The study has unequivocally demonstrated that siliceous sponges
Spirastrella cuspidifera
and
Prostylyssa foetida
from the same microecological niche exhibit a high degree of species specificity, while accumulating a host of heavy metal ions (Ni, Cr, Cd, Sn, Ti, Mo, Zr). S.
cuspidifera
accumulated, in addition,
60
Co and
63
Ni, showing discrimination against other radionuclides,
137
Cs and
131
I, present in the ambient waters receiving controlled low level waste discharges from a B. W. R. nuclear power station. P.
foetida
, on the other hand, accumulated only
131
I and showed discrimination against other radionuclides including
60
Co, although the stable iodine concentrations in both the sponges were the same. The specific activity of
60
Co (in becquerels per gram of
59
Co) in S.
cuspidifera
and
131
I (in becquerels per gram of
127
I) in P.
foetida
were at least two orders of magnitude greater than in the ambient sea water. That of
63
Ni (in becquerels per gram of
62
Ni) in
S. cuspidifera
, on the other hand, was lower by two orders of magnitude than in either abiotic matrices from the same environment. Thus, not only did both the species show bioaccumulation of a specific element, but also preferential uptake of isotopes of the same element, though they were equally available for intake. Such differential uptake of isotopes can possibly be explained in terms of two quite different mechanisms operating, each applicable in a particular case. One is that the xenobiotic isotope enters the environment in a physicochemical form or as a complex different from that of its natural counterpart. If equilibration with the latter is slow, so that the organism acquires the xenobiotic in an unfamiliar chemical context, it may treat it as a chemically distinct entity so that its concentration factor differs from that of stable isotope, thus changing the specific activity. Alternatively, if the xenobiotic is present in the same chemical form as the stable isotope, the only way in which specific activities can be modified is by fractionation on the basis of mass of isotope. In view of the remarkable concentration factors observed for stable and radioactive isotopes of the same element and the specific activities reached, it is desirable that species of sponges, especially from the coastal and estuarine environments, be monitored to detect levels of pollution due to anthropogenic substances.
BETA GLUCURONIDASE-RICH CYTOPLASMIC PARTICLES IN ANDROGEN-STIMULATED MOUSE KIDNEY