Selection of social partners as a function of peer contact during rearing

In the report "Selection of social partners as a function of peer contact during rearing" by C. L. Pratt and G. P. Sackett (3 Mar., p. 1133), the third sentence of the first paragraph should read as follows: "Monkeys reared in isolation tend to withdraw from other animals and huddle by themselves in social situations. If such animals prefer each other over more normal monkeys, they may not be effectively exposed to the stimuli which lead to some degree of social adjustment."     

Polychlorinated biphenyls and other organic chemical residues in fish from major United States watersheds near the Great Lakes, 1978

Twenty-six composite samples of fish were collected during 1978 from United States watersheds near the Great Lakes and analyzed for polychlorinated biphenyls (PCBs) and related organic chemicals. PCB mixtures resembling Aroclor 1254 were found in all samples, and mixtures resembling Aroclor 1242 (or 1016) were found in 77 percent of the samples. Total PCB concentrations in the whole-fish composite samples ranged from 0.13 to 14.6 ppm; 65 percent of the samples contained more than 2 ppm PCBs. DDT and its metabolites were found in all samples. sigma DDT concentration was 1.66 ppm, and 81 percent of the samples contained less than 1.0 ppm sigma DDT. Chlordane ranged from less than 0.001 to 2.57 ppm in 38 percent of the samples. Hexachlorobenzene was found in 65 percent of the samples, ranging from less than 0.005 to 0.447 ppm. Other chemicals identified by gas chromatography/mass spectrometry included petroleum hydrocarbons and chlorobenzenes, chlorostyrenes, chlorophenols, and chlorinated aliphatic compounds. Fish from the Ashtabula River (Ohio), Rock River (Ohio), and Wabash River (Indiana) contained extremely complex residues of chlorinated and other organic chemicals.     

Dose titration of oxfendazole against common nematodes of swine.

Oxfendazole, a benzimidazole carbamate, was administered as a 0.5% feed additive to 88 pigs naturally infected with two to four nematode species. Dose rates of 1.5 mg/kg of body weight, 3.0 mg/kg, 3.75 mg/kg, 4.5 mg/kg, 6.75 mg/kg, or 9.0 mg/kg were 100% efficacious against Oesophagostomum dentatum and 99.2% to 100% effective against Ascaris suum. Dose rates of 4.5 mg/kg, 6.75 mg/kg, and 9.0 mg/kg were 92.7%, 98.9%, and 99.5% effective, respectively, against mixed populations of Metastrongylus apri and M pudendotectus. Results were variable with Trichuris suis infections. Efficacy was based on the number of nematodes recovered at necropsy. Palatability and acceptability of the feed additive were good, and adverse reactions following administration were not observed.     

Heritability and Components of Resistance to Cercospora zeae-maydis Derived from Maize Inbred VO613Y

ABSTRACT Gray leaf spot (GLS), caused by the fungus Cercospora zeae-maydis, is one of the most important foliar diseases of maize. This study was undertaken to estimate heritability of C. zeae-maydis resistance and examine the relationship between previously identified resistance loci and certain components of resistance including incubation period, lesion number, and maximum lesion length. Partially inbred progenies arising from hybridization between maize inbred lines VO613Y (high level of partial resistance) and Pa405 (susceptible) were examined in Ohio and South Africa. Heritability estimates of resistance were calculated based on severity and incubation period values. The range of heritability estimates based on severity was broad, with values ranging from approximately 0.46 to 0.81 (mean = 0.59). Estimates of mean heritability for incubation period were lowest (0.18), indicating that this component would likely be unsuitable for selection of germ plasm intended for deployment in diverse regions. Length of GLS lesions was significantly affected by host genotype, with resistant genotypes having shorter lesions from one site in Ohio during two seasons. Genotype also had a significant effect on incubation period and lesion number; the lower values for these components also were associated with resistant genotypes. The combined action of these resistance components resulted in lower overall disease severity.