The range of life in amber: significance and implications in DNA studies

A survey of the major fossiliferous amber deposits is provided, including ages and various categories of life forms reported from each. The frequence of occurrence of the major groups of plants and animals in these amber deposits is also given. Thus far, DNA from four insect and one plant species has been extracted from amber fossils. In the case of the stingless bee in Dominican amber, evidence of reproducibility is provided, since two independent laboratories isolated DNA from six or more different specimens of the same insect.Amber sources for DNA studies are listed together with their advantages and disadvantages. The important points are the availability of desired pieces, the proper identification of the fossil, verification of the amber deposit, the cost involved, and the feasibility of causing damage to the specimen. The availability of several types of amber (Mexican, Dominican, Baltic, Chinese, Canadian, Siberian and Lebanese) at four major sources (academic collections, commercial dealers, private collections and amber mines) is discussed. The scientific implications of obtaining DNA from amber inclusions are presented.     

The censoring of Galileo’s Sunspot Letters and the first phase of his trial

Galileo’s Sunspot Letters, published in 1613, underwent extensive censorship before publication. It seems likely that the Roman Inquisition had charge of the pre-publication review of Galileo’s work, rather than the usual organ, the Master of the Sacred Palace. A study of that process demonstrates that the issue to which the censors objected was Galileo’s use of the bible, not his allegiance to Copernicus. In the course of the first phase of Galileo’s trial, orchestrated by one of the most powerful Cardinal Inquisitors, two propositions allegedly drawn from the book were judged either “formally heretical” or “at least erroneous in the faith.” These judgments might have come not from the published book but from the Inquisition’s censorship of its drafts. They supported Galileo’s silencing in 1616.     

Differentiation and tumorigenicity of human malignant melanocytes. Comparative study of two "non pigmented" and pigmented lines from the same fibroblastoid cells]

A morphological, caryological and biochemical study of two established cell lines of human malignant melanocytes derived from the same original tumour, when compared with heterotransplantation results in nude Mice, showed that "non-pigmented" cells are more tumorigenic than pigmented cells. Differentiation and tumorigenicity, although concomitant, here seem to be two independent phenomena.     

The life cycle of neutral lipids: synthesis, storage and degradation

Triacylglycerols (TAGs), steryl esters (SEs) and wax esters (WEs) form the group of neutral lipids. Whereas TAGs are present in all types of cell, the occurrence of SEs in prokaryotes is questionable, and the presence of WEs as storage molecules is restricted to plants and a few bacteria. Here, we summarize recent knowledge on the formation, storage and degradation of TAGs and SEs in various cell types. We describe the biochemical pathways involved in TAG and SE synthesis and discuss the subcellular compartmentation of these processes. Recently, several novel enzymes governing the metabolism of storage lipids have been identified and characterized. Regulatory aspects of neutral lipid storage are just beginning to be understood. Finally, we describe consequences of defects in neutral lipid metabolism. Since severe diseases like atherosclerosis, obesity and type 2 diabetes are caused by lipid accumulation, mechanisms underlying neutral lipid synthesis, depot formation and mobilization are of major interest for curing such diseases that are increasingly associated with modern civilization. Received 18 January 2006; received after revision 7 March 2006; accepted 16 March 2006     

Kant and the scope of analogy in the life sciences

In the present paper I investigate the role that analogy plays in eighteenth-century biology and in Kant's philosophy of biology. I will argue that according to Kant, biology, as it was practiced in the eighteenth century, is fundamentally based on analogical reflection. However, precisely because biology is based on analogical reflection, biology cannot be a proper science. I provide two arguments for this interpretation. First, I argue that although analogical reflection is, according to Kant, necessary to comprehend the nature of organisms, it is also necessarily insufficient to fully comprehend the nature of organisms. The upshot of this argument is that for Kant our understanding of organisms is necessarily limited. Second, I argue that Kant did not take biology to be a proper science because biology was based on analogical arguments. I show that Kant stemmed from a philosophical tradition that did not assign analogical arguments an important justificatory role in natural science. Analogy, according to this conception, does not provide us with apodictically certain cognition. Hence, sciences based on analogical arguments cannot constitute proper sciences.     

Aging and TOR: interwoven in the fabric of life

Longstanding results with calorie and growth factor restriction plus recent results with the first interventional drug suggest that retarding the pace of aging to improve the quality of life of older people is at hand. The biological system targeted by these approaches is the target of rapamycin (TOR), which is central for cellular responses to a variety of stimuli including stressors, growth factors, and nutrients and energy states. That the life-extending response to reducing its activity is highly conserved from yeast to mammals is consistent with the evolution of aging as a strategy to preserve reproductive potential of young cells and animals.