Redescription of Chloromyxum ellipticum Li & Nie, 1973 (Myxosporea: Chloromyxidae) infecting the gall bladder of grass carp Ctenopharyngodon idellus Valenciennes, 1844, supplemented by morphological and molecular characteristics

The traditional taxonomy of the genus Chloromyxum Mingazzini, 1890 has been intensively challenged to be paraphyletic by recent ribosomal DNA (rDNA)-based phylogenetic analysis. Undersampling to get rich sequence data to infer more scientific phylogenetic relationships makes scientists conservatively assign all non-marine elasmobranch-infecting species as Chloromyxum sensu lato. Although complex ridge pattern on the spore surface observed by scanning electron microscopy was thought to be critical for the identification of Chloromyxum species, insufficient data also prevent this ultrastructural data to be a valid taxonomic feature for this genus. It is especial for Chloromyxum species to be reported in China. Molecular and ultrastructural characteristics are yet available for all 22 Chloromyxum species recorded in China. During the investigation of the diversity of coelozoic fish myxosporeans, Chloromyxum ellipticum Li & Nie, 1973 was found to highly infect the gall bladder of Ctenopharyngodon idellus Valenciennes, 1844 in Poyang Lake watershed of Jiangxi province, Eastern China. Here, we redescribed it by the currently recommended holistic approach of combining morphological, ultrastructural, and molecular characteristics. Mature spores were found floating free in the gall bladder, but no plasmodium observed. Spores are typical freshwater teleost-infecting Chloromyxum species, spherical or subspherical in lateral view, measuring 7.7 ± 0.08 μm (6.9-9.1) in length, 6.3 ± 0.09 μm (5.6-7.6) in width, and 5.8 ± 0.20 μm (5.2-6.3) in thickness. Four pyriform polar capsules, located at the anterior end of the spores, were equal in size, 3.3 ± 0.06 μm (2.2-4.1) long and 2.1 ± 0.03 μm (1.7-2.5) wide. Polar filaments coiled with four to five turns. Two equal spore valves are symmetrical, with 10-16 surface extrasutural ridges per valve, aligned along the longitudinal axis. The obtained partial 18S rDNA of C. ellipticum did not match any sequences available in GenBank. Phylogenetic analysis showed that C. ellipticum clustered firstly with Chloromyxum legeri with robust nodal support and grouped then with urinary system of freshwater teleost-infecting Chloromyxum clade, rather than other gall bladder of freshwater teleost-infecting clade.

Effect of a DNA vaccine harboring two copies of inhibin α (1-32) fragments on immune response, hormone concentrations and reproductive performance in rats

The objective was to investigate the effects of a novel DNA vaccine (pcISI) harboring two copies of inhibin α (1-32) fragments on immune response, hormone concentrations and reproductive performance in rats. Female Wistar rats (n=18 per group) were immunized (twice, 4 wk apart) with 10, 50, or 100 μg (T1, T2 and T3, respectively), of the pcISI plasmid. At 4 wk after the second immunization, plasma antibody titers were higher (P<0.05) in T3 than in either T1 or T2 (0.341±0.123, 0.236±0.068, and 0.251±0.077, respectively, mean±SD). Concurrrently, plasma concentrations of FSH and estradiol were highest (P<0.05) in T3, and were higher (P<0.05) in T1 and T2 than in control groups. For antibody-positive rats, there was a correlation (P<0.01) between antibody titer and FSH concentrations after two pcISI immunizations. The number of mature follicles in the T3 group (46.00±4.65) was higher (P<0.05) than in two control groups (29.25±3.72 and 27.92±3.48), and also higher (P<0.05) than in T1 and T2 (37.17±4.99 and 38.75±7.09). Antibody-positive rats had more mature ovarian follicles than negative rats (46.75±4.23 vs. 35.60±3.38, P<0.05). Moreover, litter size and number of placentas were increased (P<0.05) in the pcISI immunization groups, except for the T1 group, compared to the control groups. In conclusion, the pcISI DNA vaccine successfully induced a humoral immune response, improved reproductive hormone concentrations, stimulated follicular development, and increased number of placentas and litter size. Furthermore, 100 μg yielded the best immune response.

Efficient method for the calculation of mean extinction. II. Analyticity of the complex extinction efficiency of homogeneous spheroids and finite cylinders

The analyticity of the complex extinction efficiency is examined numerically in the size-parameter domain for homogeneous prolate and oblate spheroids and finite cylinders. The T-matrix code, which is the most efficient program available to date, is employed to calculate the individual particle-extinction efficiencies. Because of its computational limitations in the size-parameter range, a slightly modified Hilbert-transform algorithm is required to establish the analyticity numerically. The findings concerning analyticity that we reported for spheres (Astrophys. J. 399, 164-175, 1992) apply equally to these nonspherical particles.