Category Archives: Life Science

Biologists Identified a New Way in Which Bacteria Hijack Healthy Cells

Associate professor of biological sciences Zhao-Qing Luo, foreground, and graduate student Yunhao Tan identified a new way in which bacteria modify healthy cells during infection. Shown on the computer screen are cells infected with a mutant strain of the bacteria Legionella pneumophila used in their research.

Purdue University biologists identified a new way in which bacteria hijack healthy cells during infection, which could provide a target for new antibiotics. Zhao-Qing Luo, the associate professor of biological sciences who led the study, said the team discovered a new enzyme used by the bacterium Legionella pneumophila – which causes Legionnaires’ disease – to control its host cell in order to take up residence.

“Legionnaires’ disease is a severe form of pneumonia, and this finding could lead to the design of a new therapy that saves lives,” Luo said. “At the same time it also provides great insight into a general mechanism of both bacterial infection and cell signaling events in higher organisms including humans.”

Successful infection by Legionella pneumophila requires the delivery of hundreds of proteins into the host cells that alter various functions to turn the naturally hostile environment into one tailor-made for bacterial replication. These proteins tap into existing communication processes within the cells in which an external signal, such as a hormone, triggers a cascade of slight modifications to proteins that eventually turns on a gene that changes the cell’s behavior, he said.

“Pathogens are successful because they know how information in our cells is relayed and they amplify some signals and block others in order to evade the immune system and keep the cell from defending itself,” Luo said. “Despite our understanding of this, we do not know much about how the proteins delivered by the bacteria accomplish this – how they work. This time we were able to pinpoint an enzyme and see how it disrupted and manipulated a specific signaling pathway in order to create a better environment for itself.”

The signaling pathway involved was only recently identified, and the discovery by Luo and graduate student Yunhao Tan also provides a key insight into its process. The signaling pathway involves a new form of protein modification called AMPylation in order to relay instructions to change cell behavior and has been found to be used by almost all organisms, Luo said.

The bacterium affects the host cell’s functions differently during different phases of the infection process, tapping into signaling pathways to turn on and off certain natural cellular activities. SidD stops the AMPylation process four hours after the start of infection in order to reverse an earlier modification that would be detrimental to the cell if left in place, he said.

Read the full press release.

Hydromedusae, Siphonophora, Cnidarians, Ctenophores

Jellyfish is a common name for gelatinous water dwelling animals. The diversity of these invertebrates is amazing. And what actually counts as a jellyfish is not easy to determine. Watch this great video to learn about Cnidarians, Urochordata, Polychaetes and Ctenophores.

CDC Report on Failures to Vaccinate

Science brought us the miracle of vaccines and the near elimination of many diseases. Unfortunately people are choosing to bring those diseases to many more people because they failed to get vaccinated or failed to vaccinate their children. The needless pain and suffering caused by these poor decisions are a sad testament to scientific illiteracy.

The financial implications of the US measles outbreaks

One reason measles outbreaks are so scary (and so difficult to contain) is that measles is the most infectious microbe known to man–it’s transmission rate is around 90 percent. It has also killed more children than any other disease in history.
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The most significant factor in the spread of measles in the United States is declining vaccination rates — and, similar to what occurred in the UK in the early part of the last decade, that decline can be traced back to the press-fueled panic…

CDC report on Measles

Children and adults who remain unvaccinated and develop measles also put others in their community at risk…

In Europe in recent years, measles has been fatal for several children and adolescents, including some who could not be vaccinated because they were immune compromised.

Rapid control efforts by state and local public health agencies, which are both time intensive and costly, have been a key factor in limiting the size of outbreaks and preventing the spread of measles into communities with increased numbers of unvaccinated persons. Nonetheless, maintenance of high 2-dose MMR vaccination coverage is the most critical factor for sustaining elimination. For measles, even a small decrease in coverage can increase the risk for large outbreaks and endemic transmission, as occurred in the United Kingdom in the past decade…

Nice Program on Mexican Free-tailed Bats

Mexican free-tailed bats in the Central Valley, California: the voracious insect-eating species protects the local crops from pests. Bats really are wonderful animals and very beneficial to people. They eat many insects and some also help pollinate some plants. The Mexican free-tailed bats seem to even benefit from human activity (taking advantage of bridge underpasses as homes, for example), but many other bat species are in trouble.

New Discovery Finds Fungi Different From All Known Forms is Ubiquitous

A New, Somewhat Moldy Branch On The Tree Of Life

Many fungi are already familiar. There are mushrooms, yeasts, molds like the one that makes penicillin, plant diseases such as rusts and smuts. Mildew in your shower is one, along with athlete’s foot. There are even fungi that infect insects — as well as fungi that live on other fungi.

Biologists figure they’ve probably only cataloged about 10 percent of all fungal species. But they thought they at least knew all of the major groups.
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They found novel bits of DNA — related to fungi, but clearly different from all of the known varieties — just about everywhere, “including pond water, lake water, freshwater sediments and marine sediments,” Richards says. “Almost everywhere we looked we found this novel group.”

They then brought samples back to the lab and devised a technique to make the organisms containing this novel DNA glow under a microscope. As a result, they’ve managed to get a few glimpses of these mysterious life forms, which they have named cryptomycota.

“We know they have at least three stages to their life cycle,” Richards says. “One is where they attach to a host, which are photosynthetic algae. Another stage … they form swimming tails so they can presumably find food. And [there’s] another stage, which we call the cyst phase, where they go to sleep.”

Science continues to explore and find new wonders around us. There is so much still to learn.

Evolution of Altruism in Robots

The webcast explores robots evolving cooperative behavior. A Quantitative Test of Hamilton’s Rule for the Evolution of Altruism (open access paper)

One of the enduring puzzles in biology and the social sciences is the origin and persistence of altruism, whereby a behavior benefiting another individual incurs a direct cost for the individual performing the altruistic action. This apparent paradox was resolved by Hamilton’s theory, known as kin selection, which states that individuals can transmit copies of their own genes not only directly through their own reproduction but also indirectly by favoring the reproduction of kin, such as siblings or cousins. While many studies have provided qualitative support for kin selection theory, quantitative tests have not yet been possible due to the difficulty of quantifying the costs and benefits of helping acts. In this study, we conduct simulations with the help of a simulated system of foraging robots to manipulate the costs and benefits of altruism and determine the conditions under which altruism evolves.

By conducting experimental evolution over hundreds of generations of selection in populations with different costs and benefits of altruistic behavior, we show that kin selection theory always accurately predicts the minimum relatedness necessary for altruism to evolve. This high accuracy is remarkable given the presence of pleiotropic and epistatic effects, as well as mutations with strong effects on behavior and fitness. In addition to providing a quantitative test of kin selection theory in a system with a complex mapping between genotype and phenotype, this study reveals that a fundamental principle of natural selection also applies to synthetic organisms when these have heritable properties.

Image of Map Showing Concentration of Life in Oceans

This image shows the abundance of life in the sea, measured by the SeaWiFS instrument aboard the Seastar satellite. Dark blue represents warmer areas where there is little life due to lack of nutrients, and greens and reds represent cooler nutrient-rich areas.

The nutrient-rich areas include coastal regions where cold water rises from the sea floor bringing nutrients along and areas at the mouths of rivers where the rivers have brought nutrients into the ocean from the land. NASA has posted a large gallery of great images for Earth Day.

Cancer Vaccines

A reader commented on a previous post (MIT Engineers Design New Type of Nanoparticle for Vacines) asking about how vaccines can fight cancer. Preventative vaccines can build up immune response to viruses which cause cancer. So the vaccine actually works against the virus which prevents the virus from causing cancer.

The U.S. Food and Drug Administration (FDA) has approved two vaccines, GardasilÂ® and CervarixÂ®, that protect against infection by the two types of human papillomavirus (HPV) – types 16 and 18 – that cause approximately 70% of all cases of cervical cancer worldwide. At least 17 other types of HPV are responsible for the remaining 30% of cervical cancer cases. HPV types 16 and/or 18 also cause some vaginal, vulvar, anal, penile, and oropharyngeal cancers.

Many scientists believe that microbes cause or contribute to between 15% and 25% of all cancers diagnosed worldwide each year, with the percentages being lower in developed than developing countries.

Vaccines can also help stimulate the immune system to fight cancers.

B cells make antibodies, which are large secreted proteins that bind to, inactivate, and help destroy foreign invaders or abnormal cells. Most preventive vaccines, including those aimed at hepatitis B virus (HBV) and human papillomavirus (HPV), stimulate the production of antibodies that bind to specific, targeted microbes and block their ability to cause infection. Cytotoxic T cells, which are also known as killer T cells, kill infected or abnormal cells by releasing toxic chemicals or by prompting the cells to self-destruct (a process known as apoptosis).

Other types of lymphocytes and leukocytes play supporting roles to ensure that B cells and killer T cells do their jobs effectively. These supporting cells include helper T cells and dendritic cells, which help activate killer T cells and enable them to recognize specific threats.

Cancer treatment vaccines are designed to work by activating B cells and killer T cells and directing them to recognize and act against specific types of cancer. They do this by introducing one or more molecules known as antigens into the body, usually by injection. An antigen is a substance that stimulates a specific immune response. An antigen can be a protein or another type of molecule found on the surface of or inside a cell.

How To Make Your Own Pesticide with Ingredients from Your Kitchen

Video by the Singapore National Park Board, on creating your own pesticide with just water, dish-washing liquid, chili, garlic and cooking oil.

New Analysis of Primordial Soup Experiment Half a Century Later

Open access paper: Primordial synthesis of amines and amino acids in a 1958 Miller H₂S-rich spark discharge experiment

Archived samples from a previously unreported 1958 Stanley Miller electric discharge experiment containing hydrogen sulfide (H₂S) were recently discovered and analyzed using high-performance liquid chromatography and time-of-flight mass spectrometry. We report here the detection and quantification of primary amine-containing compounds in the original sample residues, which were produced via spark discharge using a gaseous mixture of H₂S, CH₄, NH₃, and CO₂. A total of 23 amino acids and 4 amines, including 7 organosulfur compounds, were detected in these samples.

The major amino acids with chiral centers are racemic within the accuracy of the measurements, indicating that they are not contaminants introduced during sample storage. This experiment marks the first synthesis of sulfur amino acids from spark discharge experiments designed to imitate primordial environments. The relative yield of some amino acids, in particular the isomers of aminobutyric acid, are the highest ever found in a spark discharge experiment.

The simulated primordial conditions used by Miller may serve as a model for early volcanic plume chemistry and provide insight to the possible roles such plumes may have played in abiotic organic synthesis. Additionally, the overall abundances of the synthesized amino acids in the presence of H₂S are very similar to the abundances found in some carbonaceous meteorites, suggesting that H₂S may have played an important role in prebiotic reactions in early solar system environments.