. In addition to this, the Bmax of low-affinity receptor components also decreased at 4-27 h after resuscitation. In contrast, the dissociation constants of both receptor components were not altered. Because hemorrhagic shock produces abnormalities in glucose metabolism, the downregulation of hepatocyte P2-purinoceptor Bmax may be responsible for the altered glucose homeostasis under such conditions.

ATP-MgCl2 treatment after trauma-hemorrhage/resuscitation increases hepatocyte P2-purinoceptor binding capacity

1994 ◽  
Vol 266 (6) ◽  
pp. R1810-R1815
Author(s):  
M. S. Mahmoud ◽  
P. Wang ◽  
S. R. Hootman ◽  
S. S. Reich ◽  
I. H. Chaudry
Keyword(s):  
Binding Capacity ◽  
Scatchard Analysis ◽  
Binding Characteristics ◽  
Beneficial Effects ◽  
High Affinity ◽  
Receptor Component ◽  
Receptor Dynamics ◽  
Maximum Binding Capacity ◽  
High Affinity Receptor ◽  
Affinity Receptor

Although our studies indicate that P2-purinoceptor binding capacity decreases after hemorrhage and resuscitation, it is not known whether ATP-MgCl2 administration after hemorrhage has any beneficial effects on the receptor dynamics. To study this, we performed laparotomy (i.e., trauma induced) on rats and bled them to and maintained them at a mean arterial pressure of 40 mmHg until 40% of maximum bleedout volume was returned in the form of Ringer lactate (RL). The animals were then resuscitated with 3 times the volume of maximum bleedout with RL over 45 min followed by 2 times RL along with ATP-MgCl2 (50 mumol/kg body wt) over 95 min. Hepatocytes were isolated at 4, 17, and 27 h after resuscitation. P2-purinoceptor binding characteristics were determined by using [alpha-35S]ATP. Scatchard analysis revealed high-affinity and low-affinity receptor components in the hepatocytes isolated from sham-operated or hemorrhaged animals with or without ATP-MgCl2 infusion. ATP-MgCl2 ameliorated and subsequently restored the decreased maximum binding capacity (Bmax) of the high-affinity receptor component and significantly improved Bmax of the low-affinity receptor component. ATP-MgCl2 administration also produced a progressive enhancement in the affinity of the low-affinity receptor component. Thus the beneficial effects of ATP-MgCl2 observed after trauma-hemorrhage and resuscitation may be, in part, due to the restoration of P2-purinoceptor binding capacity and the enhancement of the receptor affinity.

scholarly journals Establishment of dorsal-ventral polarity of theDrosophilaegg requirescapicuaaction in ovarian follicle cells

Development ◽  
2001 ◽  
Vol 128 (22) ◽  
pp. 4553-4562 ◽  
Author(s):  
Deborah J. Goff ◽  
Laura A. Nilson ◽  
Donald Morisato
Keyword(s):  
Target Genes ◽  
Nuclear Translocation ◽  
Ovarian Follicle ◽  
Growth Factor Receptor ◽  
Follicle Cell ◽  
Dorsal Side ◽  
Follicle Cells ◽  
Follicular Epithelium ◽  
Egfr Signaling ◽  
Cell Nuclei

The dorsal-ventral pattern of the Drosophila egg is established during oogenesis. Epidermal growth factor receptor (Egfr) signaling within the follicular epithelium is spatially regulated by the dorsally restricted distribution of its presumptive ligand, Gurken. As a consequence, pipe is transcribed in a broad ventral domain to initiate the Toll signaling pathway in the embryo, resulting in a gradient of Dorsal nuclear translocation. We show that expression of pipe RNA requires the action of fettucine (fet) in ovarian follicle cells. Loss of maternal fet activity produces a dorsalized eggshell and embryo. Although similar mutant phenotypes are observed with regulators of Egfr signaling, genetic analysis suggests that fet acts downstream of this event. The fet mutant phenotype is rescued by a transgene of capicua (cic), which encodes an HMG-box transcription factor. We show that Cic protein is initially expressed uniformly in ovarian follicle cell nuclei, and is subsequently downregulated on the dorsal side. Earlier studies described a requirement for cic in repressing zygotic target genes of both the torso and Toll pathways in the embryo. Our experiments reveal that cic controls dorsal-ventral patterning by regulating pipe expression in ovarian follicle cells, before its previously described role in interpreting the Dorsal gradient.

Protein Synthesis and Uptake by Isolated Cecropia Oocytes

1971 ◽  
Vol 8 (3) ◽  
pp. 735-750
Author(s):  
LUCY M. ANDERSON
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Perchloric Acid ◽  
Selection Process ◽  
Ovarian Follicle ◽  
Follicle Cell ◽  
Follicle Cells ◽  
Follicular Epithelium ◽  
Blood Proteins ◽  
Cell Product

A procedure has been developed for separating the oocytes and follicular epithelium-nurse cell complexes making up the vitellogenic ovarian follicle of the Cecropia moth. Both components remained viable during short-term in vitro incubation in female blood. Isolated epithelial cells were found by autoradiography to incorporate tritiated amino acids and to secrete a fixable, non-dialysable labelled material. Isolated oocytes incubated in a blood medium containing this tritiated, dialysed follicle cell product incorporated it in small cortical yolk bodies, presumably by pinocytosis. Quantitative perchloric acid-precipitation and scintillation counting indicated that the amount of labelled material incorporated by the oocytes increased with time. These results provide direct confirmation of a follicle contribution to the yolk. Isolated oocytes were also tested for their ability to incorporate labelled amino acids. Fixable label was observed autoradiographically throughout the oocyte cytoplasm, with the greatest concentration in the cortex, but little appeared in the yolk spheres. The amount of perchloric acid-precipitable amino acid in oocytes incubated in female blood increased with time for up to 2 h and then remained constant or decreased slightly. In medium that had been previously conditioned by follicle cells and dialysed, however, incorporation of labelled amino acid continued for at least 4 h. A possible interpretation of this result is that stimulation of pinocytosis by the epithelial cell products causes increased turnover of cell membrane and demands continued synthesis of new proteins. Labelled female blood proteins were not incorporated into yolk to an appreciable extent by isolated oocytes, even in the presence of follicle cell product. Perhaps extracellular preconcentration, as occurs in the intact follicle, is necessary for effective accrual of blood proteins. The female blood proteins did become associated with the oocyte cortex, however, and exhibited a higher affinity for the oocyte than male blood proteins. Thus preferential adsorption to the oocyte surface may be a component of the selection process in vitellogenesis.

Ectopic activation of torpedo/Egfr, a Drosophila receptor tyrosine kinase, dorsalizes both the eggshell and the embryo

Development ◽  
1997 ◽  
Vol 124 (19) ◽  
pp. 3871-3880 ◽  
Author(s):  
A.M. Queenan ◽  
A. Ghabrial ◽  
T. Schupbach
Keyword(s):  
Cell Fate ◽  
Growth Factor Receptor ◽  
Follicle Cell ◽  
Follicle Cells ◽  
Follicular Epithelium ◽  
Cell Fates ◽  
Egfr Activation ◽  
Egg Chamber ◽  
Anterior Posterior ◽  
Anterior Posterior Axis

The Drosophila gene torpedo/Egfr (top/Egfr) encodes a homolog of the vertebrate Epidermal Growth Factor receptor. This receptor is required several times during the life cycle of the fly for the transmisson of developmental cues. During oogenesis, Top/Egfr activation is required for the establishment of the dorsal/ventral axis of the egg and the embryo. To examine how ectopic Top/Egfr activation affects cell fate determination, we constructed an activated version of the protein. Expression of this activated form (lambda top) in the follicle cells of the ovary induces dorsal cell fates in both the follicular epithelium and the embryo. Different levels of expression resulted in different dorsal follicle cell fates. These dorsal cell fates were expanded in the anterior, but not the posterior, of the egg, even in cases where all the follicle cells covering the oocyte expressed lambda top. The expression of genes known to respond to top/Egfr activation, argos (aos), kekkon1 (kek 1) and rhomboid (rho), was also expanded in the presence of the lambda top construct. When lambda top was expressed in all the follicle cells covering the oocyte, kek 1 and argos expression was induced in follicle cells all along the anterior/posterior axis of the egg chamber. In contrast, rho RNA expression was only activated in the anterior of the egg chamber. These data indicate that the response to Top/Egfr signaling is regulated by an anterior/posterior prepattern in the follicle cells. Expression of lambda top in the entire follicular epithelium resulted in an embryo dorsalized along the entire anterior/posterior axis. Expression of lambda top in anterior or posterior subpopulations of follicle cells resulted in regionally autonomous dorsalization of the embryos. This result indicates that subpopulations of follicle cells along the anterior/posterior axis can respond to Top/Egfr activation independently of one another.

scholarly journals A new unextracted-sample radioimmunoassay method for hepatic endogenous nuclear l-tri-iodothyronine content. Validity of its use in determining nuclear receptor binding characteristics

1982 ◽  
Vol 208 (3) ◽  
pp. 641-649 ◽  
Author(s):  
Toshihiro Yagura ◽  
Paul G. Walfish
Keyword(s):  
Receptor Binding ◽  
Binding Capacity ◽  
Nuclear Extract ◽  
Affinity Constant ◽  
Lower Sensitivity ◽  
Scatchard Analysis ◽  
Binding Characteristics ◽  
Radioimmunoassay Method ◽  
True Values ◽  
Good Agreement

Endogenous l-tri-iodothyronine content in an hepatic nuclear extract was measured by a new unextracted-sample radioimmunoassay method using 8-anilinonaphthalene-1-sulphonic acid to inhibit the l-[125I]tri-iodothyronine binding to the nuclear l-tri-iodothyronine receptor within the extract. For this method, the lower sensitivity limit was 3.125 pg/tube, the recovery of added l-tri-iodothyronine was 90–120%, and the between-assay coefficient of variation was 10%. The amount of endogenous l-tri-iodothyronine was 10–40 pg/0.2 ml of hepatic nuclear extract from euthyroid rats, compared with less than 3.125 pg/0.2 ml from thyroidectomized rats. The results obtained by this new method were compared with a Sephadex G-25 column extracted-sample radioimmunoassay method and showed a good agreement. The values for the endogenous l-tri-iodothyronine content were utilized to correct for the l-tri-iodothyronine concentration within the binding assay mixture in order to accurately determine by Scatchard analysis the binding characteristics of the nuclear l-tri-iodothyronine receptor. The validity of the correction for endogeneous l-tri-iodothyronine was demonstrated by using a nuclear extract from a thyroidectomized rat which was preincubated with a small known amount of l-tri-iodothyronine before determining the nuclear l-tri-iodothyronine receptor binding characteristics. When the Scatchard plots were corrected for the preincubated dose, the results obtained were similar to true values, but they were falsely lower when not corrected. It is concluded that the necessity and validity of using endogenous l-tri-iodothyronine corrections in the Scatchard analytical computations of the nuclear l-tri-iodothyronine receptor binding characteristics has been demonstrated, being particularly more important for affinity constant than maximum binding capacity.

The binding of juvenile hormone to membranes of follicle cells in the insect Rhodnius prolixus

1985 ◽  
Vol 63 (2) ◽  
pp. 102-106 ◽  
Author(s):  
T. T. Ilenchuk ◽  
K. G. Davey
Keyword(s):  
Sodium Dodecyl Sulfate ◽  
Juvenile Hormone ◽  
Binding Sites ◽  
Gel Electrophoresis ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Rhodnius Prolixus ◽  
Follicle Cells ◽  
Scatchard Analysis ◽  
Saturable Binding

3H-labelled insect juvenile hormone, which has previously been shown to stimulate the Na,K-ATPase of membrane preparations of the follicle cells of the ovary of Rhodnius prolixus, exhibits saturable binding to microsomal preparations from the follicle cells of vitellogenic and previtellogenic follicles. No saturable binding is detectable in preparations from brain. Scatchard analysis shows that there is a greater density of binding sites on the membranes from vitellogenic, as opposed to previtellogenic, follicles. Sodium dodecyl sulfate – polyacrylamide gel electrophoresis of solubilized membrane preparations shows that the hormone binds to peptides in two regions of the gel, corresponding to 43 000 and 150 000 daltons. [3H]Ouabain also binds to a peptide in the 150 000 region, as well as to the 100 000 region. Juvenile hormone thus may be binding directly to at least one of the constituent peptides of the Na,K-ATPase complex.

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