Infertile Mosquito Study Means Good News for Malaria Research

Mosquitoes are the pesky little critters that bother people in the summer with itchy red bumps and for many in developing areas, malaria. Each year, malaria, an incapacitating parasitic disease spread through mosquitoes, affects more than 300 million people, resulting in almost 800,000 deaths. Africa is especially affected by this disease because, on average, a child dies from malaria every 45 seconds.

Currently, doctors treat malaria using a slew of medications such as chloroquine and quindine. The widespread use of chloroquine in regions like Southeast Asia and East Africa has led to a resistance to the drug and a more difficult time treating the disease. 

Medical researchers are working on eradicating malaria, but money is a limiting factor. People realize that better tools are needed to reach this goal. Recently, however, a leap in malaria research may solve the problem.  

A new study from Imperial College London, led by Dr. Flaminia Catteruccia, gives hope to the idea that scientists will be able to control mosquito populations. Researchers chose to focus on the Anopheles gambiae, the mosquito species that is most commonly responsible for malaria transmission in Africa.  The results from the study indicate that female mosquitoes cannot tell whether a male has sperm or not.

Researchers chose to focus on the Anopheles gambiae mosquito species because it is most commonly responsible for malaria transmission in Africa. The study involved observing isolated mosquito mating couples in a laboratory. Scientists looked for certain behaviors between the couples such as, whether the female laid the same number of unfertilized eggs as they would with a fertile male.

For the study, researchers created 100 spermless mosquitoes by putting a protein into regular eggs that interrupts the creation of testes in the male, thus making it impossible for the mosquitoes to produce sperm. Despite preventing the development of the testes, this did not interfere with sexual behaviors.  

Female mosquitoes only mate once in their lifetime, which is followed by a blood meal and then lays eggs.  Dr. Catteruccia’s study determined that after females mate with a sterile male, her behavior does not change, despite the eggs not being fertilized.

Originally, the researchers expected to see that the female mosquitoes had evolved a method for determining if mates are infertile so that they guarantee their eggs will produce offspring. They based this idea upon female fruit flies who are capable of mating with more than one partner.

“In the fight against malaria, many hope that the ability to genetically control the mosquito vector will one day be a key part of our armory. In order for these currently theoretical control strategies to work, we need to make sure that the insects continue to mate as normal, unaware that we have interfered with their sexual mechanisms. This study strongly suggests that they cannot tell the difference between a fertile and a spermless mate,” stated Dr. Catteruccia.

These results can contribute to malaria eradication because it can help to control the number of mosquitoes carrying malaria. The current idea is that the females would mate with males who have experienced a genetic change to make them infertile and then would not produce fertilized eggs.

Charles Godfray, a professor from the Zoology department at the University of Oxford and co-author on the study explained, “this is an exciting time with modern genetics providing a series of new ideas about how to control the major insect vectors of human disease, including the mosquito Anopheles gambiae — perhaps the single most dangerous insect species for mankind. A number of these techniques involve disrupting natural mating patterns and to get these to work a really good understanding of mosquito mating and reproduction is essential.”

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New Study May Increase Number of Organic Poultry Farms

When a human suffers from a bacterial infection, a doctor will prescribe an anti-biotic to kill the bacteria. After years of certain bacteria being treated with the same antibiotic, some bacteria begin to develop a resistance to the treatment. Antibiotic-resistant bacteria can lead to uncontrollable widespread disease.

One major concern regarding antibiotic use is its presence in animal farming in the United States. The use of antibiotics in the food of animals raised for consumption has been proven to add to the increase of antibiotic-resistance bacteria.

A recent study from the University of Maryland School of Public Health presents data indicating that traditional poultry farms that have switched to organic farming and no longer use antibiotics have lower amounts of antibiotic resistant bacteria.  This is the first study to arise at this result.

Dr. Amy R. Sapkota, the lead researcher on the project, compared levels of enterococci bacteria on a conventional farm to those on a convention farm that has become an organic farm. The original hypothesis was that there would be some difference in the level, but nothing as significant as what was found. 

Enterococci bacteria was chosen because it is found in most poultry and they are pathogens that are often found in hospital patients. Also, the antibiotics given to the poultry on a traditional farm actively fight against the Enterococci.

“We initially hypothesized that we would see some differences in on-farm levels of antibiotic-resistant enterococci when poultry farms transitioned to organic practices. But we were surprised to see that the differences were so significant across several different classes of antibiotics even in the very first flock that was produced after the transition to organic standards,” says Sapkota.

To test their hypothesis, the team of researchers from Pennsylvania State University, University of Maryland, and Johns Hopkins University led by Sapkota studied ten traditional farms and ten farms that recently became organic farms. The team checked for the enterococci bacteria in litter, feed, and water, followed by checking the resistance of the bacteria to 17 antibiotics.

According to the study, enterococci bacteria were found in the litter, feed, and water on all farms participating in the test. It found that the percentages of antibiotic resistant bacteria were statistically significantly lower among newly converted organic farms compared to traditional farming practices.  Forty-two percent of the E. faecalis strain of enterococci bacteria from traditional poultry farms was resistant to multiple antibiotics, while ten percent of the strain was resistant on the organic farms. The other strain, E. faecium, showed an antibiotic resistance of eighty-four percent and seventeen percent in traditional and organic farms respectively.

“While we know that the dynamics of antibiotic resistance differ by bacterium and antibiotic, these findings show that, at least in the case of enterococci, we begin to reverse resistance on farms even among the first group of animals that are grown without antibiotics. Now we need to look forward and see what happens over 5 years, 10 years in time,” explains Sapkota.

These bacteria are of concern because they could be resistant to all available antibiotics and become a public health hazard. This means that if an animal or human becomes infected, it is difficult to treat.

In 2008, there were approximately 4.8 million acres of farmland dedicated to organic farming. Of 4.8 million acres, 2.1 million of the acres were dedicated to rangeland and pasture, the category where organic poultry farms fit. Ultimately, this study shows that transitioning from traditional farms to organic farms may be safer for public health. There was a fifteen percent average increase in organic farming between 2002 and 2008. This study bodes well for an increase in the number of traditional farms transitioning to organic farms.

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Naked Mole Rats May Have the Answers to Human Health Problems

Scientists from the University of Liverpool and the Genome Analysis Centre, while working with other scientists from across the globe, produced the first whole-genome sequence information on the naked mole-rat, an animal known for its longevity and resistance to cancer.

The naked mole-rat, Heterocephalus Glaber, is a rodent from East Africa. They live in colonies in an underground burrow system that has resulted in a number of adaptations. Adaptations include low metabolic rates, the lack of reaction to pain in the skin, and an inability to regulate body temperature because of the stable underground temperatures.

These adaptations are not the reason scientists chose to study the genome of the rodent though. Naked mole-rats are small creatures, only 8 to 10 cm long, which normally means they would live for up to five years like other rodents of that size; however, Heterocephalus can live up to 30 years.

By sequencing the genome of the naked mole-rat, scientists hope to discover the reason behind the rodent’s longevity and resistance to disease associated with aging. Specifically, researchers will study DNA repair and the genes related to the age-resistant processes.

Dr. Joao Magalhaes of the University of Liverpool stated, “The naked mole-rat has fascinated scientists for many years, but it wasn’t until a few years ago that we discovered that it could live for such a long period of time. It is not much bigger than a mouse, which normally lives up to four years, and yet this particular underground rodent lives for three decades in good health. It is an interesting example of how much we still have to learn about the mechanisms of aging.”

Researchers hope to apply the information they learn from the rodent’s genome to human biology. There has never been a recorded case of cancer in a naked mole-rat and recently, studies have found that the animal may even have anti-tumor capabilities not found in humans or other rodents. With cancer accounting for 7.6 million deaths worldwide in 2008 and even more diagnoses, scientists are looking to the naked mole-rat for answers.

“We aim to use the naked mole-rat genome to understand the level of resistance it has to disease, particularly cancer, as this might give us more clues as to why some animals and humans are more prone to disease than others. With this work, we want to establish the naked mole-rat as the first model of resistance to chronic diseases of aging,” said Magalhaes.

To map the genome, researchers used the latest technology. Advances in the technology allowed for a generation of the first draft within a few days.

This technology can best be described as chemical “scissors” that would cut out long strands of DNA code. The shorter codes are read and pieced back together to produce the genome.

According to the Head of Bioinformatics at the Genome Analysis Centre, Dr. Mario Caccamo, the speed at which the genome was sequenced “is a great achievement considering that this is a mammalian species with typically complex and repetitive genome.” 

The first draft of the genome is available online for other scientists to use in their research. Researchers can download and use the data for certain small-scale analysis without contacting the discoverers. Soon, the data will be available for use with large-scale analysis in collaboration with the Genome Analysis Centre.

Another database was launched before the data for the naked mole-rat became available. This database, considered the most extensive and complete record, contains information about more than 4,000 animal species. It has information such as lifespan, weight, litter size, and sexual maturity, which can be used to compare animals against one another.

Scientists will be able to study the genome of the naked mole-rat in comparison to other rodents and mammals using this database.

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