The plant cytosolic m6A RNA methylome stabilizes photosynthesis in the cold

The sessile lifestyle of plants requires an immediate response to environmental stressors that affect photosynthesis, growth, and crop yield. Here, we showed that three abiotic perturbations-heat, cold, and high light-triggered considerable changes in the expression signatures of 42 epitranscriptomic factors (writers, erasers, and readers) with putative chloroplast-associated functions that formed clusters of commonly expressed genes in Arabidopsis. The expression changes under all conditions were reversible upon deacclimation, identifying epitranscriptomic players as modulators in acclimation processes. Chloroplast dysfunctions, particularly those induced by the oxidative stress-inducing norflurazon in a largely GENOME UNCOUPLED-independent manner, triggered retrograde signals to remodel chloroplast-associated epitranscriptomic expression patterns. N6-methyladenosine (m6A) is known as the most prevalent RNA modification and impacts numerous developmental and physiological functions in living organisms. During cold treatment, expression of components of the primary nuclear m6A methyltransferase complex was upregulated, accompanied by a significant increase in cellular m6A mRNA marks. In the cold, the presence of FIP37, a core component of the writer complex, played an important role in positive regulation of thylakoid structure, photosynthetic functions, and accumulation of photosystem I, the Cytb6f complex, cyclic electron transport proteins, and Curvature Thylakoid1 but not that of photosystem II components and the chloroplast ATP synthase. Downregulation of FIP37 affected abundance, polysomal loading, and translation of cytosolic transcripts related to photosynthesis in the cold, suggesting m6A-dependent translational regulation of chloroplast functions. In summary, we identified multifaceted roles of the cellular m6A RNA methylome in coping with cold; these were predominantly associated with chloroplasts and served to stabilize photosynthesis.

Natural variation of temperature acclimation of Arabidopsis thaliana

Acclimation is a multigenic trait by which plants adjust photosynthesis and metabolism to cope with a changing environment. Here, natural variations of photosynthetic efficiency and acclimation of the central carbohydrate metabolism were analyzed in response to low and elevated temperatures. For this, 18 natural accessions of Arabidopsis thaliana, originating from Cape Verde Islands and Europe, were grown at 22°C before being exposed to 4°C and 34°C for cold and heat acclimation, respectively. Absolute amounts of carbohydrates were quantified together with their subcellular distribution across plastids, cytosol and vacuole. Linear electron transport rates (ETRs) were determined together with the maximum quantum efficiency of photosystem II (Fv/Fm) for all growth conditions and under temperature fluctuation. Under elevated temperature, ETR residuals under increasing photosynthetic photon flux densities significantly correlated with the degree of temperature fluctuation at the original habitat of accessions, indicating a geographical east/west gradient of photosynthetic acclimation capacities. Plastidial sucrose concentrations positively correlated with maximal ETRs under fluctuating temperature, indicating a stabilizing role within the chloroplast. Our findings revealed specific subcellular carbohydrate distributions that contribute differentially to the photosynthetic efficiency of natural Arabidopsis thaliana accessions across a longitudinal gradient. This sheds light on the relevance of subcellular metabolic regulation for photosynthetic performance in a fluctuating environment and supports the physiological interpretation of naturally occurring genetic variation of temperature tolerance and acclimation.

Predicting plant growth response under fluctuating temperature by carbon balance modelling

Quantification of system dynamics is a central aim of mathematical modelling in biology. Defining experimentally supported functional relationships between molecular entities by mathematical terms enables the application of computational routines to simulate and analyse the underlying molecular system. In many fields of natural sciences and engineering, trigonometric functions are applied to describe oscillatory processes. As biochemical oscillations occur in many aspects of biochemistry and biophysics, Fourier analysis of metabolic functions promises to quantify, describe and analyse metabolism and its reaction towards environmental fluctuations. Here, Fourier polynomials were developed from experimental time-series data and combined with block diagram simulation of plant metabolism to study heat shock response of photosynthetic CO₂ assimilation and carbohydrate metabolism in Arabidopsis thaliana. Simulations predicted a stabilising effect of reduced sucrose biosynthesis capacity and increased capacity of starch biosynthesis on carbon assimilation under transient heat stress. Model predictions were experimentally validated by quantifying plant growth under such stress conditions. In conclusion, this suggests that Fourier polynomials represent a predictive mathematical approach to study dynamic plant-environment interactions.

Temperature-induced dynamics of plant carbohydrate metabolism

Carbohydrates are direct products of photosynthetic CO₂ assimilation. Within a changing temperature regime, both photosynthesis and carbohydrate metabolism need tight regulation to prevent irreversible damage of plant tissue and to sustain energy metabolism, growth and development. Due to climate change, plants are and will be exposed to both long-term and short-term temperature changes with increasing amplitude. Particularly sudden fluctuations, which might comprise a large temperature amplitude from low to high temperature, pose a challenge for plants from the cellular to the ecosystem level. A detailed understanding of fundamental regulatory processes, which link photosynthesis and carbohydrate metabolism under such fluctuating environmental conditions, is essential for an estimate of climate change consequences. Further, understanding these processes is important for biotechnological application, breeding and engineering. Environmental light and temperature regimes are sensed by a molecular network that comprises photoreceptors and molecular components of the circadian clock. Photosynthetic efficiency and plant productivity then critically depend on enzymatic regulation and regulatory circuits connecting plant cells with their environment and re-stabilising photosynthetic efficiency and carbohydrate metabolism after temperature-induced deflection. This review summarises and integrates current knowledge about re-stabilisation of photosynthesis and carbohydrate metabolism after perturbation by changing temperature (heat and cold).

[Psychometric instruments for the diagnosis of tinnitus]

Tinnitus is a very complex phenomenon with various mechanisms of origin. Multimodal and interdisciplinary treatment is the most effective form of treatment for patients with chronic tinnitus. In order to assess existing comorbidity in tinnitus patients as well as to treat the patients individually, a comprehensive and differentiated diagnosis is needed. Since standardized guidelines for the use of relevant instruments in the diagnosis of tinnitus have been lacking hitherto, we present here psychometric questionnaires which have already been used effectively in the research, diagnosis and therapy of tinnitus in the present article. The questionnaires measure the severity of tinnitus, depression and anxiety, the perceived stress, personal resources as well as the quality of life of patients.

Psychological comorbidity in patients with chronic tinnitus: analysis and comparison with chronic pain, asthma or atopic dermatitis patients

PURPOSE

To determine the prevalence and severity of psychological comorbidity in patients with chronic tinnitus in comparison with other chronic illnesses, namely chronic pain, chronic asthma and atopic dermatitis.

METHODS

Psychological diagnoses were done according to ICD-10 Chapter V(F). Subjective impairment was evaluated using 5 psychometric questionnaires: tinnitus questionnaire, Berlin mood questionnaire, sense of coherence (SOC-L9) and perceived stress questionnaire. Sleep disturbance was measured by the subdomain 'exhaustion' of the Giessen physical complaints inventory.

RESULTS

Somatoform or affective disorders were most frequent in all disease groups. Patients with chronic tinnitus had a stronger SOC and better subjective mood, stronger commitment, and less anger and anxious depression than the patients with chronic pain, chronic asthma or atopic dermatitis. However, in patients with higher tinnitus annoyance, psychological comorbidity was similar to that found in patients with other chronic diseases.

CONCLUSIONS

Besides collecting medical and social history, special psychometric instruments should be used for the diagnosis of tinnitus patients. Based on relative high frequency of psychological comorbidity, we recommend interdisciplinary cooperation between otorhinolaryngologists and other specialists (psychosomatic medicine, psychology or psychiatry) during the treatment of tinnitus patients, especially when high degree of tinnitus annoyance is involved.

[Integrated intensive treatment of tinnitus: decrease of the tinnitus-related distress during a one-year follow-up study]

AIM OF THE STUDY

The therapy of the chronic tinnitus is aimed at improving the way patients cope with their tinnitus and at reducing the tinnitus-related distress. The present study investigated the changes of psychometric parameters that occurred in patients with chronic tinnitus after 7-days outpatient multidisciplinary therapy. The changes were monitored for up to 1 year in order to evaluate the long-term efficiency.

METHODS

Main emphasis of the intensive tinnitus therapy applied was placed on tinnitus habituation and on teaching the patients how to apply coping strategies. The main elements of the multimodal concept included progressive muscle relaxation according to Jacobson, physiotherapy, educative seminars, training of selective attention and, lastly, the change of judgment, attitude and behaviour towards tinnitus. Psychometric parameters and tinnitus-related distress were assessed prior to and after the therapy (at 3, 6 and 12 months) using the tinnitus questionnaire (TQ) according to Goebel and Hiller. Furthermore, subjects waiting for therapy (waiting list) were recruited to the control group and compared with the therapy group which had received therapy 3 months earlier.

RESULTS

The therapy group showed a significant reduction of the TQ total score after 3 months as compared to the control group. Moreover, we observed a long-term, progressive positive outcome during the one-year follow-up. The TQ total score was reduced by 10.9 points. There was an obvious decrease of the emotional and cognitive distress as well as of the intrusiveness of tinnitus, as per evaluation of TQ subscales.

CONCLUSIONS

The outpatient intensive multidisciplinary tinnitus therapy with long-term aftercare has proved to be an effective method in the treatment of patients with chronic tinnitus. The outpatient setting enables the instant implementation of strategies learned during therapy in the patients' everyday life.

[The role of stress in the pathogenesis of tinnitus and in the ability to cope with it]

Besides the impairment of somatic functions, other factors including stress, and psychological and social characteristics are known to be important factors in the pathogenesis of tinnitus and the ability to cope with it. Existing coping strategies and psychosocial factors may have an influence on the degree of stress perceived through tinnitus. In the case of missing habituation, serious psychological, neurological and immunological responses to tinnitus are possible. In order to reduce the cognitive and emotional tinnitus-distress associated with this, there should be a focus on providing functional coping strategies combined with cognitive behavioural elements.

[Integrated intensive treatment of tinnitus: method and initial results]

In recent years, no major advances have been made in understanding the mechanisms underlying the development of tinnitus. Hence, the present therapeutic strategies aim at decoupling the subconscious from the perception of tinnitus. Mindful of the lessons drawn from existing tinnitus retraining and desensitisation therapies, a new integrated day hospital strategy of treatment lasting 7-14 days has been developed at the Charité Hospital and is presented in the present paper. The strategy for treating tinnitus in the proximity of patient domicile is designed for patients who feel disturbed in their world of perception and their efficiency due to tinnitus and give evidence of mental and physical strain. In view of the etiologically non-uniform and multiple events connected with tinnitus, consideration was also given to the fact that somatic and psychosocial factors are equally involved. Therefore, therapy should aim at diagnosing and therapeutically influencing those psychosocial factors that reduce the hearing impression to such an extent that the affected persons suffer from strain. The first results of therapy-dependent changes of 46 patients suffering from chronic tinnitus are presented. The data were evaluated before and after 7 days of treatment and 6 months after the end of treatment. Immediately after the treatment, the scores of both the tinnitus questionnaire (Goebel and Hiller) and the subscales improved significantly. These results were maintained during the 6-month post-treatment period and even improved.

Potential health risks of complementary alternative medicines in cancer patients

Many cancer patients use complementary alternative medicines (CAMs) but may not be aware of the potential risks. There are no studies quantifying such risks, but there is some evidence of patient risk from case reports in the literature. A cross-sectional survey of patients attending the outpatient department at a specialist cancer centre was carried out to establish a pattern of herbal remedy or supplement use and to identify potential adverse side effects or drug interactions with conventional medicines. If potential risks were identified, a health warning was issued by a pharmacist. A total of 318 patients participated in the study. Of these, 164 (51.6%) took CAMs, and 133 different combinations were recorded. Of these, 10.4% only took herbal remedies, 42.1% only supplements and 47.6% a combination of both. In all, 18 (11.0%) reported supplements in higher than recommended doses. Health warnings were issued to 20 (12.2%) patients. Most warnings concerned echinacea in patients with lymphoma. Further warnings were issued for cod liver/fish oil, evening primrose oil, gingko, garlic, ginseng, kava kava and beta-carotene. In conclusion, medical practitioners need to be able to identify the potential risks of CAMs. Equally, patients should be encouraged to disclose their use. Also, more research is needed to quantify the actual health risks.

High functioning fragile X males: demonstration of an unmethylated fully expanded FMR-1 mutation associated with protein expression

Fragile X (fra(X)) males with a standardized IQ score of 70 or higher represent a high functioning (HF) or nonretarded fra(X) male group. This group, which does not include nonpenetrant males, has received little research attention to date. Of 221 fra(X) males who had been evaluated through The Children's Hospital in Denver since 1981 and had completed cognitive or developmental testing, 29 (13%) were high functioning by the above definition. We found that HF males on the whole had a lower cytogenetic score and were younger than retarded fra(X) males, but there was no difference between these two groups in the number of typical fra(X) physical manifestations present. FMR-1 DNA testing was performed on 134 fra(X) males and methylation status was determined for 51 of these. A greater percentage of HF males had a mosaic pattern or an incompletely methylated full mutation than did retarded males. A unique DNA pattern, an unmethylated fully expanded mutation, was discovered in 3 of the highest functioning fra(X) males. Protein studies performed on 2 of these males demonstrated the presence of FMR-1 protein, albeit at lower levels than normal. FMR-1 protein was not present in retarded fra(X) males. Significant FMR-1 protein expression may be responsible for higher cognitive functioning in the 2 males with unmethylated fully expanded mutations compared to retarded fra(X) males.