Isotype switching in human memory B cells sets intrinsic antigen-affinity thresholds that dictate antigen-driven fates.

Memory B cells (MBCs) play a critical role in protection against homologous and variant pathogen challenge by either differentiating to plasma cells (PCs) or to germinal center (GC) B cells. The human MBC compartment contains both switched IgG+ and unswitched IgM+ MBCs; however, whether these MBC subpopulations are equivalent in their response to B cell receptor cross-linking and their resulting fates is incompletely understood. Here, we show that IgG+ and IgM+ MBCs can be distinguished based on their response to κ-specific monoclonal antibodies of differing affinities. IgG+ MBCs responded only to high-affinity anti-κ and differentiated almost exclusively toward PC fates. In contrast, IgM+ MBCs were eliminated by apoptosis by high-affinity anti-κ but responded to low-affinity anti-κ by differentiating toward GC B cell fates. These results suggest that IgG+ and IgM+ MBCs may play distinct yet complementary roles in response to pathogen challenge ensuring the immediate production of high-affinity antibodies to homologous and closely related challenges and the generation of variant-specific MBCs through GC reactions.

Use of immunology in news and YouTube videos in the context of COVID-19: politicisation and information bubbles.

Background: The COVID-19 pandemic propelled immunology into global news and social media, resulting in the potential for misinterpreting and misusing complex scientific concepts. Objective: To study the extent to which immunology is discussed in news articles and YouTube videos in English and Italian, and if related scientific concepts are used to support specific political or ideological narratives in the context of COVID-19. Methods: In English and Italian we searched the period 11/09/2019 to 11/09/2022 on YouTube, using the software Mozdeh, for videos mentioning COVID-19 and one of nine immunological concepts: antibody-dependent enhancement, anergy, cytokine storm, herd immunity, hygiene hypothesis, immunity debt, original antigenic sin, oxidative stress and viral interference. We repeated this using MediaCloud for news articles.Four samples of 200 articles/videos were obtained from the randomised data gathered and analysed for mentions of concepts, stance on vaccines, masks, lockdown, social distancing, and political signifiers. Results: Vaccine-negative information was higher in videos than news (8-fold in English, 6-fold in Italian) and higher in Italian than English (4-fold in news, 3-fold in videos). We also observed the existence of information bubbles, where a negative stance towards one intervention was associated with a negative stance to other linked ideas. Some immunological concepts (immunity debt, viral interference, anergy and original antigenic sin) were associated with anti-vaccine or anti-NPI (non-pharmacological intervention) views. Videos in English mentioned politics more frequently than those in Italian and, in all media and languages, politics was more frequently mentioned in anti-guidelines and anti-vaccine media by a factor of 3 in video and of 3-5 in news. Conclusion: There is evidence that some immunological concepts are used to provide credibility to specific narratives and ideological views. The existence of information bubbles supports the concept of the "rabbit hole" effect, where interest in unconventional views/media leads to ever more extreme algorithmic recommendations.

Analysis of patients with endometrial carcinoma using the ProMise classifier: a pilot study from India.

BACKGROUND: Molecular subtyping of endometrial carcinomas (EC) has been shown to classify tumors into prognostically relevant groups. Characterizing EC with a limited number of markers viz., POLE mutations, p53 mutations, and MMR status, can provide valuable information. DESIGN: Paraffin sections of a cohort of 48 EC from a tertiary care center were characterized for the above-mentioned molecular markers and analyzed in the context of survival. METHODS: Formalin fixed paraffin embedded tissues from 48 EC were characterized for POLE mutations by Sanger sequencing (exons 9-14), for MMR (MLH1, MH2, MSH6) using immunohistochemistry (IHC) and copy number (high/low) using p53 IHC. Mutational status was integrated along with the clinicopathological details and survival analysis performed. RESULTS: Eleven (22.9%) patients were MMR deficient, 3 (6.3%) had POLE mutation, while 2 (4.1%) had both POLE and P53 mutations (regarded as multiple classifiers). Twelve (25%) patients were found to have P53 mutations, while the remaining 20 (41.7%) had no specific molecular profile (NSMP). Median follow-up duration was 43.5 (2-62) months with 8 recurrences and 9 deaths. Tumors with POLE mutation had the most favorable prognosis followed by the NSMP and the MMR mutated group while the P53 and multiple classifier groups had the worst prognosis in terms of OS (Log-rank p: 0.006) and PFS (Log-rank p: 0.001). CONCLUSION: The integration of molecular-clinicopathologic data for endometrial cancer classification, through cost-effective, clinically applicable assays appears to be a highly objective tool that can be adopted even in resource-limited settings. It has the potential to cause a shift in the paradigm of EC pathology and management practice.

B cell responses to membrane-presented antigens require the function of the mechanosensitive cation channel Piezo1.

The demand for a vaccine for coronavirus disease 2019 (COVID-19) highlighted gaps in our understanding of the requirements for B cell responses to antigens, particularly to membrane-presented antigens, as occurs in vivo. We found that human B cell responses to membrane-presented antigens required the function of Piezo1, a plasma membrane mechanosensitive cation channel. Simply making contact with a glass probe induced calcium (Ca2+) fluxes in B cells that were blocked by the Piezo1 inhibitor GsMTx4. When placed on glass surfaces, the plasma membrane tension of B cells increased, which stimulated Ca2+ influx and spreading of B cells over the glass surface, which was blocked by the Piezo1 inhibitor OB-1. B cell responses to membrane-presented antigens but not to soluble antigens were inhibited both by Piezo1 inhibitors and by siRNA-mediated knockdown of Piezo1. Thus, the activation of Piezo1 defines an essential event in B cell activation to membrane-presented antigens that may be exploited to improve the efficacy of vaccines.

The clinico pathological features and survival in serous endometrial cancers.

Background & Introduction: Serous cancers are a biologically aggressive variety of endometrial cancer (EC) with a high rate of recurrence and mortality among all the subtypes. Herein we describe our experience with serous endometrial cancer. Objective: This study was conducted to identify the clinicopathological characteristics, treatment modalities and survival outcomes in women diagnosed with serous endometrial malignancies. Methods: This was a retrospective descriptive analysis of data on patients diagnosed with serous endometrial tumours between January 2010 to September 2019 in our institute collected from electronic medical records. Descriptive statistics such as proportions, means and standard deviations and Cox regression hazards model on risk factors were performed. Survival was plotted by Kaplan-Meier curves. Results: During the study period, 32 (5.7%) patients out of 564 diagnosed cases of endometrial cancer had serous histology. The mean age at diagnosis was 62.5 years (SD 7.6) while mean BMI was 26.4 kg/m2 (SD 4.6). Staging laparotomy was done in 27(84%) of the patients. Advanced stages (III and IV) were detected in 16 patients (50%) at primary surgery.Adjuvant chemo therapy and radiation was received by 21(65.6%) patients therapy. Out of 32 patients, 13 (40%) developed recurrence while another 13 expired. Stage at diagnosis and type of adjuvant therapy were important factors in determining the outcome. Median recurrence free and overall survival was 22(95% CI 1.4-42) and 36 months (95% CI 10.1-61.8) respectively. Conclusion: Serous endometrial cancers are an intrusive subtype of EC. Comprehensive surgical staging with optimal cytoreduction should be aimed at. Adequate upfront molecular categorization of these tumors is mandated. Adjuvant therapy with chemotherapy and radiation is given in postoperative setting. Targeted therapies and immunotherapy could be considered in recurrences.

Untangling the Complexities of Processing and Analysis for Untargeted LC-MS Data Using Open-Source Tools.

Untargeted metabolomics is a powerful tool for measuring and understanding complex biological chemistries. However, employment, bioinformatics and downstream analysis of mass spectrometry (MS) data can be daunting for inexperienced users. Numerous open-source and free-to-use data processing and analysis tools exist for various untargeted MS approaches, including liquid chromatography (LC), but choosing the 'correct' pipeline isn't straight-forward. This tutorial, in conjunction with a user-friendly online guide presents a workflow for connecting these tools to process, analyse and annotate various untargeted MS datasets. The workflow is intended to guide exploratory analysis in order to inform decision-making regarding costly and time-consuming downstream targeted MS approaches. We provide practical advice concerning experimental design, organisation of data and downstream analysis, and offer details on sharing and storing valuable MS data for posterity. The workflow is editable and modular, allowing flexibility for updated/changing methodologies and increased clarity and detail as user participation becomes more common. Hence, the authors welcome contributions and improvements to the workflow via the online repository. We believe that this workflow will streamline and condense complex mass-spectrometry approaches into easier, more manageable, analyses thereby generating opportunities for researchers previously discouraged by inaccessible and overly complicated software.

Lidocaine for Neuropathic Cancer Pain (LiCPain): study protocol for a mixed-methods pilot study.

INTRODUCTION: Many patients experience unrelieved neuropathic cancer-related pain. Most current analgesic therapies have psychoactive side effects, lack efficacy data for this indication and have potential medication-related harms. The local anaesthetic lidocaine (lignocaine) has the potential to help manage neuropathic cancer-related pain when administered as an extended, continuous subcutaneous infusion. Data support lidocaine as a promising, safe agent in this setting, warranting further evaluation in robust, randomised controlled trials. This protocol describes the design of a pilot study to evaluate this intervention and explains the pharmacokinetic, efficacy and adverse effects evidence informing the design. METHODS AND ANALYSIS: A mixed-methods pilot study will determine the feasibility of an international first, definitive phase III trial to evaluate the efficacy and safety of an extended continuous subcutaneous infusion of lidocaine for neuropathic cancer-related pain. This study will comprise: a phase II double-blind randomised controlled parallel-group pilot of subcutaneous infusion of lidocaine hydrochloride 10% w/v (3000 mg/30 mL) or placebo (sodium chloride 0.9%) over 72 hours for neuropathic cancer-related pain, a pharmacokinetic substudy and a qualitative substudy of patients' and carers' experiences. The pilot study will provide important safety data and help inform the methodology of a definitive trial, including testing proposed recruitment strategy, randomisation, outcome measures and patients' acceptability of the methodology, as well as providing a signal of whether this area should be further investigated. ETHICS AND DISSEMINATION: Participant safety is paramount and standardised assessments for adverse effects are built into the trial protocol. Findings will be published in a peer-reviewed journal and presented at conferences. This study will be considered suitable to progress to a phase III study if there is a completion rate where the CI includes 80% and excludes 60%. The protocol and Patient Information and Consent Form have been approved by Sydney Local Health District (Concord) Human Research Ethics Committee 2019/ETH07984 and University of Technology Sydney ETH17-1820. TRIAL REGISTRATION NUMBER: ANZCTR ACTRN12617000747325.

Virtual Interviewing for Pediatric Emergency Medicine Fellowship-A National Survey.

OBJECTIVE: This study aimed to evaluate both applicant and interviewer satisfaction with the virtual interviewing process for pediatric emergency medicine (PEM) fellowship in hopes to improve the fellowship interviewing process. It was proposed that fellowship programs and applicants would prefer virtual interviews over traditional interviews. METHODS: A survey developed in collaboration with UT Southwestern PEM fellowship leaders and national PEM leaders was sent to all PEM fellowship applicants and programs at the conclusion of the 2020 interview season and rank list submission. The applicant survey obtained information on ease of virtual interviews and whether applicants felt that they obtained adequate information from virtual interviews to make informed program selections. Program director surveys collected data on thoughts and feelings about virtual interviews and obstacles encountered during the recruitment season. Both surveys asked about costs for interviews and interview type preference. RESULTS: A response rate of 49% from applicants and 47% from programs was obtained. Virtual interview days were similar in the amount of time and staff hours used compared with traditional days. Applicants spent less on virtual interviews compared with those who underwent traditional interviews (average $725 vs $4312). Programs received more applications than the prior year and spent less money during the virtual cycle. The majority of the applicants (90%) were comfortable with the virtual interview platform, and most (66%) agreed that virtual interviews provided adequate information to determine program rank. Geography was the number 1 rank determining factor. Programs and applicants preferred a form of in-person interviews. CONCLUSIONS: Virtual interviews provide cost savings for both applicants and programs. Despite this, both parties prefer a form of in-person interviews.

Role of Hysterectomy in Gestational Trophoblastic Neoplasia.

Hysterectomy has a limited role in the management of gestational trophoblastic neoplasia because of the high effectiveness of chemotherapy and the young age of patients. In selected patients, it is believed to help in reducing the number of chemotherapy cycles, overcoming chemo-resistance, and treating acute haemorrhagic events. The present study aimed to evaluate the indications and outcomes of hysterectomy in patients with GTN at a tertiary care centre in India. Between 2012 and 2019, we identified all patients with GTN from the hospital database. Demographic, clinical, and follow-up details of patients who underwent hysterectomy were obtained from the electronic medical records. During the study period, 98 cases of GTN were treated at our centre of which 54% were low-risk and 46% were high-risk cases. Twenty-six patients (26%) underwent hysterectomy as part of their management for GTN. The patients belonging to the high-risk group had more hysterectomies (65%) with an odds ratio of 2.96. The common pathological diagnosis was choriocarcinoma in 44% and an invasive mole in 30% of patients. Bleeding, either intraperitoneal or vaginal, was the most common indication for hysterectomy (48%). The median number of chemotherapy cycles received was 5 in patients who had primary hysterectomy and 6 in patients who did not have hysterectomy. The majority of patients received EMACO (57.7%) chemotherapy. The mean duration of follow-up was 18 months (range 1-67). After treatment, complete remission was achieved in 94 out of 98 (95.9%) and also in all patients (100%) who had undergone hysterectomy as adjuvant procedure. Three patients died during treatment (3.06%), all belonging to the high-risk group, and one patient had a recurrence (0.01%). In selected cases of GTN, hysterectomy may be an effective means to reduce or eliminate tumour bulk, to overcome chemoresistance and manage acute bleeding events.

Cryo-EM structures of an insecticidal Bt toxin reveal its mechanism of action on the membrane.

Insect pests are a major cause of crop losses worldwide, with an estimated economic cost of $470 billion annually. Biotechnological tools have been introduced to control such insects without the need for chemical pesticides; for instance, the development of transgenic plants harbouring genes encoding insecticidal proteins. The Vip3 (vegetative insecticidal protein 3) family proteins from Bacillus thuringiensis convey toxicity to species within the Lepidoptera, and have wide potential applications in commercial agriculture. Vip3 proteins are proposed to exert their insecticidal activity through pore formation, though to date there is no mechanistic description of how this occurs on the membrane. Here we present cryo-EM structures of a Vip3 family toxin in both inactive and activated forms in conjunction with structural and functional data on toxin-membrane interactions. Together these data demonstrate that activated Vip3Bc1 complex is able to insert into membranes in a highly efficient manner, indicating that receptor binding is the likely driver of Vip3 specificity.

Endometriosis and malignancy: The intriguing relationship.

OBJECTIVE: To determine the prevalence and study the association of ovarian, uterine, and breast cancers with endometriosis. METHODS: A cross-sectional study of all women with a tissue-proven diagnosis of endometriosis postoperatively in a tertiary care hospital between January 1, 2010, and December 31, 2019, was conducted to determine the prevalence of coexistent malignancy. Patient details were obtained from electronic clinical records. Univariate analysis followed by multivariate analysis was done to find independent risk factors associated with malignancy. RESULTS: Out of 800 patients, 104 (13.0%) were found to have coexistent malignancy: ovarian (50, 6.2%); endometrial (33, 4.1%); synchronous ovarian and endometrial (7, 0.9%); and breast (14, 1.8%). Increasing age (odds ratio [OR] 1.13; 95% confidence interval [CI] 1.09-1.16), higher levels of cancer antigen 125 (CA 125) (OR 1.002; 95% CI 1.001-1.005), postmenopausal status (OR 6.2; 95% CI 2.0-19.2), duration of endometriosis over 5 years (OR 4.7; 95% CI 2.5-9.0), and endometriomas larger than 8 cm (area under the curve 0.83) were predictive of coexistent malignancy. CONCLUSION: Endometriosis is associated with an increased risk of ovarian, endometrial, and breast malignancy. Increasing age, postmenopausal status, higher levels of CA 125, larger endometrioma, and long-standing disease are predictive risk factors.

Emotion regulation flexibility and disordered eating.

Research suggests that individuals with eating disorders use more putatively maladaptive emotion regulation strategies and fewer putatively adaptive strategies. However, there is growing theoretical and empirical support for the notion that the efficacy of emotion regulation strategies varies across situations. Thus, successful emotion regulation is characterized by the ability to flexibly choose between emotion regulation strategies in order to fit one's situational needs. Despite growing support for this conceptualization of successful emotion regulation, no research has investigated it in relation to disordered eating. Using the emotion regulation choice paradigm, this study investigated the association between emotion regulation flexibility and disordered eating. Women (N = 50) completed self-report questionnaires and a laboratory-based emotion regulation choice task to assess emotion regulation flexibility. Results indicated that lower emotion regulation flexibility was associated with more frequent purging and excessive exercise. Emotion regulation flexibility was not significantly associated with binge eating or overall eating disorder psychopathology. These findings suggest that individuals who engage in unhealthy compensatory behaviors exhibit reduced emotion regulation flexibility. If replicated in clinical samples, treatment for eating disorders characterized by compensatory behaviors may benefit from incorporating additional strategies to help people utilize emotion regulation strategies in a flexible, situationally appropriate manner.

Abdominal Tuberculosis Mimicking Ovarian Cancer: A Diagnostic Dilemma.

AIMS: The objective of this study was to describe the clinicopathological details in patients referred to the Gynaecologic Oncology Department with possible ovarian or primary peritoneal cancer where the final diagnosis turned out to be abdominal tuberculosis. METHODOLOGY: Retrospective chart analysis of 23 cases diagnosed with abdominal tuberculosis who were admitted under the Division of Gynaecologic Oncology suspected to have disseminated peritoneal malignancy, during 2014-2017. RESULTS: There were 23 patients who were referred to the Gynaecologic Oncology outpatient for evaluation of ascites, to rule out malignancy. The mean age of this patient group was 35 years (SD 14.5, range 14-65). The mean CA 125 was 333.5 [400.7 (9.09-1568)]. Ascitic fluid analysis confirmed TB in 26%; omental biopsy revealed TB in 69%, and operative diagnostic procedures (laparoscopy and laparotomy) were done in 15 of the 23 patients which had a positive pick up rate of 100% to confirm the diagnosis of TB. Culture of ascitic fluid/omental tissue and PCR yields were poor with a pick up rate of 33% and 6%. CONCLUSIONS: Abdominal TB is common in India and can mimic ovarian malignancy, and hence, high degree of suspicion needed. The isolation of AFB is the gold standard for diagnosis of pulmonary tuberculosis but has a low yield in abdominal TB. Ultrasound-guided procedure is reasonable as an initial procedure. As much time can be lost in working up these patients through multiple diagnostic algorithms using ascitic tap, USG biopsy and then an operative procedure, diagnostic laparoscopy could be considered early in the work up. It is a simple, time-saving and cost-effective way of establishing a diagnosis sooner with least complications.

Metabolic control of BRISC-SHMT2 assembly regulates immune signalling.

Serine hydroxymethyltransferase 2 (SHMT2) regulates one-carbon transfer reactions that are essential for amino acid and nucleotide metabolism, and uses pyridoxal-5'-phosphate (PLP) as a cofactor. Apo SHMT2 exists as a dimer with unknown functions, whereas PLP binding stabilizes the active tetrameric state. SHMT2 also promotes inflammatory cytokine signalling by interacting with the deubiquitylating BRCC36 isopeptidase complex (BRISC), although it is unclear whether this function relates to metabolism. Here we present the cryo-electron microscopy structure of the human BRISC-SHMT2 complex at a resolution of 3.8 Å. BRISC is a U-shaped dimer of four subunits, and SHMT2 sterically blocks the BRCC36 active site and inhibits deubiquitylase activity. Only the inactive SHMT2 dimer-and not the active PLP-bound tetramer-binds and inhibits BRISC. Mutations in BRISC that disrupt SHMT2 binding impair type I interferon signalling in response to inflammatory stimuli. Intracellular levels of PLP regulate the interaction between BRISC and SHMT2, as well as inflammatory cytokine responses. These data reveal a mechanism in which metabolites regulate deubiquitylase activity and inflammatory signalling.

Photocatalytic proximity labelling of MCL-1 by a BH3 ligand.

Ligand-directed protein labelling allows the introduction of diverse chemical functionalities onto proteins without the need for genetically encoded tags. Here we report a method for the rapid labelling of a protein using a ruthenium-bipyridyl (Ru(II)(bpy)3)-modified peptide designed to mimic an interacting BH3 ligand within a BCL-2 family protein-protein interactions. Using sub-stoichiometric quantities of (Ru(II)(bpy)3)-modified NOXA-B and irradiation with visible light for 1 min, the anti-apoptotic protein MCL-1 can be photolabelled with a variety of functional tags. In contrast with previous reports on Ru(II)(bpy)3-mediated photolabelling, tandem mass spectrometry experiments reveal that the labelling site is a cysteine residue of MCL-1. MCL-1 can be labelled selectively in mixtures with other proteins, including the structurally related BCL-2 member, BCL-xL. These results demonstrate that proximity-induced photolabelling is applicable to interfaces that mediate protein-protein interactions, and pave the way towards future use of ligand-directed proximity labelling for dynamic analysis of the interactome of BCL-2 family proteins.

Indirect Effects of Attributional Style for Positive Events on Depressive Symptoms Through Self-Esteem During Early Adolescence.

Research on adolescent depression has overwhelmingly focused on risk factors, such as stressful negative events and cognitive vulnerabilities, but much important information can be gained by focusing on protective factors. Thus, the current study aimed to broaden understanding on adolescent depression by considering the role of two positive elements as protective factors, attributional style for positive events and self-esteem, in a model of depression. The sample included 491 middle school students (52 % female; n = 249) with an age range from 12 to 15 years (M = 13.2, SD = .70). The sample was ethnically/racially diverse, with 55 % White, 22 % Hispanic, 10 % Asian American, 3 % African American, and 10 % Biracial/Other. Correlational analyses indicated significant cross-sectional and longitudinal associations between an enhancing attributional style (internal, stable, global attributions for positive events), self-esteem and depressive symptoms. Further, prospective analyses using bootstrapping methodology demonstrated significant indirect effects of an enhancing attributional style on decreases in depressive symptoms through its effects on self-esteem. These findings highlight the importance of considering attributional style for positive events as a protective factor in the developmental course of depressive symptoms during early adolescence.

Lung cancer stem cells-characteristics, phenotype.

Lung cancer remains a major cause of cancer-related deaths worldwide with unfavourable prognosis mainly due to the late stage of disease at presentation. High incidence and disease recurrence rates are a fact despite advances in treatment. Ongoing experimental and clinical observations suggest that the malignant phenotype in lung cancer is sustained by lung cancer stem cells (CSCs) which are putative stem cells situated throughout the airways that have the potential of initiating lung cancer formation. These cells share the common characteristic of increased proliferation and differentiation, long life span and resistance to chemotherapy and radiation therapy. This review summarises the current knowledge on their characteristics and phenotype.

An exploration of Australian hospital pharmacists' attitudes to patient safety.

OBJECTIVES: To explore the attitudes of Australian hospital pharmacists towards patient safety in their work settings. METHODS: A safety climate questionnaire was administered to all 2347 active members of the Society of Hospital Pharmacists of Australia in 2010. Part of the survey elicited free-text comments about patient safety, error and incident reporting. The comments were subjected to thematic analysis to determine the attitudes held by respondents in relation to patient safety and its quality management in their work settings. KEY FINDINGS: Two hundred and ten (210) of 643 survey respondents provided comments on safety and quality issues related to their work settings. The responses contained a number of dominant themes including issues of workforce and working conditions, incident reporting systems, the response when errors occur, the presence or absence of a blame culture, hospital management support for safety initiatives, openness about errors and the value of teamwork. A number of pharmacists described the development of a mature patient-safety culture - one that is open about reporting errors and active in reducing their occurrence. Others described work settings in which a culture of blame persists, stifling error reporting and ultimately compromising patient safety. CONCLUSION: Australian hospital pharmacists hold a variety of attitudes that reflect diverse workplace cultures towards patient safety, error and incident reporting. This study has provided an insight into these attitudes and the actions that are needed to improve the patient-safety culture within Australian hospital pharmacy work settings.

Best of both worlds: simultaneous high-light and shade-tolerance adaptations within individual leaves of the living stone Lithops aucampiae.

"Living stones" (Lithops spp.) display some of the most extreme morphological and physiological adaptations in the plant kingdom to tolerate the xeric environments in which they grow. The physiological mechanisms that optimise the photosynthetic processes of Lithops spp. while minimising transpirational water loss in both above- and below-ground tissues remain unclear. Our experiments have shown unique simultaneous high-light and shade-tolerant adaptations within individual leaves of Lithops aucampiae. Leaf windows on the upper surfaces of the plant allow sunlight to penetrate to photosynthetic tissues within while sunlight-blocking flavonoid accumulation limits incoming solar radiation and aids screening of harmful UV radiation. Increased concentration of chlorophyll a and greater chlorophyll a:b in above-ground regions of leaves enable maximum photosynthetic use of incoming light, while inverted conical epidermal cells, increased chlorophyll b, and reduced chlorophyll a:b ensure maximum absorption and use of low light levels within the below-ground region of the leaf. High NPQ capacity affords physiological flexibility under variable natural light conditions. Our findings demonstrate unprecedented physiological flexibility in a xerophyte and further our understanding of plant responses and adaptations to extreme environments.

Metabolomics in plant environmental physiology.

Changes in plant metabolism are at the heart of plant developmental processes, underpinning many of the ways in which plants respond to the environment. As such, the comprehensive study of plant metabolism, or metabolomics, is highly valuable in identifying phenotypic effects of abiotic and biotic stresses on plants. When study is in reference to analysing samples that are relevant to environmental or ecologically based hypotheses, it is termed 'environmental metabolomics'. The emergence of environmental metabolomics as one of the latest of the omics technologies has been one of the most critically important recent developments in plant physiology. Its applications broach the entire landscape of plant ecology, from the understanding of plant plasticity and adaptation through to community composition and even genetic modification in crops. The multitude of novel studies published utilizing metabolomics methods employ a variety of techniques, from the initial stages of tissue sampling, through to sample preservation, transportation, and analysis. This review introduces the concept and applications of plant environmental metabolomics as an ecologically important investigative tool. It examines the main techniques used in situ within field sites, with particular reference to sampling and processing, and those more appropriate for use in laboratory-based settings with emphasis on secondary metabolite analysis.