Upper Palaeozoic mosses of the order Protosphagnales are studied for their leaf development and found to be quite different from modern mosses. In the latter, the small actively dividing cells occur at latest stages of leaf development in the proximal part of leaf, whereas in Protosphagnales cell divisions may continue in the subapical part of leaf. Also, zones of small cells occur in some genera in the median part of the leaf, indicating relatively independent development of different leaf parts. The narrow insertion of leaves, which consists almost entirely of the costa, makes easier late growth of the basal leaf portion, where expanded aurucules may form. The small cells in median part of leaf differentiate both acropetally and basipetally, but cells above this zone become dimorphous more often than below it. The pattern of cell dimorphism is correlated with shifts of cell rows during leaf development.
РезюмеДля верхнепалеозойских мхов порядка Protosphagnales изучены листья и их фрагменты, представляющие разные стадии их развития. Анализ порядка дифференциации клеток в разных частях листа показывает существенные отличия Protosphagnales от современных мхов. У последних мелкие активно делящиеся клетки обнаруживаются практически всегда только в основании листа, тогда как у палеозойских мхов порядка Protosphagnales деления могут долго продолжаться близ верхушки листа. Кроме того, зоны с мелкими недавно поделившимися клетками обнаруживаются в средней части листа, указывая на относительно независимое развитие отдельных его частей. Узкое прикрепление листа к стеблю, охватывающее практически только жилку, делает возможным позднее дополнительное развитие ушковидного основания. Мелкие клетки средней части листа дифференцируются как акропетально, так и базипетально, но выше этой зоны диморфизм клеток формируется более выраженно. Показана обусловленность клеточного диморфизма сдвигами клеточных рядов друг относительно друга.
The moss fossil records from the Paleozoic age to the Eocene epoch are reviewed and their putative relationships to extant moss groups discussed. The incomplete preservation and lack of key characters that could define the position of an ancient moss in modern classification remain the problem. Carboniferous records are still impossible to refer to any of the modern moss taxa. Numerous Permian protosphagnalean mosses possess traits that are absent in any extant group and they are therefore treated here as an extinct lineage, whose descendants, if any remain, cannot be recognized among contemporary taxa. Non-protosphagnalean Permian mosses were also fairly diverse, representing morphotypes comparable with Dicranidae and acrocarpous Bryidae, although unequivocal representatives of these subclasses are known only since Cretaceous and Jurassic. Even though Sphagnales is one of two oldest lineages separated from the main trunk of moss phylogenetic tree, it appears in fossil state regularly only since Late Cretaceous, ca. 70 million years ago (Ma), while earlier they were found twice as small leaf fragments from Lower Jurassic (ca. 200 Ma) and Late Ordovician (ca. 455 Ma). Pleurocarpous mosses appear in fossil state near the border between Jurassic and Cretaceous, although most Cretaceous mosses belong to acrocarps. Only in Eocene amber pleurocarps become more numerous than acrocarps. Some Eocene mosses can be assigned to extant families and sometimes genera, although the majority of Eocene pleurocarps are difficult to identify up to the family, as their morphology often allows placement of a particular specimen into several different families.
Protosphagnalean mosses had a unique ability to switch the development of leaf areolation between a pathway unique to Sphagnum and another one common to all other mosses. This developmental polyvariancy hinders attempts to classify these mosses, as characters previously considered to be of generic significance can be shown to co-occur in one individual leaf. New understanding of the ontogeny has allowed us to re-evaluate the systematic significance of such diagnostic characters in these Palaeozoic plants, showing that their similarity to Sphagnum is less substantial.
We demonstrated the possibility of enrichment of umbilical cord blood mononuclear fraction with early non-differentiated precursors under conditions of co-culturing with mesenchymal stromal cells from the human adipose tissue. It was established that umbilical cord blood mononuclear cells adhered to mesenchymal stromal cell feeder and then proliferate and differentiate into hemopoietic cells. In comparison with the initial umbilical cord blood mononuclear fraction, the cell population obtained after 7-day expansion contained 2-fold more CFU and 33.4 ± 9.5 and 24.2 ± 11.2% CD34(+) and CD133(+) cells, respectively, which corresponds to enrichment of precursor cell population by 148 ± 60. The proposed scheme of expansion of hemopoietic cells from umbilical cord blood is economically expedient and can widely used in biology and medicine.
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