Immunological Activity of Leptospira Pomona Bacterins

Seven commercially available leptospiral bacterins were compared in guinea pigs and on that basis two of them, the best and the poorest, were further compared in calves. A wide variation was observed in their antigenicity and in their ability to provide protection. Guinea pigs appeared to be satisfactory test animals for evaluation of bacterins prepared for use in cattle.     

Toxoplasmosis II. Studies of Animal Sera Using Complement-Fixation Tests

Serological studies were performed in guinea pigs, a sheep, calf, goat and two pigs experimentally infected with toxoplasmosis. The direct complement-fixation method was effective in detecting antibodies in guinea-pig, goat and sheep sera. The modified complement-fixation technique supplementing complement with normal bovine serum fraction, was required when testing bovine serum. With swine sera best reactions occurred in the indirect complement-fixation test and definite but low grade reactions were produced in the direct test after pro-complementary activity was removed by pH treatment of the sera. Allergic skin reactions were produced in the experimental animals but improvement in the antigen is necessary before the test could be used generally in the field as a diagnostic method for animal toxoplasmosis.     

Identification of a Novel Cryptosporidium Genotype in Pigs

Over a 3-year period, a total of 646 fecal samples from pigs in 22 indoor and outdoor herds from Western Australia were screened for Cryptosporidium spp. by microscopy. Results revealed that 39 of 646 samples (6.03%) were positive for Cryptosporidium. Cryptosporidium was much more common in outdoor herds (17.2%) than in indoor herds (0.5%) and was more common in animals between the ages of 5 and 8 weeks (69.2%) than in younger animals (P < 0.0001). Molecular characterization of the positive samples at the 18S ribosomal DNA locus identified two distinct genotypes of Cryptosporidium: the previously identified pig genotype I and a novel pig genotype (pig genotype II), both of which warrant species status.     

Chorusing Behaviour,a Density-dependent Alternative Mating Strategy in Male Common Toads (Bufo bufo)

Male chorusing behaviour was studied in a population of common toads (Bufo bufo) on the island of Öland south Sweden, and the functional role of male advertisement calling in this species was experimentally examined. Calling males were larger and heavier than non-calling males (t = 2.41, p < 0.025 and t = 2.36, p < 0.025, respectively). However, small males were also found to call. This indicates that large males persisted in calling for longer and/or called more often. The proportion of calling males decreased as population size increased during the breeding season, indicating that calling is a low density strategy. Females responded more readily to calls than males. There were insufficient data to determine if the dominant frequencies of advertisement calls were inversely correlated with male body size, however, this relationship was found for the similar release calls. Females were found not to discriminate between high and low frequency calls, but when given a choice between two calls of different sound pressure levels (SPL), females were attracted to the louder calls. Thus, the function of chorusing is to advertise the position of males to mate-seeking females when the population density is low.     

Mutations in the X-linked E1 alpha subunit of pyruvate dehydrogenase: exon skipping, insertion of duplicate sequence, and missense mutations leading to the deficiency of the pyruvate dehydrogenase complex.

Human pyruvate dehydrogenase (PDH)-complex deficiency is an inborn error of metabolism that is extremely heterogeneous in its presentation and clinical course. In a study of 14 patients (7 females and 7 males), we have found a mutation in the coding region of the E1 alpha gene in all 14 patients. Two female patients had the same 7-bp deletion at nt 927; another female patient had a 3-bp deletion at nt 931. Another female patient was found to have a deletion of exon 6 in her cDNA. Two other female patients were found to have insertions, one of 13 bp at nt 981 and one of 46 bp at nucleotide 1078. Two male patients were found to have a 4-bp insertion at nucleotide 1163. The remaining six patients all had missense mutations. A male patient and a female patient both had an A1133G mutation. The other missense mutations were C214T, C615A, and C787G (two patients). Five of these mutations are novel mutations, five have been previously reported in other patients, and two were published observations in other patients in an E1 alpha-mutation summary. In the four cases where parent DNA was available, only one mother was found to be a carrier of the same mutation as her child.     

Interactions of yeast tRNAPhe with ribosomes from yeast and Escherichia coli. A fluorescence spectroscopic study.

The interaction of ethidium-labeled tRNAPhe from yeast with ribosomes from yeast and Escherichia coli was studied by stead-state measurements of fluorescence intensity and polarization. The ethidium label was covalently inserted into either the anticodon or the dihydrouridine loop of the tRNA. The codon-independent formation of a tRNA-ribosome complex led to only a moderate increase of the observed fluorescence polarization indicating a considerable internal mobility of the labeled parts of the tRNA molecule in the ribosome complex. When the ribosome complex was formed in the presence of poly(U), the probes both in the dihydrouridine loop and in the anticodon loop were strongly immobilized, the latter exhibiting a substantial increase in fluorescence intensity. A smaller intensity change was observed when E. coli ribosomes were used, although the extent of immobilization was found to be similar in this case. Competition experiments with non-labeled tRNAPhe showed that the labeled tRNAPheEtd was readily released from the complex with yeast ribosomes when poly(U) was absent, whereas in the presence of poly(U) it was bound practically irreversibly. The finding that the mobility of a probe in the dihydrouridine loop is affected by the codon-anticodon interaction on the ribosome suggests a conformational change of the ribosome-bound tRNA which may involve opening of the tertiary structure interactions between the dihydrouridine and the TpsiC loop.