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Threads and Nets Made By Invertebrates
Šuláková, Eva ; Říhová, Dagmar (advisor) ; Hanel, Lubomír (referee)
This diploma thesis is focused on the silk production of invertebrates. The aim of the work is to systematically introduce important species and describe the purpose of their silk production. The ability to produce silk is widespread in many insect families. The production of proteinaceous fibers also occurs in arachnids and (in the form of byssus threads) also in mollusks. The Domestic Silk Moth (Bombyx mori) is an economically important insect, being a primary producer of silk. Hence, an integral part of the thesis focuses on Domestic Silk Moth. In this thesis all developmental stages of Silk Moth (from an egg to an adult) are described. In the past, efforts to breed silkworms also appeared in the Czech lands. Therefore, a short chapter of the thesis is devoted to the history of sericulture. Furthermore, this thesis describes methods of rearing silkworm larvae. For students of Natural Sciences and Biology, it is crucial to be in touch with live objects. Because the silkworm rearing is quite simple, it is possible to incorporate this topic to the school projects about holometabolous insects. The practical part of this thesis contains schedule of practical exercise about silk moths. And in final section of practical part, worksheets for lower-secondary students are presented. Keywords: silkworm...
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Are silkworm males capable of producing vitellogenin?
VRCHOTOVÁ, Markéta
The eggs of the silkworm, Bombyx mori, obtained from the ovaries implanted into male hosts are able to complete embryonic and post-embryonic development in spite of the very low amount of vitellogenin. Using polyacrylamide gel electrophoresis, I searched for differences between the protein spectra of eggs from standard females and the eggs from ovaries implanted into the males. I also examined the variability of protein spectra in the eggs of several parthenoclones. I confirmed great differences in the egg protein spectra between the eggs from females and those from the ovaries implanted into males. Both heavy (180 kDa) and light (42 kDa) subunits of vitellogenin were present in the eggs from females but only the heavy subunit of vitellogenin was found in the eggs developed in ovaries implanted into male hosts. Interesting interactions between transplanted gonads and the host milieu were observed. All compared parthenoclones contained similar patterns of the main yolk proteins but differed slightly in some high-molecular weight protein fractions.
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Studies on the sericin 3 of \kur{Bombyx mori} and cloned sericin into \kur{Escherichia coli}
KRŮČEK, Tomáš
The spun-out silk fiber consists of two fibroin filaments that are cemented together by sericin coating. The serine-rich sericins, which make 20-30% of the cocoon silk proteins in Bombyx mori, are dissolved in hot water during silk fiber reeling from the cocoon. The sericin extract is usually discarded. Only small amounts are currently used in cosmetics and lately also as replacement of bovine serum products in the cell culture media. The use in culture media is hindered by poor standardization of the extracts. To overcome this problem, we attempted preparation of several recombinant proteins based on partial sequences of one out of the three sericin genes of Bombyx mori, sericin 3. Translation product of the Ser3 gene is extremely serine-rich with a relatively high representation of the aspartate, asparagin, glutamate, and glutamine. Using specific primers we have prepared a cDNAs of 267, 279, 525, 672, and 528 bp, respectively, derived from the Ser3 gene. The cDNAs were cloned and expressed as fusion proteins with hexahistidine in Escherichia coli. The proteins were purified by affinity chromatography and analyzed by acrylamide electrophoresis. Ser3 gene contain repetitive motifs rich in serine and including some charged amino acids.
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