One-step immunoaffinity purification and partial characterization of hypophyseal growth hormone from the African catfish, Clarias gariepinus (Burchell)

Seasonal and circadian time-dependent dual action of GH on somatic growth and ovarian development in the Asian catfish, Clarias batrachus (Linn.): role of temperature

Effect of growth hormone (GH), injected either at the morning or evening, on the somatic and ovarian development of the Asian catfish, Clarias batrachus was studied during the late quiescence and early recrudescence phase of the reproductive cycle. GH treatment during the late quiescence phase (December-January; 11L: 13D, average water temperature 16.2+/-1 degrees C) failed to exert any impact on the somatic or ovarian development, except that it increased plasma testosterone marginally, and decreased hepatic level of triglycerides (TG); while during the early recrudescence phase (March-April; 12.4L: 11.20D; average water temperature-28.4+/-2 degrees C), GH had significant circadian time-dependent effect on somatic and ovarian development. GH injection at morning stimulated ovarian growth and development, as was evident from the dose-dependent significant increase in ovarian weight, gonadosomatic index, plasma levels of testosterone and estradiol-17beta following GH treatment. The ovarian morphology also revealed the advancement in follicular development in GH treated fish. GH also induced remarkable increase in ovarian levels of TG, free cholesterol (CF) and phospholipids (PL) with concomitant declines in their hepatic levels. However, evening hour GH injection provoked appreciable increase in body weight without having any significant impact on ovarian weight and GSI. Few oocytes in the ovary of evening hour GH treated fish exhibited advanced stages of development, but number of such advanced stage oocytes was significantly much less than the morning hour GH injected fish. Ovarian TG and PL remained unchanged, while their hepatic levels were increased. The temporal synergism between GH and other intrinsic factors regulating body growth and gonadal development may be suggested herewith to be considered prior to administration of GH in fishes. This study has immense practical use in aquaculture.

Independent differentiation of mammotropes and somatotropes in the chicken embryonic pituitary gland. Analysis by cell distribution and attempt to detect somatomammotropes

It has been reported that mammotropes in a rodent pituitary gland are derived from somatotropes via somatomammotropes (SMTs), cells that produce both growth hormone (GH) and prolactin (Prl). However, no studies have been done on the transdifferentiation of somatotropes in the chicken pituitary gland. In this study, in order to determine the origin of mammotropes, we studied detail property of appearance of chicken somatotropes, mammotropes and pit-1 cells and then evaluated the existence of SMTs in the chicken embryonic pituitary gland. Immunohistochemical analysis revealed that GH-immunopositive (GH-ip) cells appeared on embryonic day (E) 14 and were mainly distributed in the caudal lobe, while Prl-immunopositive (Prl-ip) cells appeared in the cephalic lobe of the pituitary gland on E16. In situ hybridization (ISH) and RT-PCR analysis showed that expression of GH and Prl mRNA starts at E12 in the caudal lobe and at E14 in the cephalic lobe respectively. Pit-1 mRNA was first detected on E5 by RT-PCR, and pit-1 mRNA-expressing cells were found in the cephalic lobe on E8. Then with the ontogeny of the chicken, these cells spread into both lobes. Using a double staining method with ISH and immunohistochemistry, we could not detect the existence of SMTs in the chicken embryonic pituitary gland even in the marginal region of either lobe. These results suggest that chicken somatotropes and mammotropes independently appear in different lobes of pituitary gland and that transdifferentiation from somatotropes to mammotropes is not the central route for differentiation of mammotropes in the embryonic chicken pituitary gland.

Immunological and physiological validation of enzyme-linked immunosorbent assay for growth hormone of the Asian catfish, Clarias batrachus

This study describes the development and validation of competitive antigen capture enzyme-linked immunosorbent assay (ELISA) for growth hormone (GH) of the catfish, Clarias batrachus. Isolated GH was characterized first through bioassay, amino acid sequencing, immunoblotting and immunocytochemistry, and then used to raise antibody to develop ELISA. The lowest detection limit of the assay system was 0.17 ng ml(-1), and the standard curve had an ED(50) value of 0.35 ng ml(-1). Repeated determination of GH in a plasma pool exhibited intra- and interassay co-efficient of variation of 8.1% and 7.09% (n=5), respectively. Dose-response inhibition curves resulting from dilutions of plasma and pituitary homogenate of C. batrachus were parallel to the standard curve, while such parallelism in the case of Cyprinus carpio and H. fossilis was absent revealing no cross reaction of them in the present ELISA. In vivo effects of sGnRH, testosterone, 5-HT and morphine on plasma GH were also examined to validate the ELISA physiologically. sGnRH, testosterone and morphine increased, while 5-HT decreased GH level in a dose-dependent manner.

Expression of ayu (Plecoglossus altivelis) Pit-1 in Escherichia coli: its purification and immunohistochemical detection using monoclonal antibody

The pituitary-specific transcription factor Pit-1 belongs to the family of POU-domain proteins and is known to play an important role in the differentiation of pituitary cells. Here we report the complete nucleotide sequence of cDNA encoding Pit-1 from the brackish water fish, ayu (Plecoglossus altivelis). Nucleotide sequence analysis of 1910 bp of ayu Pit-1 cDNA revealed an open reading frame of 1074 bp that encodes a protein of 358 amino acids containing a POU-specific domain, POU homeodomain, and an STA (Ser/Thr-rich activation) transactivation domain. We inserted the coding region of Pit-1 cDNA, obtained by PCR, into a pET-20b(+) plasmid to produce recombinant Pit-1 in Escherichia coli BL21 (DE3) pLysS cells. Upon induction with isopropyl beta-D-thiogalactopyranoside, Pit-1 was expressed and accumulated as inclusion bodies in E. coli. The protein was then purified in one step by affinity chromatography on a nickel-nitrilotriacetic acid agarose column under denaturing conditions. This method yielded 0.7 mg of highly pure and stable protein per 200 ml of bacterial culture. A band of 40 kDa, resolved as recombinant ayu Pit-1 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, agrees well with the molecular mass calculated from the translated cDNA sequence. The purified recombinant Pit-1 was confirmed in vitro through Western blot analysis, using its monoclonal antibody. This monoclonal antibody detected Pit-1 in the nuclei of ayu developing pituitary by immunohistochemical reaction. It serves as a good reagent for the detection of ayu Pit-1 in situ.

Mass spectrometry of peptides in neuroscience

This review focuses on the contributions of modern mass spectrometry to neuropeptide research. An introduction to newer mass spectrometric techniques is provided. Also, the use of mass spectrometry in combination with high-resolution separation techniques for neuropeptide identification in biological samples is illustrated. The amino acid sequence information that is important for the identification and analysis of known, novel, or chemically modified neuropeptides may be obtained using mass spectrometric techniques. Because mass spectrometry techniques can be used to reflect the dynamic properties associated with neuropeptide processing in biological systems, they may be used in the future to monitor peptide profiles within organisms in response to environmental challenges such as disease and stress.