Silk worm

The new fibers were scientifically interesting—and they eventually laid the foundation for the synthetic textile industry—but at the time they seemed practically worthless. The first polyester fibers resembled those produced by the lowly silk worm, but Carothers did not think that the discovery would be commercially valuable. The polymer chains made in Hill s molecular still were still not long enough to make robust fibers. The filaments melted at such a low temperature and were so soluble that they could not be ironed or washed in dry cleaning fluid or hot water. Carothers knew he would have to make longer polymers if he hoped to make a marketable fiber. Instead, Carothers dramatized the romance of Hill s discovery by quoting the seventeenth-century microscopist, Robert Hooke, who had dreamed of making synthetic silk even better than that Excrement made by silk worms. 

Toyama, K. 1912. On the varying dominance of certain white breeds of the silk-worm, Bombyx mori, L. Mol. Genet. Genomics, 7(l) 252-288. 

Although it is evident from the above discussion that the fatty acids present in the usual vegetable or animal fats do not contribute to the carbohydrate stores in the animal body, there is ample proof that such may be the case in plants and lower organisms. This change has been confirmed in the castor bean where the R. Q. has been found to vary from 0.30 to 0.58 during the period of germination.1660 This could be correlated with the disappearance of fat and the formation of carbohydrate.167 There also seems to be evidence that silk worms are able to build carbohydrate at the expense of fat.168... 

Pheromones, especially insect pheromones, have become common news stories in the popular press and hence are well known to most people. For instance, most elementary schools in the USA now include coverage of pheromones in general science and biology courses. Concomitant with this widespread coverage and inclusion in elementary school curricula is ongoing basic and applied research, which leads to important practical uses and beneficial applications. Since Butenandt s initial report on the pheromone of the silk worm moth, there have been many reviews of pheromones and recent ones are cited here. This review of the chemistry of insect pheromones will cover the isolation and identification of new pheromones and the synthesis of these compounds as well as other recently reported syntheses of important pheromones. 

Selected Properties as a Function of Silk Worm Species... 

Silk Worm Species Approximate Crystallinity (%) Extension at Break Point (%)... 

Silk, used for sutures, is obtained from the cocoon of the silk worm, Bombyx mori. Tension force is gradually lost until tissue encapsulation occurs. Tissue reactivity may be moderate because silk is a protein and its interaction with the body is not benign. It is classified as nonabsorbent because it retains much of its strength for more than 2 months and 50% to half a year, but loses most of its strength after 2 years. While stronger than cotton. 

Silk worm terplnyl acetate llnalool hexenol 61... 

WOOL AND SILK (FROM SILK WORMS) ARE ANIMAL FIBERS. 

Bacillus thuringiensis first isolated from silk worm culture by Ishiwata,... 

Research in this field will not only lead to the production of effective, cheap and environmentally friendly insecticides but will also help to acquire a better understanding and control of infectious diseases of useful insects such as the honey bee and silk worm. 

The cocoon silk of the silk worm is an excellent textile material and the commercial activity in this realm attests to that. Its mechanical properties, however, are rather modest. This has been attributed to the fact that superior mechanical characteristics are not required in the cocoon. On the other hand, in spider s orb-web silk, the spider needs a fiber that can absorb the impact of the falling insect prey. Hence, the need for superior mechanical characteristics. 

Ecdysone is a steroid that is formed and secreted by the prothoracic glands of immature insects but also by the ovaries of adult female insects. It was first isolated from the silk worm, Bombix mori. Bedstone is the prohormone of the moulting hormone eedysterone, but the prohormone has also effects on its own at other stages of insect development. 

Within the context of proteins as polymer materials the number is still further limited, since only very few are available in sufficient bulk at low extraction cost to consider post-processing them into useful materials. More particularly, the fibrous proteins, such as collagen, certain plant proteins such as gluten, the component of wheat responsible for giving the elastic properties to bread doughs, and proteins produced from soy have been exploited to a limited degree, as we shall see below. In recent years there has also been renewed interest in fibrous silk proteins, from silk worms, spiders (as web-silk) and also from bioengineering routes. 

Silk is a fibrous protein produced by several insect species. Commercially, silk is produced from the cocoon stage larvae of the moth caterpillar Bombyx mori, as it has been, in China, for some 4500 years. A single cocoon produces a continuous thread up to 1 km in length, and the protein fibroin contains large amounts of glycine, alanine, tyrosine, proline and serine The peptide chains are arranged in anti-parallel P-sheets which make up the hierarchical structure of the crystalline silk fibres. A number of spiders also produce silk webs, although the fibroin structure is rather different to that from silk worms. 

Since silk fibroin of cultured silkworms contains relatively large amount of achiral glycine residue, silk fibroin cS wild lkworms with a h er content of chiral alanine residue was examined as the carrier of palladium and optical yields of S<+) 14.4% and R-(+) 32.1% were obtained in reaaions (1) and (2), re ctively (3). l n amino groups of silk fibroin of cultured silk worm were acetylated and used as the carrier, the optical yield in reaction (2) was R-(+) 65,9%. 

Polarimeters for measuring optical rotation are so sensitive that they can measure rotations to 0.001°, an important fact when only small amounts of sample are available. Ecdysone, for example, is an insect hormone that controls molting in the silk- < worm moth. When 7.00 mg ecdysone was dissolved in 1.00 mL chloroform and the solution was placed in a cell with a 2.00 cm pathlength, an observed rotation rf +0.087 was found. Calculate [a]n for ecdysone. 

Fig. 18 Powder X-ray patterns of degummed native silk fibroin (SF) fibers from the Bombyx mori silk worm (a), SF precipitated from a Ca(NC>3)2 -4H20/2Me0H solution (b), and SF coalesced from its y-CD-IC (c)...

Japanese authors were the first to establish insect disease of bacterial origin, when discovering the pathogen of the epidemic disease of the silk worm (Ishida, 1901). Berliner (1911 1915) found that the same bacterium, which he called Bacillus... 

In the case of insects, decisive proof in favour of the material contact theory was furnished by the findings of Butenandt el al. (1959). As a result of long research work, they isolated the sex attractant substance produced by the female of the silk worm, Bombyx mori, and identified it as ( )-10-(2T)-12-hexadecadienol (bom bykol, 1). Determination of the active structure was achieved by the synthesis and biological testing of the four possible isomers (Butenandt et al., 1959). 

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