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Well, it didn't happen only to you. It is often surprising how difficult it can be to find concrete biological numbers, even for properties that have been measured numerous times. To help solve this for one and all, BioNumbers (the database of key numbers in molecular biology) was created. Along with the numbers, you'll find the relevant references to the original literature, useful comments, and related numbers.

In a paper this week in Science, Vogelstein and Cristian Tomasetti, who joined the biostatistics department at Hopkins in 2013, put forth a mathematical formula to explain the genesis of cancer. Here's how it works: Take the number of cells in an organ, identify what percentage of them are long-lived stem cells, and determine how many times the stem cells divide. With every division, there's a risk of a cancer-causing mutation in a daughter cell. Thus, Tomasetti and Vogelstein reasoned, the tissues that host the greatest number of stem cell divisions are those most vulnerable to cancer. When Tomasetti crunched the numbers and compared them with actual cancer statistics, he concluded that this theory explained two-thirds of all cancers.

15. That's all you need to know about the measles. OK, that's not true at all. There's no one weird trick that will give you a flat belly (besides lying face-down on something flat), and there's no one weird number that explains measles epidemiology. But the basic reproduction number, or R0, of a disease does shed some light on which diseases become epidemics and how we can keep them in check.

In this activity, students analyze scientific figures to understand principles of island biogeography theory that determine the number of species in an isolated habitat. This activity uses a jigsaw approach to explore the processes that determine the equilibrium number of species in a habitat and how they are affected by both area and isolation. Two "Student Handouts" are provided as options for the activity. The "Analyzing Graphical Data" handout engages students in graph interpretation and sensemaking from data. The "Building the Equilibrium Model" handout facilitates a scaffolded investigation of the dynamic equilibrium model of island biogeography; students construct immigration and extinction curves to demonstrate the effects of area and isolation on the equilibrium number of species. 

She says people became much more willing to talk about their genetic predispositions and seek out testing for conditions like Alzheimer's disease and cystic fibrosis. The number of patients seeking genetic counseling and testing has increased dramatically, according to a 2014 study that looked at how Jolie's announcement affected interest in testing. But the number of genetic counselors, the people who help both doctors and patients make sense of these tests, hasn't expanded enough to keep up with that demand. There are just 4,000 certified genetic counselors in the country today. That's one for every 80,000 Americans.

In the February 19, 2014 issue of Science Translational Medicine (Sci Transl Med. 2014 Feb 19;6(224):224ra24), Bettegowda and colleagues in the Sol Goldman Pancreatic Cancer Research center at Johns Hopkins report on an exciting approach to the detection of pancreatic cancer. Bettegowda and colleagues applied cutting edge DNA sequencing to blood samples from a large number of patients with a number of different cancers. They found that many cancers, even some small curable cancers, shed mutant DNA into the blood.

The largest genome-wide association study to date, involving more than 300 institutions and more than 250,000 subjects, roughly doubles the number of known gene regions influencing height to more than 400. The study provides a better glimpse at the biology of height and offers a model for investigating traits and diseases caused by many common gene changes acting together.

Genetic differences among ethnically diverse individuals are largely due to structural elements called copy number variants (CNVs), according to a study published today (August 6) in Science. Compared with other genomic features, such as single nucleotide variants (SNVs), CNVs have not previously been studied in as much detail because they are more difficult to sequence. Covering 125 distinct human populations around the world, geneticist Evan Eichler at the University of Washington in Seattle and an international team of colleagues studied the genomes of 236 people-analyzing both SNVs and CNVs. "The take-home message is that we continue to find a lot more genetic variation between humans than we appreciated previously," Eichler told The Scientist.

Graphic tracking chromosome number during division

Herds of wooly mammoths once shook Earth beneath their feet, sending humans scurrying across the landscape of prehistoric Ohio. But then something much larger shook Earth itself, and at that point these mega mammals' days were numbered.

The lab includes a number of short videos explaining aspects of research methods or relating the evolutionary history of stickleback fish. We recommend that you view these videos, especially when going through the lab for the first time. Throughout the lab, bolded words in the text are defined in the glossary under the "Reference" tab.

More than 40 million people worldwide suffer from Alzheimer's disease, and that number is expected to increase drastically in the coming years. But no real progress has been made in the fight against the disease since its classification more than 100 years ago. Scientist Samuel Cohen shares a new breakthrough in Alzheimer's research from his lab as well as a message of hope. "Alzheimer's is a disease," Cohen says, "and we can cure it."

Breakouts are a pain and can happen well into your 40s. While there's no cure to make acne instantly go away, there are a few science-backed tips you can use to help minimize the number of pimples that pop up.

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).

The news that researchers want to create human-animal chimeras has generated controversy recently, and may conjure up ideas about Frankenstein-ish experiments. But chimeras aren't always man-made-and there are a number of examples of human chimeras that already exist. A chimera is essentially a single organism that's made up of cells from two or more "individuals"-that is, it contains two sets of DNA, with the code to make two separate organisms.

In a study published Thursday in the journal Science, they report that they've pinpointed the bit of finch DNA behind the swift transition: a gene called HMGA2. In finches, HMGA2 seems to be the primary factor in beak size - like a really good group project leader, it orchestrates the expression of a number of other genes, each of which tweaks the size of the bird's beak. The same gene also appears in dogs, horses, even humans, holding sway over body size and stature.

Methane's potency is one reason why environmentalists are so concerned about natural gas leaks. The Porter Ranch disaster in southern California spewed more than 200 million pounds of methane before it was finally plugged in mid-February. But each year, cows in the U.S. burp out 65 times more gas than was released in the now infamous leak. Globally, about a quarter of methane pollution comes from livestock. Hristov and his team study ways to reduce those emissions, so they have gotten very good at quantifying the amount their cows exhale. Prompted by some extra snacks, cow number 2050 ducks her head into a hooded machine that records the amount of methane, hydrogen, and carbon dioxide in her burps. During experiments, the scientists take eight measurements from each cow over several days. In a few months, this gives a snapshot of just how much methane the animals churn out -- and whether particular interventions work to slash that pollution.

Peer review is one collaborative writing strategy that can assist students in achieving a number of the Common Core Standards, including the one stating that students will improve their writing by "revising, editing, rewriting, or trying a new approach." Research has shown that peer review, done well, results in improved student writing and learning about writing.

The short film opens with two questions: "So what determines how many species live in a given place? Or how many individuals of the species can live somewhere?" The research that provided answers to these questions was set in motion by key experiments by ecologists Robert Paine and James Estes. Robert Paine's starfish exclusion experiments on the coast of Washington state showed that removing starfish from this marine ecosystem has a big impact on the population sizes of other species, establishing the starfish as a keystone species. James Estes and colleague John Palmisano discovered that the kelp forest ecosystems of the North Pacific are regulated by the presence or absence of sea otters, which feed on sea urchins that consume kelp. These direct and indirect effects of sea otters on other species describe a trophic cascade. These early studies were the inspiration for hundreds of investigations on other keystone species and trophic cascades, as well as ongoing studies into the regulation of population sizes and species numbers.

Multiple outbreaks have been reported in poultry farms and wild flocks across Europe, Africa and Asia in the past three months. While most involve strains that are currently low risk for human health, the sheer number of different types, and their presence in so many parts of the world at the same time, increases the risk of viruses mixing and mutating - and possibly jumping to people.