Comprehensive maps of neuronal connectivity provide a foundation for understanding the structure of neural circuits. In a circuit, neurons are diverse in morphology, electrophysiology, gene expression, activity, and other neuronal properties. Thus, constructing a comprehensive connectivity map requires associating various properties of neurons, including their connectivity, at cellular resolution. A commonly used approach is to use the gene expression profiles as an anchor to which all other neuronal properties are associated. Recent advances in genomics and anatomical techniques dramatically improved the ability to determine and associate the long-range projections of neurons with their gene expression profiles. These studies revealed unprecedented details of the gene–projection relationship, but also highlighted conceptual challenges in understanding this relationship. In this article, I delve into the findings and the challenges revealed by recent studies using state-of-the-art neuroanatomical and transcriptomic techniques. Building upon these insights, I propose an approach that focuses on understanding the gene–projection relationship through basic features in gene expression profiles and projections, respectively, that associate with underlying cellular processes. I then discuss how the developmental trajectories of projections and gene expression profiles create additional challenges and necessitate interrogating the gene–projection relationship across time. Finally, I explore complementary strategies that, together, can provide a comprehensive view of the gene–projection relationship.

The strength of reproductive isolation (RI) between two or more lineages during the process of speciation can vary by the ecological conditions. However, most speciation research has been limited to studying how ecologically dependent RI varies among a handful of broadly categorized environments. Very few studies consider the variability of RI and its effects on speciation at finer scales—that is, within each environment due to spatial or temporal environmental heterogeneity. Such variation in RI across time and/or space may inhibit speciation through leaky reproductive barriers or promote speciation by facilitating reinforcement. To investigate this overlooked aspect of speciation research, we conducted a literature review of existing studies of variation in RI in the field and then conducted individual-based simulations to examine how variation in hybrid fitness across time and space affects the degree of gene flow. Our simulations indicate that the presence of variation in hybrid fitness across space and time often leads to an increase in gene flow compared to scenarios where hybrid fitness remains static. This observation can be attributed to the convex relationship between the degree of gene flow and the strength of selection on hybrids. Our simulations also show that the effect of variation in RI on facilitating gene flow is most pronounced when RI, on average, is relatively low. This finding suggests that it could serve as an important mechanism to explain why the completion of speciation is often challenging. While direct empirical evidence documenting variation in extrinsic RI is limited, we contend that it is a prevalent yet underexplored phenomenon. We support this argument by proposing common scenarios in which RI is likely to exhibit variability and thus influence the process of speciation.

Surprisingly little attention has been given to the impact of selfing on speciation, even though selfing reduces gene flow between populations and affects other key population genetics parameters. Here we review recent theoretical work and compile empirical data from crossing experiments and genomic and phylogenetic studies to assess the effect of mating systems on the speciation process. In accordance with theoretical predictions, we find that accumulation of hybrid incompatibilities seems to be accelerated in selfers, but there is so far limited empirical support for a predicted bias toward underdominant loci. Phylogenetic evidence is scarce and contradictory, including studies suggesting that selfing either promotes or hampers speciation rate. Further studies are therefore required, which in addition to measures of reproductive barrier strength and selfing rate should routinely include estimates of demographic history and genetic divergence as a proxy for divergence time.

Mammalian astrocytes have regional roles within the brain parenchyma. Indeed, the notion that astrocytes are molecularly heterogeneous could help explain how the central nervous system (CNS) retains embryonic positional information through development into specialized regions into adulthood. A growing body of evidence supports the concept of morphological and molecular differences between astrocytes in different brain regions, which might relate to their derivation from regionally patterned radial glia and/or local neuron inductive cues. Here, we review evidence for regionally encoded functions of astrocytes to provide an integrated concept on lineage origins and heterogeneity to understand regional brain organization, as well as emerging technologies to identify and further investigate novel roles for astrocytes.

Over the past decades the zebrafish has emerged as an excellent model organism with which to study the biology of all glial cell types in nervous system development, plasticity, and regeneration. In this review, which builds on the earlier work by Lyons and Talbot in 2015, we will summarize how the relative ease to manipulate the zebrafish genome and its suitability for intravital imaging have helped understand principles of glial cell biology with a focus on oligodendrocytes, microglia, and astrocytes. We will highlight recent findings on the diverse properties and functions of these glial cell types in the central nervous system and discuss open questions and future directions of the field.

α-Synuclein (AS) is a small presynaptic protein that is genetically, biochemically, and neuropathologically linked to Parkinson's disease (PD) and related synucleinopathies. We present here a review of the topic of this relationship, focusing on more recent knowledge. In particular, we review the genetic evidence linking AS to familial and sporadic PD, including a number of recently identified point mutations in the SNCA gene. We briefly go over the relevant neuropathological findings, stressing the evidence indicating a correlation between aberrant AS deposition and nervous system dysfunction. We analyze the structural characteristics of the protein, in relation to both its physiologic and pathological conformations, with particular emphasis on posttranslational modifications, aggregation properties, and secreted forms. We review the interrelationship of AS with various cellular compartments and functions, with particular focus on the synapse and protein degradation systems. We finally go over the recent exciting data indicating that AS can provide the basis for novel robust biomarkers in the field of synucleinopathies, while at the same time results from the first clinical trials specifically targeting AS are being reported.

Approximately 8.5%–16.2% of childhood cancers are associated with a pathogenic/likely pathogenic germline variant—a prevalence that is likely to rise with improvements in phenotype recognition, sequencing, and variant validation. One highly informative, classical hereditary cancer predisposition syndrome is Li–Fraumeni syndrome (LFS), associated with germline variants in the TP53 tumor suppressor gene, and a >90% cumulative lifetime cancer risk. In seeking to improve outcomes for young LFS patients, we must improve the specificity and sensitivity of existing cancer surveillance programs and explore how to complement early detection strategies with pharmacology-based risk-reduction interventions. Here, we describe novel precision screening technologies and clinical strategies for cancer risk reduction. In particular, we summarize the biomarkers for early diagnosis and risk stratification of LFS patients from birth, noninvasive and machine learning–based cancer screening, and drugs that have shown the potential to be repurposed for cancer prevention.

Most childhood cancers possess distinct clinicopathological profiles from those seen in adulthood, reflecting their divergent mechanisms of carcinogenesis. Rather than depending on the decades-long, stepwise accumulation of changes within a mature cell that defines adult carcinomas, many pediatric malignancies emerge rapidly as the consequence of random errors during development. These errors—whether they be genetic, epigenetic, or microenvironmental—characteristically block maturation, resulting in phenotypically primitive neoplasms. Only an event that falls within a narrow set of spatiotemporal parameters will forge a malignant clone; if it occurs too soon then the event might be lethal, or negatively selected against, while if it is too late or in an incorrectly primed precursor cell then the necessary intracellular conditions for transformation will not be met. The precise characterization of these changes, through the study of normal tissues and tumors from patients and model systems, will be essential if we are to develop new strategies to diagnose, treat, and perhaps even prevent childhood cancer.

Redox reactions control fundamental biochemical processes, including energy production, metabolism, respiration, detoxification, and signal transduction. Cancer cells, due to their generally active metabolism for sustained proliferation, produce high levels of reactive oxygen species (ROS) compared to normal cells and are equipped with antioxidant defense systems to counteract the detrimental effects of ROS to maintain redox homeostasis. The KEAP1-NRF2 system plays a major role in sensing and regulating endogenous antioxidant defenses in both normal and cancer cells, creating a bivalent contribution of NRF2 to cancer prevention and therapy. Cancer cells hijack the NRF2-dependent antioxidant program and exploit a very unique metabolism as a trade-off for enhanced antioxidant capacity. This work provides an overview of redox metabolism in cancer cells, highlighting the role of the KEAP1-NRF2 system, selenoproteins, sulfur metabolism, heme/iron metabolism, and antioxidants. Finally, we describe therapeutic approaches that can be leveraged to target redox metabolism in cancer.

The broad application of noninvasive imaging has transformed preclinical cancer research, providing a powerful means to measure dynamic processes in living animals. While imaging technologies are routinely used to monitor tumor growth in model systems, their greatest potential lies in their ability to answer fundamental biological questions. Here we present the broad range of potential imaging applications according to the needs of a cancer biologist with a focus on some of the common biological processes that can be used to visualize and measure. Topics include imaging metastasis; biophysical properties such as perfusion, diffusion, oxygenation, and stiffness; imaging the immune system and tumor microenvironment; and imaging tumor metabolism. We also discuss the general ability of each approach and the level of training needed to both acquire and analyze images. The overall goal is to provide a practical guide for cancer biologists interested in answering biological questions with preclinical imaging technologies.

Vision is initiated by capturing photons in highly specialized sensory cilia known as the photoreceptor outer segment. Because of its lipid and protein composition, the outer segments are prone to photo-oxidation, requiring photoreceptors to have robust antioxidant defenses and high metabolic synthesis rates to regenerate the outer segments every 10 days. Both processes required high levels of glucose uptake and utilization. Retinitis pigmentosa is a prevalent form of inherited retinal degeneration characterized by initial loss of low-light vision caused by the death of rod photoreceptors. In this disease, rods die as a direct effect of an inherited mutation. Following the loss of rods, cones eventually degenerate, resulting in complete blindness. The progression of vision loss in retinitis pigmentosa suggested that rod photoreceptors were necessary to maintain healthy cones. We identified a protein secreted by rods that functions to promote cone survival, and we named it rod-derived cone viability factor (RdCVF). RdCVF is encoded by an alternative splice product of the nucleoredoxin-like 1 (NXNL1) gene, and RdCVF was found to accelerate the uptake of glucose by cones. Without RdCVF, cones eventually die because of compromised glucose uptake and utilization. The NXNL1 gene also encodes for the thioredoxin RdCVFL, which reduces cysteines in photoreceptor proteins that are oxidized, providing a defense against radical oxygen species. We will review here the main steps of discovering this novel intercellular signaling currently under translation as a broad-spectrum treatment for retinitis pigmentosa.

Background

In an evolving landscape of practices and policies, reviewing and incorporating the latest scientific evidence is necessary to ensure optimal clinical management for people with opioid use disorder. We provide a synopsis of the 2024 update of the 2018 National Guideline for the Clinical Management of Opioid Use Disorder, from the Canadian Research Initiative in Substance Matters.

Dis-Ease by Mariam Ghani uses strong visuals and compelling interviews to argue that how we see and describe disease affects how we deal with it, says Simon Ings

The World Health Organization has declared mpox a public health emergency of international concern – a new variant of the virus has caused an outbreak in Central and West Africa and spread to Sweden

The World Health Organization considers "gaming disorder" a condition, but researchers have now found that playing video games can boost well-being

Red and processed meat, and even poultry, seem to raise the risk of developing type 2 diabetes, according to a study of nearly 2 million adults, but not everyone is convinced

In children aged 6 to 11, long covid seems to often present as sleep problems or abdominal issues, while adolescents report fatigue and pain

Around 25 per cent of the world’s population has intestinal parasite infections – these could hinder the effectiveness of covid-19 vaccines, according to research in mice

Flu and other respiratory viruses seem to barely exist outside of winter, but covid-19 cases have consistently risen every summer over the past few years

DNA from mitochondria, the energy powerhouses inside cells, sometimes gets added to our genome – and the number of these mutations in the brain could be linked to ageing

Wastewater is a major reservoir for antibiotic resistance genes, but modified bacteria can chop up this DNA before the dangerous microbes reach people

When the fever, pains and pus-filled lesions of an mpox infection strike, how dangerous is it and how can it be treated?

A new variant of mpox is surging in Central Africa, raising concerns about how quickly it could spread further afield

A new test spots Lyme disease faster than the existing go-to approach and, if approved, could reduce the risk of complications

Climate change is extending mosquito season and helping to drive outbreaks of dengue fever, Oropouche virus and eastern equine encephalitis

I am one of millions of vapers in the UK, but growing evidence of the impact these e-cigarettes have on the environment means it may be time to quit, says Graham Lawton

Amid rising cases of mpox in Central Africa, it is important to uncover whether this virus causes symptoms even after the infection has cleared

Surrounding ourselves with greenery can do wonders for our physical and mental wellbeing. Kathy Willis reveals just what kinds of plants are best for our brains and bodies, and why

Promising new vaccines are designed to be given to patients at risk of developing Alzheimer's disease. If they perform well in clinical trials, they have the potential to one day rid society of dementia

Despite the limitations of Alzheimer's drugs like lecanemab, this new class of treatments and a group of experimental vaccines are paving the way to a world without dementia

Stem cells made in the lab may one day aid cancer treatment by reducing our reliance on donors

Drugs like Ozempic and Wegovy have unexpected effects on the brain, opening up potential new ways to treat depression, anxiety, addiction and Alzheimer’s

After an mRNA vaccine for mpox achieved promising results in monkeys, researchers say it could have several advantages over existing vaccines – but cold storage requirements mean it will be hard to roll out in some hard-hit countries

A network of neurons in the brain seems to be larger in people with depression, which could change how we think about the condition's causes

A band that measures the acidity of sweat could flag if athletes or manual workers are overexerting themselves

Narratives around addiction often reduce it to a series of poor choices, lack of values and weakness. This has real-world consequences, warns Anna Wolfe

An intricate atlas of the inner lining of the uterus could help researchers better understand conditions like endometriosis, infertility and abnormal menstruation

People with cancer may have understandable reasons to follow Australian supermodel Elle Macpherson in declining chemotherapy, but the odds aren’t in their favour, warns Elle Hunt

Rubbing a common yellow food dye onto a mouse's skin turns it temporarily transparent, so we can monitor its insides without harming the animal

Saline drops and sprays have already been linked to reduced cold symptoms in adults and now a study suggests they also work in children

They fight invaders, clear debris and tend neural connections, but sometimes microglia go rogue. Preventing this malfunction may offer new treatments for brain conditions including Alzheimer's