SciBlogs

Posts Tagged Megan Leask

This Week in Science History: 1-11-10 Genetics Otago Nov 04

1 Comment

This week in Science History
Megan Leask, PhD Student, Laboratory for Evolution and Development

Polio Virus is Crystallized — 1955

In 1955, on the 2nd of November American sciemtists Carlton Schwerdt and F.L. Schaffer crystallized the polio virus. This was the first animal virus to be obtained in crystalline form. (The first plant virus, tobacco mozaic virus, had been crystallized in 1935 by W.M. Stanley.) Each virus crystal is composed of many thousands of virus particles. Virus preparations pure enough to crystallize usually provide the best material for chemical study. The crystallized form was used to split the virus into infectious and non-infectious parts. Their research laid the groundwork for the polio vaccine.

Émile Roux – Died 3 Nov 1933 (born 17 Dec 1853)

Émile Roux was a French bacteriologist who began working with Louis Pasteur in 1878. He was noted for his work on diphtheria. In 1888, Roux and Alexandre Yersin isolated a soluble toxin from cultures of diphtheria. The bacterium itself, though only found in the throat, can destroy tissues and organs throughout the body, thus they proposed that a chemical toxin was responsible. They filtered diphtheria cultures to remove the bacteria and then used the remaining fluid filtrate into healthy animals. As expected the animals showed diphtheria lesions but without any obvious presence of bacteria thus demonstrating that a toxin is the active agent causing diphtheria. Émile Roux became director of Pasteur Institute at Paris in 1904.

Nature — The First Publication

In 1869, on the 4th of November, the first issue was published of the journal Nature, edited by astronomer Sir Norman Lockyer. The first issue included articles on astronomy, plants, moths, science teaching in schools, an obituary for Thomas Graham, paleontology and meeting notices. Nature remains one of the most popular and well respected science journals in the world, printing research articles from across a wide range of scientific fields.

This Week in Science History: 25-10-10 Genetics Otago Oct 27

No Comments

This week in Science History

Megan Leask, PhD Student, Laboratory for Evolution and Development

Marian Koshland Born 25 Oct 1921; died 28 Oct 1997.

Koshland was an American immunologist who discovered that the differences in amino acid composition of antibodies explains the efficiency and effectiveness with which they combat a huge range of foreign invaders. In 1970 she became a professor of Microbiology and Immunology, after which she discovered the J chain (a B cell antibody subunit).  In 1991, with colleagues, she identified a specialized intracellular pathway that transports antibodies into blood circulation, allowing for the multiplication of B cells essential in fighting infection.

Sir Richard Doll Born 28 Oct 1912; died 24 Jul 2005.

British epidemiologist who was one of the first two researchers to link cigarette smoking to lung cancer, as published in the British Medical Journal in 1950. In the same journal, fifty years later, Doll published (22 Jun 2004) the first research that quantified the damage over the lifetime of a generation, based on a 50-year study of a group of almost 35,000 British doctors who smoked. The study found that almost half of persistent cigarette smokers were killed by their habit, and a quarter died before age 70. Persons who quit by age 30 had normal life expectancy. Even quitting at age 50 saved six more years of life over those who continued smoking. He studied other health effects, such as those caused by asbestos and electromagnetic fields.

Daniel Nathans – Born 30 Oct 1928; died 16 Nov 1999.

American microbiologist, corecipient of the Nobel Prize for Physiology or Medicine in 1978 (with American Hamilton Othanel Smith and Swiss scientist Werner Arber). The winners were cited for their discovery and application of restriction enzymes, which provide the “chemical knives” to cut genes (DNA) into defined fragments. Restriction enzymes are used as a tool in genetics in conjunction with other tools to analyse the sequence, expression and function of genes.

This Week in Science History: 18-10-10 Genetics Otago Oct 18

No Comments

This week in Science History

Megan Leask, PhD student, Laboratory for Evolution and Development

Queen of the Flies – Christiane Nüsslein-Volhard is born 20 Oct 1942

Untitled

Expression of the Engrailed protein (one of the genes identified by Nüsslein-Volhard) in an aphid embryo. The protein is labeled with a purple dye and can be seen in cells that make up the nervous system and in stripes indicating the location of the segments. Image: Megan Leask

German developmental geneticist Christiane Nüsslein-Volhard shared the 1995 Nobel Prize for Physiology or Medicine (with Edward Lewis) for research into the mechanisms of early embryonic development. She co-authored with Eric Wieschaus the Nature paper “Mutations Affecting Segment Number and Polarity in Drosophila,” (1980), which revolutionised the field of developmental genetics. In a systematic search for mutant genes affecting the formation of segments in the eggs of a small fruit fly, they identified the developmental pathway that leads to segmentation, elucidating one of the main processes of development in the fruit fly embryo. In the Laboratory for Evolution and Development at Otago this process is being analysed in both aphids and honeybee. Investigation of this process in other insects makes it possible to elucidate how developmental pathways have evolved throughout the insect lineage.

George Wells Beadle – Born 22 Oct 1903; died 9 Jun 1989.

George Wells Beadle was an American geneticist who helped found biochemical genetics when he showed that genes are responsible for regulating chemical events. He shared the 1958 Nobel Prize for Physiology or Medicine with Edward Tatum and Joshua Lederberg. Beadle and Tatum succeeded in demonstrating that key molecules in the body are synthesized in the individual cell in a step by step fashion in long chains of chemical reactions, and that genes control these processes by individually regulating the steps in the synthesis chain. This regulation takes place through formation of enzymes which are encoded by genes in our DNA.

Discovery of the TB bacterium

In 1882, (Heinrich Hermann) Robert Koch discovered the tuberculosis germ (tubercle bacillus). He was a German physician and one of the founders of the science of bacteriology. He discovered the tubercle bacillus and the cholera bacillus. He won the 1905 Nobel Prize for Physiology or Medicine for his investigations and discoveries in relation to tuberculosis. In addition Koch made important investigations concerning plague in humans, malaria and tropical dysentery.

This Week in Science History: 4-10-10 Genetics Otago Oct 05

2 Comments

This week in Science History
Megan Leask, PhD Student, Laboratory for Evolution and Development

It’s Nobel week!

Michael Smith – died 4th of Oct 2000 (born 26 Apr 1932)

British-born Canadian biochemist who won (with Kary B. Mullis, inventor of PCR) the 1993 Nobel Prize for Chemistry for his development of a technique called oligonucleotide-based site-directed mutagenesis. This technique enabled researchers to introduce specific mutations into genes and, thus, to the proteins that they encode. The prize recognized his groundbreaking work in reprogramming segments of DNA, the building blocks of life. His work launched a new era in genetics research.

Prion discovery leads to Nobel Prize for Stanley Prusiner

Tonsil biopsy in variant CJD. Prion Protein immunostaining (Image: Sbrandner, Wikimedia Commons)

In 1997 on the 6th of October, American biology professor Stanley B. Prusiner won the Nobel Prize for medicine for discovering “prions,” described as “an entirely new genre of disease-causing agents.” Prusiner’s work proposed an explanation for the cause of bovine spongiform encephalopathy (“mad cow disease”) and its human equivalent, Creutzfeldt-Jakob disease. In this work, he coined the term prion, which comes from the words “proteinaceous” and “infectious,” to refer to a previously undescribed form of infection due to protein misfolding.

Prions propagate by transmitting a mis-folded protein state: so as with viruses the protein cannot replicate by itself. Instead, when a prion enters a healthy organism the prion form of a protein induces pre-existing normal forms of the protein to convert into the rogue form. Since the new prions can then go on to convert more proteins themselves, this triggers a chain reaction that produces large amounts of the prion form.

Franklin William Stahl – Born 8 Oct 1929

Franklin William Stahl is a U.S. geneticist who, in 1958, (with Matthew Meselson) elucidated the mode of replication of deoxyribonucleic acid (DNA) a double-stranded helix that dissociates to form two strands, each of which directs the construction of a new sister strand. They grew E. coli on media (food) that contained the heavier isotope of nitrogen-15 causing all of their DNA to be heavy. They switched the E. coli to media that contained normal nitrogen and then analyzed the DNA after each generation. After one generation, all of the DNA was medium-weight. Thus one strand of the double helix was heavy and one strand was light. After two generations, half of the DNA was medium-weight and half was normal light-weight DNA.

Maurice Hugh Frederick Wilkins – Died 5 Oct 2004 (born 15 Dec 1916)

Photo 51, an historic X-ray diffraction image of DNA (Image: Rosalind Franklin)

Photo 51, an historic X-ray diffraction image of DNA (Image: Rosalind Franklin)

Maurice Hugh Frederick Wilkins was a biophysicist, whose X-ray diffraction studies of deoxyribonucleic acid (DNA) were significant in the determination of the molecular structure of DNA accomplished by James Watson and Sir Francis Crick. For this work the three scientists shared the 1962 Nobel Prize for Physiology or Medicine. Wilkins was born in Pongaroa, north Wairarapa, New Zealand, his family moved to Birmingham, England when he was 6.

This week in Science History: 27-9-10 Genetics Otago Sep 27

No Comments

This week in Science History

Megan Leask, PhD Student, Laboratory for Evolution and Development

George Harrison Shull – Died 28 Sep 1954 (born 15 Apr 1874)

American botanist and geneticist known as the father of hybrid corn (maize). A leader in developing the multiple allele concept of genes, Shull’s work with maize led him to develop the first hybrid corn, ancestor of today’s sweet corn. Shull’s approach was to study the effects of inbreeding and subsequent cross-fertilization in corn. In 1909, he published A Pure Line Method of Corn Breeding in which he outlined the basics of breeding hybrid corn. As a result of his research corn yields per acre were increased 25 to 50 percent.

Louis Pasteur – Died 28 Sep 1895 (born 27 Dec 1822)

Louis Pasteur

Louis Pasteur

French chemist who became a founder of microbiology. He began as a chemist working on the optical properties of tartaric acid and its stereochemistry (1849). He then moved into microbiology where he discovered the role of bacteria in fermentation – that it was micro-organisms in yeast causing the formation of alcohol from sugar – and proved that the growth of microorganisms was not spontaneously generated from non-living matter. This led to understanding of the germ theory of infection, and his method of killing harmful bacteria in liquids by holding them for a time at a given temperature, which is now known as pasteurisation. He created and tested vaccines for diphtheria, cholera, yellow fever, plague, rabies, anthrax, and tuberculosis.

Thalidomide first marketed in Germany – 1st October 1957

In 1957, on the 1st of October the notorious drug thalidomide was first marketed in West Germany and shortly sold in at least 46 countries. Patented by Chemie Grünenthal in 1953 as a sedative, it seemed a wonder drug for pregnant women to combat symptoms associated with morning sickness. However the drug’s molecules crossed the placental wall, tragically affecting the proper growth of the foetus. Worldwide, over 10,000 babies were born by the early 1960′s with substantial birth defects, including deafness, blindness, internal disabilities, cleft palate, deformed or even missing limbs. Survivors, now middle-aged adults, have continuing health problems.

This Week in Science History – 20/9/10 Genetics Otago Sep 20

No Comments

This week in Science History

Megan Leask, PhD Student, Laboratory for Evolution and Development

Ötzi the Iceman discovered in his frozen glacial tomb

Otzi the Iceman (Image: Wikimedia Commons)

Otzi the Iceman (Image: Wikimedia Commons)

In 1991 on the 19th of September, Ötzi the Iceman, a wanderer who lived approximately 5300 years ago, was discovered in the Schnalstal Glacier in the Ötztal Alps, on the border between Austria and Italy. The nickname Ötzi comes from Ötztal (Ötz valley), the region in which he was discovered. He is Europe’s oldest natural human mummy, and has offered an unprecedented view of Chalcolithic (Copper Age) Europeans. The body and his belongings are displayed in the South Tyrol Museum of Archaeology in Bolzano, northern Italy. A group of scientists have sequenced Otzi’s full genome and promised to reveal it in 2011.

Uncovered: DNA holds the genetic code

In 1952, on the 20th of September, Alfred Hershey and Martha Chase published a report confirming that DNA holds hereditary data. Their experiment used the T2 bacteriophage, which, like other viruses, is a crystal of DNA and protein. It can reproduce when inside a bacterium such as E. coli. Hershey and Chase were seeking an answer to the question, ’Is it the viral DNA or viral protein coat (capsid) that is the viral genetic code material which gets injected into the E. coli?’ Their results indicated that the viral DNA, not the protein, is its genetic code material.

Lord of the Flies – Thomas Hunt Morgan – Born 25 Sep 1866; died 4 Dec 1945

Thomas Hunt Morgan

Thomas Hunt Morgan

American zoologist and geneticist and Nobel laureate (1933), Thomas Hunt Morgan was born in Lexington, Kentucky on the 25th of September. At Columbia University (1904-28), he began his revolutionary genetic investigations of the fruit fly Drosophila (1908). Initially skeptical of Gregor Mendel‘s research, Morgan performed rigorous experiments which demonstrated that genes were linked in a series on chromosomes and are responsible for identifiable, hereditary traits. In 1910 he discovered sex-linkage in Drosophila, where the phenotypic expression of an allele is related to the chromosomal sex of the individual. With his “fly room” colleagues, he mapped the relative positions of genes on Drosophila chromosomes, then published his seminal book, The Mechanisms of Mendelian Heredity (1915).

This Week in Science History: 13-9-10 Genetics Otago Sep 13

1 Comment

This week in Science History

Megan Leask, PhD student, Laboratory for Evolution and Development

This week in science history we celebrate the ’little things’ in life.

Hans Christian Joachim Gram Born 13th September 1853

A Gram stain of mixed Staphylococcus aureus (Gram positive cocci, purple) and Escherichia coli (Gram negative bacilli, pink). (Image: Y Tambe, Wikimedia Commons)

A Gram stain of mixed Staphylococcus aureus (Gram positive cocci, purple) and Escherichia coli (Gram negative bacilli, pink). (Image: Y Tambe, Wikimedia Commons)

Danish pharmacologist and pathologist Hans Christian Joachim Graminvented the Gram stain, the best known and most widely used bacteriological staining method that is almost always the first test performed for the identification of bacteria. Gram staining differentiates bacterial species into two large groups (Gram-positive and Gram-negative) based on the chemical and physical properties of their cell walls.

The term ’bacteriophage’ is coined in a note from Dr. Félix d’Hérelle to the French Academy of Sciences dated the 15th September 1917

An electron micrograph of bacteriophages attached to a bacterial cell. (Image: Graham Colm, Wikimedia Commons)

An electron micrograph of bacteriophages attached to a bacterial cell. (Image: Graham Colm, Wikimedia Commons)

French-canadian microbiologist Félix d’Hérelle, working at the Pasteur Institute in Paris discovered “an invisible, antagonistic microbe of the dysentery bacillus”. For d’Hérelle, there was no question as to the nature of his discovery: “In a flash I had understood: what caused my clear spots was in fact an invisible microbe … a virus parasitic on bacteria.’ Bacteriophage cause spots of lysis on agar plates that have a layer of bacteria on them. Basically bacteriophage infect bacteria and can either lay dormant in the bacteria’s genome or lyse the cell after making copies of itself. D’Hérelle called the virus a bacteriophage or bacteria-eater (from the Greek phagein meaning to eat). Bacteriophages have been used for over 60 years as an alternative to antibiotics in the former Soviet Union and Eastern Europe and are seen as a possible therapy against multi drug resistant strains of many bacteria.

Sir Ronald Ross died 16th September 1932 (born 13 May 1857)

Plasmodium falciparum ring-forms and gametocytes in human blood. (Image: Wikimedia Commons)

Plasmodium falciparum ring-forms and gametocytes in human blood. (Image: Wikimedia Commons)

Sir Ronald Ross was a British bacteriologist who received the Nobel Prize for Physiology or Medicine in 1902 for his work on malaria. His discovery of the malarial parasite (a unicellular organism from the genus Plasmodium) in the gastrointestinal tract and saliva of the Anopheles mosquito led to the realization that malaria was transmitted from person to person through the bite of the mosquito. Malaria is widespread in tropical regions and each year kills between one and three million people. When a mosquito bites an infected person, a small amount of blood is taken, which contains malaria parasites. These develop within the mosquito, and about one week later, when the mosquito takes its next blood meal, the parasites are injected with the mosquito’s saliva into the person being bitten. In the liver of the infected person, the malaria parasites start to multiply within red blood cells, causing symptoms that include fever, and headache. In severe cases the disease worsens leading to hallucinations, coma, and death. Malaria transmission can be reduced by preventing mosquito bites by distribution of inexpensive mosquito nets and insect repellents, or by mosquito-control measures such as spraying insecticides inside houses and draining standing water where mosquitoes lay their eggs.

Antonie van Leeuwenhoek discovers unicellular organisms, 17th September, 1683

In 1683, the Dutch scientist commonly known as “the Father of Microbiology“, and considered to be the first microbiologist wrote to the Royal Society reporting his discovery of microscopic living ’animalcules’ (unicellular organisms). Using his handcrafted microscopes he made observations from the plaque between his own teeth “in the said matter there were many very little living animalcules.” He was also the first to record microscopic observations of muscle fibers, bacteria, spermatozoa and blood flow in capillaries.

This week in Science History: 6-09-10 Genetics Otago Sep 06

2 Comments

This week in Science History
Megan Leask, PhD student, Laboratory for Evolution and Development

Production of human insulin by bacteria: 6 September, 1978

In 1978 on the 6th of September U.S. scientists announced the production of human insulin by a strain of E. coli bacteria, that had been genetically engineered after months of creative use of gene-splicing techniques.

A normal body’s production of insulin takes place within cells of the pancreas. In patients with type I diabetes, however, this production does not occur and thus they require insulin injections in order to control their blood glucose levels. Purified animal-sourced insulin was the only type of insulin available to diabetics until this amazing feat in genetics research occurred and, in 1982, insulin was the first recombinant DNA drug to be marketed, Humulin by Eli Lilly & Co.

John Snow removes the handle of the Broad Street water pump: 8 September, 1854

It is 1854, Soho, London, 500 people have died from a large cholera outbreak, and the hero of the story is an anesthetist by the name Dr John Snow. On September 8th he removed the handle of the Broad Street water pump in London, effectively halting any further spread of cholera. He identified drinking water as the vessel for transmission of the disease after he discovered that cholera cases occurred in the homes which obtained their water from the Broad Street Pump. The move is considered one of the most symbolic gestures in the history of public health at a time when it was thought that diseases such as cholera, chlamydia or the Black Death were caused by a miasma (ancient Greek: “pollution”), a noxious form of “bad air”.

Scientifically John Snow contributed to the formation of the germ theory but it wasn’t until 1890 when Robert Koch devised a series of proofs that the germ theory of disease became widely accepted. The “John Snow” pub now stands beside the pink granite slab marking the site of the original pump.

Alec Jeffreys envisions DNA fingerprinting: 10 September, 1984

On the 10th of September 1984, geneticist Alec Jeffreys had a ’eureka moment’ in his lab in Leicester, England. Within half an hour after looking at an X-ray film image of a DNA experiment, which unexpectedly showed both similarities and differences between the DNA of different members of his technician’s family, he realized the possible scope of DNA fingerprinting.

DNA fingerprinting is a technique that uses variations in the genetic code to identify individuals. DNA fingerprinting was first used as a police forensic test to identify the rapist and killer of two teenagers, Lynda Mann and Dawn Ashworth, who were both murdered in Narborough, Leicester in the 1980s. Colin Pitchfork was identified and convicted of the murders after samples taken from him matched semen samples taken from the two dead girls. This turned out to be a godsend  for Richard Buckland, the main suspect, who could have been convicted and sent to jail for life for murders he did not commit.

DNA fingerprinting has since been superseded by the advent of Polymerase Chain Reaction, which allows the amplification of specific areas of genetic code. Regions of DNA called microsattelites or short tandem repeats vary amongst the population and by testing ten microsattelites plus a marker for sex the discrimination power of DNA fingerprinting is one in over a billion.

Network-wide options by YD - Freelance Wordpress Developer