Spatio-temporal dynamics of multi-trophic communities reveal ecosystem-wide functional reorganization

Large-scale alterations in marine ecosystems as a response to environmental and anthropogenic pressures have been documented worldwide. Yet, these are primarily investigated by assessing abundance fluctuations of a few dominant species, which inadequately reflect ecosystem-wide changes. In addition, it is increasingly recognized that it is not species identity per se, but their traits that determine environmental responses, biological interactions and ecosystem functioning. In this study, we investigated long-term, spatio-temporal variability in trait composition across multiple organism groups to assess whether functional changes occur in a similar way across trophic levels and whether shifts in trait composition link to environmental change. We combined extensive trait datasets with long-term surveys (30–40 yr) of four organism groups (phytoplankton, zooplankton, benthic invertebrates and fish) in three environmentally distinct areas of a large marine ecosystem. We found similar temporal trajectories in the community weighted mean trait time-series of the different trophic groups, revealing ecosystem-wide functional changes. The traits involved and their dynamics differed between areas, concurrent with climate-driven changes in temperature and salinity, as well as more local dynamics in nutrients and oxygen. This finding highlights the importance of considering both global climate, as well as local external drivers when studying ecosystem changes. Using a multi-trophic trait-based approach, our study demonstrates the importance of integrating community functional dynamics across multiple trophic levels to capture ecosystem-wide responses which could, ultimately, help moving towards a holistic understanding, assessment and management of marine ecosystems.     

Early TCR alpha beta expression promotes maturation of T cells expressing Fc epsilon RI gamma containing TCR/CD3 complexes

In a previous study we presented data indicating that the expanded population of CD4(-)CD8(-) (DN) alphabeta T cells in TCRalpha-chain-transgenic mice was partially if not entirely derived from gammadelta T cell lineage cells. The development of both gammadelta T cells and DN alphabeta T cells is poorly understood; therefore, we thought it would be important to identify the immediate precursors of the transgene-induced DN alphabeta T cells. We have in this report studied the early T cell development in these mice and we show that the transgenic TCRalpha-chain is expressed by precursor thymocytes already at the CD3(-)CD4(-)CD8(-) (triple negative, TN) CD44(+)CD25(-) stage of development. Both by using purified precursor populations in reconstitution experiments and by analyzing fetal thymocyte development, we demonstrated that early TN precursors expressing endogenous TCRbeta-chains matured into DN alphabeta T cells at several stages of development. The genes encoding the gamma-chain of the high affinity receptor for IgE (FcepsilonRIgamma) and the CD3zeta protein were found to be reciprocally expressed in TN thymocytes such that during development the FcepsilonRIgamma expression decreased whereas CD3zeta expression increased. Furthermore, in a fraction of the transgene-induced DN alphabeta T cells the FcepsilonRIgamma protein colocalized with the TCR/CD3 complex. These data suggest that similarly to gammadelta T cells and NKT cells, precursors expressing the TCR early in the common alphabetagammadelta developmental pathway may use the FcepsilonRIgamma protein as a signaling component of the TCR/CD3 complex.     

Development of Salivary Cortisol Circadian Rhythm and Reference Intervals in Full-Term Infants

BackgroundCortisol concentrations in plasma display a circadian rhythm in adults and children older than one year. Earlier studies report divergent results regarding when cortisol circadian rhythm is established. The present study aims to investigate at what age infants develop a circadian rhythm, as well as the possible influences of behavioral regularity and daily life trauma on when the rhythm is established. Furthermore, we determine age-related reference intervals for cortisol concentrations in saliva during the first year of life.Methods130 healthy full-term infants were included in a prospective, longitudinal study with saliva sampling on two consecutive days, in the morning (07:30-09:30), noon (10:00-12:00) and evening (19:30-21:30), each month from birth until the infant was twelve months old. Information about development of behavioral regularity and potential exposure to trauma was obtained from the parents through the Baby Behavior Questionnaire and the Life Incidence of Traumatic Events checklist.ResultsA significant group-level circadian rhythm of salivary cortisol secretion was established at one month, and remained throughout the first year of life, although there was considerable individual variability. No correlation was found between development of cortisol circadian rhythm and the results from either the Baby Behavior Questionnaire or the Life Incidence of Traumatic Events checklist. The study presents salivary cortisol reference intervals for infants during the first twelve months of life.ConclusionsCortisol circadian rhythm in infants is already established by one month of age, earlier than previous studies have shown. The current study also provides first year age-related reference intervals for salivary cortisol levels in healthy, full-term infants.     

Protein synthesis of the pro-inflammatory S100A8/A9 complex in plasmacytoid dendritic cells and cell surface S100A8/A9 on leukocyte subpopulations in systemic lupus erythematosus

Introduction  

Systemic lupus erythematosus (SLE) is an autoimmune disease with chronic or episodic inflammation in many different organ systems, activation of leukocytes and production of pro-inflammatory cytokines. The heterodimer of the cytosolic calcium-binding proteins S100A8 and S100A9 (S100A8/A9) is secreted by activated polymorphonuclear neutrophils (PMNs) and monocytes and serves as a serum marker for several inflammatory diseases. Furthermore, S100A8 and S100A9 have many pro-inflammatory properties such as binding to Toll-like receptor 4 (TLR4). In this study we investigated if aberrant cell surface S100A8/A9 could be seen in SLE and if plasmacytoid dendritic cells (pDCs) could synthesize S100A8/A9.     

Regulation of T cell growth factor production: arrest of TCGF production after 18 hours in normal lectin-stimulated mouse spleen cell cultures

The detailed kinetics of TCGF accumulation in Con A-stimulated spleen cell cultures shows a maximum at 24 hr, with a subsequent decrease in activity. This decrease is not due to the appearance of inhibitory substances "masking" TCGF activity. Pulse experiments show that the rate of TCGF production falls sharply after 18 hr and is completely arrested after 24 hr of Con A stimulation. The arrest in TCGF production is the result neither of culture depletion in medium components nor of limiting accessory cell function or inactivation of the lectin, and it thus seem to be the result of inactivation of TCGF-producing T cells. This regulation is not the result of a TCGF-mediated feedback mechanism but rather of lectin-induced suppressive cells that appear in culture after 24 hr and turn off de novo production of TCGF in fresh cultures.     

Nano-cluster composite structure of calcitic sponge spicules--a case study of basic characteristics of biominerals

Spicules of calcareous sponges are elaborately shaped skeletal elements that nonetheless show characteristics of calcite single-crystals. Our atomic force microscopic and transmission electron microscopic investigation of the triradiate spicules of the sponge Pericharax heteroraphis reveals a nano-cluster structure with mostly well-aligned small crystal domains and pockets with accumulated domain misalignments. Combined high-resolution and energy-filtering transmission electron microscopy revealed carbon enrichments located in between crystal domain boundaries, which strongly suggests an intercalated network-like proteinaceous organic matrix. This matrix is proposed to be involved in the nano-clustered calcite precipitation via a transient phase that may enable a 'brick-by-brick' formation of composite and yet single-crystalline spicules with elaborate morphologies. This composite cluster structure reduces the brittleness of the material by dissipating strain energy and deflecting crack propagation from the calcite cleavage planes, but the lattice symmetry and anisotropic growth properties of calcite still play a major role in the morphogenesis of these unusual calcite single-crystals. Our structural, crystallographic, textural, and chemical analysis of sponge spicules corroborates the view that nano-clustered crystal growth, induced by organic matrices, is a basic characteristic of biomineralisation that enables the production of composite materials with elaborate morphologies.     

C-Med 100®, a hot water extract of Uncaria tomentosa, prolongs lymphocyte survival in vivo

Water extracts of the bark of Uncaria tomentosa, a vine indigenous to South America, has been used for generations as an "immuno modulator". To understand the basis of this immuno modulatory effect we fed mice in their drinking water with C-Med 100, which is a commercially available water extract from Uncaria tomentosa. We found a dose-dependent increase in spleen cell numbers in the supplemented mice, but the proportions of B cells, T cells, NK cells, granulocytes, and memory lymphocytes were normal. However, there were no detectable changes of the lymphoid architecture of the spleen even after long-term treatment. Further, when C-Med 100 treatment was interrupted the cellularity returned to normal level within four weeks. The increased number of lymphocytes was most likely not due to increased production because C-Med 100 did not have any significant effect on precursor cells nor on the accumulation of recent thymic emigrants in the spleen. We conclude that accumulation is most likely due to prolonged cell survival, because adoptive transfer experiments demonstrated that C-Med 100 treatment significantly prolonged lymphocyte survival in peripheral lymphoid organs, without increasing their proliferation rate. Since the accumulation was reversible and without detectable pathological effects, these results suggest the use of C-Med 100 as a potential agent for clinically accelerating the recovery of patients from leukopenia.     

Signal transduction through the T cell receptor-CD3 complex. Evidence for heterogeneity in receptor coupling

T cell receptor-CD3 complex (TCR-CD3)-mediated signal transduction was analyzed in HPB-ALL and Jurkat T cell lines. Both cell lines express high levels of TCR-CD3 complex on the cell surface, but provide different model systems for TCR-CD3 signaling in T cells. Jurkat responds with both inositol phosphate generation and intracellular Ca2+ mobilization after triggering of TCR-CD3, whereas TCR-CD3 triggering of HPB-ALL induces Ca2+ mobilization without detectable inositol phosphate generation. By employing a permeabilized cell system, we show that the HPB-ALL line expressed normal levels of Ca2(+)-induced phospholipase C activity. However, the TCR-CD3 on this cell line seems to be uncoupled from phospholipase C activation. In agreement with this result we also show, by analysis of protein kinase C-dependent phosphorylation of three distinct substrates, that TCR-CD3 in HPB-ALL is apparently uncoupled from protein kinase C activation. These findings may have implications for understanding signal-transducing pathways in T cells at various stages of differentiation.     

Shock,Stress or Signal? Implications of Freshwater Flows for a Top-Level Estuarine Predator

Physicochemical variability in estuarine systems plays an important role in estuarine processes and in the lifecycles of estuarine organisms. In particular, seasonality of freshwater inflow to estuaries may be important in various aspects of fish lifecycles. This study aimed to further understand these relationships by studying the movements of a top-level estuarine predator in response to physicochemical variability in a large, temperate south-east Australian estuary (Shoalhaven River). Mulloway (Argyrosomus japonicus, 47–89 cm total length) were surgically implanted with acoustic transmitters, and their movements and migrations monitored over two years via fixed-position VR2W acoustic receivers configured in a linear array along the length of the estuary. The study period included a high degree of abiotic variability, with multiple pulses (exponentially high flows over a short period of time) in fresh water to the estuary, as well as broader seasonal variation in flow, temperature and conductivity. The relative deviation of fish from their modal location in the estuary was affected primarily by changes in conductivity, and smaller fish (n = 4) tended to deviate much further downstream from their modal position in the estuary than larger fish (n = 8). High-flow events which coincided with warmer temperatures tended to drive mature fish down the estuary and potentially provided a spawning signal to stimulate aggregation of adults near the estuary mouth; however, this relationship requires further investigation. These findings indicate that pulse and press effects of freshwater inflow and associated physicochemical variability play a role in the movements of mulloway, and that seasonality of large freshwater flows may be important in spawning. The possible implications of river regulation and the extraction of freshwater for consumptive uses on estuarine fishes are discussed.