galactose are known constituents
of
lichens after chemical hydrolysis. Doubtful
amounts
of
lactose could only be detected
in
O.
convolutum.
GalaCtosamine
is
a
known constituent
of
many polysaccharides, yet was not detected in any of the three
specimens analysed. Ribose was included as standiud but contrary to expectations it
was not detected. This can only be explained in-that the concentration may have been
too low to be detected.
No
attempt was made to investigate the occurrence
of
extraceliular lichen substances.
These substances are mostly weak phenolic compounds and their physiological role
has been the subject
of
considerable speculation. Huneck (1973) and Mosbach (1973)
respectively discussed the nature and biosynthesis
of
such extracellular substances
while reference to their economic uses and possible ecological role was made by
Richardson (1975) and Vartia (1973).
TABLE I: Crude protein content of three species
of
Namib Desert Lichens.
Species
Omphalodium convolutum
Parmelia hottentotta
Teloschistes capensis
% crude protein
14,42
16,24
13,45
TABLE
2:
Quantitative amino acid analysis of three species
of
r-/amib Desert Lichens expressed as
~mol
per
10
mg
of
dried material.
Amino Acid
Omphalodium Parmelia Teloschistes
convolutum
hottentotta
capensis
Alanine
....................
1,50
3,15
2,20
Arginine
....................
0,25 '
0,90
0,55
Aspartic Acid
................
1,50 3,20
2,35
Cystine
....................
0,0
0,0
0,0
Diaminopimelic Acid
..........
0,0 0,0
0,0
Glutamic Acid
...............
1,50 4,60 3,75
Glycine
....................
1,50
2,95.
2,10
Histidine
....................
0,08 0,0
0,0
Hydroxyproline
..............
0,0· 0,0
0,0
Isoleucine
... '
................
0,30 0,85
0,50
Leucine
....................
0,75
2,20
1,25
Lysine
.....................
0,35 1,66
1,10
Methionine
..................
0,25 0,50
0,40
,Ornithine
...................
0,0
0,0
0,0
! Phenylalanine
................
1,60,
1,45
0,0
Proline
.....................
1,40
2,35
1,55
. .
Serine
.....................
1,25 2,40
1,80
Threonine
..................
1,30
2,15
1,45
I
yypt?phan
.................
. Tyrosme
...................
0,0
0,90
0,0
Valine
.....................
0,55
1,25
0,95
Ammonia
...................
2,60 I
4,30 3,60
. - = Not assayed
i
/
i
41
Reproduced by Sabinet Gateway under licence granted by the Publisher (dated 2012)
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