Summary
Cell division in plants is particularly important as cells cannot rearrange. It therefore determines the arrangement of cells (topology) and their size and shape (geometry). Cell division ...reduces mechanical stress locally by producing smaller cells and alters mechanical properties by reinforcing the mechanical wall network, both of which can alter overall tissue morphology. Division orientation is often regarded as following geometric rules, however recent work has suggested that divisions align with the direction of maximal tensile stress. Mechanical stress has already been shown to feed into many processes of development including those that alter mechanical properties. Such an alignment may enable cell division to selectively reinforce the cell wall network in the direction of maximal tensile stress. Therefore there exists potential feedback between cell division, mechanical stress and growth. Improving our understanding of this topic will help to shed light on the debated role of cell division in organ scale growth.
Plants are able to sense external mechanical stress, such as those due to gravity or obstacles, and alter their growth accordingly 1–8. Like animals 9, 10, plants can also sense internal mechanical ...stress that plays a role in regulating their development 11–19. The internal mechanical stresses also known as tissue stress can result from geometry, cell type, or differential growth 19–21. In a number of tissues, microtubules have been observed to align with mechanical stress predicted from their geometry. In the unidirectionally growing hypocotyl, the predicted tissue stresses do not reflect its cylindrical geometry. The epidermal layer experiences and resists the tensile stress coming from the expansion of the inner layers 22, 23; this is known as the epidermal-growth-control hypothesis. Here, we use our recently developed automated confocal micro-extensometer (ACME) 24 to apply relative compressive or tensile stresses to the intact Arabidopsis hypocotyls while monitoring growth and microtubule orientation in the different layers. A finite element model revealed that under relative tension, the pattern of tissue stresses was similar to that in the intact growing hypocotyl, while when relative compression was applied, the pattern of tissue stresses was overcome and the maximum stress direction in the epidermis changed to reflect what one would predict based on the geometry of the hypocotyl. Consistent with this, the microtubules in the epidermis changed orientation under relative compression. Once the direction of stress in the epidermis was altered, the growth of the organ increased.
•Simultaneous monitoring of growth, microtubule orientation, and mechanical stress•Microtubules align with the predicted maximal tensile stress direction•Constraining seedlings reverses the direction of tensile stress in the epidermis•Changing the direction of epidermal stress promotes hypocotyl axial growth
Seedling growth may be constrained by obstructions. Robinson and Kuhlemeier mimic this by applying compressive stresses to seedlings. They show that the normal pattern of tissue stress is such that the outer layer restricts growth. When constrained, the direction of tensile stress in the outer layer reverses, and growth is promoted.
Although there has yet been no undisputed discovery of a still-forming planet embedded in a gaseous protoplanetary disk, the cleared inner holes of transitional disks may be signposts of young ...planets. Here, we show that the subset of accreting transitional disks with wide, optically thin inner holes of 15 AU or more can only be sculpted by multiple planets orbiting inside each hole. Multiplanet systems provide two key ingredients for explaining the origins of transitional disks. First, multiple planets can clear wide inner holes where single planets open only narrow gaps. Second, the confined, non-axisymmetric accretion flows produced by multiple planets provide a way for an arbitrary amount of mass transfer to occur through an apparently optically thin hole without overproducing infrared excess flux. Rather than assuming that the gas and dust in the hole are evenly and axisymmetrically distributed, one can construct an inner hole with apparently optically thin infrared fluxes by covering a macroscopic fraction of the hole's surface area with locally optically thick tidal tails. We also establish that other clearing mechanisms, such as photoevaporation, cannot explain our subset of accreting transitional disks with wide holes. Transitional disks are therefore high-value targets for observational searches for young planetary systems.
For individuals experiencing intimate partner violence (IPV), formal services, including community agencies, health services, or the criminal justice system, are critical resources. Understanding the ...specific barriers that hinder or prevent survivors from seeking help from formal services could reveal important implications for the development of services for IPV as well as for members of other organizations who encounter survivors. The authors conducted a systematic review of the literature to identify barriers to help-seeking from formal services for survivors. Ten electronic databases were searched for key terms related to IPV, help seeking from formal services, and barriers to help seeking. Articles were included in the review if they were U.S.-based, contained samples that were adults who had experienced IPV, and discussed barriers to seeking help from formal services. An initial search yielded 1,155 articles and after screening, 29 articles were included in the review. Data were extracted to reveal the state of the literature regarding help-seeking barriers for survivors. Six barriers to help seeking were identified as follows: (1) lack of awareness, (2) access challenges, (3) consequences of disclosure, (4) lack of material resources, (5) personal barriers, and (6) system failures. These findings demonstrate the need for continued education surrounding available services for IPV as well as the continued development of resources that can mitigate personal barriers that survivors may face. Furthermore, these findings illuminate the necessity to increase the access of services, particularly for non-English speakers, immigrants and refugees, individuals with disabilities, men, and LGBTQIA identified individuals.
Several fungi in two different families--the Clavicipitaceae and the Trichocomaceae--produce different profiles of ergot alkaloids, many of which are important in agriculture and medicine. All ergot ...alkaloid producers share early steps before their pathways diverge to produce different end products. EasA, an oxidoreductase of the old yellow enzyme class, has alternate activities in different fungi resulting in branching of the pathway. Enzymes beyond the branch point differ among lineages. In the Clavicipitaceae, diversity is generated by the presence or absence and activities of lysergyl peptide synthetases, which interact to make lysergic acid amides and ergopeptines. The range of ergopeptines in a fungus may be controlled by the presence of multiple peptide synthetases as well as by the specificity of individual peptide synthetase domains. In the Trichocomaceae, diversity is generated by the presence or absence of the prenyl transferase encoded by easL (also called fgaPT1). Moreover, relaxed specificity of EasL appears to contribute to ergot alkaloid diversification. The profile of ergot alkaloids observed within a fungus also is affected by a delayed flux of intermediates through the pathway, which results in an accumulation of intermediates or early pathway byproducts to concentrations comparable to that of the pathway end product.
The oxidative potential of various secondary organic aerosols (SOA) was measured using dithiothreitol (DTT) assay to understand how organic aerosols react with cellular materials. SOA was produced ...via the photooxidation of four different hydrocarbons (toluene, 1,3,5-trimethylbenzene, isoprene and alpha -pinene) in the presence of NOx using a large outdoor photochemical smog chamber. The DTT consumption rate was normalized by the aerosol mass, which is expressed as DTTmass. Toluene SOA and isoprene SOA yielded higher DTTmass than 1,3,5-trimethylbenzene SOA or alpha -pinene SOA. In order to discover the correlation between the molecular structure and oxidative potential, the DTT responses of selected model compounds were also measured. Among them, conjugated aldehydes, quinones, and H2O2 showed considerable DTT response. To investigate the correlation between DTT response and cell responses in vitro, the expression of biological markers, i.e. IL-6, IL-8, and HMOX-1 were studied using small airway epithelial cells. Higher cellular expression of IL-8 was observed with toluene SOA exposure compared to 1,3,5-trimethylbenzene SOA exposure, which aligned with the results from DTT assay. Our study also suggests that within the urban atmosphere, the contribution of toluene SOA and isoprene SOA to the oxidative potential of ambient SOA will be more significant than that of alpha -pinene SOA.
Postpartum depression (PPD) is a significant public health concern due to the physical, emotional, economic, and life course outcomes. Rates of PPD are significantly higher for marginalised ...populations and can impact low‐income, minority, and/or immigrant women differently when compared to white middle‐class women. Commonly studied negative effects of PPD include poor health outcomes, mother–child bonding challenges, and negative child educational outcomes. However, research surveying the postpartum experience and negative outcomes among marginalised women is sparse. This study implemented a qualitative meta‐interpretive synthesis (QIMS) methodology to synthesise themes across 12 qualitative research articles surveying postpartum experiences of marginalised women in North American countries. Articles included in the QIMS were extracted from online databases from a 10‐year window spanning January 2008–2018. The guiding research question was “What are the PPD experiences of women belonging to marginalized populations?” Constant comparative analysis was used with coding in atlas.ti and themes were synthesised with input of all three authors. Five main themes emerged. The themes are (a) intersections of PPD and poverty, (b) culture and PPD, (c) pressures of mothering, (d) strengths and coping, and (e) abuse affects my PPD experience. Subthemes such as “I keep it to myself” relating to cultural response to PPD and idealised mothering were also discovered. Implications for social workers, nurses, and future research are discussed.
In the twinkling of an eye Flick, Sarah Robinson
Journal of religion, spirituality & aging,
07/2023, Letnik:
35, Številka:
3
Journal Article
Recenzirano
This essay explores the impact of inevitable uncertainty during the aging process and explores the effects of uncertainty on our spiritual experience during our elder years. It offers the role of ...touchstones as reminders of all that we have loved and posits that as long as we have breath, our deepest desires enfold us in our own spiritual growth. By deepening and broadening our understanding of desire, we can experience our individual spiritual growth as the product of love and compassion.
Book details
Edited by Robert L Anemone and Glen C. Conroy
Geospatial Approaches to the Anthropological Sciences
.
School for Advanced Research Press/University of New Mexico Press, 2018.
304 pages, ...ISBN: 978-082635967
A survivor’s decision to engage with formal services for experiences of intimate partner violence (IPV) is influenced by factors at the individual, interpersonal, and sociocultural levels. ...Understanding factors that facilitate survivors’ choice to seek services could be beneficial to formal service providers including community agencies, health professionals, and the criminal justice system, providing guidance toward the development and implementation of accessible services for survivors of IPV. This systematic review of the literature aims to identify key factors that facilitate survivors’ formal help-seeking. Ten electronic databases were searched for key terms related to help-seeking from formal services and facilitators of formal help-seeking. Articles were included in the review if the studies were conducted in the United States, focused on adults with experiences of IPV, and discussed facilitators of formal help-seeking. A total of 1,155 studies were initially identified, and after screening, 24 were included in the review. Seven factors were identified including provider knowledge, support, accessibility, desire to provide protection and to prevent future violence, and other factors such as knoweldge of and desire for services, policy factors, and personal factors. Findings demonstrate a need for more research on the facilitators of help-seeking among East Asian, South Asian, and Middle Eastern survivors living in the United States, as well as male-identified, trans, and gender nonconforming survivors. The review also indicates a need for culturally sensitive and accessible services that support survivors and the importance of raising awareness of the services and resources available for survivors.
PDF
