Symmetry

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24 pages, 1513 KiB

Open AccessArticle

Dynamical Complexity of Modified Leslie–Gower Predator–Prey Model Incorporating Double Allee Effect and Fear Effect

by Manoj Kumar Singh, Arushi Sharma and Luis M. Sánchez-Ruiz

Symmetry 2024, 16(11), 1552; https://doi.org/10.3390/sym16111552 - 19 Nov 2024

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Abstract

This contribution concerns studying a realistic predator–prey interaction, which was achieved by virtue of formulating a modified Leslie–Gower predator–prey model under the influence of the double Allee effect and fear effect in the prey species. The initial theoretical work sheds light on the [...] Read more.

This contribution concerns studying a realistic predator–prey interaction, which was achieved by virtue of formulating a modified Leslie–Gower predator–prey model under the influence of the double Allee effect and fear effect in the prey species. The initial theoretical work sheds light on the relevant properties of the solution, presence, and local stability of the equilibria. Both analytic and numerical approaches were used to address the emergence of diverse bifurcations, like saddle-node, Hopf, and Bogdanov–Takens bifurcations. It is noteworthy that while making the assumption that the characteristic equation of the Jacobian matrix J has a pair of imaginary roots

C (ρ) \pm ι D (ρ)

, it is sufficient to consider only

C (ρ) + ι D (ρ)

due to symmetry. The impact of the fear effect on the proposed model is discussed. Numerical simulation results are provided to back up all the theoretical analysis. From the findings, it was established that the initial condition of the population, as well as the phenomena (fear effect) introduced, played a crucial role in determining the stability of the proposed model. Full article

(This article belongs to the Special Issue Symmetry/Asymmetry in Life Sciences: Feature Papers 2024)

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15 pages, 3078 KiB

Open AccessArticle

Bilateral Correlational Behavior of Pyroglutamate Aminopeptidase I Activity in Rat Photoneuroendocrine Locations During a Standard 12:12 h Light–Dark Cycle

by Manuel Ramírez-Sánchez, Isabel Prieto, Ana Belén Segarra, Inmaculada Banegas, Magdalena Martínez-Cañamero, Germán Domínguez-Vías, Raquel Durán and Francisco Vives

Symmetry 2024, 16(11), 1539; https://doi.org/10.3390/sym16111539 - 17 Nov 2024

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Abstract

We previously described the circadian variation and bilateral distribution of pyroglutamate aminopeptidase I (pGluPI) activity levels in photoneuroendocrine locations of adult male rats during a standard 12:12 h light–dark cycle. However, the correlational analysis between such locations has not yet been studied. This [...] Read more.

We previously described the circadian variation and bilateral distribution of pyroglutamate aminopeptidase I (pGluPI) activity levels in photoneuroendocrine locations of adult male rats during a standard 12:12 h light–dark cycle. However, the correlational analysis between such locations has not yet been studied. This may provide new data about the unilateral and bilateral functional interaction between photoneuroendocrine locations under light and dark conditions. We analyzed the correlations between locations of a photoneuroendocrine circuit consisting of retina, anterior hypothalamus, superior cervical ganglion, and pineal gland, as well as other related photoneuroendocrine locations: posterior hypothalamus, anterior pituitary, posterior pituitary, occipital cortex, and serum. In particular, we analyzed the correlations between the left retina or the right retina versus the rest of the locations, as well as the correlations between the left and right sides of paired structures at the different time points selected from 12 h light and 12 h dark periods. Also, the profiles of correlational results were compared with the corresponding mean levels. The results demonstrate the complexity of asymmetrical brain behavior. The correlation profile did not always parallel the profile observed with the mean activity values. The diurnal behavior of correlations with the left or right retina differed from one location to another. Likewise, the diurnal variation of correlations between the left and right sides of the paired structures differed between them. Particularly, while most correlations between the left versus right sides of paired structures showed positive values, that of the posterior hypothalamus showed a negative value at 13 h of light period. In addition, except the posterior hypothalamus, most paired locations only correlated significantly with right retina at 07 h of the light period. The results demonstrate the dynamic complexity of brain asymmetry, which represents a challenge for understanding its functional meaning. Full article

(This article belongs to the Special Issue Symmetry/Asymmetry in Life Sciences: Feature Papers 2024)

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11 pages, 1084 KiB

Open AccessArticle

Navicular Drop Height Asymmetry as an Intrinsic Risk Factor for Lower Limb Injury in Male Recreational Athletes

by Jarosław Domaradzki

Symmetry 2024, 16(10), 1390; https://doi.org/10.3390/sym16101390 - 18 Oct 2024

Viewed by 842

Abstract

Morphological and functional asymmetry of the lower limbs is a well-recognized factor contributing to musculoskeletal injuries among athletes across different levels. However, limited research exists on evaluating foot mobility asymmetry as a potential predictor of such injuries. This study aimed to (1) assess [...] Read more.

Morphological and functional asymmetry of the lower limbs is a well-recognized factor contributing to musculoskeletal injuries among athletes across different levels. However, limited research exists on evaluating foot mobility asymmetry as a potential predictor of such injuries. This study aimed to (1) assess the frequency of foot mobility asymmetries among amateur athletes, (2) investigate the predictive value of foot mobility asymmetry (measured via navicular height drop) for injury risk, and (3) explore the relationship between foot type and injury occurrence. A cross-sectional sampling method was employed to select 45 physically active male amateur athletes (runners and team sports practitioners) from a university. Injury history was retrospectively recorded, and a modified navicular drop test was conducted to classify foot arch height. The predictive power of navicular height drop asymmetry was analyzed using ROC curves, and the relationship between foot type (neutral and defective combinations—pronated or supinated) and injury occurrence was examined using chi-square tests for independence. Multiple logistic regression was applied to calculate injury risk odds ratios across different foot type subgroups. The results revealed a significant frequency (51.1%) of participants with at least one defective foot, including 31.1% with one neutral and one defective foot and 20% with both feet defective. Navicular height drop asymmetry emerged as a valuable predictor of injuries, with a 36% asymmetry identified as the cut-off for increased injury risk (AUC = 0.832, 95% CI: 0.691–0.973, p < 0.001). A significant relationship was found between foot type and injury occurrence. Only one out of 22 participants with neutral feet (4.55%) experienced an injury, compared to 9 out of 14 (64.29%) with one neutral and one defective foot and 5 out of 9 (55.56%) with both feet defective. These differences were statistically significant (χ² = 16.24, p < 0.001, Cramer’s V = 0.60). The odds ratio for injury risk was 37.8 (p = 0.016) for those with asymmetry (one neutral and one defective foot) and 26.3 (p = 0.102) for those with both feet defective, compared to participants with both feet neutral. In clinical practice, these findings suggest that routine screenings for physically active individuals should incorporate foot mobility asymmetry assessment. However, it is essential to integrate this factor with other risk indicators. For individuals exhibiting high asymmetry, general foot defect correction programs may be beneficial, but injury prevention strategies should adopt a more comprehensive approach, focusing on overall fitness and tailored interventions for high-risk individuals. Full article

(This article belongs to the Special Issue Symmetry/Asymmetry in Life Sciences: Feature Papers 2024)

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13 pages, 1927 KiB

Open AccessArticle

An Eye Tracking Study on Symmetry and Golden Ratio in Abstract Art

by Maria Pia Lucia, Claudia Salera, Pierpaolo Zivi, Marco Iosa and Anna Pecchinenda

Symmetry 2024, 16(9), 1168; https://doi.org/10.3390/sym16091168 - 6 Sep 2024

Viewed by 928

Abstract

A visual stimulus that is divided in harmonic proportions is often judged as more pleasant than others. This is well known by artists that often used two main types of geometric harmonic patterns: symmetry and the golden ratio. Symmetry refers to the property [...] Read more.

A visual stimulus that is divided in harmonic proportions is often judged as more pleasant than others. This is well known by artists that often used two main types of geometric harmonic patterns: symmetry and the golden ratio. Symmetry refers to the property of an object to have two similar halves, whereas the golden ratio consists of dividing an object in a major and a minor part so that their proportion is the same as that between the whole object and its major part. Here we investigated looking behaviour and explicit preferences for different regularities including symmetry and golden ratio. We selected four Mark Rothko’s paintings, a famous abstract expressionism artist, characterized by two main areas depicted by different colours: one symmetric (ratio between areas: 50–50%), one in golden ratio (38–62%), one in an intermediate ratio (46–54%), and one in a ratio exceeding the golden ratio (32–68%). Thirty-six healthy participants (24.75 ± 3.71 years old) completed three tasks: observation task (OT), pleasantness task (PT), and harmony task (HT). Findings for explicit ratings of pleasantness and harmony were very similar and were not significantly correlated with patterns of looking behaviour. Eye Dwell Time mainly depended on stimuli orientation (p < 0.001), but for the harmony task also by ratio and their interaction. Our results showed that the visual scanning behaviour of abstract arts primarily depends on the orientation of internal components, whereas their proportion is more important for the pleasantness and harmony explicit judgments. Full article

(This article belongs to the Special Issue Symmetry/Asymmetry in Life Sciences: Feature Papers 2024)

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10 pages, 804 KiB

Open AccessArticle

Sex-Based Differences in Pressure Pain Thresholds of Myofascial Trigger Points in Cervical and Cranial Muscles in Tension-Type Headache: A Cross-Sectional Study

by Sofía Monti-Ballano, María Orosia Lucha-López, César Hidalgo-García, Loreto Ferrández-Laliena, Lucía Vicente-Pina, Rocío Sánchez-Rodríguez, Héctor José Tricás-Vidal and José Miguel Tricás-Moreno

Symmetry 2024, 16(8), 1087; https://doi.org/10.3390/sym16081087 - 21 Aug 2024

Viewed by 747

Abstract

Background: Tension-type headache (TTH) is the most prevalent primary headache. Pressure pain thresholds (PPTs) reflect the pressure pain sensitivity of the tissues. Women with TTH have showed greater pressure hypersensitivity in some muscles compared to men. The aim of this study was to [...] Read more.

Background: Tension-type headache (TTH) is the most prevalent primary headache. Pressure pain thresholds (PPTs) reflect the pressure pain sensitivity of the tissues. Women with TTH have showed greater pressure hypersensitivity in some muscles compared to men. The aim of this study was to compare the PPTs from myofascial trigger points in cervical and cranial muscles which might contribute to headaches between men and women with TTH. Methods: An observational and correlation cross-sectional study was performed. PPTs were evaluated bilaterally and compared between men and women in the following muscles: upper trapezius, splenius capitis and cervicis, semispinalis, rectus capitis posterior major, obliquus capitis superior and inferior, occipitofrontalis posterior and anterior, temporalis, masseter, clavicular and sternal head of sternocleidomastoid, zygomaticus major, and levator scapulae. The mean PPT was calculated as well. Results: Significant differences showing lower PPTs in women compared to men were found in the mean PPT (p = 0.000) and in all the points except in the left clavicular head of the sternocleidomastoid (p = 0.093) and in the left masseter (p = 0.069). Conclusions: Lower PPTs from myofascial trigger points in cervical and cranial muscles, which might contribute to headaches, were observed in women compared to men with TTH. The mean PPT was also lower in women than in men, suggesting the need for gender-specific approaches in the treatment of TTH. Full article

(This article belongs to the Special Issue Symmetry/Asymmetry in Life Sciences: Feature Papers 2024)

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17 pages, 943 KiB

Open AccessArticle

The Combined Additive Effect of Inter-Limb Muscle Mass Asymmetries and Body Composition Indices on Lower Limb Injuries in Physically Active Young Adults

by Jarosław Domaradzki

Symmetry 2024, 16(7), 876; https://doi.org/10.3390/sym16070876 - 10 Jul 2024

Viewed by 810

Abstract

Biological measurements that predict injury risk are crucial diagnostic tools. Yet, research on improving diagnostic accuracy in detecting accidents is insufficient. Combining multiple predictors and assessing them via ROC curves can enhance this accuracy. This study aimed to (1) evaluate the importance of [...] Read more.

Biological measurements that predict injury risk are crucial diagnostic tools. Yet, research on improving diagnostic accuracy in detecting accidents is insufficient. Combining multiple predictors and assessing them via ROC curves can enhance this accuracy. This study aimed to (1) evaluate the importance of lower limb muscle mass asymmetry and body composition (BMI and FMI) as predictors of injuries, (2) explore the role of the most effective body composition index in the relationship between muscle asymmetry and injury, and (3) assess the prognostic potential of combined predictors. Cross-sectional sampling was used to select students from a university. The sample included 237 physically active young adults (44% males). The independent variables were inter-limb muscle mass asymmetry (absolute asymmetry, AA), BMI, and FMI; the dependent variable was the number of injuries in the past year. Using zero-inflated Poisson regression, we examined the relationships, including a moderation analysis (moderated multiple ZIP regression). The mediation by body composition was tested using ZIP and logistic regression. The predictive power was assessed via ROC curves. The significance level was set at an α-value of 0.05. No significant difference in injury incidence between males and females was found (χ² = 2.12, p = 0.145), though the injury types varied. Males had more muscle strains, while females had more bone fractures (χ² = 6.02, p = 0.014). In males, the inter-limb asymmetry and FMI predicted injuries; in females, the BMI and FMI did, but not asymmetry. No moderating or mediating effects of body composition were found. In males, combined asymmetry and the FMI better predicted injuries (AUC = 0.686) than separate predictors (AA: AUC = 0.650, FMI: AUC = 0.458). For females, the FMI was the best predictor (AUC = 0.662). The most predictive factors for injuries in males were both muscle asymmetry and the FMI (as combined predictors), while in females, it was the single FMI. The hypothesis regarding the mediating role of body composition indicators was rejected, as no moderation or mediation by the FMI was detected in the relationship between absolute asymmetry (AA) and injuries. For clinical practice, the findings suggest that practitioners should incorporate assessments of both muscle asymmetry and body composition into routine screenings for physically active individuals. Identifying those with both high asymmetry and an elevated FMI can help target preventative interventions more effectively. Tailored strength training and conditioning programs aimed at reducing asymmetry and managing body composition may reduce the risk of injury, particularly in populations identified as high-risk. Full article

(This article belongs to the Special Issue Symmetry/Asymmetry in Life Sciences: Feature Papers 2024)

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11 pages, 684 KiB

Open AccessArticle

Effects of Presentation Side and Emotional Valence on Auditory Recognition in Younger and Older Adults

by Giulia Prete, Gianluca Malatesta, Anita D’Anselmo, Rocco Palumbo, Irene Ceccato, Pasquale La Malva, Adolfo Di Crosta, Nicola Mammarella, Luca Tommasi and Alberto Di Domenico

Symmetry 2024, 16(7), 835; https://doi.org/10.3390/sym16070835 - 3 Jul 2024

Viewed by 631

Abstract

(1) Background: It is well-established that older persons compared with younger persons show a bias toward positive valence (a positivity effect), together with less pronounced hemispheric asymmetries, but these topics have been scarcely explored in auditory modality. (2) Methods: We presented auditory stimuli [...] Read more.

(1) Background: It is well-established that older persons compared with younger persons show a bias toward positive valence (a positivity effect), together with less pronounced hemispheric asymmetries, but these topics have been scarcely explored in auditory modality. (2) Methods: We presented auditory stimuli with positive, neutral, or negative emotional valence dichotically to 20 younger and 20 older participants and asked them to memorize the stimuli. In a following session, stimuli were presented binaurally, and participants had to decide whether they were new or already presented in the left/right ear. (3) Results: A higher performance by younger compared with older listeners emerged, but neither the expected Right Ear Advantage nor the positivity effect was confirmed. New stimuli were correctly categorized more frequently if they had neutral valence, whereas stimuli already presented were better recognized with negative rather than neutral or positive valence, without any age difference. (4) Conclusions: These results reveal no hemispheric asymmetries and no age difference in a memory task for auditory stimuli and suggest the existence of a bias to better encode negative content, possibly due to the crucial role of negative stimuli in everyday life. Full article

(This article belongs to the Special Issue Symmetry/Asymmetry in Life Sciences: Feature Papers 2024)

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24 pages, 10985 KiB

Open AccessArticle

Phenotyping Wheat Kernel Symmetry as a Consequence of Different Agronomic Practices

by Tatiana S. Aniskina, Kirill A. Sudarikov, Nikita A. Prisazhnoy, Ishen N. Besaliev, Alexander A. Panfilov, Nelli S. Reger, Tatyana Kormilitsyna, Antonina A. Novikova, Alexander A. Gulevich, Svyatoslav V. Lebedev, Pyotr A. Vernik and Ekaterina N. Baranova

Symmetry 2024, 16(5), 548; https://doi.org/10.3390/sym16050548 - 2 May 2024

Viewed by 934

Abstract

The use of instrumental methods of analysis in the assessment of indices that record changes in symmetry in the structure of grains to evaluate the quality of durum and soft wheat grain is currently considered a search tool that will allow us to [...] Read more.

The use of instrumental methods of analysis in the assessment of indices that record changes in symmetry in the structure of grains to evaluate the quality of durum and soft wheat grain is currently considered a search tool that will allow us to obtain previously unavailable data by finding correlations associated with differences in the shape and ratio of starch granules in conditionally symmetrical and asymmetrical wheat fruits (kernels) formed in different field conditions and with different genotypes. Indicators that had previously shown their effectiveness were used to analyze the obviously complex unique material obtained as a result of growing under critically unique sowing conditions in 2022, which affected the stability of grain development and filling. For the evaluation, a typical agronomic comparative experiment was chosen, which was used to evaluate the soil tillage practices (fallow, non-moldboard loosening, and plowing) and sowing dates (early and after excessive rainfalls), which made it possible to analyze a wider range of factors influencing the studied indices. The soil tillage methods were found to affect the uniformity of kernel fullness and their symmetry, and the sowing dates did not lead to significant differences. This study presents detailed changes in the shape of the middle cut of a wheat kernel, associated with assessing the efficiency of kernel filling and the symmetrical distribution of storage substances under the influence of external and internal physical factors that affect the formation of the wheat kernel. The data obtained may be of interest to breeders and developers of predictive phenotyping programs for cereal grain and seeds of other crops, as well as plant physiologists. Full article

(This article belongs to the Special Issue Symmetry/Asymmetry in Life Sciences: Feature Papers 2024)

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24 pages, 2695 KiB

Open AccessArticle

Implicit and Explicit Preferences for Golden Ratio

by Claudia Salera, Camilla Vallebella, Marco Iosa and Anna Pecchinenda

Symmetry 2024, 16(3), 333; https://doi.org/10.3390/sym16030333 - 9 Mar 2024

Cited by 1 | Viewed by 1939

Abstract

The golden ratio, also known as Phi (ϕ ≈ 1.618034), attracted the interest of mathematicians, artists, and intellectuals for many centuries, probably from when it was discovered in human anthropometry. Even in recent times, researchers found the presence of the golden ratio in [...] Read more.

The golden ratio, also known as Phi (ϕ ≈ 1.618034), attracted the interest of mathematicians, artists, and intellectuals for many centuries, probably from when it was discovered in human anthropometry. Even in recent times, researchers found the presence of the golden ratio in Renaissance paintings and aesthetic preferences. The reasons behind the fascination with the golden ratio remain unclear, but it has been suggested that stimuli containing this proportion are often perceived as beautiful. However, evidence is conflicting, and the literature struggles to establish the existence of individual preferences for the golden ratio. To gain new insights into the nature of these preferences, one hundred participants completed an implicit association task, with either golden ratio or random stimuli presented with positive or negative words. Participants initially categorized the stimuli based on their assigned categories. Then, we assessed their explicit preferences by asking them to rate the stimuli in terms of pleasantness and by completing a line bisection task and the Ultimatum Game. The results revealed the typical effects observed in implicit association tasks, with improved response times and accuracy when golden ratio stimuli were associated with positive word categories. In contrast, explicit ratings yielded mixed results. We discuss our findings in relation to previous studies that have explored this issue, highlighting the ongoing debate surrounding preferences for the golden ratio. Full article

(This article belongs to the Special Issue Symmetry/Asymmetry in Life Sciences: Feature Papers 2024)

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Review

Jump to: Research

13 pages, 266 KiB

Open AccessReview

Motor Asymmetry in Football: Implications for Muscular Power, Balance, and Injury Prevention

by Monoem Haddad

Symmetry 2024, 16(11), 1485; https://doi.org/10.3390/sym16111485 - 7 Nov 2024

Viewed by 571

Abstract

This review explores the prevalence and impacts of muscular power and dynamic balance motor asymmetry among football players, emphasizing its impact on performance and injury risk. Motor asymmetry frequently occurs in football, largely due to the sport’s specific demands, including the frequent use [...] Read more.

This review explores the prevalence and impacts of muscular power and dynamic balance motor asymmetry among football players, emphasizing its impact on performance and injury risk. Motor asymmetry frequently occurs in football, largely due to the sport’s specific demands, including the frequent use of one leg for kicking and passing. While some motor asymmetry may lead to functional specialization and does not always hinder performance, significant imbalances are often linked to an increased risk of injuries, particularly to the lower extremities. Dynamic balance motor asymmetry is also associated with a higher risk of non-contact injuries, underscoring the importance of joint stability in preventing such injuries. However, the direct impact of balance motor asymmetry on performance metrics like sprint speed and agility is less definitive, suggesting that compensatory mechanisms or training adaptations could mitigate potential negative effects. Technological advances in assessment, such as motion capture systems and wearable devices, have enhanced the precision of asymmetry evaluations, enabling more targeted interventions. In addition, personalized training interventions, informed by real-time data from these technologies, allow for tailored rehabilitation and performance optimization, addressing asymmetry-related risks early. Despite these technological advancements, there is a significant gap in understanding how motor asymmetry affects underrepresented groups, such as female football players and youth athletes. Further research is needed to investigate motor asymmetry in these populations, particularly to assess the long-term impact on injury risk and performance. Addressing these gaps will provide valuable insights into the development of gender- and age-specific training interventions. This review recommends a multidisciplinary approach, integrating biomechanics, sports medicine, and coaching insights, to develop comprehensive strategies for managing motor asymmetry in football. Such strategies, supported by real-time monitoring and tailored interventions, will be crucial for optimizing player performance, minimizing injury risk, and improving training and rehabilitation programs tailored to the diverse needs of football players. Full article

(This article belongs to the Special Issue Symmetry/Asymmetry in Life Sciences: Feature Papers 2024)

15 pages, 2734 KiB

Open AccessReview

Comprehensive Analysis of Pelvic Asymmetries in Low Back Pain, Scoliosis, Post-Traumatic Pelvic Dysfunctions and Obstetric Changes: A Narrative Review Focused on Clinical Relevance

by Inés Cruz-Medel, Daiana Priscila Rodrigues-de-Souza and Francisco Alburquerque-Sendín

Symmetry 2024, 16(10), 1304; https://doi.org/10.3390/sym16101304 - 3 Oct 2024

Viewed by 1422

Abstract

The human pelvis is a complex structure, which participates in the biomechanical functioning of the musculoskeletal system. Although it is considered a symmetrical entity, the morphology of the pelvis is subject to different factors that alter its anatomy, function or biomechanics, such as [...] Read more.

The human pelvis is a complex structure, which participates in the biomechanical functioning of the musculoskeletal system. Although it is considered a symmetrical entity, the morphology of the pelvis is subject to different factors that alter its anatomy, function or biomechanics, such as age, bipedal locomotion, obstetric changes and sexual dimorphism. However, how these factors influence pelvic asymmetry is unknown. Some evidence suggests that this condition leads to different pathological states, such as chronic low back pain, scoliosis, post-traumatic pelvic dysfunctions and obstetric changes. Therefore, pelvic asymmetries present a significant challenge in clinical practice due to their multifactorial nature and their potential impact on quality of life. Multidisciplinary research and collaboration are essential to improve understanding and develop more effective and specific identification and treatment approaches in the presence of pelvic asymmetries. Full article

(This article belongs to the Special Issue Symmetry/Asymmetry in Life Sciences: Feature Papers 2024)

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13 pages, 1362 KiB

Open AccessReview

Hox Gene Collinearity with Pulling Physical Forces Creates a Hox Gene Clustering in Embryos of Vertebrates and Invertebrates: Complete or Split Clusters

by Spyros Papageorgiou

Symmetry 2024, 16(5), 594; https://doi.org/10.3390/sym16050594 - 10 May 2024

Viewed by 1161

Abstract

Hox gene clusters are crucial in embryogenesis. It was observed that some Hox genes are located in order along the telomeric to centromeric direction of the DNA sequence: Hox1, Hox2, Hox3…. These genes are expressed in the same order in the ontogenetic units [...] Read more.

Hox gene clusters are crucial in embryogenesis. It was observed that some Hox genes are located in order along the telomeric to centromeric direction of the DNA sequence: Hox1, Hox2, Hox3…. These genes are expressed in the same order in the ontogenetic units of the Drosophila embryo along the anterior–posterior axis. The two entities (genome and embryo) differ significantly in linear size and in-between distance. This strange phenomenon was named spatial collinearity (SP). Later, it was observed that, particularly in the vertebrates, a temporal collinearity (TC) coexists: first Hox1 is expressed, later Hox2, and later on Hox3…. According to a biophysical model (BM), pulling forces act at the anterior end of the cluster while a cluster fastening applies at the posterior end. Hox clusters are irreversibly elongated along the force direction. During evolution, the elongated Hox clusters are broken at variable lengths, thus split clusters may be created. An empirical rule was formulated, distinguishing development due to a complete Hox cluster from development due to split Hox clusters. BM can explain this empirical rule. In a spontaneous mutation, where the cluster fastening is dismantled, a weak pulling force automatically shifts the cluster inside the Hox activation domain. This cluster translocation can probably explain the absence of temporal collinearity in Drosophila. Full article

(This article belongs to the Special Issue Symmetry/Asymmetry in Life Sciences: Feature Papers 2024)

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19 pages, 6404 KiB

Open AccessFeature PaperReview

Striped Expression of Leucine-Rich Repeat Proteins Coordinates Cell Intercalation and Compartment Boundary Formation in the Early Drosophila Embryo

by Chloe A. Kuebler and Adam C. Paré

Symmetry 2023, 15(8), 1490; https://doi.org/10.3390/sym15081490 - 27 Jul 2023

Cited by 1 | Viewed by 1504

Abstract

Planar polarity is a commonly observed phenomenon in which proteins display a consistent asymmetry in their subcellular localization or activity across the plane of a tissue. During animal development, planar polarity is a fundamental mechanism for coordinating the behaviors of groups of cells [...] Read more.

Planar polarity is a commonly observed phenomenon in which proteins display a consistent asymmetry in their subcellular localization or activity across the plane of a tissue. During animal development, planar polarity is a fundamental mechanism for coordinating the behaviors of groups of cells to achieve anisotropic tissue remodeling, growth, and organization. Therefore, a primary focus of developmental biology research has been to understand the molecular mechanisms underlying planar polarity in a variety of systems to identify conserved principles of tissue organization. In the early Drosophila embryo, the germband neuroectoderm epithelium rapidly doubles in length along the anterior-posterior axis through a process known as convergent extension (CE); it also becomes subdivided into tandem tissue compartments through the formation of compartment boundaries (CBs). Both processes are dependent on the planar polarity of proteins involved in cellular tension and adhesion. The enrichment of actomyosin-based tension and adherens junction-based adhesion at specific cell-cell contacts is required for coordinated cell intercalation, which drives CE, and the creation of highly stable cell-cell contacts at CBs. Recent studies have revealed a system for rapid cellular polarization triggered by the expression of leucine-rich-repeat (LRR) cell-surface proteins in striped patterns. In particular, the non-uniform expression of Toll-2, Toll-6, Toll-8, and Tartan generates local cellular asymmetries that allow cells to distinguish between cell-cell contacts oriented parallel or perpendicular to the anterior-posterior axis. In this review, we discuss (1) the biomechanical underpinnings of CE and CB formation, (2) how the initial symmetry-breaking events of anterior-posterior patterning culminate in planar polarity, and (3) recent advances in understanding the molecular mechanisms downstream of LRR receptors that lead to planar polarized tension and junctional adhesion. Full article

(This article belongs to the Special Issue Symmetry/Asymmetry in Life Sciences: Feature Papers 2024)

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