A new species of Eimeria (Apicomplexa, Eimeriidae) from the weedy sea dragon Phyllopteryx taeniolatus (Osteichthyes: Syngnathidae)

A new species of intestinal coccidian is described from the weedy or common sea dragon Phyllopteryx taeniolatus housed at the New England Aquarium in Boston and at the Shedd Aquarium in Chicago, USA. Live oocysts of Eimeria phyllopterycis sp. n. are spherical, 30.9 (28.0-34.4) microm, with a thin, single-layered wall. Both a micropyle and oocyst residuum are absent and a large polar granule is sometimes present. Sporocysts are ellipsoidal and elongate, 24.3 x 10.4 (23.4-25.6 x 9.2-11.2) microm, with Stieda and substieda bodies; shape index (length/width) 2.33 (2.14-2.70). A sporocyst residuum is present, consisting of numerous granules of various sizes. Sporozoites each possess 3 refractile bodies. Preliminary evidence suggests that the coccidian may affect the health of sea dragons; however, it could not be determined whether this parasite caused significant morbidity or mortality.

Effect of acetylated and deacetylated 2-aminofluorene adducts on in vitro DNA synthesis

We have constructed primed phi X174 DNA templates containing either acetylated or deacetylated aminofluorene adducts at the C-8 position of guanine. T4 DNA polymerase terminates synthesis one nucleotide before the acetylated adducts but incorporates an additional nucleotide opposite the deacetylated guanylaminofluorene. These observations can be explained by the known preferred conformations of the acetylated and deacetylated guanosinylaminofluorene nucleosides--the former favoring the syn conformation (so that in DNA the guanine is displaced from the helix by the fluorene ring) and the latter preferring the anti conformation (which allows normal base pairing of the guanine with cytosine). A similar differentiation between the two adducts was found with Escherichia coli DNA polymerase I. In contrast, avian myeloblastosis virus (AMV) reverse transcriptase, which terminated with a nucleotide inserted opposite the acetylated adducts, was less able to do so at the deacetylated adducts. The nucleoside incorporated by AMV reverse transcriptase opposite the acetylated adduct was exclusively cytidine, which suggests regular base pairing with the reacted guanosine nucleoside in the anti conformation; however, synthesis was completely blocked and unable to continue beyond this point. The differences between the termination patterns of the prokaryotic enzymes and AMV reverse transcriptase indicates that specific properties of a replicating polymerase can influence the conformation of a reacted nucleoside in the DNA, thus altering its recognition and possibly its mutagenic activity.

Interactions between DNA polymerase and aminofluorene adducts that affect the recognition and possibly the mutagenicity of the lesions

Adducts of 2-aminofluorene on the C-8 position of guanine block DNA synthesis and lead to mutation. N-acetylated adducts adopt the syn conformation such that in DNA the guanine is displaced from the helix by the fluorene ring while unacetylated adducts prefer the anti conformation allowing normal base pairing of the guanine with cytosine. In vitro synthesis by both E. coli DNA polymerase I and T4 DNA polymerase terminates predominantly one nucleotide before acetylated adducts but has an increased tendency to terminate opposite the unacetylated adducts apparently reflecting the preferred conformations of the two species of reacted nucleoside. In complete contrast AMV reverse transcriptase correctly inserts cytosine opposite the acetylated adducts but prefers to terminate one nucleotide before the unacetylated adducts. We interpret these results as indicating that the specific properties of a replicating polymerase can influence the conformation of a reacted nucleoside thus altering its recognition and possibly its mutagenic activity.