HtrA--a renaissance protein

Initially identified as proteases, members of the HtrA/DegP family of proteins have also been shown to act as chaperones in bacteria, and more recently implicated, as regulators of apoptosis in mammals. Two new structures of mammalian HtrA2 and E. coli DegP provide insights into the origin of this plurality of function.     

The renaissance of microbiology.

Microbiology is finally occupying its true position as the pre-eminent field in life sciences. This is due to advances in molecular techniques that confirm the evolutionary significance of the biology of microbes. It is anticipated that the use of comparative genomics will provide information that will advance the understanding of mechanisms of pathogenesis and the importance of secondary metabolism in social microbiology. More emphasis on studies of microbial diversity will increase its value in both fundamental microbiology and its industrial applications.     

The developmental renaissance in adaptationism

From an adaptation perspective, unoccupied patches of morphological space are inferred to be empty because they are of low fitness and selected against. These inferences hinge on venturesome assumptions, because emptiness is explained by low fitness and low fitness is inferred from emptiness. Moreover, non-adaptive factors, such as developmental constraint, could also plausibly account for empty morphospace. In response, biologists increasingly study ontogeny to test the assumption that unobserved phenotypes could be produced if selection were to favor them; finding that empty space morphologies can be readily produced in development helps reject constraint and lends support to adaptive hypotheses. This developmental approach to adaptation calls on manifold techniques, including embryology, artificial selection and comparative methods. Belying their diversity, all of these methods examine the causes of empty morphospace and mark a return of development, long excluded from traditional evolutionary biology, to adaptationist practice.     

The renaissance of aminoacyl-tRNA synthesis

The role of tRNA as the adaptor in protein synthesis has held an enduring fascination for molecular biologists. Over four decades of study, taking in numerous milestones in molecular biology, led to what was widely held to be a fairly complete picture of how tRNAs and amino acids are paired prior to protein synthesis. However, recent developments in genomics and structural biology have revealed an unexpected array of new enzymes, pathways and mechanisms involved in aminoacyl-tRNA synthesis. As a more complete picture of aminoacyl-tRNA synthesis now begins to emerge, the high degree of evolutionary diversity in this universal and essential process is becoming clearer.     

The renaissance of GSK3

Glycogen synthase kinase 3 (GSK3) was initially described as a key enzyme involved in glycogen metabolism, but is now known to regulate a diverse array of cell functions. The study of the substrate specificity and regulation of GSK3 activity has been important in the quest for therapeutic intervention.     

Genomics and the renaissance of generalism

A meeting report of the sessions on human, eukaryotic and bacterial genome sequencing at the American Society for Microbiology and Institut Pasteur joint conference: Genomes 2000 International Conference on Microbial and Model Genomes, Paris, April 11-15, 2000     

Epigenetics and the renaissance of heresy.

Classic neo-Darwinian theory is predicated on the notion that all heritable phenotypic change is mediated by alterations of the DNA sequence in genomes. However, evidence is accumulating that stably heritable phenotypes can also have an epigenetic basis, lending support to the long-discarded notion of inheritance of acquired traits. As many of the examples of epigenetic inheritance are mediated by position effects, the possibility exists that chromosome rearrangements may be one of the driving forces behind evolutionary change by exerting position effect alterations in gene activity, an idea articulated by Richard Goldschmidt. The emerging evidence suggests that Goldschmidt's controversial hypothesis deserves a serious reevaluation.     

The renaissance of fluorescence resonance energy transfer

Recent advances in fluorescence resonance energy transfer have led to qualitative and quantitative improvements in the technique, including increased spatial resolution, distance range, and sensitivity. These advances, due largely to new fluorescent dyes, but also to new optical methods and instrumentation, have opened up new biological applications.     

The renaissance of mitochondrial calcium transport.

Although the capacity of mitochondria for accumulating Ca2+ down the electrical gradient generated by the respiratory chain has been known for over three decades, the physiological significance of this phenomenon has been re-evaluated only recently. Indeed, it was long believed that the low affinity of the mitochondrial Ca2+ transporters would allow significant uptake only in conditions of cellular Ca2+ overload. Conversely, the direct measurement of [Ca2+] in the mitochondrial matrix revealed major [Ca2+] increases upon agonist stimulation. In this review, we will summarize: (a) the mechanisms that allow this large response, reconciling the biochemical properties of the transporters and the large amplitude of the mitochondrial [Ca2+] rises, and (b) the biological role of mitochondrial Ca2+ signalling, that encompasses the regulation of mitochondrial function and the modulation of the spatio-temporal pattern of cytosolic [Ca2+] increases.     

Cell division: The renaissance of the centriole

Centrioles are located at the center of the cytoskeleton and duplicate exactly once per cell cycle. Recent studies suggest that centrioles are required for the organization of a functional centrosome and that centriole assembly requires both gamma- and delta-tubulin.