The operon as paradigm: normal science and the beginning of biological complexity

The papers from the Jacob and Monod groups that presented the operon model and repressor control of gene expression provided a paradigm that opened up the field of gene regulation. Following the set of papers published between 1958 and 1961, there ensued almost immediately a period of "normal science" as Thomas Kuhn has defined it. Most researchers applied the repressor model to their own systems. I suggest a number of factors that were responsible for the rapid acceptance of the Jacob-Monod model and inhibited suggestions for alternative mechanisms of regulation. Nevertheless, I argue that this adherence to the paradigm, including specifically control by repressors, may well have been necessary for the field to progress. Ultimately, the evolution of this field of study was to reveal the unexpected complexity to genetic regulation.

The dawn of mesoscopic approach in drug development

The feeling of the reaching of a crucial turning point is shared by the whole spectrum of sciences. The main features of this turning point are basically identical across different disciplines and can be interpreted as a re-location of the most relevant level of explanation (and consequently intervention for more applicative fields) from the microscopic to the so called mesoscopic level. Here, the character of the mesoscopic approach in drug development field will be briefly commented.

Reflections on the origins and evolution of genetic toxicology and the Environmental Mutagen Society

This article traces the development of the field of mutagenesis and its metamorphosis into the research area we now call genetic toxicology. In 1969, this transitional event led to the founding of the Environmental Mutagen Society (EMS). The charter of this new Society was to "encourage interest in and study of mutagens in the human environment, particularly as these may be of concern to public health." As the mutagenesis field unfolded and expanded, new wording appeared to better describe this evolving area of research. The term "genetic toxicology" was coined and became an important subspecialty of the broad area of toxicology. Genetic toxicology is now set for a thorough reappraisal of its methods, goals, and priorities to meet the challenges of the 21st Century. To better understand these challenges, we have revisited the primary goal that the EMS founders had in mind for the Society's main mission and objective, namely, the quantitative assessment of genetic (hereditary) risks to human populations exposed to environmental agents. We also have reflected upon some of the seminal events over the last 40 years that have influenced the advancement of the genetic toxicology discipline and the extent to which the Society's major goal and allied objectives have been achieved. Additionally, we have provided suggestions on how EMS can further advance the science of genetic toxicology in the postgenome era. Any oversight or failure to make proper acknowledgment of individuals, events, or the citation of relevant references in this article is unintentional.

[Modern evolutional developmental biology: mechanical and molecular genetic or phenotypic approaches?]

Heightened interest in the evolutionary problems of developmental biology in the 1980s was due to the success of molecular genetics and disappointment in the synthetic theory of evolution, where the chapters of embryology and developmental biology seem to have been left out. Modern evo-devo, which turned out to be antipodean to the methodology of the synthetic theory of evolution, propagandized in the development of evolutionary problems only the mechanical and molecular genetic approach to the evolution of ontogenesis, based on cellular and intercellular interactions. The phonotypical approach to the evaluation of evolutionary occurrences in ontogenesis, which aids in the joining of the genetic and epigenetic levels of research, the theory of natural selection, the nomogenetic conception, and the problem of the wholeness of the organism in onto- and phylogenesis may be against this. The phenotypic approach to ontogenesis is methodologically the most perspective for evolutionary developmental biology.

Quantitative genetics in the era of molecular genetics: learning abilities and disabilities as an example

OBJECTIVE

To consider recent findings from quantitative genetic research in the context of molecular genetic research, especially genome-wide association studies. We focus on findings that go beyond merely estimating heritability. We use learning abilities and disabilities as examples.

METHOD

Recent twin research in the area of learning abilities and disabilities was reviewed.

RESULTS

Three findings from quantitative genetic research stand out for their far-reaching implications for child and adolescent psychiatry. First, common disorders such as learning difficulties are the quantitative extreme of the same genetic factors responsible for genetic influence throughout the normal distribution (the Common Disorders are Quantitative Traits Hypothesis). Second, the same set of genes is largely responsible for genetic influence across diverse learning and cognitive abilities and disabilities (the Generalist Genes Hypothesis). Third, experiences are just as influenced genetically as are behaviors and genetic factors mediate associations between widely used measures of the environment and behavioural outcomes (the Nature of Nurture Hypothesis).

CONCLUSIONS

Quantitative genetics can go far beyond the rudimentary "how much" question about nature versus nurture, and can continue to provide important findings in the era of molecular genetics.

Chapter 24: the coming of molecular biology and its impact on clinical neurology

Although the chemical study of the nervous system dates back well into the 19th century, molecular biology and especially molecular neurobiology only began to be established in the second half of the 20th century. This chapter reviews their impact on clinical neuroscience during the 50 years since Watson and Crick published their seminal paper. After a short review of the part played by F.O. Schmitt in establishing molecular neuroscience the chapter outlines work that led to a detailed understanding of the biochemical structure and function of nerve cell membranes and their embedded channel proteins, receptors, and other molecules. The chapter then turns to the numerous pathologies that result from disorders of these elements: the various channel and gap-junction pathologies. The chapter continues with a discussion of some of the diseases caused by defective DNA, especially the trinucleotide repeat expansion diseases (TREDs) and ends with a short account of the development of molecular approaches to prion diseases, myasthenia gravis, and the neurodegenerative diseases of old age. Francis Bacon said long ago that "knowledge is power." The hope is that increasing molecular knowledge will help cure some of the human suffering seen in the neurological ward and clinic.

What have we learned from the congenital myasthenic syndromes

The congenital myasthenic syndromes have now been traced to an array of molecular targets at the neuromuscular junction encoded by no fewer than 11 disease genes. The disease genes were identified by the candidate gene approach, using clues derived from clinical, electrophysiological, cytochemical, and ultrastructural features. For example, electrophysiologic studies in patients suffering from sudden episodes of apnea pointed to a defect in acetylcholine resynthesis and CHAT as the candidate gene (Ohno et al., Proc Natl Acad Sci USA 98:2017-2022, 2001); refractoriness to anticholinesterase medications and partial or complete absence of acetylcholinesterase (AChE) from the endplates (EPs) has pointed to one of the two genes (COLQ and ACHE ( T )) encoding AChE, though mutations were observed only in COLQ. After a series of patients carrying mutations in a disease gene have been identified, the emerging genotype-phenotype correlations provided clues for targeted mutation analysis in other patients. Mutations in EP-specific proteins also prompted expression studies that proved pathogenicity, highlighted important functional domains of the abnormal proteins, and pointed to rational therapy.

Target gene discovery for novel therapeutic agents in cancer treatment

Target identification of novel therapeutic drugs is pivotal for the establishment of (1) new anticancer regimens, (2) to control side effects of the drugs, and (3) to identify appropriate combinations with established drugs. Here, we describe several in vitro assays applicable to characterize different characteristics of tumor cells. Furthermore, we present a protocol for establishing a reporter gene system for in vivo imaging, allowing for the study of drug effects in small animal models.

Synthetic viruses: a new opportunity to understand and prevent viral disease

Rapid progress in DNA synthesis and sequencing is spearheading the deliberate, large-scale genetic alteration of organisms. These new advances in DNA manipulation have been extended to the level of whole-genome synthesis, as evident from the synthesis of poliovirus, from the resurrection of the extinct 1918 strain of influenza virus and of human endogenous retroviruses and from the restructuring of the phage T7 genome. The largest DNA synthesized so far is the 582,970 base pair genome of Mycoplasma genitalium, although, as yet, this synthetic DNA has not been 'booted' to life. As genome synthesis is independent of a natural template, it allows modification of the structure and function of a virus's genetic information to an extent that was hitherto impossible. The common goal of this new strategy is to further our understanding of an organism's properties, particularly its pathogenic armory if it causes disease in humans, and to make use of this new information to protect from, or treat, human viral disease. Although only a few applications of virus synthesis have been described as yet, key recent findings have been the resurrection of the 1918 influenza virus and the generation of codon- and codon pair-deoptimized polioviruses.

Molecular pharmacognosy: a new borderline discipline

Pharmacognosy has developed rapidly in recent years and now represents a highly interdisciplinary science. At the boundary between pharmacognosy and molecular biology, molecular pharmacognosy has developed as a new borderline discipline. Using the method and technology of molecular biology, molecular pharmacognosy focuses on resolving a wide range of challenging problems, such as distinguishing herbal and animal drug populations by molecular marker assay, conserving and utilizing wild resources on the basis of knowledge of genetic diversity, investigating the mechanism of active compound accumulation and obtaining new resources with higher quality through genetic engineering. Recent research results show that molecular pharmacognosy has extended the scope of pharmacognostical science and plays an important role in the safe and efficient usage of crude drugs.