Heterocephalus Research Articles

Extreme examples of reparative chondrogenesis: molecular mechanisms

Restoring hyaline cartilage integrity remains a significant challenge in regenerative medicine. When damaged, the defect is replaced by fibrosis connective tissue, resulting in a loss of the biomechanical properties of the cartilage. This review examines the intricate molecular mechanisms underlying reparative chondrogenesis and presents examples from a variety of animal species. It provides a comprehensive overview of the signaling pathways and cellular responses that promote cartilage repair, showcasing the regenerative abilities of fish and amphibians, including the little skate and axolotl, and surprising cases of chondrogenesis in mammals like the naked mole-rat and the Acomys mouse. Unraveling the dynamic interplay between growth factors, cytokines, and extracellular matrix components will shed light on the complex signaling pathways controlling reparative chondrogenesis. The comparative analysis presented in this review reveals both conserved and species-specific molecular pathways involved in cartilage regeneration. This provides valuable information for translational studies. By uncovering the genetic and epigenetic determinants governing extreme examples of reparative chondrogenesis, this review provides a comprehensive framework for developing therapeutic strategies to improve cartilage repair in humans.

Robust assembly of electron transfer chain in the brain of Naked Mole-Rat during aging

Naked mole-rats (NMR, Heterocephalus glaber) are the longest-lived rodent species, with a maximum life span of more than 30 years. These long-lived mammals exhibit delayed aging phenotypes and resistance to age-related pathologies including neurodegeneration. Multiple regulatory pathways have been proposed for the anti-aging mechanisms in NMR including enhanced mitochondrial function and suppressed oxidative stress. In this study, we investigated the assembly of the electron transfer chain (ETC) which constitutes the structural base for the regulation of both oxidative phosphorylation and the production of reactive oxygen species (ROS), in brains from young and old NMR and C57BL/6 mice. While ETC assembly declined with aging in C57BL/6 mice, we found that NMR display a robust respiratory chain assembly at older ages in both males and females. Among them, individual complex IV and supercomplexes containing complex I and III or complex III and IV showed the most pronounced differences between two species. Our results indicate that a preserved robust assembly of ETC during aging contributes to enhanced mitochondrial oxidative phosphorylation and suppressed oxidative stress, which may contribute to the longevity and resistance to age-related pathologies in NMR.

The Fourth Annual Symposium of the Midwest Aging Consortium.

The Midwest Aging Consortium (MAC) has emerged as a critical collaborative initiative aimed at advancing our understanding of aging and developing strategies to combat the rising prevalence of age-related diseases. Founded in 2019, MAC brings together researchers from various disciplines and institutions across the Midwestern United States to foster interdisciplinary geroscience research. This report summarizes the highlights of the Fourth Annual Symposium of MAC, which was held at Iowa State University in May 2023. The symposium featured presentations on a wide array of topics, including studies on slow-aging animals, cellular senescence and senotherapeutics, the role of the immune system in aging, metabolic changes in aging, neuronal health in aging, and biomarkers for measuring the aging process. Speakers shared findings from studies involving a variety of animals, ranging from commonly used species such as mice, rats, worms, yeast, and fruit flies, to less-common ones like naked mole-rats, painted turtles, and rotifers. MAC continues to emphasize the importance of supporting emerging researchers and fostering a collaborative environment, positioning itself as a leader in aging research. This symposium not only showcased the current state of aging biology research but also highlighted the consortium's role in training the next generation of scientists dedicated to improving the healthspan and well-being of the aging population.

The reconstruction of evolutionary dynamics of processed pseudogenes indicates deep silencing of “retrobiome” in naked mole rat

Approximately half of mammalian genomes are occupied by retrotransposons, highly repetitive interspersed genetic elements expanded through the mechanism of reverse transcription. The evolution of this "retrobiome" involved a series of explosive amplifications, presumably associated with high mutation rates, interspersed with periods of silencing. A by-product of retrotransposon activity is the formation of processed pseudogenes (PPGs)-intron-less, promoter-less DNA copies of messenger RNA (mRNA). We examined the proportion of PPGs with varying degrees of deviation from their ancestor mRNAs as an indicator of the intensity of retrotranspositions at different times in the past. Our analysis revealed a high proportion of "young'' (recently acquired) PPGs in the DNA of mice and rats, indicating significant retrobiome activity during the recent evolution of these species. The ongoing process of new PPG entries in mouse germ line DNA was confirmed by identifying diversity in PPG content within the single strain of mice, C57BL/6. In contrast, the highly abundant PPGs of the naked mole rat (NMR) exhibited substantial deviation from their mRNAs, with a near-complete lack of PPGs without mutations, indicative of the silencing of the retrobiome in the most recent evolutionary past, preceded by a period of high activity. This distinctive feature of the NMR genome was confirmed through the analysis of a broad range of mammalian species. The peculiar evolutionary dynamics of PPGs in the NMR, an organism with exceptional longevity and resistance to cancer, may reflect the role played by the retrobiome in aging and cancer.

Evidence for inbreeding depression in captive Damaraland mole-rats.

Mating between closely related individuals can result in a reduction in offspring fitness, known as inbreeding depression. Here, we investigate whether breeding with close relatives affects the reproductive output of parents and the development of their offspring in Damaraland mole-rats (Fukomys damarensis), a cooperatively breeding species where females avoid mating with familiar individuals. By cross-fostering litters of pups soon after birth, we were able to form breeding pairs from full siblings that were reared apart. We compared the reproductive output of these sibling pairs and the survival and growth of their pups with that of unrelated pairs over a period of 4 years. The litter sizes and interbirth intervals of sibling pairs did not differ from those of unrelated pairs, but the growth and survival of inbred offspring were lower, showing that breeding between close relatives is associated with substantial fitness costs. This study suggests that inbreeding depression is an important driver of the extreme reproductive skew observed in social mole-rats. Studies of the costs of inbred matings are now needed in similar species, such as naked mole-rats (Heterocephalus glaber), where captive females more commonly breed with close relatives, to determine whether these costs are lower than in Damaraland mole-rats.

The curious case of the hypothalamic-pituitary-gonadal axis dysfunction in subordinate female naked mole-rats (Heterocephalus glaber): No apparent role of opioids and glucocorticoids.

The naked mole-rat (Heterocephalus glaber) is a unique model mammal in which to study socially induced inhibition of the hypothalamic-pituitary-gonadal (HPG) axis. Naked mole-rat groups exhibit a high degree of reproductive bias in which breeding is restricted to one female (the queen) and one male, with subordinate non-breeding colony members rarely, if ever, having the opportunity to reproduce due to a dysfunctional HPG axis. It is posited that aggression directed at subordinates by the queen suppresses reproduction in these subordinates, yet the underlying physiological mechanisms causing this dysfunction are unknown. This study aimed to investigate the possible factors contributing to the dysfunction of the HPG axis in subordinate female naked mole-rats with a specific focus on the role of ovarian feedback and stress-related factors such as circulating glucocorticoid and endogenous opioid peptides. The results showed that stress-related factors appear to not mediate the suppression of reproductive function in subordinate female naked mole rats. Indeed, in some cases, the activation of the stress axis may lead to reproductive activation instead of deactivation. At the same time, the role of ovarian sex steroid feedback in reproductive suppression is likely limited and not clearly delineated. This study highlights the need for detailed studies to elucidate the mechanism of reproductive suppression in this unique model mammalian species which may shed light on, and reveal novel mechanisms, in the social regulation of reproduction.

What can naked mole-rats teach us about ameliorating hypoxia-related human diseases?

Ameliorating the deleterious impact of systemic or tissue-level hypoxia or ischemia is key to preventing or treating many human diseases and pathologies. Usefully, environmental hypoxia is also a common challenge in many natural habitats; animals that are native to such hypoxic niches often exhibit strategies that enable them to thrive with limited O2 availability. Studying how such species have evolved to tolerate systemic hypoxia offers a promising avenue of discovery for novel strategies to mitigate the deleterious effects of hypoxia in human diseases and pathologies. Of particular interest are naked mole-rats, which are among the most hypoxia-tolerant mammals. Naked mole-rats that tolerate severe hypoxia in a laboratory setting are also protected against clinically relevant mimics of heart attack and stroke. The mechanisms that support this tolerance are currently being elucidated but results to date suggest that metabolic rate suppression, reprogramming of metabolic pathways, and mechanisms that defend against deleterious perturbations of cellular signaling pathways all provide layers of protection. Herein, we synthesize and discuss what is known regarding adaptations to hypoxia in the naked mole-rat cardiopulmonary system and brain, as these systems comprise both the primary means of delivering O2 to tissues and the most hypoxia-sensitive organs in mammals.

Pharmacokinetics of Injectable Meloxicam and Buprenorphine in the Naked Mole-Rat (Heterocephalus glaber).

Unique characteristics of the naked mole-rat (NMR) have made it increasingly popular as a laboratory animal model. These rodents are used to study many fields of research including longevity and aging, cancer, circadian rhythm, pain, and metabolism. Currently, the analgesic dosing regimens used in the NMR mirror those used in other rodent species. However, there is no pharmacokinetic (PK) data supporting the use of injectable analgesics in the NMR. Therefore, we conducted 2 independent PK studies to evaluate 2 commonly used analgesics in the NMR: meloxicam (2 mg/kg SC) and buprenorphine (0.1 mg/kg SC). In each study, blood was collected at 8 time points after subcutaneous injection of meloxicam or buprenorphine (0 [predose], 0.25, 0.5, 1, 2, 4, 8, and 24 h). Three NMRs were used per time point for a total of 24 animals per PK study. Plasma concentrations of meloxicam were highest between 0.5 and 1 h postinjection. Levels remained above the extrapolated dog and cat therapeutic threshold levels (390 to 911 ng/mL) for at least 24 h. Plasma concentrations of buprenorphine were highest between 0.25 and 0.5 h postinjection. Levels remained above the human therapeutic threshold (1 ng/mL) for up to 21 h. No skin reactions were seen in association with injection of either drug. In summary, these data support dosing meloxicam (2 mg/kg SC) once every 24 h and buprenorphine (0.1 mg/kg SC) once every 8 to 12 h in the NMR. Further studies should be performed to evaluate the clinical efficacy of these drugs by correlating plasma concentrations with postoperative pain assessments.

Positive effect of a diggable substrate on the behaviour of a captive naked mole rat colony

Naked mole rats (Heterocephalus galber) are eusocial mammals from East Africa. Their extraordinary social organisation is accompanied by remarkable adaptations to an underground lifestyle, extreme longevity and resistance to many diseases, making naked mole rats a highly relevant model for biological research. However, their living conditions in controlled environments do not allow them to express fundamental behaviours: digging galleries and exploring. This gap probably constitutes a bias to any behavioural or even medical study, because it represents a potential obstacle to their well-being. In this article, we tested the effects of the introduction of a diggable substrate on the behaviour of a colony of naked mole rats at the Menagerie, le Zoo du Jardin des Plantes, Paris. We measured individual exploratory latencies, the number of entries per minute and the frequency with which naked mole rats gnawed tunnels during observation trials. We found that: (i) young individuals explore more quickly, (ii) the introduction of a diggable substrate encourages exploration and digging behaviour, and (iii) could therefore be a relevant element to introduce under human care. This new environmental design could improve the welfare of naked mole rats by creating opportunities for cognitive challenges such as exploration and environmental control.

Can you dig it? The impact of a movable substrate "dig pit" on naked mole rat (Heterocephalus glaber) behavior and welfare.

Zoos are often limited by exhibit design in the opportunities they can provide animals to express natural behaviors; however, the opportunity to perform certain natural behaviors is key to supporting good animal welfare. Traditionally, in zoos, naked mole rats (Heterocephalus glaber) are housed in gunite-lined acrylic chambers that replicate the look of their tunnel systems in the wild but don't offer the opportunity for natural digging and tunnel construction behaviors. In this study, naked mole rat behavior was evaluated when providing two different presentations of movable substrate added on to the original exhibit-a tank with loose substrate and a dig pit with hard-packed clay. We recorded 299 5-min focal observations with 30-s intervals and 30 group scans to understand behavioral changes across treatments (10 days of observation per treatment). Results were analyzed using Bayesian mixed models. Digging behavior emerged in both presentations of moveable substrate. A potential indicator of negative welfare, barrier-directed behavior, decreased when the mole rats had access to the tank of loose substrate. A potential indicator of positive welfare, exploratory behavior, increased with access to the dig pit when the mole rats had the opportunity to build tunnels. Additionally, affiliative social interactions increased, and aggressive interactions decreased with access to either presentation of movable substrate. The observed changes in colony behavior demonstrate that captive naked mole rats readily exhibited the natural behaviors of digging and tunnel building when the opportunity was presented, and the habitat modification likely improved naked mole rat welfare.

Comparative time-series multi-omics analyses suggest H1.2 involvement in anoxic adaptation and cancer resistance.

The naked mole rat (NMR), Heterocephalus glaber, is known as the longest-lived rodent and is extraordinarily resistant to hypoxia and cancer. Here, both NMR embryonic fibroblasts (NEFs) and their mouse counterparts (MEFs) were subjected to anoxic conditions (0% O2, 5% CO2). A combination of comparative transcriptomics and proteomics was then employed to identify differentially expressed genes (DEGs). Notably, we observed distinct levels of histone H1.2 (encoded by HIST1H1C) accumulation between NEFs and MEFs. Subsequent mechanistic analyses showed that higher H1.2 expression in NEFs was associated with the lower expression of its inhibitor, PARP1. Additionally, we discovered that H1.2 can directly interact with HIF-1α PAS domains, thereby promoting the expression of HIF-1α through facilitating the dimerization with HIF-1β. The overexpression of H1.2 was also found to trigger autophagy and to suppress the migration of cancer cells, as well as the formation of xenograft tumors, via the NRF2/P62 signaling pathway. Moreover, an engineered H1.2 knock-in mouse model exhibited significantly extended survival in hypoxic conditions (4% O2) and showed a reduced rate of tumor formation. Collectively, our results indicate a potential mechanistic link between H1.2 and the dual phenomena of anoxic adaptation and cancer resistance.

Exposing the naked truth about how mole-rats evade cancer: In this first of a two-part series on what we can learn from unusually cancer-resistant or -susceptible animals, researchers are exploring how adaptations to their extreme environment may have given naked mole-rats potent cancer-fighting tools.

Exposing the naked truth about how mole-rats evade cancer: In this first of a two-part series on what we can learn from unusually cancer-resistant or -susceptible animals, researchers are exploring how adaptations to their extreme environment may have given naked mole-rats potent cancer-fighting tools.

Features of the CD1 gene family in rodents and the uniqueness of the immune system of naked mole-rat

Cluster of Differentiation 1 (CD1) proteins are widely expressed throughout jawed vertebrates and present lipid antigens to specific CD1-restricted T lymphocytes. CD1 molecules play an important role in immune defense with the presence or absence of particular CD1 proteins frequently associated with the functional characteristics of the immune system. Here, we show the evolution of CD1 proteins in the Rodentia family and the diversity among its members. Based on the analysis of CD1 protein-coding regions in rodent genomes and the reconstruction of protein structures, we found that Heterocephalus glaber represents a unique member of the suborder Hystricomorpha with significant changes in protein sequences and structures of the CD1 family. Multiple lines of evidence point to the absence of CD1d and CD1e and probably a dysfunctional CD1b protein in Heterocephalus glaber. In addition, the impact of CD1d loss on the CD1d/Natural killer T (NKT) cell axis in the naked mole-rat and its potential implications for immune system function are discussed in detail.

An Efficient Approach for Localizing Sensor Nodes in 2D Wireless Sensor Networks Using Whale Optimization-Based Naked Mole Rat Algorithm

Localization has emerged as an important and critical component of research in Wireless Sensor Networks (WSNs). WSN is a network of numerous sensors distributed across broad areas of the world to conduct numerous activities, including sensing the data and transferring it to various devices. Most applications, like animal tracking, object monitoring, and innumerable resources put in the interior as well as outdoor locations, need to identify the position of the occurring incident. The primary objective of localization is to identify the locality of sensor nodes installed in a network so that the location of a particular event can be traced. Different optimization approaches are observed in the work for solving the localization challenge in WSN and assigning the apt positions to undiscovered sensor nodes. This research employs the approach of localizing sensor nodes in a 2D platform utilizing an exclusive static anchor node and virtual anchors to detect dynamic target nodes by projecting these six virtual anchors hexagonally at different orientations and then optimizing the estimated target node co-ordinates employing Whale Optimization-based Naked Mole Rat Algorithm (WONMRA). Moreover, the effectiveness of a variety of optimization strategies employed for localization is compared to the WONMRA strategy concerning localization error and the number of nodes being localized, and it has been investigated that the average error in localization is 0.1999 according to WONMRA and is less than all other optimization techniques.

Use of qPCR to Evaluate Efficiency of the Bulky DNA Damage Removal in Extracts of Mammalian Cells with Different Maximum Lifespan

Proteins of nucleotide excision repair system (NER) are responsible for detecting and removing a wide range of bulky DNA damages, thereby contributing significantly to the genome stability maintenance within mammalian cells. Evaluation of NER functional status in the cells is important for identifying pathological changes in the body and assessing effectiveness of chemotherapy. The following method, described herein, has been developed for better assessment of bulky DNA damages removal in vitro, based on qPCR. Using the developed method, NER activity was compared for the extracts of the cells from two mammals with different lifespans: a long-lived naked mole-rat (Heterocephalus glaber) and a short-lived mouse (Mus musculus). Proteins of the H. glaber cell extract have been shown to be 1.5 times more effective at removing bulky damage from the model DNA substrate than the proteins of the M. musculus cell extract. These results are consistent with the experimental data previously obtained. The presented method could be applied not only in fundamental studies of DNA repair in mammalian cells, but also in clinical practice.

Hyaluronidase inhibitor delphinidin inhibits cancer metastasis

Cancer remains a formidable global health challenge, with metastasis being a key contributor to its lethality. Abundant high molecular mass hyaluronic acid, a major non-protein component of extracellular matrix, protects naked mole rats from cancer and reduces cancer incidence in mice. Hyaluronidase plays a critical role in degrading hyaluronic acid and is frequently overexpressed in metastatic cancer. Here we investigated the potential of targeting hyaluronidases to reduce metastasis. A high throughput screen identified delphinidin, a natural plant compound found in fruits and vegetables, as a potent hyaluronidase inhibitor. Delphinidin-mediated inhibition of hyaluronidase activity led to an increase in high molecular weight hyaluronic acid in cell culture and in mouse tissues, and reduced migration and invasion behavior of breast, prostate, and melanoma cancer cells. Moreover, delphinidin treatment suppressed melanoma metastasis in mice. Our study provides a proof of principle that inhibition of hyaluronidase activity suppresses cancer cell migration, invasion and metastasis. Furthermore, we identified a natural compound delphinidin as a potential anticancer therapeutic. Thus, we have identified a path for clinical translation of the cancer resistance mechanism identified in the naked mole rat.

Characterization of Naked Mole-Rat Mesenchymal Stromal Cells: Comparison with Long- and Short-Lived Mammals

Characterization of Naked Mole-Rat Mesenchymal Stromal Cells: Comparison with Long- and Short-Lived Mammals

Intestinal barrier function in the naked mole-rat: an emergent model for gastrointestinal insights.

The intestinal barrier plays a crucial role in homeostasis by both facilitating the absorption of nutrients and fluids and providing a tight shield to prevent the invasion by either pathogen or commensal microorganisms. Intestinal barrier malfunction is associated with systemic inflammation, oxidative stress, and decreased insulin sensitivity, which may lead to the dysregulation of other tissues. Therefore, a deeper understanding of physiological aspects related to an enhanced barrier function is of significant scientific and clinical relevance. The naked mole-rat has many unusual biological features, including attenuated colonic neuron sensitivity to acid and bradykinin and resistance to chemical-induced intestinal damage. However, insight into their intestinal barrier physiology is scarce. Here, we observed notable macroscopic and microscopic differences in intestinal tissue structure between naked mole-rats and mice. Moreover, naked mole-rats showed increased number of larger goblet cells and elevated mucus content. In measuring gut permeability, naked mole-rats showed reduced permeability compared with mice, measured as transepithelial electrical resistance, especially in ileum. Furthermore, intestinal ion secretion induced by serotonin, bradykinin, histamine, and capsaicin was significantly reduced in naked mole-rats compared with mice, despite the expression of receptors for all these agonists. In addition, naked mole-rats exhibited reduced prosecretory responses to the nonselective adenylate cyclase activator forskolin. Collectively, these findings indicate that naked mole-rats possess a robust and hard-to-penetrate gastrointestinal barrier that is resistant to environmental and endogenous irritants. Naked mole-rats may therefore provide valuable insights into the physiology of the intestinal barrier and set the stage for the development of innovative and effective therapies.NEW & NOTEWORTHY This is the first study to characterize the intestinal function of naked mole-rats. We found that these animals show a robust gut tissue structure, displaying thicker intestinal layers, longer villi, and larger crypts. Naked mole-rats showed more and larger goblet cells, with increased mucus content. Intestinal permeability, especially in the ileum, was substantially lower than that of mice. Finally, naked mole-rats showed reduced intestinal anion secretion in response to serotonin, bradykinin, histamine, capsaicin, and forskolin.

A hybrid swarm intelligence algorithm for region-based image fusion

This paper proposes a novel multi-hybrid algorithm named DHPN, using the best-known properties of dwarf mongoose algorithm (DMA), honey badger algorithm (HBA), prairie dog optimizer (PDO), cuckoo search (CS), grey wolf optimizer (GWO) and naked mole rat algorithm (NMRA). It follows an iterative division for extensive exploration and incorporates major parametric enhancements for improved exploitation operation. To counter the local optima problems, a stagnation phase using CS and GWO is added. Six new inertia weight operators have been analyzed to adapt algorithmic parameters, and the best combination of these parameters has been found. An analysis of the suitability of DHPN towards population variations and higher dimensions has been performed. For performance evaluation, the CEC 2005 and CEC 2019 benchmark data sets have been used. A comparison has been performed with differential evolution with active archive (JADE), self-adaptive DE (SaDE), success history based DE (SHADE), LSHADE-SPACMA, extended GWO (GWO-E), jDE100, and others. The DHPN algorithm is also used to solve the image fusion problem for four fusion quality metrics, namely, edge-based similarity index (QAB/F\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$Q^{AB/F}$$\\end{document}), sum of correlation difference (SCD), structural similarity index measure (SSIM), and artifact measure (NAB/F\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$N^{AB/F}$$\\end{document}). The average QAB/F=0.765508\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$Q^{AB/F} = 0.765508$$\\end{document}, SCD=1.63185\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$SCD = 1.63185$$\\end{document}, SSIM=0.726317\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$SSIM = 0.726317$$\\end{document}, and NAB/F=0.006617\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$N^{AB/F} = 0.006617$$\\end{document} shows the best combination of results obtained by DHPN with respect to the existing algorithms such as DCH, CBF, GTF, JSR and others. Experimental and statistical Wilcoxon’s and Friedman’s tests show that the proposed DHPN algorithm performs significantly better in comparison to the other algorithms under test.

Synthesis of Circular Antenna Arrays for Achieving Lower Side Lobe Level and Higher Directivity Using Hybrid Optimization Algorithm

Circular antenna arrays (CAAs) find extensive utility in a range of cutting-edge communication applications such as 5G networks, the Internet of Things (IoT), and advanced beamforming technologies. In the realm of antenna design, the side lobes levels (SLL) in the radiation pattern hold significant importance within communication systems. This is primarily due to its role in mitigating signal interference across the entire radiation pattern’s side lobes. In order to suppress the subsidiary lobe, achieve the required primary lobe orientation, and improve directivity, an optimization problem is used in this work. This paper introduces a method aimed at enhancing the radiation pattern of CAA by minimizing its SLL using a Hybrid Sooty Tern Naked Mole-Rat Algorithm (STNMRA). The simulation results show that the hybrid optimization method significantly reduces side lobes while maintaining reasonable directivity compared to the uniform array and other competitive metaheuristics.