Electronic Band Structure and Optical Properties of HgPS3 Crystal and Layers.

Transition metal thiophosphates (MPS3) are of great interest due to their layered structure and magnetic properties. Although HgPS3 may not exhibit magnetic properties, its uniqueness lies in its triclinic crystal structure and in the substantial mass of mercury, rendering it a compelling subject for exploration in terms of fundamental properties. In this work, we present comprehensive experimental and theoretical studies of the electronic band structure and optical properties for the HgPS3 crystal and mechanically exfoliated layers from a solid crystal. Based on absorption, reflectance and photoluminescence measurements supported by theoretical calculations, it is shown that the HgPS3 crystal has an indirect gap of 2.68 eV at room temperature. The direct gap is identified at the Γ point of the Brillouin zone (BZ) ≈ 50 meV above the indirect gap. The optical transition at the Γ point is forbidden due to selection rules, but the oscillator strength near the Γ point increases rapidly and therefore the direct optical transitions are visible in the reflectance spectra approximately at 60-120 meV above the absorption edge, across the temperature range of 40 to 300 K. The indirect nature of the bandgap and the selection rules for Γ point contribute to the absence of near-bandgap emission in HgPS3. Consequently, the photoluminescence spectrum is primarily governed by defect-related emission. The electronic band structure of HgPS3 undergoes significant changes when the crystal thickness is reduced to tri- and bilayers, resulting in a direct bandgap. Interestingly, in the monolayer regime, the fundamental transition is again indirect. The layered structure of the HgPS3 crystal was confirmed by scanning electron microscopy (SEM) and by mechanical exfoliation.

Inducing Angiogenesis in the Nucleus Pulposus.

Bone morphogenetic protein (BMP) gene delivery to Lewis rat lumbar intervertebral discs (IVDs) drives bone formation anterior and external to the IVD, suggesting the IVD is inhospitable to osteogenesis. This study was designed to determine if IVD destruction with a proteoglycanase, and/or generating an IVD blood supply by gene delivery of an angiogenic growth factor, could render the IVD permissive to intra-discal BMP-driven osteogenesis and fusion. Surgical intra-discal delivery of naïve or gene-programmed cells (BMP2/BMP7 co-expressing or VEGF165 expressing) +/- purified chondroitinase-ABC (chABC) in all permutations was performed between lumbar 4/5 and L5/6 vertebrae, and radiographic, histology, and biomechanics endpoints were collected. Follow-up anti-sFlt Western blotting was performed. BMP and VEGF/BMP treatments had the highest stiffness, bone production and fusion. Bone was induced anterior to the IVD, and was not intra-discal from any treatment. chABC impaired BMP-driven osteogenesis, decreased histological staining for IVD proteoglycans, and made the IVD permissive to angiogenesis. A soluble fragment of VEGF Receptor-1 (sFlt) was liberated from the IVD matrix by incubation with chABC, suggesting dysregulation of the sFlt matrix attachment is a possible mechanism for the chABC-mediated IVD angiogenesis we observed. Based on these results, the IVD can be manipulated to foster vascular invasion, and by extension, possibly osteogenesis.

Predictors for pharmacological therapy and perinatal outcomes with metformin treatment in women with gestational diabetes.

Background: The prevalence of gestational diabetes mellitus (GDM) has been increasing in Australia and worldwide. The study aims were to examine, in comparison with dietary intervention, perinatal outcomes for women with gestational diabetes who were attending a single hospital clinic and to identify predictors for their pharmacological GDM treatment. Methods: A prospective, observational study of women with GDM, treated with "Diet, N= 50", "Metformin, N = 35", "Metformin and Insulin, N = 46" or "Insulin, N = 20". Findings: The mean BMI for the whole cohort was 25.8 ± 4.7 kg/m2. The Metformin group, compared to the Diet group, had OR=3.1 (95% CI:1.13 to 8.25) for caesarean section birth (LSCS) compared to normal vaginal birth mode with no longer such a significant association after controlling for the number of their elective LSCS. The insulin treated group had the highest number of small for gestational age neonates (20%, p<0.05) with neonatal hypoglycaemia (25%, p< 0.05). Fasting glucose value on oral GTT (glucose tolerance test) was the strongest predictor for a pharmacological intervention requirement with OR = 2.77 (95CI%: 1.16 to 6.61), followed by timing of OGTT with OR=0.90 (95% CI: 0.83 to 0.97) and previous pregnancy loss with OR=0.28 (95% CI:0.10 to 0.74). Interpretation: These data suggest that metformin may be a safe alternative treatment to insulin treatment in GDM. Raised fasting glucose on oral GTT was the strongest indicator that GDM women with BMI < 35 kg/m2 may require pharmacological therapy. Further studies are needed to identify the most effective and safe management of gestational diabetes within the public hospital setting. Australian New Zealand Clinical Trial Registry ANZCTR Trial Id: ACTRN12620000397910.

Zbtb20 identifies and controls a thymus-derived population of regulatory T cells that play a role in intestinal homeostasis.

The expression of BTB-ZF transcription factors such as ThPOK in CD4+ T cells, Bcl6 in T follicular helper cells, and PLZF in natural killer T cells defines the fundamental nature and characteristics of these cells. Screening for lineage-defining BTB-ZF genes led to the discovery of a subset of T cells that expressed Zbtb20. About half of Zbtb20+ T cells expressed FoxP3, the lineage-defining transcription factor for regulatory T cells (Tregs). Zbtb20+ Tregs were phenotypically and genetically distinct from the larger conventional Treg population. Zbtb20+ Tregs constitutively expressed mRNA for interleukin-10 and produced high levels of the cytokine upon primary activation. Zbtb20+ Tregs were enriched in the intestine and specifically expanded when inflammation was induced by the use of dextran sodium sulfate. Conditional deletion of Zbtb20 in T cells resulted in a loss of intestinal epithelial barrier integrity. Consequently, knockout (KO) mice were acutely sensitive to colitis and often died because of the disease. Adoptive transfer of Zbtb20+ Tregs protected the Zbtb20 conditional KO mice from severe colitis and death, whereas non-Zbtb20 Tregs did not. Zbtb20 was detected in CD24hi double-positive and CD62Llo CD4 single-positive thymocytes, suggesting that expression of the transcription factor and the phenotype of these cells were induced during thymic development. However, Zbtb20 expression was not induced in "conventional" Tregs by activation in vitro or in vivo. Thus, Zbtb20 expression identified and controlled the function of a distinct subset of Tregs that are involved in intestinal homeostasis.

Single Nucleotide Polymorphisms of Interleukins and Toll-like Receptors and Neuroimaging Results in Newborns with Congenital HCMV Infection.

Congenital cytomegalovirus infection (cCMV) is the most common intrauterine infection with central nervous system (CNS) involvement. There is limited data on the associations between Single Nucleotide Polymorphisms (SNPs) in genes involving the first-line defense mechanism and the risk of CNS damage during cCMV. We investigated the associations between neuroimaging findings and SNPs in genes encoding the following cytokines and cytokine receptors in 92 infants with cCMV: interleukins (IL1B rs16944, IL12B rs3212227, IL28B rs12979860), C-C motif chemokine ligand 2 (CCL2 rs1024611), dendritic cell-specific intercellular adhesion grabbing non-integrin (DC-SIGN rs735240), Toll-like receptors (TLR2 rs5743708, TLR4 rs4986791, TLR9 rs352140). The SNP of IL1B rs16944 (G/A) was associated with a reduced risk of ventriculomegaly on MRI (OR = 0.46, 95% CI, 0.22-0.95; p = 0.03) and cUS (OR = 0.38, 95% CI, 0.0-0.93; p = 0.034). Infants carrying heterozygous (T/C) genotype at IL28B rs12979860 had an increased risk of cystic lesions on cUS (OR = 3.31, 95% CI, 1.37-8.01; p = 0.0064) and MRI (OR = 4.97, 95% CI, 1.84-13.43; p = 0.001), and an increased risk of ventriculomegaly on MRI (OR = 2.46, 95% CI, 1.03-5.90; p = 0.04). No other associations between genotyped SNPs and neuroimaging results were found. This is the first study demonstrating new associations between SNPs of IL1B and IL28B and abnormal neuroimaging in infants with cCMV.

Quetiapine for primary insomnia: Consider the risks.

The second-generation antipsychotic drug quetiapine (Seroquel) is increasingly being used off-label for treating insomnia in the general population, possibly to avoid standard medications with known addictive qualities and adverse side effects. However, evidence to support using it in this way is scant, and quetiapine is associated with weight gain and other metabolic effects. It must be used cautiously and with appropriate monitoring for adverse effects and abuse.

Activation of nuclear factor-kappa B by TNF promotes nucleus pulposus mineralization through inhibition of ANKH and ENPP1.

Spontaneous mineralization of the nucleus pulposus (NP) has been observed in cases of intervertebral disc degeneration (IDD). Inflammatory cytokines have been implicated in mineralization of multiple tissues through their modulation of expression of factors that enable or inhibit mineralization, including TNAP, ANKH or ENPP1. This study examines the underlying factors leading to NP mineralization, focusing on the contribution of the inflammatory cytokine, TNF, to this pathologic event. We show that human and bovine primary NP cells express high levels of ANKH and ENPP1, and low or undetectable levels of TNAP. Bovine NPs transduced to express TNAP were capable of matrix mineralization, which was further enhanced by ANKH knockdown. TNF treatment or overexpression promoted a greater increase in mineralization of TNAP-expressing cells by downregulating the expression of ANKH and ENPP1 via NF-κB activation. The increased mineralization was accompanied by phenotypic changes that resemble chondrocyte hypertrophy, including increased RUNX2 and COL10A1 mRNA; mirroring the cellular alterations typical of samples from IDD patients. Disc organ explants injected with TNAP/TNF- or TNAP/shANKH-overexpressing cells showed increased mineral content inside the NP. Together, our results confirm interactions between TNF and downstream regulators of matrix mineralization in NP cells, providing evidence to suggest their participation in NP calcification during IDD.

Insulinoma in pregnancy (a case presentation and systematic review of the literature).

Insulinomas are rare, benign and functional tumors that coincidentally may become overt during pregnancy or in the post-partum period. As the general symptoms of a pregnancy might cover the clinical presentation, diagnosing remains challenging. We present one additional case of a post-partum insulinoma, combined with a systematic review of the literature to sum up relevant details in diagnosis and treatment. A systematic request of Pubmed/Medline was conducted using the following terms: "insulinoma AND pregnancy" and "insulinoma" for a second request of ClinicalTrials.gov. All publications concerning pregnant or post-partum women with insulinoma were included. Thirty-six cases could be identified for analysis. Each publication was reviewed for demographic, diagnostic and therapeutic data. The most frequent clinical signs were unconsciousness and neurological symptoms. 64.9% were diagnosed during early pregnancy and 35.1% post-partum. 91.9% underwent surgery with a third resected during pregnancy without severe influence on fetal or maternal outcome. Three patients died of metastatic disease or misdiagnosing, two of them miscarried. Insulinoma in pregnancy is rare but should be considered in case of unclear hyperinsulinemic hypoglycemia. Surgery can be performed during the second trimester or post-partum with promising outcome.

Evaluation of physiologic and abnormal glucose uptake in palatine tonsils: differential diagnostics with sequential dual-time-point 2-deoxy-2-[18F]FDG PET/CT.

BACKGROUND: The aim of this article was to evaluate the usefulness of sequential dual-time-point 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography/computed tomography (DTP [18F]FDG PET/CT) in distinguishing physiologic, inflammatory and malignant palatine tonsils as difficult to differentiate in the oncological practice. METHODS: A total of 90 patients before the treatment underwent sequential DTP [18F]FDG PET/CT examinations. We analyzed 104 structures in 90 patients: 31 physiologic tonsils, 28 histopathologically confirmed inflammatory tonsils of non-specified origin, 31 histopathologically confirmed palatine tonsils cancer and 14 non-malignant contralateral tonsils in patients with histopathologically confirmed unilateral palatine tonsil malignancy. Patients underwent sequential [18F]FDG PET/CT examinations at 60 and 90 minutes post-injection of the [18F]FDG. We analyzed the SUVmax and SUVmean values at 60 and 90 minutes post-injection changes over time and the Retention Index (RI-SUVmax). To find the predictive SUV value and the RI cut-off between physiology, inflammatory and malignancy, we used the ROC analysis. RESULTS: The average SUVmax values at 60 and 90minutes post-injection within physiologic palatine tonsils were 1.36±0.26 and 1.31±0.26, respectively, P>0.05. The average SUVmax values at 60 and 90 minutes post-injection within inflammatory and malignant tonsils were 3.74±1.45, 3.80±1.47 (P>0.05) and 5.19±2.19, 5.81±2.50 (P<0.05), respectively. The RI-SUVmax fluctuation over time were 5±28% within physiologic, -4±11% within contralateral non-malignant tonsils in patients with one tonsil involved, 2±11% within inflammatory and 13±13% within malignant tonsils. CONCLUSIONS: The sequential dual-time-point [18F]FDG PET/CT examinations may increase the sensitivity and the specificity of the PET/CT method in differential palatine tonsils diagnosis.

An on-line support tool to reduce exercise-related hypoglycaemia and improve confidence to exercise in type 1 diabetes.

OBJECTIVE: Hypoglycaemia related to exercise and lack of confidence to exercise, are common in T1DM. An online educational exercise tool (ExT1D) was tested to determine whether these parameters can be improved. RESEARCH DESIGN AND METHODS: Thirty two adults with T1DM (50%M, age 35.8 ±â€¯9.5 yr diabetes duration 12.3 ±â€¯9.9 yr, median HbA1c 7.1%[ICR 6.4-7.7] NGSPU) exercising ≥ 60 min/week enrolled in a RCT utilising ExT1D, with partial cross-over design. The primary end-point was Exercise-related hypoglycaemia (ErH) number corrected for exercise session number, with ErH defined as CGM episodes < 4.0 mM occurring within 24 h of exercise. Secondary RCT endpoints were total ErH duration, and ErH duration/episode. A pre-defined longitudinal analysis with each subject compared with their baseline was also undertaken, for the three ErH parameters, and using fear of hypoglycaemia questionnaires. RESEARCH: In the RCT a 50% lower median ErH number (P = 0.6) (37% lower ErH number per exercise session (P = 0.06, NS primary endpoint) occurred in the Intervention vs Control group. A 49% lower ErH duration per episode (P = 0.2), and 80% less ErH duration (P = 0.3), were also observed in the Intervention vs Control group. In the longitudinal study, ErH number reduced by 43% (P = 0.088), ErH duration per episode by 52% (P = 0.157) and total duration of ErH fell by 71% (P = 0.015). Confidence to prevent glucose lowering by exercise also improved (P = 0.039). Post-hoc analysis showed those with the greatest ErH events at baseline benefited most. Fructosamine and HbA1c levels were unchanged from baseline. CONCLUSIONS: ExT1D can reduce exercise-related hypoglycaemia and provide greater confidence to exercise.

HSFA2 Functions in the Physiological Adaptation of Undifferentiated Plant Cells to Spaceflight.

Heat Shock Factor A2 (HsfA2) is part of the Heat Shock Factor (HSF) network, and plays an essential role beyond heat shock in environmental stress responses and cellular homeostatic control. Arabidopsis thaliana cell cultures derived from wild type (WT) ecotype Col-0 and a knockout line deficient in the gene encoding HSFA2 (HSFA2 KO) were grown aboard the International Space Station (ISS) to ascertain whether the HSF network functions in the adaptation to the novel environment of spaceflight. Microarray gene expression data were analyzed using a two-part comparative approach. First, genes differentially expressed between the two environments (spaceflight to ground) were identified within the same genotype, which represented physiological adaptation to spaceflight. Second, gene expression profiles were compared between the two genotypes (HSFA2 KO to WT) within the same environment, which defined genes uniquely required by each genotype on the ground and in spaceflight-adapted states. Results showed that the endoplasmic reticulum (ER) stress and unfolded protein response (UPR) define the HSFA2 KO cells' physiological state irrespective of the environment, and likely resulted from a deficiency in the chaperone-mediated protein folding machinery in the mutant. Results further suggested that additional to its universal stress response role, HsfA2 also has specific roles in the physiological adaptation to spaceflight through cell wall remodeling, signal perception and transduction, and starch biosynthesis. Disabling HsfA2 altered the physiological state of the cells, and impacted the mechanisms induced to adapt to spaceflight, and identified HsfA2-dependent genes that are important to the adaption of wild type cells to spaceflight. Collectively these data indicate a non-thermal role for the HSF network in spaceflight adaptation.

Improved timed-mating, non-invasive method using fewer unproven female rats with pregnancy validation via early body mass increases.

For studies requiring accurate conception-timing, reliable, efficient methods of detecting oestrus reduce time and costs, whilst improving welfare. Standard methods use vaginal cytology to stage cycle, and breeders are paired-up using approximately five proven females with proven males to achieve at least one conception on a specific day. We describe an alternative, fast, consistent, non-invasive method of timed-mating using detection of lordosis behaviour in Wistar and Lister-Hooded rats that used unproven females with high success rates. Rats under reverse lighting had body masses recorded pre-mating, day (d) 3-4, d8, d10 and d18 of pregnancy. Using only the presence of the oestrus dance to time-mate females for 24 hours, 89% of Wistar and 88% of Lister-Hooded rats successfully conceived. We did not observe behavioural oestrus in Sprague-Dawleys without males being present. Significant body mass increases following mating distinguished pregnant from non-pregnant rats, as early as d4 of pregnancy (10% ± 1.0 increase cf. 3% ± 1.2). The pattern of increases throughout gestation was similar for all pregnant rats until late pregnancy, when there were smaller increases for primi- and multiparous rats (32% ± 2.5; 25% ± 2.4), whereas nulliparous rats had highest gains (38% ± 1.5). This method demonstrated a distinct refinement of the previous timed-mating common practice used, as disturbance of females was minimised. Only the number required of nulli-, primi- or multiparous rats were mated, and body mass increases validated pregnancy status. This new breeding management method is now established practice for two strains of rat and has resulted in a reduction in animal use.

Characterization of two groups of Spodoptera exigua Hübner (Lepidoptera: Noctuidae) C-type lectins and insights into their role in defense against the densovirus JcDV.

Insect innate immunity relies on numerous soluble and membrane-bound receptors, named pattern recognition proteins (PRPs), which enable the insect to recognize pathogen-associated molecular patterns. C-type lectins are among the best-studied PRPs and constitute the most diverse family of animal lectins. Here we have characterized two groups of Spodoptera exigua C-type lectins that differ in their phylogeny, domain architecture, and expression pattern. One group includes C-type lectins with similar characteristics to other lepidopteran lectins, and a second group includes bracoviral-related lectins (bracovirus-like lectins, Se-BLLs) recently acquired by horizontal gene transfer. Subsequently, we have investigated the potential role of some selected lectins in the susceptibility to Junonia coenia densovirus (JcDV). For this purpose, three of the bracoviral-related lectins were expressed, purified, and their effect on the densovirus infection to two different Spodoptera species was assessed. The results showed that Se-BLL3 specifically reduce the mortality of Spodoptera frugiperda larvae caused by JcDV. In contrast, no such effect was observed with S. exigua larvae. In a previous work, we have also shown that Se-BLL2 increased the tolerance of S. exigua larvae to baculovirus infection. Taken together, these results confirm the implication of two different C-type lectins in antiviral response and reflect the biological relevance of the acquisition of bracoviral genes in Spodoptera spp.

ARG1 Functions in the Physiological Adaptation of Undifferentiated Plant Cells to Spaceflight.

Scientific access to spaceflight and especially the International Space Station has revealed that physiological adaptation to spaceflight is accompanied or enabled by changes in gene expression that significantly alter the transcriptome of cells in spaceflight. A wide range of experiments have shown that plant physiological adaptation to spaceflight involves gene expression changes that alter cell wall and other metabolisms. However, while transcriptome profiling aptly illuminates changes in gene expression that accompany spaceflight adaptation, mutation analysis is required to illuminate key elements required for that adaptation. Here we report how transcriptome profiling was used to gain insight into the spaceflight adaptation role of Altered response to gravity 1 (Arg1), a gene known to affect gravity responses in plants on Earth. The study compared expression profiles of cultured lines of Arabidopsis thaliana derived from wild-type (WT) cultivar Col-0 to profiles from a knock-out line deficient in the gene encoding ARG1 (ARG1 KO), both on the ground and in space. The cell lines were launched on SpaceX CRS-2 as part of the Cellular Expression Logic (CEL) experiment of the BRIC-17 spaceflight mission. The cultured cell lines were grown within 60 mm Petri plates in Petri Dish Fixation Units (PDFUs) that were housed within the Biological Research In Canisters (BRIC) hardware. Spaceflight samples were fixed on orbit. Differentially expressed genes were identified between the two environments (spaceflight and comparable ground controls) and the two genotypes (WT and ARG1 KO). Each genotype engaged unique genes during physiological adaptation to the spaceflight environment, with little overlap. Most of the genes altered in expression in spaceflight in WT cells were found to be Arg1-dependent, suggesting a major role for that gene in the physiological adaptation of undifferentiated cells to spaceflight. Key Words: ARG1-Spaceflight-Gene expression-Physiological adaptation-BRIC. Astrobiology 17, 1077-1111.

Expression of the lef5 gene from Spodoptera exigua multiple nucleopolyhedrovirus contributes to the baculovirus stability in cell culture.

Baculoviruses are a broad group of viruses infecting insects, predominately of the order Lepidoptera. They are used worldwide as biological insecticides and as expression vectors to produce recombinant proteins. Baculoviruses replicate in their host, although several cell lines have been developed for in vitro replication. Nevertheless, replication of baculoviruses in cell culture involves the generation of defective viruses with a decrease in productivity and virulence. Transcriptional studies of the Spodoptera exigua multiple nucleopolyhedrovirus (SeMNPV) and the Autographa californica multiple nucleopolyhedrovirus (AcMNPV) infective process revealed differences in the expression patterns when the virus replicated under in vitro (Se301 cells) or in vivo (S. exigua larvae) conditions. The late expression factor 5 (lef5) gene was found to be highly overexpressed when the virus replicates in larvae. To test the possible role of lef5 expression in viral stability, recombinant AcMNPV expressing the lef5 gene from SeMNPV (Se-lef5) was generated and its stability was monitored during successive infection passages in Sf21 cells by evaluating the loss of several essential and non-essential genes. The gfp transgene was more stable in those viruses expressing the Se-LEF5 protein and the GFP-defective viruses were accumulated at a lower level when compared to its control viruses, confirming the positive influence of lef5 in viral stability during the multiplication process. This work describes for the first time a viral factor involved in transgene stability when baculoviruses replicate in cell culture, opening new ways to facilitate the in vitro production of recombinant proteins using baculovirus.

Stress Leukogram Induced by Acute and Chronic Stress in Zebrafish (Danio rerio).

The use of zebrafish (Danio rerio) as an animal model for experimental studies of stress has increased rapidly over the years. Although many physiologic and behavioral characteristics associated with stress have been defined in zebrafish, the effects of stress on hematologic parameters have not been described. The purpose of our study was to induce a rise in endogenous cortisol through various acute and chronic stressors and compare the effects of these stressors on peripheral WBC populations. Acutely stressed fish underwent dorsal or full-body exposure to air for 3 min, repeated every 30 min over the course of 90 min. Chronically stressed fish underwent exposure to stressors twice daily over a period of 5 d. After the last stressful event, fish were euthanized, and whole blood and plasma were obtained. A drop of whole blood was used to create a blood smear, which was subsequently stained with a modified Wright-Giemsa stain and a 50-WBC differential count determined. Plasma cortisol levels were determined by using a commercially available ELISA. Endogenous cortisol concentrations were significantly higher in both stressed groups as compared with control fish. Acutely stressed fish demonstrated significant lymphopenia, monocytosis, and neutrophilia, compared with unstressed, control fish. Chronic stress induced lymphopenia and monocytosis but no significant changes in relative neutrophil populations in zebrafish. The changes in both stressed groups most likely are due to increases in endogenous cortisol concentrations and represent the first description of a stress leukogram in zebrafish.

Genetic dissection of the Arabidopsis spaceflight transcriptome: Are some responses dispensable for the physiological adaptation of plants to spaceflight?

Experimentation on the International Space Station has reached the stage where repeated and nuanced transcriptome studies are beginning to illuminate the structural and metabolic differences between plants grown in space compared to plants on the Earth. Genes that are important in establishing the spaceflight responses are being identified, their roles in spaceflight physiological adaptation are increasingly understood, and the fact that different genotypes adapt differently is recognized. However, the basic question of whether these spaceflight responses are actually required for survival has yet to be posed, and the fundamental notion that spaceflight responses may be non-adaptive has yet to be explored. Therefore the experiments presented here were designed to ask if portions of the plant spaceflight response can be genetically removed without causing loss of spaceflight survival and without causing increased stress responses. The CARA experiment compared the spaceflight transcriptome responses in the root tips of two Arabidopsis ecotypes, Col-0 and WS, as well as that of a PhyD mutant of Col-0. When grown with the ambient light of the ISS, phyD plants displayed a significantly reduced spaceflight transcriptome response compared to Col-0, suggesting that altering the activity of a single gene can actually improve spaceflight adaptation by reducing the transcriptome cost of physiological adaptation. The WS genotype showed an even simpler spaceflight transcriptome response in the ambient light of the ISS, more broadly indicating that the plant genotype can be manipulated to reduce the cost of spaceflight adaptation, as measured by transcriptional response. These differential genotypic responses suggest that genetic manipulation could further reduce, or perhaps eliminate the metabolic cost of spaceflight adaptation. When plants were germinated and then left in the dark on the ISS, the WS genotype actually mounted a larger transcriptome response than Col-0, suggesting that the in-space light environment affects physiological adaptation, which implies that manipulating the local habitat can also substantially impact the metabolic cost of spaceflight adaptation.

Dissecting Low Atmospheric Pressure Stress: Transcriptome Responses to the Components of Hypobaria in Arabidopsis.

Controlled hypobaria presents biology with an environment that is never encountered in terrestrial ecology, yet the apparent components of hypobaria are stresses typical of terrestrial ecosystems. High altitude, for example, presents terrestrial hypobaria always with hypoxia as a component stress, since the relative partial pressure of O2 is constant in the atmosphere. Laboratory-controlled hypobaria, however, allows the dissection of pressure effects away from the effects typically associated with altitude, in particular hypoxia, as the partial pressure of O2 can be varied. In this study, whole transcriptomes of plants grown in ambient (97 kPa/pO2 = 21 kPa) atmospheric conditions were compared to those of plants transferred to five different atmospheres of varying pressure and oxygen composition for 24 h: 50 kPa/pO2 = 10 kPa, 25 kPa/pO2 = 5 kPa, 50 kPa/pO2 = 21 kPa, 25 kPa/pO2 = 21 kPa, or 97 kPa/pO2 = 5 kPa. The plants exposed to these environments were 10 day old Arabidopsis seedlings grown vertically on hydrated nutrient plates. In addition, 5 day old plants were also exposed for 24 h to the 50 kPa and ambient environments to evaluate age-dependent responses. The gene expression profiles from roots and shoots showed that the hypobaric response contained more complex gene regulation than simple hypoxia, and that adding back oxygen to normoxic conditions did not completely alleviate gene expression changes in hypobaric responses.