1. health and fitness
2. disease

Reference
: Biol. Bull.,
153 : 219—227. (August,
AGGLUTININS
AND
PLANORBIDAE
LYSINS
1977)
IN
THE
: A SURVEY
MASSES,
AND
OF
ALBUMEN-GLAND
E. H. MICHELSON
Boston,
Substances
The
naturally
function
wilich agglutinate
in the heniolympii
of tilese
substances
FAMILY
Harvard
Massachusetts
EGG
EXTRACTS
AND LORIN
De/,art@nent of Tropical Public Health,
occur
MOLLUSCAN
HEMOLYMPH,
DUBOIS
Sc/tool of Public Health,
02115
or lyse human and other nianinialian
and
in extracts
from
various
has not been determined
erythrocytes
tissues
of molluscs.
; however,
Prokop
and
his associates
( 1968a, b) assume that they play a role in the defense mechanisms
of
and
gastropods
agglutinins
coined
tile
have been detected
species of Planorbidae
and Boyd,
term
“¿protectin―. Pemberton
in nearly
80 species
( 1974)
of gastropods,
noted
including
( Boyd, Brown, and Boyd, 1966 ; Brown, Aimodovar,
1968 ; Gilbertson
and Etges,
1967 ; Lee-Potter,
that
some
Bhatia,
1969 ; Pemberton,
1971;
Rudolph,1973).
Gilbertson
and Etges (1967) observed differences
in tile distribution
of henio
lymph hemaggiutinins
in species and strains of Bioniphalaria
and suggested
that
these substances
might be of value in differentiating
populations
of planorbids.
In view of the limited number of strains employed in their study, Giibertson
and
Etges' suggestion
requires further evaluation.
In fact, Pemberton
( 1974, p. 104)
reviewed
the literature
on variation
in terrestrial
gastropods
and concluded
that,
“¿Thereis, however,
no current
evidence
that agglutinin
content
and specificity
are of taxonomic
value at species level.―
In the present study, an effort was made to assess hotil interspecific
and inter
population
differences
in members
of tile Faniily Planorbidae
with respect to tile
presence and specificity of agglutinins
and lysins.
Extracts
of albumen glands and
egg-masses, as well as heniolymph, were tested
species and 4 genera of Pianorbidae.
MATERIALS
AND
froni 31 strains
representing
8
METHODS
Snails were reared and maintained
at 26 ± 1 °C in 1.5, 5, or 10 gallon aquaria
and fed romaine lettuce.
Tile water was aerated and filtered, and the snails were
exposed
to fluorescent
geographic
Preparation
Snail
light
for
12 hr daily.
Species
and
strains
of
snails,
their
origins and date of collection are listed in Table I.
of samples
hemolyniph
samples
were
obtained
by
nietilods
previously
described
( Michelson, 1966), and each sample representeda pool of hemolymphfrom
4—8snails ( 12—15mm in diameter).
To prepare egg extracts,
egg-masses
were removed from sheets of plastic film
which had been placed previously in stock aquaria.
No effort was made to separate
219
220
E. H. MICHELSON
the masses
with
in distilled
They
respect
water,
AND L. DUBOIS
to age or stage
blotted
were then placed
on paper
of developnient.
toweling,
in a tissue-grinder
The
masses
and weighed
were
rinsed
on a niicro-balance.
and 5.5 p.1 of 0.85%
saline added
for each
milligram of egg-mass.
The contents were honiogenized by hand for approxi
mately 5 nun, then centrifuged at 300 g for 5 nun, and the supernate used as the
test-sample.
To prepare
mature
albumen-gland
snails
grinder containing
was
centrifuged
Serial
made
per
x g for
dilutions
plates
in 0.85%
5 mm,
and
the
of test-material
(Cooke
Engineering
were
and
removed
from
homogenized
of tissue.
supernate
equal
volume
were
Co.,
phosphate-buffered
An
glands
, weighed,
in
5—10
a tissue
The honiogenate
used
as the
test-sample.
tests
doubling
well.
albumen
in diameter)
25 p.1of 0.85% saline per milligram
at 300
Heniagglutination
Microtiter®
extracts,
( 12—15 mm
saline
of a 2%
prepared
Alexandria,
(pH
7.2)
human
in U-bottom
Virginia).
at a final volume
red-blood
cell
wells
Dilutions
of
were
of 0.25 nil
suspension
was
then
added, the plates were covered, mixed on a mechanical
shaker, and allowed to sit
undisturbed
for one hr at 27° C or overnight
at 4° C. Control wells contained
only the diluent and red-blood
cells.
Unless otherwise
noted, a minimum
of three
different samples of each extract or hemolymph
was tested for every snail strain.
Test sanipies were used within one hour of preparation.
Studies,
comparing
agglutinins
and lysins contained
in the hemolymph
and
extracts
from
various
species
erythrocytes
from the same
ability in the receptor-cells,
from
either
members
Transfusion
Center
and
of the
contained
six
donors.
fifteen
0-type
ploying albumen-gland
Since henio!ymph
various
strains
variability
in the survey
from
of
Medical
obtained
glands from
single donor.
albumen-gland
and
S-3)
agglutinins
extracts
were
donor.
and limited
of the
Boston,
cells
of the
In
of the S-3 strain
of heinolymph
A preliminary
properties
Public
Center,
individuals
snails
a single
ten snails
Characteristics
Tropical
were
A1,
subjected
dialysis against TrisHCL
and
0
Health
or
from
the
This
used
strain
addition,
extracts
tested
strain.
of
of the
Consequently,
and
from
tested against
against
em
the degree of
of B. glabrata
was individually
were
of snails
to determine
of a particular
5-3
in tests
individual
A1-type
ten
A1-type
albumen
cells from
a
and tissue extracts
effort
was madle to characterize
contained
and
B,
Massachusetts.
subsequently
study, it was necessary
occur among
twenty-nine
from
utilized
To test for the possible van
of erythrocytes
were obtained
samples from twelve A1, four A2, three A1B,
The
snails of the CB strain of H. t-aribaeum
cells
Planorbidae,
donors.
samples
extracts froni seven strains of B. glabrata.
and tissue extracts
were pooled fnoni series
that might
hemolymph
of
Department
of the Children's
collection of erythnocytes
B, and
strains
series of three
forty different
egg
to heat
extracts
in hemolymph
from
inactivation
two
and
the physicochemical
tissue
strains
at 56° C and
of
extracts.
B.
glabrata
Thus,
( B-i
80° C for one hr;
buffer (pH 7.8) for 24 hr ; freezing at —¿20°
C for up
AGGLUTININS
AND LYSINS
IN PLANORBIDAE
221
TABLE I
Geographic
Species
origins of snail species and strains.
and strains
Origin
Biomphalaria glabrata
PR-i
PR-2
PR-2'
PR/B'
and date
of colonization
Puerto Rico, March 1954
Rio de Ia Plata, Puerto Rico, December 1957
Strain derived from single egg of a PR-2 snail, April 1959
Puerto Rican/Brazilian hybrid, March 1966
B-i
Catinga do Moura, Bahia, Brazil, June 1964
B-2
S-3
BH*
G-i
G-2
Salvador, Bahia, Brazil, June 1964
Lake Amaralina, Salvador, Brazil, July 1964
Belo Horizonte, Minas Gerias, Brazil, July 1964
Fazenda Graviel, Castro Alves, Bahia, Brazil, June 1974
Fazenda Graviel, Castro Alves, Bahia, Brazil, June 1974
G-3
Fazenda Graviel, Castro Alves, Bahia, Brazil, June 1974
M-1
RS-1
RS-2
RS-3
RS-8
Fazenda Morro
June 1974
Fazenda Riacho
Fazenda Riacho
Fazenda Riacho
Fazenda Riacho
St.L.
Cul de Sac Valley, Castries, St. Lucia, March 1969
Biomphakiria siraminea
Helisoma caribaeum
257
CH
DB
CB
B
Helisoma anceps
H' (pigmented and albino)
GB
Bulinus trunealus
E-1
E-2
do Afonso, Castro Alves, Bahia, Brazil,
Seco,
Seco,
Seco,
Seco,
Castro
Castro
Castro
Castro
Alves,
Alves,
Alves,
Alves,
Bahia,
Bahia,
Bahia,
Bahia,
Brazil,
Brazil,
Brazil,
Brazil,
June
June
June
June
1974
1974
1974
1974
Recife, Pernambuco, Brazil, May 1964
Capella Viaja, Puerto Rico, July 1959
San Juan, Puerto Rico, December 1970
Dos Bocas, Puerto Rico, July 1959
Castle Burke, St. Croix, Virgin Islands, August 1959
Bogota, Colombia, December 1970
(?) Strain originated from tropical fish aquarium, September
1954
Grand Bahama Island, June 1970
Egypt, June 1957
Liberian Institute (? Egypt), December 1963
Bulinus globosus
N-i
SA-15
Polypylis
S Albino
Nigeria, August 1972
South Africa, November 1965
hemisphaerula
Liu Ying,
so treated
were
extracts.
In addition,
albumen-gland
titered
extracts
0.1 M concentrations
A1 cells.
D-Galactosamine,
tose,
Taiwan,
June
1963
strain.
to one yr ; and repeated
employing
Tainen,
freezing and thawing
against
attempts
of various
strains
sugars in 0.85%
used in this series
a-D ( + ) Fucose,
a-D ( + ) Glucose,
and compared
a-Lactose,
times.
Extracts
to freshly
prepared
were made to block the agglutinating
from B-i and PR-2'
Sugars
for ten consecutive
A1 erythrocytes
activity
of
by incorporating
saline in hemagglutination
of tests
L( —¿
) Fucose,
D ( + ) Maltose,
of B. glabrata
tests
were as follows : N-Acetyi
D( + ) Galacto@e, $-D( —¿
) Fruc
D ( + ) Mannose,
L ( —¿
) Sorbose,
and Sucrose.
These sugars were used also in attempts to block the agglutination
of A1, B, and 0 erythrocytes by henlolymph from H. caribaeu,n (CB).
222
E. H. MICHELSON
AND L. DUBOIS
RESULTS
Survey
of strains
and species
Egg extracts.
Agglutinins for omietype or another of hunian erythrocytes were
detected in egg extracts from all seventeen strains of B. glabrata (Table II).
The
specificity of the reactions allowed a grouping of the strains into two categories:
those whose agglutinins reacted only against A-type cells (B-2, 5-3, BH, G-3,
St.L) , and those whose agglutinins reacted against both A- and B-type cells.
The type of reaction observed did not appear to be correlated with albinism.
Undiluted saniples from strains B-i and RS-2 agglutinated
0-type cells ; how
ever, for practical purposes, reactions initiated by undiluted samples may be ignored.
B. stralninea agglutinated only A-type cells.
Except
for extracts
froni the albino
varient
of H. anceps
( H' ) and from the E-2
strain of B. truncatus, in which undiluted samples agglutinated A-type cells and Aand B-type cells, respectively, agglutinins were not detected in the samples from
the other strains and species.
Albumen-gland
extracts.
Albunien-gland
extracts
were
prepared
from
all
geographic strains of B. glabrata except the G-1 strain.
Again, the reactions
permitted the grouping of snails into two categories (Table II I ) ; those which react
solely
with
A-type
cells
and
those
which
react
with
both
A- and
B-type
cells.
The PR-i strain showed slight reaction ( 1 : 4) in sonic samples, but not all, with
0-type cells. Concentrated
extracts of two strains gave evidence of lysis, but
extracts of others did not.
TABLE
Agglutinins
titerAzB0Biomphalaria
Species
II
detected in extracts of egg-masses from
Biomphalaria
strains
and species.
specificity and maximum
and strainsRBC
glabrataPR-i16320PR-264640PR-2'32640PR/B3280B-i256641B-232005-36400BH6400G-18160G-28160G-31600M-i16160RS-i16160RS-2
straminea6400
AGGLUTININS
AND LYSINS
TABLE
IN PLANORBIDAE
223
III
Agglutinins detected in extracts of albumen-glands front strains of Biomphalaria glabrata.
titerA@B0PR-i32324PR-21616nd*PR-2'16160PR/B3210B-i1640B-23200S-312800BH3200G-1ndridndG-216160G-31640M-i8320RS-18*8*RS-28160RS-3880RS-84ndSt.L
specificity and maximum
StrainsRBC
* nd
**
=
not
done.
Signifies
lysis
Extracts
in
undiluted
sample.
were prepared
no agglutinins
were
from three strains of H. caribaeuin
detected.
the use of albumen-gland
were negative.
The
size
(4—5 mm)
(257, CB, B), but
of Polypylis
All tests
Hemoiyinph.
Agglutinins
were detected
in the llemolyml)il
from
strains of B. glabrata
(5-3, BH, G-2, G-3, M-i, B-2), and all had titers
only six
less than
1 : 8
except
for
the
fronl
5-3
strain
strains
and a whole snail extract
precluded
was used.
hemoiymph
extracts
small
( 1 : 32)
S-3,
BH,
.
and
A-type
cells
B-2 ; whereas,
only
were
hemloynlph
agglutinated
from
by
strains
G-2,
G-3, M-i was reactive only against 0-type cells. The S-3 strain gave higher titers
at 4°C than at 27°C ; titers for other strains were higher at 27°C. It is of interest
that
no Puerto
Rican
strain
exhibited
agglutinins,
an observation
first
noted
by
Gilbertson and Etges (1967) . Lysins were found in the hemolymph of all strains
at either 4°or 27° C. Titers were generally low and rarely exceeded 1 : 2 in
tests
conducted
lysins
were
at 27° C and
nonspecific
and
Agglutinins
in high titer
Strain 257 of H. caribaeu;n
freshwater
Tile agglutinins,
of cells.
Lysins
titers
were
higller
with
all
the highest
however,
were observed
slightly
up to 1 : 16 in samples
cell
tested
at 4° C.
The
types.
were detected in six strains of Helisonia
(Table IV).
had titers up to 1 : 2048, the highest observed
in any
snail and possibly
thus far.
only
reacted
than
showed
hemolymph
no specificity
in all strains
those
titer for any snail studied
and reacted
with all types
except CH, B, and GB, and their
of Bioinphalaria.
In the genus Bulinus, only a South African strain of B. globosus gave evidence
of having
agglutinins.
The
titers
were
low and
never
exceeded
1 : 4.
224
E. H. MICHELSON
AND L. DUBOIS
TABLE IV
Agglutinins
in the hemolymph
of Helisonia
species and strains
titerAtB0Helisoina
(27° C).
specificity and maximum
Species and strainsRBC
caribaeum
257
CH
64
0
32
0
CB
256
256
32
B
512
256
32
DB
Helisoma anceps
H' (pigmented)
GB2048
Variability
of receptor
Some
when
frolii
variability
studies
reacted
16
8
0
cells
was
tested against
the pools used
16
16
0256
16
32
0256
H' (albino)
8
0
detected
in the response
cells obtained
in the survey
in a similar
(titer)
from a variety
of species
and
nianner,
of albumen-gland
of donors
(Table
strains
; however,
and the results
of both studies
extracts
V) and those
strains
in both
were comparable.
Those strains that were reactive to A cells alone remained so, as did those which
previously showed reactivity to both A- and B-type cells. No reactions were noted
with 0-type cells at titers greater than 1 : 1. Although the number of A1B and A2
donors
was
limited,
it was
all strains aggluinated
either
not agglutinated
Variability
of extracts
Although
individuals
observed
from
the
material
or reacted
only
and heinoly;nph
differences
in titer
were
at very
from individual
5-3 snails, all snails
strating
the presence
of agglutinins.
low titers,
from individual
observed
of CB strain of H. caribaeunr
on the other
mean
some
titer of 1 : 45.3.
samples
showing
were
negative.
aniong
Neither
heat inactivation
extracts
from
less than
1 : 4.
samples
from
snails
heniolyniph
of the albumen-glands
in both groups
responded
uniformly
in demon
In the Helisoma
saniples,
all tests showed
hand,
Heniolyniph
the presence
Preliin mary cliaracterization
appeared
Extracts
that
A2-type cells were
usually
and in extracts
titers of 1 : 256, which was as far as the material
albumen-glands,
available
A1B cells at titers from 1 : 8 to 1 : 64.
ranged
from
samples
from
of agglutinins
was diluted.
i : 8 to 1 : i28
5-3 snails were
(up to 1 : 64),
Titers
with
from the
a geometric
highly
variable,
whereas
others
of agglu tinins
at 56° C, dialysis,
to effect
the agglutinating
frozen for up to three months
nor repeated!
activity
of egg or
at —¿20°C showed
freezing
and thawing
albunien-gland
extracts.
no loss of reactivity
and
those frozen for one year only showed a loss of one titer.
A remarkable
difference
was noted
in the response
of Helisoina
hemolyniph
and
AGGLUTININS
Biomphalaria
albumen-gland
AND LYSINS
extract
IN PLANORBIDAE
to the presence
of various
225
sugars
in the test
system.
N-Acetyl-D-Galactosamine
effectively blocked agglutination
of A1-, B-,
and 0-type cells by Helisonta ilemolymph, whereas the other sugars had no effect.
On the other hand, N-Acetyl-D-Galactosaniine
had no effect on albumen-gland
extracts fronl strains of B. glabrata.
Albumen-gland
extracts were markedly
inhibited by a-D( + ) Fucose, a-L( —¿
) Fucose,
@-D(—¿
) Fructose, D( + ) Mannose,
L( —¿
) Sorbose, D( + ) Maltose, a-D ( + )Glucose, and Sucrose.
Partial inhibition
was
exerted
by D ( + ) Galactose
and a-Lactose.
DiscussIoN
Hemaggiutinins
and
present
in members
between
genera
hemolysins
of the
and
species
for
family
as well
human
Pianorbidae,
as between
erythrocytes
and
are
differences
populations
of a single
not
uniformly
were
observed
species.
Tile
ability to detect these substances
depends,
in part, on the selection of the saniple
to be tested, and variations were noted between hemolymph,
albumen-gland
extracts,
and extracts of egg-masses.
Thus, lysins were found pniniarily in hemolynipll
samples, rarely in albumen-gland extracts, and never in egg-mass extracts.
When
hemolynipil
served as the test sample, agglutinins
were detected in oniy 6 of the
17 B. glabrata populations ; however,
all populations
exhibited
agglutinins
in egg
and albumen-gland
extracts.
If one assumes that the albumen-gland
is the source
of agglutinins
and tilat these substances
are sequestered
into developing
eggs, as
well as disseminated
into the surrounding
hemolymph,
then this apparently
erratic
distribution
can be explained.
Failure to identify aggiutinins
in the hemolymph
of some populations
could be due to “¿spill-over―
concentrations
too low to detect
TABLE V
Agglulinins detected in extracts of albumen-glands from strains of Biomphalaria glabrata : summary
of trials employing RBC's from various donors.
titer'AiB0BH27.8
specificity and mean
StrainsRBC
(15)PR/B26.5
(10)―
(6)
8—640
(15)5-346.7
(11)
4—1285.0
(11)
16—2560
(13)PR-2'20.7
(15)G-28.7
(8)
0—1B-i19.0
* Geometric
Numbers
mean
in
brackets
(6)
2—80
(6)
0—20
and
(6)
8—i2812.7
(8)
4—3212.7
0—2B-247.8
**
0-10
4—320
(6)
4—320
(11)
(4)
8-2560
(8)
0—10
(6)
8—645.7
2—320
range.
equals
isumber
of
donors
tested.
(15)
(12)
(15)
0-1
226
E. H. MICHELSON
by the techniques
either
eniployed.
egg or albumen-gland
AND L. DUBOIS
On the other hand, agglutinins
extracts
of any of the species
were not found in
of Helisonia.
However,
agglutinins were detected in the heniolyniph of some strains and species and at very
high titers. This suggests that the origin of the agglutinins in Helisonta may be
different
from those of Bioinphalaria.
The lack of specificity
agglutinins
also distinguishes
theni from those of Biomphalaria.
the results of the inhibition
studies are considered,
differences
tinins
of the two genera
effectively
lana.
blocks
become patently
Helisoma
Likewise,
agglutinins,
of the hemolyniph
Moreover,
when
between the agglu
apparent ; N-Acetyl-D-Galactosaniine
but has no effect on those
those sugars which inhibited
Bioniphalaria
froni
Bio@npha
agglutinins
failed to
be effective against agglutinins
froni Helisoina.
Although
the limited number of species and strains of Bulinus
and Polyp ylis
tested prevents
a definitive evaluation
of these genera, it appears likely that both
groups
noted
lack agglutinins
some
reactivity
cells were employed,
of agglutinating
specific for human
with
extracts
Gilbertson
0-type
cells.
(1967)
lack
Our data appears
either A or 0-type
cells
reported
specificity
Brown
truncatus
when
of some Bulinus
nianimalian
and Etges
of Bioniphalaria
erythrocytes.
Bitlinus
and the heniolymph
nonhuman
lymph
from
(Rudolph,
reacted
to contradict
theirs
found in the henio
identically
against
in that reactions
Techniques
that
the
A,
B,
occurred
cells, but not with both and not at all with B-type
differed
observed
account
differences
for the differences
are
due
cells to
test eniployed,
observed.
to variability
of the
It niay be
erythrocytes
obtained
from different donors, but this does not agree with our
should be noted, that the present study indicated that Biomphalaria
experience.
hemolyniph
a poor
alone
source
paring
of agglutinins,
species
The
could
present
study
be segregated
those
could
variable,
and
not
suitable
for
that
lends
be made
support
to the
thesis
that
tool in characterizing
snail
of freshwater
snail species.
as a source
of agglutinins,
into two major
reacted
with
employing
cability for this
in the test-system
tion.
both
data
groups—those
A-
and
B-type
on heniolymph
which
cells.
lysins
lectins
populations
When
egg
populations
and
reacted
Further
(agglutinins
with
sor Augusto
Sherlock
Hoff,
We wish to also offer our thanks
Harvard-Wellconie
Mascarenhas
of the Nucleo
Project,
of the Federal
de Pesquisas
Salvador,
University
of the Ministry
and
A-type
cells
characterization
and agglutinins.
purpose of nonhuman erythrocytes
and
remains to be explored and niay contribute
( #275—0045).
Rodney
corn
and aiding
in the
or albumen-gland
of B. glabrata
The
appli
enzynie altered cells
to further differentia
This study was funded, in part. by a grant from The Edna McConnell
Foundation
It
is
and strains.
lysins)
niay be a valuable
taxonomic
discriniination
extracts
were
employed
and
extremely
and
with
since Gilbertson
our S-3 and B-2
in the type of hemoagglutination
but this alone does not necessarily
suggested
capable
i973).
the exclusion
of A. These differences
are not easily explained,
and Etges' snail strains froni Bahia, Brazil were derived from
colonies.
niodified
species appear
that the agglutinins
and
et al. (1968)
enzynie
to Drs. Kenneth
Brazil
; to Rector
Clark
Mott
Profes
of Bahia ; and to Dr. Italo
of Health
for their
aid and
AGGLUTININS
assistance
AND LYSINS
IN PLANORBIDAE
227
in the collection of snail samples from Bahia, Brazil.
indebted
to Dr. Sherwin
Massachusetts
Kevy
for numerous
of the Children's
Hospital
We are, likewise,
Medical
Center,
Boston,
samples of RBC's.
SUMMARY
1. Thirty-one
strains representing
family
Planorbidae
ysins.
Extracts
were
surveyed
prepared
eight species and four genera of the molluscan
for the presence
from albumen-glands
of heniagglutinins
and egg-masses,
lymph, were assayed
by a niicro-heniagglutination
erythrocytes
were used as receptors.
2. Hemagglutinins
and hemolysins
present
in all members
in part,
on the material
technique
in
for human erythrocytes
of the family
and detection
of these
and heniol
as we!! as hemo
which
human
were not uniformily
substances
depended,
tested.
3. Neither
heating to 56° C, dialysis,
storage at —¿20°C for up to a year,
nor repeated freezing and thawing appeared
to effect the agglutinating
activity of
egg or albumen-gland
extracts.
4. Inhibition of the agglutinating
activity of Helisoina hemolyniph could be
accomplished with N-Acetyl-D-Galactosamine,
but this sugar had no effect on the
activity of Bioniplialaria agglutinins.
5. There is evidence to suggest that the source and nature of agglutinins from
Helisonra and Bioniphalaria
species are different.
6. Lectins may be of some value in characterizing
aid in the taxonomic
discrimination
of species.
LITERATURE
snail populations
and as an
CITED
Boyn, W. C., R. BROWN, AND L. G. BOYD, 1966. Agglutinins
for human erythrocytes
iusks. J. linmunol., 96 : 301—303.
BROWN, R., L. R. ALMODOVAR, H. M. BHATIA, AND W. C. BOYD, 1968. Blood group
in mol
specific
agglutinins in invertebrates. J. Iminunol., 100: 214—216.
GILBERTSON, D. E., AND F. J. ETGES, 1967. Haemagglutinins
snails. Ann. Trop. Med. Parasitol.,
61 : 144-147.
LEE-POTTER, J. P., 1969. Haemagglutinins
in water snails.
MICHELSON,
E.
H.,
medically
PEMBERTON,
R.
1966.
Specificity
important
T.,
snails.
1971.
of
hemolymph
J. Parasitol.,
Haemagglutinins
in the haemolymph
Vox. Sang.,
antigens
of planorbid
16 : 500—502.
in taxonomic
discrimination
of
52 : 466—472.
from
some
British
non-marine
origin.
Ann.
Mollusca.
Vox
Sang., 21 : 509—521.
PEMBERTON,
R. T.,
1974.
Anti-A
and
anti-B
of gastropod
NeIL'
York
Acad.
Sci.,
Klasse
anti
234: 95—121.
PROKOP, 0.,
G. UHLENBRUCK, AND W.
KÔHLER, 1968a.
Protectine,
eine
neue
kör.perahnlicherVerbindungen. Dtsch. Gesundheitwes., 23 : 318—320.
PROKOP, 0.,
G. UHLENBRUCK,
stances
having
AND W.
anti-blood
K6HLER,
group
1968b.
specificity.
A
new
A discussion
source
of
antibody-like
on the specificity
sub
of Helix
agglutinins. Vox. Sang., 14 : 321—333.
RUDOLPH,
P. H.,
matophora.
1973.
The
Malacol.
occurrence
of hemagglutinins
Rev., 6 : 48—49.
in some
Basommatophora
and
Stylom