Development. The decade of the developing brain

Our understanding of neural development has advanced dramatically over the past decade. Significant insights have now been obtained into seven fundamental developmental processes: first, induction of the neural plate; second, regionalization of the neural tube along the dorsoventral and anteroposterior axes; third, generation of neurons and glia from multipotential precursors; fourth, apoptotic cell death; fifth, migration of neurons; sixth, guidance of axons to their targets; and seventh, formation of synapses.     

Stem cells and cell therapy: On the eve of scientific discovery

Cell therapies and stem cells (SCs) have recently become a popular topic. This field of research is cluttered with numerous publications of questionable reliability. Not all methods applied in practice are founded on evidence from research. Although the literature is abundant, there is a gap between the supposed healing properties of SCs associated with their ability to migrate to and engraft on injured tissue, as well as a lack of clear morphological proof. Accordingly, there is a gap between advertising and a part of the professional literature; whereas the former speaks about the rejuvenation of tissues, the latter attributes sometimes questionable therapeutic effects to paracrine or immunomodulating mechanisms and the secretion of cytokines and growth factors. However, SCs are undifferentiated cells; therefore, specific and efficient paracrine function compared to other, more differentiated cells can hardly be expected. In conclusion, it should be noted that the main problem with SCs and cell therapy is commercial influence. The experiences of some foreign countries where attempts have been made to stop the use of unproven treatments, including some stem-cell therapies, should most likely be studied.     

On the eve of animal radiation: phylogeny, ecology and evolution of the Ediacara biota

Ediacara fossils document an important evolutionary episode just before the Cambrian explosion and hold critical information about the early evolution of macroscopic and complex multicellular life. They also represent an enduring controversy in paleontology. How are the Ediacara fossils related to living animals? How did they live? Do they share any evolutionary patterns with other life forms? Recent developments indicate that Ediacara fossils epitomize a phylogenetically diverse biosphere, probably including animals, protists, algae, fungi and others. Their simple ecology is dominated by epibenthic osmotrophs, deposit feeders and grazers, but few if any predators. Their evolution started with an early morphospace expansion followed by taxonomic diversification within confined morphospace, and concluded by extinction of many taxa at the Ediacaran-Cambrian boundary.     

Population size at the time of mitochondrial eve

This study takes a fresh but simple approach to a controversial subject. A computer simulation is used to investigate the relation between the age of our most recent mitochondrial DNA ancestor (often called “mitochondrial Eve”) and the number of her contemporaries. The simulation follows a female population through 16,000 generations, allowing it to fluctuate at random, although guided by a growth rate of .02% per generation. At each generation an account is kept of the number of viable female lineages, that is, the number of original females who retain at least one female descendent. Simple statistical methods are applied to the results of thousands of such runs, and a correspondence is suggested — in tabular, functional, and graphical form — between the various ages commonly proposed for “mitochondrial Eve” and the likely size of the population at these times. In addition, several specific assertions are made about maximum and minimum populations in the past hundreds of thousands of years. This simulation does not presume to solve the age problem, nor to remove it from the ultimate authority of genetic research. Rather it provides a different tool with which to investigate the matter.     

The Drosophila eve Insulator Homie Promotes eve Expression and Protects the Adjacent Gene from Repression by Polycomb Spreading

Insulators can block the action of enhancers on promoters and the spreading of repressive chromatin, as well as facilitating specific enhancer-promoter interactions. However, recent studies have called into question whether the activities ascribed to insulators in model transgene assays actually reflect their functions in the genome. The Drosophila even skipped (eve) gene is a Polycomb (Pc) domain with a Pc-group response element (PRE) at one end, flanked by an insulator, an arrangement also seen in other genes. Here, we show that this insulator has three major functions. It blocks the spreading of the eve Pc domain, preventing repression of the adjacent gene, TER94. It prevents activation of TER94 by eve regulatory DNA. It also facilitates normal eve expression. When Homie is deleted in the context of a large transgene that mimics both eve and TER94 regulation, TER94 is repressed. This repression depends on the eve PRE. Ubiquitous TER94 expression is “replaced” by expression in an eve pattern when Homie is deleted, and this effect is reversed when the PRE is also removed. Repression of TER94 is attributable to spreading of the eve Pc domain into the TER94 locus, accompanied by an increase in histone H3 trimethylation at lysine 27. Other PREs can functionally replace the eve PRE, and other insulators can block PRE-dependent repression in this context. The full activity of the eve promoter is also dependent on Homie, and other insulators can promote normal eve enhancer-promoter communication. Our data suggest that this is not due to preventing promoter competition, but is likely the result of the insulator organizing a chromosomal conformation favorable to normal enhancer-promoter interactions. Thus, insulator activities in a native context include enhancer blocking and enhancer-promoter facilitation, as well as preventing the spread of repressive chromatin.     

Paradise lost: Mitochondrial eve refuted

Being based solely on neontological data, all «unique parent» evolutionary hypotheses, of which «Mitochondrial Eve» is one, fall into the category ofscala naturae. Mathematical treatment of neontological data bases, using cladistic approaches does not confer the status of scientific hypotheses onto such scenarios. Apart from these fundamental problems, such hypotheses are flawed on a number of other bases, including the fact that there is a proportion of parental contribution to mitochondrial lineages, despite widely publicised statements that mithocondrial DNA in mammals is «strictly» maternally inherited. Other weaknesses of «unique mother» hypotheses on that their proponents endeavour to describe the evolution of diploid organisms on the basis of variability in extant haploid organelles, the evolution of which is delinked from that of the diploid organism. A further difficulty is that it is not possible to reconstruct interspecific relationships on the basis of intraspecific variability. There is a general ignorance among proponents of «unique mother» hypotheses regarding the distribution of biological variability on the surface of the globe, a fact which renders the molecular clock inaccurate, and which upsets the simplistic proposal that molecular diversity equates with time. «Unique mother» scenarios are also invalidated by the presence of shared chromosome and other polymorphisms in african great apes and humans at similar percentages in the different lineages, a fact which indicates that these evolving populations did not experience «bottlenecks». These and other difficulties effectively refute the «Mitochondrial Eve» hypothesis, which in any case much resembles creationism of a special kind, in which the offspring of a breeding pair are visualised as belonging to a species different from its parents. Such extreme examples of the punctuational mode of evolution are highly likely to be incorrect.     

Stem cells and cancer: two faces of eve

Recent evidence suggests that a subset of cancer cells within some tumors, the so-called cancer stem cells, may drive the growth and metastasis of these tumors. Understanding the pathways that regulate proliferation, self-renewal, survival, and differentiation of malignant and normal stem cells may shed light on mechanisms that lead to cancer and suggest better modes of treatment.     

Stem cells and cell therapy: on the eve of scientific approach

Cell therapy and the stem cells (SC) have become a popular topic during last time. The theme is cluttered with numerous publications of questionable reliability. Not all methods applied in praxis are founded on evidence-based research. In the abundant literature, there is a gap between the supposed SC's healing properties associated with their capability to migrate to and engraft in injured tissue, and lack of clear morphological evidence thereof. Accordingly, there is a gap between advertizing and the better part of professional literature: the former speaks about rejuvenation of tissues, and the latter explains sometimes questionable therapeutic effects by paracrine or immunomodulating mechanisms, secretion of cytokines and growth factors. However, a SC is an undifferentiated cell, and a specific and efficient paracrine function can hardly be awaited from it as compared to others, more differentiated cells. It should be noted in conclusion that the main problem with the SC and cell therapy is commercial influence. Probably, experience of some foreign countries should be studied, where moves have been made to stop the use of unproven treatments, including some stem cell therapy.     

Achievement of genetics in plant reproduction research: the past decade for the coming decade

In the last decade, a variety of innovations of emerging technologies in science have been accomplished. Advanced research environment in plant science has made it possible to obtain whole genome sequence in plant species. But now we recognize this by itself is not sufficient to understand the overall biological significance. Since Gregor Mendel established a principle of genetics, known as Mendel's Laws of Inheritance, genetics plays a prominent role in life science, and this aspect is indispensable even in modern plant biology. In this review, we focus on achievements of genetics on plant sexual reproduction research in the last decade and discuss the role of genetics for the coming decade. It is our hope that this will shed light on the importance of genetics in plant biology and provide valuable information to plant biologists.