Biomedical subjects

P J Sharp

Publications and source records attributed to P J Sharp.

At least 109 records · Page 6Linked to original sources

PubMed1990

Effects of interactions between photostimulation, dietary restriction and dietary maize oil dilution on plasma LH and ovarian and oviduct weights in broiler breeder females during rearing.

1. The response of the reproductive system to photostimulation was investigated during the rearing period in dwarf broiler breeder females maintained from hatch on 8 h light/d. The effect of increased body fat on this response was investigated. Body fat was increased by diluting the diet with maize oil. 2. A significant increase in plasma luteinising hormone (LH) was observed 4 d after photostimulation with 20 h light/d at 3 and 15 weeks of age in birds fed the restricted diet alone and at 3, 7, 11, 15 and 19 weeks of age in birds fed the restricted diet diluted with maize oil. 3. Increases in ovarian weight were observed two weeks after photostimulation at 15 weeks of age in birds fed the restricted diet alone and at 7, 11 and 15 weeks of age in birds fed the restricted diet diluted with maize oil. Increases in oviduct weight were seen after photostimulation at 11, 15 and 19 weeks of age in both dietary treatment groups; however, a larger increase in oviduct weight was seen at 15 and 19 weeks of age in birds fed the restricted diet diluted with maize oil. 4. In a second experiment, the dilution of a diet fed ad libitum with maize oil significantly increased body fat content and the baseline concentration of LH but did not enhance the response of the reproductive system to photostimulation. 5. Baseline plasma LH concentrations were lower in birds fed ad libitum than in those fed a restricted diet. 6. It is concluded that the neuroendocrine pathways involved in the transmission of photoperiodic information are functional at 3 weeks of age. The function of the components of the hypothalamo-pituitary complex which control reproductive activity is enhanced when a restricted diet diluted with maize oil is fed.

Animals↗

PubMed1990

Expression and secretion in Aspergillus nidulans and Aspergillus niger of a cell surface glycoprotein from the cattle tick, Boophilus microplus, by using the fungal amdS promoter system.

A cell surface glycoprotein (Bm86) from cells of the digestive tract of the cattle tick Boophilus microplus, which has been shown to elicit a protective immunological response in vaccinated cattle, was expressed and secreted in the filamentous fungi Aspergillus nidulans and Aspergillus niger by using the fungal amdS promoter system. The cloned gene coded for the Bm86 secretory signal and all of the Bm86 mature polypeptide except for the hydrophobic carboxy-terminal segment. High levels of Bm86 mRNA were detected in the transformed cells. Bm86 polypeptide was secreted from the cells in a soluble form and it was glycosylated, probably to a similar extent to the native glycoprotein. The recombinant product had an apparent molecular mass of 83 to 87 kilodaltons, whereas that predicted from the amino acid sequence was 69 kilodaltons. The Bm86 was expressed at levels of up to 1.8 mg/liter, or approximately 6% of secreted protein under the growth conditions used. No intracellular Bm86 was detected. A general relationship was observed between transformants containing a high number of copies of the expression plasmid and high expression levels.

Animals↗

PubMed1990

Photoperiodic requirements for LH release in juvenile broiler and egg-laying strains of domestic chickens fed ad libitum or restricted diets.

Photoperiodic response curves for LH release were obtained for juvenile female domestic chickens at 8 weeks of age by measuring changes in plasma LH concentrations after increasing the daily photoperiod from 8 to 10.5, 12.75, 15.25, 17.75 or 20 h. The birds were bred either for meat production (broiler) or commercial egg-laying and were fed ad libitum or a restricted diet, similar to that used under commercial conditions. Ovarian and oviduct growth was stimulated by 2 weeks after transfer to 20 h light/day in the dwarf broiler strain, irrespective of the dietary treatment, but not in birds of the egg-laying strain. Baseline concentrations of plasma LH were higher in the egg-laying than in the dwarf broiler strain birds. A significant effect of dietary treatment was observed on the changes in concentration of plasma LH in the nonphotostimulated dwarf broiler, but not in the egg-laying bird. There was no significant interaction between dietary treatment and photoinduced LH release in birds of either strain. The shortest photoperiod needed to stimulate LH release (critical daylength) was less than 10.5 h in the dwarf broilers and between 10.5 and 12.75 h in the egg-laying birds. The shortest photoperiod needed to stimulate the maximum release of LH (saturation daylength) was between 10.5 and 12.75 h in the dwarf broiler strain. The saturation daylength in birds of the egg-laying strain was longer, being between 12.75 and 15.25 h.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1990

Physiological roles of chicken LHRH-I and -II in the control of gonadotrophin release in the domestic chicken.

The physiological roles of chicken LHRH-I and -II (cLHRH-I and -II) in the regulation of gonadotrophin release were investigated in the domestic chicken. Measurements of the neuropeptides, using specific radioimmunoassays, in brain sections cut in three planes or in grossly dissected brain areas, showed that cLHRH-II occurs in low amounts throughout the brain whereas cLHRH-I is most abundant in the diencephalon. Within the diencephalon, the largest amount of cLHRH-I occurred in the median eminence of the hypothalamus. The amount of cLHRH-I in the median eminence was higher (P less than 0.05) in laying than in out-of-lay hens. No cLHRH-II was detected in the median eminence in either reproductive state. The amount of cLHRH-I in the hypothalamus was increased (P less than 0.05) in cockerels at the onset of puberty and in somatically immature birds after castration. There were no correlated changes in the amounts of hypothalamic cLHRH-II measured in the same experimental samples. Active immunization of laying hens against cLHRH-I but not against cLHRH-II resulted in the complete regression of the reproductive system and a depression in the concentration of plasma LH. These observations, taken together, suggest that gonadotrophin secretion in the hen is more likely to be directly regulated by cLHRH-I than by cLHRH-II.

Animals↗

PubMed1989

Evidence for the involvement of dopamine and 5-hydroxytryptamine in the regulation of the preovulatory release of luteinizing hormone in the domestic hen.

Injections of the dopamine (DA) precursor L-dopa and the 5-hydroxytryptamine (5-HT) precursor 5-hydroxytryptophan, beginning 6 hr before the predicted preovulatory release of LH, abolished the LH surge and blocked ovulation. The inhibitory effect of the drugs on the preovulatory release of LH was not reversed by injection of progesterone. This showed that the drugs inhibited LH release by acting on the central nervous system rather than peripherally, by inhibiting the release of progesterone from the ovary. The turnover rates of DA and 5-HT were estimated during the ovulatory cycle in the median eminence, the posterior hypothalamus, and the anterior hypothalamus. The turnover rates of the two monoamines were estimated from their rates of accumulation after inhibiting their catabolism with the monoamine oxidase inhibitor pargyline. Turnover of DA and 5-HT in the median eminence was depressed during the preovulatory release of LH and decrease in the anterior hypothalamus when preovulatory LH levels were increasing. Observations were also made of changes in the concentrations of hypothalamic DA, 5-HT, noradrenaline (NA), and adrenaline (A) during the ovulatory cycle. Concentrations of DA, 5-HT, and NA increased in the anterior hypothalamus and decreased in the posterior hypothalamus during the 4 hr before the peak of the preovulatory release of LH. These results strengthen the view that hypothalamic DA and 5-HT play a role in the regulation of the preovulatory release of LH by a reduction in inhibitory inputs on LHRH neurones.

Animals↗

PubMed1989

Concentrations of plasma prolactin and luteinizing hormone following nest deprivation and renesting in ring doves (Streptopelia risoria).

Ring doves with increased plasma prolactin and low plasma LH (Group A) or with low plasma prolactin and low plasma LH (Group B) which had been incubating sterile eggs for 12 or 18 days, respectively, had their nests and eggs removed for 3 days. Upon nest return, observations were made on the birds' readiness to renest and on changes in plasma prolactin and LH. Birds from Group A demonstrated a far greater tendency to resume incubation than birds from Group B. Nest deprivation resulted in a sharp fall in the concentration of plasma prolactin in birds which were deprived of their nests after 12 days of incubation (Group A). Following resumption of incubation no subsequent increase in the prolactin levels was observed in Group A or B. The concentration of plasma LH rose sharply after nest deprivation in both sexes of both groups and declined after return of the nests. Birds in Groups A and B which returned to their nests laid a new clutch of eggs while continuing to incubate. The total length of uninterrupted sitting following nest return was 20.9 +/- 0.48 days (n = 8). These results suggest that (1) once the mechanism responsible for the increase in plasma prolactin during incubation is disrupted, it cannot be reactivated unless the whole reproductive cycle is repeated. (2) The inhibition of LH secretion during incubation involves neural mechanisms which do not necessarily involve the anti-gonadotrophic action of prolactin.

Animals↗

PubMed1989

A basic phospholipase A from the venom of the Australian king brown snake (Pseudechis australis) showing diverse activities against membranes.

1. A basic phospholipase A (MSPA) was isolated from the venom of the Australian king brown snake, Pseudechis australis. 2. MSPA had an approximate Mr of 13,000 and consisted of a single polypeptide chain of 119 amino acid residues cross-linked by seven disulphide bridges. 3. MSPA exhibited direct haemolytic, anticoagulant and myotoxic activities. 4. Treatment of MSPA with p-bromophenacyl bromide modified a single histidine residue, resulting in complete loss of enzyme activity.

Acetophenones↗

PubMed1989

Molecular cloning and sequence analysis of putative chicken prolactin cDNA.

A cDNA library was prepared from mRNA isolated from anterior pituitary glands of incubating bantam hens, in which prolactin mRNA levels were predicted to be very high. Nine clones, representing abundant mRNA species, were identified and shown to contain homologous sequences. Two clones, of 871 bp and 580 bp, were analysed by DNA sequencing. The shorter clone was found to be a truncated cDNA product but otherwise identical to the longer clone. The 871 bp cDNA, PRL101, contains an open reading frame capable of encoding a polypeptide of 229 amino acids. This putative polypeptide has a high degree of homology to mammalian prolactins (approximately 70%), strongly suggesting that PRL101 encodes chicken preprolactin. The protein was predicted to have a 30 amino acid signal sequence which would be cleaved off to give a mature protein of 199 amino acids. The peptide sequence also had a 26% homology to chicken growth hormone, which is related to prolactin. This similarity confirms the conclusion that PRL101 is a chicken prolactin cDNA clone. An abundant mRNA of approximately 880 b was detected in poly(A)+ RNA from pituitary glands probed with PRL101. Analysis of chicken genomic DNA showed that there is one copy of the prolactin gene in the genome. PRL101 hybridized strongly to genomic DNA from closely related galliforms (quail and turkey) and less strongly to DNA from more distantly related species (duck and ring dove).

Amino Acid Sequence↗

PubMed1989

The functional activity of hypothalamic 5-hydroxytryptamine neurones in broody bantam hens.

An assessment was made of the possible role of hypothalamic 5-hydroxytryptamine (5-HT) in the regulation of prolactin secretion in broody bantam hens. Prolactin secretion was stimulated less in incubating hens deprived of their nests for 24 h (nest-deprived) than in laying hens after administration of the 5-HT receptor agonist quipazine, or precursor 5-hydroxytryptophan. One type of 5-HT-binding site was found in the anterior and posterior hypothalami of out-of-lay, incubating and laying hens. Differences in prolactin secretion in these birds could not be accounted for by changes in the abundance of this type of 5-HT-binding site. Another type of 5-HT-binding site, with a higher density but lower affinity, was found in the anterior hypothalami of laying hens. No specific 5-HT-binding sites were found in the anterior pituitary gland. The turnover rates of 5-HT were compared in the anterior and posterior hypothalami of laying, incubating and nest-deprived hens. The turnover rates were estimated from the rate of accumulation of 5-HT after inhibiting its catabolism using the monoamine oxidase inhibitor, pargyline, or by measuring the ratio of the concentrations of 5-HT and its major metabolite, 5-hydroxyindole acetic acid. Both methods of measurement gave the same results. The turnover of 5-HT was increased in the anterior but not posterior hypothalami of incubating hens when compared with laying or nest-deprived hens. There was also a significant increase in turnover of 5-HT in the posterior hypothalami in nest-deprived hens when compared with laying or incubating birds.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1989

The functional activity of hypothalamic dopamine in broody bantam hens.

An assessment was made of the possible role of hypothalamic dopamine in the regulation of changes in plasma prolactin and LH in laying and broody bantam hens. Specific dopamine-binding sites were identified, using [3H]domperidone, in the anterior pituitary gland and in the anterior and posterior hypothalamus. The mean concentrations of dopamine-binding sites in both parts of the hypothalamus were 59-66 fmol/mg protein and did not differ between laying and incubating hens. The concentration of dopamine binding sites in the anterior pituitary gland was significantly (P less than 0.001) greater in laying than in incubating hens (278 +/- 46 compared with 420 +/- 32 fmol/mg protein, n = 5). The turnover rates of dopamine were compared in the anterior and posterior hypothalami of laying, incubating and nest-deprived hens. The turnover rates were estimated from the rate of accumulation of dopamine after inhibiting its catabolism using the monoamine oxidase inhibitor, pargyline, or by measuring the ratio of the concentrations of dopamine and its major metabolite, homovanillic acid. Both methods gave the same results. The turnover of dopamine was increased in the anterior but not posterior hypothalamus of incubating hens when compared with laying or nest-deprived hens. These results show, for the first time in birds, that the anterior pituitary gland contains specific binding sites for dopamine and that the concentration of these binding sites is inversely related to the concentration of plasma prolactin. The marked increase in dopaminergic activity in the anterior hypothalamus of incubating hens may stimulate the release of unidentified prolactin-releasing factors and/or inhibit the release of LH by exerting an inhibitory influence in the area of the hypothalamus containing LHRH cell bodies.

Animals↗

PubMed1989

The role of hypothalamic vasoactive intestinal polypeptide in the maintenance of prolactin secretion in incubating bantam hens: observations using passive immunization, radioimmunoassay and immunohistochemistry.

The role of chicken vasoactive intestinal polypeptide (cVIP) as a prolactin-releasing factor was investigated in incubating bantam hens. Specific antibodies were raised against cVIP (anti-cVIP) for passive immunization studies, to develop a radioimmunoassay and to localize VIP neurones immunohistochemically in the hypothalamus. The concentration of plasma prolactin decreased after i.v. injection of anti-cVIP: this low concentration being maintained by daily injection of anti-cVIP. Incubating hens injected daily with anti-cVIP deserted their nests after 4.5 +/- 0.6 days and returned to lay after 20 +/- 1 days. This disruption of incubation behaviour with anti-cVIP was prevented by concomitant, twice daily, injections of 30 IU ovine prolactin. The concentration of plasma LH was not immediately affected after injection of anti-cVIP but increased when the hens deserted their nests. The amount of cVIP, measured by radioimmunoassay, was significantly higher in the median eminence (P less than 0.01) and medial basal hypothalamus (P = 0.05) in incubating than in laying hens. No differences were seen in the amounts of cVIP in the preoptic hypothalamus or in a part of the forebrain including the nucleus accumbens, between laying and incubating hens. Morphological observations were made on immunohistochemically identified cVIP cell bodies in the medial basal hypothalamus. These showed that cVIP cell number, cell area and density of immunoreactive product were significantly (P less than 0.05) greater in incubating than in laying hens. Further, the density of cVIP reaction product in the anterior median eminence was also significantly (P less than 0.01) greater in incubating than in laying hens.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1989

Sex differences in body weight of chicken embryos.

Experiments were conducted to determine if sex differences in body weight of chickens exist prior to hatching and to determine if growth of twin embryos is affected by the sex of their siblings. The mean wet BW of male embryos was significantly greater than that of females at 11, 13, and 18 days of incubation, whether expressed on an absolute basis or as a percentage of egg weight. The mean dry weight of male embryos was not different from that of females at 11 days of incubation. Male dry weights were not different from female weights at 13 days of incubation in one experiment (P = .540) but approached significance (P = .078) at this age in another experiment. The mean dry weight of males was significantly greater than that of females at 18 days of incubation. Vascular anastomoses between twin embryos in double yolk eggs were demonstrated by the exchange of 125I between the twins. Fifteen-day-old twin embryos in double-yolked eggs were significantly lighter than single embryos developing in double-yolked eggs. Female embryos twinned with females were slightly but not significantly lighter than males twinned with males. Mixed sex twins tended to be lighter than unisex twins. Females twinned with males were significantly lighter than males twinned with males. The data do not support the concept that a male humoral factor is responsible for more rapid growth of male embryos.

Animals↗

PubMed1988

Steroidogenic relationships of gonadotrophin hormones in the ovary of the hen (Gallus domesticus).

The effects of chicken luteinizing hormone (cLH: IRC-2 and PRC AE1-1), turkey LH (B221B and HS-5-18), bovine follicle-stimulating hormone (bFSH: HS-2-17), chicken FSH (cFSH: PRC DC3(2) and AGCQSQ113445C), and turkey FSH (B150A and HS-1-153) on steroid output were evaluated by in vitro incubation of various ovarian tissues with the gonadotrophins. Output of androstenedione and estradiol was determined by 3-hr incubations of individual whole small follicles, classified by size and color as follows: small white (SWF, less than 1 mm), large white (LWF, 2-3 mm), and small yellow follicles (SYF, 5-10 mm). The effects of gonadotrophin preparations were also evaluated in large preovulatory follicles (F1-F5). Androstenedione and estradiol output was measured in incubation media from 100,000 theca cells and progesterone content was determined in the incubation media of 100,000 granulosa cells. All incubations were conducted in 1 ml of Medium 199 at 37 degrees. Steroid output was quantitated by radioimmunoassay of incubation media. Potency estimates were derived by calculation of a peak stimulation index. The standard reference preparation was bLH (NIAMDD-LH-B4). Steroidogenesis was stimulated by three avian LH preparations. preparations. PRC AE1-1 was the most potent, with IRC-2 and B150A showing approximately 50% of the biological activity of PRC AE1-1 in most tissues. Turkey LH HS-5-18 was generally not potent. The presence of multiple isohormones of LH was implied, as various LH preparations exhibited different potency estimates in different tissues. The effects of FSH on steroidogenesis were not significant in most cases. Although the addition of cFSH AGCQSQ113445C failed to significantly increase output of estradiol from small follicles, potency estimates of this preparation were 0.15, 0.20, and 0.13 relative to NIAMDD-LH-B4 follicles was more highly stimulated by LH than by FSH, and thus it would seem that FSH does not play a significant role in steroidogenesis in the hen's ovary. The results of this study suggest that steroid biosynthesis in the hen's ovary may be regulated by multiple forms of LH.

Androstenedione↗

PubMed1988

Endocrine changes in photostimulated willow ptarmigan (Lagopus lagopus lagopus) and Svalbard ptarmigan (Lagopus mutus hyperboreus).

Changes in plasma luteinizing hormone (LH), testosterone, thyroxine (T4), and triiodothyronine (T3) and the height of supraorbital combs were compared in captive willow ptarmigan (Lagopus lagopus lagopus) and Svalbard ptarmigan (Lagopus mutus hyperboreus) exposed to an artificial annual cycle of daylength simulating that at 70 degrees N. Plasma LH and testosterone and comb height increased more slowly in Svalbard than in willow ptarmigan as daylength increased. In both species, plasma LH and testosterone fell abruptly, and the supraorbital combs regressed in June, marking the development of long-day refractoriness. Comparison with free-living Svalbard ptarmigan (K.-A. Stokkan, P. J. Sharp, and S. Unander (1986) Gen. Comp. Endocrinol. 61, 446-451) at 80 degrees N, showed a similar slow increase in reproductive function before the onset of the breeding season. However, maximum plasma LH levels and comb size were higher in free-living than in captive Svalbard ptarmigan. Furthermore, long-day refractoriness developed earlier in captive than in free-living Svalbard ptarmigan. In both species of ptarmigan, the development of long-day refractoriness was associated with increased plasma prolactin. This increase was larger and occurred earlier in the Svalbard than in the willow ptarmigan. Seasonal changes in thyroid hormones were not as marked as for the other hormones measured. In both species, plasma T4 tended to increase and plasma T3 to decrease as daylength increased. A small increase in plasma T3 was seen after the development of long-day refractoriness in both species. It is concluded that captivity depresses the photoperiodic response of Svalbard ptarmigan more than that of willow ptarmigan.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1988

Environmental and hormonal factors in seasonal breeding in free-living male Indian rose-ringed parakeets (Psittacula krameri).

Seasonal changes in testicular activity, plasma luteinizing hormone (LH), estradiol (E2), testosterone (T), and 5 alpha-dihydrotestosterone (5 alpha-DHT) were related to pair bond formation, nest building, nest defense, and parental behavior in free-living Indian rose-ringed parakeets (Psittacula krameri) in northwest India. Spermatozoa production occurred between January and March when daylengths were short (10-12 hr) and ambient temperature was seasonally low (8-20 degrees C). At other times of the year the testes were regressed. Plasma LH levels increased during the prebreeding period (September-December) when the birds were forming pairs and selecting or defending nest sites. Plasma LH levels increased further between January and March and decreased to seasonal low values during the post breeding period between April and June when the birds were caring for young. Concentrations of plasma androgens and estrogens were similar during the prebreeding and postbreeding phases of the breeding cycle. During the breeding period, the ratios between plasma 5 alpha-DHT and testosterone and between plasma estradiol and testosterone increased. It is proposed that the absence of marked seasonal changes in plasma steroid levels is related to nest defense behavior which occurs during the prebreeding, breeding, and postbreeding phases of the breeding cycle. Winter breeding makes it possible for the parakeets to avoid competition with other birds for nesting sites, to avoid fledging young during the monsoon period, and to take advantage of the winter pea crop which provides the female with extra nutrients for egg production.

Animals↗

PubMed1988

Environmental, dietary, and hormonal factors in the regulation of seasonal breeding in free-living female Indian rose-ringed parakeets (Psittacula krameri).

The roles of environmental, dietary, and hormonal factors in the timing of seasonal breeding were assessed in free-living female Indian rose-ringed parakeets, Psittacula krameri, in northwest India (22 degrees 2'N, 73 degrees E). The ovaries and oviducts began to enlarge in January, were fully developed in February, and began to regress in March. During this time there was no significant change in the concentration of plasma luteinizing hormone (LH) or estradiol. The concentration of plasma LH decreased (P less than 0.01) at the end of the breeding season. Pair bond formation occurred between September and December and was associated with an increase in levels of plasma LH but no change in plasma estradiol. Concentrations of plasma testosterone (T) and 5 alpha-dihydrotestosterone (5 alpha-DHT) did not vary significantly during the year and were similar to those in males except for higher values of 5 alpha-DHT and lower values of T during the pre- and postbreeding periods, respectively. The similar levels of plasma androgens in both sexes may be related to the equal roles that both sexes play in the defence of their nest holes. An analysis of crop sac contents showed that the birds fed chiefly on pigeon peas (Cajanus cajan) during the breeding season and on cereal grains at other times of the year. It is suggested that pigeon peas provide the extra nutrients, including calcium, required for egg production. Since pigeon peas ripen between November and March, the production of the crop may play a role in the timing of seasonal breeding. A further factor appears to be competition for nest sites. By breeding in winter, the parakeet avoids competing with other species which nest in holes.

Animals↗

PubMed1988

An examination of the role of chiasma frequency in the genetic system of marsupials.

Chiasma frequencies have been collected from males of 33 species of marsupial, varying widely with respect to size, reproduction and development. Correlation analyses show that species with lower levels of recombination are smaller, have larger litters and develop more quickly. Two indices of recombination level were considered: Darlington's Recombination Index, and the Excess Chiasma frequency (chiasmata above one per bivalent). The EC is in general more strongly correlated than RI with aspects of life history. It is suggested that EC levels have evolved due to the effects of EC on recombination, but that chromosome number has evolved independently.

Animals↗

PubMed1988

Comparison of the fractionation and assay of domestic duck and fowl pituitary gonadotrophins.

1. Pituitary glycoproteins from domestic ducks and fowls were fractionated to separate luteinising hormone (LH) and follicle stimulating hormone (FSH) activities using the same chromatographic steps. 2. Fractions were bioassayed for LH using the release of progesterone from fowl granulosa cells and for thyroid stimulating hormone (TSH) by measuring the release of thyroxine in 3-d-old chicks. Follicle stimulating hormone activity was measured either in a cockerel-testes radioreceptor assay or by the release of oestrogen from cultured rat Sertoli cells. 3. Fractions containing predominantly FSH or LH activity were isolated from the fowl glycoproteins. Duck gonadotrophin did not occur in fractions corresponding to those containing fowl FSH. 4. Duck gonadotrophin was found in a fraction corresponding with the most highly purified fowl LH fraction. A duck LH fraction was found with little FSH activity for which there was no corresponding fowl LH fraction. 5. It is concluded that domestic fowl and duck gonadotrophins have different chromatographic properties. Further study is required to determine whether the purified duck gonadotrophin preparation comprises proteins with similar physico-chemical properties but with separate FSH and LH biological activities.

Animals↗