The ‘root-brain’ hypothesis of Charles and Francis Darwin: Revival after more than 125 years

This year celebrates the 200^th aniversary of the birth of Charles Darwin, best known for his theory of evolution summarized in On the Origin of Species. Less well known is that, in the second half of his life, Darwin’s major scientific focus turned towards plants. He wrote several books on plants, the next-to-last of which, The Power of Movement of Plants, published together with his son Francis, opened plants to a new view. Here we amplify the final sentence of this book in which the Darwins proposed that: “It is hardly an exaggeration to say that the tip of the radicle thus endowed [with sensitivity] and having the power of directing the movements of the adjoining parts, acts like the brain of one of the lower animals; the brain being seated within the anterior end of the body, receiving impressions from the sense-organs, and directing the several movements.” This sentence conveys two important messages: first, that the root apex may be considered to be a ‘brain-like’ organ endowed with a sensitivity which controls its navigation through soil; second, that the root apex represents the anterior end of the plant body. In this article, we discuss both these statements.Key words: auxin, cognition, plant neurobiology, plant tropisms, roots, sensory biology, signaling     

The Scientific Discovery of ‘Natural Capital’: The Production of Catalytic Antibodies

Modern science has undoubtedly become one the principal engines of economic growth, even though the epistemological status of scientific knowledge has been continuously contested. Leaving the philosophical problem of knowledge aside, this paper examines how scientific discovery contributes to the production of wealth. The analysis focuses on a recent achievement at the crossroads of chemistry, immunology and biotechnology: antibody catalysis. For this purpose, we develop a model of entrepreneurial work to explain how the discovery of natural products and processes generates new economic opportunities. The proposed model is based on the assumption that scientists believe that the natural environment is a repository of ‘natural capital’. Natural capital includes goods that are not made by humans but can be used to produce other goods and services. The belief in natural capital induces scientists to search for and identify a natural property that, in the specific cultural context of their work, is recognized as a valuable resource. The selection of such a property forms the initial phase of the discovery process. Certain research methods are then deployed to create novel empirical conditions within which the selected property is transformed into a specific good. The discovery of natural capital thus comprises a historically accountable entrepreneurial endeavour.     

CD46: The ‘multitasker’ of complement proteins

Complement is undeniably quintessential for innate immunity by detecting and eliminating infectious microorganisms. Recent work, however, highlights an equally profound impact of complement on the induction and regulation of a wide range of immune cells. In particular, the complement regulator CD46 emerges as a key sensor of immune activation and a vital modulator of adaptive immunity. In this review, we summarize the current knowledge of CD46-mediated signalling events and their functional consequences on immune-competent cells with a specific focus on those in CD4⁺ T cells. We will also discuss the promises and challenges that potential therapeutic modulation of CD46 may hold and pose.     

The spectre of ‘spurious’ correlations

Summary Ecologists often standardize data through the use of ratios and indices. Such measures are employed generally to remove a size effect induced by some relatively uniteresting variable. The implications of using the resultant data in correlation and regression analyses are poorly recognized. We show that ratios and indices often provide surprising and spurious results due to their unusual properties. As a solution, we advocate the use of randomization tests to evaluate hypotheses confounded by spurious correlations. In addition, we emphasize that identifying the appropriate null correlation is of utmost importance when statistically evaluating ratios, although this issue is frequently ignored.     

The patient’s hay-fever diary: three years of results from Germany

The patient’s hay-fever diary (PHD) is a newly developed, internet-based tool for self-documentation of pollen-induced symptoms (eyes, nose and airways), general well-being and medication use. In Germany, more than 1,600 users made over 60,500 reports in 3 years (2009–2011). An analysis of these reports reveal that the nose symptom “sneezing” is the most commonly reported (3/10 of reports), followed by eye symptom “itching” and nose “blocked”. In addition, medication use follows a similar pattern every year, with tablets being the most commonly used medication type (up to 60 % of the reports made in the years 2009 and 2011). Temporal variations in overall symptoms and organ-specific symptom scores are found to be associated with atmospheric concentrations of birch and grass pollen. Data from the PHD can be analysed with the aid of various mathematical methods and may provide information about symptoms and their severity for pollen-allergic sufferers. They may also be valuable for clinical studies in immunotherapy with pollen extracts.     

The ‘curse’ of Westermarck 1

This article consists of a critical application of recent theory of nationalism to the unusual case of Mauritius. It is a poly‐ethnic and poly‐religious society whose inhabitants neither share a mythical distant past nor consider themselves culturally identical, but where nation‐building has nevertheless been moderately successful since the late 1960s. Through an examination of the processes of institutional and cultural nation‐building in the island, it is argued that the current Eurocentric view of the nation (notably as a culturally homogeneous imagined community) must be modified to fit cases like this one. Thus, the value of nationalism and nationhood as comparative concepts is questioned.     

The message of ‘The Other North Sea’

This paper explains the objectives of organising the symposium ‘The Other North Sea’. A major goal is the submission of the conclusions and content of this symposium to the North Sea Task Force, an initiative of the Second Conference on the Protection of the North Sea (London, 1987) which is responsible for preparing a Quality Status Report on the North Sea by mid-1993. The conclusions and recommendations of the symposium are summarised and presented to the North Sea Task Force in connection with the preparations for the 1993 Quality Status Report. The paper stresses the need to subdivide the North Sea into areas of ecological entity and underlines the advantages of using diatom and meiofauna assemblages as indicators for present and past environmental actors in sediment conditions. A plea is also made for the promotion of research to improve understanding of disturbance of sensory perception and behaviour as an ecologically relevant early warning signal. The major role of fisheries in inducing changes of seabird and harbour porpoise populations is highlighted.     

A coral-microbialite patch reef from the late jurassic (florigemma-Bank, Oxfordian) of NW Germany (Süntel mountains)

Summary Anin situ Oxfordian patch reef from the Süntel hills (florigemma-Bank, Korallenoolith, NW-Germany) is described. It is composed of an autochthonous reef core overlain by a ‘parautochthonous’ biostrome. The exposed reefal area amounts to about 20 m in lateral and up to 4 m in vertical direction. Nearly all major marine reefal fossil associations from the Tethyal realm are present. In the reef core two facies can be distinguished: (1)Thamnasteria dendroidea thicket facies and (2) thrombolite facies. The first facies is composed of a thin branched autochthonous coral thicket mainly constructed ofTh. dendroidea colonies with only a minor portion ofStylosmilia. Frequently, theTh. dendroidea branches laterally coalesce bridge-like forming a delicate initial framework which was subsequently reinforced by thick microbial coatings, that make up approximately 80% of the rock volume. This facies is an excellent example for microbialite binding in reefal architecture. Additionally, several generations of micromorphic and partly cryptic encrusting organisms settled on theTh. dendroidea branches and microbialite crusts. They successively overgrow each other and fill the space between the coral branches in the thicket forming a characteristic community replacement sequence. Initial colonization of theThamnasteria dendroidea took place on an oncoidic/bioclastic hardground. During this early phase of reefal development, microbialites also played an important role in stabilizing and binding the reef body. The thrombolite facies (2) occupying nearly the same volume of the reef body as facies type (1) consists of a thrombolitic microbialitic limestone which fills the interstice between the coral colonies. It shows a considerably lower faunal diversity than theTh. dendroidea facies. Numerous cavities are interspersed in the thrombolithe and are almost completely filled with dolomitized allomicrite. In contrast, microbialite and allomicrite adjacent to the reef core rarely reveal any dolomitized areas. Above the reef core, mostly toppledSolenopora jurassica thalli occur together with a few massiveIsastrea colonies forming a parautochthnous biostrome. They are inhabited by a low diverse assemblage of encrusting organisms. Microbialites are only rarely present in this biostromal unit. The patch reef is developed within a lagoonal limemud facies both separated by a sharp interface. In contrast, continuous facies transition exists between theSolenopora biostrome and adjacent deposits which are characterized by micritic to pelmicritic limestone sometimes with lenses of oncoids. Debris derived from the patch reef is only sporadically intercalated in the reef surrounding lagoonal sediments. Gastropods, bivalves, and dasycladalean algae dominate the lagoonal biota. Up-section following theSolenopora biostrome nerinean gastropods become the most abundant species amounting to a ‘Nerinea-bed’. This horizon moderately elevates above the patch reef indicating, that is arose above the surrounding sea floor forming a relief. The patch reef established on a secondary hardground probably released by a minor transgression and a nondepositional regime. It grew up on a well-illuminated sea floor only a few meters below sea level. Only a low background sedimentation rate and modest water circulation are assumed during reefal growth. These features characterize an open marine lagoon. A subsequent shallowing upwards trend caused emergence of the early lithifiedflorigemma-Bank sediments. In the following erosional phase the reef core,Solenopora biostrome and ‘Nerinea-bed’ were sharply cut. Paleokarst phenomena (karst solution of the rocks, selective leaching of the aragonitic corals) truncate the surface of theflorigemma-Bank. Released by a transgressive sea level, the paleokarst surface is densely inhabited by marine boring and encrusting organisms (oysters, serpulids). Karst cavities are filled with an oncoid-bearing bioclastic limestone with a large portion of siliciclastics. Theflorigemma-Bank is overlain by the reddish bioclastic sandstone of the ‘Zwischenfl?zregion’.     

The 1991–1992 rapid ecological assessment of Palau’s coral reefs

At the request of the Palau and US governments, a team of 30 scientists under the leadership of the Nature Conservancy completed a rapid ecological assessment (REA) of nearshore marine resources in Palau in 1992. The REA provided ecological input to Palau's ongoing master plan for economic development and identified 45 marine sites worthy of special protection. The REA relied on previous literature, 1992 aerial photography, interviews, and field observations. A combination of qualitative and quantitative techniques were used to assess stony corals, other reef invertebrates, reef and shore fishes, macroscopic algae, seagrasses, sea turtles and other marine organisms. The REA covered a variety of coral reef habitats including beaches, seagrass beds, fringing reefs, lagoons, passes, channels, reef holes, patch and pinnacle reefs, barrier reefs, atolls, submerged reefs, mangroves, and rock islands. Major stresses to Palau's coral reefs include sedimentation from soil erosion, overfishing, and damage from periodic storms and waves. Minor stresses include dredge-and fill activities, sewage pollution, anchor damage, tourism use, ship groundings, aquarium fish collecting, and minor crown-of-thorns (Acanthaster) infestations.     

The role of nodal roots in prostrate clonal herbs: ‘phalanx’ versus ‘guerrilla’

The influence of nodal rooting on branching was studied in three evolutionarily and morphologically diverse species of prostrate clonal herbs: Tradescantia fluminensis (a monocotyledonous extreme ‘phalanx’ species), Calystegia silvatica (a dicotyledonous extreme ‘guerrilla’ species) and Trifolium repens (a dicotyledonous intermediate species). In all three, branch development from axillary buds is regulated by a positive signal produced by roots together with inhibitory influences from both pre-existing branches and shoot apical buds (apical dominance). Responses to nodal roots are cumulative and increased root activity leads to more vigorous bud outgrowth. In the absence of nodal roots, a single basal root system is unable to maintain continued extension growth of the shoot. We suggest that as individual nodal roots and stem internodes are both short-lived in these nodally-rooting clonal species, the plants’ investment in them is minimal. Thus, in contrast to perennial species lacking nodal roots, individual root systems in prostrate clonal herbs are small and stems have little secondary thickening and development of long-distance transport tissues. Hence the decline in extension growth of the shoot in the absence of nodal roots could be linked to the weak development of long-distance transport tissues in their relatively thin horizontal stems and to resource sharing between primary stems and lateral branches (as suggested by the greater retardation of primary stem growth in the more profusely branched ‘phalanx’ species (Trifolium and Tradescantia) than in the weakly branched ‘guerrilla’ species, Calystegia). These findings are consistent with the view that the long-term persistence of genotypes of nodally-rooting prostrate species is dependent upon them encountering the moist conditions required to facilitate the continual development of new young nodal root systems.     

Comparison of ‘ignition’ and ‘extraction’ methods for the determination of organic phosphate in rocks and soils

Summary Ignition markedly increased the solubility in dilute acid of iron- and aluminium-bound inorganic phosphate in samples of weathered New Zealand greywacke rock. This observation supports the view that ignition methods may sometimes overestimate the total organic phosphate of soils.