Duck Blood Research Articles

PCB exposure in sea otters and harlequin ducks in relation to history of contamination by the Exxon Valdez oil spill

Exposure to contaminants other than petroleum hydrocarbons could confound interpretation of Exxon Valdez oil spill effects on biota at Prince William Sound, Alaska. Hence, we investigated polychlorinated biphenyls (PCBs) in blood of sea otters and harlequin ducks sampled during 1998. PCB concentrations characterized by lower chlorinated congeners were highest in sea otters from the unoiled area, whereas concentrations were similar among harlequin ducks from the oiled and unoiled area. Blood enzymes often elevated by xenobiotics were not related to PCB concentrations in sea otters. Only sea otters from the unoiled area had estimated risk from PCBs, and PCB composition or concentrations did not correspond to reported lower measures of population performance in sea otters or harlequin ducks from the oiled area. PCBs probably did not influence limited sea otter or harlequin duck recovery in the oiled area a decade after the spill.

Immune-related gene expression in response to H11N9 low pathogenic avian influenza virus infection in chicken and Pekin duck peripheral blood mononuclear cells

The duck and chicken are important hosts of avian influenza virus (AIV) with distinctive responses to infection. Frequently, AIV infections in ducks are asymptomatic and long-lasting in contrast to the clinically apparent and transient infections observed in chickens. These differences may be due in part to the host response to AIV infection. Using real-time quantitative PCR, we examined the expression of immune-related genes in response to low pathogenic AIV H11N9 infection in peripheral blood mononuclear cells (PBMC) isolated from the blood of chickens and Pekin ducks. While chicken PBMC expressed IL-1β and IL-6 at high levels similar to mammalian species, duck PBMC expression levels were minimal or unchanged. Similarly, duck IFN-β expression was nearly unaffected, whereas chicken expression was highly upregulated. Chicken IFN-γ was expressed to higher levels than duck IFN-γ, while IFN-α was expressed similarly by both species. IL-2 was elevated early in infection in duck PBMC, but returned to baseline levels by the end of the experiment; in contrast, IL-2 was weakly induced in chicken PBMC at late time points. TLR-7 and MHC class I molecule expressions were conserved between species, whereas duck MHC class II expression was downregulated and chicken expression was unchanged. These results show distinct PBMC expression patterns of pro-inflammatory cytokines and IFNs between species. The differences in pro-inflammatory cytokine and IFN expression reflect the asymptomatic and lasting infection observed in ducks and the tendency towards clinical signs and rapid clearance seen in chickens. These results highlight important differences in the host response to AIV of two species thought to be critical in the genesis and maintenance of epidemic strains of AIV.

Effect of cell mediated immunity regulation of duck enhanced by duck IFN-α eukaryon expression plasmid and inoculated with DPV attenuated vaccine by gene-gun

In order to study the effect of cell mediated immunity regulation of duck IFN-α eukaryon expression plasmid (pcDNA-SDIFN-α) on duck plague virus (DPV) attenuated vaccine in ducks, pcDNA-SDIFN-α was administered to 28-day-old ducks at doses of 1, 3 and 6 μg per duck, respectively, by gene-gun. PBS and empty vector pcDNA were used as control. Fifteen days later, all ducks were injected with DPV attenuated vaccine and blood samples were collected at 3, 7, 14, 21, 28, 35, 49, 63 and 84 days after injection. T-lymphocyte proliferation tests (MTT) were used to detect the T-lymphocyte proliferation in the peripheral blood (PBL) of ducks. Blood samples collected at 7, 14, 21, 28, 35 and 49 days after injection were detected by fluorescence-activated cell sorter (FACS) for recording the number of CD3+ T-lymphocytes of ducks. Results were as follows: (1) Reaction of T-lymphocytes in PBL to ConA (OD value) of ducks treated with pcDNA-SDIFN-α was higher than that of PBS and pcDNA control groups in 3–84 days. There were highly significant differences between the 1 μg per duck group and the two control groups in 3–84 days (P ⩽ (0.01), between the 3 μg per duck group and the two control groups in 3–84 days (P ⩽ 0.01, P ⩽ 0.05), and between the 6 μg per duck group and the two control groups in 7–49 days (P ⩽ 0.01, P ⩽ 0.05). The significant difference was also present between the groups of 1, 3 and 6 μg per duck in 3–35 days (P ⩽ 0.05). However, there was no significant difference between the 3 and 6 μg per duck groups (P ⩾ 0.05). The pcDNA control group was higher than PBS control group, but no difference was detected (P ⩾ 0.05). (2) Change of the number of CD3+ T-lymphocytes in ducks administered with different doses of pcDNA-SDIFN-α was higher than that of PBS and pcDNA control groups in 7–49 days. The change in the 1 μg per duck group was significantly higher than that in PBS and pcDNA control groups in 14–49 days (P ⩽ 0.01). There were significant differences between the 3 μg per duck group and the two control groups in 21–49 days (P ⩽ 0.01, P ⩽ 0.05) and between the 6 μg per duck group and the two control groups in 7–49 days (P ⩽ 0.01, P ⩽ 0.05). However, no significant differences among the groups of 1, 3, and 6 μg per duck groups (P ⩾ 0.05) and between the two control groups (P ⩾ 0.05) were found. The results indicated that pcDNA-SDIFN-α administered 15 days before injection of DPV-attenuated vaccine could significantly enhance cellular immunity induced by DPV-attenuated vaccine. pcDNA-SDIFN-α is an excellent DPV-attenuated vaccine molecular adjuvant and the best result can be obtained with the dose of 1 μg per duck of pcDNA-SDIFN-α inoculated by gene-gun.

Viral Tropism and the Pathogenesis of Influenza in the Mammalian Host

Influenza viruses, single-stranded negative-sense RNA viruses within the family Orthomyxoviridae, remain an important cause of human morbidity and mortality worldwide. Despite effective vaccines, more than 200,000 individuals in the United States are hospitalized each year for influenza, and approximately 35,000 succumb to disease.1 Seasonal epidemics arise through antigenic variation and recombination events from existing and currently circulating human strains, which initially target the upper respiratory tract with extension to a bronchointerstitial pneumonia in a subset of affected individuals. Disease is often more severe in older and debilitated patients, producing a characteristic distribution in age-related mortality within the affected population.2 In contrast to seasonal epidemics, pandemics arise when antigenically novel viruses emerge and are readily transmissible within the naive human population. Such events are rare and occur after zoonotic transmission of viruses through recombination events between established human and avian strains or possibly through direct adaptation of avian strains for efficient human to human transmission.3 Concerns over an avian influenza pandemic have risen since 1997 with the recognition of H5N1 as a cause of fulminant disease in humans.4,5 Pathologically fatal H5N1 causes diffuse alveolar damage and progression to multiple organ dysfunction with a case fatality rate estimated at more than 50%. Although H5N1 disease is severe, transmission rates have been low, and viral adaptation to efficient human to human transmission has not occurred. Understanding viral and host barriers that prevent transmission may be critical in establishing rational control measures as well as predicting and stratifying risk for individual strains of influenza. In this issue of The American Journal of Pathology, van Riel et al6 examine the viral binding distribution in pulmonary tissue of a number of avian and human influenza strains to elucidate the role of tropism in transmission and pathogenesis.

Ceftiofur Distribution in Plasma and Tissues Following Subcutaneously Administration in Ducks

A study was performed to determine the residues in blood and edible tissues of healthy ducks (25 days old, mean body weight 1.0+/-0.13 kg) after subcutaneous administration of ceftiofur sodium at a dose rate of 2 mg/kg body weight (Group I) and 4 mg/kg body weight (Group II). Blood, muscle, liver, kidney, and fat samples were collected from all of ducks on the 1st, 2nd, 3rd, 4th, and 5th day after treatment of drug, and ceftiofur was analyzed with a high-performance liquid chromatography (HPLC) assay with results reported as ceftiofur-free acid equivalent (CFAE). To study the spiked recovery, blank plasma and tissues were spiked with two different concentrations of ceftiofur sodium (0.1, 0.5 microg/g). Average recovery values for all samples ranged from 70.3 to 87.3%. In the group I, desfuroylceftiofur acetamide (DCA) was not detected in all of plasma, muscle, liver, and fat tissues on the 1st day after treatment. But, kidney samples on the 1st day were detected DCA (0.059+/-0.01 microg CFAE/g tissue). On the 2nd day of post-treatment, the concentrations of DCA in all tissues were lower than the detection limit, 0.05 microg CFAE /g tissue. In the group II on the 1st day after treatment, the concentration of DCA was 0.124+/-0.06 microg CFAE/g tissue, 0.103+/-0.03 microg CFAE/g tissue, and 0.071+/-0.010 microg CFAE/g tissue in plasma, kidney, and muscle samples, respectively. On the 2nd day after treatment of ceftiofur, the concentrations of DCA in all tissues were lower than 0.05 microg CFAE/g tissue. According to our results, the concentrations of DCA on the 1st day after treatment with 2 mg/kg body weight were below 0.05 microg CFAE/g tissue equivalent in all tissues except for kidney. On the 2nd day after administration at the dose of 4 mg/kg body weight, no DCA was also detected in all of the tissues although DCA was detected in all samples on the 1st day.

Blood Lead Concentrations in Waterfowl Utilizing Lake Coeur d’Alene, Idaho

The Coeur d'Alene River Basin, Lake Coeur d'Alene, and the Spokane River contain elevated heavy metal concentrations in sediment and water from historical mining and ore processing operations in the Coeur d'Alene Basin. Lead poisoning has been identified as the cause of death in hundreds of waterfowl utilizing wetlands in the floodplain of the Coeur d'Alene River, but little was known about hazards to waterfowl from heavy metal contamination in shallow bays and wetlands of Lake Coeur d'Alene. We examined lake sediment and blood lead concentrations in waterfowl utilizing Lake Coeur d'Alene, Idaho, to evaluate potential lead contamination of waterfowl utilizing the lake. We collected 56 palustrine and 102 lacustrine sediment samples and 61 mallard and 8 wood duck blood samples. Mean lead concentrations from palustrine and lacustrine sediment samples ranged from 14 to 3508 mg/kg dry weight (dw) and from 19 to 5009 mg/kg (dw), respectively. Lead concentrations in palustrine and lacustrine sediment from several Lake Coeur d'Alene bays were higher than those in lake reference areas and were higher than Bunker Hill Superfund Site target cleanup levels and suggested site-specific toxicity thresholds for swans. Mean blood lead from mallard and wood ducks sampled from Lake Coeur d'Alene bays were within lead toxicity ranges for waterfowl associated with clinical and severe clinical lead poisoning. We also collected 19 Canada goose and 3 mallard fecal samples to evaluate exposure through sediment ingestion. Waterfowl using Lake Coeur d'Alene appear to be exposed to lead by ingesting contaminated lake sediment. Our model predicts a sediment lead effects range of 147-944 mg/kg (dw) and mortality effects level of 1652 mg/kg (dw) for mallards utilizing Lake Coeur d'Alene. The locations of Harrison Slough, Powderhorn Bay, and Cottonwood Bay at the mouth of the Coeur d'Alene River and Blackwell Island and Cougar Bay near the Spokane River outflow of Lake Coeur d'Alene were the areas of greatest concern for waterfowl exposure to lead contaminated sediment.

L’influenza aviaire hautement pathogène ou peste aviaire et le risque pour l’Homme

Since 1997, high-pathogenicity avian influenza (HPAI) virus infection in poultry "avian plague" has emerged as a potential threat to human health, with some fatal cases of bird-to-human transmission. These sporadic infections are caused by H7N7 and H5N1 viruses in Europe and Asia, respectively. The persistence of H5N1 viruses in poultry in several Asian countries, and their appearance in Europe, has raised concerns that the virus might mutate or recombine to create a human pandemic influenza A virus. Wild waterfowl are the natural reservoir of all influenza A viruses, and rarely develop the disease. Since 2002, some H5N1 HPAI viruses have become lethal for waterfowl, cats and humans, indicating an expanding host range. Transmission of H5N1 HPAI viruses from domestic poultry back to resistant domestic and wild ducks and to terrestrial birds (sparrows, pigeons, falcons, etc.) has increased the risk of geographic spread in Asia. These viruses spread through fecal contamination of the environment (particularly groundwater). Low-pathogenicity avian influenza (LPAI) viruses cause localized respiratory and gastrointestinal tract infection and, unlike HPAI viruses, are not detected in blood, muscle or eggs. Detection of HPAI viruses in meat, blood and internal organs of chickens and ducks raises public health concerns and underlines the need to thoroughly cook poultry and eggs consumed in Asia. The last case of HPA1 virus infection in France was notified in 1955.

Avian chromosomes can be examined by injection of erythrocyte nuclei into mouse oocytes.

Avian chromosomes can be examined by injection of erythrocyte nuclei into mouse oocytes.

Concentrations of cadmium, mercury and selenium in blood, liver and kidney of common eider ducks from the Canadian arctic.

We determined concentrations of selected trace elements in livers, kidneys and blood samples from common eiders (Somateria mollissima borealis) from the eastern Canadian arctic during 1997 and 1998. Concentrations of total mercury and organic mercury were generally low in the livers of these birds (less than 6 and 4 microg g(-1) dry wt, respectively). Selenium ranged between 11-47 microg g(-1) in livers. Renal cadmium concentrations were among the highest ever published for this species (range: 47-281 microg g(-1)). The regressions of log-transformed concentrations of these trace elements in blood samples on those in liver or kidney were significant (all P-values < 0.05) and positive. However, except for organic mercury (R2 = 0.83), the co-efficients of determination were low to moderate (range of R2: 0.26-0.52), suggesting poor to moderate predictive capability. Furthermore, the relationships between total mercury in blood and liver changed between 1997 and 1998, suggesting that it would not be possible to predict consistently, concentrations of mercury in blood from those in liver based on samples taken in one year. Blood samples can be used to determine concentrations of these trace elements in common eiders (and probably other sea duck species as well). The use of blood samples is especially warranted when it is undesirable to kill the animal such as when working with rare or endangered sea duck species or when the objective is to relate trace element exposure to annual survival rates. However, the predictive equations developed here should not be used to predict expected concentrations in one type of tissue from those in the other.

Clinical and experimental study on treatment of chronic hepatitis B with Yanggan Aoping Mixture

Objective: To assess the efficacy of Yanggan Aoping Mixture ( Open image in new window , YGAPM) in treating hepatitis B.Methods: Patients suffered from chronic hepatitis B were treated with YGAPM. Observe their short- and long-term efficacy and the change of serum hepatitis B virus marker. In experiment, the effects of YGAPM in treating rat’s liver injury as well as HBV-infected tree shrew and duck HBV-infected ducks were observed.Results: In 79 cases of chronic persistent hepatitis, the markedly effective rate was 60.76%, and further raised to 70.00% in follow-up study in 40 cases. In 73 cases of chronic active hepatitis, the markedly effective rate was 60.27%, and further raised to 62.50% in 32 follow-up cases. In the treatment group, 85 of the 119 cases (71.43%) with HBeAg-positive were converted to negative. Whereas in the control group, only 40 of 89 HBeAg-positive cases (44. 94%) were converted to negative,P < 0. 01. Results of experimental study showed that negative conversion rate of tree shrew infected with HBV marker was raised, while the duck HBV DNA in infected duck blood was inhibited. Those compared with the control group separately, the difference was markedly significant.Conclusion: YGAPM is an effective drug in treating chronic hepatitis B, and it could effectively convert the marker to negative.

Antigen-specific blastogenesis assays for duck hepatitis B virus using duck peripheral blood and splenic mononuclear cells

An antigen-specific lymphoblastogenesis assay for duck hepatitis B surface antigen (DHBsAg) and duck hepatitis B core antigen (DHBcAg) was developed using mononuclear cells from the periphral blood (PBMC) or spleens (SMC) of immune ducks. Optimal culture conditions for the assay were determined by testing a number of variables, including antigen concentration, cell numbers/well, and the day of harvest. The specificity of the assay was assessed. The assay used 10% pooled duck serum supplement, and 8 × 10 5 cells/well for PBMC or 5 × 10 5 cells/well for SMC. The optimum antigen concentration ranged from 0.01 to 0.1 μg/ml for both DHBsAg and DHBcAg. Maximum antigen-specific blastogenesis occurred between 4 to 7 days after establishment of the culture. The use of PHA (10 μg/ml) mitogenesis could predict the optimal cell numbers/well for antigen-specific blastogenesis. The assay demonstrated specific responses by immune ducks compared with those of unexposed ducklings and adult ducks (for DHBsAg P < 0.001; DHBcAg P < 0.05). For immune ducks, PBMC from all 8 ducks responded to DHBsAg, however, cells from only 4 of 7 immune ducks responded to DHBcAg. Splenic mononuclear cells from all immune ducks responded to either DHBsAg or DHBcAg or both antigens.

Identification of duck T lymphocytes using an anti-human T cell (CD3) antiserum

Duck lymphocytes have not been classified into cells resembling B or T cells of mammals. Reagents used in the past to identify lymphocyte populations in other species have not been useful for this purpose and antibodies raised to duck immunoglobulin bind in high proportions to blood and organ lymphocytes of ducks as well as to their red blood cells. Here we report that a polyclonal rabbit antiserum reacting to the CD3 marker on human T cells has been used to identify duck T lymphocytes. These antibodies react with the intracytoplasmic portion of the human CD3 epsilon chain (amino acids 156–168), an epitope highly conserved between mammals. Immunohistochemical staining with this antiserum of sections of duck lymphoid organs and FACScan analysis of duck lymphoid cell suspensions identified a population of duck lymphocytes with a staining pattern similar to that seen for mammalian T cells. This anti-human CD3 immunoprecipitated a 23 kDa protein from a duck lymphoblast lysate: a size similar to the human CD3 epsilon chain. This is the first direct identification of duck T lymphocytes.

Pharmacokinetics of Atrial Natriuretic Peptide in Pekin Ducks

To quantify the pharmacokinetics of atrial natriuretic peptide (ANP) in the blood of Pekin ducks, synthetic avian ANP was intravenously infused at various rates and the associated plasma concentrations of immunoreactive ANP (irANP) were measured by radioimmunoassay. At rates of 10, 25, 50, 100, and 200 ng/kg/min, steady-state arterial plasma levels, achieved within 10 min, showed a linear dose-plasma level-response relationship which indicated a mean plasma clearance rate of 174.4 ± 5.4 ml/kg/min. After stopping the 200 ng/kg/min infusion of ANP, the decay curve of plasma irANP was consistent with first-order kinetics, with the peptide having an elimination half-life time of 1.2 min. It is concluded that ANP is rapidly removed from the circulation of Pekin ducks.

Accumulation and effects of lead and cadmium on wood ducks near a mining and smelting complex in Idaho

: A study of wood ducks (Aix sponsa) was conducted along the Coeur d'Alene River system in northern Idaho in 1986 and 1987. Most of this area has been subjected to severe contamination from lead and other metals from mining and smelting since the 1880s. In 1986, a preliminary study of wood duck nesting was conducted in the contaminated area; incubating hens captured in nest boxes were bled and weighed. Blood samples were used to determine lead and cadmium concentrations and physiological characteristics. In 1987, an intensive study of wood ducks involved trapping and monitoring nest boxes in the contaminated area. Blood and tissue samples were also taken from wood ducks from a reference area without known contamination from metals. Lead levels in blood and tissues of most wood ducks from the contaminated area frequently exceeded those considered hazardous to birds; maximum levels (wet weight) of lead were 8 μg g(-1) in blood and 14 μg g(-1) in liver. Changes in physiological characteristics constituted the only evidence of potentially adverse effects from lead. In the contaminated area, nesting success (55% unadjusted, 35% Mayfield estimate) was less than in other areas where predation was low and nest boxes were used; but lead concentrations and physiological characteristics of blood were similar in successful and unsuccessful hens.Values of ALAD, hemoglobin, and body mass were negatively correlated with blood concentrations of lead, whereas protoporphyrin was positively correlated with lead levels in the blood. Some of the protoporphyrin values (1,091 μg dl(-1) in a male and 756 μg dl(-1) in a female) equalled those associated with lead toxicosis in experimental birds. ALAD activity was low in most birds from the contaminated area; values of 0 were obtained from 11 birds. Lead levels in blood, ALAD, protoporphyrin, and hemoglobin were significantly different between birds from the contaminated and reference areas. Concentrations of lead in ingesta of wood ducks ranged from 0.9 to 610 μg g(-1) in the contaminated area and 0.2 to 0.6 μg g(-1) in the reference area. Levels of cadmium in kidneys of wood ducks ranged from 1μg g(-1) to 20 μg g(-1) in the contaminated area and from only to 0.1 μg g(-1) to 1 μg g(-1) in the reference area. Cadmium concentrations were less than known effect levels.

Duck lymphocytes. VI. Requirement for phagocytic and adherent cells in lymphocyte transformation

Preparations of duck ( Anas platyrhynchos) spleen and blood lymphocytes depleted of cells capable of phagocytosing carbonyl iron gave lower transformation responses to the mitogens phytohaemagglutinin (PHA), concanavalin A (Con A), Bandeiraea simplicifolia seed lectin (BSS), wheat germ agglutinin (WGA), lentil lectin (LL) and phorbol ester (PMA) than intact cell preparations. When cell populations were fractionated on the basis of their adherence to plastic, it was found that the adherent cells were responsive to PHA, Con A, BSS, WGA and PMA, while the non-adherent cells responded to LL. These observations confirm the expected requirement for phagocytic accessory cells in the induction of in vitro mitogen-driven duck lymphocyte responses. The responses of plastic-adherent populations of cells to most mitogens are believed to reflect the generally close physical relationship between the adherent accessory cells and the lymphocytes, although it remains possible that duck monocytes respond to some of the mitogens employed. The data also suggest that LL stimulates a population of cells different to those responding to other mitogens.

Duck lymphocytes—V. Transformation responses to phorbol ester and calcium ionophore

1. Lymphocytes purified from duck blood and spleen were cultured in the presence of phorbol 12-myristate 13-acetate (PMA) and the calcium ionophore A23187. Stimulation was assessed by the incorporation of [ 3H]thymidine after 3 days' culture. 1. 2. PMA stimulated over a wide range of concentrations, with maximum stimulation at final concentrations of 5 × 10 −7−5 × 10 −8 M/litre. A23187 was effective in the range 5 × 10 −6−5 × 10 −7 M/litre and also, in some experiments using spleen lymphocytes, at 5 × 10 −11−5 × 10 −12 M litre . 2. 3. Synergism was observed between PMA and A23187, the pattern depending on the concentrations of these reagents employed. Synergism was also observed between PMA and suboptimum concentrations of phytohaemagglutinin (PHA), wheat germ agglutinin (WGA), pokeweed mitogen (PWM) and Bandeiraea simplicifolia seed extract (BSS), but not with concanavalin A (Con A), lentil lectin (LL) or Helix pomatia lectin (HP). Similarly, synergism occurred between A23187 and WGA or PWM, but not with PHA, BSS, Con A, LL or HP. 3. 4. Mitomycin C and cycloheximide inhibited the response of duck lymphocytes to PMA, A23187 and lectins. Cyclosporin A inhibited responses to lectins but not to PMA or A23187. Neither hydrocortisone nor indomethacin inhibited responses to lectins, PMA or A23187. 4. 5. These results indicate that activation of duck lymphocytes occurs by virtue of similar intracellular messenger pathways to those operating in mammalian lymphocytes.

Duck lymphocytes. IV. Collective effects of mitogens

Duck ( Anas platyrhynchos) blood lymphocytes were cultured in the presence of phytohaemagglutinin (PHA), concanavalin A (Con A), pokeweed mitogen (PWM), lentil lectin (LL), Roman snail lectin (HP), wheat germ agglutinin (WGA), Bandeiraea simplicifolia seed lectin (BSS), peanut agglutinin (PNA), horseshoe crab lectin (HSC) and bacterial lipopolysaccharide (LPS). Mitogens were used individually, in pairs, and in multiple combinations. Some pairs resulted in synergism; transformation, assessed by uptake of [ 3H]thymidine, was much greater than a direct addition of the effects of the two mitogens used separately. Best results were obtained when PHA or LL were paired with a second mitogen. In general, combinations of lectins at slightly suboptimal concentrations gave highest transformation, and all strongly synergistic combinations elicited a similar pattern of dose response through different concentrations of PHA. If a third mitogen was included, some combinations gave some further synergism, in other combinations the synergism of two mitogens was reduced by including a third, and if a pair of mitogens did not demonstrate synergism then none was generated when a third mitogen was included. Inclusion of more mitogens to successfully synergistic trios reduced transformation. The system could provide a useful model for in vitro enhancement of responses among lymphocytes from a species with a weak immune system.

Interaction of atrial natriuretic factor and osmoregulatory hormones in the Pekin duck

This study examined the influence of plasma atrial natriuretic factor (ANF) on the osmoregulatory hormones arginine vasotocin (AVT), angiotensin II (AII), aldosterone, and corticosterone in the blood of conscious Pekin ducks. Synthetic chicken ANF was iv infused at a nonhypotensive, natriuretic, and diuretic dose of 100 ng · kg −1 · min −1 in normally hydrated ducks and birds in which the circulating levels of AVT, AII, aldosterone, and corticosterone were elevated by 24-hr dehydration. In normally hydrated animals the effect of ANF was limited to a reduction ( P < 0.05) in the basal concentration of aldosterone; in dehydrated birds both AII and aldosterone levels were reduced ( P < 0.05). ANF infusion was consistently without effect on plasma AVT or corticosterone concentrations. The iv infusions of AII with or without simultaneous infusion of ANF showed that ANF inhibited ( P < 0.05) the aldosterone response to AII. Autoradiographic and membrane binding techniques indicated that there were both AII and ANF receptors in the subcapsular zone of the duck adrenal gland and that ANF had no affinity for the AII binding sites. The results demonstrate that ANF is capable of modulating the duck angiotensin-aldosterone system and suggest a role for this peptide in avian salt and fluid homeostasis.

Duck lymphocytes—III. Transformation responses to some common mitogens

The lymphocyte transformation (LT) test was performed using duck blood lymphocytes stimulated with phytohaemagglutinin (PHA), concanavalin A (Con A), lentil lectin (LC), Roman snail lectin (HP), peanut agglutinin (PNA), Bandeiraea simplicifolia seed lectin (BSS), wheat germ agglutinin (WGA), horseshoe crab lectin (HSC), pokeweed mitogen (PWM) and E. coli lipopolysaccharide (LPS). Cells were cultured in microtitre trays, at 41.6°C, 8 × 10 5 cells in 200 μl medium (=4 × 10 6 cells/ ml) supplemented with 10% pooled duck serum. Mitogens were added at final concentrations of 0.1–100 μg/ml and triplicate cultures at each concentration were harvested daily for scintillation counting 6 hr after addition of 1 μCi [ 3H]thymidine. Three patterns of response were observed. The responses to Con A, LC, HP and HSC were greatest at high mitogen concentrations (40–100 μg/ml) throughout the 7 days of culture. With PHA, PNA, WGA and LPS maximum stimulation was obtained at 3–5 days, at which time the cells were responding to lower concentrations of mitogen than were required at other times during the experiment. The response to BSS and PWM showed increasing sensitivity to lower concentrations of mitogen during the first 3 days of culture and then stimulated most strongly at 2–10 μg/ml in cultures harvested after 4–7 days. Cells from two ducks were cultured for 3 and 5 days with selected concentrations of these mitogens; the results confirmed the variation in response to different mitogens. It is possible that these patterns of response are the outcome of stimulating different populations of duck lymphocytes.

Duck lymphocytes II. culture conditions for optimum transformation response to phytohaemagglutinin

The lymphocyte transformation (LT) test was performed with duck blood lymphocytes in 96-well microtitre trays against nine concentrations (0.1–100 μg/ml) of phytohaemagglutinin (PHA). It was found that incubation at 41.6°C (duck body temperature) gave better results than incubation at 37°C, and that a 6 h pulse with [3H]thymidine gave better results than an 18 h pulse. Cell concentration was very critical: successful duck LT required rather high concentrations of cells (∼ 4×106/ml, equivalent to ∼ 8 × 105/culture) while lower and higher concentrations gave inferior results. Duck serum supported LT optimally when used at a concentration of 10–15%, but a serum pool from adult (∼ 6-month-old) ducks gave superior results to sera from younger birds. Foetal calf serum supported duck LT strongly when used at 20%, but only poorly at 10%, while chicken serum supported duck LT when used at 5–20%. Ultroser G was an ineffective supplement, and the addition of 5% tryptose phosphate broth to other supplements had variable effects. Using optimum culture conditions, maximum LT responses were obtained after 2–3 days' culture, when it was possible to obtain stimulation indices of 500–5000. The addition of PHA to cultures could be delayed for up to 18 h without affecting LT, but thereafter the cells rapidly lost responsiveness.