156 research outputs found
Freezing tolerance in alpine plants as assessed by the FDA-staining method
We established a method employing fluorescein diacetate (FDA)-staining with a laser scan microscope for evaluation of the freezing tolerance of leaf mesophyll cells, and applied it to assessments of freezing tolerance in leaves of nine alpine plants, Arcterica nana, Cassiope lycopodioides, Diapensia lapponica, Empetrum nigrum, Loiseleuria procumbens, Phyllodoce nipponica, Rhododendron aureum, Schizocodon soldanelloides, and Vaccinium vitis-idaea, which naturally occur on Mt. Iwo (36°00′N, 138°22′W, 2760 m a.s.l.) in 2001. The results obtained with the FDA-staining method were strongly correlated with those of the electrolyte-leakage test, suggesting that this method is highly reliable. Leaf mesophyll cells in all these plants collected in early September survived after freezing at -5°C, but did not survive below -30°C. The survival ratio at subzero temperatures, ranging from -5 to -16°C, varied among the species. On the other hand, all the mesophyll cells of the plants collected in the middle of November survived freezing at -30°C. However, the survival ratio decreased after freezing at -80°C in Phyllodoce nipponica and Empetrum nigrum. Using the FDA-staining method, we were able to confirm the increase of the freezing tolerance of alpine plants from September to November. Advantages of the new method are discussed
A new application of the SFDA-staining method to assessment of the freezing tolerance in leaves of alpine plants
For the first time, this study used 5- (6-) sulfofluorescein diacetate (SFDA), a fluorescent product in plant cells converted by esterase activity to fluorescein-5- (and 6-) sulfonic acid (FSA), to assess the freezing tolerance of leaf cells. We were able to readily distinguish living and dead cells, and detect differences in freezing tolerance among five alpine plants using the SFDA-staining method. We also compared this method with two conventional methods, the electrolyte leakage test and fluorescein diacetate (FDA) staining method. The electrolyte leakage test often over- or underestimated freezing injury. With the uninjured control samples, the FDA-staining method failed to stain all leaf cells, while the SFDA-staining method stained almost 100%. From these results, we concluded that SFDA-staining is a more convenient, accurate and reproducible method for analyses of freezing tolerance
Quantification of PERF 15 mRNA in Tissue Sections from Rat Testes
We previously conducted basic research to quantify in situ hybridization (ISH) signals in rat testes. In this experimental model, we selected ribosomal RNA (rRNA) as the hybridizable RNA in paraffin sections, since it allowed us to easily analyze ISH signals expressed with digoxygenin (DIG)-labeled probes quantitatively through “posterization” of the images. We applied this method to analyze the quantification of transcript, PERF 15 mRNA. PERF 15 is expressed specifically in the testes and localized in the rigid cytoskeletal structure of the sperm head, and has been considered to be involved in the apoptotic process of spermatogenic cells. Quantification of the signals may help to clarify the detailed function of PERF 15. We further analyzed the signals concomitant with a confocal laser scanning microscope. The peak of PERF 15 mRNA expression was found in diplotene spermatocytes, and the amount of PERF 15 mRNA was greatest in late pachytene and diplotene spermatocytes and early spermatids, followed by early pachytene spermatocytes, and then late spermatids. PERF 15 may be involved in the events leading to meiotic division, in which apoptosis is also involved. The present study may help to determine the concentration of mRNA in tissue sections
Alterations of Muscle Synergies During Voluntary Arm Reaching Movement in Subacute Stroke Survivors at Different Levels of Impairment
Motor system uses muscle synergies as a modular organization to simplify the control of movements. Motor cortical impairments, such as stroke and spinal cord injuries, disrupt the orchestration of the muscle synergies and result in abnormal movements. In this paper, the alterations of muscle synergies in subacute stroke survivors were examined during the voluntary reaching movement. We collected electromyographic (EMG) data from 35 stroke survivors, ranging from Brunnstrom Stage III to VI, and 25 age-matched control subjects. Muscle synergies were extracted from the activity of 7 upper-limb muscles via nonnegative matrix factorization under the criterion of 95% variance accounted for. By comparing the structure of muscle synergies and the similarity of activation coefficients across groups, we can validate the increasing activation of pectoralis major muscle and the decreasing activation of elbow extensor of triceps in stroke groups. Furthermore, the similarity of muscle synergies was significantly correlated with the Brunnstrom Stage (R = 0.52, p < 0.01). The synergies of stroke survivors at Brunnstrom Stage IV–III gradually diverged from those of control group, but the activation coefficients remained the same after stroke, irrespective of the recovery level
- …