Comparative analysis of gene expression for convergent evolution of camera eyes between octopus and human

A research from Japan by Atsushi O., Kazuho I. and Takashi G. suggests that the similar structures of the eyes of octopus and human are the result of convergent evolution, which means that octopus and human evolve to have similar structures independently of one another.
The research team conducted a comparative analysis of gene expression in octopus and human eyes to prove their suggestion. They sequenced 16432 ESTs (Expressed Sequence Tags) of the octopus eye and focused on 1052 redundant genes that have matches in the protein database. In comparing with 13303 already-known ESTs of the human eye, they found that 69.3% of the 1052 genes were commonly expressed between both eyes. However, the expression similarity was very low when they compared octopus eye ESTs with human connective tissue ESTs. They also compared octopus eye ESTs with the ESTs of other organisms, and they found that 1019 out of the 1052 genes had already existed at the common ancestor of bilateria, and 83.2% were conserved between humans and octopuses. As a result, the larger number of conserved genes and their similar gene expressions may be responsible for the convergent evolution of the camera eye.

Reference
Atsushi O., Kazuho I. and Takashi G., 2003, ‘Comparative analysis of gene expression for convergent evolution of camera eyes between octopus and human’, 14 Dec 2003, Center for Information Biology and DNA Bank of Japan, National Institute of Genetics, viewed 19 May 2009, http://genome.cshlp.org/content/14/8/1555.abstract.

Malaria Resistance in Mosquitoes

A recent publication from Technology Review outlines research from John Hopkins University claiming that they have discovered a cost effective and practical malaria control strategy. Malaria is most prominent in Africa and kills millions of people every year, most of which are children. Anopheles female mosquitoes pass the parasite Plasmodium between human hosts rapidly, making control methods difficult to achieve. Researchers have proposed one possible method involving the release of genetically modified mosquitoes into the wild which are unable to transmit the parasite.

At John Hopkins, Jacobs-Lorena and his colleagues engineered malaria resistance in their mosquitoes by modifying the insects to produce the SM1 peptide which prevents the invasion of the mosquitoes gut by Plasmodium and in effect prevents the parasite’s development.

Computer generated models suggested that in order for the transmission of the disease to be stopped, the resistant mosquitoes must nearly entirely replace to wild population. Possible success with this method was then further tested via experiments where equal numbers of resistant and non-resistant mosquitoes were allowed to feed on mice infected with Plasmodium; from which the insects’ eggs were collected and then reared. After nine generations the experiment showed that the malaria resistant mosquitoes had greatly out competed their non-resistant counterparts with 70% of the progeny expressing the desired resistance, suggesting that perhaps being infected with the parasite may inhibit mosquitoes fertility making them less successful competitors against those that had been genetically modified to produce the SM1 peptide. If enough of the GM mosquitoes could be released into the wild and be able to out compete the non-resistant insects, future generations of not only mosquitoes but humans could not longer face the inhibitions of malaria.

Reference: Wu. C., 2007, Malaria-Resistant Mosquitoes, http://www.technologyreview.com/biomedicine/18407/ [Viewed: 19 May 2009]

Genes identified that influence the spread of cancer to the brain

A recent study has identified a gene that can influence the spread of breast cancer cells to brain. The team of researchers analysed a number of tissue samples and used advanced genetic techniques in order to try and identify the genetic code and determine how the cancer cells were capable of breaching the brain’s vast network of defences. The study was conducted on mice 3 genes were identified as responsible for the spread.

The gene that was identified to assist in penetrating the brains defences, ST6GALNAC5, supposedly allows cancerous cells to ‘stick’ to the blood vessels of the brain, eventually allowing them to access the tissue. These blood vessels are the brains primary means of defence, and normally control what foreign substances gain access to the brain, whether they are drugs or viruses. Once the cells breach this defence, the cancer can rapidly develop within the tissue. The researchers also found that when ST6GALNAC5 was absent, the cells failed to spread to the brain.

Two other genes, COX2 and HBEGF, were also shown to assist breast cancer cells to invade other areas of the body, including the lungs. They are also believed to have an influence on the spread of secondary tumours.

Professor Sir David Lane, one of the Cancer Research UK’s chief scientists said ‘the genes they've identified could become good targets for new drugs as well as some existing medicines, so they offer hope of being able to block this particular form of metastasis.’

Although this study is still within its early stages and was conducted in mice, it still could have heavy implications on the way we treat cancer in the future.

References:
Gene allows cancer to enter brain, retrieved 19/05/2009
http://news.bbc.co.uk/2/hi/health/8033630.stm

Controversial Alzheimer's Gene Discovered:

It is rarely we see a gene mutation which leads to beneficial effects in living organisms. Even rarer still is a beneficial gene mutation occurring in animals, let alone humans.

Yet, such a mutation has been discovered, in the form of the APP gene – the gene which causes Alzheimer’s disease. Fabrizio Tagliavini, a neurologist, and his team from the Carlo Besta National Neurological Institute (in Milan); have observed a 44-year-old man who had two copies of the mutated APP gene. Symptoms of early Alzheimer’s disease appeared in the man during his mid thirties. However, six of his family members only have one of the mutated APP gene, and none of them are afflicted with Alzheimer’s disease. The man also had a younger sister with two copies of the faulty APP gene. She has exhibits some mild symptoms of Alzheimer’s but is not completely afflicted with the disease.

The APP gene, in case you are wondering, causes clumping in the brain through the production of the sticky A-beta protein, which, as it accumulates, sticks together and prevents the communication between neurons in the brain. This leads to the telltale symptoms of Alzheimer’s disease: memory loss and the deterioration of physical functions.

Tagliavini’s team tested the mutant gene by mixing the mutant A-beta clumps with normal A-beta clumps. When the genes were left unmixed, they clumped together more than when they were mixed with each other. This could explain why people with only one of the mutated APP gene apparently show no signs of the disease.

With the discovery of the faulty A-beta protein, scientists may find a way to produce a cure for Alzheimer’s disease, or at least slow down the creation of A-beta clumping in Alzheimer’s sufferers.

Original Article: http://www.newscientist.com/article/dn16750-paradoxical-gene-causes-and-protects-against-alzheimers.html

COMMON GENES TIED TO MULTIPLE ADDICTIONS

In recent studies undertaken by experts at the University of Virginia Health System and the University of Michigan, it has been documented that there is a confirmed relationship between specific genes and varying types of addiction.  A scientific discovery in the field of molecular genetics originally thought to be of great complexity and uncertainty until now.

Established by means of comparison, the study provides an outline of particular genomic locations on eleven chromosomes where addictions to alcohol, cannabis, cocaine, heroin, nicotine and opoids are assembled closely.

It must be established however, that the specific nature and functionality of the gene variants remains unknown. Once this can be identified, more beneficial, possibly even personalized, treatments for addicted individuals to multiple substances can be determined.

It is recognized that research into the genetics of addiction is far from complete, with the suggestion of functional studies as well as further sampling involving ethnic populations currently being scrutinized.

Original article: http://www.sciencedaily.com/releases/2009/03/090310142912.htm

Post by: Elyse Bond (42054067)

Synthetic blood – the end to blood shortage woes

The constant shortage of blood in our banks has always been an issue in Australia. You only need to see the advertisements on television or the Red Cross van parked on campus to realise that blood is at the top of the ‘most wanted’ list. Thanks to researchers in the UK, donating blood could really be a thing of the past. By using the stem cells from left over IVF embryos, scientists have already been able to create synthetic blood. Lead by the Scottish National Blood Transfusion Service, a three year trail of transfusions into human volunteers of the synthetic blood, could see the beginnings of an unlimited blood supply.

Whilst there are numerous blood groups, only the ‘O – Negative’ blood group can be universally transfused without fear of tissue rejection. Especially in patients with unknown blood groups, it is the only safe administration. With seven percent of the population carrying this blood group, keeping in mind that not all seven percent of people will choose to donate blood, the current blood funds are under tight restraints. Fortunately, researchers are already testing embryos left over from IVF treatment for those that are genetically programmed to develop in ‘O-negative’ blood group. The ability of cells to replicate indefinitely in the laboratory means blood shortages would no longer be a problem.

Scientists have readily known about the ability of stem cells to develop into any cells in the body. By extracting a single stem cell from an early human embryo, it is possible to stimulate it to develop into mature blood cells in the laboratory. A US firm called Advanced Cell Technology has already managed to produce billions of red blood cells from embryos. Another major advantage of the synthesised blood is the removed risk of blood carrying viruses such as HIV and hepatitis or the human form of ‘mad cow’ disease. The major challenge now is to upsize the production and bring it into public domain.

Any usage of stem cells always comes with ethical debate. Many people believe that by using embryonic stem cells, we are murdering a potential human. Furthermore, blood donors who share beliefs in defending the rights of human embryos may choose to discontinue their generous donations.

The project will be led by Professor Marc Turner of Edinburgh University who is the director of the Scottish National Blood Transfusion Service. Although he sees promise in the technique, he believes ‘a realistic treatment is probably five to 10 years away’. The Wellcome Trust is understood to have promised £3m towards the research project with other contributors including the blood transfusion services of Scotland, and England and Wales.

Sources:

Article and Pictures: http://news.bbc.co.uk/2/hi/health/7958582.stm

Post by: Chen Li (4204861)

Cancer's one-way ticket to the brain

HOW do cancer cells get into the brain? A "ticket" made of three genes seems to grant them access in mice. The discovery could one day lead to drugs that cancel out a similar ticket in people.
Around 10 per cent of people whose cancer has metastasised, or spread beyond the original site, develop brain tumours. But it's a mystery how cancer cells get past the "blood-brain barrier", which prevents the passage of most cells.
To investigate, Joan Massagué and his colleagues at the Memorial Sloan-Kettering Cancer Center in New York city injected human breast cancer cells into the arteries of mice. Three key genes were expressed in those cells that infiltrated the brain: one that helped cancer cells "stick" to blood vessels in the brain, another that is known to make capillaries leaky, and a third that makes cancer cells mobile (Nature, DOI: 10.1038/nature08021).

Published in New Scientist 13-May-2009

Dolly the Clone

On the 5 of July 1996, the first successful clone was birthed. A sheep, to be precise; Dolly the sheep. Named with a sly nod towards Dolly Parton, the cells from the udder of a pregnant six year old sheep were introduced into the uterus of a of another sheep and in the July of 1996, Dolly was born. Dolly had the exact DNA taken from the sheep six years prior, making her the first ever mammal successfully cloned using adult cells. Sadly, though, she was euthanized on the 14 of February 2003 after doctors detected progressive lung disease.
Post mortem confirmed however, that this was not likely in relation to being cloned; her telomeres were actually half as short as that of a regular sheep. Normally sheep live for about 11 to 12 years. Dolly lived only for a total of six. Spooky. Nonetheless, not a bad effort after 276 preceding failures, Dolly being the 277th attempt. Hoorah.
However, the result of this test shows that cloning has an amazing, almost limitless potential. It can be used to save endangered species or even resurrect extinct ones. Although nothing is promised, it’s not too much of a stretch to envision a possible Jurassic Park. In a true mammalian clone, the nucleus from a body cell of an animal is inserted into an egg, which then develops into an individual that is genetically identical to the original animal.
This does warrant further consideration in terms of direct benefits to the human race though, since the risk is not necessarily worth the rewards. There are controversies surrounding the dehumanizing of subjects since they can be grown and therefore just as easily discarded.
Also the exact purposes of cloning have been narrowed down to two basic reasons: aid to current IVF techniques and use for genetic selection or eugenics purposes. The latter has shown to be very problematic in the wrong hands thanks to some certain individuals over the course of history. But nevertheless, the technique might be useful in regards to regenerating transplant tissues or organs without ever having compromised the ethical, legal, and moral controversies that would arise from deliberately generating whole foetuses or people.

Genetics and Sports

Based on previous research, the genetics factors and its influence on athletes performance varies from 20% to 80%. The factors involved here include cardiorespiratory function, muscle biochemistry, body size and motor skills. Recently research has found a potential link between sprint performance and a particular gene.
This particular gene is the Actinin Alpha-3(ACTN3). The general expression of this gene is limited to the skeletal muscle. Based on recent research, the expression on the ACTN3 is found mostly in elite sprint athletes. However, endurance sports athletes do not show the expression of this gene and it was not inherited. In reference to this knowledge, this opens a window for genetic testing in children. From this, children can see if they are predisposed to certain types of activities or sport.
The University of Sydney also conducted a research which showed results that supported this theory and opened more deeper routes on this issue. The ACTN3 gene has two variants which is the R variant and the X variant. The R variant is involved in the production of muscle protein. Thus, individuals with the R variant would show more rapid and forceful muscle contraction. On the other hand, the X variant has no effect on protein production. Based on the research in the University of Sydney, Sprint athletes have the R variant exclusively while endurance athletes have both the R and X variant. This knowledge has already lead to genetic testing of children for the ACTN3 gene and it’s variant. Based on the results, some parents believe that they can guide a child to excel in the sport that they are gifted in.

Main Reference

MacArthur DG, North KN (2007) ACTN3: A genetic influence on muscle function and athletic performance. Exercise and Sport Sciences Reviews, 35:30-34.

Genetic influences on blood lipids and cardiovascular disease risk

Genetic polymorphism in human populations is part of the evolutionary process that results from the interaction between the environment and the human genome. Recent changes in diet have upset this equilibrium, potentially influencing the risk of most common morbidities such as cardiovascular diseases, obesity, diabetes, and cancer. Reduction of these conditions is a major public health concern, and such a reduction could be achieved by improving our ability to detect disease predisposition early in life and by providing more personalized behavioral recommendations for successful primary prevention. In terms of cardiovascular diseases, polymorphisms at multiple genes have been associated with differential effects in terms of lipid metabolism; however, the connection with cardiovascular disease has been more elusive, and considerable heterogeneity exists among studies regarding the predictive value of genetic markers. This may be because of experimental limitations, the intrinsic complexity of the phenotypes, and the aforementioned interactions with environmental factors. The integration of genetic and environmental complexity into current and future research will drive the field toward the implementation of clinical tools aimed at providing dietary advice optimized for the individual’s genome. This may imply that dietary changes are implemented early in life to gain maximum benefit. However, it is important to highlight that most reported studies have focused on adult populations and to extrapolate these findings to children and adolescents may not be justified until proper studies have been carried out in these populations and until the ethical and legal issues associated with this new field are adequately addressed.

Reference:
http://www.ajcn.org/ (cited on May 10, 2009)

It’s Not Such A Small World After All: DNA Repeats may explain increased human diversity.

Image Caption: A triangle plot showing the clustering of 210 unrelated HapMap individuals assuming three ancestral populations (k = 3). The proximity of an individual to each apex of the triangle indicates the proportion of that genome that is estimated to have ancestry in each of the three inferred ancestral populations. The clustering together of most individuals from the same population near a common apex indicates the clear discrimination between populations obtained through this analysis. The clustering was qualitatively similar to that obtained previously with a similar number of biallelic Alu insertion polymorphisms on different African, European and Asian population samples.

In a series of ongoing research projects, scientists have unearthed evidence that human phenotypes may be influenced by repeated sequences of DNA in addition to the traditional idea of genetic heritage.

A paper published in Nature (23rd of November, 2006) reported the investigation of various affects of differences in the numbers of repeats in sections of DNA, or copy number variations (CNVs), on the genotypes of humans. It states that CNVs are present in all humans and other mammals, and are known in Drosophila melanogaster (an example is the Bar gene causing the Bar eye phenotype).

In humans, the repeats have quite varied effects: the diseases Alzheimer’s and Parkinson’s, both being debilitating and incurable diseases which place great strain on our heath care system, are strongly linked to CNVs. On the other hand, genomes from Africans that were surveyed included numerous repeats in the CCL3L1 gene—greater numbers of repeats giving resistance to HIV-1 infection. Genomes from Asians families included repeats in DNA that may be linked to age-related cataracts and other heritable diseases. If you’re thinking that these varied bits of information on racial genetics suggest something important, you’d be right: CNV analysis has reinforced the idea of diversity in human continental populations! This means that CNV analysis can be used to determine and find the differences between Europeans, Africans and Asians genetically (as in this study’s case)—allowing the investigation of ethnicity and common ancestry in modern human populations, a crucial tool for disease and phenotype analysis in the modern world’s complex assortment of globalised genetics. The specific patterns of CNVs discovered in each population group suggest also that CNV occurrence is influenced by environment (such as the aforementioned HIV resistance in the African gene example). Interestingly, CNVs were found to only rarely occur in ultra-conserved sequences and gene sequences—compared with the common occurrence of conserved non-coding sections and putatively functional genes within CNV regions.

The study also found that CNPs occur in many genes that are already known to cause complex diseases, as well as in genes that are linked to complex traits. It certainly seems that human genetic study has to come a long way before even simple mechanisms such as repeated sequences can be understood.

Article found at: http://www.nature.com/doifinder/10.1038/nature05329
Accessed: 18/5/2009. The paper is available for viewing at this site, and it includes diagrams, references and much greater detail than this summary. Various other related articles may be found by following the links on this page. Also, the webpage of one of the teams involved in the 2006 paper can be found at http://www.sanger.ac.uk/Teams/Team16/ (as of 18/5/2009), and lists many additional papers that have been published from research in a similar vein to this topic.

Unlocking the Genetic Secrets of Africa

The findings of a widespread study into the varied genetic make up of the populations of the continent of Africa were recently published in the online journal: Science Express.

This study collected genetic material from 121 African and African American populations and traced the ancestry of these populations to 14 genetically distinct, modern day population clusters. With this genetic material more then 4 million DNA variations were recorded which indicates the huge range of diversity within Africa. The study also found that the first humans in Africa were probably situated near the South Africa- Namibian border before spreading northeast across Africa and leaving the continent from an area near the Red Sea. When analysing the genetics of African Americans, the study found that these people were likely to have a very diverse mixture of West African ancestry which made tracing the origins of this group difficult.

This study opens new avenues of research including investigations into the genetic basis of disease susceptibility, drug resistance and the evolutionary history of man.


From: The Genetic Structure and History of Africans and African Americans -- Tishkoff et al., Science Express

By Angus Ades

Genetics Holds the key to love at first sight

Does love at first really exist? In fact genetics may have the answer to a question that has bewildered many. From a study published in April 09 , in the issue of the journal “ Genetics” , a team of American and Australian scientists have undergone a series of experiments , which have discovered through a genetic level, that some males and females are more companionable than others. It is this “companionability” which plays a significant part in the “mate selection, mating outcomes and future reproduction behaviour.”

In experiments with fruit flies , it was researched that before mating, the female fruit flies ,contain a genetic factor involved to make them more likely to mate with a particular male, rather than others. Marina Wolfner, a Professor of Developmental Biology at Cornell University suggested that “ Our research helps to shed light on the complex biochemistry involved in mate selection and reproduction”.

But not only can these findings solve the puzzling question of love at first sight, but the results could also mean that populations can be genetically altered by activating or deactivating genes which play a role in these mating decisions. Marina Wolfner suggested that “ These findings may lead to ways to curb unwanted insect populations..”

The scientific team also undertook another experiment, by mating two different strains of fruit fly females to males, and noted the males and females which tended to mate and also the behaviour after mating, as well as reproduction activities; such as the amount of offspring produced or the amount of sperm stored. Also examined was the RNA of females, which was used to compare what genes were expressed in females, when mated to males of different strains. From these results the conclusion established was that the genetic changes for mate selection and reproduction, happened before mating even began.

Mark Johnston , editor of the Journal “GENETICS” concludes “ It appears that females really do care about the character of their consorts, but they may not have as much control over our choice of mates as they’d like to think”.

Original article: (http://www.eurekalert.org/pub_releases/2009-04/foas-ila040709.php)

You Were Always On My Mind

It is a well known fact regarding cancer, that an original tumor can spread to organs throughout the entire body of a patient. Breast cancer is no exception to this trend with cancer often spreading to vital organs of the body such as the lungs, and as medical records now show, to the brain. In humans, the two major genes responsible for breast cancers ability to spread have been identified in mice models as COX2 and HB-EGF. Until recently though, scientists were unsure how the cancer was commonly spreading to the brain.

The brain has a protective mechanism known as the blood-brain barrier, which is a tight network of capillaries and connective tissue that greatly restricts movement of any material between theblood flow of the rest of the body and the blood flow of the brain. This mechanism stops toxins, pathogens and most cancers entering the brain from the rest of the body. Despite this barrier, a recently discovered gene, ST6GALNAC5, is showing to play an important role in assisting breast cancer cells to enter brain tissue. ST6GALNAC5 creates enzymes that cause a chemical reaction on the outside of cancer cells causing them to become sticky. Combined with the action of the

previous two genes mentioned, mobile, sticky cancer cells can now be released into the bloodstream from the original breast cancer. When these sticky cells reach the blood-brain barrier, they are able to attach to the capillaries long enough for the cells to infiltrate into the organ itself where they will replicate and form a new tumor.

The good news out of this discovery is that researchers are confident that drugs can be developed to prevent the products of this gene causing the reaction responsible for breast cancers crossing to the brain. With breast cancer being the top killer of women globally, any advance in stopping even one part of these tumors spreading could save countless lives.

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Reference: http://au.news.yahoo.com/a/-/technology/5549112/genes-help-breast-cancer-spread-brain/, accessed 19/05/09