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71.
Mark R. Winter Miri Morgulis Tsvia Gildor Andrew R. Cohen Smadar Ben-Tabou de-Leon 《PLoS computational biology》2021,17(2)
Biomineralization is the process by which organisms use minerals to harden their tissues and provide them with physical support. Biomineralizing cells concentrate the mineral in vesicles that they secret into a dedicated compartment where crystallization occurs. The dynamics of vesicle motion and the molecular mechanisms that control it, are not well understood. Sea urchin larval skeletogenesis provides an excellent platform for investigating the kinetics of mineral-bearing vesicles. Here we used lattice light-sheet microscopy to study the three-dimensional (3D) dynamics of calcium-bearing vesicles in the cells of normal sea urchin embryos and of embryos where skeletogenesis is blocked through the inhibition of Vascular Endothelial Growth Factor Receptor (VEGFR). We developed computational tools for displaying 3D-volumetric movies and for automatically quantifying vesicle dynamics. Our findings imply that calcium vesicles perform an active diffusion motion in both, calcifying (skeletogenic) and non-calcifying (ectodermal) cells of the embryo. The diffusion coefficient and vesicle speed are larger in the mesenchymal skeletogenic cells compared to the epithelial ectodermal cells. These differences are possibly due to the distinct mechanical properties of the two tissues, demonstrated by the enhanced f-actin accumulation and myosinII activity in the ectodermal cells compared to the skeletogenic cells. Vesicle motion is not directed toward the biomineralization compartment, but the vesicles slow down when they approach it, and probably bind for mineral deposition. VEGFR inhibition leads to an increase of vesicle volume but hardly changes vesicle kinetics and doesn’t affect f-actin accumulation and myosinII activity. Thus, calcium vesicles perform an active diffusion motion in the cells of the sea urchin embryo, with diffusion length and speed that inversely correlate with the strength of the actomyosin network. Overall, our studies provide an unprecedented view of calcium vesicle 3D-dynamics and point toward cytoskeleton remodeling as an important effector of the motion of mineral-bearing vesicles. 相似文献
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Accurate temporal control of gene expression is essential for normal development and must be robust to natural genetic and environmental variation. Studying gene expression variation within and between related species can delineate the level of expression variability that development can tolerate. Here we exploit the comprehensive model of sea urchin gene regulatory networks and generate high-density expression profiles of key regulatory genes of the Mediterranean sea urchin, Paracentrotus lividus (Pl). The high resolution of our studies reveals highly reproducible gene initiation times that have lower variation than those of maximal mRNA levels between different individuals of the same species. This observation supports a threshold behavior of gene activation that is less sensitive to input concentrations. We then compare Mediterranean sea urchin gene expression profiles to those of its Pacific Ocean relative, Strongylocentrotus purpuratus (Sp). These species shared a common ancestor about 40 million years ago and show highly similar embryonic morphologies. Our comparative analyses of five regulatory circuits operating in different embryonic territories reveal a high conservation of the temporal order of gene activation but also some cases of divergence. A linear ratio of 1.3-fold between gene initiation times in Pl and Sp is partially explained by scaling of the developmental rates with temperature. Scaling the developmental rates according to the estimated Sp-Pl ratio and normalizing the expression levels reveals a striking conservation of relative dynamics of gene expression between the species. Overall, our findings demonstrate the ability of biological developmental systems to tightly control the timing of gene activation and relative dynamics and overcome expression noise induced by genetic variation and growth conditions. 相似文献
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Association mapping of leaf rust response in durum wheat 总被引:1,自引:0,他引:1
Marco Maccaferri Maria C. Sanguineti Paola Mantovani Andrea Demontis Andrea Massi Karim Ammar James A. Kolmer Jerzy H. Czembor Smadar Ezrati Roberto Tuberosa 《Molecular breeding : new strategies in plant improvement》2010,26(2):189-228
Resistance to leaf rust (Puccinia triticina Eriks.) is a main objective for durum wheat (Triticum durum Desf.) breeding. Association mapping on germplasm collections is now being used as an additional approach for the discovery
and validation of major genes/QTLs. In this study, a collection of 164 elite durum wheat accessions suitable for association
mapping has been tested for leaf rust response at the seedling stage and under field conditions (adult plant stage). Seedling
tests were carried out with 25 selected isolates from durum wheat, bread wheat and triticale, while field experiments were
carried out in artificially inoculated plots in Italy and in Mexico. The collection has been profiled with 225 simple sequence
repeat (SSR) loci of known map position and a PCR assay targeting Ppd-A1. Associations showing highly consistent experiment-wise significances across leaf rust isolates and field trials were mainly
detected for the 7BL distal chromosome (chr.) region (harbouring Lr14 from cultivar Llareta INIA and QLr.ubo-7B.2 from cultivar Creso) and for two chr. regions located in chrs. 2A and 2B. Additionally, isolate-specific associations and/or
associations with smaller effects in the field trials were identified in most of the chromosomes. The chr. 7BL distal region
was investigated in detail through haplotyping with 15 SSR markers, revealing that the Creso and Llareta INIA alleles are
identical by descent at 6 adjacent SSR loci in the most distal 7BL region spanning 8 cM. Association mapping allowed us to
further refine the map location of the Lr14/QLr.ubo-7B.2 resistance gene to the most distal region of the linkage group, tagged by Xcfa2257.2, Xgwm344.2 and Xwmc10. The resistant haplotype is present in a number of accessions (ca. 15% of the accessions included in the collection) from
the Italian, CIMMYT and ICARDA breeding programmes. Therefore, this chr. 7BL region can be considered as the most important
source of resistance to leaf rust currently exploited by durum breeders in the Mediterranean areas. Furthermore, the field
trials at the adult plant stage allowed us to identify marker associations (e.g. chrs. 2BL and 3BS, proximal regions; chr.
7BS, distal region) which suggest the presence of minor QTLs for slow-rusting resistance. 相似文献
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Anna Aronovich Dalit Tchorsh Elias Shezen Chava Rosen Yael Klionsky Sivan Cohen Orna Tal Uri Martinowitz Helena Katchman Smadar Eventov-Friedman Ninette Amariglio Jasmine Jacob-Hirsch Gideon Rechavi Yair Reisner 《PloS one》2009,4(12)
Very little is known about the mechanisms that contribute to organ size differences between species. In the present study, we used a mouse model of embryonic pig tissue implantation to define the role of host Factor VIII in controlling the final size attained by the implant. We show here that pig embryonic spleen, pancreas, and liver all grow to an increased size in mice that are deficient in the Factor VIII clotting cascade. Similar results were obtained using the transplantation model after treatment with the low molecular weight heparin derivative Clexane which markedly enhanced transplant size. Likewise, enhanced size was found upon treatment with the direct thrombin inhibitor Dabigatran, suggesting that organ size regulation might be mediated by thrombin, downstream of Factor VIII. Considering that thrombin was shown to mediate various functions unrelated to blood clotting, either directly by cleavage of protease-activated receptors (PARs) or indirectly by cleaving osteopontin (OPN) on stroma cells, the role of PAR1 and PAR4 antagonists as well as treatment with cleaved form of OPN (tcOPN) were tested. While the former was not found to have an impact on overgrowth of embryonic pig spleen implants, marked reduction of size was noted upon treatment with the (tcOPN). Collectively, our surprising set of observations suggests that factors of the coagulation cascade have a novel role in organ size control. 相似文献
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Parental investment strategies can be fixed or flexible. A fixed strategy predicts making all offspring a single ‘optimal’
size. Dynamic models predict flexible strategies with more than one optimal size of offspring. Patterns in the distribution
of offspring sizes may thus reveal the investment strategy. Static strategies should produce normal distributions. Dynamic
strategies should often result in non-normal distributions. Furthermore, variance in morphological traits should be positively
correlated with the length of developmental time the traits are exposed to environmental influences. Finally, the type of
deviation from normality (i.e., skewed left or right, or platykurtic) should be correlated with the average offspring size.
To test the latter prediction, we used simulations to detect significant departures from normality and categorize distribution
types. Data from three species of ants strongly support the predicted patterns for dynamic parental investment. Offspring
size distributions are often significantly non-normal. Traits fixed earlier in development, such as head width, are less variable
than final body weight. The type of distribution observed correlates with mean female dry weight. The overall support for
a dynamic parental investment model has implications for life history theory. Predicted conflicts over parental effort, sex
investment ratios, and reproductive skew in cooperative breeders follow from assumptions of static parental investment strategies
and omnipresent resource limitations. By contrast, with flexible investment strategies such conflicts can be either absent
or maladaptive.
Electronic Supplementary Material Supplementary material is available for this article at 相似文献
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Ronit Lavi Michael Sinyakov Amram Samuni Smadar Shatz Harry Friedmann Asher Shainberg 《Free radical research》2013,47(9):893-902
Low-energy visible light (LEVL) has previously been found to modulate various processes in different biological systems. One explanation for the stimulatory effect of LEVL is light-induced reactive oxygen species formation. In the present study, both sperm and skin cells were illuminated with LEVL and were found to generate singlet oxygen (1O2). The detection of 1O2 was performed using a trapping probe, 2,2,6,6-tetramethyl-4-piperidone, coupled with electron paramagnetic resonance spectroscopy. In addition, we have shown that, together with 1O2 generation, LEVL illumination increases the reductive capacity of the cells, which explains the difficulties encountered in 1O2 detection. The potential of visible light to change the cellular redox state may explain the recently observed biostimulative effects exerted by LEVL. 相似文献
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