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2016 is here. The New Year is a time for renewal and resolution. It is also a time for dieting. Peak enrolment and attendance times at gyms occur after sumptuous holiday indulgences in December and again when beach wear is cracked out of cold storage in summer. As the obesity epidemic reaches across the globe we need new solutions. We need better ways to live healthy lifestyles.

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Another ‘Awareness Day’, International Kissing Day, is coming up on July 6. It might not seem obvious but kissing, like most subjects can now be easily linked to the science of DNA. Thus, there could be no more perfect opener for my Double Helix column, given the elegance and beauty of a kiss. To start, there is the obvious biological link between kissing and DNA: propagation of the species. Kissing is not only pleasurable but seems to be a solid way to assess the quality and suitability of a mate.

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The study of minerals is the most fundamental aspect of the Earth and environmental sciences. Minerals existed long before any forms of life. They have played an important role in the origin and evolution of life and interact with biological systems in ways we are only now beginning to understand.

One of the most rapidly developing areas in what is now called ‘geobiology’ concerns the role of microbes in processes both of mineral formation and destruction. For example, the ‘geobacter’ bacteria, shown in the accompanying picture taken in an electron microscope, are not just sitting on an iron oxide mineral surface but interacting with it because it is their method of ‘respiration’ (just as breathing oxygen is ours).

A transfer of electrons between the microbe and the mineral in this case brings about a change in the chemical state of the iron (its ‘reduction’) which also causes the mineral to dissolve. Interactions of this type are now known to play important roles in the release and movement of metals and other elements, including pollutants such as arsenic, at the Earth’s surface.

A very different story linking minerals and the living world concerns the ways that many organisms form minerals to fulfil a particular function, such as providing an external skeleton (shell).

For example, the chalk rock responsible for the ‘White Cliffs of Dover’ in the south of England are almost entirely composed of the remains of microscopic plates of calcite derived from a protective armour around unicellular planktonic algae (‘coccolithophorids’). In many cases the products of such processes of ‘biomineralisation’ are delicate structures of great beauty.

A good example is provided by the (as illustrated) ‘radiolaria’, free-floating single celled organisms found in the upper regions of the water column in the oceans, and  which have skeletons of poorly crystalline (‘opaline’) silica.

Amongst the most remarkable examples of organisms producing a mineral to serve a specific function are the ‘magnetotactic bacteria’. Here the bacterium concerned produces a chain of perfect crystals (see illustration of magnetite crystals), most commonly of magnetite, which make use of the magnetic properties of that mineral. It seems that these organisms use magnetite to become aligned in relation to the Earth’s magnetic field and therefore in the most advantageous position in relation to the sediment-water interface.

One of the most challenging questions in all of science is: ‘How did life on Earth originate’? It is now widely believed that minerals played a key role as catalysts for biochemical reactions and templates for the emergence of the complex biomolecules needed for life. Many different routes have been proposed for the emergence of the first living organisms, almost all have major roles for minerals. These roles may have been in providing catalysts through biomolecule sized cavities in their crystal structures or weathered surfaces. Other routes involve clay minerals as substrates aiding in the formation of the first self-replicating genetic molecules, or look to the environments at, or near, mid-ocean ridges where hot fluids emerge releasing a stream of metal sulphide mineral particles. At the present day, both micro- and macro-organisms utilise chemical energy available in these environments for their metabolisms. Iron sulphide minerals are suggested as the key catalysts in these models.

There are challenging questions in all of these areas, whether it be understanding the electron transfer processes involved when bacteria interact with minerals, the mechanisms involved in biomineral formation, or the complex roles probably played by minerals in the emergence of life on Earth.

In these and many other cases, it is the processes at mineral surfaces which are critically important. Only in recent years has it been possible to study mineral surfaces at a molecular scale. Today, we are at the threshold of a new understanding of the processes taking place at the surface of the Earth which integrates the mineralogical, geochemical and biological realms at the molecular scale. Understanding what happens at surfaces and interfaces at scales from global to molecular is key to that understanding. Here, the emergent field of ‘molecular environmental science’ should provide new insights into the way our planet ‘works’ comparable to the revolutionary advances seen in human biology associated with the genetic code.

Featured image credit: Didimocrytus tetrathalamus, by Tim Evanson. CC-BY-SA-2.0 via Wikimedia Commons.

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Microbiology should be part of everyone’s educational experience. European students deserve to know something about the influence of microscopic forms of life on their existence, as it is at least as important as the study of the Roman Empire or the Second World War. Knowledge of viruses should be as prominent in American high school curricula as the origin of the Declaration of Independence. This limited geographic compass reflects the fact that the science of microbiology is a triumph of Western civilization, but the educational significance of the field is a global concern. We cannot understand life without an elementary comprehension of microorganisms.

Appreciation of the microbial world might begin by looking at pond water and pinches of wet soil with a microscope. Precocious children could be encouraged in this fashion at a very early age. Deeper inquiry with science teachers would build a foundation of knowledge for teenagers, before the end of their formal education or the pursuit of a university degree in the humanities.

Earth has always been dominated by microorganisms. Most genetic diversity exists in the form of microbes and if animals and plants were extinguished by cosmic bombardment, biology would reboot from reservoirs of this bounty. The numbers of microbes are staggering. Tens of millions of bacteria live in a crumb of soil. A drop of seawater contains 500,000 bacteria and tens of millions of viruses. The air is filled with microscopic fungal spores, and a hundred trillion bacteria swarm inside the human gut. Every macroscopic organism and every inanimate surface is coated with microbes. They grow around volcanoes and hydrothermal vents. They live in blocks of sea ice, in the deepest oceans, and thrive in ancient sediment on the seafloor. Microbes act as decomposers, recycling the substance of dead organisms. Others are primary producers, turning carbon dioxide into sugars using sunlight or by tapping chemical energy from hydrogen sulfide, ferrous iron, ammonia, and methane.

Bacterial infections are caused by decomposers that survive in living tissues. Airborne bacteria cause diphtheria, pertussis, tuberculosis, and meningitis. Airborne viruses cause influenza, measles, mumps, rubella, chickenpox, and the common cold. Hemorrhagic fevers caused by Ebola viruses are spread by direct contact with infected patients. Diseases transmitted by animal bites include bacterial plague, as the presumed cause of the Black Death, which killed 200 million people in the 14^th century. Typhus spread by lice decimated populations of prisoners in concentration camps and refugees during the Second World War. Malaria, carried by mosquitos, massacres half a million people every year.

Contrary to the impression left by this list of infections, relatively few microbes are harmful and we depend on a lifelong cargo of single-celled organisms and viruses. The bacteria in our guts are essential for digesting the plant part of our diet and other bacteria and yeasts are normal occupants of healthy skin. The tightness of our relationship with microbes is illustrated by the finding that human DNA contains 100,000 fragments of genes that came from viruses. We are surprisingly microbial.

Missing the opportunity to learn something about microbiology is a mistake. The uninformed are likely to be left with a distorted view of biology in which they miscast themselves as the most important organisms. For example, “Sarah” is a significant manifestation of life from Sarah’s perspective, but her body is not the individual organism that she imagines, and nor, despite her talents, is she a major player in the ecology of the planet. Her interactions with microbes will include a healthy relationship with bacteria in her gut, bouts of influenza and other viral illnesses, and death in old age from an antibiotic-resistant infection. Sarah’s microbiology will continue after death with her decomposition by fungi. In happier times she will become an expert on Milton’s poetry, and delight students by reciting Lycidas through her tears, but she will never know a thing about microbiology. This is a pity. Learning about viruses that bloom in seawater and fungi that sustain rainforests would not have stopped her from falling in love with Milton.

Even brief consideration of microorganisms can be inspiring. A simple magnifying lens transforms the surface of rotting fruit into a hedgerow of glittering stalks topped with jet-black fungal spores. Microscopes take us deeper, to the slow revolution of the bright green globe of the alga Volvox as its beats its way through a drop of pond water. A greater number of microbes are quite dull things to look at and their appreciation requires greater imagination. Considering that our bodies are huge ecosystems supported by trillions of bacteria is a good place to start, and then we might realize that we fade from view against the grander galaxy of life on Earth. The science of microbiology is a marvel for our time.

Featured image credit: BglII-DNA complex By Gwilliams10. Public domain via Wikimedia Commons

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By John Archibald

We humans have a love-hate relationship with bugs. I’m not talking about insects — although many of us cringe at the thought of them too — but rather the bugs we can’t see, the ones that make us sick.

Sure, microorganisms give us beer, wine, cheese, and yoghurt; hardly a day goes by without most people consuming food or drink produced by microbial fermentation. And we put microbes to good use in the laboratory, as vehicles for the production of insulin and other life-saving drugs, for example.

But microbes are also responsible for much of what ails us, from annoying stomach ‘bugs’ to deadly infectious diseases such as tuberculosis and plague. Bacteria and viruses are even linked to certain cancers. Bugs are bad; antibiotics and antivirals are good. We spend billions annually trying to rid ourselves of microorganisms, and if they were to all disappear, well, all the better, right?

This is, of course, nonsense. Even the most ardent germaphobe would take a deep breath and accept the fact that we could no more survive without microbes than we could without oxygen. No matter how clean we strive to be, there are 100 trillion bacterial cells living on and within our bodies, 10 times the number of human cells that comprise ‘us’. Hundreds of different bacterial species live within our intestines, hundreds more thrive in our mouths and on our skin. Add in the resident viruses, fungi, and small animals such as worms and mites, and the human body becomes a full-blown ecosystem, a microcosm of the world around us. And like any ecosystem, if thrown off-balance bad things can happen. For example, many of our ‘good’ bacteria help us metabolize food and fight off illness. But after a prolonged course of antibiotics such bacteria can be knocked flat, and normally benign species such as ‘Clostridium difficile’ can grow out of control and cause disease.

Given the complexity of our body jungle, some researchers go as far as to propose that there is no such thing as a ‘human being’. Each of us should instead be thought of as a human-microbe symbiosis, a complex biological relationship in which neither partner can survive without the other. As disturbing a notion as this may be, one thing is indisputable: we depend on our microbiome and it depends on us.

And there is an even more fundamental way in which the survival of Homo sapiens is intimately tied to the hidden microbial majority of life. Each and every one of our 10 trillion cells betrays its microbial ancestry in harboring mitochondria, tiny subcellular factories that use oxygen to convert our food into ATP, the energy currency of all living cells. Our mitochondria are, in essence, domesticated bacteria — oxygen-consuming bacteria that took up residence inside another bacterium more than a billion years ago and never left. We know this because mitochondria possess tiny remnants of bacterium-like DNA inside them, distinct from the DNA housed in the cell nucleus. Modern genetic investigations have revealed that mitochondria are a throwback to a time before complex animals, plants, or fungi had arisen, a time when life was exclusively microbial.

As we ponder the bacterial nature of our mitochondria, it is also instructive to consider where the oxygen they so depend on actually comes from. The answer is photosynthesis. Within the cells of plants and algae are the all-important chloroplasts, green-tinged, DNA-containing factories that absorb sunlight, fix carbon dioxide, and pump oxygen into the atmosphere by the truckload. Most of the oxygen we breathe comes from the photosynthetic activities of these plants and algae—and like mitochondria, chloroplasts are derived from bacteria by symbiosis. The genetic signature written within chloroplast DNA links them to the myriad of free-living cyanobacteria drifting in the world’s oceans. Photosynthesis and respiration are the biochemical yin and yang of life on Earth. The energy that flows through chloroplasts and mitochondria connects life in the furthest corners of the biosphere.

For all our biological sophistication and intelligence, one could argue that we humans are little more than the sum of the individual cells from which we are built. And as is the case for all other complex multicellular organisms, our existence is inexorably linked to the sea of microbes that share our physical space. It is a reality we come by honestly. As we struggle to tame and exploit the microbial world, we would do well to remember that symbiosis—the living together of distinct organisms—explains both what we are and how we got here.

John Archibald is Professor of Biochemistry and Molecular Biology at Dalhousie University and a Senior Fellow of the Canadian Institute for Advanced Research, Program in Integrated Microbial Biodiversity. He is an Associate Editor for Genome Biology & Evolution and an Editorial Board Member of various scientific journals, including Current Biology, Eukaryotic Cell, and BMC Biology. He is the author of One Plus One Equals One: Symbiosis and the Evolution of Complex Life.

Image credit: Virus Microbiology. Public domain via Pixabay

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By Rebecca Cramp

In recent decades, the extraordinarily rapid disappearance of frogs, toads, and salamanders has grabbed the attention of both the scientific community and concerned citizens the world over. Although the causes of some of these losses remain unresolved, the novel disease chytridiomycosis caused by the skin-based fungus Batrachochytrium dendrobatidis (Bd), has been identified as the causative agent in many of the declines and extinctions worldwide. Bd is now regarded as being responsible for the greatest disease-driven loss of vertebrate biodiversity in recorded history.  Like other entirely cutaneous microbes, interactions with the skin of its host determine how and under what conditions the fungus can induce disease.

The skin plays an important role in immune defence. In the first instance, skin acts as a physical barrier against microbes and pathogens. It also produces anti-microbial skin secretions and supports a large microbial community made up of good (commensal), bad (pathogenic) and indifferent (neither good nor bad; having no discernable effect) microbes. Like most animals, the outer skin layer of amphibians is shed (sloughed) on a regular basis—as often as daily to every couple of weeks. However, unlike mammals, amphibians shed (and often eat) the entire outer skin layer in one piece.  Therefore, anything adhering to or within that outer layer would be lost from the body every time the animal sloughs it skin. As such, regular sloughing could play a role in regulating the abundance and persistence of microbes (including Bd) at the body’s surface. To date, however, the potential for regular skin sloughing to serve as an immune defense strategy in amphibians has been largely overlooked.

A green tree frog. Photo by Ed Meyer.

To test the hypothesis that sloughing in plays a role in the management of cutaneous microbe abundance, we investigated changes in the number of cultivable cutaneous bacteria on the ventral and dorsal body surfaces of the Green tree frog (Litoria caerulea) with sloughing. Effects of temperature on sloughing periodicity were also investigated in order to determine how the efficacy of sloughing in regulating microbial infection might vary with climate and season. Our study showed that sloughing massively reduced the overall abundance of bacteria, in some cases by as much as 100%. In addition, temperature had a marked effect on sloughing periodicity, with animals in cooler temperatures having a much longer time between sloughs compared with animals at held higher temperatures.

Most importantly however, we found that the extended time between sloughs in animals in the cold treatments allowed skin microbe numbers to increase to levels in excess of those seen in animals in the warm treatment. These data suggest that for pathogens that like relatively cooler conditions (like Bd), the effect of temperature on host sloughing frequency may allow pathogen numbers to build up to such a degree that fatal disease occurs.

What does it all mean, though? Firstly, the epidemiology of skin based diseases like Bd could be in part attributed to the effects of temperature on host sloughing periodicity particularly when disease outbreaks occur in cool habitats and/or at cooler times of year. Secondly, differences between species in the frequency of sloughing could influence pathogen establishment and go some way to explaining why some amphibian species are more resistant to cutaneous pathogens than others. Thirdly, the ability of commensal (good) bacteria to protect against pathogens may be reduced in frog species which slough frequently as commensal bacteria would also be lost from the skin with sloughing, unless they are able to recolonise the skin rapidly.

Understanding the role the skin plays as the first bastion of defense against external pathogens is vitally important as the rate of emergence of both novel and pre-existing infectious diseases is predicted to skyrocket in the future as a result of anthropogenic climate change.

Dr Rebecca Cramp is a Research Officer at The University of Queensland in the laboratory of Professor Craig Franklin. Rebecca has diverse research interests and is currently working on several projects including a study of disease susceptibility in frogs, the control of ion regulation in acid-tolerant amphibian larvae and the effects of environmental stressors on immune function in amphibian larvae. She is a co-author of the paper ‘First line of defence: the role of sloughing in the regulation of cutaneous microbes in frogs‘, which appears in the journal Conservation Physiology.

Conservation Physiology is an online only, fully open access journal published on behalf of the Society for Experimental Biology. Biodiversity across the globe faces a growing number of threats associated with human activities. Conservation Physiology publishes research on all taxa (microbes, plants and animals) focused on understanding and predicting how organisms, populations, ecosystems and natural resources respond to environmental change and stressors. Physiology is considered in the broadest possible terms to include functional and mechanistic responses at all scales.

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Image credit: A green tree frog. Photo by Ed Meyer. Do not reproduce without permission.

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By Nicholas P. Money

The small picture is the big picture and biologists keep missing it. The diversity and functioning of animals and plants has been the meat and potatoes of most natural historians since Aristotle, and we continue to neglect the vast microbial majority. Before the invention of the microscope in the seventeenth century we had no idea that life existed in any form but the immediately observable. This delusion was swept away by Robert Hooke, Anton van Leeuwenhoek, and other pioneers of optics who found that tiny forms of life looked a lot like the cells that comprise our own tissues. We were, they showed, constructed from the same essence as the writhing animalcules of ponds and spoiled food. And yet this revelation was somehow folded into the continuing obsession with human specialness, allowing Carolus Linnaeus to catalogue plants and big animals and ignore the lilliputian majority. When microbiological inquiry was restimulated by Louis Pasteur in the nineteenth century, it became the science of germs and infectious disease. The point was not to glory in the diversity of microorganisms but exterminate them. In any case, as before, most of life was disregarded.

Things are changing very swiftly now. Molecular fishing expeditions in which raw biological information is examined using metagenomic methods have discovered an abundance of cryptic life forms. This research has made it clear that we are a very long way, centuries perhaps, from comprehending biodiversity properly.

Revelation of the human microbiome, the teeming trillions of bacteria and archaea in our guts that affect every aspect of our wellbeing, is the best publicized part of the inquiry. We are walking ecosystems, farmed by our microbes and dependent upon their metabolic virtuosity. There is much more besides, including the fact that a single cup of seawater contains 100 million cells, which are in turn preyed upon by billions of viruses; that a pinch of soil teems with incomprehensibly rich populations of cells; and that 50 megatons of fungal spores are released into our air supply every year. Even the pond in my Ohio garden is filled with unknowable riches: the most powerful techniques illuminate the genetic identity of only one in one billion of the cells in its shallow water.

Most biologists continue to be concerned with animals and plants, the thinnest slivers of biological splendor, and students are taught this macrobiology—with the occasional nod toward the other things that constitute almost all of life. Practical problems abound from this nepotism. Ecologists study things muscled and things leafed and conservationists worry most about animals, arguing for expensive stamp-collecting exercises to register the big bits of creation before they go extinct. This is a predicament of considerable importance to humanity. Consider: A single kind of photosynthetic bacterium absorbs 20 billion tons of carbon per year, making this minuscule cell a stronger refrigerant than all of the tropical rainforests.

Surveying our planet for its evolutionary resources, the perceptive extraterrestrial would report that Earth is swarming with viral and bacterial genes. The visitor might comment, in passing, that a few of these genes have been strung together into large assemblies capable of running around or branching toward the sunlight. It is time for us to embrace this kind of objectivity and recognize that the macrobiological bias that drives our exploration and teaching of biology is no more sensible than attempting to evaluate all of English Literature by reading nothing but a Harry Potter book. The science of biology would benefit from a philosophical reboot.

Nicholas P. Money is Professor of Botany and Western Program Director at Miami University in Oxford, Ohio. He is the author of more than 70 peer-reviewed papers on fungal biology and has authored several books. His new book is The Amoeba in the Room: Lives of the Microbes.

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Image Credit: Scanning electron micrograph of amoeba, computer-coloured mauve. By David Gregory & Debbie Marshall, CC-BY-NC-ND 4.0, via Wellcome Images.

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By William Firshein

It is almost impossible to read a daily newspaper or listen to news reports from television and radio without hearing about an outbreak of an infectious disease. On 13 March 2014, the New York City Department of Health investigated a measles outbreak. Sixteen cases including nine pediatric cases were detected, probably caused by a failure to vaccinate the victims. On 12 February, an outbreak of a common microbial pathogen known as C.difficile occurred in several hospitals in Great Britain. This pathogen induces severe cases of gastrointestinal distress including diarrhea, fever, and stomach cramps. One of the main problems with a number of microbial pathogens like C.difficile is that they have become completely resistant to many known drugs.

How did this occur? Antibiotics, complex substances produced by certain types of microbes that destroy other microbes, were hailed as miracle drugs when the first one (penicillin) was discovered more than 70 years ago by Alexander Flemming. Although over 70 useful antibiotics have been discovered since penicillin, many can no longer be used because microbial pathogens have become resistant to them through evolution. In fact, over two million people in the United States become infected with antibiotic resistant pathogens every year, leading to 23,000 deaths according to the Centers for Disease Control and Prevention (CDC). New non-antibiotic drugs are always being sought to treat infectious diseases (mostly microbial because viral diseases are not susceptible to antibiotics). One such new discovery is a commonly used pain medication called Carprofen which inhibits antibiotic resistant pathogens. Thus, the “war against” infectious diseases remains an ongoing focus of medical research.

Of course there are many other pathogens (both microbial and viral) besides those mentioned above that assault us and our body defenses constantly. They include pneumonia, dysentery, tuberculosis, tetanus, diphtheria, scarlet fever, ulcers, typhoid, meningitis, plague, cholera (bacterial), polio, HIV (AIDS), rabies, influenza, measles, mumps, the common cold, yellow fever, and chicken pox (viral). Nevertheless, all of us are not equally “susceptible” to each infectious disease — a poorly understood term that determines why some of us get one disease but not another, or why some diseases occur in the winter while others occur in the summer.

This brings us to an important concept, namely, that there is no way to be free of microbes that inhabit every “nook and cranny” of our bodies. Of the approximately ten million cells that make up the human body, there are billions of microbes that come along with them. Most microbes that inhabit our bodies are necessary for our existence. Together they make up what is called the “microbiome” consisting of a diverse group of microbes that help keep each of us healthy. Most of them are found in the gastrointestinal tract where they aid digestion; synthesize vitamins and other necessary biochemicals our cells cannot make; attack and destroy pathogens; and stimulate our immune system to act in the same way.

Nevertheless, with this constant assault, one might wonder how it is possible we have survived for so long. There are a number of other variables besides the “microbiome’ that are responsible and that are still poorly understood. These include an ability of a host (us) to coexist with a pathogen (we keep them at bay or limit their spread internally like tuberculosis), an ability to mount a furious immunological attack on the pathogen to destroy them, or an innate ability to remain “healthy” (a vague term that really signifies the fact that all of our metabolic systems are operating optimally most of the time like digestion, excretion, blood circulation, neurological or brain function, and healthy gums and teeth among other systems).

Where does this innate ability come from? Simply put, genetic phenomena (both in microbes and in humans). These traits are not only inherited under the control of genes but their functions are also controlled by such genes. Different pathogens have different sets of genes which act to produce a specific disease in a susceptible host. However, it is also why individual hosts (humans) are more or less resistant to such infectious diseases.

How does the body interact with these “foreign” entities? The immune system must protect the body from attack by pathogens and also from the formation of abnormal cells which could turn cancerous. Two types of immune responses exist. One is under the control of antibodies (proteins which circulate in the blood stream) that resist and inactivate invading pathogens by binding to them. The other is mediated by a certain type of white blood cell called a lymphocyte that destroys abnormal (potentially cancerous) cells and viral infected cells. Together, with other white blood cells, they present a formidable defense against infection and abnormality.

It takes time for an immune response by antibodies to develop during a pathogenic invasion because there are many components involved in the activity. They are usually divided into primary and secondary responses. The primary response represents the first contact with the antigen which after a period of time results in an increased production of specific antibodies that react only to that antigen (which by the way are also produced by certain lymphocytes called “B” or plasma cells). Once the infection is controlled, antibody levels fall considerably. If, however, another infection occurs in the future by the same pathogen, a much more vigorous response will result (called the secondary response) producing a much faster development and a higher level of antibodies. Why is the secondary response so much faster and vigorous? This phenomenon is due to a remarkable property of the immune system in which the primary response is “remembered” after its decrease by the preservation of “memory” “B” lymphocytes that circulate until the secondary response occurs, no matter how long it takes.

William Firshein is the Daniel Ayers Professor of Biology, Emeritus and author of The Infectious Microbe. He chaired the Biology Department at Wesleyan University for six years and published over 75 original research papers in the field of Molecular Microbiology of Pathogens. He was the recipient of several million dollars of grant support from various public and private research agencies and taught over 6,000 graduate and undergraduate students during his 48 year career.

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Dorothy H. Crawford is a Professor of Medical Microbiology and Assistant Principle for the Public Understanding of Medicine at the University of Edinburgh. Her most recent book, Deadly Companions: How Microbes Shaped Our History, takes us back in time to follow the interlinked history of microbes and man, impressing upon us how a world free of dangerous microbes is an illusion.  In an excerpt this morning we looked at SARS.  The excerpt below looks at the effect of poverty on disease.

It is glaringly obvious from a glance at the figures that poverty is the major cause of microbe-related deaths. On a worldwide scale microbes are still major killers, accounting for one in three of all deaths. But the huge discrepancy in the death rates between rich and poor nations reveals the stark reality. Whereas only 1–2 per cent of all deaths in the West are caused by microbes, this figure rises to over 50 per cent in the poorest nations of the world, and it is in these highly microbe-infected areas where over 95 per cent of the global deaths from infections occur. Most of the 17 million killed by microbes each year are children in developing countries where the link with poverty is clear. It is the poor who are malnourished, live in filthy, overcrowded urban slums and go without clean drinking water or sewage disposal, and therefore they are the ones who fall prey to the killer microbes: HIV, malaria, TB, respiratory infections and diarrhea diseases like cholera, typhoid and rotavirus; all eminently preventable and treatable given the resources.

The spread of HIV is an excellent example of how microbes exploit the poor, striking at the most disadvantaged in the community. The virus emerged in Central Africa and spread silently throughout the continent in the 1970s, given a head start by its long silent incubation period, and aided by despotic leaders, corrupt governments, civil wars, tribal conflicts, droughts and famines. Carried by undisciplined armies and terrorists, the virus infiltrated city slums, infected commercial sex workers, was picked up by migrant workers and passed on to their wives and families. While malnutrition accelerated the onset of AIDs, breakdown of health-care services in the political turmoil of Africa excluded any possibility of medical support for the millions in need.

Now we are living through the worst pandemic the world has ever known, with 40 million living with HIV, 25 million already dead and around 10,000 dying daily—the equivalent of over three 9/11disasters every twenty-four hours. A third of people living in sub-Saharan African cities are HIV-infected, and while highly active antiretroviral therapy (HAART) has converted this lethal disease into a manageable chronic infection in the West, presently only a tiny proportion of Africans living with HIV receive this treatment; for most there is no hope of obtaining the drugs vital for keeping them alive.

The dynamics of HIV in Africa reflects its mode of spread. As the virus is sexually transmitted gender inequalities mean that women are particularly vulnerable. In general they are poorer and less well educated than their male counterparts, and are often powerless to choose or restrict their sexual partners, or to insist on condom use. Indeed many are forced to exchange sex for essentials like food, shelter and schooling. Now one in four African women are HIV-infected by the age of twenty-two years (compared to one in fourteen men of the same age), and women account for 60 per cent of all those living with HIV.

Over 90 per cent of HIV-positive women in Africa are mothers, and the virus has created 15 million orphans worldwide, 12 million of them in sub-Saharan Africa. These children are bearing the burden of the HIV pandemic; they miss school to care for their sick mothers or to earn the family income; the virus has not only deprived them of their parents but their childhood and their education as well.

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Este año, mi Santa cambió de horizonte, como nosotros mismos.
Que tengan una hermosa Navidad y se cumplan todos los deseos!

This year, my Santa has a new horizon, like ourselves.
I wish you a Merry Christmas and hope your dreams will come true!

La red tiene su magia. Una muy especial. Una que no deja de sorprerme, de alegrarme, de llenarme de afectos de gente que de otra manera probablemente nunca hubiera encontrado.

Es a través de ella que hace poco conocí a Zime y a su hermosa familia, a mi querida amiga y excelente escritora La Spectatrice , así como al creativo Willie y a la querible Tanya cuando pasaron por Buenos Aires.

La red me regaló nuevos amigos en todo el mundo. Amigos a quienes deseo recordar especialmente estas fiestas. A quienes están o estuvieron por aquí, muchas gracias por tanto cariño y apoyo!

Zime me dejó varios mensajitos en el blog. Algunos decían: "cuando estés en Bs.As., si querés, chiflá!". Chiflé. Y qué buena idea fue hacerlo!

Con Ximena nos conocimos virtualmente a través de IF. Hace ya tres días -pido disculpas por el tardío post- compartimos un refresco y una soleada tarde porteña. Sorpresas y temores iniciales pasaron rapidito. Fue como si siempre hubiéramos sido amigas, vecinas, compañeras de trabajo o de estudio. Ella es una joven diseñadora e ilustradora argentina. Es muy creativa, alegre y últimamente tiene el blog lleno de pajaritos -como verán, alguno de ellos se escapó al mío!

Espacios nuevos que acercan a almitas gemelas disperas por el mundo. Como diría Pati, muy chévere!

Gracias a todos ustedes por compartir tantos momentos. Y que sean muchos más!