Retarded development of fetal renal alkaline phosphatase in mice given 2,4,5-trichlorophenoxyacetic acid

Histologic study of the fetal offspring of maternal mice given 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) suggested that the previously reported fetal "cystic kidneys" were due to a retardation in fetal renal development and downgrowth of the renal papilla into the pelvis. To determine a possible retardation in renal alkaline phosphatase or functional development, maternal mice received by gavage 60-120 mg/kg, 2,4,5-T on days 6-14 of pregnancy. At necropsy on day 17, the fetal kidneys were excised and fixed 24 hr in cold 65% ethanol. Paraffin sections stained by Gomori's method revealed alkaline phosphatase mainly in tubules in the inner renal cortex. Fetal kidneys showing diminished or no alkaline phosphatase were designated subnormal. There was a statistically significant greater incidence of subnormal fetal kidneys in the 2,4,5-T-treated mice than in the untreated controls. In three experiments, some mice were also sacrificed on day 18, and the incidence of subnormal fetal kidneys was significantly lower than on day 17. This retardation in renal alkaline phosphatase development indicates a retardation in renal functional development and indirectly supports the view that 2,4,5-T also retards the morphological development of the fetal kidney and is not a renal teratogen in mice. It also illustrates that selected histochemical studies may be helpful in a teratologic investigation.

Studies on the mechanism of renal transport depression caused by pretreatment with 2,4,5-trichlorophenoxyacetate

Relatively low toxicity in the adult has been reported for the organic acid herbicides 2,4-dichlorophenoxyacetate and 2,4,5-trichlorophenoxyacetate (2,4,5-T). Although small doses of these herbicides are excreted rapidly, acute impairment of renal excretion has been reported when large doses of herbicide were administered. After the administration of 2,4,5-T in vitro analysis of renal proximal tubular function showed a decrease in the activity of the organic acid transport system which handles these herbicides. In addition, the pretreated animals show an impairment in the organic base transport system. To determine the nature of 2,4,5-T renal depression, renal cortical slices from herbicide-pretreated animals were studied. Alterations in the initial influx of organic ions, steady-state accumulation, and efflux were measured. Furthermore, a specific and reversible depression of tissue oxygen consumption was demonstrated. These changes do not appear to be the result of alterations in the gross morphology, electrolyte composition, or cell water content of the renal cortex.

Distribution and cytogenetic test of 2,4-D and 2,4,5-T phenoxyacetic acids in mouse blood tissues

The phenoxyacetic acids 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), extensively used as herbicides, were tested for cytogenetic effects by means of induced micronuclei in erythrocytes of mouse bone marrow. Because of the hig experimental resolution power this is a particularly suitable test system for the detection of weak chromosome breaking activity in mammals. The cytogenetic tests were supplemented with chemical analyses of the concentration the the test substances reaching the target cells...

Teratogenic and toxicological examination of 2,4,5-trichlorphenoxyacetic acid in developing chick embryos

Practical grade 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), dissolved in dimethylsulfoxide (DMSO), was injected into the air space of fertilized chicken eggs prior to incubation. Doses of 2,4,5-T administered were 12.5, 25, 50, 75, 100, and 125 mg/kg to determine herbicide toxicity on the first day of incubation. A similar group was studied on day 5 of incubation with doses of 2,4,5-T at 50, 75, 100 and 250 mg/kg. LD50 was estimated to be 62 mg/kg on day zero and 68 mg/kg on day 5. Additionally, embryos were exposed to 2,4,5-T at 50 mg/kg on day zero of gestation and sacrificed after 48 h of incubation. Serial sections were examined for teratological and developmental anomalies. None were found.

Effects of selected herbicides and plant hormones on Prototheca wickerhamii

Prototheca wickerhamii was treated in vitro with 11 different herbicides and plant hormones. Growth was inhibited by indolyl-3-acetic acid, indolyl-3-butyric acid and indolyl-3-propionic acid at 400 mug per ml. Coconut milk was stimulatory.

Sequential histopathologic, hematologic, and blood chemistry changes induced in mice by a technical and a purified preparation of 2,4,5-trichlorophenoxyacetic acid

Maternal mice were given 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) on days 6 through 14 of pregnancy in a tetratologic study at the National Center for Toxicological Research. Sick or moribund mice sacrificed after 4-8 doses of 120 mg/kg 2,4,5-T often showed severe myocardial lesions, hypocellularity of the bone marrow, and depletion of lymphocytes in the thymus, spleen, or lymph nodes. Healthy mice sacrificed on day 17, 11 days after treatment began, showed few or no severe lesions. To determine if lesions earlier in gestation contributed significantly to an increase in fetal abnormalities in the healthy 17-day survivors, dihybrid croos F2 pregnant and nonpregnant mice received by gavage 0, 60, or 120 mg/kg 2,4,5-T on days 6 through 14 of pregnancy. One group received a technical preparation containing 97.9 +/- 0.4% 2,4,5-T; another received a purified preparation containing 99 +/- 0.3% 2,4,5-T. Mice were sacrificed when they became moribund and at 6, 24, and 30 hr, as well as at 4, 6, 8, and 11 days after beginning treatment. Almost all mice given 60 mg/kg and many given 120 mg/kg 2,4,5-T appeared normal at sacrifice either early or late in pregnancy and showed little or no pathologic changes. Mice that became ill or moribund often showed severe lesions; few survived 11 days. Severe myocardial lesions were seen in 26 of 70 moribund mice fiven the technical 2,4,5-T and 24 of 33 given the purified preparation of 2,4,5-T. The moribund mice, particularly those given the purified compound, also showed a high incidence of lesions in other organs and marked hematological and blood chemistry changes. These findings indicate that the lesions are primarily due to 2,4,5-T rather than to impurities in the technical preparation; also impaired maternal health is not the primary cause of the increase in fetal abnormalities.

Distribution and effects of 2,4,5-trichlorophenoxyacetic acid in cells of Bacillus megaterium

Cell death in a resting population of an asporogenous Bacillus megaterium was accelerated by ambient concentrations of 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) equal to or greater than 10 mug/ml or 5 mug/mg of cells (dry weight), but only after prolonged exposure. Conversely, populations of growing cells were not markedly influenced even at 100 mug/ml. Effects on cell respiration were not manifest until the ambient concentration reached 1,000 mug of 2,4,5-T/ml, or 500 mug/mg. Cells of B. megaterium did, however, accumulate 2,4,5-T passively to a level approximately twofold above the ambient concentration. Most of the accumulated compound was easily washed from the cells, but, of the firmly bound herbicide, about 0.5 mug/mg of cells (dry weight), nearly 60% by weight, was localized in the protoplast membrane. The foregoing results, obtained with a purified preparation of 2,4,5-T were also elicited by 2,4,5-T analytical standards. The extracted contaminants did not produce the results alone nor did they influence the results when present in combination with 2,4,5-T.

The effect of the herbicide 2,4,5 trichlorophenoxy acetic acid (245T) on the growth and metabolism of Tetrahymena pyriformis

The herbicide 2,4,5 trichlorophenoxy acetic acid (245T) at concentrations from 0.5 to 0.9 mM, was found to inhibit respiration and then growth in exponentially growing cultures of Tetrahymena pyriformis. Cell division was stopped for periods up to 60 minutes after which the cells recovered and division resumed. Recovery of oxygen utilization and cell division occurred in the presence of 245T. 245T was shown to inhibit mitochondrial oxygen utilization. Mitochondria from cells that had recovered from 245T treatment lost their sensitivity to low concentrations of the herbicide and sedimented deeper in a sucrose gradient than mitochondria from control cells.

Alterations in cholesterol and fatty acid biosynthesis in rat liver homogenates by aryloxy acids

2,4-Dichlorophenoxyacetic acid and 2,4,5-trichlorophenoxyacetic acid inhibited the incorporation of [2-(14)C]mevalonate into cholesterol and non-saponifiable lipids. Both compounds inhibited the conversion of [1-(14)C]isopentenyl pyrophosphate into cholesterol and the synthesis of cholesterol and fatty acids from [2-(14)C]acetate. There was no inhibition of the conversion of [1-(14)C]mevalonate into CO(2). At low concentrations (0.5mm) of the compounds there was a stimulation of acetate incorporation into fatty acids.

Mutation test of 2,4,5-trichlorophenoxyacetic acid on Drosophila melanogaster

Oregon-R Drosophila melanogaster males were fed medium containing 0, 250, and 1000 pm of 2,4,5-T to test the mutagenic effects of this herbicide. Both levels of the herbicide increased the number of sex-linked recessive lethals. This increase in mutation rate was found to be significant only at the 1000 ppm concentration.

Regulation of Mitosis

The conclusion of earlier studies that the pronounced cytological effects of 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) formulations are actually due to 2,4,5-T is unwarranted. Inhibition of mitosis and the development of cytological abnormalities are caused by a contaminant, 2,3,7,8-tetrachlorodibenzo-p-dioxin. The appearance and behaviour of dividing endosperm cells of the African blood lily (Haemanthus katherinae Baker) subjected to a 10-4 M solution of highly purified 2,4,5-T, observed in vitro by phase-contrast microscopy for a 2-h treatment period, did not differ significantly from controls. Subjecting these cells to 0.2 or 1.0 µg/l. dioxin, to 0.2 µg/l. dioxin plus 10-4 M 2,4,5-T (highly purified sample), or to 10-4 M 2,4,5-T containing dioxin as a contaminant caused a dramatic inhibition of mitosis. These preparations also induced formation of dicentric bridges, chromatin fusion with formation of multinuclei or a single large nucleus. Impairment of the functioning of the mitotic apparatus was evident; chromosomes ‘floated free’ in the cytoplasm. Both quantitative and qualitative data substantiate these conclusions.

In view of the extreme toxicity of dioxins to man, of their demonstrated teratogenic effects in some animals under experimental conditions, of their effectiveness in producing cytological effects in dividing cells formerly ascribed to 2,4,5-T of their presence as contaminants in 2,4,5-T, pentachlorophenol, and other polychlorophenols, and of the potential for widespread contamination of the environment with dioxins, investigation of all facets of this class of compounds should be given high priority. It is quite possible that contamination of the environment with dioxins from sources of polychlorophenols is far greater than that contributed by 2,4,5-T. Amplification of dioxin levels in food chains is, of course, of particular concern.

Dielectrophoresis of cells

Dielectrophoresis, the motion produced by the action of nonuniform electric field upon a neutral object, is shown to be a simple and useful technique for the study of cellular organisms. In the present study of yeast (Saccharomyces cerevisiae) using a simple pin-pin electrode system of platinum and high-frequency alternating fields, one observes that the collectability of cells at the electrode tip, i.e. at the region of highest field strength, depends upon physical parameters such as field strength, field uniformity, frequency, cell concentration, suspension conductivity, and time of collection. The yield of cells collected is also observed to depend upon biological factors such as colony age, thermal treatment of the cells, and chemical poisons, but not upon irradiation with ultraviolet light. Several interesting side effect phenomena coincident with nonuniform electric field conditions were observed, including stirring (related to "jet" effects at localized electrode sites), discontinuous repulsions, and cellular rotation which was found to be frequency dependent.