For successful infection of their hosts, pathogenic bacteria recognize host-derived signals that induce the expression of virulence factors in a spatiotemporal manner. The fulminating food-borne pathogen Vibrio vulnificus produces a cytolysin/hemolysin protein encoded by the vvhBA operon, which is a virulence factor preferentially expressed upon exposure to murine blood and macrophages. The Fe-S cluster containing transcriptional regulator IscR activates the vvhBA operon in response to nitrosative stress and iron starvation, during which the cellular IscR protein level increases. Here, electrophoretic mobility shift and DNase I protection assays revealed that IscR directly binds downstream of the vvhBA promoter PvvhBA, which is unusual for a positive regulator. We found that in addition to IscR, the transcriptional regulator HlyU activates vvhBA transcription by directly binding upstream of PvvhBA, whereas the histone-like nucleoid-structuring protein (H-NS) represses vvhBA by extensively binding to both downstream and upstream regions of its promoter. Of note, the binding sites of IscR and HlyU overlapped with those of H-NS. We further substantiated that IscR and HlyU outcompete H-NS for binding to the PvvhBA regulatory region, resulting in the release of H-NS repression and vvhBA induction. We conclude that concurrent antirepression by IscR and HlyU at regions both downstream and upstream of PvvhBA provides V. vulnificus with the means of integrating host-derived signal(s) such as nitrosative stress and iron starvation for precise regulation of vvhBA transcription, thereby enabling successful host infection.

(University of Illinois at Urbana-Champaign, News Bureau) University of Illinois classics professor Clara Bosak-Schroeder writes about how the ancient Greeks thought about natural resources and how it is relevant to responding to climate change today.

(University of Bath) Researchers at the University of Bath have developed an AI model that can automatically classify underwater environments directly from sonar measurements.

This programme of work addresses the conundrum of nuclear weapons as a wicked problem in a complex adaptive system.

Research Event

Event participants

Glada Lahn, Senior Research Fellow, Energy, Environment and Resources Programme, Chatham House
Greg Shapland, Associate Fellow, Middle East and North Africa Programme, Chatham House 
Moderator: Sanam Vakil, Deputy Director and Senior Research Fellow, Middle East and North Africa Programme, Chatham House

The histidine kinase Hik33 plays important roles in mediating cyanobacterial response to divergent types of abiotic stresses including cold, salt, high light (HL), and osmotic stresses. However, how these functions are regulated by Hik33 remains to be addressed. Using a hik33-deficient strain (hik33) of Synechocystis sp. PCC 6803 (Synechocystis) and quantitative proteomics, we found that Hik33 depletion induces differential protein expression highly similar to that induced by divergent types of stresses. This typically includes downregulation of proteins in photosynthesis and carbon assimilation that are necessary for cell propagation, and upregulation of heat shock proteins, chaperons, and proteases that are important for cell survival. This observation indicates that depletion of Hik33 alone mimics divergent types of abiotic stresses, and that Hik33 could be important for preventing abnormal stress response in the normal condition. Moreover, we found the majority of proteins of plasmid origin were significantly upregulated in hik33, though their biological significance remains to be addressed. Together, the systematically characterized Hik33-regulated cyanobacterial proteome, which is largely involved in stress responses, builds the molecular basis for Hik33 as a general regulator of stress responses.

Under UNIX, the process of updating a lookup table in SAS Business Rules Manager does not work properly. The problem occurs when you perform these steps:  Open a lookup table. Cl

Tumor cells can spread to distant sites through their ability to switch between mesenchymal and amoeboid (bleb-based) migration. Because of this difference, inhibitors of metastasis must account for each migration mode. However, the role of vimentin in amoeboid migration has not been determined. Because amoeboid leader bleb–based migration (LBBM) occurs in confined spaces and vimentin is known to strongly influence cell-mechanical properties, we hypothesized that a flexible vimentin network is required for fast amoeboid migration. To this end, here we determined the precise role of the vimentin intermediate filament system in regulating the migration of amoeboid human cancer cells. Vimentin is a classic marker of epithelial-to-mesenchymal transition and is therefore an ideal target for a metastasis inhibitor. Using a previously developed polydimethylsiloxane slab–based approach to confine cells, RNAi-based vimentin silencing, vimentin overexpression, pharmacological treatments, and measurements of cell stiffness, we found that RNAi-mediated depletion of vimentin increases LBBM by ∼50% compared with control cells and that vimentin overexpression and simvastatin-induced vimentin bundling inhibit fast amoeboid migration and proliferation. Importantly, these effects were independent of changes in actomyosin contractility. Our results indicate that a flexible vimentin intermediate filament network promotes LBBM of amoeboid cancer cells in confined environments and that vimentin bundling perturbs cell-mechanical properties and inhibits the invasive properties of cancer cells.

Mikael Knip
Dec 1, 2005; 54:S125-S136
Section IV: Polygenic Disease and Environment

Invitation Only Research Event

1 June 2012 , Volume 68, Number 4

Eyes in the skies keeping watch on a planet under stress. Click on the PDF link to view the graphic

7 September 2012 , Volume 88, Number 5

The rapid changes in the global environment have led many scientists to conclude that we are living in a new geological epoch—the Anthropocene—in which human activities have become the dominant driving force transforming the Earth’s natural systems. A recent joint publication by the World Health Organization and Convention on Biological Diversity...

2 July 2014 , Volume 90, Number 4

This policy brief explores the relationship between environmental change and migration to Europe in light of recent scholarship challenging the notion that environmental change triggers mass migration. It presents an overview of European policy response in this area and summarizes the spectrum of proposed solutions.

Environmental change is likely to affect global migration flows in a number of ways. Both long-term trends such as increased flooding and the increasing scarcity of resources as well as shorter term trends like severe weather are likely to contribute to displacement and increased migration for individuals already in vulnerable situations. While often viewed as a negative outcome of climate change, planned migration can also serve as a strategy for mitigating its impact.  

Discussion at launch of this MPI-IOM Issue in Brief, Human Rights, Climate Change, Environmental Degradation and Migration: A New Paradigm, which focuses on the vulnerability of environmental migrants and how the international legal framework can better ensure their protection, particularly in the Asia-Pacific region.

This issue brief addresses the rights of migrants whose movement is induced by environmental degradation or climate change, particularly in the highly vulnerable Asia-Pacific region. The brief evaluates the current international legal framework, identifies gaps in the framework and its implementation, and reviews options available to the international community.

This MPI event, in partnership with the International Organization for Migration (IOM), discusses the critical issue of climate-related displacement in the Asia-Pacific region, focusing on the vulnerability of environmental migrants and how the international legal framework can better ensure their protection.

OBJECTIVE

Excessive iron intake has been linked to diabetes risk. However, the evidence is inconsistent. This study examined the association between dietary heme and nonheme iron intake and diabetes risk in the Chinese population.

The warty comb jelly is native to the western Atlantic, but in recent decades, it has invaded the waters of Eurasia. New research suggests cannibalism is key to the species' ability to move into new environs.

In the courts and in Congress, Sen. Larry Craig is fighting to withdraw his guilty plea to a misdemeanor charge that may suggest he tried to solicit sex from a man in June at a Minneapolis airport bathroom. Rather than resign yesterday, as the senator had promised and Republicans had hoped, Craig...

If you consult the online encyclopedia Wikipedia, which is democratically created by Internet users, you will see a pattern emerge in the phrases used to describe the first female leaders of many countries.

Christine A. Beebe
Jul 1, 2011; 29:123-126
Practical Pointers

Two forthcoming pieces in History of the Human Sciences may be of interest to AHP readers. Full details below. “Cold War Pavlov: Homosexual aversion therapy in the 1960s,” by Kate Davison. Abstract: Homosexual aversion therapy enjoyed two brief but intense periods of clinical experimentation: between 1950 and 1962 in Czechoslovakia, and between 1962 and 1975 … Continue reading Forthcoming in HHS: Homosexual Aversion Therapy, Comte on Organism-Environment Relationships →