Skip to main content
  • Submit
  • About
    • Editorial Board
    • PNAS Staff
    • FAQ
    • Rights and Permissions
    • Site Map
  • Contact
  • Journal Club
  • Subscribe
    • Subscription Rates
    • Subscriptions FAQ
    • Open Access
    • Recommend PNAS to Your Librarian
  • Log in
  • My Cart

Main menu

  • Home
  • Articles
    • Current
    • Latest Articles
    • Special Features
    • Colloquia
    • Collected Articles
    • PNAS Classics
    • Archive
  • Front Matter
  • News
    • For the Press
    • Highlights from Latest Articles
    • PNAS in the News
  • Podcasts
  • Authors
    • Information for Authors
    • Purpose and Scope
    • Editorial and Journal Policies
    • Submission Procedures
    • For Reviewers
    • Author FAQ
  • Submit
  • About
    • Editorial Board
    • PNAS Staff
    • FAQ
    • Rights and Permissions
    • Site Map
  • Contact
  • Journal Club
  • Subscribe
    • Subscription Rates
    • Subscriptions FAQ
    • Open Access
    • Recommend PNAS to Your Librarian

User menu

  • Log in
  • My Cart

Search

  • Advanced search
Home
Home

Advanced Search

  • Home
  • Articles
    • Current
    • Latest Articles
    • Special Features
    • Colloquia
    • Collected Articles
    • PNAS Classics
    • Archive
  • Front Matter
  • News
    • For the Press
    • Highlights from Latest Articles
    • PNAS in the News
  • Podcasts
  • Authors
    • Information for Authors
    • Purpose and Scope
    • Editorial and Journal Policies
    • Submission Procedures
    • For Reviewers
    • Author FAQ

New Research In

Physical Sciences

Featured Portals

  • Physics
  • Chemistry
  • Sustainability Science

Articles by Topic

  • Applied Mathematics
  • Applied Physical Sciences
  • Astronomy
  • Computer Sciences
  • Earth, Atmospheric, and Planetary Sciences
  • Engineering
  • Environmental Sciences
  • Mathematics
  • Statistics

Social Sciences

Featured Portals

  • Anthropology
  • Sustainability Science

Articles by Topic

  • Economic Sciences
  • Environmental Sciences
  • Political Sciences
  • Psychological and Cognitive Sciences
  • Social Sciences

Biological Sciences

Featured Portals

  • Sustainability Science

Articles by Topic

  • Agricultural Sciences
  • Anthropology
  • Applied Biological Sciences
  • Biochemistry
  • Biophysics and Computational Biology
  • Cell Biology
  • Developmental Biology
  • Ecology
  • Environmental Sciences
  • Evolution
  • Genetics
  • Immunology and Inflammation
  • Medical Sciences
  • Microbiology
  • Neuroscience
  • Pharmacology
  • Physiology
  • Plant Biology
  • Population Biology
  • Psychological and Cognitive Sciences
  • Sustainability Science
  • Systems Biology

In This Issue

PNAS December 4, 2018 115 (49) 12319-12320; https://doi.org/10.1073/iti4918115
  • Article
  • Figures & SI
  • Info & Metrics
  • PDF
Loading

Fine analysis of fur grooming in cats

Figure1
  • Download figure
  • Open in new tab
  • Download powerpoint

Cat grooming fur. Image courtesy of Candler Hobbs (Georgia Institute of Technology, Atlanta).

Domestic cats, which sleep on average 14 hours each day, spend up to a quarter of their waking hours grooming, which removes fleas, debris, and excess heat from fur. Cats’ tongues are carpeted with hundreds of sharp, scoop-shaped spines called filiform papillae, which are composed of keratin and spring into action during grooming. Alexis Noel and David Hu (pp. 12377–12382) used high-speed videos, CT scans, and grooming force measurements to explore how papillae aid grooming in postmortem tongue tissues from six cat species—domestic cat, bobcat, cougar, snow leopard, tiger, and lion. Experiments revealed that U-shaped hollows at the tips of papillae wick saliva from the mouth, each wicking action capturing up to 4.1 µL of saliva, tantamount to one-tenth of the drop of a typical eyedropper. Each lick of the tongue deposits nearly 50% of the fluid on the tongue onto fur and can deliver a substantive fraction of the cooling effect required for regulating body temperature. Further, the ease of grooming depends on whether papillae can penetrate fur to reach the skin, explaining why some species of domestic cats, such as long-haired Persian cats, are covered in fur that mats easily and is notoriously difficult to groom. Using the insights, the authors fashioned a cat tongue-inspired hairbrush that is easier to clean than human hairbrushes. According to the authors, the biologically inspired hairbrush might prove a handy implement to remove allergens from cat fur and apply cleaning lotions and medications on cat skin. — P.N.

Meteorite architecture suggests path to synthetic rare-earth magnets

Meteorites contain magnetic minerals, the crystalline structures of which reveal their thermal and magnetic histories. When certain iron–nickel alloys cool slowly, they can acquire nanoscale intergrowths of tetrataenite islands known as the “cloudy zone,” a metallurgic feature that can be exploited as a sustainable replacement for rare-earth permanent magnets. Joshua Einsle et al. (pp. E11436–E11445) combined high-resolution tomography with computer simulations to uncover the 3D architecture of the cloudy zone and describe the mechanism that imbues this nanostructure with its signature magnetic properties. The authors found that in the cloudy zone three distinct crystallographic variants—each a specific clustering of islands—dictate how magnetic information is encoded in the cloudy zone. In addition, the authors describe a model for how the cloudy zone acquires remanence—the permanent residual magnetism leftover from the meteorite parent body. Based on the findings, the authors developed a theoretical blueprint to adapt a recently developed low-temperature nitrogen insertion and topotactic extraction process to fabricate synthetic tetrataenite nanocomposite as a sustainable permanent magnetic material. The findings suggest that synthetic analogs of the cloudy zone can be used for industrial applications, according to the authors. — T.J.

Shape formation in plants

Figure2
  • Download figure
  • Open in new tab
  • Download powerpoint

Clamshell orchid (Prosthechea cochleata) with helical twisting petals. Image courtesy of Wikimedia Commons/D. Joshua Zampini.

The genetic and biomolecular mechanisms that give rise to complex 3D shapes in plant organs have been widely studied, but the role of biomechanical factors is unclear. Changjin Huang et al. (pp. 12359–12364) combined quantitative analyses of live plants with computational simulations to elucidate how mechanical stress and deformation influence plant leaf morphology. Within a leaf, growth strain, defined as the differential change in length between the center stem and a segment parallel to the stem, increased according to a power-law distribution from the center stem to the edge. Two parameters—the value of the power-law exponent that defines the strain profile and the maximum strain value—determined the leaf morphology in growth simulations. The authors constructed a phase diagram illustrating how each of four common leaf geometries—twisting, helical twisting, saddle bending, and edge waving—are associated with specific combinations of the parameters. By manipulation of the two key parameters, the authors reproduced the geometries in a hydrogel, the formation of which mimics plant growth. The results provide a general framework for understanding shape formation in plant organs and suggest ways to generate bio-inspired structures in soft materials, according to the authors. — B.D.

Exon skipping helps treat inherited ciliary disorder in animal model

Joubert syndrome (JS) is a genetic disorder marked by retinal dystrophy, brain defects, and renal failure. The condition is caused by defective cilia, which are fine cell-surface protuberances that perform crucial physiological functions. Given that few preclinical approaches have successfully corrected the underlying genetic defects, Simon Ramsbottom, Elisa Molinari, Shalabh Srivastava, et al. (pp. 12489–12494) used a strategy called exon skipping to offset the effects of a mutated exon, or coding stretch of DNA, in the CEP290 gene, implicated in JS. Using cells from a 14-year-old male patient, in whom a mutation in exon 41 of CEP290 led to abnormally long cilia in renal epithelial cells, the authors performed exon skipping with targeted antisense oligonucleotides, which are DNA snippets designed to trigger exon skipping. The intervention resulted in production of properly localized, full-length CEP290 protein and restoration of normal ciliary length 48 hours after treatment. Antisense-mediated skipping of a different exon in CEP290 in a mouse model of JS revealed that the approach can not only ameliorate defects in CEP290 protein production and cilia length but also reduce kidney cysts. Thus, exon skipping using antisense oligonucleotides can reverse pathological symptoms in patient-derived cells and an animal model of JS. According to the authors, the findings indicate the therapeutic promise of the strategy for inherited renal diseases tied to defective cilia. — P.N.

Competition among urban-adapted birds

Figure3
  • Download figure
  • Open in new tab
  • Download powerpoint

Blue Jay (Cyanocitta cristata), an urban-adapted species.

Urbanization affects many species worldwide, but it remains unclear why certain species persist in urban habitats while others do not. Paul Martin and Frances Bonier (pp. E11495–E11504) examined how competitive interactions between bird species affect the birds’ ability to survive and reproduce in cities. The authors compiled breeding occurrence data on nearly 300 bird species in 260 cities worldwide. Species were classified according to their propensity for breeding in cities, a measure of their degree of adaptation to urban environments, and whether they were dominant or subordinate in interactions with closely related species. Among urban-adapted species, dominant species were more widespread than subordinate species in cities where both types coincided. Dominant and subordinate species were equally prevalent in cities where their ranges did not overlap. The difference between dominant and subordinate urban-adapted species was largest in economically developed countries, while in developing countries, dominant and subordinate species were equally prevalent even when their ranges overlapped. According to the authors, the results suggest that asymmetric competition enables behaviorally dominant species to take advantage of urban habitats and exclude equally well-adapted subordinate species, and that economic development exacerbates this phenomenon. — B.D.

View Abstract
PreviousNext
Back to top
Article Alerts
Email Article

Thank you for your interest in spreading the word on PNAS.

NOTE: We only request your email address so that the person you are recommending the page to knows that you wanted them to see it, and that it is not junk mail. We do not capture any email address.

Enter multiple addresses on separate lines or separate them with commas.
In This Issue
(Your Name) has sent you a message from PNAS
(Your Name) thought you would like to see the PNAS web site.
Citation Tools
In This Issue
Proceedings of the National Academy of Sciences Dec 2018, 115 (49) 12319-12320; DOI: 10.1073/iti4918115

Citation Manager Formats

  • BibTeX
  • Bookends
  • EasyBib
  • EndNote (tagged)
  • EndNote 8 (xml)
  • Medlars
  • Mendeley
  • Papers
  • RefWorks Tagged
  • Ref Manager
  • RIS
  • Zotero
Request Permissions
Share
In This Issue
Proceedings of the National Academy of Sciences Dec 2018, 115 (49) 12319-12320; DOI: 10.1073/iti4918115
del.icio.us logo Digg logo Reddit logo Twitter logo CiteULike logo Facebook logo Google logo Mendeley logo
  • Tweet Widget
  • Facebook Like
  • Mendeley logo Mendeley
Proceedings of the National Academy of Sciences: 116 (8)
Current Issue

Submit

Sign up for Article Alerts

Jump to section

  • Article
    • Fine analysis of fur grooming in cats
    • Meteorite architecture suggests path to synthetic rare-earth magnets
    • Shape formation in plants
    • Exon skipping helps treat inherited ciliary disorder in animal model
    • Competition among urban-adapted birds
  • Figures & SI
  • Info & Metrics
  • PDF

You May Also be Interested in

Several aspects of the proposal, which aims to expand open access, require serious discussion and, in some cases, a rethink.
Opinion: “Plan S” falls short for society publishers—and for the researchers they serve
Several aspects of the proposal, which aims to expand open access, require serious discussion and, in some cases, a rethink.
Image credit: Dave Cutler (artist).
Several large or long-lived animals seem strangely resistant to developing cancer. Elucidating the reasons why could lead to promising cancer-fighting strategies in humans.
Core Concept: Solving Peto’s Paradox to better understand cancer
Several large or long-lived animals seem strangely resistant to developing cancer. Elucidating the reasons why could lead to promising cancer-fighting strategies in humans.
Image credit: Shutterstock.com/ronnybas frimages.
Featured Profile
PNAS Profile of NAS member and biochemist Hao Wu
 Nonmonogamous strawberry poison frog (Oophaga pumilio).  Image courtesy of Yusan Yang (University of Pittsburgh, Pittsburgh).
Putative signature of monogamy
A study suggests a putative gene-expression hallmark common to monogamous male vertebrates of some species, namely cichlid fishes, dendrobatid frogs, passeroid songbirds, common voles, and deer mice, and identifies 24 candidate genes potentially associated with monogamy.
Image courtesy of Yusan Yang (University of Pittsburgh, Pittsburgh).
Active lifestyles. Image courtesy of Pixabay/MabelAmber.
Meaningful life tied to healthy aging
Physical and social well-being in old age are linked to self-assessments of life worth, and a spectrum of behavioral, economic, health, and social variables may influence whether aging individuals believe they are leading meaningful lives.
Image courtesy of Pixabay/MabelAmber.

More Articles of This Classification

  • In this issue
  • In This Issue
  • In This Issue
Show more

Related Content

  • Targeted exon skipping of a CEP290 mutation rescues Joubert syndrome phenotypes in vitro and in a murine model
  • Differential growth and shape formation in plant organs
  • Species interactions limit the occurrence of urban-adapted birds in cities
  • Nanomagnetic properties of the meteorite cloudy zone
  • Cats use hollow papillae to wick saliva into fur
  • Google Scholar

Cited by...

  • No citing articles found.
  • Google Scholar

Similar Articles

Site Logo
Powered by HighWire
  • Submit Manuscript
  • Twitter
  • Facebook
  • RSS Feeds
  • Email Alerts

Articles

  • Current Issue
  • Latest Articles
  • Archive

PNAS Portals

  • Classics
  • Front Matter
  • Teaching Resources
  • Anthropology
  • Chemistry
  • Physics
  • Sustainability Science

Information

  • Authors
  • Editorial Board
  • Reviewers
  • Press
  • Site Map

Feedback    Privacy/Legal

Copyright © 2019 National Academy of Sciences. Online ISSN 1091-6490