Excellent Model Research Articles

Fat body-derived juvenile hormone acid methyltransferase functions to maintain iron homeostasis in Drosophila melanogaster.

Iron homeostasis is of critical importance to living organisms. Drosophila melanogaster has emerged as an excellent model to study iron homeostasis, while the regulatory mechanism of iron metabolism remains poorly understood. Herein, we accidently found that knockdown of juvenile hormone (JH) acid methyltransferase (Jhamt) specifically in the fat body, a key rate-limiting enzyme for JH synthesis, led to iron accumulation locally, resulting in serious loss and dysfunction of fat body. Jhamt knockdown-induced phenotypes were mitigated by iron deprivation, antioxidant and Ferrostatin-1, a well-known inhibitor of ferroptosis, suggesting ferroptosis was involved in Jhamt knockdown-induced defects in the fat body. Further study demonstrated that upregulation of Tsf1 and Malvolio (Mvl, homolog of mammalian DMT1), two iron importers, accounted for Jhamt knockdown-induced iron accumulation and dysfunction of the fat body. Mechanistically, Kr-h1, a key transcription factor of JH, acts downstream of Jhamt inhibiting Tsf1 and Mvl transcriptionally. In summary, the findings indicated that fat body-derived Jhamt is required for the development of Drosophila by maintaining iron homeostasis in the fat body, providing unique insight into the regulatory mechanisms of iron metabolism in Drosophila.

Soft sensor modeling based on masked convolutional transformer block deep residual shrinkage network

BackgroundData-driven soft sensor technology is currently an important means for industrial data prediction, addressing the challenge of predicting key quality variables in industrial production processes. Convolutional neural networks (CNN) are widely applied in soft sensor modeling due to their excellent nonlinear modeling and feature extraction capabilities. However, CNN also faces several issues, such as poor robustness to interference and difficulties in extracting features from complex process data. MethodsThis paper introduces a novel CNN model called the Masked Convolutional Transformer Block Deep Residual Shrinkage Network (MCTB-DRSN). Firstly, the Masked Convolutional Transformer Block (MCTB) is utilized to extract features from different positions, thereby enabling the network model to focus more on important information. Secondly, the Global Response Normalization (GRN) layer is incorporated into the Deep Residual Shrinkage Network (DRSN) module, which enhances feature competition among channels. Significant FindingsThis method can provide effective monitoring for chemical production process. Compared with the traditional soft sensor method on the debutanizer column dataset, the results show that the prediction accuracy of this model is significantly improved.

Improved whole-mount immunofluorescence protocol for consistent and robust labeling of adult Drosophila melanogaster adipose tissue.

Energy storage and endocrine functions of the Drosophila fat body make it an excellent model for elucidating mechanisms that underlie physiological and pathophysiological organismal metabolism. Combined with Drosophila's robust genetic and immunofluorescence microscopy toolkits, studies of Drosophila fat body function are ripe for cell biological analysis. Unlike the larval fat body, which is easily removed as a single, cohesive sheet of tissue, isolating intact adult fat body proves to be more challenging, thus hindering consistent immunofluorescence labeling even within a single piece of adipose tissue. Here, we describe an improved approach to handling Drosophila abdomens that ensures full access of the adult fat body to solutions generally used in immunofluorescence labeling protocols. In addition, we assess the quality of fluorescence reporter expression and antibody immunoreactivity in response to variations in fixative type, fixation incubation time, and detergent used for cellular permeabilization. Overall, we provide several recommendations for steps in a whole mount staining protocol that results in consistent and robust immunofluorescence labeling of the adult Drosophila fat body.

Insights of ecological resilience in Caatinga assemblages – landscape configuration drives Chrysomeloidea (Coleoptera) diversity in a seasonally dry tropical forest

AbstractSeasonally Dry Tropical Forests (SDTFs) have long suffered from chronic, intensive and extensive landscape transformations due to human activities, challenging biodiversity conservation in this biome. The Caatinga is the largest Neotropical SDTF, serving as an excellent model to understand how land use changes modulate ecological communities. In this study, we assessed the effects of landscape configuration and composition on the abundance and diversity of Chrysomeloidea in a region of Caatinga. We sampled beetles in 10 landscape units, in which we measured landscape configuration (patch size, edge density) and composition (landscape diversity, patch richness). Hill numbers (q0, q1, q2) were used to analyze the diversities of Chrysomeloidea. A total of 484 individuals belonging to 82 species were collected. Landscape configuration affected Chrysomeloidea assemblages with a positive correlation between edge density and Chrysomeloidea diversity. We provide a new perspective regarding the spatial distribution of Chrysomeloidea in Caatinga and conclude that landscape configuration, but not composition, directly affects Chrysomeloidea assemblages.

Deletion in RMST lncRNA impairs hypothalamic neuronal development in a human stem cell-based model of Kallmann Syndrome

Rhabdomyosarcoma 2-associated transcript (RMST) long non-coding RNA has previously been shown to cause Kallmann syndrome (KS), a rare genetic disorder characterized by congenital hypogonadotropic hypogonadism (CHH) and olfactory dysfunction. In the present study, we generated large deletions of approximately 41.55 kb in the RMST gene in human pluripotent stem cells using CRISPR/Cas9 gene editing. To evaluate the impact of RMST deletion, these cells were differentiated into hypothalamic neurons that include 10–15% neurons that express gonadotrophin-releasing hormone (GnRH). We found that deletion in RMST did not impair the neurogenesis of GnRH neurons, however, the hypothalamic neurons were electro-physiologically hyperactive and had increased calcium influx activity compared to control. Transcriptomic and epigenetic analyses showed that RMST deletion caused altered expression of key genes involved in neuronal development, ion channels, synaptic signaling and cell adhesion. The in vitro generation of these RMST-deleted GnRH neurons provides an excellent cell-based model to dissect the molecular mechanism of RMST function in Kallmann syndrome and its role in hypothalamic neuronal development.

A novel real-time model for predicting acute kidney injury in critically ill patients within 12 hours.

A major challenge in prevention and early treatment of acute kidney injury (AKI) is the lack of high-performance predictors in critically ill patients. Therefore, we innovatively constructed U-AKIpredTM for predicting AKI in critically ill patients within 12h of panel measurement. The prospective cohort study included 680 patients in the training set and 249 patients in the validation set. After performing inclusion and exclusion criteria, 417 patients were enrolled in the training set and 164 patients were enrolled in the validation set finally. AKI was diagnosed by Kidney Disease Improving Global Outcomes (KDIGO) criteria. Twelve urinary kidney injury biomarkers (mALB, IgG, TRF, α1MG, NAG, NGAL, KIM-1, L-FABP, TIMP2, IGFBP7, CAF22 and IL-18) exhibited good predictive performance for AKI within 12h in critically ill patients. U-AKIpredTM, combined with three crucial biomarkers (α1MG, L-FABP and IGFBP7) by multivariate logistic regression analysis, exhibited better predictive performance for AKI in critically ill patients within 12h than the other twelve kidney injury biomarkers. The area under the curve (AUC) of the U-AKIpredTM, as a predictor of AKI within 12h, was 0.802 (95% CI: 0.771-0.833, P<0.001) in the training set and 0.844 (95% CI: 0.792-0.896, P<0.001) in validation cohort. A nomogram based on the results of the training and validation sets of U-AKIpredTM was developed which showed optimal predictive performance for AKI. The fitting effect and prediction accuracy of U-AKIpredTM was evaluated by multiple statistical indicators. To provide a more flexible predictive tool, the dynamic nomogram (https://www.xsmartanalysis.com/model/U-AKIpredTM) was constructed using a web-calculator. Decision curve analysis (DCA) and a clinical impact curve were used to reveal that U-AKIpredTM with the three crucial biomarkers had a higher net benefit than these twelve kidney injury biomarkers respectively. The net reclassification index (NRI) and integrated discrimination index (IDI) were used to improve the significant risk reclassification of AKI compared with the 12 kidney injury biomarkers. The predictive efficiency of U-AKIpredTM was better than the NephroCheck® when testing for AKI and severe AKI. U-AKIpredTM is an excellent predictive model of AKI in critically ill patients within 12h and would assist clinicians in identifying those at high risk of AKI.

Exposure to Total Suspended Solids (TSS) Impacts Gill Structure and Function in Adult Zebrafish.

Total suspended solids (TSS) are a major contributor of anthropogenic impacts to aquatic systems. TSS exposure have been shown to affect the function of gills, but the mode of action is unclear. Zebrafish (Danio rerio) is emerging as an excellent model for mechanistic toxicology, and as there are no baseline studies on TSS effects in zebrafish gills, we tested the hypothesis that environmental concentrations of TSS damages gill structure and function in this species. Adult zebrafish were exposed to either 0, 10, 100, 500, 1000, or 2000mg/L TSS for 4 days to assess the gill morphology. The minimal concentration that affected the gill structure was further tested for the distribution of key ion transporters, including Na+/K+- ATPase (NKA) and vacuolar-type H+-ATPase (VHA), using confocal microscopy. Our results reveal that TSS concentration as low as 100mg/L alters the morphology of gills, including greater filament thickness, lamellae thickness, and epithelial lifting. This was also associated with a reduction in NKA immunoreactive (IR) cell count and intensity in the 100mg/L TSS group, while there was neither a change in the VHA-IR cell count or expression nor the transcript abundance of atp6v1a and atp1a1a4 in the gills. Markers of stress response in these animals, including levels of cortisol, glucose, lactate, and glycogen were not altered after 4 days of TSS exposure. Overall, environmentally relevant concentrations of TSS can damage the gill structure and function in zebrafish and has the potential to enhance the toxicity of contaminants acting via the gills.

Adaptive Graph Neural Network with Incremental Learning Mechanism for Knowledge Graph Reasoning

Knowledge graphs are extensively utilized in diverse fields such as search engines, recommendation systems, and dialogue systems, and knowledge graph reasoning plays an important role in the aforementioned domains. Graph neural networks demonstrate the capability to effectively capture and process the graph structure inherent in knowledge graphs, leveraging the relationships between nodes and edges to enable efficient reasoning. Current research on graph neural networks relies on predefined propagation paths. The models based on predefined propagation paths overlook the correlation between entities and query relations, limiting adaptability and scalability. In this paper, we propose an adaptive graph neural network with an incremental learning mechanism to search the adaptive propagation path in order to retain promising targets. In detail, the incremental learning mechanism is able to filter out unrelated entities in the propagation path by incorporating the node sampling technique to increase the learning efficiency of the model. In addition, the incremental learning mechanism can select semantically related entities, which promotes the capture of meaningful connections among different nodes in the knowledge graph. At the same time, we apply the parameter initialization module to accelerate the convergence and improve the robustness of the model. Experimental results on benchmark datasets demonstrate that the adaptive graph neural network with the incremental learning mechanism has excellent semantic awareness ability, which surpasses several excellent knowledge graph reasoning models.

Interactions between myoblasts and macrophages under high glucose milieus result in inflammatory response and impaired insulin sensitivity

BACKGROUND Skeletal muscle handles about 80% of insulin-stimulated glucose uptake and become the major organ occurring insulin resistance (IR). Many studies have confirmed the interactions between macrophages and skeletal muscle regulated the inflammation and regeneration of skeletal muscle. However, despite of the decades of research, whether macrophages infiltration and polarization in skeletal muscle under high glucose (HG) milieus results in the development of IR is yet to be elucidated. C2C12 myoblasts are well-established and excellent model to study myogenic regulation and its responses to stimulation. Further exploration of macrophages' role in myoblasts IR and the dynamics of their infiltration and polarization is warranted. AIM To evaluate interactions between myoblasts and macrophages under HG, and its effects on inflammation and IR in skeletal muscle. METHODS We detected the polarization status of macrophages infiltrated to skeletal muscles of IR mice by hematoxylin and eosin and immunohistochemical staining. Then, we developed an in vitro co-culture system to study the interactions between myoblasts and macrophages under HG milieus. The effects of myoblasts on macrophages were explored through morphological observation, CCK-8 assay, Flow Cytometry, and enzyme-linked immunosorbent assay. The mediation of macrophages to myogenesis and insulin sensitivity were detected by morphological observation, CCK-8 assay, Immunofluorescence, and 2-NBDG assay. RESULTS The F4/80 and co-localization of F4/80 and CD86 increased, and the myofiber size decreased in IR group (P &lt; 0.01, g = 6.26). Compared to Mc group, F4/80+CD86+CD206- cells, tumor necrosis factor-α (TNFα), inerleukin-1β (IL-1β) and IL-6 decreased, and IL-10 increased in McM group (P &lt; 0.01, g &gt; 0.8). In McM + HG group, F4/80+CD86+CD206- cells, monocyte chemoattractant protein 1, TNFα, IL-1β and IL-6 were increased, and F4/80+CD206+CD86- cells and IL-10 were decreased compared with Mc + HG group and McM group (P &lt; 0.01, g &gt; 0.8). Compered to M group, myotube area, myotube number and E-MHC were increased in MMc group (P &lt; 0.01, g &gt; 0.8). In MMc + HG group, myotube area, myotube number, E-MHC, GLUT4 and glucose uptake were decreased compared with M + HG group and MMc group (P &lt; 0.01, g &gt; 0.8). CONCLUSION Interactions between myoblasts and macrophages under HG milieus results in inflammation and IR, which support that the macrophage may serve as a promising therapeutic target for skeletal muscle atrophy and IR.

Molecular Mechanisms and Enhancement of Piezoelectricity in the M13 Virus

AbstractUnderstanding the structure and function of bioelectric materials is challenging due to the complex nature of biomaterials and a lack of appropriate tools. The precisely defined structures and genetic tunability of viruses provide an excellent model system to investigate bioelectrical behavior in biomaterials. This study presents the molecular mechanisms of piezoelectricity in the M13 bacteriophage (phage) under various mechanical stresses for bio‐piezoelectric generation. A computational approach is used to calculate the piezoelectric tensors of the M13 phage and quantify its direction‐dependent dipole moments. By computationally designing negatively charged residues on the phage surface, the surface charge density is enhanced to 16.7 µC cm−2. Using genetic engineering, phages are experimentally designed with different charges and tail structures to create model phage nanostructures, including individual phages, vertically standing phage films, and horizontally aligned phage films. Their vertical, horizontal, and shear‐mode piezoelectric properties are then measured using scanning probe microscopy techniques. The resulting phage‐based piezoelectric energy generators exhibit an effective piezoelectric coefficient of 15.4 pm V−1 and a power density of 4.2 µW cm−2. This phage‐based bioengineering approach provides a versatile platform for investigating fundamental mechanisms of bioelectricity and designing bioelectric materials for applications in energy harvesting, biomemory, and biosensors.

A predictive model for ischemic colitis: Integrating clinical and laboratory parameters

AbstractObjectiveWe aimed to develop a predictive model for the clinical diagnosis of ischemic colitis (IC).MethodsClinical data were collected from patients with acute IC lesions who were diagnosed and admitted to Beijing Tsinghua Changgung Hospital from January 2016 to December 2022. These patients were included in the IC case group in this retrospective observational study. The control group comprised patients aged ≥40 years who were diagnosed with abdominal pain during the same period, excluding those with IC. All patients were divided into a training and test sets based on the time window. Least absolute shrinkage and selection operator regression was used to screen risk factors for the occurrence of IC. Logistic stepwise regression (maximum likelihood ratio method) was performed in multifactorial analysis, and a diagnostic prediction model for IC was established using R language. The area under the receiver operating characteristic (ROC) curve (AUC) was examined to assess differentiation using working ROC curves. We used bootstrap resampling (1000 times) for internal validation. Model calibration curves and decision curve analysis (DCA) were also applied.ResultsOur study indicates that constipation, hematochezia, neutrophil counts, and specific abdominal computed tomography (CT) (plain scan) findings, including intestinal wall edema and thickening, intestinal lumen stenosis, and dilation, are independent predictors of IC. The predictive model exhibited high discriminative ability with an AUC of 0.9788 in the training set, and the calibration and DCA curves demonstrated excellent model performance. After validation, the AUC remained robust at 0.9868, underscoring the model's reliability in predicting IC.ConclusionAccording to our model, constipation accompanied by hematochezia necessitates careful consideration of IC. Abdominal CT (plain scan) is an effective diagnostic tool for IC, and it is common for patients to exhibit elevated neutrophil counts. The predictive model, demonstrating high discriminative ability and accuracy, shows promise for practical application in clinical settings, aiding in the early diagnosis and management of IC.

Liquid Crystals from Curved Colloidal Rods: Waves, Twists and More.

The curvature of elongated microscopic building blocks plays a crucial role on their self-assembly into orientationally ordered phases. While rod-like molecules form a handful of liquid crystal (LC) phases, curved or banana-shaped molecules show more than fifty phases, with fascinating physical properties, such as chirality or polarity. Despite the fundamental and technological importance of these so-called 'banana-shaped liquid crystals', little is know about their microscopic details at the single-molecule level. Curved colloidal liquid crystals - liquid crystals formed by curved colloidal rods -, are excellent model systems to optically resolve the structure and dynamics of curved building blocks within these condensed phases. Recent advances in the synthesis of curved rod-like particles have unlocked the potential for studying - at the single-particle level - the intimate relationship between shape and phase symmetry, and even confirmed the stability of elusive LC phases. Further developments in this nascent field promise exciting findings, such as the first observation of the colloidal twist-bend nematic phase or the fabrication of functional materials with curvature-dependent properties. In this perspective, we will highlight recent advances in the synthesis and assembly of curved colloidal liquid crystals and discuss the upcoming challenges and opportunities of this field.

Gekko gecko as a model organism for understanding aspects of laryngeal vocal evolution.

The ability to communicate through vocalization plays a key role in the survival of animals across all vertebrate groups. While avian reptiles have received much attention relating to their stunning sound repertoire, non-avian reptiles have been wrongfully assumed to have less elaborate vocalization types and little is known about the biomechanics of sound production and their underlying neural pathways. We investigated alarm calls of Gekko gecko using audio and cineradiographic recordings of their alarm calls. Acoustic analysis revealed three distinct call types: a sinusoidal call type (type 1), a train-like call type, characterized by distinct pulse trains (type 3), and an intermediary type, which showed both sinusoidal and pulse train components (type 2). Kinematic analysis of cineradiographic recordings showed that laryngeal movements differ significantly between respiratory and vocal behavior: during respiration, animals repeatedly moved their jaws to partially open their mouths, which was accompanied by small glottal movements. During vocalization, the glottis was pulled back, contrasting with what has previously been reported. In-vitro retrograde tracing of the nerve innervating the laryngeal constrictor and dilator muscles revealed round to fusiform motoneurons in the hindbrain-spinal cord transition ipsilateral to the labeled nerve. Taken together, our observations provide insight into the alarm calls generated by G. gecko, the biomechanics of this sound generation and the underlying organization of motoneurons involved in the generation of vocalizations. Our observations suggest that G. gecko may be an excellent non-avian reptile model organism for enhancing our understanding of the evolution of vertebrate vocalization.

An efficient inducible model for the control of gene expression in renin cells.

Fate mapping and genetic manipulation of renin cells have relied on either non-inducible Cre lines that can introduce developmental effects of gene deletion or BAC transgene-based inducible models that may be prone to spurious and/or ectopic gene expression. To circumvent these problems, we generated an inducible mouse model in which CreERT2 is under the control of the endogenous Akr1b7 gene, an independent marker of renin cells that is expressed in a few extrarenal tissues. We confirmed the proper expression of Cre using Akr1b7CreERT2/+;R26RmTmG/+ mice in which Akr1b7+/renin+ cells become GFP+ upon tamoxifen administration. In embryos and neonates, GFP was found in Juxtaglomerular cells, along the arterioles, and in the mesangium, and in adults, GFP was present mainly in Juxtaglomerular cells. In mice treated with captopril and a low salt diet to induce recruitment of renin cells, GFP extended along the afferent arterioles and in the mesangium. We generated Akr1b7CreERT2/+;Ren1cFl/-;R26RmTmG/+ mice to conditionally delete renin in adult mice and found a marked reduction in kidney renin mRNA and protein, and mean arterial pressure in mutant animals. When subjected to a homeostatic threat, mutant mice were unable to recruit renin+ cells. Most importantly, these mice developed concentric vascular hypertrophy ruling out potential developmental effects on the vasculature due to the lack of renin. We conclude that Akr1b7CreERT2 mice constitute an excellent model for the fate mapping of renin cells and for the spatial and temporal control of gene expression in renin cells.

The Silverjaw Minnow, Ericymba buccata: An Extraordinary Lateral Line System and Its Contribution to Prey Detection.

Fishes use their mechanosensory lateral line system to detect local water flows in different behavioral contexts, including the detection of prey. The lateral line system is comprised of neuromast receptor organs on the skin (superficial neuromasts) and within bony canals (canal neuromasts). Most fishes have one cranial lateral line canal phenotype, but the silverjaw minnow (Ericymba buccata) has two: narrow canals dorsal and caudal to the eye and widened canals ventral to the eye and along the mandible. The ventrally directed widened lateral line canals have been hypothesized to be an adaptation for detection of their benthic prey. Multiple morphological methods were used to describe the narrow and widened canals and canal neuromasts in detail. The primary distribution of hundreds of superficial neuromasts and taste buds ventral to the eye and on the mandible (described here for the first time) suggests additional sensory investment for detecting flow and chemical stimuli emanating from benthic prey. The hypothesis that the lateral line system mediates prey localization was tested by measuring five parameters in behavioral trials in which the combination of sensory modalities available to fish was manipulated (four experimental treatments). Fish detected and localized prey regardless of available sensory modalities and they were able to detect prey in the dark in the absence of lateral line input (lateral line ablation with neomycin sulfate) revealing that chemoreception was sufficient to mediate benthic prey detection, localization, and consumption. However, elimination of lateral line input resulted in a change in the angle of approach to live (mobile) prey even when visual input was available, suggesting that mechanosensory input contributes to the successful detection and localization of prey. The results of this study demonstrate that the extraordinary lateral line canal system of the silverjaw minnow, in addition to the large number of superficial neuromasts, and the presence of numerous extraoral taste buds, likely represent adaptations for multimodal integration of sensory inputs contributing to foraging behavior in this species. The morphological and behavioral results of this study both suggest that this species would be an excellent model for future comparative structural and functional studies of sensory systems in fishes.

Behaviour of Tunisian Psammomys obesus fed high-calorie diets: biochemical disturbance and histopathological alterations

This work investigated the biochemical disturbances and histological alteration in Psammomys obesus animal model fed different high calorie diets (HCDs) during three months. Four diets were used: a low-calorie natural diet, Chenopodiaceae halophyte plant used as control (LCD), a high standard carbohydrate diet rich in protein, HCD 0, a high carbohydrate diet rich in two concentrations of fat, HCD 1 and HCD 2. All animals having received HCDs developed dyslipidemia after one month of experiment with distinction of different sub-groups developing or not obesity and diabetes. HCDs induced a remarkable increasing in blood cholesterol, LDL-cholesterol and triglyceride levels indicating a fast induction of dyslipidemia and a significant increase of aminotransaminases activities revealing a pronounced hepatotoxicity. Animal developing diabetes showed a severe hepatic injury, a degeneration of the adipose tissue and a significant reduction of retinal thickness. P. obesus seems to be an excellent animal model to investigate nutritional metabolic diseases.

Behaviour of Tunisian Psammomys obesus fed high-calorie diets: biochemical disturbance and histopathological alterations

This work investigated the biochemical disturbances and histological alteration in Psammomys obesus animal model fed different high calorie diets (HCDs) during three months. Four diets were used: a low-calorie natural diet, Chenopodiaceae halophyte plant used as control (LCD), a high standard carbohydrate diet rich in protein, HCD 0, a high carbohydrate diet rich in two concentrations of fat, HCD 1 and HCD 2. All animals having received HCDs developed dyslipidemia after one month of experiment with distinction of different sub-groups developing or not obesity and diabetes. HCDs induced a remarkable increasing in blood cholesterol, LDL-cholesterol and triglyceride levels indicating a fast induction of dyslipidemia and a significant increase of aminotransaminases activities revealing a pronounced hepatotoxicity. Animal developing diabetes showed a severe hepatic injury, a degeneration of the adipose tissue and a significant reduction of retinal thickness. P. obesus seems to be an excellent animal model to investigate nutritional metabolic diseases.

Agouti-induced anxiety-like behaviour is mediated by central serotonergic pathways in zebrafish.

Overexpression of the agouti-signalling protein (asip1), an endogenous melanocortin antagonist, under the control of a constitutive promoter in zebrafish [Tg(Xla.Eef1a1:Cau.Asip1]iim4] (asip1-Tg) increases food intake by reducing sensitivity of the central satiety systems and abolish circadian activity rhythms. The phenotype also shows increased linear growth and body weight, yet no enhanced aggressiveness in dyadic fights is observed. In fact, asip1-Tg animals choose to flee to safer areas rather than face a potential threat thus suggesting a potential anxiety-like behaviour (ALB). Standard behavioural tests, i.e. the open field test (OFT), the novel object test (NOT) and the novel tank dive test (NTDT) were used to investigate thigmotaxis and ALB in male and female zebrafish. Results showed that the asip1-Tg strain exhibited severe ALB in every test, mainly characterised by pronounced freezing behaviour and increased linear and angular swimming velocities. asip1-Tg animals exhibited low central serotonin (5HT) and dopamine (DA) levels and high turnover rates, thus suggesting that central monoaminergic pathways might mediate melanocortin antagonist-induced ALB. Accordingly, the treatment of asip1-Tg animals with fluoxetine, a selective serotonin reuptake inhibitor (SSRI), reversed the ALB phenotype in NTDT as well as 5-HT turnover. Genomic and anatomical data further supported neuronal interaction between melanocortinergic and serotonergic systems. These results suggest that inhibition of the melanocortin system by ubiquitous overexpression of endogenous antagonist has an anxiogenic effect mediated by serotonergic transmission.Significance statement In this paper, we show that inhibition of the melanocortin system by ubiquitous overexpression of endogenous antagonists has a potent anxiogenic effect mediated by serotonergic transmission in zebrafish. asip1-overexpressing fish (asip1-Tg) also exhibit a severe disruption of the central satiety system, leading to increased feed intake and abolishing circadian locomotor activity patterns. The melanocortin system plays a key role in the control of hunger, and data suggest that the anxiety-like behaviour in asip1-Tg may be related to the feeding anxiety induced by negative energy balance states, which promote constant foraging and thus disrupt activity rhythms. This makes asip1-Tg animals an excellent model to study dieting-induced anxiety, one of the major causes of dieting failure.

Whole Genomes Reveal Evolutionary Relationships and Mechanisms Underlying Gene-Tree Discordance in Neodiprion Sawflies.

Rapidly evolving taxa are excellent models for understanding the mechanisms that give rise to biodiversity. However, developing an accurate historical framework for comparative analysis of such lineages remains a challenge due to ubiquitous incomplete lineage sorting and introgression. Here, we use a whole-genome alignment, multiple locus-sampling strategies, and summary-tree and SNP-based species-tree methods to infer a species tree for eastern North American Neodiprion species, a clade of pine-feeding sawflies (Order: Hymenopteran; Family: Diprionidae). We recovered a well-supported species tree that-except for three uncertain relationships-was robust to different strategies for analyzing whole-genome data. Nevertheless, underlying gene-tree discordance was high. To understand this genealogical variation, we used multiple linear regression to model site concordance factors estimated in 50-kb windows as a function of several genomic predictor variables. We found that site concordance factors tended to be higher in regions of the genome with more parsimony-informative sites, fewer singletons, less missing data, lower GC content, more genes, lower recombination rates, and lower D-statistics (less introgression). Together, these results suggest that incomplete lineage sorting, introgression, and genotyping error all shape the genomic landscape of gene-tree discordance in Neodiprion. More generally, our findings demonstrate how combining phylogenomic analysis with knowledge of local genomic features can reveal mechanisms that produce topological heterogeneity across genomes.

Essential role of p21Waf1/Cip1 in the modulation of post-traumatic hippocampal Neural Stem Cells response

BackgroundTraumatic Brain Injury (TBI) represents one of the main causes of brain damage in young people and the elderly population with a very high rate of psycho-physical disability and death. TBI is characterized by extensive cell death, tissue damage and neuro-inflammation with a symptomatology that varies depending on the severity of the trauma from memory loss to a state of irreversible coma and death. Recently, preclinical studies on mouse models have demonstrated that the post-traumatic adult Neural Stem/Progenitor cells response could represent an excellent model to shed light on the neuro-reparative role of adult neurogenesis following damage. The cyclin-dependent kinase inhibitor p21Waf1/Cip1 plays a pivotal role in modulating the quiescence/activation balance of adult Neural Stem Cells (aNSCs) and in restraining the proliferation progression of progenitor cells. Based on these considerations, the aim of this work is to evaluate how the conditional ablation of p21Waf1/Cip1 in the aNSCS can alter the adult hippocampal neurogenesis in physiological and post-traumatic conditions.MethodsWe designed a novel conditional p21Waf1/Cip1 knock-out mouse model, in which the deletion of p21Waf1/Cip1 (referred as p21) is temporally controlled and occurs in Nestin-positive aNSCs, following administration of Tamoxifen. This mouse model (referred as p21 cKO mice) was subjected to Controlled Cortical Impact to analyze how the deletion of p21 could influence the post-traumatic neurogenic response within the hippocampal niche.ResultsThe data demonstrates that the conditional deletion of p21 in the aNSCs induces a strong increase in activation of aNSCs as well as proliferation and differentiation of neural progenitors in the adult dentate gyrus of the hippocampus, resulting in an enhancement of neurogenesis and the hippocampal-dependent working memory. However, following traumatic brain injury, the increased neurogenic response of aNSCs in p21 cKO mice leads to a fast depletion of the aNSCs pool, followed by declined neurogenesis and impaired hippocampal functionality.ConclusionsThese data demonstrate for the first time a fundamental role of p21 in modulating the post-traumatic hippocampal neurogenic response, by the regulation of the proliferative and differentiative steps of aNSCs/progenitor populations after brain damage.