Dinosaurs in our garden

Thanks to their light skeleton and feathers covering their whole body birds are able to fly, much to the longstanding admiration and envy of mankind. Birds are indeed remarkable creatures, but what is their origin?

When a huge meteorite struck the earth some 60 million years ago, arguably in what is now known as the Gulf of Mexico, the resulting dust cloud blocked the sunlight from reaching the earth surface during several years, causing in the first place a worldwide cooling and a massive extinction of the vegetation. The massive coldblooded dinosaurs being blocked from sunlight and nourishment did not survive long, much to the benefit of the smaller dinosaurs (some with feathers) and mammals with their inbuilt thermo-regulatory capability and their lesser nutritional needs.

Being better insulated and now with less natural enemies, those smaller, feather-covered dinosaurs eventually evolved in all known living and extinct birds. And we can say now that we see dinosaurs flying in our backyard.

The sea's most disgusting creature!

The Myxini a.k.a. the hagfish is a slimy, toothy, eel-like fish.
Hagfish have a lot of horny teeth and a pair of tooth-like rasps on their tongue, which they project into a prey to rip out chunks of flesh.
Because it is not only a slimy fish but also a very flexible one it can make a knot with its body.
The knot can travel towards the head and is used to pull out the hagfish’s tongue, which had been stuck in its prey.
When scared, the hagfish can produce over 20 litres of slime in only a few minutes to suffocate a predator.
If the slime clogs in its own nostrils the hagfish will sneeze, ATCHOOM!

Like an Egyptian

Too much lead isn’t good for you and it can cause serious conditions such as brain damage, nevertheless Egyptians used lead salts in their typical black eyeliner. These salts aren’t found in nature and are quite difficult to make, so why did they go trough so much trouble making these components? Ancient manuscripts gave an answer to this question, Egyptians used them as a treatment for eye diseases and scars.
Scientists tested the theory by adding lead salts to skin cells and saw that they started to produce nitric oxide, a compound involved in the body’s immune system, that can kill the bacteria near the eye by breaking down the DNA or other cell structures but it’s not clear yet if it is the nitric oxide that did the job or if it is the lead that directly kills the bacteria.
The fact that it can have a positive effect in small amounts and a negative one in large amounts, fits the hormesis model. Egyptians just didn’t live long enough to experience the harmful consequences of long-term exposure to lead.

The benefit of sticking out your tongue

The alligator turtle has an odd way of getting the attention of his preys. Underneath his tongue he has a pink wormlike protrusion he can move to use as bait. When the freshwater turtle gets hungry, he slips silently into the water and waits keeping his mouth wide open. Because of his rocklike appearance and due to the fact that his rough skin is often covered in algae the preys can't detect him. These preys, e.g. fish, swim to the fake worm and when they reach the turtle's beak the jaws snap, the fish are trapped and eaten by the turtle. And that's why sticking out your tongue isn't, for the alligator turtle at least, inappropriate but necessary to survive.

The cultivation of organs: future or fiction?

Tissue cultivation is a very fascinating and current scientific investigation with a lot of potential. The tissue cultivation starts with suitable undifferentiated cells, also called stem cells, that are put into a design of synthetic material of the organ of interest (for example a bladder). At this moment the cells will divide, develop into the organ and the organ can be transplanted into the patient where the synthetic material will dissolve. Tissue cultivation could be the solution for people who are on a waiting list for a donor and for the rejection symptoms that occur during transplantation. However, the new method isn’t ready to use yet because there are some problems like the support material that’s needed, the supply of nutrition and the chemicals that are essential for the differentiation of the stem cells. But who knows, maybe in the future tissue cultivation will really be put into practice!

Our mood can influence our DNA ...

DNA was thought as an absolute code, determining our characters, always well regulated and impossible to deform, except by a few number of factor such as mutations.
However, an other factor able to influence our DNA was found ; the stress.
Our DNA is composed of genes, which can, depending of the need, be expressed or inhibited, if presenting a methyl group (CH4).
DNA expression is falsified due to the stress which inhibits the wrong gene by fixing methyl group.
The main part of the DNA which is touched is situated in the area of the brain dealing with emotions ; the hippocampus.
If the DNA of the hippocampus' cells is touched during the childhood, it can have dramatic consequences in the adult life, as difficulties to handle hard situations and stress.

By Pessarossi-Langlois Julien, based on Sciences & Vie n°1110, March 2010.