. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 372 MARIE M. JENKINS TABLE I Effect of goitrogens on oxygen consumption of planarians within 27\ hours after initial exposure p\. O2 Treatments Days 0 i 2 Water 140 147 142 Thiourea, 5 X 10~3 M 121 122 135 Thiourea, X 10"3 M 120 117 127 Phenylthiourea, 5 X 10~4 M 143 116 127 Phenylthiourea, X 10~4 M 138 105 119 Thiouracil, 5 X 10~3 M 141 143 136 Thiouracil, X lO"3 M 132 140 133 rise which was significantly above normal by the sixth clay, the maximum being reached on the eighth day. The effect wa
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 372 MARIE M. JENKINS TABLE I Effect of goitrogens on oxygen consumption of planarians within 27\ hours after initial exposure p\. O2 Treatments Days 0 i 2 Water 140 147 142 Thiourea, 5 X 10~3 M 121 122 135 Thiourea, X 10"3 M 120 117 127 Phenylthiourea, 5 X 10~4 M 143 116 127 Phenylthiourea, X 10~4 M 138 105 119 Thiouracil, 5 X 10~3 M 141 143 136 Thiouracil, X lO"3 M 132 140 133 rise which was significantly above normal by the sixth clay, the maximum being reached on the eighth day. The effect was similar in the lower concentration, but less pronounced. A return to water slightly diminished the rise in oxygen uptake, but a return to normal levels was not established within four days. The effect of the higher concentrations of goitrogens on the respiratory rate of the planarians as compared with the usual gradual decline exhibited by the water controls is illustrated in Figure 1. DISCUSSION The mechanism of goitrogenic action has not been completely elucidated, but current evidence favors the view that these compounds, by virtue of their reducing activity, produce their effect in the vertebrate thyroid by interfering with the conversion of iodide to iodine, presumably by inhibiting a peroxidase (Astwood, 1955), although the presence of the latter in the thyroid has not been demonstrated. It is possible that the action of the goitrogens in depressing oxygen consumption in planarians is mediated through a similar mechanism. Although the fall in WAT CD CONTROL PHENYLTHIOUREA. RETURNED TO WATER ,40 RETURNED TO WATER RETURNED TO WATER I- DAYS EXPOSED TO GOITROGENS FIGURE 1. Effect of higher concentrations of goitrogens on oxygen consumption of Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original M
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
