Ovaries Of Fish Research Articles

Acetyl Salmon Endorphin-Like Immunoreactivity in the Ovary of Two Teleostean Species: Changes with Environmental Conditions

FACCHINETTI, F., D. RADI, G. MOSCONI, O. CARNEVALI, M. PESTARINO AND A. M. POLZONETTI-MAGNI.Acetyl salmon endorphin-like immunoreactivity in the ovary of two teleostean species: changes with environmental conditions.PEPTIDES 18(7) 957–963, 1997.—The presence of salmon acetylated endorphin (acetyl sEP) in the ovary of seabream and sea bass was investigated through immunocytochemical and biochemical techniques in order to compare aquatic species with terrestrial ones. Endorphin-like immunoreactivity was found in the cytoplasm of oogonia and similar immunostaining was present in the granulosa layer of mature follicles. In both pituitary and ovarian extracts of the two teleostean species, acetyl sEP-like immunoreactivity was distributed over three main peaks, the second one corresponding to the elution time of the reference synthetic peptide. Serial dilutions of HPLC fraction II of the ovaries of both fishes ran parallel with the standard curve obtained with reference peptide. The ovarian content of acetyl sEP, obtained by calculating the integrated area of the fraction II peak, indicates large and highly significant (p < 0.01) differences in the amount of peptide found in ovarian tissues of wild seabream in comparison with that of farmed fish. Increased peptide values in wild animals with respect to farmed fish were also found in the sea bass. These data indicate that not only the pituitary, but also the ovary is sensitive to environmental cues, and strongly suggest the role of opioid peptides in adaptation.

Activity of UDP-GlcNAc:GlcNAcβ1→6(GlcNAcβ1→2) Manα1→R[GlcNAc to Man]β1→4N- Acetylglucosaminyltransferase VI (GnT VI) from the Ovaries ofOryzias latipes(Medaka Fish)

UDP-GlcNAc:GlcNAcβ1→(GlcNAcβ1→2) Manα1→R[GlcNAc to Man]β1→4N-acetylglucosaminyltransferase VI (GnT VI) activity was shown to be present in crude homogenates of Medaka fish (Oryzias latipes) ovaries using UDP-[14C]GlcNAc and synthetic GlcNAc β1→6 (GlcNAcβ1→2)Manα1→6Glcβ1→octyl as substrates. Characterization of this activity showed a pH optimum at about pH 7.0 and an absolute requirement for divalent cations. The optimum concentration of Mn2+was at about 25 mM. This finding is the first report on GnT VI activity in fish; the enzyme has previously been described only in avian tissues.

Role of very low density lipoproteins in the accumulation of o, p′-DDT in fish ovaries during gonadal recrudescence

The binding of o, p′-DDT by plasma lipoproteins and its accumulation in the gonads of Atlantic croaker ( Micropogonias undulatus) were investigated. Tissue accumulation of o, p′-DDT was determined in fish fed o, p′-DDT for a 3 week period during gonadal recrudescence at concentrations of 1.8, 10.8, and 54.6 μg o, p′-DDT per 100 g fish day −1. The ovaries accumulated significantly more o, p′-DDT than the testes at the three dosage levels ( P < 0.001). Furthermore, there was a positive linear correlation between the size of the ovaries, as calculated by the gonadosomatic index, and their o, p′-DDT content ( r 2 = 0.52, 0.85, and 0.76 for the low, middle and high doses, respectively). Compartmentalization of o, p′-DDT within the oocyte occurred, with over 95% of the o, p′-DDT present in the triglyceride-rich oil globule. The triglyceride-rich, very low density lipoprotein (VLDL) fraction of the plasma contained the highest percentage of o, p′-DDT (40%) with little (less than 7%) in the vitellogenin-containing VHDL. In addition, ovarian uptake of o, p′-DDT when it was bound to VLDL was six times greater than that observed after injection of o, p′-DDT bound to vitellogenin or in corn oil. The results suggest that o, p′-DDT is carried in the plasma via lipoproteins and that oocyte uptake of triglyceride-rich VLDL is a major mechanism of o, p′-DDT accumulation in croaker ovaries.

Effects of exogenous estradiol-17β on early growth and gonadal development of diploid and triploid female rainbow trout (Oncorhyncus mykiss)

Triploidy is a viable condition in teleosts. However, in many salmonids, the triploid condition in the female results in sterility as gametogenesis appears to be disrupted. Although the underlying mechanisms regulating the gonadal development of teleosts have not been clearly elucidated, the reversal of phenotypic sex by the administration of the appropriate exogenous steroid during early development supports the argument that gonadal steroids play a pivotal role in sexual differentiation and subsequent gonad development in these fish. To determine whether the failure of normal ovarian development in triploid female rainbow trout (Oncorhynchus mykiss) is due to an absence or reduction of endogenous sex steroids, ovarian morphology was compared between diploid and triploid juvenile rainbow trout treated with exogenous estradiol-17β (E2). The ovaries of both untreated and E2 treated diploid fish, at 145 days post-fertilization, contained synchronously developing oocytes in the perinucleolar stage, whereas ovaries from untreated and estradiol-treated triploid fish of the same age were considerably smaller and devoid of developing oocytes. No differences in the ovaries of triploid untreated fish and triploid fish treated with E2 were observed. It is reported that exposure to exogenous E2 during the period of gonadal differentiation is not sufficient to induce oocyte development in triploid rainbow trout. © 1996 Wiley-Liss, Inc.

Activation of hypothalamic neurons by intraovarian pressure signals in a teleost fish, Clarias batrachus: role of mechanosensitive channels.

Application of intraovarian pressure is known to trigger profound cytomorphological changes in the neurosecretory cells of nucleus preopticus in the teleost Clarias batrachus. These findings indicate the presence of stretch receptors in the ovaries, perhaps equipped with mechanosensitive channels that transduce the stretch signals to be transmitted to the brain. To test the occurrence of the mechanosensitive channels in the ovaries, we administered a range of pharmacological agents (lignocaine, quinidine, tetraethylammonium chloride, ethylene-diaminetetraacetic acid and gadolinium) known to block the mechanosensitive ion channels, in the ovarian lumen prior to the administration of the intraovarian pressure. Pretreatment with the above agents inhibited the response by the nucleus preopticus neurosecretory cells to intraovarian pressure. The results suggest the occurrence of the mechanosensitive channels in the ovaries of teleostean fishes. In terms of function we speculate that the stretch sensory system and the ensuing pathway connecting the ovaries with the hypothalamus might play a role in apprising the brain of the status of ovarian maturity and in the initiation of the spawning reflex.

Effects of exogenous estradiol‐17β on early growth and gonadal development of diploid and triploid female rainbow trout (Oncorhyncus mykiss)

Triploidy is a viable condition in teleosts. However, in many salmonids, the triploid condition in the female results in sterility as gametogenesis appears to be disrupted. Although the underlying mechanisms regulating the gonadal development of teleosts have not been clearly elucidated, the reversal of phenotypic sex by the administration of the appropriate exogenous steroid during early development supports the argument that gonadal steroids play a pivotal role in sexual differentiation and subsequent gonad development in these fish. To determine whether the failure of normal ovarian development in triploid female rainbow trout (Oncorhynchus mykiss) is due to an absence or reduction of endogenous sex steroids, ovarian morphology was compared between diploid and triploid juvenile rainbow trout treated with exogenous estradiol-17β (E2). The ovaries of both untreated and E2 treated diploid fish, at 145 days post-fertilization, contained synchronously developing oocytes in the perinucleolar stage, whereas ovaries from untreated and estradiol-treated triploid fish of the same age were considerably smaller and devoid of developing oocytes. No differences in the ovaries of triploid untreated fish and triploid fish treated with E2 were observed. It is reported that exposure to exogenous E2 during the period of gonadal differentiation is not sufficient to induce oocyte development in triploid rainbow trout. © 1996 Wiley-Liss, Inc.

Cloning of cDNAs for the Precursor Protein of a Low-Molecular-Weight Subunit of the Inner Layer of the Egg Envelope (Chorion) of the Fish Oryzias latipes

cDNA clones for L-SF, the precursor of a low-molecular-weight subunit (ZI-3) of the inner layer of the Oryzias latipes egg envelope were isolated from Lambda ZAP cDNA libraries constructed from the poly(A) + RNA of the liver of spawning female fish and estrogen-treated male fish. Among them, a clone, L-SF41, is 1473 bp long and contains an open reading frame encoding a signal peptide of 19 amino acids and L-SF protein of 420 amino acids. L-SF protein seems to be glycosylated, judging from the result of the glycanase digestion. L-SF protein contains a domain similar to ZP-domains in ZP3 of some mammalian species. Northern blot analysis employing XhoI- SmaI fragments of the cloned cDNA as probes revealed that expression of the L-SF gene occurred exclusively in the livers of spawning female fish and estrogen-treated male fish and that there was no mRNA encoding L-SF in the ovary of the spawning female fish.

Microflora of Fermented Puffer Fish Ovaries in Rice-Bran &amp;ldquo;Fugunoko Nukazuke&amp;rdquo;

Microbial flora of an indigenous food to Japan, fermented puffer fish ovaries, “fugunoko nukazuke”, were examined. Samples used for the examinations were salted ovaries of puffer fish Fugu stictonotum for 2 months and 1 year, exudate from ovaries after 2 months' and 1 year's salting, ovaries fermented in rice-bran for 4 months and 2 years, and rice-bran fermented for 4 months and 2 years. The viable bacterial counts obtained from these samples were different dependingon the culture conditions and manufacturing process. However, high counts of 107 cfu/g and 107 cfu/ml were obtained in some samples of fermented rice-bran and exudate. Most isolates which were tolerant to high levels of salt concentration can be tentativelydivided into four groups: lactic acid cocci, halophilic anaerobes, Pseudomonas-like halophiles, and halophilic archaea. These four groups of bacteria were found insalted ovaries and exudate, while in the samples fermented with rice-bran the dominant microflora were lactic acid cocci. Bacillus, Corynebacterium, and Staphylococcus were also isolated, but the counts of these were much lower.

Sublethal malathion induced changes in the ovary of an air-breathing fish, Heteropneustes fossilis: a histological study

This paper describes effects of a sublethal (1.2 mg 1−1) organophosphate, malathion, on the ovary of an air breathing catfish, Heteropneustes fossilis. The study focuses on microscopic changes that occur on ovigerous lamellae, oocytes at different stages of development and the nucleus of the immature oocyte. Also, change in estrogen levels in blood serum is investigated. Clumping of cytoplasm appears after 24 h of exposure to malathion. Clumping intensified after 48 h. Degeneration in the follicular cells was also observed. After 72 h exposure the number of nucleoli increased, nuclear materials shrunk, oocytes became adhered. With 96 h of exposure, nuclear materials of all the oocytes shrunk to a smaller clump. The oocytes fused together, and follicular epithelium became loose and ruptured. A few atretic oocytes were visible. Radioimmunoassay of the estrogen level in blood serum after 72 h of exposure of malathion showed a reduction in the level. This study showed that the histopathological condition of the gonad is reflected in malfunctioning of the endocrine system and hormonal disbalance.

Insulin as an Amplifier of Gonadotropin Action on Steroid Production: Mechanisms and Sites of Action in Goldfish Prematurational Full-Grown Ovarian Follicles

The present study examines the effects of mammalian insulin and insulin-like growth factor-1 (IGF-I) on steroid production by goldfish vitellogenic and prematurational full-grown ovarian follicles in vitro. Insulin (0.4-40 μg/ml) had no effect on its own, but potentiated human chorionic gonadotropin (hCG) and 25-hydroxycholesterol-stimulated testosterone production by prematurational full-grown follicles in both a dose- and time-dependent manner. By comparison, in vitellogenic follicles insulin (4 μg/ml) had no effect on hCG- or 25-hydroxycholesterol-stimulated testosterone and 17β-estradiol production. IGF-I (11-100 ng/ml) neither affected basal nor hCG- and 25-hydroxycholesterol-stimulated testosterone production by vitellogenic or prematurational full-grown follicles. Studies to determine the site(s) of action of insulin showed that insulin had no effect on basal cyclic adenosine 3′.5′-monophosphate (cAMP) generation, but it enhanced hCG-stimulated cAMP and testosterone production by prematurational full-grown follicles. Insulin also enhanced conversion of 25-hydroxycholesterol to testosterone, but had no effect on the metabolism of pregnenolone, suggesting that insulin either enhances mobilization of cholesterol to the mitochondria or increases the activity of the cytochrome P450 side-chain cleavage enzyme. The ability of insulin to enhance hCG and/or 25-hydroxycholesterol-stimulated testosterone production was blocked by the addition of the protein kinase A (PKA) inhibitor H89, which confirmed that these actions of insulin are exerted, at least in part, by the cAMP/PKA pathway. These findings suggest that insulin, but not IGF-I, is capable of participating in the regulation of ovarian steroid biosynthesis through effects at multiple steps within the steroid cascade and that ovarian responsiveness to insulin changes during the course of follicular development in the goldfish. Together, these results provide new insights into the biological action of insulin in the fish ovary.

Differential expression and hormonal regulation of alternatively spliced IGF-I mRNA transcripts in salmon

Salmon have been shown to express alternatively spliced IGF-I mRNA transcripts coding for four different IGF-I prohormones. These transcripts, now designated Ea-1, Ea-2, Ea-3 and Ea-4, differ in size due to the inclusion of additional sequences in the E domain-coding region of the molecule. In this study, the tissue distribution and hormonal regulation of expression of alternatively spliced IGF-I mRNA transcripts were investigated in coho salmon. IGF-I mRNAs were detected by solution hybridization/RNase protection assay in all tissues examined. GH treatment significantly increased hepatic IGF-I mRNA content. Hepatic IGF-I mRNA levels were not influenced by prolactin or somatolactin. Heart, fat, brain, kidney, spleen and ovary IGF-I mRNA levels were not affected by GH, prolactin or somatolactin. Ea-1, Ea-3 and Ea-4 mRNA transcripts were detectable in the liver, and Ea-1 and Ea-3 levels increased dramatically in response to GH treatment, whereas the amount of Ea-4 mRNA was unchanged. Most non-hepatic tissues expressed only the Ea-4 transcript, and expression was not influenced by GH, prolactin or somatolactin. Ea-1 and Ea-3 transcripts were visible in gill samples from fish treated with GH. The ovaries of juvenile fish expressed Ea-1, Ea-2 and Ea-4. The amounts of these transcripts were not changed by gonadotrophin treatment. During smoltification of juvenile coho salmon, liver and gill IGF-I mRNA levels increased with increasing plasma GH and thyroxine concentrations. Muscle, brain and ovary IGF-I mRNA levels were unchanged during this period. These data suggest that the liver is a major site of IGF-I production in response to GH. Heart, fat, brain, kidney, spleen and ovary did not show increased IGF-I mRNA levels in response to GH treatment. GH and prolactin had inconsistent effects on muscle IGF-I mRNA levels. Somatolactin and a gonadotrophin preparation did not stimulate IGF-I expression in tissues of juvenile fish. Differences in tissue GH responsiveness can be partially explained by the expression of alternatively spliced IGF-I mRNAs. Of the four hepatic IGF-I mRNA transcripts, Ea-1 and Ea-3 are GH-responsive, while Ea-2 and Ea-4 are not. Most non-hepatic tissues express only the Ea-4 transcript, and IGF-I mRNA levels do not increase after GH treatment. The increased IGF-I mRNA levels observed in gill tissue during smoltification suggest that other factors, in addition to GH, may regulate IGF-I expression.(ABSTRACT TRUNCATED AT 400 WORDS)

Ovarian melanotropic peptides and adaptation in two teleostean species: Sparus aurata L. and Dicentrarchus labrax L.

The ovarian tissue of Dicentrarchus labrax and Sparus aurata displays two immunoreactive peaks that correspond to the elution time of human des-acetyl α-MSH [ACTH(1–13)-amide] and human α-MSH. In view of the close identity between the primary structure of fish and human α-MSH, these data demonstrate that two MSH-related peptides are present both in sea bream and sea bass ovary. α-MSH-like immunoreactivity was found within both granulosa and thecal layers of mature follicles, as well as in the cytoplasm of oogonia of sea bream and sea bass ovary. Gonadal content of ACTH(1–13)-amide and α-MSH display differences with regard to season, showing the highest peptide levels in reproductive animals. Moreover, the α-MSH content is significantly higher in the ovary of fish farm animals, whereas that of ACTH(1–13)-amide prevails in wild fish ovary.

Mycobacterium infection in pejerrey, Odonthestes bonariensis Cuvier &amp; Valenciennes

Abstract. Mycobacterium infection was found in pejerrey, Odonthestes bonariensis Cuvier &amp; Valenciennes, with and without saprolegniasis, in Japan. Many typical focal mycobacterial granulomas were found in the kidney, spleen, liver and pancreas, but they were not found in lateral musculature at sites of fungal infection, or in the intestine, ovary, heart and gills of infected fish. The isolated bacterium was photochromogenic and was identified as a rapidly growing species of the genus Mycobacterium.

Effects of malathion on steroidogenesis and sex reversal in Monopterus albus

Monopterus albus in their female phase were exposed to Malathion at a concentration of either 9 ppm for four weeks to study the acute effects on steroidogenesis or 3 ppm for seven months to study the chronic effects on the process of sex reversal. Gonadal tissue obtained from Malathion-exposed fish showed a lower rate of in-vitro testosterone and estradiol production than controls. Addition of homologous pituitary extract or human chorionic gonadotrophin to the medium could partly overcome this inhibitory effect of Malathion on steroid production. Aromatase activity (assessed indirectly by measuring the conversion of exogenous testosterone to estradiol) was found to be significantly lower in the ovaries of Malathion-exposed fish. However, since the production of testosterone by the ovarian follicles of exposed fish was lower than that of controls, Malathion may also be interfering with biosynthetic steps prior to testosterone formation. Long-term treatment of females with Malathion resulted in massive morphological damage to the gonads. The gonads of these fish were filled with degenerated testicular lobules and atretic oocytes. Moreover, the Malathion-exposed group had a lower number of functional intersexes and males after seven months of exposure than controls.

EFFECTS OF THE HEAVY METAL, ZINC, ON THE FRESHWATER FISH TILAPIA NILOTICA L.

Gills, gonads, and blood of Tilapia nilotica exposed to different concentrations of zinc sulfate (ZnSO4. 7H2O) exhibited histological effects. Gills of posthatch larvae exposed chronically for 21 days to 2 ppm zinc sulfate and fingerlings to 10 ppm sublethal zinc concentrations exhibited hyperplasia that resulted in fusion of adjacent secondary gill lamellae. The same effects were observed in 4-hour short-term exposure to 30 ppm lethal dose. Posthatch larvae subjected to 2 and 5 ppm sublethal levels of zinc for 30 days retained undifferentiated gonads with differentiation with oogonial proliferation. Ovaries of control fish demonstrated healthy oocyte growth and other normal histological features after 57 days. In contrast, ovaries in treated groups exhibited excessive amounts of connective tissue, hyperemia and markedly reduced oocyte number. Oocytes had wavy irregular surface outlines. Deviation from normal was observed to be dose dependent. In juvenile tilapia, spermatogenesis was observed in control testes. Testes of zinc-exposed fish, on the other hand, remained immature. Hyperemia was markedly pronounced in both testes and ovary after 90 days exposure to zinc. Blood of Tilapia nilotica fingerlings exposed to sublethal concentrations of 2, 5, and 10 ppm zinc for 30, 60, and 90 days exhibited anisocytosis and poikilocytosis. There was an increase in hematocrit values in zinc-reared fish which, however, reverted to control/near control levels at day 90. Hemoglobin values were inversely proportional to the level of zinc in the rearing water. The marked reduction in hemoglobin values in fish reared at the higher zinc concentrations of 5 and 10 ppm suggests the development of some degree of anemia which is also supported by the observations of anisocytosis and poikilocytosis.

Impact of sublethal concentrations of pollutants in the Budha nallah brook on ovarian recrudescence in Indian catfish,heteropneustes fossilis(B1.)‐IV

The effect of prolonged (60 days) exposure of sublethal (25%, 50%) concentrations (v/v) of the polluted Budha Nallah water on ovarian recrudescence and fecundity in Heteropneustes fossils was studied. The process of ovarian recrudescence was significantly retarded as evidenced by the low ovarian weights and the low occurrence of the vitellogenic (Stage II) and the yolky (stage III) oocytes in the ovaries of treated fish. A high occurrence of atretic oocytes was also noticed in the treated fish ovaries. The fecundity was also significantly low in Budha Nallah water exposed fish. Further, it was recorded that the magnitude of the effect on different parameters mentioned above was influenced by the concentration of the Budha Nallah water to which the fish was exposed.

Reproductive biology and early life history of the marine teleost Platycephalus speculator Klunzinger (Platycephalidae) in a temperate Australian estuary

A description is given of the seasonal trends exhibited by gonadosomatic indices, gonadal maturation and oocyte diameters of different age classes of the flathead, Platycephalus speculator, in Wilson Inlet, a seasonally closed estuary on the south coast of Western Australia. These data indicate that, although sexual maturity is attained by the vast majority of males at the end of the first year, it is delayed for a further year in females. Breeding occurs predominantly during the summer and early autumn (December to March). The presence of late stage eggs and preflexion larvae between January and March of 1988, when a sand bar was present across the mouth of the inlet channel, demonstrates that this marine species spawns in the estuary. Spawning also occurred within the estuary in the following year, even though the estuary mouth was open during the breeding period. Although P. speculator typically spawns at sea, spawning in Wilson Inlet takes place at salinities less than 30%, i.e. below full strength sea water. The distribution of oocyte diameters and the presence of mature eggs and post‐ovulatory follicles in the ovaries of many fish indicate that P. speculator spawns more than once in a breeding season. Late stage eggs of P. speculator are pelagic, ca 0.8 mm in diameter and possess embryos with an unpigmented yolk sac containing a single, pigmented oil globule. The larvae are pelagic and characterized by a relatively large and wide head bearing a series of spines, a moderately long gut, an elongated and compressed tail, large fan‐shaped pectoral fins and 25 or 26 myomeres. Flexion of the notochord occurs between 5 and 7 mm and settlement takes place at approximately 13 mm.

Pesticide-induced atresia in ovary of a fresh water fish, Colisa lalia (Hamilton-Buchanan).

Pesticide-induced atresia in ovary of a fresh water fish, Colisa lalia (Hamilton-Buchanan).

44] Overview of toxins and drugs as tools to study excitable membrane ion channels: II. Transmitter-activated channels

Publisher Summary This chapter discusses the mechanisms of action of toxins and drugs to study the excitable membrane channels. Many chemicals are known to act on voltage-activated sodium channels, and several of them are employed as useful tools in the laboratory because of their specific or unique actions on ion channels. Chemicals acting on sodium channels may be classified into two large groups—namely, blockers and modulators. Tetrodotoxin (TTX) is a potent neurotoxin contained in the ovary and fiver of puffer fish, while saxitoxin (STX) is contained in the toxic Alaska butter clam Saxidoma giganteus, but the toxin actually derives from the dinoflagellate Gonyaulax catanella. Both TTX and STX exert an identical effect on the nerve membrane. Procaine and cocaine are found to block both sodium and potassium channels of squid giant axons. The enzyme pronase is a blocker of sodium channel inactivation, and is extensively to analyze the kinetics of sodium channel activation.

43] Overview of toxins and drugs as tools to study excitable membrane ion channels: I. Voltage-activated channels

This chapter discusses the mechanisms of action of toxins and drugs to study the excitable membrane channels. Many chemicals are known to act on voltage-activated sodium channels, and several of them are employed as useful tools in the laboratory because of their specific or unique actions on ion channels. Chemicals acting on sodium channels may be classified into two large groups—namely, blockers and modulators. Tetrodotoxin (TTX) is a potent neurotoxin contained in the ovary and fiver of puffer fish, while saxitoxin (STX) is contained in the toxic Alaska butter clam Saxidoma giganteus, but the toxin actually derives from the dinoflagellate Gonyaulax catanella. Both TTX and STX exert an identical effect on the nerve membrane. Procaine and cocaine are found to block both sodium and potassium channels of squid giant axons. The enzyme pronase is a blocker of sodium channel inactivation, and is extensively to analyze the kinetics of sodium channel activation.