Biology – Little Bits of Science

Repelling Mosquitoes. Or Not.

So all those gadgets and candles you use for getting rid of mosquitoes? Mostly worthless, it seems.

A large number of different spray-on repellents and wearable repellent devices are commercially available. The efficacies of many repellents are unknown. This study focuses on the efficacy of eleven different repellents in reducing the number of Ae. aegypti female mosquitoes attracted to human bait. We performed attraction-inhibition assays using a taxis cage in a wind tunnel setting. One person was placed upwind of the taxis cage and the mosquito movement towards or away from the person was recorded. The person was treated with various spray-on repellents or equipped with different mosquito repellent devices.

The most effective repellent was a DEET-based product. And least effective were devices which use high-frequency sound to keep mosquitoes away. Link found via ScienceMag.

Bees are Addicted to Caffeine

I’m a big fan of caffeine. So much so that I have a caffeine molecule tattooed on my left forearm. caffeine photo But it turns out that humans aren’t the only caffeine aficionados. Bees like caffeine, and spend more time gathering nectar from flowers which naturally produce caffeine.

Scientists at the University of Sussex said they thought the plants produce the caffeine in their nectar to fool bees into thinking it contains more sugar than it actually does. The insects will repeatedly visit those flowers, helping the plants maximize pollination.

Francis Ratnieks, a professor of apiculture at the university, said bees communicate by moving their abdomens a certain way — or, as he calls it, “dancing.” He said the caffeine increases that dancing.

Photo by Hey Paul Studios

Photo by paulscott56

Toxoplasmosis and Rage Disorders

Because at Little Bits of Science we seem to love writing about poop stories, here’s another fecal-related story to catch your eye:

Uncontrollable, explosive bouts of anger such a road rage might be the result of an earlier brain infection from the toxoplasmosis parasite, an organism found in cat feces, a new study finds.

Puppy Poop for Goodness!

Seems science has a lot going on in the world of poop right now. The latest news is a bit on curing puppy diarrhea with fecal transplants. Veterinarians looking to prevent diarrhea in kennel puppies may have a new option:

A veterinarian in Palmetto, Florida this week revealed a technique that uses poop transfers to successfully treat service puppies in-training that suffer from recurrent diarrhea, a common problem for dogs kept in kennels. The method reportedly cured 87 percent of dogs in the first round and 93 percent of those needing a second treatment.

That’s some pretty good numbers for preventing potential problems for pups.

Lobsters Don’t Live Forever

So there’s a meme going around (at least, I’m seeing it on Facebook and Instagram) that suggests jellyfish and lobsters are basically immortal. lobster photo Well, Smithsonian Magazine is here to teach us that no, lobsters are not immortal.

The viral scientific tidbit can be traced back to a brief 2007 news story that reports that lobsters don’t show typical signs of a phenomenon known as senescence. In plain terms, the report says that lobsters don’t age the way other living creatures do—they don’t lower their reproductive ability, slow their metabolism or decrease in strength. This led to extrapolations that lobsters, if left undisturbed, can’t die.

So it’s a fun story to read, but it’s sadly false. And it makes me hungry.

Photo by stu_spivack

Jellyfish Poop!

Videos of pooping comb jellyfish stun evolutionary biologists:

No buts about it, the butthole is one of the finest innovations in the past  540 million years of animal evolution. The first animals that arose seem to have literally had potty mouths: Their modern-day descendants, such as sea sponges, sea anemones, and jellyfish, all lack an anus and must eat and excrete through the same hole. Once an independent exit evolved, however, animals diversified into the majority of species alive today, ranging from earthworms  to humans.

I don’t want to spoil the punchline, but comb jellyfish aren’t such potty mouths – this suggests that either scientists have been wrong about jellyfish digestion, or later animals lost the trait after splitting from an ancestor which had an anus. Either way, this opens up more research areas for scientists and may further define our understanding of evolution.

Prairie Dog Serial Killers

Aw, those sweet little prairie dogs. Always a hit at the zoo. Adored by many because they are just so dang cute! Turns out there’s a wicked side to them, however, as some prairie dogs are just serial killers of squirrels in cute little packages.

The rabbit-sized herbivore’s relations with the ground squirrels that forage alongside it often explode into murderous attacks – with some prairie dogs biting squirrels to death on a regular basis.

This is thought to be the first time that one mammalian herbivore has been seen routinely killing members of another herbivore species.

As to why, well, it seems there is some benefit to the family of the serial killers over the families of non-serial killer prairie dogs. That is to say, the serial killers had more offspring than non-serial killers, and the serial killers had survival rates nearly three times their less maniacal brethren.

Photo by Gary Yankech

Women in Science – Dr. Maud L. Menten

To start my Women in Science series, I’ll present information on a scientist with whom I share a birthday – Dr. Maud L. Menten, Biochemist from Canada. Born in Port Lambton, Ontario in 1879, Dr. Menten graduated from the University of Toronto in 1913 (some sources say 1911). Later in 1913, she was an author for the article “Die Kinetik der Invertinwirkung” which introduced the Michaelis-Menten equation, used to relate the reaction rate of an enzyme to the concentration of a substrate.

The reaction rate increases with increasing substrate concentration $[S]$ , asymptotically approaching its maximum rate $V_\max$ , attained when all enzyme is bound to substrate. It also follows that $V_\max = k_\mathrm{cat} [E]_0$ , where $[E]_0$ is the initial enzyme concentration. $k_\mathrm{cat}$ , the turnover number, is the maximum number of substrate molecules converted to product per enzyme molecule per second.

Her contributions to science continued long after the Michaelis-Menten equation. She made additional discoveries/co-discoveries relating to hemoglobin, blood sugar, and kidney functions. Because women were not generally able to work in the medical field in Canada at the time, she ended up working mainly in the US with some time spent in Europe, as well.

Dr. Menten continues to be honored today by the Dr. Maud L. Menten Memorial Lecture Series.

The Dr. Maud L. Menten Memorial Lecture Series is held annually by the Department of Biochemistry. Two mini-symposia and at least eight lectures will be held each year. The speakers are expected to be active, high-profile scientists and are nominated by the Department of Biochemistry research community. Invitations are sent after selection of the speakers by the Dr. Maud L. Menten Memorial Lecture Series Committee.

Double Mastectomy Rates on the Rise, but Survival Rates Steady

A study covering 20 years of treatment for breast cancer in California shows a significant rise in rates of double mastectomies, but no significant change in survival rates as a result.

The researchers looked at the medical records of 189,734 California women who were diagnosed with early-stage breast cancer in one breast from 1998 to 2011.

During that time, the overall number of women who chose to have double mastectomy increased from 2% in 1998 to 12.3% in 2011. This increase was even larger in women younger than 40:

. . . (survival rates given) . . .

The small difference in survival rates between the women who had lumpectomy plus radiation and the women who had double mastectomy wasn’t statistically significant, which means it could have happened by chance and wasn’t because of the difference in treatment.

Weekends on the Couch Add to Weight

In news that shouldn’t surprise anyone, scientists find that sitting around doing nothing on the weekends contributes to fat buildup in the body. What might be surprising to some is that this sedentary time is apparently worse for the body than a normal 9-5 weekday desk job.

Exercise scientists reported that even a 20-minute reduction in sedentary time on Saturdays and Sundays added up to a loss of more than 2 pounds and 1.6 percent of body fat after a year. But the same association was not seen with sedentary time during the weekdays.

So do your body a favor and spend at least some of your weekend time getting out of the house and doing something active, whether it’s a full workout at the gym, a long walk with your dog, or pretty much anything that raises your heart rate.