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This indicates that the mutation originated in just one person who became the ancestor of all subsequent people in the world with blue eyes, according to a study by Professor Hans Eiberg and colleagues at the University of Copenhagen.

The study by researchers from the Wellcome Trust Sanger Institute and collaborators at La Trobe University in Melbourne and several other Australian institutes, challenges a previous theory that suggested an influx of people from India into Australia around 4-5 thousand years ago. This new DNA sequencing study focused on the Y chromosome, which is transmitted only from father to son, and found no support for such a prehistoric migration. The results instead show a long and independent genetic history in Australia.

Learn how the light dependent and light independent cycles work together to create glucose for plants. We'll also explain why this is so important for humans! Get ready to start cooking with photosynthesis.

Elephants have evolved extra copies of a gene that fights tumour cells, according to two independent studies, offering an explanation for why the animals so rarely develop cancer.

Plant species belonging to divergent branches of the evolutionary tree are known to have independently evolved caffeine production. According to scientists at Western Michigan University, caffeine-producing plants have taken a number of different biochemical routes to synthesize the stimulant. Coffee, tea, cocoa, orange, and guaraná plants make caffeine using an array of enzymes and substrates, the researchers reported in PNAS this week (September 20).

It's one of the big mysteries of cell biology. Why do mitochondria-the oval-shaped structures that power our cells-have their own DNA, and why have they kept it when the cell itself has plenty of its own genetic material? A new study may have found an answer. Scientists think that mitochondria were once independent single-celled organisms until, more than a billion years ago, they were swallowed by larger cells. Instead of being digested, they settled down and developed a mutually beneficial relationship developed with their hosts that eventually enabled the rise of more complex life, like today's plants and animals.

A link has been made between sleep apnoea - which is often indicated by loud snoring - and worse cancer outcomes in recent studies.

An elderly woman living independently with some help from her family is brought to the local emergency room because she is confused and vomiting. While her son suspects a stroke, a quick battery of laboratory tests indicates that her current problems are the result of impaired kidney function, an old-fashioned home remedy for ulcers, and her prescribed blood pressure medication. The combination of patient- and drug-related factors produces an acid-base disorder responsible for her confusion. This disorder further disrupts her kidney function. The case illustrates secretion and reabsorption processes in the kidney tubule which regulate plasma and urinary electrolytes (including calcium) and pH. The role of bicarbonate in maintaining systemic pH is emphasized. Interactions among the renal, respiratory and nervous systems in the regulation of systemic pH are also illustrated. Further, basic principles of pharmacotherapy and issues related to the appropriate use of medications are introduced. The case was developed for use in a physiology or human anatomy and physiology course, but it might be used in undergraduate nursing courses as well (e.g., pharmacology, pathophysiology).

All introductory biology textbooks, and many sophomore-level genetics textbooks as well, describe several classic experiments in molecular biology. This interrupted case study takes students through two of these classic experiments, namely, those by Griffith and Avery, McCarty and MacLeod that showed DNA to be the genetic material in Streptococcus pneumoniae, and the experiment by Meselson and Stahl that demonstrated DNA replication to be semiconservative. Engaging students with the experiments in a more exploratory manner can reinforce the nature of scientific discovery and the logic behind these findings. The case, which has been formatted as two separate exercises that can be used independently, was developed for use in introductory biology classes for biology majors. The material is accessible enough to also be useful for non-majors college biology or high school AP biology students.

This animated short video tells the story of Alfred Russel Wallace, who independently formulated the theory of evolution by natural selection at the same time as Charles Darwin.Co-directed by Flora Lichtman and Sharon Shattuck of Sweet Fern Production, the video tracks A. R. Wallace's life from growing up in England to his voyages with Henry Walter Bates and later adventures in the Malay Archipelago. The 8-minute video ends with an examination of the naturalist's legacy. (The video is presented here with permission from Sweet Fern Productions.)

31min video  The epic voyages of Darwin and Wallace led each to independently discover the natural origin of species and to formulate the theory of evolution by natural selection.

For years whale evolution was characterized by speculation and limited evidence. Evolution critics even focused on whales as a means to criticize evolutionary theory. Now whale evolution represents one of the best examples of "macroevolution." This "clicker case" uses this fascinating story of historical irony as a backdrop to the study of whale evolution. First, students study an array of whale fossils to learn how evolution is properly viewed as a branching, relationship-based process, not a linear, progressive, "chain-of-being." Using this view they learn how scientists seek to reconstruct past relationships and study transitional features, not search for "missing links." Students then learn that evidence for macroevolution relies on several lines of independent evidence from fossils, comparative anatomy, embryology, genetics, and paleoecology. With a focus on macroevolution, this case makes a critical contribution to evolution education. It could work well in a lower level undergraduate biology / evolution / paleontology course (non-majors or majors), or in an upper-level evolution course, perhaps early in the semester as a primer for related topics.

The Y chromosome is only one-third the size of the X. Although the Y has a partner in X, only the tips of these chromosomes are able to recombine. Thus, most of the Y chromosome is inherited from father to son in a pattern resembling asexual, not sexual, reproduction. No recombination means no reassortment, so deleterious mutations have no opportunity to be independently selected against. The Y chromosome therefore tends to accumulate changes and deletions faster than the X. Degradation doesn't occur in X chromosomes because during female meiosis, the X has the other X as a full partner in recombination.

IN recent weeks, two major medical organizations have issued independent warnings about toxic chemicals in products all around us. Unregulated substances, they say, are sometimes linked to breast and prostate cancer, genital deformities, obesity, diabetes and infertility. "Widespread exposure to toxic environmental chemicals threatens healthy human reproduction," the International Federation of Gynecology and Obstetrics warned in a landmark statement last month.

Researchers in a new study at the University of Edinburgh have honed in on five of 89 independent variations in human genetics that are believed to be responsible for autoimmune conditions, from celiac disease and multiple sclerosis to rheumatoid arthritis and asthma. Understanding how these mechanisms work could help scientists to develop new treatments. The team found that a mutation in the ADAR1 gene causes a defect in an "alarm system" in cells that normally protects the body from viruses and other infections by triggering the body's immune system to fight.

What does it mean to be 'alive'? At a basic level, viruses are proteins and genetic material that survive and replicate within their environment, inside another life form. In the absence of their host, viruses are unable to replicate and many are unable to survive for long in the extracellular environment. Therefore, if they cannot survive independently, can they be defined as being 'alive'?

"This modular case study tells the story of Dan and Annie, a married couple of Acadian ancestry who have a genetic form of deafblindness called Usher syndrome. They live in Southwest Louisiana, home of the largest population of DeafBlind citizens in the United States. Acadian Usher syndrome is caused by an allele of the USH1C gene that came to Louisiana with the first Acadian settlers from Canada who founded today's Cajun population. This allele's single nucleotide substitution creates an erroneous splice site that produces a defective cytoskeletal protein (harmonin) of the cochlear and vestibular hair cells and retinal photoreceptors. This splice site is the target of a promising gene therapy. The case study applies and connects Mendelian inheritance, chromosomes, cell division, vision and hearing, DNA sequences, gene expression, gene therapy and population genetics to a specific gene and its movement through generations of Dan and Annie's families.  After the introduction, each of the remaining sections can be used independently either for in-class team activities or out-of-class extensions or assignments over an entire year of introductory undergraduate biology. "

A common misconception is that Darwin suggested that something as complex as the eye could not have evolved through natural selection. While the misunderstanding often comes from an incomplete reading of his argument, we have long known that intermediate varieties of eyes (e.g., eyespots, cupped eyes, and complex camera-type eyes) exist in a variety of organisms. Eyes are so common that it was thought that they had evolved independently 40-60 times. More recent molecular work, however, has identified the role of Pax6 genes and their homologs in the formation of eyes during development. The basic information for eye formation appears to have been present in the common ancestor to all bilaterans, and perhaps may be more ancient than that. This interrupted case study examines the history of evidence for eye evolution from Darwin's initial postulates, through evidence of multiple intermediate forms, concluding in an examination of Pax6 homologs. The case is primarily for an introductory biology class but an additional section would be appropriate for upper-level evolution or developmental biology courses.

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