Microglia, the resident macrophages of the CNS, engage in various CNS-specific functions that are critical for development and health. To better study microglia and the properties that distinguish ...them from other tissue macrophage populations, we have optimized serum-free culture conditions to permit robust survival of highly ramified adult microglia under defined-medium conditions. We find that astrocyte-derived factors prevent microglial death ex vivo and that this activity results from three primary components, CSF-1/IL-34, TGF-β2, and cholesterol. Using microglial cultures that have never been exposed to serum, we demonstrate a dramatic and lasting change in phagocytic capacity after serum exposure. Finally, we find that mature microglia rapidly lose signature gene expression after isolation, and that this loss can be reversed by engrafting cells back into an intact CNS environment. These data indicate that the specialized gene expression profile of mature microglia requires continuous instructive signaling from the intact CNS.
•Astrocytic factors allow defined-medium cultures of ramified adult microglia•Microglia rely on TGF-β and exogenous cholesterol for survival in vitro•Serum exposure transforms the phagocytic capacity of cultured microglia•Microglial specification requires continuous instruction by CNS-specific signaling
Bohlen et al. describe a serum-free culture platform for microglia that recapitulates the morphology and process dynamics observed in vivo. They find that serum exposure enhances phagocytosis, and through transcriptomic characterizations show that signature gene expression requires continuous CNS instruction.
The specific function of microglia, the tissue resident macrophages of the brain and spinal cord, has been difficult to ascertain because of a lack of tools to distinguish microglia from other immune ...cells, thereby limiting specific immunostaining, purification, and manipulation. Because of their unique developmental origins and predicted functions, the distinction of microglia from other myeloid cells is critically important for understanding brain development and disease; better toolswould greatly facilitate studies of microglia function in the developing, adult, and injured CNS. Here, we identify transmembrane protein 119 (Tmem119), a cell-surface protein of unknown function, as a highly expressed microglia-specific marker in both mouse and human. We developed monoclonal antibodies to its intracellular and extracellular domains that enable the immunostaining of microglia in histological sections in healthy and diseased brains, as well as isolation of pure nonactivated microglia by FACS. Using our antibodies, we provide, to our knowledge, the first RNAseq profiles of highly pure mouse microglia during development and after an immune challenge. We used these to demonstrate that mouse microglia mature by the second postnatal week and to predict novel microglial functions. Together, we anticipate these resources will be valuable for the future study and understanding of microglia in health and disease.
The harbour seal Phoca vitulina is a ubiquitous pinniped species found throughout coastal waters of the Northern Hemisphere. Harbour seal impacts on ecosystem dynamics may be significant due to their ...high abundance and food web position. Two subspecies exist in North America, P. v. richardii in the Pacific Ocean and P. v. vitulina in the Atlantic. Strong natal philopatry of harbour seals can result in fine-scale genetic structure and isolation by distance. Management of harbour seals is expected to benefit from improved resolution of seal population structure and dynamics. Here, we use genotyping-by-sequencing to genotype 146 harbour seals from the eastern Pacific Ocean (i.e. British Columbia (BC), Oregon and California) and the western Atlantic Ocean (i.e. Québec, Newfoundland and Labrador). Using 12,742 identified variants, we confirm the recently identified elevated genetic diversity in the eastern Pacific relative to the western Atlantic and greatest differentiation between the subspecies. Further, we demonstrate that this is independent of reference genome bias or other potential technical artefacts. Coast-specific analyses with 8933 and 3828 variants in Pacific and Atlantic subspecies, respectively, identify divergence between BC and Oregon-California, and between Québec and Newfoundland-Labrador. Unexpected PCA outlier clusters were observed in two populations due to cryptic relatedness of individuals; subsequently, closely related samples were removed. Admixture analysis indicates an isolation-by-distance signature where Oregon seals contained some of the BC signature, whereas California did not. Additional sampling is needed in the central and north coast of BC to determine whether a discrete separation of populations exists within the region.
ABSTRACTScanlan, AT, Tucker, PS, Dascombe, BJ, Berkelmans, DM, Hiskens, MI, and Dalbo, VJ. Fluctuations in activity demands across game quarters in professional and semiprofessional male basketball. ...J Strength Cond Res 29(11)3006–3015, 2015—Examination of activity demands and stoppage durations across game periods provides useful insight concerning fatigue, tactical strategies, and playing pace in team sports such as basketball. Therefore, the aims of this study were to quantify and compare game activity fluctuations across quarters in professional and semiprofessional basketball players. Video-based time-motion analyses were conducted across multiple games. Frequencies, total durations (in seconds), total distances (in meters), and mean velocities (in meters per second) were calculated for low-intensity movement (≤3 m·s), high-intensity movement (>3 m·s), shuffling, and dribbling activity. Frequencies were determined for jumping and upper-body activity; stoppage durations were also calculated. Separate repeated-measures analysis of variance and Cohenʼs d were used to identify significant differences and quantify the effect sizes between game quarters for all outcome measures, respectively. Pearson correlation analyses were performed to determine the relationship between stoppage duration and all activity measures. The results showed significantly (p ≤ 0.05) reduced dribbling (3.09 ± 0.03 m·s vs. 2.81 ± 0.01 m·s) and total (2.22 ± 0.04 m·s vs. 2.09 ± 0.03 m·s) activity velocities during the third compared with the first quarter in professional players. Furthermore, effect size analyses showed greater decreases in high-intensity (professionald = 1.7–5.4; semiprofessionald = 0.3–1.7), shuffling (professionald = 2.3–3.2; semiprofessionald = 1.4–2.1), and total (professionald = 1.0–4.9; semiprofessionald = 0.3–0.8) activity and increases in dribbling (professionald = 1.4–4.7; semiprofessionald = 2.5–2.8) with game progression in professional players. In semiprofessional players, stoppage duration was significantly (p ≤ 0.05) related to various low-intensity (R = 0.64–0.72), high-intensity (R = 0.65–0.72), and total (R = 0.63–0.73) activity measures. Although not directly measured, the observed game activity fluctuations were likely because of a combination of physiological (e.g., muscle glycogen depletion, dehydration), tactical (e.g., ball control, game pace), and game-related (e.g., time-outs, player fouls) factors. Basketball coaches can use the provided data to (a) develop more precise training plans and management strategies, (b) elevate semiprofessional player performance closer to the professional level, and (c) incorporate tactical strategies to maximize the benefits of stoppages.
The tackle is responsible for the majority of head injuries during rugby union. In order to address head injury risk, risk factors during the tackle must first be identified. This study analysed ...tackle characteristics in the professional game in order to inform potential interventions.
464 tackles resulting in a head injury assessment (HIA) were analysed in detail, with tackle type, direction, speed, acceleration, nature of head contact and player body position the characteristics of interest.
Propensity to cause an HIA was significantly greater for active shoulder tackles, front-on tackles, high speeder tackles and an accelerating tackler. Head contact between a tackler's head and ball carrier's head or shoulder was significantly more likely to cause an HIA than contact below the level of the shoulder (incident rate ratio (IRR) 4.25, 95%-CI 3.38 to 5.35). The tackler experiences the majority (78%) of HIAs when head-to-head contact occurs. An upright tackler was 1.5 times more likely to experience an HIA than a bent at the waist tackler (IRR 1.44, 95% CI 1.18 to 1.76).
This study confirms that energy transfer in the tackle is a risk factor for head injury, since direction, type and speed all influence HIA propensity. The study provides evidence that body position and the height of tackles should be a focus for interventions, since lowering height and adopting a bent at the waist body position is associated with reduced risk for both tacklers and ball carriers. To this end, World Rugby has implemented law change based on the present data.
Phagocytosis is required for a broad range of physiological functions, from pathogen defense to tissue homeostasis, but the mechanisms required for phagocytosis of diverse substrates remain ...incompletely understood. Here, we developed a rapid magnet-based phenotypic screening strategy, and performed eight genome-wide CRISPR screens in human cells to identify genes regulating phagocytosis of distinct substrates. After validating select hits in focused miniscreens, orthogonal assays and primary human macrophages, we show that (1) the previously uncharacterized gene NHLRC2 is a central player in phagocytosis, regulating RhoA-Rac1 signaling cascades that control actin polymerization and filopodia formation, (2) very-long-chain fatty acids are essential for efficient phagocytosis of certain substrates and (3) the previously uncharacterized Alzheimer's disease-associated gene TM2D3 can preferentially influence uptake of amyloid-β aggregates. These findings illuminate new regulators and core principles of phagocytosis, and more generally establish an efficient method for unbiased identification of cellular uptake mechanisms across diverse physiological and pathological contexts.
Emerging observational evidence supports a role for higher fruit and vegetable intake in protecting against the development of depression. However, there is a scarcity of research in older adults or ...in low- to middle-income countries (LMICs).
Participants were 7801 community-based adults (mean age 68.6 ± 8.0 years, 55.8 % female) without depression, from 10 diverse cohorts, including four cohorts from LMICs. Fruit and vegetable intake was self-reported via comprehensive food frequency questionnaire, short food questionnaire or diet history. Depressive symptoms were assessed using validated measures, and depression defined applying validated cut-offs. The associations between baseline fruit and vegetable intakes and incident depression over a follow-up period of three to nine years were examined using Cox regression. Analyses were performed by cohort with results meta-analysed.
There were 1630 cases of incident depression (21 % of participants) over 40,258 person-years of follow-up. Higher intake of fruit was associated with a lower risk of incident depression (HR 0.87, 95%CI 0.77, 0.99, I2 = 4 %). No association was found between vegetable intake and incident depression (HR 0.93, 95%CI 0.84, 1.04, I2 = 0 %).
Diverse measures used across the different cohorts and the modest sample size of our study compared with prior studies may have prevented an association being detected for vegetable intake.
Our study supports a role for fruit, but not vegetable intake in protecting against depression. Research investigating different types of fruits and vegetables using standardised measures in larger cohorts of older adults from low- and middle-income countries is warranted.
•Higher fruit and vegetable intake may reduce the risk of depression.•There is a lack of research in low- and middle-income countries.•Results for 10 culturally diverse cohorts across six continents were meta-analysed.•Higher intakes of fruit were associated with a reduced risk of incident depression.•No association between vegetable intakes and the risk of incident depression.
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