Family life at close quarters: communication and constraint in angiosperm seed development

The formation of viable angiosperm seeds involves the co-ordinated growth and development of three genetically distinct organisms, the maternally derived seed coat and the zygotic embryo and endosperm. The physical relationships of these tissues are initially established during the specification and differentiation of the female gametophyte within the tissues of the developing ovule. The molecular programmes implicated in both ovule and seed development involve elements of globally important pathways (such as auxin signalling), as well as ovule- and seed-specific pathways. Recurrent themes, such as the precisely controlled death of specific cell types and the regulation of cell–cell communication and nutrition by the selective establishment of symplastic and apoplastic barriers, appear to play key roles in both pre- and post-fertilization seed development. Much of post-fertilization seed growth occurs during a key developmental window shortly after fertilization and involves the dramatic expansion of the young endosperm, constrained by surrounding maternal tissues. The complex tissue-specific regulation of carbohydrate metabolism in specific seed compartments has been shown to provide a driving force for this early seed expansion. The embryo, which is arguably the most important component of the seed, appears to be only minimally involved in early seed development. Given the evolutionary and agronomic importance of angiosperm seeds, the complex combination of communication pathways which co-ordinate their growth and development remains remarkably poorly understood.     

Biophysics at the turn of the century: autowaves

By the example of the formation of dissipative patterns in Belousov-Zhabotinsky reactions and in population waves of mobile microorganisms, an attempt was made to analyze the development of the "autowave conception" in the last ten years. New results obtained at the Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, were demonstrated. The place of the "autowave conception" among other methods of studying nonlinear cooperative bioprocesses that form the basis of synergism is shown. The review was prepared on the occasion of the 275th anniversary of the Russian Academy of Sciences and the 2nd Biophysical Meeting of Russia.     

Representations of the Natural System in the Nineteenth century

‘The Natural System’ is the abstract notion of the order in living diversity. The richness and complexity of this notion is revealed by the diversity of representations of the Natural System drawn by ornithologists in the Nineteenth Century. These representations varied in overall form from stars, to circles, to maps, to evolutionary trees and cross-sections through trees. They differed in their depiction of affinity, analogy, continuity, directionality, symmetry, reticulation and branching, evolution, and morphological convergence and divergence. Some representations were two-dimensional, and some were three-dimensional; n-dimensional representations were discussed but never illustrated. The study of diagrammatic representations of the Natural System is made difficult by the frequent failure of authors to discuss them in their texts, and by the consequent problem of distinguishing features which carried meaning from arbitrary features and printing conventions which did not. Many of the systematics controversies of the last thirty years have their roots in the conceptual problems which surrounded the Natural System in the late 1800s, problems which were left unresolved when interest in higher-level systematics declined at the turn of this century. From the symposium ‘Making Sense of Science Making Diagrams’, held at the History, Philosophy, and Social Studies of Biology meeting, London, Ontario, 1989.     

Parasitic diseases: opportunities and challenges in the 21st century

The opportunities and challenges for the study and control of parasitic diseases in the 21st century are both exciting and daunting. Based on the contributions from this field over the last part of the 20th century, we should expect new biologic concepts will continue to come from this discipline to enrich the general area of biomedical research. The general nature of such a broad category of infections is difficult to distill, but they often depend on well-orchestrated, complex life cycles and they often involve chronic, relatively well-balanced host/parasite relationships. Such characteristics force biological systems to their limits, and this may be why studies of these diseases have made fundamental contributions to molecular biology, cell biology and immunology. However, if these findings are to continue apace, parasitologists must capitalize on the new findings being generated though genomics, bioinformatics, proteomics, and genetic manipulations of both host and parasite. Furthermore, they must do so based on sound biological insights and the use of hypothesis-driven studies of these complex systems. A major challenge over the next century will be to capitalize on these new findings and translate them into successful, sustainable strategies for control, elimination and eradication of the parasitic diseases that pose major public health threats to the physical and cognitive development and health of so many people worldwide.     

Entering the 21st century: the challenges for development

By many people, the 20th century will be remembered as an era of great achievement in human endeavour, and of enormous economic growth and prosperity. Achievements in medical research, from eradicating infectious diseases to laser surgery; in engineering, from the transistor to space exploration; and in economic development have all contributed to greater well being in the world at the end of the 20th century. Among the challenges to development identified by the World Bank in the coming decades will be managing the twin processes of globalization and localization, as well as post-conflict reconstruction. These will form the backdrop of the Bank''s main focus of creating a world free of poverty.     

Natural foci of leptospirosis in Moscow in 1995 - 2004

The article deals with the results of the 10-year study of the synanthropic urban foci of leptospirosis on the territory of Moscow. Information on the manifestation of the activity of the foci under study, rodents serving as the reservoir of infection in these foci, the etiological structure of the leptospires among these rodents, the state of leptospirosis morbidity among humans is presented.     

Natural foci of leptospirosis on the territory of Moscow in 1995 - 2004

The results of ten-year observations of the natural foci of leptospirosis on the territory of Moscow are presented. Information on the foci, the main species of small mammals (the reservours of the infection), the etiological structure of leptospires, circulating among rodents and insectivores, is given.     

Therapeutic treatments of mtDNA diseases at the earliest stages of human development

More than 150 pathogenic mitochondrial DNA (mtDNA) mutations associated with a range of illnesses have been described in humans. These mutations are carried by one in 400 people and their inheritance is exclusively maternal. Currently there is no method to prevent mtDNA diseases, which highlights the need for strategies to predict their transmission. Here we outline the scientific background and unique difficulties in understanding the transmission of mtDNA diseases, explaining why their management has lagged so far behind the genetics revolution. Moreover, both current and future management options, including cytoplasmic and nuclear transfer, are also discussed.