Effects of short-term endurance exercise on gut microbiota in elderly men.

Regular exercise reduces the risks for cardiovascular diseases. Although the gut microbiota has been associated with fitness level and cardiometabolic risk factors, the effects of exercise-induced gut microbiota changes in elderly individuals are unclear. This study evaluated whether endurance exercise modulates the gut microbiota in elderly subjects, and whether these changes are associated with host cardiometabolic phenotypes. In a randomized crossover trial, 33 elderly Japanese men participated in a 5-week endurance exercise program. 16S rRNA gene-based metagenomic analyses revealed that the effect of endurance exercise on gut microbiota diversity was not greater than interindividual differences, whereas changes in α-diversity indices during intervention were negatively correlated with changes in systolic and diastolic blood pressure, especially during exercise. Microbial composition analyses showed that the relative abundance of Clostridium difficile significantly decreased, whereas that of Oscillospira significantly increased during exercise as compared to the control period. The changes in these taxa were correlated with the changes in several cardiometabolic risk factors. The findings indicate that short-term endurance exercise has little effect on gut microbiota in elderly individuals, and that the changes in gut microbiota were associated with cardiometabolic risk factors, such as systolic and diastolic blood pressure, providing preliminary insight into the associations between the gut microbiota and cardiometabolic phenotypes.

Effect of Accommodating Elastic Bands on Mechanical Power Output during Back Squats.

The aim of this study was to investigate whether accommodating elastic bands with barbell back squats (BSQ) increase muscular force during the deceleration subphase. Ten healthy men (mean ± standard deviation: Age: 23 ± 2 years; height: 170.5 ± 3.7 cm; mass: 66.7 ± 5.4 kg; and BSQ one repetition maximum (RM): 105 ± 23.1 kg; BSQ 1RM/body mass: 1.6 ± 0.3) were recruited for this study. The subjects performed band-resisted parallel BSQ (accommodating elastic bands each sides of barbell) with five band conditions in random order. The duration of the deceleration subphase, mean mechanical power, and the force and velocity during the acceleration and deceleration subphases were calculated. BSQ with elastic bands elicited greater mechanical power output, velocity, and force during the deceleration subphase, in contrast to that elicited with traditional free weight (p < 0.05). BSQ with elastic bands also elicited greater mechanical power output and velocity during the acceleration subphase. However, the force output during the acceleration subphase using an elastic band was lesser than that using a traditional free weight (p < 0.05). This study suggests that BSQ with elastic band elicit greater power output during the acceleration and deceleration subphases.

Influence of Different Loads on Force-Time Characteristics during Back Squats.

The deceleration sub-phase during the back squat (BSQ) makes it difficult to stimulate the muscles throughout the full range of motion, and it has only been reported for one load during BSQ. The purpose of this study was to investigate whether a deceleration sub-phase occurs during BSQ with different loads and to assess the influence of load on the deceleration sub-phase duration and negative impulse during the deceleration sub-phase. Sixteen healthy men (mean ± standard deviation: age: 25 ± 3 years; height: 1.73 ± 0.07 m; mass: 83.2 ± 16.1 kg; BSQ one repetition maximum (1RM): 163.8 ± 36.6 kg; BSQ 1RM/body weight: 2.0 ± 0.4) who had performed resistance training for at least 1 year were recruited for this study. The subjects performed parallel BSQ with 0%, 12%, 27%, 42%, 56%, 71%, and 85% of each 1RM on a force plate in a random order. The deceleration sub-phase duration and negative impulse during the deceleration sub-phase were calculated from force-time data. The absolute durations of the deceleration sub-phase were not significantly different according to load except for 27% 1RM and 85% 1RM (p = 0.01). However, as the load increased from 12 to 85% 1RM, the relative duration of the deceleration sub-phase decreased (p < 0.05). The negative impulse during the deceleration sub-phase also increased from 0 to 42% 1RM (p < 0.05). A deceleration sub-phase occurs regardless of the load (0%-85% 1RM), and a large portion of the deceleration sub-phase occupied the concentric phase, with low-moderate loads, and a large amount of negative impulse occurred during the short deceleration sub-phase with a high load.

Availability of right femoral vein as a route for tunneled hemodialysis catheterization.

PURPOSE: This study was performed to investigate the primary patency rate and catheter-related problems associated with use of the femoral vein as a route for tunneled hemodialysis catheterization compared with those of the right internal jugular vein as the first-choice route in patients undergoing maintenance hemodialysis. PATIENTS AND METHODS: Twenty-two patients underwent placement of indwelling tunneled hemodialysis catheters in the right internal jugular vein as the first option for maintenance hemodialysis, and 20 patients underwent placement in the right femoral vein as the second option. The primary patency rate of the catheters and catheter-related problems at 1, 3, 6, and 12 months after placement were investigated. RESULTS: The 1-, 3-, 6-, and 12-month primary patency rates of the tunneled hemodialysis catheters in the right internal jugular vein were 95.5%, 95.5%, 81.3%, and 58.3%. The primary patency rates of the catheters in the right femoral vein were 95.0%, 89.5%, 86.7%, and 66.7%. There were no statistically significant differences in the primary patency rates at 1, 3, 6, and 12 months or in catheter-related problems between the right internal jugular vein and right femoral vein. CONCLUSION: The primary patency rate and catheter-related problems of indwelling tunneled hemodialysis catheters placed in the right femoral vein were not different from those in the right internal jugular vein in patients undergoing maintenance hemodialysis. These results suggest that the right femoral vein might be a useful option for placement of indwelling tunneled hemodialysis catheters in patients undergoing maintenance hemodialysis.

Acute hepatitis E in a renal transplantation recipient: a case report.

Hepatitis E is caused by infection with the hepatitis E virus (HEV). HEV is transmitted orally via HEV-contaminated food or drink. Hepatitis E usually shows mild symptoms and is self-limiting in the general population; however, it may progress to chronic hepatitis in immunosuppressed patients such as recipients of organ transplantation. However, a few cases of acute hepatitis E have been reported in organ transplantation recipients. We herein report a case of acute hepatitis E in a 31-year-old male renal transplant recipient. The patient underwent renal transplantation 2 years ago, and his postoperative course was uneventful without rejection. After complaining of general fatigue and low-grade fever for 1 week, he was referred to and admitted to our hospital. Careful interview revealed that he ate undercooked pork 10 weeks prior. Blood analysis revealed liver dysfunction but was serologically negative for hepatitis A, B and C virus, cytomegalovirus infection and collagen diseases. Immunoglobulin A antibody against hepatitis E virus (HEV-IgA) was also negative at that point. After 2 weeks of admission, HEV-IgA and HEV-RNA were measured again as hepatitis E could not be ruled out due to history of ingestion of undercooked meat that may have been contaminated with HEV. At that time, HEV-IgA and HEV-RNA (genotype 3) were positive. Thus, an acute hepatitis E was diagnosed. His liver function gradually improved to within the normal range, and HEV-IgA and HEV-RNA were negative at 11 weeks after admission. In conclusion, we describe here a case of acute hepatitis E in a renal transplant recipient. Careful interview regarding the possibility of ingestion of HEV-contaminated food and repeated measurements of HEV-IgA were helpful in finalizing a diagnosis.

Effects of chronic endurance exercise training on serum 25(OH)D concentrations in elderly Japanese men.

BACKGROUND: Higher levels of physical activity and cardiorespiratory fitness are positively related to serum 25-hydroxyvitamin D [25(OH)D] concentrations; however, the response of 25(OH)D concentrations to chronic endurance exercise training is unclear. Therefore, the purpose of this study was to elucidate whether serum 25(OH)D concentrations were directly increased by 5 weeks of endurance exercise training and influenced by changes in body fat in elderly men. METHODS: Twenty elderly Japanese men were randomized to either the 5-week endurance exercise training group (ET group; N = 10) or the sedentary control group (SC group; N = 10). Fasting blood samples were collected to determine serum 25(OH)D and other blood parameters. The visceral fat area and hepatic fat content were assessed by magnetic resonance imaging and proton magnetic resonance spectroscopy, respectively. RESULTS: After 5 weeks of endurance exercise training, the levels of maximal oxygen uptake (VO2 max) were significantly increased from 23.3 at baseline to 28.1 mL/kg/min at the endpoint for the ET group; levels were unchanged for the SC group. A significant seasonal reduction in serum 25(OH)D concentrations was observed in the SC group (P < 0.05), while no change was found in the ET group. The results may be partly attributed to the slight decrease in intrahepatic fat in the ET group. No changes were observed in percent body fat or visceral fat area. CONCLUSIONS: The results of our study suggest that 5 weeks of endurance training could inhibit the seasonal reduction in serum 25(OH)D concentrations without changes in body fat.

Endurance Exercise Reduces Hepatic Fat Content and Serum Fibroblast Growth Factor 21 Levels in Elderly Men.

CONTEXT: Age-related hepatic fat accumulation increases the risk of cardiometabolic diseases, and the fibroblast growth factor (FGF) 21-resistant state caused by fatty liver underlies the pathogenesis of these diseases. OBJECTIVE: Previous studies suggested that a higher level of cardiorespiratory fitness was associated with both lower hepatic fat content and serum FGF21 levels; however, the effect of endurance exercise on hepatic fat content and serum FGF21 concentration has not been studied. Therefore, we aimed to elucidate whether endurance exercise reduced hepatic fat content and serum FGF21 levels. DESIGN: This is a randomized crossover trial. SETTING: The study setting was an institutional practice. PATIENTS: Thirty-three elderly Japanese men participated in the study. INTERVENTION: The intervention was a 5-week endurance exercise program comprising three cycle ergometer sessions per week. MAIN OUTCOME MEASURES: Hepatic fat content was assessed by proton magnetic resonance spectroscopy, and serum FGF21 level was determined by ELISA. RESULTS: A 5-week endurance exercise program decreased the hepatic fat content and serum FGF21 levels without weight loss, and the changes were higher in the exercise period than in the control period (P = .021 and P = .026, respectively). Correlation analysis demonstrated that only the change in hepatic fat content was significantly and positively correlated with change in serum FGF21 levels (r = 0.366, P = .006). CONCLUSIONS: A 5-week endurance exercise program decreased hepatic fat content and serum FGF21 levels without weight loss in elderly men, and exercise-induced hepatic fat reduction mediated the reduction in serum FGF21 levels. These findings suggest that endurance exercise modulates hepatic fat content and FGF21 resistance, regardless of obesity status.

TAE226, a Bis-Anilino Pyrimidine Compound, Inhibits the EGFR-Mutant Kinase Including T790M Mutant to Show Anti-Tumor Effect on EGFR-Mutant Non-Small Cell Lung Cancer Cells.

TAE226, a bis-anilino pyrimidine compound, has been developed as an inhibitor of focal adhesion kinase (FAK) and insulin-like growth factor-I receptor (IGF-IR). In this study, we investigated the effect of TAE226 on non-small-cell lung cancer (NSCLC), especially focusing on the EGFR mutational status. TAE226 was more effective against cells with mutant EGFR, including the T790M mutant, than against cells with wild-type one. TAE226 preferentially inhibited phospho-EGFR and its downstream signaling mediators in the cells with mutant EGFR than in those with wild-type one. Phosphorylation of FAK and IGF-IR was not inhibited at the concentration at which the proliferation of EGFR-mutant cells was inhibited. Results of the in vitro binding assay indicated significant differences in the affinity for TAE226 between the wild-type and L858R (or delE746_A750) mutant, and the reduced affinity of ATP to the L858R (or delE746_A750) mutant resulted in good responsiveness of the L858R (or delE746_A750) mutant cells to TAE226. Of interest, the L858R/T790M or delE746_A750/T790M mutant enhanced the binding affinity for TAE226 compared with the L858R or delE746_A750 mutant, resulting in the effectiveness of TAE226 against T790M mutant cells despite the T790M mutation restoring the ATP affinity for the mutant EGFR close to that for the wild-type. TAE226 also showed higher affinity of about 15-fold for the L858R/T790M mutant than for the wild-type one by kinetic interaction analysis. The anti-tumor effect against EGFR-mutant tumors including T790M mutation was confirmed in mouse models without any significant toxicity. In summary, we showed that TAE226 inhibited the activation of mutant EGFR and exhibited anti-proliferative activity against NSCLCs carrying EGFR mutations, including T790M mutation.

Preclinical evaluation of microRNA-34b/c delivery for malignant pleural mesothelioma.

The microRNA-34s (miR-34s) have p53 response elements in their 5'-flanking regions and demonstrate tumor-suppressive functions. In malignant pleural mesothelioma (MPM), we previously reported that expression of miR-34b and miR-34c (miR-34b/c) was frequently downregulated by methylation in MPM cell lines and primary tumors. The forced overexpression of miR-34b/c showed significant antitumor effects with the induction of apoptosis in MPM cells. In this study, we examined the in vivo antitumor effects of miR-34b/c using adenovirus vector on MPM. We subcutaneously transplanted NCI-H290, a human MPM cell line, into BALB/C mice and injected adenovirus vector expressing miR-34b/c, luciferase driven by the cytomegalovirus promoter (Ad-miR-34b/c or Ad-Luc), or PBS control into tumors over 5mm in diameter. A statistically significant growth inhibition of the tumor volume was observed in the Ad-miR-34b/c group from day 6 onward compared to the Ad-Luc group. The inhibition rate of Ad-miR-34b/c, compared to the tumor volume treated with Ad-Luc, was 58.6% on day 10 and 54.7% on day13. Our results indicate that adenovirus-mediated miR-34b/c gene therapy could be useful for the clinical treatment of MPM.

Heparin-conjugated gelatin as a growth factor immobilization scaffold.

Tissue engineering requires growth factors, cells and a scaffold to permit effective tissue regeneration. This study aimed to develop a scaffold with a focus on immobilizing growth factors within gelatin. We focused on the extracellular matrix and developed a heparin-conjugated gelatin (Hep-gela). Conjugation was confirmed using the alcian blue assay and X-ray diffraction patterns. The mechanical strength and stability of the Hep-gela gel in protease solution were improved compared with collagen gel. Hep-gela was able to immobilize vascular endothelial growth factor (VEGF) even in the presence of albumin, with an efficiency of 54.2%. Immobilized VEGF promoted proliferation of human umbilical vein endothelial cells. Hep-gela-immobilized VEGF maintained its native biological activity. In summary, Hep-gela has the potential to become an effective material in the field of regenerative medicine.

MicroRNA miR-34b/c enhances cellular radiosensitivity of malignant pleural mesothelioma cells.

BACKGROUND: We previously reported that epigenetic silencing of microRNA-34b/c (miR-34b/c) plays an important role in the pathogenesis of malignant pleural mesothelioma (MPM). We examined the impact of miR-34b/c restoration on the radiosensitivity of MPM cells. MATERIALS AND METHODS: We established stable miR-34b/c and scramble transfectants of two MPM cell lines, H2052 and H28. We examined these transfectants by clonogenic survival assay, phosphorylated histone H2AX (γH2AX) foci assay, cell-cycle analysis, and western blotting. RESULTS: The clonogenic survival assay revealed that miR-34b/c radiosensitized MPM cells. γH2AX foci assay showed that DNA double-strand break repair was delayed in miR-34b/c transfectants. The proportion of sub-G(1) phase cells was increased in miR-34b/c transfectants after irradiation. miR-34b/c inhibited expression of cyclin-D1, cyclin-dependent kinase 4/6, B-cell lymphoma-2 (BCL-2) and increased cleaved poly (ADP-ribose) polymerase (cPARP) and cleaved caspase-3 after irradiation. CONCLUSION: Our results indicate that miR-34b/c enhances radiosensitivity by promoting radiation-induced apoptosis and suggested that miR-34b/c might be a useful therapeutic molecule to enhance radiotherapy in MPM.

Knockdown of the epidermal growth factor receptor gene to investigate its therapeutic potential for the treatment of non-small-cell lung cancers.

BACKGROUND: Epidermal growth factor receptor (EGFR) is often overexpressed in non-small-cell lung cancer (NSCLC). Anti-EGFR agents, including EGFR-tyrosine kinase inhibitors are considered to be effective when a drug-sensitive EGFR mutation is present. However, inherent and acquired resistances are major problems of EGFR-targeting therapies. In this study, we performed EGFR knockdown by using small interfering RNAs in NSCLC cell lines to examine the significance of targeting EGFR for NSCLC therapy. METHODS: We treated 13 NSCLC cell lines, including 8 EGFR mutant and 5 EGFR wild type by using gefitinib or small interfering RNAs against EGFR (siEGFR). Three cell lines (PC-9-GR1, RPC-9, and HCC827-ER) were experimentally established with acquired resistance to EGFR-tyrosine kinase inhibitors. The antitumor effect was determined by using an 3-[4,5-dimethylthiazol-2-yl]-5-[3-carboxymethoxyphenyl]-2-[4-sulfophenyl]-2H-tetrazolium, inner salt (MTS) or colony formation assay. The protein expression was evaluated by using Western blotting. RESULTS: All 13 cell lines expressed EGFR protein, and siEGFR downregulated EGFR protein expression in all. The cell viability was suppressed by siEGFR in 6 of 8 EGFR-mutant cell lines (suppressed 57%-92% of control cells), including PC-9-GR1 and RPC-9. The NCI-H1650 and HCC827-ER harbored EGFR mutations but were not suppressed. Of note, PTEN (phosphatase and tensin homolog) was deleted in NCI-H1650, and c-MET was amplified in HCC827-ER. It was not suppressed in any of the EGFR wild-type cells except in the NCI-H411, in which EGFR is phosphorylated, which indicates its activation. CONCLUSIONS: Analysis of the results indicated that EGFR can be a therapeutic target in NSCLCs with EGFR activation. In contrast, targeting EGFR is not appropriate for tumors in which EGFR is not activated, even if EGFR is expressed.

The anti-proliferative effect of heat shock protein 90 inhibitor, 17-DMAG, on non-small-cell lung cancers being resistant to EGFR tyrosine kinase inhibitor.

Acquired resistance to epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs), gefitinib and erlotinib, is frequently observed after initiation of TKIs therapy. Non-small-cell lung cancers (NSCLC) with activating EGFR mutations were reported to be sensitive to heat shock protein 90 (Hsp90) inhibitors regardless of the secondary TKI-resistant T790M mutation. We established EGFR-TKI resistant clones for PC-9 cell lines, harboring EGFR exon 19 deletions, with or without the secondary T790M mutation. We examined the anti-proliferative effect of 17-dimethylaminoethylamino-17-demethoxygeldanamycin (17-DMAG), an orally active Hsp90 inhibitor, on the growth of NSCLC cell lines in vitro and in vivo. In MTS assay, the IC(50) values of 17-DMAG for 13 EGFR-mutant cell lines including eight EGFR-TKI resistant cell lines ranged from 0.04 to 0.16 µM while those for seven EGFR-wild type cell lines ranged from 1.6 to 27.4 µM. Western blot analysis revealed that phospho-EGFR, phospho-Akt, phospho-MAPK, cdk4, and cyclin D1 were more readily depleted by 17-DMAG treatment in EGFR-mutant cell lines than in EGFR-wild type cell lines. Cleaved PARP expression confirmed apoptosis in response to 17-DMAG treatment in EGFR-mutant cell lines but not in EGFR-wild type cell lines. In mice xenograft models, 17-DMAG significantly reduced the growth of EGFR-mutant lines irrespective of T790M mutation. These results suggested that 17-DMAG is a potential novel therapeutic agent for NSCLC patients with EGFR mutations with or without EGFR-TKI resistance.

Frequent methylation and oncogenic role of microRNA-34b/c in small-cell lung cancer.

Small-cell lung cancer (SCLC) is an aggressive tumor with a dismal prognosis among primary lung cancers. MicroRNAs (miRNAs) can act as oncogenes or tumor-suppressor genes in human malignancy. The miR-34 family is comprised of tumor-suppressive miRNAs, and its reduced expression by methylation has been reported in various cancers, including non-small cell lung cancer (NSCLC). In this study, we investigated the alteration and tumor-suppressive impact of miR-34s in SCLC. The methylation of miR-34a and miR-34b/c was observed in 4 (36%) and 7 (64%) of 11 SCLC cell lines, respectively. Among the 27 SCLC clinical specimens, miR-34a and miR-34b/c were methylated in 4 (15%) and 18 (67%), respectively. In contrast, 13 (28%) miR-34a methylated cases and 12 (26%) miR-34b/c methylated cases were found in 47 NSCLC primary tumors. The frequency of miR-34b/c methylation was significantly higher in SCLC than in NSCLC (p<0.001). The expressions of miR-34s were reduced in methylated cell lines and tumors and restored after 5-aza-2'-deoxycytidine treatment, indicating that methylation was responsible for the reduced expression of miR-34s. Because the frequency of methylation was higher in miR-34b/c, we focused on miR-34b/c for a functional analysis. We examined the effect of miR-34b/c introduction on cell proliferation, migration and invasion. The transfection of miR-34b/c to two SCLC cell lines (H1048 and SBC5) resulted in the significant inhibition of cell growth, migration, and invasion, compared with control transfectants. Our results indicate that the aberrant methylation of miR-34b/c plays an important role in the pathogenesis of SCLC, implying that miR-34b/c may be a useful therapeutic target for SCLC.

Aberrant methylation of p21 gene in lung cancer and malignant pleural mesothelioma.

Suppression of p21 has been implicated in the genesis and progression of many human malignancies. DNA methylation is an important mechanism of gene silencing in human malignancies. In this study, we examined the expression status and aberrant methylaion of p21 in lung cancers and malignant pleural mesotheliomas (MPM). We used 12 small cell lung cancer (SCLC) cell lines, 13 non-small cell lung cancer (NSCLC) cell lines, 50 primary NSCLCs, 6 MPM cell lines and 10 primary MPMs. The expression and methylation of p21 was examined by reverse transcription-PCR (RT-PCR), Western blotting and methylation-specific PCR (MSP) assay. Loss of p21 protein expression was observed in 7 SCLC cell lines (58.3%), 5 NSCLC cell lines (38.5%) and 3 MPM cell lines (50%) while mRNA expression was lost in 2 SCLC cell lines (16.7%), 2 NSCLC cell lines (15.4%) and none of the MPM cell lines. Aberrant methylation of p21 was found in 8.3% of SCLC cell lines, 30.2% of NSCLCs and 6.3% of MPMs. Among primary NSCLCs, methylation in adenocarcinomas was significantly more frequent than in squamous cell carcinomas. Loss of p21 expression was frequently observed in lung cancers and MPMs and aberrant methylation was one of the mechanisms of suppression of p21, especially in NSCLCs.

Epigenetic silencing of microRNA-34b/c plays an important role in the pathogenesis of malignant pleural mesothelioma.

PURPOSE: Malignant pleural mesothelioma (MPM) is an aggressive tumor with a dismal prognosis. Unlike other malignancies, TP53 mutations are rare in MPM. Recent studies have showed that altered expression of microRNA (miRNA) is observed in human malignant tumors. In this study, we investigated the alterations of miR-34s, a direct transcriptional target of TP53, and the role of miR-34s on the pathogenesis of MPM. EXPERIMENTAL DESIGN: Aberrant methylation and expression of miR-34s were examined in MPM cell lines and tumors. miR-34b/c was transfected to MPM cells to estimate the protein expression, cell proliferation, invasion, and cell cycle. RESULTS: Aberrant methylation was present in 2 (33.3%) of 6 MPM cell lines and 13 (27.7%) of 47 tumors in miR-34a and in all 6 MPM cell lines (100%) and 40 (85.1%) of 47 tumors in miR-34b/c. Expression of miR-34a and 34b/c in all methylated cell lines was reduced and restored with 5-aza-2'-deoxycytidine treatment. Because epigenetic silencing was the major event in miR-34b/c, we investigated the functional role of miR-34b/c in MPM. miR-34b/c-transfected MPM cells with physiologic miR-34b/c expression exhibited antiproliferation with G(1) cell cycle arrest and suppression of migration, invasion, and motility. The forced overexpression of miR-34b/c, but not p53, showed a significant antitumor effect with the induction of apoptosis in MPM cells. CONCLUSIONS: We show that the epigenetic silencing of miR-34b/c by methylation is a crucial alteration and plays an important role in the tumorigenesis of MPM, suggesting potential therapeutic options for MPM.

Nuclear DNA fragmentation during cell death of short-lived ray tracheids in the conifer Pinus densiflora.

One key event in the programmed cell death is nuclear DNA fragmentation. We investigated the timing of nuclear DNA fragmentation during the cell death of short-lived ray tracheids in Pinus densiflora using the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assay. Fluorescence due to TUNEL was detected only in deformed nuclei that lacked obvious chromatin in ray tracheids that were adjacent to ray tracheids that no longer contained nuclei. Our observations revealed that nuclear DNA fragmentation occurred only at the final stage of cell death in ray tracheids in situ.

Changes in the localization and levels of starch and lipids in cambium and phloem during cambial reactivation by artificial heating of main stems of Cryptomeria japonica trees.

BACKGROUND AND AIMS: Cambial reactivation in trees occurs from late winter to early spring when photosynthesis is minimal or almost non-existent. Reserve materials might be important for wood formation in trees. The localization and approximate levels of starch and lipids (as droplets) and number of starch granules in cambium and phloem were examined from cambial dormancy to the start of xylem differentiation in locally heated stems of Cryptomeria japonica trees in winter. METHODS: Electric heating tape was wrapped on one side of the stem of Cryptomeria japonica trees at breast height in winter. The localization and approximate levels of starch and lipids (as droplets) and number of starch granules were determined by image analysis of optical digital images obtained by confocal laser scanning microscopy. KEY RESULTS: Localized heating induced earlier cambial reactivation and xylem differentiation in stems of Cryptomeria japonica, as compared with non-heated stems. There were clear changes in the respective localizations and levels of starch and lipids (as droplets) determined in terms of relative areas on images, from cambial dormancy to the start of xylem differentiation in heated stems. In heated stems, the levels and number of starch granules fell from cambial reactivation to the start of xylem differentiation. There was a significant decrease in the relative area occupied by lipid droplets in the cambium from cambial reactivation to the start of xylem differentiation in heated stems. CONCLUSIONS: The results showed clearly that the levels and number of storage starch granules in cambium and phloem cells and levels of lipids (as droplets) in the cambium decreased from cambial reactivation to the start of xylem differentiation in heated stems during the winter. The observations suggest that starch and lipid droplets might be needed as sources of energy for the initiation of cambial cell division and the differentiation of xylem in Cryptomeria japonica.