Small business owners’ success criteria, a values approach to personal differences

This study of 150 Dutch small business owners, identified through business/ network directories, investigated relationships between owners’ understanding of success and their personal values. Business owners ranked 10 success criteria. Per- sonal satisfaction, profitability, and satisfied stakeholders ranked highest. Multidi- mensional scaling techniques revealed two dimensions underlying the rank order of success criteria: person-oriented (personal satisfaction versus business growth) and business-oriented (profitability versus contributing back to society). Furthermore, business growth, profitability, and innovativeness were guided by self-enhancing value orientations (power and achievement). Softer success criteria, such as having satisfied stakeholders and a good work–life balance, were guided by self-transcendent value orientations (benevolence and universalism)

Investigation of hospital discharge cases and SARS-CoV-2 introduction into Lothian care homes

Background The first epidemic wave of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) in Scotland resulted in high case numbers and mortality in care homes. In Lothian, over one-third of care homes reported an outbreak, while there was limited testing of hospital patients discharged to care homes. Aim To investigate patients discharged from hospitals as a source of SARS-CoV-2 introduction into care homes during the first epidemic wave. Methods A clinical review was performed for all patients discharges from hospitals to care homes from 1st March 2020 to 31st May 2020. Episodes were ruled out based on coronavirus disease 2019 (COVID-19) test history, clinical assessment at discharge, whole-genome sequencing (WGS) data and an infectious period of 14 days. Clinical samples were processed for WGS, and consensus genomes generated were used for analysis using Cluster Investigation and Virus Epidemiological Tool software. Patient timelines were obtained using electronic hospital records. Findings In total, 787 patients discharged from hospitals to care homes were identified. Of these, 776 (99%) were ruled out for subsequent introduction of SARS-CoV-2 into care homes. However, for 10 episodes, the results were inconclusive as there was low genomic diversity in consensus genomes or no sequencing data were available. Only one discharge episode had a genomic, time and location link to positive cases during hospital admission, leading to 10 positive cases in their care home. Conclusion The majority of patients discharged from hospitals were ruled out for introduction of SARS-CoV-2 into care homes, highlighting the importance of screening all new admissions when faced with a novel emerging virus and no available vaccine

SARS-CoV-2 Omicron is an immune escape variant with an altered cell entry pathway

Vaccines based on the spike protein of SARS-CoV-2 are a cornerstone of the public health response to COVID-19. The emergence of hypermutated, increasingly transmissible variants of concern (VOCs) threaten this strategy. Omicron (B.1.1.529), the fifth VOC to be described, harbours multiple amino acid mutations in spike, half of which lie within the receptor-binding domain. Here we demonstrate substantial evasion of neutralization by Omicron BA.1 and BA.2 variants in vitro using sera from individuals vaccinated with ChAdOx1, BNT162b2 and mRNA-1273. These data were mirrored by a substantial reduction in real-world vaccine effectiveness that was partially restored by booster vaccination. The Omicron variants BA.1 and BA.2 did not induce cell syncytia in vitro and favoured a TMPRSS2-independent endosomal entry pathway, these phenotypes mapping to distinct regions of the spike protein. Impaired cell fusion was determined by the receptor-binding domain, while endosomal entry mapped to the S2 domain. Such marked changes in antigenicity and replicative biology may underlie the rapid global spread and altered pathogenicity of the Omicron variant

The Role of Kinesins in Cell Fate Determination During Neurogenesis

The mammalian brain is a complex organ, the result of a very specific and regulated differentiation process. Although there are many different cell types in the mammalian brain, neurons make up the bulk of the tissue. Neurons come from the divisions of radial glial progenitors (RGPs), which are columnar stem cells in the developing brain. These cells undergo two types of division: symmetric or asymmetric. Symmetric divisions expand the stem cell population, resulting in two new RGPs. Symmetric divisions are critical for ensuring the stem cell population is not depleted too quickly in development. Asymmetric divisions are neurogenic, producing one RGP and one cell that will either differentiate into one neuron, or an intermediate progenitor (IP) that will divide again and produce two to four neurons (Shitamukai, Konno, and Matsuzaki 2011). Several factors have been linked to this determination, including mitotic spindle orientation, centrosomal inheritance, and exposure to proliferative factors, like sonic hedgehog and Notch (Chenn and McConnell 1995; Gaiano and Fishell 2002; Han 2016). This work will focus on spindle orientation, which has been linked to cell fate in many contexts (Lancaster and Knoblich 2012; Williams and Fuchs 2013; Chenn and McConnell 1995). Spindle orientationmust be tightly controlled in order to expand the RGP cell population in early development, then, with more randomized spindles, to shift to producing neural precursors during cortical expansion (Götz and Huttner 2005). While the exact mechanism is still unknown, the orientation of the mitotic spindle relative to the ventricular surface at the time of division affects what type of division occurs (Lancaster and Knoblich 2012). A related process in RGP neural production is interkinetic nuclear migration (INM), in which the RGP nucleus travels apically and basally in a cell-cycle dependent manner (Noctor et al. 2001; Sauer 1935; Hu et al. 2013). The RGP only divides when the nucleus reaches the apical surface; why this occurs is still not known. INM ensures that only a small population of RGPs is dividing in a controlled manner, allowing for cells to interpret polarity cues and orientthe spindle while dividing. One protein that is important to multiple processes in neuronal development is Kif1A. Kif1A is a kinesin motor that has been shown to be critical for INM, in particular for transporting the nucleus basally after division. When Kif1A expression is reduced using shRNA, RGPs fail to migrate away from the ventricular surface, but continue to go through the cell cycle at a normal rate (Carabalona, Hu, and Vallee 2016). Additionally, RGPs that lack Kif1A also exhibit more horizontal and symmetric divisions. This indicates that Kif1a is involved in asymmetric, oblique divisions that produce neurons. Thus, without Kif1a, RGPs produce fewer neurons, instead expanding the RGP cell population. Another kinesin that may be involved in spindle orientation is Kif13B. Kif13B is in the same kinesin-3 subfamily as Kif1A. While structurally very similar to Kif1A, it does have distinct features. It contains a CAP-gly domain, used for binding to the plus end of microtubules. This domain is absent from other kinesin-3 family members, including the most closely related,Kif13A. Kif13B has been shown to be critical for spindle orientation in polarized Drosophila S2 cells, as well as in neuroblasts (Carabalona, Hu, and Vallee 2016; Siegrist and Doe 2005). Kif13B functions to anchor the mitotic spindle to other factors at the cell cortex during mitosis. This occurs through direct interaction with Discs large (Dlg1), which then connects to other factors at the cell membrane, including G?i, LGN, and NuMA. This is a critical process to ensure daughter cells are properly specified. Many of these factors, including LGN and NuMA have been identified as important spindle regulators in RGP divisions as well. Kif13B binds to Dlg1 and to 14-3-3 ?, which is bound to 14-3-3 ?, bound to NudE and Dynein, connecting the Kif13B to Dynein (Lu and Prehoda 2013). Kif13B, as a kinesin, moves along microtubules towards the plus end. Dynein moves in the opposite direction, towards the minus end. The connection of two opposing motors moving in opposite directions may serve to put tension on the spindle and prevent it from freely moving within the cell. When Kif13B is knocked down or removed in cells, the spindle orients randomly in the cell, not in line with LGN or NuMA at the cell cortex (Siegrist and Doe 2005; Lu and Prehoda 2013). This indicates that in mammalian systems, it likely is important for maintaining orientation, and its loss in RGPs would result in random orientation as well. This would result in more neurogenic divisions in RGPs, which is the opposite of the effect seen with Kif1a shRNA. By using in utero electroporation of embryonic rat brains as well as a mouse model ofKif13b knockout in RGPs, I have shown that Kif13B and Kif1A have opposing roles in neurogenesis. This difference can be traced to an alteration of IP production, which Kif1A shRNA decreases, and Kif13b shRNA increases. This can be further traced to the opposing effects on spindle orientation of dividing RGPs. Kif1a shRNA results in more horizontal spindle angles while Kif13b shRNA or deletion results in more random spindle angles. While the kinesin-3 family members are very similar in structure, there are key differences between them. Kif1A has a cargo binding domain at its C terminus, the pleckstrin homology (PH) domain. Kif13B contains a CAP-gly domain. This difference in tail domains would presumably allow Kif13B to bind to microtubule plus ends, while Kif1A would dissociate from the spindle. This difference, therefore, could explain why these two very similar kinesins appear to be performing the opposite roles in spindle orientation. This work provides evidence for a novel mechanism of regulation of neuron production in the mammalian cortex

A two-kinesin mechanism controls neurogenesis in the developing brain

Abstract During the course of brain development, Radial Glial Progenitor (RGP) cells give rise to most of the neurons required for a functional cortex. RGPs can undergo symmetric divisions, which result in RGP duplication, or asymmetric divisions, which result in one RGP as well as one to four neurons. The control of this balance is not fully understood, but must be closely regulated to produce the cells required for a functioning cortex, and to maintain the stem cell pool. In this study, we show that the balance between symmetric and asymmetric RGP divisions is in part regulated by the actions of two kinesins, Kif1A and Kif13B, which we find have opposing roles in neurogenesis through their action on the mitotic spindle in dividing RGPs. We find that Kif1A promotes neurogenesis, whereas Kif13B promotes symmetric, non-neurogenic divisions. Interestingly, the two kinesins are closely related in structure, and members of the same kinesin-3 subfamily, thus their opposing effects on spindle orientation appear to represent a novel mechanism for the regulation of neurogenesis

The Role of Nde1 Phosphorylation in Interkinetic Nuclear Migration and Neural Migration During Cortical Development

International audienceNde1 is a cytoplasmic dynein regulatory protein with important roles in vertebrate brain development. One noteworthy function is in the nuclear oscillatory behavior in neural progenitor cells, the control and mechanism of which remain poorly understood. Nde1 contains multiple phosphorylation sites for the cell cycle-dependent protein kinase CDK1, though the function of these sites is not well understood. To test their role in brain development we expressed phosphorylation-state mutant forms of Nde1 in embryonic rat brains using in utero electroporation. We find that Nde1 T215 and T243 phosphomutants block apical interkinetic nuclear migration (INM) and, consequently, mitosis in radial glial progenitor cells. Another Nde1 phosphomutant at T246 also interfered with mitotic entry without affecting INM, suggesting a more direct role for Nde1 T246 in mitotic regulation. We also found that the Nde1 S214F mutation, which is associated with schizophrenia, inhibits Cdk5 phosphorylation at an adjacent residue which causes alterations in neuronal lamination. These results together identify important new roles for Nde1 phosphorylation in neocortical development and disease, and represent the first evidence for Nde1 phosphorylation roles in INM and neuronal lamination

Role of Nesprin-2 and RanBP2 in BICD2-associated brain developmental disorders.

Bicaudal D2 (BICD2) is responsible for recruiting cytoplasmic dynein to diverse forms of subcellular cargo for their intracellular transport. Mutations in the human BICD2 gene have been found to cause an autosomal dominant form of spinal muscular atrophy (SMA-LED2), and brain developmental defects. Whether and how the latter mutations are related to roles we and others have identified for BICD2 in brain development remains little understood. BICD2 interacts with the nucleoporin RanBP2 to recruit dynein to the nuclear envelope (NE) of Radial Glial Progenitor cells (RGPs) to mediate their well-known but mysterious cell-cycle-regulated interkinetic nuclear migration (INM) behavior, and their subsequent differentiation to form cortical neurons. We more recently found that BICD2 also mediates NE dynein recruitment in migrating post-mitotic neurons, though via a different interactor, Nesprin-2. Here, we report that Nesprin-2 and RanBP2 compete for BICD2-binding in vitro. To test the physiological implications of this behavior, we examined the effects of known BICD2 mutations using in vitro biochemical and in vivo electroporation-mediated brain developmental assays. We find a clear relationship between the ability of BICD2 to bind RanBP2 vs. Nesprin-2 in controlling of nuclear migration and neuronal migration behavior. We propose that mutually exclusive RanBP2-BICD2 vs. Nesprin-2-BICD2 interactions at the NE play successive, critical roles in INM behavior in RGPs and in post-mitotic neuronal migration and errors in these processes contribute to specific human brain malformations