He associated the human disease to similar symptoms observed in hens. (What symptoms?)

Transcription

1 (6) ) ) ) ) ) ((((((6) (6) (6) = = + = mod 10 (6) 133 mod 43 (85) 133 mod 85 (9) 133 mod 9 (99) 133 mod 99 (36) 133 mod 36 (10)

2 43*6 / * *6 6 mod 133.

3

4 Beriberi - Symptoms include irritability and fatigue, and later, numbness in the fingers and toes, seizures and decreased mental ability. Dutch physician Eijkman, under the influence of Pasteur, believed a bacterium caused beriberi, but failed to identify the agent. (The pre-critical part.) He associated the human disease to similar symptoms observed in hens. (What symptoms?)

5 It is showed that the hens developed the beriberi-like disease soon after their feed was changed to polished rice... and by adding rice bran (the parts removed in polishing) to the hens' food, the disease could be cured.

6 Eijkman and his successor, later used water or ethanol to extract the mysterious antineuritic factor from rice hulls. "There is present in rice polishings a substance different from protein and salts," the two researchers wrote in 1906, "which is indispensable to health and the lack of which causes nutritional polyneuritis." (This work earned him the Nobel prize in 199.) In 196 B. C. P. Jansen and W. Donath, two Dutch chemists working in Eijkman's old laboratory in Jakarta, crystallized the water-soluble antineuritic factor--now called vitamin B1, from rice bran. (Bacterium conjecture really being refuted?)

7 Salt Sodium Chloride Sugar Carbohydrates Protein Amines It is now known that various vitamins contain no amines at all. An example? So the name Vitamin serves as a hallmark of human error and sign of critical thinking. Closing in on Rickets.

8 Sporadic reports of cures for rickets surfaced, including one by feeding cod-liver oil. McCollum in US found out that fat-soluble vitamin A can cure night blindness. It is known that cod-liver oil is rich in vitamin A. This leads to the conjecture that vitamin A was a cure for rickets.

9 McCollum began by heating and aerating the oil to destroy its vitamin A. As expected, the treated oil no longer cured night blindness.. But, to everyone's surprise, it did remain effective against rickets. Clearly, an unknown essential nutrient was responsible. He dubbed the new miracle worker Vitamin D. In recognition of his seminal research on vitamins, McCollum was elected a member of the National Academy of Sciences (USA). (Election to the Academy is considered one of the highest honors that can be accorded a scientist or engineer. The Academy membership is comprised of approximately,000 members and 300 foreign associates, of whom more than 180 have won Nobel Prizes.).

10 Early in the 0 th century, Windaus had embarked on his study of cholesterol and related sterols, about which virtually nothing was known at the time. From the very start, he believed that investigations into the structure of these molecules would yield unexpected results. (198 Nobel Prize in Chemistry) Sterols are nitrogen-free secondary alcohols of high molecular weight

11 By 1975, it is confirmed that vitamin D helps to increase the absorption of Ca In the intestine. In 197, Windaus et al. deduce that ergosterol is the likely parent substance of vitamin D in food. In 1936, Windaus deduces the structure of vitamin D3 produced in skin, and identifies the structure of Its parent molecule, 7-dehydrocholesterol. In 1968, it is shown that an active Vitamin D metabolite is produced in the liver. A final active form of vitamin D is later found to be produce in kidneys. (Hormone?)

12 1,5-dihydroxyvitamin D_3 -- a hormone that not only controls calcium metabolism by increasing intestinal calcium absorption and bone calcium mobilization, but also has many other effects e.g cancer control, immune system. (Eat well and exercise!)

13 TRADITION, PERSONALITY OBJECTIVITY, REASON (1)Personal Use of Imagination; () Connoisseurship subtle nuances; (3) Conviviality; (4) Serendipity.

14 Tumor-like crown gall disease impedes the growth of plants and can cause substantial crop losses. Crown gall tissue is able to develop on a simple medium of salts and sugar for years. On the basis of his experiments, Braun surmised that the plant cells had been permanently transformed into tumor cells by some tumor-inducing factor introduce by the bacterium A. Tumefaciens (1947). (Speculation partly based on fact and partly on imagination.)

15 Double Helix structure of DNA.

16 This DNA is made up of 3 billion base pairs. If printed out, those base pairs would fill more than 1,000 local telephone directories. When people tried to break up DNA molecules into more manageable pieces, however, they ended up with a chaos of random fragments whose order in the original DNA was lost.

17 In the late 1960s, a useful tool came to the rescue from a very unexpected area. At The Johns Hopkins University School of Medicine, a series of studies by Werner Arber and Hamilton Smith on how some bacteria resist invasion by viruses reveal that viral DNA enters these bacteria and is cut into small pieces and inactivated by enzyme. Smith showed that one of these enzymes cut the DNA at a specific short DNA sequence. Sphere?

18 Conviviality at work. Smith's colleague Daniel Nathans recognized that this provided a means of cutting a large DNA molecule into welldefined smaller fragments, and he used the method to generate the first physical map of a chromosome, that of the small monkey virus SV40. The SV40 virus's small genome makes it amenable to research.

19 When the first Bt insecticides were commercialized in the 1930s and 1940s, researchers knew only that they killed insects A critical piece of missing information was how Bt kills insects, i.e., the mechanism behind (subtle nuances). By the 1950s, a series of experiments revealed that proteins produced by Bt bacteria were lethal to particular insect species. By 1980, it s clear that the different proteins produced by different strains of Bt bacteria determined which groups of insects would be killed. By 1989, more than 40 Bt genes, each responsible for a protein toxic to specific groups of insects, had been pinpointed and cloned by various researchers.

20 When both the A. tumefaciens vector for gene transfer and cloned Bt genes became widely available in the mid-1980s, a number of researchers realized that the two could be combined to modify crop plants so that they produce Bt proteins to kill insect pests. Picture depicting a healthy cotton boll in juxtaposition with pest-damaged cotton.

21 By 1987, three groups of scientists had spliced Bt genes into the genomes of cotton plants and exposed the altered plants to bollworms and budworms. Disappointingly, the bioengineered cotton plants showed the same degree of insect damage as the nonmodified cotton plants. -- ``Spelling is wrong! To solve these problems, scientists altered the spelling of the Bt gene. Subtle nuances.

22 New strains of insects that can withstand the toxic proteins produced by Bt. 4% of the field with standard seeds to create a refuge for Bt-susceptible insects. The idea is that the rare Bt-resistant insects that survive feeding on Bt crops will mate with Bt-susceptible insects in the refuge and that the Bt susceptibility trait will predominate in their offspring. Computer models predict that, without such refuges, Bt resistance will be widespread within 10 years. If refuges are used, however, more than 50 years might pass before Bt resistance becomes a major problem.