Articles selected from the Sept. 2007 issue of Molecular & Cellular Proteomics (Vol. 6, No. 9):
- Finding better ways to treat schistosomiasis, a tropical disease caused by a parasitic worm
- New insight into lethal shrimp viral disease
- How some algae tolerate very salty environments
- New technique detects protein changes with high sensitivity and selectivity
Finding better ways to treat schistosomiasis, a tropical disease caused by a parasitic worm
Researchers provide new details about the inner workings of a parasitic worm that causes a tropical disease called schistosomiasis, which leads to itchy skin, fever, chills, muscle aches, and liver disease that, in some cases, can be fatal. The new results may help design drugs or vaccines against the disease.
Schistosomiasis, a disease affecting up to 200 million people in Asia, Africa, and South America, is spread by parasitic worms called blood flukes that live in fresh water. The worms enter the human body through the skin and move to either the large intestine, small intestine, or the bladder. In the case of a species called Schistosoma mansoni, infection starts when larvae cross the skin and migrate to the large intestine, where they become adults and mate. The females then lay about 300 eggs a day in the blood vessels of the gut wall.
Stuart M. Haslam and colleagues compared the chemicals released by the larvae and eggs to understand how these chemicals help them to infect the human body. They found that although these chemicals are detected by the immune system, the parasite can still spread throughout the body.
In the case of the larvae, the scientists suggest that although the chemicals secreted prompt the human immune system to attack them, these chemicals act as a decoy so that the larvae themselves are not destroyed and can spread at will. The chemicals released by the eggs also attract molecules from the immune system but this time the chemicals fool the immune system into helping them escape from the body through feces and spread in the environment. These results provide new clues as to how the worms infect the human body and may help design drugs that target some of these chemicals in the future.
Article: “Glycomics Analysis of Schistosoma mansoni Egg and Cercarial Secretions,” by Jihye Jang-Lee, Rachel S. Curwen, Peter D. Ashton, Berangere Tissot, William Mathieson, Maria Panico, Anne Dell, R. Alan Wilson, and Stuart M. Haslam
MEDIA CONTACT: Stuart M. Haslam, Imperial College London, United Kingdom; tel: 44-207-594-5222; e-mail: s.haslam@imperial.ac.uk
New insight into lethal shrimp viral disease
Researchers report the most complete list so far of proteins present in a virus that causes severe shrimp mortality and significant economic losses to shrimp cultivation worldwide. This discovery could help understand how the virus is assembled and how it infects shrimps.
White spot syndrome is a viral infection of shrimps that is highly lethal and contagious, killing shrimps within 7 to 10 days. In 1993, this disease resulted in a virtual collapse of the Chinese shrimp farming industry and, by 1996, it had severely affected East and South Asia. The disease was reported in the United States in late 1995. Although no treatment for the disease is available yet, scientists have been studying the proteins that make up the virus to understand how it infects shrimps and avoids their immune system.
Choy-Leong Hew and colleagues showed that the virus is assembled by at least 58 proteins, including 13 proteins which are reported for the first time. The scientists also localized 33 of the proteins on the envelope, which is the membrane surrounding the virus, and nine proteins in the nucleocapsid, the core of the virus that contains its genetic material. Although Hew and colleagues do not know yet how these proteins work together, their localization in the virus is shedding light on some of their functions and will help determine which ones could be targeted by antiviral drugs.
Article: “Shotgun Identification of the Structural Proteome of Shrimp White Spot Syndrome Virus and iTRAQ Differentiation of Envelope and Nucleocapsid Subproteomes,” by Zhengjun Li, Qingsong Lin, Jing Chen, Jin Lu Wu, Teck Kwang Lim, Siew See Loh, Xuhua Tang, and Choy-Leong Hew
MEDIA CONTACT: Choy-Leong Hew, National University of Singapore; tel: 65-6516- 2692; e-mail: dbshewcl@nus.edu.sg or dbshead@nus.edu.sg
How some algae tolerate very salty environments
Researchers have identified unique proteins that allow a unicellular alga called Dunaliella salina to proliferate in environments with extreme salt content. These results might provide ways to help crop plants resist the progressive accumulation of salt in soil, which is a major limitation for agricultural productivity worldwide.
Since its discovery in 1905, D. salina has become a convenient model organism to study general mechanisms of salt adaptation in algae and plants. Previous studies have shown that in very salty environments, the alga’s plasma membrane -- which is a barrier that protects it from the outside environment -- undergoes major changes that are expected to play a role in salinity tolerance.
For the first time, Adriana Katz and colleagues have obtained a comprehensive overview of membrane-associated proteins and have shown how changes in the structure and composition of the membrane may help D. salina adapt to high salt content.
The scientists identified 55 proteins, many of which have not been discovered before. Some of these proteins strengthen the membrane against rupture, activate salt elimination, and enable the cells to sense and signal changes in salt levels in the environment. These results highlight proteins and mechanisms that play a key role in salinity tolerance and could pave the way for improving salinity tolerance in other organisms.
Article: “Salt-induced Changes in the Plasma Membrane Proteome of the Halotolerant Alga Dunaliella salina as Revealed by Blue Native Gel Electrophoresis and Nano-LC-MS/MS Analysis,” by Adriana Katz, Patrice Waridel, Andrej Shevchenko, and Uri Pick
MEDIA CONTACT: Adriana Katz, Weizmann Institute of Science, Rehovot, Israel; tel: 972-8-9342731; e-mail: adriana.katz@weizmann.ac.il
New technique detects protein changes with high sensitivity and selectivity
Scientists describe a new technique that can detect how proteins undergo changes inside a cell. The technique promises to improve our understanding of how proteins inside cells work and identify how some proteins are not modified properly in common diseases such as cancer and cardiovascular diseases.
In 2006, Ola Soderberg and colleagues established a technique called in situ proximity ligation assay (in situ PLA) to reveal protein-protein interactions in cells. The technique recognizes a target protein by binding a “probe” consisting of a pair of proteins attached to DNA onto the target protein. Then the DNA is replicated, producing a molecule that can be visualized under a microscope as a fluorescent spot – thus marking the presence of individual molecules in the target protein.
In the new study, Soderberg and colleagues developed a generalized version of the technique in which different probes can identify proteins that have undergone various changes in their structure. The researchers used this technique to detect a protein on the membrane of cells called platelet-derived growth factor receptor beta, which undergoes changes that will promote cell proliferation and movement. The technique is more sensitive and selective than other currently-used techniques, that is, it does not miss as many proteins as the other techniques do and the rate of mix-ups among the detected proteins is lower.
Article: “In Situ Detection of Phosphorylated Platelet-derived Growth Factor Receptor Beta Using a Generalized Proximity Ligation Method,” by Malin Jarvius, Janna Paulsson, Irene Weibrecht, Karl-Johan Leuchowius, Ann-Catrin Andersson, Carolina Wahlby, Mats Gullberg, Johan Botling, Tobias Sjoblom, Boyka Markova, Arne Ostman, Ulf Landegren, and Ola Soderberg
MEDIA CONTACT: Ola Soderberg, Uppsala University, Uppsala, Sweden; tel: 46-18-4714868; e-mail: ola.soderberg@genpat.uu.se
The American Society for Biochemistry and Molecular Biology is a nonprofit scientific and educational organization with over 11,900 members in the United States and internationally. Most members teach and conduct research at colleges and universities. Others conduct research in various government laboratories, nonprofit research institutions and industry. The Society’s student members attend undergraduate or graduate institutions.
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Journal
Molecular & Cellular Proteomics