Giant peroxisomes in a moss (Physcomitrella patens) peroxisomal biogenesis factor 11 mutant

Peroxisomal biogenesis factor 11 (PEX11) proteins are found in yeasts, mammals and plants, and play a role in peroxisome morphology and regulation of peroxisome division. The moss Physcomitrella patens has six PEX11 isoforms which fall into two subfamilies, similar to those found in monocots and dicots. We carried out targeted gene disruption of the Phypa_PEX11-1 gene and compared the morphological and cellular phenotypes of the wild-type and mutant strains. The mutant grew more slowly and the development of gametophores was retarded. Mutant chloronemal filaments contained large cellular structures which excluded all other cellular organelles. Expression of fluorescent reporter proteins revealed that the mutant strain had greatly enlarged peroxisomes up to 10 μm in diameter. Expression of a vacuolar membrane marker confirmed that the enlarged structures were not vacuoles, or peroxisomes sequestered within vacuoles as a result of pexophagy. Phypa_PEX11 targeted to peroxisome membranes could rescue the knock out phenotype and interacted with Fission1 on the peroxisome membrane. Moss PEX11 functions in peroxisome division similar to PEX11 in other organisms but the mutant phenotype is more extreme and environmentally determined, making P. patens a powerful system in which to address mechanisms of peroxisome proliferation and division

Salt Stress Causes Peroxisome Proliferation, but Inducing Peroxisome Proliferation Does Not Improve NaCl Tolerance in Arabidopsis thaliana

The PEX11 family of peroxisome membrane proteins have been shown to be involved in regulation of peroxisome size and number in plant, animals, and yeast cells. We and others have previously suggested that peroxisome proliferation as a result of abiotic stress may be important in plant stress responses, and recently it was reported that several rice PEX11 genes were up regulated in response to abiotic stress. We sought to test the hypothesis that promoting peroxisome proliferation in Arabidopsis thaliana by over expression of one PEX11 family member, PEX11e, would give increased resistance to salt stress. We could demonstrate up regulation of PEX11e by salt stress and increased peroxisome number by both PEX11e over expression and salt stress, however our experiments failed to find a correlation between PEX11e over expression and increased peroxisome metabolic activity or resistance to salt stress. This suggests that although peroxisome proliferation may be a consequence of salt stress, it does not affect the ability of Arabidopsis plants to tolerate saline conditions

Dry Matter Production of Two Rice Cultivars with Contrasting Root Plasticity Expression Under Different Topographic Conditions Subjected to Soil Moisture Fluctuation

In rainfed lowland rice fields characterized by sloping terrains and the presence of a hardpan in a flat topography, plants are often exposed to soil moisture fluctuation (SMF) stress due to erratic rainfall patterns. Root plasticity is one of the key traits that play important roles in plant adaptation under such conditions. In this study, two contrasting genotypes, KDML105 and IRAT109, were examined to quantify the expression of plasticity in root branching at different positions in the toposequence (TP) and in a flat topography with a hardpan, both without a groundwater table, and subjected to SMF. Results showed that KDML105 exhibited improved adaptation to SMF conditions due to its greater root system because of the promoted nodal root production and development of lateral roots in the upper soil layer (0 – 20 cm soil depth) along the TP and above the hardpan in a flat topography, which led to the maintenance of its stomatal conductance and dry matter production. IRAT109, on the other hand, did not express root plasticity in deep-rooting due to the absence of groundwater table, particularly in the upper TP, as well as branching ability above the hardpan in a flat topography, which resulted in less water uptake and reduced dry matter production under SMF. Overall, the results indicated that root plasticity in the upper soil layer could be an important trait for the adaptation of rice, both in a sloping TP without a hardpan or in a flat topography with a hardpan, experiencing SMF

Grain Yield Variations in Rice Genotypes under Different Growing Environments in the Philippines

Grain yield variations in PSB Rc18, NSIC Rc222 (inbreds) and NSIC Rc202H (hybrid) were determined across growing environments as a function of cropping seasons and locations in rice producing areas in the Philippines. Contribution of location to variation in grain yield is 61.0%, while 12.7% for the season, and 6.1% for the genotype and this must be due location by season by genotype interactions. Dry season cropping in Nueva Ecija produced the highest mean grain yield. On the other hand, wet season cropping in Davao del Sur produced the least mean grain yield. The genotypes differed in their response to varying growing environments. NSIC Rc202H is the highest yielder among genotypes during dry season in Nueva Ecija. NSIC Rc222 is the most stable, having relatively high and constant grain yield across environments. High grain yield is associated with aboveground biomass particularly in NSIC Rc202H (R2= 0.8615). Harvest index of NSIC Rc222 has less variations across growing environments, hence, one reason for its relative stability. Among yield components, spikelets per panicle and percent filled spikelets are highly correlated with grain yield (r = 0.85 and r = 0.82, respectively). Grain yield is highly influenced by solar radiation and temperature. Growing degree days (GDD) accumulated by genotypes are generally lower during wet season than dry season. While genotypes with different growth durations may require different GDDs, the higher the GDD accumulated by a particular genotype, regardless of growth duration resulted in higher grain yield, and variations in accumulated GDD is affected directly by temperature and indirectly by solar radiation, contributed to the variations in grain yield across growing environments

A multi-ethnic meta-analysis identifies novel genes, including ACSL5, associated with amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a devastating progressive motor neuron disease that affects people of all ethnicities. Approximately 90% of ALS cases are sporadic and thought to have multifactorial pathogenesis. To understand the genetics of sporadic ALS, we conducted a genome-wide association study using 1,173 sporadic ALS cases and 8,925 controls in a Japanese population. A combined meta-analysis of our Japanese cohort with individuals of European ancestry revealed a significant association at the ACSL5 locus (top SNP p = 2.97 × 10−8). We validated the association with ACSL5 in a replication study with a Chinese population and an independent Japanese population (1941 ALS cases, 3821 controls; top SNP p = 1.82 × 10−4). In the combined meta-analysis, the intronic ACSL5 SNP rs3736947 showed the strongest association (p = 7.81 × 10−11). Using a gene-based analysis of the full multi-ethnic dataset, we uncovered additional genes significantly associated with ALS: ERGIC1, RAPGEF5, FNBP1, and ATXN3. These results advance our understanding of the genetic basis of sporadic ALS

Tissue Localization of the Glycine Betaine Biosynthetic Enzymes in Barley Leaves

Barley (Hordeum vulgare L.) plants accumulate glycine betaine (GB), a major compatible solute, in response to salt stress. In barley, GB is produced by a two-step oxidation of choline in a cooperative way in the cytosol and peroxisomes. In this study, we investigated the localization of two GB biosynthetic enzymes, choline monooxygenase (CMO) and betaine aldehyde dehydrogenase (BADH), in the tissues of barley plants (cv. Haruna-nijyo) grown under normal and saline conditions. Three-week-old barley plants grown hydroponically were treated with a hydroponic culture solution containing 200 mM NaCl for 72 h. Salt treatment resulted in increased expression of CMO and BADH proteins mainly in the leaves of barley but not in the roots. The expression of CMO protein was increased by the presence of NaCl in younger leaves but decreased in older leaves. The tissue localization of CMO and BADH proteins was analyzed by immunofluorescent labeling method using their primary antibodies and a fluorescein-conjugated secondary antibody. CMO and BADH proteins were constitutively co-localized in mesophyll and bundle sheath cells under both normal and saline conditions. A possible physiological function of GB in the salt tolerance of barley plants is discussed

Locked Tension Band Wiring: A Modified Technique for Olecranon Fractures—A Multicenter Study Comparing Clinical Outcomes and Complications with Conventional Methods

Purpose: Tension band wiring is the standard treatment for olecranon fractures, but it is associated with high rate of implant-related complication. To reduce this high complication rate, we developed a modified technique, locked tension band wiring (LTBW). The aim of this study was to investigate whether LTBW reduces complication and reoperation rates compared to conventional methods (CTBW). Methods: We identified 213 olecranon fractures treated with tension band wiring: 183 were treated with CTBW, and 30 were treated with LTBW, and patients in each group were selected using propensity score matching. We evaluated operation time, intraoperative bleeding, complication and reoperation rates, the amount of Kirschner’s wire (K-wire) back-out, and Mayo Elbow Performance Index (MEPI). Complications included nonunion, loss of fracture reduction, implant failure, infection, neurological impairment, heterotopic ossification, and implant irritation. Implant removal included at the patient's request with no symptoms. Results: We finally investigated 29 patients in both groups. The mean operation time was significantly longer in the LTBW (106.7 ± 17.5 vs. 79.7 ± 21.1 min; p < 0.01). Complication rates were significantly lower in the LTBW than the CTBW group (10.3 vs. 37.9%; p = 0.03). The rate of implant irritation was more frequent in the CTBW, but there was no significant difference (3.4 vs. 20.7%; p = 0.10). Removal rate was significantly lower in the LTBW (41.4 vs. 72.4%; p = 0.03). The mean amount of K-wire backout at last follow-up was significantly less in the LTBW (3.79 ± 0.65 mm vs. 8.97 ± 3.54 mm; p < 0.01). There were no significant differences in mean MEPI at all follow-up periods (77.4 ± 9.0 vs. 71.5 ± 14.0; p = 0.07, 87.4 ± 7.2 vs. 85.2 ± 10.3; p = 0.40, 94.6 ± 5.8 vs. 90.4 ± 9.0; p = 0.06, respectively). Conclusion: Our modified TBW significantly increased operation time compared to conventional method, but reduced the complication and removal rate and had equivalent functional outcomes in this retrospective study.journal articl