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Abstract
This work aimed to study the differences in haemolymph
cellular (haemocytes) and chemical constituents (glucose, total lipids
and total proteins) of Biomphalaria alexandrina, Bulinus truncatus,
Lanistes carinatus, Limnaea natalensis and Physa acuta.
Light and scanning electron microscopic investigations were
carried out to study haemocytes and the effect of infection and
environmental contaminants on its different types and differential
count.
Three main haemocyte categories could be distinguished
namely: hyalinocytes, agranulocytes and granulocytes according to the
presence or absence of granules, the ability of the cytoplasm and
granules (if present) to stain as well as the nucleic/cytoplasmic ratio.
Several differences were observed in the morphology,
differential count, cell area, nuclear area and nucleic/cytoplasmic ratio
(N/C ratio) of the haemocytes in laboratory bred field and infected
snails.
Hyalinocytes have the highest N/C ratios in all snail categories.
The predominant type of haemocytes counted in field and infected
Biomphalaria alexandrina, Limnaea natalensis, field Bulinus truncatus
and laboratory bred Lanistes carinatus was hyalinocytes (38.4, 61.41,
38.5, 42.9, 31.43, 79.4% of the counted cells), while agranulocytes with
basophilic cytoplasm in infected Bulinus truncatus, field and infected
Lanistes carinatus and laboratory bred and field Physa acuta were the
predominant haemocyte type (68.21, 51.5, 24.9, 49.66 and 50.4% of the
counted cells).Phagocytic ability and pseudopodial formation are increased
significantly in infected snails. Pseudopodia were found in haemocytes
of infected Biomphalaria alexandrina, field and infected Lanistes
carinatus, field and infected Limnaea natalensis and in field Physa
acuta. Numerous long filopodia were detected in laboratory bred Physa
acuta.
Giant cells with many globules were observed only in infected
Bulinus truncatus; these cells have many granules.
Vacuoles in agranulocytes with basophilic cytoplasm of
infected Bulinus truncatus were more frequent than those in field ones.
In infected Biomphalaria alexandrina; laboratory bred, field and
infected Lanistes carinatus; one or more vacuoles might be present in
both agranulocytes with acidophilic or basophilic cytoplasm, while in
field Physa acuta; vacuoles might be present in agranulocytes with
basophilic cytoplasm only.
A significant difference recorded in the cell area of acidophilic
agranulocytes of both field and infected Biomphalaria alexandrina. The
cell area of basophilic granulocytes of field and infected Biomphalaria
alexandrina and Bulinus truncatus significantly increased.
Significant differences were found in cell area of hyalinocytes of
all haemocytes of Lanistes carinatus studied. Agranulated acidophilic
haemocytes of laboratory bred Lanistes carinatus were significantly
different from that of infected snails. Agranulated basophilic
haemocytes were significantly different in all Lanistes carinatus
studied. Acidophilic granulocytes haemocytes of field Lanistes
carinatus were significantly different from that of infected Lanistes
carinatus. Basophilic granulocytes were significantly different in all
Lanistes carinatus studied.By comparing cell area of each cell type in both field and
infected Limnaea natalensis and in both laboratory bred and field Physa
acuta the following data were obtained:
Hyalinocytes: were significantly different in field and infected
Limnaea natalensis and also in laboratory bred and field Physa acuta.
Agranulocytes with acidophilic cytoplasm: were insignificantly
different in all Limnaea natalensis and Physa acuta studied.
Agranulocytes with basophilic cytoplasm were significantly different in
field and infected Limnaea natalensis and also in laboratory bred and
field Physa acuta.
Granulocytes with acidophilic granules: were insignificantly
different in all Limnaea natalensis and Physa acuta studied.
Granulocytes with basophilic granules: were significantly
different in laboratory bred and field Physa acuta, while insignificant
differences were found in field and infected Limnaea natalensis.
There was an increase in the cell number of hyalinocytes of
infected Biomphalaria alexandrina and infected Limnaea natalensis.
Acidophilic agranulocytes increased in both infected Biomphalaria
alexandrina and Lanistes carinatus and in field Physa acuta. Basophilic
agranulocytes increased in number in all snails under study except
infected Biomphalaria alexandrina. Acidophilic granulocytes increased
in number in field and infected Lanistes carinatus, while basophilic
granulocytes increased in number in all snails under study except
infected Biomphalaria alexandrina and field Physa acuta.
The increase in cell area of hyalnocytes occured in all snails
under study except Biomphalaria alexandrina.
Acidophilic and basophilic agranulocytes increased in cell area
in field and infected Lanistes carinatus.Acidophilic granulocytes increased in cell area in all snails
under study except infected Limnaea natalensis and field Physa acuta,
while basophilic granulocytes increased in cell area in all snails under
study except field Physa acuta.
Classification of haemocytes studied by SEM depends on shape,
size and surface structure. There were many differences in haemocytes
shapes under SEM.
Quantitative determination of glucose, total lipids and total
proteins contents in the haemolymph and also the qualitative
determination of general proteins reflect stress and pathological
response.
There was a significant difference between the mean
haemolymph glucose concentration of infected Lanistes carinatus and
field Bulinus truncatus only.
The mean concentration of total lipids was significantly
different in; laboratory bred Lanistes carinatus and both field Lanistes
carinatus and Bulinus truncatus, infected Lanistes carinatus and both
field Biomphalaria alexandrina and Physa acuta
While the mean concentration of total protein was significantly
different between; field and infected Lanistes carinatus, laboratory bred
Lanistes carinatus and field Bulinus truncatus, field Lanistes carinatus
and Bulinus truncatus, infected Lanistes carinatus and field
Biomphalaria alexandrina, infected Lanistes carinatus and field
Bulinus truncatus, infected Lanistes carinatus and Physa acuta, field
Biomphalaria alexandrina and Bulinus truncatus, field Physa acuta and
both Biomphalaria alexandrina and Bulinus truncatus.
Electrophoretic study of the haemolymph general proteins of
field and infected Bulinus truncatus, Lanistes carinatus, laboratory bred
Lanistes carinatus, field Limnaea natalensis, and field and laboratory
bred Biomphalaria alexandrina and Physa acuta shows that there are
clear different in patterns of all snails under study except field and
laboratory bred Physa acuta.
All these changes among snails under study indicate the effect
of environmental contaminants on field snails and the influence of
trematode infection on infected ones.
So the changes in the biochemical and cellular composition of the
snail’s haemolymph could be used as monitoring or indicator of the
biotic (parasitic) or abiotic (chemical, environmental) contamination.