Visualisation of Leishmania donovani Fluorescent Hybrids during Early Stage Development in the Sand Fly Vector

hybrids were produced by co-infecting sand flies with two strains carrying different drug resistance markers. However, the location and timing of hybridisation events in sand flies has not been described. strains carrying hygromycin or neomycin resistance genes and red or green fluorescent markers. Fed females were dissected at different times post bloodmeal (PBM) and examined by fluorescent microscopy or fluorescent activated cell sorting (FACS) followed by confocal microscopy. In mixed infections strains LEM3804 and Gebre-1 reached the cardia and stomodeal valves more rapidly than strains LEM4265 and LV9. Hybrids unequivocally expressing both red and green fluorescence were seen in single flies of both vectors tested, co-infected with LEM4265 and Gebre-1. The hybrids were present as short (procyclic) promastigotes 2 days PBM in the semi-digested blood in the endoperitrophic space. Recovery of a clearly co-expressing hybrid was also achieved by FACS. However, hybrids could not sustain growth in vitro. has profound epidemiological significance, because it facilitates the emergence and spread of new phenotypic traits

A Rho Scaffold Integrates the Secretory System with Feedback Mechanisms in Regulation of Auxin Distribution

In plants, auxin distribution and tissue patterning are coordinated via a feedback loop involving the auxin-regulated cell polarity factor ICR1 and the secretory machinery

The bHLH transcription factor SPATULA enables cytokinin signaling, and both activate auxin biosynthesis and transport genes at the medial domain of the gynoecium

[EN] Fruits and seeds are the major food source on earth. Both derive from the gynoecium and, therefore, it is crucial to understand the mechanisms that guide the development of this organ of angiosperm species. In Arabidopsis, the gynoecium is composed of two congenitally fused carpels, where two domains: medial and lateral, can be distinguished. The medial domain includes the carpel margin meristem (CMM) that is key for the production of the internal tissues involved in fertilization, such as septum, ovules, and transmitting tract. Interestingly, the medial domain shows a high cytokinin signaling output, in contrast to the lateral domain, where it is hardly detected. While it is known that cytokinin provides meristematic properties, understanding on the mechanisms that underlie the cytokinin signaling pattern in the young gynoecium is lacking. Moreover, in other tissues, the cytokinin pathway is often connected to the auxin pathway, but we also lack knowledge about these connections in the young gynoecium. Our results reveal that cytokinin signaling, that can provide meristematic properties required for CMM activity and growth, is enabled by the transcription factor SPATULA (SPT) in the medial domain. Meanwhile, cytokinin signaling is confined to the medial domain by the cytokinin response repressor ARABIDOPSIS HISTIDINE PHOSPHOTRANSFERASE 6 (AHP6), and perhaps by ARR16 (a type-A ARR) as well, both present in the lateral domains (presumptive valves) of the developing gynoecia. Moreover, SPT and cytokinin, probably together, promote the expression of the auxin biosynthetic gene TRYPTOPHAN AMINOTRANSFERASE OF ARABIDOPSIS 1 (TAA1) and the gene encoding the auxin efflux transporter PIN-FORMED 3 (PIN3), likely creating auxin drainage important for gynoecium growth. This study provides novel insights in the spatiotemporal determination of the cytokinin signaling pattern and its connection to the auxin pathway in the young gynoecium.IRO, VMZM, HHU and PLS were supported by the Mexican National Council of Science and Technology (CONACyT) with a PhD fellowship (210085, 210100, 243380 and 219883, respectively). Work in the SDF laboratory was financed by the CONACyT grants CB-2012-177739, FC-2015-2/1061, and INFR-2015-253504, and NMM by the CONACyT grant CB-2011-165986. SDF, CF and LC acknowledge the support of the European Union FP7-PEOPLE-2009-IRSES project EVOCODE (grant no. 247587) and H2020-MSCARISE-2015 project ExpoSEED (grant no. 691109). SDF also acknowledges the Marine Biological Laboratory (MBL) in Woods Hole for a scholarship for the Gene Regulatory Networks for Development Course 2015 (GERN2015). IE acknowledges the International European Fellowship-METMADS project and the Universita degli Studi di Milano (RTD-A; 2016). Research in the laboratory of MFY was funded by NSF (grant IOS-1121055), NIH (grant 1R01GM112976-01A1) and the Paul D. Saltman Endowed Chair in Science Education (MFY). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Reyes Olalde, J.; Zuñiga, V.; Serwatowska, J.; Chávez Montes, R.; Lozano-Sotomayor, P.; Herrera-Ubaldo, H.; Gonzalez Aguilera, K.... (2017). The bHLH transcription factor SPATULA enables cytokinin signaling, and both activate auxin biosynthesis and transport genes at the medial domain of the gynoecium. PLoS Genetics. 13(4):1-31. https://doi.org/10.1371/journal.pgen.1006726S131134Reyes-Olalde, J. I., Zuñiga-Mayo, V. M., Chávez Montes, R. A., Marsch-Martínez, N., & de Folter, S. (2013). Inside the gynoecium: at the carpel margin. Trends in Plant Science, 18(11), 644-655. doi:10.1016/j.tplants.2013.08.002Alvarez-Buylla, E. 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The impact of weather conditions on dynamics of Hylocomium splendens annual increment and net production in forest communities of forest-steppe zone in Khakassia

Dynamics of annual increments of green moss Hylocomium splendens (Hedw.) Schimp. in B.S.G. in the Khakassia forest-steppe zone has been studied. The values of the moss linear and phytomass increments were investigated in different habitats for 6 years. The aboveground annual production of the H. splendens in phytocenosis was estimated. Linear increments of the H. splendens growing under the tree canopy and opening between trees were not significantly different. Phytomass increments under the tree canopy are significantly higher than in the openings between trees. The density of moss mats, proportion between leaves and stems were calculated. It was revealed that climatic factors have a different degree and duration influence on the moss increments in different habitats. Linear increments of H. splendens in different habitats synchronously respond to weather factor changes. The air temperature was the most important at the beginning and the end of the vegetation period; the amount of precipitation was more important in the middle of the growth period. Phytomass increments of H. splendens in different habitats respond differently to influence of weather conditions. Phytomass increments under the tree canopy are not sensitive to air temperature, and more sensitive to precipitations in the middle of growth period than one of opening between trees. The specificity of the climatic factors’ influence on the biomass growth depends on habitat conditions

Variability of the tree-rings structure of Gmelin’s larch at northern tree line (peninsula of Taymyr)

The study of tree-ring cell structure changes as the result of tree adaptation to varying environmental conditions becomes increasingly important to predict future vegetation shifts under projected climate changes. The estimate of intrapopulation annual variability of wood anatomy characteristics is particularly informative. It helps to divide the contribution of different ecological factors to total features dispersion. In this work, a comparative analysis of individual and climatic variability of tree ring structure characteristics of Gmelin’s larch Larix gmelinii (Rupr.) growth within northernmost forest was carried out. The trees from forest-tundra boundary has greater radial growth intensity, forms the bigger conductive zone in rings with wider mean lumen area in comparison with trees from closed forest. This result can be explained by adaptive features and height ecological xylem plasticity of larch. The tree rings structure of larch from boundary with tundra is determined by largely current weather conditions. Is because these ones evince high adaptive plasticity on the level of xylem structure. The xylem reflects joint changes of climate factors and local ecological conditions. The trees from closed forest are characterized by larger individual variability. The local conditions in oldest forest (for example, bad hydrothermal soil conditions) inhibit the radial growth and sensitivity to environmental factors. In this case, the trees on individual level are tended to save the normal functioning of water-transport system. The significant differences in ratio individual to climate variability of tree ring structure characteristics can be caused by the different in the level of ecological habitat heterogeneity or the different in the level genetic within-population heterogeneity

BASE-TO-TIP RADIAL GROWTH AND ANATOMICAL STRUCTURE OF STAG-HEADED LARCH TREES ON PERMAFROST: CAUSES AND EMPIRICAL PRIORITIES

In the northern larch forests of Siberia growing on permafrost soils the top drying phenomenon is widely spread. Its causes remain unclear. We suggest that an acute water deficiency in continuous climate warming could trigger the process of top drying in larch trees. In order to validate this hypothesis, dendroclimatic and wood anatomy approaches were used. A comparative analysis of the base-to-tip radial growth dynamics and wood anatomical structure in healthy and stag-headed Gmelin larch trees (Larix gmelinii (Rupr.) Rupr.), growing in the even-aged forest on the permafrost soil of the north-facing slope (64°19′23″ N, 100°13′28″ E) was made. The tree ring width, as well as lumen radial size and wall thickness of tracheids were measured at 1/4, 1/2 and 3/4 of the stem height and 20-25 cm below the top, in 15 healthy and 12 stag-headed trees. Decreasing trends of the aforementioned parameters from tree base to top were found in all the trees, which was especially evident in the stag-headed trees. Wood anatomical structure in the upper part of the stag-headed stems underwent modifications over the last 20 years: there occurred tree ring boundaries became indistinct, disturbance of the tracheid rows, thinning of early- and latewood tracheid walls. Using sliding climate correlations with the indexed radial increments it was found that the trees on the north-facing slope could suffer from water deficiency from the end of May until the late June. The presence of both stag-headed and neighboring healthy trees on the north-facing slope can be explained by high variability of soil hydrothermal growth conditions due to very high spatial mosaic moss-lichen cover, common to the north-facing slopes. The trees, growing in these unfavorable local hydrothermal conditions under continuous climate warming could experience an extremely acute water deficiency, leading to top drying out