A new look at antibiotic resistance

Abstract Since the discovery of antibiotic resistance in clinically important microbes, attention has focused properly on the profound medical aspects of this problem. However, studies of antibiotic resistance are of great interest in their own right for studies of gene regulation, evolution, chromosome structure, etc.; several resistance genes in clinical isolates are components of classical 'operon' structures. The construction of cloning vectors and gene transfer systems, particularly for interspecies studies, rely heavily on the use of antibiotic resistance genes, since these phenotypes can be used to select for DNA transfer between microbes, plants, and animals. Studies of the role of resistance mechanisms and their genetic determinants in antibiotic-producing organisms have shown that these functions play important roles in biosynthetic pathways and can provide important genetic and biochemical tools for the rational analysis of antibiotic production.     

A new look at cytokine signaling

Signal transduction is initiated when a cytokine binds to the extracellular domains of its receptors, bringing them together and triggering a complicated sequence of events inside the cell. In this issue, LaPorte et al. (2008) present crystal structures of three signaling complexes of the cytokines interleukin-4 and interleukin-13 with their receptors, showing how events taking place outside the cell may affect the specificity of signal transduction.     

A new look at vitreous-humour collagen.

The collagens of bovine vitreous-humour and nasal-septum cartilage have been extracted, fractionated and compared. Both tissues show the same heterogeneity of collagen types, consisting of type II, 1 alpha, 2 alpha, 3 alpha and C-PS collagens. The type II collagen of the vitreous humour was significantly more hydroxylated both in the lysine and proline residues than was that of cartilage. C-PS1 collagen, together with higher-Mr forms were present in the vitreous humour, but the higher-Mr forms were not seen in cartilage. Both C-PS1 and C-PS2 were present in vitreous humour and cartilage, but vitreous humour contained three times more of these collagens than did cartilage. Despite the difference in amount, the molar ratio C-PS1/C-PS2 was approx. 1 in both tissues, suggesting that they are components of a larger molecule. The 1 alpha, 2 alpha, 3 alpha collagens were present in the same concentration in both tissues. These three chains co-precipitated on dialysis against phosphate-buffered saline, pH 7.2, in a manner analogous to type V collagen.