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Weightlessness during spaceflight can harm various bodily systems, including bone density, muscle mass, strength and cognitive functions. Exercise appears to somewhat counteract these effects. A terrestrial model for this is head‐down bedrest (HDBR), simulating gravity loss. This mirrors challenges faced by older adults in extended bedrest and space environments. The first Canadian study, backed by the Canadian Space Agency, Canadian Institutes of Health Research, and Canadian Frailty Network, aims to explore these issues. The study seeks to: (1) scrutinize the impact of 14‐day HDBR on physiological, psychological and neurocognitive systems, and (2) assess the benefits of exercise during HDBR. Eight teams developed distinct protocols, harmonized in three videoconferences, at the McGill University Health Center. Over 26 days, 23 participants aged 55–65 underwent baseline measurements, 14 days of −6° HDBR, and 7 days of recovery. Half did prescribed exercise thrice daily combining resistance and endurance exercise for a total duration of 1 h. Assessments included demographics, cardiorespiratory fitness, bone health, body composition, quality of life, mental health, cognition, muscle health and biomarkers. This study has yielded some published outcomes, with more forthcoming. Findings will enrich our comprehension of HDBR effects, guiding future strategies for astronaut well‐being and aiding bedrest‐bound older adults. By outlining evidence‐based interventions, this research supports both space travellers and those enduring prolonged bedrest.

Bed rest accelerates bone loss and may exacerbate skeletal fragility. This study examined the effects of 14 days of head-down tilt bed rest (HDBR) with or without exercise, and subsequent recovery, on bone turnover, density and structure in older adults. Twenty-two healthy older adults (55-65 years) completed the HDBR protocol. Participants were randomized to a control group that received passive physiotherapy (CON, n = 11) or a group that performed daily exercise (EX, n = 11). Serum biomarkers of bone formation (procollagen type 1 N-terminal propeptide (P1NP) and bone-specific alkaline phosphatase (BSAP)), resorption (N-terminal cross-linked telopeptide of type I collagen (NTX) and C-terminal cross-linked telopeptide of type I collagen (CTX)), and osteocalcin were measured at baseline (BDC4), day-9 (HDT9), and immediately (R1), 4 weeks (4W), and 4 months (4M) post-HDBR. Bone mineral density (BMD) was assessed via dual-energy X-ray absorptiometry (DXA) at BDC4, R1, 4W and 4M. Femoral bone structure was measured via peripheral quantitative computed tomography (pQCT) at BDC4 and R1. CTX and NTX increased at R1 vs. BDC4 (time: P < 0.001), while P1NP and BSAP increased at 4W and 4M (time: P < 0.001). No DXA-derived BMD changes occurred. pQCT revealed reduced femoral trabecular volumetric BMD at 4% (EX: 342.3 ± 7.8 to 337.9 ± 8.0 mg/cm ; CON: 329.3 ± 8.1 to 326.4 ± 8.4 mg/cm ; time: P = 0.05) and cortical volumetric BMD at 25% (EX: 1089.5 ± 6.7 to 1087.5 ± 7.1 mg/cm ; CON: 1102.7 ± 6.7 to 1095.7 ± 7.1 mg/cm ; time: P = 0.05). However, changes were within the precision error of pQCT measurements. Fourteen days of HDBR, with or without exercise, increased biomarkers of bone resorption but did not alter BMD or bone structure.

In vegetative leaf tissues, cuticles including cuticular waxes are important for protection against nonstomatal water loss and pathogen infection as well as for adaptations to environmental stress. However, their roles in the anther wall are rarely studied. The innermost layer of the anther wall (the tapetum) is essential for generating male gametes. Here, we report the characterization of a T-DNA insertional mutant in the Wax-deficient anther1 (Wda1) gene of rice (Oryza sativa), which shows significant defects in the biosynthesis of very-long-chain fatty acids in both layers. This gene is strongly expressed in the epidermal cells of anthers. Scanning electron microscopy analyses showed that epicuticular wax crystals were absent in the outer layer of the anther and that microspore development was severely retarded and finally disrupted as a result of defective pollen exine formation in the mutant anthers. These biochemical and developmental defects in tapetum found in wda1 mutants are earlier events than those in other male-sterile mutants, which showed defects of lipidic molecules in exine. Our findings provide new insights into the biochemical and developmental aspects of the role of waxes in microspore exine development in the tapetum as well as the role of epicuticular waxes in anther expansion.

The outermost epidermal cell wall is specialized to withstand pathogens and natural stresses, and lipid-based cuticular polymers are the major barrier against incursions. The Arabidopsis thaliana mutant bodyguard (bdg), which exhibits defects characteristic of the loss of cuticle structure not attributable to a lack of typical cutin monomers, unexpectedly accumulates significantly more cell wall-bound lipids and epicuticular waxes than wild-type plants. Pleiotropic effects of the bdg mutation on growth, viability, and cell differentiation are also observed. BDG encodes a member of the [alpha]/{szligbeta}-hydrolase fold protein superfamily and is expressed exclusively in epidermal cells. Using Strep-tag epitope-tagged BDG for mutant complementation and immunolocalization, we show that BDG is a polarly localized protein that accumulates in the outermost cell wall in the epidermis. With regard to the appearance and structure of the cuticle, the phenotype conferred by bdg is reminiscent of that of transgenic Arabidopsis plants that express an extracellular fungal cutinase, suggesting that bdg may be incapable of completing the polymerization of carboxylic esters in the cuticular layer of the cell wall or the cuticle proper. We propose that BDG codes for an extracellular synthase responsible for the formation of cuticle. The alternative hypothesis proposes that BDG controls the proliferation/differentiation status of the epidermis via an unknown mechanism.

In plants, extracellular matrix polymers built from polysaccharides and cuticular lipids have structural and protective functions. The cuticle is found to be ten times thinner in Arabidopsis thaliana (L.) Heynh than in many other plants, and there is evidence that it is unusual in having a high content of α-,ω-dicarboxylic fatty acids (FAs) in its polyesters. We designated the new organ fusion mutant hth-12 after it appeared to be allelic to adhesion of calyx edges (ace) and hothead (hth), upon molecular cloning of the gene by transposon tagging. This mutant is deficient in its ability to oxidize long-chain ω-hydroxy FAs to ω-oxo FAs, which results in leaf polyesters in decreased α-,ω-dicarboxylic FAs and increased ω-hydroxy FAs. These chemical phenotypes lead to disorder of the cuticle membrane structure in hth-12. ACE/HTH is a single-domain protein showing sequence similarity to long-chain FA ω-alcohol dehydrogenases from Candida species, and we hypothesize that it may catalyze the next step after cytochrome P450 FA ω-hydroxylases in the ω-oxidation pathway. We show that ACE/HTH is specifically expressed in epidermal cells. It appears very likely therefore that the changes in the amount of α-,ω-dicarboxylic FAs in hth-12 reflect the different composition of cuticular polyesters. The ACE/HTH gene is also expressed in root epidermal cells which do not form a polyester membrane on the exterior surface, thereby making it possible that the end products of the pathway, α-,ω-dicarboxylic FAs, are generally required for the cross-linking that ensures the integrity of the outer epidermal cell wall.

The aim of this study was to determine the impact of inter-professional teaching on the application of ergonomic operator and patient positioning. A randomized case-control study was conducted with 83 first-year dental students at the UNC Chapel Hill Adams School of Dentistry. Forty-nine percent (n=41) of the students solicited participated. All students participated in a didactic lecture on ergonomics, along with a pre-clinical practice session with peer patients. During the clinical practice session students in the case group received ten minutes of one-on-one individualized instruction. Two weeks later, all students were assessed using a rubric on operator and patient positioning, while simulating restorative work. There was a statistically significant difference between the two groups with respect to the composite ergonomic compliance score (p=0.005), operator shoulder abduction position (p=0.03), and lateral flexion of the spinal column (p=0.02). Hands-on individualized instruction positively effects ergonomic compliance.

Abundant data are available on the ages of perennial seed plants, but we know little about the longevity of ferns. In this study we estimated the ages of 30 colonies of Osmunda claytoniana (Interrupted Fern). Common in the Monongahela National Forest of northeastern West Virginia, Interrupted Ferns typically form convexly bulging, elliptically shaped colonies. We studied colonies larger than 6.6 ft (2 m) in average diameter. Each colony was comprised of dozens of ramets interconnected by a subsurface, dichotomously branching rhizome system. The fronds' stipe bases persist through the colony's life, endure along the entire length of the rhizome, and extend back to the origin of the colony's founding ramet. We estimated the age of a fern colony by dividing the average radius of the colony by the growth rate of its rhizomes. We estimated rhizome growth rate by dividing the average number of stipe bases per length of rhizome by the average number of fronds generated by an individual ramet per year. Rhizome growth rates varied from 0.04 to 0.24 in (0.1–0.6 cm) per year, which represents a slow outward expansion by colonies. Our observational data and derived estimates indicated that these colonies were as old as 414 years. If our estimates are accurate, the Interrupted Fern may be one of the longest-lived organisms in the Appalachian Mountains.

Very-long-chain fatty acids (VLCFAs) are important functional components of various lipid classes, including cuticular lipids in the higher plant epidermis and lipid-derived second messengers. Here, we report the characterization of transgenic Arabidopsis thaliana plants that epidermally express FATTY ACID ELONGATION1 (FAE1), the seed-specific β-ketoacyl-CoA synthase (KCS) catalyzing the first rate-limiting step in VLCFA biosynthesis. Misexpression of FAE1 changes the VLCFAs in different classes of lipids but surprisingly does not complement the KCS fiddlehead mutant. FAE1 misexpression plants are similar to the wild type but display an essentially glabrous phenotype, owing to the selective death of trichome cells. This cell death is accompanied by membrane damage, generation of reactive oxygen species, and callose deposition. We found that nuclei of arrested trichome cells in FAE1 misexpression plants cell-autonomously accumulate high levels of DNA damage, including double-strand breaks characteristic of lipoapoptosis. A chemical genetic screen revealed that inhibitors of KCS and phospholipase A2 (PLA2), but not inhibitors of de novo ceramide biosynthesis, rescue trichome cells from death. These results support the functional role of acyl chain length of fatty acids and PLA2 as determinants for programmed cell death, likely involving the exchange of VLCFAs between phospholipids and the acyl-CoA pool.