Nutritional requirements for protein synthesis during parasitic development of the entomophilic nematode Mermis nigrescens

Parasitology - Tập 64 Số 1 - Trang 161-172 - 1972
Roger Gordon1, John Webster1
1Pestology Centre, Department of Biological Sciences, Simon Fraser University, Burnaby, Vancouver, B.C., Canada

Tóm tắt

Adult desert locusts were experimentally infected with a dose of 50 M. nigrescens ova and larval nematodes removed 14, 17, 21 and 24 days afterwards for in vitro radiotracer studies. These nematodes were incubated under controlled conditions either in a nutrient medium or in insect saline, which contained the appropriate 14C or 3H-labelled radioisotope. The rate of incorporation of the radioisotope into the proteins of the nematode was measured.The rate of incorporation of 14C-leucine into proteins was greatest for the 17- day-old larvae and this accorded with the in vivo growth pattern of the nematode. This isotope was incorporated less rapidly into proteins by the 14-, 21 and 24-day- old larvae, which synthesized proteins at approximately the same rates as each other. A non-linear rate of incorporation was manifest for each of the larval stages.Total dry weight and protein determinations showed that the nematode synthesizes relatively large quantities of non-proteinaceous reserves during the third week of infection, whilst proteins are preferentially synthesized between the 21st and 24th days of infection.The 17-day-old nematode larvae were able to incorporate six 14C-amino acids into proteins to varying degrees. Leucine was incorporated most effectively into nematode proteins, whilst glutamic acid was the least incorporated of the six amino acids.These nematode larvae could not effectively metabolize the 3H-dipeptide histidyl-leucine and incorporate its component amino acid residues into proteins. Similarly, a preparation of 3H-haemolymph proteins were not significantly metabolised and incorporated into proteins by the nematode. However, the nematode metabolized and incorporated an exogenous source of 14C-glucose into proteins at relatively high levels.Incorporation of 14C-luecine into proteins was seven times more rapid for nematodes incubated in buffered insect saline than for those incubated in a more complete nutrient medium.The dietary requirements of the nematode for protein synthesis were discussed in relation to their associated effects upon the host metabolism and an active transport of dietary amino acids into the nematode was postulated.We wish to thank Dr H. L. Speer and Dr K. K. Nair for their helpful suggestions regarding radioisotope techniques. Thanks are also due to the National Research Council of Canada for providing financial assistance (Grant No. A4679).

Từ khóa


Tài liệu tham khảo

10.1016/0014-4894(58)90012-2

10.1016/0006-3002(61)90274-8

Read, 1966, Biology of Parasites, 101

Lee, 1965, The Physiology of Nematodes, 154

10.1016/0014-4894(70)90030-5

10.1163/187529264X00268

10.3181/00379727-91-22288

10.1016/0003-2697(60)90025-7

10.1017/S0031182000012063

10.2307/3277338

10.1085/jgp.39.6.841

10.1071/BI9570465

10.2307/3277652

Beucher, 1971, Cultivation of Caenorhabditis briggsae and Turbatrix aceti with defined proteins, Journal of Nematology, 3, 89

10.1016/0014-4894(71)90012-9

10.1139/z71-066

10.1098/rspb.1963.0007

10.1016/0022-1910(70)90088-0

10.1042/bj0800332

Jackson, 1969, Germ-Free Biology, 331

10.1016/0022-1910(65)90027-2

10.1016/0022-1910(69)90186-3

10.1016/0014-4894(62)90064-4

Thông tin
Thông tin xuất bản

Parasitology

Tập 64 Số 1

161-172

Thông tin tác giả