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Chitin Content (chitin + content)

Distribution by Scientific Domains

Life Sciences	80%

Selected Abstracts

The Tribolium chitin synthase genes TcCHS1 and TcCHS2 are specialized for synthesis of epidermal cuticle and midgut peritrophic matrix

INSECT MOLECULAR BIOLOGY, Issue 5 2005
Y. Arakane
Abstract Functional analysis of the two chitin synthase genes, TcCHS1 and TcCHS2, in the red flour beetle, Tribolium castaneum, revealed unique and complementary roles for each gene. TcCHS1- specific RNA interference (RNAi) disrupted all three types of moult (larval,larval, larval,pupal and pupal,adult) and greatly reduced whole-body chitin content. Exon-specific RNAi showed that splice variant 8a of TcCHS1 was required for both the larval-pupal and pupal-adult moults, whereas splice variant 8b was required only for the latter. TcCHS2 -specific RNAi had no effect on metamorphosis or on total body chitin content. However, RNAi-mediated down-regulation of TcCHS2, but not TcCHS1, led to cessation of feeding, a dramatic shrinkage in larval size and reduced chitin content in the midgut. [source]

Mode of action of etoxazole

PEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 5 2006
Ralf Nauen
Abstract The mode of action of the 2,4-diphenyl-1,3-oxazoline acaricide/insecticide etoxazole has been argued to be moulting inhibition, but experimental results supporting this hypothesis are lacking. This study investigated the effect of etoxazole on chitin biosynthesis in the fall armyworm, Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae). Etoxazole induced moulting defects in fall armyworm larvae similar, if not identical, to those caused by benzoylphenylureas, a well-known class of insecticidal chitin biosynthesis inhibitors. Furthermore, in contrast to untreated larvae, the chitin content in the integuments of larvae several days after treatment did not differ from that in freshly ecdysed individuals, thus suggesting strong chitin biosynthesis inhibition in vivo. A more detailed investigation of the inhibitory potential by incubating cultured integument pieces from larvae of S. frugiperda with [14C]N -acetyl- D -glucosamine, a radiolabelled chitin precursor, revealed I50 values of 2.95 and 0.071 µM for etoxazole and triflumuron respectively. The incorporation of radiolabel into potassium hydroxide-resistant material was inhibited by etoxazole in a dose-dependent manner. Based on these results, it is concluded that the acaricidal and insecticidal mode of action of etoxazole is chitin biosynthesis inhibition. Copyright © 2006 Society of Chemical Industry [source]

Ovary colonization by Claviceps africana is related to ergot resistance in male-sterile sorghum lines

PLANT PATHOLOGY, Issue 5 2003
B. Komolong
Ergot, caused by Claviceps africana, has emerged as a serious threat to sorghum hybrid seed production worldwide. In the absence of gene-for-gene-based qualitative resistance in commercial cultivars, varieties with high pollen production that can escape ergot infection are preferred. Recent demonstration of differences in ergot susceptibility among male-sterile lines has indicated the presence of partial resistance. Using chitin-specific fluorescin-isothiocyanate-conjugated wheat germ agglutin and callose-specific aniline blue, this study investigated the process of sorghum ovary colonization by C. africana. Conidia germinated within 24 h after inoculation (a.i.); the pathogen was established in the ovary by 79 h a.i., and at least half of the ovary was converted into sphacelial tissue by 120 h a.i. Changes in fungal cell wall chitin content and strategic callose deposition in the host tissue were associated with penetration and invasion of the ovary. The rate of ovary colonization differed in three male-sterile lines that also differed in ergot susceptibility. This work demonstrates a possible histological basis for partial resistance in male-sterile sorghum lines that could lay the foundation for variety improvement through further breeding and selection. [source]

Adverse effect of the chitinolytic enzyme PjCHI-1 in transgenic tomato on egg mass production and embryonic development of Meloidogyne incognita

PLANT PATHOLOGY, Issue 5 2010
Y.-L. Chan
A novel chitinase gene (PjCHI-1) isolated from Paecilomyces javanicus, a non-nematophagous fungus, and driven by a CaMV35S promoter, was delivered into CLN2468D, a heat-tolerant cultivar of tomato (Solanum lycopersicum). T1 tomato plants exhibited high endochitinase activity and reduced numbers of eggs and egg masses when infected with the root-knot nematode (RKN) Meloidogyne incognita. The eggs found in transgenic tomato had lower shell chitin contents than eggs collected from control plants. Egg masses from transgenic plants exhibited higher chitinase activity than those from control plants. Moreover, only 30% of eggs from transgenic plants were able to develop to the multi-cell/J1 stage, compared with more than 96% from control plants. The present study demonstrated that the expression of the PjCHI-1 chitinase gene can effectively reduce the production of egg masses and repress the embryonic development of M. incognita, presenting the possibility of a novel agro-biotechnological strategy for preventing crop damage by RKN. [source]