Cell polarization during monopolar cytokinesis

During cytokinesis, a specialized set of proteins is recruited to the equatorial region between spindle poles by microtubules and actin filaments, enabling furrow assembly and ingression before cell division. We investigate the mechanisms underlying regional specialization of the cytoskeleton in HeLa cells undergoing drug-synchronized monopolar cytokinesis. After forced mitotic exit, the cytoskeleton of monopolar mitotic cells is initially radially symmetric but undergoes a symmetry-breaking reaction that simultaneously polarizes microtubules and the cell cortex, with a concentration of cortical furrow markers into a cap at one side of the cell. Polarization requires microtubules, F-actin, RhoA, Myosin II activity, and Aurora B kinase activity. Aurora B localizes to actin cables in a gap between the monopolar midzone and the furrow-like cortex, suggesting a communication between them. We propose that feedback loops between cortical furrow components and microtubules promote symmetry breaking during monopolar cytokinesis and regional specialization of the cytoskeleton during normal bipolar cytokinesis

Genetic and ecological consequences of recent habitat fragmentation in a narrow endemic plant species within an urban context

Understanding the timescales that shape spatial genetic structure is pivotal to ascertain the impact of habitat fragmentation on the genetic diversity and reproductive viability of long-lived plant populations. Combining genetic and ecological information with current and past fragmentation conditions allows the identification of the main drivers important in shaping population structure and declines in reproduction, which is crucial for informing conservation strategies. Using historic aerial photographs, we defined the past fragmentation conditions for the shrub Conospermum undulatum, a species now completely embedded in an urban area. We explored the impact of current and past conditions on its genetic layout and assessed the effects of genetic and environmental factors on its reproduction. The historically high structural connectivity was evident in the genetics of the species. Despite the current intense fragmentation, we found similar levels of genetic diversity across populations and a weak spatial genetic structure. Historical connectivity was negatively associated with genetic differentiation among populations and positively related to within-population genetic diversity. Variation partitioning of reproductive performance explained ~ 66% of the variance, showing significant influences for genetic (9%), environmental (15%), and combined (42%) fractions. Our study highlights the importance of considering the historical habitat dynamics when investigating fragmentation consequences in long-lived plants. A detailed characterization of fragmentation from 1953 has shown how low levels of genetic fixation are due to extensive gene flow through the non-fragmented landscape. Moreover, knowledge of the relationships between genetic and environmental variation and reproduction can help to implement effective conservation strategies, particularly in highly dynamic landscapes

Methodology of Natsal-COVID Wave 2: A large, quasi-representative, longitudinal survey measuring the impact of COVID-19 on sexual and reproductive health in Britain [version 1; peer review: awaiting peer review]

Background: The National Surveys of Sexual Attitudes and Lifestyles COVID study (Natsal-COVID) was designed to understand the impact of COVID-19 on Britain’s sexual and reproductive health (SRH). Natsal-COVID Wave 1 survey and qualitative follow-up interviews were conducted in 2020. The Wave 2 survey was designed to capture one-year prevalence estimates for key SRH outcomes and measure changes over the first year of the pandemic. We describe the Wave 2 survey methodology and assess the sample representativeness. Methods: Natsal-COVID Wave 2 was conducted March-April 2021; approximately one year after the start of Britain’s first national lockdown. Data were collected using an online web-panel survey administered by Ipsos. The sample comprised a longitudinal sample of Wave 1 participants who had agreed to re-contact plus a sample of participants residing in Britain, aged 18-59, including a boost sample comprising people aged 18-29. Questions covered reproductive health, relationships, sexual behaviour and SRH service use. Quotas and weighting were used to achieve a quasi-representative sample of the British population. Comparisons were made with recent national probability surveys, Natsal-3 (2010-12) and Natsal-COVID Wave 1 to understand bias. Results: A total of 6,658 individuals completed the survey. In terms of gender, age, ethnicity, and rurality, the weighted Natsal-COVID Wave 2 sample was like the general population. Participants were less likely to be married or to report being in good health than the general population. The longitudinal sample (n=2,098) were broadly like participants who only took part in Wave 1 but were older. Among the sexually active, longitudinal participants were less likely to report multiple sexual partners or a new sexual partner in the past year compared to those who only took part in Wave 1. Conclusions: Natsal-COVID collected longitudinal, quasi-representative population data to enable evaluation of the population-level impact of COVID-19 on SRH and to inform policy

DETECTING AND QUANTIFYING REDUCTIVE DECHLORINATION DURING MONITORED NATURAL ATTENUATION AT THE SAVANNAH RIVER CBRP SITE

Various attenuation mechanisms control the destruction, stabilization, and/or removal of contaminants from contaminated subsurface systems. Measuring the rates of the controlling attenuation mechanisms is a key to employing mass balance as a means to evaluate and monitor the expansion, stability and subsequent shrinkage of a contaminant plume. A team of researchers investigated the use of push-pull tests for measuring reductive dechlorination rates in situ at sites with low chlorinated solvent concentrations (<1 ppm). The field research also examined the synergistic use of a suite of geochemical and microbial assays. Previous push-pull tests applied to environmental remediation objectives focused on general hydrological characterization or on designing bioremediation systems by examining the response of the subsurface to stimulation. In this research, the push-pull technique was tested to determine its ''low-range'' sensitivity and uncertainty. Can these tests quantify relatively low attenuation rates representative of natural attenuation? The results of this research indicate that push-pull testing will be useful for measurement of in situ reductive dechlorination rates for chlorinated solvents at ''Monitored Natural Attenuation'' (MNA) sites. Further, using principal component analysis and other techniques, the research confirmed the usefulness of multiple lines of evidence in site characterization and in upscaling measurements made in individual wells--especially for sites where there is a geochemical gradient or varying geochemical regimes within the contaminant plume

Common and low Frequency variants in MERTK are independently associated with multiple sclerosis susceptibility with discordant association dependent upon HLA-DRB1*15:01 status

Multiple Sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system. The risk of developing MS is strongly influenced by genetic predisposition, and over 100 loci have been established as associated with susceptibility. However, the biologically relevant variants underlying disease risk have not been defined for the vast majority of these loci, limiting the power of these genetic studies to define new avenues of research for the development of MS therapeutics. It is therefore crucial that candidate MS susceptibility loci are carefully investigated to identify the biological mechanism linking genetic polymorphism at a given gene to the increased chance of developing MS. MERTK has been established as an MS susceptibility gene and is part of a family of receptor tyrosine kinases known to be involved in the pathogenesis of demyelinating disease. In this study we have refined the association of MERTK with MS risk to independent signals from both common and low frequency variants. One of the associated variants was also found to be linked with increased expression of MERTK in monocytes and higher expression of MERTK was associated with either increased or decreased risk of developing MS, dependent upon HLA-DRB1*15:01 status. This discordant association potentially extended beyond MS susceptibility to alterations in disease course in established MS. This study provides clear evidence that distinct polymorphisms within MERTK are associated with MS susceptibility, one of which has the potential to alter MERTK transcription, which in turn can alter both susceptibility and disease course in MS patients

Multiple Sclerosis risk variants regulate gene expression in innate and adaptive immune cells

At least 200 single-nucleotide polymorphisms (SNPs) are associated with multiple sclerosis (MS) risk. A key function that could mediate SNP-encoded MS risk is their regulatory effects on gene expression. We performed microarrays using RNA extracted from purified immune cell types from 73 untreated MS cases and 97 healthy controls and then performed Cis expression quantitative trait loci mapping studies using additive linear models. We describe MS risk expression quantitative trait loci associations for 129 distinct genes. By extending these models to include an interaction term between genotype and phenotype, we identify MS risk SNPs with opposing effects on gene expression in cases compared with controls, namely, rs2256814 MYT1 in CD4 cells (q = 0.05) and rs12087340 RF00136 in monocyte cells (q = 0.04). The rs703842 SNP was also associated with a differential effect size on the expression of the METTL21B gene in CD8 cells of MS cases relative to controls (q = 0.03). Our study provides a detailed map of MS risk loci that function by regulating gene expression in cell types relevant to MS

Mutations in KCTD1 Cause Scalp-Ear-Nipple Syndrome

Scalp-ear-nipple (SEN) syndrome is a rare, autosomal-dominant disorder characterized by cutis aplasia of the scalp; minor anomalies of the external ears, digits, and nails; and malformations of the breast. We used linkage analysis and exome sequencing of a multiplex family affected by SEN syndrome to identify potassium-channel tetramerization-domain-containing 1 (KCTD1) mutations that cause SEN syndrome. Evaluation of a total of ten families affected by SEN syndrome revealed KCTD1 missense mutations in each family tested. All of the mutations occurred in a KCTD1 region encoding a highly conserved bric-a-brac, tram track, and broad complex (BTB) domain that is required for transcriptional repressor activity. KCTD1 inhibits the transactivation of the transcription factor AP-2 alpha (TFAP2A) via its BTB domain, and mutations in TFAP2A cause cutis aplasia in individuals with branchiooculofacial syndrome (BOFS), suggesting a potential overlap in the pathogenesis of SEN syndrome and BOFS. the identification of KCTD1 mutations in SEN syndrome reveals a role for this BTB-domain-containing transcriptional repressor during ectodermal development.National Institutes of Health National Human Genome Research InstituteLife Sciences Discovery FundWashington Research FoundationMassachusetts Gen Hosp, Cutaneous Biol Res Ctr, Charlestown, MA 02129 USAUniv Washington, Dept Pediat, Seattle, WA 98195 USAUniv Washington, Dept Genome Sci, Seattle, WA 98195 USAUniv Western Sydney Macarthur, Sch Med, Campbelltown, NSW 2560, AustraliaGenet Learning Disabil Serv, Newcastle, NSW 2298, AustraliaJohns Hopkins Univ, Sch Med, McKusick Nathans Inst Genet Med, Baltimore, MD 21205 USAUniversidade Federal de São Paulo, Dept Morphol & Genet, Clin Genet Ctr, BR-04021001 São Paulo, BrazilPontificia Univ Catolica Parana, Dept Internal Med, BR-1155 Curitiba, Parana, BrazilWestern Gen Hosp, South East Scotland Clin Genet Serv, Edinburgh EH4 2XU, Midlothian, ScotlandUniv Florence, Dept Genet & Mol Med, I-50132 Florence, ItalyHop Necker Enfants Malad, Dept Genet, INSERM, U781, F-75015 Paris, FranceUniv Paris Descartes Sorbonne Paris Cite, Inst Imagine, F-75015 Paris, FranceHop Cote Nacre, CHU Caen, Serv Genet, F-14033 Caen 9, FranceUniv Connecticut, Ctr Hlth, Dept Reconstruct Sci, Farmington, CT 06030 USABoston Childrens Hosp, Dept Plast & Oral Surg, Boston, MA 02115 USATreuman Katz Ctr Pediat Bioeth, Seattle Childrens Res Inst, Seattle, WA 98101 USAUniversidade Federal de São Paulo, Dept Morphol & Genet, Clin Genet Ctr, BR-04021001 São Paulo, BrazilNational Institutes of Health National Human Genome Research Institute: 1U54HG006493National Institutes of Health National Human Genome Research Institute: 1RC2HG005608National Institutes of Health National Human Genome Research Institute: 5RO1HG004316Life Sciences Discovery Fund: 2065508Life Sciences Discovery Fund: 0905001Web of Scienc

Methodology of Natsal-COVID Wave 1: a large, quasi-representative survey with qualitative follow-up measuring the impact of COVID-19 on sexual and reproductive health in Britain.

BACKGROUND: Britain’s National Surveys of Sexual Attitudes and Lifestyles (Natsal) have been undertaken decennially since 1990 and provide a key data source underpinning sexual and reproductive health (SRH) policy. The COVID-19 pandemic disrupted many aspects of sexual lifestyles, triggering an urgent need for population-level data on sexual behaviour, relationships, and service use at a time when gold-standard in-person, household-based surveys with probability sampling were not feasible. We designed the Natsal-COVID study to understand the impact of COVID-19 on the nation’s SRH and assessed the sample representativeness. METHODS: Natsal-COVID Wave 1 data collection was conducted four months (29/7-10/8/2020) after the announcement of Britain’s first national lockdown (23/03/2020). This was an online web-panel survey administered by survey research company, Ipsos MORI. Eligible participants were resident in Britain, aged 18-59 years, and the sample included a boost of those aged 18-29. Questions covered participants’ sexual behaviour, relationships, and SRH service use. Quotas and weighting were used to achieve a quasi-representative sample of the British general population. Participants meeting criteria of interest and agreeing to recontact were selected for qualitative follow-up interviews. Comparisons were made with contemporaneous national probability surveys and Natsal-3 (2010-12) to understand bias. RESULTS: 6,654 participants completed the survey and 45 completed follow-up interviews. The weighted Natsal-COVID sample was similar to the general population in terms of gender, age, ethnicity, rurality, and, among sexually-active participants, numbers of sexual partners in the past year. However, the sample was more educated, contained more sexually-inexperienced people, and included more people in poorer health. CONCLUSIONS: Natsal-COVID Wave 1 rapidly collected quasi-representative population data to enable evaluation of the early population-level impact of COVID-19 and lockdown measures on SRH in Britain. Although sampling was less representative than the decennial Natsals, Natsal-COVID will complement national surveillance data and Natsal-4 (planned for 2022)

Uncoupling the functions of CALM in VAMP sorting and clathrin-coated pit formation.

CALM (clathrin assembly lymphoid myeloid leukemia protein) is a cargo-selective adaptor for the post-Golgi R-SNAREs VAMPs 2, 3, and 8, and it also regulates the size of clathrin-coated pits and vesicles at the plasma membrane. The present study has two objectives: to determine whether CALM can sort additional VAMPs, and to investigate whether VAMP sorting contributes to CALM-dependent vesicle size regulation. Using a flow cytometry-based endocytosis efficiency assay, we demonstrate that CALM is also able to sort VAMPs 4 and 7, even though they have sorting signals for other clathrin adaptors. CALM homologues are present in nearly every eukaryote, suggesting that the CALM family may have evolved as adaptors for retrieving all post-Golgi VAMPs from the plasma membrane. Using a knockdown/rescue system, we show that wild-type CALM restores normal VAMP sorting in CALM-depleted cells, but that two non-VAMP-binding mutants do not. However, when we assayed the effect of CALM depletion on coated pit morphology, using a fluorescence microscopy-based assay, we found that the two mutants were as effective as wild-type CALM. Thus, we can uncouple the sorting function of CALM from its structural role