Is polyphenol induction simply a result of altered carbon and nitrogen accumulation?

Carbon translocation in plants is shaped by phyllotaxis and regulated by source/sink interactions that respond to the demands of growth and defense. We have studied this extensively in poplar saplings, and recently showed that unlike carbon import, nitrogen is not translocated to sink leaves in response to application of jasmonic acid. Here we report that this is also true for young trees in the field. We discuss the importance of transport processes in establishing local C:N ratios, and suggest that the JA-induced flow of C but not N to sink tissues, and their corresponding increases in C-based defenses, may simply reflect a plant adaptation to handle excess reduced carbon and energy.     

Is adrenomedullin a causal agent in some cases of type 2 diabetes?

The study of two populations with a recent onset of type 2 diabetes showed that a subset of the patients had higher levels of adrenomedullin (AM) than the rest of the diabetics. In this subset, physiological elevations of AM might have triggered the disease in predisposed individuals. Diabetics showed higher levels of AM than healthy controls. In addition, glycemia was measured in diabetic rats after injection of saline, AM, or antiAM antibody. AM elevated glycemia, whereas the antibody reduced circulating glucose to normal. These results suggest that manipulation of AM levels could represent a new approach in the management of diabetes for the appropriate individuals.     

Is a genome a codeword of an error-correcting code?

Since a genome is a discrete sequence, the elements of which belong to a set of four letters, the question as to whether or not there is an error-correcting code underlying DNA sequences is unavoidable. The most common approach to answering this question is to propose a methodology to verify the existence of such a code. However, none of the methodologies proposed so far, although quite clever, has achieved that goal. In a recent work, we showed that DNA sequences can be identified as codewords in a class of cyclic error-correcting codes known as Hamming codes. In this paper, we show that a complete intron-exon gene, and even a plasmid genome, can be identified as a Hamming code codeword as well. Although this does not constitute a definitive proof that there is an error-correcting code underlying DNA sequences, it is the first evidence in this direction.     

Is gene therapy a form of eugenics?

If, as I believe, gene therapy is in principle ethically sound except for its possible connection with eugenics then there are two obvious ways of giving a simple and straightforward answer to a question such as this. The first is to say "yes it is, and so what?" The second is to say "no it isn't so we shouldn't worry". If we accept the first of the above definitions we might well be inclined to give the first of our two answers. If on the other hand, we accept the sort of gloss that Ruth Chadwick gives on Galton's account, "those who are genetically weak should simply be discouraged from reproducing", either by incentives or compulsory measures, we get a somewhat different flavour, and one which might incline a decent person who favours gene therapy towards the second answer.     

Is there a biology of quantum information?

This paper briefly considers the notion of a biology of quantum information from a number of complementary points of view. We begin with a very brief look at some of the biomolecular systems that are thought to exploit quantum mechanical effects and then turn to the issue of measurement in these systems and the concomitant generation of information. This leads us to look at the internalist stance and the exchange interaction of quantum particles. We suggest that exchange interaction can also be viewed using ecological ideas related to apparatus-object. This can also help develop the important notion of complementarity in biosystems in relation to the nature and generation of information at the microphysical scale.     

Is the originality of a species measurable?

In this paper, we introduce the concept of 'originality of a species within a set' in order to indicate the average rarity of all the features belonging to this species. Using a phylogenetic tree of 70 species of New World terrestrial Carnivora, we suggest measuring the originality by a probability distribution. This maximizes the expected number of features shared by two species randomly drawn from the set. By using this new index, we take account of branch lengths whereas current indices of originality focus on tree topology. As a supplement to Nee and May's optimizing algorithm, we find that originality must be one of the criteria used in conservation planning.     

Regulation of integrin function through conformational complexity: not simply a knee-jerk reaction?

Such diverse biological processes as the maintenance of tissue architecture and the regulation of cell migration are controlled through dynamic changes in integrin receptor conformation. Early analyses of the mechanisms of shape change by integrins led to the definition of three inter-convertible conformational states: inactive, primed and ligand-occupied. Recent advances reviewed in this article have now shown that the integrin molecule contains a number of flexible joints and connections, leading to a broad spectrum of possible conformational states. This conformational complexity is likely to permit fine-tuning of integrin function through regulation of ligand-binding affinity and intracellular signalling.     

Is aggregation of beta-amyloid peptides a mis-functioning of a current interaction process?

In a previous study, Hughes et al. [Proc. Natl. Acad. Sci. USA 93 (1996) 2065-2070] demonstrated that the amyloid peptide is able to interact with itself in a two-hybrid system and that interaction is specific. They further supported that the method could be used to define the sequences that might be important in nucleation-dependent aggregation. The sequence of the amyloid peptide can be split into four clusters, two hydrophilic (1-16 and 22-28) and two hydrophobic (17-21 and 29-42). We designed by molecular modeling and tested by the two-hybrid approach, series of mutations spread all over the sequence and changing the distribution of hydrophobicity and/or the spatial hindrance. In the two-hybrid assay, interaction of native Abeta is reproduced. Screening of mutations demonstrates that the C-domain (residues 29-40 (42)), the median domain (residues 17-22) and the N-domain (1-16) are all crucial for interaction. This demonstrates that almost all fragments of the amyloid peptide but a loop (residues 23-28) and the C-term amino acid are important for the native interaction. We support that the folded three-dimensional (3D) structure is the Abeta-Abeta interacting species, that the whole sequence is involved in that 3D fold which has a low secondary structure propensity and a high susceptibility to mutations and thus should have a low stability. The native fold of Abeta could be stabilized in Abeta-Abeta complexes which could in other circumstances facilitate the nucleation event of aggregation that leads to the formation of stable senile plaques.     

Is a mosaic embryo also a mosaic of communication compartments?

We have studied the pathways of cell communication in embryos of the mollusc Lymnaea stagnalis in which the developmental fate of a cell or a group of cells is known from cell lineage studies. We iontophoretically injected Lucifer Yellow CH and followed the spread of fluorescence between cells interconnected via gap junctions. In early stages all blastomeres appear to be dye-coupled, but later on communication is restricted within compartments. The pattern of cell communication corresponds with the development of compartments with specific cell fates. Dye-spread is limited by communication boundaries which completely or mostly prevent the passage of dye to adjacent compartments with different developmental fates. These boundaries appear progressively during development. Our results suggest that, during the development of Lymnaea, the progressive changes in the pattern of dye spread correspond with the progressive restrictions of the developmental fates of individual cells or groups of cells. We conclude that changes in the pattern of cell communication and in the appearance of communication compartments are not exclusive features of regulative embryos.     

Is Histoplasma capsulatum a native inhabitant of Japan?

Histoplasmosis is an infectious disease caused by inhaling spores of the fungal pathogen H. capsulatum and in Japan is considered an imported mycosis. However, some patients in Japan with histoplasmosis have no history of traveling overseas nor of risk of occupational exposure to Histoplasma. To investigate the possibility of native distribution of Histoplasma in Japan, 187 bat guano samples from 67 bat‐inhabited caves in 17 prefectures were collected. These were examined for H. capsulatum by culture and Histoplasma‐specific PCR in three independent laboratories. No H. capsulatum was detected by either method, therefore H. capsulatum is unlikely to be present in bat guano in Japanese caves.     

Is stress-induced analgesia a measure of stress severity?

When comparing magnitudes of "behavioural despair" (duration of immobility) and stress-induced analgesia in the tail suspension test and cold water swim test with SHR and NMRI male mice. The results might depend on saline injection prior the test and on the fact that exposure to cold water in swim test was sufficient to alter the response patterns. The findings show that the main parameters are closely related to each other. Stress-induced analgesia seems to be a measure of stress as the stress becomes stronger analgesia changes in linear dependence, whereas duration of immobility has an invert U-shaped function.     

Is N-acetylglutamate a short-term regulator of urea synthesis?

A method is described for determining N-acetylglutamate as glutamate. N-Acetylglutamate content of hepatocytes from 48 h-starved rats is high. It shows no parallelism with rates of urea synthesis from glutamine. We question its accepted function as a short-term regulator of urea synthesis.     

Is canavanine a natural component of mammalian metabolism?

A group of non-protein amino acids of higher plants, namely l-canavanine, l-canaline, 0-ureido-l-homoserine, and l-canavaninosuccinic acid, have been implicated in mammalian intermediary metabolism. The clinical observations and biochemical basis for this hypothesis as well as conflicting experimental evidence are presented. A possible explanation for the apparent role of these non-protein amino acids in mammalian metabolism is offered.