Coordinated ARP2/3 and glycolytic activities regulate the morphological and functional fitness of human CD8+ T cells.

Actin cytoskeleton remodeling sustains the ability of cytotoxic T cells to search for target cells and eliminate them. We here investigated the relationship between energetic status, actin remodeling, and functional fitness in human CD8+ effector T cells. Cell spreading during migration or immunological synapse assembly mirrored cytotoxic activity. Morphological and functional fitness were boosted by interleukin-2 (IL-2), which also stimulated the transcription of glycolytic enzymes, actin isoforms, and actin-related protein (ARP)2/3 complex subunits. This molecular program scaled with F-actin content and cell spreading. Inhibiting glycolysis impaired F-actin remodeling at the lamellipodium, chemokine-driven motility, and adhesion, while mitochondrial oxidative phosphorylation blockade impacted cell elongation during confined migration. The severe morphological and functional defects of ARPC1B-deficient T cells were only partially corrected by IL-2, emphasizing ARP2/3-mediated actin polymerization as a crucial energy state integrator. The study therefore underscores the tight coordination between metabolic and actin remodeling programs to sustain the cytotoxic activity of CD8+ T cells.

Systemic Inflammation and Normocytic Anemia in DOCK11 Deficiency.

BACKGROUND: Increasing evidence links genetic defects affecting actin-regulatory proteins to diseases with severe autoimmunity and autoinflammation, yet the underlying molecular mechanisms are poorly understood. Dedicator of cytokinesis 11 (DOCK11) activates the small Rho guanosine triphosphatase (GTPase) cell division cycle 42 (CDC42), a central regulator of actin cytoskeleton dynamics. The role of DOCK11 in human immune-cell function and disease remains unknown. METHODS: We conducted genetic, immunologic, and molecular assays in four patients from four unrelated families who presented with infections, early-onset severe immune dysregulation, normocytic anemia of variable severity associated with anisopoikilocytosis, and developmental delay. Functional assays were performed in patient-derived cells, as well as in mouse and zebrafish models. RESULTS: We identified rare, X-linked germline mutations in DOCK11 in the patients, leading to a loss of protein expression in two patients and impaired CDC42 activation in all four patients. Patient-derived T cells did not form filopodia and showed abnormal migration. In addition, the patient-derived T cells, as well as the T cells from Dock11-knockout mice, showed overt activation and production of proinflammatory cytokines that were associated with an increased degree of nuclear translocation of nuclear factor of activated T cell 1 (NFATc1). Anemia and aberrant erythrocyte morphologic features were recapitulated in a newly generated dock11-knockout zebrafish model, and anemia was amenable to rescue on ectopic expression of constitutively active CDC42. CONCLUSIONS: Germline hemizygous loss-of-function mutations affecting the actin regulator DOCK11 were shown to cause a previously unknown inborn error of hematopoiesis and immunity characterized by severe immune dysregulation and systemic inflammation, recurrent infections, and anemia. (Funded by the European Research Council and others.).

First evidence of Proganochelys quenstedtii (Testudinata) from the Plateosaurus bonebeds (Norian, Late Triassic) of Frick, Canton Aargau, Switzerland.

Proganochelys quenstedtii represents the best-known stem turtle from the Late Triassic, with gross anatomical and internal descriptions of the shell, postcranial bones and skull based on several well-preserved specimens from Central European fossil locations. We here report on the first specimen of P. quenstedtii from the Late Triassic (Klettgau Formation) Frickberg near the town of Frick, Canton Aargau, Switzerland. Similar to other Late Triassic 'Plateosaurus-bearing bonebeds', Proganochelys is considered to be a rare faunal element in the Swiss locality of Frick as well. The specimen, which is largely complete but was found only partially articulated and mixed with large Plateosaurus bones, overall resembles the morphology of the classical specimens from Germany. Despite being disarticulated, most skull bones could be identified and micro-computed tomography (CT) scanning of the posterior skull region reveals new insights into the braincase and neurovascular anatomy, as well as the inner ear region. These include the presence of a fenestra perilymphatica, potentially elongated cochlear ducts, and intense vascularization of small tubercles on the posterior end of the skull roof, which we interpret as horn cores. Other aspects of the skull in the braincase region, such as the presence or absence of a supratemporal remain ambiguous due to the fusion of individual bones and thus lack of visible sutures (externally and internally). Based on the size of the shell and fusion of individual elements, the specimen is interpreted as a skeletally mature animal. Supplementary Information: The online version contains supplementary material available at 10.1186/s13358-022-00260-4.

Morphological profiling of human T and NK lymphocytes by high-content cell imaging.

The immunological synapse is a complex structure that decodes stimulatory signals into adapted lymphocyte responses. It is a unique window to monitor lymphocyte activity because of development of systematic quantitative approaches. Here we demonstrate the applicability of high-content imaging to human T and natural killer (NK) cells and develop a pipeline for unbiased analysis of high-definition morphological profiles. Our approach reveals how distinct facets of actin cytoskeleton remodeling shape immunological synapse architecture and affect lytic granule positioning. Morphological profiling of CD8+ T cells from immunodeficient individuals allows discrimination of the roles of the ARP2/3 subunit ARPC1B and the ARP2/3 activator Wiskott-Aldrich syndrome protein (WASP) in immunological synapse assembly. Single-cell analysis further identifies uncoupling of lytic granules and F-actin radial distribution in ARPC1B-deficient lymphocytes. Our study provides a foundation for development of morphological profiling as a scalable approach to monitor primary lymphocyte responsiveness and to identify complex aspects of lymphocyte micro-architecture.

Molluscan benthic communities at Brijuni Islands (northern Adriatic Sea) shaped by Holocene sea-level rise and recent human eutrophication and pollution.

The effects of and the interplay between natural and anthropogenic influences on the composition of benthic communities over long time spans are poorly understood. Based on a 160-cm-long sediment core collected at 44 m water depth in the NE Adriatic Sea (Brijuni Islands, Croatia), we document changes in molluscan communities since the Holocene transgression ~11,000 years ago and assess how they were shaped by environmental changes. We find that (1) a transgressive lag deposit with a mixture of terrestrial and marine species contains abundant seagrass-associated gastropods and epifaunal suspension-feeding bivalves, (2) the maximum-flooding phase captures the establishment of epifaunal bivalve-dominated biostromes in the photic zone, and (3) the highstand phase is characterized by increasing infaunal suspension feeders and declining seagrass-dwellers in bryozoan-molluscan muddy sands. Changes in the community composition between the transgressive and the highstand phase can be explained by rising sea level, reduced light penetration, and increase in turbidity, as documented by the gradual up-core shift from coarse molluscan skeletal gravel with seagrass-associated molluscs to bryozoan sandy muds. In the uppermost 20 cm (median age <200 years), however, epifaunal and grazing species decline and deposit-feeding and chemosymbiotic species increase in abundance. These changes concur with rising concentrations of nitrogen and organic pollutants due to the impact of eutrophication, pollution, and trawling in the 20th century. The late highstand benthic assemblages with abundant bryozoans, high molluscan diversity, and abundance of soft-bottom epi- and infaunal filter feeders and herbivores represent the circalittoral baseline community largely unaffected by anthropogenic impacts.

Holocene ecosystem shifts and human-induced loss of Arca and Ostrea shell beds in the north-eastern Adriatic Sea.

The molluscan assemblages in a sediment core from the north-eastern Adriatic show significant compositional changes over the past 10,000yrs related to (1) natural deepening driven by the post-glacial sea-level rise, (2) increasing abundance of skeletal sand and gravel, and (3) anthropogenic impacts. The transgressive phase (10,000-6000 BP) is characterized by strongly time-averaged communities dominated by infaunal bivalves. During the early highstand (6000-4000 BP), the abundance of epifaunal filter feeders and grazers increases, and gastropods become more important. Epifaunal dominance culminates during the late highstand (4000-2000 BP) with the development of extensive shell beds formed by large-sized Arca noae and Ostrea sp. bivalves. This community persists until the early 20th century, when it falls victim to multiple anthropogenic impacts, mainly bottom trawling, and is substituted by an infauna-dominated community indicative of instability, disturbance and organic enrichment. The re-establishment of this unique shell-bed ecosystem can be a goal for restoration efforts.

An updated description of the osteology of the pancake tortoise Malacochersus tornieri (Testudines: Testudinidae) with special focus on intraspecific variation.

Exceptional variability in the shell of the pancake tortoise Malacochersus tornieri, both in the keratinous surficial scutes and the underlying bones, in addition to its remarkably fenestrated bony shell are unique among tortoises. Based on 14 individuals of different sizes and ages, the observed variation in M. tornieri was described in detail, with additional notes on the typically testudinid skull, inner ear and brain endocast using microCT-scan data, as well as the limbs. Similar degrees of variation have not yet been described in any other extant turtle species and therefore seem notable in M. tornieri, and might be related to the species' unique lifestyle. Within the carapace, the peripherals and suprapygals are most variable in number. Furthermore, different combinations of peripherals are participating in the central plastral fontanelle and in some individuals additional bones take part in the formation of the plastron. J. Morphol. 278:321-333, 2017. © 2017 Wiley Periodicals, Inc.