Roles of prolactin in salmonids.
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Animals↗
Biomedical subjects
P Prunet
Publications and source records attributed to P Prunet.
Accessory cells in the gill epithelium of the freshwater rainbow trout Salmo gairdneri.
Two types of mitochondria-rich cells were identified in the gill epithelium of the freshwater-adapted rainbow trout, Salmo gairdneri, after selective impregnation of their tubular system with reduced osmium. A first type consisted of large cells with a poorly developed and loosely anastomosed tubular system; thus, that resembled the chloride cells commonly encountered in the gill epithelium of freshwater-adapted euryhaline fishes. A second type comprised smaller cells with an extensively developed and tightly anastomosed tubular system. These never reached the basal lamina of the gill epithelium and were adjacent to chloride cells, to which they were linked by shallow apical junctions (100-200 nm); thus, they resembled accessory cells, which are currently found in the gill epithelium of seawater-adapted fishes but are usually lacking in freshwater living fishes. Transfer of the freshwater-adapted trout into seawater induced the proliferation of the tubular system in the chloride cells and the formation of lateral plasma membrane interdigitations between accessory cells and the apical portion of the chloride cells. The length of the apical junction sealing off this extended intercellular space was reduced to 20-50 nm. The tubular system of the accessory cells was not modified. The extension of the tubular system in the chloride cells of the seawater-adapted fishes indicated that, as in most euryhaline fishes, these cells have a role in the adaptation of the rainbow trout to seawater. In contrast, the function of the presumptive accessory cells in freshwater trout remains to be established.
Animals↗
Smoltification and seawater adaptation in coho salmon (Oncorhynchus kisutch): plasma prolactin, growth hormone, thyroid hormones, and cortisol.
The status of circulating growth hormone and prolactin during the parr-smolt transformation and during seawater adaptation of coho salmon (Oncorhynchus kisutch) was investigated in relation to changes in plasma levels of thyroxine, triiodothyronine, and cortisol, and in hypoosmoregulatory ability. Sampling (biweekly or monthly) occurred between early February and October. When peak hypoosmoregulatory ability was achieved (mid-April), one group of fish was acclimated to seawater over a period of 18 hr and was sampled 1, 3, and 7 days after the introduction of fish to seawater and biweekly thereafter. Plasma prolactin levels rose steadily from the first sampling date to a peak of 15 ng/ml in early April, declined rapidly, and remained low until June when a second increase occurred. Prolactin declined to 2 ng/ml within 1 day of the beginning of seawater adaptation. Growth hormone increased twofold from February to late March, and achieved plateau levels of 20 ng/ml in the period from mid-April to July and then gradually declined to 10 ng/ml in September and October. Plasma levels of growth hormone in seawater-acclimated fish were similar to those of freshwater coho, but with larger fluctuations; no increase was apparent during the first week of seawater acclimation. Plasma cortisol and plasma triiodothyronine increased at the same time as plasma growth hormone; increases in plasma thyroxine occurred later. In general, both growth hormone and cortisol levels were elevated when hypoosmoregulatory ability was high. Conversely, prolactin levels generally showed a negative relationship with hypoosmoregulatory ability.
Acclimatization↗
Smoltification and seawater adaptation in Atlantic salmon (Salmo salar): plasma prolactin, growth hormone, and thyroid hormones.
To obtain more information on the role of prolactin and growth hormone during the parr-smolt transformation of Atlantic salmon, a population of fish in fresh water was sampled from January to June during two consecutive years. Gill Na+,K+-ATPase activity increased steadily during smoltification and a plasma thyroxine peak was observed 2-3 weeks before the gill Na+,K+-ATPase peak. On the basis of these two parameters, smoltification was considered complete in our populations in April 1985 and May 1986. Two peaks in plasma growth hormone levels occurred in 1986, one in mid-April and the second in mid-May. In both cases, these peaks coincided with a peak in plasma triiodothyronine and preceded the thyroxine peak by 1-2 weeks. Moreover, the second peak which lasted for 1 month coincided with maximal gill Na+,K+-ATPase activity. A decrease in plasma prolactin levels was observed during smoltification of Atlantic salmon in 2 consecutive years. During this period of decreasing and low plasma prolactin levels, gill Na+,K+-ATPase activity increased to its highest values. Atlantic salmon smolts were also directly transferred into seawater. After 2 days or more in seawater, plasma prolactin levels were not significantly different from those on Day 0, whereas in fresh water they showed large fluctuations. All these data indicate that growth hormone may play an important role in the development of hypoosmoregulatory activity. Increased hypoosmoregulatory ability also appears to be associated with low prolactin levels.
Acclimatization↗
Rainbow trout prolactin cDNA cloning in Escherichia coli.
We describe the isolation and characterization of a cDNA for trout prolactin (tPrl). An extensive analysis of tPrl recombinant clones by restriction analysis and sequencing revealed the presence of only one form of tPrl mRNA. The deduced protein sequence consists of 210 amino acids, including a signal peptide of 23 amino acids. The amino acid sequence of the mature protein is compared among teleosts and mammals, showing two domains of strong similarity that may be involved in biological activity.
Amino Acid Sequence↗
Tilapia prolactin: molecular cloning of two cDNAs and expression in Escherichia coli.
We have isolated cDNA clones encoding tilapia prolactin (tiPRL) from a cDNA library prepared from tilapia (Oreochromis niloticus) anterior pituitary glands. A trout PRL cDNA fragment was used as hybridization probe to select the recombinant plasmids carrying the tiPRL coding sequence. Two types of PRL cDNA were isolated and their complete nucleotide sequence determined. The larger cDNA (tiPRL-I) codes for a polypeptide of 212 amino acids, including a putative signal sequence of 24 amino acids, and contains a 3' untranslated region of 787 bp. The second prolactin cDNA (tiPRL-II) encodes a polypeptide of 200 amino acids, including a presumptive signal peptide of 23 amino acids, and contains a noncoding region of 512 bp. tiPRL-I and tiPRL-II cDNA sequences are 81% similar, whereas the encoded proteins share 69% amino acid identity at optimal alignment. Mature tiPRL-I was efficiently expressed in Escherichia coli carrying a plasmid in which the tiPRL-I cDNA was under the control of the phi 10 promoter of T7 bacteriophage. The new recombinant protein representing about 45% of the total cellular proteins was found in inclusion bodies and cross-reacted with salmon PRL antiserum.
Amino Acid Sequence↗
Ultrastructural features of chloride cells in the gill epithelium of the Atlantic salmon, Salmo salar, and their modifications during smoltification.
To elucidate the ultrastructural modifications of the gill epithelium during smoltification, gills of the Atlantic salmon (Salmo salar) were examined by electron microscopy at three stages of this process, which were defined as follows: "parrs" were freshwater fish that had not yet started their transformation; "freshwater smolts" were freshwater fish that were ready to enter seawater; and "seawater smolts" were smolts that had been transferred from fresh water and maintained for 4 days in seawater (35%). In the gill epithelium of parrs, there were two types of chloride cells. The large chloride cells contained deeply stained mitochondria and numerous apical, irregular, dense, membrane-bound bodies that formed 77% of the chloride cell population and were distinguished easily from small chloride cells that have distinctly paler mitochondria and no dense bodies in their apical cytoplasm. In freshwater smolts, the large chloride cells formed 95% of the chloride-cell population. In contrast to the small chloride cells that were not modified, they almost doubled in size. Their tubular system developed extensively to form a tight network with regular meshes significantly smaller than those observed in parr chloride cells. Forty percent of the large chloride cells were associated with a new type of cell, the accessory cell, to which they were bound by shallow apical junctions. Half of these accessory cells were not seen to be in contact with the external medium. In seawater smolts, 80% of the large chloride cells were associated with accessory cells. Most accessory cells reached the external medium and sent numerous cytoplasmic interdigitations within the apical portion of the adjacent chloride cells. As a result, a section through the apical portion of the chloride cells and their associated accessory cells revealed a mosaic of interlocked cell processes bound together by an extended, shallow apical junction. It was concluded that the Atlantic salmon develops in fresh water most of the ultrastructural modifications of the gill epithelium which in most euryhaline fish are triggered by exposure to seawater. The effective transfer into seawater would act only as a final stimulus to achieve some adequacy between the freshwater smolt and its new environment.
Animals↗
Effect of osmotic pressure on prolactin release in rainbow trout: in vitro studies.
To investigate a possible effect of osmotic pressure on prolactin (PRL) release in rainbow trout, we developed a technique for in vitro perifusion of trout pituitaries. Changes in osmotic pressure similar to those observed in fish plasma during transfer experiments did not induce significant modifications of PRL release. In contrast, high-amplitude variation of osmotic pressure resulted in clear modifications of PRL secretion: hyperosmotic medium caused a reduction in PRL release, while infusion of hyposmotic medium induced a transitory increase in PRL release. By using different concentrations of mannitol, we found that the modifications of prolactin secretion could not be ascribed to alterations of the ionic composition of the medium but actually resulted from variations in the osmotic pressure of the incubation medium. In further experiments osmotic pressure was decreased from 300 to 220 mOsm/kg or from 400 to 300 mOsm/kg; a similar transitory increase in PRL release was observed. Measurement of gonadotropin (GtH) in the perifusion effluent medium showed that PRL and GtH secretion followed similar patterns. Thus, our results suggest a possible mechanical effect of wide changes in osmotic pressure on pituitary cell membranes. These data indicate that the rainbow trout differs notably from nonsalmonid teleost species thus far studied in the lack of sensitivity of its PRL cells to osmotic pressure.
Animals↗
Plasma and pituitary prolactin levels in rainbow trout during adaptation to different salinities.
The development of a highly specific radioimmunoassay for salmonid prolactin (PRL) using chinook salmon PRL allowed us to study plasma and pituitary PRL profiles in large sedentary rainbow trout (Salmo gairdneri) transferred from fresh water to seawater and vice versa. Plasma osmotic pressure and chloride levels were also measured for 3 weeks following change of salinity. Within 1 day after transfer to full seawater we observed a plasma PRL decrease, which stayed significantly lower (3-5 ng/ml) than the fresh water control group (10-15 ng/ml) during the entire experiment. Pituitary PRL content showed an initial abrupt increase, but after 3 weeks in seawater pituitary PRL content had decreased to the same level as in the fresh water control group. On the contrary, transfer from seawater to fresh water was followed within 1 day by a rise in plasma PRL levels, which stayed high (10-15 ng/ml) after 3 weeks in fresh water. Simultaneously, pituitary PRL content decreased significantly. These results may indicate an important role of PRL in fresh water adaptation of sedentary rainbow trout.
Acclimatization↗
Development and validation of a salmon prolactin radioimmunoassay.
A highly specific radioimmunoassay (RIA) for the measurement of prolactin (PRL) in the plasma and pituitary of salmonid fishes was developed using a rabbit antiserum to chinook salmon (Oncorhynchus tschawytscha) PRL. The PRLs purified from chinook salmon and chum salmon (O. keta) pituitaries showed exactly the same competitive inhibition curves in the RIA, regardless of iodination of either hormone. The displacement curves for pituitary extracts and plasma from several salmonids, including chum, coho, and amago salmon, rainbow trout, and Japanese charr, were parallel to the salmon PRL standard, whereas those from the eel, goldfish, carp, and tilapia showed negligible cross-reactivity. Negligible cross-reactivity was also seen with plasma from hypophysectomized rainbow trout or coho salmon. None of the mammalian PRL or growth hormone (GH) preparations, bullfrog PRL, or presumptive chum salmon "gonadotropin" and eel "PRL" cross-reacted in the PRL RIA. Presumptive chum salmon GH showed less than 0.05% cross-reactivity. The RIA sensitivity was less than 0.1 ng of the salmon PRL standard per milliliter. The immunoreactive plasma PRL levels in mature chum salmon were below 1 ng/ml in seawater. The plasma PRL in females increased to about 8 ng/ml 1 day after transfer to fresh water, and high levels (2-4 ng/ml) were maintained during 3-7 days after the transfer. In contrast, when males were transferred to fresh water, an increase in plasma PRL was seen only 1 day after the transfer. A significant decrease in plasma osmolality was observed in both males and females after transfer to fresh water. No change was observed either in plasma PRL or osmolality, when fish were transferred from seawater to seawater.
Animals↗
Purification and biological characterization of chinook salmon prolactin.
Prolactin from chinook salmon pituitaries was purified by acid acetone extraction, saline precipitation, chromatofocusing, and gel filtration. This procedure allowed us to recover highly purified prolactin as demonstrated by the presence of a single NH2-terminal amino acid and a single band in sodium dodecyl sulfate gel electrophoresis. Chinook salmon prolactin appeared to be a basic protein of 22,500 molecular weight. Throughout the purification, prolactin bioactivity was followed by radioreceptor assay for lactogenic hormones. The prolactin character of the purified protein was established by its lactogenic activity in the rabbit mammary gland in vitro and its sodium-retaining activity in hypophysectomized Fundulus heteroclitus.
Amino Acid Sequence↗
Bioassay for salmon prolactin using hypophysectomized Fundulus heteroclitus.
A bioassay for salmon prolactin (PRL) is described. This assay which is based on the sodium-retaining action of PRL in the hypophysectomized killifish, Fundulus heteroclitus, has proved to be rapid, sensitive (250 pg PRL per gram of fish), and specific. The procedure has been used to characterize the biological activity of a highly purified PRL from the pituitaries of the chinook salmon, Oncorhynchus tschawytscha, and a similar PRL isolated (by acid buffer polyacrylamide disc gel electrophoresis) from pituitaries of coho salmon (O. kisutch) (MW ca. 22,000; isoelectric point greater than 9).
Animals↗
Elimination of serum proteins and potential virus contaminants during hepatitis B vaccine preparation.
As first generation hepatitis B vaccines are derived from human plasma, detailed information is required concerning the elimination of hepatitis B virus and other potential transmissible infectious agents during vaccine preparation. To demonstrate the safety of a hepatitis B vaccine, the efficiency of each of the six main steps used in the preparation process to remove or destroy pathogens was determined for representatives of major groups of animal viruses. Infectivity of all the tested viruses was reduced 10(5)-fold to a factor of 10(9)-fold by the first and last steps, namely PEG fractionation and formalin treatment. The four successive zonal ultracentrifugations decreased virus infectivity by at least 10(7)-fold. Five of these steps tend also to purify the hepatitis B surface antigen (HBsAg) which increases the HBsAg: protein ratio by at least 10(5)-fold. Considering the high degree of purity obtained, checked on each batch, it is concluded that the procedure consistently eliminates any potential virus with a ide safety margin.
Blood Proteins↗
Serial transmission of hepatitis B like non-A, non-B hepatitis and associated markers to chimpanzees successfully immunized against HBV.
In order to demonstrate that the HBV like strain of NANB hepatitis bred true as non-B together with its associated markers, 2 chimpanzees with high titer anti-HBs (45 and 125 AUSAB RU respectively) immunized with the Pasteur HB vaccine received 1 ml IV of a NANB inoculum. Two neighbour captive animal served as controls. The inoculum was the serum of a leukemic patient in remission for over 3 years with NANB chronic active hepatitis which serum contained HBV like particles and was found positive for NANBe Ag and anti-NANBc whereas in the liver typical numerous "SHIMIZU" dense soft edge aggregated intranuclear structures were demonstrated by electron microscopy. After 4 weeks portal inflammation and hepatocyte necrosis with significant aminotransferase elevation lasting for over 10 weeks developed in the 2 infected chimpanzees. No change in anti-HBs titer was seen and HBs, HBc, HBe Ag and/or AB could neither be detected in serum by RIA nor in liver by immunofluorescence during the 6 month follow up period. By contrast NANBc Ag became clearly demonstrable by immunofluorescence in the liver nuclei together with anti-NANBc in the serum after the 6th week and both persisted for over 4 months. Double unit structures similar to those of NANB/F strain were demonstrable in the cytoplasm at the acute phase. None of these changes was seen in the two control animals. Inoculation of the acute phase serum in the 2 previous control animals was again followed by the same sequence of events. Hybridization studies with HBV DNA of liver biopsies of infected chimps were negative.
Animals↗
[Production of rabies vaccine in animal diploid cells].
Modalities for production of inactivated rabies vaccine derived from diploid hamster cell cultures are reported. The inactivated concentrated virus, purified by zonal centrifugation, is utilised for the preparation of vaccines destinated to carnivores, either in the form of monovalent vaccine or associated with distemper and canine contagious hepatitis vaccines. The inactivated concentrated virus is utilised for the preparation of bovine vaccine. The procedure is compatible with industrial production. The results concerning safety and potency tests of the experimental lots are presented.
Animals↗
[New technics and antirabies vaccination].
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Animals↗
Randomised placebo-controlled trial of hepatitis B surface antigen vaccine in french haemodialysis units: II, Haemodialysis patients.
A vaccine against hepatitis B surface antigen (Institut Pasteur Production) was assessed in 138 haemodialysis patients in a placebo-controlled randomised double-blind trial. In an interim analysis, hepatitis B infections were observed in 21% of the vaccine group and 45% of the placebo group (p less than 0.02). 2 of the infections in the vaccine group and 12 of the infections in the placebo group occurred after the third injection. 60% of the vaccine recipients had an immune response. 4 months after the first injection the mean titre of anti-HBs was 120 mlU/ml.
Adult↗
Randomised placebo-controlled trial of hepatitis B surface antigen vaccine in French haemodialysis units: I, Medical staff.
A vaccine against hepatitis B surface antigen (Institut Pasteur Production) was assessed in staff members from forty-eight French haemodialysis units where the risk of hepatitis B was high. Of 318 subjects who completed the protocol, 164 received three monthly injections of vaccine and 154 received corresponding injections of placebo. Hepatitis B infection was observed in 3.6% of the vaccine group and 12.3% of the placebo group (p less than 0.005). The 6 infections in the vaccine group all arose within 63 days from the first injections, whereas the 19 in the placebo group arose throughout the 12 months of follow-up. The rate of side-effects after injection did not differ in the two groups. 94% of the vaccine recipients had an immune response ( greater than 10 mIU/ml in at least 5 successive specimens). 4 months after the first injection the mean + or - 2 SE peak level of anti-HBs was 2433 + or - 1077 mIU/ml.
Clinical Trials as Topic↗