Spine Elongation Research Articles

Magnetic resonance imaging evaluation of the cerebellar tonsil position before and after posterior spinal fusion in adolescent idiopathic scoliosis.

Chiari malformation type I(CM-I) is one of the most common neurological malformations observed in patients with adolescent idiopathic scoliosis (AIS). It remains uncertain whether AIS patients without neurological symptoms require CM-I decompression before undergoing spinal corrective surgery to prevent cerebellar tonsil herniation and potential neurological complications. This study aims to assess variations in the position of the cerebellar tonsil after posterior spinal fusion (PSF) in neurologically intact patients with AIS. We retrospectively evaluated 40 patients with AIS who underwent posterior spinal fusion (PSF) without neurological symptoms. Sagittal hindbrain MRIs were performed before and after spinal surgery. The cerebellar tonsil's position relative to the foramen magnum was measured using the method described by Aboulezz (J Comput Assist Tomogr 1985). We assessed variations in the cerebellar tonsil position concerning spinal correction and elongation after PSF. The average preoperative magnitude of the scoliotic curve was 53.15 degrees (SD 10.46 degrees), and that of thoracic kyphosis was 35.42 degrees (SD 12.38 degrees). In the immediate postoperative period, the average magnitudes were 7.45 degrees (SD 7.33 degrees) and 27.87 degrees (SD 9.03 degrees), respectively. The average correction achieved with PSF was 86% in the coronal plane (p < 0.00001). The average length of the spine in the coronal plane was 44.5cm (SD 5.25cm) preoperatively and 48.27cm (SD 4.40cm) postoperatively (p < 0.00001). The average length of the vertebral column in the sagittal plane was 50.87cm (SD 4.47cm) preoperatively and 55.13cm (SD 3.27cm) postoperatively (p < 0.00001). No significant difference was observed in the position of the cerebellar tonsil in the measurements taken before and after spinal deformity correction (p = 0.6042). In 10 out of 40 patients, caudal displacement of the cerebellar tonsil was observed after PSF. In 28 patients, no variation in the position of the cerebellar tonsil was observed, and in 2, cephalic displacement was noted. In AIS patients with a normal position of the cerebellar tonsil undergoing posterior spinal fusion, there is no significant change in their positionafter surgery. Our analysis did not reveal any correlation between curve correction, spine elongation, and variations in the cerebellar tonsil position. The position of the cerebellar tonsil remained largely unchanged after PSF in AIS patients without neurological symptoms. Further studies would be necessary to determine whether surgical decompression is required in asymptomatic patients with CM-I before undergoing surgery to correct spinal deformity.

MARCKS and PI(4,5)P2 reciprocally regulate actin-based dendritic spine morphology.

Myristoylated, alanine-rich C-kinase substrate (MARCKS) is an F-actin and phospholipid binding protein implicated in numerous cellular activities, including the regulation of morphology in neuronal dendrites and dendritic spines. MARCKS contains a lysine-rich effector domain that mediates its binding to plasma membrane phosphatidylinositol-4,5-biphosphate (PI(4,5)P2) in a manner controlled by PKC and calcium/calmodulin. In neurons, manipulations of MARCKS concentration and membrane targeting strongly affect the numbers, shapes, and F-actin properties of dendritic spines, but the mechanisms remain unclear. Here, we tested the hypothesis that the effects of MARCKS on dendritic spine morphology are due to its capacity to regulate the availability of plasma membrane PI(4,5)P2. We observed that the concentration of free PI(4,5)P2 on the dendritic plasma membrane was inversely proportional to the concentration of MARCKS. Endogenous PI(4,5)P2 levels were increased or decreased, respectively, by acutely overexpressing either phosphatidylinositol-4-phosphate 5-kinase (PIP5K) or inositol polyphosphate 5-phosphatase (5ptase). PIP5K, like MARCKS depletion, induced severe spine shrinkage; 5ptase, like constitutively membrane-bound MARCKS, induced aberrant spine elongation. These phenotypes involved changes in actin properties driven by the F-actin severing protein cofilin. Collectively, these findings support a model in which neuronal activity regulates actin-dependent spine morphology through antagonistic interactions of MARCKS and PI(4,5)P2.

Ultrasonographic assessment of magnetic growing rods overestimates the lengthening of the thoracic spine compared to radiographs in early-onset scoliotic patients.

Magnetic growing rods (MGRs) are one of the most common procedures to treat early-onset scoliosis (EOS). Radiographic examinations (X-ray) or ultrasonographic (US) assessments are used to evaluate the lengthening of the rods. X-ray exposes patients to radiation, while the US has not been validated and may be affected by the radiologist's ability to assess elongation. The research question of the present study is to compare the difference between US and X-ray growth assessments in EOS patients treated with MGRs. The study enrolled 65 patients consecutively from July 2011 to July 2022. Noninvasive lengthening was performed every fourmonths, and X-ray follow-up was performed at different intervals. An experienced radiologist assessed the mean US rod elongation per session. The mean elongation/session of T2-T12 and T2-S1 was calculated, and the results were compared using an independent t-test. The mean age at operation was 8.8 ± 2years, and the mean follow-up was four± twoyears. The average rod elongation assessed by the US was 3.1 ± 0.1mm. The average rod elongation evaluated by X-ray was 1.2 ± 2.9mm (T2-T12) and 1.8 ± 1.9mm (T2-S1). The difference between the values measured by US and X-ray was statistically significant in the T2-T12 group (p < 0.05) and not significant in the T2-S1 group (p = 0.34). This is the most extensive single-center study comparing US and X-ray data for MGRs in EOS patients. US overestimates thoracic spine elongation compared to X-ray. US elongation analysis could be appropriate in long thoracolumbar curves.

Epiphanes brachionus spinosa from a temporary habitat in the Chihuahuan Desert: Morphological response to Asplanchna and control of sexual reproduction

Abstract The rotifer Epiphanes brachionus spinosa occurs in shallow temporary waters with hydroperiods up to several months in the Chihuahuan Desert (U.S.A. and Mexico). Clonal populations from one such habitat were initiated from stem females hatched from fertilised resting eggs in flooded dried sediment, and cultured with the alga Cryptomonas erosa at 19°C in a photoperiod (L:D 16:8). Experiments show that the rotifer has: (1) a morphological response to the predatory rotifer Asplanchna, with which it can co‐occur; and (2) an early and constant propensity for sex and resting‐egg production during population development. Stem females, and females from later generations, have two posterior spines. Measurements of live juveniles and adults indicate that spine length increases isometrically during postnatal growth. Presence of live Asplanchna brightwellii, or its kairomone in Asplanchna‐conditioned medium, significantly increase spine length. In one clone, spine lengths of juvenile Epiphanes from cultures with or without live Asplanchna were, respectively, c. 40 and c. 27 μm. In that clone, spine lengths of adult Epiphanes in cultures with or without Asplanchna kairomone were, respectively, c. 54 and c. 37 μm. In another clone, these spine lengths were, respectively, c. 44 and c. 36 μm. Asplanchna‐induced spine elongation may act as a mechanical defence against capture and ingestion by the predator. Sexual reproduction in E. brachionus spinosa populations is initiated soon after populations develop from stem females and then continues at a rate allowing both population growth by female parthenogenesis and production of resting eggs. Resting eggs hatched after 6–12 days at 19°C. Stem females were amictic (producing daughters parthenogenetically) but produced some daughters that were mictic (producing haploid males parthenogenetically or fertilised resting eggs). In subsequent generations tested 2–7 weeks after hatching of stem females, amictic females from three clonal populations produced similar proportions of mictic daughters (mean c. 0.25) when cultured singly in large volumes (15 and 40 ml) or a small one (1.5 ml). Mictic‐female production is probably automatic and controlled by an endogenous mechanism, rather than specifically induced by crowding or some other environmental factor. Early and continuous sexual reproduction assures production of resting eggs throughout short and unpredictable hydroperiods.

Morphometric analysis of adult Hippopotamus forelimb bones

Background: Understanding the adaptative changes in bone shapes among animals involves studying bone morphology. We examined adult hippopotamus (Hippopotamus amphibius)forelimb bones at the anatomy laboratory of Patuakhali Science and Technology University, Bangladesh. Samples were collected from Rangpur Recreation Park and Zoo between September 2021 and July 2022. Methods: Bones were processed by removing mud and boiled with water. Subsequently, hydrogen peroxide was used for one and a half hours to remove any remaining muscular tissues from the bones. Following this, the bones were air-dried under sunlight for a month. Measurements of key parameters including length, height, width, circumference, and weight were obtained using calibrated instruments, thereby ensuring precision. Results:The scapula displayed a pronounced and elongated spine – the spina scapulae – that demarcated the lateral surface into two distinct fossae: the supraspinous fossa and the infraspinous fossa. The distal expansion of the spine, known as the acromion process, consisted of the fused hamate process and suprahamate process. The head of humerus was round and featured two undivided tubercles: the greater or major and the lesser tubercle. On the medial surface, a small and shallow radial fossa was observed, while on the opposite side, a large and deep olecranon fossa was present. The proximal surface of the radius head exhibited concave fovea capitis radii, which articulated with the lateral condyle of the humerus. The shaft of the radius was slightly expanded in the cranio-caudal direction. Similarly, the shaft of the ulnahad a somewhat triangular shape, resembling the shape of the radius shaft. Medially, it had a convex facet that articulated with the radius, and cranially, the interosseous space between the radius and ulna was longer than the caudal view. Conclusions: The unique anatomical features and morphometric measurements of the forelimb bones in hippos can be beneficial for identification, radiographic interpretation, and forensic investigation. Furthermore, this study provides essential guidelines and insights for understanding appropriate anatomical parameters.

Virtual Reality for Upper Limb Rehabilitation in Patients With Obstetric Brachial Palsy: Systematic Review and Meta-Analysis of Randomized Controlled Trials.

Obstetric brachial palsy (OBP) is a pathology caused by complications during childbirth because of cervical spine elongation, affecting the motor and sensory innervation of the upper limbs. The most common lesion occurs on the C5 and C6 nerve branches, known as Erb-Duchenne palsy. The least common lesion is when all nerve roots are affected (C5-T1), which has the worst prognosis. Virtual reality (VR) is commonly used in neurological rehabilitation for the evaluation and treatment of physical deficits. This systematic review aims to assess the efficacy of VR in the rehabilitation of upper limb function in patients with OBP. A search was performed according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) 2020 guidelines in several scientific databases-PubMed, Web of Science, PEDro, Cochrane, MEDLINE, Scopus, and CINAHL-without language or date restrictions and including articles published up to April 2023. The inclusion criteria were established according to the population, intervention, comparison, outcome, and study (PICOS) design framework: children aged <18 years diagnosed with OBP, VR therapy used in addition to conventional therapy or isolated, VR therapy compared with conventional therapy, outcomes related to OBP rehabilitation therapy, and randomized controlled trials (RCTs). The PEDro scale was used to assess the methodological quality of the RCTs, and the Cochrane Collaboration tool was used to assess the risk of bias. The Review Manager statistical software (version 5.4; The Cochrane Collaboration) was used to conduct the meta-analysis. The results were synthesized through information extraction and presented in tables and forest plots. In total, 5 RCTs were included in this systematic review, with 3 (60%) providing information for the meta-analysis. A total of 138 participants were analyzed. All the studies used semi-immersive or nonimmersive VR systems. The statistical analysis showed no favorable results for all outcomes except for the hand-to-mouth subtest of the Mallet scoring system (functional activity; standardized mean difference -0.97, 95% CI -1.67 to -0.27; P=.007). The evidence for the use of VR therapy for upper limb rehabilitation outcomes in patients with OBP was insufficient to support its efficacy and strongly recommend its use. Nevertheless, scientific literature supports the use of VR technologies for rehabilitation as it provides several advantages, such as enhancing the patient's motivation, providing direct feedback, and focusing the patient's attention during the intervention. Thus, the use of VR for upper limb rehabilitation in patients with OBP is still in its first stages. Small sample sizes; limited long-term analysis; lack of testing of different doses; and absence of International Classification of Functioning, Disability, and Health-related outcomes were present in the included RCTs, so further research is needed to fully understand the potential of VR technologies as a therapeutic approach for patients with OBP. PROSPERO CRD42022314264; https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=314264.

Transcriptome analysis reveals the molecular basis of anti‐predation defence in Daphnia pulex simultaneously responding to Microcystis aeruginosa

Abstract1. The influence of cyanobacteria on interspecies interactions has received growing attention as a predictor of aquatic ecosystem function. It is well‐known that cyanobacteria greatly affect predator‐induced phenotypic plasticity in planktonic animals. However, the underlying molecular mechanism remains unclear.2. Here, we used Daphnia pulex as a model organism for inducible defence, examining its morphological and life‐history responses to fish kairomone while feeding on 100% Chlorella pyrenoides, or while feeding on 70% Chlorella and either microcystin‐producing or ‐free Microcystis aeruginosa, separately. Transcriptome profiles of kairomone‐exposed D. pulex fed different types of food were detected using RNA‐seq. How the differentially expressed genes and pathways identified are responsible for the altered adaptive traits under Microcystis stress was discussed.3. Daphnia pulex fed 100% Chlorella matured at a smaller body size, elongated tail spine length, and produced smaller offspring as adaptive morphological and reproductive responses to fish kairomone. These anti‐predation defences entailed a cost in decreased somatic growth rate. Microcystis stress caused defence trade‐offs in both morphology and reproduction: reduction of body size at maturity was stronger whereas tail spine elongation was unchanged or inhibited. Given that reproductive investment was reduced overall in Daphnia exposed to fish kairomones, there was a trade‐off for unchanged offspring size by reducing offspring number in Daphnia fed Microcystis. Defence‐induced costs to growth were increased by Microcystis exposure.4. Transcriptome analysis revealed that neuronal signals including acetylcholine and glutamate signalling implicated in kairomone reception and/or transmission exhibited stronger responses under Microcystis stress. Cuticle development associated with the biosynthesis of wax esters and chitin, modification of lipo‐chitin saccharides, and the stability of collagen triple helix apparently participated in the morphological changes. The arachidonic acid pathway and biosynthesis of cholesterol and steroid hormones mediated altered reproductive performance. In addition, metabolic processes such as detoxification, food assimilation, lysosome dysfunction and apoptosis activation were involved in the survival and growth of Daphnia, which may contribute to the increased defence‐induced cost in growth when fed Microcystis.5. Taken together, these findings advance our understanding of the molecular mechanisms underlying anti‐predation defensive responses by Daphnia to cyanobacterial stress. This work also provides a reference for further exploring the functional genes that mediate zooplankton–fish coevolution dynamics under eutrophic conditions.

Effects of a microgravity SkinSuit on lumbar geometry and kinematics

PurposeAstronauts returning from long ISS missions have demonstrated an increased incidence of lumbar disc herniation accompanied by biomechanical and morphological changes associated with spine elongation. This research describes a ground-based study of the effects of an axial compression countermeasure Mk VI SkinSuit designed to reload the spine and reduce these changes before return to terrestrial gravity.MethodsTwenty healthy male volunteers aged 21–36 without back pain participated. Each lay overnight on a Hyper Buoyancy Flotation (HBF) bed for 12 h on two occasions 6 weeks apart. On the second occasion participants donned a Mk VI SkinSuit designed to axially load the spine at 0.2 Gz during the last 4 h of flotation. Immediately after each exposure, participants received recumbent MRI and flexion–extension quantitative fluoroscopy scans of their lumbar spines, measuring differences between spine geometry and intervertebral kinematics with and without the SkinSuit. This was followed by the same procedure whilst weight bearing. Paired comparisons were performed for all measurements.ResultsFollowing Mk VI SkinSuit use, participants evidenced more flexion RoM at L3–4 (p = 0.01) and L4–5 (p = 0.003), more translation at L3–4 (p = 0.02), lower dynamic disc height at L5–S1 (p = 0.002), lower lumbar spine length (p = 0.01) and greater lordosis (p = 0.0001) than without the Mk VI SkinSuit. Disc cross-sectional area and volume were not significantly affected.ConclusionThe MkVI SkinSuit restores lumbar mobility and lordosis following 4 h of wearing during hyper buoyancy flotation in a healthy control population and may be an effective countermeasure for post space flight lumbar disc herniation.

Performance of Daphnia simultaneously exposed to nitrite and predation risk: Reduced nitrite tolerance and aggravated predation-induced miniaturization

Nitrogenous pollutants derived from human activities not only pose direct risk on aquatic organisms but may also indirectly endanger the stability of interspecific relations. To date, the effects of the nitrogen-containing pollutants on the induced defense remain unclear. Here, we aim to investigate the induced defense of an aquatic keystone species, Daphnia pulex, which responds to predation risk under nitrite pollution at environmentally relevant concentrations and simultaneously evaluate the effects of their induced defenses on nitrite tolerance. Results showed that increasing nitrite significantly reduced the survival time of D. pulex and posed severe reproductive toxicity, consequently reducing the offspring and broods. In the morphological defensive responses, early nitrite exposure interfered with the spine elongation, but the relative spine length induced by the predation risk was unaffected by the nitrite concentrations with exposure time prolonged, although high-dose nitrite inhibited the spine elongation and the increase of the body size. The integration of biomarker response index analyses further indicated that the reproductive capacity was more seriously impaired than the morphology and the survival. Moreover, the sensitivity analyses of growth and reproduction indicated that predation risk significantly reduced Daphnia's tolerance to nitrite. Conclusively, these findings highlight that long-term nitrite exposure exacerbates the predator-induced miniaturization of zooplanktons, and predation risk also reduces their tolerance to nitrite, which provides new insights into the performance changes of zooplanktons exposed to pollutants under predation risk and the vulnerability of predator–prey interspecific relationships in polluted environments.

Activation of the 5-HT7 receptor and MMP-9 signaling module in the hippocampal CA1 region is necessary for the development of depressive-like behavior.

Major depressive disorder is a complex disease resulting from aberrant synaptic plasticity that may be caused by abnormal serotonergic signaling. Using a combination of behavioral, biochemical, and imaging methods, we analyze 5-HT7R/MMP-9 signaling and dendritic spine plasticity in the hippocampus in mice treated with the selective 5-HT7R agonist (LP-211) and in a model of chronic unpredictable stress (CUS)-induced depressive-like behavior. We show that acute 5-HT7R activation induces depressive-like behavior in mice in an MMP-9-dependent manner and that post mortem brain samples from human individuals with depression reveal increased MMP-9 enzymatic activity in the hippocampus. Both pharmacological activation of 5-HT7R and modulation of its downstream effectors as a result of CUS lead to dendritic spine elongation and decreased spine density in this region. Overall, the 5-HT7R/MMP-9 pathway is specifically activated in the CA1 subregion of the hippocampus during chronic stress and is crucial for inducing depressive-like behavior.

Spines and baskets in apex predatory sea scorpions uncover unique feeding strategies using 3D-kinematics

SummaryMegalograptidae and Mixopteridae with elongate, spinose prosomal appendages are unique early Palaeozoic sea scorpions (Eurypterida). These features were presumably used for hunting, an untested hypothesis. Here, we present 3D model-based kinematic range of motion (ROM) analyses of Megalograptus ohioensis and Mixopterus kiaeri and compare these to modern analogs. This comparison confirms that the eurypterid appendages were likely raptorial, used in grabbing and holding prey for consumption. The Megalograptus ohioensis model illustrates notable Appendage III flexibility, indicating hypertrophied spines on Appendage III may have held prey, while Appendage II likely ripped immobilized prey. Mixopterus kiaeri, conversely, constructed a capture basket with Appendage III, and impaled prey with Appendage II elongated spines. Thus, megalograptid and mixopterid frontalmost appendages constructed a double basket system prior to moving dismembered prey to the chelicerae. Such 3D kinematic modeling presents a more complete understanding of these peculiar euchelicerates and highlights their possible position within past ecosystems.

Deafening‐induced rapid changes to spine synaptic connectivity in the adult avian vocal basal ganglia

The basal ganglia have been implicated in auditory-dependent vocal learning and plasticity in human and songbirds, but the underlying neural phenotype remains to be clarified. Here, using confocal imaging and three-dimensional electron microscopy, we investigated striatal structural plasticity in response to hearing loss in Area X, the avian vocal basal ganglia, in adult male zebra finch (Taeniopygia guttata). We observed a rapid elongation of dendritic spines, by approximately 13%, by day 3 after deafening, and a considerable increase in spine synapse density, by approximately 61%, by day 14 after deafening, compared with the controls with an intact cochlea. These findings reveal structural sensitivity of Area X to auditory deprivation and suggest that this striatal plasticity might contribute to deafening-induced changes to learned vocal behavior.

Predator-induced allometric changes in the tail spine length ofDaphnia: a distinct resource allocation strategy

AbstractUnderstanding resource allocation strategies underlying inducible defense is a challenging scientific issue, because of the difficulty in measuring resource allocations of defensive traits. We examined allometric changes to evaluate resource allocation strategies on the tail spine of Daphnia within and between species and further explore the allometric changes at different developmental stages and their relationship with growth and reproduction. We found that four Daphnia species (Daphnia magna, Daphnia sinensis, Daphnia galeata and Daphnia mitsukuri) can perform significant inducible defensive responses when exposed to fish kairomone. Different from the other Daphnia species, D. mitsukuri significantly enhanced the allometric slope of its tail spine when exposed to fish kairomone. We also found that allometric changes among different D. mitsukuri clones are significant in adult individuals. Furthermore, the allometric changes show a significant negative interaction with individual growth, indicating that a trade-off may exist between the resource allocations of tail spine elongation and growth. This study highlights the species-specific allometric changes in tail spine elongation and provides an explanation for this from resource allocations.

Growth pattern of the siliceous skeletons of living Spumellaria (Radiolaria) from the Kuroshio Current, offshore southwestern Shikoku Island, Japan

Experimental culture studies of living radiolarians experience many difficulties because radiolarians are too sensitive to be maintained alive in artificial conditions. We here developed an improved experimental protocol in order to detect newly-formed parts of the polycystine radiolarian skeletons after they were labeled with fluorescent markers. Living samples were collected from surface seawater of the Kuroshio Current offshore from Kashiwajima Island, Kochi Prefecture on the island of Shikoku, Japan. The taxonomic composition of the Kashiwajima radiolarian samples varied markedly across the seasons and sampling sites. Spumellaria were usually abundant in samples collected near Kashiwajima, and had high diversity in shell morphology. Here, we performed experimental studies on living spumellarian radiolarians to clarify their siliceous skeletogenesis. Our culture-based research on spumellarians provided the following results.(A) The pattern of silica deposition on the skeleton of Spongaster tetras tetras varies depending on the growth stage. Three ontogenetic stages were identified: (1) young, (2) progressively-growing and (3) fully-grown. Furthermore, novel varied types of skeletal growth modes were determined as follows: (i) rapid growth on the outermost shell with enlargement of shell size and (ii) internal deposition on skeletal components without change in shell size. From measurements of the growth rate of cultured radiolarians, it is assumed that S. tetras tetras cell has at least a month-long life cycle.(B) Spherical spumellarians have their own shell-forming strategy that permits additional silicogenesis while maintaining the taxonomically-specific shape of their shell; the meshwork of their shell surface consists of polygonal-shaped pore-frames formed by heterogeneous patterns of added silica.Our direct observation with fluorescence markers detected a skeletogenesis process of Haliommilla capillacea possessing a fragile spherical shell. We thus confirm the bridge-growth hypothesis for morphogenesis of the polygonal frame as proposed in previous studies. Spongosphaera streptacantha, having extremely long spines, exhibited a special growth pattern of spine elongation in a centrifugal direction, without a change in width. This was achieved by a particular temporal pattern of silicification characterized by an alternating pattern of patchy addition of new silica on the entire part of each blade from the base to the tip. Moreover, a thin layer of new silica was added by a flowing deposition along the edge of the spine. Based on these culture-based studies using living radiolarians, we conclude that Spumellaria control and maintain a particular shell shape by regulating where silicification takes place on the skeleton, particularly depending on the growth stage.

Intraspecific variation in sensitivity to food availability and temperature-induced phenotypic plasticity in the rotifer Keratella cochlearis.

Organisms with wide environmentally induced morphological plasticity and cosmopolitan distribution, e.g. the common freshwater rotifer Keratella cochlearis, are ideal models to study the evolution of plastic polymorphisms and the capacity of zooplankton to adapt to local selection conditions. We investigated population-level differences (population-by-environment interaction) in sensitivity to food availability and temperature-induced phenotypic plasticity between two clones of K. cochlearis isolated from neighboring populations in Ruidera Natural Park (Spain) with different trophic statuses: Tinaja lake (mesotrophic) and Cueva Morenilla lake (eutrophic). Using common-garden experiments, each clone proved to have a different sensitivity to food availability, with substantial phenotypic differences between them. When rotifers grew at moderate temperature (15.6°C), low food levels were more efficiently used by the Tinaja versus Cueva Morenilla clone, whereas high food levels were more efficiently used by the Cueva Morenilla versus Tinaja clone. The posterior spine was much longer and the lorica wider in the Tinaja versus Cueva Morenilla clone, with no difference in lorica length. Phylogenetic analysis based on cytochrome c oxidase subunit I (COI) gene sequences showed that the two populations have the same haplotype. This is the first study to show possible local adaptation by a rotifer species to habitats that consistently differ in food availability. We also detected an intriguing deviation from the expected negative relationship between posterior spine length and temperature. Our experimental results indicate that intermediate temperatures may activate the gene responsible for spine elongation in K. cochlearis This suggests that rotifers in nature could use water temperature as proxy signal of a change in predation risk before defense is needed.

Fish kairomones induce spine elongation and reduce predation in marine crab larvae.

Specialized defense strategies are induced in zooplankton upon detection of predator chemical cues or kairomones. These defenses are well-described for freshwater zooplankters, with morphological defenses being particularly striking, but few studies have reported kairomone-induced morphological defenses in marine zooplankton. Here, we compare morphological responses to kairomones in the larvae of two marine crab species, estuarine mud crabs (Rhithropanopeus harrisii) and Asian shore crabs (Hemigrapsus sanguineus). When reared in the presence of fish kairomones, spine length increased by 2-3% in larval R.harrisii, while no morphological changes were identified in H.sanguineus. In subsequent feeding assays with a co-occurring fish predator (Atlantic silversides, Menidia menidia), consumption of R.harrisii was lower on larvae that had been reared with kairomones. In addition, we found that broods with smaller larvae are more likely to exhibit increases in spine length after kairomone exposure. Hence, the observed morphological response is likely influenced by larval size.

Functional and Radiographic Outcomes Following Growth-Sparing Management of Early-Onset Scoliosis.

In this study, we sought to evaluate radiographic, functional, and quality-of-life outcomes of patients who have completed growth-sparing management of early-onset scoliosis. This prospective study involved patients with early-onset scoliosis who underwent growth-sparing treatment and either "final" fusion or observation for ≥2 years since the last lengthening procedure. Demographics, radiographic parameters, pulmonary function test (PFT) values, and scores of patient-reported assessments (Early-Onset Scoliosis Questionnaire [EOSQ] and Scoliosis Research Society [SRS]-30) were obtained. At the most recent follow-up, patients performed 2 additional functional outcome tests: step-activity monitoring and a treadmill exercise-tolerance test. Twelve patients were evaluated as "graduates" of growth-sparing management of early-onset scoliosis (mean of 37 months since the most recent surgery). The major scoliosis curve measurement averaged 88° before treatment and 47° at the most recent follow-up. T1-S1 height increased from a mean of 22.3 cm to 34.7 cm and T1-T12 height, from 13.3 to 22.3 cm. At the most recent follow-up, the mean forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) as a percentage of the predicted volume were 52.1% and 55.3%, respectively, and were essentially unchanged from the earliest PFT that patients could perform (FEV1 = 53.8% of predicted and FVC = 53.5% of predicted). There was no difference between graduates and controls with respect to activity time or total steps in step-activity monitoring, and in the exercise-tolerance test, graduates walked at the same speed but at a higher heart rate and at a significantly higher (p <0.001) VO2 cost (rate of oxygen consumed per distance traveled). The EOSQ mean score was 102.2 of a possible 120 points, and the SRS mean score was 4.1 of a possible 5 points. A realistic long-term goal for the management of early-onset scoliosis appears to be spine elongation and maintenance of pulmonary function at a level that is no less than the percentage of normal at initial presentation. Functional testing and patient-reported outcomes at a mean of 3 years from the last surgery suggest that activity levels were generally equal to those of controls but required greater physiologic demand. General health and physical function outcomes revealed continued impairment in these domains. Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Regulation of spinogenesis in mature Purkinje cells via mGluR/PKC-mediated phosphorylation of CaMKIIβ

Dendritic spines of Purkinje cells form excitatory synapses with parallel fiber terminals, which are the primary sites for cerebellar synaptic plasticity. Nevertheless, how density and morphology of these spines are properly maintained in mature Purkinje cells is not well understood. Here we show an activity-dependent mechanism that represses excessive spine development in mature Purkinje cells. We found that CaMKIIβ promotes spine formation and elongation in Purkinje cells through its F-actin bundling activity. Importantly, activation of group I mGluR, but not AMPAR, triggers PKC-mediated phosphorylation of CaMKIIβ, which results in dissociation of the CaMKIIβ/F-actin complex. Defective function of the PKC-mediated CaMKIIβ phosphorylation promotes excess F-actin bundling and leads to abnormally numerous and elongated spines in mature IP3R1-deficient Purkinje cells. Thus, our data suggest that phosphorylation of CaMKIIβ through the mGluR/IP3R1/PKC signaling pathway represses excessive spine formation and elongation in mature Purkinje cells.

Synaptic Remodeling Depends on Signaling between Serotonin Receptors and the Extracellular Matrix

Rewiring of synaptic circuitry pertinent to memory formation has been associated with morphological changes in dendritic spines and with extracellular matrix (ECM) remodeling. Here, we mechanistically link these processes by uncovering a signaling pathway involving the serotonin 5-HT7 receptor (5-HT7R), matrix metalloproteinase 9 (MMP-9), the hyaluronan receptor CD44, and the small GTPase Cdc42. We highlight a physical interaction between 5-HT7R and CD44 (identified as an MMP-9 substrate in neurons) and find that 5-HT7R stimulation increases local MMP-9 activity, triggering dendritic spine remodeling, synaptic pruning, and impairment of long-term potentiation (LTP). The underlying molecular machinery involves 5-HT7R-mediated activation of MMP-9, which leads to CD44 cleavage followed by Cdc42 activation. One important physiological consequence of this interaction includes an increase in neuronal outgrowth and elongation of dendritic spines, which might have a positive effect on complex neuronal processes (e.g., reversal learning and neuronal regeneration).

CD44: a novel synaptic cell adhesion molecule regulating structural and functional plasticity of dendritic spines.

Synaptic cell adhesion molecules regulate signal transduction, synaptic function, and plasticity. However, their role in neuronal interactions with the extracellular matrix (ECM) is not well understood. Here we report that the CD44, a transmembrane receptor for hyaluronan, modulates synaptic plasticity. High-resolution ultrastructural analysis showed that CD44 was localized at mature synapses in the adult brain. The reduced expression of CD44 affected the synaptic excitatory transmission of primary hippocampal neurons, simultaneously modifying dendritic spine shape. The frequency of miniature excitatory postsynaptic currents decreased, accompanied by dendritic spine elongation and thinning. These structural and functional alterations went along with a decrease in the number of presynaptic Bassoon puncta, together with a reduction of PSD-95 levels at dendritic spines, suggesting a reduced number of functional synapses. Lack of CD44 also abrogated spine head enlargement upon neuronal stimulation. Moreover, our results indicate that CD44 contributes to proper dendritic spine shape and function by modulating the activity of actin cytoskeleton regulators, that is, Rho GTPases (RhoA, Rac1, and Cdc42). Thus CD44 appears to be a novel molecular player regulating functional and structural plasticity of dendritic spines.