Estradiol-17 beta effects on lipid and carbohydrate metabolism and on the induction of a yolk precursor in goldfish, Carassius auratus

Isolation and Characterization of a Novel Sialoglycopeptide Promoting Osteogenesis from Gadus morhua Eggs

Gadus morhua eggs contain several nutrients, including polyunsaturated fatty acids, lecithin and glycoproteins. A novel sialoglycopeptide from the eggs of G. morhua (Gm-SGPP) was extracted with 90% phenol and purified by Q Sepharose Fast Flow (QFF) ion exchange chromatography, followed by S-300 gel filtration chromatography. Gm-SGPP contained 63.7% carbohydrate, 16.2% protein and 18.6% N-acetylneuraminic acid. High-performance size exclusion chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) demonstrated that Gm-SGPP is a 7000-Da pure sialoglycopeptide. β-elimination reaction suggested that Gm-SGPP contained N-glycan units. Amino acid N-terminal sequence analysis indicated the presence of Ala-Ser-Asn-Gly-Thr-Gln-Ala-Pro amino acid sequence. Moreover, N-glycan was connected at the third Asn location of the peptide chain through GlcNAc. Gm-SGPP was composed of D-mannose, D-glucuronic acid and D-galactose. Fourier transform-infrared spectroscopy (FT-IR), ¹H-nuclear magnetic resonance spectroscopy (¹H-NMR) and methylation analysis were performed to reveal the structure profile of Gm-SGPP. In vitro results showed that the proliferation activity of MC3T3-E1 cells was significantly promoted by Gm-SGPP. In vivo data revealed that Gm-SGPP increased the calcium and phosphorus content of tibias and promoted longitudinal bone growth in adolescent rats.

Vitellogenin functions as a multivalent pattern recognition receptor with an opsonic activity

Background

Vitellogenin (Vg), a major reproductive protein, has been associated with infection-resistant response in fish. However, the underlying mechanisms by which Vg is involved in anti-infectious response are not understood.

Methodology/Results

By both protein-microbe interaction analysis and enzyme-linked immunosorbent assay as well as phagocytosis test, we demonstrate for the first time that fish Vg acts as a pattern recognition molecule with multiple specificities that can recognize bacteria as well as fungus rather than self components from fish, and functions as an opsonin that can enhance macrophage phagocytosis.

Conclusions

This study shows that fish Vg plays an integrative function in regulating immunity via its pleiotropic effects on both recognizing pathogen-associated molecular patterns and promoting macrophage phagocytosis. It also supports the notion that factors normally involved in control of female reproduction are associated with immunity in organisms that rely on Vg for oocyte development.

A vitellogenin chain containing a superoxide dismutase-like domain is the major component of yolk proteins in cladoceran crustacean Daphnia magna

A cDNA encoding vitellogenin (VTG), a precursor of a major yolk protein, vitellin (VTN), was isolated from cladoceran crustacean Daphnia magna. The deduced amino acid sequence of DmagVTG1, the polypeptide encoded by the cDNA, contained a possible signal peptide sequence of 16 amino acid (aa) residues. The possible mature form of DmagVTG1 consists of 1985 aa residues with a calculated molecular mass of 223,070 Da. The large lipid transfer (LLT) module and a part of the von Willebrand factor D (VWD) module found in the aa sequences of VTGs of many other organisms are well conserved in DmagVTG1. Phylogenetic analysis suggested that the LLT module of DmagVTG1 is more closely related to those of insect VTGs than those of decapodan crustaceans. A unique feature of DmagVTG1 is that it has a superoxide dismutase (SOD)-like domain at its NH(2)-terminus. Antisera against the SOD-like domain, the NH(2)-terminal part of the VTG domain and the COOH-terminal part of the VTG domain, respectively, were prepared and used for analysis of D. magna yolk proteins. Six species (I to VI) of major protein complexes were found in D. magna parthenogenetic eggs isolated immediately after ovulation. Complexes IV and V were the most abundant. DmagVTG1 was a component of Complexes III, IV and V, and the most abundant polypeptide in D. magna eggs. The protein complexes underwent gradual proteolysis during development. One of the primary sites of cleavage was between the two successive Arg residues located at the 1454th and 1455th positions of DmagVTG1.

Purification and characterization of a putative vitellogenin from the ovary of amphioxus (Branchiostoma belcheri tsingtaunese)

An oocyte-yolk protein was purified by double-step chromatography from amphioxus ovaries. The purified protein appeared to exist as a homodimer of approximately 320 kDa in native polyacrylamide gel electrophoresis (PAGE), and was reduced to a single monomer of approximately 160 kDa in sodium dodecyl sulfate-PAGE (SDS-PAGE). The protein was characterized as a phospholipoglycoprotein by native PAGE and staining of gels for phosphorus with methyl green, for lipids with oil red O and Sudan black B, and for carbohydrates using periodic acid/Schiff reagent. In addition, the amino acid composition of the oocyte-yolk protein was generally similar to that of vitellogenins (Vgs) isolated from different phyla of animals including both vertebrates and invertebrates. The purified phospholipoglycoprotein is thus considered as putative amphioxus Vg.

Vitellogenins of Oreochromis niloticus: identification, isolation, and biochemical and immunochemical characterization

Two native forms of vitellogenin (EIP1 and EIP2) were identified in the plasma of Oreochromis niloticus. They were present in females and were estrogen-inducible in males. Both were phosphoglycolipoproteins and both immunoreacted with the antiserum raised against egg proteins. Two prominent bands (EIpp1 and EIpp2; corresponding to 185 and 120 kDa, respectively), observed on sodium dodecyl sulfate-polyacrylamide gels, were induced by estradiol treatment of males and immunoreacted with the antiserum against egg proteins. EIP1 and EIP2 were isolated by precipitation with Mg2+ ions and ethylenediamine tetraacetic acid, preparative polyacrylamide gel electrophoresis, and electroelution. During purification the fractions containing EIP1 and EIP2 also retained EIpp2 and EIpp1, respectively. Immunoblot analyses using affinity-purified antibodies against EIP1, EIP2, EIpp1, and EIpp2 confirmed that EIP1 and EIP2 were at least composed of EIpp2 and EIpp1, respectively. These results suggest that at least two immunochemically different proteins are induced and are secreted into the blood to serve as vitellogenin and to provide a source of nutrient for the developing embryo of Oreochromis niloticus.

The purification and partial characterization of carp, Cyprinus carpio, vitellogenin

A procedure is described for the isolation of intact vitellogenin (c-VTG) from the carp, Cyprinus carpio. VTG was induced in juvenile females using oestradiol-17β and purified from the plasma using a combination of gel-filtration chromatography on Sepharose 6B and ion exchange chromatography on DEAE-cellulose. Purification procedures were conducted at low temperatures (below 9°C) in the presence of the proteolytic enzyme inhibitor aprotinin to prevent degradation. Intact c-VTG had an apparent molecular mass of 390,000 Daltons, but when extracted from plasma in the absence of aprotinin it underwent proteolysis into at least 2 protein fragments (apparent molecular masses of 230,000 and 96,000 Daltons), showing an instability of the native dimer. An amino acid analysis of c-VTG showed that its composition was almost identical to goldfish VTG, a species closely allied to the true carps and also similar to other oviparous vertebrate VTGs. Collectively, these data indicate that using these purification procedures VTG from carp, and probably other teleost species, can be isolated in an intact, highly purified form.

Changes in tissue lipid levels in the freshwater catfishClarias batrachus associated with the reproductive cycle

The levels of free fatty acid (FFA), monoglyceride (MG), diglyceride (DG), triglyceride (TG), phospholipid (PL), free cholesterol (CF) and esterified cholesterol (CE) were measured in the liver, plasma, ovary, abdominal fat and muscle during different phases of the annual reproductive cycle in femaleClarias batrachus. During the preparatory phase, hepatic lipogenic activity predominated over mobilization and consumption. In the prespawning season, an increased hepatic lipogenic activity was maintained, but lipids were transferred from the liver to the ovary. In the spawning phase, the diminished food intake, and enhanced caloric demand for spawning behaviour and activity limited hepatic lipogenic activity, and TG lypolysis was increased as was the production of more FFA. Maximum accumulation of vitellogenin, as reflected by maximum rise in ovarian PL titre was characteristic of this phase. Marked reductions in ovarian lipid occurred during the postspawning phase. In the resting phase, there was a recovery of lipogenic activity, but PL synthesis was still inhibited. In contrast to other investigated teleosts, there were extremely high level of FFA in liver, plasma, ovary and muscle throughout the annual reproductive cycle inC. batrachus. FFA appears to be the main lipid metabolite which had a very high turnover. As evidenced by the high TG content, abdominal fat seems to be the main fat depot, not the liver and muscle.

Effects of 17 beta-estradiol and methyl testosterone on the activity of the thyroid gland in rainbow trout, Salmo gairdneri Richardson

Methyl testosterone (MT) and 17 beta-estradiol (E2), suspended either in sesame oil (and injected on alternate days) or in warm hydrogenated coconut oil (and injected once in the form of an "implant"), were administered intraperitoneally to nonvitellogenic rainbow trout (Salmo gairdneri Richardson). When given as sesame oil injections E2 significantly reduced plasma triiodo-L-thyronine (T3) levels and thyroid epithelial cell height (TEH), but had no apparent effect on plasma L-thyroxine (T4) levels. When given as a coconut oil "implant" E2 significantly reduced both plasma T3 and T4 levels. E2 also elevated the hepatosomatic index (HSI), plasma Ca2+, Mg2+, protein, triglyceride, and alkali-labile phosphoprotein (ALP) and hepatic lipid concentration, decreased hepatic glycogen levels, but was without effect on plasma Na+ and glucose levels. MT given via sesame oil injections significantly lowered plasma T3 levels, but was without effect on plasma T4 concentrations or TEH; the T3-lowering effect of MT was not evident when the steroid was given in the form of a coconut oil "implant." MT also effected a lowering of plasma Mg2+ and protein and hepatic lipid concentrations, but had no significant effect on HSI, plasma Na+, glucose triglyceride and ALP concentration, or hepatic glycogen levels. MT given as a series of injections lowered plasma Ca2+ levels, but was without effect when given as an "implant" and had no significant effect on plasma Ca2+. Intraperitoneal injections of ovine thyrotropin (TSH) (2 micrograms/g body wt) elicited an increase in both plasma T4 and T3 levels within 24 hr in E2-, MT-, and oil-injected groups. The TSH-stimulated increase in plasma T4 level was significantly less in the E2-treated fish compared with oil- or MT-treated groups. The TSH-stimulated increase in plasma T3 levels in both groups of steroid-treated fish was significantly less than that of the oil-injected controls.