Marek's disease and major histocompatibility complex haplotypes in chickens selected for high or low antibody response

Sublines of chickens differing in genotypes at the major histocompatibility complex (MHC) were developed from lines selected for high (HA) and low (LA) antibody response to sheep erythrocytes. To evaluate the influence of MHC genotypes in diverse background genomes on resistance to Marek's disease, chicks with MHC genotypes B13B13, B13B21 and B21B21 from both background genomes were exposed naturally commencing at 1 day of age. Individuals which died up to 120 days of age were autopsied to determine cause of death. Mortality due to Marek's disease was greater for HA than LA chickens and greater for males than females. Interactions of MHC genotypes with background genome and with sex suggest a complex picture of the influence of MHC genotypes. A heterozygous advantage for resistance to Marek's disease was noted, as would be predicted by genetic theory concerning maintenance of polymorphism at the MHC.     

Antibody responses to sheep erythrocytes for White Leghorn chickens differing in haplotypes of the major histocompatibility complex (B)

Lines of White Leghorn chickens were developed by selection for high (HA) or low (LA) antibody response to sheep red blood cells (SRBC) and then backcrossed to provide individuals segregating for haplotypes B13 and B21 of the major histocompatibility complex (MHC) within each selected line. Although antibody response to SRBC was consistently higher in background genome HA than LA, there was a significant interaction between background genome and MHC haplotypes. The interaction resulted from higher antibody response in B13/B21 individuals of line HA and in B21/B21 individuals of line LA. Thus, response to SRBC was dependent on particular haplotype combinations present at the MHC as well as the background genome in which they were expressed.     

Antibody responses to sheep erythrocytes for White Leghorn chickens differing in haplotypes of the major histocompatibility complex (B)

Summary. Lines of White Leghorn chickens were developed by selection for high (HA) or low (LA) antibody response to sheep red blood cells (SRBC) and then backcrossed to provide individuals segregating for haplotypes B ¹³ and B ²¹ of the major histocompatibility complex (MHC) within each selected line. Although antibody response to SRBC was consistently higher in background genome HA than LA, there was a significant interaction between background genome and MHC haplotypes. The interaction resulted from higher antibody response in B¹³/B²¹ individuals of line HA and in B²¹/ B ²¹ individuals of line LA. Thus, response to SRBC was dependent on particular haplotype combinations present at the MHC as well as the background genome in which they were expressed.     

Frequency of headshaking in White Leghorn chickens in response to hormonal and environmental changes

Frequency of headshaking in chickens from two selected lines (HA and LA) known to differ in this trait was observed at various ages, during hormonal fluctuations and in different environmental surroundings. Neither hormonal changes concomitant with the initial onset of lay nor ingestion of corticosterone (which stopped egg production in 240-day-old pullets) altered headshaking frequency. When pullets reared in flocks on litter were moved at 77 days of age to individual battery cages, headshaking frequency was dramatically increased in one flock but did not change in another flock. Moving 252-day-old birds from individual cages to floor pens decreased headshaking frequency in males but not in females; returning the birds to cages did not significantly alter levels of headshaking. In older birds (252 days of age), headshaking frequency in all birds in line HA and in males of line LA were considerably greater than in LA females.     

Ovine placenta at high altitudes: comparison of animals with different times of adaptation to hypoxic environment

Fetal growth and newborn weight from ovine gestations at high altitudes (HA) are greater in ewes that live at HA for several generations than in those native to low altitudes (LA) exposed to HA only during pregnancy. Because the placenta is a key regulator of fetal growth, the present study compared placental characteristics in term pregnancies among ewes native to HA and LA. Conception occurred at HA and ewes continued to reside at HA throughout pregnancy or conception occurred at LA and ewes were transported to HA or remained at LA (controls). Ewes native to LA were moved to HA shortly after mating (group LH) and joined with pregnant ewes native to HA (group HH). After parturition, placental cotyledons were counted and measured for total area and histological estimation of surface occupied by vasculature. The total surface of the cotyledons and surface occupied by vasculature were greater at HA, whereas the number of cotyledons was smaller at HA. These changes were more pronounced in ewes of the HH compared with the LH group. The present study showed that exposure to HA induces, in pregnant ewes, placental morphological changes that may improve maternal-fetal exchange. Moreover, because of accentuation of placental changes in ewes with long-term residence at HA, this appears to be an efficient mechanism of adaptation to hypobaric hypoxia.     

表达H5亚型禽流感病毒HA基因和鸡IL-18基因重组禽痘病毒的构建

[目的]获得共表达H5亚型AIV HA基因和鸡IL-18基因的重组禽痘病毒.[方法]将含痘病毒启动子LP2EP2的HA基因和鸡IL-18基因插入到禽痘病毒转移载体pSY681中,获得重组转移载体pSYHA/IL-18.用脂质体将其转染已感染亲本禽痘病毒S-FPV-017株的鸡胚成纤维细胞,使其在鸡胚成纤维细胞内与禽痘病毒基因组发生同源重组,产生表达HA和IL-18的重组禽痘病毒(rFPV-HA-IL-18).在含有X-gal的营养琼脂培养基上进行蓝斑筛选后,对重组禽痘病毒又进行了多次蚀斑克隆.[结果]以重组禽痘病毒DNA为模板,利用HA基因和鸡IL-18基因引物进行PCR,分别扩增出1条约1.7 kb带和1条0.6 kb左右的带.以间接免疫荧光试验、T细胞转化试验和SPF雏鸡免疫接种证实重组禽痘病毒能表达HA和鸡IL-18,并初步证明鸡IL-18增强HA免疫作用.[结论]重组禽痘病毒能表达具有生物学活性的HA和鸡IL-18.     

Gas exchange, heat production and oxidation of fat in chicken embryos from a fast or slow growing line

The experiment comprised 48 chicken (Gallus gallus) embryos from a modern, fast growing line, Ross 308 (RO) and 48 from a slow growing line, Labresse (LA). The O(2) consumption and CO(2) production were measured in an open-air-circuit respiration unit, and heat production (HE) from embryos was calculated at an age of 10, 13, 16 and 19 days. Gas exchange was below 10 ml/h for RO and LA by an age of 10-13 days, increasing steeply to a "peak" on day 16 and then slowing down between 16 and 19 days. The pattern of curves for gas exchange was identical for RO and LA, but on a lower level for LA. HE followed the pattern of gas exchange, with a mean around 50 J/h on day 10, increasing to 528 (RO) and 402 (LA) J/h on day 19. The main source of HE was oxidized fat. In addition to respiration experiments chemical analyses were carried out on 60 eggs from RO and 60 from LA. Prior to chemical analyses the eggs were incubated for 7, 13 and 19 days. Since fat oxidation was the main energy fuel the content of fat in the eggs decreased by 2.0 (RO) and 1.6 g (LA), while protein content was fairly constant in each line. It is remarkable that the differences in heat production between chickens from fast and slow growing lines were already manifested during their embryonic development.     

Differential metabolic capacity of mice selected for magnitude of swim stress-induced analgesia.

Maximum oxygen consumption (Vo(2)) elicited by swimming in 20 degrees C water or by exposure to -2.5 degrees C in helium-oxygen (Helox) atmosphere is higher in mice selected for low (LA) than for high (HA) stress-induced analgesia (SIA) produced by swimming. However, this line difference is greater with respect to swim- than to cold-elicited Vo(2). To study the relationship between the analgesic and thermogenic mechanisms, we acclimated HA and LA mice to 5 degrees C or to daily swimming at 20 or 32 degrees C. Next, the acclimated mice were exposed to a Helox test at -2.5 degrees C and to a swim test at 20 degrees C to compare Vo(2) and hypothermia (DeltaT). Cold acclimation raised Vo(2) and decreased DeltaT. These effects were similar in both lines in the Helox test but were smaller in the HA than in the LA line in the swim test. HA and LA mice acclimated to 20 or 32 degrees C swims increased Vo(2) and decreased DeltaT elicited by swimming, but only HA mice acclimated to 20 degrees C swims increased Vo(2) and decreased DeltaT in the Helox test. We conclude that the between-line difference in swim Vo(2) results from a stronger modulation of thermogenic capacities of HA mice by a swim stress-related mechanism, resulting in SIA. We suggest that the predisposition to SIA observed in laboratory as well as wild animals may significantly affect both the results of laboratory measurements of Vo(2) and the interpretation of its intra- and interspecific variation.     

Increased hemoglobin O2 affinity does not improve O2 consumption in hypoxemia

We perfused an isolated rabbit hindlimb preparation with suspensions of human erythrocytes (RBC) having different O2 affinities. Our objective was to compare the effect of changes in P50, the PO2 at which hemoglobin is 50% saturated, on tissue O2 consumption during severe hypoxemia. A high-affinity (HA) group (n = 9) was perfused with RBC incubated in NaCNO (P50 = 21.4 +/- 1.9 Torr). This was compared with a low-affinity (LA) group (n = 9) perfused with rejuvenated RBC (P50 = 31.1 +/- 1.8 Torr). The arterial PO2 of the perfusate was decreased to approximately 24 Torr in both preparations. Perfusion flow and hemoglobin concentration were maintained constant. During hypoxemia arterial O2 saturation and total O2 transport (TO2) were greater in the HA than the LA group (P less than 0.05). O2 consumption and effluent venous PO2 decreased with hypoxemia in both groups to similar levels. Consequently, the LA group showed a greater O2 extraction ratio than the HA group (P less than 0.05). The ratio of phosphocreatine to inorganic phosphate, measured with 31P magnetic resonance spectroscopy, decreased at a comparable rate in both groups. As shown by a mathematical model of peripheral O2 transport, these experimental results can be explained on the basis of peripheral limitation to O2 diffusion. We conclude that increased hemoglobin affinity does not appreciably improve tissue oxygenation in hypoxemia, since the increase in TO2 is offset by diffusion limitation at the tissues.     

Effects of the methanol extract residue (MER) tubercle bacillus fraction on the production of antibodies in vitro. II. Effects on macrophage and lymphocyte populations

The effect of the methanol extract residue (MER) fraction of BCG tubercle bacilli on the generation of primary antibody responsiveness in vitro to sheep red blood cells (SRBC) was ascertained in cell reconstitution experiments, employing enriched populations of mouse macrophages and of T and B lymphocytes. In each of the antibody generation cultures one or another of the cell fractions had been exposed to MER, either by treatment of the donor animals or by preincubation with the agent for 48 hr in vitro. In some experiments, supernatants of MER-preincubated cells were employed in place of the cells. Macrophages and T cells that had been exposed to MER in vivo or in vitro and their supernatants demonstrated a markedly greater effect than nonexposed cells in the generation of direct specific plaque-forming cells (PFC) upon antigenic stimulation of the cultures with SRBC. In contrast, PFC production was not stimulated in B-lymphocyte populations that had been in contact with the agent.     

Hemagglutination activities of purified pertussis toxin and filamentous hemagglutinin against erythrocytes from various animals

The hemagglutinating (HA) activities of purified pertussis toxin (PT) and filamentous hemagglutinin (FHA) were evaluated against unfixed and glutaraldehyde-fixed erythrocytes from ox, goose, horse, monkey, sheep, chicken, and rabbit. Both PT and FHA showed HA activities against fixed and unfixed erythrocytes from all the animals studied. The HA titers of FHA were higher than those of PT. The HA activities of FHA and PT were not destroyed completely even after heating these preparations at 56 C for 30 min. A simple test for the assay of PT in culture supernatants of Bordetella pertussis on the basis of HA activity has been described.     

Effect of calcium concentration on textural properties of high and low acyl mixed gellan gels

Textural properties of 1% low and high acyl gellan gels and their mixtures were studied using compression tests and the microcentrifuge-microfiltration based water holding capacity (WHC) method. Low acyl (1% LA), high acyl (1% HA) gels and mixtures of 1% 25/75 LA/HA, 50/50 LA/HA, 75/25 LA/HA gels with calcium concentrations ranging from 2 to 80 mM were studied. HA or mixed gels with a lower LA/HA ratio had a greater WHC and failure strain than that of LA or mixed gels with a higher LA/HA ratio. Gellan gels with a higher LA/HA ratio had a larger initial Young's modulus. Our study also indicates that a higher LA/HA ratio does not necessarily result in a gel with a larger failure stress, although LA gels are generally firmer than HA gels. Gel strength and WHC of HA and LA/HA mixtures may reflect both stabilization and destabilization effects of glycerate groups positioned at one of the glucose residues in each repeating tetrasaccharide unit of HA gels.     

Influence of the genotype on the polytene chromosome puffing and bioelectrical properties of cellular nuclei of Drosophila melanogaster treated with ecdysone in vivo and in vitro experiments

Activity of polytene chromosome puffs at the 0-hour prepupae stage and bioelectric properties of cellular nuclei of salivary glands were investigated under the influence of the hormone 20-OH-ecdysone in vitro in highly inbred selected lines LA (low activity) and HA (high activity) and their F1 hybrids LA x HA and Ha x LA. The inadaptive line LA differs from the line HA by the smaller size of the puffs. The hybrids exceed the best parental line by the size of the majority of the investigated puffs. In the course of investigation of F1 hybrids Ha x LA chromosomes the phenomenon of heteropuffing has been revealed at the asinapsis sites. In vitro impact of ecdysone increases the electrokinetic potential of cellular nuclei; in hybrids this effect expressed more strongly than in parental lines. The data obtained indicate genetic differences in puffing activity in Drosophila polytene chromosomes as a result of inbreeding, destabilizing selection and heterosis effect, and they also confirm the correlation of bioelectric properties of the nuclear genome with regulation of genetic activity of a cellular nucleus.     

Amino acid transport and intracellular Na+ and K+ content of chicken erythrocytes genetically selected for high and low leucine transport activity

1. Amino acid transport and intracellular Na+ and K+ content have been studied in two lines of chickens, one high and the other low uptake, selected for their ability to transport leucine into erythrocytes. 2. Low line birds were less effective in absorbing glycine into erythrocytes than were high line birds, the difference in transport being due to a difference in maximal flux (Vmax), but not in apparent affinity for transport sites (Kt). 3. In contrast to glycine uptake, the greater ability of the high line to absorb lysine was found to be due to a difference in both Vmax and Kt. 4. High line erythrocytes were also observed to contain slightly more K+ (about 5%) and about 20% less Na+ than low line erythrocytes. 5. These results are discussed in terms of the ion dependency of amino acid transport.     

Mycoplasma pulmonis depresses humoral and cell-mediated responses in mice

Humoral and cell-mediated immune responses to sheep red blood cells (SRBC) were studied in mice infected experimentally with Mycoplasma pulmonis. The hemagglutinating (HA) antibody against SRBC was evaluated at 0, 3, 5, 7, 14, 21 and 28 days postinfection (PI). Antibody tiers during all days PI were depressed significantly (p less than 0.05) in infected mice as compared to noninfected controls. The HA antibody, which is of the IgM class, peaks at day 5 PI. There is no shift in the kinetics of the humoral response in M. pulmonis infected mice. Cellular immune responses were evaluated by a delayed-type hypersensitivity (DTH) reaction and the lymphocyte transformation technique. Mice were sensitized at 0,3,5,7,14, 21 and 28 days PI with SRBC and challenged by footpad injection of SRBC 7 days later. The DTH reaction measured at 24 hours after challenge was depressed significantly (p less than 0.05) in all infected animals. After a transient enhancement on day 3 PI, the DTH responses remained depressed through day 28 PI. The lymphocyte transformation test showed a significantly (p less than 0.05) depressed response except on days 5 and 7 PI. These results indicate that M. pulmonis infection in mice suppresses the humoral antibody and cell-mediated immune responses.     

Effects of the MER tubercle bacillus fraction on the production of antibodies in vitro: I. Effect on the primary response

The effect of the methanol extraction residue (MER) fraction of BCG tubercle bacilli on the primary antibody response in vitro to sheep red blood cells (SRBC), TNP conjugates, and the monovalent hapten DNP-glycine was studied. Addition of MER to whole splenocyte cultures simultaneously with antigen presentation potentiated the antibody response to SRBC and TNP-SRBC, and facilitated reactivity to DNP-glycine; there was no effect on the response to the T-independent entity TNP-LPS (lipopolysaccharide from E. coli 055-B5). Immunopotentiating activity of MER for SRBC and DNP-glycine was also evident in macrophage-depleted cultures. Peritoneal exudate cells (PEC) taken from MER-treated donors were more efficient than PEC from untreated donors in reconstituting antibody formation to SRBC by macrophage-depleted spleen cell populations. The results obtained indicate that activation of both macrophages and of certain lymphocyte population(s) by MER may play a role in the potentiation of antibody responsiveness in vitro by this agent.     

The ability of genetically lean or fat slow-growing chickens to synthesize and store lipids is not altered by the dietary energy source

The increasing use of unconventional feedstuffs in chicken’s diets results in the substitution of starch by lipids as the main dietary energy source. To evaluate the responses of genetically fat or lean chickens to these diets, males of two experimental lines divergently selected for abdominal fat content were fed isocaloric, isonitrogenous diets with either high lipid (80 g/kg), high fiber (64 g/kg) contents (HL), or low lipid (20 g/kg), low fiber (21 g/kg) contents (LL) from 22 to 63 days of age. The diet had no effect on growth performance and did not affect body composition evaluated at 63 days of age. Glycolytic and oxidative energy metabolisms in the liver and glycogen storage in liver and Sartorius muscle at 63 days of age were greater in chicken fed LL diet compared with chicken fed HL diet. In Pectoralis major (PM) muscle, energy metabolisms and glycogen content were not different between diets. There were no dietary-associated differences in lipid contents of the liver, muscles and abdominal fat. However, the percentages of saturated (SFA) and monounsaturated fatty acids (MUFA) in tissue lipids were generally higher, whereas percentages of polyunsaturated fatty acids (PUFA) were lower for diet LL than for diet HL. The fat line had a greater feed intake and average daily gain, but gain to feed ratio was lower in that line compared with the lean line. Fat chickens were heavier than lean chickens at 63 days of age. Their carcass fatness was higher and their muscle yield was lower than those of lean chickens. The oxidative enzyme activities in the liver were lower in the fat line than in the lean line, but line did not affect energy metabolism in muscles. The hepatic glycogen content was not different between lines, whereas glycogen content and glycolytic potential were higher in the PM muscle of fat chickens compared with lean chickens. Lipid contents in the liver, muscles and abdominal fat did not differ between lines, but fat chickens stored less MUFA and more PUFA in abdominal fat and muscles than lean chickens. Except for the fatty acid composition of liver and abdominal fat, no interaction between line and diet was observed. In conclusion, the amount of lipids stored in muscles and fatty tissues by lean or fat chickens did not depend on the dietary energy source.     

The titration of tetanus antitoxin I. Factors affecting the sensitivity of the indirect haemagglutination test

Various factors affecting the indirect HA test for the titration of tetanus antitoxin have been evaluated with a view to obtaining maximum sensitivity in tests using unfixed sheep erythrocytes and sheep erythrocytes fixed with glutaraldehyde, formaldehyde and pyruvic aldehyde. The optimal concentration of tannic acid has been found to be 1/40 000 for tanning both fixed and unfixed sheep erythrocytes. Tanned sheep erythrocytes sensitized with 50 Lf/ml of tetanus toxoid at pH 7.2 for one hour were the most sensitive. Although the optimal temperature of sensitization was found to be 56 degrees C, unfixed cells tended to clump and lyse at this temperature. Thus a temperature of 37 degrees C was used to sensitize unfixed sheep erythrocytes. Sheep erythrocytes from different animals and the final concentration of sensitized sheep erythrocytes both had great effects on sensitivity. A final concentration of 0.5% of sensitized sheep erythrocytes was found suitable as a compromise between sensitivity and readability. The loss of sensitivity of fixed and sensitized erythrocytes was investigated by storing these cells at 4-8 degrees C for six to nine months.     

Trypanosoma cruzi: Effect on B-cell-responsive and -responding clones

During the course of Trypanosoma cruzi infection in C57BL/6 mice, which are relatively resistant to the parasite, the hosts developed antibody activity against previously unencountered antigens. The anti-sheep erythrocyte and antitrinitrophenyl antibody levels increased rapidly from Day 7 of infection, reached a peak by the 21st day, and were maintained at this level through 120 days postinfection in these mice. In contrast, highly susceptible C3H(He) mice did not have demonstrable antibody responses to SRBC or TNP during the 24-day infection period. Autoantibody activity against the selfantigens presented on isologous erythrocytes or thymocytes, however, were reduced in infected C57BL/6 mice. No significant reduction in autoreactivity to the self-antigens on erythrocytes or thymocytes was observed in C3H(He) mice infected with T. cruzi although a trend of reduced autoresponsiveness toward erythrocytes appeared to be developing by the time of death. C57BL/6 mice immunized with sheep erythrocytes as neonates and infected with T. cruzi as adults, or adult mice primed with low doses of sheep erythrocytes prior to infection, had elevated antibody responses to sheep erythrocytes unless the mice were immunized with sheep erythrocytes during the course of infection, in which case suppression of the response against sheep erythrocytes resulted. The nonspecific synthesis of immunoglobulins in infected C57BL/6 mice was, in part, a result of the lymphocyteactivating properties of T. cruzi-associated antigens. The T. cruzi-associated antigens induced proliferative and differentiative responses in spleen cells in vitro. It is proposed that the T. cruzi-associated antigens differentially affect lymphocytes capable of responding to antigen and those lymphocytes previously stimulated by antigen.     

Effect of dietary selenium on the response of stressed and unstressed chickens toEscherichia coli challenge and antigen

Selenium was added to the feed of White Leghorn type chickens 1 day prior to challenge with eitherEscherichia coli or sheep erythrocyte antigen. the incidence of death or lesions was reduced from 86% to 21% at the optimal dose of selenium (0.4 mg/kg resulting in feed concentration of 0.45 mg/kg). After the chickens were stressed by chilling, selenium was ineffective againstE. coli. Dietary additions of selenium between 0.1 and 0.8 mg/kg resulted in an antibody titer increase from 2.2 to 3.9 to the log₂ against sheep erythrocytes (SRBC). Followng chilling, antibody titer response was reduced from 4.9 to 2.4 to the log₂. This titer reduction could be prevented with dietary additions of selenium between 0.1 and 1.2 mg/kg. The effects of a nitrofuran and selenium were additive againstE. coli challenge infection.