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Two of the present authors have presented a model for macrofibril template self-assembly which is based on a concerted process of sudden, delayed, short filament formation with immediate phase transfer to a lyotropic liquid crystal (mesophase). In recent years, information on the spatio-temporal patterns of keratin protein expression within wool follicles has come to hand, and we here report some recently acquired important information in this area. If the "mesophase model" is to remain credible it must be compatible with the spatio-temporal patterns of keratin expression. This paper explores the match between the mesophase model and patterns of protein expression, and concludes that they are broadly consistent. At present the model does not extend to keratin associated protein (KAP) expression. The model is also particularly successful in explaining macrofibril structural features in different cell types. [ABSTRACT FROM AUTHOR]

Investigates the influence of optical cues on predatory behavior used by the jumping spider, Portia fimbriata in Australia. Cryptic stalking against standard virtual lure; Influence of the size of anterior median (AM) eyes on cryptic stalking; Freezing response when faced with lure with large AM eyes.

Portia fimbriata, an araneophagic jumping spider (Salticidae), makes undirected leaps (erratic leaping with no particular target being evident) in the presence of chemical cues from Jacksonoides queenslandicus, another salticid and a common prey of P.fimbriata. Whether undirected leaping by P.fimbriata functions as hunting by speculation is investigated experimentally. Our first hypothesis, that undirected leaps provoke movement by J. queenslandicus, was investigated using living P.fimbriata and three types of lures made from dead, dry arthropods (P.fimbriata, J. queenslandicus and Musca domestica). When a living P.fimbriata made undirected leaps or a spring-driven device made the lures suddenly move up and down, simulating undirected leaping, J. queenslandicus responded by waving its palps and starting to walk. There was no statistical evidence that the species from which the lure was made influenced J. queenslandicus' response in these tests. Our second hypothesis, that J. queenslandicus reaction to J. queenslandicus when J. queenslandicus reacted to lures simulating undirected leaping. In these tests, P.fimbriata responded by turning toward J. queenslandicus and waving its palps. [ABSTRACT FROM AUTHOR]

Investigates the optical cues for prey discernment by the jumping spider Portia fimbriata. Adoption of ordinary stalking by P. fimbriata when lure did not have anterior-median eyes visible; Adoption of cryptic stalking only against intact lures on which the large anterior-median eyes are visible.

The role of liquid-crystalline (mesophase) structures in extra-cellular morphogenesis is widely recognized. This paper summarizes a model for the more unusual case of intra-cellular mesophases. In the nascent mammalian hair cortex, cell differentiation is correlated with different mesophase textures within tactoids that are composed of intermediate filaments (IFs), and which form by a concerted process of unit-length-filament (ULF) polymerization and phase separation. Nematic and double-twist textures arise from differences in mesogen orientation and length in apposed tactoids. The model explains features of mature structures such as the fibril-matrix ratios in different cell types. The rapidity of IF formation suggests that a sudden-transition equilibrium polymerization, involving a high-energy initiating species, obeying the same statistical model as several other biological transitions, may be involved. This leads to an appealing symmetry, with the key factor in both polymerization and mesophase stability being the retention of protein head-group entropy. [ABSTRACT FROM AUTHOR]