Amino acid interrelationships in cysteine toxicity in Neurospora crassa

L-Cysteine became toxic to the growth of Neurospora crassa (wild, Em 5297a), in the range 1.0-2.0 mM in the culture medium. The specificity of cysteine toxicity was shown by absence of toxicity with other sulphydryl compounds (β -mercaptoethanol, thioglycollic acid, reduced glutathione) and with cysteine metabolites, L-cysteic acid and taurine, under similar conditions. The toxicity of L-cysteine was completely overcome by supplements of S-methyl-L-cysteine and to a marked extent by DL-methionine and DL-homocysteine; partial counteraction of cysteine toxicity was observed with L-serine, DL-tryptophan, DL-alanine, DL-valine, DL-homoserine or DL-threonine. DL-Methionine and S-methyl-L-cysteine counteracted the inhibitory effect of L-cysteine in two N. crassa mutants, namely, methionineless mutant 38706 and cystathionineless mutant 9666

Effect of copper on growth and catalase levels of Corcyra cephalonica St. in zinc toxicity

The work of Smith and Larson, van Reen and van Reen and Pearson has revealed that the dietary ingestion of toxic levels of zinc results in a marked inhibition of growth and deranged iron metabolism in rats. The latter effect was reflected in anæmia and decreased levels of liver catalase and cytochrome oxidase. Liver extract partially counteracted the growth inhibition, while minute supplements of copper to the toxic diet reversed the anæmic condition and restored the levels of the iron enzymes. From such results it has been concluded that the inhibition of growth is unrelated to the enzymic changes observed, and that the two phenomena are distinct and different effects of zinc toxicity in the animal organism

<span style="font-size:14.0pt;line-height: 115%;font-family:"Times New Roman";mso-fareast-font-family:"Times New Roman"; color:black;mso-ansi-language:EN-IN;mso-fareast-language:EN-IN;mso-bidi-language: HI" lang="EN-IN">Transport properties of Mg²⁺ ion doped Cu(HCOO)₂ organic molecular single crystals</span>

473-475<span style="font-size:14.0pt;line-height: 115%;font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" color:black;mso-ansi-language:en-in;mso-fareast-language:en-in;mso-bidi-language:="" hi"="" lang="EN-IN">Thermally stimulated discharge current (TSDC) of Mg, Cu(HCOO)2  organic molecular single crystals has been studied in the low temperature (77-300K) region. The pure (x = 0) single crystals show only one TSDC peak at 183 K with the maximum current of 5.5 nA, which is attributed to 'detrapping of charge carriers'. But three peaks were observed in impurity doped (x =1 and 2 mole %) Cu(HCOO)2 single crystals. The maximum current in these crystals was in the order of few microamps. The two new peaks have been assigned to ‘Trap-limited band transport model’ and ‘Maxwell-Wagner effect’. Relaxation parameters and activation energies of these crystals have been calculated.</span