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  • 1
    Electronic Resource
    Electronic Resource
    Cortisol stimulates intestinal fluid uptake in Atlantic salmon (Salmo salar) in the post-smolt stage (1994)
    Springer
    Fish physiology and biochemistry 13 (1994), S. 183-190 
    Details
    ISSN: 1573-5168
    Keywords: cortisol implants ; intestinal transport ; Atlantic salmon ; Salmo salar ; parr-smolt transformation ; gill Na+,K+-ATPase activity ; seawater adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The fluid uptake rate of the posterior intestine of salmonids increases during the parr-smolt transformation. Intestinal fluid uptake in post-smolt Atlantic salmon was investigated after treatment with cortisol and growth hormone (GH), alone or together. Two replicate experiments were conducted in August 1991 and August 1992. Cortisol was emulsified in vegetable shortening and vegetable oil (1:1) and implanted into the peritoneal cavity. GH was administered as intraperitoneal injections in a saline vehicle on days 0 and 2. On days 5 and 6, plasma cortisol levels, gill Na+,K+-ATPase activity, andin vitro measurements of fluid transport rate (Jv) across the posterior intestine were measured. Implants of cortisol elevated the plasma cortisol levels within a physiological range, and resulted in elevated gill Na+,K+-ATPase activity, as expected. The fluid uptake rate across the posterior intestine was roughly doubled by cortisol treatment. GH treatment did not affect intestinal fluid transport, gill Na+,K+-ATPase activity, or plasma cortisol concentrations. The seawater-adapting increase in the rate of fluid uptake by the posterior intestine of smolting salmon is probably stimulated by elevated plasma cortisol concentrations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00004356
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  • 2
    Electronic Resource
    Electronic Resource
    Effect of triiodothyronine on the growth and survival of larval striped bass (Morone saxatilis) (1996)
    Springer
    Fish physiology and biochemistry 15 (1996), S. 57-64 
    Details
    ISSN: 1573-5168
    Keywords: striped bass ; Morone saxatilis ; triiodothyronine ; growth ; survival
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This study was carried out to test the effect of triiodothyronine (T3) on the growth and survival of larval striped bass (Morone saxatilis). Growth and survival of striped bass held in 5 ppt seawater and treated with various doses of T3 were measured beginning at 5 and 16 days after hatching. Body content of T3 was measured by radioimmunoassay. T3 dissolved in the 5 ppt seawater was taken up by larval striped bass in a dose-dependent manner, and affected the growth and survival of the fish. At 5 days after hatching, T3 at 100 ng ml−1 and 50 ng ml−1 retarded the growth of larval striped bass and caused a lower survival rate than T3 at 25 ng ml−1 or the control treatment. At 16 days after hatching, T3 at 100 ng ml−1 retarded the growth of larval fish and caused a higher mortality. T3 at 10 ng ml−1 and 1 ng ml−1 did not show any effect on either survival or growth. Body content of T3 returns to control levels within days following end of treatment. The results indicate that exogenous T3 can be detrimental to the growth and survival of larval striped bass.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01874838
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  • 3
    Electronic Resource
    Electronic Resource
    Unequal activities of the two tilapia prolactins in the whole-animal transepithelial potential bioassay using the red eft (1989)
    Springer
    Fish physiology and biochemistry 7 (1989), S. 119-124 
    Details
    ISSN: 1573-5168
    Keywords: prolactin ; bioassay ; hormone variants ; transepithelial potential ; tilapia ; Oreochromis mossambicus ; red eft ; Notophthalmus viridescens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The cichlid fish tilapia (Oreochromis mossambicus) produces two forms of prolactin (tPRL177 and tPRL188) at equal rates. The primary sequences of this prolactin pair share only 69% identity. In these experiments, the whole-animal transepithelial potential (TEP) in the eft stage of the red-spotted newt (Notophthalmus viridescens) was measured in response to two injections totaling about 2 μg of tPRL177, tPRL188, ovine PRL, or tilapia growth hormone (tGH), or distilled water (5 μL/injection). This investigation was undertaken in order to locate prolactin receptors which discriminate between the two molecular forms of tilapia prolactin. The salamandrid integumental bioassay for prolactin was found to respond to tPRL177 as it does to ovine PRL. The more mainline tPRL188 was without effect at this dose and thus behaved more similarly to growth hormone (tilapia and ungulate) in this bioassay. The suspected magnitude of differences in the molecular surface characteristics between the two prolactins seem to be adequate to allow the binding of tPRL177 and to hinder the binding of tPRL188 to prolactin specific receptors in eft epithelial tissues.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00004697
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  • 4
    Electronic Resource
    Electronic Resource
    Salinity and temperature effects on whole-animal thyroid hormone levels in larval and juvenile striped bass, Morone saxatilis (1990)
    Springer
    Fish physiology and biochemistry 8 (1990), S. 507-514 
    Details
    ISSN: 1573-5168
    Keywords: thyroid hormones ; striped bass ; seawater adaptation ; larval fishes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Whole-animal thyroxine (T4) and 3,5,3′-triiodothyronine (T3) levels were measured in larval and juvenile striped bass, Morone saxatilis, reared for 10 days at one of three levels of salinity (equivalent to fresh water (FW), one-third seawater (1/3 SW), and seawater (SW) and two temperatures (15°C and 20°C). The striped bass were pre-metamorphic larvae, metamorphic larvae or juveniles. The short-term effects of seawater on plasma T4 levels of juvenile striped bass were also measured. Higher salinities increased T4 levels in premetamorphic larvae. In metamorphic larvae, SW and 1/3 SW increased T4 levels and SW increased T3 levels at 20°C. This response was eliminated in those at 15°C. Whole-animal thyroid hormone content was unaffected by salinity or temperature in juvenile striped bass, although significant fluctuations in plasma T4 levels occurred in those transferred to 1/3 SW and SW. The thyroid axis of striped bass responds to salinity and temperature as early as in the pre-metamorphic stage. Thyroid hormones may mediate the beneficial effects of salinity on larval striped bass growth and survival.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00003408
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  • 5
    Electronic Resource
    Electronic Resource
    Changes in gonadal hormones during oocyte development in the striped bass,Morone saxatilis (1991)
    Springer
    Fish physiology and biochemistry 9 (1991), S. 51-62 
    Details
    ISSN: 1573-5168
    Keywords: striped bass ; reproduction ; steroid hormones ; oocyte development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Wild striped bass,Morone saxatilis, were collected from coastal waters and spawning areas to describe the endocrine correlates of oocyte development in non-captive, migratory fish. The fish were classified according to their most advanced oocytes. Serum levels of estradiol (E2), testosterone (T) and 17α-20β-dihydroxyprogesterone (DHP) were measured by radioimmunoassay (RIA). Females in the primary growth phase and early secondary growth phase (pre-vitellogenic) had low levels of plasma steroids, ovarian lipid content and gonadosomatic indices (GSIs). Significant increases in E2, T, ovarian lipid content and GSIs occurred during the vitellogenic phase. Maximum levels of all reproductive parameters were found in prespawning fish sampled in the Hudson River. Mean levels of E2, T, ovarian lipids and GSIs for these fish were 2.0±0.5 ng/ml, 3.0±0.3 ng/ml, 24±1 mg/g, and 5.6±0.3% (mean±SEM), respectively. In fish induced to spawn with human chorionic gonadotropin (HCG), DHP levels (1.9±0.4 ng/ml) were significantly elevated. Similar levels were found in two fish captured during the spawning season, suggesting that DHP may serve as the maturation-inducing steroid in this species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01987611
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  • 6
    Electronic Resource
    Electronic Resource
    Vitellogenin in tilapia (Oreochromis mossambicus): Induction of two forms by estradiol, quantification in plasma and characterization in oocyte extract (1993)
    Springer
    Fish physiology and biochemistry 12 (1993), S. 171-182 
    Details
    ISSN: 1573-5168
    Keywords: tilapia (Oreochromis mossambicus) ; vitellogenin ; ELISA ; yolk proteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two forms of vitellogenin were isolated by DEAE agarose ion-exchange chromatography from plasma of the tilapia, Oreochromis mossambicus. The monomers have apparent molecular masses of 200 and 130 kDa, as indicated by SDS-polyacrylamide gel electrophoresis (SDS-PAGE), and a total amount of phosphorus of 1.7 and 0.1%, respectively. Antibodies specific to the two forms, designated tVTG-200 and tVTG-130, were generated in rabbits and used to develop enzyme-linked immunosorbent assays (ELISAs) and in Western blot analyses of plasma and oocyte extract. SDS-PAGE of the oocyte extract showed a major protein band at 106.6, minor bands at 26.6, 24.2, and 23.7 kDa, and very faint bands at 83.4 and 17.5 kDa. Western blots of the oocyte extract revealed that the antiserum to tVTG-200 recognized strongly the protein bands at 24.2 and 23.7 kDa, and less strongly the bands at 25.1 and 22.6 kDa, whereas the antiserum to tVTG-130 recognized mainly the protein band at 106.6 kDa. The presence of both VTGs in untreated male tilapia was detected with the ELISAs using relatively high plasma volumes. Their presence in males was confirmed by VTG-like immunoreactive materials eluting from the ion-exchange column at the same positions as tVTG-200 and tVTG-130. The concentrations of the VTGs in males were several orders of magnitude lower than in vitellogenic females. Treatment of male tilapia with estradiol-17β (E2) induced both VTGs within 24h. After 7 days, tVTG-130 reached a maximum concentration in plasma, whereas tVTG-200 continued to increase. Our findings demonstrate that the two vitellogenins are biochemically distinct, possibly differentially regulated, and made by both sexes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00004365
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  • 7
    Electronic Resource
    Electronic Resource
    Changes in intestinal fluid transport in Atlantic salmon (Salmo salar L) during parr-smolt transformation (1993)
    Springer
    Fish physiology and biochemistry 12 (1993), S. 193-202 
    Details
    ISSN: 1573-5168
    Keywords: intestinal fluid transport ; parr-smolt transformation ; seawater adaptation ; Atlantic salmon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We examined changes in fluid transport by the intestine of Atlantic salmon (Salmo salar L) undergoing parrsmolt transformation during springtime. In vitro measurements of fluid transport rate (Jv) across non-everted middle and posterior intestinal sac preparations were made in late April and early June 1990 and from February through June 1991 for juvenile smolting fish. Intestinal Jv was also compared between parr- and smolt-stage salmon in both years. To evaluate the osmoregulatory role of the intestine, Jv was measured for smolts adapted to seawater and their cohorts remaining in fresh water. The middle intestine of smolting fish underwent a significant decrease in fluid transport during the springtime, while posterior intestinal Jv significantly increased. Parr-stage fish decreased Jv in the middle intestine during springtime similar to smolts. However, the posterior intestinal Jv of smolts showed a significant increase over the parr around the peak smolt period in both years. Seawater-adapted smolts generally exhibited posterior intestinal Jv approximately double that of freshwater cohorts. A decrease over time shown for the middle intestine, together with the increased Jv in the posterior intestine preceding and after seawater entry, suggests the development of a functional regionalization during parr-smolt transformation, with the posterior intestine taking on increased importance in osmoregulation in seawater.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00004367
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  • 8
    Electronic Resource
    Electronic Resource
    Ultrastructural analysis of the developing follicle during early vitellogenesis in tilapia, Oreochromis niloticus, with special reference to the steroid-producing cells (1993)
    Springer
    Cell & tissue research 272 (1993), S. 33-39 
    Details
    ISSN: 1432-0878
    Keywords: Ovary ; Folliculogenesis ; Interstitial cell ; Estradiol ; Testosterone ; Oreochromis niloticus (Teleostei)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The development and distribution of steroid producing cells (SPCs) in the ovary of tilapia have been studied by light and electron microscopy. At 40–50 d after hatching, these cells are seen only in the vicinity of blood vessels; there are no SPCs in the interstitial region, nor in the thecal layer enclosing young oocytes at the peri-nucleolus stage. By 70–80 d after hatching, the number of SPCs in the area near blood vessels has increased, and the capillaries have spread among the developing peri-nucleolar stage oocytes, and into the ovarian tunica. Clusters of SPCs have also migrated into the interstitial region and into the tunica along with these capillaries. In the ovary 100 d after hatching, some SPCs can be found in the thecal layer enclosing vitellogenic oocytes. Moreover, masses of SPCs can now be observed infiltrating the thecal layer of the oocyte. Serum testosterone (T) and estradiol-17β (E2) levels at 40–70 d after hatching, are low (T, 0.75–1.10 ng/ml, E2, 0.36–1.08 ng/ml), but at 100 d, plasma E2, but not T, is elevated (T, 1.95 ng/ml, E2, 4.65 ng/ml). These results suggest that SPCs appearing in the vicinity of blood vessels move into the interstitial region between oocytes, and finally enclose the oocytes at an early vitellogenic stage. It is interesting to note that the enclosure of oocytes by SPCs coincides with significant increases in E2 production.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00323568
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  • 9
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    Ultrastructural analysis of the developing follicle during early vitellogenesis in tilapia, Oreochromis niloticus, with special reference to the steroid-producing cells (1993)
    Springer
    Details
    Publication Date: 1993-04-01
    Print ISSN: 0302-766X
    Electronic ISSN: 1432-0878
    Topics: Biology , Medicine
    Published by Springer
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