RESUMEN

To investigate the differences on morphological growth patterns of statolith of Todarodes pacificus in the East China Sea during La Niña and normal years, we analyzed the samples of T. pacificus collected in the East China Sea by Chinese light purse seine fishery fleets from February to April in 2020 (a normal year) and 2021 (a La Niña year). The results showed that total statolith length (TSL), lateral dome length (LDL), wing length (WL), and maximum width (MW) could be used as characterization parameters to representing the morphological growth of statolith. The characterization parameters of statolith in T. pacificus differed significantly between different climate years and between different genders. The values of those characterization parameters of statolith were greater in normal year than those in La Niña year, which in both years were larger in females, except for TSL in males in La Niña year. The statolith growth of males were faster than that of females in different climate years. TSL, LDL, and WL increased faster in normal year, while MW increased faster in La Niña year. The relative size of statolith gradually slowed down with the growth of individuals.

Asunto(s)

Océanos y Mares , China , Animales , Masculino , Femenino , Clima

RESUMEN

Alternative reproductive tactics (ARTs) are discontinuous phenotypes associated with reproduction, observed in males of many species. Typically, large males adopt a tactic of competing with rivals for mating, while small males adopt a tactic of stealing fertilization opportunities from the large males. The 'birth date hypothesis', proposing that the date of birth influences the determination of each male's reproductive tactic, has been tested only in teleost fish to date. Here, the birth date hypothesis was tested in ARTs of Japanese spear squid Heterololigo bleekeri (consort/sneaker) by analysing statolith growth increments. The birth date significantly differed between consorts (early-hatched) and sneakers (late-hatched). However, no differences were detected in growth history up to 100 days from hatching. Most immature males caught during the reproductive season were larger than sneakers, and their hatch date was similar to that of consorts, suggesting that these immature males had already been following a life-history pathway as a consort. These results indicate that ARTs of H. bleekeri are determined based on their hatch date in early life. This study firstly suggests that the birth date hypothesis applies to aquatic invertebrates, suggesting that the mechanism by which birth date determines the individual phenotype is a phenomenon more common than previously believed.

Asunto(s)

Decapodiformes , Reproducción , Conducta Sexual Animal , Animales , Masculino , Decapodiformes/fisiología , Femenino

RESUMEN

Gravity controls directional growth of plants, and the classical starch-statolith hypothesis proposed more than a century ago postulates that amyloplast sedimentation in specialized cells initiates gravity sensing, but the molecular mechanism remains uncharacterized. The LAZY proteins are known as key regulators of gravitropism, and lazy mutants show striking gravitropic defects. Here, we report that gravistimulation by reorientation triggers mitogen-activated protein kinase (MAPK) signaling-mediated phosphorylation of Arabidopsis LAZY proteins basally polarized in root columella cells. Phosphorylation of LAZY increases its interaction with several translocons at the outer envelope membrane of chloroplasts (TOC) proteins on the surface of amyloplasts, facilitating enrichment of LAZY proteins on amyloplasts. Amyloplast sedimentation subsequently guides LAZY to relocate to the new lower side of the plasma membrane in columella cells, where LAZY induces asymmetrical auxin distribution and root differential growth. Together, this study provides a molecular interpretation for the starch-statolith hypothesis: the organelle-movement-triggered molecular polarity formation.

Asunto(s)

Proteínas de Arabidopsis , Arabidopsis , Plastidios , Arabidopsis/fisiología , Proteínas de Arabidopsis/metabolismo , Sensación de Gravedad , Raíces de Plantas/metabolismo , Plastidios/metabolismo , Almidón/metabolismo , Proteínas de la Membrana/metabolismo

RESUMEN

Sthenoteuthis oualaniensis (Lesson, 1830) is a pelagic species with a complex population structure and wide migration range. The trace elements in statoliths are effective indicators for reconstructing the life history of an individual. In this study, the trace elements in statoliths were determined via laser ablation inductively coupled plasma mass spectrometry, and a multiple regression tree (MRT) model was used to trace the migration of S. oualaniensis and identify its potential habitats in the South China Sea. Na, Mg, Fe, Sr, and Ba were the effective trace elements, with significant differences found among stocks (p < 0.05). The MRT was divided into five clusters representing five life history stages. The Mg:Ca and Sr:Ca ratios decreased initially and increased thereafter, and the Mg:Ca, Sr:Ca, and Ba:Ca ratios differed significantly among the stages of the life history in each stock (p < 0.05). The hatching water temperatures for the winter and summer-autumn spawning populations were 28.05-28.88 °C (temperature at 25 m) and 27.15-27.92 °C (temperature at 25 m). The winter stock hatched in the southern South China Sea, and the larvae then migrated northwest during the summer monsoon. The summer-autumn stocks hatched in the northern South China Sea, and the larvae migrated southward under the mesoscale closed anticyclonic circulation in the northern South China Sea. These results provide insight into the migration of S. oualaniensis in the South China Sea.

RESUMEN

Statolith is one of the most important hard tissues to study the age, growth, population structure and life history of cephalopods. In order to stuty statolith microstructure and growth characteristics of Sthenoeuthis oualaniensis in the northwest Indian Ocean, 1009 samples were collected by Chinese light falling-net fishery fleets during investigation and production in the northwest Indian Ocean from February to May of 2019. Total statolith length (TSL), lateral dome length (LDL), wing length (WL) and maximum width (MW) were taken as the indicators of morphological feature of the statolith, combined with the age data, the statolith microstructure and growth characteristics of S. oualaniensis were studied. The results showed that the statolith microstructure could be divided into postnuclear zone, dark zone and peripheral zone according to the width of growth increment. The analysis of covariance showed that there was no growth difference of TSL, LDL, WL and MW between different sexes. The relationships between TSL, WL, MW and age were best described by the power functions, while the relationship between LDL and age was best described by the linear function. In general, with the increase of age, the instantaneous relative growth rate and absolute growth rate of TSL, WL, LDL and MW decreased, and 140-180 d may be the age of sexual maturity for this squid.

Asunto(s)

Decapodiformes , Animales , Océano Índico

RESUMEN

Micro-computed tomography (micro-CT) is a high-resolution 3D-imaging technique which is now increasingly applied in biological studies focusing on taxonomy and functional morphology. The creation of virtual representations of specimens can increase availability of otherwise underexploited and inaccessible samples. The 3D model dataset can be also further processed through volume rendering and morphometric analysis. The success of micro-CT as a visualisation technique depends on several methodological manipulations, including the use of contrast enhancing staining agents, filters, scanning mediums, containers, exposure time and frame averaging. The aim of this study was to standardise a series of micro-CT scanning and 3D analysis protocols for a marine gastropod species, Hexaplextrunculus. The analytical protocols have followed all the developmental stages of this gastropod, from egg capsules and embryos to juveniles and adults.

RESUMEN

Roots typically grow downward into the soil where they anchor the plant and take up water and nutrients necessary for plant growth and development. While the primary roots usually grow vertically downward, laterals often follow a gravity set point angle that allows them to explore the surrounding environment. These responses can be modified by developmental and environmental cues. This review discusses the molecular mechanisms that govern root gravitropism in flowering plant roots. In this system, the primary site of gravity sensing within the root cap is physically separated from the site of curvature response at the elongation zone. Gravity sensing involves the sedimentation of starch-filled plastids (statoliths) within the columella cells of the root cap (the statocytes), which triggers a relocalization of plasma membrane-associated PIN auxin efflux facilitators to the lower side of the cell. This process is associated with the recruitment of RLD regulators of vesicular trafficking to the lower membrane by LAZY proteins. PIN relocalization leads to the formation of a lateral gradient of auxin across the root cap. Upon transmission to the elongation zone, this auxin gradient triggers a downward curvature. We review the molecular mechanisms that control this process in primary roots and discuss recent insights into the regulation of oblique growth in lateral roots and its impact on root-system architecture, soil exploration and plant adaptation to stressful environments.

RESUMEN

Plants orientate their growth either towards (in roots) or away from (in shoots) the Earth's gravitational field. While we are now starting to understand the molecular architecture of these gravity response pathways, the gravity receptor remains elusive. This perspective looks at the biology of statoliths and suggests it is conceivable that their immediate environment may be tuned to modulate the strength of the gravity response. It then suggests how mutant screens could use this hypothesis to identify the gravity receptor.

RESUMEN

Root gravitropism is one of the most important processes allowing plant adaptation to the land environment. Auxin plays a central role in mediating root gravitropism, but how auxin contributes to gravitational perception and the subsequent response are still unclear. Here, we showed that the local auxin maximum/gradient within the root apex, which is generated by the PIN directional auxin transporters, regulates the expression of three key starch granule synthesis genes, SS4, PGM and ADG1, which in turn influence the accumulation of starch granules that serve as a statolith perceiving gravity. Moreover, using the cvxIAA-ccvTIR1 system, we also showed that TIR1-mediated auxin signaling is required for starch granule formation and gravitropic response within root tips. In addition, axr3 mutants showed reduced auxin-mediated starch granule accumulation and disruption of gravitropism within the root apex. Our results indicate that auxin-mediated statolith production relies on the TIR1/AFB-AXR3-mediated auxin signaling pathway. In summary, we propose a dual role for auxin in gravitropism: the regulation of both gravity perception and response.

Asunto(s)

Arabidopsis/fisiología , Gravitropismo/fisiología , Ácidos Indolacéticos/farmacología , Raíces de Plantas/crecimiento & desarrollo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Transporte Biológico , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , Quinurenina/farmacología , Almidón/genética , Almidón/metabolismo , Almidón Sintasa/genética , Almidón Sintasa/metabolismo

RESUMEN

Tropisms are directed growth-mediated plant movements which allow plants to respond to their environment. Gravitropism is the ability of plants to perceive and respond to the gravity vector and orient themselves accordingly. The gravitropic pathway can be divided into three main components: perception, biochemical signaling, and differential growth. Perception of the gravity signal occurs through the movement/sedimentation of starch-filled plastids (termed statoliths) in gravity sensing cells. Once perceived, proteins interact with the settling statoliths to set a cascade of plant hormones to the elongation zones in the roots or shoots. Plant growth regulators that play a role in gravitropism include auxin, ethylene, gibberellic acid, jasmonic acid, among others. Differential growth on opposing sides of the root or shoot allow for the plant to grow relative to the direction of the perceived gravity vector. In this review, we detail how plants perceive gravity and respond biochemically in response to gravity as well as synthesize the recent literature on this important topic in plant biology. Keywords: auxin, gravitropism, gravity perception, plant growth regulators, space biology, statolith.

Asunto(s)

Gravitropismo/genética , Desarrollo de la Planta/genética , Reguladores del Crecimiento de las Plantas/genética , Plantas

RESUMEN

Sthenoteuthis oualaniensis is the most important cephalopods fishery resource of the South China Sea, which supported the falling-net fishery of Guangdong, Guangxi and Hainan Provinces of China. Understanding the fisheries biology is essential for sustainable exploitation and management of this squid. Statolith is one of the most important hard tissues of cephalopods which were widely used in the research of fisheries biology and ecology. Elements of 20 statoliths of S. oualaniensis collected in the Xisha islands waters of South China Sea during May to August by the falling-net fishery of 2017 were analyzed with Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) for different sexes, different hatching groups, and history stages. The results showed that the statolith of the S. oualaniensis contained 55 elements, with calcium (Ca), strontium (Sr), sodium (Na), phosphorus (P), silicon (Si),magnesium (Mg), potassium (K), iron (Fe), barium (Ba) and boron (B) being the top ten abundant elements. The analysis of variance (ANOVA) showed that there was no significant difference in all element distributions between sexes for the most abundant ten elements. Significant differences existed in the contents of Si, Sr, Mg, Na and K but no significant difference was found in the contents of Ca, P, B, Fe and B between different hatching groups. There were significant differences in the contents of Sr, Na, P, K, Si, Mg, B and Ba, but no significant difference in the contents of Ca and Fe in the statoliths among different growth zones. Our results suggested that Sr, Na, K and Mg were probably the best four elements for life history reconstruction and examining population structure of the S. oualaniensis.

Asunto(s)

Decapodiformes , Animales , China , Islas , Magnesio

RESUMEN

Statoliths are nonskeletal calcified structures included in most invertebrates' gravireceptors. They have been identified and characterized in several gastropod and cephalopod molluscs and have proved to be very useful for age estimation, growth studies, and connectivity analysis, among other applications. Beyond the scarce available records on their occurrence in Class Bivalvia, statoliths are yet to be documented in the grooved carpet shell, Ruditapes decussatus, a species of high ecological and commercial value. An easy method for the extraction and processing of R. decussatus statoliths is described herein. The statolith growth was followed from the initial shell length (SL) of 2.5-3.5 mm (seed commercial size T1.5) for a period of 6 months in a nursery facility located in the Ria de Aveiro (an estuarine system in NW Portugal). The relationship between statolith diameter (StD) and SL follows the function StD=14.305 SL0.254 (N=173; r=0.855, p<0.001). All statoliths observed showed similar morphostructure and general chemistry: hard, translucent spheres of crystalline calcium oxalate (whewellite), with a central nucleus delimited by a growth check of 6.7±1.0 µm in diameter, possibly as a result of growth arrest during metamorphosis, a metamorphic ring, as described for their gastropod counterparts. Subsequent studies should validate this and will involve a search for the occurrence of additional checks that may potentially be present in older specimens and if they are, would open a new range of most promising applications for bivalve statoliths.

Asunto(s)

Bivalvos/fisiología , Membrana Otolítica/anatomía & histología , Animales , Sensación de Gravedad , Membrana Otolítica/crecimiento & desarrollo , Portugal

RESUMEN

Land plants perceive gravity and respond to it in an organ-specific way; shoots typically direct growth upwards, roots typically downwards. Historically, at least with respect to maize plants, this phenomenon is attributed to three sequential processes, namely graviperception, the transduction of the perceived signal, and the graviresponse, resulting in a typical (re)positioning of the organ or entire plant body relative to the gravivector. For decades, sedimentation of starch-containing plastids within the cells of special tissues has been regarded as the primary and initiating process fundamental for gravitropic growth (starch-statolith hypothesis). Based on Popper's falsification principle, uncompromising experiments were executed. The results indicate that the model of graviperception based on amyloplast sedimentation does not apply to maize seedlings.

Asunto(s)

Sensación de Gravedad/fisiología , Plastidios/metabolismo , Zea mays/fisiología , Germinación , Gravitropismo , Procesamiento de Imagen Asistido por Computador , Raíces de Plantas/fisiología , Plantones/fisiología

RESUMEN

Many medical doctors consider vertigo and dizziness as the major, almost obligatory complaints in patients with vestibular disorders. In this chapter, we will explain that vestibular disorders result in much more diverse and complex complaints. Many of these other complaints are unfortunately often misinterpreted and incorrectly classified as psychogenic. When we really understand the function of the vestibular system, it becomes quite obvious why patients with vestibular disorders complain about a loss of visual acuity, imbalance, fear of falling, cognitive and attentional problems, fatigue that persists even when the vertigo attacks and dizziness decreases or even disappears. Another interesting new aspect in this chapter is that we explain why the function of the otolith system is so important, and that it is a mistake to focus on the function of the semicircular canals only, especially when we want to understand why some patients seem to suffer more than others from the loss of canal function as objectified by reduced caloric responses.

Asunto(s)

Vías Auditivas/anatomía & histología , Vías Auditivas/fisiología , Fenómenos Físicos , Enfermedades Vestibulares/patología , Enfermedades Vestibulares/fisiopatología , Animales , Percepción Auditiva/fisiología , Humanos

RESUMEN

Gastropod statoliths are spherical biocarbonates formed during their lifespan. The stability and homogeneity of these structures' mineral matrix was characterised along their radiuses, using Nassarius reticulatus as a model. Generally, they were proved to be bimineralic. Two of the three CaCO3 crystalline polymorphs occurring in biocarbonates - aragonite and calcite - coexist along statolith radiuses, aragonite being unequivocally the most abundant phase. The presence of a diffuse organic matrix was also perceived by the detection of a weak Raman band between 2800 and 3000 cm(-1) consistently observed along radiuses. Beyond the apparent stability and homogeneity, different crystalline orientations were disclosed by Raman spectroscopy. A change in the intensity pattern of the features related to the lattice and bending modes of aragonite between different radiuses give new insights for a possible spherulitic-like growth of these structures. As expected from the relative homogeneity of both mineral and organic signals, there was no pattern on the distribution of Ca, O, Na and S along radiuses. However, a higher concentration of Sr occurs in growth rings (known as winter tags), corroborating the already described negative correlation between the concentration of this element in statoliths and temperature. Despite the apparent stability and homogeneity of the matrix during its lifespan, the periodic distribution of Sr potentially influences a dissimilar incorporation of trace elements in increments and growth rings. Since gastropod statolith elemental fingerprinting was recently suggested as a new tool to monitor marine environmental changes, the pressing need for further studies on the incorporation of traces in these structures is highlighted.

Asunto(s)

Bicarbonatos/análisis , Carbonato de Calcio/análisis , Membrana Otolítica/química , Membrana Otolítica/ultraestructura , Animales , Microanálisis por Sonda Electrónica , Gastrópodos , Espectrometría Raman , Estroncio/análisis , Temperatura , Difracción de Rayos X

RESUMEN

Mechanosensitive (MS) channels are expressed in a variety of cells. The molecular and biophysical mechanism involved in the regulation of MS channel activities is a central interest in basic biology. MS channels are thought to play crucial roles in gravity sensing in plant cells. To date, two mechanisms have been proposed for MS channel activation. One is that tension development in the lipid bilayer directly activates MS channels. The second mechanism proposes that the cytoskeleton is involved in the channel activation, because MS channel activities are modulated by pharmacological treatments that affect the cytoskeleton. We tested whether tension in the cytoskeleton activates MS channels. Mammalian endothelial cells were microinjected with phalloidin-conjugated beads, which bound to stress fibres, and a traction force to the actin cytoskeleton was applied by dragging the beads with optical tweezers. MS channels were activated when the force was applied, demonstrating that a sub-pN force to the actin filaments activates a single MS channel. Plants may use a similar molecular mechanism in gravity sensing, since the cytoplasmic Ca(2+) concentration increase induced by changes in the gravity vector was attenuated by potential MS channel inhibitors, and by actin-disrupting drugs. These results support the idea that the tension increase in actin filaments by gravity-dependent sedimentation of amyloplasts activates MS Ca(2+) -permeable channels, which can be the molecular mechanism of a Ca(2+) concentration increase through gravistimulation. We review recent progress in the study of tension sensing by actin filaments and MS channels using advanced biophysical methods, and discuss their possible roles in gravisensing.

Asunto(s)

Actinas/metabolismo , Sensación de Gravedad , Canales Iónicos/metabolismo , Mecanotransducción Celular , Plantas/metabolismo , Fibras de Estrés/metabolismo , Estrés Fisiológico

RESUMEN

Increasing ocean temperatures and strengthening boundary currents have caused the poleward migration of many marine species. Cubozoan jellyfish known to cause Irukandji syndrome have historically been confined to tropical waters but may be expanding into subtropical regions. Here, we examine the interactive effects of warming and acidification on the population dynamics of polyps of an Irukandji jellyfish, Alatina nr mordens, and the formation of statoliths in newly metamorphosed medusae, to determine if this jellyfish could tolerate future conditions predicted for southeast Queensland (SEQ), Australia. Two experiments, examining the orthogonal factors of temperature and pH, were undertaken. Experiment 1 mimicked the current, ca. 2050 and ca. 2100 summer temperature and pH conditions predicted for SEQ using A1F1 scenarios (temperature: 25, 27, 29 °C; pH: 7.9, 7.8, 7.6) and Experiment 2 mimicked current and future winter conditions (18 and 22 °C, pH 7.9, 7.8, 7.6). All polyps in Experiment 1 survived and budded. Fewer polyps budded in the lower pH treatments; however, patterns varied slightly among temperature treatments. Statoliths at pH 7.6 were 24% narrower than those at pH 7.8 and 7.9. Most polyps survived the winter conditions mimicked by Experiment 2 but only polyps in the 22 °C, pH 7.9 treatment increased significantly. The current absence of A. nr mordens medusae in SEQ, despite the polyps' ability to tolerate the current temperature and pH conditions, suggests that ecological, rather than abiotic factors currently limit their distribution. Observations that budding was lower under low pH treatments suggest that rates of asexual reproduction will likely be much slower in the future. We consider that A. nr mordens polyps are likely to tolerate future conditions but are unlikely to thrive in the long term. However, if polyps can overcome potential ecological boundaries and acidification proceeds slowly A. nr mordens could expand polewards in the short term.

Asunto(s)

Cambio Climático , Cubomedusas/fisiología , Animales , Concentración de Iones de Hidrógeno , Dinámica Poblacional , Queensland , Reproducción , Temperatura

RESUMEN

The starch-statolith hypothesis proposes that starch-filled amyloplasts act as statoliths in plant gravisensing, moving in response to the gravity vector and signaling its direction. However, recent studies suggest that amyloplasts show continuous, complex movements in Arabidopsis shoots, contradicting the idea of a so-called 'static' or 'settled' statolith. Here, we show that amyloplast movement underlies shoot gravisensing by using a custom-designed centrifuge microscope in combination with analysis of gravitropic mutants. The centrifuge microscope revealed that sedimentary movements of amyloplasts under hypergravity conditions are linearly correlated with gravitropic curvature in wild-type stems. We next analyzed the hypergravity response in the shoot gravitropism 2 (sgr2) mutant, which exhibits neither a shoot gravitropic response nor amyloplast sedimentation at 1 g. sgr2 mutants were able to sense and respond to gravity under 30 g conditions, during which the amyloplasts sedimented. These findings are consistent with amyloplast redistribution resulting from gravity-driven movements triggering shoot gravisensing. To further support this idea, we examined two additional gravitropic mutants, phosphoglucomutase (pgm) and sgr9, which show abnormal amyloplast distribution and reduced gravitropism at 1 g. We found that the correlation between hypergravity-induced amyloplast sedimentation and gravitropic curvature of these mutants was identical to that of wild-type plants. These observations suggest that Arabidopsis shoots have a gravisensing mechanism that linearly converts the number of amyloplasts that settle to the 'bottom' of the cell into gravitropic signals. Further, the restoration of the gravitropic response by hypergravity in the gravitropic mutants that we tested indicates that these lines probably have a functional gravisensing mechanism that is not triggered at 1 g.

Asunto(s)

Proteínas de Arabidopsis/química , Arabidopsis/fisiología , Gravitropismo , Fosfoglucomutasa/química , Fosfolipasas/química , Brotes de la Planta/química , Plastidios/química , Arabidopsis/química , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/fisiología , Centrifugación , Gravitropismo/genética , Hipergravedad , Microscopía de Polarización , Mutación , Fosfoglucomutasa/genética , Fosfoglucomutasa/fisiología , Fosfolipasas/genética , Fosfolipasas/fisiología , Brotes de la Planta/genética , Brotes de la Planta/fisiología , Plastidios/genética , Plastidios/fisiología , Dominios RING Finger/genética , Dominios RING Finger/fisiología , Ubiquitina-Proteína Ligasas/química , Ubiquitina-Proteína Ligasas/genética , Ubiquitina-Proteína Ligasas/fisiología

RESUMEN

Future space missions and implementation of permanent bases on Moon and Mars will greatly depend on the availability of ambient air and sustainable food supply. Therefore, understanding the effects of altered gravity conditions on plant metabolism and growth is vital for space missions and extra-terrestrial human existence. In this mini-review we summarize how plant cells are thought to perceive changes in magnitude and orientation of the gravity vector. The particular advantages of several single-celled model systems for gravity research are explored and an overview over recent advancements and potential use of these systems is provided.