Biology

Coronavirus seems to reach the brain. What could this mean for us?

Genetics - 7 hours 30 min ago
From loss of smell to stroke, people with covid-19 are reporting strange neurological issues that challenge our understanding of the disease – and how to treat it
Categories: Biology

Structure of TBC1D23 N-terminus reveals a novel role for rhodanese domain

PLOS Biology (new articles) - 16 hours 30 min ago

by Dingdong Liu, Fan Yang, Zhe Liu, Jinrui Wang, Wenjie Huang, Wentong Meng, Daniel D. Billadeau, Qingxiang Sun, Xianming Mo, Da Jia

Members of the Tre2-Bub2-Cdc16 (TBC) family often function to regulate membrane trafficking and to control signaling transductions pathways. As a member of the TBC family, TBC1D23 is critical for endosome-to-Golgi cargo trafficking by serving as a bridge between Golgi-bound golgin-97/245 and the WASH/FAM21 complex on endosomal vesicles. However, the exact mechanisms by which TBC1D23 regulates cargo transport are poorly understood. Here, we present the crystal structure of the N-terminus of TBC1D23 (D23N), which consists of both the TBC and rhodanese domains. We show that the rhodanese domain is unlikely to be an active sulfurtransferase or phosphatase, despite containing a putative catalytic site. Instead, it packs against the TBC domain and forms part of the platform to interact with golgin-97/245. Using the zebrafish model, we show that impacting golgin-97/245-binding, but not the putative catalytic site, impairs neuronal growth and brain development. Altogether, our studies provide structural and functional insights into an essential protein that is required for organelle-specific trafficking and brain development.
Categories: Biology, Journals

Anticipation-induced delta phase reset improves human olfactory perception

PLOS Biology (new articles) - 16 hours 30 min ago

by Ghazaleh Arabkheradmand, Guangyu Zhou, Torben Noto, Qiaohan Yang, Stephan U. Schuele, Josef Parvizi, Jay A. Gottfried, Shasha Wu, Joshua M. Rosenow, Mohamad Z. Koubeissi, Gregory Lane, Christina Zelano

Anticipating an odor improves detection and perception, yet the underlying neural mechanisms of olfactory anticipation are not well understood. In this study, we used human intracranial electroencephalography (iEEG) to show that anticipation resets the phase of delta oscillations in piriform cortex prior to odor arrival. Anticipatory phase reset correlates with ensuing odor-evoked theta power and improvements in perceptual accuracy. These effects were consistently present in each individual subject and were not driven by potential confounds of pre-inhale motor preparation or power changes. Together, these findings suggest that states of anticipation enhance olfactory perception through phase resetting of delta oscillations in piriform cortex.
Categories: Biology, Journals

The evolution of the type VI secretion system as a disintegration weapon

PLOS Biology (new articles) - 16 hours 30 min ago

by William P. J. Smith, Andrea Vettiger, Julius Winter, Till Ryser, Laurie E. Comstock, Marek Basler, Kevin R. Foster

The type VI secretion system (T6SS) is a nanomachine used by many bacteria to drive a toxin-laden needle into other bacterial cells. Although the potential to influence bacterial competition is clear, the fitness impacts of wielding a T6SS are not well understood. Here we present a new agent-based model that enables detailed study of the evolutionary costs and benefits of T6SS weaponry during competition with other bacteria. Our model identifies a key problem with the T6SS. Because of its short range, T6SS activity becomes self-limiting, as dead cells accumulate in its way, forming “corpse barriers” that block further attacks. However, further exploration with the model presented a solution to this problem: if injected toxins can quickly lyse target cells in addition to killing them, the T6SS becomes a more effective weapon. We tested this prediction with single-cell analysis of combat between T6SS-wielding Acinetobacter baylyi and T6SS-sensitive Escherichia coli. As predicted, delivery of lytic toxins is highly effective, whereas nonlytic toxins leave large patches of E. coli alive. We then analyzed hundreds of bacterial species using published genomic data, which suggest that the great majority of T6SS-wielding species do indeed use lytic toxins, indicative of a general principle underlying weapon evolution. Our work suggests that, in the T6SS, bacteria have evolved a disintegration weapon whose effectiveness often rests upon the ability to break up competitors. Understanding the evolutionary function of bacterial weapons can help in the design of probiotics that can both establish well and eliminate problem species.
Categories: Biology, Journals

HIV-1 Tat-mediated astrocytic amyloidosis involves the HIF-1α/lncRNA BACE1-AS axis

PLOS Biology (new articles) - 16 hours 30 min ago

by Susmita Sil, Guoku Hu, Ke Liao, Fang Niu, Shannon Callen, Palsamy Periyasamy, Howard S. Fox, Shilpa Buch

Increased life expectancy of patients diagnosed with HIV in the current era of antiretroviral therapy is unfortunately accompanied with the prevalence of HIV-associated neurocognitive disorders (HANDs) and risk of comorbidities such as Alzheimer-like pathology. HIV-1 transactivator of transcription (Tat) protein has been shown to induce the production of toxic neuronal amyloid protein and also enhance neurotoxicity. The contribution of astrocytes in Tat-mediated amyloidosis remains an enigma. We report here, in simian immunodeficiency virus (SIV)+ rhesus macaques and patients diagnosed with HIV, brain region–specific up-regulation of amyloid precursor protein (APP) and Aβ (40 and 42) in astrocytes. In addition, we find increased expression of β-site cleaving enzyme (BACE1), APP, and Aβ in human primary astrocytes (HPAs) exposed to Tat. Mechanisms involved up-regulation of hypoxia-inducible factor (HIF-1α), its translocation and binding to the long noncoding RNA (lncRNA) BACE1‐antisense transcript (BACE1-AS), resulting, in turn, in the formation of the BACE1-AS/BACE1 RNA complex, subsequently leading to increased BACE1 protein, and activity and generation of Aβ-42. Gene silencing approaches confirmed the regulatory role of HIF-1α in BACE1-AS/BACE1 in Tat-mediated amyloidosis. This is the first report implicating the role of the HIF-1α/lncRNABACE1-AS/BACE1 axis in Tat-mediated induction of astrocytic amyloidosis, which could be targeted as adjunctive therapies for HAND-associated Alzheimer-like comorbidity.
Categories: Biology, Journals

Behavioral flexibility is associated with changes in structure and function distributed across a frontal cortical network in macaques

PLOS Biology (new articles) - 16 hours 30 min ago

by Jérôme Sallet, MaryAnn P. Noonan, Adam Thomas, Jill X. O’Reilly, Jesper Anderson, Georgios K. Papageorgiou, Franz X. Neubert, Bashir Ahmed, Jackson Smith, Andrew H. Bell, Mark J. Buckley, Léa Roumazeilles, Steven Cuell, Mark E. Walton, Kristine Krug, Rogier B. Mars, Matthew F. S. Rushworth

One of the most influential accounts of central orbitofrontal cortex—that it mediates behavioral flexibility—has been challenged by the finding that discrimination reversal in macaques, the classic test of behavioral flexibility, is unaffected when lesions are made by excitotoxin injection rather than aspiration. This suggests that the critical brain circuit mediating behavioral flexibility in reversal tasks lies beyond the central orbitofrontal cortex. To determine its identity, a group of nine macaques were taught discrimination reversal learning tasks, and its impact on gray matter was measured. Magnetic resonance imaging scans were taken before and after learning and compared with scans from two control groups, each comprising 10 animals. One control group learned discrimination tasks that were similar but lacked any reversal component, and the other control group engaged in no learning. Gray matter changes were prominent in posterior orbitofrontal cortex/anterior insula but were also found in three other frontal cortical regions: lateral orbitofrontal cortex (orbital part of area 12 [12o]), cingulate cortex, and lateral prefrontal cortex. In a second analysis, neural activity in posterior orbitofrontal cortex/anterior insula was measured at rest, and its pattern of coupling with the other frontal cortical regions was assessed. Activity coupling increased significantly in the reversal learning group in comparison with controls. In a final set of experiments, we used similar structural imaging procedures and analyses to demonstrate that aspiration lesion of central orbitofrontal cortex, of the type known to affect discrimination learning, affected structure and activity in the same frontal cortical circuit. The results identify a distributed frontal cortical circuit associated with behavioral flexibility.
Categories: Biology, Journals

Predictive whisker kinematics reveal context-dependent sensorimotor strategies

PLOS Biology (new articles) - 16 hours 30 min ago

by Avner Wallach, David Deutsch, Tess Baker Oram, Ehud Ahissar

Animals actively move their sensory organs in order to acquire sensory information. Some rodents, such as mice and rats, employ cyclic scanning motions of their facial whiskers to explore their proximal surrounding, a behavior known as whisking. Here, we investigated the contingency of whisking kinematics on the animal’s behavioral context that arises from both internal processes (attention and expectations) and external constraints (available sensory and motor degrees of freedom). We recorded rat whisking at high temporal resolution in 2 experimental contexts—freely moving or head-fixed—and 2 spatial sensory configurations—a single row or 3 caudal whiskers on each side of the snout. We found that rapid sensorimotor twitches, called pumps, occurring during free-air whisking carry information about the rat’s upcoming exploratory direction, as demonstrated by the ability of these pumps to predict consequent head and body locomotion. Specifically, pump behavior during both voluntary motionlessness and imposed head fixation exposed a backward redistribution of sensorimotor exploratory resources. Further, head-fixed rats employed a wide range of whisking profiles to compensate for the loss of head- and body-motor degrees of freedom. Finally, changing the number of intact vibrissae available to a rat resulted in an alteration of whisking strategy consistent with the rat actively reallocating its remaining resources. In sum, this work shows that rats adapt their active exploratory behavior in a “homeostatic” attempt to preserve sensorimotor coverage under changing environmental conditions and changing sensory capacities, including those imposed by various laboratory conditions.
Categories: Biology, Journals

Poll reveals declining trust in UK government before Cummings crisis

Genetics - Tue, 2020-05-26 19:30
The latest coronavirus news updated every day including coronavirus cases, the latest news, features and interviews from New Scientist and essential information about the covid-19 pandemic
Categories: Biology

UK plans to further ease lockdown as new case rate remains high

Genetics - Tue, 2020-05-26 18:09
Despite the UK having far more new daily coronavirus cases than many other countries, further restrictions are expected to be lifted in England and Scotland
Categories: Biology

Asteroid that killed the dinosaurs hit just right for maximum damage

Genetics - Tue, 2020-05-26 18:00
The asteroid impact that formed Chicxulub crater and is linked to the extinction of the dinosaurs seems to have come in at the optimal angle to cause as much destruction as possible
Categories: Biology

Space Force review: The sitcom is almost as comical as the real thing

Genetics - Tue, 2020-05-26 10:01
The newly created US Space Force has provided a lot of laughs since its inception. A TV satire about it is almost as funny as the original, says Simon Ings
Categories: Biology

The sun may have formed because a small galaxy passed by the Milky Way

Genetics - Mon, 2020-05-25 18:00
A small galaxy called Sagittarius passed close to the Milky Way four times in the past 6 billion years, which may have caused periods of intense star formation
Categories: Biology

Behavioural science advisers express concern over Cummings crisis

Genetics - Mon, 2020-05-25 16:51
Leading behavioural scientists have expressed concern that the Dominic Cummings scandal could encourage people to disregard the UK’s coronavirus restrictions
Categories: Biology

A blood test could reveal how quickly or slowly you are ageing

Genetics - Mon, 2020-05-25 08:00
A blood test that measures changes in gene expression to estimate a person's age can also help predict whether a person is more likely to develop a chronic disease
Categories: Biology

All five of Earth's largest mass extinctions linked to global warming

Genetics - Fri, 2020-05-22 20:04
There have been five particularly large extinction events in Earth’s history, and for the first time all of them have been linked to global warming
Categories: Biology

Fake news gets shared more when it is angry and anxiety-inducing

Genetics - Fri, 2020-05-22 12:00
An analysis of fake news shared on social media service Weibo has found that posts flagged as fake news were more like to contain words associated with anger than real news
Categories: Biology

Which animals are benefitting from coronavirus lockdowns?

Genetics - Fri, 2020-05-22 11:22
It isn’t true that dolphins have returned to Venice, but bees are benefitting from lower air pollution, and a drop in ocean traffic could be good for whales
Categories: Biology

Coronavirus drugs: how well is the hunt for covid-19 treatments going?

Genetics - Fri, 2020-05-22 00:56
Hundreds of trials are testing known antiviral drugs, as well as those that block immune responses to coronavirus, but we may need to build a covid-19 treatment from scratch
Categories: Biology

Bees force plants to flower early by cutting holes in their leaves

Genetics - Thu, 2020-05-21 21:00
Hungry bumblebees can make plants flower up to a month earlier than usual by cutting holes in their leaves, which may help them adapt to climate change
Categories: Biology

Population of world’s strangest plant threatened by climate change

Genetics - Thu, 2020-05-21 20:10
Hardy and resilient welwitschia is unlike anything else on Earth, but climate change appears to be pushing these plants past their limits
Categories: Biology