Posts about life

Virgin Birth for Another Shark Species

Virgin shark birth in Virginia

The first time it happened, scientists thought it might be a fluke. A female hammerhead shark residing at a zoo in Omaha, Neb., had not been in contact with male sharks for at least three years and yet experienced a “virgin birth.” She delivered a single pup.

But it has happened again, according to today’s issue of the Journal of Fish Biology. This time, a blacktip shark… had spent nearly her entire eight years at either the Virginia Aquarium without any male companionship from her kind.

Related: No sex for all-girl fish speciesBdelloid Rotifers Abandoned Sex 100 Million Years Agoposts on the science and life

Foreign Cells Outnumber Human Cells in Our Bodies

This is one of those area I find very interesting: People Have More Bacterial Cells than Human Cells. Colin Nickerson has written an interesting article on the topic: Of microbes and men

Scientists estimate that 90 percent of the cells contained in the human body belong to nonhuman organisms – mostly bacteria, but also a smattering of fungi and other eensy entities. Some 100 trillion microbes nestle in niches from our teeth to our toes.

But what’s setting science on its heels these days is not the boggling numbers of bugs so much as the budding recognition that they are much more than casual hitchhikers capable of causing disease. They may be so essential to well-being that humans couldn’t live without them.

In this emerging view, humans and their microbes – or, as some biologists playfully put it, microbes and their attached humans – have evolved together to form an extraordinarily complex ecosystem.

The understanding of the complex interaction is something I came to through reading on the overuse of antibiotics. And the more I read the more interesting it gets.

“We can’t take nutrition properly without bacteria. We can’t fight bad germs without good germs,” he said. “It may turn out that secretions from bacteria affect not only long-term health, but hour-by-hour moods – could a person’s happiness depend on his or her bugs? It’s possible. Our existences are so incredibly intertwined.”

However, in the opinion of some researchers, this strange union may be headed for trouble because of profligate use of antibiotics and antiseptic lifestyles that deter the transfer of vital strains of bacteria that have swarmed in our systems at least since early humans ventured out of Africa.

Related: Tracking the Ecosystem Within UsSkin BacteriaMove over MRSA, C.diff is HereCats Control Rats … With ParasitesBeneficial Bacteria

Viruses and What is Life

Viruses are generally considered not to be alive (they must use a host cell of something else to reproduce). However, defining exactly what life is, is not as easy as you might think.

The debate about what counts as a living thing is fuelled today by the discovery of the first virus that is able to fall “ill” by being infected with another virus.

the discovery of a giant virus that itself falls ill through infection by another virus seems to suggest they too are alive, highlighting how there is no watertight definition of what exactly scientists mean when they refer to something as “living”.

“There’s no doubt, this is a living organism,” the journal Nature is told by Prof Jean-Michel Claverie, director of the Mediterranean Institute of Microbiology in Marseilles, part of France’s basic-research agency CNRS. “The fact that it can get sick makes it more alive.”

Related: People Have More Bacterial Cells than Human CellsBacteria Feed on Earth’s Ocean-Bottom CrustRetrovirusesBacteriophages: The Most Common Life-Like Form on Earth

Life After the Chernobyl Nuclear Accident

Silent Spring by Lauren Monaghan, Cosmos

Ever since, a 30 km ‘exclusion zone’ has existed around the contaminated site, accessible to those with special clearance only. It’s quite easy, then, to conjure an apocalyptic vision of the area; to imagine an eerily deserted wasteland, utterly devoid of life.

But the truth is quite the opposite. The exclusion zone is teeming with wildlife of all shapes and sizes, flourishing unhindered by human interference and seemingly unfazed by the ever-present radiation. Most remarkable, however, is not the life buzzing around the site, but what’s blooming inside the perilous depths of the reactor.

Sitting at the centre of the exclusion zone, the damaged reactor unit is encased in a steel and cement sarcophagus. It’s a deathly tomb that plays host to about 200 tonnes of melted radioactive fuel, and is swarming with radioactive dust.

But it’s also the abode of some very hardy fungi which researchers believe aren’t just tolerating the severe radiation, but actually harnessing its energy to thrive.

“Our findings suggest that [the fungi] can capture the energy from radiation and transform it into other forms of energy that can be used for growth,” said microbiologist Arturo Casadevall from the Albert Einstein College of Medicine at Yeshiva University in New York, USA.

Taken together, the researchers think their results do indeed hint that fungi can live off ionising radiation, harnessing its energy through melanin to somehow generate a new form of biologically usable growing power.

If they’re right, then this is powerful stuff, said fungal biologist Dee Carter from the University of Sydney. The results will challenge fundamental assumptions we have about the very nature of fungi, she said.

It also raises the possibility that fungi might be using melanin to secretly harvest visible and ultraviolet light for growth, adds Casadevall. If confirmed, this will further complicate our understanding of these sneaky organisms and their role in ecosystems.

Pretty amazing stuff. It really is great all that nature gives us to study and learn about using science.

Related: Radiation Tolerant BacteriaNot Too Toxic for LifeBacterium Living with High Level RadiationWhat is an Extremophile?

Bacteria “Feed” on Earth’s Ocean-Bottom Crust

Bacteria “Feed” on Earth’s Ocean-Bottom Crust

Once considered a barren plain dotted with hydrothermal vents, the seafloor’s rocky regions appear to be teeming with microbial life, say scientists

“Initial research predicted that life could in fact exist in such a cold, dark, rocky environment,” said Santelli. “But we really didn’t expect to find it thriving at the levels we observed.” Surprised by this diversity, the scientists tested more than one site and arrived at consistent results, making it likely, according to Santelli and Edwards, that rich microbial life extends across the ocean floor. “This may represent the largest surface area on Earth for microbes to colonize,” said Edwards.

Santelli and Edwards also found that the higher microbial diversity on ocean-bottom rocks compared favorably with other life-rich places in the oceans, such as hydrothermal vents. These findings raise the question of where these bacteria find their energy, Santelli said.

“We scratched our heads about what was supporting this high level of growth,” Edwards said. With evidence that the oceanic crust supports more bacteria than overlying water, the scientists hypothesized that reactions with the rocks themselves might offer fuel for life.

Why doesn’t this stuff make the news over what some celebrity did or politician said… (well I must admit I am just guessing since I don’t actually watch the news or read the mass media much – other than some science, investing or economics content). Oh well, at least you get to read the Curious Cat Science blog and find out about some of the cool stuff being learned every day.

Related: Life Far Beneath the OceanClouds Alive With BacteriaBacterium Living with High Level RadiationGiant Star Fish and More in Antarctica

Parasite Rex

Parasite Rex is a great book by Carl Zimmer (one of the bloggers listed in the Curious Cat directory of science blogs). This is the first book read as part of my specific plan to read more about bacteria, cells, virus, genes and the like.

One of the most enjoyable aspects of writing this blog is that I have focused much more on cool things I read. And over time the amazing things I posted about related to these topics made me realize I should put some focused effort to reading more on these topics. Some of the posts that sparked that idea: Tracking the Ecosystem Within UsInner Life of a Cell: Full VersionWhere Bacteria Get Their Genes, People Have More Bacterial Cells than Human Cells, Biological Molecular MotorsEnergy Efficiency of DigestionOld Viruses Resurrected Through DNAMidichloria mitochondriiMicrobesUsing Bacteria to Carry Nanoparticles Into CellsHow Bacteria Nearly Destroyed All LifeNew Understanding of Human DNASoil Could Shed Light on Antibiotic ResistanceSymbiotic relationship between ants and bacteria

Parasite Rex was a great place to start. Carl Zimmer is a great writer, and the details on how many parasites there are and how interconnected those parasites are to living systems and how that has affected, and is affecting, us is amazing. And the next book I am reading is also fantastic: Good Germs, Bad Germs. Here is one small example from Parasite Rex, page 196-7:

A person who dies of sickle cell anemia is less likely to pass on the defective gene, and that means the disease should be exceedingly rare. But it’s not – one in four hundred American blacks has sickle sell anemia, and one in ten carries a single copy of the defective gene. The only reason the gene stays in such high circulation is that is also happens to be a defense against malaria.

Malaria is a parasite. One of the amazing things with repeated examples in the book were parasites that seemed to have extremely complicated life cycles (that don’t seem like a great strategy to prosper but obviously work). Where they grow in one life form (an insect or mammal or whatever) but must leave that life form for some other specific life form for the next stage in life (they cannot have descendants without doing so…). Seems like a crazy way to evolve but it happens over and over again.
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People Have More Bacterial Cells than Human Cells

Humans Carry More Bacterial Cells than Human Ones

All the bacteria living inside you would fill a half-gallon jug; there are 10 times more bacterial cells in your body than human cells

The infestation begins at birth: Babies ingest mouthfuls of bacteria during birthing and pick up plenty more from their mother’s skin and milk—during breast-feeding, the mammary glands become colonized with bacteria. “Our interaction with our mother is the biggest burst of microbes that we get,”

there are estimated to be more than 500 species living at any one time in an adult intestine, the majority belong to two phyla, the Firmicutes (which include Streptococcus, Clostridium and Staphylococcus), and the Bacteroidetes (which include Flavobacterium).

probiotics – dietary supplements containing potentially beneficial microbes – have been shown to boost immunity. Not only do gut bacteria “help protect against other disease-causing bacteria that might come from your food and water,” Huffnagle says, “they truly represent another arm of the immune system.”

But the bacterial body has made another contribution to our humanity – genes. Soon after the Human Genome Project published its preliminary results in 2001, a group of scientists announced that a handful of human genes – the consensus today is around 40 – appear to be bacterial in origin.

How cool is science? Very, I think 🙂

Related: Tracking the Ecosystem Within UsBeneficial BacteriaEnergy Efficiency of DigestionLarge Number of Bacteria on our SkinWhere Bacteria Get Their GenesAmazing Science: Retroviruses

Tracking the Ecosystem Within Us

Gut Check: Tracking the Ecosystem Within Us

For more than 100 years, scientists have known that humans carry a rich ecosystem within their intestines. An astonishing number and variety of microbes, including as many as 400 species of bacteria, help humans digest food, mitigate disease, regulate fat storage, and even promote the formation of blood vessels. By applying sophisticated genetic analysis to samples of a year’s worth baby poop, Howard Hughes Medical Institute researchers have now developed a detailed picture of how these bacteria come and go in the intestinal tract during a child’s first year of life.

Before birth, the human intestinal tract is sterile, but babies immediately begin to acquire the microbial denizens of the gut from their environment — the birth canal, mothers’ breast, and even the touch of a sibling or parent. Within days, a thriving microbial community is established and by adulthood, the human body typically has as many as ten times more microbial cells than human cells.

The results, said Palmer, were striking: the group found that the intestinal microbial communities varied widely from baby to baby – both in terms of which microbes were present and in how that composition changed over time. That finding, she said, is important because it helps broaden the definition of healthy microbial colonization in a baby.

Another intriguing observation, Palmer noted, was a tendency for sudden shifts in the composition of the infants’ intestinal microbial communities over time as different species of bacteria ebbed and flowed.

I find this area and this study fascinating. I’m not exactly sure why this study and the incredibly significant positive bacteria for human life news doesn’t get more notice. Oh well I guess there are not cool pictures of robots or scary stories of potential threats to those reading which makes the news less interesting to some. Still I find this stuff amazing: Energy Efficiency of DigestionBeneficial BacteriaSkin BacteriaHacking Your Body’s Bacteria for Better HealthWhere Bacteria Get Their Genes