Regulation of shoot meristem shape by photoperiodic signaling and phytohormones during floral induction of Arabidopsis

Floral transition, the onset of plant reproduction, involves changes in shape and identity of the shoot apical meristem (SAM). The change in shape, termed doming, occurs early during floral transition when it is induced by environmental cues such as changes in day-length, but how it is regulated at the cellular level is unknown. We defined the morphological and cellular features of the SAM during floral transition of Arabidopsis thaliana. Both cell number and size increased during doming, and these changes were partially controlled by the gene regulatory network (GRN) that triggers flowering. Furthermore, dynamic modulation of expression of gibberellin (GA) biosynthesis and catabolism enzymes at the SAM contributed to doming. Expression of these enzymes was regulated by two MADS-domain transcription factors implicated in flowering. We provide a temporal and spatial framework for integrating the flowering GRN with cellular changes at the SAM and highlight the role of local regulation of GA.

Download Full-text

Systematic analyses of the MIR172 family members of Arabidopsis define their distinct roles in regulation of APETALA2 during floral transition

PLoS Biology ◽

10.1371/journal.pbio.3001043 ◽

2021 ◽

Vol 19 (2) ◽

pp. e3001043

Author(s):

Diarmuid S. Ó’Maoiléidigh ◽

Annabel D. van Driel ◽

Anamika Singh ◽

Qing Sang ◽

Nolwenn Le Bec ◽

...

Keyword(s):

Arabidopsis Thaliana ◽

Gene Regulatory Networks ◽

Shoot Apex ◽

Regulatory Networks ◽

Floral Induction ◽

Mature Mirnas ◽

Floral Transition ◽

Shoot Meristem ◽

Gene Regulatory

MicroRNAs (miRNAs) play important roles in regulating flowering and reproduction of angiosperms. Mature miRNAs are encoded by multiple MIRNA genes that can differ in their spatiotemporal activities and their contributions to gene regulatory networks, but the functions of individual MIRNA genes are poorly defined. We functionally analyzed the activity of all 5 Arabidopsis thaliana MIR172 genes, which encode miR172 and promote the floral transition by inhibiting the accumulation of APETALA2 (AP2) and APETALA2-LIKE (AP2-LIKE) transcription factors (TFs). Through genome editing and detailed confocal microscopy, we show that the activity of miR172 at the shoot apex is encoded by 3 MIR172 genes, is critical for floral transition of the shoot meristem under noninductive photoperiods, and reduces accumulation of AP2 and TARGET OF EAT2 (TOE2), an AP2-LIKE TF, at the shoot meristem. Utilizing the genetic resources generated here, we show that the promotion of flowering by miR172 is enhanced by the MADS-domain TF FRUITFULL, which may facilitate long-term silencing of AP2-LIKE transcription, and that their activities are partially coordinated by the TF SQUAMOSA PROMOTER-BINDING-LIKE PROTEIN 15. Thus, we present a genetic framework for the depletion of AP2 and AP2-LIKE TFs at the shoot apex during floral transition and demonstrate that this plays a central role in floral induction.

Download Full-text

Increasing photoperiod stimulates the initiation of spring migratory behaviour and physiology in a facultative migrant, the pine siskin

Royal Society Open Science ◽

10.1098/rsos.180876 ◽

2018 ◽

Vol 5 (8) ◽

pp. 180876 ◽

Cited By ~ 7

Author(s):

Ashley R. Robart ◽

Mali M. K. McGuire ◽

Heather E. Watts

Keyword(s):

Experimental Test ◽

Spring Migration ◽

Fat Deposition ◽

Day Length ◽

Environmental Cues ◽

Migratory Restlessness ◽

Migratory Behaviour ◽

Behavioural Changes ◽

Short Day

The transition to a migratory state involves coordinated changes in physiology and behaviour. In species with regular, predictable (obligate) migrations, increasing day length triggers the expression of a spring migratory state and androgens play an important role in stimulating its development. By contrast, we know little about the environmental cues and endocrine mechanisms that regulate migration in species with less predictable (facultative) migrations. Here, we tested whether photoperiod stimulates a migratory state in a facultative nomadic migrant, the pine siskin ( Spinus pinus ). We exposed wintering birds to either a naturally increasing or short-day photoperiod and measured physiological and behavioural changes indicative of a migratory state. We also examined changes in circulating hormones that may play a role in the migratory transition. Natural-day, but not short-day, birds displayed physiological preparations for migration, including increases in fat deposition, and showed increased levels of migratory restlessness. We found no evidence for a role of corticosterone in the migratory transition, but testosterone may be important. This study is the first experimental test of the role of photoperiod in regulating facultative migration and demonstrates that the predictive cue used by many obligate migrants to time spring migration is also important in a facultative migrant.

Download Full-text

An Acromegaly Disease Zebrafish Model Reveals Decline in Body Stem Cell Number along with Signs of Premature Aging

Biology ◽

10.3390/biology9060120 ◽

2020 ◽

Vol 9 (6) ◽

pp. 120

Author(s):

Abdalla Elbialy ◽

Yoji Igarashi ◽

Shuichi Asakawa ◽

Shugo Watabe ◽

Shigeharu Kinoshita

Keyword(s):

Stem Cells ◽

Growth Hormone ◽

Pathological Condition ◽

Cell Number ◽

Cellular Level ◽

The Body ◽

Premature Aging ◽

Cell Integrity ◽

Zebrafish Model

In our previous publication, it was shown that growth hormone (GH) excess in acromegaly affects the cell integrity of somatic cells through increased DNA damage throughout the body and impaired DNA repair pathways. Acromegaly is a hormone disorder pathological condition that develops as a result of growth hormone over-secretion from the pituitary gland. We produced a zebrafish acromegaly model to gain a better understanding of the excess GH effects at the cellular level. Here we show that the acromegaly zebrafish model progressively reduced the number of stem cells in different organs and increased oxidative stress in stem cells. Importantly, the decline in the stem cells was even more apparent than in aged fish. The controversy and debate over the use of GH as an anti-aging therapy have been going on for several years. In this study, excess GH induced aging signs such as increased senescence-associated (SA)-β-galactosidase staining of abdominal skin and similarity of the pattern of gene expression between aged and acromegaly zebrafish. Thus, this study highlights the role of excess GH in acromegaly stem cells.

Download Full-text

EpiLog: A software for the logical modelling of epithelial dynamics

F1000Research ◽

10.12688/f1000research.15613.2 ◽

2019 ◽

Vol 7 ◽

pp. 1145 ◽

Cited By ~ 2

Author(s):

Pedro L. Varela ◽

Camila V. Ramos ◽

Pedro T. Monteiro ◽

Claudine Chaouiya

Keyword(s):

Regulatory Networks ◽

Cellular Responses ◽

Tissue Level ◽

Cellular Level ◽

Environmental Cues ◽

Link Type ◽

Qualitative Models ◽

Logical Modelling ◽

Gene Regulatory ◽

External Signals

Cellular responses are governed by regulatory networks subject to external signals from surrounding cells and to other micro-environmental cues. The logical (Boolean or multi-valued) framework proved well suited to study such processes at the cellular level, by specifying qualitative models of involved signalling pathways and gene regulatory networks. Here, we describe and illustrate the main features of EpiLog, a computational tool that implements an extension of the logical framework to the tissue level. EpiLog defines a collection of hexagonal cells over a 2D grid, which embodies a mono-layer epithelium. Basically, it defines a cellular automaton in which cell behaviours are driven by associated logical models subject to external signals. EpiLog is freely available on the web at http://epilog-tool.org. It is implemented in Java (version ≥1.7 required) and the source code is provided at https://github.com/epilog-tool/epilog under a GNU General Public License v3.0.

Download Full-text

Gene regulatory networks controlled by FLOWERING LOCUS C that confer variation in seasonal flowering and life history

Journal of Experimental Botany ◽

10.1093/jxb/eraa216 ◽

2020 ◽

Cited By ~ 1

Author(s):

Eva Madrid ◽

John W Chandler ◽

George Coupland

Keyword(s):

Gene Regulatory Networks ◽

Regulatory Networks ◽

Target Genes ◽

Higher Plants ◽

Floral Transition ◽

Environmental Cues ◽

Flowering Locus C ◽

Gene Regulatory ◽

Flowering Locus

Abstract Responses to environmental cues synchronize reproduction of higher plants to the changing seasons. The genetic basis of these responses has been intensively studied in the Brassicaceae. The MADS-domain transcription factor FLOWERING LOCUS C (FLC) plays a central role in the regulatory network that controls flowering of Arabidopsis thaliana in response to seasonal cues. FLC blocks flowering until its transcription is stably repressed by extended exposure to low temperatures in autumn or winter and, therefore, FLC activity is assumed to limit flowering to spring. Recent reviews describe the complex epigenetic mechanisms responsible for FLC repression in cold. We focus on the gene regulatory networks controlled by FLC and how they influence floral transition. Genome-wide approaches determined the in vivo target genes of FLC and identified those whose transcription changes during vernalization or in flc mutants. We describe how studying FLC targets such as FLOWERING LOCUS T, SQUAMOSA PROMOTER BINDING PROTEIN-LIKE 15, and TARGET OF FLC AND SVP 1 can explain different flowering behaviours in response to vernalization and other environmental cues, and help define mechanisms by which FLC represses gene transcription. Elucidating the gene regulatory networks controlled by FLC provides access to the developmental and physiological mechanisms that regulate floral transition.

Download Full-text

EpiLog: A software for the logical modelling of epithelial dynamics

F1000Research ◽

10.12688/f1000research.15613.1 ◽

2018 ◽

Vol 7 ◽

pp. 1145 ◽

Cited By ~ 5

Author(s):

Pedro L. Varela ◽

Camila V. Ramos ◽

Pedro T. Monteiro ◽

Claudine Chaouiya

Keyword(s):

Regulatory Networks ◽

Cellular Responses ◽

Tissue Level ◽

Cellular Level ◽

Environmental Cues ◽

Link Type ◽

Qualitative Models ◽

Logical Modelling ◽

Gene Regulatory ◽

External Signals

Download Full-text

How do histone modifications contribute to transgenerational epigenetic inheritance in C. elegans?

Biochemical Society Transactions ◽

10.1042/bst20190944 ◽

2020 ◽

Vol 48 (3) ◽

pp. 1019-1034 ◽

Cited By ~ 1

Author(s):

Rachel M. Woodhouse ◽

Alyson Ashe

Keyword(s):

Histone Modifications ◽

Molecular Mechanisms ◽

Epigenetic Inheritance ◽

Nematode Caenorhabditis Elegans ◽

Histone Methyltransferases ◽

Transgenerational Epigenetic Inheritance ◽

C Elegans ◽

Recent Developments ◽

Gene Regulatory

Gene regulatory information can be inherited between generations in a phenomenon termed transgenerational epigenetic inheritance (TEI). While examples of TEI in many animals accumulate, the nematode Caenorhabditis elegans has proven particularly useful in investigating the underlying molecular mechanisms of this phenomenon. In C. elegans and other animals, the modification of histone proteins has emerged as a potential carrier and effector of transgenerational epigenetic information. In this review, we explore the contribution of histone modifications to TEI in C. elegans. We describe the role of repressive histone marks, histone methyltransferases, and associated chromatin factors in heritable gene silencing, and discuss recent developments and unanswered questions in how these factors integrate with other known TEI mechanisms. We also review the transgenerational effects of the manipulation of histone modifications on germline health and longevity.

Download Full-text

Giscience in the Mountain Geography

Tribhuvan University Journal ◽

10.3126/tuj.v27i1-2.26390 ◽

2010 ◽

Vol 27 (1-2) ◽

pp. 81-90

Author(s):

Krishna Poudel

Keyword(s):

Spatial Data ◽

Environmental Data ◽

Temporal Data ◽

Observation Systems ◽

Research Findings ◽

Temporal And Spatial ◽

Temporal And Spatial Characteristics ◽

Mountain Geography ◽

Different Sources

Mountains have distinct geography and are dynamic in nature compared to the plains. 'Verticality' and 'variation' are two fundamental specificities of the mountain geography. They possess distinct temporal and spatial characteristics in a unique socio-cultural setting. There is an ever increasing need for spatial and temporal data for planning and management activities; and Geo Information (GI) Science (including Geographic Information and Earth Observation Systems). This is being recognized more and more as a common platform for integrating spatial data with social, economic and environmental data and information from different sources. This paper investigates the applicability and challenges of GISscience in the context of mountain geography with ample evidences and observations from the mountain specific publications, empirical research findings and reports. The contextual explanation of mountain geography, mountain specific problems, scientific concerns about the mountain geography, advances in GIScience, the role of GIScience for sustainable development, challenges on application of GIScience in the contexts of mountains are the points of discussion. Finally, conclusion has been made with some specific action oriented recommendations.

Download Full-text

The Gene Regulatory Roles of Herbal Extracts on the Growth, Immune System, and Reproduction of Fish

Animals ◽

10.3390/ani11082167 ◽

2021 ◽

Vol 11 (8) ◽

pp. 2167

Author(s):

Ehsan Ahmadifar ◽

Hamideh Pourmohammadi Fallah ◽

Morteza Yousefi ◽

Mahmoud A. O. Dawood ◽

Seyed Hossein Hoseinifar ◽

...

Keyword(s):

Immune System ◽

Mode Of Action ◽

Medicinal Herbs ◽

Environmental Stressors ◽

Fish Diet ◽

Sustainable Aquaculture ◽

Herbal Supplements ◽

Aquatic Animals ◽

Gene Regulatory

The crucial need for safe and healthy aquatic animals obligates researchers in aquaculture to investigate alternative and beneficial additives. Medicinal herbals and their extracts are compromised with diverse effects on the performances of aquatic animals. These compounds can affect growth performance and stimulate the immune system when used in fish diet. In addition, the use of medicinal herbs and their extracts can reduce oxidative stress induced by several stressors during fish culture. Correspondingly, aquatic animals could gain increased resistance against infectious pathogens and environmental stressors. Nevertheless, the exact mode of action where these additives can affect aquatic animals’ performances is still not well documented. Understanding the mechanistic role of herbal supplements and their derivatives is a vital tool to develop further the strategies and application of these additives for feasible and sustainable aquaculture. Gene-related studies have clarified the detailed information on the herbal supplements’ mode of action when administered orally in aquafeed. Several review articles have presented the potential roles of medicinal herbs on the performances of aquatic animals. However, this review article discusses the outputs of studies conducted on aquatic animals fed dietary, medicinal herbs, focusing on the gene expression related to growth and immune performances. Furthermore, a particular focus is directed to the expected influence of herbal supplements on the reproduction of aquatic animals.

Download Full-text

Applying Expanded Servicescape to the Hotel Industry

Journal of Hospitality & Tourism Research ◽

10.1177/10963480211011535 ◽

2021 ◽

pp. 109634802110115

Author(s):

Seonjeong (Ally) Lee ◽

Ning-Kuang Chuang

Keyword(s):

Quality Of Life ◽

Customer Loyalty ◽

Physical Environment ◽

Online Survey ◽

Hotel Industry ◽

Holistic Approach ◽

Environmental Cues ◽

Practical Implications

The physical environment plays an essential role in customers’ hotel stay experiences. Hotels offer a differentiated atmosphere that creates favorable customers’ evaluations. Based on the significant role of environmental cues, this study investigates the effects of an expanded servicescape on customers’ evaluations, including customer satisfaction, quality of life, and customer loyalty, in the context of the hotel industry. To test the proposed research framework, this study collects data from previous hotel customers and conducts a self-administered, online survey. Findings identified ambience, interactions with employees, authenticity, and fascination positively influenced customers’ satisfaction, which further influenced customer loyalty. Only ambience and fascination positively influenced quality of life, which in turn influenced customer loyalty. Results contributed to the application of expanded servicescape in the hotel context. Results also suggested practical implications of the holistic approach of servicescape in the hotel industry.

Download Full-text