Dorsal Zone Research Articles

Cdx1 and Gsc distinctly regulate the transcription of BMP4 target gene ventx3.2 by directly binding to the proximal promoter region in Xenopus gastrulae

A comprehensive regulatory network of transcription factors controls the dorsoventral patterning of the body axis in developing vertebrate embryos. Bone morphogenetic protein signaling is essential for activating the Ventx family of homeodomain transcription factors, which regulates embryonic patterning and germ layer identity during Xenopus gastrulation. Although Ventx1.1 and Ventx2.1 of the Xenopus Ventx family have been extensively investigated, Ventx3.2 remains largely understudied. Therefore, this study aimed to investigate the transcriptional regulation of ventx3.2 during the embryonic development of Xenopus. We used goosecoid (Gsc) genome-wide chromatin immunoprecipitation-sequencing data to isolate and replicate the promoter region of ventx3.2. Serial deletion and site-directed mutagenesis were used to identify the cis-acting elements for Gsc and caudal type homeobox 1 (Cdx1) within the ventx3.2 promoter. Cdx1 and Gsc differentially regulated ventx3.2 transcription in this study. Additionally, positive cis-acting and negative response elements were observed for Cdx1 and Gsc, respectively, within the 5' flanking region of the ventx3.2 promoter. This result was corroborated by mapping the active Cdx1 response element (CRE) and Gsc response element (GRE). Moreover, a point mutation within the CRE and GRE completely abolished the activator and repressive activities of Cdx1 and Gsc, respectively. Furthermore, the chromatin immunoprecipitation-polymerase chain reaction confirmed the direct binding of Cdx1 and Gsc to the CRE and GRE, respectively. Inhibition of Cdx1 and Gsc activities at their respective functional regions, namely, the ventral marginal zone and dorsal marginal zone, reversed their effects on ventx3.2 transcription. These results indicate that Cdx1 and Gsc modulate ventx3.2 transcription in the ventral marginal zone and dorsal marginal zone by directly binding to the promoter region during Xenopus gastrulation.

Ontogenetic Expression of Aquaporins in the Kidney and Urinary Bladder of the Japanese Tree Frog, Dryophytes japonicus.

For adult anuran amphibians, the kidney and urinary bladder play important osmoregulatory roles through water reabsorption. In the present study, we have examined ontogenetic expression of aquaporins, i.e., AQP2, AQPamU (AQP6ub, AQPa2U), and AQP3, in these organs using the Japanese tree frog, Dryophytes japonicus. Immunohistochemistry using the metamorphosing larvae at stages 40-43 localized AQP2 protein to the collecting ducts in the dorsal zone of the mesonephric kidney. At prometamorphic stages 40 and 41, labelling of AQP2 protein was observed in the apical/ subapical regions of the collecting duct cells. At climax stages 42 and 43, labels for AQP2 and AQP3 became observed in the apical/subapical regions and basolateral membrane of the collecting duct cells, respectively, as seen in the adults. As for the urinary bladder, immuno-positive labels for AQPamU were localized to the apical/subapical regions of granular cells in the mucosal epithelium at stages 40-43. On the other hand, AQP3 immunoreactivity was hardly observed in the urinary bladder at stage 40, and weakly appeared in many granular cells at stage 41. Thereafter, labels for AQP3 became evident along the basolateral membrane of granular cells at stages 42 and 43, together with AQPamU in the apical/subapical regions. These results suggest that the kidney and urinary bladder might be capable of water reabsorption, via AQP2, AQPamU, and AQP3, at stage 42, contributing to the acclimation of the tree frogs to terrestrial environments.

Altered functional connectivity of insular subregions in subjective cognitive decline.

Recent research has highlighted the insula as a critical hub in human brain networks and the most susceptible region to subjective cognitive decline (SCD). However, the changes in functional connectivity of insular subregions in SCD patients remain poorly understood. The present study aims to clarify the altered functional connectivity patterns within insular subregions in individuals with SCD using resting-state functional magnetic resonance imaging (rs-fMRI). In this study, we collected rs-fMRI data from 30 patients with SCD and 28 healthy controls (HCs). By defining three subregions of the insula, we mapped whole-brain resting-state functional connectivity (RSFC). We identified several distinct RSFC patterns of the insular subregions. Specifically, for positive connectivity, three cognitive-related RSFC patterns were identified within the insula, suggesting anterior-to-posterior functional subdivisions: (1) a dorsal anterior zone of the insula that shows RSFC with the executive control network (ECN); (2) a ventral anterior zone of the insula that shows functional connectivity with the salience network (SN); and (3) a posterior zone along the insula that shows functional connectivity with the sensorimotor network (SMN). Compared to the controls, patients with SCD exhibited increased positive RSFC to the sub-region of the insula, demonstrating compensatory plasticity. Furthermore, these abnormal insular subregion RSFCs are closely correlated with cognitive performance in the SCD patients. Our findings suggest that different insular subregions exhibit distinct patterns of RSFC with various functional networks, which are affected differently in patients with SCD.

Dynamic changes characteristics of the spermatozoon during the reproductive process of mud crab (Scylla paramamosain): From spermatophore formation, transportation to dispersion

To enhance comprehension of the destiny of the spermatozoon throughout the reproductive process of mud crab (Scylla paramamosain) is important for achieving large-scale artificial breeding of Scylla. The reproductive systems of sexually mature male and female mud crabs were studied, utilizing the histomorphological method. The spermatozoon traveled from testicular lobules through the seminiferous duct, into the anterior vas deferens (AVD) via the collecting duct. The spermatophore wall formed at the end of the AVD. During copulation, spermatophores stored in the median vas deferens (MVD) were transferred to the seminal receptacle through the posterior vas deferens (PVD), ejaculatory duct, and gonopod, with seminal plasma secreted by both MVD and PVD together. After mating, the sperm plug was formed within the seminal receptacle's ventral zone. At ovary stage Ⅲ, the spermatophore wall ruptured, and the sperm plug disappeared. Bundled sperm packets congregated into a dense mass, while a few spermatozoa dispersed along the intermediate chamber to the dorsal zone. At ovary stage Ⅳ, the dorsal zone also exhibited a dense sperm mass due to increased dispersal. At ovary stage Ⅴ, merely a modest portion of the dense sperm mass remained in the ventral zone, and the rest dissociated and dispersed within the seminal receptacle. Following ovulation, sperm mass remained in the ventral zone, re-dissociating and re-dispersing once ovarian development reached stage Ⅲ again. The phased dispersion supply mode of spermatozoa behind multiple ovipositions was unveiled. Furthermore, we observed the ultrastructural changes in the spermatozoon during the process of the capacitation, including operculum widening, actin-containing substance accumulation, and the density of chromatin in the nucleus decreased. As presented herein, the elucidation of the dynamic changes of the spermatozoon, as well as the pattern of spermatozoa supply, contributes significantly to our enhanced comprehension of the reproductive biology of Scylla.

Analyses of transcutaneous oxygen pressure values stratified for foot angiosomes to predict diabetic foot ulcer healing

AimsPrevious research suggested that diabetic foot ulcer (DFU) location could affect transcutaneous oxygen pressure (TcPO2) values following the angiosome concept. Up to our knowledge no studies have yet analyzed if the location of a diabetic foot ulcer can be a confounding factor that modifies TcPO2 values. The primary aim of this study was to compare the potential healing prognosis of TcPO2 differentiated for diabetic foot ulcers in different angiosome locations. Methodsa 2-years observational cohort prospective study was performed in 81 patients with diabetic foot ulcers. Transcutaneous oxygen pressure measurements were performed at baseline by placing the electrode on two different angiosomes: dorsal zone of the foot (dorsalis pedis angiosome) and between the navicular bone and the tibial malleolus (posterior tibial angiosome). The main outcome was establishing the effectiveness of TcPO2 measurements (dorsalis pedis angiosome and posterior tibial angiosome) for predicting DFU healing. ResultsTranscutaneous oxygen pressure probe placed in the dorsum of the foot (dorsalis pedis angiosome) yielded a sensitivity (S) of 95 % and specificity (SP) of 73 %, and an area under the curve (AUC) of 0.902 (p < 0.001 [0.84–0.96]) for ulcers located in the forefoot and toes; while TcPO2 placed in the posterior tibial angiosome yielded an S of 100 % and SP of 85 % and an AUC of 0.894 (p < 0.001 [0-822-0.966]) for DFU located in the midfoot and heel. ConclusionThis study suggests that angiosome-guided TcPO2 contributes to a prognosis of successful foot ulcer healing.

Distribution of transpulmonary pressure during one-lung ventilation in pigs at different body positions.

Background. Global and regional transpulmonary pressure (PL) during one-lung ventilation (OLV) is poorly characterized. We hypothesized that global and regional PL and driving PL (ΔPL) increase during protective low tidal volume OLV compared to two-lung ventilation (TLV), and vary with body position. Methods. In sixteen anesthetized juvenile pigs, intra-pleural pressure sensors were placed in ventral, dorsal, and caudal zones of the left hemithorax by video-assisted thoracoscopy. A right thoracotomy was performed and lipopolysaccharide administered intravenously to mimic the inflammatory response due to thoracic surgery. Animals were ventilated in a volume-controlled mode with a tidal volume (VT) of 6mLkg-1 during TLV and of 5mLkg-1 during OLV and a positive end-expiratory pressure (PEEP) of 5 cmH2O. Global and local transpulmonary pressures were calculated. Lung instability was defined as end-expiratory PL<2.9 cmH2O according to previous investigations. Variables were acquired during TLV (TLVsupine), left lung ventilation in supine (OLVsupine), semilateral (OLVsemilateral), lateral (OLVlateral) and prone (OLVprone) positions randomized according to Latin-square sequence. Effects of position were tested using repeated measures ANOVA. Results. End-expiratory PL and ΔPL were higher during OLVsupine than TLVsupine. During OLV, regional end-inspiratory PL and ΔPL did not differ significantly among body positions. Yet, end-expiratory PL was lower in semilateral (ventral: 4.8 ± 2.9 cmH2O; caudal: 3.1 ± 2.6 cmH2O) and lateral (ventral: 1.9 ± 3.3 cmH2O; caudal: 2.7 ± 1.7 cmH2O) compared to supine (ventral: 4.8 ± 2.9 cmH2O; caudal: 3.1 ± 2.6 cmH2O) and prone position (ventral: 1.7 ± 2.5 cmH2O; caudal: 3.3 ± 1.6 cmH2O), mainly in ventral (p ≤ 0.001) and caudal (p = 0.007) regions. Lung instability was detected more often in semilateral (26 out of 48 measurements; p = 0.012) and lateral (29 out of 48 measurements, p < 0.001) as compared to supine position (15 out of 48 measurements), and more often in lateral as compared to prone position (19 out of 48 measurements, p = 0.027). Conclusion. Compared to TLV, OLV increased lung stress. Body position did not affect stress of the ventilated lung during OLV, but lung stability was lowest in semilateral and lateral decubitus position.

Determination of Al(III), Pb(II), and Cu(II) in Gunshot Residue Using Amino-Functionalized Silica Adsorbents in Dispersive Solid Phase Microextraction (DSPME) with Capillary Electrophoresis (CE)

Here is reported the design, synthesis, and application of an amino silica adsorbent for the extraction and determination of Al(III), Pb(II), and Cu(II) in gunshot residue (GSR) from the dorsal and palmar zones by capillary electrophoresis. The extraction procedure was used to determine the adsorbent composition by varying the molar ratio of the cross-linking agent tetramethyl orthosilicate (TMOS) and the functional monomer 3-aminopropyl trimethoxysilane (APTMS). (5.0:0.0 to 0.0:5.0). The optimal composition (3.0:2.0) was characterized using Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and adsorption isotherm analysis. A univariate method was used to optimize critical factors in dispersive solid phase microextraction (DSPME), including the adsorbent mass, contact time, sample volume, and elution solution. Using the optimal conditions (adsorbent, 10 mg; contact time, 10 min; sample volume, 5 mL; eluent solution, methanol/10−1 mol L−1 HNO3), the method provides limits of detection of 0.06 mg L−1 for Pb(II), 0.08 mg L−1 for Cu(II), and 0.11 mg L−1 for Al(III). The precision and accuracy were evaluated in terms of inter- and intra-day repeatability (n = 3) with a relative standard deviation below 10%. The developed method was applied for gunshot residue analysis, providing concentrations from 12.6 to 702 mg L−1 for Al(III), 11.8 to 280 mg L−1 for Pb(II), and 29.8 to 395.6 mg L−1 for Cu(II).

Deafness induces complete crossmodal plasticity in a belt region of dorsal auditory cortex.

Many neural areas, where patterned activity is lost following deafness, have the capacity to become activated by the remaining sensory systems. This crossmodal plasticity can be measured at perceptual/behavioural as well as physiological levels. The dorsal zone (DZ) of auditory cortex of deaf cats is involved in supranormal visual motion detection, but its physiological level of crossmodal reorganisation is not well understood. The present study of early-deaf DZ (and hearing controls) used multiple single-channel recording methods to examine neuronal responses to visual, auditory, somatosensory and combined stimulation. In early-deaf DZ, no auditory activation was observed, but 100% of the neurons were responsive to visual cues of which 21% were also influenced by somatosensory stimulation. Visual and somatosensory responses were not anatomically organised as they are in hearing cats, and fewer multisensory neurons were present in the deaf condition. These crossmodal physiological results closely correspond with and support the perceptual/behavioural enhancements that occur following hearing loss.

SRY-box Transcription Factor 6 Is Expressed Not Only in the Dorsal but Also in the Ventral Zone of the Neural Tube and Is Highly Expressed in the Notochord and Chordoma

In the course of SRY-box transcription factor 6 (SOX6) expression profiling in human embryonic tissue, SOX 6 was found to be highly expressed in the notochord, based on the findings of immunohistochemistry (IHC). Sox6 is also expressed in the neural tube and the distribution of SOX6 is located in the ventral and dorsal zones of the neural tube. In contrast to the findings that SOX6-positive cells were located on the floor plate of the neural tube, OLIG2- and NKX2.2-expressing cells were lacking on the floor plate of the neural tube, and their expression was restricted only to the ventral zone of the neural tube. The expression patterns of SOX9 were similar to those of OLIG2 and NKX2.2 in the neural tube. NKX2.2 and OLIG2 are not expressed in the notochord, but SOX9 and SOX6 are. Because Sox6 is highly expressed in the notochord, the present study investigated whether or not SOX6 is an immunohistochemical marker for the pathologic diagnosis of chordoma, a neoplasm derived from the notochord. IHC revealed that chordoma was strongly positive for SOX6 in two cases of chordoma, one of which occurred in the sacrococcygeal region and another that developed at the base of the skull, suggesting that SOX6 is a useful marker for the histopathologic diagnosis of chordoma.

Microscopical Analysis of Autofluorescence as a Complementary and Useful Method to Assess Differences in Anatomy and Structural Distribution Underlying Evolutive Variation in Loss of Seed Dispersal in Common Bean.

The common bean has received attention as a model plant for legume studies, but little information is available about the morphology of its pods and the relation of this morphology to the loss of seed dispersal and/or the pod string, which are key agronomic traits of legume domestication. Dehiscence is related to the pod morphology and anatomy of pod tissues because of the weakening of the dorsal and ventral dehiscence zones and the tensions of the pod walls. These tensions are produced by the differential mechanical properties of lignified and non-lignified tissues and changes in turgor associated with fruit maturation. In this research, we histologically studied the dehiscence zone of the ventral and dorsal sutures of the pod in two contrasting genotypes for the dehiscence and string, by comparing different histochemical methods with autofluorescence. We found that the secondary cell wall modifications of the ventral suture of the pod were clearly different between the dehiscence-susceptible and stringy PHA1037 and the dehiscence-resistant and stringless PHA0595 genotypes. The susceptible genotype had cells of bundle caps arranged in a more easily breakable bowtie knot shape. The resistant genotype had a larger vascular bundle area and larger fibre cap cells (FCCs), and due to their thickness, the external valve margin cells were significantly stronger than those from PHA1037. Our findings suggest that the FCC area, and the cell arrangement in the bundle cap, might be partial structures involved in the pod dehiscence of the common bean. The autofluorescence pattern at the ventral suture allowed us to quickly identify the dehiscent phenotype and gain a better understanding of cell wall tissue modifications that took place along the bean's evolution, which had an impact on crop improvement. We report a simple autofluorescence protocol to reliably identify secondary cell wall organization and its relationship to the dehiscence and string in the common bean.

Experimental study of the thermal probing depth of a skin calorimeter

In this work we perform an experimental study of the thermal probing depth of a skin calorimeter developed to measure in vivo the heat capacity and the thermal resistance of a 4 cm2 skin region. To determine these properties, a small thermal excitation is applied to the skin and then, the static and dynamic response of the calorimetric signal is studied. This excitation consists of a periodic change of the calorimeter thermostat temperature while the device is applied on the skin. We have found that the thermal penetration depth depends mainly on the period of this periodic thermal excitation. This time dependence is exponential for non-semi-infinite domains. Using a time–variant model, we performed measurements on the dorsal and volar areas of the left wrist of a healthy 64-year-old male subject. For a 4 cm2 region of skin, the results show that the heat capacity in both zones are of the same order of magnitude. Its initial value is 4 J/K and increases exponentially up to 7 J/K with a time constant of 6.5 min. Thermal resistance also increases exponentially with time: from 27 to 36 K/W for the volar zone, and from 32 to 45 K/W for the dorsal zone.

Two new Raabena species and a new Pararaabena species (Ciliophora, Entodiniomorphida) with redescriptions of Raabena bella and Pararaabena dentata

The genera Raabena and Pararaabena (Ciliophora, Entodiniomorphida, Blepharocorythidae) were monospecific, and their type species are Raabena bella Wolska, 1967 and Pararaabena dentata Wolska, 1968. They have been found in Asian elephants and closely resemble each other: ovoid and laterally compressed body; non-retractable adoral ciliary zone; funnel-shaped vestibulum; three non-retractable somatic ciliary arches. Furthermore, the positional relationship between the vestibular ciliary zone and the anterior dorsal ciliary zone identifies Raabena and Pararaabena: these two ciliary zones are connected in Raabena while they are separated in Pararaabena. While investigating entodiniomorphid ciliates of Asian elephants, the author often encountered ciliates similar to Raabena bella but with a sinuous body or with a small body and ciliates similar to Pararaabena dentata but with a slender body or with no or two caudal lobes. In this study, their general morphology and infraciliature were compared to R. bella and P. dentata to know whether they are new species or morphological variations in a species. As a result, the present study redescribed R. bella and P. dentata, and described R. sinuosa n. sp., R. bellafilia n. sp., P. gracilis n. sp., and morphotypes of P. dentata.

The complete dorsal structure is formed from only the blastocoel roof of Xenopus blastula: insight into the gastrulation movement evolutionarily conserved among chordates

Gastrulation is a critical event whose molecular mechanisms are thought to be conserved among vertebrates. However, the morphological movement during gastrulation appears to be divergent across species, making it difficult to discuss the evolution of the process. Previously, we proposed a novel amphibian gastrulation model, the “subduction and zippering (S&Z) model”. In this model, the organizer and the prospective neuroectoderm are originally localized in the blastula’s blastocoel roof, and these embryonic regions move downward to make physical contact of their inner surfaces with each other at the dorsal marginal zone. The developmental stage when contact between the head organizer and the anterior-most neuroectoderm is established is called “anterior contact establishment (ACE).” After ACE, the A-P body axis elongates posteriorly. According to this model, the body axis is derived from limited regions of the dorsal marginal zone at ACE. To investigate this possibility, we conducted stepwise tissue deletions using Xenopus laevis embryos and revealed that the dorsal one-third of the marginal zone had the ability to form the complete dorsal structure by itself. Furthermore, a blastocoel roof explant of the blastula, which should contain the organizer and the prospective neuroectoderm in the S&Z model, autonomously underwent gastrulation and formed the complete dorsal structure. Collectively, these results are consistent with the S&Z gastrulation model and identify the embryonic region sufficient for construction of the complete dorsal structure. Finally, by comparing amphibian gastrulation to gastrulation of protochordates and amniotes, we discuss the gastrulation movement evolutionarily conserved among chordates.

Capacity for LDL (Low-Density Lipoprotein) Retention Predicts the Course of Atherogenesis in the Murine Aortic Arch.

To cause atherosclerosis, LDLs (low-density lipoproteins) must first pass through the endothelium and then become retained in the arterial matrix. Which of these two processes is rate-limiting and predicts the topography of plaque formation remains controversial. To investigate this issue, we performed high-resolution mapping of LDL entry and retention in murine aortic arches before and during atherosclerosis development. Maps of LDL entry and retention were created by injecting fluorescently labeled LDL followed by near-infrared scanning and whole-mount confocal microscopy after 1 hour (entry) and 18 hours (retention). By comparing arches between normal mice and mice with short-term hypercholesterolemia, we analyzed changes in LDL entry and retention during the LDL accumulation phase that precedes plaque formation. Experiments were designed to secure equal plasma clearance of labeled LDL in both conditions. We found that LDL retention is the overall limiting factor for LDL accumulation but that the capacity for LDL retention varied substantially over surprisingly short distances. The inner curvature region, previously considered a homogenous atherosclerosis-prone region, consisted of dorsal and ventral zones with high capacity and a central zone with low capacity for continued LDL retention. These features predicted the temporal pattern of atherosclerosis, which first appeared in the border zones and later in the central zone. The limit to LDL retention in the central zone was intrinsic to the arterial wall, possibly caused by saturation of the binding mechanism, and was lost upon conversion to atherosclerotic lesions. Capacity for continued LDL retention varies over short distances and predicts where and when atherosclerosis develops in the mouse aortic arch.

Профили астроцитарной дифференцировки переднего мозга человека на внутриутробном этапе онтогенеза

Introduction. Brain functioning is kept by both neuronal cell activity and macroglia, i.e., astrocytes and oligodendrocytes. The current data on the prenatal development of the human brain are scarce, and gliogenesis is less studied than cortical neurogenesis. Normal limits and variations and spatiotemporal patterns of glial differentiation in human brain development remain poorly studied. Materials and methods. We used human fetal autopsy samples from the Collection of the Laboratory of Nervous System Development of Avtsyn Research Institute of Human Morphology. For immune and morphological analysis, samples of 38 fetal cerebral hemispheres at stages from 8 postconceptional weeks to birth were chosen. Results. We provided the results of the pilot comparative immune and morphological study with the panel of markers (GFAP, ALDH1L1, FABP-7) of the fetal human telencephalon in prenatal ontogenesis. Specific differentiation and maturation of the astrocyte population on the telencephalon start before early fetal period (12–13 gestational weeks). GFAP+ and ALDH1L1+ astrocyte populations in early human telencephalon are still to be studied for their homology. Analysis of GFAP+ and ALDH1L1+ glioblast distribution proposes dorsal proliferative zone as a source for fibrous cortical astrocytes. Comparative immune and morphological analysis of FABP-7+ neuroblasts in the fetal telencephalon questions whether FABP-7 cells belong to astrocyte population at early prenatal human ontogenesis. Conclusion. In the telencephalon, temporal and/or spatiotemporal translational profiles of these three antigens differ, which indicates that the astrocyte population is heterogeneous in early ontogenesis. Keywords: human brain development, telencephalon, glial differentiation, astrocytes, astrocyte fate lineage, GFAP, ALDH1L1, FABP-7

Establishing an Efficient Electroporation-Based Method to Manipulate Target Gene Expression in the Axolotl Brain

The tetrapod salamander species axolotl (Ambystoma mexicanum) is capable of regenerating injured brain. For better understanding the mechanisms of brain regeneration, it is very necessary to establish a rapid and efficient gain-of-function and loss-of-function approaches to study gene function in the axolotl brain. Here, we establish and optimize an electroporation-based method to overexpress or knockout/knockdown target gene in ependymal glial cells (EGCs) in the axolotl telencephalon. By orientating the electrodes, we were able to achieve specific expression of EGFP in EGCs located in dorsal, ventral, medial, or lateral ventricular zones. We then studied the role of Cdc42 in brain regeneration by introducing Cdc42 into EGCs through electroporation, followed by brain injury. Our findings showed that overexpression of Cdc42 in EGCs did not significantly affect EGC proliferation and production of newly born neurons, but it disrupted their apical polarity, as indicated by the loss of the ZO-1 tight junction marker. This disruption led to a ventricular accumulation of newly born neurons, which are failed to migrate into the neuronal layer where they could mature, thus resulted in a delayed brain regeneration phenotype. Furthermore, when electroporating CAS9-gRNA protein complexes against TnC (Tenascin-C) into EGCs of the brain, we achieved an efficient knockdown of TnC. In the electroporation-targeted area, TnC expression is dramatically reduced at both mRNA and protein levels. Overall, this study established a rapid and efficient electroporation-based gene manipulation approach allowing for investigation of gene function in the process of axolotl brain regeneration.

A comparison of multisensory features of two auditory cortical areas: primary (A1) and higher-order dorsal zone (DZ).

From myriads of ongoing stimuli, the brain creates a fused percept of the environment. This process, which culminates in perceptual binding, is presumed to occur through the operations of multisensory neurons that occur throughout the brain. However, because different brain areas receive different inputs and have different cytoarchitechtonics, it would be expected that local multisensory features would also vary across regions. The present study investigated that hypothesis using multiple single-unit recordings from anesthetized cats in response to controlled, electronically-generated separate and combined auditory, visual, and somatosensory stimulation. These results were used to compare the multisensory features of neurons in cat primary auditory cortex (A1) with those identified in the nearby higher-order auditory region, the Dorsal Zone (DZ). Both regions exhibited the same forms of multisensory neurons, albeit in different proportions. Multisensory neurons exhibiting excitatory or inhibitory properties occurred in similar proportions in both areas. Also, multisensory neurons in both areas expressed similar levels of multisensory integration. Because responses to auditory cues alone were so similar to those that included non-auditory stimuli, it is proposed that this effect represents a mechanism by which multisensory neurons subserve the process of perceptual binding.

Microsurgical Methods to Make the Keller Sandwich Explant and the Dorsal Isolate.

This protocol summarizes preparation of the dorsal marginal zone sandwich explant (a.k.a. the "Keller sandwich") and the dorsal isolate from Xenopus embryos. The Keller sandwich is assembled from two early gastrula stage dorsal marginal zone (DMZ) explants. DMZ explants isolated before involution maintain planar patterning processes and block radial signals that might be exchanged between pre- and postinvolution tissues. DMZ explants isolated later in gastrulation, but subsequently opened and flattened may have both planar and radial patterning. The epithelial margins of DMZ explants in Keller sandwiches heal and basal contacts form between the deep layers of the two DMZ explants. The dorsal isolate is dissected from mid- to late-gastrula stage embryos after involution and archenteron formation. Germ-layer contacts between dorsal endoderm, mesoderm, and ectoderm generated by gastrulation movements are maintained in the dorsal isolate. These two explants can be used to study tissue, cell, and subcellular processes relevant to convergent extension, from patterning to cell behaviors, and their collective biomechanics. Skills needed to dissect the Keller sandwich are greater than those needed to dissect animal cap ectoderm and can be mastered in a few weeks; skills needed to dissect the dorsal isolate are similar to those needed to dissect animal caps and can be learned in a week.

Microsurgical Methods to Isolate and Culture the Early Gastrula Dorsal Marginal Zone.

Marginal zone explants from Xenopus embryos can be used to expose cell behaviors and tissue movements that normally operate in dorsal tissues. Dorsal explants comprise the diverse set of progenitor cells found in dorsal tissues including mesendoderm, head mesoderm, prechordal mesoderm, endoderm with bottle cells, axial mesoderm of the prospective notochord, paraxial mesoderm of the somites, lateral plate mesoderm, neural ectoderm, and ectoderm. Unlike an organoid, the dorsal marginal zone (DMZ) explant is "organotypic" in that microsurgery does not disrupt native tissue organization beyond manipulations needed to dissect the tissue from the embryo. An organotypic early gastrula DMZ explant preserves boundaries and close tissue associations in the native marginal zone. Depending on the stage, patterning and cell identities can be maintained in explants and tissue isolates. Local cell movements and behaviors may also be preserved; however, the large-scale biomechanical impact of their collective movements may be altered from those in the native marginal zone. For instance, involution is typically inhibited in the DMZ explant, precluding the two-layer association of mesoderm and prospective neural ectoderm normally achieved during gastrulation. DMZ explants may be mounted and imaged in a variety of ways, exposing interesting cell behaviors or collective movements such as mediolateral cell intercalation in the axial and paraxial mesoderm, apical constriction of bottle cells, and directional migration of mesendoderm. The flattened DMZ explant can also be used to study emergence of new tissue-defining boundaries such as the notochord-somite boundary, the ectoderm-mesoderm boundary, and the mesendoderm-mesoderm boundary.

Hand wounds: An analysis of topography and related damage to underlying structures

IntroductionHand wounds account for 35 to 51% of hand traumas. Damage to underlying anatomical structures depends on the location of the wound. The objective of this study is to describe the topographic distribution of hand wounds allowing for subsequent evaluation of the link between affected surface area and underlying lesion. MethodsWe retrospectively reviewed the medical records of 1058 patients with a total of 1319 wounds over a period of 2 years. Wound location was described according to the cutaneous projection of IFSSH zones for flexors and extensors. Any associated deep lesions were evaluated. Topographical distribution was modeled graphically using a heat-map. We compared the proportion of underlying lesions between each cutaneous zone. Sub-group analysis for lesions’ rate regarding zone groups were performed. Results58.9% of wounds were located on the palmar surface and 41.1% on the dorsal surface. 71% of wounds affected only the digits. The index finger was the most affected. The most damaged region was zone 2 for palmar wounds and zone 3 for dorsal wounds. 45.5% of wounds resulted in injury to a significant underlying anatomical structure. This frequency was 36.4% and 58.5% for palmar and dorsal wounds respectively. More than 50% of wounds in palmar zone 5 and dorsal zones 1, 3, 5, 6 and 7 presented at least one lesion.A lesion of major structure was more frequently found in palmar zone 5 (p <0.001). Dorsally, no zone predominated. Subgroup analysis for dorsal wounds revealed that wounds overlying joints had more major lesions including more tendons injuries and more articular violations with zone 3 presenting a rate of 68%. ConclusionWe provided the first graphical representation for the topographical distribution of hand wounds. Dorsal wounds have a higher association with injury to underlying structures. These results generally support surgical exploration of all hand wounds regardless of their location.Level of evidence: IV Study type: Epidemiological study.