Editor's note: Science Scan is a roundup of recently published biotechnology-relevant research.
Consider an anthill or nest, teeming with thousands of the social insects. Some male ants can avoid fights by emitting a ladylike odor, researchers report. The olfactory camouflage allows them to thrive alongside their more macho counterparts.
Males of the tropical ant Cardiocondyla obscurior come in two guises: wingless and aggressive or winged and docile. Both compete for access to virgin queens in the nest. Wingless males never leave this domicile, and fight each other until only one is left alive. Although the fighter males (ergatoids) attack and kill other ergatoids, they tolerate and even attempt to mount and mate with their winged enemies.
Winged males have it much easier in life. After being born, they hang around the nest for a week or two before sallying forth to seek mates in the outer world. Surprisingly, before dispersal, they are as successful as ergatoid males in attaining copulation with virgin nest-mate queens. Ergatoid males would therefore be expected to benefit from killing their winged rivals.
Meanwhile, winged males in the nest mate just as frequently as their wingless brethren, but get none of the hassle. This is because youthful winged males secrete fragrant chemicals very similar to the perfumes whipped up by virgin queens. Wingless males, aroused by the regal odor of cuticular hydrocarbons on the female body surface - which is one important way social insects communicate - often mount winged males. Some male garter snakes and rove beetles avoid aggression by mimicking females, but this usually puts off for-real females. Perhaps for the first time, such a strategy has been found to be just as good as the he-man approach.
That finding is reported in a fetchingly titled "Brief Communication" carried by Nature dated Oct. 31, 2002. It is headed: "Male ants disguised by the queen's bouquet." Its authors are at the University of Regensburg in Germany. "Here we show," their paper leads off, "that the winged males avoid the aggression of wingless males by mimicking the chemical bouquet of virgin queens, but their mating success is not reduced as a result."
The two-column paper concludes: "Cardiocondyla provides a new evolutionary context for chemical deception. It is deployed . . . by all young winged males and renders them simultaneously attractive to both sexes."
Calcium Indicted As Major Perpetrator Of Enzyme Cell Necrosis In Neurodegenerative Diseases
A somewhat less seductive in vivo report in the same Oct. 31, 2002, issue of Nature points to certain proteases that are crucial to cell death. Ergo, they could be potential targets for preventing or treating neurodegenerative disease. The article's title: "Specific aspartyl and calpain proteases are required for neurodegeneration in C. elegans [the nematode worm]." Its authors are molecular biologists at the Foundation for Research & Technology in Heraklion, Crete, Greece.
These two enzymes, the paper points out, are regulated by calcium, which may explain why disruptions to the concentration of calcium inside cells can cause them to sicken and die.
"Necrotic cell death underlies the pathology of numerous human neurodegenerative conditions," the paper points out, and continues: "In the nematode Caenorhabditis elegans, gain-of-function mutations in specific ion channel genes . . . evoke an analogous pattern of degenerative (necrotic-like) cell death in neurons that express the mutant proteins. An increase in concentrations of cytoplasmic calcium in dying cells . . . is thought to comprise a major death-signaling event. Here," it went on, "we report that neuronal degeneration inflicted by various genetic lesions in C. elegans requires the activity of the calcium-regulated proteases.
"Our findings show that distinct classes of proteases are involved in necrotic cell death and suggest that perturbation of intracellular concentrations of calcium may initiate neuronal degeneration by deregulating proteolysis. Similar proteases may mediate necrotic cell death in humans.
"These findings suggest," the paper concludes, "that, similar to apoptosis, necrotic cell death mechanisms are conserved from nematodes to humans, and they highlight specific executioner proteases as potential targets for therapeutic intervention in an effort to battle neurodegenerative disorders."
Caenorhabditis elegans Models Homo sapiens' Life Span Aging Process - But Only Up To A Point
For a millimeter-long worm that dies of old age in 12 to 18 days, the Caenorhabditis elegans nematode has served molecular biologists for the past 20 years as an ideal working model of human senescence. Its minute transparent body counts precisely 939 somatic cells, which handle all of its complex lifestyle activities, except reproduction. More than 50 mutations that extend the worm's life span have now been described, and the metabolic pathways regulated by these genes are being teased apart.
Deploying the modern analytical tools of molecular genetics, scientists at Rutgers, the State University of New Jersey at Piscataway, have checked out the worms through all the evidence of their life span and demise. The co-authors' report, in Nature dated Oct. 24, 2002, bears the title: "Stochastic [random, pure chance] and genetic factors influence tissue-specific decline in aging C. elegans."
Middle-aged worms run to fat as much as humans do, once youth has passed, the paper intimates. Its authors find that the worm's progressive muscle deterioration is similar to the loss of muscle mass and strength common in middle-aged people. Meanwhile, the C. elegans nervous system remains structurally intact.
A commentary accompanying the paper is headed, "The old worm turns more slowly." It makes the point that "competition for metabolic resources between processes such as growth, reproduction and cellular maintenance lies at the heart of the aging process. We knew," it added, "how long worms lived, but not how they died."