Rapid,gregarious settlement of the larvae of the marine echiuran Urechis caupo Fisher & MacGinitie 1928

Larvae of Urechis caupo Fisher & MacGinitie, reared in the laboratory, were exposed to potential settlement stimuli, including natural sediment from adult burrows, and “scent” obtained from the skin of adult animals. Competent larvae settled rapidly and specifically in response to adult burrow sediment when compared with their responses to other natural and abiotic sediments. Larvae also responded specifically to chemical “scent” from adult animals when the “scent” of another echiuran worm, Listriolobus pelodes Fisher served as a control. Larval responses to chemical “scent” were as great as their responses to natural burrow sediment. Hence, it is likely that larvae settle gregariously in nature in response to “scent” on sediment grains of adult burrows. The chemical “scent” had a molecular weight between ≈3500 and 14000 daltons, as determined by dialysis. It quickly lost its effectiveness in promoting settlement after it was heated to 80 °C, but was relatively stable at ambient ocean temperatures, retaining its effectiveness for several days. It was soluble in sea water. However, larvae did not respond to the chemical “scent”, unless it was adsorbed onto a surface. Purely tactile stimuli, such as the shape, texture, and size-distribution of particles, were not important settlement cues during these experiments.     

CX3CR1 Is Expressed by Human B Lymphocytes and Meditates CX3CL1 Driven Chemotaxis of Tonsil Centrocytes

Background

Fractalkine/CX₃CL1, a surface chemokine, binds to CX₃CR1 expressed by different lymphocyte subsets. Since CX₃CL1 has been detected in the germinal centres of secondary lymphoid tissue, in this study we have investigated CX₃CR1 expression and function in human naïve, germinal centre and memory B cells isolated from tonsil or peripheral blood.

Methodology/Principal Findings

We demonstrate unambiguously that highly purified human B cells from tonsil and peripheral blood expressed CX₃CR1 at mRNA and protein levels as assessed by quantitative PCR, flow cytometry and competition binding assays. In particular, naïve, germinal centre and memory B cells expressed CX₃CR1 but only germinal centre B cells were attracted by soluble CX₃CL1 in a transwell assay. CX₃CL1 signalling in germinal centre B cells involved PI3K, Erk1/2, p38, and Src phosphorylation, as assessed by Western blot experiments. CX₃CR1⁺ germinal centre B cells were devoid of centroblasts and enriched for centrocytes that migrated to soluble CX₃CL1. ELISA assay showed that soluble CX₃CL1 was secreted constitutively by follicular dendritic cells and T follicular helper cells, two cell populations homing in the germinal centre light zone as centrocytes. At variance with that observed in humans, soluble CX₃CL1 did not attract spleen B cells from wild type mice. OVA immunized CX₃CR1⁻/⁻ or CX₃CL1⁻/⁻ mice showed significantly decreased specific IgG production compared to wild type mice.

Conclusion/Significance

We propose a model whereby human follicular dendritic cells and T follicular helper cells release in the light zone of germinal centre soluble CX₃CL1 that attracts centrocytes. The functional implications of these results warrant further investigation.     

Regional and local determinants of drought resilience in tropical forests

The increase in severity of droughts associated with greater mortality and reduced vegetation growth is one of the main threats to tropical forests. Drought resilience of tropical forests is affected by multiple biotic and abiotic factors varying at different scales. Identifying those factors can help understanding the resilience to ongoing and future climate change. Altitude leads to high climate variation and to different forest formations, principally moist or dry tropical forests with contrasted vegetation structure. Each tropical forest can show distinct responses to droughts. Locally, topography is also a key factor controlling biotic and abiotic factors related to drought resilience in each forest type. Here, we show that topography has key roles controlling biotic and abiotic factors in each forest type. The most important abiotic factors are soil nutrients, water availability, and microclimate. The most important biotic factors are leaf economic and hydraulic plant traits, and vegetation structure. Both dry tropical forests and ridges (steeper and drier habitats) are more sensitive to droughts than moist tropical forest and valleys (flatter and wetter habitats). The higher mortality in ridges suggests that conservative traits are not sufficient to protect plants from drought in drier steeper habitats. Our synthesis highlights that altitude and topography gradients are essential to understand mechanisms of tropical forest''s resilience to future drought events. We described important factors related to drought resilience, however, many important knowledge gaps remain. Filling those gaps will help improve future practices and studies about mitigation capacity, conservation, and restoration of tropical ecosystems.     

Time of Progression to Osteopenia/Osteoporosis in Chronically HIV-Infected Patients: Screening DXA Scan

Background

Algorithms for bone mineral density (BMD) management in HIV-infected patients are lacking. Our objective was to assess how often a dual-energy x-ray absorptiometry (DXA) scan should be performed by assessing time of progression to osteopenia/osteoporosis.

Methods

All DXA scans performed between 2000 and 2009 from HIV-infected patients with at least two DXA were included. Time to an event (osteopenia and osteoporosis) was assessed using the Kaplan–Meier method. Strata (tertiles) were defined using baseline minimum T scores. Differences between strata in time to an event were compared with the log-rank test.

Results

Of 391 patients (1,639 DXAs), 49.6% had osteopenia and 21.7% osteoporosis at their first DXA scan. Of the 112 (28.6%) with normal BMD, 35.7% progressed to osteopenia; median progression time was 6.7 years. These patients were stratified: “low-risk" (baseline minimum T score >−0.2 SD), “middle-risk" (between −0.2 and −0.6 SD), and “high-risk" (from −0.6 to −1 SD); median progression time to osteopenia was 8.7, >7.2, and 1.7 years, respectively (p<0.0001). Of patients with osteopenia, 23.7% progressed to osteoporosis; median progression time was >8.5 years. Progression time was >8.2 years in “low-risk" tertile (T score between −1.1 and −1.6 SD), >8.5 years in “middle-risk" (between −1.6 and −2), and 3.2 years in “high-risk" (from −2 to −2.4) (p<0.0001).

Conclusions

Our results may help to define the BMD testing interval. The lowest T score tertiles would suggest recommending a subsequent DXA in 1–2 years; in the highest tertiles, ≥6 years. Early intervention in patients with bone demineralization could reduce fracture–related morbidity/mortality.     

Circulating miRNA‐375 as a potential novel biomarker for active Kaposi’s sarcoma in AIDS patients

The aim of this study was to identify circulating microRNAs (miRNAs) that could be used as biomarkers in patients at risk for or affected by AIDS‐Kaposi's sarcoma (KS). Screening of 377 miRNAs was performed using low‐density arrays in pooled plasma samples of 10 HIV/human herpesvirus 8 (HHV8)‐infected asymptomatic and 10 AIDS‐KS patients before and after successful combined antiretroviral therapy (cART). MiR‐375 was identified as a potential marker of active KS, being the most down‐regulated in AIDS‐KS patients after cART and the most up‐regulated in naïve AIDS‐KS patients compared to naïve asymptomatic subjects. Validation on individual plasma samples confirmed that miR‐375 levels were higher in AIDS‐KS compared to asymptomatic patients, decreased after cART‐induced remission in most AIDS‐KS patients and increased in patients with active KS. In asymptomatic patients miR‐375 was up‐regulated after cART in both screening and validation. Statistical analyses revealed an association between miR‐375 changes and CD4 cell counts, which could explain the discordant cases and the opposite trend between asymptomatic and AIDS‐KS patients. These data suggest that circulating miR‐375 might be a good indicator of active AIDS‐KS. Moreover, changes in miR‐375 levels may have a prognostic value in HIV/HHV8‐infected patients undergoing treatment. Further large‐scale validation is needed.     

Behavioural responses in three ichneumonid pollen beetle parasitoids to volatiles emitted from different phenological stages of oilseed rape

Pollen beetles (Meligethes spp.; Coleoptera: Nitiduliae) are a major pest of oilseed rape, Brassica napus L. (Brassicaceae) in northern Europe. Phradis interstitialis Thomson, P. morionellus Holmgr., and Tersilochus heterocerus Thomson (Hymenoptera: Ichneumonidae) are among the most frequent pollen beetle parasitoids. These three species differ in temporal occurrence, as well as in preferred host stage. The behavioural responses of female parasitoids to odours from oilseed rape at bud and flowering stage were evaluated in two‐choice experiments. The role of visual stimuli was examined by combining green and yellow colours with odour stimuli. All three species were attracted to odours from the bud stage of oilseed rape. Tersilochus heterocerus was attracted to odours of flowering rape, but the two Phradis species avoided the flower odours. However, when the odours of flowering rape were combined with yellow, and odours of the bud stage were combined with green, P. interstitialis was equally attracted to both stimuli, and T. heterocerus showed an increased preference for flower odours, while no effect of colours could be found in P. morionellus. The observed differences in responses between the parasitoids may reflect differences in their biology and may be involved in the niche segregation of these often coexisting species. The volatile blends released from the two phenological stages were identified and compared. Clearly, odours can be reliable cues for differentiating between oilseed rape in the bud and flowering stage. Of 20 identified compounds, 18 were released at a significantly higher rate from flowering plants. The terpenes sabinene, myrcene, limonene, and (E,E)‐α‐farnesene were the dominant volatiles in the bud and flower headspace. A group of aromatic compounds including benzaldehyde, methyl benzoate, and phenyl acetaldehyde were mainly released from flowering rape.     

T Cell Activation and Cytokine Profile of Tuberculosis and HIV-Positive Individuals during Antituberculous Treatment and Efavirenz-Based Regimens

Introduction

The profile of immune activation markers in tuberculosis and HIV-infected patients is already known. The impact of simultaneous infections on the immune parameters is still not fully explored.

Methods

We conducted a prospective study to estimate trajectories of activated T cell subsets and the profile of anti- and pro-inflammatory cytokines in a group of HIV-TB individuals, previously naïve for HAART, recruited from a randomized clinical trial during TB treatment and first antiretroviral therapy with efavirenz. Patients were evaluated according to the immunosuppression levels at baseline as group 1 (CD4<200 cells/mm³) and group 2 (CD4>200 cells/mm³). These parameters were measured at the time of HAART initiation (started about 30 days after the onset of TB treatment) and at the follow-up visits after 30, 60, 90 and 180 days. Trajectories were estimated using least squares estimates of the coefficients of a restricted cubic spline function in time after adjusting for subject effects, bootstrapping it 500 times.

Results

Increase of CD4 T cell counts and suppression of HIV viral load were observed for all patients under HAART and TB treatment. Descendent trajectories were observed for the activated CD8⁺/CD38⁺ and CD3⁺/HLA-DR⁺ T cell subsets, and for plasma concentration of gamma- interferon (IFN-γ). Except for TNF-α and IL-2 discrete variations were observed for the other cytokines. Differences in the trajectories of these parameters were observed for groups 1 and 2. Higher values of IFN-γ, IL-2, IL-6 and IL-10 were observed for group 1 from the baseline to two months after treatment initiation, whereas reduced levels of TNF-α were observed for this group between 60 and 120 days of HAART.

Conclusion

Independent of the immunosuppression profile at baseline, HIV-TB patients under HAART were able to recover the CD4⁺ T cell counts, and control viral replication and immune activation parameters over time.     

Regulation to Create Environments Conducive to Physical Activity: Understanding the Barriers and Facilitators at the Australian State Government Level

Introduction

Policy and regulatory interventions aimed at creating environments more conducive to physical activity (PA) are an important component of strategies to improve population levels of PA. However, many potentially effective policies are not being broadly implemented. This study sought to identify potential policy/regulatory interventions targeting PA environments, and barriers/facilitators to their implementation at the Australian state/territory government level.

Methods

In-depth interviews were conducted with senior representatives from state/territory governments, statutory authorities and non-government organisations (n = 40) to examine participants'': 1) suggestions for regulatory interventions to create environments more conducive to PA; 2) support for preselected regulatory interventions derived from a literature review. Thematic and constant comparative analyses were conducted.

Results

Policy interventions most commonly suggested by participants fell into two areas: 1) urban planning and provision of infrastructure to promote active travel; 2) discouraging the use of private motorised vehicles. Of the eleven preselected interventions presented to participants, interventions relating to walkability/cycling and PA facilities received greatest support. Interventions involving subsidisation (of public transport, PA-equipment) and the provision of more public transport infrastructure received least support. These were perceived as not economically viable or unlikely to increase PA levels. Dominant barriers were: the powerful ‘road lobby’, weaknesses in the planning system and the cost of potential interventions. Facilitators were: the provision of evidence, collaboration across sectors, and synergies with climate change/environment agendas.

Conclusion

This study points to how difficult it will be to achieve policy change when there is a powerful ‘road lobby’ and government investment prioritises road infrastructure over PA-promoting infrastructure. It highlights the pivotal role of the planning and transport sectors in implementing PA-promoting policy, however suggests the need for clearer guidelines and responsibilities for state and local government levels in these areas. Health outcomes need to be given more direct consideration and greater priority within non-health sectors.