Eimeria acervulina infections from each of the four sporocysts of a single oocyst

Oocysts were found in all four birds each infected with one of the four sporocysts of a single oocyst of Eimeria acervulina and in three of the four birds infected with single sporocysts from two other oocysts. Possible use of these infections for genetic studies was discussed. An efficient method for collecting fecal material containing sometimes rather low levels of oocysts was also described.

Selective killing of macrophages in the peritoneal cavity by carrageenan and its effect on normal infection of Eimeria tenella in chickens

An in vivo method is described showing how selective killing of macrophages in the peritoneal cavity by carrageenan affects Eimeria tenella infection in chickens. Killing of macrophages was demonstrated by the increasing loss of cytoplasmic contents under light microscopy, by the disappearance of mitochondria and endoplasmic reticulum ultrastructurally, and by the about 10%-per-hr loss of nonspecific esterase activity as uptake of carrageenan increased. Heterophils were apparently unaffected. Effect of such a selective killing on E. tenella infection seemed to be greatest when the carrageenan was injected intraperitoneally 24 hr before oocyst inoculation per os, but effect after the oocysts were inoculated was minimal or nonexistent. That chickens injected with carrageenan twice (once 24 hr before and once 48 hr after E. tenella inoculation) showed higher lesion scores with 15,000 oocysts than the controls showed with 60,000 oocysts further demonstrated the participation of macrophages in E. tenella infection.

Retardation of Senescence in Red Clover Leaf Discs by a New Antiozonant, N-[2-(2-Oxo-1-imidazolidinyl)ethyl]-N'-phenylurea

Dark-induced senescence in leaf discs from O(3)-sensitive red clover trifoliates (Trifolium pratense L. cv. ;Pennscott') was markedly retarded by treatment with N-[2-(2-oxo-1-imidazolidinyl)ethyl-N'-phenylurea (EDU). EDU also protects against acute and chronic foliar O(3) injury when sprayed on intact leaves or supplied to the plants through soil application. Senescence retardation was measured by time-dependent analyses of chlorophyll, protein, and RNA in discs floated on aqueous EDU solutions ranging from 0 to 500 micrograms per milliliter EDU. Chlorophyll degradation, total protein, and nucleic acids were followed over 10-day test periods.EDU at 500 micrograms per milliliter (50 milligrams per pot), a concentration known to provide optimal protection to intact leaves against O(3) injury, was most effective in preventing chlorosis and in maintaining high concentrations of protein and RNA in the discs. In discs treated with 500 micrograms per milliliter EDU 90% of the chlorophyll was retained after 10 days in the dark. In contrast, lower concentrations (0, 125, and 250 micrograms per milliliter) showed the complete loss of chlorophyll or an intermediate retardation. The intermediate concentrations were similarly less effective in maintaining protein and RNA levels in the dark stressed leaf discs. It is suggested that EDU retards senescence and mitigates O(3) injury through the induction of specific free radical scavenging enzymes and in sustaining RNA and protein synthesis.

A method for isolating the two sporozoites of a single sporocyst of Eimeria acervulina

A micromanipulation technique for isolating the two sporozoites of a single sporocyst of Eimeria acervulina is described.

Orthotopic bone transplantation in mice. II. Studies of the alloantibody response

The alloantibody response of mice receiving cortical bone allografts was investigated. Such grafts were highly immunogenic, resulting in antibody responses at least as strong as those to skin allografts in the same combinations. The duration of the response to a single bone allograft was very prolonged (greater than 10 months). The antibody response was shown to be directed against H-2K, H-2D, Ia, and at least two non-H-2 antigens. Although the great majority of the parenchymal cells of the graft were dead, the immunogenicity of the graft required living cells, since bone that had previously been frozen and thawed was nonimmunogenic. By retransplanting bone allografts to a second recipient it was possible to demonstrate that the grafts remained immunogenic for at least 4 weeks after transplantation, indicating that the living immunogenic cells survived in the recipient for at least 4 weeks. Such cells may be certain cells of the cortical bone itself, or else residual bone marrow elements which adhere to the endosteal surface of the bone. The observation that a small subpopulation of living cells can provoke strong immune responses against a wide variety of antigens may have implications for understanding the immunogenicity of other types of allografts.

Orthotopic bone transplantation in mice. I. Technique and assessment of healing

A technique for orthotopic bone transplantation in mice has been developed. A section of recipient tibia was removed and replaced by a similar section from the donor animal. The graft was held in place by internal fixation. Bone healing was assessed clinically, histologically, radiologically, and by torsion testing. The most objective measurements of bone healing were the maximum torque and the energy absorbed by the bone to failure, which were derived from torsion testing. The degree of bone healing in donor-recipient combinations differing at H-2, non-H-2, or H-Y antigens was compared to the degree of healing in syngeneic controls. The incidence of nonunion was significantly increased in the H-2-disparate group. Furthermore, the extent of bone healing as measured by torsion testing was significantly reduced in both the H-2-and the H-Y-disparate groups. Thus, in the strain combinations tested, the order of importance of the genetic disparities influencing allogeneic bone grafts was H-2 greater than H-Y greater than non-H-2. The impaired healing of allogeneic bone grafts was probably immunologically mediated, as suggested by the observation that recipients of bone allografts rejected subsequent skin allografts in an accelerated manner.

Single and low-level oocyst infections of drug-resistant field strains of Eimeria tenella in medicated birds

Five out of ten birds infected with a single oocyst of strain Gt2 of Eimeria tenella and medicated with the recommended level of robenidine were found positive in the first experiment and four in the second in comparison with seven and six respectively in nonmedicated birds. Six birds out of ten were found positive in the two groups of similarly medicated birds infected with two or four oocysts each. Although single oocyst infections of strain Lilly 155 were unsuccessful, six out of ten birds were found positive in birds infected with ten oocysts each.All single and low-level oocyst infections were accomplished with oocysts previously treated with beta-glucuronidase and broken into sporocysts prior to infections. The overall results suggested that when a coccidium became resistant to an anticoccidial drug, only one or a few occysts were needed to start an infection if the drug was continued. The results also showed that, perhaps, successful single or low-level oocyst infections can also be used as a criterion for demonstrating drug resistance in coccidia.

Immunogenicity of a single sporocyst of Eimeria maxima

Eight out of a total 40 chickens infected with single sporocysts of Eimeria maxima produced infective oocysts. These 8 chickens, when challenged with 4 X 10(5) oocysts per bird at 28 days postinfection, showed at least twice the percent average weight gain of the previously unexposed chickens, indicating that partial immunity was probably conferred by these infections. Also, these successful single sporocyst infections suggest that like E. tenella, sporozolles of E. maxima are probably sexually undifferentiated.

Drug resistance in coccidia: a robenidine-resistant strain of eimeria tenella

Tests for resistance to a recently introduced anticoccidial drug, robenidine, were performed on a strain of Eimeria tenella recovered from broiler chickens infected with acute cecal coccidiosis. The strain was identified previously and again confirmed by the timing of mortality of the infected chickens (five to six days postinfection), the appearance of lesions and parasites in ceca only, and the measurements (21.6 +/- 1.9 micron X 19.8 +/- 2.4 micron) of the oocysts. The tests showed that the strain of E. tenella could establish infections in chickens medicated with fourfold the recommended level of robenidine in feed but no oocysts could be recovered from the feces of infected chickens when the level of drug was increased to eightfold. The decrease in mortality, in the severity of lesions and oocyst output and the increase in the average weight gain of infected chickens followed closely the increase in the level of robenidine in feed. In contrast, no infections were found in chickens infected with a sensitive strain of E. tenella and maintained on feed mixed with the recommended level of robenidine. This and other findings discussed here show that resistance to robenidine is developing in coccidia commonly found in broiler houses.

Studies on IgE in human intestinal fluids

A fragment of IgE with molecular weight of about 40,000 was identified by radioimmunoassay in human small intestinal fluid after fractionation by gel filtration chromatography. Digestion of E myeloma protein PS by pooled intestinal fluid, trypsin or chymotrypsin yielded a degradation product of similar molecular weight that probably consisted principally of epsilon 1 determinant-containing fragments. These findings suggest that IgE is secreted into the intestinal lumen and degraded there by pancreatic proteolytic enzymes, producing an enzyme-resistant portion of the amino-terminal part of the Fc region.

A new method of obtaining zygotes in Saccharomyces cerevisiae

Experiments leading to a simple method of mass zygote formation in Saccharomyces cerevisiae are described. This method ordinarily requires only about 3 h of incubation, and consistently yielded 55-65% zygotes in seven different crosses among six different strains. Matings involving one strain required about 4 h of incubation but otherwise the results were comparable.

Effects of variations in temperature on infective larvae and their relationship to inhibited development of Obeliscoides cuniculi in rabbit

The relationship between changes in the temperature of storage of infective O. cuniculi larvae and the proportion that become inhibited in a subsequentinfection was studied. Prolonged storage at 5°C resulted in an initial inhibitionfollowed by acclimation to this temperature and subsequent normal developmentin the host. After acclimation to low temperature raising the temperature ofstorage produced no appreciable increase in the proportion of worms inhibited atthe early 4th stage. Maintenance of infective larvae at 15°C followed by a suddendecrease in storage temperature to 5°C resulted in rapid onset of inhibition. This inhibition was not reversed even after 25 days at the lower temperature. These temperature variations and the consequent pattern of arrested development werecompared to seasonal changes of spring and autumn occurring to nematode larvaeon pasture. An increase in the number of larvae given from 5000 to 15000 perrabbit had a slightly significant effect upon the proportion that remained inhibited. The need for careful assessment of the methods used for determining the extentof such inhibition is discussed.