The family Carlemanniaceae in East Asia and tropical Asia, comprising two genera, Carlemannia and Silvianthus, are mainly distributed along the southern foot of the Himalaya Mountains and the western and southern interface of the Yunnan Plateau. The main reproductive process for Carlemannia tetragona was verified as self-pollination by the pollination experiments in this work. Germination rates for seeds of both C. tetragona and Silvianthus bracteatus could reach 100% when the seeds were collected after two months, while the rates decreased to 25% when collection took place in the previous year. It was found that the seed had no dormancy stages, and their seed banks were of the Transient Soil type. In field observations, the dehiscence status for fruits showed that their seeds could not be ejected effectively by capsules for dispersal. After analyzing the temperature and rainfall data from the years 1971 to 2000, it was shown that annual rainfall, the lowest mean monthly temperature in a year, and the extreme lowest temperature in a month had a great effect on the distribution range of Carlemanniaceae, while the mean annual temperature had a lesser effect. The narrow distribution range of Carlemanniaceae was affected by multiple factors, such as the short pollen dispersal distance and the Transient Soil Seed Bank. The population sizes of Carlemanniaceae were also easily affected by the level of rainfall, not by any single variable.
Through constructing a specialized cDNA library based on small RNAs isolated from partial purified nuclei of Schizosaccharomyces pombe, two novel noncoding RNAs, termed Sp15-70 and Sp18-61, have been identified. Bioinformatics analysis reveals that both the novel RNAs possess a typical secondary structure of box HACA snoRNA and antisense elements to rRNAs. According to the relationship between the structure and function of box HACA snoRNA, Sp15-70 was predicted to direct pseudouridylation in 25S rRNA at U2401 and U2298; Sp18-61 was predicted to direct pseudouridylation in 18S rRNA at U208 and 25S rRNA at U2341. The four predicted pseudouridylation sites were all verified experimentally by the CMC-primer extension analysis. Both Sp15-70 and Sp18-61 were encoded by single copies which were located in the intergenic regions between the CDS of two protein-coding genes on chromosome Ⅰ and Ⅲ of S. pombe, respectively. Putative TATA-like elements can be found upstream from the 5′ end of these snoRNA genes, suggesting that they could be transcribed from their own promoters. Comparison of the two snoRNAs and their functional homologues in diverse organisms reveals that extensive recombinations among different snoRNAs have occurred during the evolution from their primitive progenitors. 相似文献
