Individual and collective behaviour in cellular slime mould development: contributions of John Bonner (1920-2019)

John Bonner used the cellular slime moulds to address issues that lie at the heart of evolutionary and developmental biology. He did so mostly by combining acute observation and a knack for asking the right questions with the methods of classical embryology. The present paper focusses on his contributions to understanding two phenomena that are characteristic of development in general: chemotaxis of single cells to an external attractant, and spatial patterning and proportioning of cell types in the multicellular aggregate. Brief mention is also made of other areas of slime mould biology where he made significant inputs. He saw cellular slime moulds as exemplars of development and worthy of study in their own right. His ideas continue to inspire researchers.

New species of dictyostelid cellular slime moulds from Australia

During the 2001–2006 field seasons, samples for isolation of dictyostelid cellular slime moulds were collected at several localities in Queensland, the Northern Territory, Western Australia and Victoria. The majority of these samples were collected from the soil–litter layer on the ground, but some additional samples were obtained from the layer of organic matter (‘canopy soil’) associated with the bases of vascular epiphytes on the trunks and branches of trees in the tropical forests of northern Queensland. Many of the forms recovered from these samples could be assigned to described taxa, including such cosmopolitan species as Dictyostelium mucoroides, Polysphondylium pallidum, P. violaceum and D. giganteum. However, several others appear to represent new species, and eight of these (D. boomeransporum, D. flexuosum, D. granulosum, D. myxobasis, D. radiculatum, D. rotatum, P. australicum and P. stolonicoideum) are described herein. The large number of apparently undescribed forms suggests that the dictyostelid biota of Australia is relatively distinct when compared with that of any other continent.

Implications of enzyme kinetics

Of the many examples of oscillatory kinetic behaviour known, several are briefly reviewed, including those of glycolysis, the peroxidase–oxidase reaction and oscillations in cellular calcium concentration. It is shown that simple mathematical models employing allosteric rate laws are sufficient to explain the instability of the steady state and the appearance of sustained oscillations. The cAMP-signalling systems of cellular slime moulds and the dynamics of intracellular calcium oscillations illustrate the importance of such oscillophores to inter- and intra-cellular communication and differentiation.