Male gametes originate from a small population of spermatogonial stem cells (SSCs). These cells are believed to divide infinitely and to support spermatogenesis throughout life in the male. Here, we developed a strategy for the establishment of SSC lines from embryonic stem (ES) cells. These cells are able to undergo meiosis, are able to generate haploid male gametes in vitro, and are functional, as shown by fertilization after intracytoplasmic injection into mouse oocytes. Resulting two-cell embryos were transferred into oviducts, and live mice were born. Six of seven animals developed to adult mice. This is a clear indication that male gametes derived in vitro from ES cells by this strategy are able to induce normal fertilization and development. Our approach provides an accessible in vitro model system for studies of mammalian gametogenesis, as well as for the development of new strategies for the generation of transgenic mice and treatment of infertility.
Members of the genera Aurantimonas and Fulvimarina have largely been described on the basis of 16S rRNA gene sequence analyses, biochemical tests and limited chemotaxonomic data. Examination of the polar lipid compositions of members of these two genera indicated that although the patterns were similar with regards the phospholipid and amino lipid compositions, there were clear differences in the presence or absence of the glycolipid sulfoquinovosyldiacylglycerol (SQDG). This glycolipid was absent in members of the species Aurantimonas coralicida and Fulvimarina pelagi but was present in Aurantimonas altamirensis, Aurantimonas ureilytica and Aurantimonas frigidaquae. These results are also consistent with the 16S rRNA sequence-based grouping. We therefore propose that the genus Aurantimonas be divided further to reflect this additional information. Thus, it is recommended that Aurantimonas altamirensis, Aurantimonas ureilytica and Aurantimonas frigidaquae are transferred to a new genus, Aureimonas gen. nov., as Aureimonas altamirensis gen. nov., comb. nov. (type strain S21BT = CECT 7138T = CIP 109525T = KCTC 22106T = LMG 23375T = DSM 21988T), Aureimonas ureilytica comb. nov. (type strain 5715S-12T = KACC 11607T = DSM 18598T = CIP 109815T) and Aureimonas frigidaquae comb. nov. (type strain CW5T = KCTC 12893T = JCM 14755T = DSM 21987T). The type species of the new genus is Aureimonas altamirensis. Additionally, emended descriptions of the genera Aurantimonas and Fulvimarina are provided.
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