Connecting the Cytoskeleton to the Endoplasmic Reticulum and Golgi

A tendency in cell biology is to divide and conquer. For example, decades of painstaking work have led to an understanding of endoplasmic reticulum (ER) and Golgi structure, dynamics, and transport. In parallel, cytoskeletal researchers have revealed a fantastic diversity of structure and cellular function in both actin and microtubules. Increasingly, these areas overlap, necessitating an understanding of both organelle and cytoskeletal biology. This review addresses connections between the actin/microtubule cytoskeletons and organelles in animal cells, focusing on three key areas: ER structure and function; ER-to-Golgi transport; and Golgi structure and function. Making these connections has been challenging for several reasons: the small sizes and dynamic characteristics of some components; the fact that organelle-specific cytoskeletal elements can easily be obscured by more abundant cytoskeletal structures; and the difficulties in imaging membranes and cytoskeleton simultaneously, especially at the ultrastructural level. One major concept is that the cytoskeleton is frequently used to generate force for membrane movement, with two potential consequences: translocation of the organelle, or deformation of the organelle membrane. While initially discussing issues common to metazoan cells in general, we subsequently highlight specific features of neurons, since these highly polarized cells present unique challenges for organellar distribution and dynamics

Barber Shops, Salons, and Spas: The Complexity – and Simplicity – Of Implementing Outreach and Enrollment Contracts Under The Affordable Care Act

This article examines the implementation of The Patient Protection and Affordable Care Act (ACA) with a particular focus on the states’ contracted outreach and enrollment services. Having collected administrative and perceptual data from key informants, we examined outreach and enrollment contracts in six states that have reduced the uninsured rate by at least 20% of ACA-eligible population. Our findings suggest that the complexity of the law and its structure, as well as the characteristics of contracting were, in effect, “drowned out” by clear patterns of highly collaborative implementation that involved extensive chains of diverse outreach/enrollment actors. These networks – ranging from experienced health advocacy organizations to community members’ recruiting in local churches, schools and barbershops – were able to put into effect comparatively simple systems with clear, shared goals among on-the-ground actors who broke through the implementation complexity, thereby creating new capacity and achieving significant enrollment gains

Novel Roles for Actin in Mitochondrial Fission

Mitochondrial dynamics, including fusion, fission and translocation, are crucial to cellular homeostasis, with roles in cellular polarity, stress response and apoptosis. Mitochondrial fission has received particular attention, owing to links with several neurodegenerative diseases. A central player in fission is the cytoplasmic dynamin-related GTPase Drp1, which oligomerizes at the fission site and hydrolyzes GTP to drive membrane ingression. Drp1 recruitment to the outer mitochondrial membrane (OMM) is a key regulatory event, which appears to require a pre-constriction step in which the endoplasmic reticulum (ER) and mitochondrion interact extensively, a process termed ERMD (ER-associated mitochondrial division). It is unclear how ER-mitochondrial contact generates the force required for pre-constriction or why pre-constriction leads to Drp1 recruitment. Recent results, however, show that ERMD might be an actin-based process in mammals that requires the ER-associated formin INF2 upstream of Drp1, and that myosin II and other actin-binding proteins might be involved. In this Commentary, we present a mechanistic model for mitochondrial fission in which actin and myosin contribute in two ways; firstly, by supplying the force for pre-constriction and secondly, by serving as a coincidence detector for Drp1 binding. In addition, we discuss the possibility that multiple fission mechanisms exist in mammals

Actin Filaments Target the Oligomeric Maturation of the Dynamin Gtpase Drp1 to Mitochondrial Fission Sites

While the dynamin GTPase Drp1 plays a critical role during mitochondrial fission, mechanisms controlling its recruitment to fission sites are unclear. A current assumption is that cytosolic Drp1 is recruited directly to fission sites immediately prior to fission. Using live-cell microscopy, we find evidence for a different model, progressive maturation of Drp1 oligomers on mitochondria through incorporation of smaller mitochondrially-bound Drp1 units. Maturation of a stable Drp1 oligomer does not forcibly lead to fission. Drp1 oligomers also translocate directionally along mitochondria. Ionomycin, a calcium ionophore, causes rapid mitochondrial accumulation of actin filaments followed by Drp1 accumulation at the fission site, and increases fission rate. Inhibiting actin polymerization, myosin IIA, or the formin INF2 reduces both un-stimulated and ionomycin-induced Drp1 accumulation and mitochondrial fission. Actin filaments bind purified Drp1 and increase GTPase activity in a manner that is synergistic with the mitochondrial protein Mff, suggesting a role for direct Drp1/actin interaction. We propose that Drp1 is in dynamic equilibrium on mitochondria in a fission-independent manner, and that fission factors such as actin filaments target productive oligomerization to fission sites

Controlled and Efficient Hybridization Achieved with DNA Probes Immobilized Solely through Preferential DNA-Substrate Interactions

Quantitatively correlating the response of DNA sensors to clinically and biologically significant sample abundances requires optimizing the reproducibility of hybridization between DNA targets and surface-bound DNA probes. 1,2 Although gold surfaces are not used in commercial fluorescence-based DNA arrays, gold offers many useful properties as a model substrate 3 and has been successfully used in systematic studies of the interactions governing DNA hybridization near interfaces. 4-8 The hybridization behavior of surface-immobilized DNA probes strongly depends on the probe conformation and on the lateral spacing between adjacent probes. Hybridization is generally enhanced for DNA probes that extend away from a surface, in part because steric hindrance is lower for such brushlike probes than for DNA directly adsorbed on gold. At surface densities e5 × 10 12 cm -2 , typical probe sequences (15-30 nucleotides) can hybridize with efficiencies >60%, 7-10 but at probe densities >1 × 10 13 cm -2 hybridization efficiency is often reduced because of increased electrostatic repulsion and steric constraints. 11-13 Surfaces with DNA probes in upright conformations can be prepared following a number of strategies, including adsorption via a thiol incorporated at one end (DNA-SH) or coupling DNA probes to bifunctional monolayers. [4][5][6][7][8][14][15][16][17][18] Preparing DNA probes * To whom correspondence should be addressed. E-mail: opdahl

A mixed methods PAR study investigating social capital as a resource for Black and other racially minoritised communities in the UK:A study protocol

Understanding how different Black and other racially minoritised communities thrive is an emerging priority area in mental health promotion. Literature demonstrates health benefits of social capital (social resources embedded within social networks). However, its effects are not always positive, particularly for certain subpopulations who are already disadvantaged. The CONtributions of social NEtworks to Community Thriving (CONNECT) study will use Participatory Action Research (PAR) to investigate social capital as a resource that benefits (or hinders) racially minoritised communities and their mental health. The CONNECT study was designed within a partnership with community organisations and responds to local policy in two South-East London Boroughs, thereby providing potential channels for the action component of PAR. Taking an anti-racism lens, we acknowledge the underpinning role of racism in creating health inequities. We apply an intersectional framework to be considerate of overlapping forms of oppression such as age, gender, socioeconomic status, and sexual orientation as an essential part of developing effective strategies to tackle health inequities. Key components of this mixed methods PAR study include (1) involving racialised minority community members as peer researchers in the team (2) collecting and analysing primary qualitative data via interviews, photovoice, and community mapping workshops, (3) developing relevant research questions guided by peer researchers and collaborating organisations and analysing secondary quantitative data accordingly, (4) integrating qualitative and quantitative phases, and (5) working closely with community and policy partners to act on our findings and use our research for social change. The PAR approach will allow us to engage community (voluntary sector and government) and academic partners in decision making and help address imbalances in power and resource allocation. Knowledge generated through this collaborative approach will contribute to existing community initiatives, policies, and council strategies. This will ensure the views and experiences of racially minoritised communities drive the changes we are collaboratively committed to achieving.<br/

Breast cancer risk factors in relation to breast density (United States)

OBJECTIVES: Evaluate known breast cancer risk factors in relation to breast density. METHODS: We examined factors in relation to breast density in 144,018 New Hampshire (NH) women with at least one mammogram recorded in a statewide mammography registry. Mammographic breast density was measured by radiologists using the BI-RADS classification; risk factors of interest were obtained from patient intake forms and questionnaires. RESULTS: Initial analyses showed a strong inverse influence of age and body mass index (BMI) on breast density. In addition, women with late age at menarche, late age at first birth, premenopausal women, and those currently using hormone therapy (HT) tended to have higher breast density, while those with greater parity tended to have less dense breasts. Analyses stratified on age and BMI suggested interactions, which were formally assessed in a multivariable model. The impact of current HT use, relative to nonuse, differed across age groups, with an inverse association in younger women, and a positive association in older women (p < 0.0001 for the interaction). The positive effects of age at menarche and age at first birth, and the inverse influence of parity were less apparent in women with low BMI than in those with high BMI (p = 0.04, p < 0.0001 and p = 0.01, respectively, for the interactions). We also noted stronger positive effects for age at first birth in postmenopausal women (p = 0.004 for the interaction). The multivariable model indicated a slight positive influence of family history of breast cancer. CONCLUSIONS: The influence of age at menarche and reproductive factors on breast density is less evident in women with high BMI. Density is reduced in young women using HT, but increased in HT users of age 50 or more

The wide-field, multiplexed, spectroscopic facility WEAVE : survey design, overview, and simulated implementation

Funding for the WEAVE facility has been provided by UKRI STFC, the University of Oxford, NOVA, NWO, Instituto de Astrofísica de Canarias (IAC), the Isaac Newton Group partners (STFC, NWO, and Spain, led by the IAC), INAF, CNRS-INSU, the Observatoire de Paris, Région Île-de-France, CONCYT through INAOE, Konkoly Observatory (CSFK), Max-Planck-Institut für Astronomie (MPIA Heidelberg), Lund University, the Leibniz Institute for Astrophysics Potsdam (AIP), the Swedish Research Council, the European Commission, and the University of Pennsylvania.WEAVE, the new wide-field, massively multiplexed spectroscopic survey facility for the William Herschel Telescope, will see first light in late 2022. WEAVE comprises a new 2-degree field-of-view prime-focus corrector system, a nearly 1000-multiplex fibre positioner, 20 individually deployable 'mini' integral field units (IFUs), and a single large IFU. These fibre systems feed a dual-beam spectrograph covering the wavelength range 366-959 nm at R ∼ 5000, or two shorter ranges at R ∼ 20,000. After summarising the design and implementation of WEAVE and its data systems, we present the organisation, science drivers and design of a five- to seven-year programme of eight individual surveys to: (i) study our Galaxy's origins by completing Gaia's phase-space information, providing metallicities to its limiting magnitude for ∼ 3 million stars and detailed abundances for ∼ 1.5 million brighter field and open-cluster stars; (ii) survey ∼ 0.4 million Galactic-plane OBA stars, young stellar objects and nearby gas to understand the evolution of young stars and their environments; (iii) perform an extensive spectral survey of white dwarfs; (iv) survey  ∼ 400 neutral-hydrogen-selected galaxies with the IFUs; (v) study properties and kinematics of stellar populations and ionised gas in z 1 million spectra of LOFAR-selected radio sources; (viii) trace structures using intergalactic/circumgalactic gas at z > 2. Finally, we describe the WEAVE Operational Rehearsals using the WEAVE Simulator.PostprintPeer reviewe

The wide-field, multiplexed, spectroscopic facility WEAVE: Survey design, overview, and simulated implementation

WEAVE, the new wide-field, massively multiplexed spectroscopic survey facility for the William Herschel Telescope, will see first light in late 2022. WEAVE comprises a new 2-degree field-of-view prime-focus corrector system, a nearly 1000-multiplex fibre positioner, 20 individually deployable 'mini' integral field units (IFUs), and a single large IFU. These fibre systems feed a dual-beam spectrograph covering the wavelength range 366$-$959\,nm at $R\sim5000$, or two shorter ranges at $R\sim20\,000$. After summarising the design and implementation of WEAVE and its data systems, we present the organisation, science drivers and design of a five- to seven-year programme of eight individual surveys to: (i) study our Galaxy's origins by completing Gaia's phase-space information, providing metallicities to its limiting magnitude for $\sim$3 million stars and detailed abundances for $\sim1.5$ million brighter field and open-cluster stars; (ii) survey $\sim0.4$ million Galactic-plane OBA stars, young stellar objects and nearby gas to understand the evolution of young stars and their environments; (iii) perform an extensive spectral survey of white dwarfs; (iv) survey $\sim400$ neutral-hydrogen-selected galaxies with the IFUs; (v) study properties and kinematics of stellar populations and ionised gas in $z<0.5$ cluster galaxies; (vi) survey stellar populations and kinematics in $\sim25\,000$ field galaxies at $0.3\lesssim z \lesssim 0.7$; (vii) study the cosmic evolution of accretion and star formation using $>1$ million spectra of LOFAR-selected radio sources; (viii) trace structures using intergalactic/circumgalactic gas at $z>2$. Finally, we describe the WEAVE Operational Rehearsals using the WEAVE Simulator.Comment: 41 pages, 27 figures, accepted for publication by MNRA