Posts about biology

An Eukaryote that Completely Lacks Mitochondria

If you don’t have any idea what the title means that is ok. I probably wouldn’t have until the last 15 years when I found how interesting biology is thanks to the internet and wonderful resources online making biology interesting. I hope you find learning about biology as interesting as I do.

Look, Ma! No Mitochondria

Mitochondria have their own DNA, and scientists believe they were once free-living bacteria that got engulfed by primitive, ancient cells that were evolving to become the complex life forms we know and love today.

What they learned is that instead of relying on mitochondria to assemble iron-sulfur clusters, these cells use a different kind of machinery. And it looks like they acquired it from bacteria.

The researchers say this is the first example of any eukaryote that completely lacks mitochondria.

However, the results do not negate the idea that the acquisition of a mitochondrion was an important and perhaps defining event in the evolution of eukaryotic cells, he adds.

That’s because it seems clear that this organism’s ancestors had mitochondria that were then lost after the cells acquired their non-mitochondrial system for making iron-sulfur clusters.

Biology is amazing and mitochondria are one of the many amazing details. I wish so much that my education could have given biology a tiny fraction of the interest I have found it in after school.

Related: Human Gene Origins: 37% Bacterial, 35% Animal, 28% EukaryoticOne Species’ Genome Discovered Inside Another’sParasite Evolved from Cnidarians (Jellyfish etc.)Plants, Unikonts, Excavates and SARs

Healthy Living Greatly Reduces Likelihood of Dying from Cancer

Lifestyle choices can greatly reduce the incidence and death rates from cancer. 4 factors can reduce the incidence of cancer by up to 40% and death rate by 50%: don’t smoke, don’t drink alcohol in excess, maintain a BMI between 18.5 and 27.5, and exercising at a moderate intensity for at least 150 minutes or at a vigorous intensity for at least 75 minutes every week.

Preventable Incidence and Mortality of Carcinoma Associated With Lifestyle Factors Among White Adults in the United States

A substantial cancer burden may be prevented through lifestyle modification. Primary prevention should remain a priority for cancer control.

Cancer is the second leading cause of death in the United States, with 1.6 million new cancer cases and 0.6 million cancer deaths projected to occur in 2016.1 The cancer mortality rate, age-standardized to the 2000 US standard population, decreased from 199 to 163 per 100 000 between 1969 and 2013.2 However, this decline (17.9%) has been modest compared with the dramatic decrease in heart disease mortality (67.5%) during the same period, highlighting the need for further efforts in cancer prevention and treatment.

The study reviewed previous studies and the makeup of the previous studies and available statistics. As they state in the paper: “Because our cohorts’ participants were predominantly whites, to avoid any influence of different racial distributions on the comparison with the general population, we only included whites in the analysis.” They also excluded about 10% of cancers that are believed to have strong environmental factors.

Table Showing a Comparison of Lifestyle Factors in the Low- and High-Risk Groups

In the 2 cohort studies of US white individuals, we found that overall, 20% to 40% of carcinoma cases and about half of carcinoma deaths can be potentially prevented through lifestyle modification. Not surprisingly, these figures increased to 40% to 70% when assessed with regard to the broader US population of whites, which has a much worse lifestyle pattern than our cohorts.

Notably, approximately 80% to 90% of lung cancer deaths could be avoided if Americans adopted the lifestyle of the low-risk group, mainly by quitting smoking. For other cancers, from 10% to 70% of deaths could be prevented. These results provide strong support for the importance of environmental factors in cancer risk and reinforce the enormous potential of primary prevention for cancer control.

Related: A Healthy Lifestyle is More About Health Care than the Sickness Management That We Call Health Care IsBetter Health Through: Exercise, Not Smoking, Low Weight, Healthy Diet and Low Alcohol Intake (2013)Exercise Is Really Really Good for YouPhysical Activity for Adults: Inactivity Leads to 5.3 Million Early Deaths a Year (2012)

Medicinal Plants

Another great webcast from SciShow. In this webcast Hank Green discusses how we have used plants to treat us and improve our health.

In the webcast, Hank also does a good job touching a bit on the scientific inquiry process (which is something I find interesting and I think is very important for people living in society today to understand).

Related: Youyou Tu, The First Chinese Woman to Win a Nobel PrizeRubber TreesPhotosynthesis: Science Explained

Gut Bacteria Explored as Medical Treatment – even for Cancer

The interaction between gut bacteria and human health continues to be a fertile area of medical research. It appears to be in the very early days of such research. Of course, as I have said before, headline making news often doesn’t result in medical breakthrough, and even when it does a decade isn’t a long wait for it to happen.

How Gut Bacteria Are Shaking Up Cancer Research

In November, University of Chicago researchers wrote that giving mice Bifidobacterium, which normally resides in the gastrointestinal tract, was as effective as an immunotherapy in controlling the growth of skin cancer. Combining the two practically eliminated tumor growth. In the second study, scientists in France found that some bacterial species activated a response to immunotherapy, which didn’t occur without the microbes.

The complex interactions involved in human health is another area that has huge room for research going forward.

Related: Some Bacteria Might Fight Cancer (2008)Cancer Vaccines (2011)Using Diatom Algae to Deliver Chemotherapy Drugs Directly to Cancer Cells (2015)Webcast of a T-cell Killing a Cancerous Cell (2012)

Webcasts on the Human Microbiome

The human microbiome is a very interesting aspect of our health and biology.

The 99% figure they quote is mainly silly. It might be technically accurate, but it is much more misleading than accurate (if it is accurate). We have more non-human cells than human but those cells are much smaller and we are overwhelmingly made up of human cells by weight (95+%).

The complexity of healthy bodies is far from understood. It is interesting to watch our understanding of the balancing act going on inside of us. Many foreign “invaders” are critical to our health.

Related: People are Superorganisms With Microbiomes of Thousands of SpeciesPeople Have More Bacterial Cells than Human CellsFighting Superbugs with Superhero BugsWe Have Thousands of Viruses In Us All the Time

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Parasite Evolved from Cnidarians (Jellyfish etc.)

This is another instance of science research providing us interesting details about the very odd ways life has evolved on earth.

Genome sequencing confirms that myxozoans, a diverse group of microscopic parasites that infect invertebrate and vertebrate hosts, are actually highly reduced cnidarians — the phylum that includes jellyfish, corals and sea anemones.

“This is a remarkable case of extreme degeneration of an animal body plan,” said Paulyn Cartwright, associate professor of ecology and evolutionary biology at the University of Kansas (KU) and principal investigator on the research project. “First, we confirmed they’re cnidarians. Now we need to investigate how they got to be that way.”

images of myxozoans parasite spores and a jellyfish

Not only has the parasitic micro jellyfish evolved a stripped-down body plan of just a few cells, but via data generated at the KU Medical Center’s Genome Sequencing Facility researchers also found the myxozoan genome was drastically simplified.

“These were 20 to 40 times smaller than average jellyfish genomes,” Cartwright said. “It’s one of the smallest animal genomes ever reported. It only has about 20 million base pairs, whereas the average Cnidarian has over 300 million. These are tiny little genomes by comparison.”

Despite its radical phasedown of the modern jellyfish’s body structure and genome over millions of years, Myxozoa has retained the essential characteristic of the jellyfish — its stinger, or “nematocyst” — along with the genes needed to make it.

“Because they’re so weird, it’s difficult to imagine they were jellyfish,” she said. “They don’t have a mouth or a gut. They have just a few cells. But then they have this complex structure that looks just like stinging cell of cnidarian. Jellyfish tentacles are loaded with them — little firing weapons.”

The findings are the stuff of scientific fascination but also could have a commercial effect. Myxozoa commonly plague commercial fish stock such as trout and salmon.

“They’re a very diverse group of parasites, and some have been well-studied because they infect fish and can wreak havoc in aquaculture of economic importance,” Cartwright said.

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Fighting Superbugs with Superhero Bugs

As concerns over deadly antibiotic-resistant strains of ‘superbug’ bacteria grow, scientists at the Salk Institute are offering a possible solution to the problem: ‘superhero’ bacteria that live in the gut and move to other parts of the body to alleviate life-threatening side effects caused by infections.

Salk researchers reported finding a strain of microbiome Escherichia coli bacteria in mice capable of improving the animals’ tolerance to infections of the lungs and intestines by preventing wasting–a common and potentially deadly loss of muscle tissue that occurs in serious infections. If a similarly protective strain is found in humans, it could offer a new avenue for countering muscle wasting, which afflicts patients suffering from sepsis and hospital-acquired infections, many of which are now antibiotic resistant.

images of E. coli bacteria, salmonella typhimurium and burkholderia thailandensis

Salk scientists found a strain of E. coli bacteria (left) that were able to stop muscle wasting in mice infected with either Salmonella Typhimurium (center) and Burkholderia thailandensis (right). Image courtesy the Salk Institute.

“Treatments for infection have long focused on eradicating the offending microbe, but what actually kills people aren’t the bacteria themselves–it’s the collateral damage it does to the body,” says Janelle Ayres, a Salk assistant professor in the Nomis Foundation Laboratories for Immunobiology and Microbial Pathogenesis and senior researcher on the study.

“Our findings suggest that preventing the damage–in this case muscle wasting–can stave off the most life-threatening aspects of an infection,” she adds. “And by not trying the kill the pathogen, you’re not encouraging the evolution of the deadly antibiotic-resistant strains that are killing people around the world. We might be able to fight superbugs with ‘superhero’ bugs.”

Once the most powerful and revolutionary of drugs, antibiotics appear to have reached their limits, due to the ability of bacteria to rapidly evolve resistance to the medicines. The rise of antibiotic resistance presents a grave threat to people around the world, as diseases once easily controlled repel all attempts at treatment. A recent study found that up to half of the bacteria that cause infections in US hospitals after a surgery are resistant to standard antibiotics.

In the United States alone, two million people annually become infected with bacteria that are resistant to antibiotics and at least 23,000 people die each year as a direct result of these infections, according to the U.S. Centers for Disease Control.

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Funding Sources for Independent Postdoctoral Research Projects in Biology

Here is a nice list of funding sources for independent postdoctoral research projects in biology.

Some examples:

Directory of select science and engineering scholarships and fellowships for undergraduates, graduates and faculty on our blog.

Related: Science, Engineering and Math Fellowships (2008)Proposal to Triple NSF GFRP Awards and the Size of the Awards by 33% (2007)HHMI Expands Support of Postdoctoral ScientistsNSF Graduate Research Fellow Profiles (Sergy Brin, Google co-founder)

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.

Related: Pigs Instead of PesticidesWhy Don’t All Ant Species Replace Queens in the Colony, Since Some DoHow To Make Your Own Pesticide with Ingredients from Your KitchenAnother Bee Study Finds CCD is Likely Due to Combination of Factors Including Pesticides (2013)

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.

Related: Better Health Through Exercise, Not Smoking, Low Weight, Healthy Diet and Low Alcohol IntakeExamining the Scientific Basis Around Exercise and Diet ClaimsInactivity Leads to 5.3 Million Early Deaths a Year

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.

Related: Why does orange juice taste so bad after brushing your teeth?Microbiologist Develops Mouthwash That Targets Only Harmful Cavity Causing BacteriaUsing Nanocomposites to Improve Dental Filling PerformanceFinding a Dentist in Chiang Mai, ThailandFalse Teeth For CatsWhy Does Hair Turn Grey as We Age?

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