Anhydrobiosis in Pratylenchus penetrans

Anhydrobiotic survival of Pratylenchus penetrans was compared in several soil moisture regimes. Bodies of anhydrobiotic nematodes were coiled. In slow-dried soils, Vineland silt loam (VSL) and Fox loamy sand (FLS), 70 and 58% of the total P. penetrans populations were anhydrobiotic when soil moistures reached ca. 3% and water potential 15 kPa or greater. Coiling began at a much lower water potential in FLS than in VSL. In fast-dried soils, only 31 and 22% of the P. penetrans populations in the same two soil types had entered the anhydrobiotic state at comparable moistures. In the above soils, 76-96% of the P. penetrans were alive immediately after entering the anhydrobiotic state. In slow-dried VSL, some nematodes (1%) survived 770 days. In the other soils, all anhydrobiotic nematodes were dead after 438 days. Anhydrobiosis increased the ability of nematodes to survive subzero temperatures, but it did not increase their ability to survive temperatures above 40 C. Infectivity and reproductivity of rehydrated P. penetrans were not affected by anhydrobiosis.

Relative Tolerance of Selected Soybean Cultivars to Hoplolaimus columbus and Possible Effects of Soil Temperature

Eleven soybean [Glycine max (L.) Merr.] cultivars resistant to one or more plant-parasitic nematodes, and one resistant to the Mexican bean beetle (Epilachna varivestis Muls.), were tested for susceptibility to Hoplolaimus columbus. All cultivars were parasitized, but nematode reproduction varied. 'Pickett-71' was the most susceptible host among the cultivars tested. 'Dyer' and three 'P.I. cultivars' were most tolerant when yield /plant and total yield were compared for fumigated and unfumigated plots, even though their yield potential was low. 'Hardee,' 'Coker 4504,' 'W-4,' 'D71-9257,' and 'ED-371' appeared tolerant throughout the growing season and yielded well in unfumigated soil. Infection and reproduction of H. columbus in 'Forrest' soybean roots were greater at 30 +/- 1 C than at 20 or 25 +/- 1 C. Plant height and root weight varied with the soil treatments.

Effects of aldicarb on the behavior of Heterodera schachtii and Meloidogyne javanica

The toxic effects of sublethal concentrations of aldicarb were studied on eggs and second-stage larvae and males of Heterodera schachtii and second-stage larvae only of Meloidogyne javanica in a quartz sand substrate. Aldicarb was more toxic to eggs of H. schachtii than to those of M. javanica. Complete suppression of hatching occurred between 0.48 and 4.8 microg/ml aldicarb for H. schachtii whereas 100% inhibition of hatch of M. javanica occurred between 4.8 and 48.0 microg/ml. M. javanica hatch was stimulated at 0.48 microg/ml aldicarb. Migration of second-stage larvae of H. schachtii and M. javanica in sand columns was inhibited under continuous exposure to 1 microg/ml aldicarb. Infection of sugarbeet and tomato seedlings by larvae was inhibited at 1 microg/ml. H. schachtii males failed to migrate toward nubile females at 0.01 microg/ml aldicarb. This was partially confirmed in a field study in which adding aldicarb to soil resulted in fewer females being fertilized.

In vitro reassembly of shell-like particles from disrupted polyoma virus

When purified polyoma virus is exposed to 0.01 M dithiothreitol in the presence of 0.2 M Na(2)CO(3)-NaHCO(3) (pH 10.6) at 0-4 degrees C, the capsids are rapidly disrupted to protein subunits of capsomere size, as judged by density gradient centrifugation, sedimentation equilibrium centrifugation, and electron microscopy. Hemagglutination activity and infectivity of disrupted virus are reduced to below detectable amounts. Removal of the disruption reagents by dialysis at 4 degrees C against 0.05 M Tris-0.14 M NaCl-1 mM EDTA and 0.1 mM 2-mercaptoethanol (pH 8.0) results in a time-dependent reappearance of up to 17% of the starting hemagglutination titer, under optimum conditions of ionic strength, pH, temperature, and virus protein concentration. The recovered hemagglutination activity is found in glycerol gradients associated with a 100S DNA-protein complex consisting mostly of linear aggregates of capsomeres. When the linear complex is treated with pancreatic DNase, the complex is converted into spherical particles, of approximately virus size, that sediment at 140 S (with aggregates at 180 S), as well as on the cushion of half-saturated CsCl at the bottom of the gradients. All reassembled particles are not infectious and have markedly reduced DNA to protein ratios.