Week In Science

Information about the first news item is credited to an online Science News article titled The Big Dry. It describes drought conditions afflicting Australia; a nation which experiences less rainfall than most countries even during wetter periods. The drought has affected the economy, agriculture, ecosystems and people of Australia. While rainfall has lessened, temperatures have increased. The effects have been predictable. There have been more wildfires and a decline in the water levels of lakes, rivers and reservoirs. There may have occurred a change in climate that will stay for quite some time, yet measures required to deal with the challenge are slow in coming.

An area of Australia known as the Murray-Darling River Basin is of special concern because this region of the country is the center of agriculture; yielding up to 40 per cent of the agricultural production of Australia even though it encompasses only 14 per cent of the country's area. The Murray-Darling River Basin is heavily reliant on irrigation. The numbers are not encouraging. When rainfall declines by 10 per cent there is a 30 to 40 per cent decline in the runoff into streams and rivers. Also disturbing is the fact that by the end of August of this year reservoir capacities were measured at 21 per cent while 71 per cent has been the historic measurement at the end of August.

What is causing the drought? Many attribute it, at least in part, to global warming. Others have pointed to climactic patterns that are cyclical in nature throughout history. We may be currently in transition. But there are also some specific phenomenon that may impact Australia uniquely.

Periodic warming of the eastern and central regions of the Pacific Ocean by a process that has come to be known as El Niño tends to make Australian weather hotter and drier. A similar process that cools ocean waters is known as La Niña. Australian weather patterns are very sensitive to both.

Land clearing may contribute to the drought. "A tree tends to cool the area of earth beneath it", explained a climate expert in the report. Removal of vast numbers of trees covering large areas may simply lead to a cumulative warming effect.

Compounding the effects of drought is a nearly 25 per cent increase in the population of Australia since 1990. Fewer water resources on the one hand are met with increased demands on the other. So increased conservation efforts have been the byword.

Along with humans wildlife in Australia has been adversely affected by the drought. Domino effects are probable as the decline in certain fauna causes a demise in animal populations that are dependent on it. Koalas seem to be a case in point. Their main food source is eucalyptus trees which have been dying off due to the drought. A whole food chain can be impacted by what occurs to vegetation.

There have been efforts to increase the availability of water. A desalination plant exists in Perth. Plans are afoot to build such plants in Melbourne and Sydney as well. The market place responds as it does everywhere. When supplies decline prices go up. This in turn leads to increased incentives to find water. Water is bought and sold like other commodities.

The climate challenge will not abate any time soon but Australians are resourceful people.

Citrus Trees and Viral Vectors

A stable RNA virus-based vector for citrus trees is the title of a paper appearing in Virology (Volume 368, Issue 1, 10 November 2007, Pages 205-216). It discusses virus-based vectors and focuses on strategies for development of a Citrus tristeza virus (CTV)-based vector. Vectors involve integrating DNA from one source into DNA from another. This in turn can be a means to induce the expression of genes or to silence them. This makes vectors an important tool in the study and manipulation of plant genomes and plant molecular biology. The paper also makes mention of another tool; a green fluorescent protein (GFP) used as a reporter. Scientists engineered different vector constructs and analyzed them with respect to a number of functions including replication, encapsidation, and their ability to infect, express GFP, and be maintained in citrus plants. Successful vectors were found to be unusually stable and after four years were still producing GFP fluorescence

Colony Collapse Disorder- Hunting Down a Suspect

An article in Nature titled Virus could be cause of disappearing bees by Emma Marris, (doi:10.1038/news070903-17), cites a recent investigation involving Diana Cox-Foster of Pennsylvania State University in University Park and others who sequenced microflora living inside bees. This includes bacteria, viruses, and fungi. The entire group of about 30 people worked for five months to locate sequences that might reveal clues as to the cause of Colony Collapse Disorder (CCD). This mysterious phenomenon entails the disappearance of honey bees. The problem is severe enough in the United States to cause major worries among farmers and ecologists. Colony Collapse Disorder was reported previously on this site in the article titled News About Honey Bees.

The study of genomes of a group of different organisms may have yielded an important clue as to the cause of CCD and that clue centers on a virus. The virus has a name and it is the Israeli acute paralysis virus (IAPV). The correlation between finding IAPV in a colony and finding CCD is as high as 96% according to Columbia University's Ian Lipkin. Researchers agree that this correlation is not proof that IAPV causes CCD but that it is a good suspect. It is possible that IAPV might take advantage of bees weakened by some other malady. The search continues and will involve infecting healthy bees with IAPV. There are other threats to bees which include other viruses, mites and pesticides. CCD could reflect the effects of multiple causes.

IAPV has been fingered before as the source of trouble in Israel. However bees in Israel died inside the hive rather than simply disappearing. IAPV was discovered by
Ilan Sela, a virologist at the Hebrew University of Jerusalem in Israel. There was hopeful news. Sela discovered that some Israeli bees appeared resistant to the virus. The reason may be because they had integrated partial IAPV sequences into their own genomes.

Outstanding Supernovas

The article Stellar Explosion Outshines Sun 100 Billion Times by Ker Than at Space.com reveals possible strategy changes in supernova exploration techniques that might result from some startling discoveries made by a single researcher.

Discovering the brightest stellar explosion might be a career landmark for most astronomers but discovering the two brightest ever recorded could only indicate the identity of a single person. His name is Robert Quimby, a Caltech postdoctoral researcher. Yet Quimby has accomplished one more thing which may be his most enduring legacy. He has motivated others to reconsider their searching techniques based on Quimby's own technique of looking for exploding stars in places considered low priority by others. Quimby looked at such non-standard locations as dwarf galaxies and galaxies having at their center active black holes. Those intending strategy shifts include heavyweights like the University of Michigan's Robotic Transient Search Experiment (ROTSE) project and the Sloan Digital Sky Survey Supernova Search.

The two supernovas discovered by Quimby are dubbed 2005ap and 2006gy. At peak luminosity 2005ap was 100 billion times brighter than the sun or about twice as bright as 2006gy. It is believed that Type II supernovas like 2005ap incur explosions when their cores collapse under their own weight.

One of the differences between 2005ap and 2006gy was the duration of brightness before dimming. 2005ap was like other Type IIs in that it brightened and dimmed within a period of a few days. On the other hand the brightness of 2006gy lasted for several weeks leading to speculation that prior to the supernova explosion the star had a mass of about 150 suns. Also interesting was a belief that the explosion itself involved antimatter in a theorized, but hitherto never observed, mechanism. What might make the physics explanations of the two supernovas different is an enigma.