AtMYB41 acts as a dual-function transcription factor that regulates the formation of lipids in an organ- and development-dependent manner.

The plant cuticle controls non-stomatal water loss and can serve as a barrier against biotic agents, whereas the heteropolymer suberin and its associated waxes are deposited constitutively at specific cell wall locations. While several transcription factors controlling cuticle formation have been identified, those involved in the transcriptional regulation of suberin biosynthesis remain poorly characterized. The major goal of this study was to further analyse the function of the R2R3-Myeloblastosis (MYB) transcription factor AtMYB41 in formation of the cuticle, suberin, and suberin-associated waxes throughout plant development. For functional analysis, the organ-specific expression pattern of AtMYB41 was analysed and Atmyb41ge alleles were generated using the CRISPR/Cas9 system. These were investigated for root growth and water permeability upon stress. In addition, the fatty acid, wax, cutin, and suberin monomer composition of different organs was evaluated by gas chromatography. The characterization of Atmyb41ge mutants revealed that AtMYB41 negatively regulates the production of cuticular lipids and fatty acid biosynthesis in leaves and seeds, respectively. Remarkably, biochemical analyses indicate that AtMYB41 also positively regulates the formation of cuticular waxes in stems of Arabidopsis thaliana. Overall, these results suggest that the AtMYB41 acts as a negative regulator of cuticle and fatty acid biosynthesis in leaves and seeds, respectively, but also as a positive regulator of wax production in A. thaliana stems.

Wound-induced triacylglycerol biosynthesis is jasmonoy-l-isoleucin and abscisic acid independent.

Triacylglycerol (TAG) plays a significant role during plant stress - it maintains lipid homeostasis. Upon wounding plants accumulate TAG, likely as a storage form of fatty acids (FAs) that originate from damaged membranes. This study asked if this process depends on the two phytohormones jasmonoyl-isoleucine (JA-Ile) and abscisic acid (ABA), which are involved in wound signalling. To analyse regulation of wound-induced TAG accumulation, we used mutants deficient in JA-Ile, with reduced ABA and the myb96 mutant, which is deficient in an ABA-dependent transcription factor. The expression of genes involved in TAG biosynthesis, and TAG content after wounding were analysed via LC-MS and GC-FID, plastidial lipid content in all mentioned mutant lines was also determined. The localization of newly synthesized TAG was investigated using lipid droplet staining. TAG accumulation upon wounding was confirmed as well as the fact that the newly synthesized TAG are mostly composed of polyunsaturated fatty acids. Nevertheless, all tested mutant lines were able to accumulate TAG similar to the WT. We observed differences in reduction of plastidial lipids - in WT plants this was higher than in mutant lines. Newly synthesized TAGs were stored in lipid droplets at and around the wounded area. Our results show that TAG accumulation upon wounding is not dependent on JA-Ile or ABA. The newly synthesized TAG species are composed of unsaturated fatty acids of membrane origin, and most likely serves as a transient energy store.

Intranasal oxytocin and the stress-buffering effects of social support during experimentally induced pain: The role of attachment security.

BACKGROUND: This study examined whether intranasal oxytocin enhances the stress-buffering effects of social support during experimentally induced pain, taking into account the role of individual differences in attachment security. METHODS: Female participants (N = 193) were randomly assigned to oxytocin (24 IU intranasal) or placebo and to receive support or no support from a friend (2 × 2 factorial design with repeated measures)). Participants underwent the Cold Pressor Task (CPT) and were monitored for heart rate variability (HRV: RMSSD) and heart rate and reported pain levels. The Experiences in Close Relationships Questionnaire was used to measure attachment. RESULTS: Oxytocin reduced RMSSD (p = 0.003, partial ɳ2 = 0.03) and increased heart rate (p = 0.039, partial ɳ2 = 0.03) in individuals who received support, possibly reflecting an enhanced attentional state. Oxytocin did not enhance beneficial effects of social support on perceived pain, but increased pain intensity in avoidantly attached individuals who were supported by a friend (p = 0.009, partial ɳ2 = 0.06). LIMITATIONS: Only female participants were examined. Future studies are needed to determine sex differences in how oxytocin shapes stress-buffering effects of support. CONCLUSIONS: Oxytocin may enhance the salience of social proximity and may be a mechanism underlying previously reported social influences on cardiovascular and mental health. However, oxytocin effects depend on interpersonal insecurities and may trigger discomfort in avoidantly attached individuals. Caution about oxytocin's therapeutic promise is warranted.

Multi-modal responses to the Virtual Reality Trier Social Stress Test: A comparison with standard interpersonal and control conditions.

The Trier Social Stress Test (TSST) is a reliable social-evaluative stressor. To overcome limitations of the in vivo TSST, a standardized virtual reality TSST (VR-TSST) was developed. The present study compares the emotional (anxiety) and physiological (heart period and variability) response to a VR-TSST with an in vivo TSST and a control condition. Participants took part in either an in vivo TSST (N = 106, 64% female), VR-TSST (N = 52, 100% female), or a control TSST (N = 20, 40% female). Mixed linear modeling examined response profile differences related to TSST type. While there was an equivalent anxiety response to the in vivo TSST as the VR-TSST, we found a smaller heart period and heart rate variability response in VR-TSST compared to the in vivo TSST, especially in response to the math part of the test. The present findings demonstrate that social evaluative stress can be successfully induced in a VR setting, producing similar emotional and slightly attenuated cardiovascular responses.

The role of autonomy-connectedness in stress-modulating effects of social support in women: An experimental study using a virtual Trier Social Stress Test.

Social support is associated with mental well-being and favorable therapy outcomes. As autonomy-connectedness, the capacity for self-governance in interpersonal context, may affect reliance on others, we investigated whether stress-modulating effects of social support are moderated by autonomy-connectedness. Ninety-seven undergraduates completed measures on autonomy-connectedness and trait social anxiety, and attended a laboratory session with a friend (support) or alone (control). All underwent a virtual Trier Social Stress Test and completed anxiety, cortisol and heart rate (variability) measures. Preregistered analyses revealed that social support reduced anxiety reactivity and delayed heart rate variability decreases, but not heart rate. Contrary to hypotheses, autonomy-connectedness did not predict stress-reactivity or interact with condition. Exploratory analyses suggested effects of social support on cortisol reactivity and indicated that reported support quality varied by trait anxiety and self-awareness. Our findings underline the stress-modulating effects of social support and suggest that social support can benefit individuals with varying levels of autonomy-connectedness.

Oxytocin effects on resting-state heart rate variability in women: The role of childhood rearing experiences.

Oxytocin is known for its stress-reducing effects and has been associated with autonomic nervous system measures (ANS) involved in the stress response, such as heart rate variability (HRV). The current study examined the effects of intranasal oxytocin on HRV among women (oxytocin N â€‹= â€‹87, placebo N â€‹= â€‹86) during rest. Results show that oxytocin reduced RMSSD and low frequency (LF)-HRV, but only in women with positive childhood rearing experiences, and not in women with negative childhood experiences. These findings suggest that oxytocin plays a role in ANS regulation and that childhood rearing experiences may influence oxytocin effects on this stress regulating system.

Intranasal oxytocin enhances stress-protective effects of social support in women with negative childhood experiences during a virtual Trier Social Stress Test.

Oxytocin is considered a biological mechanism underlying stress-protective effects of positive social interactions. It is assumed to underlie the women-specific tend-and-befriend response to stress, although few studies have tested this assertion with female samples. The aim of the present study was, therefore, to test whether oxytocin enhances stress-protective effects of social support during stress in women, taking into account the moderating role of childhood adversity. The sample consisted of 180 female undergraduate students who had reported on experiences of childhood abuse and how often their mother used love withdrawal as an insensitive disciplinary strategy. Women participated in a virtual version of the Trier Social Stress Test (TSST) and were randomly assigned to receive 24 IU oxytocin or a placebo and to receive support or no support from a female friend (sub-groups N = 45). Results showed that oxytocin reduced heart rate variability during the TSST in participants who received support, possibly indicating that oxytocin increases attention and stimulates a challenge motivational state in the presence of a friend. In addition, we found that, in the presence of a friend, oxytocin reduced state anxiety levels and cortisol levels after the TSST, but only in women with higher levels of adverse childhood experiences. Our findings may indicate that oxytocin is a neurobiological means to attain and benefit from social support under stressful circumstances, which may be particularly adaptive for women with a history of adversity. Thus, oxytocin may function as motivator for affiliative disposition during stress exposure in women with a history of childhood adversity. Results should be replicated in clinical samples.

Autonomy deficits as vulnerability for anxiety: evidence from two laboratory-based studies.

BACKGROUND: Autonomous individuals are characterized by self-governance; awareness of and capacity to realize one's wishes and needs, while being connected with and sensitive towards others. In line with earlier research showing consistent associations between autonomy-connectedness deficits and anxiety, we tested in two studies whether autonomy deficits predict anxious responses to acute stressors. METHODS: In Study 1, participants (N = 177) viewed an anxiety-inducing film fragment and reported anxiety before and after viewing the clip. In experimental Study 2, participants (N = 100) were randomly allocated to one of two conditions: giving a short presentation to an audience (impromptu speech task) or watching another person's presentation (control condition). Anxiety was measured at baseline, after a preparation period and directly after the presentation. RESULTS: In Study 1, individuals' anxiety in reaction to watching the movie was positively associated with the autonomy-connectedness component sensitivity to others. In Study 2, individuals' anxiety in reaction to preparing the presentation was negatively associated with the autonomy-connectedness component self-awareness. CONCLUSIONS: Specific autonomy components may be related to experiencing anxiety in differing situations (i.e., related to others' distress or presenting one's personal views). Collectively these results indicate that autonomy-connectedness deficits may form a vulnerability factor for experiencing anxiety.

AP2 Gene Determines the Identity of Perianth Organs in Flowers of Arabidopsis thaliana.

We have examined the floral morphology and ontogeny of three mutants of Arabidopsis thaliana, Ap2-5, Ap2-6, and Ap2-7, that exhibit homeotic changes of the perianth organs because of single recessive mutations in the AP2 gene. Homeotic conversions observed are: sepals to carpels in all three mutants, petals to stamens in Ap2-5, and petals to carpels in Ap2-6. Our analysis of these mutants suggests that the AP2 gene is required early in floral development to direct primordia of the first and second whorls to develop as perianth rather than as reproductive organs. In addition, our results support one of the two conflicting hypotheses concerning the structures of the calyx and the gynoecium in the Brassicaceae.

Biosynthesis and secretion of plant cuticular wax.

The cuticle covers the aerial portions of land plants. It consists of amorphous intracuticular wax embedded in cutin polymer, and epicuticular wax crystalloids that coat the outer plant surface and impart a whitish appearance. Cuticular wax is mainly composed of long-chain aliphatic compounds derived from very long chain fatty acids. Wax biosynthesis begins with fatty acid synthesis in the plastid. Here we focus on fatty acid elongation (FAE) to very long chains (C24-C34), and the subsequent processing of these elongated products into alkanes, secondary alcohols, ketones, primary alcohols and wax esters. The identity of the gene products involved in these processes is starting to emerge. Other areas of this field remain enigmatic. For example, it is not known how the hydrophobic wax components are moved intracellularly, how they are exported out of the cell, or translocated through the hydrophilic cell wall. Two hypotheses are presented for intracellular wax transport: direct transfer of lipids from the endoplasmic reticulum to the plasma membrane, and Golgi mediated exocytosis. The potential roles of ABC transporters and non-specific lipid transfer proteins in wax export are also discussed. Biochemical-genetic and genomic approaches in Arabidopsis thaliana promise to be particularly useful in identifying and characterizing gene products involved in wax biosynthesis, secretion and function. The current review will, therefore, focus on Arabidopsis as a model for studying these processes.

[Word patterns in the LIM (Life-line Interview Method) / life story]. / Op zoek naar woordpatronen in het LIM / Levensverhaal.

In this exploratory study, life story data on the word patterns in the LIM (Life-line Interview Method) are reported for 98 men and women, almost equally divided over a younger (18-30), a middle-aged (31-55) and an older (56-84) age group. All respondents tell about their past in great detail, but have a short view of the future. In terms of word frequency are memories (past) and expectations (future) in the proportion of about five to one. As expected, older persons need more words for telling their past story than younger people; word counts of the future life story, however, do not yield in any difference between young, middle-aged and older men and women. In general, the word frequency for memories of negative and positive life events is in the proportion of about three to two. The significance of the LIM word patterns for practical interventions (reminiscence, life-review) is discussed briefly.

All fatty acids are not equal: discrimination in plant membrane lipids.

Plant membrane lipids are primarily composed of 16-carbon and 18-carbon fatty acids containing up to three double bonds. By contrast, the seed oils of many plant species contain fatty acids with significantly different structures. These unusual fatty acids sometimes accumulate to >90% of the total fatty acid content in the seed triacylglycerols, but are generally excluded from the membrane lipids of the plant, including those of the seed. The reasons for their exclusion and the mechanisms by which this is achieved are not completely understood. Here we discuss recent research that has given new insights into how plants prevent the accumulation of unusual fatty acids in membrane lipids, and how strict this censorship of membrane composition is. We also describe a transgenic experiment that resulted in an excessive buildup of unusual fatty acids in cellular membranes, and clearly illustrated that the control of membrane lipid composition is essential for normal plant growth and development.

The natural genetic variation of the fatty-acyl composition of seed oils in different ecotypes of Arabidopsis thaliana.

The fatty-acyl composition of the seed oil was determined for 100 ecotypes of Arabidopsis thaliana. Despite coming from diverse geographical locations, seed fatty-acyl profiles of all ecotypes were remarkably similar. They contained identical fatty acids, including the characteristic C20 and C22 very-long-chain fatty acids (VLCFAs). The total proportions of seed VLCFA varied between 22% and 35% w/w of the total seed fatty acid content.

Testing the usefulness of twin formation theory: the tocopherols and vitamin D.

The theoretical and empirical search for biologically and pharmacologically active molecules has long been of interest. In 1965 Revici proposed a class of biologically and pharmacologically active molecules which he described as having twin formations. Twin formations are defined as molecules containing two or more adjacent carbon atoms having the same induced electrical charge. An examination of recently discovered facts about the biological activity of the tocopherol family and of vitamin D lends support to this concept, which if true, could greatly facilitate selection of promising pharmacological substances for testing.

Altered regulation of lipid biosynthesis in a mutant of Arabidopsis deficient in chloroplast glycerol-3-phosphate acyltransferase activity.

The leaf membrane lipids of many plant species, including Arabidopsis thaliana (L.) Heynh., are synthesized by two complementary pathways that are associated with the chloroplast and the endoplasmic reticulum. By screening directly for alterations in lipid acyl-group composition, we have identified several mutants of Arabidopsis that lack the plastid pathway because of a deficiency in activity of the first enzyme in the plastid pathway of glycerolipid synthesis, acyl-ACP:sn-glycerol-3-phosphate acyltransferase (EC 2.3.1.15) (where ACP is acyl carrier protein). The lesion results in an increased synthesis of lipids by the cytoplasmic pathway that largely compensates for the loss of the plastid pathway and provides nearly normal amounts of all the lipids required for chloroplast biogenesis. However, the fatty acid composition of the leaf membrane lipids of the mutants is altered because the acyltransferases associated with the two pathways normally exhibit different substrate specificities. The remarkable flexibility of the system provides an insight into the nature of the regulatory mechanisms that allocate lipids for membrane biogenesis.

Expression of the wax-specific condensing enzyme CUT1 in Arabidopsis.

The Arabidopsis thaliana gene CUT1 encodes a very-long-chain fatty acid-condensing enzyme required for the production of epicuticular wax in bolting stems. We have examined the expression pattern of CUT1 in Arabidopsis at different developmental stages and under different environmental conditions. RNA blot analysis showed that CUT1 was highly expressed in shoots, but not in roots. CUT1 expression was detectable throughout development. Light was required for CUT1 expression, and expression was increased by salt and drought treatments. The promoter region of the CUT1 gene was cloned, and 1.2 kb of the sequence 5' to the translation start codon was used to direct beta-glucuronidase (GUS) expression in transgenic plants. Histochemical and fluorometric (quantitative) GUS assays confirmed that the CUT1 promoter directed epidermal-specific expression and was highly active in Arabidopsis and in tobacco. A construct using the CUT1 promoter to drive CUT1 expression (CUT1p-CUT1) was used to transform Arabidopsis. Transgenic plants which had somewhat increased (overexpression) or greatly reduced (co-suppression) wax loads were recovered. Thus, the CUT1 promoter should be useful for genetic engineering applications that require epidermis-specific expression of genes.

Production of hydroxy fatty acids in the seeds of Arabidopsis thaliana.

Seed-specific expression in Arabidopsis thaliana of oleate hydroxylase enzymes from castor bean and Lesquerella fendleri resulted in the accumulation of hydroxy fatty acids in the seed oil. By using various Arabidopsis mutant lines it was shown that the endoplasmic reticulum (ER) n-3 desaturase (FAD3) and the FAE1 condensing enzyme are involved in the synthesis of polyunsaturated and very-long-chain hydroxy fatty acids, respectively. In Arabidopsis plants with an active ER Delta12-oleate desaturase the presence of hydroxy fatty acids corresponded to an increase in the levels of 18:1 and a decrease in 18:2 levels. Expression in yeast indicates that the castor hydroxylase also has a low level of desaturase activity.