Category Archives: Life Science

Cancer Rates Consistent Across Species Instead of Increasing Due to Body Mass

It would seem sensible to think cancer should be more prevalent in species with a huge number of cells, and thus more cells to become cancerous. But cancer risk doesn’t increase in this way. This interesting, open source paper, sheds some light on what is behind this.

Solutions to Peto’s paradox revealed by mathematical modelling and cross-species cancer gene analysis

Whales have 1000-fold more cells than humans and mice have 1000-fold fewer; however, cancer risk across species does not increase with the number of somatic cells and the lifespan of the organism. This observation is known as Peto’s paradox. How much would evolution have to change the parameters of somatic evolution in order to equalize the cancer risk between species that differ by orders of magnitude in size? Analysis of previously published models of colorectal cancer suggests that a two- to three-fold decrease in the mutation rate or stem cell division rate is enough to reduce a whale’s cancer risk to that of a human. Similarly, the addition of one to two required tumour-suppressor gene mutations would also be sufficient.

We surveyed mammalian genomes and did not find a positive correlation of tumour-suppressor genes with increasing body mass and longevity. However, we found evidence of the amplification of TP53 in elephants, MAL in horses and FBXO31 in microbats, which might explain Peto’s paradox in those species. Exploring parameters that evolution may have fine-tuned in large, long-lived organisms will help guide future experiments to reveal the underlying biology responsible for Peto’s paradox and guide cancer prevention in humans.

Elephants in Kenya by John Hunter. See more photos from my trip to Kenya.

In another way it would make sense that large animals would have hugely increased risks of cancer. As they evolved, extremely high cancer rates would be a much bigger problem for them. Therefore it wouldn’t be surprising to find they have evolved a way of reducing cancer risks.

Despite these limitations, we found genes that have been dramatically amplified in specific mammalian genomes, the most interesting of which is the discovery of 12 TP53 copies in the genome of the African elephant. We subsequently cloned those genes and identified 19 distinct copies of TP53 in African elephants and 15–20 in Asian elephants [1]. Another potential lead for solving Peto’s paradox is MAL, which is found to have eight copies in the horse genome and two in microbat. This could be an example of convergent evolution where a large animal (horse) and a small, long-lived animal (microbat) both evolved extra copies of the same gene to overcome their increased risk of cancer. Further analysis and experimentation would need to be performed to determine the function of these copies and whether or not they provide enhanced suppression of carcinogenesis.

The researchers have found an interesting potential explanation for how that has been accomplished.

In Many Crops Ants Can Provide Pest Protection Superior or Equal to Chemicals at a Much Lower Cost

Ants are as Effective as pesticides

The review [of over 70 studies] was conducted by Aarhus University’s Dr Joachim Offenberg, an ecologist who has studied ants for almost 20 years. It includes studies of more than 50 pest species on nine crops across eight countries in Africa, South-East Asia and Australia.

Most of the studies in Offenberg’s review are on weaver ants (Oecophylla), a tropical species which lives in trees and weaves ball-shaped nests from leaves. Because weaver ants live in their host trees’ canopy, near the flowers and fruit that need protection from pests, they are good pest controllers in tropical orchards.

All farmers need to do is collect ant nests from the wild, hang them in plastic bags among their tree crops and feed them a sugar solution while they build their new nests. Once a colony is established, farmers then connect the trees that are part of the colony with aerial ‘ant walkways’ made from string or lianas.

After that, the ants need little, except for some water in the dry season (which can be provided by hanging old plastic bottles among the trees), pruning trees that belong to different colonies so that the ants do not fight, and avoiding insecticide sprays.

The review shows that crops such as cashew and mango can be exceptionally well protected from pests by weaver ants.

One three-year study in Australia recorded cashew yields 49% higher in plots patrolled by ants compared with those protected by chemicals. Nut quality was higher too, so net income was 71% higher with ants than with chemicals.

Similar studies in Australian mango crops found that ants could produce the same yield as chemical control, but because the ants were cheaper, and fruit quality better, net income from mangoes produced with ant protection was 73% higher.

Those crops are special cases in which the ants are vastly superior. But in many other cases ants are as effective and much cheaper than chemical options. Different species of ants are suited to protecting different types of drops. Weaver ants require a canopy, other ants can protect crops without a canopy.

I hope more farmers adopt ants to help protect their crop yields.

Exercise Is Really Really Good for You

Nice webcast that reviews the benefits of exercise that are confirmed by medical studies.

Other than [not] smoking there are few modifiable risk factors that seem to have the huge impact on heath activity does…

150 minutes a week of moderate (walking briskly, biking, even mowing the lawn maybe) activity (30 minutes a day 5 days a week) is a decent target for a minimum amount of activity for most people. I have not bought a car since my move (2 months ago) and walk to the grocery store, library, bank, subway, restaurants which is easily 30 minutes and usually more each trip. And for further away places I am biking.

Another option is 25 minutes of vigorous activity 3 times a week and 2 days a week of weight training. Basketball is my favorite form of vigorous activity and sometimes my biking and yard work reach that mark. I like swimming (and I did swim a fair amount when I had a pool at my condo but I don’t swim now as it isn’t right downstairs from my bedroom). I like vigorous activity as I end up feeling refreshed and it serves as a noticeable form of stress release for me.

Chimpanzees Use Spears to Hunt Bush Babies

Video replaced with new one because original was removed 🙁

Savanna Chimpanzees, Pan troglodytes verus, Hunt with Tools by Jill D. Pruetz and Paco Bertolani

Although tool use is known to occur in species ranging from naked mole rats to owls, chimpanzees are the most accomplished tool users. The modification and use of tools during hunting, however, is still considered to be a uniquely human trait among primates. Here, we report the first account of habitual tool use during vertebrate hunting by nonhumans. At the Fongoli site in Senegal, we observed ten different chimpanzees use tools to hunt prosimian prey in 22 bouts. This includes immature chimpanzees and females, members of age-sex classes not normally characterized by extensive hunting behavior. Chimpanzees made 26 different tools, and we were able to recover and analyze 12 of these.

Tool construction entailed up to five steps, including trimming the tool tip to a point. Tools were used in the manner of a spear, rather than a probe or rousing tool. This new information on chimpanzee tool use has important implications for the evolution of tool use and construction for hunting in the earliest hominids, especially given our observations that females and immature chimpanzees exhibited this behavior more frequently than adult males.

The full paper, from 2007, was available as a pdf when I visited (I don’t really trust these publishers and what articles by professors they will block access to later when they don’t clearly say it is open access – in fact the journal broke the link on the post I made about this in 2007 now that I checked – sigh).

The full paper isn’t filled with overly complex scientific jargon (as scientific papers can be). In that sense it is an easy read; it is a bit graphic for those that are squeamish.

Dr. Jill Pruetz maintains an interesting blog the Chimpanzees she studies: Fongoli Savanna Chimpanzee Project

Scientific Inquiry Leads to Using Fluoride for Healthy Teeth

This webcast, from the wonderful SciShow, explores how we discovered fluoride helps prevent tooth decay and how we then used that knowledge and finally discovered why it worked.

I love stories of how we learn for observing what is happening. We don’t always need to innovate by thinking up creative new ideas. If we are observant we can pick up anomalies and then examine the situation to find possible explanations and then experiment to see if those explanations prove true.

When working this way we often are seeing correlation and then trying to figure out which part of the correlation is an actual cause. So in this dental example, a dentist noticed his patients had bad brown stains on their teeth than others populations did.

After investigation the natural fluoridation of the water in Colorado Springs, Colorado, USA seemed like it might be an explanation (though they didn’t understand the chemistry that would cause that result). They also explored the sense that the discolored teeth were resistant to decay.

Even without knowing why it is possible to test if the conditions are the cause. Scientists discovered by reducing the level of fluoridation in the water the ugly brown stains could be eliminated (these stains took a long time to develop and didn’t develop in adults). Eventually scientists ran an experiment in Grand Rapids, Michigan and found fluoridation of the water achieved amazing results for dental health. The practice of fluoridation was then adopted widely and resulted in greatly improved dental health.

In 1901, Frederick McKay, a recent dental school graduate, opened a dental practice in Colorado Springs, Colorado. He was interested in what he saw and sought out other dentists to explore the situation with him but had little success. In 1909, he found some success when renowned dental researcher Dr. G.V. Black collaborate with him.
Dr. H. Trendley Dean, head of the Dental Hygiene Unit at the National Institute of Health built on their work when he began investigating the epidemiology of fluorosis in 1931. It wasn’t until 1945 that the Grand Rapids test started. Science can take a long time to move forward.

Only later did scientists unravel why this worked. The fluoride reacts to create a stronger enamel than if the fluoride is not present. Which results in the enamal being less easily dissolved by bacteria.
Health tip: use a dental stimudent (dental picks) or floss your teeth to maintain healthy gums and prevent tooth decay. It makes a big difference.

We Have Thousands of Viruses In Us All the Time

Biology and the amazing interactions within a human body are amazing. Our bodies are teeming with other life (and almost life – viruses). All these microbes have a drastic impact on our health and those impacts are not always bad.

A Virus In Your Mouth Helps Fight The Flu

Hidden inside all of us are likely thousands of viruses — maybe more. They just hang out, harmlessly. We don’t even know they’re there.

But every once in a while, one of these viral inhabitants might help us out.

Young people infected with a type of herpes virus have a better immune response to the flu vaccine than those not infected, scientists at Stanford University report Wednesday. In mice, the virus directly stops influenza itself.
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We’re talking about a ubiquitous critter, called cytomegalovirus. About half of all Americans carry it. And so do nearly 100 percent of people in developing countries.
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In younger people, CMV had the opposite effect that Davis had predicted: “The virus ramped up the immune system to give better protection from pathogens,” Mark Davis says. “We tested only for the flu, but I speculate it protects against everything.”

So should we all go out and get infected with CMV? No way! Davis exclaims.

You see, CMV has a dark side. It can become dangerous if the immune system is suppressed, which happens after an organ transplant or during treatments for autoimmune disorders. CMV is also a concern for pregnant woman. It’s the top viral cause of birth defects worldwide.

The human microbiome is incredible and teams with thousands of species (bacteria, viruses, members of domain Archaea, yeasts, single-celled eukaryotes, helminth parasites and bacteriophages). The complexity of interactions between all the elements of what is in our bodies and cells is one of the things that makes health care so challenging. It is also fascinating how these interactions provide benefits and costs as they work within our bodies.

The fact that we have evolved in concert with all these interactions is one of the big problems with anti-biotics. Antibiotics are miraculous when they work, but they can also decimate our natural micro-biomes which does create risks.

I would have thought Stanford wasn’t still supporting closed science 🙁 Sadly this research is not published in an open science manner.

Camera Trap Images of Very Rare Wild Cats

This video show some wonderful images from remote cameras equipped to film when an animal is spotted. These camera have aided scientists in understanding wildlife in their natural environment and also by providing us cool images.

Yacouba Sawadogo – The Man Who Stopped the Desert

Quote from the video

Yacouba single-handedly had more impact on the soil conservation in the Sahel than than all the national and international researchers combined.

Dr. Chris Reij, Vrije University of Amsterdam.

As is normally the case making improvements in the real world is challenging and visionaries often face setbacks. Even when they have success that success is threatened by those that want to take the rewards but ignore the lessons. The clip above is a excerpt from the documentary film on his efforts.

Meet Yacouba Sawadogo – The Man Who Stopped the Desert

The simple old farmer’s re-forestation and soil conservation techniques are so effective they’ve helped turn the tide in the fight against the desertification of the harsh lands in northern Burkina Faso.

Over-farming, over-grazing and over population have, over the years, resulted in heavy soil erosion and drying in this landlocked West African nation.
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Zai is a very simple and low-cost farming technique. Using a shovel or an axe, small holes are dug into the hard ground and filled with compost. Seeds of trees, millet or sorghum are planted in the compost. The holes catch water during the rainy season, so they are able to retain moisture and nutrients during the dry season.

According to the rules of Zai, Yacouba would prepare the lands in the dry season – exactly the opposite of the local practice. Other farmers and land chiefs laughed at him, but soon realized that he is a genius. In just 20 years, he converted a completely barren area into a thriving 30-acre forest with over 60 species of trees.
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Yacouba has chosen not to keep his secrets to himself. Instead, he hosts a workshop at his farm, teaching visitors and bringing people together in a spirit of friendship. “I want the training program to be the starting point for many fruitful exchanges across the region

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Manufacture Biological Sensors Using Silk and Looms

The fabric chip platform from Achira Labs in India uses looms to manufacture biological sensors.

Image of process for creating silk test strips

image by Achira Labs

Yarn coated with appropriate biological reagents like antibodies or enzymes is woven into a piece of fabric at the desired location. Strips of fabric are then cut out, packaged and can form the substrate for dierent biological assays. Even a simple handloom could produce thousands of these sensors at very low cost.

The resulting fabrics can be used to test for pregnancy, diabetes, chronic diseases, etc.. Achira Labs, an Indian start-up, received $100,000 in Canadian funding in 2013 to develop a silk strip that can diagnose rotavirus, a common cause of diarrhea and can be used in diapers.

The company is planing to start selling silk diabetes test strips using there process this year and expects costs to be about 1/3 of the existing test strips using conventional manufacturing processes.

Defying Textbook Science, Study Finds Proteins Built Without DNA Instructions

Open any introductory biology textbook and one of the first things you’ll learn is that our DNA spells out the instructions for making proteins, tiny machines that do much of the work in our body’s cells. Results from a recent study show for the first time that the building blocks of a protein, called amino acids, can be assembled without blueprints – DNA and an intermediate template called messenger RNA (mRNA). A team of researchers has observed a case in which another protein specifies which amino acids are added.

“This surprising discovery reflects how incomplete our understanding of biology is,” says first author Peter Shen, Ph.D., a postdoctoral fellow in biochemistry at the University of Utah. “Nature is capable of more than we realize.”

To put the new finding into perspective, it might help to think of the cell as a well-run factory. Ribosomes are machines on a protein assembly line, linking together amino acids in an order specified by the genetic code. When something goes wrong, the ribosome can stall, and a quality control crew is summoned to the site. To clean up the mess, the ribosome is disassembled, the blueprint is discarded, and the partly made protein is recycled.

Yet this study reveals a surprising role for one member of the quality control team, a protein conserved from yeast to man named Rqc2. Before the incomplete protein is recycled, Rqc2 prompts the ribosomes to add just two amino acids (of a total of 20) – alanine and threonine – over and over, and in any order. Think of an auto assembly line that keeps going despite having lost its instructions. It picks up what it can and slaps it on.

“In this case, we have a protein playing a role similar to that filled by mRNA,” says Adam Frost, M.D., Ph.D., assistant professor at University of California, San Francisco (UCSF) and adjunct professor of biochemistry at the University of Utah. He shares senior authorship with Jonathan Weissman, Ph.D., a Howard Hughes Medical Institute investigator at UCSF, and Onn Brandman, Ph.D., at Stanford University. “I love this story because it blurs the lines of what we thought proteins could do.”

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