Changes in endogenous abscisic acid and stomata of the resurrection fern, Pleopeltis polypodioides, in response to de- and rehydration.

PREMISE: While angiosperms respond uniformly to abscisic acid (ABA) by stomatal closure, the response of ferns to ABA is ambiguous. We evaluated the effect of endogenous ABA, hydrogen peroxide (H2 O2 ), nitric oxide (NO), and Ca2+ , low and high light intensities, and blue light (BL) on stomatal opening of Pleopeltis polypodioides. METHODS: Endogenous ABA was quantified using gas chromatography-mass spectrometry; microscopy results and stomatal responses to light and chemical treatments were analyzed with Image J. RESULTS: The ABA content increases during initial dehydration, peaks at 15 h and then decreases to one fourth of the ABA content of hydrated fronds. Following rehydration, ABA content increases within 24 h to the level of hydrated tissue. The stomatal aperture opens under BL and remains open even in the presence of ABA. Closure was strongly affected by BL, NO, and Ca2+ , regardless of ABA, H2 O2 effect was weak. CONCLUSIONS: The decrease in the ABA content during extended dehydration and insensitivity of the stomata to ABA suggests that the drought tolerance mechanism of Pleopeltis polypodioides is independent of ABA.

The role of peltate scales in desiccation tolerance of Pleopeltis polypodioides.

MAIN CONCLUSION: The extreme drought tolerance of the resurrection fern is in part the result of the dorsal scales that assist in water distribution and controlled desiccation. We studied the effect of peltate scales on water uptake and loss of the desiccation-tolerant epiphytic fern Pleopeltis polypodioides using optical and FTIR microscopy and staining with calcofluor, solophenyl flavine7GFE, and Ruthenium Red. We provide information on structure, property, and function of the scales by measuring water uptake and dehydration, contact angles, and metabolic activity. Peltate scales mainly contain cellulose, xylogalactans, and pectin. Water is absorbed from the center of scales, and the overlapping arrangement of scales facilitates surface spreading of water. Intact fronds hydrated fully within 5 h of imbibition of the apical pinna, without scales water uptake stopped after 1 h. Hydration rates via rhizomes followed a longer time course but also improved in the presence of scales. Fronds with and without scales lost half of their water content in 15 or 4 h, respectively. The overall metabolism of rapidly dehydrated fronds was significantly reduced compared with slowly dehydrated fronds. Thus, water management and metabolism of Pleopeltis are dependent on surface properties determined by peltate scales.

Assessing Radish Health during Space Cultivation by Gene Transcription.

During the Advanced Plant Habitat experiment 2, radish plants were grown in two successive grow-outs on the International Space Station (ISS) for 27 days each. On days 10, 18, and 24, leaf punch (LP) samples were collected and frozen. At harvest, bulb tissue was sampled with oligo-dT functionalized Solid Phase Gene Extraction (SPGE) probes. The space samples were compared with samples from ground controls (GC) grown at the Kennedy Space Center (KSC) under the same conditions as on the ISS, with notably elevated CO2 (about 2500 ppm), and from lab plants grown under atmospheric CO2 but with light and temperature conditions similar to the KSC control. Genes corresponding to peroxidase (RPP), glucosinolate biosynthesis (GIS), protein binding (CBP), myrosinase (RMA), napin (RSN), and ubiquitin (UBQ) were measured by qPCR. LP from day 24 and bulb samples collected at harvest were compared with RNA-seq data from material that was harvested, frozen, and analyzed after return to Earth. The results showed stable transcription in LP samples in GC but decreasing values in ISS samples during both grow-outs, possibly indicative of stress. SPGE results were similar between GC and ISS samples. However, the RNA-seq analyses showed different transcription profiles than SPGE or LP results, possibly related to localized sampling. RNA-seq of leaf samples showed greater variety than LP data, possibly because of different sampling times. RSN and RPP showed the lowest transcription regardless of method. Temporal analyses showed relatively small changes during plant development in space and in ground controls. This is the first study that compares developmental changes in space-grown plants with ground controls based on a comparison between RNA-seq and qPCR analyses.

Intranasal parainfluenza virus type 5 (PIV5)-vectored RSV vaccine is safe and immunogenic in healthy adults in a phase 1 clinical study.

Respiratory syncytial virus (RSV) can lead to serious disease in infants, and no approved RSV vaccine is available for infants. This first in-human clinical trial evaluated a single dose of BLB201, a PIV5-vectored RSV vaccine administrated via intranasal route, for safety and immunogenicity in RSV-seropositive healthy adults (33 to 75 years old). No severe adverse events (SAEs) were reported. Solicited local and systemic AEs were reported by <50% of participants and were mostly mild in intensity. Vaccine virus shedding was detected in 17% of participants. Nasal RSV-specific immunoglobulin A responses were detected in 48%, the highest level observed in adults among all intranasal RSV vaccines evaluated in humans. RSV-neutralizing antibodies titers in serum rose ≥1.5-fold. Peripheral blood RSV F-specific CD4+ and CD8+ T cells increased from ≤0.06% at baseline to ≥0.26 and 0.4% after vaccination, respectively, in >93% participants. The safety and immunogenicity profile of BLB201 in RSV-seropositive adults supports the further clinical development of BLB201.

Desiccation Mitigates Heat Stress in the Resurrection Fern, Pleopeltis polypodioides.

Although heat and desiccation stresses often coincide, the response to heat especially in desiccation tolerant plants is rarely studied. We subjected hydrated Pleopeltis polypodioides fronds to temperatures up to 50°C and dehydrated fronds up to 65°C for 24 h. The effect of heat stress was evaluated using morphological changes, photosystem (PS) II efficiency, and metabolic indicators. Pinnae of dried fronds exposed to more than 40°C curled tighter and became brittle compared to fronds dried at lower temperatures. Exposure to > 50°C leads to discolored fronds after rehydration. Hydrated fronds turned partially brown at > 35°C. Chlorophyll fluorescence (Ft) and quantum yield (Qy) increased following re-hydration but the recovery process after 40°C treatment lasted longer than at lower temperatures. Similarly, hydrated fronds showed reduced Qy when exposed to > 40°C. Dried and hydrated fronds remained metabolically active up to 40°C. Hydroperoxides and lipid hydroperoxides in dried samples remained high up to 50°C, but decreased in hydrated fronds at > 40°C. Catalase (CAT) and glutathione (GSH) oxidizing activities remained high up to 40°C in dehydrated fronds and up to 35°C in hydrated fronds. Major fatty acids detected in both dehydrated and hydrated fronds included palmitic (C16:0) and stearic (C18:0) acids, oleic (18:1), linoleic (C18:2); and linolenic (C18:3) acids. Linolenic acid was most abundant. In dried fronds, all fatty acids decreased at > 35°C. The combined data indicate that the thermotolerance of dry fronds is about 55°C but is at least 10°C lower for hydrated fronds.

Biochemical responses of the desiccation-tolerant resurrection fern Pleopeltis polypodioides to dehydration and rehydration.

The epiphytic fern Pleopeltis polypodioides can tolerate repeated drying and rehydration events without conspicuous damage. To understand the biochemical principles of drought-tolerance, we analyzed the effect of dehydration and rehydration at 25 °C on hydroperoxide and lipid hydroperoxide, the activities of antioxidative (catalase and glutathione-oxidizing) enzymes and evaluated changes in fatty acid composition and saturation levels. Dehydration increased peroxide concentration and the activity of glutathione oxidases, but reduced catalase activity. During dehydration, the biosynthesis of palmitic (C16:0), linoleic (C18:2), linolenic (C18:3) and stearic acid (C18:0) increased 18, 12, 20, and 8-fold, respectively. In contrast, rehydration lowered levels of peroxides, the activity of glutathione-oxidizing enzymes, and fatty acids but increased catalase activity. The coordinated changes during de- and rehydration suggest that lipids and oxidative and antioxidative enzymes are components of the drought-resistance system.

Effects of mechanostimulation on gravitropism and signal persistence in flax roots.

Gravitropism describes curvature of plants in response to gravity or differential acceleration and clinorotation is commonly used to compensate unilateral effect of gravity. We report on experiments that examine the persistence of the gravity signal and separate mechanostimulation from gravistimulation. Flax roots were reoriented (placed horizontally for 5, 10 or 15 min) and clinorotated at a rate of 0.5 to 5 rpm either vertically (parallel to the gravity vector and root axis) or horizontally (perpendicular to the gravity vector and parallel to the root axis). Image sequences showed that horizontal clinorotation did not affect root growth rate (0.81 ± 0.03 mm h-1) but vertical clinorotation reduced root growth by about 7%. The angular velocity (speed of clinorotation) did not affect growth for either direction. However, maximal curvature for vertical clinorotation decreased with increasing rate of rotation and produced straight roots at 5 rpm. In contrast, horizontal clinorotation increased curvature with increasing angular velocity. The point of maximal curvature was used to determine the longevity (memory) of the gravity signal, which lasted about 120 min. The data indicate that mechanostimulation modifies the magnitude of the graviresponse but does not affect memory persistence.

Incidence of agenesis of palmaris longus in the Andhra population of India.

BACKGROUND: The knowledge of Palmaris longus (PL) is a growing interest for its wide role in reconstructive plastic surgeries as a donor tendon for transfer or transplant. The prevalence of the PL agenesis has been well-documented by many authors in different ethnic groups or populations. Many conventional tests for determining the presence of the PL has been described, but lamentably there are many discrepancies in confirming its presence or absence. Slight modifications of the prevailing methods can still give authenticate results. AIM: This prospective study was conducted to determine the incidence of unilateral and bilateral agenesis of PL and its association with sex and side of the limb in the Andhra population of India. MATERIALS AND METHODS: A total of 942 subjects of both sexes belonging to 18-23 years were used to access the PL using various tendon examination techniques including our modified Schaeffer's test. The data collected were analyzed by Pearsons χ(2) test using SPSS software. RESULTS: Overall agenesis of muscle in both sexes was 264 (28.0%), out of which 40.2% was seen in females and 14.7% in males with the ratio of 3:1. The unilateral agenesis was seen in 70.5% and bilateral agenesis in 29.5% subjects. The left side agenesis was seen in 51.6% and right side in 48.4% subjects. CONCLUSIONS: The prevalence of bilateral and unilateral agenesis was more common on left side with a greater likelihood in the female subjects. The proposed technique could bring better results in all subjects and can be implemented in manual examination of PL.