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Leiden, Netherlands

Badek B.,Research Institute of Horticulture | Romanowska-Duda Z.,University of Lodz | Grzesik M.,Research Institute of Horticulture | Van Duijn B.,Sylvius Laboratory | Van Duijn B.,Leiden University
Journal of Horticultural Research | Year: 2014

The correlation between the sowing value of primed China aster seeds represented by germination percentage (GP), mean germination time (MGT), germination uniformity expressed as the time between 25% and 75% of germinated seeds (T75-25) and some selected physiological characteristics - total activity of dehydrogenases (TAD), activity of catalase (AC), activity of cell cycle (ACC) and electrolyte leakage (EL) has been analysed in order to find useful markers of biological quality of seeds. To achieve this objective, analyses of effects of three methods of water supply to seeds viz. - hydroconditioning by soaking in excessive amount of water (M1), hydroconditioning by soaking in limited amount of water (M2) or hydroconditioning by contact with solid carrier of water - matriconditioning (M3), three levels (30.0, 35.0 and 40.0%) of seed moisture content (m.c.) and three incubation periods (1, 8 and 10 days) during priming and hence their influence on germination properties (GP, MGT, T75-25) in comparison with TAD, AC, ACC and EL were determined. The results showed that MGT and T75-25 were correlated with TAD, AC, ACC and EL, irrespective of their priming method and sowing value. Therefore, all the investigated physiological/biochemical parameters of seed quality can be used as markers of germinability and sowing value reached by primed China aster seeds. The results also proved that, irrespective of the water supply method applied, hydration of seeds up to 37.5% m.c., and their incubation at 20 °C for 8 days, followed by drying to their initial moisture content, increased to the greatest extent the speed and uniformity of seed germination and their physiological activity. Source

Durston A.J.,Sylvius Laboratory
Current Genomics | Year: 2013

This article was to have been written by Kees Weijer, an outstanding pioneer in Dictyostelium research. It was (and is) to celebrate J.T. Bonner's and Weijer's contributions to the field and those of the other great pioneers. Unfortunately, Weijer was unable to write his article, due to ill health and since I have some knowledge of this field, I took it over. The article summarises some main results and ideas in Dictyostelium research and their relevance for development of more advanced organisms. ©2013 Bentham Science Publishers. Source

Zhang S.,Leiden University | de Boer A.H.,VU University Amsterdam | van Duijn B.,Leiden University | van Duijn B.,Sylvius Laboratory
Journal of Plant Physiology | Year: 2016

The plant hormone auxin has been widely studied with regard to synthesis, transport, signaling and functions among the land plants while there is still a lack of knowledge about the possible role for auxin regulation mechanisms in algae with "plant-like" structures. Here we use the alga Chara corallina as a model to study aspects of auxin signaling. In this respect we measured auxin on membrane potential changes and different ion fluxes (K+, H+) through the plasma membrane. Results showed that auxin, mainly IAA, could hyperpolarize the membrane potential of C. corallina internodal cells. Ion flux measurements showed that the auxin-induced membrane potential change may be based on the change of K+ permeability and/or channel activity rather than through the activation of proton pumps as known in land plants. © 2016 Elsevier GmbH. Source

In der Rieden P.M.J.,Studiekring | Jansen H.J.,Sylvius Laboratory | Durston A.J.,Sylvius Laboratory
PLoS ONE | Year: 2011

Hox transcription factors provide positional information during patterning of the anteroposterior axis. Hox transcription factors can co-operatively bind with PBC-class co-factors, enhancing specificity and affinity for their appropriate binding sites. The nuclear localisation of these co-factors is regulated by the Meis-class of homeodomain proteins. During development of the zebrafish hindbrain, Meis3 has previously been shown to synergise with Hoxb1 in the autoregulation of Hoxb1. In Xenopus XMeis3 posteriorises the embryo upon ectopic expression. Recently, an early temporally collinear expression sequence of Hox genes was detected in Xenopus gastrula mesoderm (see intro. P3). There is evidence that this sequence sets up the embryo's later axial Hox expression pattern by time-space translation. We investigated whether XMeis3 is involved in regulation of this early mesodermal Hox gene expression. Here, we present evidence that XMeis3 is necessary for expression of Hoxd1, Hoxb4 and Hoxc6 in mesoderm during gastrulation. In addition, we show that XMeis3 function is necessary for the progression of gastrulation. Finally, we present evidence for synergy between XMeis3 and Hoxd1 in Hoxd1 autoregulation in mesoderm during gastrulation. © 2011 Durston et al. Source

Durston A.J.,Sylvius Laboratory | Jansen H.J.,Sylvius Laboratory | Wacker S.A.,University of Ulm
Genomics | Year: 2010

Here, we review a recently discovered developmental mechanism. Anterior-posterior positional information for the vertebrate trunk is generated by sequential interactions between a timer in the early non-organiser mesoderm and the Spemann organiser. The timer is characterised by temporally colinear activation of a series of Hox genes in the early ventral and lateral mesoderm (i.e., the non-organiser mesoderm) of the Xenopus gastrula. This early Hox gene expression is transient, unless it is stabilised by signals from the Spemann organiser. The non-organiser mesoderm (NOM) and the Spemann organiser undergo timed interactions during gastrulation which lead to the formation of an anterior-posterior axis and stable Hox gene expression. When separated from each other, neither non-organiser mesoderm nor the Spemann organiser is able to induce anterior-posterior pattern formation of the trunk. We present a model describing that NOM acquires transiently stable hox codes and spatial colinearity after involution into the gastrula and that convergence and extension then continually bring new cells from the NOM within the range of organiser signals that cause transfer of the mesodermal pattern to a stable pattern in neurectoderm and thereby create patterned axial structures. In doing so, the age of the non-organiser mesoderm, but not the age of the organiser, defines positional values along the anterior-posterior axis. We postulate that the temporal information from the non-organiser mesoderm is linked to mesodermal Hox expression. The role of the organiser was investigated further and this turns out to be only the induction of neural tissue. Apparently, development of a stable axial hox pattern requires neural hox patterning. © 2009 Elsevier Inc. Source

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