Tuesday, November 27, 2012

The comeback of whooping cough

October issue of Microbe, published by ASM.

I read a very interestingand somewhat alarmingarticle in the October issue of the journal Microbe (formerly ASM News). In this article, Merry Buckley explains that whooping cough (aka pertussis), a childhood disease that has strongly declined since the introduction of a vaccine in the 1940s, is now on the rise again. We even see epidemics! says Buckley.

In 2012, in the USA, the number of pertussis cases is expected to be the highest in fifty years, approaching 40,000. Other countries such as Australia and the Netherlands also have high incidence of the diseasein the Netherlands, 6,000 cases were reported in 2009, against only 30 cases in 1980. The causes of this comeback are not fully understood, but scientists have gathered many clues.

Whooping cough is caused by Bordetella pertussis, a Gram negative bacterium belonging to the group beta Proteobacteria. It infects the respiratory system, causing a characteristic ‘whoop’ sound in sick children. Teens and adults can also be infected, although the symptoms are milder than in small children. In the prevaccine era, pertussis was a terrible threat, killing on average 5,000 children a year during the 1920s and 30s in the USA alone. At this period, the epidemics peaked following a cyclic pattern of a couple of years.

Sunday, November 18, 2012

Naming Nature by Carol Kaesuk Yoon

Published by W. W. Norton & Company
For a book that aims at a large readership, Naming Nature (2009) dares to explore a topic that seems anything but sexy at first sight: taxonomy. But we know better and we won’t turn away from the book, since the act of naming and classifying organisms is of course a very exciting activity! (No, I’m not kidding.)

In her book, Carol Yoon recapitulates the history of the discipline and presents the main scientific actors who contributed to the advance of taxonomy. She thus tells us about important figures:  Linné (Carolus Linnaeus), who is considered the founder of modern taxonomy, and who notably popularized the use of the binomial nomenclature (Felis catus and Escherichia coli, to name two lovable examples); Charles Darwin, who needs no introduction, and who revolutionized taxonomy by showing that species were not immutable; Ernst Mayr,  one of the main architects of the modern synthesis of evolutionary theory; Linus Pauling, the Nobel laureate chemist who had the brilliant idea of classifying organisms by looking at the amino acid sequence of hemoglobin; and Carl Woese, microbiologists’ modern hero, who classified organisms by looking at their DNA sequence and turned the tree of life topsy-turvy. Nothing new to me here, but, after all, this book is not written for biologists.

On the other hand, I learned facts that I was ignorant of (and this seems to be an inexhaustible category of facts...). For instance, I learned that it was Julian Huxley (member of a family in which each member is either a literary or a scientific genius) who coined the term ‘systematics’ and proposed to use it in place of taxonomy.

Wednesday, November 07, 2012

Plant pathogen focus: black Sigatoka as a worldwide threat to banana

Banana trees affected by Sigatoka in Malawi. Photo courtesy of APS.
Since I work in the department of plant pathology at UCDand even though I am not a plant pathologist myself!I decided to start a series of posts on microbes that cause plant disease, focusing on stories that are of economic and societal importance.

A couple of weeks ago, one of my colleaguehim a true plant pathologist, managed to scare me by claiming during a talk that banana could disappear in the not-so-distant future! The culprit? The fungus Mycosphaerella fijiensis: This ascomycete causes a disease (black Sigatoka) that damages the leaves of banana trees and reduces photosynthesis. Moreover, the fungus triggers a premature ripening that spoils the fruit. Together these effects of black Sigatoka provoke the loss of 50% or more of the fruit production. 
[I learnt a lot about black Sigatoka in an online article by Randy Ploetz on the website of the American Phytopathological Society (APS). When no other source is explicit, the information in this post comes from the Ploetz article. In general, the APS website is a great starting point for everything related to plant pathology!]