Biology Fact-Sheet on ‘Fragile X Syndrome’

CHARECTERISTICS

Fragile X syndrome is an X-linked dominant disorder causing mental and emotional disabilities. This disorder is heritable and can be passed from one generation to another. The persons suffering from this disorder show phenotypes like prominent ears, long face, autism and behavioral problems (Fragile X Syndrome). It is called “fragile X syndrome” because the affected X chromosomes are narrowed at the end when observed under high resolution microscope. (Fragile X Syndrome, 2007)

 Since the gene causing is present on the X chromosome, the number of affected males is higher than the number of affected females. It is so because, males have only one X chromosome present (XY chromosome) while females have two X chromosomes (XX chromosomes). Most of the females with fragile X syndrome have one normal X chromosome and one defective X chromosome but they have only one functional copy of X chromosome. During protein formation cell randomly chooses only one X chromosome for translation, therefore sometimes females with a defective X chromosome also have normal phenotype. Where as in males the X chromosome is always utilized in protein formation and the disorder is expressed. (Fragile X Syndrome)

CAUSES

It is caused by the mutation in a gene that encodes for the Fragile X Mental Retardation Protein (FMRP) required for the brain to carry out normal functions. Due to the transcriptional silencing of the Fragile X Mental Retardation 1 (FMR1) gene the expression is inhibited. (Garber 2008)

The promoter region of the FMR1 gene consists of a repeated CGG sequence. A normal FMR1 gene has about 6 to 40 CGG repeats where a mutated FMR1 may have more than 200 repeats. The number of repeats vary from person to person.  A mutation ranging from 55 to 200 repeats is called “Premutation” where as a mutation with more than 200 repeats in a gene is known as “Full Mutation” and the phenomenon is called as methylation. (Fragile X Syndrome)

 Due to extended CGG repeats in the untranslated 5′- region the gene is inactivated and production of FMRP is halted. FMRP is a protein which selectively binds to RNA and carries out the negative regulation of protein synthesis in neuronal dendrites (Hagerman 2005). When FMRP is not present, the transcripts regulated by FMRP are over translated resulting in the abundance of proteins. The protein abundance reduces the synaptic strength due to trafficking of AMPA receptor (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor). Because AMPA receptors get inhibited, the synaptic transmission to the Central Nervous System is reduced leading to synaptic plasticity and mental abnormalities. Because synaptic plasticity is responsible for learning and memory, its alteration results into fragile X syndrome. (Garber 2008)

TREATMENT

There are several ongoing research projects funded by National Institute of Child Health and Human Development (NICHD), which aim to find a suitable cure for this disorder. NICHD has established three research centers across the country for the treatment of Fragile X Disorder.  The disorder can be determined by carryings genetic testing. In order to find the treatment, the research is carried out on several model analogous to human brain the possible outcomes are discussed as follows: (Fragile X Syndrome)

1.    Production of certain chemical in the brain that repairs the mutated, extended FMR1 gene.
2.    A drug that initiates reverse methylation.
3.    Replacing the mutated FMR1 gene with a normal gene.
4.    To introduce FMRP artificially into brain via pills or injections.
5.    To find a substitute for FMRP that carries out similar function.

Bradford micro-assay

Bradford micro-assay is a technique which is used to determine the total protein concentration in an unknown sample. The presence of protein is determined by a dye named, Comassie Brilliant Blue G250 (Bradford Reagent) which favorably binds to the basic amino acid residues like arginine and lysine. Upon binding, the dye turns blue in the presence of protein or may appear brown in color if the protein is absent in the solution. The quantity of protein is analyzed with the help of a spectrophotometer which measures the quantity of protein by measuring its transmission properties. To analyze the quantity of protein, a standard curve with known amount of protein content is prepared first. The standard curve is a smooth line and by locating the value obtained from unknown sample, we will get the value of the protein content in the unknown sample.


need Help with your Lab report, Please contact: nicole.freelancer@gmail.com

Use of OLIGONUCLEOTIDES as anti viral drugs

Antibiotics are widely used against a wide spectrum of microorganisms but they are not effective on the viruses because viruses are not living and they become active only through the viral transcript. Therefore a different class of drugs known as antiviral drugs is meant for the treatment of viral diseases. Most of the antiviral drugs are the analogues of nucleosides lacking hydroxyl groups, which get incorporated in the viral genome when the viral DNA replicates itself. The double stranded DNA created after replication is inactive due to the presence of nucleoside analogues and the virus is not able to grow. (Mindel 1983)

Conventional antiviral drugs do not destroy the virus but only inhibits their growth by halting the replication. But there is a significant risk associated with these drugs because the nucleoside analogues may also inhibit the replication of cellular DNA.  (Soundararajan 2009)

Therefore there is a requirement of a drug molecule that acts only on the specific target and selectively inhibits the gene expression. There has been an ongoing research on the usage of oligonucleotide as antiviral in antisense and RNA interference against pathogenic RNA viruses. Oligonucleotide as antiviral therapeutics has proved to be effective in this direction and has shown high target specificity so far.  (Lopez-Fraga 2008)

 It utilizes complementary oligonucleotide sequence that inhibits gene transcription either by catalytic degradation of mRNA or binding to mRNA sites for translation. It is different from the optimal approach in being specific because the optimal approach aims at total inhibition of the viral genome. (Spurgersa 2007)

Oligonucleotides in RNA interference (RNAI)

The double stranded small interfering RNA (siRNA) have been used in the mammalian cells for gene silencing. They are about 21 nucleotides in length and generated by the cleavage of long dsRNA by RNase class III riboendonuclease proteins, also known as Dicer. The Dicer generated siRNAs are incorporated into the RNA-induced silencing complex (RISC). RISC is activated by the action of Argonaute 2 (AGO2). After getting activated, the siRNA cleaves the sense strand of targeted RNA and generates a complementary sequence to the mRNA. The endonuclease present in the RISC complex, cleaves mRNA which is then degraded by intracellular proteins and does not gets translated. The RISC complex is recovered at the end of the process. (Lopez-Fraga 2008)

Another method of gene silencing involves micro RNAs (miRNA) which are produced in the cell as a separate species and posses some complementary sequences. They are about 21 nucleotides long non coding RNAs that bind to the mRNA and translation is inhibited leading to degradation of mRNA. (Lopez-Fraga 2008)

The RNAi based antiviral therapy is analogous to this naturally occurring process. Its aim to silence the targeted viral gene without harming the cellular genes and it can be achieved either by transfecting the cell with synthetic siRNA or short hairpin RNA (shRNA) resembling miRNA. There has been a sufficient progress in achieving the stability, drug resistance, toxicity, and cost of siRNA therapy. There are several other advantages associated with siRNA therapy like, they have short pharmacological development time period, very specific in action, can be easily synthesized and a broad spectrum of pathogens could be targeted. These findings support siRNA being used as an antiviral therapy for the treatment of highly pathogenic viruses. (Lopez-Fraga 2008)

Oligonucleotides in Antisense Technology

The antisense technology is not dependent on the host cell mechanism but it is a simple technique where the antisense oligonucleotide combines to the mRNA and inhibits the translation of viral transcript. The analogous antisense oligonucleotides are synthesized artificially and they consist of nuclease activity. Their binding capacity is much higher than the oligonucleotides naturally occurring in the cell. This avoids the binding of the analogue to cellular gene. The analogue is about 20 to 25 nucleotides in length and with 10 to 100% modified bases for effective and specific binding.  (A New Generation of Antiviral Drugs). They are chemically modified and purified to maintain the stability and keep them safe from the exonuclease activity. (Khan 1993)

One of the example of antisense technology is vaccine against Enterovirus and Rhinovirus which are pathogenic viruses and cause several diseases. Antisense antiviral therapy has proved to be very effective in the treatment as no effective treatment was available earlier. Single stranded DNA like antisense compound called, Peptide-conjugated phosphorodiamidate morpholino oligomers   (PPMO) was used. It can easily enter the cell and is specific for internal ribosome entry site (IRES) sequence which is the target sequence against human rhinovirus. The IRES sequence is highly conserved (about 99%) in the Enterovirus and Rhinovirus so it is a good target for a drug. The results showed that PPMO was highly efficient against broad variety of Enterovirus and Rhinovirus.  (Stone 2008)

There are several advantages associated with antisense antiviral therapy like , they do not depend upon the host machinery for functioning, they are very specific in action, can be used against a wide variety of pathogens and several diseases such as, HIV, Hepatitis C, Influenza etc. The main concern in the application of antisense antiviral therapy is to maintain its stability in the cell and prevent from degradation, method of delivery and maintain their bioavailabity. Therefore they are first chemically modified before transfection. The success of PPMO vaccine against Enterovirus and Rhinovirus supports the fact that antisense antiviral therapy can be uses as potential drug again undruggable pathogenic viruses. (A New Generation of Antiviral Drugs)

Forces stabilizing the nucleic acid structure

The forces responsible for stabilizing nucleic acid structures include non-covalent intramolecular interactions between the bases, magnitude of the Gibbs free energy and the thermodynamic relationships between enthalpy and entropy changes.

Two different forces and interactions govern the stability, including: 1) Occuring in the plane of the bases (horizontal); most commonly hydrogen bonds; b) Occuring perpendicular to the base planes or "base stacking" effects; these are stabilized by London dispersion forces and the hydrophobic effect. 1. Under the influence of a hydrogen bond, the H becomes more electropositive and becomes a better donor. 2. Stacking is a diffusion controlled, additive, and stabilized by two separate forces: hydrophobic effect and London dispersion forces.

Referencing styles

• ACS

           Style manual of the American Chemical Society

• AGLC

          Standard Australian guide for referencing in Law

• AGPS/AGIMO

           Standard Australian style manual

• AMA

           Style is widely used in medicine 

• APA

           Standard style used in Psychology

• Chicago

           Style is the most widely consulted of all style manuals

• CSE (CBE)

           Manual of the Council of Science Editors

• Harvard

           Generic term for any style which contains author-date references

• IEEE

           Professional body and publisher in the fields of electrical engineering and computer science

• MLA

           Style is widely used in the fields of modern literature and linguistics

• Vancouver

           Generic term for a style of referencing used in the health sciences

For more please contact @: nicole.freelancer@gmail.com

AGEING

The need of having a good life is universal and is similar across countries, cultures and religions. Though the parameters of a good life varies from person to person but there are some basic things that remain same throughout such as, having a good health, being young and to have a good social life. In a broader sense all the components are interrelated with each other like having a good health can delay the ageing process and this can uplift the esteem of a person and make him socially more active. So we can say the having a good health should be the main goal for a good life, but in today’s world living has become more stressful and unhealthy. Even in developed countries such as Australia, the quality of living is good but it does promises a healthy living that can prevent some of the major problems faced by people such as sickness, ageing etc.

Ageing is a biological process and we all are ageing with passing time. But sometimes some social and environmental factors may accelerate this process and cause early ageing. It is important to be aware of such social factors which may interfere with the biological clock and cause early ageing. Ageing is a major problem in developed countries like Australia because of the social factors such as, Independent living and relying on Junk food which is unhealthy and lack essential nutrients required for the body to keep fit and young. Another social factor having unhealthy habits such as smoking and having alcohol which again had harmful toxins and free radicals which lead to ageing. (1) And lastly taking sun bath, tanning, excessive sun exposure and staying in sun for longer period of time also causes the skin cells to age early (2) and in a country like Australia, eating junk food,  smoking, alcoholism and taking a sun bath for long period of time is a prevalent culture which is leading towards ageing. This topic has been chosen because it is a matter of concern and should be acknowledged. Guidelines and measures should be provided by specialists to avoid this problem and educate people about a healthy living.

For more please contact @: nicole.freelancer@gmail.com

Chemistry of metallic nanoparticles

In the past few decades, application of nanoparticles has been central in the development of science and new technologies. Nanoparticles are being used in many techniques such as water purification, use in jewelry, pesticide removal and other medical applications.  The major advantage of the use of nanoparticles is that they offer minimal reactivity with other materials because of their electrochemical potential, molecular potential etc even when used in bulk. But this usage of nanoparticles has made them exposed to our natural environment and they can be found in our natural environment along with other organic and inorganic environmental contaminants. Therefore it is very important to know the analytical chemistry of these nanoparticles to keep a check on its distribution in our natural environment. Knowing the chemical properties of nanoparticles will lead to the knowledge of the extent up to which nanoparticles can influence the environmental behavior, extent up to which they can contaminate the drinking ground water and extent of their ingestion by human beings. The analytical chemistry will also let us know about the affect of nanoparticles on ecological factors such as, sea creatures, land dwelling animals.

For more please contact @: nicole.freelancer@gmail.com

Risks of Bowel cancer due to Alcohol consumption

Alcohol is considered to be linked with a major cause of several types of cancer including breast cancer in women, cancers of the mouth, esophagus, stomach, pharynx, larynx, ovaries, colorectal or bowel cancer and liver cancer. A unit of World Health Organization (WHO) called, The International Agency for Research on Cancer has classified alcohol as Group 1 Carcinogen proving that alcoholic beverages are carcinogenic to humans. There are several possible mechanisms under which alcohol can work as a carcinogen. Some of the mechanisms are mentioned as follows:

1.    Acetaldehyde: The liver produces acetaldehyde after the break down ethanol present in alcohol. The liver can break down about 99 percent of the acetaldehyde from the body.  A defect in the gene alcohol dehydrogenase may affect the breakdown of ethanol and this may cause a more than normal percentage of acetaldehyde in the body. Those individuals with a defective gene have a great risk of being prone to cancers of the liver and gastrointestinal tract.  

2.     Epithelial mesenchymal transition: It is suggested that alcohol stimulates the EMT i.e. epithelial mesenchymal transition due to which normal cancerous cells transform into an aggressive form and start spreading across the body.

 Alcohol affects cancer progression: According to a research conducted on patients with type C cirrhosis, there was an increase in the progression of tumor growth of hepatocellular carcinoma (HCC) under the influence of alcohol intake known as alcohol influenced tumor volume doubling time (TVDT).

For more please contact @: nicole.freelancer@gmail.com

Literature Search

A systemic search is method of searching literature to write a review. In the healthcare sector, students are required to maintain a high level of competence in their literature and carrying out a systemic search improves the literature quality and its retrieval. A systemic search provides an understanding of indexing and using proper keywords for search in the databases. A strategy for systemic search is mentioned as follows (Grant, K.L. et. al.):

1.    Break the question into smaller parts and label each part as A, B, C etc.

2.    Write down a key word for each part A, B, C respectively.

3.    Combine each key work with Boolean operators such as “or”, “and” etc. and search in the database.

4.    Use precise key words in the search.

5.    Use key words such as: registry number, investigational drug number etc.

The main advantage of using systemic search is to create a systemic review which is a high quality literature review for assessment of healthcare research. A systemic review includes all the relevant references and material for a topic that can be collected from the electronic databases.

For more please contact @: nicole.freelancer@gmail.com