Evolution of Plant Na+-P-Type ATPases: From Saline Environments to Land Colonization

Soil salinity is one of the major factors obstructing the growth and development of agricultural crops. Eukaryotes have two main transport systems involved in active Na+ removal: cation/H+ antiporters and Na+-P-type ATPases. Key transport proteins, Na+/K+-P-ATPases, are widely distributed among the different taxa families of pumps which are responsible for keeping cytosolic Na+ concentrations below toxic levels. Na+/K+-P-ATPases are considered to be absent in flowering plants. The data presented here are a complete inventory of P-type Na+/K+-P-ATPases in the major branches of the plant kingdom. We also attempt to elucidate the evolution of these important membrane pumps in plants in comparison with other organisms. We were able to observe the gradual replacement of the Na+-binding site to the Ca2+-binding site, starting with cyanobacteria and moving to modern land plants. Our results show that the α-subunit likely evolved from one common ancestor to bacteria, fungi, plants, and mammals, whereas the β-subunit did not evolve in green algae. In conclusion, our results strongly suggest the significant differences in the domain architecture and subunit composition of plant Na+/K+-P-ATPases depending on plant taxa and the salinity of the environment. The obtained data clarified and broadened the current views on the evolution of Na+/K+-P-ATPases. The results of this work would be helpful for further research on P-type ATPase functionality and physiological roles.

A new Devonian euthycarcinoid reveals the use of different respiratory strategies during the marine-to-terrestrial transition in the myriapod lineage

Myriapods were, together with arachnids, the earliest animals to occupy terrestrial ecosystems, by at least the Silurian. The origin of myriapods and their land colonization have long remained puzzling until euthycarcinoids, an extinct group of aquatic arthropods considered amphibious, were shown to be stem-group myriapods, extending the lineage to the Cambrian and evidencing a marine-to-terrestrial transition. Although possible respiratory structures comparable to the air-breathing tracheal system of myriapods are visible in several euthycarcinoids, little is known about the mechanism by which they respired. Here, we describe a new euthycarcinoid from Upper Devonian alluvio-lagoonal deposits of Belgium. Synchrotron-based elemental X-ray analyses were used to extract all available information from the only known specimen. Sulfur X-ray fluorescence (XRF) mapping and spectroscopy unveil sulfate evaporation stains, spread over the entire slab, suggestive of a very shallow-water to the terrestrial environment prior to burial consistent with an amphibious lifestyle. Trace metal XRF mapping reveals a pair of ventral spherical cavities or chambers on the second post-abdominal segment that do not compare to any known feature in aquatic arthropods, but might well play a part in air-breathing. Our data provide additional support for amphibious lifestyle in euthycarcinoids and show that different respiratory strategies were used during the marine-to-terrestrial transition in the myriapod lineage.

Requirements for multispectral remote sensing data used for the detection of arable land colonization by tree and shrubbery vegetation

We discuss requirements for the multispectral remote sensing (RS) data utilized in the author's technique for estimating plant species concentration to detect arable land colonization by tree and shrubbery vegetation. The study is carried out using available high-resolution remote sensing data of two arable land plots. The paper considers the influence of resolution, combinations of spectral channels of RS data, as well as the season RS data is acquired on the quality of identification of elementary vegetation classes that form the basis of the plant community – a fallow land. A fallow land represents a piece of arable land that has not been cultivated for a long time. The study was conducted using a technology that is based on image superpixel segmentation. We found out that for determining tree and shrub vegetation, it is preferable to use RS data acquired in autumn, namely, in late September. The combination of red and blue spectral channels turned out to be the best for the analysis of tree-shrub vegetation against the background of grassy plant communities, and the presence of a near-infrared channel is necessary to range the various grassy plant communities in different classes. RS data with a spatial resolution of 2.5 m can be used to define tree-shrub plant communities with a high closeness of crowns (90 % or more), but cannot be used to classify isolated trees. Trees and shrubs (with a height of 8 m) can be classified in images with a spatial resolution of 0.8 m. An increase in spatial resolution does not improve the quality of the classification. The highest accuracies achieved for the land areas studied are 90 % and 83 %. Therefore, the suggested technology can be used in arable land expertise.

Transformaciones territoriales en la Amazonía: indígenas, campesinos, fronteras y colonización/ Territorial transformations in the Amazon: indigenous, peasants, borders and colonization

El artículo hace un balance sobre los aspectos principales que se deducen del proceso de expansión de la frontera agrícola en la Amazonía ecuatoriana con énfasis en el nororiente en donde se desarrollan actividades de explotación petrolera desde la década de 1960. Tal proceso, al igual que la colonización, junto con el ingreso de las empresas agroindustriales y madereras tuvo como trasfondo el discurso oficial de la “Amazonía como territorio vacío”. Plantea además, el papel que ha jugado la reproducción de las economías campesinas en la expansión del capital y, consecuentemente, en la integración de tierras al mercado interno y al Estado nacional. En el artículo se advierte que gracias a los flujos de colonización y sus efectos acumulados sobre la dinámica de la población está cobrando fuerza la “urbanización” de la Amazonía. En este contexto, los pueblos indígenas, así como los asentamientos poblacionales (afectados por la contaminación ambiental petrolera) permanecen como actores subordinados y excluidos de los frutos del “desarrollo”. Por último, el trabajo presenta de manera breve los artículos que forman parte del No. 12 de la revista EUTOPÍA de FLACSO, sede Ecuador. Abstract This article analyses the main issues related with the expansion of the agricultural frontier in the Ecuadorian rainforest, emphasizing oil extraction impacts in the northeast region since 1960. Oil extraction, land colonization, the expansion of agro-processing and wood industries influenced the discourse of “Empty Territory Rainforest”. The article also points out the role of indigenous and peasant economies in capital expansion, as well as the integration of their land to the inner market and State ownership. Thereafter, colonization flows and their cumulative effects over the population dynamics is promoting “urbanization” of the Ecuadorian rainforest. In this context, the indigenous people, as well as human settlements, both affected by the environmental impacts of oil industry, remain as agents subordinated to and excluded from “development”. Lastly, the articles in Journal “EUTOPIA”, No. 12 edition, of FLACSO-ECUADOR are introduced.

The Identification of Phytohormone Receptor Homologs in Early Diverging Fungi Suggests a Role for Plant Sensing in Land Colonization by Fungi

ABSTRACT Histidine kinases (HKs) are among the most prominent sensing proteins studied in the kingdom Fungi. Their distribution and biological functions in early diverging fungi (EDF), however, remain elusive. We have taken advantage of recent genomic resources to elucidate whether relationships between the occurrence of specific HKs in some EDF and their respective habitat/lifestyle could be established. This led to the unexpected discovery of fungal HKs that share a high degree of similarity with receptors for plant hormones (ethylene and cytokinin). Importantly, these phytohormone receptor homologs are found not only in EDF that behave as plant root symbionts or endophytes but also in EDF species that colonize decaying plant material. We hypothesize that these particular sensing proteins promoted the interaction of EDF with plants, leading to the conquest of land by these ancestral fungi.