Gravity Response Research Articles

Simultaneous mutations in ITPK4 and MRP5 genes result in a low phytic acid level without compromising salt tolerance in Arabidopsis.

Generation of crops with low phytic acid (myo-inositol-1,2,3,4,5,6-hexakisphosphate (InsP6)) is an important breeding direction, but such plants often display less desirable agronomic traits. In this study, through ethyl methanesulfonate-mediated mutagenesis, we found that inositol 1,3,4-trisphosphate 5/6-kinase 4 (ITPK4), which is essential for producing InsP6, is a critical regulator of salt tolerance in Arabidopsis. Loss of function of ITPK4 gene leads to reduced root elongation under salt stress, which is primarily because of decreased root meristem length and reduced meristematic cell number. The itpk4 mutation also results in increased root hair density and increased accumulation of reactive oxygen species during salt exposure. RNA sequencing assay reveals that several auxin-responsive genes are down-regulated in the itpk4-1 mutant compared to the wild-type. Consistently, the itpk4-1 mutant exhibits a reduced auxin level in the root tip and displays compromised gravity response, indicating that ITPK4 is involved in the regulation of the auxin signaling pathway. Through suppressor screening, it was found that mutation of Multidrug Resistance Protein 5 (MRP5)5 gene, which encodes an ATP-binding cassette (ABC) transporter required for transporting InsP6 from the cytoplasm into the vacuole, fully rescues the salt hypersensitivity of the itpk4-1 mutant, but in the itpk4-1 mrp5 double mutant, InsP6 remains at a very low level. These results imply that InsP6 homeostasis rather than its overall amount is beneficial for stress tolerance in plants. Collectively, this study uncovers a pair of gene mutations that confer low InsP6 content without impacting stress tolerance, which offers a new strategy for creating "low-phytate" crops.

High-Efficiency Forward Modeling of Gravitational Fields in Spherical Harmonic Domain with Application to Lunar Topography Correction

Gravity forward modeling as a basic tool has been widely used for topography correction and 3D density inversion. The source region is usually discretized into tesseroids (i.e., spherical prisms) to consider the influence of the curvature of planets in global or large-scale problems. Traditional gravity forward modeling methods in spherical coordinates, including the Taylor expansion and Gaussian–Legendre quadrature, are all based on spatial domains, which mostly have low computational efficiency. This study proposes a high-efficiency forward modeling method of gravitational fields in the spherical harmonic domain, in which the gravity anomalies and gradient tensors can be expressed as spherical harmonic synthesis forms of spherical harmonic coefficients of 3D density distribution. A homogeneous spherical shell model is used to test its effectiveness compared with traditional spatial domain methods. It demonstrates that the computational efficiency of the proposed spherical harmonic domain method is improved by four orders of magnitude with a similar level of computational accuracy compared with the optimized 3D GLQ method. The test also shows that the computational time of the proposed method is not affected by the observation height. Finally, the proposed forward method is applied to the topography correction of the Moon. The results show that the gravity response of the topography obtained with our method is close to that of the optimized 3D GLQ method and is also consistent with previous results.

Resolution analysis of the gravity survey network in the middle and south sections of Tan-Lu fault and recent changes in the gravity field

In this paper, we computed the fractal dimension of three survey areas within the central and southern sections of the Tan-Lu fault zone using fractal analysis. Subsequently, simulations were conducted to analyze the gravity response under a forward model of equivalent density changes. Additionally, we thoroughly investigated the seismic monitoring capabilities of the gravity network in the central and southern regions of the Tan-Lu fault. Expanding on these analyses. Recent gravity field variations were examined in the mid-southern segment of the Tan-Lu fault zone and its surrounding areas from 2013 to 2023. The results indicate that the observation capabilities of the northern network in the study area outperform those of the southern gravity network, with the northern network demonstrating a more evenly distributed coverage. The optimal gravity anomaly recovery effect for the entire study area is achieved at a resolution of 0.5° × 0.5°. With an equivalent observable signal in the range of 30 × 10−8 m/s2 to 40 × 10−8 m/s2, the spatial resolution of the gravity network's field source is estimated to be approximately 55 km. From 2013 to 2023, a significant positive change has been observed in the gravity field within the study area. The Tan-Lu fault zone plays a crucial role in governing the crustal movement in this region, with the dextral strike-slip movement trend of the fault persisting. Small earthquakes occur more frequently in the southern section of the fault zone, while strong earthquakes are less common. The alignment of gravity field changes with the fault strike indicates ongoing activity in the fault zone without any signs of locking. In the central segment of the Tan-Lu fault zone in the Shandong region, there appears to be a weaker correlation between gravity field changes and fault trends. This discrepancy may suggest that the area is locked, resulting in the accumulation of stress and strain. It is imperative to monitor the continuous evolution of the gravity field in this region to gain insights into potential seismic risks.

Implementation of the Gauss-Kronrod Quadrature Method (G7, K15) on 2D Gravity Anomaly Modeling in Basins with a Polynomial Variation of Density Distribution with Depth

Forward modeling of 2D gravity anomalies, considering density contrasts that vary polynomially with depth, was performed to examine basin structures. This process involved two main stages: deriving analytical formulas and executing numerical integration. The Gauss-Kronrod Quadrature Method, utilizing 7 Gauss points and 15 Kronrod points, was employed to precisely compute these integrals. Initial modeling applied to theoretical basement scenarios with fixed density contrasts showed gravity anomalies that accurately reflected the curvature of the basement. To validate the approach, it was then applied to real-world cases including the Sebastian Vizcaino Basin, San Jacinto Graben, and Sayula Basin. By incorporating suitable density contrasts, modeling lengths, and basement curvature shapes, the results revealed that both fixed-density and depth-variable density models produced gravity anomalies with patterns consistent with the actual basement curvature. These findings validate the modeling technique’s effectiveness in representing real geological features accurately. The study confirms that the Gauss-Kronrod Quadrature Method (G7, K15) is robust for analyzing 2D gravity anomalies, providing a reliable tool for understanding the influence of varying density contrasts on gravity responses.

PagKNAT2/6b regulates tension wood formation and gravitropism by targeting cytokinin metabolism.

Tension wood is a specialized xylem tissue associated with gravitropism in angiosperm trees. However, few regulators of tension wood formation have been identified. The molecular mechanisms underpinning tension wood formation remain elusive. Here, we report that a Populus KNOTTED-like homeobox gene, PagKNAT2/6b, is involved in tension wood formation and gravity response. Transgenic poplar plants overexpressing PagKNAT2/6b displayed more sensitive gravitropism than controls, as indicated by increased stem curvature. Microscopic examination revealed greater abundance of fibre cells with a gelatinous cell wall layer (G-layer) and asymmetric growth of secondary xylem in PagKNAT2/6b overexpression lines. Conversely, PagKNAT2/6b dominant repression plants exhibited decreased tension wood formation and reduced response to gravity stimulation. Moreover, sensitivity to gravity stimulation showed a negative relationship with development stage. Expression of genes related to growth and senescence was affected in PagKNAT2/6b transgenic plants. More importantly, transcription activation and electrophoretic mobility shift assays suggested that PagKNAT2/6b promotes the expression of cytokinin metabolism genes. Consistently, cytokinin content was increased in PagKNAT2/6b overexpression plants. Therefore, PagKNAT2/6b is involved in gravitropism and tension wood formation, likely via modulation of cytokinin metabolism.

BTA2 regulates tiller angle and the shoot gravity response through controlling auxin content and distribution in rice.

Tiller angle is a key agricultural trait that establishes plant architecture, which in turn strongly affects grain yield by influencing planting density in rice. The shoot gravity response plays a crucial role in the regulation of tiller angle in rice, but the underlying molecular mechanism is largely unknown. Here, we report the identification of the BIG TILLER ANGLE2 (BTA2), which regulates tiller angle by controlling the shoot gravity response in rice. Loss-of-function mutation of BTA2 dramatically reduced auxin content and affected auxin distribution in rice shoot base, leading to impaired gravitropism and therefore a big tiller angle. BTA2 interacted with AUXIN RESPONSE FACTOR7 (ARF7) to modulate rice tiller angle through the gravity signaling pathway. The BTA2 protein was highly conserved during evolution. Sequence variation in the BTA2 promoter of indica cultivars harboring a less expressed BTA2 allele caused lower BTA2 expression in shoot base and thus wide tiller angle during rice domestication. Overexpression of BTA2 significantly increased grain yield in the elite rice cultivar Huanghuazhan under appropriate dense planting conditions. Our findings thus uncovered the BTA2-ARF7 module that regulates tiller angle by mediating the shoot gravity response. Our work offers a target for genetic manipulation of plant architecture and valuable information for crop improvement by producing the ideal plant type.

Optimizing Baby Telon Oil Preparation Formula Tree Tea Oil (Melaleuca alternifolia Cheel) with VCO and Olive Oil Variations using the Simplex Lattice Design Method

One of the plants that can be used as a natural medicine is the tea tree plant (Melaleuca alternifolia Cheel) which is generally known as the tea tree. The tea tree plant contains essential oils which are useful as antimicrobial and anti-inflammatory. Another plant that can be used as a natural ingredient is the fennel plant (Foeniculum vulgare Mill) which contains essential oils which are useful as antimicrobials. In order to develop the preparation, a telon oil preparation was formulated. The use of additional ingredients in the formulation of telon oil preparations, namely VCO and Olive Oil as vegetable oils which function as solvents for essential oils, can certainly affect the physical properties of telon oil preparations, so a method is needed to find an optimum formula that meets the good physical properties of the preparation. This research aims to determine the optimum formula composition of telon oil preparations with variations of VCO and Olive Oil using the Simplex Lattice Design method by looking at the results of evaluation tests of the physical properties of telon oil preparations which include organoleptic tests, homogeneity tests, pH tests, specific gravity tests, viscosity tests and displaced volume test. The results of organoleptic tests, homogeneity, pH, specific gravity, viscosity and transferred volume have met the requirements. Analysis using SLD showed that the optimal preparation formula for baby telon tree tea oil (Melaleuca alternifolia Cheel) was obtained with a VCO and Olive Oil composition of 78.4% and 19.6% with a specific gravity response value of 0.906 gr/ml, viscosity 36.84 cp and volume transferred 57.33 ml. In the hedonic testing of baby telon oil preparations, tree tea oil (Melaleuca alternifolia Cheel) with variations of VCO and olive oil from the optimum formula in terms of color was preferred more by the panelists.

Molecular mechanism of brassinosteroids involved in root gravity response based on transcriptome analysis

BackgroundBrassinosteroids (BRs) are a class of phytohormones that regulate a wide range of developmental processes in plants. BR-associated mutants display impaired growth and response to developmental and environmental stimuli.ResultsHere, we found that a BR-deficient mutant det2-1 displayed abnormal root gravitropic growth in Arabidopsis, which was not present in other BR mutants. To further elucidate the role of DET2 in gravity, we performed transcriptome sequencing and analysis of det2-1 and bri1-116, bri1 null mutant allele. Expression levels of auxin, gibberellin, cytokinin, and other related genes in the two mutants of det2-1 and bri1-116 were basically the same. However, we only found that a large number of JAZ (JASMONATE ZIM-domain) genes and jasmonate synthesis-related genes were upregulated in det2-1 mutant, suggesting increased levels of endogenous JA.ConclusionsOur results also suggested that DET2 not only plays a role in BR synthesis but may also be involved in JA regulation. Our study provides a new insight into the molecular mechanism of BRs on the root gravitropism.

Stable computation of analytical expressions for the gravity and magnetic field response of distant polyhedral targets

Stable computation of analytical expressions for the gravity and magnetic field response of distant polyhedral targets

Callose Metabolism in Flax Fibers During Gravity Response: Analysis of Gene Expression

Callose Metabolism in Flax Fibers During Gravity Response: Analysis of Gene Expression

Expression of auxin transporter genes in flax (Linum usitatissimum) fibers during gravity response.

Gravitropism is an adaptive reaction of plants associated with the ability of various plant organs to be located and to grow in a certain direction relative to the gravity vector, while usually the asymmetric distribution of the phytohormone auxin is a necessary condition for the gravitropical bending of plant organs. Earlier, we described significant morphological changes in phloem fibers with a thickened cell wall located on different sides of the stem in the area of the gravitropic curvature. The present study is the first work devoted to the identification of genes encoding auxin transporters in cells at different stages of development and during gravity response. In this study, the flax genes encoding the AUX1/LAX, PIN-FORMED, PIN-LIKES, and ABCB auxin transporters were identified. A comparative analysis of the expression of these genes in flax phloem fibers at different stages of development revealed increased expression of some of these genes at the stage of intrusive growth (LusLAX2 (A, B), LuxPIN1-D, LusPILS7 (C, D)), at the early stage of tertiary cell wall formation (LusAUX1 (A, D), LusABCB1 (A, B), LusABCB15-A, LusPIN1 (A, B), LusPIN4-A, and LusPIN5-A), and at the late stage of tertiary cell wall development (LusLAX3 (A, B)). It was shown that in the course of gravitropism, the expression of many genes, including those responsible for the influx of auxin in cells (LusAUX1-D), in the studied families increased. Differential expression of auxin transporter genes was revealed during gravity response in fibers located on different sides of the stem (upper (PUL) and lower (OPP)). The difference was observed due to the expression of genes, the products of which are responsible for auxin intracellular transport (LusPILS3, LusPILS7-A) and its efflux (LusABCB15-B, LusABCB19-B). It was noted that the increased expression of PIN genes and ABCB genes was more typical of fibers on the opposite side. The results obtained allow us to make an assumption about the presence of differential auxin content in the fibers of different sides of gravistimulated flax plants, which may be determined by an uneven outflow of auxin. This study gives an idea of auxin carriers in flax and lays the foundation for further studies of their functions in the development of phloem fiber and in gravity response.

In silico analysis of the expression of β-1,3-glucanase genes of flax phloem fibers Linum usitatissimum L. with gravity response

In silico analysis of the expression of β-1,3-glucanase genes of flax phloem fibers Linum usitatissimum L. with gravity response

Gravity imaging of sub-Zechstein geological structures in the UK sector of the North Sea using the gravity layer stripping method

Extensive geophysical databases, covering the UK sector of the North Sea, have been used to gravity layer strip the sedimentary layers down to the base Zechstein so that the gravity response of the Carboniferous and deeper strata can be identified and structurally interpreted. To achieve this, the average bulk density grids for each layer were derived using Gardner's functions derived from well velocity and density logs. The resulting residual gravity response of each layer and the Moho response were then removed from the Free air gravity anomaly to generate the isostatic gravity response of the crust below the base Zechstein. This gravity response was used to re-evaluate the British Geological Survey interpretation over the Mid North Sea High (MNSH) and was able to identify the same crustal structures. Using the tilt derivative method, a positive gravity anomaly was found to parallel the central fracture zone that forms a northern extension of the Dowsing fault zone. This anomaly can be traced north across the MNSH with offsets coinciding with the WSW–ENE basement lineaments. To the south, the southern North Sea basin is well defined by the stratigraphic layer depth and thickness maps as well as the residual gravity maps which identify the structures associated with the low-density Carboniferous Coal Measures.

Polarized distribution of extracellular nucleotides promotes gravity-directed polarization of development in spores of Ceratopteris richardii.

Gravity directs the polarization of Ceratopteris fern spores. This process begins with the uptake of calcium through channels at the bottom of the spore, a step necessary for the gravity response. Data showing that extracellular ATP (eATP) regulates calcium channels led to the hypothesis that extracellular nucleotides could play a role in the gravity-directed polarization of Ceratopteris spores. In animal and plant cells ATP can be released from mechanosensitive channels. This report tests the hypothesis that the polarized release of ATP from spores could be activated by gravity, preferentially along the bottom of the spore, leading to an asymmetrical accumulation of eATP. In order to carry out this test, an ATP biosensor was used to measure the [eATP] at the bottom and top of germinating spores during gravity-directed polarization. The [eATP] along the bottom of the spore averaged 7-fold higher than the concentration at the top. All treatments that disrupted eATP signaling resulted in a statistically significant decrease in the gravity response. In order to investigate the source of ATP release, spores were treated with Brefeldin A (BFA) and gadolinium trichloride (GdCl3). These treatments resulted in a significant decrease in gravity-directed polarization. An ATP biosensor was also used to measure ATP release after treatment with both BFA and GdCl3. Both of these treatments caused a significant decrease in [ATP] measured around spores. These results support the hypothesis that ATP could be released from mechanosensitive channels and secretory vesicles during the gravity-directed polarization of Ceratopteris spores.

How thick is the Strathbogie Complex?

The Strathbogie Complex is a large granitic body in north central Victoria. Previous detailed mapping of part of its western and southern boundary suggested that the body was relatively thin, probably less than 1 km. However, forward modelling its gravity response suggests the complex is thicker, perhaps more than 6 km in its deepest parts. The only way the measured gravity response could be modelled to fit a maximum thickness of 1.5 km is with an unrealistically low density. While not definitive, the modelling provides a warning that, where available, even excellent surface mapping should be combined with other data to obtain the most realistic subsurface geometries.

Transcriptome and hormone metabolome reveal the mechanism of stem bending in water lily (Nymphaea tetragona) cut-flowers.

Water lilies are popular ornamental cut-flowers with significant economic and cultural value. However, stem bending affects the preservation of cut-flowers during their vase life. To gain further insights into the molecular mechanisms of stem bending, transcriptome profiling, hormone measurement, and morphological analysis were performed using the stems of the 'Blue Bird' water lily. Transcriptome analysis revealed that 607 differentially expressed genes (DEGs) were associated with the dorsal and ventral stems of the water lily, of which 247 were up-regulated and 360 were down-regulated. Significant differences in genes associated with plant hormones, calcium ions, glucose metabolism, and photosynthesis pathways genes involved in the dorsal and ventral areas of the curved stem. In particular, DEGs were associated with the hormone synthesis, gravity response, starch granules, Ca2+ ions, and photosynthesis. The results of qRT-PCR were consistent with that of the transcriptome sequence analysis. A total of 12 hormones were detected, of which abscisic acid, indole-3-carboxaldehyde, indole-3-carboxaldehyde and jasmonic acid were significantly differentially expressed in the dorsal and ventral stems, and were significantly higher in the dorsal stem than in the ventral stem. The cell morphology in the dorsal and ventral areas of the curved stem clearly changed during vase life. The direction of starch granule settlement was consistent with the bending direction of the water lily stem, as well as the direction of gravity. In conclusion, stem bending in water lily cut-flowers is regulated by multiple factors and genes. This study provides an important theoretical basis for understanding the complex regulatory mechanism of water lily stem bending.

Three‐axis borehole gravity monitoring for CO2 storage using machine learning coupled to fluid flow simulator

AbstractThe field of geophysics faces the daunting task of monitoring complex reservoir dynamics and imaging carbon dioxide storage up to several decades into the future. This presents numerous challenges, including sensitivity to parameter changes, resolution of obtained results and the cost of long‐term deployment. To effectively store CO2 subsurface, it is necessary to monitor and account for the injected CO2. The gravity method provides several advantages for CO2 monitoring, as changes in fluid saturation correspond directly and uniquely to observed density changes. Three‐axis borehole gravity has demonstrated significant promise as a next‐generation tool for reliably monitoring reservoir dynamics across a range of depths and sizes. However, the gravity inverse problem is highly ill‐posed, necessitating regularization that incorporates prior knowledge. To address this issue, we propose using a feed‐forward neural network, a machine learning method, to invert time‐lapse three‐axis borehole gravity data and monitor CO2 movement within a reservoir. By training the neural network on models that analyse changes in density and corresponding gravity responses resulting from perturbations made to the reservoir model, we can create scenarios that train the algorithm to identify unexpected CO2 migration in addition to the normal movement of CO2. Our method is demonstrated using reservoir models for the Johansen formation in offshore Norway. We convert reservoir saturation models into density changes and generate their corresponding three‐axis gravity data in a set of boreholes. Our results show that the developed machine learning inversion algorithm has high reliability and resolution for imaging density change associated with CO2 plumes, as demonstrated in the Johansen reservoir models utilized by the simulator. We also investigate machine learning inversion using regularization parameters and show that it is robust, with a strong tolerance for higher levels of noise. Our study demonstrates that the developed machine learning algorithm is a powerful tool for inverting three‐axis borehole gravity data and monitoring the migration and long‐term storage of injected CO2.

Analysis of aquifers zones using aeromagnetic and satellite gravimetric data in Grijalva and Usumacinta basins, Mexico

The purpose of this study is to characterize the magnetic and gravity responses of the subsurface in the Grijalva and Usumacinta Basins of southeastern Mexico, to identify and define areas of rock units with aquifer potential. For this purpose, aeromagnetic and gravimetric satellite data were processed to delimit the geological features of greatest interest. The results show that the central-northern part of the study area corresponds to the zone with the greatest aquifer potential and coincides with the areas of greatest sedimentary thickness and where groundwater concessions are concentrated. The gradients between the magnetic and gravity responses help to identify the structural framework, including faults, fractures, edges, and geological contacts, and to infer the regions with aquifer potential. Among the transforms or filters used, the Tilt Derivative (TDR) exhibits the linear trends associated with the structural framework of hydrological interest. The work delimited permeable rock units present in the study area; however, it is important to continue with other studies focused on direct exploration and research techniques such as geological, lithological, and hydrogeological mapping, as an additional method of validating results gotten. The study aims to contribute to decision-making and research on geohydrological issues, land use planning, and related public policies.

Multi-Scale Potential Field Data Integration Using Fuzzy C-Means Clustering for Automated Geological Mapping of North Singhbhum Mobile Belt, Eastern Indian Craton

Fuzzy C-Means (FCM) clustering is an unsupervised machine learning algorithm that helps to integrate multiple geophysical datasets and provides automated objective-oriented information. This study analyzed ground-based Bouguer gravity and aeromagnetic datasets using the FCM clustering algorithm to classify lithological units in the western part of the North Singhbhum Mobile Belt, a mineralized belt in the Eastern Indian Craton. The potential field signatures of clusters obtained using FCM correlate remarkably well with the existing surface geology on a broad scale. The cluster associated with the highest gravity signatures corresponds to the metabasic rocks, and the cluster with the highest magnetic response represents the mica schist rocks. The cluster characterized by the lowest gravity and magnetic responses reflects the granite gneiss rocks. However, few geological formations are represented by two or more clusters, probably due to the close association of similar rock types. The fuzzy membership scores for most of the data points in each cluster show above 0.8, indicating a consistent relationship between geophysical signatures and the existing lithological units. Further, the study reveals that integrating multi-scale geophysical data helps to disclose bedrock information and litho-units under the sediment cover.

Feasibility of 4D Gravity Monitoring in Deep-Water Turbidites Reservoirs

We present a seafloor 4D gravity feasibility analysis for monitoring deep-water hydrocarbon reservoirs. To perform the study, we have simulated the gravity effect due to different density and pore pressure distributions derived from a realistic model of a turbiditic oil field in Campos Basin, offshore Brazil. These reservoirs are analogs of several other passive-margin turbiditic systems located around the world. We considered four reservoir scenarios including and not including seafloor subsidence. Our results indicate that the gravity responses are higher than the feasible value of 3 μGal 12 years following the base survey. The area of maximum gravity anomaly corresponds to where we suppose hydrocarbon extraction occurs. A maximum seafloor subsidence of 0.6 cm was estimated, resulting in no detectable gravity effects. Our results endorse the 4D seafloor gravity acquisition as a beneficial tool for monitoring deep-water passive-margin turbiditic reservoirs.