A novel osteopontin-like protein is expressed in the trout ovary during ovulation

Using suppression subtraction hybridization between ovulatory and postovulatory trout ovaries, a down-regulated cDNA was obtained that presumably encodes a novel ovarian protein ('NOP'). NOP mRNA is present in the ovary during ovulation and down-regulated by 48 h postovulation, suggesting an important role for NOP during ovulation. Besides the ovary, NOP is also strongly expressed in the testis and at lower levels in the skin, gills, kidney and gastrointestinal tract. While the overall identity is not high, NOP shares several sequence similarities with mammalian and chicken osteopontins, including the percentage of aspartate, serine and alanine residues and the presence of a cell attachment motif.     

Germinal epithelium, folliculogenesis, and postovulatory follicles in ovaries of rainbow trout, Oncorhynchus mykiss (Walbaum, 1792) (Teleostei, protacanthopterygii, salmoniformes)

The rainbow trout, Oncorhynchus mykiss (Walbaum, 1792), is a salmoniform fish that spawns once per year. Ripe females that had ovulated naturally, and those induced to ovulate using salmon gonadotropin-releasing hormone, were studied to determine whether follicles were forming at the time of spawning and to describe the process of folliculogenesis. After ovulation, the ovaries of postspawned rainbow trout were examined histologically, using the periodic acid-Schiff procedure, to stain basement membranes that subtend the germinal epithelium and to interpret and define the activity of the germinal epithelium. After spawning, the ovary contained a few ripe oocytes that did not ovulate, numerous primary growth oocytes including oocytes with cortical alveoli, and postovulatory follicles. The germinal epithelium was active in postspawned rainbow trout, as determined by the presence of numerous cell nests, composed of oogonia, mitotic oogonia, early diplotene oocytes, and prefollicle cells. Cell nests were separated from the stroma by a basement membrane continuous with that subtending the germinal epithelium. Furthermore, follicles containing primary growth oocytes were connected to the germinal epithelium; the basement membrane surrounding the follicle joined that of the germinal epithelium. After ovulation, the basement membrane of the postovulatory follicle was continuous with that of the germinal epithelium. We observed consistent separation of the follicle, composed of an oocyte and surrounding follicle cells, from the ovarian stroma by a basement membrane. The follicle is derived from the germinal epithelium. As with the germinal epithelium, follicle cells derived from it never contact those of the connective tissue stroma. As with epithelia, they are always separated from connective tissue by a basement membrane.     

Ultrastructure of somatic tissues in the ovaries of a chaetognath (Ferosagitta hispida)

Transmission electron microscopy reveals that the ovaries of Ferosagitta hispida contain four somatic tissues. A myoepithelial ovary wall, continuous with a thin layer of peritoneocytes lining the coelomic cavity, encloses a fluid-filled ovarian space in which oocytes develop. Lamellar extensions of a “follicular reticulum” branch throughout the ovarian space and ensheath developing oocytes. This tissue has been overlooked in most previous studies of chaetognath ovaries. A bipartite oviductal complex extends the length of each ovary just within the lateral ovary wall. It consists of a flattened, blindly ending cellular tube, herein referred to as the cellular sheath, and an enclosed syncytium. Sheath cells secrete an electron-dense product into the ovarian space. Those sheath cells directly bordering the syncytium are contractile and are joined to the to the syncytium by gap junctions and microvillar interdigitations. The syncytium contains a complex of membrane-bounded lumina. The latter sometimes enclose sperm received during mating or ovulated eggs. Thus the syncytium serves both as a seminal receptacle and as a duct for passage of eggs to the outside. Contrary to several classical reports, the cellular sheath and syncytium of the oviductal complex do not separate at ovulation to form a temporary oviductal lumen.     

Ovarian structure of the marsupial frog Gastrotheca riobambae (Fowler)

The mature ovary of Gastrotheca riobambae presents large oocytes (3 mm in diameter) of pale yellow color. After ovulation and the beginning of embryonic incubation, the empty postovulatory follicles can be recognized in the ovary for about 30 days. The granulosa of these follicles never fills the follicular lumen and this cavity becomes filled with fluid during the first five days of incubation. Later, at 18 days of incubation, the lumen is mostly empty and contains few cells of the granulosa. Shrinkage results in the disappearance of the follicular cavity by approximately the thirtieth day of incubation. The thecae are thick and become separated by a space. This space is filled progressively with cells, blood capillaries and fluid. After the thirtieth to fortieth day of incubation, these follicles become regressive and disappear. The postovulatory follicles of Gastrotheca may correspond to corpora lutea. The evidence suggests that pouch vascularization and the formation of embryonic chambers of pouch tissue may be under ovarian control. In addition, the process of vitellogenesis is influenced by incubation, as most growth of the ovarian oocyte occurs after birth of the tadpoles. Follicular atresia is common and is similar to that of other frogs.     

Characterization of insulin-like growth factor-binding proteins of porcine ovarian follicular fluid.

Using competitive ligand-binding studies, ligand blotting, and immunoprecipitation, we have characterized the insulin-like growth factor (IGF)-binding proteins (BPs) of porcine follicular fluid. Competitive ligand-binding studies revealed a preference of ovarian IGFBPs for IGF-II over IGF-I. Follicular fluid from small, 1-3-mm follicles had nearly twice the binding capacity for IGFs as that from large, 6-10-mm follicles. Ligand blots of porcine follicular fluid resolved 5 major bands of IGF-binding activity having apparent molecular sizes of 44, 40, 34, 29, and 22 kDa. The 40-44-kDa bands were immunoprecipitated by an antibody to porcine IGFBP-3, the acid-stable subunit of the 150-kDa growth hormone-dependent IGF-binding protein complex of porcine serum. The 34-kDa band was immunoprecipitated by an antibody to rat IGFBP-2, the major IGF-binding protein found in fetal rat serum. To date we have been unable to immunoprecipitate the 29- and 22-kDa bands with any of the antibodies tested, including a panel of monoclonal antibodies to human IGFBP-1, the amniotic fluid IGF-binding protein. The 40-44-kDa species (IGFBP-3) was the predominant form and was equally abundant in fluid from large and small follicles. In contrast, the smaller forms, including IGFBP-2 and the 29- and 22-kDa forms were significantly more prominent in fluid from small follicles. In view of other studies indicating a significant effect of IGFBPs on ovarian cell function, follicular IGFBPs may play an important role in the IGF autocrine/paracrine regulatory system of the ovary.     

Expression of HSP70 and CYP1A protein in ovary and liver of juvenile rainbow trout exposed to beta-naphthoflavone

Cytochrome P4501A (CYP1A) and the 70-kDa stress protein (HSP70) were determined using Western blotting in the ovary and liver of juvenile female rainbow trout (Oncorhynchus mykiss) exposed for 4 days to beta-naphthoflavone (betaNF) following a single intraperitoneal injection. Ovarian CYP1A protein was observed in both control and betaNF-exposed fish, indicating constitutive and inducible expression of CYP1A in immature trout ovaries. CYP1A protein levels determined using densitometry were 14- and 46-fold greater in betaNF-exposed trout compared to controls in the liver and ovary, respectively. Hepatic microsomal ethoxyresorufin O-deethylase (EROD) activity, a specific catalytic marker of CYP1A, was also induced 38-fold above controls following betaNF exposure. Hepatic HSP70 protein expression was significantly higher in whole cell homogenates, but not in cytosolic fractions, collected from betaNF-exposed fish in comparison to control fish. There was no difference in ovarian HSP70 levels determined in whole cell homogenates between control and betaNF-exposed fish. The observation that unlike liver, ovarian HSP70 expression remained unchanged following induction of CYP1A protein may be related to the sensitivity of the teleost ovary to environmental toxicants that act as aryl hydrocarbon receptor agonists.     

Identification of the acid proteinase in human seminal fluid as a gastricsin originating in the prostate

Summary On the basis of a) kinetic data obtained with a synthetic substrate and two peptide inhibitors and b) immunological cross-reactivity, it is shown that the aspartic proteinase of human seminal fluid is a gastricsin. The source of the precursor (progastricsin) in the male genital tract is identified to be the prostate.     

Zinc-binding property of the major yolk protein in the sea urchin - implications of its role as a zinc transporter for gametogenesis

Major yolk protein (MYP), a transferrin superfamily protein that forms yolk granules in sea urchin eggs, is also contained in the coelomic fluid and nutritive phagocytes of the gonad in both sexes. MYP in the coelomic fluid (CFMYP; 180 kDa) has a higher molecular mass than MYP in eggs (EGMYP; 170 kDa). Here we show that MYP has a zinc-binding capacity that is diminished concomitantly with its incorporation from the coelomic fluid into the gonad in the sea urchin Pseudocentrotus depressus. Most of the zinc in the coelomic fluid was bound to CFMYP, whereas zinc in eggs was scarcely bound to EGMYP. Both CFMYP and EGMYP were present in nutritive phagocytes, where CFMYP bound more zinc than EGMYP. Saturation binding assays revealed that CFMYP has more zinc-binding sites than EGMYP. Labeled CFMYP injected into the coelom was incorporated into ovarian and testicular nutritive phagocytes and vitellogenic oocytes, and the molecular mass of part of the incorporated CFMYP shifted to 170 kDa. Considering the fact that the digestive tract is a major production site of MYP, we propose that CFMYP transports zinc, essential for gametogenesis, from the digestive tract to the ovary and testis through the coelomic fluid, after which part of the CFMYP is processed to EGMYP with loss of zinc-binding site(s).