A sex-limited serum protein of Syrian hamsters: definition of female protein and regulation by testosterone.

Abstract

Normal Syrian hamster females contain a serum protein not found by simple gel diffusion assay in normal adult males. This sex-limited protein was called female protein (FP). Low levels of FP were found in sera from normal weanling male hamsters. Adult male hamsters castrated or treated with diethylstilbestrol also developed serum FP, which could be suppressed by administration of testosterone. Exogenous testosterone also suppressed serum FP in adult females, and ovarian function did not appear to be critical for maintenance of serum FP. Although FP is present in significant amounts (1-2 mg/ml) in adult females, its function is presently unknown. Serum proteins specific for one sex have been described in many species. Numerous examples exist in insects (1) where hormonally controlled female specific proteins have been detected in serums during egg production and are necessary for egg maturation (2). Similarly, a phosphoprotein, called "serum vitellin" by Laskowski (3) was found in the plasma of laying hens. This protein was also found in cockerels after diethylstilbestrol (DES) treatment (4) and along with a lipoprotein component (5) apparently acts as a transport system for the developing yolk. Another sex-linked serum protein called "hormone-influenced protein" has been detected in some normal laying hens and in other chickens (male and female) after progesterone treatment (6).In mammals, sex-differences in serum levels of IgM (7, 8) have been described and two mouse complement components, C5 and C6, have been shown to be under sex hormone control (9,10 Freund's adjuvant. Specific antisera to FP were obtained either by direct addition of absorbing antigen (normal male hamster serum, NMHS) to the antisera and removal of precipitins by centrifugation or usually by passage of the antiserum through a column of Sepharose 2B (Pharmacia, Uppsala, Sweden) to which NMHS had been coupled by cyanogen bromide (14). FP was isolated by passing normal female hamster sera (NFHS) through a column containing Sepharose 2B conjugated by cyanogen bromide to the one-half saturated ammonium sulfate precipitate of specific rabbit antisera against FP. The column was thoroughly washed with phosphate buffered saline at pH 7.2 and the FP was eluted with 0.5 M acetic acid, promptly neutralized with Tris base, and then concentrated by negative pressure and dialyzed against phosphate-buffered saline.Immunodiffusion Studies. Agar electrophoresis and immunoelectrophoresis were performed on 2% agar covered microscope slides using 7 V/cm with barbital buffer at pH 8.2 (ionic strength 0.04). Agar electrophoresis patterns of FP were stained with various dyes according to Uriel (15). Simple gel diffusion was done on 1% agarose covered slides. FP was quantified by radial diffusion on glass slides covered with 1% agar containing specific rabbit antisera against FP. Five microliter samples were placed into 14 gauge needle holes and after 24 hr at room temperature the precipitin diameters were measured. The squared diameters were then compared...

Hamster female protein, a sex-limited pentraxin, is a constituent of Syrian hamster amyloid.

“…Even after 7 or 9 mo of treatment, only minimal amyloid was detectable in males, whereas extensive deposits (and death) were characteristic in females. DES was more effective than (12).…”

“…Therefore, for control purposes, liver FP content was determined in three male hamsters 1 mo after DES, when serum FP was increased (12), but before amyloid development (Table I). The extractable FP (0.031 mg/g) in this "early DES" group was similar to that of normal female liver (0.04 mg/g).…”

“…Tissue suspensions were centrifuged at 13,000 rpm in a Sorvall RC5B, 4°C, 30 min (DuPont-Sorvall). The supernatant fluids were pooled, concentrated by negative pressure dialysis, and quantified for FP by either ring diffusion or rocket electrophoresis using specific rabbit anti-FP in agarose (12).…”

“…The Syrian hamster has an unusual sex-limited serum pentraxin called female protein (FP) (12,13). So far, only in the Syrian hamster has a pentraxin gene come under such stringent sex hormone control (14).…”

Re-examination on the Sex-influenced Esterase (ESSI) in Rat Serum

“…Female protein (FP) in Syrian hamsters [3] and sex influenced esterase (ESSI) in rats [4] are hardly detectable in the normal mature males. The quantitative difference in protein levels between the sexes and the sex dimorphism for a specific protein provide unique models for studying regulatory mechanisms in the synthesis and metabolism of proteins.…”