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61.
J. G. Dubrovsky A. Soukup S. Napsucialy-Mendivil Z. Jekni? M. G. Ivanchenko 《Annals of botany》2009,103(5):807-817
Background and Aims
Lateral root initiation is an essential and continuous process in the formation of root systems; therefore, its quantitative analysis is indispensable. In this study a new measure of lateral root initiation is proposed and analysed, namely the lateral root initiation index (ILRI), which defines how many lateral roots and/or primordia are formed along a parent-root portion corresponding to 100 cortical cells in a file.Methods
For data collection, a commonly used root clearing procedure was employed, and a new simple root clearing procedure is also proposed. The ILRI was determined as 100dl, where d is the density of lateral root initiation events (number mm−1) and l is the average fully elongated cortical cell length (mm).Key Results
Analyses of different Arabidopsis thaliana genotypes and of a crop plant, tomato (Solanum lycopersicum), showed that ILRI is a more precise parameter than others commonly used as it normalizes root growth for variations in cell length. Lateral root primordium density varied in the A. thaliana accessions Col, Ler, Ws, and C24; however, in all accessions except Ws, ILRI was similar under the same growth conditions. The nitrogen/carbon ratio in the growth medium did not change the lateral root primordium density but did affect ILRI. The ILRI was also modified in a number of auxin-related mutants, revealing new root branching phenotypes in some of these mutants. The rate of lateral root initiation increased with Arabidopsis seedling age; however, ILRI was not changed in plants between 8 and 14 d post-germination.Conclusions
The ILRI allows for a more precise comparison of lateral root initiation under different growth conditions, treatments, genotypes and plant species than other comparable methods.Key words: Arabidopsis thaliana, auxin, lateral root density, lateral root initiation index, mutant phenotype, pericycle, root architecture, root branching, root primordium, Solanum lycopersicum 相似文献62.
Wondmikun Y Soukup T Asmussen G 《Physiological research / Academia Scientiarum Bohemoslovaca》2006,55(6):641-652
The slow-twitch soleus muscle (SOL) exhibits decreased twitch tension (cold depression) in response to a decreased temperature, whereas the fast-twitch extensor digitorum longus (EDL) muscle shows enhanced twitch tension (cold potentiation). On the other hand, the slow-twitch SOL muscle is more sensitive to twitch potentiation and contractures evoked by caffeine than the fast-twitch EDL muscle. In order to reveal the effects of these counteracting conditions (temperature and caffeine), we have studied the combined effects of temperature changes on the potentiation effects of caffeine in modulating muscle contractions and contractures in both muscles. Isolated muscles, bathed in a Tyrode solution containing 0.1-60 mM caffeine, were stimulated directly and isometric single twitches, fused tetanic contractions and contractures were recorded at 35 degrees C and 20 degrees C. Our results showed that twitches and tetani of both SOL and EDL were potentiated and prolonged in the presence of 0.3-10 mM caffeine. Despite the cold depression, the extent of potentiation of the twitch tension by caffeine in the SOL muscle at 20 degrees C was by 10-15 % higher than that at 35 degrees C, while no significant difference was noted in the EDL muscle between both temperatures. Since the increase of twitch tension was significantly higher than potentiation of tetani in both muscles, the twitch-tetanus ratio was enhanced. Higher concentrations of caffeine induced contractures in both muscles; the contracture threshold was, however, lower in the SOL than in the EDL muscle at both temperatures. Furthermore, the maximal tension was achieved at lower caffeine concentrations in the SOL muscle at both 35 degrees C and 20 degrees C compared to the EDL muscle. These effects of caffeine were rapidly and completely reversed in both muscles when the test solution was replaced by the Tyrode solution. The results have indicated that the potentiation effect of caffeine is both time- and temperature-dependent process that is more pronounced in the slow-twitch SOL than in the fast-twitch EDL muscles. 相似文献
63.
Garrett A. Soukup Bernd Fritzsch Michael D. Weston Michael T. McManus 《Developmental biology》2009,328(2):328-654
Inner ear development requires coordinated transformation of a uniform sheet of cells into a labyrinth with multiple cell types. While numerous regulatory proteins have been shown to play critical roles in this process, the regulatory functions of microRNAs (miRNAs) have not been explored. To demonstrate the importance of miRNAs in inner ear development, we generated conditional Dicer knockout mice by the expression of Cre recombinase in the otic placode at E8.5. Otocyst-derived ganglia exhibit rapid neuron-specific miR-124 depletion by E11.5, degeneration by E12.5, and profound defects in subsequent sensory epithelial innervations by E17.5. However, the small and malformed inner ear at E17.5 exhibits residual and graded hair cell-specific miR-183 expression in the three remaining sensory epithelia (posterior crista, utricle, and cochlea) that closely corresponds to the degree of hair cell and sensory epithelium differentiation, and Fgf10 expression required for morphohistogenesis. The highest miR-183 expression is observed in near-normal hair cells of the posterior crista, whereas the reduced utricular macula demonstrates weak miR-183 expression and develops presumptive hair cells with numerous disorganized microvilli instead of ordered stereocilia. The correlation of differential and delayed depletion of mature miRNAs with the derailment of inner ear development demonstrates that miRNAs are crucial for inner ear neurosensory development and neurosensory-dependent morphogenesis. 相似文献
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65.
In our chronic experiments (over several months), the activity and protein amount of glycerol-3-phosphate dehydrogenase (GPDH) in mitochondria isolated from the liver of adult male and female inbred Lewis strain euthyroid (EU), hyperthyroid (TH), and hypothyroid (HY) rats were analyzed by biochemical and Western blot methods. The TH status was induced by intraperitoneal injections of 3,3',5-triiodo- L-thyronine and the HY status with 0.05% solution of methimazole in drinking water. The TH status led to a significant increase and the HY status to a significant decrease of enzyme activity and protein amount in both male and female animals. These changes were, however, more pronounced in females. The EU and TH female rats also showed a significantly higher activity and the TH female rats showed also a significantly higher enzyme amount in comparison with males, while the HY rats showed low levels in both sexes. The glycerol-3-phosphate-dependent oxygen consumption of freshly isolated rat liver mitochondria from the TH animals was higher in comparison with the EU animals and it was activated by idebenone, a synthetic analogue of coenzyme Q, in both the EU and TH rats. Measurements of serum thyroid hormone levels and analysis of anatomical parameters (relative heart and thyroid gland weights) confirmed that our procedures inducing the TH and HY states are efficient and reliable and that determination of GPDH can serve as an additional criterion for the evaluation of the thyroid hormone status. 相似文献
66.
Giles SS Soukup AA Lauer C Shaaban M Lin A Oakley BR Wang CC Keller NP 《Applied and environmental microbiology》2011,77(11):3669-3675
Secondary metabolite (SM) production by fungi is hypothesized to provide some fitness attribute for the producing organisms. However, most SM clusters are "silent" when fungi are grown in traditional laboratory settings, and it is difficult to ascertain any function or activity of these SM cluster products. Recently, the creation of a chromatin remodeling mutant in Aspergillus nidulans induced activation of several cryptic SM gene clusters. Systematic testing of nine purified metabolites from this mutant identified an emodin derivate with efficacy against both human fungal pathogens (inhibiting both spore germination and hyphal growth) and several bacteria. The ability of catalase to diminish this antimicrobial activity implicates reactive oxygen species generation, specifically, the generation of hydrogen peroxide, as the mechanism of emodin hydroxyl activity. 相似文献
67.
Pavel Tomsik Tomas Soukup Eva Cermakova Stanislav Micuda Mohamed Niang Lenka Sucha Martina Rezacova 《Central European Journal of Biology》2011,6(1):1-9
It is documented that deficient fucosylation may play an important role in the pathogenesis of cancer. Since the supplementation
of L-fucose could restore fucosylation in both in vitro and in vivo conditions, our intent was to examine the effect of intraperitoneal administration of L-fucose and L-rhamnose (a similar
deoxysaccharide) on tumour growth, mitotic activity and metastatic setting of a solid form of Ehrlich carcinoma as well as
on the survival rate of tumour bearing mice. Both L-fucose and L-rhamnose exerted a significant suppressive effect on tumour
growth (P<0.05). After 10 days of therapy, the greatest inhibition of tumour growth expressed as a percentage of controls
was observed in L-rhamnose at a dose of 3 g/kg/day (by 62%) and L-fucose at a dose of 5 g/kg/day (by 47%). Moreover, the mitotic
index decreased with increasing doses of L-fucose and L-rhamnose. Prolonged survival of tumour bearing mice was observed after
14 consecutive days of daily administering L-rhamnose. Its optimal dose was estimated to be 3.64 g/kg/day. L-Fucose, however,
displayed only a slight effect on the survival of the mice. Our results suggest that L-fucose and especially L-rhamnose have
anticancer potential. This study is the first to demonstrate the tumour-inhibitory effect of L-rhamnose. 相似文献
68.
Iva Smykalová Ji?í Horá?ek Michaela Kubo?iová Prokop ?mirous Jr Ale? Soukup Nikol Gasmanová Miroslav Griga 《In vitro cellular & developmental biology. Plant》2012,48(1):30-39
Plant regeneration was obtained from cultured anthers and hypocotyl segments of caraway (Carum carvi L.). Microspore- and somatic tissue-derived embryos were compared by observation of the regeneration process under identical
induction conditions. Fluorescent microscopy with DAPI staining showed initiation of cell divisions and formation of embryogenic
callus and somatic embryos from anther sacs, with production of embryos of both microspore and somatic origin. Induction of
somatic embryos from hypocotyl-derived callus was also demonstrated. Isozyme native polyacrylamide gel electrophoresis was
used to identify haploids and doubled haploids, and to determine the frequency of spontaneous diploidization of regenerated
plants of microspore origin. Donor plants (2n = 20) and their anther-derived derivative plants (n = 10, 2n = 20, 4n = 40) in callus stage or leafy rosette stage were compared. The esterase (EST) band patterns of regenerated plants differed
from the heterozygous parental material, suggesting that the regenerated plants were microspore-derived haploid/doubled haploid
plants. The similar profile of EST bands between the diploid anther-derived plants and a sample of the donor plants corresponded
to a somatic regeneration pathway. Although the selected induction conditions revealed no preference for induction of microspore
embryogenesis, the anther culture protocol established for caraway utilizing isozyme segregating EST loci markers is suitable
for DH production. 相似文献
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