For over a century, Haeckel's Gastraea theory remained a dominant theory to explain the origin of multicellular animals. According to this theory, the animal ancestor was a blastula-like colony of uniform cells that gradually evolved cell differentiation. Today, however, genes that typically control metazoan development, cell differentiation, cell-to-cell adhesion, and cell-to-matrix adhesion are found in various unicellular relatives of the Metazoa, which suggests the origin of the genetic programs of cell differentiation and adhesion in the root of the Opisthokonta. Multicellular stages occurring in the complex life cycles of opisthokont protists (mesomycetozoeans and choanoflagellates) never resemble a blastula. Here, we discuss a more realistic scenario of transition to multicellularity through integration of pre-existing transient cell types into the body of an early metazoon, which possessed a complex life cycle with a differentiated sedentary filter-feeding trophic stage and a non-feeding blastula-like larva, the synzoospore. Choanoflagellates are considered as forms with secondarily simplified life cycles.

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[1] The behavior of the critical frequency foF 2 of the ionospheric F2 layer is considered for the period 1990-2010. Various available databanks of ionospheric vertical sounding data are described and compared. The analysis is performed in terms of comparison of the foF 2 data for the period 1958-1980 to the data for 1990-2010. Two moments of the day (14:00 LT and the after-sunset moment) and two seasons (winter and summer) are considered for 12 stations for which the necessary data were available. The scatter of the foF 2 values (in terms of the standard deviation, SD) relative to the dependence on the solar activity index F 10.7 is considered. It is demonstrated that the values of SD for the period 1998-2010 are much higher than for the period . This increase in the SD includes two factors: real increase in the foF 2 scatter and systematic decrease (negative trend) in foF 2 . This systematic decrease makes it possible to provide an independent evaluation of the trend in foF 2 : À0.03 MHz per year. Analysis of foF 2 behavior for each of all 12 stations is performed. The obtained linear trends are negative for all stations, but the trend magnitude varies from one station to another. The trends for two moments of time are found of the same order of magnitude: À0.024 and À0.054 MHz per year for the summer and winter seasons, respectively. Some conclusions on the behavior of the hmF 2 trends for the same period are presented. Possible causes of the changes in the trends in the F2 layer parameters are discussed.

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The median values of critical frequencies observed at ionospheric stations Slough, Juliusruh, and Rome are analyzed in detail. Long term trends in foF2 for the period 1985-2010 were found using the method previously described numerous times by the authors. The dependence of the trend value k on local time and month of the year was studied. For all three stations, a similar seasonal and diurnal behavior of k is obtained. The maximum values of the negative trends in foF2 fall on the noontime period of the day (1000-1600 LT). In the seasonal behavior, two maximums of the absolute value of k (in the end of winter-beginning of spring and middle of fall) are observed. The absolute values of the trends are small in the summer months. The conclusion regarding the seasonal behavior of k coincides with the conclusion of the authors in an earlier publication: negative trends in foF2 are better pronounced in winter than in summer. The possible conclu sions on the character of trends in the thermospheric parameters, which follow from the obtained conclusions on variations in the foF2 trends, are discussed.

Fifty-six nuclear protein coding genes from Taxonomically Broad EST Database and other databases were selected for phylogenomic-based examination of alternative phylogenetic hypotheses concerning intergroup relationship between multicellular animals (Metazoa) and other representatives of Opisthokonta. The results of this work support sister group relationship between Metazoa and Choanoflagellata. Both of these groups form the taxon Holozoa along with the monophyletic Ichthyosporea or Mesomycetozoea (a group that includes Amoebidium parasiticum, Sphaeroforma arctica, and Capsaspora owczarzaki). These phylogenetic hypotheses receive high statistical support both when utilizing whole alignment and when only 5000 randomly selected alignment positions are used. The presented results suggest subdivision of Fungi into Eumycota and lower fungi, Chytridiomycota. The latter form a monophyletic group that comprises Chytridiales+Spizellomycetales+Blastocladiales (Batrachochytrium, Spizellomyces, Allomyces, Blastocladiella), contrary to the earlier reports based on the analysis of 18S rRNA and a limited set of protein coding genes. The phylogenetic distribution of genes coding for a ubiquitin-fused ribosomal protein S30 implies at least three independent cases of gene fusion: in the ancestors of Holozoa, in heterotrophic Heterokonta (Oomycetes and Blastocystis) and in the ancestors of Cryptophyta and Glaucophyta. Ubiquitin-like sequences fused with ribosomal protein S30 outside of Holozoa are not FUBI orthologs. Two independent events of FUBI replacement by the ubiquitin sequence were detected in the lineage of C. owczarzaki and in the monophyletic group of nematode worms Tylenchomorpha+Cephalobidae. Bursaphelenchus xylophilus (Aphelenchoidoidea) retains a state typical of the rest of the Metazoa. The data emphasize the fact that the reliability of phylogenetic reconstructions depends on the number of analyzed genes to a lesser extent than on our ability to recognize reconstruction artifacts.