118 P. S. CHEN 
With the exception of hydroxyproline, taurine, asparagine and tryptophane, 
AUCLAIR AND DuBREUIL® identified all the amino acids referred to above in three 
other species of Lepidoptera (Phlegethontius quinquemaculatus, Malacosoma americana 
and Archips cerasivorana) but a-amino-n-butyric acid was found only in P. quin- 
quemaculatus. 
Diptera 
In connection with genetic and developmental problems, the free amino acids in larvae 
and adults of Drosophila melanogaster have been extensively studied by a number of 
investigators (HADORN AND MITCHELL®; AUCLAIR AND DUBREUIL®; CHEN AND 
HaADORN®?; BENZ!9; Fox?®?; KAPLAN, HOLDEN AND HOCHMAN!”). For larvae aged 72 
and 96 h CHEN AND HaAporn®® noted the presence of 22 free ninhydrin-reacting sub- 
stances, including four peptides (Table I). AUCLAIR AND DUBREUIL® found asparagine 
and hydroxyproline, but detected no /-alanine, histidine, and y-amino-n-butyric acid. 
In addition to the above amino acids, BENz!® reported the presence of taurine and 
ornithine. Taurine and methionine sulfoxide appear in larger quantities only in later 
developmental stages and in the adults (CHEN AND DreM?5). FAULHABER®™ identified 
tryptophane, but this amino acid apparently accumulates in larger quantities only in 
the v-mutant (GREEN**). The occurrence of y-amino-n-butyric acid in this insect is 
understandable, as this amino acid has been found in yeast extract (REED!*°). But 
the possibility that it is formed by decarboxylation of glutamate is not excluded. 
Very recently MitcHELL, CHEN AND Haporn! demonstrated the occurrence of 
tyrosine-O-phosphate in Drosophila larvae (see also paper by MITCHELL and SIMMONS 
in this conference). This compound has Rp values corresponding to peptides I plus 2 
described by CHEN AND Haporn®’. The last authors also observed a high concen- 
tration of tyrosine in the hydrolysates of these peptides. 
Sexual differences in the pattern of free ninhydrin-reacting components of this 
insect have been noted by several workers. KAPLAN, HOLDEN AND HocHMAN!”, by 
both chromatography and microbiological assays, showed that adult females contain 
almost twice as much methionine as males. Fox®? as well as Fox, MEAD AND Munyon™! 
reported the presence of a “sex peptide” in male adults, but not in females. Very 
recently, CHEN AND Drem** recorded a ninhydrin-positive substance which is specifically 
located in the accessory glands (paragonia) of the male flies and probably corresponds 
to the “sex peptide” described by Fox®’. Its quantity increases in the course of imaginal 
development, apparently due to the gradual increase in size of these glands. 
The mosquitoes are another group of dipterous insects the free amino acids of 
which have been studied in detail. In the body extract and hemolymph of Culex prprens 
CHEN*°, 31 identified the presence of methionine sulfoxide and two peptides in addi- 
tion to 19 other free ninhydrin-positive components (Table I). The same pattern was 
found for Culex fatigans (GEIGER’’). Most of these amino acids were also reported for 
Culex tarsalis, Culex stigmatosoma, Culex quinquefasciatus, Aedes varipalpus and Culiseta 
incidens (CLARK AND BALL*; 43; BALL AND CLARK"). The main difference is that both 
tryptophane and a-amino-n-butyric acid were noted in these insects, but not in C. 
pipiens and C. fatigans (see ref. 33). CLARK AND BALL* identified cysteic acid which, 
as noticed by these authors, was probably derived from cystine. The patterns of free 
amino acids for Culex salinarius, Aedes aegypti, Aedes sollicitans, Culiseta inornata and 
Anopheles quadrimaculatus are very similar to that found for C. pipiens, except for 
References p. 132/135 
