Spine Shape Research Articles

Morphological and molecular characterization of larval Echinocephalus sp. (Spirurida: Gnathostomatidae), a parasite of the greater lizard fish (Saurida undosquamis) and red porgy or common seabream (Pagrus pagrus).

Larvae of an unidentified Echinocephalus species were obtained from two fish species: red porgy or common seabream (Pagrus pagrus) and greater lizard fish (Saurida undosquamis) from the Red Sea. The prevalence of Echinocephalus sp. larvae in P. pagrus was 4.92% and 4.98% in S. undosquamis. The length, width, cephalic bulb, and spine shape and pattern of the larvae resembled Echinocephalus overstreeti. SSU gene sequences of larvae from P. pagrus and S. undosquamis were identical. Comparison of the SSU sequence to those available in GenBank showed that the larvae from P. pagrus and S. undosquamis are diagnosably distinct. Based on sequence similarity and published phylogenetic analysis, these larvae are most similar to an unknown species of Echinocephalus from an Australian sea snake (Hydrophis peronii). Despite morphological similarities of the Red Sea larvae to E. overstreeti, the SSU sequence differences show that they are not the same species.

81. Does the spinal shape described by the Roussouly Classification explain proximal junctional kyphosis?

81. Does the spinal shape described by the Roussouly Classification explain proximal junctional kyphosis?

P102. Quantifying the impact of spinal shape: incorporating Roussouly criteria into novel alignment schemata increases probability of optimal radiographic alignment in adult spinal deformity surgery

P102. Quantifying the impact of spinal shape: incorporating Roussouly criteria into novel alignment schemata increases probability of optimal radiographic alignment in adult spinal deformity surgery

Cofilin overactivation improves hippocampus-dependent short-term memory.

Many living organisms of the animal kingdom have the fundamental ability to form and retrieve memories. Most information is initially stored as short-term memory, which is then converted to a more stable long-term memory through a process called memory consolidation. At the neuronal level, synaptic plasticity is crucial for memory storage. It includes the formation of new spines, as well as the modification of existing spines, thereby tuning and shaping synaptic efficacy. Cofilin critically contributes to memory processes as upon activation, it regulates the shape of dendritic spines by targeting actin filaments. We previously found that prolonged activation of cofilin in hippocampal neurons attenuated the formation of long-term object-location memories. Because the modification of spine shape and structure is also essential for short-term memory formation, we determined whether overactivation of hippocampal cofilin also influences the formation of short-term memories. To this end, mice were either injected with an adeno-associated virus expressing catalytically active cofilin, or an eGFP control, in the hippocampus. We show for the first time that cofilin overactivation improves short-term memory formation in the object-location memory task, without affecting anxiety-like behavior. Surprisingly, we found no effect of cofilin overactivation on AMPA receptor expression levels. Altogether, while cofilin overactivation might negatively impact the formation of long-lasting memories, it may benefit short-term plasticity.

Efficacy of Varying Surgical Approaches on Achieving Optimal Alignment in Adult Spinal Deformity Surgery.

The Roussouly, SRS-Schwab, and GAP classifications define alignment by spinal shape and deformity severity. The efficacy of different surgical approaches and techniques to successfully achieve these goals is not well understood. Identify the impact of surgical approach and/or technique on meeting complex realignment goals in adult spinal deformity(ASD) corrective-surgery. Retrospective. Included: ASD patients fused to pelvis with two-year(2Y) data. Patients were categorized by: 1)Roussouly: matching current and theoretical spinal shapes; 2)improving in SRS-Schwab modifiers(0, +, ++); 3)improving GAP Proportionality by 2Y. ANCOVA and multivariable logistic regression analyses controlling for age, levels fused, baseline deformity, and three-column osteotomy usage compared the effect of different surgical approaches, interbody and osteotomy use on meeting realignment goals. 693 ASD patients were included. By surgical approach, 65.7% were posterior-only and 34.3% underwent anterior-posterior(AP) approach with 76% receiving an osteotomy(21.8% 3CO). By 2Y, 34% matched Roussouly, 58% improved in GAP, 45% in SRS-Schwab PT, 62% SVA, and 70% PI-LL. Combined approaches were most effective for improvement in PT(OR: 1.7,[1.1-2.5]) and GAP(OR: 2.2,[1.5-3.2]). Specifically, ALIFs below L3 demonstrated higher rates of improvement versus TLIFs in Roussouly(OR: 1.7, [1.1-2.5]) and GAP(OR: 1.9, [1.3-2.7]). Patients undergoing PSO at L3 or L4 were more likely to improve in PT(OR: 2.0,[1.0-5.2]) and PI-LL(OR: 3.8[1.4-9.8]). Clinically, patients undergoing combined approach demonstrated higher rates of meeting SCB in ODI by 2Y while minimizing rates of PJF, most often with an ALIF at L5-S1(ODI-SCB: OR: 1.4,[1.1-2.0];PJF: OR: 0.4,[0.2-0.8]). Among patients undergoing ASD realignment, optimal lumbar shape and proportion can be achieved more often with a combined approach. While TLIFs incorporating a three-column osteotomy at L3 and L4 can restore lordosis and normalize pelvic compensation, ALIFs at L5-S1 were most likely to achieve complex realignment goals with an added clinical benefit and mitigation of junctional failure.

DiGeorge syndrome critical region gene 2 (DGCR2), a schizophrenia risk gene, regulates dendritic spine development through cell adhesion

BackgroundDendritic spines are the sites of excitatory synapses on pyramidal neurons, and their development is crucial for neural circuits and brain functions. The spine shape, size, or number alterations are associated with neurological disorders, including schizophrenia. DiGeorge syndrome critical region gene 2 (DGCR2) is one of the deleted genes within the 22q11.2 deletion syndrome (22q11DS), which is a high risk for developing schizophrenia. DGCR2 expression was reduced in schizophrenics. However, the pathophysiological mechanism of DGCR2 in schizophrenia or 22q11DS is still unclear.ResultsHere, we report that DGCR2 expression was increased during the neurodevelopmental period and enriched in the postsynaptic densities (PSDs). DGCR2-deficient hippocampal neurons formed fewer spines. In agreement, glutamatergic transmission and synaptic plasticity were decreased in the hippocampus of DGCR2-deficient mice. Further molecular studies showed that the extracellular domain (ECD) of DGCR2 is responsible for its transcellular interaction with cell adhesion molecule Neurexin1 (NRXN1) and spine development. Consequently, abnormal behaviors, like anxiety, were observed in DGCR2-deficient mice.ConclusionsThese observations indicate that DGCR2 is a novel cell adhesion molecule required for spine development and synaptic plasticity, and its deficiency induces abnormal behaviors in mice. This study provides a potential pathophysiological mechanism of DGCR2 in 22q11DS and related mental disorders.

Three-dimensional spinal shape changes during daily activities

Motivation:Intuitive assessment of spinal motion poses a tremendous challenge to both physicians and computer modelers. On the one side, medically detailed analyses of spinal shapes, such as computer tomography or X-ray images, are usually subject to static boundary constraints, thereby omitting dynamic information. On the other side, complex computer simulations often lack proper calibration aside from few control points, particularly regarding the three-dimensional arrangement of the spinal column and its idiomotion. Purpose:Here, we investigate whether the full three-dimensional changes in spinal shape over time can be concisely detected and depicted. Further, we assess which parts of the spine undergo significant changes during various daily activities. Methods:We utilize a set of previously published motion capture data from the spinous processes (sacrum up to vertebra C7) of 17 healthy individuals performing the daily tasks of standing, walking, stair climbing, sitting down, and lifting. These three-dimensional, time-dependent marker positions were approximated by a Bézier curve at each time instant. The curves’ characteristics, i.e.curvature and torsion, were calculated and juxtaposed for each individual and each activity over time. A statistical parametric mapping revealed significant changes in spinal shape. Results:We found the individual spinal shape characteristics being recognizably preserved during all activities. The walking task did not significantly alter the spinal curvature, while sitting and forward bending significantly altered the lumber and whole spine curvature, respectively. Torsion did not show any significant alterations. Conclusion:Based on these results, we suggest that individualized dynamic information on spinal shapes can improve (i) the evaluation of (healthy) motion characteristics, (ii) the detection of pathologies, and (iii) individualized computer simulation models.

Pollen morphology of selected Brazilian species of Abolboda Humb. et Bonpl. (Xyridaceae): a statistical approach

Previous studies on Abolboda pollen did not conduct statistical analyses of morphological data. Here, the pollen morphology of four Brazilian species and three varieties, represented by 13 herbarium specimens, is described. Pollen grains were treated by 60% lactic acetolysis, measured and photographed under light and scanning electron microscopy. A multivariate analysis was performed for the first time to find possible features that aid the specific and infraspecific delimitation within this genus. Abolboda is characterised by pollen grains in monads that are spheroidal, large to very large sized (59.9 µm [A. abbreviata] to 158.9 µm [A. pulchella]), inaperturate and atectate. The nexine is very thick. The spine shape and the width of its base have been considered specific and infraspecific diagnostic features; however, at present, they are not considered consistent characters with a systematic value. The combination of pollen size, nexine thickness, and dimensions of the sexine excrescences (‘inverted funnelform shaped’ spines, ‘obconical shaped’ spines, and baculum-like, pilum-like or verruca-like elements) are the most important characteristics at the species level and for grouping the varieties. This study presents informative morphological data useful for future phylogenetic optimisation and contributes to the systematics of the Abolboda genus.

Morphological variations in some brinjal (Solanum melongena L.) genotypes

Fifteen brinjal genotypes were grown under field condition during the period from September 2019 to March 2020 to study the variation in their morphological characters. Based on the growth habit, the genotypes were classified as erect, semi-erect, and spreading types. Hair was observed generally on the leaf and stem while variability in spine, fruit color, and fruit shape were found among the genotypes. Days to first fruit harvest ranged from 79.67 to 103 days, while the leaf area ranged from 44.33 to 83.67 cm in the genotypes studied. The highest values for the fruit length and breadth had the means of 37.93 and 8.03 cm, respectively. The number of fruits per plant ranged from 9 to 23 with an average yield of 1.08 to 7.65 kg per plant. This study revealed significant morphological variations among the genotypes evaluated, which could be utilized into future breeding programs. Bangladesh J. Agri. 2023, 48(1): 123-129

Creation and Evaluation of a Severity Classification of Hyperkyphosis and Hypolordosis for Exercise Therapy.

The rise in the occurrence of musculoskeletal disorders, such as thoracic hyperkyphosis (THK) or lumbar hypolordosis (LHL), is a result of demographic changes. Exercise therapy is an effective approach that can reduce related disabilities and costs. To ensure successful therapy, an individualized exercise program adapted to the severity of the disorder is expedient. Nevertheless, appropriate classification systems are scarce. This project aimed to develop and evaluate a severity classification focused on exercise therapy for patients with THK or LHL. A multilevel severity classification was developed and evaluated by means of an online survey. Reference limits of spinal shape angles were established by data from video rasterstereography of 201 healthy participants. A mean kyphosis angle of 50.03° and an average lordosis angle of 40.72° were calculated as healthy references. The strength of the multilevel classification consisting of the combination of subjective pain and objective spinal shape factors was confirmed by the survey (70% agreement). In particular, the included pain parameters were considered relevant by 78% of the experts. Even though the results of the survey provide important evidence for further analyses and optimization options of the classification system, the current version is still acceptable as therapeutic support.

Rod angulation does not reflect sagittal curvature in adult spinal deformity surgery: comparison of lumbar lordosis and rod contouring.

A retrospective study. Relationship between rod and spinal shape in the sagittal plane in adult spinal deformity (ASD) surgery. Corrective surgery for adult spinal deformity (ASD) involves the use of contoured rods to correct and modify the spinal curvatures. Adequate rod bending is crucial for achieving optimal correction. The correlation between rods and spinal shape in long constructs has not been reported previously. We conducted a retrospective analysis of a prospective, multicenter database of patients who underwent surgery for ASD. The inclusion criteria were patients who underwent pelvic fixation and had an upper instrumented vertebra at or above T12. Pre- and post-operative standing radiographs were used to assess lumbar lordosis at the L4S1 and L1S1 levels. The angle between the tangents to the rod at the L1, L4, and S1 pedicles was calculated to determine the L4S1 and L1S1 rod lordosis. The difference between the lumbar lordosis (LL) and the rod lordosis (RL) was calculated as ΔL = LL-RL. The correlation between this difference (ΔL) and various characteristics was analyzed using descriptive and statistical methods. Eighty-three patients were included in the study, resulting in 166 analyzed differences (ΔL) between the rod and spinal lordosis. The values for rod lordosis were found to be both greater and lesser than those of the spine but were mostly lower. The range for total ΔL was -24°-30.9°, with a mean absolute ΔL of 7.8° for L1S1 (standard deviation (SD) = 6.0) and 9.1° for L4S1 (SD = 6.8). In 46% of patients, both rods had a ΔL of over 5°, and over 60% had at least one rod with a ΔL difference of over 5°. Factors found to be related to a higher ΔL included postoperative higher lumbar lordosis, presence of osteotomies, higher corrected degrees, older age, and thinner rods. Multivariate analysis correlated only higher postoperative L1S1 lordosis with higher ΔL. No correlation was found between a higher ΔL and sagittal imbalance. Variations between spinal and rod curvatures were observed despite the linear regression correlation. The shape of the rod does not seem to be predictive of the shape of the spine in the sagittal plane in ASD long-construct surgeries. Several factors, other than rod contouring, are involved in explaining the postoperative shape of the spine. The observed variation calls into question the fundamentals of the ideal rod concept.

VLTENet: A Deep-Learning-Based Vertebra Localization and Tilt Estimation Network for Automatic Cobb Angle Estimation.

Scoliosis diagnosis and assessment rely upon Cobb angle estimation from X-ray images of the spine. Recently, automated scoliosis assessment has been greatly improved using deep learning methods. However, in such methods, the Cobb angle is usually predicted based on regression models that don't account for information of the spine structure. Alternatively, the Cobb angle can be estimated indirectly through landmark-detection and vertebra-segmentation, but this approach is still highly sensitive to small detection and segmentation errors. This paper proposes a novel deep-learning architecture, called the vertebra localization and tilt estimation network (VLTENet). This network boosts the Cobb angle estimation accuracy through employing vertebra localization and tilt estimation as network prediction goals. In particular, the VLTENet model innovatively combines a deep high-resolution network (HRNet) and a fully-convolutional U-Net architecture for capturing long-range contextual information, the overall structure, and local details in spinal X-ray images. A feature fusion channel attention (FFCA) module is also proposed to selectively emphasize more informative features and suppress less informative ones. In addition, a joint spine loss function (JS-Loss) is designed to account for the spine shape and other spatial constraints, so that the network focuses more on spine-related regions and ignore irrelevant background regions. Finally, we propose a new Cobb angle estimation method conforms with the clinical Cobb angle calculation guidelines, and produces accurate estimates for different types of scoliosis. Extensive experiments on the publically-available AASCE challenge dataset and on an in-house dataset demonstrated the superiority of our method for the task of automatic assessment of scoliosis.

MORPHOLOGY AND TAXONOMY OF <i>AULACOSEIRA ALPIGENA</i> (BACILLARIOPHYTA) AND ITS DISTRIBUTION IN RUSSIA

The study of materials from Western and Eastern Siberia and the Far East has revealed a significant variability of an important diagnostic feature (the shape of spines) in Aulacoseira alpigena and a wider range of the species. This study and published data make it possible to emend the diagnosis of A. alpigena and reduce it to the synonyms of a morphologically similar species A. helvetica.

The role of spine curvatures in the sagittal plane in physical performance among team sports players.

Spine shapes determine the body posture, which could also be impacted by specific sports training. However, the meaning of spine curvatures in physical performance remains unclear. This study aimed to investigate the role of spine curvatures in the sagittal plane in physical performance regarding team sports training. The study sample included 21±2.1 years old males: 19 team sport players (TSP) and 17 average physically active men (comparison group, CG). The spine curvatures in the sagittal plane were assessed using the photogrammetric method (Moire), and physical performance tests were conducted. The sacrolumbar spine position was positively related to speed abilities only in TSP. The sacrolumbar spine inclination angle (α) increase by one unit was associated with improving the time in the 20 m linear speed and agility t-test measured change of direction speed (CODs) by 0.02 s and 0.07 s, respectively. The downsized lumbar lordosis angle by a one-unit caused improvement by 0.01s in 20 m linear speed. In CG, it was revealed that a higher thoracolumbar spine inclination angle (β) was associated with a worse ability to maintain static balance. In TSP, sacrolumbar spine position is associated with speed abilities. The flattened spine curves are not conducive to linear speed and CODs. There is a need to keep proper spine curvatures to develop and maintain high physical performance. Indicated sagittal plane spine curvatures could predispose to better speed performance. Measurement of these parameters could be valuable in prediction speed and CODs abilities.

The morphological diversity of pollen in the genus Gossypium

BackgroundPlant pollen has diverse morphological characteristics that can be consistently passed down from generation to generation. Information on pollen morphology is thus immensely important for plant classification and identification. In the genus Gossypium, however, in-depth research on pollen morphology is lacking, with only few reports on limited cotton species. To evaluate the diversity of pollen in Gossypium, we therefore conducted a comprehensive analysis of the pollen morphology of 33 cotton species and varieties using scanning electron microscopy.ResultsThe 33 analyzed cotton samples exhibited common pollen morphological features, including spherical shapes, radial symmetry, echination, panporation, and operculation, while the pollen size, spine shape, spine density and length showed distinctive features. Pollen size varied significantly among species, with diameters ranging from 62.43 μm in G. harknessii to 103.41 μm in G. barbadense. The exine had an echinate sculptural texture, and spines were mostly conical or sharply conical but occasionally rod-like. Spine density varied from 173 in G. incanum to 54 in G. gossypioides, while spine length ranged from 3.53 μm in G. herbaceum to 9.47 μm in G. barbadense. In addition, the 33 cotton species and varieties were grouped at a genetic distance of 3.83 into three clusters. Cluster I comprised five allotetraploid AD-genome cotton species, four D-genome species, and one K-genome species. Cluster II included 13 diploid species from A, B, D, E, and G genomes, whereas Cluster III only consisted one E-genome species G. incanum.ConclusionsAlthough pollen characteristics alone are not enough to resolve taxonomic and systematic relationships within the genus Gossypium, our results add to knowledge on palynomorphology and contribute to phenological information on these taxa. Our findings should aid future systematic and phylogenetic studies of the Gossypium genus.

Predicting spinal column profile from surface topography via 3D non-contact surface scanning.

3D Non-Contact surface scanning (3DSS) is used in both biomechanical and clinical studies to capture accurate 3D images of the human torso, and to better understand the shape and posture of the spine-both healthy and pathological. This study sought to determine the efficacy and accuracy of using 3DSS of the posterior torso, to determine the curvature of the spinal column in the lateral lying position. A cohort of 50 healthy adults underwent 3DSS and Magnetic Resonance Imaging (MRI) to correlate the contours of the external spine surface with the internal spinal column. The correlation analysis was composed of two phases: (1) MRI vertebral points vs MRI external spine surface markers; and (2) MRI external spine surface markers vs 3DSS external spine surface markers. The first phase compared the profiles of fiducial markers (vitamin capsules) adhered to the skin surface over the spinous processes against the coordinates of the spinous processes-assessing the linear distance between the profiles, and similarity of curvature, in the sagittal and coronal planes. The second phase compared 3DSS external spine surface markers with the MRI external spine surface markers in both planes, with further qualitative assessment for postural changes. The distance between the MRI vertebral points and MRI external spine surface markers showed strong statistically significant correlation with BMI in both sagittal and coronal planes. Kolmogorov-Smirnov (KS) tests showed similar no significant difference in curvature, k, in almost all participants on both planes. In the second phase, the coronal 3DSS external spine surface profiles were statistically different to the MRI external spine surface markers in 44% of participants. Qualitative assessment showed postural changes between MRI and 3DSS measurements in these participants. These study findings demonstrate the utility and accuracy of using anatomical landmarks overlaid on the spinous processes, to identify the position of the spinal bones using 3DSS. Using this method, it will be possible to predict the internal spinal curvature from surface topography, provided that the thickness of the overlaying subcutaneous adipose layer is considered, thus enabling postural analysis of spinal shape and curvature to be carried out in biomechanical and clinical studies without the need for radiographic imaging.

The relationship between minor coronal asymmetry of the spine and measures of spinal sagittal shape in adolescents without visible scoliosis

The purpose of this work is to identify what features of overall spinal sagittal shape are associated with coronal asymmetry in those without scoliosis. Using a longitudinal analysis of Integrated Shape Imaging System 2 (ISIS2) surface topography images of those without scoliosis, measures of coronal asymmetry, along with measures of spinal sagittal shape (kyphosis, lordosis and sagittal imbalance, which is a measure of the position of the top of the thoracic spine relative to the sacrum) were analysed using linear mixed effect models (LMEM), which is a method of analysing the components of a complex model (such as that describing overall spinal shape), to ascertain the relative relationships between the parameters. Data was also analysed when subdivided for the anatomical level of coronal asymmetry (thoracic or thoracolumbar/lumbar pattern). There were 784 measures from 196 children. Kyphosis had little effect on coronal asymmetry for males and females, lordosis increased with coronal asymmetry in females only and sagittal imbalance increased with coronal asymmetry in males only. The results of the LMEM modelling were that the parameters related to coronal asymmetry were lordosis and sagittal imbalance. In thoracic coronal asymmetry, whilst lordosis was predominant, kyphosis played more of a role. In thoracolumbar/lumbar coronal asymmetry, lordosis and sagittal imbalance were the larger coefficients. Coronal asymmetry of the spine in those without scoliosis is related to features of spinal sagittal shape, particularly lordosis and sagittal imbalance. This knowledge adds to the understanding of the aetiology of adolescent idiopathic scoliosis.

Variation in Lumbar Shape and Lordosis in a Large Asymptomatic Population: A MEANS Study.

Prospective, cross-sectional cohort study. To determine the relationship between lumbar shape and sagittal parameters. Understanding the lumbar shape is vital for deformity surgery. Normative sagittal parameters and spine shape remain unstudied in large, multiethnic, asymptomatic cohorts. A prospective, cross-sectional cohort of 468 asymptomatic volunteers between 18 and 80 years was enrolled across 5 countries. Demographic data and radiographic parameters such as pelvic incidence (PI) were collected. Pearson correlation test and linear regression were used to find the relationship between lumbar lordosis (LL) and other parameters. One-way analysis of variance and Welch 2-sample t test were performed to compare lumbar shape across such categories as PI and lumbar apex followed by post hoc Bonferroni correction if needed. PI was moderately correlated with proximal lumbar lordosis (pLL) ( r = -0.54) and weakly correlated with distal lumbar lordosis (dLL) ( r = -0.16). Thoracic kyphosis (T1-T12) was moderately correlated with pLL ( r = -0.35) and dLL ( r = -0.29). dLL was moderately correlated with LL ( r = 0.64). 2.6% (12/468) of subjects had lumbar apex at L2, 40.2% (188/468) at L3, 56.6% at L4 (265/468), and 0.6% (3/468) at other levels. Mean PI was different between volunteers with the apex at L3 and L4. A lower mean PI was associated with the apex at L4 (49.0°), whereas a higher mean PI was associated with the apex at L3 (55.8°). The mean PI-LL mismatch for volunteers was -5.4° with a range from -35° to 39.7°. PI-LL mismatch increased from a mean of -10.1° in volunteers with low PI to a mean of 2.2° in volunteers with high PI. Age was not correlated with LL ( P = 0.84). In asymptomatic adult volunteers, pLL showed a moderate correlation with PI and increased with PI, whereas dLL showed a weak correlation. The lumbar apex migrated proximally with increasing PI. Segmental lordosis and apex position instead of solely global lordosis should be emphasized. Level III.

Taurus of the Tidepool? Inferring the Function of Cranial Weapons in Intertidal Sculpins (Pisces: Cottoidea: Oligocottinae)

From dissuading predators to gaining an edge on intraspecific rivals, animals have evolved weapons to meet various needs. Those with the most extreme weapons often use them to battle conspecifics, but some weapons defend against predation and others signal prowess to prospective mates and rivals. Many fishes have evolved armaments, but humans rarely observe these structures in action due to the inaccessibility of many weapon-bearing fish species. For example, how sculpins use the diverse horn-like spines that project from their head remains a mystery. We deduced the function of the weaponized preopercle in the 16 species of sculpins in the subfamily Oligocottinae by determining whether they exhibit three well-documented hallmarks of offensive weapons in terrestrial animals: ontogenetic change, sexual dimorphism, and fluctuating asymmetry. Geometric morphometrics of micro-computed tomography (lCT) scans show no sexual dimorphism in preopercular spine shape but reveal phylogenetically widespread ontogenetic shape change. Fluctuating asymmetry is low to moderate across species. Taken together, these results suggest that despite their varied reproductive habits, frequent territoriality, and possession of weapons that resemble bovid horns, oligocottine sculpins evolved their spines primarily to defend against predators.

Urp1 and Urp2 act redundantly to maintain spine shape in zebrafish larvae

Urp1 and Urp2 are two neuropeptides, members of the Urotensin 2 family, that have been recently involved in the control of body axis morphogenesis in zebrafish. They are produced by a population of sensory spinal neurons, called cerebrospinal fluid contacting neurons (CSF-cNs), under the control of signals relying on the Reissner fiber, an extracellular thread bathing in the CSF. Here, we have investigated further the function of Urp1 and Urp2 (Urp1/2) in body axis formation and maintenance. We showed that urp1;urp2 double mutants develop strong body axis defects during larval growth, revealing the redundancy between the two neuropeptides. These defects were similar to those previously reported in uts2r3 mutants. We observed that this phenotype is not associated with congenital defects in vertebrae formation, but by using specific inhibitors, we found that, at least in the embryo, the action of Urp1/2 signaling depends on myosin II contraction. Finally, we provide evidence that while the Urp1/2 signaling is functioning during larval growth, it is dispensable for embryonic development. Taken together, our results show that Urp1/2 signaling is required in larvae to promote correct vertebral body axis, most likely by regulating muscle tone.