A Study of the Interrelationship of Magnesium Metabolism with that of Protein in the Human Adult

(From the Introduction) The purpose of the work reported in this paper was to study the influence of level of dietary protein upon utilization of magnesium. The experiments consisted of a series of metabolic balance studies in which young adults were fed diets containing different, relatively low levels of protein and constant amounts of magnesium and other nutrients. Results will provide information concerning the influence of dietary protein upon magnesium metabolism in the adult and serve as a basis for planning a future similar study with preadolescent children

How effective are MPAs? Predation control and 'spill-in effects' in seagrass-coral reef lagoons under contrasting fishery management

Marine protected areas (MPAs) are heavily promoted as a panacea for marine conservation, but lagging and sometimes idiosyncratic protection effects bring their overall effectiveness into question. In Kenyan lagoons, seagrass overgrazing by the sea urchin Tripneustes gratilla has been linked to removal of predators, but overgrazing has also been observed within well-protected MPAs. In this study we investigated the effectiveness of Kenyan MPAs in facilitating predation control over sea urchins, particularly T gratilla, in relation to system (seagrass or coral reef), distance to reefs, and seagrass presence. A strong protection effect on urchin densities on reefs and a negative correlation between T gratilla density and predation pressure (from sea stars, fish and gastropods) in seagrass beds (r(2) = 0.345) confirmed the importance of top-down control. Yet there were no clear effects of protection or distance to reefs in seagrass beds, most likely due to (1) low predator densities in the recently established Mombasa MPA; (2) 'spill-in' of aggregated T gratilla into the older Watamu MPA (potentially facilitated by low predation pressure on the large urchins and nutrient enrichment); and (3) a potential buffering effect of seagrass canopies on predation, regardless of distance to reefs. Effects of seagrass presence differed between areas, but indicated that overgrazing in some areas could be self-regulated by inducing higher urchin mortality. As MPA effects appear to be system-, time- and site-specific, managers should also assess other more holistic approaches (e.g. banned fishing of urchin predators and reduced nutrient input from land runoff) to protect seagrasses

A framework to assess national level vulnerability from the perspective of food security: the case of coral reef fisheries

Measuring the vulnerability of human populations to environmental change is increasingly being used to develop appropriate adaptation policies and management plans for different economic sectors. We developed a national-level vulnerability index that is specific to food security policies by measuring nations' relative vulnerabilities to a decline in their coral reef fisheries. Coral reef fisheries are expected to decline with climate and anthropogenic disturbances, which may have significant consequences for food security. The vulnerability measure was composed of exposure, sensitivity, and adaptive capacity indicators specific to fisheries, reef management, and food security. The vulnerability index was used to evaluate 27 countries, as data required to fully populate the theoretical framework was limited. Of these, Indonesia and Liberia were identified as most and Malaysia and Sri Lanka as least vulnerable nations. Our analysis revealed two common national vulnerability characterizations: low income countries with low adaptive capacity and middle-income countries with higher adaptive capacity but high sensitivity. These results suggest developing context-specific policies and actions to build adaptive capacity in the low-income countries, and to decrease sensitivity in middle-income countries. Comparing our food security evaluation to a more general vulnerability approach shows that they produce different priority countries and associated policies

IL-6, but not TNF-α, response to alcohol cues and acute consumption associated with neural cue reactivity, craving, and future drinking in binge drinkers

Objective and design: Preclinical studies suggest learned immune system responses to alcohol cues and consumption may contribute to alcohol's pharmacodynamic properties and/or Alcohol Use Disorder (AUD) pathogenesis. Mechanistically, these immune alterations may be associated with increased craving and alcohol consumption, both acutely and over time. We sought to characterize this relationship in a randomized, counter-balanced, crossover neuroimaging experiment which took place between June 2020–November 2021. Methods: Thirty-three binge drinkers (BD) and 31 non-binge, social drinkers (SD), matched for demographic and psychological variables, were exposed to alcohol cues and water cues in two separate 7 T functional magnetic resonance imaging (fMRI) scans. Each scan was followed by the Alcohol Taste Test (ATT) of implicit motivation for acute alcohol. Craving measures and blood cytokine levels were collected repeatedly during and after scanning to examine the effects of alcohol cues and alcohol consumption on craving levels, Tumor necrosis factor alpha (TNF-α), and Interleukin 6 (IL-6) levels. A post-experiment one-month prospective measurement of participants’ “real world” drinking behavior was performed to approximate chronic effects. Results: BD demonstrated significantly higher peak craving and IL-6 levels than SD in response to alcohol cues and relative to water cues. Ventromedial Prefrontal Cortex (VmPFC) signal change in the alcohol-water contrast positively related to alcohol cue condition craving and IL-6 levels, relative to water cue condition craving and IL-6 levels, in BD only. Additionally, peak craving and IL-6 levels were each independently related to ATT alcohol consumption and the number of drinks consumed in the next month for BD, again after controlling for craving and IL-6 repones to water cues. However, TNF-α release in the alcohol cue condition was not related to craving, neural activation, IL-6 levels, immediate and future alcohol consumption in either group after controlling for water cue condition responses. Conclusions: In sum, BD show greater craving and IL-6 release in the alcohol cue condition than SD, both of which were associated with prefrontal cue reactivity, immediate alcohol consumption, and future alcohol consumption over the subsequent 30 days. Alcohol associated immune changes and craving effects on drinking behavior may be independent of one another or may be indicative of a common pathway by which immune changes in BD could influence motivation to consume alcohol. Trial registration: Clinical Trials NCT04412824

Crucial role of FLT3 ligand in immune reconstitution after bone marrow transplantation and high-dose chemotherapy

Almost 5 decades after the first clinical transplantations, delayed immune reconstitution remains a considerable hurdle in bone marrow transplantation, and the mechanisms regulating immune reconstitution after transplantation remain to be established. Whereas adult fms-like tyrosine kinase 3 ligand-deficient (FL-/-) mice have reduced numbers of early Band T-cell progenitors, they sustain close to normal levels of mature B and T cells. Herein, we demonstrate that adult bone marrow cells fail to reconstitute B-cell progenitors and conventional B cells in lethally irradiated FL-/- recipients, which also display delayed kinetics of T-cell reconstitution. Similarly, FL is essential for B-cell regeneration after chemotherapy-induced myeloablation. In contrast, fetal progenitors reconstitute B lymphopoiesis in FL-/- mice, albeit at reduced levels. A critical role of FL in adult B lymphopoiesis is further substantiated by an age-progressive decline in peripheral conventional B cells in FL-/- mice, whereas fetally and early postnatally derived B1 and marginal zone B cells are sustained in a FL-independent manner. Thus, FL plays a crucial role in sustaining conventional B lymphopoiesis in adult mice and, as a consequence, our findings implicate a critical role of FL in promoting immune reconstitution after myeloablation and bone marrow transplantation

Immune evasion or avoidance: fungal skin infection linked to reduced defence peptides in Australian green-eyed treefrogs, Litoria serrata

Many parasites and pathogens suppress host immunity to maintain infection or initiate disease. On the skin of many amphibians, defensive peptides are active against the fungus Batrachochytrium dendrobatidis (Bd), the causative agent of the emerging infectious disease chytridiomycosis. We tested the hypothesis that infection with the fungus may be linked to lower levels of defensive peptides. We sampled both ambient (or constitutive) skin peptides on the ventral surface immediately upon capture, and stored skin peptides induced from granular glands by norepinephrine administration of Australian green-eyed treefrogs, Litoria serrata. Upon capture, uninfected frogs expressed an array of antimicrobial peptides on their ventral surface, whereas infected frogs had reduced skin peptide expression. Expression of ambient skin peptides differed with infection status, and antimicrobial peptides maculatin 1.1 and 2.1 were on average three times lower on infected frogs. However, the repertoire of skin peptides stored in granular glands did not differ with infection status; on average equal quantities were recovered from infected and from uninfected frogs. Our results could have at least two causes: (1) frogs with reduced peptide expression are more likely to become infected; (2) Bd infection interferes with defence peptides by inhibiting release or causing selective degradation of peptides on the skin surface. Immune evasion therefore may contribute to the pathogenesis of chytridiomycosis and a mechanistic understanding of this fungal strategy may lead to improved methods of disease control

Macroalgae exhibit diverse responses to human disturbances on coral reefs

Scientists and managers rely on indicator taxa such as coral and macroalgal cover to evaluate the effects of human disturbance on coral reefs, often assuming a universally positive relationship between local human disturbance and macroalgae. Despite evidence that macroalgae respond to local stressors in diverse ways, there have been few efforts to evaluate relationships between specific macroalgae taxa and local human‐driven disturbance. Using genus‐level monitoring data from 1205 sites in the Indian and Pacific Oceans, we assess whether macroalgae percent cover correlates with local human disturbance while accounting for factors that could obscure or confound relationships. Assessing macroalgae at genus level revealed that no genera were positively correlated with all human disturbance metrics. Instead, we found relationships between the division or genera of algae and specific human disturbances that were not detectable when pooling taxa into a single functional category, which is common to many analyses. The convention to use percent cover of macroalgae as an indication of local human disturbance therefore likely obscures signatures of local anthropogenic threats to reefs. Our limited understanding of relationships between human disturbance, macroalgae taxa, and their responses to human disturbances impedes the ability to diagnose and respond appropriately to these threats