Between the sheets: a molecular sieve makes myelin membranes

Myelin is a lipid-rich, spiraled membrane structure that allows for rapid propagation of action potentials through axons. In this issue, Aggarwal et?al. (2011) present evidence that myelin basic protein, essential for myelination by oligodendrocytes, regulates the biosynthesis of myelin membranes by restricting diffusion of membrane-bound proteins into compact myelin.     

Chromatography of prostaglandins utilizing silicic acid impregnated-glass fiber sheets: A communication

A chromatographic method has been developed which offers rapid and convenient monitoring of prostaglandin biosynthesis from arachidonic acid.     

Studying plant development in mosses: the transgenic route

The current status of transgenic studies in mosses is reviewed with particular attention being given to the mosses Physcomitrella patens and Ceratodon purpureus. This paper reviews the advantages of using mosses as models for higher plants in the study of plant development, and includes developmental processes, already partially characterized at the genetic level by mutant analysis, for which transgenic studies may be applicable. The P. patens transformation process is being studied in this laboratory and details are given for a class of transformants which contain extrachromosomal plasmid DNA. Publications which present the nucleic acid and/or protein sequence for nuclear, chloroplast and mitochondrial genes are reviewed. Areas of research in which transgenic studies promise to complement existing cell biological and physiological approaches are discussed. These include the measurement of calcium levels in mutant and wild-type transformants expressing the apoaequorin gene and a role for phytochrome gene expression in the establishment of polarity.     

Cysteine-rich peptides (CRPs) mediate diverse aspects of cell-cell communication in plant reproduction and development

Cell-cell communication in plants is essential for the correct co-ordination of reproduction, growth, and development. Studies to dissect this mode of communication have previously focussed primarily on the action of plant hormones as mediators of intercellular signalling. In animals, peptide signalling is a well-documented intercellular communication system, however, relatively little is known about this system in plants. In recent years, numerous reports have emerged about small, secreted peptides controlling different aspects of plant reproduction. Interestingly, most of these peptides are cysteine-rich, and there is convincing evidence suggesting multiple roles for related cysteine-rich peptides (CRPs) as signalling factors in developmental patterning as well as during plant pathogen responses and symbiosis. In this review, we discuss how CRPs are emerging as key signalling factors in regulating multiple aspects of vegetative growth and reproductive development in plants.     

Reducing the babel in plant volatile communication: using the forest to see the trees

While plants of a single species emit a diversity of volatile organic compounds (VOCs) to attract or repel interacting organisms, these specific messages may be lost in the midst of the hundreds of VOCs produced by sympatric plants of different species, many of which may have no signal content. Receivers must be able to reduce the babel or noise in these VOCs in order to correctly identify the message. For chemical ecologists faced with vast amounts of data on volatile signatures of plants in different ecological contexts, it is imperative to employ accurate methods of classifying messages, so that suitable bioassays may then be designed to understand message content. We demonstrate the utility of ‘Random Forests’ (RF), a machine‐learning algorithm, for the task of classifying volatile signatures and choosing the minimum set of volatiles for accurate discrimination, using data from sympatric Ficus species as a case study. We demonstrate the advantages of RF over conventional classification methods such as principal component analysis (PCA), as well as data‐mining algorithms such as support vector machines (SVM), diagonal linear discriminant analysis (DLDA) and k‐nearest neighbour (KNN) analysis. We show why a tree‐building method such as RF, which is increasingly being used by the bioinformatics, food technology and medical community, is particularly advantageous for the study of plant communication using volatiles, dealing, as it must, with abundant noise.     

Heterochrony in plant development

Plants proceed through several distinct phases of growth and development in their life cycle. Under normal conditions, one phase terminates as another begins, but the relative time at which the phases initiate and terminate can be altered experimentally. New phenotypes are obtained when two developmental phases are expressed at the same time, as well as when phases are shifted coordinately. By analyzing these phenotypes, we can learn how plants normally regulate the transitions between developmental phases.     

Cytoskeleton in plant development

The plant cytoskeleton has crucial functions in a number of cellular processes that are essential for cell morphogenesis, organogenesis and development. These functions have been intensively investigated using single cell model systems. With the recent characterization of plant mutants that show aberrant organogenesis resulting from primary defects in cytoskeletal organization, an integrated understanding of the importance of the cytoskeleton for plant development has begun to emerge. Newly established techniques that allow the non-destructive visualization of microtubules or actin filaments in living plant cells and organs will further advance this understanding.     

Plastids unleashed: their development and their integration in plant development

Derived by endosymbiosis from ancestral cyanobacteria, chloroplasts integrated seamlessly into the biology of their host cell. That integration involved a massive transfer of genes to the cell's nucleus, with the modification of pre-existing processes, like plastid division and the operation of the plastid genetic machinery and the emergence of new ones, like the import of proteins translated in the cytoplasm. The uncovering in molecular detail of several of these processes reveals a merger of mechanisms of symbiont and host origin. Chloroplasts acquired roles as part of the biology of land plants by differentiating into a variety of interconvertible plastid forms according to the cell type. How these conversions take place, or how new problems, like the regulation of the plastid population size in cells, have been solved, is barely starting to be understood. Like the whole plant and as a result of the requirements and dangers associated with photosynthetic activity, chloroplasts in particular are under the control of environmental cues. Far from being passive targets of cellular processes, plastids are sources of signals of plastid-nuclear communication, which regulate activities for their own biogenesis. Plastids are also sources of developmental signals, in whose absence tissue architecture or cell differentiation are aberrant, in a cell-autonomous fashion. Over evolutionary time, plastids also contributed many genes for activities that are no longer directly associated with them (like light perception or hormone function). The overall picture is one in which plastids are at both the receiving and the acting ends in plant development, in both ontogenic and evolutionary terms.     

Cell-cell communication in plants: self-incompatibility in flower development.

Self-incompatibility, a mechanism that prevents self-fertilization in plants, is based on the ability of the pistil to discern the presence of self-pollen and on the female tissue's capacity to inhibit the growth or germination of self-related, but not of genetically unrelated, pollen. As a self-recognition system, self-incompatibility responds to specific cellular products and signals and thus offers a unique system in which to study the components of cellular communication in plants. The cytological manifestations of self-incompatibility have been well studied, and, with the cloning of cDNAs for several proteins associated with this recognition process, a detailed molecular view of self-incompatibility is emerging.     

Between cheap and costly signals: the evolution of partially honest communication

Costly signalling theory has become a common explanation for honest communication when interests conflict. In this paper, we provide an alternative explanation for partially honest communication that does not require significant signal costs. We show that this alternative is at least as plausible as traditional costly signalling, and we suggest a number of experiments that might be used to distinguish the two theories.