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241.
Fa-Guo Wang Ai-Hua Wang Cheng-Ke Bai Dong-Mei Jin Li-Yun Nie AJ Harris Le Che Juan-Juan Wang Shi-Yu Li Lei Xu Hui Shen Yu-Feng Gu Hui Shang Lei Duan Xian-Chun Zhang Hong-Feng Chen Yue-Hong Yan 《Plant Diversity》2022,44(2):141
Ferns and lycophytes have remarkably large genomes. However, little is known about how their genome size evolved in fern lineages. To explore the origins and evolution of chromosome numbers and genome size in ferns, we used flow cytometry to measure the genomes of 240 species (255 samples) of extant ferns and lycophytes comprising 27 families and 72 genera, of which 228 species (242 samples) represent new reports. We analyzed correlations among genome size, spore size, chromosomal features, phylogeny, and habitat type preference within a phylogenetic framework. We also applied ANOVA and multinomial logistic regression analysis to preference of habitat type and genome size. Using the phylogeny, we conducted ancestral character reconstruction for habitat types and tested whether genome size changes simultaneously with shifts in habitat preference. We found that 2C values had weak phylogenetic signal, whereas the base number of chromosomes (x) had a strong phylogenetic signal. Furthermore, our analyses revealed a positive correlation between genome size and chromosome traits, indicating that the base number of chromosomes (x), chromosome size, and polyploidization may be primary contributors to genome expansion in ferns and lycophytes. Genome sizes in different habitat types varied significantly and were significantly correlated with habitat types; specifically, multinomial logistic regression indicated that species with larger 2C values were more likely to be epiphytes. Terrestrial habitat is inferred to be ancestral for both extant ferns and lycophytes, whereas transitions to other habitat types occurred as the major clades emerged. Shifts in habitat types appear be followed by periods of genomic stability. Based on these results, we inferred that habitat type changes and multiple whole-genome duplications have contributed to the formation of large genomes of ferns and their allies during their evolutionary history. 相似文献
242.
Sophie La Salle Christopher C Oakes Oana R Neaga Déborah Bourc'his Timothy H Bestor Jacquetta M Trasler 《BMC developmental biology》2007,7(1):104
Background
Formation of haploid spermatozoa capable of fertilization requires proper programming of epigenetic information. Exactly how DNMT3L (DNA methyltransferase 3-Like), a postulated regulator of DNA methyltransferase activity, contributes to DNA methylation pattern acquisition during gametogenesis remains unclear. Here we report on the role of DNMT3L in male germ cell development. 相似文献243.
244.
Aromatase inhibition and experimental antitumor activity of FCE 24304, MDL 18962 and SH 489 总被引:2,自引:0,他引:2
E di Salle G Briatico D Giudici G Ornati T Zaccheo 《Journal of steroid biochemistry》1989,34(1-6):431-434
Human placental aromatase inhibitory properties of FCE 24304, MDL 18962, SH 489 and 4-hydroxyandrostenedione (4-OHA) were compared. The compounds caused time-dependent enzyme inactivation with t1/2 values of 13.9, 13.1, 45.3 and 2.1 min and Ki values of 26.0, 0.7, 2.0 and 29.0 nM respectively. The antitumor activity of FCE 24304, MDL 18962 and SH 489 was studied on the DMBA-induced mammary tumor in rats, at daily s.c. doses of 10 and 50 mg/kg. FCE 24304 induced 30 and 73% regressions of established tumors, associated with 86 and 93% decrease in total ovarian aromatase activity. SH 489 and MDL 18962 did not affect tumor growth. FCE 24304, like 4-OHA, was shown to inhibit LH hypersection in castrated rats. A gonadotropin suppressive effect could contribute to the antitumor activity of aromatase inhibitors in intact DMBA-induced tumor bearing rats. 相似文献
245.
Oxygen consumption (VO2) and carbon dioxide emission (VCO2) have been continuously recorded for 24 consecutive hours in 7 premature infants with a range of gestational age of 29-31 weeks at birth, and placed in incubators within a thermal neutral limit. These infants, submitted to continuous light, were fed every 3-4h through a gastric tube which was left in their stomachs throughout the whole experiment. Variance and spectral analyses performed on VCO2 values sampled on the recordings every 10 min showed ultradian variations, in the 40 min-6 h period range, which represent 20 and even 40% of the mean level. Moreover 5 out of the 7 premature infants show ultradian VCO2, VO2 and respiratory quotient rhythms related to feeding frequency. 相似文献
246.
瑞典国家财产委员会拥有骑士岛的所有权与管理权,并计划对该岛上所有的公共空间进行更新和开发,以提高其可达性与吸引力。该项目的核心是找到一种更新和修复岛屿的方法,从而在尊重历史价值的同时满足现代功能需求。对骑士岛南部的改造是岛上公共空间更新的第一部分。设计的关键条件是沿滨水区域创造可以供人步行与停坐的大面积空间,并在保持开放海港氛围的同时,对旧的道路铺装进行管理。设计者设计了一套灵活使用公共空间的综合解决方案,将开放空间与之前的码头一样,沿着水滨的形态进行布局。 相似文献
247.