Agammaglobulinemia in a horse with evidence of functional T lymphocytes.

Agammaglobulinemia was diagnosed in a 1-year-old Thoroughbred horse on the basis of the following observations: (1) absence of serum immunoglobulins M, A, and G(T); (2) small amounts of serum immunoglobulin G (16 mg/100 ml); (3) absence of specific antibody in the serum of the horse following immunization and challenge exposure to 2 antigens; (4) absence of plasma cells, primary follicles, and germinal centers in a lymph node removed after antigenic stimulation; (5) absence of "natural" serum antibodies to rabbit-erythrocytes which were easily detectable in age-matched control horse serums; and (6) increased susceptibility to infections. There was evidence of functional cell-mediated immunity which included a skin response to injected phytolectins, skin response to antigen challenge following sensitization, and in vitro proliferative response of lymph node cells to phytohemagglutinin. An intact cell-mediated immune response was also supported by the observation that the horse lived to 17 months of age without antibody production, whereas horses with an absence of both antibody production and cell-mediated immunity (combined immunodeficiency) die by 4 months of age without immunologic intervention. The known features of agammaglobulinemia in this horse are similar to those in sex-linked agammaglobulinemia in persons and are unique among the immunodeficiences described in other animals.     

A simple method for isolating leucocytes from bovine blood and their separation into lymphocyte and granulocyte fractions.

A method for the separation of leucocytes from bovine blood and its separation into lymphocyte and granulocyte fractions is described. The method, involving flash lysis of the erythrocyte population, was found to yield large numbers of viable cells suitable for maintenance in tissue culture medium and hence of value in immunological studies.     

Mercury residues in breast muscle of wild ducks, 1970-71.

Samples of breast muscle from 327 ducks collected from October 1970 to March 1971 in the conterminous United States were analyzed for total mercury by flameless atomic absorption spectrometry. Mercury levels for the entire collection ranged from less than 0.01 to 3.91 ppm wet weight with a median of 0.10 ppm. Twenty-five ducks had levels equalling or exceeding the 0.5 ppm guideline for fish and shellfish established by the Food and Drug Administration, U.S. Department of Health, Education, and Welfare. Dabbling ducks, which are shallow-water feeders and mostly vegetarian in fall, winter, and spring, usually had lower levels than diving and sea ducks. Levels were generally higher in ducks collected in areas where environmental mercury levels were known to be greater than in ducks from nonsuspect areas. Despite the mobility of the ducks, levels seemed more closely linked to local environmental contamination than to various factors associated with large geographic areas.     

Prepenetration stages in infection of clematis by Phoma clematidina

A detailed study of conidial germination, germ-tube growth and the formation of infection structures in Phoma clematidina , the causal agent of clematis wilt, is described for two clematis varieties differing in disease resistance. On both the resistant and susceptible varieties, the fungus entered leaves and stems by direct penetration of the cuticle, often, but not always, following the formation of infection structures. More germ tubes per conidium were formed on the susceptible host, but these germ tubes were on average shorter than on the resistant host. Although germ tubes regularly entered the plant via trichomes, stomata were not found to be sites of entry. Following penetration of the cuticle of resistant plants, germ-tube growth was sometimes restricted to the subcuticular region, and halo formation occurred at the sites where penetration was attempted. Subcuticular growth and halo formation were not observed on susceptible plants. These observations may partly explain the resistance of small-flowered clematis varieties to P. clematidina .     

Non-structural plum pox potyvirus proteins detected by immunogold labelling

Plum pox potyvirus (PPV) induces in infected Nicotiana clevelandii cells characteristic crystalline inclusions known as nuclear inclusions (NI) when located in the nucleus and as dense material (Dm) when located in the cytoplasm. Crystalline inclusions contain protease (NIa) and RNA-dependent RNA polymerase (NIb) proteins. It is now well established for all potyviruses that cylindrical inclusions contain CI helicase ATPase protein (Martin et al., 1992). The intracellular location of other non-structural PPV proteins remains unknown. Using Escherichia coli expression vectors, specific antibodies were obtained against P1, P3, 6K2 and NIb PPV proteins for which antibodies were not yet available. As expected, NIb antiserum labelled crystalline inclusions. P1, P3 and 6K2 proteins were present in both types of crystalline inclusions found in the nucleus and in the cytoplasm of PPV-infected leaves of N. clevelandii, suggesting that nuclear inclusions and dense material were composed of the same proteins. This composition is discussed.