Karl H. Deubert

Studies on the biodegradation of parathion

SummaryFour compounds formed as the results of parathion degradation byChlorella pyrenoidosa proteose were identified or partly characterized in these studies. The major parathion metabolite, aminoparathion, was shown by bioassay to be nontoxic to vinegar flies at the levels tested. Evidence is presented that aminoparathion is released rapidly from algal cells after this compound is formed from parathion. Metabolites of unknown chemical structure which were detected were partially characterized as follows:Metabolite 1- contains sulfur and phenyl ring, strong cholinesterase inhibitor.Metabolite 2- contains sulfur, lacks phenyl ring, not a cholinesterase inhibitor at levels tested.Metabolite 3- contains phenyl ring but not sulfur, a strong cholinesterase inhibitor. Probably an oxon of parathion. The findings herein support previous conclusions that biotic forces, rather than abiotic factors, are of greater importance to the degradation of parathion under natural conditions extant in a temperate climate.

Biogenic amines in the free-living nematode caenorhabditis briggsae

Abstract Dopamine, epinephrine, norepinephrine and serotonin were demonstrated from homogenates of Caenorhabditis briggsae by two-dimensional thin layer chromatography and the identifications confirmed by gas liquid chromatography. In Vitro studies with 14C precursors of these biogenic amines demonstrate the ability of C. briggsae to synthesize each compound. The results provide required preliminary data for studying the neurophysiology of aging utilizing the nematode as a model.

The Influence of Tylenchus Agricola and Tylenchorhynchus Claytoni On Corn Roots Under Gnotobiotic Conditions

In studies carried out under controlled conditions, changes in the size and shape of nuclei were observed in corn roots parasitized by Tylenchorhynchus claytoni and Tylenchus agricola. Nuclei become spheroid in areas 1-3 mm behind the meristem of parasitized roots, whereas the same areas of non-parasitized roots had ellipsoidal nuclei. No differences were observed in nuclei in the meristematic zone. Since the nuclei of cortical cells were affected, and these cells apparently did not serve as feeding sites for the nematodes, it is probable that the stimulus which provoked the host response migrated from cell to cell.

The Histochemical Demonstration of Cytochrome Oxidase in Fresh-Frozen Sections of Nematodes

Histochemical procedures for the demonstration of cytochrome oxidase in fresh-frozen sections prepared from nematodes are described.

Studies On a Growth Supplement for Caenorhabditis Briggsae From Freeze-Dried Bacteria

Freeze-dried bacteria isolated from Panagrellus redivivus, contained a growth supplement that initially supported rapid growth and reproduction of Caenorhabditis briggsae. However, after four serial subcultures, the nematodes became sluggish and eventually died. Evidence is given that C. briggsae utilizes the bacterial cell as a food source, thereby showing that the bacterium-nematode relation is not one of mutualism.

Development of Panagrellus redivivus (Nematoda: Rhabditidae) in chemically defined media

Abstract Larvae of Panagrellus redivivus (L.) grew slowly and did not mature in the unsupplemented, chemically defined media 199, NCTC 109, and EM I. The addition of linoleic acid, linolenic acid, ethyl arachidonate, and RNA from yeast promoted growth in all media, but maturation occurred only in EM I. Limited reproduction occurred only when both fatty acids and RNA were added to EM I.

The influence of benzo(a)pyrene on the growth of wheat and corn

Abstract Corn seeds responded to soaking in aqueous solutions of benzo(a)pyrene with increased root growth. Growth stimulation decreased from 14% to 0 with increasing concentrations (0.0005–0.02 ppm), and with increasing soaking times (6 and 12 hr). Shoot growth and dry weights of shoots were not affected. Wheat did not respond as distinctly as corn to similar treatments. A decrease in the growth of shoots and roots with increasing BaP concentrations was not statistically significant.

Phenylalanine deaminase in plant parasitic nematodes.

Conversion of phenylalanine-1-C14 to phenylpyruvic acid-1-C14 was demonstrated with homogenates of Tylenchus agricola and Pratylenchus penetrans, giving the first evidence of a deamination system in plant parasitic nematodes. A commercially prepared paper strip, designed to test for the presence of phenylalanine deaminase in bacteria, was also utilized and found to be useful as a rapid method for identification of this enzyme in nematode homogenates.

Preparation of fresh frozen sections of free-living and plant parasitic nematodes with a cold microtome.

A technique is described for the preparation of fresh frozen sections for histochemical studies. This technique fulfills most requirements for histochemical work, and the quality of the sections is satisfactory.