Early transcription in Caenorhabditis elegans embryos

We have analysed early transcription in devitellinized, cultured embryos of the nematode Caenorhabditis elegans by two methods: measurement of [32P]UTP uptake into TCA-precipitable material and autoradiographic detection of [3H]UTP labelling both in the presence and absence of alpha-amanitin. RNA synthesis was first detected at the 8- to 12-cell stage, and alpha-amanitin sensitivity also appeared at this time, during the cleavages establishing the major founder cell lineages. The requirements for maternally supplied versus embryonically produced gene products in early embryogenesis were examined in the same culture system by observing the effects of alpha-amanitin on cell division and the early stereotyped lineage patterns. In the presence of high levels of alpha-amanitin added at varying times from two cells onward, cell division continued until approximately the 100-cell stage and then stopped during a single round of cell division. The characteristic unequal early cleavages, orientation of cleavage planes and lineage-specific timing of early divisions were unaffected by alpha-amanitin in embryos up to 87 cells. These results indicate that embryonic transcription starts well before gastrulation in C. elegans embryos, but that although embryonic transcripts may have important early functions, maternal products can support at least the mechanics of the first 6 to 7 cell cycles.

Autoradiographic Detection of Lesser Cornstalk Borer (Lepidoptera: Pyralidae) Eggs in Soil Environments

A nondestructive method of detecting lesser cornstalk borer, Elasmopalpus lignosellus (Zeller), eggs in soil is outlined. Fourth instar larvae were fed a diet containing radioactive phosphorus (4 μ Ci/g), and eggs laid by females that emerged from these larvae contained sufficient radioactivity to expose X-ray film. Fecundity, oviposition rates, and longevity were similar for 32P-labeled adult females and unlabeled adult females. In greenhouse tests using corn planted in simulations of conventional tillage and no-tillage conditions, eggs were autoradiographically detected in soil and on plant tissue.

Fate and Transport of Alachlor, Metolachlor and Atrazine in Large Columns

14C ring-labelled atrazine, alachlor, and metolachlor were surface-applied at 3.14 kg a.i./ha in greenhouse lysimeters containing two soils in an ongoing experiment. Bromide (Br) – a conservative tracer – at 6.93 kg/ha as KBr and nitrate-nitrogen (NO3-N) at 112 kg/ha as KNO3 were mixed with each herbicide and surface-applied. Growth of Red top (Agrostis alba) was established in each column (105 cm long and 29.4 cm i.d.). The experiment consisted of 12 columns (2 soils × 3 herbicides × 2 replicates) each fitted with four sampling ports for leachates, a volatilization chamber, and an aeration and irrigation system. Volatile materials are being trapped directly in solvents. One column replicate was dismantled for soil and plant analyses. Columns of Plainfield sand and Piano silt loam treated with alachlor and metolachlor were sampled after 23 and 28 weeks, respectively; the atrazine columns after 35 weeks. Herbicide residues are determined by liquid scintillation counting, extracted and separated by thin-layer chromatography using autoradiographic detection. Volatilization was ≤ 0.01% of the amount of herbicide applied. The order of herbicide mobility was alachlor > metolachlor >> atrazine. As many as 8 to 12 alachlor metabolites and 2 to 6 metolachlor metabolites were separated in leachates.