Enlarge / Orange amphipods caught the eye (and interest) of Brown University graduate students conducting field research. (credit: David Johnson)

Scour the salt marshes of Plum Island Estuary in Massachusetts and you're likely to spot bright orange shrimp lurking among the vegetation and detritus. That unusual hue is a sign that a shrimp has been infected with a parasitic worm, which also seems to affect the shrimp's behavior. Infected shrimp typically become sluggish and spend more time exposed in the open marsh, easy pickings for hungry birds. Now biologists at Brown University have sequenced the DNA of these shrimp to hone in on the molecular mechanisms behind the changes, according to a recent paper published in the journal Molecular Ecology.

“This may be an example of a parasite manipulating an intermediate host to ensure its own transmission between hosts,” said co-author David Rand of Brown University, drawing an analogy to how malaria spreads to humans via the intermediary of mosquito bites. “Rabies could be another relevant example: it drives infected individuals ‘mad’ so they bite others and infect the next host. Learning the molecular mechanisms of these kinds of host-parasite interactions can have important implications for how to manage pathogens generally, and in humans.”

Parasites that control and alter the behavior of their hosts are well-known in nature. Most notably, there is a family of zombifying parasitic fungi called Cordyceps —more than 400 different species , each targeting a particular insect species, whether it be ants, dragonflies, cockroaches, aphids, or beetles. In fact, The Last of Us game co-creator Neil Druckmann has said the premise was partly inspired by an episode of the BBC nature documentary Planet Earth (narrated by Sir David Attenborough) portraying the "zombification" of an ant in vivid detail . Scientists are keen to study Cordyceps to learn more about the origins and intricate mechanisms behind these kinds of pathogen-based diseases.

Enlarge / Portrait of Beethoven by Joseph Karl Stieler, 1820 (credit: Beethoven-Haus Bonn)

Ludwig van Beethoven is one of the greatest composers of all time, but he was plagued throughout his life by myriad health problems, most notably going mostly deaf by 1818. These issues certainly affected his career and emotional state, so much so that Beethoven requested— via a letter addressed to his brothers—that his favorite physician examine his body after his death to determine the cause of all his suffering.

Nearly two centuries after the composer's demise, scientists say they have sequenced his genome based on preserved locks of hair. While the analysis of that genome failed to pinpoint a definitive cause of Beethoven's hearing loss or chronic digestive problems, he did have numerous risk factors for liver disease and was infected with hepatitis B, according to a new paper published in the journal Current Biology. The researchers also found genetic evidence that somewhere in the Beethoven paternal line, an ancestor had an extramarital affair.

“We cannot say definitely what killed Beethoven, but we can now at least confirm the presence of significant heritable risk and an infection with hepatitis B virus,” said co-author Johannes Krause , an expert in ancient DNA at the Max Planck Institute of Evolutionary Anthropology. “We can also eliminate several other less plausible genetic causes.” The fully sequenced genome will be made publicly available so other researchers can have access to conduct future studies.

Enlarge (credit: National Academies of Science )

With the advent of genomic studies, it's become ever more clear that humanity's genetic history is one of churn. Populations migrated, intermingled, and fragmented wherever they went, leaving us with a tangled genetic legacy that we often struggle to understand. The environment—in the form of disease, diet, and technology—also played a critical role in shaping populations.

But this understanding is frequently at odds with the popular understanding, which often views genetics as a determinative factor and, far too often, interprets genetics in terms of race . Worse still, even though race cannot be defined or quantified scientifically, popular thinking creeps back into scientific thought, shaping the sort of research we do and how we interpret the results.

Those are some of the conclusions of a new report produced by the National Academies of Science. Done at the request of the National Institutes of Health (NIH), the report calls for scientists and the agencies that fund them to stop thinking of genetics in terms of race, and instead to focus on things that can be determined scientifically.

Enlarge / Coronaviruses (credit: Getty | BSIP )

Ever since the novel coronavirus, SARS-CoV-2, began jumping from human to human, it’s been mutating. The molecular machinery the virus uses to read and make copies of its genetic code isn’t great at proofreading; minor typos made in the copying process can go uncorrected. Each time the virus lands in a new human victim, it infects a cell and makes an army of clones, some carrying genetic errors. Those error-bearing clones then continue on, infecting more cells, more people. Each cycle, each infection offers more opportunity for errors. And, over time, those errors, those mutations, accumulate.

Some of these changes are meaningless. Some are lost in the frenetic viral manufacturing. But some become permanent fixtures, passed on from virus to virus, human to human. Maybe it happens by chance; maybe it’s because the change helps the virus survive in some small way. But in aggregate, viral strains carrying one notable mutation can start carrying others. Collections of notable mutations start popping up in viral lineages, and sometimes they seem to have an edge over their relatives. That’s when these distinct viruses—these variants—get concerning.

Scientists around the world have been closely tracking mutations and variants since the pandemic began, watching some rise and fall without much ado. But in recent months, they have become disquieted by at least three variants. These variants of concern, or VOCs, have raised critical questions—and alarm—over whether they can spread more easily than previous viral varieties, whether they can evade therapies and vaccines, or even whether they’re deadlier.

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Enlarge / Researchers have looked at whether there are genetic influences on who experiences a case of severe COVID-19. (credit: ALBERTO PIZZOLI / Getty Images )

The body's response to SARS-CoV-2 infection range from imperceptible to death, raising an obvious question: what makes the difference? If we could identify the factors that make COVID-19 so dangerous for some people, we could do our best to address these factors, and provide extra protections for those who are at highest risk. But aside from the obvious&dmash;health disparities associated with poverty and race seem to be at play here, too—we've had trouble identifying the factors that make a difference.

A recently published study takes a look at one potential influence: genetics. In a large study of UK COVID-19 patients, researchers have found a number of genes that appear to be associated with severe cases, most of them involved in immune function. But the results don't clarify how immune function is linked to the disease's progression.

All in the genes

The work took place in the UK, one of the countries involved in the GenOMICC ( Genetics Of Mortality In Critical Care ) project, which has already been exploring the genetics underlying hospitalization for communicable diseases. For the new study, the researchers worked with over 200 intensive care units in the UK to identify study participants. All told, they managed to get genetic data for over 2,700 critical COVID-19 patients. These were matched with people in the UK's Biobank who had similar demographics in order to provide a control population. The one weakness of this design is that some people in the Biobank may be susceptible to severe COVID-19 but simply haven't been infected yet, which would tend to weaken any genetic signals.

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