Booze may make men more sexually pushy

A US study, published in Aggressive Behaviour, has examined the acute effects of alcohol on men’s decisions about how to respond to sexual refusals in a dating simulation. In the study, 62 men in their 20s were randomly assigned to consume alcohol (target breath alcohol level, 0.080%) or no alcohol. Participants were encouraged to talk to a computer-simulated woman as if they were on a date, and they made choices from a list which included non-sexual and sexual options. The female agent was programmed to engage in some sexual activities but refuse others, and her refusals became more intense if participants persisted. As predicted, participants’ self-reported desire to have sex was positively associated with choosing activities in which the woman willingly engaged. Consensual sexual activities were positively associated with the number of times participants persisted after the woman refused. Alcohol moderated this relationship such that it was stronger for intoxicated men than sober men. The more sexual refusals participants received, the more hostile verbal comments they made to the woman. Contrary to the investigators’ predictions, this relationship was not moderated by alcohol. “We found that when a man is sexually interested in a woman, being intoxicated increases the likelihood that he will be more persistent pushing sex, even when she clearly refuses his advances. Furthermore, being sexually refused is associated with making hostile comments to the woman, regardless of whether or not the men were drinking,” said lead author Dr Jacqueline Woerner, currently at Yale University School of Medicine.

How HIV is shielded from immune attack

Scientists from UNSW Sydney and the UK have discovered that the human immunodeficiency virus (HIV) hijacks a small molecule from the host cell to protect itself from being destroyed by the host’s immune system. The finding, as well as details of the new strategy that enabled it, are published as back-to-back articles in eLife (here and here). They identify a new target for antiviral therapy against HIV and provide a method for testing and measuring new drugs designed to target the capsid – the virus’ protein shell. HIV’s capsid shields its genetic material from host defence mechanisms as it enters the cell and makes its way to the nucleus to establish infection. Using a new single-molecule microscopy technique – developed at UNSW’s Single Molecule Science in the School of Medicine – the research teams found that HIV specifically incorporates a small molecule from the host cell – inositol hexakisphosphate – to strengthen its capsid. The host inadvertently provides the key for the virus infecting it to lock down the protective shell, keeping the genetic cargo safe until it is released into the nucleus. “The HIV capsid falls apart within minutes once it’s isolated from the virus,” said Associate Professor Till Böcking, who led the UNSW team involved in both studies. “Our strategy lets us study exactly how a native capsid breaks apart in real-time without taking it out of the viral membrane.” The team engineered viruses with fluorescent tags to monitor the viral capsid using fluorescence microscopy. The researchers found that inositol hexakisphosphate, which is abundantly present inside mammalian cells, makes the capsid much stronger, stabilising it for 10–20 hours. Most of the currently approved HIV therapies target enzymes needed at different stages of the virus’ life cycle, but none of them are directed at the HIV capsid. New drug alternatives could improve the treatment of HIV with reduced toxic effects.

Study finds new brain pathway for escaping predators

Researchers from the University of Queensland have discovered how the zebrafish brain perceives and reacts to predators in a study that may unlock a longstanding mystery in neuroscience. School of Biomedical Sciences’ Associate Professor Ethan Scott said the processing of visual threats by the brain was an “interesting puzzle”. “Animals ranging from insects to humans will try to escape physically in response to a visual threat,” Dr Scott said. “But we don’t know how the brain recognises that the stimulus is threatening or decides to escape. Because zebrafish larvae are small and transparent, we examined activity across the entire brain using microscopes while visual threats were presented. This gave us a window into the brain’s responses.” The researchers showed zebrafish a large threatening shape moving towards them. “We found that visual information received from the eyes was broken down into components, such as shapes and brightness. These components then needed to be processed separately by two different parts of the brain for the fish to respond appropriately. When a visual threat appeared, cells in a particular part of the brain, the thalamus, lit up. But if we interfered with activity in the thalamus, the fish failed to recognise the threat and did not swim away. These results help to complete our picture of how different sensory information travels through the brain, and how the brain represents the outside world. Because these functions are abnormal in patients with certain psychiatric disorders, including autism spectrum disorder and schizophrenia, this work sets the stage for deeper studies into the disorders’ basic mechanisms.” The study was published in Neuron.

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