Current Biology最新文献

The acentrosomal spindle apparatus has kinetochore fibers organized and converged toward opposite poles; however, mechanisms underlying the organization of these microtubule fibers into an orchestrated bipolar array were largely unknown. Kinesin-14D is one of the four classes of Kinesin-14 motors that are conserved from green algae to flowering plants. In Arabidopsis thaliana, three Kinesin-14D members displayed distinct cell cycle-dependent localization patterns on spindle microtubules in mitosis. Notably, Kinesin-14D1 was enriched on the midzone microtubules of prophase and mitotic spindles and later persisted in the spindle and phragmoplast midzones. The kinesin-14d1 mutant had kinetochore fibers disengaged from each other during mitosis and exhibited hypersensitivity to the microtubule-depolymerizing herbicide oryzalin. Oryzalin-treated kinesin-14d1 mutant cells had kinetochore fibers tangled together in collapsed spindle microtubule arrays. Kinesin-14D1, unlike other Kinesin-14 motors, showed slow microtubule plus end-directed motility, and its localization and function were dependent on its motor activity and the novel malectin-like domain. Our findings revealed a Kinesin-14D1-dependent mechanism that employs interpolar microtubules to regulate the organization of kinetochore fibers for acentrosomal spindle morphogenesis.

Numerous kinds of pathogens have spread around the world along with human travellers. A study of sea journeys in the age of sail and steam shows that their global distribution is not just a matter of transport availability but has to be described as a complex network of ecological factors. A better understanding of these connections sheds light on historic pandemics and might help prepare for future ones. Michael Gross reports.

Hallucinations are vivid and transient experiences of objects, such as images or sounds, that occur in the absence of a corresponding stimulus.^{1,2,3,4,5,6,7,8,9} To understand the neurocomputational mechanisms of hallucinations, cognitive neuroscience has focused on experiments that induce false alarms (FAs) in healthy participants,^1,2,3,4,5,9 psychosis-prone individuals,^1,3,4 and patients diagnosed with schizophrenia.⁵ FAs occur when participants make decisions about difficult-to-detect stimuli and indicate the presence of a signal that was, in fact, not presented. Since FAs are, at heart, reports, they must meet two criteria to serve as an experimental proxy for hallucinations: first, FAs should reflect perceptual states that are characterized by specific contents^10,11,12 (criterion 1). Second, FAs should occur on a timescale compatible with the temporal dynamics of hallucinations^13,14 (criterion 2). In this work, we combined a classification image approach¹⁵ with hidden Markov models¹⁶ to show that FAs can match the perceptual and temporal characteristics of hallucinations. We asked healthy human participants to discriminate visual stimuli from noise and found that FAs were more likely to occur during an internal mode of sensory processing, a minute-long state of the brain during which perception is strongly biased toward previous experiences¹⁷ (serial dependency). Our results suggest that hallucinations are driven by dynamic predictive templates that transform noise into transient, coherent, and meaningful perceptual experiences.

Regenerative organisms such as plants must have specific signals that respond to damage and instruct remnant tissue to undergo repair. A recent paper identifies a long-sought candidate for the signal that links injury to regenerative programs.

Interview with Jennifer Botha, who studies the life history responses of extinct vertebrates to extreme environmental changes and is the Director of GENUS at the University of the Witwatersrand, South Africa.

The resurfacing of cutaneous wounds in mammals takes up to several weeks, but in zebrafish complete coverage is achieved within hours. New work uncovers that the rapid wound healing on zebrafish body surfaces involves the mobilization of fin-resident epithelial cells.

A new mitochondrial genome is the most gene-rich one found in a major division of eukaryotes - and it shares remarkable features with that of one of its most distant relatives.

In humans and other primates, vision is subserved by at least two parallel processing streams that are interconnected through a pathway known as the vertical occipital fasciculus. New research reveals that this white matter pathway may be a unique feature of the primate brain.

Predators often search for prey while moving through the environment, but there are important exceptions, including the way sedentary predators sometimes rely on signals for drawing prey to within striking distance^1,2. Some spiders, for instance, leave the remnants of previously-captured prey in their webs where they function as static lures that effectively attract a diverse array of additional prey³⁴⁵⁶. However, important questions remain concerning how specific the targeted prey may be and how dynamic, instead of static, signalling might be. With these questions as our rationale, we initiated research on Araneus ventricosus (L. Koch, 1878), an orb-weaving spider, as the predator and the firefly Abscondita terminalis males as the prey (Figure 1A-C). Using two lanterns situated on their abdomen (Figure 1D,F), A. terminalis males make female-attracting multi-pulse flash trains (Figure 1J), whereas sedentary females attract males by making single-pulse signals (Figure 1C,K) with a single lantern (Figure 1E,G). Drawing from extensive field observations, we propose that A. ventricosus practices deceptive interspecific communication by first ensnaring firefly males in its web and then predisposing the entrapped male fireflies to broadcast bioluminescent signals that deviate from female-attracting signals typically made by A. terminalis males and instead mimic the male-attracting signals typically made by females. The outcome is that the entrapped male fireflies broadcast false signals that lure more male fireflies into the web.

Members of the order Diptera, the true flies, are among the most maneuverable flying animals. These aerial capabilities are partially attributed to flies' possession of halteres, tiny club-shaped structures that evolved from the hindwings and play a crucial role in flight control. Halteres are renowned for acting as biological gyroscopes that rapidly detect rotational perturbations and help flies maintain a stable flight posture. Additionally, halteres provide rhythmic input to the wing steering system that can be indirectly modulated by the visual system. The multifunctional capacity of the haltere is thought to depend on arrays of embedded mechanosensors called campaniform sensilla that are arranged in distinct groups on the haltere's dorsal and ventral surfaces. Although longstanding hypotheses suggest that each array provides different information relevant to the flight control circuitry, we know little about how the haltere campaniforms are functionally organized. Here, we use in vivo calcium imaging during tethered flight to obtain population-level recordings of the haltere sensory afferents in specific fields of sensilla. We find that haltere feedback from both dorsal fields is continuously active, modulated under closed-loop flight conditions, and recruited during saccades to help flies actively maneuver. We also find that the haltere's multifaceted role may arise from the steering muscles of the haltere itself, regulating haltere stroke amplitude to modulate campaniform activity. Taken together, our results underscore the crucial role of efferent control in regulating sensor activity and provide insight into how the sensory and motor systems of flies coevolved.