If size and frequency count, crickets may be the sexiest creatures

 

Life as a cricket is rough: cannibalism, exhausting procreation and the world’s largest testicles. Tom Zegler

Susan Lawler, La Trobe University: If you had to guess what creature in the world had the largest testes, I doubt you would guess that the prize belonged to a cricket.

The testes of the tuberous bush cricket (Platycleis affinis) are an internal affair, taking up most of the cricket’s abdomen. At nearly 14% of their body weight, they are disproportionately large when compared to other species. Just think, a 100kg human would be walking around with 14kg of testicles, which would be mighty uncomfortable.

Why do these crickets need all that sperm power? It is because their females are highly promiscuous. The male bush crickets do not release more sperm than normal in any given sexual act, but they can be called upon to do it so often they apparently need the reserves. In the world of insects, it is not worth missing an opportunity, and if the females are going to be all available like that, then a cricket needs some world-class balls.

But this is not the only sexual record held by crickets. An Australian species known as scaly crickets (Ornebius aperta) have the most frequent sex of any species in the world. These little guys can do it more than 50 times in a few hours, often with the same female!

Why do they have to keep this up? Because she eats it.

That’s right, cricket sex provides more than the spark for the next generation. Males actually produce a package called a spermatophore, which is sperm wrapped up in a nutritious protein package. When the males insert it into a special opening in the females, sometimes she just bends down to gobble up her yummy post-coital snack.

Australian spiny cricket males respond to this sabotage by releasing only a few sperm per package, between 5 and 225 sperm per copulation, an astonishingly low amount compared to the average (100,000). Yet when researchers measured sperm loads in females, they had up to 20,000 sperm stored away. This means that they had sex up to 200 times to collect that amount.

Of course the females were storing up more than sperm. They also gathered nutrients that will help them develop eggs for the next generation. Other species of crickets manage the situation by offering a courtship gift in the form of food from the dorsal glands that distract the female and give her something to eat during sex.

Some female crickets seek out males in order to get these tasty gifts. A study of 32 different species of bushcrickets showed that the larger the spermatophore, the more likely the females were to actively seek out males. These gifts are costly to produce, so species that produce small spermatophores may mate twice a night, while those with large spermatophores may mate only once or twice in a lifetime.

The final cricket sex record goes to the Mormon cricket, which produces a spermatophore that is 27% of its body weight. That’s a huge investment in wild oats, which is a good description, since most of the package is food. The Mormon crickets are flightless and form swarms similar to locusts. These great walking hordes are often so hungry that cannibalism is common.

Female Mormon crickets will compete for males just so they can get a feed, and the benefit for the male is that some of his sperm may make it to the next generation.

Crickets are not likely to be overly loyal to each other, because research on Spanish field crickets shows that individuals with more mating partners leave more offspring. This applies to both male and female crickets, so it is surprising that males will nevertheless protect a female that they have mated with.

Male crickets will linger near a female they have recently given their sperm to, not to scare away other suitors, but to protect the female from predators. He does this at his own peril, because males that hang about after sex are four times more likely to be eaten. On the other hand, the females are six times less likely to be eaten if he is there to protect her.

Male crickets are not confused about the goal of spermatophore transfer. But female crickets want more than just sperm from their partner. A meal (or several dozen meals) increases the male cricket’s chance of getting lucky.

Maybe they are not so different from people, after all.

Susan Lawler, Head of Department, Department of Environmental Management & Ecology, La Trobe University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Read More........→April 30, 2024

Scientists Discover Potential HIV Cure that Eliminates Disease from Cells Using CRISPR-Cas Gene Editing

HIV-1 virus particles under electron micrograph with H9 T-cells (in blue) – Credit: National Institute of Allergy and Infectious Diseases

A new study has unveiled a likely future cure for HIV which uses molecular scissors to ‘cut out’ HIV DNA from infected cells. To cut out this virus, the team used CRISPR-Cas gene editing technology—a groundbreaking method that allows for precise alterations to a patient’s genome, for which its inventors won the Nobel Prize in Chemistry in 2020. One of the significant challenges in HIV treatment is the virus’s ability to integrate its genome into the host’s DNA, making it extremely difficult to eliminate—but the CRISPR-Cas tool provides a new means to isolate and target HIV DNA. Because HIV can infect different types of cells and tissues in the body, each with its own unique environment and characteristics, the researchers are searching for a way to target HIV in all of these situations. In this study, which is to be presented ahead of this year’s European Congress of Clinical Microbiology and Infectious Diseases, the authors used CRISPR-Cas and two guide RNAs against “conserved” HIV sequences. They focused on parts of the virus genome that stay the same across all known HIV strains and infected T cells. Their experiments showed outstanding antiviral performance, managing to completely inactivate HIV with a single guide RNA and cut out the viral DNA with two guide RNAs. “We have developed an efficient combinatorial CRISPR-attack on the HIV virus in various cells and the locations where it can be hidden in reservoirs, and demonstrated that therapeutics can be specifically delivered to the cells of interest,” said Associate professor Elena Herrera Carrillo from the University of Amsterdam AMC. “These findings

HIV AIDS virus (in yellow) infecting a human cell – Credit: National Cancer Institute

represent a pivotal advancement towards designing a cure strategy.” The team has a long way to go before their cure will be available to patients, but said, “These preliminary findings are very encouraging’. Currently, HIV can be kept in check with anti-retroviral medication, but no one has actually been cured—although three patients receiving stem cell transplants for blood cancer were subsequently declared free of the disease when their HIV became undetectable. “We hope to achieve the right balance between efficacy and safety of this CURE strategy,” said Dr. Carrillo. “Only then can we consider clinical trials of ‘cure’ in humans to disable the HIV reservoir.“Our aim is to develop a robust and safe combinatorial CRISPR-Cas regimen, striving for an inclusive ‘HIV cure for all’ that can inactivate diverse HIV strains across various cellular contexts. Scientists Discover Potential HIV Cure that Eliminates Disease from Cells Using CRISPR-Cas Gene Editing

Read More........→March 26, 2024

'Love hormone' guides young songbirds in choice of 'voice coach'

Zebra finches are highly social birds and will press a lever in order to hear a recording of another Zebra finch singing. (Photo by Carlos Rodríguez-Saltos)

By Carol Clark: Oxytocin, the so-called “love hormone,” plays a key role in the process of how a young zebra finch learns to sing by imitating its elders, suggests a new study by neuroscientists at Emory University. Scientific Reports published the findings, which add to the understanding of the neurochemistry of social learning. “We found that the oxytocin system is involved from an early age in male zebra finches learning song,” says Natalie Pilgeram, first author of the study and an Emory PhD candidate in psychology. “It’s basic science that may lead to insights into the process of vocal learning across the animal kingdom, including humans.” “Our results suggest that the neurochemistry of early social bonds, particularly during language learning, may be relevant in studies of autism,” adds Donna Maney, a professor of neuroscience in Emory’s Department of Psychology and senior author of the study. Young male zebra finches learn to sing by listening to an adult male tutor that they choose to pay close attention to, normally their biological father or a “foster” father who nurtures them. This social process holds some similarities for how children learn to speak, making the birds a laboratory model for the neural underpinnings of social vocal learning. In the current paper, the researchers show how oxytocin, a hormone essential to social bonding, influences young finches exposed only to the songs of unfamiliar males. In experiments, blocking the young birds’ oxytocin receptors while they listened to a male biased the birds against that male’s song. Instead they preferred to listen to and eventually learn the song of a male they heard when their oxytocin receptors were allowed to function normally. The paper builds on previous work by the Maney lab regarding the hormonal and genetic influences on social behavior. Her lab is working with researchers at the Marcus Autism Center in Atlanta to maximize any potential translational impact of its research findings. Finding their voice: Zebra finches are highly social birds. In the wild they nest together in large colonies. Only adult males sing, primarily to court females. From the time they hatch, the males begin listening for song, and memorizing particular songs, even before they can actually sing one. “Up until around day 50, they are making little cheeps and warbles, what we call ‘subsong,’” Pilgeram explains. “It’s similar to human infants who begin to babble at around six months without actually talking.” During this sensitive listening phase, a male zebra finch pays closest attention to the song of its father, even though it can hear other adult males nearby. In a laboratory environment, research shows that if a biological father is removed from a cage before a male hatches and then substituted with a “foster father” that they can interact with, the young male will prefer the song of the foster father over other males it can hear. The young males demonstrate this preference by pressing levers that allow them to hear playback of different songs. Learning from their environment: “The young birds have got to learn all that they can from their environment,” Pilgeram says. “Just as during human development, the birds pay the closest attention to their immediate caregivers, on whom they rely for everything.” Around day 50, the young male finches enter puberty and what is called the “plastic song phase.” During this time, they practice their song motor skills and actively try to produce song. Although they begin to shift their attention away from their fathers and show a preference for hearing songs of other males, each young male still practices dad’s tune. By day 100, most male zebra finches are fully singing their father’s song. They have reached adulthood and their tune has “crystalized” into the song that they will sing for the rest of their lives. In previous research, the Maney lab found that the stronger the preference a male zebra finch shows for its father’s song during the early listening phase, the more closely its crystalized adult song will mimic that of the father. The role of oxytocin: For the current paper, the researchers wanted to test whether the oxytocin system played a role in that preference. The research centered on male juvenile zebra finches hatched in the lab. At day four, the fathers were removed from each of the youngsters’ cages so they were raised only by their mothers. The cages were enclosed in chambers that prevented the young birds from hearing song from other birds housed nearby. Beginning at day 27 in a young bird’s life, it was exposed to a series of tutoring sessions by two different adult male tutors that it had never heard. The tutor’s cage was placed next to the cage of the young bird, or pupil. When it was exposed to one of the tutors, the pupil was given a substance that blocked its oxytocin receptors from activating. When the young bird was exposed to the other tutor it received a control substance that allowed its oxytocin receptors to function normally. After completing a series of tutoring sessions, the pupils were presented with two different levers they could press in their cages. Pressing one lever was more likely to play the song they heard when their oxytocin receptors were blocked. The other lever was more likely to play the song they heard with normally functioning oxytocin. The results showed that early in their development, the juveniles favored the song that they heard when their oxytocin was not blocked. Building on past findings: “We also found that when their oxytocin was not blocked, the birds’ developmental milestones fit the same data curve as in our previous research,” Maney says. “They showed an early preference for the song of one tutor, then switched to preferring the other song during puberty.” The preference flattened out as they began singing the song of their chosen tutor, she adds. And the stronger the preference that they showed for the chosen tutor’s song during the early listening phase, the more closely their own adult song resembled that of the chosen tutor. The researchers also noted behavioral differences in the way the pupils and tutors interacted. With normally functioning oxytocin, a pupil pecked more often at the wall of its cage facing the tutor and more often preened in a fashion known to be associated with focused listening in the birds, compared to when its oxytocin was blocked. “Our results suggest that the oxytocin system is involved in how an animal decides where to focus its attention very early in its life,” Pilgeram says. Co-authors of the study include Carlos Rodríguez-Saltos, who received his doctorate from Emory and is now at Illinois State University; postdoctoral fellow Nicole Baran; research technicians Matthew Davis and Erik Iverson; and Emory undergraduates Sumin Lee, Emily Kim and Aditya Bhise. The work was funded by the National Science Foundation and the Silvio O. Conte Center for Oxytocin and Social Cognition. eScienceCommons: 'Love hormone' guides young songbirds in choice of.

Read More........→March 07, 2024