bluuebunny/crossref_metadata_2025_split huggingface dataset:
The mechanism of cell membrane repair
Authors: Togo Tatsuru , Alderton Janet M. , Steinhardt Richard A. 
Published: July 2018

Disruption of plasma membranes is a widespread, common and normal event that occurs in many mechanically challenged tissues (McNeil & Steinhardt, 1997). After injury to the plasma membrane, rapid resealing of the membrane occurs with little loss of intracellular contents.Analysis of plasma membrane repair in the sea urchin egg and early embryos revealed a new model of the mechanism for plasma membrane repair. Resealing of disrupted plasma membranes required external Ca2+that could be antagonised by Mg2+. Block of Ca2+/calmodulin kinase II, which regulates exocytotic vesicle availability at synapses (Llináset al., 1991), inhibited membrane resealing. Resealing was also inhibited by botulinum neurotoxins A, B, C1, and tetanus toxin, which disrupt SNARE vesicle docking/fusion proteins. Confocal microscopic observations of exocytotic events in sea urchin eggs and embryos during membrane resealing showed that inhibition of kinesin or myosin motor activity, which are believed to be required for vesicle transport (Goodsonet al., 1997), also inhibited membrane resealing and delivery of vesicles to sites of membrane disruption. This pattern of inhibition indicates that membrane repair of micrometre-sized lesions requires vesicle delivery, docking and fusion, similar to the exocytosis of neurotransmitter (Steinhardtet al., 1994; Biet al., 1995, 1997).The mechanism of resealing in eggs and embyros was found to be a general property of all cells (Steinhardtet al., 1994; Togoet al., 1999). It is now known that elevated intracellular Ca2+triggers exocytosis in various types of cells (Dan & Poo, 1992; Coorssenet al., 1996), and that endosomal compartments such as lysosomes can behave as Ca2+-regulated exocytotic vesicles (Rodríguezet al., 1997).
Origin and behaviour of pigment cells in sea urchin embryos
Authors: Kominami Tetsuya 
Published: July 2018

Sea urchin pluteus larvae contain dozens of pigment cells in their ectoderm. These pigment cells are the descendants of the veg2 blastomeres of the 60-cell stage embryo. According to the fate map made by Ruffins and Ettensohn, the prospective pigment cells occupy the central region of the vegetal plate. Most of these prospective pigment cells exclusively give rise to pigment cells. Therefore, specification of the pigment cell lineage should occur at some point between the 60-cell and mesenchyme blastula stage. However, the detailed process of the specification of the pigment lineage is unknown.When are pigment cells specified? Are cell interactions necessary for the specification? Do founder cells exist? To answer these questions, I treated embryos with Ca2+-free seawater during the cleavage stage and examined the number of pigment cells observed in pluteus larvae. Treatment at 5.5–8.5 h and especially 7.5–10.5 h postfertilisation markedly reduced the number of pigment cells. The decrease was statistically significant. On the other hand, the treatment at 3.5–6.5 h or 9.5–12.5 h never reduced the number of pigment cells. By examining the frequency of the appearance of embryos whose numbers of pigment cells were less than 20, it was also found that the numbers of pigment cells were frequently in multiples of 4. Embryos having 4, 8, 12, 16 and 20 pigment cells were more frequently observed. Statistics indicated that the frequency of appearance was not random. These results indicated that cell contacts are necessary for the specification of pigment cells and that the specification occurs from 7 to 10 h postfertilisation. The results also suggest that the founder cells, if they exist, divide twice before they differentiate into pigment cells.
cDNA cloning of GTH receptor family in starfish ovaries
Authors: Hirai Toshiaki , Oba Yuichi , Yoshikuni Michiyasu , Nagahama Yoshitaka , Mita Masatoshi 
Published: July 2018

In starfish, oocytes in the ripe ovary do not develop beyond the end of the first prophase stage of meiosis. Such immature oocytes are not fertilisable. The resumption of meiosis in these oocytes and release from the ovary are induced by the maturation-indueing hormone 1-methyladenine (1-MeAde) (Kanatani et al., 1969). 1-MeAde is produced by ovarian follicle cells after stimulation by a gonad-stimulating hormone (GSS) secreted from radial nerves. The action of GSS on 1-MeAde production in follicle cells appears to be mediated by its receptor, G-proteins and adenylyl cyclase (Mita & Nagahama, 1991). It has been shown that upon incubation of follicle cells with GSS, there is a dose-related increase in cyclic AMP production, coincident with an increase in 1-MeAde production (Mita et al., 1989). Thus, it was suggested that a G-protein coupled (seven transmembrane type) receptor is involved in GSS signal transduction in a similar manner to the pituitary–gonadal axis in vertebrates. To elucidate the mechanism of starfish oocyte maturation, we focused on a receptor protein for GSS on the ovarian follicle cell surface. In this study, we cloned the cDNA with glycoprotein hormone receptor homology in a transmembrane region from ovaries of the starfish Asterina pectinifera.Using consensus sequences from glycoprotein hormone receptors, a 3953 bp cDNA was cloned from mRNA of starfish A. pectinifera ovaries. The region from nucleotide 72 to 3109 represents the open-reading frame. The seven transmembrane spanning domains were found in the region from nucleotide 1745 to 2533. The lengths of specific domains in the cDNA were 1671 bp, 789 bp and 579 bp for extracellular (ECD), transmembrane (TMD) and intracellular domains (ICD), respectively. Similar to other glycoprotein hormone receptors, the cDNA from starfish ovaries had a large ECD region. With respect to the predicted amino acid sequence, the ECD, TMD and ICD were composed of 557, 263 and 192 amino acids, respectively.
Light-induced reactivation of movement in degenerated sperm of echiuroid, oyster and sea urchin
Authors: Kamata Yasuyuki , Fujiwara Akiko , Yamazaki Ken , Tazawa Eigoro , Yasumasu Ikuo 
Published: July 2018

Previously, it has been reported that NADH cytochrome c reductase and succinate cytochrome c reductase, in which the redox reaction in cytochrome b is involved, are activated by light irradiation with peaks of photo-activation at wavelengths of 430, 530 and 570 nm corresponding to those in the absorption spectrum of reduced cytochrome b in mitochondria isolated from sperm of echiuroid, oyster and sea urchin (Tazawa et al., 1996). In sperm of these species, augmentation of respiration due to photo-activation of the cytochrome b reaction is observed only when the electron transport in this span of the mitochondrial respiratory chain is inhibited by carbon monoxide (Fujiwara et al., 1991; Yasumasu et al., 1991) or by a decrease in the amount of cytochrome b due to sperm ageing. In sperm cultured for a long time, the respiratory rate was very low and almost all sperm became immotile. In these sperm, respiration was reactivated by light irradiation at the wavelengths of 430, 530 and 570 nm (Fujiwara et al., 1999).In the present study, photo-reactivation of movement in these somewhat degenerated sperm incubated for a long time was also found to occur, with peaks at the above-mentioned wavelengths. We concluded that photo-reactivation of movement in these sperm, in which the cytochrome b reaction probably became rate-limiting in the respiration chain, is supported by reactivation of respiration by light irradiation. On the other hand, though the ATP level decreased to a rather low level at about 30 min after the initiation of incubation in sperm of all species examined, sperm swam for more than 10 h, by which time the ATP level was quite low. Light irradiation induced reactivation of movement but did not alter the rather low ATP level in these sperm. Thus the ATP level does not seem to be responsible for making sperm immotile. In sperm treated with Triton X-100, movement was induced by adding ATP and Mg2+, even when many sperm had become immotile after a long incubation. Hence, capacity for movement does not seem to be reduced by a long incubation time. The movement of sperm treated with Triton X-100 was not activated bv light irradiation.
Lipid raft on gametic cells as a functional domain for sperm–egg interaction coupled with signal transduction
Authors: Ohta Kaoru , Sato Chihiro , Matsuda Tsukasa , Toriyama Masaru , Vacquier Victor D. , Hirohashi Noritaka , Lennarz William J. , Kitajima Ken 
Published: July 2018

It has been shown that lipid raft, a microdomain of plasma membrane, is a hot spot of signal transduction in somatic cells, because it contains several transducer proteins as well as various receptor molecules. The lipid raft is characterised by its low-density detergent-insoluble nature and by enrichment of glycosphingolipids (GSLs). We hypothesised that lipid raft was also on the gamete surface, and might function as a sperm–egg adhesion site as well as in signal transduction during fertilisation. To test this hypothesis, we have initiated studies using sea urchin gametes. Recently we have demonstrated the presence of the lipid raft in sperm of three sea urchin species as the first example in gametic cells (Ohtaet al., 1999). Here we show several lines of evidence for the functional importance of the lipid raft in sperm–egg interaction as well as in subsequent signal transduction.In sea urchin sperm, lipid rafts were able to be prepared as a low-density detergent-insoluble membrane (LD-DIM) fraction and were rich in GSLs including gangliosides and sulphatide, containing more than 50% of the total amount of GSL present in sperm. On the other hand, cholesterol and sphingomyelin were not so enriched, which contrasted with the LD-DIM from MDCK cells, where these lipids were reported to be abundant (Brown & Rose, 1992).
Role of the fertilisation envelope and specialised microvilli in morphogenesis of starfish embryos
Authors: Matsunaga Maki , Uemura Isao , Tamura Miwa , Nemoto Shin-ichi 
Published: July 2018

In the early cleavage stages of animal embryos, blas-tomeres lack devices to connect to each other. It is well known that in sea urchin embryos the hyaline layer plays an important role in maintaining the position of individual blastomeres, and provides a scaffold for morphogenesis to the embryo. In starfish embryos, however, the presence of the hyaline layer is not certain in the early cleavage stages, although it has been observed at the gastrula stage (Dan-Sohkawaet al., 1986). In the present study we have investigated the devices corresponding to the hyaline layer of sea urchin embryos in the early cleavage stages, where blastomeres lack such devices for cell adhesion as desmosomes.We examined how blastomeres keep their position in the early cleavage stages of starfish embryos usingAsterina pectiniferaandAstropecten scoparius. By neither electron microscopy nor immunofluorescent staining with an antibody against the hyaline layer of sea urchin embryos (Yazaki, 1968) could we detect the hyaline layer, at least up to 6 h after fertilisation.When the fertilisation envelope (FE) was dilated larger by urea treatment, blastomeres increasingly came apart with the expansion of the FE, resulting in the formation of plural small blastulae due to the failure of the blastomeres to come together into a single mass. In urea-treated embryos, blastomeres were observed closely apposed to the inner surface of the FE. These observations suggest that blastomeres are fixed by some means to the FE. Differential interference-contrast microscopy revealed numerous projections between the cell surface of the blastomeres and the FE. Probably, the FE and the projections are involved in maintaining the three-dimensional position of each blastomere in an embryo.
Lim1-related homeobox gene (HpLim1) expressed in sea urchin embryo
Authors: Mitsunaga-Nakatsubo Keiko , Kawasaki Takahiko , Takeda Koichi , Akasaka Koji , Shimada Hiraku 
Published: July 2018

A characteristic cysteine-rich motif, LIM domain, was first detected in three different transcription factors: lin-11, Islet-1 and mec-3. A feature shared by these genes is the presence of two LIM domains linked to a DNA-binding homeodomain (Sánchez-Garcíaet al., 1994). LIM homeodomain (LHX) proteins have been reported to be implicated in a variety of developmental processes (Dawidet al., 1998).Expression patterns of LHX genes have been analysed in a wide variety of organisms and reported to be cell-type specific (Dawidet al., 1998). In vertebrates, they are expressed in organiser equivalent regions at the gastrula stage, suggesting their involvement in mesoderm induction (Tairaet al., 1992; Barneset al., 1994; Toyamaet al., 1995).Hrlim, an ascidian Lim3, zygotically expresses in the endoderm lineage before gastrulation, suggesting that it is involved in the endoderm determination (Wadaet al., 1995).Here, cDNA cloning of the Lim1-related homeobox gene (HpLim1) of the sea urchin,Hemicentrotus pulcherrimus, is described together with the spatially as well as temporally regulated expression ofHpLim1during sea urchin development. A possible role of HpLiml in sea urchin development is also discussed based on its spatial pattern of expression and on the result of an over-expression study.
Regulative potential to form an amniotic cavity in mesomeres of a direct developing echinoid, Peronella japonica
Authors: Kitazawa Chisato , Amemiya Shonan 
Published: July 2018

Peronella japonica, a direct developer, exhibits certain peculiar features during development, particularly heterochrony, a change in the relative timing of expression among tissues and organs. One of the important heterochronical changes in the species was found in the development of the amniotic cavity, a component of an adult rudiment. In indirect developers the amniotic cavity is formed on the left side of the larval body in the late pluteus stage. In P. japonica the organ is formed at the gastrula stage in the region located on the midline of the larval body.In the present study, the ability of partial embryos isolated from 8- or 16-cell stage embryos of P. japonica to differentiate an amniotic cavity was investigated to assess the regulative potential of a direct developer.The embryos were dissected at 8-cell stage with a glass needle to obtain half embryos. Some of the half embryos were further divided into four blastomeres to obtain mesomere pairs. Each half embryo and blastomere that did not form micromeres but divided equally during the next cleavage was identified as an animal cap and presumptive mesomere pair. Isolated animal caps and mesomere pairs were cultured, and differentiation of the amniotic cavity was examined at 24 and 48 h after fertilisation, when the organ in the normal embryos had already completed differentiation.
An HPLC analysis of neurotransmitters in sea urchin larvae
Authors: Yazawa Toru , Uemura Isao 
Published: July 2018

Classical neurotransmitters such as acetylcholine (ACh), biogenic amines and ϒ-aminobutyric acid (GABA) have been shown to mediate various forms of intercellular signalling in marine invertebrates including sea urchin larvae (Buznikovet al., 1996). The presence of amines and GABA in the nervous system of sea urchin larvae has been demonstrated by a cytochemical method at the gastrula stage (Bisgrove & Burke, 1987). However, few quantitative analyses of neurotransmitters have been attempted in the embryonic sea urchin. To accomplish this during the period of embryogenesis, in the present study we attempted to make homogenate samples adequate for HPLC analysis and to determine the levels of neurotransmitter in their extracts.We established an HPLC protocol using a batch of four-armed sea urchin larvae, and detected neurotransmitters (per milligram wet weight) in the homogenate of pluteus larvae ofHemicentrotus pulcherrimus(1.5–3.5 pmol dopamine, 0.22–0.51 pmol serotonin, 4.4–40 pmol ACh, 0.28–0.36 nmol glutamate, 20–23 nmol glycine) (Figs. 1, 2). GABA was not detected (detection limit, 10 pmol/10 μl injection). We also observed glyoxylic-acid-induced yellowish-green monoamine fluorescence in the larval nervous system. Serotonin has been a leading candidate neurotransmitter in sea urchin larvae (Nakajimaet al., 1993).
Experimental hybridisation between two tropical species of sea urchins (genus Echinometra) in Okinawa
Authors: Rahman M. Aminur , Uehara Tsuyoshi 
Published: July 2018

Recent morphological, biochemical, ecological and reproductive studies have revealed that there are four sympatric biological species of sea urchins in Echinometra from Okinawa, which are currently referred to as Echinometra species A, B, C and D (e.g. Uehara et al., 1990,1991; Arakaki & Uehara, 1991; Matsuoka & Hatanaka, 1991; Palumbi & Metz, 1991; Nishihira et al., 1991). Of these four species, E. sp. A (Ea) and E. sp. C (Ec), while being most closely related to each other genetically (Matsuoka & Hatanaka, 1991), can also be distinguished from each other by differences in adult morphology and microhabitat preference. No studies have addressed the mechanisms that maintain the independence of these species despite their close affinity and sympatry.Experimental hybridisation conducted between two genetically very divergent species of Okinawan Echinometra, E. sp. A (Ea) and E. sp. D (Ed), revealed the presence of prezygotic isolation (Asian & Uehara, 1997). To test whether the closely related Okinawan Echinometra spp. are isolated by pre- or postzygotic mechanisms, we carried out experimental hybridisation by using much closer species, Ea and Ec, through a series of cross-fertilisation experiments and rearing of the resulting hybrids. The percentage of successful heterogametic fertilisation was high when eggs of Ec and sperms of Ea were involved, whereas it was considerably lower with eggs of Ea and sperms of Ec. This reduction, at least among some heterogametic crosses, indicates the presence of a gamete recognition protein binding system, as reported by Metz et al. (1994) and Metz & Palumbi (1996), which might eventually lead to gametic incompatibility and reproductive isolation.
Disaster Exercises to Prepare Hospitals for Mass-Casualty Incidents: Does it Contribute to Preparedness or is it Ritualism?
Authors: Verheul Marlous LMI , Dückers Michel LA , Visser Bea B , Beerens Ralf JJ , Bierens Joost JLM 
Published: July 2018

AbstractIntroductionThe central question this study sought to answer was whether the team members of Strategic Crisis Teams (SCTs) participating in mass-casualty incident (MCI) exercises in the Netherlands learn from their participation.MethodsEvaluation reports of exercises that took place at two different times were collected and analyzed against a theoretical model with several dimensions, looking at both the quality of the evaluation methodology (three criteria: objectives described, link between objective and items for improvement, and data-collection method) and the learning effect of the exercise (one criterion: the change in number of items for improvement).ResultsOf all 32 evaluation reports, 81% described exercise objectives; 30% of the items for improvement in the reports were linked to these objectives, and 22% of the 32 evaluation reports used a structured template to describe the items for improvement. In six evaluation categories, the number of items for improvement increased between the first (T1) and the last (T2) evaluation report submitted by hospitals. The number of items remained equal for two evaluation categories and decreased in six evaluation categories.ConclusionThe evaluation reports do not support the ideal-typical disaster exercise process. The authors could not establish that team members participating in MCI exercises in the Netherlands learn from their participation. More time and effort must be spent on the development of a validated evaluation system for these simulations, and more research into the role of the evaluator is needed.Verheul MLMI, Dückers MLA, Visser BB, Beerens RJJ, Bierens JJLM. Disaster exercises to prepare hospitals for mass-casualty incidents: does it contribute to preparedness or is it ritualism? Prehosp Disaster Med. 2018;33(4):387–393
AUTHORITY, LEGITIMACY, AND THE OBLIGATION TO OBEY THE LAW
Authors: Dagger Richard 
Published: July 2018

ABSTRACTAccording to the standard or traditional account, those who hold political authority legitimately have a right to rule that entails an obligation of obedience on the part of those who are subject to their authority. In recent decades, however, and in part in response to philosophical anarchism, a number of philosophers have challenged the standard account by reconceiving authority in ways that break or weaken the connection between political authority and obligation. This paper argues against these revisionist accounts in two ways: first, by pointing to defects in their conceptions of authority; and second, by sketching a fair-play approach to authority and political obligation that vindicates the standard account.
Nurse practitioner consultations in primary health care: a case study-based survey of patients’ pre-consultation expectations, and post-consultation satisfaction and enablement
Authors: Barratt Julian , Thomas Nicola 
Published: July 2018

AbstractBackgroundResearch has not yet fully investigated links to consultation duration, patient expectations, satisfaction, and enablement in nurse practitioner consultations. This study was developed to address some of these research gaps in nurse practitioner consultations, particularly with a focus on expectations, satisfaction, and enablement.AimTo explore the influence of pre-consultation expectations, and consultation time length durations on patient satisfaction and enablement in nurse practitioner consultations in primary health care.DesignSurvey component of a larger convergent parallel mixed methods case study designed to conjointly investigate the communication processes, social interactions, and measured outcomes of nurse practitioner consultations. The survey element of the case study focusses on investigating patients’ pre-consultation expectations and post-consultation patient satisfaction and enablement.MethodsA questionnaire measuring pre-consultation expectations, and post-consultation satisfaction and enablement, completed by a convenience sample of 71 adults consulting with nurse practitioners at a general practice clinic. Initial fieldwork took place in September 2011 to November 2012, with subsequent follow-up fieldwork in October 2016.ResultsRespondents were highly satisfied with their consultations and expressed significantly higher levels of enablement than have been seen in previous studies of enablement with other types of clinicians (P=0.003). A significant, small to moderate, positive correlation of 0.427 (P=0.005) between general satisfaction and enablement was noted. No significant correlation was seen between consultation time lengths and satisfaction or enablement.ConclusionHigher levels of patient enablement and satisfaction are not necessarily determined by the time lengths of consultations, and how consultations are conducted may be more important than their time lengths for optimising patient satisfaction and enablement.