The development of bone structures in alligator eggs raised under varying oxygen concentrations creates a link to fossil records of the evolution of vertebrates and prehistoric atmospheric oxygen concentrations, according to a paper to be presented at the Earth System Processes 2 meeting in Alberta, Canada.
“Alligator eggs are an ideal self-contained unit for studying the effects of oxygen on development – they have a limited food source in the yolk and they are incubated i
Prehistoric big game hunters and not the last ice age are the likely culprits in the extinction of giant ground sloths and other North American great mammals such as mammoths, mastodons and saber-toothed tigers, says a University of Florida researcher.
Determining whether the first arrival of humans or the warm-up of the American continent at the end of the last Ice Age was responsible for the demise of prehistoric sloths has puzzled scientists because both events occurred at the
In their efforts to understand the complex biology of life, scientists often seek to isolate individual elements of the puzzle for study, to break the problem down to a more manageable size. Single genes and molecules are closely analyzed to better understand their specific interactions with other single entities within larger systems.
Sometimes, however, this approach misses important aspects of biology that depend on higher levels of organization. Sometimes putting a few of the piec
Alaska researchers seek clues to bird flu
While Alfred Hitchcock’s “The Birds” made many of us uneasy at the sight of amassing gulls years ago, today public health officials around the world are beginning to cast an equally uneasy eye toward migratory birds, especially in Alaska, following recent outbreaks of avian influenza in Southeast Asia and, last week, in Siberia.
Alaska is at the intersection of the Asian and North American flyways for migratory birds and sc
Study says Nicargua are last stop for endangered green turtles
Sea turtles that receive the highest protection in Costa Rica and other neighboring countries are dying by the thousands at the hands of unregulated – and unsustainable – commercial fishing in Nicaragua, according to a study by the Bronx Zoo based Wildlife Conservation Society.
The study, appearing in the latest issue of the journal Herpetologica, found that turtles tagged in Nicaragua have only little mor
Containment in a medium-sized Southeast Asian community may be possible, though challenging, if implemented early, researchers say
Though quick to caution about the many things that could go wrong, researchers say that it may be possible to contain a Southeast Asian outbreak of avian influenza in humans, buying precious time for the production of a vaccine.
Using a computer model to simulate an outbreak in a rural Southeast Asian population, the scientists have shown how
Prostate cancer, the second leading cause of cancer death for men in the United States, is caused by changes in several tummor suppressor genes including PTEN and p53. Up to 70 percent of men with prostate cancer have lost one copy of the PTEN gene at the time of diagnosis, and p53 is absent in a high number of patients with advanced prostate cancer.
Scientists at Memorial Sloan-Kettering Cancer Center have found an unexpected effect of the interaction of these two genes in early s
As anyone whose nerves have been jangled by a baby’s howl or who have been riveted by the sight of an attractive person knows, nature has evolved sensory systems to be exquisitely tuned to relevant input. A major question in neurobiology is how neurons tune the strength of their interconnections to optimally respond to such inputs.
Neuronal circuitry consists of a web of neurons, each triggering others by launching bursts of neurotransmitters at targets on receiving neurons
While researchers have long known the genetic defect underlying Fragile X syndrome, they are still tracing how that defect creates the complex mix of mental retardation, hyperactive behavior, attention deficits, and other problems in the disorder. Fragile X is particularly important because it is the most common single-gene cause of mental retardation–affecting about 1 in 4000 males and 1 in 8000 females in the U.S.
In an article in the August 4, 2005, issue of Neuron, researche
Using a novel analysis of the interactions among related genes, Duke University Medical Center researchers have uncovered some of the first evidence that complex genetic interactions account for autism risk. The Duke team found that the brain mechanism that normally stops or slows nerve impulses contributes to the disease.
The team’s findings implicate the so-called GABA receptor genes, which are genes that code for key components of “off switches” in the brain’s ne
Ecological specialization is an important process underlying the self-organization of ecosystems. Insight into this process leads to a better understanding of the structure and functioning of the real and complex ecosystems surrounding us. In an article in the September issue of The American Naturalist, Tineke A. Troost and colleagues address these fundamental issues, while focusing on a simple but common aquatic system.
Their research integrates three separate threads of modern ecolog
Helps give mentally disabled children a better lease on life
Reconstructing severe facial deformities in children with mental disabilities can be a hard decision for parents. Insurance companies may consider some operations to be only for cosmetic purposes and refuse to cover them. However, craniofacial plastic surgery, to correct abnormalities of the face, skull and neck, may give these children significant psychological, social and emotional benefits that can help them attain
Materials scientists working with biologists at the University of California, Santa Barbara have developed “smart” bio-nanotubes — with open or closed ends — that could be developed for drug or gene delivery applications.
The nanotubes are “smart” because in the future they could be designed to encapsulate and then open up to deliver a drug or gene in a particular location in the body. The scientists found that by manipulating the electrical charges of lipid bilayer membranes a
In territorial species with polygynous mating systems, reproductive success reflects phenotypic variation. At the gross level, such phenotypic variation can include that of body size and weapon morphology, as well as of weapon function and performance. In a study published in the September issue of The American Naturalist, A. Kristopher Lappin (Northern Arizona University) and Jerry F. Husak (Oklahoma State University) use the eastern collared lizard (Crotaphytus collaris ), a sexually dimorp
For many species, the ratio of sons to daughters a mother produces can have a profound effect on her evolutionary success. Too many sons, or too many daughters, may mean a female does not pass on as many copies of her genes to the next generation as another mother. The crucial determinant of sex ratio for many species will be how likely related individuals will interact, in particular whether brothers will be competing amongst themselves to mate with their sisters. This situation becomes increa
Long-distance dispersal (LDD) of wind-borne organisms is central to quantifying risk for transgenic escape and gene flow, control of pests and invasions, persistence in fragmented landscapes and species co-existence; yet LDD remains notoriously difficult to define, measure and model. This difficulty has shaped the current paradigm that the frequency and spatial extent of LDD events are almost impossible to predict.
In the September issue of The American Naturalist, G. G. Katul (Duke Uni
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