Czechia

The Arabidopsis genome contains genes encoding High Mobility Group (HMG) chromatin remodelers which function as transcription activators crucial for transcription of a plethora of genes. AtHMGB15, an ARID-HMG protein that harbors an AT rich interaction domain along with the classic HMG-Box DNA binding domain exhibits heightened expression primarily in flowers and pollen grains. The intricate process of male gametophyte development in flowering plants is regulated by jasmonic acid (JA) signaling. JA signalling initiates with the activation of MYC2 transcription factor, leading to the expression of numerous JA-responsive genes during stamen development, and pollen maturation. 

This study investigates the broader molecular analysis and biological relevance of transcriptional regulation of AtHMGB15 in orchestrating pollen development via the hormone pathway. Phenotypic characterization of athmgb15-4 mutant plants revealed delayed bolting, shorter siliques, and reduced seed set compared to the wildtype. Additionally, the mutation of AtHMGB15 resulted in defective pollen morphology, delayed pollen germination, aberrant pollen tube growth, and a higher percentage of non-viable pollen grains. In silico and molecular analysis validated the down-regulation of JA biosynthesis and signaling genes in the athmgb15-4 mutant. Quantitative analysis demonstrated that jasmonic acid and its derivatives were approximately tenfold lower in athmgb15-4 flowers. Exogenous application of methyl jasmonate could restore pollen morphology and germination alongside elevating the expression of previously down-regulated JA signaling genes, suggesting that the low jasmonate content in athmgb15-4 impaired JA signaling during pollen development. Furthermore, our study suggests that AtHMGB15 physically interacts with the MYC2 protein to form a transcription activation complex further promoting the transcription of two key JA signaling genes, namely MYB21 and MYB24, during stamen, and pollen development. 

We thereby propose the quintessential role of AtHMGB15 as a positive regulator of JA pathway, controlling the spatial, and temporal expression of key regulators involved in stamen and pollen development.

(Sachdev et. al., Plant Physiology 2024)

SEB Conference Prague 2024


Deciphering AtHMGB15, an ARID-HMG Protein in Arabidopsis: Orchestrating the JA Pathway Through MYC2 Regulation in Pollen Development.

jasmonic acid pathway

pollen development

arid-hmg

technical paper

If you see this page it means you are not logged in or registered.

If you  feel like you see this message by mistake please make sure you are logged in with the email you registered with.

If you are not registered yet you can do so [**here**](https://www.sebiology.org/events/seb-conference-prague-2024/registration2024.html). 

Please login or register

SEB’s Annual Conference is celebrated for creating the perfect composition of research, new discoveries and collaborative connections. Be creative and innovative by exchanging ideas and knowledge with masters of biology from all over the world.

For decades marine biologists and earth scientists have wanted to understand how changes in the seawater environment affect coral skeleton growth. That’s because coral calcification builds ecologically important coral reef structures and coral skeletons contain chemical signatures used as recorders of climate. The growth front of the coral skeleton does not come into direct contact with seawater, but instead forms in an extracellular calcifying medium (ECM) controlled by a specialised cell layer called the calcifying ‘calicoblastic’ epithelium. Unravelling the physiology of this calcifying epithelium (and coral physiology in general) is key to understanding why coral calcification responds to environment change. This challenge is an important focus of research at the Centre Scientifique de Monaco (CSM). Using an innovative coral sample preparation in controlled environmental experiments, we carry out in vivo physiological studies using a range of tools including confocal microscopy coupled with physiological indicator dyes and microelectrodes. This research has provided insight into regulation of pH, calcium and dissolved inorganic carbon concentration of the ECM by transcellular transport via the calicoblastic cells. We have also conducted investigations of paracellular transport to better understand how permeability of the calicoblastic epithelium determines exchange of ions and molecules between seawater and the ECM. We also investigate the impact of ocean acidification on these physiological parameters. Overall, our in vivo physiological data complement information arising from ‘omics’ studies on corals at CSM and other laboratories and helps us move towards a clearer understanding of coral calcification in a rapidly changing ocean.

An engineering epithelium: ion transport and pH regulation of the calcifying cell layer of reef-building corals

Thermal acclimation represents a key process enabling ectotherms to cope with changing environmental conditions, including climate change or biological invasions. Intraspecific variations in thermal acclimation may reflect adaptation to locally prevalent environmental conditions. Environmental gradients can provide useful models to study such processes. Here, we compared the thermal acclimation capacity of the invasive common periwinkle Littorina littorea, along a large latitudinal gradient. Specifically, we exposed adult snails collected from 10 different locations along Atlantic North America to 12 temperatures (5 to 27 C) and measured survival, feeding rate, growth, metabolic rate and Ctmax.
Our results showed that latitude, average summer temperature, and growing season length at the place of origin influenced snails’ thermal responses. In particular, snails from higher latitudes showed a higher capacity for acclimation, with increasing CTmax and feeding performance at higher temperatures. Furthermore, survival underwent a steeper decrease towards higher temperatures for snails from lower latitudes, showing they possess a better acclimation capacity in colder locations. In addition, growth and metabolic rate curves presented differences among snails from different locations. In conclusion, feeding, CTmax and survival results were coherent with a counter-gradient adaptive scenario. Low-latitude individuals may be lacking acclimation capacity because they already live near their thermal limits, while higher latitudes individuals may possess higher acclimation capacity to better exploit the shorter periods of warm temperatures they experience. Whereas growth and metabolic rate results indicate the presence of potential local adaptation, especially at the distribution edges, characterised by harsher conditions. 


Beat the heat. Thermal acclimation across latitudes reveals counter-gradient physiological variations in a widespread marine gastropod.

Amphibians are resilient species that have adapted during their long evolutionary history to rather diverse environmental conditions. Current climate change, however, is pushing many species tolerance limits, especially as it is translating into not only increased temperature but also, increased drought and shortened pond duration. Some species have evolved the ability to adaptively alter their phenotype in response to some of these factors, but the combination of hazards and the rate at which they are taking place, may exceed the ability of amphibians to cope. Reduced pond duration may trigger developmental acceleration in amphibian larvae, allowing them to reach metamorphosis sooner, but at the cost of doing so smaller and with depleted fat reserves. Moreover, if they metamorphose onto a harsher environment, the odds of survival during the juvenile stage may be severely reduced. We are studying the plastic responses of tadpoles of the spadefoot toad, Pelobates cultripes, to risk of pond drying, which is a complex combination of reduced water level, increased temperature, increased larval density and reduced food availability. We then also studied the carry-over effects of the developmental alterations experienced by larvae onto the juvenile stage, especially when they then face drier and warmer environments, monitoring juvenile survival, growth, activity pattern, hormonal levels and thermal tolerance.

Plastic responses of amphibians to shortened pond duration and increased drought and temperature

Insects use the adhesive force working on the soles of the legs for walking on the walls and ceilings. Particularly, fruit flies achieve stable wall walking due to the scale effect. However, the ground reaction force (GRF) during wall walking has not been measured because of lightness of their body. In this study, we use a force plate whose tilt angle can be adjusted to measure the total GRF of all legs in the shear and vertical directions when a fruit fly walks on a wall. The force plate has measuring section with an area of 10 mm^2 and spring structures that move in the shear and vertical directions, and it measures forces in two axes using Hooke's law. The resolution in both directions is 0.36 µN and 0.31 µN, which represents about 1/30 of its weight. It could be fabricated through a simple process by using thin film glass as the force plate material and processing the spring structure with a UV laser marker. It could adjust the inclination angle of the force plate via θ-axis stage, thereby the wall would be prepared. The GRF in two axis is measured when a fruit fly walks on the plate. When the force plate was placed horizontally, we confirmed that the fruit fly walked with almost no vibration in the shear and vertical directions.

Measurement of the ground reaction force of fruit fly using a tilted biaxial force plate

The ubiquitous presence of microplastics (MPs) in aquatic ecosystems is a growing concern. The ability to adsorb a variety of pollutants on its surface, including heavy metals, accentuates the magnitude of its impacts. The widespread contamination by MPs highlights the need to investigate the toxicological interactions of these polymers with heavy metals. Besides, there is still a gap in knowledge regarding the toxic effects of this mixture on microbiological interactions.
This study intended to evaluate the combined effects of MPs and copper on the intestinal microbiota. Polyethylene (PE) and polystyrene (PS) MPs were selected because of their extensive use and high accumulation in aquatic environments. For this, zebrafish (Danio rerio) were exposed for 21 days, to copper (Cu-25 μg/L), microplastics (PE and PS, 1mg/L), and the respective mixtures (PE-Cu and PS-Cu), to evaluate their effect on the intestinal wall ultrastructure and the intestinal microbiota.
The histopathological evaluation revealed changes, including necrosis, degeneration of intestinal folds, edema, infiltration of inflammatory cells, and goblet cells hyperplasia. Considering the intestinal microbiota, P. shigelloides was the microorganism present in the highest percentage (47%) and a multidrug resistance profile was observed in 67.6% of the isolated microorganisms. The highest resistance rates were observed in response to β lactam antibiotics, aminoglycosides, and tetracyclines.
This work has provided valuable insights into the intricate interaction between MPs and copper in the induction of histological changes, and antibiotic susceptibility.

This work is supported by National Funds by FCT - Portuguese Foundation for Science and Technology, under the project UIDB/04033/2020.

Gut microbiota and antibiotic susceptibility profile: combined effect of microplastics and copper in zebrafish (Danio rerio)

Organisms that occupy environments contaminated by radionuclides such as Chornobyl, Ukraine, face putative detrimental effects. How radioactive pollution affects organisms, especially in early life, is not well studied in the wild. Our study focuses on two interconnected factors that might be altered due to radionuclide contamination of the environment and influence fitness: early-life diet and gut microbiota, an important physiological constituent tied closely to diet and host physiology. We quantified fitness components, diet, and gut microbiota from nestlings of two passerine birds, Great tit (Parus major) and Pied flycatcher (Ficedula hypoleuca), by sampling animals in nest-boxes located in contaminated and uncontaminated areas within the Chornobyl Exclusion Zone, Ukraine. We used amplicon sequencing to identify dietary insects and to quantify the bacterial diversity and composition of the birds’ gut microbiota. Environmental radiation had no effect on fitness components (body condition and brood size) of either species. Both species had greater diversity in dietary insects in contaminated areas. In both bird species environmental radiation was not associated with bacterial diversity of gut microbiome, however radiation was associated with composition of microbiome. Other ecological factors: forest type, brood size and age were associated with P. major gut microbiome composition but not in F. hypoleuca. Our data show comparable responses in diet and gut microbiome of two wild species when exposed to environmental radionuclide contamination. These results give valuable insight to ecological processes in contaminated environment.

Environmental contamination by radionuclides alters diet and gut microbiota of wild passerines

Awarding gaps are differences in degree classification between demographic groups. In the UK there are known awarding gaps on the basis of ethnicity, socioeconomic status, age and disability. Progress on closure of gaps is notoriously slow, with inequity persisiting year after year. In this presentation I will explore the potential of innovative assessment in closing gaps. At the University of Hull we have made significant progress in closing awarding gaps, primarily through an institution wide focus on innovative, authentic competency based assessment. I will give an overview of this at institution level and within the biosciences, and provide practical suggestions for equitable assessment design

Closing Awarding Gaps through Innovative Assessment: A whole university approach

Temperature is a major factor governing the distribution and seasonal behavior of plants. The mild increasing ambient temperatures affect the growth rate and morphology of plants. Global warming makes it imperative to decipher how crops sense and transduce the warm temperature signals to physiological acclimations and developmental programs. We performed phenotyping on a spring barley collection consisting of 400 accessions grown at normal and mild warmer day-time temperatures and characterized the thermoresponsive traits at vegetative stages. Genome-wide association studies identified SNPs and their proximal genes associated with leaf length and tillering related traits. We examined the organ-specific transcriptome dynamics in three barley genotypes grown at two temperature conditions. The time-courses of differentially expressed genes induced by warmer temperatures reflect the varieties of thermoresponse speed, sensitivities, and acclimation in three genotypes. We also performed MNase-defined cistrome occupancy analysis (MOA-seq) to identify genomic regions with altered chromatin accessibility and transcription factor occupancy induced by warmer temperatures. Combining GWAS, transcriptome and cistrome, we identified novel regulators regulating barley thermomorphogenesis, which provides new perspectives for breeding climate-smart crops.



Feeling the warmth: the molecular mechanisms underlying the morphogenetic response of spring barley to warmer temperatures

Hypomethylation in plants is associated with improved stress responses and is therefore a favourable trait. However, when methylation mutants are produced there is often a transgenerational decrease in fitness, meaning this is not a viable avenue to explore in crops. 

Utilising a set of epigenetics recombinant inbred lines (epiRILs), where met1-3 was crossed with Col-0 to produce a ‘mosaic pattern’ in DNA methylation, we found that a region of chromosome 3 where was inheritance solely from the Col-0 parent. This region contains the gene IBM1, for which transgenerational deleterious effects has been previously associated with change in intronic methylation, leading to alternative splicing of the IBM1 transcript and ectopic genomic hypermethylation occurring at gene bodies. 
In the same regions we also found another gene, a vacuolar ATPase (VHA), had a similar methylation profile to IBM1 and complementary expression within the flower. We hypothesized that the interaction of IBM1 and VHA could explain the transgenerational decrease in fitness observed in met1-3 plants. Existing RNA-seq data was assessed for this possibility, and a range of genetic approaches were applied including crossing of IBM1 and VHA knockout mutants and CRISPR-Cas9 to generate double mutants. 
We propose there is incompatibility between the pollen and carpels of these methylation mutants, ultimately resulting in decreased fitness and viability


Interaction of IBM1 and a vacuolar ATPase in flowers may explain transgenerational instability of hypomethylated lines

In wild vertebrates, age has a strong influence on individual reproductive performance. Specifically, young parents are less likely to successfully rear offspring relative to older ones because of lower parental skills, lower parental investment or because of a progressive disappearance of lower-quality individuals at young ages (i.e., according to the constraint, restraint and selection hypotheses respectively). Such phenomenon has been extensively studied through reproductive success’ features. However, to better evaluate the influence of age on reproductive performance in species with high reproductive success, assessing also the quality of developmental conditions and offspring phenotype appears crucial. While it is practically difficult to follow an offspring during its entire life, several proxies of nestlings’ quality can be useful to assess the ability of young to survive and recruit into the population (i.e., body condition, corticosterone levels, and telomere length). By sampling chicks reared by known-aged mothers, we specifically investigated the influence of maternal age on offspring quality in two long-lived seabird species, the Black-browed Albatross (Thalassarche melanophrys) and the Snow Petrel (Pagodroma nivea). In both species, maternal age is correlated to proxies of offspring quality. More precisely, older individuals provide better parental cares to their offspring. In the light of the three age-related improvement of reproductive performance hypotheses, our results suggest that maternal age can affect offspring phenotype with potential long-term consequences.

Deciphering AtHMGB15, an ARID-HMG Protein in Arabidopsis: Orchestrating the JA Pathway Through MYC2 Regulation in Pollen Development.

Downloads

Next from SEB Conference Prague 2024

An engineering epithelium: ion transport and pH regulation of the calcifying cell layer of reef-building corals

Stay up to date with the latest Underline news!

PRESENTATIONS

CONFERENCES

COMPANY

RESOURCES

Deciphering AtHMGB15, an ARID-HMG Protein in Arabidopsis: Orchestrating the JA Pathway Through MYC2 Regulation in Pollen Development.

.css-70qvj9{display:-webkit-box;display:-webkit-flex;display:-ms-flexbox;display:flex;-webkit-align-items:center;-webkit-box-align:center;-ms-flex-align:center;align-items:center;}Downloads

Next from SEB Conference Prague 2024

An engineering epithelium: ion transport and pH regulation of the calcifying cell layer of reef-building corals

Stay up to date with the latest Underline news!

PRESENTATIONS

CONFERENCES

COMPANY

RESOURCES

Downloads