Ecological Aspects Of Iron Acquisition In Synechococcus Sp (cyanophyceae)

As primary producers, marine cyanobacteria regulate the biological and biogeochemical cycles of aquatic ecosystems and influence ocean-atmosphere gas exchange. The purposes of this project were to determine if a Synechococcus sp. was capable of utilizing a high-affinity iron transport system during periods of iron-limited growth and if physiological changes due to iron limitation could be identified. Resolution of these factors was achieved by maintaining the cyanobacterium Synechococcus sp. PCC 7002 in continuous culture chemostats over a range of iron availabilities.;Changes in physiology were detected over a range of iron concentrations. Reductions in the levels of photosynthetic pigments were accompanied by a deterioration of thylakoid integrity and changes in cellular carboxysome and polyphosphate bodies. Polypeptide profiles of thylakoid, cytoplasmic, and outer membrane fractions demonstrated the enhanced production of specific proteins during iron-limited growth. The photosynthetic efficacy (measured as oxygen evolution and carbon fixation) is significantly reduced during iron-limitation, with carbon incorporation being reduced from luxury levels to the minimum requirements for cellular carbon turnover.;Steady state cell densities within chemostats, combined with growth data obtained from batch cultures, demonstrate a non-linear response between iron concentration and cyanobacterial proliferation. Results suggest that this is brought about by changes in the cellular iron quotient, coupled with the activation of an energy dependant high-affinity iron transport system. The activation of this system involves the release of four novel iron-regulated, iron-binding cell products (siderophores) by Synechococcus sp. PCC 7002.;To determine the prevalence of siderophore production, ten species of cyanobacteria were examined for the ability to produce siderophores under iron-limiting conditions. In all cases these cyanobacteria were found to produce siderophores, and, in many species, the production of multiple siderophores was detected. Analysis of the chemical moieties associated with these compounds demonstrated that hydroxamate-type, catechol-type, and atypical-type iron chelators are produced by these cyanobacteria.;The presence of siderophores enhances the ability of cyanobacteria, grown under iron-limiting conditions, to assimilate iron from the environment via membrane-associated receptor proteins. Ferrisiderophore receptors are not expressed by cyanobacteria grown under iron-replete conditions.;An amalgamation of these results infers that some cyanobacteria utilize high-affinity iron transport systems, involving the serial transport of iron via soluble and membrane-associated ferrisiderophore complexes, in a process which requires the presence of membrane-specific receptors and ATP. This work demonstrates that the definition of affinity in iron transport must consider the biologically available and unavailable pools of iron in the environment. This work suggests that high-affinity iron transport in cyanobacteria involves the conversion of biologically unavailable iron to an available form

Editorial Remarks: Youth at Risk

Youth must always be analysed with respect to two aspects: Firstly, as a societally shaped phase of life that varies socially and culturally across countries and regions, characterized by different chances of social integration and dangers of disintegration. Secondly, as individual biographies playing out in a specific societal dynamic of integration/disintegration, where experiences with violence as perpetrators or victims play an important role. Life in particular societal constellations presents risks for certain parts of the young generation, just as the behavior of youth may itself pose risks in some societal situations. The way the general relationship varies across different national and cultural contexts is the question we have chosen to home in on in this issue of the journal. Post-war, post-dictatorial, developing, transformative, and precarious societal contexts form consistent points of reference for the contributions, which include both country-specific case studies and comparative investigations

Evolution and Denial: State Sentencing after Blakely and Booker

Justice Louis Brandeis famously described the states as laboratories where individual jurisdictions can experiment with various legal strategies. In the wake of Blakley v. Washington, and United States v. Booker those laboratories have been working overtime. Since June 2004, both state legislatures and state courts have grappled with the significance of the United States Supreme Court\u27s treatment of the Sixth Amendment in sentencing. It is unsurprising, given the extraordinary significance and potential reach of Blakely and Booker, that this Herculean task has produced divergent results. Although there are many potential ways to sort those results, for the purposes of these observations, we have divided them into states of “evolution” and states of “denial.” Evolution states have read Blakely and Booker fairly, accepted that Blakely controls what is permissible within their sentencing regimes, and responded in ways that best fit their circumstances. Still, there are differences in how these jurisdictions have evolved. Many of the states responding to Blakely (particularly those with active sentencing commissions) have retained their more presumptive sentencing systems. Others have followed Booker toward a more advisory system of guiding judicial discretion at sentencing. In contrast, denial states, acting through their state supreme courts, have found ways to repudiate that Blakely even applies to their systems, despite compelling evidence to the contrary. California is probably the most notable of the denial states and, consistent with our views but after these observations went to press, it attracted the Supreme Court’s attention in Cunningham v. California. We conclude with a look toward the future and a plea for states to strengthen their sentencing commissions

Determining rates of virus production in aquatic systems by the virus reduction approach,

The reduction approach to assess virus production and the prokaryotic mortality by viral lysis stops new infection by reducing total virus abundance (and thus virus–host contacts). This allows for easy enumeration of viruses that originate from lysis of already infected cells due to the decreased abundance of free virus particles. This reoccurrence can be quantified and used to assess production and cell lysis rates. Several modifications of the method are presented and compared. The approaches have great potential for elucidating trends in virus production rates as well as for making generalized estimates of the quantitative effects of viruses on marine microbial communities

The construction and analysis of marker gene libraries

Marker genes for viruses are typically amplified from aquatic samples to determine whether specific viruses are present in the sample, or to examine the diversity of a group of related viruses. In this chapter, we will provide an overview of common methods used to amplify, clone, sequence, and analyze virus marker genes, and will focus our discussion on viruses infecting algae, bacteria, and heterotrophic flagellates. Within this chapter, we endeavor to highlight critical aspects and components of these methods. To this end, instead of providing a detailed experimental protocol for each of the steps involved in examining virus marker gene libraries, we have provided a few key considerations, recommendations, and options for each step. We conclude this chapter with a brief discussion of research on a major capsid protein (g20) of cyanomyoviruses using this work as a case study for polymerase chain reaction primer design and development. By building on the experience of numerous labs, this chapter should not only be useful to the new virus ecologist, but also serve as a valuable resource to established research groups

Evolution and Denial: State Sentencing after Blakely and Booker

Justice Louis Brandeis famously described the states as laboratories where individual jurisdictions can experiment with various legal strategies. In the wake of Blakley v. Washington, and United States v. Booker those laboratories have been working overtime. Since June 2004, both state legislatures and state courts have grappled with the significance of the United States Supreme Court\u27s treatment of the Sixth Amendment in sentencing. It is unsurprising, given the extraordinary significance and potential reach of Blakely and Booker, that this Herculean task has produced divergent results. Although there are many potential ways to sort those results, for the purposes of these observations, we have divided them into states of “evolution” and states of “denial.” Evolution states have read Blakely and Booker fairly, accepted that Blakely controls what is permissible within their sentencing regimes, and responded in ways that best fit their circumstances. Still, there are differences in how these jurisdictions have evolved. Many of the states responding to Blakely (particularly those with active sentencing commissions) have retained their more presumptive sentencing systems. Others have followed Booker toward a more advisory system of guiding judicial discretion at sentencing. In contrast, denial states, acting through their state supreme courts, have found ways to repudiate that Blakely even applies to their systems, despite compelling evidence to the contrary. California is probably the most notable of the denial states and, consistent with our views but after these observations went to press, it attracted the Supreme Court’s attention in Cunningham v. California. We conclude with a look toward the future and a plea for states to strengthen their sentencing commissions

Whole-body heat stress and exercise stimulate the appearance of platelet microvesicles in plasma with limited influence of vascular shear stress

Intense, large muscle mass exercise increases circulating microvesicles, but our understanding of microvesicle dynamics and mechanisms inducing their release remains limited. However, increased vascular shear stress is generally thought to be involved. Here, we manipulated exercise-independent and exercise-dependent shear stress using systemic heat stress with localized single-leg cooling (low shear) followed by single-leg knee extensor exercise with the cooled or heated leg (Study 1, n = 8) and whole-body passive heat stress followed by cycling (Study 2, n = 8). We quantified femoral artery shear rates (SRs) and arterial and venous platelet microvesicles (PMV-CD41+) and endothelial microvesicles (EMV-CD62E+). In Study 1, mild passive heat stress while one leg remained cooled did not affect [microvesicle] (P ≥ 0.05). Single-leg knee extensor exercise increased active leg SRs by ~12-fold and increased arterial and venous [PMVs] by two- to threefold, even in the nonexercising contralateral leg (P < 0.05). In Study 2, moderate whole-body passive heat stress increased arterial [PMV] compared with baseline (mean±SE, from 19.9 ± 1.5 to 35.5 ± 5.4 PMV.μL-1.103, P < 0.05), and cycling with heat stress increased [PMV] further in the venous circulation (from 27.5 ± 2.2 at baseline to 57.5 ± 7.2 PMV.μL-1.103 during cycling with heat stress, P < 0.05), with a tendency for increased appearance of PMV across exercising limbs. Taken together, these findings demonstrate that whole-body heat stress may increase arterial [PMV], and intense exercise engaging either large or small muscle mass promote PMV formation locally and systemically, with no influence upon [EMV]. Local shear stress, however, does not appear to be the major stimulus modulating PMV formation in healthy humans

Cognitive behavioral therapy for body image and self-care (CBT-BISC) in sexual minority men living with HIV: a randomized controlled trial

OBJECTIVE: Body image disturbance is a distressing and interfering problem among many sexual minority men living with HIV, and is associated with elevated depressive symptoms and poor HIV self-care (e.g., antiretroviral therapy [ART] nonadherence). The current study tested the preliminary efficacy of a newly created intervention: cognitive–behavioral therapy for body image and self-care (CBT-BISC) for this population. METHOD: The current study entailed a 2-arm randomized controlled trial (N = 44) comparing CBT-BISC to an enhanced treatment as usual (ETAU) condition. Analyses were conducted at 3 and 6 months after baseline. The primary outcome was body image disturbance (BDD-YBOCS), and secondary outcomes were ART adherence (electronically monitored via Wisepill), depressive symptoms (MADRS), and global functioning (GAF). RESULTS: At 3 months, the CBT-BISC condition showed substantial improvement in BDD-YBOCS (b = −13.6, SE = 2.7, 95% CI [−19.0, −8.3], p < .001; dppc2 = 2.39); MADRS (b = −4.9, SE = 2.8, 95% CI [−10.6, .70], p = .086; dppc2 = .87); ART adherence (b = 8.8, SE = 3.3, 95% CI [2.0, 15.6], p = .01; dppc2 = .94); and GAF (b = 12.3, SE = 3.2, 95% CI [6.1, 18.6], p < .001; dppc2 = 2.91) compared with the ETAU condition. Results were generally maintained, or improved, at 6 months; although, adherence findings were mixed depending on the calculation method. CONCLUSIONS: CBT-BISC shows preliminary efficacy in the integrated treatment of body image disturbance and HIV self-care behaviors among sexual minority men living with HIV. (APA PsycInfo Database Record (c) 2019 APA, all rights reserved)Funding from this project came from K23MH096647. Author time for Steven A. Safren was supported by K24DA040489 (formally K24MH094214). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institute of Mental Health or the National Institutes of Health. (K23MH096647; K24DA040489; K24MH094214)Accepted manuscrip

Niche of harmful alga Aureococcus anophagefferens revealed through ecogenomics

Harmful algal blooms (HABs) cause significant economic and ecological damage worldwide. Despite considerable efforts, a comprehensive understanding of the factors that promote these blooms has been lacking, because the biochemical pathways that facilitate their dominance relative to other phytoplankton within specific environments have not been identified. Here, biogeochemical measurements showed that the harmful alga Aureococcus anophagefferens outcompeted co-occurring phytoplankton in estuaries with elevated levels of dissolved organic matter and turbidity and low levels of dissolved inorganic nitrogen. We subsequently sequenced the genome of A. anophagefferens and compared its gene complement with those of six competing phytoplankton species identified through metaproteomics. Using an ecogenomic approach, we specifically focused on gene sets that may facilitate dominance within the environmental conditions present during blooms. A. anophagefferens possesses a larger genome (56 Mbp) and has more genes involved in light harvesting, organic carbon and nitrogen use, and encoding selenium- and metal-requiring enzymes than competing phytoplankton. Genes for the synthesis of microbial deterrents likely permit the proliferation of this species, with reduced mortality losses during blooms. Collectively, these findings suggest that anthropogenic activities resulting in elevated levels of turbidity, organic matter, and metals have opened a niche within coastal ecosystems that ideally suits the unique genetic capacity of A. anophagefferens and thus, has facilitated the proliferation of this and potentially other HABs

Infection by a Giant Virus (AaV) Induces Widespread Physiological Reprogramming in Aureococcus anophagefferens CCMP1984 – A Harmful Bloom Algae

While viruses with distinct phylogenetic origins and different nucleic acid types can infect and lyse eukaryotic phytoplankton, “giant” dsDNA viruses have been found to be associated with important ecological processes, including the collapse of algal blooms. However, the molecular aspects of giant virus–host interactions remain largely unknown. Aureococcus anophagefferens virus (AaV), a giant virus in the Mimiviridae clade, is known to play a critical role in regulating the fate of brown tide blooms caused by the pelagophyte Aureococcus anophagefferens. To understand the physiological response of A. anophagefferens CCMP1984 upon AaV infection, we studied the transcriptomic landscape of this host–virus pair over an entire infection cycle using a RNA-sequencing approach. A massive transcriptional response of the host was evident as early as 5 min post-infection, with modulation of specific processes likely related to both host defense mechanism(s) and viral takeover of the cell. Infected Aureococcus showed a relative suppression of host-cell transcripts associated with photosynthesis, cytoskeleton formation, fatty acid, and carbohydrate biosynthesis. In contrast, host cell processes related to protein synthesis, polyamine biosynthesis, cellular respiration, transcription, and RNA processing were overrepresented compared to the healthy cultures at different stages of the infection cycle. A large number of redox active host-selenoproteins were overexpressed, which suggested that viral replication and assembly progresses in a highly oxidative environment. The majority (99.2%) of annotated AaV genes were expressed at some point during the infection cycle and demonstrated a clear temporal–expression pattern and an increasing relative expression for the majority of the genes through the time course. We detected a putative early promoter motif for AaV, which was highly similar to the early promoter elements of two other Mimiviridaemembers, indicating some degree of evolutionary conservation of gene regulation within this clade. This large-scale transcriptome study provides insights into the Aureococcus cells infected by a giant virus and establishes a foundation to test hypotheses regarding metabolic and regulatory processes critical for AaV and other Mimiviridae members