Functional characterization of a Δ6 fatty acid desaturase gene and its 5′-upstream region cloned from the arachidonic acid-rich microalga Myrmecia incisa Reisigl(Chlorophyta)

It is suggested that Δ6 fatty acid desaturase(FAD) plays a critical role in the biosynthesis of polyunsaturated fatty acids in plants and microalgae. But why does it adapt to the changed environments such as nitrogen starvation is seldom understood. One Δ6 FAD gene( MiD6 fad) from an arachidonic acidrich microalga M yrmecia incisa Reisigl(Chlorophyta) was first heterologously expressed in S accharomyces cerevisiae for the identification of function. The fatty acid profile of transgenic yeast detected by gas chromatography-mass spectrometry illustrated that the enzyme MiD6 FAD could convert linoleic and ?-linolenic acids to γ-linolenic and stearidonic acids, respectively, demonstrating that M iD6 fad encoded a Δ6 FAD. A 1 965-bp fragment of the cloned 2 347-bp 5′-upstream region of M iD6 fad was next subcloned and fused upstream with green fluorescent protein(GFP) gene to replace the GAL1 promoter of the vector pYES2. The generated construct was transformed into S. cerevisiae for function determination. Confocal microscopic images of the transformed line illustrated that this inserted fragment could drive GFP expression, which was further verified by fluorescence intensity quantification and Western blot analysis using antiGFP antibody. The conversion efficiency(approximately 2%-3%) of MiD6 FAD was much lower than the reported ? 3 FAD and Δ6 elongase in this microalga, suggesting that MiD6 FAD catalysed the possible ratelimiting step for ArA biosynthesis. The presence of several putative c is-acting regulatory elements in this identified promoter sheds new light on the regulation mechanism research of Δ6 FAD transcription for the ArA production in M. incisa in changing environmental factors.

Point mutation of 5' noncoding region of BCL-6gene in primary gastric lymphomas

AIM: To investigate the mutations of the 5' noncoding region of BCL-6 gene in Chinese patients with primary gastric lymphomas. METHODS: PCR and direct DNA sequencing were used to identify BCL-6 gene mutations in the 5' noncoding region in 29 cases of gastric diffuse large B-cell lymphoma (DLBCL) and 18 cases of gastric mucosa-associated lymphoid tissue (MALT) lymphoma as well as 10 cases of reactive hyperplasia of lymph node (LRH). RESULTS: Six of 29 gastric DLBCLs (20.7%), 4 of 18 gastric MALT lymphomas (22.2%) and 1 of 10 LRHs(10%) were found to have mutations. All mutations were single-base substitutions and the frequency of single-base changes was 0.20×1O^(-2)-1.02×1O^(-2)per bp. CONCLUSION: Point mutations in the 5' noncoding region of BCL-6 gene are found in Chinese patients with primary gastric DLBCLs and MALT lymphomas, suggesting that they may, in some extent, participate in the pathogenesis of primary gastric DLBCLs and MALT lymphomas.

Genomic structure analysis of SNC6, a progesterone-receptor associated protein gene, and cloning and characterization of its 5＇-flanking region

Objective: To analyze the genomic structure of SNC6, a progesterone\|receptor associated protein gene and its regulatory elements in its 5'\|flanking region. Methods: Genomic sequence from GenBank database (accession number: Z98048) covering the whole SNC6 gene was used to analyze the genomic structure of SNC6 and design primers for PCR amplification of its 5'\|flanking region. A 1894 bp fragment of the 5'\|flanking region \{(-1814\} to +75) was cloned by PCR using genomic DNA from a healthy donor peripheral blood lymphocyte as template. This fragment, as well as 3 shorter derivative fragments (1423 bp, 632 bp and 416 bp, which correspond to -1344 to +75, -552 to +75 and -337 to +75 respectively), were subcloned into pGL2 series luciferase reporter vectors. These constructs were introduced into colorectal cancer cell line SW620 for transient expression of reporter gene and luciferase activities were measured. Results: The genomic structure analysis showed there are 12 exons for SNC6 gene, which spans 32017 bp (nt71529 to nt39513 in Z98048 sequence). All transfected SW620 cells with the above 5\|flanking region\|containing constructs showed luciferase activities. The highest luciferase activities were measured in transfected cells with vectors containing 1894 bp fragments, and the lowest luciferase activities were measured in transfected cells with vectors containing 416 bp fragments. Luciferase activities were higher in transfected cells with vectors containing 632 bp fragments than that in transfected cells with vectors containing 1423 bp fragments. Conclusion: The basic transcription\|promoting element (promoter) for SNC6 expression resides between 0 to -337, and two transcription\|enhancing elements (enhancer) resides between -337 to -552 and -1344 to -1814, whereas one transcription\|inhibiting element (silencer) exists between -552 to -1344.

Polymorphisms and functions of the aldose reductase gene 5' regulatory region in Chinese patients with type 2 diabetes mellitus

OBJECTIVE: To screen the 5' regulatory region of the aldose reductase (AR) gene for genetic variabilities causing changes in protein expression and affecting the promoter function. METHODS: The screenings were carried out by polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP). All SSCP variants were submitted for DNA sequencing and inserted into the plasmid chloromycetin acetyl transferase (CAT) enhancer vector. The constructs were used to transfect Hela cells, and CAT assays were performed to assess promoter activity. Gel mobility shift and footprinting assays were also performed to determine the interaction between the DNA and nuclear proteins. RESULTS: Two polymorphisms, C (-106) T and C (-12) G, were identified in the regulatory region in 123 Chinese control subjects and 145 patients with type 2 diabetes mellitus. The frequencies of genotypes WT/WT, WT/C (-12) G and WT/C (-106) T were not significantly different between the subjects and patients. In the patients with and without retinopathy, frequencies of WT/C (-106) T were 31.5% and 17.5% (P 0.05) respectively. The total frequency of WT/C (-12) G and WT/C (-106) T in patients with retinopathy was 41.8%, significantly higher than that (20.0%) in patients without retinopathy (P

Analysis of hypermutation of the 5' noncoding region in the BCL-6 gene

ObjectiveTo investigate BCL 6 gene mutations in Chinese populations with B cell non Hodgkin's lymphoma Methods Polymerase chain reaction (PCR), denaturing gradient gel electrophoresis (DGGE) and direct DNA sequencing were used to identify mutations in the 5' noncoding region of the BCL 6 gene in a total of 40 cases of diffuse large cell lymphoma (DLCL) and follicular lymphoma (FL) Results Nine cases were found to have base substitutions The incidence of BCL 6 gene mutation and the frequency of single base changes were approximately 25 7% and (0 56-1 10)×10 2 /bp, respectively Conclusions The 5' regulatory region of the BCL 6 gene undergoes frequent somatic hypermutation during lymphomagenesis and the identification of BCL 6 gene hypermutations provides a molecular marker for confirmatory diagnosis of B NHL

Polymorphisms in the 5 ′ regulatory region of my-ostatin gene are associated with early growth traits in Yorkshire pigs

Myostatin is a negative regulator of skeletal muscle mass.The present studycloned the 5' regulatory region of porcine myostatin gene,screened its polymorphisms and analyzedtheir associations with early growth traits in Yorkshire pigs.The results indicated that a fragmentlength polymorphism and a polymorphism concerning two nucleotide changes exist in the 5' regulatoryregion of porcine myostatin gene.At sites 435 and 447,allele A and allele B have the haplotypes ofA-G and G-A,respectively.The allelic frequency of B is 0.475 in Yorkshire pigs.No homozygous BBgenotype was detected in 9 Laiwu Black pigs.Allele B was found to have positive effect on bodyweight on day 21 (BW21) (P【0.01),body weight on day 28 (BW28) (P【0.05),body weight on day 70 (BW70)(P【0.05),average daily gain from birth to 21 d (ADG1) (P【0.01),average daily gain from birth to 28 d(ADG2) (P【0.05) and average daily gain from 21 d to 70 d (ADG3) (P【0.01),respectively.The additiveeffect of allele B on BW21,BW28,BW70,ADG1,ADG2 and ADG3 was 0.596±0.205 kg (P=0.0041),0.498±0.200kg (P=0.0136) 1.409±0.551 kg (P=0.0112),28.39±9.74 g P=0.0041),17.78±7.15 g (P=0.0136) and37.00±16.92 g (P=0.0304),respectively,whereas its effect on average daily gain from 28 d to 70 d(ADG4) was not significant (P】0.1),although BB individuals are superior in average daily gain to AAand AB.