Structural modulation of the surface and cytoplasm of oocytes during vitellogenesis in the lobster, Homarus americanus. An electron microscope-protein tracer study.
01 Jan 1980-Journal of Morphology (Wiley Subscription Services, Inc., A Wiley Company)-Vol. 163, Iss: 1, pp 13-26
TL;DR: The hypothesis for a dual source of yolk protein in the American lobster is supported, notably, pinocytotic incorporation of extra‐oocytic material and hypertrophy of oocyte surface microvilli.
Abstract: The present investigation describes the ultrastructural changes which occur at the surface and in the cytoplasm of developing oocytes of the lobster, Homarus americanus, during vitellogenesis. The immature oocytes showed no surface specializations of the oolemma and no pinocytotic activity was observed. Horseradish peroxidase (HRP) tracer studies showed penetration of the tracer into the perivitelline space, but no uptake by the oocytes. The surfaces of oocytes examined during vitellogenesis, when yolk protein accumulation was maximal, exhibited numerous microvilli that projected into the perivitelline space, often appearing to be embedded in the follicular cell mass. In addition, the plasma membrane of vitellogenic oocytes contained many pinocytotic pits frequently situated at the bases of microvilli. The perivitelline space was engorged with electrondense material which appeared similar to that contained in pinocytotic structures of the oocytes. Vitellogenic oocytes incubated in HRP showed uptake of tracer reaction product by the coated pits and vesicles of the oolemma. Aggregation and subsequent fusion of these vesicles into large multivesicular bodies of ingested material were also observed in vitellogenic oocytes. Animals artificially induced to undergo vitellogenesis exhibited modulations of oocyte ultrastructure similar to those of normal vitellogenesis, notably, pinocytotic incorporation of extra-oocytic material and hypertrophy of oocyte surface microvilli. This study supports the hypothesis for a dual source of yolk protein in the American lobster.
Citations
More filters
Journal Article•
TL;DR: A. Vitellogenesis control, timing of the reproductive cycle: duration and relation with the molting cycle 227, and ways of action.
Abstract: 1. General considerations 221 2. Origin of vitellogenin 222 3. Vitellogenin uptake by vitellogenic ovaries 223 a) Transformation and role of the follicle envelope 223 b) Vitellogenic oocyte and endocytosis mechanism 224 4. From vitellogenin to vitellin: a processing? 224 5. Vitellogenin synthesis and vitellogenin level in haemolymph as means for monitoring vitellogenesis 226 6. Timing of the reproductive cycle: duration and relation with the molting cycle 227 B. Vitellogenesis control 229 1. Inhibitory control by VIH (Vitellogenesis Inhibiting Hormone) 229 a) The X organ-sinus gland complex 229 Eyestalked species Eyestalkless species b) Ways of action 230 Control of vitellogenin synthesis Control of vitellogenin uptake by the oocytes c) Extraction and purification of VIH 231 d) Latest data on VIH 231 2. Stimulatory control 233 a) Neurohumoral factors 234 b) Vitellogenin Stimulating Ovarian Hormone (VSOH) 234 c) Ecdysteroids 234 d) Juvenoids 235 e) Ovary-stimulating factor from males 237
236 citations
TL;DR: Yolk proteins were isolated from ovaries of the shrimp Penaeus vannamei and used as an antigen for antibody production in rabbits and extracts of shrimp eyestalks inhibited in vitro protein synthesis by both tissues.
Abstract: 1. 1. Yolk proteins were isolated from ovaries of the shrimp Penaeus vannamei and used as an antigen for antibody production in rabbits. 2. 2. Protein synthesis was measured for both the hepatopancreas and the ovary in vitro, and proteins present in both tissues were immunoreactive with the antibodies. 3. 3. Extracts of shrimp eyestalks inhibited in vitro protein synthesis by both tissues. The inhibitory factor from the eyestalks was heat stable and had a molecular weight of 3300 daltons.
113 citations
TL;DR: Vitellogenin concentrations increased in the hemolymph of prawns in the early stages of ovarian development and were maintained at high levels until stage V, which correlated closely with the gonadosomatic index, the oocyte diameters, and the characteristics of ovarian histology.
Abstract: Summary The objectives were to characterize the ovarian development and hemolymph vitellogenin concentrations during the reproductive cycle in the freshwater prawn, Macrobrachium rosenbergii. The ovaries of M. rosenbergii were classified into five developmental stages, and the ovarian histology of each stage was characterized. The ovarian stages correlated closely with the gonadosomatic index, the oocyte diameters, and the characteristics of ovarian histology. Sequential bleeding at 3-day intervals from each of seven prawns was also conducted for at least two reproductive cycles. Vitellogenin concentrations in the hemolymph were measured with a validated enzyme-linked immunosorbent assay. Vitellogenin concentrations in the hemolymph showed similar profiles in the 18 reproductive cycles tested in these prawns. Vitellogenin concentrations increased in the hemolymph of prawns in the early stages of ovarian development (stage I or 11) and were maintained at high levels until stage V. Hemolymph vitellogenin co...
88 citations
TL;DR: The results lead to the conclusion that the contribution of Vg to the formation of Vt in the ovary is quantitatively insignificant.
Abstract: The concentration of vitellogenin (Vg) in the hemolymph of Penaeus semisulcatus was found to increase from an average of 50 μg ml-1 to 439 μg ml-1 in female shrimp during ovarian development. The most significant increase in Vg occurred concomitant with the increase in the vitellin (Vt) content of oocytes with an average diameter (AOD) ranging between 150 and 250 μm. The amount of Vt in the oocytes was found to increase linearly from a mean of 0.0126 mg to 4.55 mg per gm body weight. However, the percentage of Vt in the total protein was found to decrease, from 67% in ovaries with AOD of 150-250 μm, to 39.7% in ovaries with AOD of 350 μm or larger. The volume of the hemolymph was found to be 0.4 ml per gm body weight and did not change significantly during ovarian development. Assuming that Vg in the hemolymph represents either an extraovarian origin of Vt or an active secretion from the ovary, a turnover rate of two to three times per day was calculated over one full cycle of oocyte development. However, during the most significant increase in Vt in the ovary (in ovaries with AOD of 150-250 μm), the turnover rate in the hemolymph could reach seven to eight times per day. The results lead to the conclusion that the contribution of Vg to the formation of Vt in the ovary is quantitatively insignificant.
66 citations
01 Jan 1989
TL;DR: Research reports from 25 laboratories working with the brine shrimp Artemia to investigate the patterns of development, the biochemistry and the structure and expression of genes in crustaceans are divided into sections on dormancy and development.
Abstract: Research reports from 25 laboratories working with the brine shrimp Artemia to investigate the patterns of development, the biochemistry and the structure and expression of genes in crustaceans. The 27 full papers and abstracts of another 17 are divided into sections on dormancy and development, cel
64 citations
References
More filters
TL;DR: The stain reported here differs from previous alkaline lead stains in that the chelating agent, citrate, is in sufficient excess to sequester all lead present, and is less likely to contaminate sections.
Abstract: Aqueous solutions of lead salts (1, 2) and saturated solutions of lead hydroxide (1) have been used as stains to enhance the electron-scattering properties of components of biological materials examined in the electron microscope. Saturated solutions of lead hydroxide (1), while staining more intensely than either lead acetate or monobasic lead acetate (l , 2), form insoluble lead carbonate upon exposure to air. The avoidance of such precipitates which contaminate surfaces of sections during staining has been the stimulus for the development of elaborate procedures for exclusion of air or carbon dioxide (3, 4). Several modifications of Watson's lead hydroxide stain (1) have recently appeared (5-7). All utilize relatively high pH (approximately 12) and one contains small amounts of tartrate (6), a relatively weak complexing agent (8), in addition to lead. These modified lead stains are less liable to contaminate the surface of the section with precipitated stain products. The stain reported here differs from previous alkaline lead stains in that the chelating agent, citrate, is in sufficient excess to sequester all lead present. Lead citrate, soluble in high concentrations in basic solutions, is a chelate compound with an apparent association constant (log Ka) between ligand and lead ion of 6.5 (9). Tissue binding sites, presumably organophosphates, and other anionic species present in biological components following fixation, dehydration, and plastic embedding apparently have a greater affinity for this cation than lead citrate inasmuch as cellular and extracellular structures in the section sequester lead from the staining solution. Alkaline lead citrate solutions are less likely to contaminate sections, as no precipitates form when droplets of fresh staining solution are exposed to air for periods of up to 30 minutes. The resultant staining of the sections is of high intensity in sections of Aralditeor Epon-embedded material. Cytoplasmic membranes, ribosomes, glycogen, and nuclear material are stained (Figs. 1 to 3). STAIN SOLUTION: Lead citrate is prepared by
24,137 citations
TL;DR: The early stages of absorption of intravenously injected horseradish peroxidase in proximal tubules of mouse kidney were studied with a new ultrastructural cytochemical technique, which gives sharp localization and is sensitive to protein transport.
Abstract: The early stages of absorption of intravenously injected horseradish peroxidase in proximal tubules of mouse kidney were studied with a new ultrastructural cytochemical technique. In animals killed as early as 90 sec after injection, reaction product was found on the brushborder membranes and in the apical tubular invaginations. From the latter structures it was transported to the apical vacuoles, in which it was progressively concentrated to form protein absorption droplets. The method, which employs 3,3'-diaminobenzidine as oxidizable substrate, gives sharp localization and is sensitive. This system is advantageous in studying the early stages of renal tubular protein absorption, since small amounts of protein on membranes and in tubules and vesicles can be detected easily. The method also appears promising for studying protein transport in a variety of other cells and tissues.
6,495 citations
TL;DR: Endothelial and epithelial tight junctions occlude the interspaces between blood and parenchyma or cerebral ventricles, thereby constituting a structural basis for the blood-brain and blood-cerebrospinal fluid barriers.
Abstract: Certain junctions between ependymal cells, between astrocytes, and between some electrically coupled neurons have heretofore been regarded as tight, pentalaminar occlusions of the intercellular cleft. These junctions are now redefined in terms of their configuration after treatment of brain tissue in uranyl acetate before dehydration. Instead of a median dense lamina, they are bisected by a median gap 20–30 A wide which is continuous with the rest of the interspace. The patency of these "gap junctions" is further demonstrated by the penetration of horseradish peroxidase or lanthanum into the median gap, the latter tracer delineating there a polygonal substructure. However, either tracer can circumvent gap junctions because they are plaque-shaped rather than complete, circumferential belts. Tight junctions, which retain a pentalaminar appearance after uranyl acetate block treatment, are restricted primarily to the endothelium of parenchymal capillaries and the epithelium of the choroid plexus. They form rows of extensive, overlapping occlusions of the interspace and are neither circumvented nor penetrated by peroxidase and lanthanum. These junctions are morphologically distinguishable from the "labile" pentalaminar appositions which appear or disappear according to the preparative method and which do not interfere with the intercellular movement of tracers. Therefore, the interspaces of the brain are generally patent, allowing intercellular movement of colloidal materials. Endothelial and epithelial tight junctions occlude the interspaces between blood and parenchyma or cerebral ventricles, thereby constituting a structural basis for the blood-brain and blood-cerebrospinal fluid barriers.
2,345 citations
TL;DR: During stimulation the intracellular compartments of this synapse change shape and take up extracellular protein in a manner which indicates that synaptic vesicle membrane added to the surface during exocytosis is retrieved by coated vesicles and recycled into new synaptic vESicles by way of intermediate cisternae.
Abstract: When the nerves of isolated frog sartorius muscles were stimulated at 10 Hz, synaptic vesicles in the motor nerve terminals became transiently depleted. This depletion apparently resulted from a redistribution rather than disappearance of synaptic vesicle membrane, since the total amount of membrane comprising these nerve terminals remained constant during stimulation. At 1 min of stimulation, the 30% depletion in synaptic vesicle membrane was nearly balanced by an increase in plasma membrane, suggesting that vesicle membrane rapidly moved to the surface as it might if vesicles released their content of transmitter by exocytosis. After 15 min of stimulation, the 60% depletion of synaptic vesicle membrane was largely balanced by the appearance of numerous irregular membrane-walled cisternae inside the terminals, suggesting that vesicle membrane was retrieved from the surface as cisternae. When muscles were rested after 15 min of stimulation, cisternae disappeared and synaptic vesicles reappeared, suggesting that cisternae divided to form new synaptic vesicles so that the original vesicle membrane was now recycled into new synaptic vesicles. When muscles were soaked in horseradish peroxidase (HRP), this tracerfirst entered the cisternae which formed during stimulation and then entered a large proportion of the synaptic vesicles which reappeared during rest, strengthening the idea that synaptic vesicle membrane added to the surface was retrieved as cisternae which subsequently divided to form new vesicles. When muscles containing HRP in synaptic vesicles were washed to remove extracellular HRP and restimulated, HRP disappeared from vesicles without appearing in the new cisternae formed during the second stimulation, confirming that a one-way recycling of synaptic membrane, from the surface through cisternae to new vesicles, was occurring. Coated vesicles apparently represented the actual mechanism for retrieval of synaptic vesicle membrane from the plasma membrane, because during nerve stimulation they proliferated at regions of the nerve terminals covered by Schwann processes, took up peroxidase, and appeared in various stages of coalescence with cisternae. In contrast, synaptic vesicles did not appear to return directly from the surface to form cisternae, and cisternae themselves never appeared directly connected to the surface. Thus, during stimulation the intracellular compartments of this synapse change shape and take up extracellular protein in a manner which indicates that synaptic vesicle membrane added to the surface during exocytosis is retrieved by coated vesicles and recycled into new synaptic vesicles by way of intermediate cisternae.
2,032 citations
TL;DR: Preliminary radioautographs, and certain morphological features of the fat body, ovary, and midgut, suggest that the midGut is the principal site of yolk protein synthesis in the mosquito.
Abstract: Yolk proteins are thought to enter certain eggs by a process akin to micropinocytosis but the detailed mechanism has not been previously depicted. In this study the formation of protein yolk was investigated in the mosquito Aedes aegypti L. Ovaries were fixed in phosphate-buffered osmium tetroxide, for electron microscopy, before and at intervals after a meal of blood. The deposition of protein yolk in the oocyte was correlated with a 15-fold increase in 140 mµ pit-like depressions on the oocyte surface. These pits form by invagination of the oocyte cell membrane. They have a 20 mµ bristle coat on their convex cytoplasmic side. They also show a layer of protein on their concave extracellular side which we propose accumulates by selective adsorption from the extraoocyte space. The pits, by pinching off from the cell membrane become bristle-coated vesicles which carry the adsorbed protein into the oocyte. These vesicles lose the coat and then fuse to form small crystalline yolk droplets, which subsequently coalesce to form the large proteid yolk bodies of the mature oocyte. Preliminary radioautographs, and certain morphological features of the fat body, ovary, and midgut, suggest that the midgut is the principal site of yolk protein synthesis in the mosquito.
1,284 citations