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Whale sharks studied with new method that could open up to more research

Claire Peterson on September 25, 2023

Whale sharks — Science and technology are fascinating because they enable us to learn more about topics in which we were previously interested.

Ultrasound was not used for pregnancy testing until the 1950s and 1970s.

Because of comparable breakthroughs, humans can also track the pregnancy of animals, notably cats and dogs.

Recent studies, on the other hand, may have discovered a mechanism to better comprehend whale shark reproduction.

Initial thoughts

Scientists formerly thought that larger spots on the undersides of female whale sharks indicated pregnancy.

However, for the first time, a method for free-swimming animals was used, indicating that it was all skin and muscle.

The humps, like breasts in humans, may constitute a secondary sex feature in adult females, according to researchers in the March 23 edition of Endangered Species Research.

Scientists are looking for new ways to learn more about whale shark reproduction, including underwater “jet packs” and blood testing.

The animal

Whale sharks, or Rhincodon typus, are listed as critically endangered by the International Union for Conservation of Nature.

Only an estimated 100,000 to 238,000 ocean inhabitants remain, a reduction of more than 50% in the previous 75 years.

Whale sharks have an average length of 12 meters and may attain speeds of up to five kilometers per hour.

Due to the paucity of whale sharks, scientists are perplexed about their reproductive biology.

Biologists gained experience by evaluating the catch of a pregnant female by a commercial fishing boat in 1995.

“Protecting organisms without knowing about their biology is like trying to catch a fly with our eyes closed,” said Okinawa Churashima Foundation fishers biologist Rui Matsumoto.

Okinawa Churashima Foundation conducts research on subtropical animals and plants in order to develop and preserve natural resources in protected areas.

Research

Matsumoto worked with Okinawa Churaumi Aquarium shark expert Kiyomi Murakumo to learn more about whale sharks and how to keep up with them.

The researchers swam alongside the whale sharks, which had scuba tanks with propellers, using underwater jet packs.

The scientists utilized a 17-kilogram suitcase with a waterproof ultrasonography wand to collect blood from the undersides of 22 female whale sharks cruising near the Galápagos Islands.

Prior to the study, the ultrasound wand has never been used on free-swimming animals outside of an aquarium.

The two investigations were difficult, according to Simon Pierce, a whale shark biologist with the Marine Megafauna Foundation.

The Marine Megafauna Foundation is a non-profit organization dedicated to marine conservation via research.

According to Pierce, the whale shark possesses some of the thickest skin of any animal, measuring more than 30 centimeters thick.

Another problem was that the blood samples may have been contaminated by seawater.

To address this issue, researchers devised a two-syringe method in which the first syringe creates a vacuum while the second syringe draws blood.

Lab tests

The Marine Megafauna Foundation is a non-profit organization dedicated to marine conservation via research.

According to Pierce, the whale shark possesses some of the thickest skin of any animal, measuring more than 30 centimeters thick.

Another problem was that the blood samples may have been contaminated by seawater.

To address this issue, researchers devised a two-syringe method in which the first syringe creates a vacuum while the second syringe draws blood.

Tech innovations

Researchers have learned more about other vulnerable marine creatures thanks to noninvasive technologies used on whale sharks.

Waterproof ultrasonography wands attached to poles are being used on tiger sharks in places where the predators are drawn in with bait, according to Simon Pierce.

The underwater sample procedure was revolutionary, according to Rachel Graham, the MarAlliance’s creator and a marine conservation specialist.

She is skeptical that wild sea species like faster-swimming sharks or other marine animals will agree to such studies.

“What makes whale sharks fairly unique… is that they move relatively slowly at times, have the ability to remain stationary,” Graham pointed out.

“They tolerate the presence of other animals – such as us – nearby.”

Graham has traveled the world studying sharks.

Using satellite monitoring, the new technique, according to Pierce, may reveal where whale sharks give birth.

Little is known about whale shark pups, such as whether they are born in shallow or deep water, if they are delivered one at a time, and whether moms cluster to give birth.

“Assuming they do have some sort of breeding or pelagic nursery area we can identify… then that obviously goes quite a long way towards conserving the population,” said Pierce.

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Estrogen has potential to go lower, according to studies

Leah Cooper on September 5, 2023

Estrogen — Estrogen is a female hormone that is produced mostly in the ovaries and is necessary for the creation and function of reproductive organs.

It regulates menstruation, encourages endometrial growth, and is in charge of the development of female secondary sex characteristics.

Estrogen is combined with other hormones in birth control pills to prevent pregnancy.

It suppresses ovulation and thickens cervical mucus, making sperm more difficult to reach an egg.

Estrogen also aids in the control of the menstrual cycle, decreases the risk of ovarian and endometrial cancer, and may provide other health benefits such as acne reduction and bone density enhancement.

Side effects

The inclusion of estrogen in birth control pills raises the risk of blood clots and stroke, especially in women who smoke or have other cardiovascular risk factors.

Although estrogen may increase the chance of developing breast cancer, the absolute risk is low.

Nausea and breast soreness are the minor estrogen side effects of birth control pills.

These negative effects are usually transitory and disappear within a few weeks.

Headaches, mood changes, and libido variations are among the other minor adverse effects.

The benefits of estrogen-containing birth control pills outweigh the risks for the vast majority of women, but any concerns or potential adverse effects should be explored with a healthcare provider.

New findings

There is ongoing research to create birth control that is both effective and low in estrogen.

Researchers revealed, using a mathematical model, that decreasing the estrogen level in traditional contraceptives by 92% still has the power to prevent pregnancy.

The research was published in the April 13 edition of PLOS Computational Biology.

They claimed that a low dose of progesterone, another contraceptive hormone, or a combination of the two hormones might prevent ovulation.

However, the drugs would have to be given at a critical point in the menstrual cycle.

Many highly successful contraceptives include enough estrogen to render them useless for some people, particularly those with a family history of hypertension or breast cancer.

Furthermore, establishing in clinical trials that lower doses of the hormones prevent ovulation may enable individuals at high risk of severe side effects with access to estrogen-based contraception.

The mathematical model

Brenda Lyn Gavina and Aurelio de los Reyes of the University of the Philippines Diliman in the Philippines expanded on an existing menstrual cycle mathematical model.

They looked at real-world data from 23 women ages 20 to 34.

The model takes into account the intricacies of blood hormone levels from three major sources:

The pituitary glands
The ovaries
Hormonal birth control

Throughout a menstrual cycle, the researchers duplicated progesterone or estrogen levels that inhibited ovulation.

They used the same dose levels as standard methods of birth control.

The researchers then utilized optimum control theory, a mathematical approach, to determine the least amount of estrogen or progesterone that may prevent ovulation.

They observed that administering 8% estrogen 11 days after the start of the menstrual cycle inhibited the ovary from producing an egg.

Gavina and de los Reyes also observed that utilizing less estrogen and progesterone during that time period caused ovulation to be disturbed.

According to the researchers, the dose might be delivered by injections or implants.

“We did not only lower the dosage, but we also identified when to administer the contraceptive,” said de los Reyes.

According to Alison Edelman, a gynecologist at Oregon Health & Science University in Portland, a modest amount of estrogen would probably ease some of the negative effects.

The new discoveries, according to Edelman, will not be utilized to produce better contraception anytime soon.

The model assumes that estrogen from birth control remains constant throughout time and does not take into account how the hormone is absorbed by the body.

It is likely to change, impacting the medicine’s effectiveness.

“I want to assure people that [low-dose estrogen in birth control] is already being looked at,” said Edelman.

She emphasized that people may now use hormone-based birth control that is both safe and effective.

Gavina and de los Reyes expressed a wish to cooperate with doctors like Edelman to make their models more relevant to researchers working on low-dose birth control medicines.