Table 9

 

Effects of hormones and their precursors on the growth of Tetrahymena.

 

Values are related to control as one, concentrations in moles.

 

(Csaba, G., Németh, G., Effect of hormones and their precursors on protozoa – the selective responsiveness of Tetrahymena, Comp. Biochem. Physiol. 65B, 387-390, 1980)

 

 

Signal

10-5

10-6

10-7

10-8

10-9

10-10

10-11

10-12

Tryptophane

2.09*

1.75*

1.69*

1.55*

1.36*

1.09

1.03

1.02

Tryptamine

0.20*

0.37*

0.52*

0.88&

1.08

1.15+

1.08

0.86+

5hydroxytryptophane

0.18*

0.19*

0.49*

0.82*

0.79*

1.13

1.03

0.87+

Serotonin

0.23*

0.34*

0.69*

1.10

1.34*

1.25*

1.02

0.72+

 

 

 

 

 

 

 

 

 

Tyrosine

1.91*

1.75*

1.63*

1.59*

1.54*

1.44*

1.20*

1.09

Monoiodoty-rosine

1.09

1.36*

1.45*

1.54*

1.45*

1.35*

1.20*

1.10+

Diiodotyrosine

0.99

1.25*

1.37*

1.64*

1.63*

1.54*

1.47*

1.21*

Triiodothyronine

0.74*

0.88+

0.98

1.33*

1.29*

1.00

0.81*

0.68*

Thyroxine

0.30*

0.48*

0.67*

0.97

1.12*

1.03

0.98

0.85&

 

Significance to control: *=p<0.01; &=p<0.02; +=p<0.05

 

 

Conclusions:

 

  1. Members of serotonin and thyroxine series influence the growth of Tetrahymena.
  2. In the serotonin series serotonin itself is the most effective, while in the thyroxin series diiodothyrosine. Serotonin is ubiquitous in the living world (and is present also in Tetrahymena), while thyroxine appears at a higher level of phylogeny in the animal kingdom.
  3. This suggests that receptors of Tetrahymena easier recognizes hormones (precursors) which are at a lower level of phylogeny.
  4. The toxicity of thyroxin series was dependent on the number of iodine atoms present in the molecule.
  5. The basic amino acids exerted a concentration-dependent effect on Tetrahymena.