Partial Small Subunit Ribosomal Gene Research Articles

Prevalence and Genetic Diversity of a Microsporidian Parasite in the Black Imported Fire Ant and Its Social Parasitic Ant (Formicidae: Myrmicinae: Solenopsis) in Buenos Aires Province, Argentina.

Microsporidia are natural pathogens of arthropods and have been used as biological control against insect pests. In the United States, efforts to control the invasive Red Imported Fire Ant, Solenopsis invicta, and Black Imported Fire Ant, Solenopsis richteri, have included the use of the microsporidium, Kneallhazia solenopsae. However, there is limited information about the genetic differences among the microsporidian variants found in S. invicta and in S. richteri. In this study, we assessed the prevalence and genetic diversity of K. solenopsae in native populations of S. richteri in Argentina (South America). Additionally, we examined the social parasitic ant, Solenopsis daguerrei, which is found in some S. richteri nests, for the presence of this microsporidium. The survey of 219 S. richteri nests revealed K. solenopsae infections in all five sites analyzed, with 28 colonies (12.8%) positive for the microsporidium. Among the 180 S. daguerrei individuals collected, seven ants (3.9%) from three sites tested positive for K. solenopsae. Phylogenetic analyses of the microsporidian variants present in S. richteri and S. daguerrei based on partial small subunit ribosomal gene sequences (SSU rRNA) showed that both ant species shared the same variant, which is different from the ones found in S. invicta. Further studies are needed to determine the pathogenicity of genetically different K. solenopsae variants among Solenopsis species.

Biology of a new xenoma-forming gonadotropic microsporidium in the invasive blotchfin dragonet Callionymus filamentosus.

A gonadotropic microsporidian parasite, Obruspora papernae gen. et sp. nov. (Microsporidia: Enterocytozoonidae), is described from Callionymus filamentosus (Teleostei: Callionymidae) in the Mediterranean Sea. The host, a Red Sea invasive species which entered the Mediterranean through the Suez Canal, was first collected in the Levant Basin in 1953, whereas its parasite went unobserved until 2008. Analysis of partial small subunit ribosomal gene sequences (SSU rDNA) placed the new species within the Nucleospora, Desmozoon, and Paranucleospora clade, and as it differs from each of them, it is assigned to a new genus. The development of the parasite is described, and the biological mechanisms underlying this parasite-host system are analyzed. Prevalence of infection approached 80% in female samples throughout most of the year. Males showed no signs of infection, but parasite rDNA was detected in male internal organs. The parasite-induced xenomas progressively occupied and eventually replaced much of the ovary, in some cases producing effective castration. Despite high levels of parasite infection, current trawl fishery statistics indicate that the abundance of Mediterranean populations of the host remains high. The parasite impact on the host population dynamics is unclear. Possible effects of the new microsporidian parasite on the reproductive effort of C. filamentosus and the potential role of another parasite, the ectoparasitic copepod Lernanthropus callionymicola, as an additional host in the life cycle of O. papernae, require further investigation.

Do Galeate-Ascospore Members of the Cephaloascaceae, Endomycetaceae and Ophiostomataceae Share a Common Phylogeny?

Using partial small subunit ribosomal gene sequences we show that yeast-like genera that produce galeate (hat-shaped) ascospores and similar-spored members of the Ophiostomatales do not form a monophyletic group. Based on distance and parsimony methods Cephaloascus fragrans and Endomyces decipiens failed to form a monophyletic grouping with species of Ceratocystis sensu stricto and Ophiostoma. Instead these yeast species clustered with Saccharomyces cerevisiae, Kluyveromyces lactis, and Torulaspora delbrueckii in >9% of both the distance and parsimony majority-rule consensus trees generated using the statistical method of bootstrapping. Therefore galeate ascospores appear to be an example of convergent evolution in fungi and by itself this trait should not be considered as an indicator of evolutionary relatedness.

Do Galeate-Ascospore Members of the Cephaloascaceae, Endomycetaceae and Ophiostomataceae Share a Common Phylogeny?

Using partial small subunit ribosomal gene sequences we show that yeast-like genera that produce galeate (hat-shaped) ascospores and similar-spored members of the Ophiostomatales do not form a monophyletic group. Based on distance and parsimony methods Cephaloascusfragrans and Endomyces decipiens failed to form a monophyletic grouping with species of Ceratocystis sensu stricto and Ophiostoma. Instead these yeast species clustered with Saccharomyces cerevisiae, Kluyveromyces lactis, and Torulaspora delbrueckii in >99% of both the distance and parsimony majority-rule consensus trees generated using the statistical method of bootstrapping. Therefore galeate ascospores appear to be an example of convergent evolution in fungi and by itself this trait should not be considered as an indicator of evolutionary relatedness.