Mechanotransduction in root gravity sensing cells

The analysis of the dose-response curve of the gravitropic reaction of lentil seedling roots has shown that these organs are more sensitive when they have been grown in microgravity than when they have been grown on a 1 g centrifuge in space before gravistimulation. This difference of gravisensitivity is not due to the volume or the density of starch grains of statoliths, which are about the same in both conditions (1 g or microgravity). However, the distribution of statoliths within the statocyte may be responsible for this differential sensitivity, since the dispersion of these organelles is greater in microgravity than in 1 g. When lentil roots grown in microgravity or in 1 g are stimulated at 0.93 g for 22 min, the amyloplasts sediment following two different trajectories. They move from the proximal half of the statocytes toward the lower longitudinal wall in the microgravity grown sample and from the distal half toward the longitudinal wall in the 1 g grown sample. At the end of the stimulation, they reach a similar position within the statocytes. If the roots of both samples are left in microgravity for 3 h, the amyloplasts move toward the cell centre in a direction that makes an average angle of 40 degrees with respect to the lower longitudinal wall. The actin filaments, which are responsible for this movement, may have an overall orientation of 40 degrees with respect to this wall. Thus, when roots grown in microgravity are stimulated on the minicentrifuge the amyloplasts slide on the actin filaments, whereas they move perpendicular to them in 1 g grown roots. Our results suggest that greater sensitivity of seedling roots grown in microgravity should be due to greater dispersion of statoliths, to better contacts between statoliths and the actin network and to greater number of activated mechanoreceptors. One can hypothesize that stretch activated ion channels (SACs) located in the plasma membrane are responsible for the transduction of gravistimulus. These SACs may be connected together by elements of the cytoskeleton lining the plasma membrane and to the actin filaments. They could be stimulated by the action of statoliths on the actin network and/or on these elements of the cytoskeleton which link the mechanoreceptors (SACs).     

Invertebrate neuropeptide hormones

The development of a long-term research program on the neurosecretory hormones of arthropods is described. The purification and full characterization of the first invertebrate neurohormones, the red pigment-concentrating hormone (RPCH) and the distal retinal pigment hormone (DRPH) demonstrated that they are peptides, an octapeptide and an octadecapeptide, respectively. Physiological function studies with the pure hormones and their synthetic preparations showed that the RPCH acts as a general pigment-concentrating hormone (PCH), and that the DRPH, in addition to its light-adaptive function, also constitutes a general pigment-dispersing hormone (PDH). In the regulation of the color-adaptation of the animals, the two hormones act as antagonists. The chromatophorotropic activities are widely distributed within the arthropod neuroendocrine systems. Purification of the pigment-concentrating activities from the locust corpora cardiaca lead to the isolation and characterization of the first insect neurohormones, the adipokinetic hormones (AKH I and AKH II). These two hormones, AKH I being a decapeptide and AKH II being an octapeptide, are close structural analogs to the crustacean PCH, demonstrating a common evolution of arthropod neurohormones. The hormones of this PCH-family all cross-react, but structure-function studies of the hormones show that quite different parts of their structure are involved in their binding to the various receptors.     

Invertebrate diversity on

Despite the global importance of New Zealands invertebrates, relatively little is known about them and their relationships with plants and plant communities in native habitats. Invertebrate diversity was examined by beating randomly chosen shrubs of the species Olearia bullata (Asteraceae) and Coprosma propinqua(Rubiaceae). Invertebrate taxon richness was assessed initially using morphospecies, which were identified subsequently by expert taxonomists. Though the taxon richness of invertebrates recorded from O. bullata was not significantly higher than that on C. propinqua (except for the orders Diptera and Hemiptera), there was a clear indication that O. bullata hosts a higher diversity of invertebrates. Mean number of taxa per shrub for O. bullata was higher in all cases (except Coleoptera), and so was the maximum number of taxa per shrub. Overall, O. bullata yielded 115 invertebrate taxa compared with 93 for C. propinqua. Moreover, 50 invertebrate taxa were restricted to O. bullata compared with 28 for C. propinqua. Since at least ten species of Oleariaare threatened or uncommon, this could be cause for concern with respect to the maintenance of invertebrate diversity. Therefore, sites where Oleariaspecies are still present are likely to be of significance for invertebrate conservation.     

A Thesaurus for Soil Invertebrate Trait-Based Approaches

Soil invertebrates are known to be much involved in soil behaviour and therefore in the provision of ecosystem services. Functional trait-based approaches are methodologies which can be used to understand soil invertebrates’ responses to their environment. They (i) improve the predictions and (ii) are less dependent on space and time. The way traits have been used recently has led to misunderstandings in the integration and interpretation of data. Trait semantics are especially concerned. The aim of this paper is to propose a thesaurus for soil invertebrate trait-based approaches. T-SITA, an Internet platform, is the first initiative to deal with the semantics of traits and ecological preferences for soil invertebrates. It reflects the agreement of a scientific expert community to fix semantic properties (e.g. definition) of approximately 100 traits and ecological preferences. In addition, T-SITA has been successfully linked with a fully operational database of soil invertebrate traits. Such a link enhances data integration and improves the scientific integrity of data.     

History of the Society for Invertebrate Pathology

Scientists studying diseases of invertebrates in the USA, Europe, and Asia began to meet at international congresses in the 1950s and early 1960s, and soon recognized that they needed both a society and a journal where their common interests could be discussed and their findings presented. Edward A. Steinhaus played a major role in bringing together scientists from across the globe with common interests in these diseases. As a consequence, the Journal of Invertebrate Pathology (then Journal of Insect Pathology) was initiated in 1959 and Steinhaus became its first editor. Along with Albert Sparks he organized a meeting at Seattle, Washington in 1967 that led to the founding of the Society for Invertebrate Pathology with Steinhaus as its first President. The Society held its first meeting at Ohio State University in 1968, and has continued to meet annually. The Society has instituted a Founder's Lecture series, graduate student awards, and Divisions of Microbial Control, Microsporidia, Bacteriology, Fungi, Viruses, and Nematodes. Members enjoy several social functions at meetings as well as symposia, submitted papers, and poster sessions. The Society for Invertebrate Pathology is a truly international organization which to date has held meetings in 13 countries and 14 US states, usually attended by members from at least 20 countries.