Effect of Planting Date,Alachlor, and Fenamiphos on Heterodera glycines Development

The effects of alachlor (2.25 kg a.i./ha) and fenamiphos (2.25 kg a.i./ha) on the penetration and development of Heterodera glycines were examined on Glycine max cultivars Deltapine 105 planted 29 April, 29 May, and 29 June 1986 and Deltapine 105 and Centennial planted 15 May, 15 June, and 15 July 1987. Penetration was lowest on the third planting of soybeans and on fenamiphos-treated plants. Development from second-stage juveniles to adult females required 270 (1986) and 260 (1987) DD20/32 on roots from the first planting control and alachlor treatments. Fenamiphos, alone or with alachlor, retarded development in Deltapine 105 (1986) and in Centennial (1987). Males matured in roots from the second planting in 190 (1986) and 180 (1987) DD20/32 regardless of treatment or cultivar. No development occurred in roots from the third planting until 400 DD20/32 in 1986, but in 1987 development was similar to that in roots from the second planting. Nematode development was similar in alachlor-treated and control roots regardless of planting date. Fenamiphos restricted nematode penetration on most planting dates and slowed development. Simultaneous applications of alachlor and fenamiphos usually also inhibited development.     

Use of a quaternary ammonium detergent in liposome mediated DNA transfection of mouse L-cells

Sonicated liposomes composed of dioleoylphosphatidylethanolamine (DOPE) and a quaternary ammonium detergent (dodecyl-, tetradecyl-, or cetyl-trimethylammonium bromide) mediates functional transfer of pSV2 CAT plasmid DNA to mouse L929 fibroblasts. Successful transfection was determined by assaying for chloramphenicol acetyltransferase activity in cell lysates collected 40 h after exposure to the lipid-DNA complexes. Liposomes prepared with the quaternary ammonium detergents were less toxic than the free detergents at the same concentrations and were more efficient in their delivery of the plasmid DNA to the cells. Analysis of the three detergents in combination with the lipid showed that cetyltrimethylammonium bromide was least toxic to the cells. This detergent, at a minimal concentration of 20 mol% in DOPE, allowed for stable liposome preparations and efficient transfection. Optimal efficiency of transfection occurred with 30 micrograms of DNA. Further increases in the DNA concentration caused a decrease in the transfection efficiency, perhaps due to charge repulsions between the liposomes now saturated with negatively charged DNA and the negatively charged cell surface. The transfection activity of the liposome was limited by its cytotoxicity at high liposome concentrations. These results are compared with that of the Lipofectin, another positively charged liposome preparation which is commercially available. Although the overall transfection activity of the liposome containing the quaternary ammonium detergent is somewhat lower than that of the Lipofectin, it may serve as an inexpensive and convenient alternative.     

Expression of Thomsen-Friedenreich (TF) antigens on lymphocytes. I. Distribution of cryptic and exposed TF antigens on murine lymphocytes from different lymphoid organs: detection with an anti-TF monoclonal antibody and peanut agglutinin

Cryptic Thomsen-Friedenreich (TF) antigens were detected by the lectin peanut agglutinin (PNA) on the surface of murine lymphocytes after treatment of cells with neuraminidase. Thereby, a particular TF antigen could be distinguished using a monoclonal anti-TF antibody 49H8. In contrast to the known general galactoside specificity of PNA, the mAb was restricted to Gal beta(1-3)GalNAc/GlcNAc. Preincubation of cells with PNA abolished mAb 49H8 binding completely. However, only the intensity of staining with PNA was reduced by prior incubation of cells with the mAb. Cryptic TF antigens detected by the mAb were expressed on 39% of murine bone marrow cells, 88% of thymocytes, 62% of lymph node cells, and 65% of spleen cells. On the other hand, over 80% of the lymphatic cells carried cryptic PNA binding sites independent of the lymphoid organ they derived. In the thymus, a subpopulation of cells (76%) could be detected by PNA without neuraminidase treatment. Twenty-eight percent of thymocytes carried exposed mAb binding sites, too. All of them were shown to express further binding sites for PNA constantly. Therefore, a subpopulation of PNA-reactive, immature thymocytes can be distinguished by the mAb 49H8. During activation of splenic lymphocytes with PHA, the lymphoblasts completely lost their cryptic mAb binding sites while PNA reactivity was not affected. We conclude that the anti-TF mAb recognizes a particular TF antigen exposed on thymocytes and present in a cryptic form on other lymphocytes. The number of cells carrying mAb 49H8 binding sites varied, dependent on the organ from which the lymphocytes derived. PNA-reactive lymphocytes are distributed homogeneously in the lymphoid organs.     

The context theory as applied to the decoding of the initiator tRNA by Escherichia coli ribosomes

The involvement of nucleotides adjacent to the termination codons in tRNA during the suppression of termination has been formulated as the 'context theory' by Bossi and Roth (1980) [Nature (Lond.) 286, 123-127]. The finding that U-U-G functions as an initiator codon has revived the discussion on the participation of the nucleotides flanking the initiator triplet in the decoding of initiator tRNA (context theory of initiation by the ribosome). We compared the capacity of oligonucleotides cognate to the anticodon loop of formylmethionine tRNA, such as A-U-G, A-U-G-A and U-A-U-G-A, to enhance the formation of the 30-S and 70-S ribosomal initiation complexes. Three different methods were used to determine the apparent binding constants and the stoichiometries of the respective complexes: adsorption of the complexes to nitrocellulose filters, equilibrium dialysis, and velocity sedimentation. We found that in the 30-S ribosomal initiation complex and in the presence of initiation factor 2 and GTP, formylmethionyl-tRNA is preferentially decoded by more than three mRNA bases. With the 70-S ribosome, however, once initiation factor 2 had been released, A-U-G represented the most effective codon to direct the formylmethionyl-tRNA to the peptidyl site. An extended initiator sequence may either give additional stability to the 30-S initiation complex or may allow for an ambiguity by one base pair in the decoding of the initiator tRNA.     

Influence of Nitrate and Ammonia on Photosynthetic Characteristics and Leaf Anatomy of Moricandia arvensis

The leaf anatomy and certain photosynthetic properties of nitrate- and ammonia-grown plants of Moricandia arvensis (L.) DC., a species previously reported to be a C₃-C₄ intermediate, were investigated. Nitrate-grown plants had a high level of malate in the leaves while ammonia-grown plants had low levels of malate. In young leaves of nitrate-grown plants, there was a diurnal fluctuation of malate content, increasing during the day and decreasing during the night. Titratable acidity remained low in leaves of both nitrate- and ammonia-grown plants.

In nitrate-grown plants, the activity of phosphoenolpyruvate (PEP) carboxylase was about 2-fold higher than in ammonia-grown plants, the latter having activity typical of C₃ species. Also, in nitrate-grown plants, the ratio of activities of ribulose 1,5-bisphosphate (RuBP) carboxylase/PEP carboxylase was lower than in ammonia-grown plants. Nitrate reductase activities were higher in nitrate- than in ammonia-grown plants and the greatest activity was found in younger leaves.

With nitrate-grown plants, during a pulse-chase experiment the label in malate, as a percentage of the total labeled products, increased from about 7% after a 10-second pulse with ¹⁴CO₂ up to 17% during a 5-minute chase with ¹²CO₂. The pattern of ¹⁴C labeling in various metabolites suggests the primary carboxylation is through RuBP carboxylase with a secondary carboxylation through PEP carboxylase. In similar experiments, with ammonia-grown plants, the percentage label in malate was only 0% to 4% with no increase in malate labeling during the chase period. The CO₂ compensation point was lower in nitrate-grown than ammonia-grown plants.

There was no evidence of Kranz-like anatomy in either the nitrate or ammonia-grown plants. Mitochondria of bundle-sheath cells were strikingly positioned along the inner tangential wall. This might allow the chloroplasts of these cells to fix the mitochondrial photorespired CO₂ more effectively and contribute to the low CO₂ compensation point in the species. Chloroplasts of bundle-sheath cells and contiguous mesophyll cells were similar in size and structure in plants grown on different media, although chloroplast thylakoids and stromata of the ammonia-grown plants stained more intensely than those of nitrate-grown plants. In addition, irregular clusters of phytoferritin particles occurred in the chloroplasts of the ammonia-grown plants.

The results indicate that the substantial activity of PEP carboxylase, incorporation of CO₂ into malate, the high malate content, and in part the relatively low CO₂ compensation point in Moricandia arvensis may be accounted for by metabolism of nitrate rather than by a state of C₃-C₄ intermediacy.

     

Further evidence validating adjuvant arthritis as an experimental model of chronic pain in the rat

The experiments described here were aimed at further validating adjuvant arthritis as an animal model of chronic pain. It was found that the relative oral intake of a 0.008 mg/ml solution of fentanyl was higher in arthritic than in normal control rats; this difference was predicted by the notion that the analgesic effect of a substance may reinforce its intake in animals exposed to pain, more so than in normal pain-free animals. It was also found that body weight decreases and that vocalizations of aggregated rats increase as a result of the challenge; these effects suggest that the vegetative signs and the behavioral irritability which are characteristic of chronic pain in humans, also occur in arthritic animals. The pain which thus seems to be associated with adjuvant arthritis was estimated to have its onset on days 10–11, to peak on days 18–21, and to terminate on days 35–40 after inoculation with $\text{Mycobacterium butyricum}$.     

Contrsating anti-predator defenses of sympatric marine gastropods (family Trochidae)

Three of four sympatric gastropods found in southern California waters, Tegula aureotincta Forbes, Norrisia norrisi (Sowerby), and Astraea undosa (Wood), display behavioral flight responses to predatory asteroids and a gastropod. The fourth species, Tegula eiseni Jordan, lacks this behavior but does have morphological features that deter predators. The shell of T. eiseni is thicker and the tissue more difficult to acid hydrolyze than that of its sympatric congener, T. aureotincta. Juvenile seastars fed T. aureotincta grew three times faster than those reared on T. eiseni. The dissimilarity in growth rates is not attributed to differences in nutritive value of the two Tegula species, but is due to differences in the rate at which the seastars can consume the snails. Laboratory choice tests demonstrate that the anti-predator defense of T. eiseni reduces its acceptability as food. In contrast, the behavioral flight defense of the three remaining gastropods decreases the probability of their capture by certain predators.     

Interaction of Fensulfothion and Phorate with Preemergence Herbicides on Soybean Parasitic Nematodes

The herbicides alachlor, linuron, vernolate, and metribuzin were applied to plots treated with the nematicide fensulfothion or the insecticide phorate and planted to soybean in two locations in North Carolina. In 1976 treatment with fensulfothion + alachlor or vernolate, phorate + alachlor or metribuzin resulted in greater nematode population densities than no treatment, or treatment with fensulfothion alone, or phorate alone. In 1977 fensulfothion and phorate alone and in combination with the preemergence herbicides effectively controlled Tylenchorhynchus cIaytoni. Late season population resurgence of Heterodera glycines occurred in fensulfothion + alachlor treated plots. Correlation coefficients for H. glycines vs. yield were -0.48 (P = 0.05) and -0.46 (P = 0.05) for 30 and 68 d after planting, respectively.