Molecular biology: silencing unlimited

Heterochromatin domains are essential for normal chromosome functions. The Eri1 ribonuclease is a negative regulator of the RNA interference machinery; recent studies have shown that, in fission yeast lacking Eri1, heterochromatin formation is more promiscuous.     

Lipophilic triphenylphosphonium cations as tools in mitochondrial bioenergetics and free radical biology

Lipophilic phosphonium cations were first used to investigate mitochondrial biology by Vladimir Skulachev and colleagues in the late 1960s. Since then, these molecules have become important tools for exploring mitochondrial bioenergetics and free radical biology. Here we review why these molecules are useful in mitochondrial research and outline some of the ways in which they are now being utilized.Translated from Biokhimiya, Vol. 70, No. 2, 2005, pp. 273–283.Original Russian Text Copyright ¢ 2005 by Ross, Kelso, Blaikie, James, Cochemé, Filipovska, Da Ros, Hurd, Smith, Murphy.This revised version was published online in April 2005 with corrections to the post codes.     

Molecular radiation biology: Future aspects

Summary Future aspects of molecular radiation biology may be envisaged by looking for unsolved problems and ways to analyse them. Considering the endpoints of cellular radiation effects as cell inactivation, chromosome aberrations, mutation and transformation, the type of DNA damage in the irradiated cell and the mechanisms of DNA repair as excision repair, recombination repair and mutagenic repair are essential topics. At present, great efforts are made to identify, to clone and to sequence genes involved in the control of repair of DNA damage and to study their regulation. There are close relationships between DNA repair genes isolated from various organisms, which promises fast progress for the molecular analysis of repair processes in mammalian cells. More knowledge is necessary regarding the function of the gene products, i.e. enzymes and proteins involved in DNA repair. Effort should be made to analyse the enzymatic reactions, leading to an altered nucleotide sequence, encountered as a point mutation. Mislead mismatch repair and modulation of DNA polymerase might be possible mechanisms.Paper given at the workshop Molecular Radiation Biology. German Section of the DNA Repair Network, München-Neuherberg, 21.–23.3.90     

Photosynthesis research in India: transition from yield physiology into molecular biology

Photosynthesis research in India can be traced back several thousand years, with the mention of the Sun energizing the plants, which form food for all living creatures on the earth (from the Mahabharata, the great epic, ca. 2600 B.C.) and the report of Sage Parasara (ca. 100 B.C.) on the ability of plants to make their own food, due to their pigments. With the pioneering studies by Sir Jagdish Chandra Bose, work on photosynthesis proceeded steadily during the first half of the 20th century. Some of the classic reports during this period are: malate metabolism in Hydrilla, spectrophotometric estimation of chlorophylls, importance of spectral quality for photosynthesis – an indication of two photosystems, photoinactivation of photosynthesis, and importance of flag leaf photosynthesis to grain yield. After the 1960s, there was a burst of research in the areas of physiology and biochemistry of carbon assimilation and photochemistry. A significant transition occurred, before the beginning of new millennium, into the area of molecular biology of chloroplasts, regulation of photosynthesis and stress tolerance. Future research work in India is geared to focus on the following aspects of photosynthesis: elucidation/analysis of genes, molecular biology/evolution of enzymes, development/use of transgenics and modeling. This revised version was published online in August 2006 with corrections to the Cover Date.     

Molecular biology and Pauling's immunochemistry: a neglected dimension

This paper argues that there is a substantial overlap between the history of immunology and the history of molecular biology, an overlap manifested in the researches on antibodies during the 1930s and 1940s. This common ground is a product of intellectual developments, as well as institutional trends. Viewed from an intellectual vantage point of the 1930s and 1940s, molecular biology was essentially the study of the biological specificities of the so-called 'giant protein molecules'. Within the conceptual framework of early molecular biology, which was rooted in the protein view of life, the concepts of protein template, autocatalysis, and heterocatalysis were central in explaining the protein syntheses of genes, viruses, enzymes, hormones, and antibodies. Immunochemistry and serological genetics were at the heart of that research agenda. This paper also shows that the immunochemistry program of Linus Pauling, which focused on molecular mechanisms of antibody structure and function, and the projects in serological genetics at Caltech's biology division were supported by the Rockefeller Foundation under the aegis of its molecular biology program. Based on the close examination of intellectual and institutional factors, the histories of molecular biology and immunology in the pre-DNA era are seen as closely linked.     

Molecular biology of hair morphogenesis: development and cycling

In mammals, hair follicles produce hairs that fulfill a number of functions including thermoregulation, collecting sensory information, protection against environmental trauma, social communication, and mimicry. Hair follicles develop as a result of epithelial-mesenchymal interactions between epidermal keratinocytes committed to hair-specific differentiation and cluster of dermal fibroblasts that form follicular papilla. During postnatal life, hair follicles show patterns of cyclic activity with periods of active growth and hair production (anagen), apoptosis-driven involution (catagen), and relative resting (telogen). During last decade, substantial progress has been achieved in delineating molecular mechanisms that control hair follicle development and cyclic activity. In this review, we summarize the data demonstrating that regulation of hair follicle development in the embryo and control of hair follicle growth during postnatal life are highly conserved and both require involvement of similar molecular mechanisms. Since many of the molecules that control hair follicle development and cycling are also involved in regulating morphogenesis and postnatal biology of other ectodermal derivatives, such as teeth, feathers, and mammary glands, basic principles and molecular mechanisms that govern hair follicle development and growth may also be applicable for other developmental systems.     

Molecular biology of archaebacteria

In the process of phylogenetic studies, based on the comparative analysis of sequences of 16S (18S) rRNA, C. Woese and collaborators discovered that some microorganisms, which previously had been described as bacteria, form a group named archaebacteria, differing from other bacteria as well as from eukaryotes to the same extent as the latter differ from each other. A review of the work leading to that result, as well as characteristics of archaebacteria with emphasis on their biochemistry and molecular biology, is presented.