DNA gleaned from ancient coral unlocks clues about warming Boston Globe, United States - That is what Tim Shank discovered when he sent an underwater robot to sweep up a basket full of broccoli-like fossils from volcanoes under the sea. ...
Chicken or egg? Actually, hair came first MSNBC - Nov 11, 2008 ... birds and lizards, according to a new study that discovered genes associated with hair production in living green anole lizards and chickens. ...
Scientists Witness Flies Giving Live Birth RedOrbit, TX - Nov 25, 2008 Clues to how animals switch from laying eggs to live birth may be found in the well-studied species? ecology and genes. The fly is one of a dozen species of ...
Your genome and your physiology Ceylon Daily News, Sri Lanka - Nov 24, 2008 What is more, some scientists claim to have discovered genes that make some people homosexual or criminal or alcoholic. The truth, however, is neither so ...
Blame it on your DNA Taranaki Daily News, New Zealand - Nov 9, 2008 The German-speaking Austrian priest and scientist discovered genes through his studies on the inheritance of traits in pea plants back in the 1800s. ...
UPI NewsTrack Health and Science News United Press International - Nov 12, 2008 The scientists, in collaboration with Dr. William Snider at the University of North Carolina, discovered the mice missing the gene for ERK2 in neural crest ...
FOOD WEB STRUCTURE AND THE ROLE OF EPILITHIC BIOFILMS IN CAVE STREAMS - KS Simon, EF Benfield, SA Macko - Ecology, 2003 - esajournals.org ... 5 m/s) and uptake rates (0.04?0.23 mg m ... that biofilm C was passed through the entire
food web. This study shows that DOC and epilithic biofilms are important ...
Vertical Flux of Biogenic Carbon in the Ocean: Is There Food Web Control? - RB Rivkin, L Legendre, D Deibel, JE Tremblay, B … - Science, 1996 - sciencemag.org ... Vertical Flux of Biogenic Carbon in the Ocean: Is There Food Web Control? Richard ...
it. Thus, neither food web structure nor NP can predict ...
[PDF]SOUND, MUSIC AND TEXTUAL ASSOCIATIONS ON THE WORLD WIDE WEB - I Knopke - Proceedings of the International Symposium on Music …, 2004 - ee.columbia.edu ... Overlap Link Text 0.28 0.25 0.23 Surrounding Text 0.37 0.30 ... the same results between
the entire doc- ument of ... Sound files on the web are sparser than other ...
[PDF]Report on the TREC-8 Experiment: Searching on the Web and in Distributed Collections - J Savoy, J Picard - Proceedings of the Eighth Text REtrieval Conference (TREC-8) - unine.ch ... For the web track, we have conducted different experiments using various weighting ...
the best performance, significantly better that the vector- scheme (doc=L NU ... -
THE TROPHIC SIGNIFICANCE OF BACTERIA IN A DETRITUS-BASED STREAM FOOD WEB - RO Hall Jr, JL Meyer - Ecology, 1998 - JSTOR ... on the trophic role of bacteria in the stream food web. ... appeared to rely more on
streamwater DOC and less ... 0.09) Bacterial biomass 19 Dec 1994 0.23 (0.027) 0.14 ...
Genes, egg-1 and egg-2, required for fertilization discovered
Researchers at Rutgers have reported groundbreaking research on the genetics of fertility. They have discovered two genes, aptly named egg-1 and egg-2, required for fertilization to take place. The proteins encoded by these genes are similar to low density lipoprotein ( LDL ) receptors, known from cholesterol and fat metabolism but never before specifically implicated in fertilization.
A team led by Andrew Singson at the Waksman Institute of Microbiology at Rutgers, The State University of New Jersey, found that in the absence of these two genes, the vital process of fertilization came to a halt. " What we learn in studying fertilization is not only important for this event, but also for the functioning of other cells in our bodies and for understanding many of those processes," Singson said.
Fertilization can be a paradigm for gaining insight into how cells interact over the life and development of multicellular organisms because it is one of the most basic of cell-cell interactions. The underlying cell biology is going to be universal with applications even in infectious diseases, such as AIDS, where the virus passes its genetic material to the cells it infects just as fertilization transmits sperm DNA to the egg, Singson explained.
Fertilization has primarily been studied in mammals or select marine invertebrates; but Singson and his group have instead turned to the lowly roundworm Caenorhabditis elegans ( C. elegans ), the first multicellular organism to have had its genome completely sequenced.
In addition to having its genome sequence, C. elegans offers particular advantages as a model system – one from which results can be extrapolated to other organisms including humans. The millimeter-long worm is transparent, allowing a clear view of its internal workings, and its short life cycle permits researchers to chronicle developmental and hereditary factors over generations. These properties have enabled researchers to use C. elegans for fundamental discoveries in other fields ranging from cell death and life span regulation to nervous system structure and function.
But the worm's most important attribute as a model for this work may be its curious reproductive biology. Worms exist as males or hermaphrodites. When hermaphrodites are young they produce sperm and switch to produce eggs as adults. The Rutgers researchers were thus able to alter eggs in the hermaphrodites and use sperm from young males to test fertilization.
Genetic tools such as RNA interference and gene "knockout" mutants were used to see what would happen if worms lacked the function of egg-1 or egg-2 genes. The results were that the worms became sterile because fertilization had failed to occur. Normal sperm could no longer enter the eggs produced by egg-1 and egg-2 mutant hermaphrodites.
The traditional biochemical approach to studying fertilization has been to collect sperm and eggs and try to separate all the molecules or components of the cells, then discern how they might function in fertility. Singson admits that this has been productive, but he says that the definitive test for a role in fertilization or any biological process is to completely remove that molecule, or the gene that codes for it, and watch what happens.
" If you get infertility, then you know that the molecule is required for fertility, and this is our 'smoking gun.' Basically, we are asking the animal to tell us what it requires for its fertility, and then we try to understand how it works on a molecular level," he said. "Our use of this genetic approach, which hasn't been generally done in the past, is, indeed, groundbreaking."
Singson's group picked the two "egg" genes as an educated guess based on research Singson had previously conducted with a group of sperm genes. Mutations in sperm genes prevented the sperm from fertilizing normal eggs. The hope was that the sperm genes, together with the newly discovered egg genes, would be the "lock and key" that mediate normal fertilization.
For a sperm to enter an egg, the sperm has to recognize the egg and ignore other sperm or cells in the environment, Singson explained. Then there are interactions needed to get the surface membranes of both sperm and egg to fuse, a critical initial step in fertilization.
The results described in the Current Biology by Kadandale et al. confirm that along with the previously identified sperm genes, the egg-1 and egg-2 encoded molecules are a key component of the cellular machinery required for successful fertilization in worms.
Source: Rutgers, the State University of New Jersey, 2005
