6. WALTERS, D.A., SMITH, B.L., BELCHER, A.M., PALOCZI, G.T.,
STUCKY, G.D., MORSE, D.E. & HANSMA, P.K. 1997. Biophys. J., 72:
1425–1433.
7. BELCHER, A.M., WU, X.H., CHRISTENSEN, R.J., HANSMA, P.K.,
STUCKY, G.D. & MORSE, D.E. 1996. Nature, 381: 56–58.
8. FALINI, G., ALBECK, S., WEINER, S., ADDADI, L. 1996. Science,
271: 67–69.
9. SAMATA, T., HAYASHI, N., KONO, M., HASEGAWA, K.,
HORITA, C. & AKERA, S. 1999. FEBS Lett., 462: 225–229.
10. MIYAMOTO, H., MIYASHITA, T., OKUSHIMA, M., NAKANO, S.,
MORITA, T. & MATSUSHIRO, A. 1996. Proc. Natl Acad. Sci. USA,
93: 9657–9660.
11. HEWETT-EMMETT, D. & TASHIAN, R.E. 1996. Mol. Phylogenet.
Evol., 5: 50–77.
12. SLY, W.S., HEWETT-EMMETT, D., WHYTE, M.P., YU, Y.L. &
TASHIAN, R.E. 1983. Proc. Natl. Acad. Sci. USA, 80: 2752–2756.
13. TASHIAN, R.E. 1989. BioEssays, 10: 186–192.
14. COLEMAN, J.R. 1991. Plant Cell Environ., 14: 861–867.
15. WEINER, S. 1983. Biochemistry, 22: 4139–4145.
16. CARIOLOU, M.A. & MORSE, D.E. 1988. J. Comp. Physiol. B, 157:
717–729.
17. FREEMAN, J.A. & WILBUR, K.M. 1948. Biol. Bull., 94: 55–59.
18. KONO, M., HAYASHI, N. & SAMATA, T. 2000. Biochem. Biophys. Res.
Commun., 269: 213–218.
19. HEDEGAARD, C. 1997. J. Moll. Stud., 63: 369–377.
20. HEDEGAARD, C. & WENK, H.R. 1998. J. Moll. Stud., 64: 133–136.
21. WISE, S.W. 1970. Eclogae Geol. Helv., 63: 775–797.
22. CHOMCZYNSKI, P. & SACCHI, N. 1987. Anal. Biochem., 162:
156–159.
RESEARCH NOTES
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Figure 4. Northern blot analysis of nacrein. The mantle poly(A)
+
RNA (1 g)
was separated by electrophoresis through 1% agarose gel containing
formaldehyde and transferred to nitrocellulose filter (Nitroplus 2000,
Micron Separation). The filter was hybridized at 65°C in 6 SSC, 5
Denhardt’s solution, 0.5% SDS, 4 mM EDTA, 100 g of salmon sperm DNA
per ml, and random-primed
32
P-radiolabelled probe prepared from T. mar-
moratus nacrein cDNA. After the filter was washed in 0.5 SSC at 60°C, posi-
tive signals were detected using BAS2500 Image Analyser (Fuji film).
Nucleotides 1–690 (lane 1) and 1191–1670 (lane 2) were used as probes.
J. Moll. Stud. (2003) 69: 89–92 © The Malacological Society of London 2003
The first freshwater molluscs from Antarctica
Allan C. Ashworth
1
and Richard C. Preece
2
1
Department of Geosciences, North Dakota State University, Fargo, ND 58105-5517, USA, and
2
Department of Zoology, University of Cambridge, Downing Street,
Cambridge CB2 3EJ, UK
Fossils of freshwater molluscs are reported for the first time
from Antarctica from a locality about 500 km NNE from the
South Pole. The fossils come from lightly-cemented siltstones
and marlstones interbedded with tillites of the Meyer Desert
Formation of the Sirius Group.
1
The formation is well exposed
in the Oliver Bluffs at 1760 m elevation above sea level on the
western flank of the upper valley of the Beardmore Glacier at
85°07' S, 166°35' E. The glacial and non-glacial deposits overlie
shallow marine deposits of the Cloudmaker Formation and are
thought to have been uplifted between 1300 and 1700 m since
deposition.
2
The depositional environment is inferred to have
been an active glacial margin at the head of a wide fjord more
than 100 km from the Ross Sea.
Two contrasting age estimates have been proposed for the
Meyer Desert Formation. The first is Pliocene, based on
reworked marine diatoms, but this is controversial because the
provenance of the sediments would be south of the site and
would require open marine conditions in the interior of
Antarctica.
2,3
The second is for a pre-Pliocene age based on the
interpretation that the marine diatoms were later introductions
to the Sirius deposits either by being windblown, although no
source has been identified,
4,5
or by being ejected from the deep
ocean floor by the impact of the Eltanin Asteroid.
6
The older
age interpretation is based on the hypothesis that land surfaces
in the Dry Valleys sector of the Transantarctic Mountains
(TAM) have been stable since the mid-Miocene,
7
although not
all landscapes in the TAM may be as stable.
8
Pollen evidence
from boreholes in Ross Sea sediments indicate that a tundra-like
vegetation persisted in the region until at least the early
Miocene
9
and possibly the Pliocene.
10
Palaeosol evidence from
the Meyer Desert Formation at the fossil site is more supportive
of a Pliocene than a Miocene age.
11
The cemented siltstones and marlstones were disaggregated
by first soaking in water, which softened the calcite cement, and
then wet sieved to remove the finer fraction. Fossils were then
picked from the sediment residues that were greater than 300 m
in size. They consist of a large number of shell fragments of
dextral basommatophoran gastropods and sphaeriid bivalves.
The gastropods are represented by 135 juvenile specimens,
up to 1.5 whorls, with maximum diameters ranging from Correspondence: A. C. Ashworth; e-mail: allan.ashworth@ndsu.nodak.edu
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