Automated contour extraction for light-sheet microscopy images of zebrafish embryos based on object edge detection algorithm

Embryo contour extraction is the initial step in the quantitative analysis of embryo morphology, and it is essential for understanding the developmental process. Recent developments in light-sheet microscopy have enabled the in toto time-lapse imaging of embryos, including zebrafish. However, embryo contour extraction from images generated via light-sheet microscopy is challenging owing to the large amount of data and the variable sizes, shapes, and textures of objects. In this report, we provide a workflow for extracting the contours of zebrafish blastula and gastrula without contour labeling of an embryo. This workflow is based on the edge detection method using a change point detection approach. We assessed the performance of the edge detection method and compared it with widely used edge detection and segmentation methods. The results showed that the edge detection accuracy of the proposed method was superior to those of the Sobel, Laplacian of Gaussian, adaptive threshold, Multi Otsu, and k-means clustering-based methods, and the noise robustness of the proposed method was superior to those of the Multi Otsu and k-means clustering-based methods. The proposed workflow was shown to be useful for automating small-scale contour extractions of zebrafish embryos that cannot be specifically labeled owing to constraints, such as the availability of microscopic channels. This workflow may offer an option for contour extraction when deep learning-based approaches or existing non-deep learning-based methods cannot be applied.

Epigenetically distinct synaptic architecture in clonal compartments in the teleostean dorsal pallium

The dorsal telencephalon (i.e. the pallium) exhibits high anatomical diversity across vertebrate classes. The non-mammalian dorsal pallium accommodates various compartmentalized structures among species. The developmental, functional, and evolutional diversity of the dorsal pallium remain unillustrated. Here, we analyzed the structure and epigenetic landscapes of cell lineages in the telencephalon of medaka fish (Oryzias latipes) that possesses a clearly delineated dorsal pallium (Dd2). We found that pallial anatomical regions, including Dd2, are formed by mutually exclusive clonal units, and that each pallium compartment exhibits a distinct epigenetic landscape. In particular, Dd2 possesses a unique open chromatin pattern that preferentially targets synaptic genes. Indeed, Dd2 shows a high density of synapses. Finally, we identified several transcription factors as candidate regulators. Taken together, we suggest that cell lineages are the basic components for the functional regionalization in the pallial anatomical compartments and that their changes have been the driving force for evolutionary diversity.

Formation and three-dimensional architecture of Leishmania adhesion in the sand fly vector

Attachment to a substrate to maintain position in a specific ecological niche is a common strategy across biology, especially for eukaryotic parasites. During development in the sand fly vector, the eukaryotic parasite Leishmania adheres to the stomodeal valve, as the specialised haptomonad form. Dissection of haptomonad adhesion is a critical step for understanding the complete life cycle of Leishmania. Nevertheless, haptomonad studies are limited, as this is a technically challenging life cycle form to investigate. Here, we have combined three-dimensional electron microscopy approaches, including serial block face scanning electron microscopy (SBFSEM) and serial tomography to dissect the organisation and architecture of haptomonads in the sand fly. We showed that the attachment plaque contains distinct structural elements. Using time-lapse light microscopy of in vitro haptomonad-like cells, we identified five stages of haptomonad-like cell differentiation, and showed that calcium is necessary for Leishmania adhesion to the surface in vitro. This study provides the structural and regulatory foundations of Leishmania adhesion,which are critical for a holistic understanding of the Leishmania life cycle.

FGF signaling induces the regeneration of collagen fiber structure during skin wound healing in axolotls

Axolotls have been considered to be able to regenerate their skin completely. Our recent study updated this theory with the finding that the lattice structure of dermal collagen fibers was not fully regenerated after skin injury. We also discovered that nerves induce the regeneration of collagen fibers. The mechanism of collagen fiber regeneration remains unknown, however. In this study, we focused on the structure of collagen fibers with collagen braiding cells, and cell origin in axolotl skin regeneration. In the wounded dermis, cells involved in skin repair/regeneration were derived from both the surrounding dermis and the subcutaneous tissue. Regardless of cell origin, cells acquired the proper cell morphology to braid collagen fiber with nerve presence. We also found that FGF signaling could substitute for the nerve roles in the conversion of subcutaneous fibroblasts to lattice-shaped dermal fibroblasts. Our findings contribute to the elucidation of the fundamental mechanisms of true skin regeneration and provide useful insights for pioneering new skin treatments.

Light-sheet microscopy reveals dorsoventral asymmetric membrane dynamics of Amoeba proteus during pressure-driven locomotion

Amoebae are found all around the world and play an essential role in the carbon cycle in the environment. Therefore, the behavior of amoebae is a crucial factor when considering the global environment. Amoebae change their distribution through amoeboid locomotion, which are classified into several modes. In the pressure-driven mode, intracellular hydrostatic pressure generated by the contraction of cellular cortex actomyosin causes the pseudopod to extend. During amoeboid locomotion, the cellular surface exhibits dynamic deformation. Therefore, to understand the mechanism of amoeboid locomotion, it is important to characterize cellular membrane dynamics. Here, to clarify membrane dynamics during pressure-driven amoeboid locomotion, we developed a polkadot membrane staining method and performed light-sheet microscopy in Amoeba proteus, which exhibits typical pressure-driven amoeboid locomotion. It was observed that the whole cell membrane moved in the direction of movement, and the dorsal cell membrane in the posterior part of the cell moved more slowly than the other membrane. In addition, membrane complexity varied depending on the focused characteristic size of the membrane structure, and in general, the dorsal side was more complex than the ventral side. In summary, the membrane dynamics of Amoeba proteus during pressure-driven locomotion are asymmetric between the dorsal and ventral sides. This article has an associated interview with the co-first authors of the paper.

Lattice-patterned collagen fibers and their dynamics in axolotl skin regeneration

The morphology of collagen-producing cells and the structure of produced collagen in the dermis have not been well-described. This lack of insights has been a serious obstacle in the evaluation of skin regeneration. We succeeded in visualizing collagen-producing cells and produced collagen using the axolotl skin, which is highly transparent. The visualized dermal collagen had a lattice-like structure. The collagen-producing fibroblasts consistently possessed the lattice-patterned filopodia along with the lattice-patterned collagen network. The dynamics of this lattice-like structure were also verified in the skin regeneration process of axolotls, and it was found that the correct lattice-like structure was not reorganized after simple skin wounding but was reorganized in the presence of nerves. These findings are not only fundamental insights in dermatology but also valuable insights into the mechanism of skin regeneration.

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Dermal collagen synthesized by a single cell was visualized in the axolotl skin

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Collagen-synthetic cells were visualized and revealed lattice-patterned filopodia

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Collagen pattern was deformed after simple skin wounding

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The lattice-patterned collagen was only restorable in the presence of nerves

Colocalization Analysis of Lipo-Deoxyribozyme Consisting of DNA and Protic Catalysts in a Vesicle-Based Protocellular Membrane Investigated by Confocal Microscopy

The linkage between the self-reproduction of compartments and the replication of DNA in a compartment is a crucial requirement for cellular life. In our giant vesicle (GV)-based model protocell, this linkage is achieved through the action of a supramolecular catalyst composed of membrane-intruded DNA and amphiphilic acid catalysts (C@DNA) in a GV membrane. In this study, we examined colocalization analysis for the formation of the supramolecular catalyst using a confocal laser scanning fluorescence microscope with high sensitivity and resolution. Red fluorescence spots emitted from DNA tagged with Texas Red (Texas Red-DNA) were observed in a GV membrane stained with phospholipid tagged with BODIPY (BODIPY-HPC). To our knowledge, this is the first direct observation of DNA embedded in a GV-based model protocellular membrane containing cationic lipids. Colocalization analysis based on a histogram of frequencies of "normalized mean deviation product" revealed that the frequencies of positively correlated [lipophilic catalyst tagged with BODIPY (BODIPY-C) and Texas Red-DNA] were significantly higher than those of [BODIPY-HPC and Texas Red-DNA]. This result demonstrates the spontaneous formation of C@DNA in the GV membrane, which serves as a lipo-deoxyribozyme for producing membrane lipids from its precursor.

Near-wall rheotaxis of the ciliate Tetrahymena induced by the kinesthetic sensing of cilia

To survive in harsh environments, single-celled microorganisms autonomously respond to external stimuli, such as light, heat, and flow. Here, we elucidate the flow response of Tetrahymena, a well-known single-celled freshwater microorganism. Tetrahymena moves upstream against an external flow via a behavior called rheotaxis. While micrometer-sized particles are swept away downstream in a viscous flow, what dynamics underlie the rheotaxis of the ciliate? Our experiments reveal that Tetrahymena slides along walls during upstream movement, which indicates that the cells receive rotational torque from shear flow to control cell orientation. To evaluate the effects of the shear torque and propelling speed, we perform a numerical simulation with a hydrodynamic model swimmer adopting cilia dynamics in a shear flow. The swimmer orientations converge to an upstream alignment, and the swimmer slides upstream along a boundary wall. The results suggest that Tetrahymena automatically responds to shear flow by performing rheotaxis using cilia-stalling mechanics.

Transient microglial absence assists postmigratory cortical neurons in proper differentiation

In the developing cortex, postmigratory neurons accumulate in the cortical plate (CP) to properly differentiate consolidating subtype identities. Microglia, despite their extensive surveying activity, temporarily disappear from the midembryonic CP. However, the mechanism and significance of this absence are unknown. Here, we show that microglia bidirectionally migrate via attraction by CXCL12 released from the meninges and subventricular zone and thereby exit the midembryonic CP. Upon nonphysiological excessive exposure to microglia in vivo or in vitro, young postmigratory and in vitro-grown CP neurons showed abnormal differentiation with disturbed expression of the subtype-associated transcription factors and genes implicated in functional neuronal maturation. Notably, this effect is primarily attributed to interleukin 6 and type I interferon secreted by microglia. These results suggest that “sanctuarization” from microglia in the midembryonic CP is required for neurons to appropriately fine-tune the expression of molecules needed for proper differentiation, thus securing the establishment of functional cortical circuit.

Microglia temporarily disappear from the cortical plate in the midembryonic stage. This study demonstrated that microglial transient absence from the cortical plate is required for postmigratory neurons to appropriately fine-tune the expression of molecules needed for their proper differentiation.

Skeleton construction upon local regression of the sponge body

We previously revealed that the mechanism of demosponge skeleton construction is self-organization by multiple rounds of sequential mechanical reactions of player cells. In these reactions, "transport cells" dynamically carry fine skeletal elements (spicules) on epithelia surrounding the inner body space of sponges (basal epithelium (basopinacoderm) and the endodermal epithelium (ENCM)). Once spicules pierce ENCM and apical pinacoderm, subsequently they are cemented to the substratum under the sponge body, or connected to other skeleton-constructing spicules. Thus, the "pierce" step is the key to holding up spicules in the temporary periphery of growing sponges' bodies. Since sponges can regress as well as grow, here we asked how skeleton construction occurs during local regression of the body. We found that prior to local basopinacoderm retraction (and thus body regression), the body became thinner. Some spicules that were originally carried outward stagnated for a while, and were then carried inwards either on ENCM or basopinacoderm. Spicules that were carried inwards on ENCM pierced epithelia after a short transport, and thus became held up at relatively inward positions compared to spicules carried on outwardly extending basopinacoderm. The switch of epithelia on which transport cells migrate efficiently occurred in thinner body spaces where basopinacoderm and ENCM became close to each other. Thus, the mechanisms underlying this phenomenon are rather mechanical: the combination of sequential reactions of skeleton construction and the narrowed body space upon local retraction of basopinacoderm cause spicules to be held up at more-inward positions, which might strengthen the basopinacoderm's attachment to substratum.

Developmental analyses of mouse embryos and adults using a non-overlapping tracing system for all three germ layers

Genetic lineage-tracing techniques are powerful tools for studying specific cell populations in development and pathogenesis. Previous techniques have mainly involved systems for tracing a single gene, which are limited in their ability to facilitate direct comparisons of the contributions of different cell lineages. We have developed a new combinatorial system for tracing all three germ layers using self-cleaving 2A peptides and multiple site-specific recombinases (SSRs). In the resulting TRiCK (TRiple Coloured germ layer Knock-in) mice, the three germ layers are conditionally and simultaneously labelled with distinct fluorescent proteins via embryogenesis. We show that previously reported ectopic expressions of lineage markers are the outcome of secondary gene expression. The results presented here also indicate that the commitment of caudal axial stem cells to neural or mesodermal fate proceeds without lineage fluctuations, contrary to the notion of their bi-potency. Moreover, we developed IMES, an optimized tissue clearing method that is highly compatible with a variety of fluorescent proteins and immunostaining, and the combined use of TRiCK mice and IMES can facilitate comprehensive analyses of dynamic contributions of all three germ layers.

Evolutionary transformation of mouthparts from particle-feeding to piercing carnivory in Viper copepods: Review and 3D analyses of a key innovation using advanced imaging techniques

BACKGROUND

Novel feeding adaptations often facilitate adaptive radiation and diversification. But the evolutionary origins of such feeding adaptations can be puzzling if they require concordant change in multiple component parts. Pelagic, heterorhabdid copepods (Calanoida) exhibit diverse feeding behaviors that range from simple particle feeding to a highly specialized form of carnivory involving piercing mouthparts that likely inject venom. We review the evolutionary history of heterorhabdid copepods and add new high-resolution, 3D anatomical analyses of the muscular system, glands and gland openings associated with this remarkable evolutionary transformation.

RESULTS

We examined four heterorhabdid copepods with different feeding modes: one primitive particle-feeder (Disseta palumbii), one derived and specialized carnivore (Heterorhabdus subspinifrons), and two intermediate taxa (Mesorhabdus gracilis and Heterostylites longicornis). We used two advanced, high-resolution microscopic techniques - serial block-face scanning electron microscopy and two-photon excitation microscopy - to visualize mouthpart form and internal anatomy at unprecedented nanometer resolution. Interactive 3D graphical visualizations allowed putative homologues of muscles and gland cells to be identified with confidence and traced across the evolutionary transformation from particle feeding to piercing carnivory. Notable changes included: a) addition of new gland cells, b) enlargement of some (venom producing?) glands, c) repositioning of gland openings associated with hollow piercing fangs on the mandibles, d) repurposing of some mandibular-muscle function to include gland-squeezing, and e) addition of new muscles that may aid venom injection exclusively in the most specialized piercing species. In addition, live video recording of all four species revealed mandibular blade movements coupled to cyclic contraction of some muscles connected to the esophagus. These behavioral and 3D morphological observations revealed a novel injection system in H. subspinifrons associated with piercing (envenomating?) carnivory.

CONCLUSIONS

Collectively, these results suggest that subtle changes in mandibular tooth form, and muscle and gland form and location, facilitated the evolution of a novel, piercing mode of feeding that accelerated diversification of the genus Heterorhabdus. They also highlight the value of interactive 3D animations for understanding evolutionary transformations of complex, multicomponent morphological systems.

Calaxin is required for cilia-driven determination of vertebrate laterality

Calaxin is a Ca2+-binding dynein-associated protein that regulates flagellar and ciliary movement. In ascidians, calaxin plays essential roles in chemotaxis of sperm. However, nothing has been known for the function of calaxin in vertebrates. Here we show that the mice with a null mutation in Efcab1, which encodes calaxin, display typical phenotypes of primary ciliary dyskinesia, including hydrocephalus, situs inversus, and abnormal motility of trachea cilia and sperm flagella. Strikingly, both males and females are viable and fertile, indicating that calaxin is not essential for fertilization in mice. The 9 + 2 axonemal structures of epithelial multicilia and sperm flagella are normal, but the formation of 9 + 0 nodal cilia is significantly disrupted. Knockout of calaxin in zebrafish also causes situs inversus due to the irregular ciliary beating of Kupffer's vesicle cilia, although the 9 + 2 axonemal structure appears to remain normal.

System level analysis of motor-related neural activities in larval Drosophila

The way in which the central nervous system (CNS) governs animal movement is complex and difficult to solve solely by the analyses of muscle movement patterns. We tackle this problem by observing the activity of a large population of neurons in the CNS of larval Drosophila. We focused on two major behaviors of the larvae - forward and backward locomotion - and analyzed the neuronal activity related to these behaviors during the fictive locomotion that occurs spontaneously in the isolated CNS. We expressed a genetically-encoded calcium indicator, GCaMP and a nuclear marker in all neurons and then used digitally scanned light-sheet microscopy to record (at a fast frame rate) neural activities in the entire ventral nerve cord (VNC). We developed image processing tools that automatically detected the cell position based on the nuclear staining and allocate the activity signals to each detected cell. We also applied a machine learning-based method that we recently developed to assign motor status in each time frame. Our experimental procedures and computational pipeline enabled systematic identification of neurons that showed characteristic motor activities in larval Drosophila. We found cells whose activity was biased toward forward locomotion and others biased toward backward locomotion. In particular, we identified neurons near the boundary of the subesophageal zone (SEZ) and thoracic neuromeres, which were strongly active during an early phase of backward but not forward fictive locomotion.

Influence of cellular shape on sliding behavior of ciliates

Some types of ciliates accumulate on solid/fluid interfaces. This behavior is advantageous to survival in nature due to the presence of sufficient nutrition and stable environments. Recently, the accumulating mechanisms of Tetrahymena pyriformis at the interface were investigated. The synergy of the ellipsoidal shape of the cell body and the mechanosensing feature of the cilia allow for cells to slide on interfaces, and the sliding behavior leads to cell accumulation on the interfaces. Here, to examine the generality of the sliding behavior of ciliates, we characterized the behavior of Paramecium caudatum, which is a commonly studied ciliate. Our experimental and numerical results confirmed that P. caudatum also slid on the solid/fluid interface by using the same mechanism as T. pyriformis. In addition, we evaluated the effects of cellular ellipticity on their behaviors near the wall with a phase diagram produced via numerical simulation.

Axially-confined in vivo single-cell labeling by primed conversion using blue and red lasers with conventional confocal microscopes

Green-to-red photoconvertible fluorescent proteins have been found to undergo efficient photoconversion by a new method termed primed conversion that uses dual wave-length illumination with blue and red/near-infrared light. By modifying a confocal laser-scanning microscope (CLSM) such that two laser beams only meet at the focal plane, confined photoconversion at the axial dimension has been achieved. The necessity of this custom modification to the CLSM, however, has precluded the wide-spread use of this method. Here, we investigated whether spatially-restricted primed conversion could be achieved with CLSM without any hardware modification. We found that the primed conversion of Dendra2 using a conventional CLSM with two visible lasers (473 nm and 635 nm) and a high NA objective lens (NA, 1.30) resulted in dramatic restriction of photoconversion volume: half-width half-maximum for the axial dimension was below 5 μm, which is comparable to the outcome of the original method that used the microscope modification. As a proof of this method's effectiveness, we used this technique in living zebrafish embryos and succeeded in revealing the complex anatomy of individual neurons packed between neighboring cells. Because unmodified CLSMs are widely available, this method can be widely applicable for labeling cells with single-cell resolution.

Three-dimensional assessment of the normal Japanese glenoid and comparison with the normal French glenoid

INTRODUCTION

In 2014, reverse total shoulder arthroplasty was approved in Japan. We were concerned that the base plate might be incompatible with Japanese who were generally smaller than Westerners. Therefore, we investigated the dimensions and morphology of the normal Japanese glenoid and compared with the normal French glenoid.

MATERIALS AND METHODS

One hundred Japanese shoulders without glenoid lesions (50 men and 50 women) were investigated and compared with 100 French shoulders (50 men and 50 women). Computed tomography was performed with 3-dimensional image reconstruction and images were analyzed using Glenosys software. Glenoid parameters (width, height, retroversion and inclination) were compared between Japanese and French subjects.

RESULTS

In Japanese subjects, the mean glenoid width was 25.5mm, height was 33.3mm, retroversion was 2.3° and inclination was 11.6° superiorly. In French subjects, the mean glenoid width was 26.7mm, height was 35.4mm, retroversion was 6.0° and inclination was 10.4° superiorly. Glenoid width and height were significantly smaller in Japanese subjects than French subjects (P=0.001 and P<0.001), while retroversion was significantly greater in French subjects (P<0.001). There was no significant difference of inclination.

CONCLUSIONS

These findings will help surgeons to identify suitable patients for RSA and perform the procedure with appropriate preoperative planning.

LEVEL OF EVIDENCE

IV: retrospective or historical series.

High-speed microscopy with an electrically tunable lens to image the dynamics of in vivo molecular complexes

We provide an evaluation for an electrically tunable lens (ETL), combined with a microscope system, from the viewpoint of tracking intracellular protein complexes. We measured the correlation between the quantitative axial focus shift and the control current for ETL, and determined the stabilization time for refocusing to evaluate the electrical focusing behaviour of our system. We also confirmed that the change of relative magnification by the lens and associated resolution does not influence the ability to find intracellular targets. By applying the ETL system to observe intracellular structures and protein complexes, we confirmed that this system can obtain 10 nm order z-stacks, within video rate, while maintaining the quality of images and that this system has sufficient optical performance to detect the molecules.

Ultrasensitive imaging of Ca2+ dynamics in pancreatic acinar cells of yellow cameleon-nano transgenic mice

Yellow Cameleons are genetically encoded Ca²⁺ indicators in which cyan and yellow fluorescent proteins and calmodulin work together as a fluorescence (Förster) resonance energy transfer Ca²⁺-sensor probe. To achieve ultrasensitive Ca²⁺ imaging for low resting Ca²⁺ or small Ca²⁺ transients in various organs, we generated a transgenic mouse line expressing the highest-sensitive genetically encoded Ca²⁺ indicator (Yellow Cameleon-Nano 15) in the whole body. We then focused on the mechanism of exocytotic events mediated by intracellular Ca²⁺ signaling in acinar cells of the mice with an agonist and observed them by two-photon excitation microscopy. In the results, two-photon excitation imaging of Yellow Cameleon-Nano 15 successfully visualized intracellular Ca²⁺ concentration under stimulation with the agonist at nanomolar levels. This is the first demonstration for application of genetically encoded Ca²⁺ indicators to pancreatic acinar cells. We also simultaneously observed exocytotic events and an intracellular Ca²⁺ concentration under in vivo condition. Yellow Cameleon-Nano 15 mice are healthy and no significant deteriorative effect was observed on physiological response regarding the pancreatic acinar cells. The dynamic range of 165% was calculated from R_max and R_min values under in vivo condition. The mice will be useful for ultrasensitive Ca²⁺ imaging in vivo.

Wide field intravital imaging by two-photon-excitation digital-scanned light-sheet microscopy (2p-DSLM) with a high-pulse energy laser

Digital-scanned light-sheet microscopy (DSLM) illuminates a sample in a plane and captures single-photon-excitation fluorescence images with a camera from a direction perpendicular to the light sheet. This method is potentially useful for observing biological specimens, because image acquisition is relatively fast, resulting in reduction of phototoxicity. However, DSLM cannot be effectively applied to high-scattering materials due to the image blur resulting from thickening of the light sheet by scattered photons. However, two-photon-excitation DSLM (2p-DSLM) enables collection of high-contrast image with near infrared (NIR) excitation. In conventional 2p-DSLM, the minimal excitation volume for two-photon excitation restricts the field of view. In this study, we achieved wide-field 2p-DSLM by using a high-pulse energy fiber laser, and then used this technique to perform intravital imaging of a small model fish species, medaka (Oryzias latipes). Wide fields of view (>700 μm) were achieved by using a low-numerical aperture (NA) objective lens and high-peak energy NIR excitation at 1040 nm. We also performed high-speed imaging at near-video rate and successfully captured the heartbeat movements of a living medaka fish at 20 frames/sec.

Direct determination of spin-orbit interaction coefficients and realization of the persistent spin helix symmetry

The spin-orbit interaction plays a crucial role in diverse fields of condensed matter, including the investigation of Majorana fermions, topological insulators, quantum information and spintronics. In III-V zinc-blende semiconductor heterostructures, two types of spin-orbit interaction--Rashba and Dresselhaus--act on the electron spin as effective magnetic fields with different directions. They are characterized by coefficients α and β, respectively. When α is equal to β, the so-called persistent spin helix symmetry is realized. In this condition, invariance with respect to spin rotations is achieved even in the presence of the spin-orbit interaction, implying strongly enhanced spin lifetimes for spatially periodic spin modes. Existing methods to evaluate α/β require fitting analyses that often include ambiguity in the parameters used. Here, we experimentally demonstrate a simple and fitting parameter-free technique to determine α/β and to deduce the absolute values of α and β. The method is based on the detection of the effective magnetic field direction and the strength induced by the two spin-orbit interactions. Moreover, we observe the persistent spin helix symmetry by gate tuning.

Live imaging and quantitative analysis of gastrulation in mouse embryos using light-sheet microscopy and 3D tracking tools

This protocol describes how to observe gastrulation in living mouse embryos by using light-sheet microscopy and computational tools to analyze the resulting image data at the single-cell level. We describe a series of techniques needed to image the embryos under physiological conditions, including how to hold mouse embryos without agarose embedding, how to transfer embryos without air exposure and how to construct environmental chambers for live imaging by digital scanned light-sheet microscopy (DSLM). Computational tools include manual and semiautomatic tracking programs that are developed for analyzing the large 4D data sets acquired with this system. Note that this protocol does not include details of how to build the light-sheet microscope itself. Time-lapse imaging ends within 12 h, with subsequent tracking analysis requiring 3-6 d. Other than some mouse-handling skills, this protocol requires no advanced skills or knowledge. Light-sheet microscopes are becoming more widely available, and thus the techniques outlined in this paper should be helpful for investigating mouse embryogenesis.

Is endoscopic submucosal dissection an effective treatment for operable patients with clinical submucosal invasive early gastric cancer?

BACKGROUND AND STUDY AIMS

Gastrectomy with lymph node dissection is the gold standard curative treatment for clinical submucosal invasive early gastric cancer (cSM EGC), but a relatively small number of operable patients with cSM EGC have undergone endoscopic submucosal dissection (ESD) instead because they refused surgery. The aim of this study was to determine the effectiveness of ESD in these operable patients.

METHODS

The therapeutic outcomes of ESD were retrospectively assessed for 38 patients with 38 operable cSM EGC lesions who initially refused surgery at the National Cancer Center Hospital, Tokyo, from January 1999 to December 2008.

RESULTS

The en bloc resection rate was 84.2% (32 lesions) and the complete (R0) resection rate was 63.2% (24 lesions). A total of 33 lesions (86.8%) involved submucosal invasion on pathology. Resection was non-curative in 34 patients (89.5%), 22 of whom (64.7%) underwent subsequent gastrectomy after the need for such surgery was carefully explained to them again. The median follow-up period was 73.2 months (range 3-115 months). Local recurrence was detected in one patient, distant metastasis in two patients, and both local recurrence and distant metastasis were detected in one patient. None of these four patients with recurrence (10.5%) had undergone surgery when their recurrent disease was detected and all of them died from gastric cancer. The 5-year cause-specific survival rate for all patients was 91.8%.

CONCLUSION

The 5-year cause-specific survival rate for all patients was lower than the previously reported rate of 96.7% for pathologically submucosal invasive EGC patients after gastrectomy; therefore, ESD appears to have been an ineffective treatment for operable patients with cSM EGC.

Live imaging of whole mouse embryos during gastrulation: migration analyses of epiblast and mesodermal cells

During gastrulation in the mouse embryo, dynamic cell movements including epiblast invagination and mesodermal layer expansion lead to the establishment of the three-layered body plan. The precise details of these movements, however, are sometimes elusive, because of the limitations in live imaging. To overcome this problem, we developed techniques to enable observation of living mouse embryos with digital scanned light sheet microscope (DSLM). The achieved deep and high time-resolution images of GFP-expressing nuclei and following 3D tracking analysis revealed the following findings: (i) Interkinetic nuclear migration (INM) occurs in the epiblast at embryonic day (E)6 and 6.5. (ii) INM-like migration occurs in the E5.5 embryo, when the epiblast is a monolayer and not yet pseudostratified. (iii) Primary driving force for INM at E6.5 is not pressure from neighboring nuclei. (iv) Mesodermal cells migrate not as a sheet but as individual cells without coordination.

Asymmetric distribution of dynamic calcium signals in the node of mouse embryo during left-right axis formation

In the node of mouse embryo, rotational movements of cilia generate an external liquid flow known as nodal flow, which determines left-right asymmetric gene expression. How nodal flow is converted into asymmetric gene expression is still controversial, but the increase of Ca(2+) levels in endodermal cells to the left of the node has been proposed to play a role. However, Ca(2+) signals inside the node itself have not yet been described. By our optimized Ca(2+) imaging method, we were able to observe dynamic Ca(2+) signals in the node in live mouse embryos. Pharmacological disruption of Ca(2+) signals did not affect ciliary movements or nodal flow, but did alter the expression patterns of the Nodal and Cerl-2 genes. Quantitative analyses of Ca(2+) signal frequencies and distributions showed that during left-right axis establishment, formerly symmetric Ca(2+) signals became biased to the left side. In iv/iv mutant embryos that showed randomized laterality due to ciliary immotility, Ca(2+) signals were found to be variously left-sided, right-sided, or bilateral, and thus symmetric on average. In Pkd2 mutant embryos, which lacked polycystin-2, a Ca(2+)-permeable cation channel necessary for left-right axis formation, the Ca(2+) signal frequency was lower than in wild-type embryos. Our data support a model in which dynamic Ca(2+) signals in the node are involved in left-right patterning.

Mechanism of microtubule array expansion in the cytokinetic phragmoplast

In land plants, the cell plate partitions the daughter cells at cytokinesis. The cell plate initially forms between daughter nuclei and expands centrifugally until reaching the plasma membrane. The centrifugal development of the cell plate is driven by the centrifugal expansion of the phragmoplast microtubule array, but the molecular mechanism underlying this expansion is unknown. Here, we show that the phragmoplast array comprises stable microtubule bundles and dynamic microtubules. We find that the dynamic microtubules are nucleated by γ-tubulin on stable bundles. The dynamic microtubules elongate at the plus ends and form new bundles preferentially at the leading edge of the phragmoplast. At the same time, they are moved away from the cell plate, maintaining a restricted distribution of minus ends. We propose that cycles of attachment of γ-tubulin complexes onto the microtubule bundles, microtubule nucleation and bundling, accompanied by minus-end-directed motility, drive the centrifugal development of the phragmoplast.

Visualization of mouse nodal cilia and nodal flow

The earliest left-right asymmetry in mouse development arises in 7.5 days, at the ventral surface of the embryonic node. The node cells possess monocilia beating in rotatory fashion to generate fluid flow from the right to the left (nodal flow). The direction of nodal flow will determine the side of expression of nodal, the responsible gene for "leftness." Nodal flow is visualized by combination of DIC (differential interference contrast) and microbeads in culture medium. Node cilia movement is visualized by DIC, a high-speed camera, and image processing.

High-speed imaging of amoeboid movements using light-sheet microscopy

Light-sheet microscopy has been developed as a powerful tool for live imaging in biological studies. The efficient illumination of specimens using light-sheet microscopy makes it highly amenable to high-speed imaging. We therefore applied this technology to the observation of amoeboid movements, which are too rapid to capture with conventional microscopy. To simplify the setup of the optical system, we utilized the illumination optics from a conventional confocal laser scanning microscope. Using this set-up we achieved high-speed imaging of amoeboid movements. Three-dimensional images were captured at the recording rate of 40 frames/s and clearly outlined the fine structures of fluorescent-labeled amoeboid cellular membranes. The quality of images obtained by our system was sufficient for subsequent quantitative analysis for dynamics of amoeboid movements. This study demonstrates the application of light-sheet microscopy for high-speed imaging of biological specimens.

Cilia at the node of mouse embryos sense fluid flow for left-right determination via Pkd2

Unidirectional fluid flow plays an essential role in the breaking of left-right (L-R) symmetry in mouse embryos, but it has remained unclear how the flow is sensed by the embryo. We report that the Ca(2+) channel Polycystin-2 (Pkd2) is required specifically in the perinodal crown cells for sensing the nodal flow. Examination of mutant forms of Pkd2 shows that the ciliary localization of Pkd2 is essential for correct L-R patterning. Whereas Kif3a mutant embryos, which lack all cilia, failed to respond to an artificial flow, restoration of primary cilia in crown cells rescued the response to the flow. Our results thus suggest that nodal flow is sensed in a manner dependent on Pkd2 by the cilia of crown cells located at the edge of the node.

Migration of neuronal precursors from the telencephalic ventricular zone into the olfactory bulb in adult zebrafish

In the brain of adult mammals, neuronal precursors are generated in the subventricular zone in the lateral wall of the lateral ventricles and migrate into the olfactory bulbs (OBs) through a well-studied route called the rostral migratory stream (RMS). Recent studies have revealed that a comparable neural stem cell niche is widely conserved at the ventricular wall of adult vertebrates. However, little is known about the migration route of neuronal precursors in nonmammalian adult brains. Here, we show that, in the adult zebrafish, a cluster of neuronal precursors generated in the telencephalic ventricular zone migrates into the OB via a route equivalent to the mammalian RMS. Unlike the mammalian RMS, these neuronal precursors are not surrounded by glial tubes, although radial glial cells with a single cilium lined the telencephalic ventricular wall, much as in embryonic and neonatal mammals. To observe the migrating neuronal precursors in living brain tissue, we established a brain hemisphere culture using a zebrafish line carrying a GFP transgene driven by the neurogenin1 (ngn1) promoter. In these fish, GFP was observed in the neuronal precursors migrating in the RMS, some of which were aligned with blood vessels. Numerous ngn1:gfp-positive cells were observed migrating tangentially in the RMS-like route medial to the OB. Taken together, our results suggest that the RMS in the adult zebrafish telencephalon is a functional migratory pathway. This is the first evidence for the tangential migration of neuronal precursors in a nonmammalian adult telencephalon.

Cell movements of the deep layer of non-neural ectoderm underlie complete neural tube closure in Xenopus

In developing vertebrates, the neural tube forms from a sheet of neural ectoderm by complex cell movements and morphogenesis. Convergent extension movements and the apical constriction along with apical-basal elongation of cells in the neural ectoderm are thought to be essential for the neural tube closure (NTC) process. In addition, it is known that non-neural ectoderm also plays a crucial role in this process, as the neural tube fails to close in the absence of this tissue in chick and axolotl. However, the cellular and molecular mechanisms by which it functions in NTC are as yet unclear. We demonstrate here that the non-neural superficial epithelium moves in the direction of tensile forces applied along the dorsal-ventral axis during NTC. We found that this force is partly attributable to the deep layer of non-neural ectoderm cells, which moved collectively towards the dorsal midline along with the superficial layer. Moreover, inhibition of this movement by deleting integrin β1 function resulted in incomplete NTC. Furthermore, we demonstrated that other proposed mechanisms, such as oriented cell division, cell rearrangement and cell-shape changes have no or only minor roles in the non-neural movement. This study is the first to demonstrate dorsally oriented deep-cell migration in non-neural ectoderm, and suggests that a global reorganization of embryo tissues is involved in NTC.

Planar polarity of multiciliated ependymal cells involves the anterior migration of basal bodies regulated by non-muscle myosin II

Motile cilia generate constant fluid flow over epithelial tissue, and thereby influence diverse physiological processes. Such functions of ciliated cells depend on the planar polarity of the cilia and on their basal bodies being oriented in the downstream direction of fluid flow. Recently, another type of basal body planar polarity, characterized by the anterior localization of the basal bodies in individual cells, was reported in the multiciliated ependymal cells that line the surface of brain ventricles. However, little is known about the cellular and molecular mechanisms by which this polarity is established. Here, we report in mice that basal bodies move in the apical cell membrane during differentiation to accumulate in the anterior region of ependymal cells. The planar cell polarity signaling pathway influences basal body orientation, but not their anterior migration, in the neonatal brain. Moreover, we show by pharmacological and genetic studies that non-muscle myosin II is a key regulator of this distribution of basal bodies. This study demonstrates that the orientation and distribution of basal bodies occur by distinct mechanisms.

Planar polarization of node cells determines the rotational axis of node cilia

Rotational movement of the node cilia generates a leftward fluid flow in the mouse embryo because the cilia are posteriorly tilted. However, it is not known how anterior-posterior information is translated into the posterior tilt of the node cilia. Here, we show that the basal body of node cilia is initially positioned centrally but then gradually shifts toward the posterior side of the node cells. Positioning of the basal body and unidirectional flow were found to be impaired in compound mutant mice lacking Dvl genes. Whereas the basal body was normally positioned in the node cells of Wnt3a(-/-) embryos, inhibition of Rac1, a component of the noncanonical Wnt signalling pathway, impaired the polarized localization of the basal body in wild-type embryos. Dvl2 and Dvl3 proteins were found to be localized to the apical side of the node cells, and their location was polarized to the posterior side of the cells before the posterior positioning of the basal body. These results suggest that posterior positioning of the basal body, which provides the posterior tilt to node cilia, is determined by planar polarization mediated by noncanonical Wnt signalling.

Feasibility of endoscopic mucosal resection for superficial pharyngeal cancer: a minimally invasive treatment

BACKGROUND AND STUDY AIMS

New diagnostic techniques have recently been developed so detection of superficial pharyngeal cancer is dramatically increasing and endoscopic mucosal resection (EMR) can now be performed on an experimental basis. The aim of this study was to clarify the effectiveness of EMR for superficial pharyngeal cancer.

PATIENTS AND METHODS

Between 2004 and 2007, 31 patients with 37 pharyngeal lesions underwent EMR at our hospital. EMR using a cap-fitted endoscope (EMR-C) was used on 34 lesions and strip biopsies on the remaining three. We retrospectively assessed the effectiveness of those procedures in treating superficial pharyngeal cancer.

RESULTS

Median procedure time was 45 minutes (range 20 - 180 minutes) and median hospital stay was 7 days (range 4 - 12 days). Regarding complications, one patient experienced laryngeal edema, one suffered aspiration pneumonia, and two sustained dermatitis around the mouth caused by Lugol staining. Histologically, 18 lesions were confirmed as carcinoma in situ and the other 19 lesions demonstrated microinvasion of the subepithelial tissue with lymphatic invasion in one case. During the median follow-up period of 40 months (range 21 - 62 months), two patients received radiotherapy and two patients underwent an additional EMR because of recurrent tumors. Five other patients developed metachronous superficial pharyngeal cancers, but all those lesions were resected primarily by EMR while two of the study's 31 patients died from esophageal cancer. None of the remaining 20 patients experienced any recurrent or metachronous tumors during their follow-up periods.

CONCLUSIONS

Our results indicated that EMR was a safe, effective, and minimally invasive treatment for superficial pharyngeal cancer.

Lateral supraorbital keyhole approach to clip unruptured anterior communicating artery aneurysms

OBJECT

Clipping of an anterior communicating artery (A-com A) aneurysm requires various working angles for safe manipulation and observation. The lateral supraorbital keyhole approach provides a more lateral subfrontal corridor to observe and clip an A-com A aneurysm than the standard Perneczky method.

METHODS

Preoperative planning was individualized in each patient based on three-dimensional computed tomography (3D-CT) angiography and 3D-CT osteotomy planning images. The procedure consisted of a 40-50 mm periorbital skin incision, partial dissection of the anterior portion of the temporal muscle, a 35 x 25 mm keyhole minicraniotomy from the supraorbital area to the sphenoid ridge, and opening of the carotid cistern and sylvian fissure in an antegrade fashion. Ten keyhole clipping procedures were performed in 10 patients with unruptured A-com A aneurysms.

RESULTS

No shaving of scalp hair, drain placement, or anticonvulsant medication were required. No patient suffered neurological deficits or abnormal findings on postoperative magnetic resonance imaging. Most patients were discharged on the 2nd to 3rd postoperative days except for one patient who suffered from meningitis.

CONCLUSIONS

The lateral supraorbital keyhole approach is a minimally invasive treatment option for relatively small and unruptured A-com A aneurysms.

Endoscopic diagnosis of pharyngeal carcinoma by NBI

Head and neck cancer, especially pharyngeal cancer, frequently co-exist with esophageal cancer, but pharyngeal cancer has proven difficult to detect in such cases before its progression to an advanced stage. Several recent reports have indicated that narrow-band imaging (NBI) endoscopy with magnification is able to improve the detection of superficial pharyngeal cancer. NBI is a relatively new optical technology based on limiting the depth of light penetration into the mucosa. The recognition of these lesions is dramatically improved and the microvascular structure of the mucosal surface is significantly enhanced by NBI. As a result, NBI enables more accurate diagnosis and increases the detection rate of superficial pharyngeal cancer. This particular field has only been developed in recent years, however, and there are still a number of problems that need to be addressed in the future. It will be necessary to accumulate and evaluate resected specimens and follow up patients in order to establish the appropriate criteria for curative endoscopic treatment in these patients. The ease in using NBI in combination with this new diagnostic concept based on microvascular changes makes NBI suitable for worldwide use in the future.

Salsolinol is present in the bovine posterior pituitary gland and stimulates the release of prolactin both in vivo and in vitro in ruminants

The aims of the present study were to determine whether salsolinol (SAL), a dopamine-related compound, is present in the bovine posterior pituitary (PP) gland, and to clarify the effect of SAL on the secretion of prolactin (PRL) in ruminants. SAL was detected in extract of bovine PP gland using high-pressure liquid chromatography with electrochemical detection (HPLC-EC). A single intravenous (i.v.) injection of SAL (5 and 10mg/kg body weight) significantly and dose-dependently stimulated the release of PRL in goats (P<0.05). Plasma PRL levels reached a peak 10min after the injection, then gradually returned to basal values in 60-80min. The PRL-releasing pattern was similar to that in response to sulpiride (a dopamine receptor antagonist). The intracerebroventricular (i.c.v.) injection of 1mg of SAL had no significant effect on the release of PRL in calves, however, 5mg significantly stimulated the release (P<0.05) with peak values reached 30-40min after the injection. Moreover, SAL significantly stimulated the release of PRL from cultured bovine anterior pituitary cells at doses of 10(-6) and 10(-5)M, compared to control cells (P<0.05). Taken together, our data clearly show that SAL is present in extract of the PP gland of ruminants, and has PRL-releasing activity both in vivo and in vitro. Therefore, this endogenous compound is a strong candidate for the factor having PRL-releasing activity that has been previously detected in extract of the bovine PP gland.

Cilia: tuning in to the cell's antenna

Cilia are microtubule-based organelles that project like antennae from the surface of most cells in the body. Motile cilia move fluid past cells, for example mucus in the airway. Non-motile primary cilia, however, transduce a multitude of sensory stimuli, including chemical concentrations of growth factors, hormones, odorants, and developmental morphogens, as well as osmolarity, light intensity, and fluid flow. Cilia have evolved a complex ultrastructure to accommodate these diverse functions, and an extensive molecular machinery has developed to support the assembly of these organelles. Defects in the cilia themselves, or the machinery required to assemble them, lead to a broad spectrum of human disease symptoms, including polycystic kidney disease, nephronophthisis, hydrocephalus, polydactyly, situs inversus, retinal degeneration, and obesity. While these diseases highlight the pivotal roles of cilia in physiology and development, the mechanistic link between cilia, physiology, and disease remains unclear.

De novo formation of left-right asymmetry by posterior tilt of nodal cilia

In the developing mouse embryo, leftward fluid flow on the ventral side of the node determines left-right (L-R) asymmetry. However, the mechanism by which the rotational movement of node cilia can generate a unidirectional flow remains hypothetical. Here we have addressed this question by motion and morphological analyses of the node cilia and by fluid dynamic model experiments. We found that the cilia stand, not perpendicular to the node surface, but tilted posteriorly. We further confirmed that such posterior tilt can produce leftward flow in model experiments. These results strongly suggest that L-R asymmetry is not the descendant of pre-existing L-R asymmetry within each cell but is generated de novo by combining three sources of spatial information: antero-posterior and dorso-ventral axes, and the chirality of ciliary movement.

Bovine Posterior Pituitary Extract Stimulates Prolactin Release from the Anterior Pituitary Gland In Vitro and In Vivo in Cattle

It has been reported that the posterior pituitary (PP) gland contains a potent, unknown prolactin (PRL)-releasing factor (PRF) in rats. PRFs are assumed to be produced in neurones located within the hypothalamus, and to be peptidergic in nature. However, little is known about PRFs in domestic animals. To characterize the PRF in the PP of domestic animals, the present study examined the PRL-releasing activity of an acidic extract from bovine PP (bPP) in vitro and in vivo in cattle. First, the PRL-releasing effect of bPP extract was compared with that of PRL-releasing peptide (PrRP), and thyrotropin-releasing hormone (TRH) from cultured bovine anterior pituitary cells. The extract significantly increased PRL concentrations in the culture medium, at doses of 0.002 and 0.02 eq./ml (one eq. is the PP extract from one animal), compared with the control (p < 0.05). PrRP failed to stimulate the release of PRL. TRH significantly increased PRL concentrations in the culture medium, at doses from 10(-9) to 10(-7) M, compared with the control (p < 0.05). The rate of increase in the PRL concentration, by 0.02 eq./ml bPP extract, was significantly greater than that in TRH (p < 0.05). Secondly, plasma PRL responses to the intravenous (i.v.) injection of bPP extract (0.5 eq./head), PrRP [3.59 mug/kg body weight (BW)], TRH (1 mug/kg BW), and a dopamine receptor antagonist (sulpiride, 0.1 mg/kg BW), were examined in calves. PrRP failed to stimulate PRL release; however, plasma PRL increased immediately following the injection of bPP extract, TRH and sulpiride. The PRL-releasing effect of i.v. injections of TRH and sulpiride was more potent than that of bPP extract. Finally, plasma PRL responses to the intra-hypothalamic injection of bPP extract were examined in calves. The intra-hypothalamic infusion (arcuate nucleus) of 0.0625 eq./head of bPP extract strongly stimulated PRL release in calves (p < 0.05). The present results show that PP contains a physiologically potent PRF in cattle.