Tuesday, September 19, 2017

Caught in My Web: Spiders!

Image by Luc Viatour at Wikimedia Commons
Spiders creep most of us out. But let’s face it: they are pretty darn amazing! For this edition of Caught in My Web, we appreciate our 8-legged friends.

1. Did you know that sea spiders use their gut as a heart?

2. And lace sheet weaver spiders make optical illusion webs to lure nocturnal moths.

3. Even our run-of-the-mill spiders are pretty amazing, when you really look at them. Watch this amazing timelapse of a garden orb web spider building a web:



4. Portia, the spider-hunting spider, is a genius with super-powers:


5. And researchers at the National University of Singapore have now found that personality affects how these smart spiders hunt.

Tuesday, September 12, 2017

I Know I Want to Work With Animals. Now What?

"What to do? What to do?" Photo by Dmitry Rozhkov at Wikimedia Commons

Does this sound familiar: “I know I want to work with animals, but I don’t know if I want to be a vet. What should I be? How do I prepare for a career if I don’t even know what I want to do?”

If this is you, don’t panic. There are many professions that work with animals, and luckily, there is a lot of overlap when it comes to qualifications for those jobs. This means that there are certain steps that you can take to make you competitive for a range of jobs that work with animals and you don’t have to decide today exactly what that job will be.


Experience With Animals


To get a job that works with animals, you need to be good at working with animals. Seems pretty obvious, but it can be more difficult than you think. To get good at something, you need experience, and to get experience, you need a position, and to get a position, you need to be good at it… AARRGG!

The trick is to get your foot in the door: Train your pets to compete in obedience or agility competitions. Work in a pet store, groomers, or pet boarding kennel. Volunteer at a local animal shelter, animal rehabilitation center, veterinary clinic, or zoo. If you are considering colleges, ask about clubs, internships and other opportunities that they offer to get animal experience.

It is also important to keep a record of all your animal experiences; List all of the experiences by category or position and keep track of your hours. This will be invaluable information to put on applications in the future.


Experience With People


We often forget that many positions that work with animals also require a strong ability to work with people. Veterinary clinics work with pet owners; Zoos and aquariums teach the public; Animal trainers would be more accurately called “pet-owner-trainers”. As counterintuitive as it may seem, you can improve your marketability to animal jobs by improving your people skills.

First and foremost, don’t shy away from face-to-face contact. Yes, texting and emailing is faster and easier, but an actual conversation can have a much better outcome and helps develop your people skills without a conscientious effort. Beyond that, pay attention in English classes, read books, and seek out opportunities to interface with actual people. Jobs in retail and as receptionists are good for this. Look for opportunities in the field of education, perhaps as a tutor or assistant. Volunteer to interact with people in nursing homes, hospitals, or shelters. And again… keep track of your hours.


Education


Educate yourself for the job you want.
Photo by raider of gin at Wikimedia Commons.
There are jobs that work with animals for people with all levels of education, so you may want to pursue the level of education you need for the job(s) that you want.

Before you complete high school, you may be eligible to be a: volunteer (at an animal hospital, rehabilitation center, zoo, aquarium, or animal shelter), pet store employee, pet boarding employee

With a high school diploma, you may be additionally eligible to be a: veterinary assistant, veterinary receptionist, domestic animal care staff, domestic animal trainer, animal control worker or dog warden, animal farmer or breeder

With a specialized 2-year degree, you may be additionally eligible to be a: veterinary technician or veterinary technologist

With a 4-year degree, you may be additionally eligible to be a: zoo keeper or aquarist, educator, wildlife rehabilitator, wildlife animal trainer, assistant research biologist, animal care manager, animal cruelty investigator

With a DVM, you may be additionally eligible to be a: veterinarian (at a clinic, hospital, zoo, or university), research biologist

With a PhD, you may be additionally eligible to be a: research biologist


Are you already in an animal-related career? Share your tips in the comment section below! And for more advice for working with animals, go here.

Tuesday, September 5, 2017

A New Key to the Story of How the Sexes Have Come to Be


In the beginning, we are all male and female… More specifically, we are all in between male and female. So what makes our embryonic selves choose and follow a developmental path to becoming the sex that we are today? New research has dramatically changed our understanding of this process.

During early embryonic development, all mammals develop a single pair of gonads that are neither testes nor ovaries, but have the potential to become either. Likewise, the external genitalia at this early stage has the potential to become either a penis and scrotum or a clitoris, vagina, and labia. Two pairs of ducts develop to connect the gonads to the undifferentiated external genitalia: One set of ducts, the Wolffian ducts, would become the epididymis, vas deferens, and seminal vesicles if this animal becomes male. The other set of ducts, the Müllerian ducts, would become the oviducts, uterus and innermost part of the vagina if this animal becomes female. So what determines if a given animal will develop male or female reproductive anatomy?

Early in development, mammalian embryos have one set of gonads that has the potential to become either testes or ovaries (here labeled as "bipotential gonad"). These gonads are connected the the developing external genitalia by two sets of tubes: The Wolffian ducts become the reproductive tracts in males and the Müllerian ducts become the reproductive tracts in females. The ducts that do not become reproductive tracts typically disintegrate. However, XX female embryos that lack the COUP-TFII protein do not dismantle their male-like reproductive tracts. Figure from Swain, 2017.

The sex of a mammal is determined by the combination of sex chromosomes it has. If the mammal has two X chromosomes, it will likely become female, and if it has an X chromosome and a Y chromosome, it will likely become male. The story physiologists have been telling for decades is that there is a single gene located on the Y chromosome, called the SRY gene, that single-handedly makes an embryo become a male. When expressed, the SRY gene produces a protein, called testes-determining factor, which interacts with the cells of the undifferentiated gonads to turn them into testicular cells. These newly formed testicular cells produce two key hormones: testosterone, which causes the Wolffian ducts to become the epididymis, vas deferens, and seminal vesicles, and anti-Müllerian hormone (AMH), which causes the Müllerian ducts to degenerate. In other words, if an animal has a Y chromosome, it will typically have an SRY gene that will trigger the sequence of events that causes the animal to develop into a male. If the animal does not have the Y chromosome, it will typically become female. However, it is not just the lack of a Y chromosome that can make a female; Any disruption of this pathway (such as an SRY gene that is not expressed, or the lack of testicular hormones) typically causes the animal to develop into a female. For this reason, females in mammals have been called the default sex. The scientific understanding since the 1950s has been that, in mammals, the development of a male reproductive system is an active process and the development of a female reproductive system is a passive process. However, a new study reveals that the process of becoming female mammal is not as passive as we have thought.

Fei Zhao, Humphrey Yao and their research team at the National Institute of Environmental Health Sciences and Baylor College of Medicine discovered a critical role for a specific protein, called COUP-TFII, in the active process of becoming a mammalian female. The research team examined female mouse embryos (which lack a Y chromosome, and hence an SRY gene) that had been genetically modified to lack a particular protein called the COUP-TFII protein. They compared these genetically modified XX embryos to genetically typical XX mouse embryos. When the unmodified XX embryos had developed to have only Müllerian ducts (the “typical” female reproductive pathway), the XX embryos without COUP-TFII protein retained both Müllerian and Wolffian ducts! Unfortunately, these XX mice that lacked the COUP-TFII protein died shortly after birth, so it was difficult to tell if this developmental process would have continued. The research team cultured reproductive organs of XX mice with and without COUP-TFII protein and found that this developmental trajectory likely would have continued after birth.

Images A and B show the reproductive tract from the side (A) and as a cross-section (B) in a "typical" XX female mouse embryo. Images D and E show that XX females that lack the COUP-TFII protein retain both Müllerian (pink arrows) and Wolffian (blue arrows) ducts. Figure from Zhao et al., 2017.

We know that testosterone helps promote the development of Wolffian ducts in XY males, so the most likely explanation of what they witnessed is that the lack of COUP-TFII protein somehow increased action of testosterone in these genetically modified XX embryos. The researchers ran a number of tests to explore this possibility. Testosterone is mostly produced by the gonads, so they compared the gene expression and enzymes of ovaries of unmodified XX mice with the ovaries of XX mice that lacked the COUP-TFII protein, and they found no differences that pointed to differences in testosterone production. They then considered the possibility that testosterone was produced somewhere else in the body, but the XX mice that lacked the COUP-TFII protein did not have more masculine body features compared to the unmodified XX mice. Finally, the researchers gave extra testosterone to the mother mice that were pregnant with unmodified XX mice and XX mice that lacked the COUP-TFII protein. The extra testosterone did not affect any of the mouse pups; it did not cause the Wolffian ducts of the XX mice that lacked the COUP-TFII protein to regress. Together, the researchers found that no, XX embryos that lack COUP-TFII protein do not have any more testosterone-like activity than their non-genetically modified XX sisters. This means that testosterone alone is not enough to keep Wolffian ducts.

This research has shown us that for the Wolfian ducts to go away during the reproductive development of a mammalian female, they need to be actively dismantled using a biochemical process (similar to how AMH dismantles Müllerian ducts during male reproductive development). COUP-TFII protein appears to be the chemical in charge of triggering this process. Female mammals are not the passive result of simply not becoming male, as has been taught in physiology classes for decades. Becoming a female mammal requires a process all its own, and we are only now starting to learn what that is.


Want to know more? Check these out:

F. Zhao et al. Elimination of the male reproductive tract in the female embryo is promoted by COUP-TFII in mice. Science. Vol. 357, August 18, 2017, p. 717. doi: 10.1126/science.aai9136

A. Swain. Ductal sex determination. Science. Vol. 357, August 18, 2017, p. 648. doi: 10.1126/science.aao2630

Tuesday, August 29, 2017

The Olympic Athlete of the Animal Kingdom: The Circulatory System of a Horse (A Guest Post)

By Emily Fandrey


How do you judge the abilities of an athlete? Is it all about speed? What about endurance? Strength? How would you judge an animal that can run up to 48 kilometers per hour (30 mph), cover 48 kilometers (30 miles) in a day, or clear a 2.4 meter (8 foot) jump, all while carrying a human on its back? Because of these abilities, the horse (Equus caballus) is often considered to be one of the animal kingdom’s best athletes. The major factor behind horses’ advanced athleticism is their unique circulatory system, specialized for delivering large amounts of oxygen throughout the body.

Image by Paul Kehrer at Wikimedia Commons.

A horse’s circulatory system has three major players: the heart, the spleen, and the frog (and no, this has nothing to do with the animal frog, but rather a specialized unit of a horse’s hoof). Due to these three components, horses have one of the best aerobic capacities in the animal kingdom. Let’s look at a racehorse for example: During a race, a thoroughbred can reach a maximum oxygen capacity (the amount of oxygen the blood can carry) of 200 milliliters per kilogram per minute, meaning 200 milliliters of blood per kilogram of weight (or 3.1 ounces per pound) are transported to the body every minute! This is more than twice the oxygen capacity of the most elite human athlete!

This diagram illustrates the horse’s circulatory system,
including the heart, arteries, veins, and spleen. Diagram by Emily Fandrey.

So let’s break down this superior aerobic system, starting with the horse heart. Typically, a horse’s heart weighs 1% of its total body weight; meaning if a horse weighs 450 kilograms (1000 pounds), its heart will be roughly 4.5 kilograms (10 pounds). If this was true for humans, a 68 kilogram (150 pound) human’s heart would be 0.68 kilograms (1.5 pounds), although the average human heart is only about 0.23 kilograms (half a pound). The horse’s heart functions very similarly to a human heart. It contains four chambers and is responsible for getting oxygen to the body by pumping the oxygen-filled blood. After the body systems have used the oxygen in the blood, this deoxygenated blood enters the heart and is sent to the lungs where the blood is resupplied with oxygen from breathing air. This oxygenated blood reenters the heart and is pumped back out to the body. Because of the size of their hearts, horses are able to supply large amounts of blood with oxygen to the body with each heartbeat, averaging a combined 38 liters (10 gallons) per minute (this is about ten times as much as a human).

Horses also have very different heart rates than humans during rest and exercise. A horse’s resting heart rate is 28-44 beats per minute (bpm), compared to the average human’s, which is 60-80 bpm. During exercise, a human’s heart rate is 90-170 bpm, depending on age. A horse’s heart rate, however, rises to 80 bpm during a walk, 130 bpm during a trot, 180 during a canter, and 240 bpm while galloping. At top speed, the fast beating heart of the horse is what allows the heart to pump much more blood to the body than a human, increasing their athletic abilities.

A diagram of how the horse’s frog sends blood back to heart quickly,
working against gravity. Diagram by Emily Fandrey.

With the long legs of horses, the heart also has to work against gravity to get blood from the limbs back to the heart. To combat this, the horse has its “frog”. For a horse, the frog is a vessel-filled tissue structure on each of its four hooves. When weight is placed on the frog, this structure can help the heart work against gravity. How? When the horse’s hoof meets the ground, the ground will push up on the frog, resulting in the frog being compressed and squeezing blood in the vessels out and rapidly up the leg. The frog helps heart work against gravity by sending the blood up the leg and back to the heart, allowing for faster blood circulation, increasing the athleticism of the horse.

The last key factor to the horse’s circulatory system is the spleen. This organ improves aerobic capabilities and the horse’s athleticism. Now, the primary function of the horse’s spleen is to remove damaged blood cells. However, when a horse is relaxed, their spleen will fill with up to 30 liters (8 gallons) of oxygen-filled blood. And then, once the excitement of activities like running or jumping sparks, the spleen will contract and send up to 25 liters (6.6 gallons) of this stored blood back into circulation in mere seconds! So in seconds, the spleen is capable of almost doubling the maximum amount of oxygen the blood can carry, increasing the athleticism of the horse as well.

So if you ever need an excelling athlete on your team, consider an animal with a superior circulatory system: the horse. With a large and powerful heart capable of pumping large amounts of blood, a spleen to provide an extra burst of blood in seconds, and a “frog” to work against gravity, there is no wonder why horse is considered to be one of the world’s superior athletes.


References

Allen, K.J., Young, L.E., and Franklin, S.H. (2016). Evaluation of heart rate and rhythm during exercise. Equine Veterinary Education 28: 99-112. DOI: 10.1111/eve.12405.

Cardiovascular System (2007). In EQUINAvet.

Circulatory System of the Horse (2010). In Helpful Horse Hints.

Equine Circulatory System Vet, Horse First Aid (2012). In Equestrian and Horse.

Norton, J. (2013). The equine circulatory system. In EquiMed: Horse Health Matters.

Monday, August 21, 2017

Caught in My Web: Animal Reactions to A Solar Eclipse

Animation by Locutus Borg at Wikimedia Commons.
A solar eclipse is a rare event that can have dramatic effects not only on us people, but on animals as well. For this edition of Caught in My Web, we think about how animals may respond to such a rare celestial event.







Image by Luc Viatour at Wikimedia Commons.
1. National Geographic shares many ways animals are known to behave in strange ways in response to a solar eclipse.

2. Much of the effect of an eclipse on animal behavior is utter confusion, but many groups will be watching animals to see how they respond.

3. Researchers at the University of Nebraska will be collecting behavior data on GPS-tagged red-tailed hawks to see how the solar eclipse affects them.

4. Some nature centers are studying animal behavior during the eclipse.

5. If you found any animals that freaked out so badly as to injure themselves, check here for advice.