Sunday, December 27, 2009

The meaning of life



The organism Mixotricha paradoxa exemplifies the problems of biological classifications and the overly-simplistic views about life on earth that modern biologists are trying to abandon. This microscopic “organism” lives in the gut of termites and helps the termite digest cellulose (fiber). When it was first described in 1933, Mixotricha looked like a single-celled organism with little hairs like cilia all over it and a whip-like tail to help it move. However, decades later, upon further scrutiny, these accessory structures on the Mixotricha turned out to be separate organisms. The thousands of cilia-like structures are actually spirochete bacteria and the “tail” is yet a different bacterium. So, what at first appears to be AN organism is actually several different organisms that depend on each other for survival (a form of symbiosis called mutualism). Or, perhaps it should be classified as one composite organism (E pluribus unum!). After all, consider the human organism. Each human body is an organism with more bacterial cells living on and in it than the number of human cells in it. Furthermore, in every one of the human cells reside tiny little mitochondria. They each have their own circular DNA molecule, which is very similar to bacterial DNA. Mitochondria replicate inside of our cells and carry out metabolic reactions, which benefit our cells and allow us to live. Living things evolve through complex mergers and separations of life systems. Two become one, one becomes two etc…Perhaps the concept of life is stated best by Lynn Margulis, a renowned symbiologist.

" 'What is life?' is a linguistic trap. To answer according to the rules of grammer, we must supply a noun, a thing. But life on Earth is more like a verb. It is a material process, surfing over matter like a strange slow wave. It is a controlled artistic chaos, a set of chemical reactions so staggeringly complex that more than 4 billion years ago it began a sojourn that now, in human form, composes love letters and uses silicon computers to calculate the temperature of matter at the birth of the universe."




Thursday, December 17, 2009

Leprosy and other related diseases


Leprosy (Hansen's Disease) is a chronic bacterial infection of the skin and peripheral nerves. The agent Mycobacterium leprae is a close relative of the bacterial agent of tuberculosis (Mycobacterium tuberculosis). DNA from both of these bacteria has been found in ancient human remains and artifacts. The belief that leprosy is highly contagious is conveyed in historical texts such as The Bible and mediaeval literature. Many people with leprosy (lepers) were isolated and/or shunned by society. However, now we know that leprosy is not easily transmitted from person to person unlike tuberculosis which is highly communicable. In fact, rapid spread of tuberculosis may have actually limited the spread of leprosy in the mediaeval populations. A third mycobacterial disease, Buruli Ulcer, is found in Africa and Australia. It appears to be contracted from water; however, like leprosy, the exact route of transmission is unknown. Mycobacterium ulcerans creates large, chronic lesion (bottom picture) that leaves infected people (often children under 15) disfigured.

Animalcules

Antonie van Leeuwenhoek is one of the historic figures often credited with inventing (or co-inventing ) the microscope as well as founding the science of microbiology. He made powerful glass lenses that enabled him to see single-celled organisms and conduct many experiments that ultimately convinced the scientific community that tiny living things existed-even though they were not visible to the naked eye. Leeuwenhoek called these microscopic organisms "animalcules", a term that is not widely used today other than in historic context. The story of Leeuwenhoek exemplifies science in several ways. First, it reminds us that scientific advancements are made after observations are tested methodically. Second, we see that sometimes unlikely scientists, like Leeuwenhoek, discover the unexpected.

Wednesday, December 16, 2009

Introduction

Welcome to my blog about biological sciences. I hope that all who visit will find something here intellectually stimulating. I feel confident that over time this will evolve considerably. However, like living organisms, its future form may depend on various selective pressures. At this point, my goal is that it will be informative and instrumental in connecting visitors with the amazing science of biology.

"We will now discuss in a little more detail the Struggle for Existence."

-Charles Darwin