Antibody response to sheep red blood cells in platypus and echidna

There is limited information regarding the kinetics of antibody responses exhibited by the platypus and the echidna in response to a T cell dependent antigen. In this preliminary study a platypus, an echidna and a rabbit were inoculated with sheep red blood cells to compare their antibody responses and kinetics. The antibody titres, produced by the platypus and echidna, were less than those elicited in the rabbit. Furthermore, the echidna and platypus exhibited a weak secondary response. This was most likely due to a failure of the platypus and echidna to undergo the characteristic IgM to IgG isotype switch following second antigen exposure. The conformational structure of these antibodies may differ from eutherian antibodies. This was further supported by a heat sensitivity experiment that indicated that these antibodies are more labile than rabbit immunoglobulins and therefore structurally less stable.     

Altered humoral immune response to sheep red blood cells by sheep erythrocyte-soluble hemolysate.

Adult C3H/He mice were rendered unresponsive to a primary injection of sheep red blood cells (SRBC) by pretreatment with sheep hemolysate supernatant (SHS) or subfractions of SHS isolated by column chromatography. The following effects of SHS on the immune response were observed: SHS did not kill antigen-reactive cells, it did not prevent the release of antibody by cells actively synthesizing and secreting antibody, and SHS-induced tolerance was not inhibited or abrogated by methods which terminate or abolish tolerance. In addition, cell-mediated responses were not affected in animals whose humoral responses were suppressed; however, the secondary plaque-forming cell (PFC) response was enhanced by SHS treatment. SDS gel electrophoresis revealed SHS to contain several proteins ranging from 12,000 to approximately 500,000 daltons.     

In vitro response of chicken spleen cells to sheep red blood cells

A modification of the Marbrook system for obtaining both primary and anamnestic responses from chicken spleen cells in vitro is described. The patterns of responsiveness of chicken spleen cell cultures resembled those previously described for the mouse. However, the requirement for normal chicken serum (NCS) to support the response could not be replaced by foetal calf serum (FCS). Cell survival, response kinetics, antigen dose requirements, antibody class, and temporal development of memory are described. The requirement for cooperation of B and T cells in the SRBC response was demonstrated by the use of specific anti-T and anti-B sera.     

Lower haematocrit,haemoglobin and red blood cell number in zebra finches acclimated to cold compared to thermoneutral temperature

Thermoregulation constitutes an important share of the energy budget of endotherms. Elevated thermoregulatory requirements must be met by oxygen supply through the blood, as heat is produced mainly via aerobic processes. In contrast to mammal studies, it remains unclear whether elevated thermoregulatory needs are followed by changes in haematological variables in birds. We investigated haematocrit (HCT), haemoglobin content per volume of blood (HGB), number of red blood cells (RBC_count), and size of the erythrocytes (RBC_area) in zebra finches Taeniopygia guttata acclimated to either cold or thermoneutral ambient temperatures under laboratory conditions. Seventy‐nine females were maintained for six weeks either in cold (T = +12°C) or thermoneutral (T = +32°C) ambient temperature prior to blood collection. On average, HGB, HCT and RBC_count were significantly lower by about 10% in cold acclimated compared to thermoneutral acclimated birds. Only RBC_area was not different between the two acclimation temperatures. Mean HCT, one of the most commonly measured haematological variable for example was 53 ± 0.9% (LSM ± SEM) in thermoneutral and 49 ± 0.8 % (LSM ± SEM) in cold acclimated zebra finches. On first sight, the observed lower values for three out of the four determined haematological variables in response to acclimation to cold question oxygen supply to be indeed a limiting factor for heat production. However, higher demands of oxygen supply due to increased thermoregulation in birds may instead require specific optimisation of blood viscosity and modulation by other cardiovascular properties. Nucleated red blood cells in birds may pose different strain on blood viscosity compared to non‐nucleated mammalian erythrocytes and explain the contrasting response in haematological variables to temperature acclimation between birds and mammals.     

Genomic regions associated with antibody response to sheep red blood cells in the chicken

F(1) and F(2) populations were generated by crossing two lines of chickens divergently selected from a common founder population for 32 generations for either high or low antibody response 5 days post-injection of a non-pathogenic antigen, sheep red blood cells (SRBCs). The number of loci with major effects on day 5 SRBC titers was estimated to be more than 7 in this population. There was a significant association between MHC haplotype and day 5 antibody titers as well as body weight at sexual maturity. A significant difference between reciprocal F(2) crosses for both 5- and 12-day antibody titers suggests that sex chromosome and/or parent of origin effects on autosomal loci have an important role in immune response. A single marker-trait association analysis on 1024 genetic markers and 128 F(2) individuals detected 11 genomic regions associated with antibody response traits and 17 regions associated with body weight gain. Several of the genomic regions identified as being associated with antibody response have been described previously, while novel regions associated with antibody response were identified on chromosomes 11 and 24. Based on the lack of overlap of the regions associated with body weight and antibody response, we conclude that while these phenotypes are inversely correlated in the selected lines, they are controlled by distinct genetic loci and may be reflective of intense selection pressure on loci affecting the partitioning of nutrients between the immune system and growth pathways.     

Detection of QTL for immune response to sheep red blood cells in laying hens

The aim of this study is to detect quantitative trait loci (QTL) involved in the regulation of the primary and the secondary immune response to sheep red blood cells (SRBC) in a resource population using microsatellite DNA markers. The F2 resource population originates from a cross of two divergently selected lines for either high (H line) or low (L line) primary antibody response to SRBC. The F2 population consisted of six half-sib families, three families per each of reciprocal crosses. Total antibody titres to SRBC were determined by agglutination in serum from all birds. F2, F1 and F0 generations were genotyped for 170 microsatellite markers, using a whole-genome scan approach. The half-sib and the line-cross analyses were performed to determine QTL regions associated with regulation of the immune response. In the half-sib analysis, four QTL for SRBC primary response have been identified: on GGA3, GGA5, GGA16 and GGA23. No QTL was identified for SRBC secondary response under the half-sib model. In the line-cross analysis, three QTL were identified on GGA10, GGA16 and GGA27 for SRBC primary response and five QTL were identified on GGA6, GGA9, GGA15, GGA16 and GGA27 for SRBC secondary response. Subsequently, the family contribution of individual families to the QTL was analysed. The family with the largest contribution was genotyped with additional microsatellite markers in the QTL region on GGA5. The extended half-sib analysis with additional genotype information results in narrowing down the QTL region on GGA5.     

Bill redness is positively associated with reproduction and survival in male and female zebra finches

Sexual traits can serve as honest indicators of phenotypic quality when they are costly. Brightly coloured yellow to red traits, which are pigmented by carotenoids, are relatively common in birds, and feature in sexual selection. Carotenoids have been linked to immune and antioxidant function, and the trade-off between ornamentation and these physiological functions provides a potential mechanism rendering carotenoid based signals costly. Mutual ornamentation is also common in birds and can be maintained by mutual mate choice for this ornament or by a correlated response in one sex to selection on the other sex. When selection pressures differ between the sexes this can cause intralocus sexual conflict. Sexually antagonistic selection pressures have been demonstrated for few sexual traits, and for carotenoid-dependent traits there is a single example: bill redness was found to be positively associated with survival and reproductive output in male zebra finches, but negatively so in females. We retested these associations in our captive zebra finch population without two possible limitations of this earlier study. Contrary to the earlier findings, we found no evidence for sexually antagonistic selection. In both sexes, individuals with redder bills showed higher survival. This association disappeared among the females with the reddest bills. Furthermore, females with redder bills achieved higher reproductive output. We conclude that bill redness of male and female zebra finches honestly signals phenotypic quality, and discuss the possible causes of the differences between our results and earlier findings.     

The optokinetic response in wild type and white zebra finches

Optic flow is a main source of information about self movement and the three-dimensional composition of the environment during locomotion. It is processed by the accessory optic system in all vertebrates. The optokinetic response is elicited by rotational optic flow, e.g. in a rotating drum lined with vertical stripes. We investigated here the effect of rotational optic flow on the optokinetic response in wild type and white zebra finches. The highest stimulus velocity eliciting an optokinetic response (upper velocity threshold) was dependent on stimulus direction and illumination level, but was not different between the colour morphs. The upper velocity threshold was higher with temporal to nasal movements in monocularly exposed birds and symmetrical with binocular exposure. Its increase with illumination level followed Fechner's law and reached a plateau at about 560 Lux. In bright daylight, white birds did not show optokinetic responses. We conclude that the altered wiring of the visual system of white birds has no influence on accessory optic system function. The unwillingness of white birds to respond with optokinetic response in bright daylight may be due to a substantial lack of inhibition within the visual system as demonstrated earlier, which may enhance the sensibility to glare.     

Altered auditory BOLD response to conspecific birdsong in zebra finches with stuttered syllables

How well a songbird learns a song appears to depend on the formation of a robust auditory template of its tutor's song. Using functional magnetic resonance neuroimaging we examine auditory responses in two groups of zebra finches that differ in the type of song they sing after being tutored by birds producing stuttering-like syllable repetitions in their songs. We find that birds that learn to produce the stuttered syntax show attenuated blood oxygenation level-dependent (BOLD) responses to tutor's song, and more pronounced responses to conspecific song primarily in the auditory area field L of the avian forebrain, when compared to birds that produce normal song. These findings are consistent with the presence of a sensory song template critical for song learning in auditory areas of the zebra finch forebrain. In addition, they suggest a relationship between an altered response related to familiarity and/or saliency of song stimuli and the production of variant songs with stuttered syllables.     

Triiodothyronine improves the primary antibody response to sheep red blood cells in severely undernourished weanling mice

Three experiments were conducted in which weanling mice were fed a nutritionally complete diet either ad libitum or in restricted quantities such that they lost about 30% of their initial weight over a 14-day period. In Experiments 1 and 2, half the animals from each group received dietary triiodothyronine (T3) supplements. In Experiment 3, food-intake-restricted mice were fed graded levels of potassium iodide. Malnutrition reduced the number of nucleated cells per spleen, the number of splenic IgG plaque-forming cells (PFC) per 10(6) cells, and the serum antibody titers against sheep red blood cells. T3 supplements increased antibody titers, the number of nucleated cells per spleen, and both IgM and IgG PFC per 10(6) spleen cells in malnourished mice, but had no effect on well-nourished mice. The beneficial effect of T3 was not a result of improved protein, energy, or iodine status in the malnourished mice.     

IgM and IgG response to sheep red blood cells in mouse hepatitis virus-infected nude mice.

In nude mice which originally had no ability to respond to sheep red blood cells, an enhanced response to the same antigen with IgM-IgG switching was demonstrated during subacute infection with mouse hepatitis virus. IgM antibody-producing cells in the spleen were detected at days 2 to 6 after the antigen injection and IgG antibody-producing cells appeared at day 6 or later. The secondary IgG response, though not remarkable, was recognized after reinjection of the antigen 10 days after the first injection.     

H-2-linked genetic control of the plaque-forming cell response to sheep red blood cells

The role of genes linked to the H-2 locus in effecting an immune response to SRBC was examined using strains of mice which differ in the classes of antibodies produced following multiple injections with SRBC. While H-2-linked gene action appeared to be at the level of regulating the number of plaque-forming cells (PFC) present in the spleens of different strains following two injections with SRBC, non-H-2-linked immune response genes seemed to determine whether an IgM-IgG switch occurred as well as how much of each antibody class was produced by the number of PFC available as a result of H-2-linked gene intervention. Mapping studies showed that the H-2-linked genetic effects were due to either the requirement for two genes or the presence of genes located between I-B and H-2D.     

Targeting of monoclonal antibody-coated liposomes to sheep red blood cells

A monoclonal mouse anti-sheep red blood cell specific antibody IgG_2b was esterified with palmitic acid which served as a hydrophobic anchor for successfull incorporation into the liposomal membrane. The formation of coated liposomes by dialyzing the mixed antibody/lipid/detergent micelles against phosphate buffer was simplified b by using the same detergent as for the antibody derivatization. No purification step of any intermediate product was necessary. Targeting of the resulting vesicles to sheep red blood cells occured with high efficiency compared with control liposomes. The uptake was fast and specific as demonstrated with sheep and horse red blood cells by the use of radioactively labelled liposomes and by scanning electron microscopy.