Wnt, Frizzled, and sFRP gene expression patterns during gastrulation in the starfish Patiria (Asterina) pectinifera

Publication date: Available online 23 June 2016
Source:Gene Expression Patterns
Author(s): Narudo Kawai, Ritsu Kuraishi, Hiroyuki Kaneko
By the initial phase of gastrulation, Wnt pathway regulation mediates endomesoderm specification and establishes the animal-vegetal axis, thereby leading to proper gastrulation in starfish. To provide insight into the ancestral mechanism regulating deuterostome gastrulation, we identified the gene expression patterns of Wnt, Frizzled (Fz), and secreted frizzled-related protein (sFRP) family genes, which play a role in the initial stage of the Wnt pathway, in starfish Patiria (Asterina) pectinifera embryos using whole mount in situ hybridization. We identified ten Wnt, four Fz, and two sFRP paralogues. From the hatching blastula to the late gastrula stage, the majority of the Wnt genes and both Fz5/8 and sFRP1/5 were expressed in the posterior and anterior half of the embryo, respectively. Wnt8, Fz1, and Fz4 showed restricted expression in the lateral ectoderm. On the other hand, several genes were expressed de novo in the restricted domain of the archenteron at the late gastrula stage. These results suggest that the canonical and/or non-canonical Wnt pathway might implicate endomesoderm specification, anterior-posterior axis establishment, anterior-posterior patterning, and archenteron morphogenesis in the developmental context of starfish embryos. From comparison with the expression patterns observed in Patria miniata, we consider that the Wnt pathway is conserved among starfishes.



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Analysis of anthocyanin biosynthesis genes expression profiles in contrasting cultivars of Japanese plum (Prunus salicina L.) during fruit development

Publication date: Available online 1 July 2016
Source:Gene Expression Patterns
Author(s): Máximo González, Erika Salazar, Soledad Cabrera, Pilar Olea, Basilio Carrasco
Flavonoids are responsible of different fruit sensorial properties. In Japanese plum (Prunus salicina L.) these compounds are variable in both type and quantity during the different stages of fruit growth and maturation. Here we present the first study which determines the expression profile of structural genes of the flavonoid pathway and accumulation profiles of total phenols, proanthocyanidins and anthocyanins during fruit development stages in contrasting cultivars in Japanese plum. The biosynthesis of these compounds is differentially regulated in different tissues and cultivars. Our result showed that all pigmented tissues increased the expression of the leucoanthocyanidin dioxygenase (LDOX) gene, while all tissues without anthocyanin accumulation presented a minimal expression of LDOX. In addition, the regulation of putative transcription factors PsMYB10 and PsMYB1 were correlated positively and negatively with the pigmented tissues respectively, suggesting a critical and coordinated mechanism involved in the change of the fruit color.



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N-linked glycosylation of Kv1.2 voltage-gated potassium channel facilitates cell surface expression and enhances stability of internalized channels

Abstract

Studies in cultured hippocampal neurons and the COS-7 cell line demonstrate important roles for N-linked glycosylation of Kv1.2 channels in forward trafficking and protein degradation. Kv1.2 channels can contain complex N-linked glycans, which facilitate cell surface expression of the channels. Additionally, the protein stability of cell surface-expressed Kv1.2 channels is affected by glycosylation via differences in degradation of internalized channels. This study reveals the importance of N-linked complex glycosylation in boosting Kv1.2 channel density. Notably, sialic acids at the terminal sugar branches play an important role in dampening degradation of Kv1.2 internalized from the cell membrane to promote its stability.

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Parallel processing of afferent olfactory sensory information

Abstract

Primary olfactory receptor neurons terminate in anatomically and functionally discrete cortical modules known as olfactory bulb glomeruli. The synaptic connectivity and postsynaptic responses of mitral and external tufted cells within the glomerulus may involve both direct and indirect components. For example, it has been suggested that sensory input to mitral cells is indirect through feedforward excitation from external tufted cells. We also observed feedforward excitation of mitral cells with weak stimulation of the olfactory nerve layer, however, focal stimulation of an axon bundle entering an individual glomeruli, revealed that mitral cells receive monosynaptic afferent inputs. Although external tufted cells had a 4.1 fold larger peak EPSC amplitude, integration of the evoked currents showed that the synaptic charge was 5 fold larger in mitral cells, reflecting the prolonged response in mitral cells. Presynaptic afferents onto mitral and external tufted cells had similar quantal amplitude and release probability, suggesting that the larger peak EPSC in external tufted cells resulted from more synaptic contacts. Our results indicate that the monosynaptic afferent input to mitral cells depends on the strength of odorant stimulation. The enhanced spiking we observed in response to brief afferent input provides a mechanism to amplify sensory information and contrasts with the transient response in external tufted cells. These parallel input paths may have discrete functions in processing olfactory sensory input.

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Secondary hyperalgesia is mediated by heat-insensitive A-fibre nociceptors

Abstract

Secondary hyperalgesia refers to the increase in sensitivity to mechanical nociceptive stimuli delivered outside the area of tissue injury. Previous studies suggested that secondary hyperalgesia is mediated by a specific class of myelinated nociceptors: slowly-adapting A-fibre mechano- and heat-sensitive (AMH) Type I nociceptors. Here, we tested this hypothesis by examining, whether long-lasting heat stimuli, which are known to activate AMH-type I nociceptors, elicit enhanced responses when delivered to the area of secondary hyperalgesia induced by high frequency electrical stimulation of the skin (HFS). Before and twenty minutes after HFS, sustained 30-s radiant heat stimuli were delivered to the area of increased mechanical pinprick sensitivity while participants continuously rated intensity of perception using an online visual-analogue scale (0-100 mm). After HFS, no significant enhancement of heat perception was observed in the area of increased pinprick sensitivity. To establish that myelinated nociceptors actually contribute to the perception of sustained heat, we conducted a second experiment in which sustained heat stimuli were presented before and during an A-fibre nerve conduction block, achieved by applying a rubber band with weights which compresses the superficial radial nerve against the radius. During the block, heat perception was significantly reduced 17–33 s after the onset of the heat stimulus (before: mean = 53 mm, during: mean = 31 mm; P = .03), matching the response profile of AMH-type I nociceptors. These results support the notion that AMH-type I nociceptors contribute to the perception of sustained heat, but also show that these afferents do not mediate secondary hyperalgesia.

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A new device for monitoring individual activity rhythms of honey bees reveals critical effects of the social environment on behavior

Abstract

Chronobiological studies of individual activity rhythms in social insects can be constrained by the artificial isolation of individuals from their social context. We present a new experimental set-up that simultaneously measures the temperature rhythm in a queen-less but brood raising mini colony and the walking activity rhythms of singly kept honey bees that have indirect social contact with it. Our approach enables monitoring of individual bees in the social context of a mini colony under controlled laboratory conditions. In a pilot experiment, we show that social contact with the mini colony improves the survival of monitored young individuals and affects locomotor activity patterns of young and old bees. When exposed to conflicting Zeitgebers consisting of a light–dark (LD) cycle that is phase-delayed with respect to the mini colony rhythm, rhythms of young and old bees are socially synchronized with the mini colony rhythm, whereas isolated bees synchronize to the LD cycle. We conclude that the social environment is a stronger Zeitgeber than the LD cycle and that our new experimental set-up is well suited for studying the mechanisms of social entrainment in honey bees.

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Does general anesthesia have a clinical impact on intraocular pressure in children?

Summary

Background

Reliable measurement of intraocular pressure (IOP) is crucial in pediatric patients with suspected glaucoma. General anesthesia (GA) is usually needed in infants to allow a thorough examination. However, anesthesia itself may influence IOP, depending on the type used and the depth of sedation. The purpose of this study was to evaluate the normal distribution of IOP during GA in healthy children and to analyze differences in IOP relative to the anesthetics used and the measurement time point.

Methods

Approval for this observational study was received from the local institutional review boards and written informed consent was obtained from the children's parents. A total of 100 pediatric patients with no history of glaucoma scheduled for nonintraocular surgery underwent general anesthesia, induced with sevoflurane (s) or propofol (p) and maintained with either sevoflurane with remifentanil (S) or propofol with remifentanil (P). The patients were grouped to one of four subgroups (sS, sP, pP, pS) depending on the anesthetics used during induction and maintenance. Hemodynamic parameters and IOP were measured in both eyes at four defined time points: before anesthesia induction (M1); in apnea immediately after induction and before insertion of a laryngeal mask airway (M2); in deep anesthesia during mechanical ventilation (M3); and after extubation (M4), using a handheld Perkins applanation tonometer. Differences in IOP in both eyes during the measurement periods were analyzed using multivariate repeated-measures analysis of variance and Tukey-HSD as a posthoc test with statistical significance set at P < 0.05. Pearson correlation coefficient was used to investigate further relationships between heart rate, systolic blood pressure, and IOP.

Results

General anesthesia reduced IOP significantly. The mean IOP was normally distributed, with a mean of 7.4 ± 2.89 mmHg at M1. It decreased significantly to a minimum of 5.6 ± 3.04 mmHg (P < 0.01) at M2 and increased significantly to 7.2 ± 2.51 mmHg (P < 0.01) at M3 and again to 8.4 ± 3.72 mmHg (P = 0.03) at M4. All four subgroups (sS, sP, pP, pS) showed comparable decreases in IOP between M1 and M2. During deep anesthesia (M3) and during reversal (M4), the IOP increased again in all groups. During reversal (M4), however, the sS group had a significantly lower IOP than the pP group (P = 0.001) and sP group (P = 0.02). There were no correlations between changes in IOP and gender, age, or type of surgery.

Conclusions

Sevoflurane and propofol, both in combination with remifentanil, significantly lower IOP in children. Individual IOP levels rise and fall during anesthesia, depending on the time point of measurement. The lowest IOP can be measured immediately after induction of anesthesia. This needs to be taken into account when measuring IOP in children.

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