bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effect of Using the Art of Harmony and Synergy with Strategic and Cognitive Dimensions in Improving the Methods of Storming Competitors' Strategies
Authors: Al-Shawi Hani Fadhil Jumaah
Published: April 2021

When I start talking about clarifying and explaining what distinguishes between the cognitive, social and performance capabilities of the leader, I must analyze the characteristics of leadership and management related to their perceptions of work activities represented in solving technical problems that arise in the field of administrative work by creating a style of harmony and coping, and the effect of the characteristics of his nature and the reflection of their upbringing on How to create an appropriate climate to contain the emergency situations that hinder the functional and production processes and try to find out whether they have the capabilities that direct it towards (Benchmarking) organizations that develop unique solutions to those situations or not?This study came as an attempt to present explanations and clarifications of the aforementioned by introducing scientific additions to what researchers have gone by, who contributed to drawing a roadmap, but they did not fully seize the opportunity, but rather left it for the coming intellectual generations to put touches on it that approach their reality and their era, which increases questions, ambiguity and challenges. The study aims to develop a (Head, heart, Legs) model for the contemporary managerial psychologist (Finn Havaleshka), which is one of the most important and pioneering scientific contributions in the field of managerial psychology that focuses on explaining the characteristics of individuals at the level of managerial decision-making (administrative and leadership) from By focusing on the cognitive and social aspects, and their impact on performance), let this study be an evolution of this model and an update of what this pioneering scientist started by adding a fourth stage to the model represented by the dimension of (Arms) or arms that defend the successes achieved through their maintenance and preservation. On the one hand, the situation is transferred to the offensive stage by expanding the area of success by using offensive strategies that invade the labor market, as it is said that the best defense is attack. The study was divided into three axes:The first axis focused on presenting the methodological aspect of the research, while the second focused on the available theorizing and the third covered the conclusions.
Recent findings suggest adding red fox to climate-threatened whitebark pine trophic system
Authors: Cross Patrick R. , Crabtree Robert L.
Published: April 2021

Mountain ecosystems are sensitive to climate change, and climate-driven declines in primary producers can impact food webs. Whitebark pine (Pinus albicaulis Engelm.) seed, a valuable food resource for montane wildlife species, is threatened by climate change. Whitebark pine exhibit masting, and during a snowtracking study of Rocky Mountain red foxes (Vulpes vulpes macroura Baird, 1852) in the Greater Yellowstone Ecosystem that happened to coincide with masting, we unexpectedly observed red foxes consuming whitebark pine seeds from red squirrel (Tamiasciurus hudsonicus Erxleben, 1777) middens. Seed production then decreased the following year. To investigate whether whitebark pine seed availability affected winter foraging and habitat use by red foxes, we assessed interannual variance in our dietary and habitat use data. We found both seed consumption and use of habitats where seeds were available also decreased during the non-mast winter. Given the limitations of our small-scale, opportunistic analysis, we suggest whitebark pine seeds may be an important food resource for red foxes, and that their relationship warrants further research and consideration in conservation efforts for both species.
Logarithmic corrections to Newtonian gravity and large scale structure
Authors: Capozziello Salvatore , Faizal Mir , Hameeda Mir , Pourhassan Behnam , Salzano Vincenzo
Published: April 2021

Effects from nonstandard corrections to Newtonian gravity, at large scale, can be investigated using the cosmological structure formation. In particular, it is possible to show if and how a logarithmic correction (as that induced from nonlocal gravity) modifies the clustering properties of galaxies and of clusters of galaxies. The thermodynamics of such systems can be used to obtain important information about the effects of such modification on clustering. We will compare its effects with observational data and it will be demonstrated that the observations seem to point to a characteristic scale where such a logarithmic correction might be in play at galactic scales. However, at larger scales such statistical inferences are much weaker, so that a fully reliable statistical evidence for this kind of corrections cannot be stated without further investigations and the use of more varied and precise cosmological and astrophysical probes.
Electron bunchers for industrial RF linear accelerators: theory and design guide
Authors: Kutsaev Sergey V.
Published: April 2021

The acceleration of electrons in resonant linear accelerators (linacs) typically consists of three main stages: (1) emission of the electrons from the cathode and their pre-acceleration with a DC field to the energy of tens of keV; (2) grouping the DC electron beam into bunches and their synchronization with the correct phase of high-frequency electromagnetic fields, and (3) accelerating the bunches of relativistic electrons to the required energies. Although many books describe the theoretical and practical aspects of electron linac design, most of them concentrate on beam physics in either the gun stage or in the relativistic regime, while leaving the description of the bunching process rather general. The physics of non-relativistic motion is described in the literature on ion accelerators, but in practice, it cannot be scaled to electron machines due to the significantly different particle mass and acceleration rate, beam velocity change, and frequencies. In this tutorial review paper, we will fill this gap with a detailed description of the bunching process and provide practical advice on the design of bunching sections in industrial-grade electron linacs.
A grammatical description of the placeholder are in spontaneous Japanese
Authors: SERAKU Tohru , PARK Min-Young , SAKAGUCHI Sayaka
Published: April 2021

When a speaker encounters a word-formulation problem in interaction, she may use a placeholder to saturate the syntactic slot of the target expression in the unfolding sentence. Japanese exhibits the placeholder are, which is assumed to derive from the demonstrative are ‘that.’ Despite rich studies on placeholders, no serious attention has been paid to grammatical parallelism and differences between a placeholder and its original lexical counterpart. In this paper, we focus on the nominal placeholder are (and its predicative variants) and the demonstrative are ‘that,’ and propose the set of criteria which capture their parallelism and differences in non-discrete terms.
The cost-effectiveness of gene therapy for severe hemophilia B: a microsimulation study from the United States perspective
Authors: Bolous Nancy S. , Chen Yichen , Wang Huiqi , Davidoff Andrew M. , Devidas Meenakshi , Jacobs Timothy W. , Meagher Michael M. , Nathwani Amit C. , Neufeld Ellis J. , Piras Bryan A. , Rodriguez-Galindo Carlos , Reiss Ulrike M. , Bhakta Nickhill
Published: April 2021

Adeno-associated virus (AAV)-mediated gene therapy is a novel treatment promising to reduce morbidity associated with hemophilia. Although multiple clinical trials continue to evaluate efficacy and safety, limited cost-effectiveness data have been published. This study compared the potential cost-effectiveness of AAV-mediated factor IX (FIX)-Padua gene therapy for patients with severe hemophilia B in the United States vs on-demand FIX replacement and primary FIX prophylaxis, using either standard or extended half-life FIX products. A microsimulation Markov model was constructed, and transition probabilities between health states and utilities were informed by using published data. Costs were aggregated by using a microcosting approach. A time horizon from 18 years old until death, from the perspective of a third-party payer in the United States, was conducted. Gene therapy was more cost-effective than both alternatives considering a $150 000/quality-adjusted life-year threshold. The price for gene therapy was assumed to be $2 000 000 in the base case scenario; however, one of the 1-way sensitivity analyses was conducted by using observed manufacturing, administration, and 5-year follow-up costs of $87 198 for AAV-mediated gene therapy vector as derived from the manufacturing facility and clinical practice at St Jude Children’s Research Hospital. One-way sensitivity analyses revealed 10 of 102 scenarios in which gene therapy was not cost-effective compared with alternative treatments. Notably, gene therapy remained cost-effective in a hypothetical scenario in which we estimated that the discounted factor concentrate price was 20% of the wholesale acquisition cost in the United States. Probabilistic sensitivity analysis estimated gene therapy to be cost-effective at 92% of simulations considering a $150 000/quality-adjusted life-year threshold. In conclusion, based on detailed simulation inputs and assumptions, gene therapy was more cost-effective than on-demand treatment and prophylaxis for patients with severe hemophilia B.
Primary hepatic lymphoma diagnosed using endoscopic ultrasound-guided liver biopsy: a case report
Authors: Nishikawa Kenichiro , Katsuta Koji , Tanaka Syota , Fujibe Kodai , Hattori Aiji , Shiono Yasunori , Oiwa Michiaki , Matsusaki Shimpei
Published: April 2021

Background

Because of the rarity of primary hepatic lymphomas, diagnosis of this disease entity may often be difficult, and performing a liver biopsy is the only way to establish a definitive diagnosis. Recently, endoscopic ultrasound-guided liver biopsy has emerged as a safe technique for obtaining liver tissue. However, there is no report on the use of endoscopic ultrasound-guided liver biopsy for diagnosing primary hepatic lymphomas.

Case presentation

An 85-year-old Asian man was admitted to our hospital because of multiple liver lesions without any identifiable primary tumor or extrahepatic lymphadenopathy. Serum tumor markers, including alpha-fetoprotein, were in the normal range. We provisionally diagnosed the patient with a cancer of unknown primary origin with liver metastases. An endoscopic ultrasound-guided fine needle liver biopsy of the tumor in the left lobe of the liver was performed using a transgastric approach, and histology revealed a primary hepatic lymphoma of a diffuse large B-cell lymphoma type.

Conclusions

Primary hepatic lymphomas are quite rare, and diagnosis is often difficult without performing a biopsy. Endoscopic ultrasound-guided liver biopsy is a useful diagnostic modality even in such cases.
Hemopneumothorax detection through the process of artificial evolution - a feasibility study
Authors: Sommer Adir , Mark Noy , Kohlberg Gavriel D. , Gerasi Rafi , Avraham Linn Wagnert , Fan-Marko Ruth , Eisenkraft Arik , Nachman Dean
Published: April 2021

Background

Tension pneumothorax is one of the leading causes of preventable death on the battlefield. Current prehospital diagnosis relies on a subjective clinical impression complemented by a manual thoracic and respiratory examination. These techniques are not fully applicable in field conditions and on the battlefield, where situational and environmental factors may impair clinical capabilities. We aimed to assemble a device able to sample, analyze, and classify the unique acoustic signatures of pneumothorax and hemothorax.

Methods

Acoustic data was obtained with simultaneous use of two sensitive digital stethoscopes from the chest wall of an ex-vivo porcine model. Twelve second samples of acoustic data were obtained from the in-house assembled digital stethoscope system during mechanical ventilation. The thoracic cavity was injected with increasing volumes of 200, 400, 600, 800, and 1000 ml of air or saline to simulate pneumothorax and hemothorax, respectively. The data was analyzed using a multi-objective genetic algorithm that was used to develop an optimal mathematical detector through the process of artificial evolution, a cutting-edge approach in the artificial intelligence discipline.

Results

The in-house assembled dual digital stethoscope system and developed genetic algorithm achieved an accuracy, sensitivity and specificity ranging from 64 to 100%, 63 to 100%, and 63 to 100%, respectively, in classifying acoustic signal as associated with pneumothorax or hemothorax at fluid injection levels of 400 ml or more, and regardless of background noise.

Conclusions

We present a novel, objective device for rapid diagnosis of potentially lethal thoracic injuries. With further optimization, such a device could provide real-time detection and monitoring of pneumothorax and hemothorax in battlefield conditions.
Research progress in the effects of terahertz waves on biomacromolecules
Authors: Sun Liu , Zhao Li , Peng Rui-Yun
Published: April 2021

With the rapid development of terahertz technologies, basic research and applications of terahertz waves in biomedicine have attracted increasing attention. The rotation and vibrational energy levels of biomacromolecules fall in the energy range of terahertz waves; thus, terahertz waves might interact with biomacromolecules. Therefore, terahertz waves have been widely applied to explore features of the terahertz spectrum of biomacromolecules. However, the effects of terahertz waves on biomacromolecules are largely unexplored. Although some progress has been reported, there are still numerous technical barriers to clarifying the relation between terahertz waves and biomacromolecules and to realizing the accurate regulation of biological macromolecules by terahertz waves. Therefore, further investigations should be conducted in the future. In this paper, we reviewed terahertz waves and their biomedical research advantages, applications of terahertz waves on biomacromolecules and the effects of terahertz waves on biomacromolecules. These findings will provide novel ideas and methods for the research and application of terahertz waves in the biomedical field.
Forest fire and law: an analysis of Turkish forest fire legislation based on Food and Agriculture Organization criteria
Authors: Elvan Osman Devrim , Birben Üstüner , Özkan Ulaş Yunus , Yıldırım Hasan Tezcan , Türker Yavuz Özhan
Published: April 2021

Background

Because of climate and forest vegetation, Turkey has regions (particularly the Mediterranean and Aegean regions) that are vulnerable to forest fires. Approximately 2000 forest fires have occurred every year for the last 20 years, with at least 48% of them caused by humans. This percentage increases to 71% when the rates of fires of unknown causes are included. In this study, legislation on Turkish forest fires was analyzed based on the Food and Agriculture Organization’s (FAO’s) guide, “Forest Fires and the Law.” The guide was prepared by expert lawyers and addresses the basic topics of definitions; institutional setup and interinstitutional coordination planning, monitoring, and assessment; prevention and preparedness; detection and early warning and suppression; participatory and community-based approaches to fire management; fire use; rehabilitation; and law enforcement. The objective of this study was to reveal the current status of Turkish forestry legislation and its practices based on the FAO guide.

Results

According to our analysis, Turkish forestry legislation has followed the FAO criteria 78.1% of the time. It is clear that effective regulations exist, with the Turkish Constitution being the foremost touchstone. The results illustrate that, no matter how strong the legislation is, a deficiency in administrative measures and a lack of public awareness make combating forest fires unsuccessful.

Conclusions

The areas that need to be improved have been determined to be definitions, participatory and community-based approaches to fire management, and creating a fire line. A focus on public participation and the social approach is needed.
Genetic Thyrotropin Regulation of Atrial Fibrillation Risk Is Mediated Through an Effect on Height
Authors: Shi Mingjian , Manouchehri Ali M , Shaffer Christian M , Vaitinadin Nataraja Sarma , Hellwege Jacklyn N , Salem Joe-Elie , Davis Lea K , Simmons Jill H , Roden Dan M , Shoemaker M Benjamin , Ferguson Jane F , Mosley Jonathan D
Published: April 2021

Context

A genetic predisposition to lower thyrotropin (TSH) levels is associated with increased atrial fibrillation (AF) risk through undefined mechanisms.

Objective

Defining the genetic mediating mechanisms could lead to improved targeted therapies to mitigate AF risk.

Methods

We used 2-sample mendelian randomization (MR) to test associations between TSH-associated single-nucleotide variations and 16 candidate mediators. We then performed multivariable mendelian randomization (MVMR) to test for a significant attenuation of the genetic association between TSH and AF, after adjusting for each mediator significantly associated with TSH.

Results

Four candidate mediators (free thyroxine, systolic blood pressure, heart rate, and height) were significantly inversely associated with genetically predicted TSH after adjusting for multiple testing. In MVMR analyses, adjusting for height significantly decreased the magnitude of the association between TSH and AF from –0.12 (SE 0.02) occurrences of AF per SD change in height to –0.06 (0.02) (P = .005). Adjusting for the other candidate mediators did not significantly attenuate the association.

Conclusion

The genetic association between TSH and increased AF risk is mediated, in part, by taller stature. Thus, some genetic mechanisms underlying TSH variability may contribute to AF risk through mechanisms determining height occurring early in life that differ from those driven by thyroid hormone–level elevations in later life.
Clinical Adverse Events Associated with Sodium–Glucose Cotransporter 2 Inhibitors: A Meta-Analysis Involving 10 Randomized Clinical Trials and 71 553 Individuals
Authors: Lin Donna Shu-Han , Lee Jen-Kuang , Chen Wen-Jone
Published: April 2021

Context

SGLT2is are first-line antidiabetic agents with demonstrated cardiovascular benefits. Prior meta-analyses have examined adverse events (AEs) associated with these drugs in general, but such knowledge needs to be updated with the results of more recent trials. In addition, the occurrence of various AEs with different underlying diseases is unknown.

Objective

This meta-analysis aimed to investigate the occurrence of various AEs associated with sodium–glucose cotransporter 2 inhibitors (SGLT2is) and to examine the level of risk of AEs in patients with different underlying diseases.

Methods

We conducted a quantitative meta-analysis of randomized controlled trials (RCTs) retrieved from the MEDLINE and EMBASE databases and the Cochrane library on January 31, 2021. Outcomes of interest included 4 overall safety outcomes (AEs) and 12 specified safety outcomes. Further analyses were performed on various subgroups, which were defined based on the status of diabetes mellitus (DM), atherosclerotic cardiovascular disease (ASCVD), chronic kidney disease, and congestive heart failure, and by the dosage of SGLT2i (high dose vs low dose).

Results

Our analysis included 10 eligible studies with a total of 71 553 participants. The meta-analysis showed that SGLT2i led to increased risks of genital infection (risk ratio [RR] 3.56, 95% CI 2.84-4.46), urinary tract infection (RR 1.06, 95% CI 1.00-1.12), diabetic ketoacidosis (RR 2.23, 95% CI 1.36-3.63), and volume depletion (RR 1.14, 95% CI 1.06-1.23). However, the use of SGLT2i was associated with reduced risks of any serious AE (RR 0.92, 95% CI 0.90-0.94), acute kidney injury (AKI) (RR 0.84, 95% CI 0.77-0.91), and hyperkalemia (RR 0.84, 95% CI 0.72–0.99). Within the different subgroups, the risk of amputation was higher in patients with ASCVD than in those without (RR 1.44 vs 0.96, P = .066).

Conclusion

The use of SGLT2is is generally safe. SGLT2is may be associated with increased risks of genital infection but are protective against AKI. Of note, the risk of amputation was higher in patients with ASCVD. The key to the safe use of SGLT2is lies in the identification of high-risk populations and close surveillance of patients after treatment.
Production of somatic and germline chimeras in the chicken by transfer of early blastodermal cells
Authors: Petitte J. N. , Clark M. E. , Liu G. , Gibbins A. M. Verrinder , Etches R. J.
Published: April 2021

Cells were isolated from stage X embryos of a line of Barred Plymouth Rock chickens (that have black pigment in their feathers due to the recessive allele at the I locus) and injected into the subgerminal cavity of embryos from an inbred line of Dwarf White Leghorns (that have white feathers due to the dominant allele at the I locus). Of 53 Dwarf White Leghorn embryos that were injected with Barred Plymouth Rock blastodermal cells, 6 (11.3 %) were phenotypically chimeric with respect to feather colour and one (a male) survived to hatching. The distribution of black feathers in the recipients was variable and not limited to a particular region although, in all but one case, the donor cell lineage was evident in the head. The male somatic chimera was mated to several Barred Plymouth Rock hens to determine the extent to which donor cells had been incorporated into his testes. Of 719 chicks hatched from these matings, 2 were phenotypically Barred Plymouth Rocks demonstrating that cells capable of incorporation into the germline had been transferred. Fingerprints of the blood and sperm DNA from the germline chimera indicated that both of these tissues were different from those of the inbred line of Dwarf White Leghorns. Bands that were present in fingerprints of blood DNA from the chimera and not present in those of the Dwarf White Leghorns were observed in those of the Barred Plymouth Rocks. It was concluded that cells recovered from the stage X embryo can subsequently contribute to melanocytes derived from the neural crest, to erythrocytes and to germ cells. This technique of blastodermal cell transfer should be useful in developmental studies and may facilitate the production of transgenic poultry either directly or through the establishment of chicken pluripotent stem cell lines in vitro.
Brn3a is a transcriptional regulator of soma size, target field innervation and axon pathfinding of inner ear sensory neurons
Authors: Huang Eric J. , Liu Wei , Fritzsch Bernd , Bianchi Lynne M. , Reichardt Louis F. , Xiang Mengqing
Published: April 2021

The POU domain transcription factors Brn3a, Brn3b and Brn3c are required for the proper development of sensory ganglia, retinal ganglion cells, and inner ear hair cells, respectively. We have investigated the roles of Brn3a in neuronal differentiation and target innervation in the facial-stato-acoustic ganglion. We show that absence of Brn3a results in a substantial reduction in neuronal size, abnormal neuronal migration and downregulation of gene expression, including that of the neurotrophin receptor TrkC, parvalbumin and Brn3b. Selective loss of TrkC neurons in the spiral ganglion of Brn3a−/− cochlea leads to an innervation defect similar to that of TrkC−/− mice. Most remarkably, our results uncover a novel role for Brn3a in regulating axon pathfinding and target field innervation by spiral and vestibular ganglion neurons. Loss of Brn3a results in severe retardation in development of the axon projections to the cochlea and the posterior vertical canal as early as E13.5. In addition, efferent axons that use the afferent fibers as a scaffold during pathfinding also show severe misrouting. Interestingly, despite the well-established roles of ephrins and EphB receptors in axon pathfinding, expression of these molecules does not appear to be affected in Brn3a−/− mice. Thus, Brn3a must control additional downstream genes that are required for axon pathfinding.
Evidence for a role of protein kinase C in FGF signal transduction in the developing chick limb bud
Authors: Lu Hui-Chen , Swindell Eric C. , Sierralta Walter D. , Eichele Gregor , Thaller Christina
Published: April 2021

In developing limbs, numerous signaling molecules have been identified but less is known about the mechanisms by which such signals direct patterning. We have explored signal transduction pathways in the chicken limb bud. A cDNA encoding RACK1, a protein that binds and stabilizes activated protein kinase C (PKC), was isolated in a screen for genes induced by retinoic acid (RA) in the chick wing bud. Fibroblast growth factor (FGF) also induced RACK1 and such induction of RACK1 expression was accompanied by a significant augmentation in the number of active PKC molecules and an elevation of PKC enzymatic activity. This suggests that PKCs mediate signal transduction in the limb bud. Application of chelerythrine, a potent PKC inhibitor, to the presumptive wing region resulted in buds that did not express sonic hedgehog (Shh) and developed into wings that were severely truncated. This observation suggests that the expression of Shh depends on PKCs. Providing ectopic SHH protein, RA or ZPA grafts overcome the effects of blocking PKC with chelerythrine and resulted in a rescue of the wing morphology. Taken together, these findings suggest that the responsiveness of Shh to FGF is mediated, at least in part, by PKCs.
Consequences of Hox gene duplication in the vertebrates: an investigation of the zebrafish Hox paralogue group 1 genes
Authors: McClintock James M. , Carlson Robin , Mann Devon M. , Prince Victoria E.
Published: April 2021

As a result of a whole genome duplication event in the lineage leading to teleosts, the zebrafish has seven clusters of Hox patterning genes, rather than four, as described for tetrapod vertebrates. To investigate the consequences of this genome duplication, we have carried out a detailed comparison of genes from a single Hox paralogue group, paralogue group (PG) 1. We have analyzed the sequences, expression patterns and potential functions of all four of the zebrafish PG1 Hox genes, and compared our data with that available for the three mouse genes. As the basic functions of Hox genes appear to be tightly constrained, comparison with mouse data has allowed us to identify specific changes in the developmental roles of Hox genes that have occurred during vertebrate evolution. We have found variation in expression patterns, amino acid sequences within functional domains, and potential gene functions both within the PG1 genes of zebrafish, and in comparison to mouse PG1 genes. We observed novel expression patterns in the midbrain, such that zebrafish hoxa1a and hoxc1a are expressed anterior to the domain traditionally thought to be under Hox patterning control. The hoxc1a gene shows significant coding sequence changes in known functional domains, which correlate with a reduced capacity to cause posteriorizing transformations. Moreover, the hoxb1 duplicate genes have differing functional capacities, suggesting divergence after duplication. We also find that an intriguing function ‘shuffling’ between paralogues has occurred, such that one of the zebrafish hoxb1 duplicates, hoxb1b, performs the role in hindbrain patterning played in mouse by the non-orthologous Hoxa1 gene.
Knockout mice reveal a contribution of the extracellular matrix molecule tenascin-C to neural precursor proliferation and migration
Authors: Garcion Emmanuel , Faissner Andreas , ffrench-Constant Charles
Published: April 2021

The extracellular matrix glycoprotein tenascin-C is widely expressed in the vertebrate central nervous system (CNS) during development and repair. Despite multiple effects of tenascin-C on cell behaviour in culture, no structural abnormalities of the CNS and other organs have been found in adult tenascin-C-null mice, raising the question of whether this glycoprotein has a significant role in vivo. Using a transgenic approach, we have demonstrated that tenascin-C regulates both cell proliferation and migration in oligodendrocyte precursors during development. Knockout mice show increased rates of oligodendrocyte precursor migration along the optic nerve and reduced rates of oligodendrocyte precursor proliferation in different regions of the CNS. Levels of programmed cell death were reduced in areas of myelination at later developmental stages,providing a potential corrective mechanism for any reduction in cell numbers that resulted from the proliferation phenotype. The effects on cell proliferation are mediated via the αvβ3 integrin and an interaction with the platelet-derived growth factor-stimulated mitogenic pathway, emphasising the importance of both CNS extracellular matrix and integrin growth factor interactions in the regulation of neural precursor behaviour.
Math5is required for retinal ganglion cell and optic nerve formation
Authors: Brown Nadean L. , Patel Sima , Brzezinski Joseph , Glaser Tom
Published: April 2021

The vertebrate retina contains seven major neuronal and glial cell types in an interconnected network that collects, processes and sends visual signals through the optic nerve to the brain. Retinal neuron differentiation is thought to require both intrinsic and extrinsic factors, yet few intrinsic gene products have been identified that direct this process. Math5 (Atoh7) encodes a basic helix-loop-helix (bHLH) transcription factor that is specifically expressed by mouse retinal progenitors. Math5 is highly homologous to atonal, which is critically required for R8 neuron formation during Drosophila eye development. Like R8 cells in the fly eye, retinal ganglion cells (RGCs) are the first neurons in the vertebrate eye. Here we show that Math5 mutant mice are fully viable, yet lack RGCs and optic nerves. Thus, two evolutionarily diverse eye types require atonal gene family function for the earliest stages of retinal neuron formation. At the same time, the abundance of cone photoreceptors is significantly increased in Math5−/− retinae, suggesting a binary change in cell fate from RGCs to cones. A small number of nascent RGCs are detected during embryogenesis, but these fail to develop further, suggesting that committed RGCs may also require Math5 function.
Hedgehog-dependent oligodendrocyte lineage specification in the telencephalon
Authors: Tekki-Kessaris Nicoletta , Woodruff Rachel , Hall Anita C. , Gaffield William , Kimura Shioko , Stiles Charles D. , Rowitch David H. , Richardson William D.
Published: April 2021

In the caudal neural tube, oligodendrocyte progenitors (OLPs) originate in the ventral neuroepithelium under the influence of Sonic hedgehog (SHH), then migrate throughout the spinal cord and brainstem before differentiating into myelin-forming cells. We present evidence that oligodendrogenesis in the anterior neural tube follows a similar pattern. We show that OLPs in the embryonic mouse forebrain express platelet-derived growth factor alpha-receptors (PDGFRA), as they do in more caudal regions. They first appear within a region of anterior hypothalamic neuroepithelium that co-expresses mRNA encoding SHH, its receptor PTC1 (PTCH) and the transcription factors OLIG1, OLIG2 and SOX10. Pdgfra-positive progenitors later spread through the forebrain into areas where Shh is not expressed, including the cerebral cortex. Cyclopamine inhibited OLP development in cultures of mouse basal forebrain, suggesting that hedgehog (HH) signalling is obligatory for oligodendrogenesis in the ventral telencephalon. Moreover, Pdgfra-positive progenitors did not appear on schedule in the ventral forebrains of Nkx2.1 null mice, which lack the telencephalic domain of Shh expression. However, OLPs did develop in cultures of Nkx2.1−/− basal forebrain and this was blocked by cyclopamine. OLPs also developed in neocortical cultures, even though Shh transcripts could not be detected in the embryonic cortex. Here, too, the appearance of OLPs was suppressed by cyclopamine. In keeping with these findings, we detected mRNA encoding SHH and Indian hedgehog (IHH) in both Nkx2.1−/− basal forebrain cultures and neocortical cultures. Overall, the data are consistent with the idea that OLPs in the telencephalon, possibly even some of those in the cortex, develop under the influence of SHH in the ventral forebrain.
Large-scale cDNA analysis of the maternal genetic information in the egg ofHalocynthia roretzifor a gene expression catalog of ascidian development
Authors: Makabe Kazuhiro W. , Kawashima Takeshi , Kawashima Shuichi , Minokawa Takuya , Adachi Asako , Kawamura Hiroshi , Ishikawa Hisayoshi , Yasuda Riho , Yamamoto Hiroki , Kondoh Keisuke , Arioka Sachiko , Sasakura Yasunori , Kobayashi Ako , Yagi Kasumi , Shojima Keisuke , Kondoh Yuki , Kido Sumina , Tsujinami Mayu , Nishimura Nahoko , Takahashi Miyuki , Nakamura Tetsuji , Kanehisa Minoru , Ogasawara Michio , Nishikata Takahito , Nishida Hiroki
Published: April 2021

The ascidian egg is a well-known mosaic egg. In order to investigate the molecular nature of the maternal genetic information stored in the egg, we have prepared cDNAs from the mRNAs in the fertilized eggs of the ascidian, Halocynthia roretzi. The cDNAs of the ascidian embryo were sequenced, and the localization of individual mRNA was examined in staged embryos by whole-mount in situ hybridization. The data obtained were stored in the database MAGEST (http://www.genome.ad.jp/magest) and further analyzed. A total of 4240 cDNA clones were found to represent 2221 gene transcripts, including at least 934 different protein-coding sequences. The mRNA population of the egg consisted of a low prevalence, high complexity sequence set. The majority of the clones were of the rare sequence class, and of these, 42% of the clones showed significant matches with known peptides, mainly consisting of proteins with housekeeping functions such as metabolism and cell division. In addition, we found cDNAs encoding components involved in different signal transduction pathways and cDNAs encoding nucleotide-binding proteins. Large-scale analyses of the distribution of the RNA corresponding to each cDNA in the eight-cell, 110-cell and early tailbud embryos were simultaneously carried out. These analyses revealed that a small fraction of the maternal RNAs were localized in the eight-cell embryo, and that 7.9% of the clones were exclusively maternal, while 40.6% of the maternal clones showed expression in the later stages. This study provides global insights about the genes expressed during early development.
CRTF is a novel transcription factor that regulates multiple stages ofDictyosteliumdevelopment
Authors: Mu Xiuqian , Spanos Seth A. , Shiloach Joseph , Kimmel Alan
Published: April 2021

During aggregation, Dictyostelium establish nanomolar oscillation waves of extracellular cAMP, but as development progresses, cells become responsive to higher, non-fluctuating concentrations of cAMP. The regulation of the promoter responsible for expression of cAMP receptor subtype 1, CAR1, during aggregation reflects these signaling variations. Transcription of CAR1 from the early, aggregation promoter is activated by cAMP pulsing, but is repressed by continuous exposure to micromolar concentrations of cAMP. Deletion and mutation analyses of this promoter had defined an element essential for cAMP-regulated expression, and mobility shift assay, DNA crosslinking and DNase I footprinting experiments had identified a nuclear protein (CRTF) with zinc-dependent sequence binding specificity. In our study, CRTF was purified to homogeneity, peptides were sequenced and full-length cDNAs were obtained. The deduced CRTF protein is ∼100 kDa with a C-terminal, zinc finger-like motif required for DNA binding; CRTF purified from cells, however, represents only a 40 kDa C-terminal fragment that retains DNA-binding activity.

As might have been predicted if CRTF were essential for the regulation of CAR1, crtf-null strains fail to develop under standard conditions or to exhibit induced expression of CAR1 or other cAMP-regulated genes. Furthermore, crtf-nulls also fail to sporulate, even under conditions that bypass the dependence on early cAMP signaling pathways. In addition, early developmental events of crtf-null strains could be rescued with exogenous cAMP treatment, constitutive expression of CAR1 or co-development with wild-type cells; however, these treatments were insufficient to promote sporulation. This suggests a cell-autonomous role for CRTF during late development that is separate from its capacity to control CAR1 expression. Finally, ablation of CRTF promotes a precocious induction of certain cAMP-dependent gene expression pathways. We suggest that CRTF may function to help insulate distinct pathways from simultaneous and universal activation by cAMP. CRTF, thus, exhibits multiple complex and independent regulatory functions during Dictyostelium development.
Polarized basolateral cell motility underlies invagination and convergent extension of the ascidian notochord
Authors: Munro Edwin M. , Odell Garrett M.
Published: April 2021

We use 3D time-lapse analysis of living embryos and laser scanning confocal reconstructions of fixed, staged, whole-mounted embryos to describe three-dimensional patterns of cell motility, cell shape change, cell rearrangement and tissue deformation that accompany formation of the ascidian notochord. We show that notochord formation involves two simultaneous processes occurring within an initially monolayer epithelial plate: The first is invagination of the notochord plate about the axial midline to form a solid cylindrical rod. The second is mediolaterally directed intercalation of cells within the plane of the epithelial plate, and then later about the circumference of the cylindrical rod, that accompanies its extension along the anterior/posterior (AP) axis. We provide evidence that these shape changes and rearrangements are driven by active extension of interior basolateral notochord cell edges directly across the faces of their adjacent notochord neighbors in a manner analogous to leading edge extension of lamellapodia by motile cells in culture. We show further that local edge extension is polarized with respect to both the AP axis of the embryo and the apicobasal axis of the notochord plate. Our observations suggest a novel view of how active basolateral motility could drive both invagination and convergent extension of a monolayer epithelium. They further reveal deep similarities between modes of notochord morphogenesis exhibited by ascidians and other chordate embryos, suggesting that cellular mechanisms of ascidian notochord formation may operate across the chordate phylum.
Characterisation ofcis-acting sequences reveals a biphasic, axon-dependent regulation ofKrox20during Schwann cell development
Authors: Ghislain Julien , Desmarquet-Trin-Dinh Carole , Jaegle Martine , Meijer Dies , Charnay Patrick , Frain Monique
Published: April 2021

In Schwann cells (SC), myelination is controlled by the transcription factor gene Krox20/Egr2. Analysis of cis-acting elements governing Krox20 expression in SC revealed the existence of two separate elements. The first, designated immature Schwann cell element (ISE), was active in immature but not myelinating SC, whereas the second, designated myelinating Schwann cell element (MSE), was active from the onset of myelination to adulthood in myelinating SC. In vivo sciatic nerve regeneration experiments demonstrated that both elements were activated during this process, in an axon-dependent manner. Together the activity of these elements reproduced the profile of Krox20 expression during development and regeneration. Genetic studies showed that both elements were active in a Krox20 mutant background, while the activity of the MSE, but likely not of the ISE, required the POU domain transcription factor Oct6 at the time of myelination. The MSE was localised to a 1.3 kb fragment, 35 kb downstream of Krox20. The identification of multiple Oct6 binding sites within this fragment suggested that Oct6 directly controls Krox20 transcription. Taken together, these data indicate that, although Krox20 is expressed continuously from 15.5 dpc in SC, the regulation of its expression is a biphasic, axon-dependent phenomenon involving two cis-acting elements that act in succession during development. In addition, they provide insight into the complexity of the transcription factor regulatory network controlling myelination.
Ypsilon Schachtel, aDrosophilaY-box protein, acts antagonistically to Orb in theoskarmRNA localization and translation pathway
Authors: Mansfield Jennifer H. , Wilhelm James E. , Hazelrigg Tulle
Published: April 2021

Subcellular localization of mRNAs within the Drosophila oocyte is an essential step in body patterning. Yps, a Drosophila Y-box protein, is a component of an ovarian ribonucleoprotein complex that also contains Exu, a protein that plays an essential role in mRNA localization. Y-box proteins are known translational regulators, suggesting that this complex might regulate translation as well as mRNA localization. Here we examine the role of the yps gene in these events. We show that yps interacts genetically with orb, a positive regulator of oskar mRNA localization and translation. The nature of the genetic interaction indicates that yps acts antagonistically to orb. We demonstrate that Orb protein is physically associated with both the Yps and Exu proteins, and that this interaction is mediated by RNA. We propose a model wherein Yps and Orb bind competitively to oskar mRNA with opposite effects on translation and RNA localization.
Functional dissection of theDrosophilamodifier of variegationSu(var)3-7
Authors: Jaquet Yannis , Delattre Marion , Spierer Anne , Spierer Pierre
Published: April 2021

An increase in the dose of the heterochromatin-associated Su(var)3-7 protein of Drosophila augments the genomic silencing of position-effect variegation. We have expressed a number of fragments of the protein in flies to assign functions to the different domains. Specific binding to pericentric heterochromatin depends on the C-terminal half of the protein. The N terminus, containing six of the seven widely spaced zinc fingers, is required for binding to bands on euchromatic arms, with no preference for pericentric heterochromatin. In contrast to the enhancing properties of the full-length protein, the N terminus half has no effect on heterochromatin-dependent position-effect variegation. In contrast, the C terminus moiety suppresses variegation. This dominant negative effect on variegation could result from association of the fragment with the wild type endogenous protein. Indeed, we have found and mapped a domain of self-association in this C-terminal half. Furthermore, a small fragment of the C-terminal region actually depletes pericentric heterochromatin from endogenous Su(var)3-7 and has a very strong suppressor effect. This depletion is not followed by a depletion of HP1, a companion of Su(var)3-7. This indicates that Su(var)3-7 does not recruit HP1 to heterochromatin. We propose in conclusion that the association of Su(var)3-7 to heterochromatin depends on protein-protein interaction mediated by the C-terminal half of the sequence, while the silencing function requires also the N-terminal half containing the zinc fingers.
Six3inactivation reveals its essential role for the formation and patterning of the vertebrate eye
Authors: Carl Matthias , Loosli Felix , Wittbrodt Joachim
Published: April 2021

The establishment of retinal identity and the subsequent patterning of the optic vesicle are the key steps in early vertebrate eye development. To date little is known about the nature and interaction of the genes controlling these steps. So far few genes have been identified that, when over-expressed, can initiate ectopic eye formation. Of note is Six3, which is expressed exclusively in the anterior neural plate. However, ‘loss of function’ analysis has not been reported. Using medaka fish, we show that vertebrate Six3 is necessary for patterning of the anterior neuroectoderm including the retina anlage. Inactivation of Six3 function by morpholino knock-down results in the lack of forebrain and eyes. Corroborated by gain-of-function experiments, graded interference reveals an additional role of Six3 in the proximodistal patterning of the optic vesicle. During both processes of vertebrate eye formation, Six3 cooperates with Pax6.
Rescue of cleft palate inMsx1-deficient mice by transgenicBmp4reveals a network of BMP and Shh signaling in the regulation of mammalian palatogenesis
Authors: Zhang Zunyi , Song Yiqiang , Zhao Xiang , Zhang Xiaoyun , Fermin Cesar , Chen YiPing
Published: April 2021

Cleft palate, the most frequent congenital craniofacial birth defects in humans, arises from genetic or environmental perturbations in the multi-step process of palate development. Mutations in the MSX1 homeobox gene are associated with non-syndromic cleft palate and tooth agenesis in humans. We have used Msx1-deficient mice as a model system that exhibits severe craniofacial abnormalities, including cleft secondary palate and lack of teeth, to study the genetic regulation of mammalian palatogenesis. We found that Msx1 expression was restricted to the anterior of the first upper molar site in the palatal mesenchyme and that Msx1 was required for the expression of Bmp4 and Bmp2 in the mesenchyme and Shh in the medial edge epithelium (MEE) in the same region of developing palate. In vivo and in vitro analyses indicated that the cleft palate seen in Msx1 mutants resulted from a defect in cell proliferation in the anterior palatal mesenchyme rather than a failure in palatal fusion. Transgenic expression of human Bmp4 driven by the mouse Msx1 promoter in the Msx1–/– palatal mesenchyme rescued the cleft palate phenotype and neonatal lethality. Associated with the rescue of the cleft palate was a restoration of Shh and Bmp2 expression, as well as a return of cell proliferation to the normal levels. Ectopic Bmp4 appears to bypass the requirement for Msx1 and functions upstream of Shh and Bmp2 to support palatal development. Further in vitro assays indicated that Shh (normally expressed in the MEE) activates Bmp2 expression in the palatal mesenchyme which in turn acts as a mitogen to stimulate cell division. Msx1 thus controls a genetic hierarchy involving BMP and Shh signals that regulates the growth of the anterior region of palate during mammalian palatogenesis. Our findings provide insights into the cellular and molecular etiology of the non-syndromic clefting associated with Msx1 mutations.
Blood-forming potential of vascular endothelium in the human embryo
Authors: Oberlin Estelle , Tavian Manuela , Blazsek Istvàn , Péault Bruno
Published: April 2021

Hematopoietic cells arise first in the third week of human ontogeny inside yolk sac developing blood vessels, then, one week later and independently, from the wall of the embryonic aorta and vitelline artery. To address the suggested derivation of emerging hematopoietic stem cells from the vessel endothelium, endothelial cells have been sorted by flow cytometry from the yolk sac and aorta and cultured in the presence of stromal cells that support human multilineage hematopoiesis. Embryonic endothelial cells were most accurately selected on CD34 or CD31 surface expression and absence of CD45, which guaranteed the absence of contaminating hematopoietic cells. Yet, rigorously selected endothelial cells yielded a progeny of myelo-lymphoid cells in culture. The frequency of hemogenic endothelial cells in the yolk sac and aorta reflected the actual blood-forming activity of these tissues, as a function of developmental age. Even less expected, a subset of endothelial cells sorted similarly from the embryonic liver and fetal bone marrow also exhibited blood-forming potential. These results suggest that a part at least of emerging hematopoietic cells in the human embryo and fetus originate in vascular walls.