Biology Journal Day 7

The Linnean taxonomy is useful because when someone is referring to an  organism in a scientific way, there will be no ambiguity. I acquired new knowledge about earthworms that I had never known before, their various characteristics and behavior was fascinating. Anatomical features including their segmented bodies and the presence of a clitellum gives them their unique classification.

Duchenne muscular dystrophy is the number one killer of children affected with muscular dystrophies and any male child can be afflicted, regardless of race or nationality. Though incurable now, my one hope is that scientists will find the cure for it in our lifetime.

The greatest difficulty with this journal was the sheer amount of research that I had to do, and trying to condense the information into something readable.

                             

Biology Journal Day 6

Today I will discuss the genetic testing for Duchenne's muscular dystrophy. As it is a disease with dire consequences, and the genetic link is so strong, the best way to screen for it is to do prenatal testing. This is done before the fetus is even born. It can be done by sampling the amniotic fluid or be taking a sample from  the villous lining. There is a small physical risk of miscarriage from the procedure , and this can be tragic if the fetus is otherwise normal. If the fetus is tested positive for carrying the defective gene, then a termination of the pregnancy may be considered. It is a difficult decision for the parents to make, but if there is a strong family history or a child that is already affected, a trained genetic counsellor should advice them about the pros and cons of the procedure.

Sometimes the child is born normally but may be noticed to have the previous mentioned symptoms as he is growing , and genetic testing can then be done for diagnosis rather than for prevention. There are some implications for legal and social reasons, eg if he is tested positive , it may be difficult to get insurance for medical expenses and hospitalizations. He may also be stigmatized by his friends if they know he has a disease which is incurable. If they are enlightened friends, they may be able to help him, but it will be painful for his friends and family to see his condition deteriorate.

Finally, research into the specific genetic cause of Duchenne's has enable the use of stem cell therapy and drug therapy that may help this patient prolonged their lives or even effect a cure eventually.

Biology Journal Day 5

Hello, everyone. Today I decided to do the next question on genetic disorders.  I have chosen Duchenne muscular dystrophy which is a genetic disease where the afflicted patient suffers from severe muscular degeneration, leading to paralysis and of course, death.This is caused by a defective gene on the x chromosome . Boys have an x and a y chromosone, girls have double "x"s. So,boys can get the disease if their mother is a carrier, and they happen to receive the defective x chromosone from their mothers. Girls are afflicted only if their father is afflicted and their mother is a carrier and they inherited the x chromosome from their mother which has the defective gene.  This explains why Duchenne Muscular Dystrophy is mostly seen in boys. In some cases, the disease can be caused by a new mutation in a gene rather than from an inherited defective gene.


Symptoms may be seen in children before 5, usually between the ages of two to three years old. The symptoms include getting tired easily, inability to climb stairs, walking with a waddling gait, and appearing clumsy, falling over often, and having difficulty rising from a lying or a sitting position. By the age of ten, most will be needing braces but by age twelve, they would most likely be wheelchair bound. Later, they will suffer from abnormal bone development, resulting in deformities. Most die from their mid-teens to 30 years of age.However, some cases have lived to 40 years old, some even 50!


One can find out whether he or she has muscle disease by the following methods:

1. Blood test
2. Electromyography which measures the changes of electrical activities in the muscle
3. Ultrasonography which uses sound waves to produce precise images of tissues in one's body
4. Muscle biopsy, and 
5. Genetic Testing.

Patients are treated by physical therapy or drugs. Steroids may help improve muscle strength and delay the progression of Duchenne Muscular Dystrophy.  Immunosuppressive drugs are also sometimes prescribed to delay some damage to dying cells. Assistive devices like braces, canes, walkers and wheelchair provide support for weakened muscles and maintain mobility and independence.  These assistive devices also slows down the progression of contractures but when contractures develop, surgery may be needed to release them.

There's a short trailer video of a Duchenne patient call Darius and his brave journey to raise funds for more research into the disease.

Darius goes west

Biology Journal Day 4

Today I've found some pictures of earthworms and will add it. There's even a video of an earthworm with a short narration!

This is a picture  of a typical American Terrestrial earthworm

This is a picture of two earthworms performing the mating ritual

This is a schematic diagram of the anatomy of the earthworm. Note especially the clitellum which gives it the Taxonomic Class

And finally, here is a link to a Youtube video about earthworms. See how they Move!

http://www.youtube.com/watch?v=r5aRPP4C0J8

Biology Journal Day 3

Here we are this new day. I've found out that Earthworms are classified under Annelids because they have segmented bodies. Included in this Phylum are the ragworms and leeches. They are further divided into the Class Clitellata because they have a clitellum, a reproductive organ. The leeches are also endowed with a clitellum. Here the leeches , which are Hematophagous go their separate ways and the earthworms are further classified into Order Haplotaxida which they share with Tubifex worms. Finally, the Sub-Order Lumbricina contains only earthworms, although there are a variety of species. This are named according to Family, Genus and Species. In Singapore we actually have 15 species belonging to seven Genera, four Families and two Orders of terrestrial earthworms. The most interesting one is Pontoscolex corethrurus which is the commonest earthworm in Singapore. It is not native to our soil, but was probably transported here to colonize Singapore by our early human ancestors!

Biology Journal Day 2

Today I decided to choose the Earthworm as my animal of study. Earthworms are invertebrates with a segmented trunk.They have a few interesting characteristics for study . They are hermaphrodite, which means they have two pairs of reproductive organs, both male and female. these consists of both testes and ovaries located on different segments. Two earthworms will lie close together and release sperm into the other worms ovaries, and they will then deposit the eggs which have been fertilised into coccoons. The baby earthworms will emerge fully formed , however they will be sexually immature.


Another interesting characteristic about earthworms - they can regenerate. Many people believe that you can cut a earthworm up many times over and the pieces will grow back. However, this is erroneous. The actual regeneration depends on the species and the extent of the damage to the trunk.


Earthworms move by alternately expanding and contracting their segmented bodies. They have an important function of enriching soil as they crawl through and tunnel through earth, which is ingested from the mouth in front and excreted after it passes through the gut of the worm. The dead leaves ( compost) and humus and other organic matter are deposited as worm casts. The soil is also aerated and loosened and this makes it more fertile.


The Detailed classification of the American Earthworm is as follows:
Kingdom: Animalia
Phylum: Annelida
Class: Clitellata
Order: Haplotaxida
Sub-order: Lumbricina


I'll read more about the various classifications and write it up tomorrow. Maybe I can find some classification of Singapore Earthworms!

My Biology Journal Day 1

Today I learnt about Taxonomy. The first system I encountered was the Linnaeus , which is a ranked based scientific classification.

When Linnaeus wrote the Imperium Naturie, he divided it mainly into 3 Kingdoms- Animal, Vegetable and Mineral. He further sub-divided the Animal Kingdom into 6 Classes, the Vegetables into 24 Classes and the Minerals into 3 Classes.

The most important aspect of the rank based scientific classification is the use of Binomial Nomenclature; the combination of a Genus name and a second more specific Species. Ultimately, all organisms will have a specific classification with no overlap between species.

A more modern system of classification places all organisms in one of the six kingdoms- namely Animal, Plant, Protists, Fungi, Bacterium and Archaebacterium.The kingdoms are subdivided into many Phyla ( Singular Phylum). Each Phylum is divided into Classes, each Class into various Orders. The Orders will be further grouped into Families, which will be further divided into Genus. The final and specific group will be the Species. All organisms will have a scientific name with the Genus followed by the Species (An important note is when writing the Genus and species, the name is usually italicised with the Large Cap for Genus and a small cap for species ) A mneumonic that can be used to remember the classication from top-down is “ King Phillip, Come Out For Goodness Sake!) - Kingdom, Phyla, Class, Order, Family, Genus and Species.