Fatty acid desaturase-2 (FAD2) introduces a double bond in position 12 in oleic acid (18:1) to form linoleic acid (18:2 n-6) in higher plants and microbes. A new transgenic expression cassette, containing CMV promoter/fad2 cDNA/SV40 polyA, was constructedto produce transgenic mice. Among 63 healthy offspring, 10 founders (15.9%) integrated the cotton fad2 transgene into their genomes, as demonstrated by PCR and Southern blotting analysis. All founder mice were fertile and heterozygous fad2 female and nontransgenic littermates were used for fatty acid analysis using gas chromatography. One fad2 transgenic line showed substantial differences in the fatty acid profiles and the level of linoleic acid was increased 19% (P<0.05) in transgenic muscles compared to their nontransgenic littermates. Moreover, it exhibited an 87% and a 9% increase (P<0.05) in arachidonic acid (20:4 n-6) in muscles and liver, compared to their nontransgenic littermates. The results indicate that the plant fad2 gene can be functionally expressed in transgenic mice and may playan active role in conversion of oleic acid into linoleic acid.
CHEN Qing1, LIU Qing2, WU ZhiFang1, WANG ZongYi3 & GOU KeMian1 1 State Key Laboratory for Agrobiotechnology, China Agricultural University, Beijing 100193, China
Ribosomal protein L8 is a component of the 60S subunit of the ribosome and is involved in protein synthesis but its role in Drosophila development is not well understood.We depleted L8 through RNA interference (RNAi) to examine its effects on fly development both in vivo and in vitro.The results demonstrated that L8 RNAi caused embryonic or first-larval lethality,delay of larval development,defects in eye and wing morphology,and dramatically reduced the number of S2 cells.This indicated that L8 plays a crucial role in Drosophila development.Acridine orange staining of the wing discs showed that apoptosis occurred when L8 was depleted,indicating that depletion of L8 is tightly connected to apoptosis.RT-PCR analyses of the transcription level of genes that are known to be key factors in apoptosis (p53,hid,reaper,dark,Dcp-1) and cell cycle regulation (cdc45,MCM3,cyclin B,incenp) in L8-deficient S2 cells,were consistent with their role in apoptosis induction and cell cycle arrest.These results indicate that depletion of L8 strongly impairs Drosophila development,and that this depletion is associated with cell proliferation arrest and apoptosis,in which p53 may play a central role.
