Wednesday, November 11, 2020

You drive like a girl: Study shows gender bias in perceptions of ride-sharing performance

UNIVERSITY OF NOTRE DAME

Research News

Gender discrimination continues to plague organizations, and "gig economy" businesses, which have thrived over the last decade, are not immune, according to new research from the University of Notre Dame.

Gig economy businesses, including Uber and Airbnb, offer temporary positions to independent workers while relying on consumer ratings and reviews as part of their advertising and marketing strategies.

But the system has its flaws. While digital brokerages provide a more efficient method for the exchange of goods and services and an improved way for consumers to voice their opinions about the quality of work they receive, bias and discrimination can emerge as part of the review process, according to "How unbecoming of you: Online experiments uncovering gender biases in perceptions of ridesharing performance," forthcoming in the Journal of Business Ethics from Nathan Meikle, postdoctoral research and teaching associate, and Corey Angst, professor of information technology, analytics and operations at Notre Dame's Mendoza College of Business.

For the study, the team created an ostensibly new ride-sharing service called Agile Rides with a publicly available mock website to reinforce its legitimacy. The team asked 919 participants from the crowdsourcing website Amazon MTurk to help them understand what makes a good rider experience and to imagine going through a detailed experience based on a recent customer experience with a driver. The vignette varied by gender and whether the rider had a good or bad experience. Participants then rated driver performance.

"In the online experiment, we examined participants' perceptions of the drivers," said Meikle, who specializes in social perception and its implications for organizations. "When driver performance was high-quality, participants rated female and male drivers equally. However, when driver performance was low-quality, participants rated female drivers significantly lower than male drivers."

In the gig economy, the traditional manager-subordinate relationship is absent and drivers receive their "performance evaluations" from customers.

The team points out that because digital platforms represent new, rapidly growing work environments capable of subjecting workers to bias and discrimination from a wide number of evaluators, companies should -- for moral, strategic and legal reasons -- consider algorithmic weightings based on gender to combat discrimination.

"If customers discriminate against female drivers, the female drivers may be dismissed from the platform, or at least punished financially, for performing equal quality work as men," Meikle said. "When employees' compensation and job security depend on the ratings of customers rather than on the ratings of managers, companies should examine whether customers are rating employees fairly and adjust the ratings accordingly."

###

Co-authors of the study include Brad Greenwood from George Mason University and Idris Adjerid from Virginia Tech.

Posted by at No comments:

 

Study finds surprising diversity in early child care

Seven pathways to kindergarten identified in one state

OHIO STATE UNIVERSITY

Research News

COLUMBUS, Ohio - A new study of kindergarteners in one Midwestern state identified seven different pathways the children took in their early education and care before arriving at school.

The researchers were surprised by the diverse experiences that kids brought with them to kindergarten: While some received care only in their home or mainly in a child care center, others switched back and forth between different types of care, or had other arrangements.

This study is one of the few that has looked at kids' child care experiences all the way from birth to kindergarten, which allowed the researchers to capture the broad range of pathways, said Nathan Helsabeck, lead author of the study and a graduate research associate in educational studies at The Ohio State University.

"There are more nuanced differences in children's experiences before kindergarten than we originally thought," said Helsabeck, who is also an associate of Ohio State's Crane Center for Early Childhood Education and Policy.

"Looking at how children get to kindergarten could help us better consider what they need when they are entering school."

The study was published online in the journal Early Education and Development.

The study is part of a larger federally funded project designed to improve understanding of what happens in classrooms from pre-school to third grade. Data was collected from two large, suburban school districts including 25 schools, 152 classrooms and 3,472 students. A subsample of 568 students was used in this study.

One part of the study involved having parents complete questionnaires about their children's education and care from birth to 5 years old.

The researchers found that the largest group of children - 44% - received care only in the home over the first five years of life.

About 10% spent their first two years at home and in the third year became increasingly likely to be in center-based care. Another 7% spent these early years mostly in center-based care.

Those were the three pathways that the researchers had hypothesized would occur before they conducted the study, said Kelly Purtell, co-author of the study and associate professor of human sciences at Ohio State and faculty associate at the Crane Center.

But they found four other pathways as well: The second-largest group, 21%, were at home most of the early years, but were enrolled in a preschool or pre-kindergarten program in the last year before kindergarten. Other groups included children mostly cared for in informal settings (5%); those who went between home and informal care (8%); and those had both home and center care through the whole 5 years (5%).

Why were there so many different pathways?

"It reflects the patchwork availability of child care in this country," Purtell said.

"Child care for infants and young kids is expensive, so there are not a lot of affordable options for parents. Parents have to find different ways to take care of their kids while they work."

Helsabeck said he was particularly struck by the children whose care shifted from year to year, often from home to informal care, as their parents' situations changed.

"There was more than I expected in this category," he said.

"We need to realize that some kids face a lot of instability and their child care situations may change a lot. That may affect how they do in school."

The study also looked at how children who took different pathways did in kindergarten.

Findings did not show differences in test scores between children from different pathways. That was surprising, because most studies show an advantage to kids who spent more time in center-based care, Helsabeck said.

But he cautioned against making too much of that finding. It could be that there were not enough children in each of the seven groups to reveal differences in this study.

Results confirmed other studies that found children who spent most of their time in center-based care during their first five years had more teacher-reported social and behavioral problems in kindergarten.

That may be because these kids are already comfortable in school-like settings and are not as shy about acting out, Purtell said. They may also be more easily bored because for them, the experience is not novel.

"This is a real challenge for kindergarten teachers to navigate children who are brand new to this setting with those kids who are already familiar with the classroom setting," she said.

The researchers said that the seven pathways to kindergarten found in this study may not be the same everywhere.

"We looked at only two school districts in one state. That's not going to represent the whole country," Helsabeck said.

"But what we can take away from this is the wide range of experiences kids bring to kindergarten. It is going to affect how they do in school."

###

The research was supported by funding from the federal Institute of Education Sciences.

Other co-authors on the study, all from Ohio State, were Jessica Logan, assistant professor of educational studies; Laura Justice, professor of educational psychology and executive director of The Crane Center; and Tzu-Jung Ling, associate professor of educational studies and The Crane Center.

Contact:
Nathan Helsabeck,
Helsabeck.1@osu.edu

Kelly Purtell,
Purtell.15@osu.edu

Written by Jeff Grabmeier,
614-292-8457;
Grabmeier.1@osu.edu

Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.

 
Posted by at No comments:

Tuesday, November 10, 2020

 

Maunakea telescopes confirm first brown dwarf discovered by radio observations

Gemini North and IRTF confirm LOFAR discovery

ASSOCIATION OF UNIVERSITIES FOR RESEARCH IN ASTRONOMY (AURA)

Research News

 
Volume 90%
 

VIDEO: MAUNAKEA TELESCOPES CONFIRM FIRST BROWN DWARF DISCOVERED BY RADIO OBSERVATIONS view more 

CREDIT:

IMAGES AND VIDEOS:

INTERNATIONAL GEMINI OBSERVATORY/NOIRLAB/NSF/AURA/LOMBERG J, J. CHU/J. POLLARD, E. MASTROIANNI, LOFAR / ASTRON, S. BRUNIER/DIGITIZED SKY SURVEY 2.

MUSIC:

STELLARDRONE - AIRGLOW (HTTPS://STELLARDRONE.BANDCAMP.COM/)

...

A collaboration between the LOw Frequency ARray (LOFAR) radio telescope in Europe, the Gemini North telescope, and the NASA InfraRed Telescope Facility (IRTF), both on Maunakea in Hawai'i, has led to the first direct discovery of a cold brown dwarf from its radio wavelength emission. Along with paving the way for future brown dwarf discoveries, this result is an important step towards applying radio astronomy to the exciting field of exoplanets.

For the first time, astronomers have used observations from the LOFAR radio telescope, the NASA IRTF, operated by the University of Hawai'i, and the international Gemini Observatory, a Program of NSF's NOIRLab, to discover and characterize a cold brown dwarf. The object, designated BDR J1750+3809, is the first substellar object to be discovered through radio observations -- until now, brown dwarfs have been uncovered in large infrared and optical surveys. Directly discovering these objects with sensitive radio telescopes such as LOFAR is a significant breakthrough because it demonstrates that astronomers can detect objects that are too cold and faint to be found in existing infrared surveys -- maybe even large free-floating exoplanets.

"In this discovery, Gemini was particularly important because it identified the object as a brown dwarf and also gave us an indication of the temperature of the object," explained lead author Harish Vedantham of ASTRON, the Netherlands Institute for Radio Astronomy. "The Gemini observations told us that the object was cold enough for methane to form in its atmosphere -- showing us that the object is a close cousin of Solar System planets like Jupiter."

Brown dwarfs are substellar objects straddling the boundary between the largest planets and the smallest stars [1]. Occasionally dubbed failed stars, brown dwarfs lack the mass to trigger hydrogen fusion in their cores, instead glowing at infrared wavelengths with leftover heat from their formation. While they lack the fusion reactions that keep our Sun shining, brown dwarfs can emit light at radio wavelengths. The underlying process powering this radio emission is familiar, as it occurs in the largest planet in the Solar System. Jupiter's powerful magnetic field accelerates charged particles such as electrons, which in turn produces radiation -- in this case, radio waves [2] and aurorae.

The fact that brown dwarfs are radio emitters allowed the international collaboration of astronomers behind this result to develop a novel observing strategy. Radio emissions have previously been detected from only a handful of cold brown dwarfs -- and they have been known and cataloged by infrared surveys before being observed with radio telescopes. The team decided to flip this strategy, using a sensitive radio telescope to discover cold, faint sources and then perform follow-up infrared observations with a large telescope like the 8-meter Gemini North telescope to categorize them.

"We asked ourselves, 'Why point our radio telescope at cataloged brown dwarfs?'," said Vedantham. "Let's just make a large image of the sky and discover these objects directly in the radio."

Having found a variety of tell-tale radio signatures in their observations, the team had to distinguish potentially interesting sources from background galaxies. To do so, they searched for a special form of light that was circularly polarized [3] -- a feature of light from stars, planets, and brown dwarfs, but not from background galaxies. Having found a circularly polarized radio source, the team then turned to telescopes including Gemini North and the NASA IRTF to provide the measurements required to identify their discovery.

Gemini North is equipped with a variety of infrared instruments, one of which is usually kept ready to observe when an interesting astronomical opportunity arises. In the case of BDR J1750+3809, Gemini's mainstay infrared imager, the Near InfraRed Imager and spectrograph (NIRI) , was not available -- so Gemini astronomers took the unusual step of using the acquisition camera for the Gemini Near-Infrared Spectrograph (GNIRS) instead. Thanks to the careful work and foresight of Gemini staff, this camera provided deep, sharp, and accurate imaging at several infrared wavelengths.

"These observations really highlight the versatility of Gemini, and in particular the little-used 'keyhole' imaging capability of Gemini's GNIRS spectrograph," commented Gemini Observatory and University of Edinburgh astronomer Trent Dupuy -- a co-author of the research paper. The Gemini North observations were obtained via Director's Discretionary Time, which is reserved for programs needing small amounts of observing time with potentially high-impact results.

"This observation showcases both the flexibility and the power of the Gemini Observatories," said Martin Still of the National Science Foundation (NSF). "This was an opportunity where Gemini's design and operations enabled an innovative idea to develop into a significant discovery."

As well as being an exciting result in its own right, the discovery of BDR J1750+3809 could provide a tantalizing glimpse into a future when astronomers can measure the properties of exoplanets' magnetic fields. Cold brown dwarfs are the closest things to exoplanets that astronomers can currently detect with radio telescopes, and this discovery could be used to test theories predicting the magnetic field strength of exoplanets. Magnetic fields are an important factor in determining atmospheric properties and long term evolution of exoplanets.

"Our ultimate goal is to understand magnetism in exoplanets and how it impacts their ability to host life," concluded Vedantham. "Because magnetic phenomena of cold brown dwarfs are so similar to what is seen in Solar System planets, we expect our work to provide vital data to test theoretical models that predict the magnetic fields of exoplanets."

###

Notes

[1] The first unambiguous observation of a brown dwarf did not occur until 1995, after more than 30 years of theoretical predictions. The name of these objects was coined by the American astronomer Jill Tarter in reference to their expected color.

[2] The radiation emitted by the acceleration of charged particles in a magnetic field is referred to as cyclotron radiation. The name comes from the cyclotron, an early type of particle accelerator.

[3] Circularly polarized light is also used to create 3D movies.

More information

This research was presented in the paper Direct Radio Discovery of a Cold Brown Dwarf to appear in The Astrophysical Journal Letters.

The team is composed of H. K. Vedantham (ASTRON and University of Groningen), J. R. Callingham (Leiden Observatory and ASTRON), T. W. Shimwell (ASTRON and Leiden Observatory), T. Dupuy (University of Edinburgh and Gemini Observatory/NSF's NOIRLab), William M. J. Best (University of Texas and Visiting Astronomer at the NASA IRTF, Michael C. Liu (University of Hawai'i and Visiting Astronomer at the NASA IRTF), Zhoujian Zhang (University of Hawai'i), K. De (California Institute of Technology), L. Lamy (LESIA, Observatoire de Paris), P. Zarka (LESIA, Observatoire de Paris), H. J. A. Röttgering (Leiden Observatory), and A. Shulevski (Leiden Observatory).

NSF's NOIRLab (National Optical-Infrared Astronomy Research Laboratory), the US center for ground-based optical-infrared astronomy, operates the international Gemini Observatory (a facility of NSF, NRC-Canada, ANID-Chile, MCTIC-Brazil, MINCyT-Argentina, and KASI-Republic of Korea), Kitt Peak National Observatory (KPNO), Cerro Tololo Inter-American Observatory (CTIO), the Community Science and Data Center (CSDC), and Vera C. Rubin Observatory. It is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with NSF and is headquartered in Tucson, Arizona. The astronomical community is honored to have the opportunity to conduct astronomical research on Iolkam Du'ag (Kitt Peak) in Arizona, on Maunakea in Hawai?i, and on Cerro Tololo and Cerro Pachón in Chile. We recognize and acknowledge the very significant cultural role and reverence that these sites have to the Tohono O'odham Nation, to the Native Hawaiian community, and to the local communities in Chile, respectively.

Links

Research paper
ASTRON Press Release
Institute for Astronomy Press Release
Photos of Gemini North

Posted by at No comments:

 


Study: Remote learning adds pressure for teachers who work second shift as mothers

To relieve stress on teacher-mothers, researchers suggest improved parental leave policies, higher teacher pay and more equal distribution of household labor

UNIVERSITY AT BUFFALO

Research News

BUFFALO, N.Y - The transition to remote learning coupled with an unequal distribution of second-shift responsibilities has placed teachers who are also mothers under immense stress, according to new University at Buffalo research.

The study explored the experiences and challenges facing teacher-mothers who perform the roles of educator in the classroom and parent at home, while also typically carrying out more household labor than their partners.

These responsibilities are exacerbated by technology that blurs the line between work and home, inadequate parental leave policies and low teacher pay, says study co-author Julie Gorlewski, PhD, chair of the Department of Learning and Instruction in the UB Graduate School of Education.

"Balancing a teaching career and motherhood seems to be becoming more difficult," Gorlewski says. "Both roles carry an expectation of selfless nurturing and can result in physical and emotional exhaustion.

"The implications of this work are particularly relevant today, where the roles of motherhood and teacher are intensified by the shift to online learning as a result of the pandemic. Through a greater understanding of the lived experiences of teacher-mothers, this study can inform policy and practice to better support an integral segment of the education workforce."

The research was published in late October in Educational Studies.

Additional investigators include Mary A. Hermann, PhD, JD, first author and associate professor at Virginia Commonwealth University; Robyn Walsh, PhD, assistant professor at Capital University; Lindsay Kozachuk, PhD, assistant professor at Palm Beach Atlantic University; UB Graduate School of Education doctoral candidate Elizabeth Ciminelli; and Virginia Commonwealth University School of Education doctoral candidates Dana Brookover and Michael Deitz.

Fatigue from rising expectations

The researchers surveyed 12 teacher-mothers across the nation working in elementary, middle and high school settings. During the interviews, several themes emerged around work-life balance, problematic cultural norms and financial difficulties.

The participants shared the benefits of both roles, including how being a mother allowed them to better relate to the parents of their students, and how their work as a teacher provided them with greater awareness of their children's development. However, they also experienced frequent exhaustion from perpetual caregiving, says Gorlewski.

Technology and the transition to remote learning have raised expectations for teachers, who are expected to maintain contact with parents throughout the day and with their students at all hours. These demands build on the additional work teachers perform after school hours on grading and lesson planning.

Due to the COVID-19 pandemic, parents became responsible for homeschooling their children after many schools shuttered. For teachers who have children, this responsibility in the household often fell on them as the parent better trained to provide instruction, says Gorlewski.

Societal norms compound these pressures for mothers, who face elevated expectations at home, says Gorlewski. The research found that teacher-mothers reported performing more second-shift activities (household labor such as cooking, cleaning and child care) than their partners. Even when partners contributed more equally toward household labor, mothers typically engaged in significantly more mental labor planning and managing tasks, she says.

Homemaking standards are also magnified by portrayals of the perfect home on social media, and women are more likely to face judgement if their households do not match these heightened expectations, says Gorlewski.

Opportunity in a time of crisis

The researchers advocate for numerous policy changes to reduce the challenges faced by teacher-mothers, including improved parental leave and teacher pay.

Most participants reported that they had to use sick and personal days to earn pay while they were on maternity leave, leaving them with little to no time off after their child's birth to attend follow-up doctor's appointments. Teachers in their early career are particularly disadvantaged, says Gorlewski, as they have less accrued time off.

Due to the small amount of paid maternity leave and pressure to breastfeed from doctors, nurses and friends, some teacher-mothers reported having to pump at work between classes or while preparing the next day's lesson.

In addition to the second shift, many teacher-mothers also work a second job. One in every six teachers work a second job, and teachers are three times more likely than other professions to have multiple jobs, says Gorlewski.

The researchers encourage schools to enact mentoring programs for new mothers as well, as many participants appreciated being able to ask colleagues for advice on parenting and managing multiple roles.

The pandemic presents the opportunity for the nation to rethink the norms in education and family systems, and for teacher-mothers to renegotiate policies in the classroom and expectations in the household, says Gorlewski.

She calls on partners to take equal responsibility for second-shift labor, and suggests teacher-mothers abandon perfectionistic standards of child care and household maintenance on social media in favor of portrayals that show the messiness of authentic parenthood.

"This unanticipated and challenging global event has the potential to reveal some of the invisible work of mothers and educators," says Gorlewski. "Advocates can use these results to promote better norms and policies to support teachers and all working mothers."

Future research will compare the experiences of teacher-mothers with teacher-fathers and teachers who are not parents.

###

Posted by at No comments:

    Clinicians who prescribe unnecessary antibiotics fuel future antibiotic use

    HARVARD MEDICAL SCHOOL

    Research News

    Receiving an initial antibiotic prescription for a viral acute respiratory infection--the type of infection that doesn't respond to antibiotics--increases the likelihood that a patient or their spouse will seek care for future such infections and will receive subsequent antibiotic prescriptions, according to the findings of a study from Harvard Medical School and the Harvard T.H. Chan School of Public Health.

    The analysis, published online August 10 in Clinical Infectious Diseases, is believed to be the first to measure how variation in clinicians' antibiotic-prescribing patterns impacts patients' care-seeking behavior and antibiotic use in the long term.

    The findings are alarming because they suggest that once such prescriptions are given improperly for a viral infection they could become a gateway to more antibiotic use, the researchers said. Overuse of antibiotics is common. Previous studies have shown that nearly a quarter of antibiotics prescribed in an outpatient setting are given inappropriately for a diagnosis that does not warrant antibiotic treatment.

    "The choices physicians make about prescribing antibiotics can have long-term effects on when individual patients choose to obtain care," said lead study author Zhuo Shi, an HMS student in the Harvard-MIT Program in Health Sciences and Technology program. "A physician who prescribes an antibiotic inappropriately needs to understand that it's not just one little prescription of a harmless antibiotic but a potential gateway to a much bigger problem."

    The researchers used encounter data from a national insurer to analyze more than 200,000 initial visits for acute respiratory infections (ARIs) at 736 urgent care centers across the United States. At those centers, the researchers found that antibiotic prescribing rates for ARIs varied greatly among clinicians. In the highest quartile of prescribers, 80 percent of clinicians prescribed antibiotics for viral respiratory infections, and in the lowest, 42 percent did. To understand the impact of greater antibiotic prescribing, the researchers exploited the fact that patients do not choose their urgent care clinician. They are essentially randomly assigned to a clinician.

    In the year after an initial ARI visit, patients seen by clinicians in the highest-prescribing group received 14.6 percent more antibiotics for ARI--an additional three antibiotic prescriptions filled per 100 patients--compared with patients seen by the lowest-antibiotic-prescribing clinicians. The increase in patient ARI antibiotic prescriptions was largely driven by an increased number of ARI visits, an increase of 5.6 ARI visits per 100 patients, rather than a higher antibiotic prescribing rate during those subsequent ARI visits, the analysis showed.

    It's not that they were more likely to get antibiotics on repeat visits, the researchers found, simply that each return visit provided another opportunity to receive antibiotics.

    Why? In the case of a viral illness, patients wrongly attribute improvement in symptoms to the antibiotics. Naturally, next time they have similar symptoms they believe they need more antibiotics, the researchers said.

    "You'll hear lots of people say, 'Every winter I need antibiotics for bronchitis,'" said study senior author Ateev Mehrotra, an associate professor of health care policy in the Blavatnik Institute at Harvard Medical School and a hospitalist at Beth Israel Deaconess Medical Center. "The antibiotics don't actually help, but patients tend to perceive a benefit. The fancy term for this psychological phenomenon is 'illusionary correlation.'"

    "They get antibiotics and they feel better, not because the antibiotics have worked but because the infection has run its course," Mehrotra said. "The next time they become ill with similar symptoms they go back to the doctor to get another prescription."

    And the lesson isn't just learned by the patients themselves. Their spouses showed similar increases in visits and use of antibiotics for ARIs.

    The inappropriate use of antibiotics is a serious problem, the researchers said, noting that the practice increases spending unnecessarily, exposes patients to the risk of side effects for no medical reason and helps to drive the rise of antibiotic-resistant strains of bacteria.

    Using encounter data from a national insurer, the researchers categorized clinicians within each urgent care center based on their ARI antibiotic prescribing rate. The fact that urgent care patients are randomly assigned to a clinician ruled out the possibility that patients might be choosing a physician they knew would likely give them antibiotics for their viral infection, enabling the researchers to examine the impact of physician behavior on future patient behavior. The researchers examined the association between the clinician's antibiotic prescribing rate and the patients' rates of ARI antibiotic receipt as well as their spouses' rate of antibiotic receipt in the subsequent year. Several members of the research team first applied this method to examine pattens of opioid prescribing.

    While there is plenty of anecdotal evidence that some physicians say they give antibiotics to patients who request them to improve patient satisfaction, the researchers wanted to see whether and how physician prescribing behavior might be fueling the effect. They set out to answer the question: Could an initial prescription from a high-prescribing physician drive future antibiotic-seeking behavior among patients?

    It does, the analysis showed, and the study, the researchers said, underscores the ongoing need to educate clinicians and patients on judicious prescribing practices to reduce inappropriate prescribing, as well as the overall overuse of antibiotics and its associate risks.

    ###

    Support for this study was provided by the Office of the Director, National Institutes of Health (grant 1DP5OD017897).

    The following additional co-authors also contributed to the study: Michael Barnett, Department of Health Policy and Management, Harvard T.H. Chan School of Public Health, and Department of Medicine, HMS and Brigham and Women's Hospital; Anupam Jena, Department of Health Care Policy, HMS; Kristin Ray, Department of Pediatrics, University of Pittsburgh School of Medicine; and Kathe Fox, Department of Biomedical Informatics, HMS, and Department of Analytics and Behavior Change, Aetna/CVS Health.

    doi.org/10.1093/cid/ciaa1173

Posted by at No comments:

 

New study defines life cycle of a destructive plant pathogen 142 years after its discovery

AMERICAN PHYTOPATHOLOGICAL SOCIETY

Research News

IMAGE

IMAGE:  "USING CONFOCAL AND ELECTRON MICROSCOPIC IMAGING, WE PROVIDE COMPELLING EVIDENCE TO SUPPORT THE PROPOSED LIFE CYCLE OF P. BRASSICAE, MAKING IT MORE CONVINCING AND ACCEPTABLE TO THE COMMUNITY, " EXPLAINED LIU.... view more 

CREDIT: LIJANG LIU

Found in more than 60 countries, cruciferous clubroot disease is one of the most destructive plant diseases, causing so-called tumors on the roots of Brassicaceae crops and resulting in huge yield losses annually. The causal agent of this disease, Plasmodiophora brassicae, was first discovered by Russian biologist M. S. Woronin in 1878. Despite this early discovery, the life history of the pathogen remains a mystery.

"Although P. brassicae has been identified as the causal agent of cruciferous clubroot disease for 142 years, much earlier than the discovery of most plant pathogens, we were astonished that the full life cycle of this pathogen remained unclear when we started our investigation on this plant disease in 2015," said Lijang Liu, a scientist based at the University of Saskatchewan and the Chinese Academy of Agricultural Sciences. "The limited knowledge of P. brassicae biology greatly hinders the progress of studies on the cruciferous clubroot disease, which drove us to conduct this research."

The life history of the pathogen is very complex, comprising many different life forms. Liu and colleagues clarified the life history of P. brassicae in the root tissues of host Arabidopsis in a recently published article.

"Using confocal and electron microscopic imaging, we provide compelling evidence to support the proposed life cycle of P. brassicae, making it more convincing and acceptable to the community," explained Liu. "Notably, and most surprisingly, we discovered the existence of a sexual life stage of P. brassicae, starting from the fusion of two secondary zoospores within the infected epidermal cells."

Their other major findings include defining the development of zoosporangia and secondary zoospores and the sexual behavior between secondary zoospores in root epidermal cells and elucidating the growth and development of secondary plasmodia in root cortical cells, as well as the resultant physiological disturbances to host cortical cells.

"This research provides a fundamental understanding of the pathogen's biology as well as its cellular interactions with host plants. The knowledge gained from this investigation may further illuminate cellular mechanisms underlying host resistance and susceptibility and offers insights into the management practices against clubroot disease," said Liu. "Our article will help readers understand how such a lower eukaryotic microorganism performs a complex and sophisticated life history, giving a rise to a 'tumor' disease on plant roots."

Their article also highlights microscopic techniques coupled with live microbial fluorescence staining, which can be widely used in studying host-pathogen interactions. For more information, read "Refining the Life Cycle of Plasmodiophora brassicae" published in the October issue of Phytopathology.

###

Posted by at No comments:
Subscribe to: Posts (Atom)