Saturday, August 10, 2013

Scientists unveil mechanism for ‘up and down’ in plants

Ghent, Belgium – VIB researchers at Ghent University discovered how the transport of an important plant hormone is organized in a way that the plant knows in which direction its roots and leaves have to grow. They discovered how the needed transport protein turns up at the underside of plant cells. The discovery helps us to understand how plants grow, and how they organize themselves in order to grow. The scientific journal Nature published the news in advance on its website.
Versatile hormone
It is known for a long time that the plant hormone auxin is transmitted from the top to the bottom of a plant, and that the local concentration of auxin is important for the growth direction of stems, the growth of roots, the sprouting of shoots. To name a few things; auxin is also relevant to, for instance, the ripening of fruit, the clinging of climbers and a series of other processes. Thousands of researchers try to understand the different roles of auxin.
In many instances the distribution of auxin in the plant plays a key role, and thus the transport from cell to cell. At the bottom of plant cells, so-called PIN proteins are located on the cell membrane, helping auxin to flow through to the lower cell. However, no one thoroughly understood why the PIN proteins only showed up at the bottom of a cell.
Endocytosis
An international group of scientists from labs in five countries, headed by Jirí Friml of the VIB-department Plant Systems Biology at Ghent University, revealed a rather unusual mechanism. PIN proteins are made in the protein factories of the cell and are transported all over the cell membrane. Subsequently they are engulfed by the cell membrane, a process called endocytosis. The invagination closes to a vesicle, disconnects and moves back into the cell. Thus the PIN proteins are recycled and subsequently transported to the bottom of the cell, where they are again incorporated in the cell membrane. It is unclear why plants use such a complex mechanism, but a plausible explanation is this mechanism enables a quick reaction when plant cells feel a change of direction of gravity, giving them a new ‘underside’.
 Gene technology
To see the path of the protein, the researchers used gene technology to make cells in which the PIN protein was linked to fluorescent proteins.  (This technology was rewarded with the Nobel Prize 2008 for chemistry.) Subsequently they produced cells in which the endocytosis was disrupted in two different ways. The PIN proteins showed up all over the cell membrane. When the researchers proceeded from single cells to plant embryos, the embryos developed deformations, because the pattern of auxin concentrations in the embryo was distorted. When these plants with disrupted endocytosis grew further, roots developed where the first leaflet should have been.

Read More @ Story Source:  http://www.vib.be/en/news/Pages/Scientists-unveil-mechanism-for-%E2%80%98up-and-down%E2%80%99-in-plants.aspx

Cells Eat Themselves Into Shape

The process cells use to ‘swallow’ up nutrients, hormones and other signals from their environment – called endocytosis – can play a crucial role in shaping the cells themselves, scientists at the European Molecular Biology Laboratory (EMBL) in Heidelberg, Germany, have found. The study, published today in Nature Communications, could help explain how the cells on your skin become different from those that line your stomach or intestine.
“We’re the first to show that endocytosis really drives changes in cell shape by directly remodelling the cell membrane,” says Stefano De Renzis, who led the work.

De Renzis and colleagues made the discovery by studying the fruit fly Drosophila, which starts life as a sac. The fly’s embryo is initially a single large cell, inside which nuclei divide and divide, until, at three hours old, the cell membrane moves in to surround each nucleus, so that in about an hour the embryo goes from one to 6000 cells. As this happens, cells change shape. The cell membrane starts off with lots of finger-like tendrils sticking out of the embryo, and in about 10 minutes it smoothes down to a flat surface, like a rubber glove transforming into a round balloon.

Read More @ Story Source:  http://www.embl.de/aboutus/communication_outreach/media_relations/2013/130807_Heidelberg/

Malaria Vaccine Found Safe and Protective

An investigational malaria vaccine has been found to be safe, to generate an immune system response, and to offer protection against malaria infection in healthy adults, according to the results of an early-stage clinical trial published Aug. 8 in the journal Science.
The vaccine, known as PfSPZ Vaccine, was developed by scientists at Sanaria Inc., of Rockville, Md. The clinical evaluation was conducted by researchers at the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health, and their collaborators at the Walter Reed Army Institute of Research and the Naval Medical Research Center, both in Silver Spring, Md.
Malaria is transmitted to humans by the bite of an infected mosquito. After the bite occurs, infectious malaria parasites in the immature, sporozoite stage of their life cycle first travel to the liver, where they multiply, and then spread through the bloodstream, at which time symptoms develop.
The PfSPZ Vaccine is composed of live but weakened sporozoites of the species Plasmodium falciparum, the most deadly of the malaria-causing parasites.
“The global burden of malaria is extraordinary and unacceptable,” said NIAID Director Anthony S. Fauci, M.D. “Scientists and health care providers have made significant gains in characterizing, treating and preventing malaria; however, a vaccine has remained an elusive goal. We are encouraged by this important step forward.”
The Phase I trial, which took place at the NIH Clinical Center in Bethesda, received informed consent from and enrolled 57 healthy adult volunteers ages 18 to 45 years who never had malaria. Of these, 40 participants received the vaccine and 17 did not. To evaluate the vaccine’s safety, vaccinees were split into groups receiving two to six intravenous doses of PfSPZ Vaccine at increasing dosages. After vaccination, participants were monitored closely for seven days. No severe adverse effects associated with the vaccine occurred, and no malaria infections related to vaccination were observed.
Based on blood measurements, researchers found that participants who received a higher total dosage of PfSPZ Vaccine generated more antibodies against malaria and more T cells—a type of immune system cell—specific to the vaccine.
To evaluate whether and how well the PfSPZ Vaccine prevented malaria infection, each participant—the vaccinees as well as the control group that did not receive vaccine – was exposed to bites by five mosquitoes carrying the P. falciparum strain from which the PfSPZ Vaccine was derived. This controlled human malaria infection procedure—a standard process in malaria vaccine trials—took place three weeks after participants received their final vaccination. Participants were monitored as outpatients for seven days and then admitted to the NIH Clinical Center, where they stayed until they were diagnosed with malaria, treated with anti-malarial drugs and cured of infection, or shown to be free of infection.
The researchers found that the higher dosages of PfSPZ Vaccine were associated with protection against malaria infection. Only three of the 15 participants who received higher dosages of the vaccine became infected, compared to 16 of 17 participants in the lower dosage group who became infected. Among the 12 participants who received no vaccine, 11 participants became infected after mosquito challenge.
 “In this trial, we showed in principle that sporozoites can be developed into a malaria vaccine that confers high levels of protection and is made using the good manufacturing practices that are required for vaccine licensure ,” said Robert A. Seder, M.D., chief of the Cellular Immunology Section of the NIAID Vaccine Research Center and principal investigator of the trial.
An important challenge in the continued development of PfSPZ Vaccine is that the vaccine currently is administered intravenously—a rare delivery route for vaccines. Previous studies at lower doses have shown that the more common intradermal (into the skin) and subcutaneous (under the skin) routes did not yield as strong an immune response as the intravenous route.
“Despite this challenge, these trial results are a promising first step in generating high-level protection against malaria, and they allow for future studies to optimize the dose, schedule and delivery route of the candidate vaccine,” said Dr. Seder.

A number of follow-up studies are planned, including research to evaluate the vaccine’s different dose schedules, possible protection against other Plasmodium strains and the durability of protection. The researchers may also evaluate whether higher doses administered subcutaneously or intradermally provide the same level of protection as that found in this study.

Story Source:  http://www.niaid.nih.gov/news/newsreleases/2013/Pages/PfSPZ.aspx

Wednesday, August 7, 2013

Newly-Discovered Rice Gene for Drought Resistance

An international team of crop scientists from Japan's National Institute of Agrobiological Sciences (NIAS) and the International Center for Tropical Agriculture (CIAT) have identified a gene in rice called Deeper Rooting 1 (DRO1) that gives plants deeper roots, resulting in triple yields during droughts. Rice is highly susceptible to drought because of its shallow roots, but the new study shows that by pointing roots down instead of sideways, the DRO1 gene results in roots that are nearly twice as deep as those of standard rice varieties.
The study's lead author Yusaku Uga, a researcher from NIAS, said "If rice adapts to or avoids drought conditions using deeper roots, it can get water and nutrients from the deep soil layers."
The team crossbred IR64, a high-yielding, but short-rooted and drought-prone commercial rice variety, with a deep-rooting upland rice variety from the Philippines, called Kinandang Patong. While IR64 already contains the DRO1 gene, it cannot produce the necessary proteins that enable the gene to function effectively. The scientists then combined the high yields of IR64, with the fully-functional DRO1 gene in Kinandang Patong.
The resulting plants had roots that were able to reach more than twice as deep as those of IR64. When tested under simulated conditions of moderate drought, IR64 yields were lessened by almost 60%, while the crossbreeds suffered only a 10% yield loss. Under extreme drought, IR64 completely failed, but the new rice plants continued to produce grain – about 30% of the yield of unstressed rice plants growing in normal conditions.
According to CIAT's Manabu Ishitani, "It's a very exciting discovery. We've known for some time that deeper roots can buy farmers extra time during periods of drought, but until now we haven't known which gene in rice is responsible for root architecture, or how to control it."

Read More @ http://www.ciatnews.cgiar.org/2013/08/06/newly-discovered-rice-gene-goes-to-the-root-of-drought-resistance/

Scientists to Use Gene Sequencing to Combat Witchweed, Other Parasitic Plants

An international research team is attempting to save billions of dollars in crop losses around the world by combatting witchweed and other parasitic plants through the use of gene sequencing and transfer. The said research is part of the Parasitic Plant Genome Project, funded by the National Science Foundation.


Scientists are identifying the genome-wide changes that have evolved among this group of wild plants which may have led to the development of their parasitic ability. John Yodder, professor from the University of California Davis and one of the researchers of the study added that they will identify critical parasite genes and pathways to use this information to develop parasite-resistant crops.
Read More @ http://news.ucdavis.edu/search/news_detail.lasso?id=10680
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