Expression and characterization of biologically active ovine FSH from mammalian cell lines

Stably transfected cell lines expressing the alpha subunit, beta subunit and alpha/beta heterodimer of ovine (o)FSH have been established following the transfection of Chinese hamster ovary cells with alpha and beta subunit cDNA expression vectors. In the absence of the alpha subunit, FSH beta subunit polypeptides were inefficiently secreted and displayed a short intracellular half-life, while free alpha subunits were readily secreted in the absence of the beta subunit. Cotransfection of oFSH alpha and beta subunit cDNAs led to heterodimer assembly and secretion. While alteration of the nucleotide sequence flanking the beta subunit AUG initiation codon did not appreciably enhance heterodimer biosynthesis and secretion, the replacement of the 5' untranslated and signal peptide-coding regions of the beta subunit cDNA with the corresponding sequences from an oGH cDNA clone was associated with a twofold increase in oFSH heterodimer secretion. The recombinant oFSH had a higher molecular weight than pituitary-derived oFSH, and was more acidic than the native hormone when analysed using isoelectric focusing, suggesting a greater degree of sialylation of the recombinant hormone. A comparison of the activities of the recombinant and native hormones in the porcine testis radioreceptor assay and in the in vitro Sertoli cell bioassay revealed that the recombinant oFSH displayed enhanced biological activity in the Sertoli cell assay when compared with the native hormone.

Gonadotrope responsiveness in orchidectomized sheep: III. Effect of estradiol withdrawal after continuous infusion

The magnitude of GnRH-induced (1600 ng/hourly pulse for 24 h) preovulatory surge-like secretion of LH was assessed in orchidectomized sheep (wethers) during infusion of estradiol (E2, 5 micrograms/h in 10% ethanol-saline [vehicle]) or at 0, 12, 24, or 48 h after E2 withdrawal (n = 6 wethers/group). In one group, infusion of E2 was continued for 48 h, with concurrent circhoral delivery of GnRH during the final 24 h of the E2 delivery period. In other treatment groups, infusion of E2 or vehicle was continued for 24 h. Circhoral delivery of GnRH was initiated at the conclusion of E2 delivery or 12, 24, or 48 h thereafter, or at 48 h after cessation of vehicle infusion. Total GnRH-induced LH secretion in wethers receiving concurrent E2 was significantly augmented relative to the GnRH-induced secretory response in wethers receiving vehicle alone. The magnitude of GnRH-induced LH release was significantly reduced in animals in which E2 delivery was halted at the beginning of the GnRH challenge period. Further reductions in gonadotrope responsiveness were noted 12, 24, and 48 h after cessation of E2 delivery. Responsiveness 48 h after halting the E2 infusion did not differ (p > 0.05) from the responsiveness of wethers that had not been treated with E2. In a companion study, anterior pituitary tissue was collected at the end of E2 infusion (5 micrograms/h for 24 h) or at 12, 24, or 48 h thereafter (n = 6 wethers/group). Anterior pituitary tissue of control animals (n = 6) was collected after halting the infusion of vehicle alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Testis function and feedlot performance of bulls actively immunized against gonadotropin-releasing hormone: effect of implants containing progesterone and estradiol benzoate

The effect of implants containing anabolic steroid (Synovex) on testis function, feedlot performance, and carcass traits was evaluated in bulls, steers, and bulls actively immunized against gonadotropin-releasing hormone (GnRH). Ninety-one Hereford or Hereford x Red Angus bull calves were randomly assigned to a 3 x 2 factorial experiment. The treatments were: 1) unimmunized control (n = 30), 2) actively immunized against GnRH (n = 31), or 3) castrate (n = 30). The classes were 1) unimplanted (n = 45) or 2) implanted (n = 46) with Synovex. Animals in treatment Groups 2 and 3 were either immunized with a GnRH-keyhole limpet hemocyanin (KLH) conjugate or castrated at 3.6 +/- .1 mo of age. Animals assigned to Class 2 received Synovex-C at the time of initial treatment and Synovex-S at weaning and feedlot entry. Animals in treatment Group 2 received a booster immunization at feedlot entry. Anti-GnRH titer was evident at weaning and remained elevated to slaughter in all (31 of 31) immunized animals. Anti-GnRH titer was not evident in steers or unimmunized bulls. Immunization and (or) Synovex decreased (P < .05) serum concentrations of testosterone (T) and scrotal circumference (SC) at weaning. Similarly, SC, testis weight, and tissue concentrations of spermatozoa at slaughter were significantly reduced by immunization, Synovex, or the immunization/Synovex combination. Immunization, but not Synovex, reduced (P < .05) serum levels of T at slaughter. The masculinity of immunized bulls was less (P < .05) than that of control bulls.(ABSTRACT TRUNCATED AT 250 WORDS)

Gonadotrope responsiveness in orchidectomized sheep. II. Effect of gonadotropin-releasing hormone amplitude shift during continuous infusion of estradiol

Gonadotropin secretion during continuous infusion of estradiol (E2; 5 micrograms/h, i.v.) and pulsatile delivery of GnRH was assessed in orchidectomized sheep (wethers). Wethers received 200 ng GnRH per hourly pulse during the first 12 h of E2 infusion. During the final 36 h of infusion, animals (n = 6/group) received 0, 200, 400, 800, or 1600 ng GnRH/h pulse. Amplitude shift to 1600 ng GnRH/h pulse induced preovulatory surge-like secretion of LH in animals receiving concurrent E2 infusion. In the absence of E2, the same change in GnRH amplitude did not significantly affect serum concentrations of LH. Full expression of the GnRH-induced surge of LH in wethers required prior exposure to E2, but was not dependent on pretreatment with low-amplitude GnRH stimulus. In a companion experiment, anterior pituitary tissue was collected from E2-treated wethers 0, 3, 6, 12, or 24 h after initiation of episodic GnRH delivery (1600 ng/h pulse). Treatment with E2 induced a 5-fold increase in GnRH receptor concentration. The tissue concentration of GnRH receptor was depressed (p < 0.05) within 6 h of initiation of high-amplitude GnRH stimulation and remained depressed for the duration of GnRH delivery. Tissue stores of LH were increased (P < 0.05) by E2 and reduced (p < 0.05) after 3 h of high-amplitude GnRH stimulation. In contrast, tissue stores of FSH were reduced (p < 0.05) by both E2 alone and E2 with concurrent high-amplitude GnRH stimulation. The concentration of mRNA for the FSH beta subunit, but not for the alpha or LH beta subunits, was reduced (p < 0.05) by E2.(ABSTRACT TRUNCATED AT 250 WORDS)

Production of methionyl-minus ovine growth hormone in Escherichia coli and one-step purification

The overproduction of ovine growth hormone (oGH) in Escherichia coli is described, achieved in part by alteration of the codon usage for nine of the first 15 amino acids (aa) of the mature hormone. Recombinant oGH (re-oGH), representing 12% of the total cellular protein, was isolated from inclusion bodies by solubilisation using the cationic surfactant cetyltrimethylammonium chloride (CTAC). The hormone was refolded and subsequently purified to greater than 95% homogeneity in a single step using preparative reverse phase high performance liquid chromatography. The aa sequence analysis revealed that the N-terminus of the E. coli-derived polypeptide was identical to that of pituitary-derived oGH, and re-oGH displayed potent somatotropic activity in vivo.

Removal of 3'untranslated sequences dramatically enhances transient expression of ovine follicle-stimulating hormone Beta gene messenger ribonucleic Acid

The influence of the 3'untranslated (3'-UT) region of the ovine follicle-stimulating hormone (FSH) β mRNA on the level of transcript expression was studied. Only very low levels of FSH β mRNA were detected following transient transfection of COS cells with a eukaryotic expression vector containing a full-length ovine FSH β cDNA that includes 1.1 kilobases (kb) of 3'-UT. In contrast, deletion of all but 135 basepairs (bp) of the 3'-UT resulted in a striking increase in FSH β mRNA expression following transfection of the truncated cDNA construct. These observations suggest that sequences within the 3'-UT of the ovine FSH β mRNA may play a significant role in the post-transcriptional regulation of FSH β expression.

Pattern of gonadotropin-releasing hormone (GnRH)-like stimuli sufficient to induce follicular growth and ovulation in ewes passively immunized against GnRH

The pattern of GnRH-like stimuli capable of inducing follicular growth, ovulation, and luteal function was evaluated in ewes passively immunized against GnRH. The estrous cycles of 30 regularly cyclic sheep were synchronized using vaginal pessaries impregnated with a synthetic progestogen. Animals were passively immunized against GnRH (groups 2-5, n = 6) or the carrier protein, keyhole limpet hemocyanin (KLH; group 1, n = 6), at the time of pessary removal (PR). Circhoral delivery of saline (groups 1, 2, and 5) or low amplitude GnRH agonist (des-Gly10 GnRH ethylamide [100 ng/hourly pulse]; groups 3 and 4) was initiated at PR and continued for 3 (groups 4 and 5) or 12 days (groups 1-3). In groups 4 and 5, the amplitude of the GnRH-like stimulus was increased to 800 ng/hourly pulse (stimulus-shift) during the 24-h period beginning 72 h after PR. The amplitude of the hourly stimulus was adjusted to 100 ng/pulse 96 h after PR and continued at that level to Day 12. The endocrine changes associated with follicle growth and maturation (serum concentrations of estradiol [E2] above 10 pg/ml), ovulation (surge-like secretion of LH and FSH), and normal luteal function (serum concentrations of progesterone [P] above 2 ng/ml) were evident in ewes passively immunized against KLH (group 1). In this group, the preovulatory surge of gonadotropins was noted 48.7 +/- 1.2 h after PR. These endocrine events were blocked by passive immunization against GnRH (group 2).(ABSTRACT TRUNCATED AT 250 WORDS)

Functional expression of an ovine growth hormone receptor in transfected Chinese hamster ovary cells

Structural heterogeneity has been demonstrated for growth hormone (GH) receptors from a number of species, and both high and low affinity art receptors have been characterised by ligand binding studies. In the present study, we have transfected Chinese hamster ovary (CHO-K1) cells with a cDNA clone encoding a full-length transmembrane ovine (o) GH receptor, under the regulatory control of the human metallothionein IIA promoter. A stably transfected cell line was established (GHR9.5) which expresses on the cell surface a single class of receptor which binds 220,000 [125I]oGH molecules at high affinity (Kd = 0.30 nM) which is comparable to the affinity established for endogenous oGH receptors in postnatal sheep liver microsomes (Kd = 0.27 nM, Freemark et al. (1987) Endocrinology 120, 1865-1872). The expressed receptor also binds ovine placental lactogen (oPL, 205,000 binding sites per cell) with high affinity (Kd = 0.76 nM). The presence of two species of oGH receptor was detected in GHR9.5 cells using affinity cross-linking analysis (M(r) 148,000 and M(r) 73,000) and given that the oGH receptor cDNA codes for a non-glycosylated receptor of M(r) 69,914, it is likely that these cross-linked species correspond to homodimeric and monomeric forms of the oGH receptor, each binding to a single molecule of GH. Parallel cross-linking studies with sheep liver microsomes also demonstrated two oGH receptor species (M(r) 133,000 and M(r) 58,000), the difference in relative molecular weights between the transfected and endogenous receptors presumably resulting from tissue-specific post-translational modifications. In the presence of oGH, the GHR9.5 cells respond by increasing total cellular protein synthesis by 27% relative to non-GH-exposed GHR9.5 cells, indicating the functionality of the expressed receptor. We also demonstrate unequivocally that oPL, through a specific interaction with the transfected oGH receptor, is able to mediate a similar cellular response (38% protein synthesis induction). Responsiveness to oGH and oPL in the GHR9.5 cells is dependent on serum starvation prior to oGH exposure and occurs only with prolonged exposure (greater than 2 h) to oGH. This cellular stimulation occurs independently of c-fos transcription which has previously been shown to be one of the earliest events associated with GH action in tissues expressing endogenous GH receptors (Doglio et al. (1989) Proc. Natl. Acad. Sci. USA 86, 1148-1152; Slootweg et al. (1990) J. Mol. Endocrinol. 4, 265-274).

Feedlot performance of steers and bulls actively immunized against gonadotropin-releasing hormone

Feedlot performance and testicular and pituitary function were assessed in cattle actively immunized against GnRH. In Trial 1, 50 steers were either unimmunized (n = 10), actively immunized against keyhole limpet hemocyanin (KLH; n = 10), or immunized against a GnRH-KLH conjugate (n = 30). Fifteen of 30 steers immunized against GnRH-KLH received a secondary immunization 8 wk after primary immunization. Antibodies against GnRH were not evident in unimmunized steers or steers actively immunized against KLH. Antibodies against GnRH were noted in all immunized animals (n = 30) within 6 wk of primary immunization and anti-GnRH antibody concentrations became maximal 20 to 24 wk after immunization. The increasing anti-GnRH titer in immunized steers was associated with decreasing serum concentrations of LH. Serum concentrations of LH were depressed (P less than .05) within 8 wk of primary immunization and reached a nadir by wk 20. The patterns of increase in GnRH titer and decrease in serum concentrations of LH did not differ (P greater than .05) in animals receiving primary immunization alone or primary and secondary immunization. Feedlot performance and carcass quality were not affected (P greater than .05) by immunization against KLH or the GnRH-KLH conjugate. In Trial 2, 60 bull calves (mean weight = 325.2 +/- 2.8 kg) were randomly assigned to a 2 x 3 factorial experiment. The two classes (n = 30) were 1) unimplanted and 2) implanted with Synovex-S. The three treatments (n = 20) were 1) intact control, 2) actively immunized against GnRH, and 3) castrate.(ABSTRACT TRUNCATED AT 250 WORDS)

Gonadotrope responsiveness in orchidectomized sheep: I. Effect of continuous infusion of estradiol

Gonadotrope function during continuous infusion of estradiol (E2) was evaluated in orchidectomized sheep (wethers). Serum concentrations of LH were reduced (p less than 0.05) within 3 h of introduction of E2 and remained depressed for the period of E2 delivery (48 h). Gonadotrope responsiveness (change in LH secretion induced by a 500-ng GnRH challenge, i.v.) was assessed 0, 3, 6, 12, 24, or 48 h after initiation of E2 infusion. Gonadotrope responsiveness was augmented (p less than 0.05) 12, 24, and 48 h after first introduction of E2. In a companion study, anterior pituitary tissue was collected 0, 3, 6, 12, 24, or 48 h after the beginning of E2 infusion. Tissue concentration of GnRH receptor was increased 3-fold within 12 h of first introduction of E2. Tissue stores of LH were also increased (p less than 0.05) during E2 infusion. Passive immunization against GnRH increased (p less than 0.05) tissue stores of LH, but had no effect on GnRH receptor concentration. Passive immunization against GnRH and concurrent infusion of E2 increased (p less than 0.05) both tissue stores of LH and tissue concentrations of GnRH receptor. The acute suppression of LH secretion induced by infusion of E2 was not affected by concurrent episodic administration of GnRH (200 ng/hourly pulse). However, serum concentrations of LH were restored to pretreatment levels within 12 h of initiation of E2 infusion and episodic delivery of GnRH. These data indicate that E2 acts in wethers to suppress gonadotropin secretion while simultaneously increasing GnRH receptor concentration, tissue stores of LH, and gonadotrope responsiveness.(ABSTRACT TRUNCATED AT 250 WORDS)

Nucleotide sequence, polymorphism, and evolution of ovine MHC class II DQA genes

The nucleotide sequence of all exons and introns, excluding exon 1, of the ovine major histocompatibility complex (MhcOvar) genes analogous to the HLA-DQA1 and -DQA2 genes has been determined and the gene structure found to be similar to that reported for other species. The predicted amino acid sequences of the Ovar-DQA genes have been compared with the equivalent DQA genes in man, mouse, rat, rabbit, and cattle and used to determine the evolutionary relationships of the sheep class II genes to these other species. Northern blot analysis of sheep mRNA using exon specific probes for each of the two Ovar-DQA genes show that both genes are transcribed, whereas in humans there is no evidence that HLA-DQA2 is transcriptionally active. Restriction fragment length polymorphisms (RFLPs) have been used to define a polymorphic series of alleles in both Ovar-DQA genes and have indicated that the number of DQA genes is not constant in sheep as it is in humans, but varies with the haplotype.

Developmental and tissue-specific regulation of ovine insulin-like growth factor II (IGF-II) mRNA expression

Insulin-like growth factor II (IGF-II) is believed to be involved in the development of the fetus. Northern and dot-blot analysis of RNA isolated from different sheep tissues at various stages of development were undertaken, revealing that the ovine IGF-II gene is expressed as a multitranscript family (6.0, 5.1, 5.0, 4.7, 3.8, 2.9, 2.3, 1.9, 1.6, 1.3 kb). Evidence that the ovine IGF-II gene may be regulated in a developmental, tissue-specific, co-ordinate or independent manner is presented. The developmental profile of IGF-II gene expression correlates with plasma levels (Mesiano et al. (1989) Endocrinology 124, 1485-1491), and suggests that the rapid fall in plasma concentration at term can be attributed to regulation at the transcriptional level. With the exception of the kidney, IGF-II expression was down-regulated at birth in all tissues examined. As in man but not rat, an adult liver-specific transcript was detected and attributed to different 5' untranslated regions in the fetal and adult IGF-II mRNAs. The finding of IGF-II transcripts in all tissues examined supports evidence from other species of autocrine/paracrine roles for IGF-II in the development of the fetus.

The sheep growth hormone receptor: molecular cloning and ontogeny of mRNA expression in the liver

Two overlapping cDNA clones encoding the sheep growth hormone (GH) receptor were isolated from a sheep liver cDNA library. The translated amino acid sequence predicts a polypeptide precursor of 634 amino acids with a calculated molecular weight of 70,799. The mature GH receptor comprises an extracellular domain of 242 amino acids, a hydrophobic transmembrane region of 24 amino acids, and a cytoplasmic domain of 350 amino acids. The nucleotide and translated amino acid sequences display extensive similarity with sequences established for GH receptors from a number of other mammalian species. A prominent transcript of 4.5 kb and a minor transcript of 1.9 kb are detected following Northern blot hybridization of poly(A)+ RNA isolated from sheep liver. The onset of GH receptor mRNA expression in the liver is developmentally regulated: GH receptor transcripts are first detected by Northern blot hybridization in liver taken from a term (145 days of gestation) fetus and reach maximum levels within one week following birth. Ribonuclease protection assays reveal heterogeneity within the 5' untranslated region of GH receptor mRNA transcripts detected in liver and a number of other tissues. At least one transcript appears to be expressed in a liver-specific fashion, supporting a role for alternative RNA splicing in the tissue-specific regulation of sheep GH receptor expression.

Feedlot performance of beef heifers implanted with Synovex-H: effect of melengestrol acetate, ovariectomy or active immunization against GnRH

The effects on anabolic steroid implantation on feedlot performance and carcass composition and quality were examined in control (CNTRL), ovariectomized (OVX) or melengestrol acetate-fed (MGA) beef heifers or heifers actively immunized against GnRH (Anti-GnRH). Heifers (n = 112) were assigned randomly to a 2 x 4 factorial experiment. The two classes were made up of heifers not implanted and those implanted with Synovex-H. The four treatments were 1) CNTRL, 2) MGA, 3) OVX and 4) Anti-GnRH. Heifers were housed in individual pens and fed a high-energy diet for the 4-mo study. Synovex-H increased final live weight (P less than .005), carcass weight (P less than .005), ADG (P less than .0001) and feed efficiency (P less than .005) but did not alter carcass quality and yield grade (P greater than .05). Synovex-H increased deposition of protein (P less than .0001) and reduced deposition of fat (P less than .0001). Oral administration of MGA had no significant effect on feedlot performance or carcass quality. For heifers not implanted, active immunization against GnRH, but not ovariectomy, depressed ADG (P less than .05) and increased fat deposition (P less than .05) while reducing protein deposition (P less than .05). These effects of active immunization were reversed by concurrent administration of Synovex-H. Feedlot performance and carcass composition of heifers were improved by administration of anabolic steroids. When heifers were housed singly, neither ovariectomy, active immunization against GnRH nor oral administration of MGA improved feedlot performance of heifers implanted with Synovex-H.

Reproductive function and feedlot performance of beef heifers actively immunized against GnRH1

Two trials were conducted to examine reproductive function and feedlot performance by heifers after active immunization against GnRH. In trial 1, heifers were not immunized or were immunized with one of three doses of a GnRH-KLH (keyhole limpet hemocyanin) conjugate in Freund's complete adjuvant. Antibodies against GnRH were not detectable in non-immunized heifers (n = 9). However, antibodies against GnRH were noted in all immunized animals (n = 30) within 8 wk of primary immunization; anti-GnRH antibody concentrations were at a maximum 16 to 20 wk after immunization. This increased anti-GnRH titer was associated with a decreased serum concentration of progesterone. Ovarian and uterine weight and tissue concentrations of LH and GnRH receptor were reduced (P less than .05) by immunoneutralization of GnRH. Similarly, immunization against GnRH reduced (P less than .05) weight gain during feedlot confinement. In trial 2, feedlot performance after insertion of anabolic steroid implants (Synovex H) was evaluated in non-immunized heifers (n = 15), heifers actively immunized against GnRH-KLH (n = 15) or KLH alone (n = 15), or non-immunized heifers treated with melengestrol acetate (MGA; n = 15). Serum concentrations of progesterone were depressed in anti-GnRH and MGA-fed groups, but ovarian and uterine weights were depressed (P less than .05) only in heifers immunized against GnRH. Total weight gain and gain during the final 4 wk of confinement did not differ (P greater than .05) among groups with steroid implants. The GnRH-KLH conjugate is an effective immunogen in heifers, leading to suppression of reproductive activity. The depression of weight gain that attends development of anti-GnRH titers may be reversed by use of implants that contain anabolic steroids.

Genetic selection for disease resistance and traits of economic importance in animal production

Significant advances have been made in recent years in improving animal stocks by selective breeding. However, existing selection techniques still rely on laborious and time-consuming progeny-testing programs and often depend on subjective assessment of the phenotype. New techniques in molecular genetics are being developed, aimed at the isolation and identification of DNA markers linked to genes for economically important production traits and disease resistance. When available, these markers will provide animal breeders with an objective test system to identify, at birth or even earlier, animals carrying desirable genes. This review outlines some of these new techniques and how they may be applied to the animal industries. Consideration is also given to some of the recent advances in our understanding of the immune system and of possible mechanisms of genetic control of animal disease resistance or susceptibility. The current knowledge of major histocompatibility complex (MHC) and non-MHC associated disease resistance/susceptibility in domestic animals is summarised and mechanisms which may be responsible for these associations are presented. Genes that control such factors as macrophage activation, cytokines, cytokine receptors and gamma delta-T cell receptors are also presented as potential candidates for analysis in genetic disease association studies. Ultimately, the goal will be to identify genes or DNA markers which can be used to select for or to genetically engineer disease resistance and enhanced production traits.

Tolerance to self-antigens in transgenic mice

Transgenic mice represent a versatile experimental approach for understanding the pathways by which the immune system regulates responsiveness to self-antigens, thereby establishing self-tolerance. The introduction of immunoglobulin and T cell receptor genes with specificity for self-antigens into the germline of mice has enabled the fate of self-reactive lymphocyte precursors to be followed in vivo. The influence of both developmentally regulated, and tissue-specific gene expression on tolerance to self-antigens has been addressed using transgenic mice expressing novel self-antigens under the transcriptional control of heterologous gene promoters. The generation of transgenic mice expressing structurally altered forms of self-antigens has allowed the role of antigen-processing in the induction of tolerance to be examined. Significantly, while these studies have confirmed the classically derived principles of immunological self-tolerance, they also point to the existence of pathways, as yet undefined, by which tolerance to self-antigens may be implemented and maintained.

Gonadotropin secretion in ovariectomized ewes: effect of passive immunization against gonadotropin-releasing hormone (GnRH) and infusion of a GnRH agonist and estradiol

Gonadotropin secretion was examined in ovariectomized sheep after passive immunization against gonadotropin-releasing hormone (GnRH). Infusion of ovine anti-GnRH serum, but not control antiserum, rapidly depressed serum concentrations of luteinizing hormone (LH). The anti-GnRH-induced reduction in serum LH was reversed by circhoral (hourly) administration of a GnRH agonist that did not cross-react with the anti-GnRH serum. In contrast, passive immunization against GnRH led to only a modest reduction in serum concentrations of follicle-stimulating hormone (FSH). Pulsatile delivery of the GnRH agonist did not influence serum concentrations of FSH. Continuous infusion of estradiol inhibited and then stimulated gonadotropin secretion in animals passively immunized against GnRH, with gonadotrope function driven by GnRH agonist. However, the magnitude of the positive feedback response was only 10% of the response noted in controls. These data indicate that the estradiol-induced surge of LH secretion in ovariectomized sheep is the product of estrogenic action at both hypothalamic and pituitary loci. Replacement of the endogenous GnRH pulse generator with an exogenous generator of GnRH-like pulses that were invariant in frequency and amplitude could not fully reestablish the preovulatory-like surge of LH induced by estradiol.

Avian gonadotropin-releasing hormones I and II in brain and other tissues in turkey hens

1. Radioimmunoassays were developed for measuring avian gonadotropin-releasing hormones I and II (cGnRH I and II) in tissue extracts during the reproductive cycle. 2. Hypothalamic concentrations of cGnRH I and II were qualitatively similar being lowest in non-photostimulated hens, greater in laying hens and greatest in incubating hens. 3. cGnRH II concentrations were similar in paraolfactory lobe and hypothalamic fragments while lesser amounts were found in cerebrum, cerebellum, duodenum, shell gland, and pineal. 4. These results suggest that cGnRH II has unknown functions in turkeys quite distinct from traditional functions associated with GnRHs.

Gonadotrophin secretion during the periovulatory period in Galway and Finnish Landrace ewes and Finnish Landrace ewes selected for high ovulation rate

Rates of ovulation differed significantly (P less than 0.01) among ewes of the different genetic lines. However, of the reproductive characteristics studied, only progesterone concentration at the height of luteal function, duration of oestrus, and interval from onset of oestrus to peak of the preovulatory gonadotrophin surge showed significant positive association with rate of ovulation. The pattern of secretion of LH during the periovulatory period did not differ in the Galway and Finnish Landrace breeds. The total amount of LH secreted during the preovulatory surge did not differ amongst lines. Similarly, no difference in the plasma concentration of LH at the height of the preovulatory surge was noted among Galway and reference Finnish Landrace lines. However, the concentration of LH at the height of the surge was significantly (P less than 0.05) reduced in the selected Finnish Landrace line. Plasma concentrations of FSH during the preovulatory period were significantly (P less than 0.05) elevated in the breed (Galway) with the lowest prolifcacy. When contrasted with either of the Finnish Landrace lines, the magnitudes of the preovulatory surge of FSH and the secondary surge of FSH were significantly greater (P less than 0.05) in Galway ewes. These results suggest that genetic difference in rate of ovulation among sheep breeds is not tightly coupled to quantitative differences in plasma concentration of gonadotrophic hormones during the periovulatory period.

Concentrations of bioactive and immunoactive luteinizing hormone in bovine anterior pituitary tissue

Tissue concentrations of LH as determined by radioimmunoassay (RIA) may not accurately measure actual changes that could occur in biological activity of the hormone. To examine this possibility, pituitary homogenates from 135 beef cows in various physiological states were analyzed for content of LH by both RIA and an in vitro bioassay. The ratio of biological/immunological active concentrations of LH remained constant (.52 +/- .02) even though tissue concentrations of immunoactive LH differed among groups. Tissue concentrations of bioactive LH were linearly related to, and highly correlated with (P less than .001), tissue concentrations of immunoactive LH. These data indicate that only a fraction of the immunoactive LH in the bovine pituitary is biologically active. However, this fraction does not vary with the reproductive status or plane of nutrition.

Induction of precocious puberty in ewe lambs by pulsatile administration of GnRH

Circhoral administration (250 ng/h, i.v.) of GnRH induced a preovulatory-like surge of LH and subsequent luteal function in 4 of 4 ewe lambs 1 month before expected date of puberty. Within 12h of the start of pulsatile delivery of GnRH, mean concentrations of immunoactive and bioactive LH increased significantly (P less than 0.05) and the LH surge occurred by 1.8 +/- 0.6 days of treatment. Mean concentrations of serum progesterone were elevated significantly (P less than 0.001) 3 days after the surge. The biopotency of LH (bioactive LH/immunoactive LH) before the GnRH-induced surge of LH did not differ from LH biopotency in ewe lambs receiving circhoral delivery of saline (0.41 +/- 0.05 and 0.46 +/- 0.04, respectively). Biopotency of LH declined markedly at the GnRH-induced LH surge (0.25 +/- 0.04), but biopotency of serum LH was significantly augmented (P less than 0.05) during the period of luteal activity (0.70 +/- 0.07). Regular oestrous cycles were observed in 3 of 4 ewe lambs after the 10-day GnRH treatment period. These results indicate that pulsatile delivery of GnRH is effective in inducing precocious puberty in ewe lambs. Increase in LH biopotency does not appear to be required in the pubertal transition to reproductive cyclicity in this species. Augmented LH biopotency may be important in support of luteal function after first ovulation.

Secretory dynamics of bioactive and immunoactive LH during the oestrous cycle of the sheep

Blood samples were collected every 15 min for 6 h during the follicular (1 day before oestrus), and early (Days +1 to +3), mid- (Days +4 to +8), and full (Days +9 to +14) luteal phases of the oestrous cycle. Serum concentrations of immunoactive LH were measured by radioimmunoassay. The biological activity of serum LH was determined by an in-vitro bioassay that uses LH-induced testosterone production from mouse interstitial cells as an endpoint. Only ovine and bovine LH and hCG had appreciable activity in this bioassay. The temporal pattern of secretion of bioactive LH paralleled the secretory pattern of immunoactive LH at all stages of the ovine oestrous cycle. However, the secretory pattern itself varied regularly through the oestrous cycle. The frequency of secretory excursions of LH was highest during the follicular phase (6.2 +/- 0.9 pulses/6 h) and was progressively reduced through the luteal phase (1.1 +/- 0.1 pulses/6 h during full luteal phase). Conversely, amplitude of secretory excursions of immunoactive LH was low during the follicular phase (0.79 +/- 0.08 ng/ml) and significantly (P less than 0.05) increased during the mid- and full luteal phases (1.49 +/- 0.10 and 2.37 +/- 0.20 ng/ml, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Non-tolerance and autoantibodies to a transgenic self antigen expressed in pancreatic beta cells

Transgenic mice expressing simian virus 40 T antigen under control of the insulin gene regulatory region vary in their response to this protein. Each lineage is characteristically either tolerant to T antigen, or not, in which case autoantibodies arise with high frequency, and lymphocytes infiltrate and disrupt the pancreatic islets. Both non-tolerance and the autoimmune response appear to result from delayed onset of T antigen expression during beta cell development.

Gonadotropin-releasing hormone (GnRH) receptor dynamics and gonadotrope responsiveness during and after continuous GnRH stimulation

Gonadotrope responsiveness, serum and tissue levels of luteinizing hormone (LH), and tissue concentration of gonadotropin-releasing hormone (GnRH) receptors in ovariectomized rats were determined during and after continuous GnRH stimulation. Intraperitoneal placement of GnRH-containing osmotic minipumps for 96 h established a rate of GnRH delivery (1 microgram/h) that resulted in stable serum levels of GnRH (500-700 pg/ml). Secretion of LH increased 8-fold within 6 h; however, serum LH returned to pretreatment levels by 24 h, even with continued GnRH stimulation. Tissue concentration of LH was depressed within 48 h of initiation of treatment but levels were restored by 96 h. Tissue levels of GnRH receptor remained elevated during the first 6 h of treatment but were reduced by 60% within 24 h and remained depressed for the duration of treatment. Gonadotrope responsiveness 48 h and 96 h after initiation of treatment was reduced by 50% and 90%, respectively. Removal of the GnRH delivery vehicle resulted in rapid disappearance of GnRH from serum. Dramatic reduction (75%) in circulating levels of LH, and a 2-fold increase in tissue levels of LH and in GnRH receptor concentration were noted within 6 h of minipump removal. Although tissue concentration of GnRH receptor returned to pretreatment levels within 48 h of minipump removal, both basal LH secretion and gonadotrope responsiveness remained depressed even 96 h after cessation of continuous GnRH stimulation. These data indicate that GnRH can "down regulate" its receptor, gonadotrope responsiveness is not obligatorily linked to receptor concentration, and desensitization that follows hyperstimulation represents effects directed at post-receptor loci.

Gonadotrope function in ovariectomized ewes actively immunized against gonadotropin-releasing hormone (GnRH)

The gonadotrope cells of the ovine anterior pituitary were insulated from hypothalamic inputs by imposing an immunologic barrier generated by active immunization of ovariectomized ewes against gonadotropin-releasing hormone (GnRH) conjugated to keyhole limpet hemocyanin (KLH) through a p-aminophenylacetic acid bridge. All GnRH-KLH animals immunized developed titers of anti-GnRH that exceeded 1:5000. The antisera were specific for GnRH and cross-reacted with GnRH agonists modified in position 10 to an extent that was less than 0.01%. Ewes actively immunized against GnRH-KLH displayed levels of basal and GnRH agonist-induced gonadotropin secretion that were markedly lower (p less than 0.05) than comparable parameters in ewes actively immunized against KLH. In contrast, basal and thyrotropin-releasing hormone (TRH)-induced prolactin (PRL) secretion were not compromised by active immunization. Immunization against the GnRH-KLH conjugate, but not KLH alone, prevented expression of the positive feedback response to exogenous estradiol (E2). Pituitary stores of immunoactive luteinizing hormone (LH) and follicle-stimulating hormone (FSH) were significantly (p less than 0.001) reduced in ewes immunized against GnRH-KLH but stores of PRL were not affected by such immunization. Further, the biopotency of the residual LH stores in tissue of animals from the anti-GnRH group was significantly (p less than 0.05) lower than LH biopotency in anti-KLH animals. Serum levels of LH in anti-GnRH ewes were restored by circhoral administration of a GnRH agonist that did not cross-react with the antisera generated. Pulsatile delivery of GnRH agonist in anti-GnRH ewes significantly (p less than 0.05) elevated serum LH within 48 h and reestablished LH levels comparable to anti-KLH ewes within 6 days of treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Exercise performance of subjects with ankylosing spondylitis and limited chest expansion

To examine the mechanism of exercise limitation associated with chest wall restriction (CWR), we compared the ramp (1 W/3 s) exercise performance of six untrained subjects with ankylosing spondylitis (AS) and six healthy subjects matched for age and body size. Subjects with AS had CWR (maximum rib cage expansion : 1.4 +/- 0.2 cm; means +/- sem). The maximum oxygen uptake (VO2max) of AS subjects (2.15 +/- 0.2 1-stpd) was less than their predicted VO2max (2.68 +/- 0.13 1-stpd; p less than 0.03) and the measured VO2max of matched healthy subjects (2.78 +/- 0.22 1-stpd; p less than 0.03). Subjects with AS achieved 95 percent of predicted maximum heart rate, and their maximum voluntary ventilation exceeded their maximum exercise ventilation by at least 15 l X min-1 unless parenchymal pulmonary disease was present. We conclude that maximum ramp exercise performance of AS subjects with CWR is decreased. Deconditioning or cardiovascular impairment rather than ventilatory impairment appears responsible for the observed reduction of VO2max.

Molecular cloning and in vitro expression of a cDNA clone for human cellular tumor antigen p53

Three clones for the human tumor antigen p53 were isolated from a cDNA library prepared from A431 cells. One of these clones, pR4-2, contains the entire coding region for human p53. This clone directs the synthesis of a polypeptide with the correct molecular weight and immunological epitopes of an authentic p53 molecule in an in vitro transcription-translation reaction. Although the pR4-2 clone contains the coding region for p53, it is not a full-length copy of the human p53 mRNA. Northern analysis showed that the p53 mRNA is approximately 2,500 nucleotides long, whereas the pR4-2 insert is only 1,760 base pairs in length. Analysis of the DNA sequence of this clone suggests that the human p53 polypeptide has 393 amino acids. We compared the predicted amino acid sequence of the pR4-2 clone with similar clones for the mouse p53 and found long regions of amino acid homology between these two molecules.

A monoclonal antibody that detects HLA-D region antigen in routinely fixed, wax embedded sections of normal and neoplastic lymphoid tissues

We describe the use of a monoclonal antibody (TAL-IB5) to HLA-D region alpha-chains that reacts well with HLA-D positive cells in normal and neoplastic lymphoid tissues fixed in routine fixatives and embedded in paraffin wax in the conventional fashion. This antibody should prove to be useful in routine histological investigations of lymphoid and possibly other neoplasms as well as other non-neoplastic conditions where the immune system plays an important part.

Biochemical and functional evidence that an MT3 supertypic determinant defined by a monoclonal antibody is carried on the DR molecule on HLA-DR7 cell lines

A cytotoxic monoclonal antibody, PL3, was produced by immunizing mice with a cell line homozygous for the HLA class II antigenic specificity DR7. The serologic specificity of PL3 was completely concordant with the MT3 supertypic specificity, which is tightly associated with HLA-DR4, -DR7, and -DRw9. This was confirmed by the finding that F(ab')2 fragments of PL3 blocked the cytotoxicity of anti-MT3 alloantisera. Although PL3 bound to each of the MT3-positive cell lines, it showed significantly weaker binding to HLA-DR4 and -DRw9 cells relative to -DR7 cells, both in titration and in quantitative absorption assays. This differential pattern of binding was not found for the polyclonal MT3 alloantisera, suggesting that the PL3 determinant may be one of several closely related determinants that comprise the MT3 allospecificity. To identify which of the subpopulations of class II molecules carry the PL3 determinant, several approaches have been used. F(ab')2 fragments of PL3 which block the anti-MT3 alloantisera were also tested with anti-MB2 and anti-DR7 sera. Binding of the PL3 F(ab')2 fragments to DR7 homozygous target cells had no effect on the anti-MB2 sera, but significantly enhanced the cytotoxic reactivity of some anti-DR7 sera. This finding suggested that the PL3 determinant is distinct from the DR7 determinant, but is carried on the same molecule. PL3 was also used in blocking studies with allocytotoxic T cell clones which only recognize DR7-positive cell lines. Binding of PL3 to the DR7-positive target cells was found to completely inhibit these T cell clones. Complete blocking was also found with a monoclonal antibody, PL8, which recognizes a monomorphic determinant found on the DR subpopulation of class II molecules. This finding suggested that the PL3 determinant is carried on the same molecule that carries these T cell-defined DR7 allodeterminants. In biochemical studies with DR7-positive cell lines, PL3 and PL8 were found to immunoprecipitate the same subpopulation of class II molecules recognized by other DR-specific antibodies, SG157 and TAL-1B5. Two-dimensional gel analysis demonstrated that the pattern of alpha- and beta-chains immunoprecipitated by PL3, PL8, and TAL-1B5 were identical. In sequential immunoprecipitation studies, both PL3 and TAL-1B5 were capable of removing the same DR subpopulation of molecules recognized by PL3, PL8, TAL-1B5, or SG157 while leaving the additional class II molecules (DS) recognized by SG171 on DR7 cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Biochemical and functional evidence that an MT3 supertypic determinant defined by a monoclonal antibody is carried on the DR molecule on HLA-DR7 cell lines

A cytotoxic monoclonal antibody, PL3, was produced by immunizing mice with a cell line homozygous for the HLA class II antigenic specificity DR7. The serologic specificity of PL3 was completely concordant with the MT3 supertypic specificity, which is tightly associated with HLA-DR4, -DR7, and -DRw9. This was confirmed by the finding that F(ab')2 fragments of PL3 blocked the cytotoxicity of anti-MT3 alloantisera. Although PL3 bound to each of the MT3-positive cell lines, it showed significantly weaker binding to HLA-DR4 and -DRw9 cells relative to -DR7 cells, both in titration and in quantitative absorption assays. This differential pattern of binding was not found for the polyclonal MT3 alloantisera, suggesting that the PL3 determinant may be one of several closely related determinants that comprise the MT3 allospecificity. To identify which of the subpopulations of class II molecules carry the PL3 determinant, several approaches have been used. F(ab')2 fragments of PL3 which block the anti-MT3 alloantisera were also tested with anti-MB2 and anti-DR7 sera. Binding of the PL3 F(ab')2 fragments to DR7 homozygous target cells had no effect on the anti-MB2 sera, but significantly enhanced the cytotoxic reactivity of some anti-DR7 sera. This finding suggested that the PL3 determinant is distinct from the DR7 determinant, but is carried on the same molecule. PL3 was also used in blocking studies with allocytotoxic T cell clones which only recognize DR7-positive cell lines. Binding of PL3 to the DR7-positive target cells was found to completely inhibit these T cell clones. Complete blocking was also found with a monoclonal antibody, PL8, which recognizes a monomorphic determinant found on the DR subpopulation of class II molecules. This finding suggested that the PL3 determinant is carried on the same molecule that carries these T cell-defined DR7 allodeterminants. In biochemical studies with DR7-positive cell lines, PL3 and PL8 were found to immunoprecipitate the same subpopulation of class II molecules recognized by other DR-specific antibodies, SG157 and TAL-1B5. Two-dimensional gel analysis demonstrated that the pattern of alpha- and beta-chains immunoprecipitated by PL3, PL8, and TAL-1B5 were identical. In sequential immunoprecipitation studies, both PL3 and TAL-1B5 were capable of removing the same DR subpopulation of molecules recognized by PL3, PL8, TAL-1B5, or SG157 while leaving the additional class II molecules (DS) recognized by SG171 on DR7 cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Production and characterization of monoclonal antibodies recognizing the alpha-chain subunits of human ia alloantigens

Two monoclonal antibodies, TAL-1B5 and TAL-3C3, specific for human Ia alpha-chain subunits have been produced by fusing P3/NSI/1-Ag4-1 mouse myeloma cells with spleen cells from a BALB/c mouse immunized with purified alpha-chains. Specificity for the alpha-chain subunits was initially established using a solid-phase radioimmunoassay. Indirect binding assays demonstrated that TAL-1B5 bound strongly to all human B lymphoblastoid lines tested and to CLLs, but only weakly to PBL-B cells and not to PBL-T cells or the T-cell lines Molt 4 and HSB-2. TAL-3C3 bound only weakly to B lymphoblastoid lines and not to CLLs or PBL-B cells. From 125I cell surface-labelled lysates TAL-1B5 immunoprecipitated a 33,000(alpha):28,000(beta) Ia dimer, but TAL-3C3 failed to immunoprecipitate cell surface molecules. Under denaturing conditions, however, both TAL-1B5 and TAL-3C3 immunoprecipitated the 33,000 alpha-chain subunit. Competitive inhibition studies demonstrated that both monoclonal antibodies recognize the same or spatially related alpha-chain antigenic determinants with some slight cross-reactivity against beta-chains. 2D-NEPHGE/SDS-PAGE analysis of TAL-1B5 immunoprecipitates from [35S]-methionine biosynthetically labelled cells revealed the presence of a number of alpha-chain spots in association with beta-chain products of three previously described loci (beta-1, beta-2, beta-3) suggesting that this antibody recognizes an antigenic site common to those human Ia alpha-chains so far identified.

Copper supplementation of drinking water for cattle grazing molybdenum-rich pastures

A field trial was carried out with young cattle grazing molybdenum-rich pastures to test the efficacy of supplying copper salts in drinking water. One group was given two copper injections and 1.8 kg barley supplemented with 125 mg/kg copper, while the other received drinking water containing 2 to 3 mg/litre copper as copper sulphate supplied by means of a proportioner. The results demonstrated that this low concentration of copper in the water was effective in maintaining normal blood levels and in preventing scouring and subsequent loss of condition. The proportioner was capable of finely controlling the level of copper added to the water.

Dopamine: effects on prolactin and luteinizing hormone secretion in ovariectomized rhesus macaques after transection of the pituitary stalk

Luteinizing hormone (LH) and prolactin (PRL) levels were compared in the serum of ovariectomized rhesus macaques (Macaca mulatta) with pituitary-intact (PI) and surgically transected pituitary stalks (SS). After stalk sectioning, LH levels declined and PRL levels rose dramatically. Chronic infusion of intermittent pulses of gonadotropin-releasing hormone (GnRH; 1 microgram/min for 6 of every 60 min) into SS females reinitiated LH secretion within a few days despite increased PRL secretion. Continuous infusion of dopamine (10 micrograms/min/kg of body weight) for 9 days suppressed PRL levels in GnRH-infused SS females to near normal without alteration in basal serum LH levels or pulsatile LH release. A comparable dopamine regimen also failed to modify serum LH patterns in PI monkeys. Immediately after cessation of dopamine, serum PRL levels rose sharply in both PI and SS animals. Injection of estradiol benzoate (42 micrograms/kg of body weight) into SS monkeys receiving GnRH infusions resulted initially in LH suppression and then in LH release. However, the magnitude of LH release was less and the latency to its onset was longer in SS animals given estrogen than in PI controls with similar serum estrogen concentrations. It is unclear whether the atypical pattern of the estrogen-induced LH release in SS monkeys was due to hyperprolactinemia or other deficiencies in this GnRH-infused model. However, these data indicate that the response of gonadotropes to GnRH stimulation was not altered by a direct action of either PRL or dopamine on the pituitary gland. Conversely, dopamine directly suppressed the lactotrope, which became hypersecretory immediately upon dopamine withdrawal. We have concluded that estrogen-induced inhibition and subsequent augmentation of LH release represents a direct action at a pituitary locus, although effects at additional, nonpituitary loci are not precluded.

Ewe luteal function influenced by pulsatile administration of synthetic LHRH/FSHRH

The influence of repetitive administration of synthetic LHRH/FSHRH or saline (S) on 17beta-estradiol (E2)-induced precocious luteal regression in the ewe was examined. Ewes were pre-treated on days 10 and 11 of the estrous cycle with either 750 mug E2 (total dose = 1.5 mg) in oil or with oil (O) alone. Treatment involved in delivery of 10 mug of synthetic LHRH/FSHRH in saline or an equal volume of saline only, administered at 2-h intervals beginning on day 12 of the estrous cycle and continuing through the succeeding 72 hours. During the period of LHRH administration, the serum LH patterns in the O-LHRH and E2-LHRH groups were characterized by rhythmic fluctuation, rising in response to LHRH and falling prior to the subsequent treatment injection. Throughout the course of the treatment period, the serum LH levels in the O-LHRH group were consistently higher than those in the E2-LHRH group. No increase in serum LH concentration was observed in the saline-treated animals. The mean luteal weight and mean luteal progesterone content at the end of the 72-h period were not significantly different between the O-S and E2-LHRH groups (543 +/- 88 vs. 455 +/- 126 mg and 13.1 +/- 6.2 vs 16.0 +/- 9.7 mug, respectively). Both luteal weight and progesterone content were increased (P less than .01) in the O-LHRH group (1089 +/- 87 mg and 47.5 +/- 3.1 mug) and significantly reduced (P less than .05) in the E2-S group (309 +/- 49 mg and 5.2 +/- 0.1 mug) compared with those of either the O-S group or the E2-LHRH group. Thus LHRH treatment increased mean luteal weight and mean luteal progesterone content while E2 pre-treatment depressed the same parameters. These data suggest that pulsatile administration of synthetic LHRH is able to elevate serum LH levels to an extent sufficient to counteract both natural luteolysis and premature luteal regression induced by E2 treatment.