Snippets from Science

• Malaria kills more than a million people each year. The vectors of the malaria parasite are mosquitoes. One group of malaria-carrying mosquitoes has the scientific name of Anopheles gambiae. Unfortunately, this group consists of six identical appearing species that require molecular tests to distinguish them apart. The six forms mate independently, but how do the sexes of each group find each other when they all look alike? A British medical entomologist isolated larvae of two forms of A. gambiae and raised them in the lab. He stuck a short piece of wire to the backs of adults and paired them according to opposite sex near a very sensitive microphone. When he held them within an inch or so of each other and began “buzzing” their wings. By speeding up or slowing down their wing beats, they changed the frequency (“music”?) of their high-pitched buzzing. Pairs of mosquitoes adjusted their wing beats to each other, or harmonized, only if they belonged to the same “subspecies.” And when harmonizing, a male and female of the same subtype reached their legs out toward the other. Finding each molecular mate by harmonizing helps keep the six subgroups genetically distinct.

(Helen Fields, in scienceNOW, Jan. 13, 2010)

• All the oxygen surrounding planet earth is generated by plants. Marine plants generate 70 – 80 percent of the oxygen, while the rest is generated by terrestrial plants. The aquatic plants are photosynthetic algae, one of which is Great Lakes Cladophora. While we may appreciate the oxygen produced by Cladophora, things have gotten completely out-of-balance, and the amount of Cladophora has increased dramatically. As the algae die they wash up on our shorelines and, literally, stink up the place. The increase can be traced in part to the filter-feeding activities of zebra and quagga mussels, causing populations of bacteria and plankton to diminish. This greatly clarifies lake water and allows sunlight to penetrate deeper and deeper. The more sunlight, the larger the population of algae. Another factor is “fertilizer” for algal growth in the form of phosphorous-containing runoff from farms and lawns. As if this weren’t enough, the mussels themselves excrete concentrated amounts of phosphorous. The good news, more oxygen for the atmosphere. The bad news, larger piles of decaying Cladophora. (Adrianne Appel, in IPS News, Jan. 12, 2010)

• The concentration of PCBs and DDT in top predator fish continues to drop in Lake Michigan, reflecting a gradually declining amount of these toxins in the lake itself. However, the amounts found in these fish remain elevated over the “safe” threshold, and state and federal regulatory agencies advise limiting the amount of fish eaten from Lake Michigan waters. (epa.gov/glindicators/fishtoxins/topfish)

• How important is maintaining diversity among plants and animals? Consider that more than 50 percent of modern medicines and more than 90 percent of traditional medicines are derived from wild plants and animals. Over 70,000 plant species have contributed to the development of drugs to fight human illness, and “new” plant samples from all over the world are being analyzed for chemicals that may be of medical importance. The action of toxins isolated from snakes, bees, and jellyfish may provide clues to better treatments of diseases of the nervous system. The bottom line: biodiversity may someday save your life. (conservation.org/learn/health.org, Jan. 12, 2010).