Posterior Axis Research Articles

Comparative transcriptomics of sympatric species of coral reef fishes (genus: Haemulon).

BackgroundCoral reefs are major hotspots of diversity for marine fishes, yet there is still ongoing debate on the mechanisms that promote divergence in these rich ecosystems. Our understanding of how diversity originates in this environment could be enhanced by investigating the evolutionary dynamics of closely related fishes with overlapping ranges. Here, we focus on grunts of the genus Haemulon, a group of coral reef fishes with 15 species in the Western Atlantic, 11 of which are syntopic.MethodsWild fish samples from three sympatric species of the Caribbean: Haemulon flavolineatum, H. carbonarium and H. macrostomum, were collected while SCUBA diving. RNA was extracted from livers, and the transcriptomes were assembled and annotated to investigate positive selection (Pairwise dN/dS) and patterns of gene expression between the three species.ResultsPairwise dN/dS analyses showed evidence of positive selection for genes associated with immune response, cranial morphology and formation of the anterior–posterior axis. Analyses of gene expression revealed that despite their sympatric distribution, H. macrostomum showed upregulation of oxidation-reduction machinery, while there was evidence for activation of immune response in H. carbonarium.DiscussionOverall, our analyses suggest closely related grunts show important differences in genes associated with body shape and feeding morphology, a result in-line with previous morphological studies in the group. Further, despite their overlapping distribution they interact with their environment in distinct fashions. This is the largest compendium of genomic information for grunts thus far, representing a valuable resource for future studies in this unique group of coral reef fishes.

Multimodal Parcellations and Extensive Behavioral Profiling Tackling the Hippocampus Gradient.

The hippocampus displays a complex organization and function that is perturbed in many neuropathologies. Histological work revealed a complex arrangement of subfields along the medial-lateral and the ventral-dorsal dimension, which contrasts with the anterior-posterior functional differentiation. The variety of maps has raised the need for an integrative multimodal view. We applied connectivity-based parcellation to 1) intrinsic connectivity 2) task-based connectivity, and 3) structural covariance, as complementary windows into structural and functional differentiation of the hippocampus. Strikingly, while functional properties (i.e., intrinsic and task-based) revealed similar partitions dominated by an anterior-posterior organization, structural covariance exhibited a hybrid pattern reflecting both functional and cytoarchitectonic subdivision. Capitalizing on the consistency of functional parcellations, we defined robust functional maps at different levels of partitions, which are openly available for the scientific community. Our functional maps demonstrated a head-body and tail partition, subdivided along the anterior-posterior and medial-lateral axis. Behavioral profiling of these fine partitions based on activation data indicated an emotion-cognition gradient along the anterior-posterior axis and additionally suggested a self-world-centric gradient supporting the role of the hippocampus in the construction of abstract representations for spatial navigation and episodic memory.

Vitelline membrane proteins promote left-sided nodal expression after neurula rotation in the ascidian, Halocynthia roretzi

Stereotyped left–right asymmetry both in external and internal organization is found in various animals. Left-right symmetry is broken by the neurula rotation in the ascidian, Halocynthia roretzi. Neurula embryos rotate along the anterior–posterior axis in a counterclockwise direction, and the rotation stops when the left side of the embryo is oriented downwards, resulting in contact of the left-side epidermis with the vitelline membrane at the bottom of perivitelline space. Then, such contact induces the expression of nodal and its downstream Pitx2 gene in the left-side epidermis. Vitelline membrane is required for the promotion of nodal expression. Here, we showed that a chemical signal from the vitelline membrane promotes nodal gene expression, but mechanical stimulus at the point of contact is unnecessary since the treatment of devitellinated neurulae with an extract of the vitelline membrane promoted nodal expression on both sides. The signal molecules are already present in the vitelline membranes of unfertilized eggs. These signal molecules are proteins but not sugars. Specific fractions in gel filtration chromatography had the nodal promoting activity. By mass spectrometry, we selected 48 candidate proteins. Proteins that contain both a zona pellucida (ZP) domain and epidermal growth factor (EGF) repeats were enriched in the candidates of the nodal inducing molecules. Six of the ZP proteins had multiple EGF repeats that are only found in ascidian ZP proteins. These were considered to be the most viable candidates of the nodal-inducing molecules. Signal molecules are anchored to the entire vitelline membrane, and contact sites of signal-receiving cells are spatially and mechanically controlled by the neurula rotation. In this context, ascidians are unusual with respect to mechanisms for specification of the left-right axis. By suppressing formation of epidermis monocilia, we also showed that epidermal cilia drive the neurula rotation but are dispensable for sensing the signal from the vitelline membrane.

Rotational Malalignment of the Knee Extensor Mechanism: Defining Rotation of the Quadriceps and Its Role in the Spectrum of Patellofemoral Joint Instability.

Background:Osseous rotational malalignment of the lower limb is widely accepted as a factor contributing to patellofemoral instability, particularly in pediatric patients. Patellar instability occurs when the lateral force vector generated by the quadriceps exceeds the restraints provided by osseous and soft-tissue anatomy. The anatomy and activation of the quadriceps are responsible for the force applied across the patellofemoral joint, which has previously been measured using the quadriceps (Q)-angle. To our knowledge, the contribution of the quadriceps anatomy in generating a force vector in the axial plane has not previously been assessed. The primary aim of this study was to introduce the quadriceps torsion angle, a measure of quadriceps rotational alignment in the juvenile population. The secondary aims of this study were to determine the inter-assessor and intra-assessor reliability of the quadriceps torsion angle in the juvenile population and to investigate whether a large quadriceps torsion angle is a classifier of patellar dislocator group membership in a mixed cohort of patellar dislocators and typically developing controls.Methods:Participants between the ages of 8 and 19 years were recruited as either controls or recurrent patellar dislocators. A total of 58 knees in both groups were assessed from magnetic resonance imaging scans of the entire lower limbs. Axial cuts midway between the superior aspect of the femoral head and the articular surface of the medial femoral condyle were used to calculate the proximal reference for the quadriceps torsion angle. The quadriceps torsion angle was defined as the angle between the line connecting the anterior aspect of the sartorius and the junction of the anterior and posterior compartments at the lateral intermuscular septum and the posterior condylar axis line. Inter-assessor reliability was calculated using the intraclass correlation coefficient. The relationship between the quadriceps torsion angle and the femoral torsion was assessed in the entire cohort. These values were compared between the control group and the dislocator group to determine if the raw values or an interplay between the 2 factors played a role in the pathoanatomy of recurrent patellofemoral dislocation.Results:The quadriceps torsion angle was a reproducible assessment in both inter-assessor and intra-assessor reliability analyses. A moderate positive correlation (r = 0.624; p < 0.01) was found between the femoral torsion and the quadriceps torsion angle. Although the quadriceps torsion angle was a fair classifier of patellar dislocation group membership, femoral torsion was not.Conclusions:This study has quantified the rotational alignment of the extensor mechanism using the quadriceps torsion angle. The measurement is shown to be reliable and reproducible and a fair classifier of patellofemoral instability.Clinical Relevance:This article introduces an objective measure of soft-tissue rotational malalignment in the pathogenesis of recurrent patellar dislocation.

What are the roles of retinoids, other morphogens, and Hox genes in setting up the vertebrate body axis?

SummaryThis article is concerned with the roles of retinoids and other known anterior–posterior morphogens in setting up the embryonic vertebrate anterior–posterior axis. The discussion is restricted to the very earliest events in setting up the anterior–posterior axis (from blastula to tailbud stages in Xenopus embryos). In these earliest developmental stages, morphogen concentration gradients are not relevant for setting up this axis. It emerges that at these stages, the core patterning mechanism is timing: BMP‐anti BMP mediated time space translation that regulates Hox temporal and spatial collinearities and Hox‐Hox auto‐ and cross‐ regulation. The known anterior–posterior morphogens and signaling pathways––retinoids, FGF's, Cdx, Wnts, Gdf11 and others––interact with this core mechanism at and after space–time defined “decision points,” leading to the separation of distinct axial domains. There are also other roles for signaling pathways. Besides the Hox regulated hindbrain/trunk part of the axis, there is a rostral part (including the anterior part of the head and the extreme anterior domain [EAD]) that appears to be regulated by additional mechanisms. Key aspects of anterior–posterior axial patterning, including: the nature of different phases in early patterning and in the whole process; the specificities of Hox action and of intercellular signaling; and the mechanisms of Hox temporal and spatial collinearities, are discussed in relation to the facts and hypotheses proposed above.

Head Motion Elicited by Viewing Affective Pictures as Measured by a New LED-Based Technique.

The complex sensory input and motor reflexes that keep body posture and head position aligned are influenced by emotional reactions evoked by visual or auditory stimulation. Several theoretical approaches have emphasized the relevance of motor reactions in emotional response. Emotions are considered as a tendency or predisposition to act that depends on two motivational systems in the brain- the appetitive system, related to approach behaviours, and the defensive system, related to withdrawal or fight-or-flight behaviours. Few studies on emotion have been conducted employing kinematic methods, however. Motion analysis of the head may be a promising method for studying the impact of viewing affective pictures on emotional response. For this purpose, we presented unpleasant, neutral and pleasant affective pictures. Participants were instructed to view the pictures and to remain still. Two light-emitting diodes (LEDs) were attached to the foreheads of participants, and a Wii Remote controller, positioned 25cm away, detected the position of the LEDs in the medial-lateral and anterior-posterior axes. We found more sway in response to unpleasant pictures. In addition, unpleasant pictures also provoked faster movements than both neutral and pleasant pictures. This response to unpleasant pictures, in contrast to pleasant ones, might reflect the readiness or predisposition to act. Our data also revealed that men moved faster than women, which is in accordance with previous findings related to gender differences.

Establishment of the Axial Polarity and Cell Fate in Metazoa via Canonical Wnt Signaling: New Insights from Sponges and Annelids

In this paper, the role of the Wnt/β-catenin pathway in the establishment of the body plan in multicellular animals has been analyzed. We demonstrated that at different stages of development the Wnt signaling cascade is involved in several directly unrelated processes such as inner germ layer specification, anterior–posterior axis patterning, and terminal growth. Bioinformatics analysis revealed the independent divergence of Wnt ligands in basal Metazoa and conservation of Wnt subfamilies within the Cnidaria + Bilateria clade. Polarized expression of Wnt ligands in sponge and annelid larvae has been shown, thus confirming the applicability of the existing model of the main body axis patterning to two more taxa. The β-catenin localization and inhibitory analysis have provided evidence of the unlikely role for Wnt pathway in endomesoderm determination in nereid polychaetes. The evolutionary trend to establish alternative mechanisms even for key events such as segregation of germ layers has been observed in the case of more determinative ontogeny and predominance of autonomous specification, as exemplified by the heteroquadrant (unequal) type of spiral development.

A re-inducible gap gene cascade patterns the anterior-posterior axis of insects in a threshold-free fashion.

Gap genes mediate the division of the anterior-posterior axis of insects into different fates through regulating downstream hox genes. Decades of tinkering the segmentation gene network of Drosophila melanogaster led to the conclusion that gap genes are regulated (at least initially) through a threshold-based mechanism, guided by both anteriorly- and posteriorly-localized morphogen gradients. In this paper, we show that the response of the gap gene network in the beetle Tribolium castaneum upon perturbation is consistent with a threshold-free 'Speed Regulation' mechanism, in which the speed of a genetic cascade of gap genes is regulated by a posterior morphogen gradient. We show this by re-inducing the leading gap gene (namely, hunchback) resulting in the re-induction of the gap gene cascade at arbitrary points in time. This demonstrates that the gap gene network is self-regulatory and is primarily under the control of a posterior regulator in Tribolium and possibly other short/intermediate-germ insects.

The Chick Caudolateral Epiblast Acts as a Permissive Niche for Generating Neuromesodermal Progenitor Behaviours

Neuromesodermal progenitors (NMps) are a population of bipotent progenitors that maintain competence to generate both spinal cord and paraxial mesoderm throughout the elongation of the posterior body axis. Recent studies have generated populations of NMp-like cells in culture, which have been shown to differentiate to both neural and mesodermal cell fates when transplanted into either mouse or chick embryos. Here, we aim to compare the potential of mouse embryonic stem (ES) cell-derived progenitor populations to generate NMp behaviour against both undifferentiated and differentiated populations. We define NMp behaviour as the ability of cells to: (i) contribute to a significant proportion of the anterior-posterior body axis, (ii) enter into both posterior neural and somitic compartments, and (iii) retain a proportion of the progenitor population within the posterior growth zone. We compare previously identified ES cell-derived NMp-like populations to undifferentiated mouse ES cells and find that they all display similar potentials to generate NMp behaviour in vivo. To assess whether this competence is lost upon further differentiation, we generated anterior and posterior embryonic cell types through the generation of 3D gastruloids and show that NMp competence is lost within the anterior (Brachyury-negative) portion of the gastruloid. Together this suggests that in vitro-derived NMp-like cells maintain an ability to contribute to multiple germ layers that is also present within pluripotent ES cells, rather than acquiring a neuromesodermal competent state through differentiation.

Znfl1s are essential for patterning the anterior-posterior axis of zebrafish posterior hindbrain by acting as direct target genes of retinoic acid

RA (retinoic acid) signaling is essential for the patterning the hindbrain of vertebrates. Although hundreds of potential RA targets genes are identified, the ones other than hox genes playing roles in patterning anterior-posterior axis of hindbrain by mediating RA signaling remains largely unknown. Previously, we reported that znfl1s play essential roles in the formation of posterior neuroectoderm in zebrafish embryos. Here, we revealed that znfl1s play a critical role in patterning the posterior axis of hindbrain by maintaining the homeostasis of RA signaling in zebrafish embryos. Knocking down znfl1s shortened the length of the posterior hindbrain in a similar way of reducing RA signaling in zebrafish embryos and the defective posterior hindbrain was effectively rescued by elevating RA signaling. By performing mutagenesis assays and chromatin immunoprecipitation assays on the promoter of znfl1s, we demonstrated that znfl1s are direct target genes of RA to mediate RA signaling through a functional DR1 RA response element. Taken together, our results showed that Znfl1s are essential for patterning the anterior-posterior axis development of posterior hindbrain by acting as direct target genes of RA signaling.

Efficacy and safety of vitrectomy for congenital cataract surgery: a systematic review and meta-analysis based on randomized and controlled trials.

PurposeTo explore the effectiveness and safety of vitrectomy for congenital cataract surgery.MethodsWe searched PubMed, Science Direct, The Cochrane Library, China National Knowledge Infrastructure and the Wanfang Database. Two researchers extracted data and assessed paper quality independently. Posterior capsule opacification (PCO) or visual axis opacification (VAO), reoperation rate, visual acuity, intraocular lenses (IOL) deposit, synechias, uveitis, secondary glaucoma, low‐contrast sensitivity and IOL decentration were compared.ResultsWe included 11 randomized controlled trials (RCTs) with 634 congenital cataract eyes. Cases of posterior capsule opacification in vitrectomy group were significantly less than that of control group, with risk ratio (RR) of 0.15 [95% confidence interval (CI): 0.09, 0.26], and there was no heterogeneity (I 2 = 0%, p = 0.94). Reoperation rate in vitrectomy group was lower than that of control group either (RR = 0.40, 95%CI: 0.17, 0.94), and there was no heterogeneity (I 2 = 0%, p = 0.85). Best‐corrected visual acuity (BCVA) measured in LogMAR unit of vitrectomy group was smaller, with a mean difference (MD) of −0.17 (95%CI: −0.28, −0.05), and I 2 was only 22%, indicating of a small heterogeneity. No statistical difference was found between two groups on IOL deposit (RR = 1.23, 95%CI: 0.70, 2.17), and the heterogeneity was small (I 2 = 16%, p = 0.31). No statistical difference was found between two groups on synechias (RR = 1.08, 95%CI: 0.60, 1.94), with a quite small heterogeneity (I 2 = 3%, p = 0.38). No statistical difference was found between two groups on uveitis (RR = 0.55, 95%CI: 0.15, 2.01), and there was no heterogeneity (I 2 = 0%, p = 0.94). There was no statistical difference on IOP either, with a MD of 0.25 (95%CI: −1.56, 2.07), and there was no heterogeneity (I 2 = 0%). Egger's test showed that there was no publication bias for all assessed outcomes. Low‐contrast sensitivity was better in the vitrectomy group. And no evidence indicated vitrectomy could lead to a higher risk on secondary glaucoma or IOL decentration.ConclusionVitrectomy helps lower the PCO risk and reoperation risk after congenital cataract surgery, and also, vitrectomy helps patients gain a better BCVA and achieve a better low‐contrast sensitivity, with no trade‐off on IOP control, IOL deposit, synechias, uveitis and secondary glaucoma. We recommend performing vitrectomy during congenital cataract surgery.

Anatomical Study of Periosteal Vascularization of the Forearm: Design of Vascularized Periosteal Flaps

Introduction Vascularized periosteal flaps (VPFs) have proven to be a useful technique for the treatment of unfavorable biological situations in children, with excellent results due to their osteogenic potential. The objective of this work is to present a detailed anatomical description of the periosteal vascularization of the radius and ulna, as well as the design of the forearm VPFs. Methods Anatomical study with 10 fresh-frozen specimens with antegrade injection of green colored latex. Periosteal branches of the radius and ulna, septocutaneous branches, and muscular branches were dissected. The size of the pre and postdissection flaps was measured, as well as the length of the vascular pedicles. Results The four vascular axes studied were the anterior interosseous vascular axis (AIA), radial axis (RA), ulnar axis (UA), and posterior interosseous vascular axis (PIA). The AIA (volar-radial VPF): an average of 16.2 periosteal branches were obtained, with a mean distance of 6.6 mm between them. The mean size of the VPF was 41.3 cm2 pre-dissection and 32.4 cm2 post-dissection. The average pedicle length was 16.1 cm. Vascular RA (radial VPF): an average of 20.8 branches was found, with a mean VPF size of 54.8 cm2predissection, and 39.3 cm2 post-dissection. The average pedicle length was 20.2 cm. Vascular PIA (dorsal-ulnar VPF): an average of 12.8 periosteal branches were obtained, with the mean VPF size being 26.2 cm2 pre-dissection and 20.4 cm2 post-dissection. The average pedicle length 12.6 cm. Vascular UA (ulnar VPF): an average of 10.2 periosteal branches were obtained with a mean VPF size of 37.5 cm2 pre-dissection and 28.2 cm2 post-dissection. of the average pedicle length was 14.8 cm. Conclusions We have described four new VPFs, with the most useful and versatile being the dorsal-ulnar VPF, based on the PIA, and the volar-radial, based on the AIA. The main advantages of these flaps with respect to microsurgical techniques are the simplicity and speed of the technique, its elasticity and adaptability to the recipient bed, as well as its versatility.

Precision in a rush: Trade-offs between reproducibility and steepness of the hunchback expression pattern.

Fly development amazes us by the precision and reproducibility of gene expression, especially since the initial expression patterns are established during very short nuclear cycles. Recent live imaging of hunchback promoter dynamics shows a stable steep binary expression pattern established within the three minute interphase of nuclear cycle 11. Considering expression models of different complexity, we explore the trade-off between the ability of a regulatory system to produce a steep boundary and minimize expression variability between different nuclei. We show how a limited readout time imposed by short developmental cycles affects the gene’s ability to read positional information along the embryo’s anterior posterior axis and express reliably. Comparing our theoretical results to real-time monitoring of the hunchback transcription dynamics in live flies, we discuss possible regulatory strategies, suggesting an important role for additional binding sites, gradients or non-equilibrium binding and modified transcription factor search strategies.

The hippocampus of birds in a view of evolutionary connectomics

The avian brain displays a different brain architecture compared to mammals. This has led the first pioneers of comparative neuroanatomy to wrong conclusions about bird brain evolution by assuming that the avian telencephalon is a hypertrophied striatum. Based on growing evidence from divers analysis demonstrating that most of the avian forebrain is pallial in nature, this view has substantially changed during the past decades. Further, birds show cognitive abilities comparable to or even exceeding those of some mammals, even without a “six-layered” cortex. Beside higher associative regions, most of these cognitive functions include the processing of information in the hippocampal formation (HF) that shares a homologue structure in birds and mammals. Here we show with 3D polarized light imaging (3D-PLI) that the HF of pigeons like the mammalian HF shows regional specializations along the anterior–posterior axis in connectivity. In addition, different levels of adult neurogenesis were observed in the subdivisions of the HF per se and in the most caudal regions pointing towards a functional specialization along the anterior–posterior axis. Taken together our results point to species specific morphologies but still conserved hippocampal characteristics of connectivity, cells and adult neurogenesis if compared to the mammalian situation. Here our data provides new aspects for the ongoing discussion on hippocampal evolution and mind.

Staggered Hox expression is more widespread among molluscs than previously appreciated.

Hox genes are expressed along the anterior–posterior body axis in a colinear fashion in the majority of bilaterians. Contrary to polyplacophorans, a group of aculiferan molluscs with conserved ancestral molluscan features, gastropods and cephalopods deviate from this pattern by expressing Hox genes in distinct morphological structures and not in a staggered fashion. Among conchiferans, scaphopods exhibit many similarities with gastropods, cephalopods and bivalves, however, the molecular developmental underpinnings of these similar traits remain unknown. We investigated Hox gene expression in developmental stages of the scaphopod Antalis entalis to elucidate whether these genes are involved in patterning morphological traits shared by their kin conchiferans. Scaphopod Hox genes are predominantly expressed in the foot and mantle but also in the central nervous system. Surprisingly, the scaphopod mid-stage trochophore exhibits a near-to staggered expression of all nine Hox genes identified. Temporal colinearity was not found and early-stage and late-stage trochophores, as well as postmetamorphic individuals, do not show any apparent traces of staggered expression. In these stages, Hox genes are expressed in distinct morphological structures such as the cerebral and pedal ganglia and in the shell field of early-stage trochophores. Interestingly, a re-evaluation of previously published data on early-stage cephalopod embryos and of the gastropod pre-torsional veliger shows that these developmental stages exhibit traces of staggered Hox expression. Considering our results and all gene expression and genomic data available for molluscs as well as other bilaterians, we suggest a last common molluscan ancestor with colinear Hox expression in predominantly ectodermal tissues along the anterior–posterior axis. Subsequently, certain Hox genes have been co-opted into the patterning process of distinct structures (apical organ or prototroch) in conchiferans.

Bicoid gradient formation mechanism and dynamics revealed by protein lifetime analysis

Embryogenesis relies on instructions provided by spatially organized signaling molecules known as morphogens. Understanding the principles behind morphogen distribution and how cells interpret locally this information remains a major challenge in developmental biology. Here, we introduce morphogen‐age measurements as a novel approach to test models of morphogen gradient formation. Using a tandem fluorescent timer as a protein age sensor, we find a gradient of increasing age of Bicoid along the anterior–posterior axis in the early Drosophila embryo. Quantitative analysis of the protein age distribution across the embryo reveals that the synthesis–diffusion–degradation model is the most likely model underlying Bicoid gradient formation, and rules out other hypotheses for gradient formation. Moreover, we show that the timer can detect transitions in the dynamics associated with syncytial cellularization. Our results provide new insight into Bicoid gradient formation and demonstrate how morphogen‐age information can complement knowledge about movement, abundance, and distribution, which should be widely applicable to other systems.

Insights into the Etiology of Mammalian Neural Tube Closure Defects from Developmental, Genetic and Evolutionary Studies.

The human neural tube defects (NTD), anencephaly, spina bifida and craniorachischisis, originate from a failure of the embryonic neural tube to close. Human NTD are relatively common and both complex and heterogeneous in genetic origin, but the genetic variants and developmental mechanisms are largely unknown. Here we review the numerous studies, mainly in mice, of normal neural tube closure, the mechanisms of failure caused by specific gene mutations, and the evolution of the vertebrate cranial neural tube and its genetic processes, seeking insights into the etiology of human NTD. We find evidence of many regions along the anterior–posterior axis each differing in some aspect of neural tube closure—morphology, cell behavior, specific genes required—and conclude that the etiology of NTD is likely to be partly specific to the anterior–posterior location of the defect and also genetically heterogeneous. We revisit the hypotheses explaining the excess of females among cranial NTD cases in mice and humans and new developments in understanding the role of the folate pathway in NTD. Finally, we demonstrate that evidence from mouse mutants strongly supports the search for digenic or oligogenic etiology in human NTD of all types.

Prognosis of Functional Results of Arising or Immature Cataract Phacoemulsification High Myopia

Actuality. Complicated cataract surgery in high myopia is accompanied by the high risk of intra- and postoperative complications caused by this background disease. The presence of lens opalescence influences the results of many functional diagnostic tests. Diagnostic and prognostic research of the modern methods of investigation such as spectral optical coherence tomography, ultrasound biomicroscopy and B-scanning is urgent in patients with high myopia and cataract. The true prognosis of visual functions in these patients will allow solving the problem of cataract phacoemulsification expediency, decreasing the risks of complications.Purpose. To determine prognostic criteria of complicated cataract phacoemulsification outcome in high myopia.Patients and methods. 62 patients (101 eyes) with arising or immature cataract and high myopia were examined. All patients underwent ultrasound biomicroscopy of retinal periphery, ultrasound B-scanning of vitreous body and spectral optical coherence tomography of macular zone preoperatively, in the first postoperative days, in a month, in 6–8 months. We performed the correlation analysis of the initial morphological parameters and postoperative visual acuity. To solve the problem of the favorable outcome prognostication (achieving a certain level of visual acuity by the definite term after surgery) the method of binary logistic regression was used.Results and conclusion. The performed mathematical analysis showed the correlation between the postoperative visual acuity and the initial morphological parameters in a myopic eye: the value of ocular anterior posterior axis, the height of the posterior vitreous detachment, posterior staphyloma, the retinoschisis length in the superior outer segment, epiretinal membrane height, pigmented epithelium destruction and discharge, increased choroidal reflectivity, subfoveal choroidal thickness. We built the mathematical models that allowed predicting with high accuracy the probability of achieving a certain level of postoperative visual acuity following cataract phacoemulsification in high myopia.

Wavy movements of epidermis monocilia drive the neurula rotation that determines left–right asymmetry in ascidian embryos

Tadpole larvae of the ascidian, Halocynthia roretzi, show morphological left–right asymmetry in the brain structures and the orientation of tail bending within the vitelline membrane. Neurula embryos rotate along the anterior–posterior axis in a counterclockwise direction, and then this rotation stops when the left side of the embryo is oriented downwards. Contact of the left-side epidermis with the vitelline membrane promotes nodal gene expression in the left-side epidermis. This is a novel mechanism in which rotation of whole embryos provides the initial cue for breaking left–right symmetry. Here we show that epidermal monocilia, which appear at the neurula rotation stage, generate the driving force for rotation. A ciliary protein, Arl13b, fused with Venus YFP was used for live imaging of ciliary movements. Although overexpression of wild-type Arl13b fusion protein resulted in aberrant movements of the cilia and abrogation of neurula rotation, mutant Arl13b fusion protein, in which the GTPase and coiled-coil domains were removed, did not affect the normal ciliary movements and neurula rotation. Epidermis cilia moved in a wavy and serpentine way like sperm flagella but not in a rotational way or beating way with effective stroke and recovery stroke. They moved very slowly, at 1/7 Hz, consistent with the low angular velocity of neurula rotation (ca. 43°/min). The tips of most cilia pointed in the opposite direction of embryonic rotation. Similar motility was also observed in Ciona robusta embryos. When embryos were treated with a dynein inhibitor, Ciliobrevin D, both ciliary movements and neurula rotation were abrogated, showing that ciliary movements drive neurula rotation in Halocynthia. The drug also inhibited Ciona neurula rotation. Our observations suggest that the driving force of rotation is generated using the vitelline membrane as a substrate but not by making a water current around the embryo. It is of evolutionary interest that ascidians use ciliary movements to break embryonic left–right symmetry, like in many vertebrates. Meanwhile, ascidian embryos rotate as a whole, similar to embryos of non-vertebrate deuterostomes, such as echinoderm, hemichordate, and amphioxus, while swimming.

The Reissner Fiber in the Cerebrospinal Fluid Controls Morphogenesis of the Body Axis

SummaryOrgan development depends on the integration of coordinated long-range communication between cells. The cerebrospinal fluid composition and flow properties regulate several aspects of central nervous system development, including progenitor proliferation, neurogenesis, and migration [1, 2, 3]. One understudied component of the cerebrospinal fluid, described over a century ago in vertebrates, is the Reissner fiber. This extracellular thread forming early in development results from the assembly of the SCO-spondin protein in the third and fourth brain ventricles and central canal of the spinal cord [4]. Up to now, the function of the Reissner fiber has remained elusive, partly due to the lack of genetic invalidation models [4]. Here, by mutating the scospondin gene, we demonstrate that the Reissner fiber is critical for the morphogenesis of a straight posterior body axis. In zebrafish mutants where the Reissner fiber is lost, ciliogenesis and cerebrospinal fluid flow are intact but body axis morphogenesis is impaired. Our results also explain the frequently observed phenotype that mutant embryos with defective cilia exhibit defects in body axis curvature. Here, we reveal that these mutants systematically fail to assemble the Reissner fiber. We show that cilia promote the formation of the Reissner fiber and that the fiber is necessary for proper body axis morphogenesis. Our study sets the stage for future investigations of the mechanisms linking the Reissner fiber to the control of body axis curvature during vertebrate development.