Ileum Gene Expression in Response to Acute Systemic Inflammation in Mice Chronically Fed Ethanol: Beneficial Effects of Elevated Tissue n-3 PUFAs.

Chronic alcohol consumption leads to disturbances in intestinal function which can be exacerbated by inflammation and modulated by different factors, e.g., polyunsaturated fatty acids (PUFAs). The mechanisms underlying these alterations are not well understood. In this study, RNA-seq analysis was performed on ileum tissue from WT and fat-1 transgenic mice (which have elevated endogenous n-3 PUFAs). Mice were chronically fed ethanol (EtOH) and challenged with a single lipopolysaccharide (LPS) dose to induce acute systemic inflammation. Both WT and fat-1 mice exhibited significant ileum transcriptome changes following EtOH + LPS treatment. Compared to WT, fat-1 mice had upregulated expression of genes associated with cell cycle and xenobiotic metabolism, while the expression of pro-inflammatory cytokines and pro-fibrotic genes was decreased. In response to EtOH + LPS, fat-1 mice had an increased expression of genes related to antibacterial B cells (APRIL and IgA), as well as an elevation in markers of pro-restorative macrophages and γδ T cells that was not observed in WT mice. Our study significantly expands the knowledge of regulatory mechanisms underlying intestinal alterations due to EtOH consumption and inflammation and identifies the beneficial transcriptional effects of n-3 PUFAs, which may serve as a viable nutritional intervention for intestinal damage resulting from excessive alcohol consumption.

Fads3 modulates docosahexaenoic acid in liver and brain.

Fatty acid desaturase 3 (FADS3) is the third member of the FADS gene cluster. FADS1 and FADS2 code for enzymes required for highly unsaturated fatty acid (HUFA) biosynthesis, but FADS3 function remains elusive. We generated the first Fads3 knockout (KO) mouse with an aim to characterize its metabolic phenotype and clues to in vivo function. All mice (wild type (WT) and KO) were fed facility rodent chow devoid of HUFA. No differences in overt phenotypes (survival, fertility, growth rate) were observed. Docosahexaenoic acid (DHA, 22:6n-3) levels in the brain of postnatal day 1 (P1) KO mice were lower than the WT (P < 0.05). The ratio of docosapentaenoic acid (DPA, 22:5n-3) to DHA in P1 KO liver was higher than in WT suggesting lower desaturase activity. Concomitantly, 20:4n-6 was lower but its elongation product 22:4n-6 was greater in the liver of P1 KO mice. P1 KO liver Fads1 and Fads2 mRNA levels were significantly downregulated whereas expression levels of elongation of very long chain 2 (Elovl2) and Elovl5 genes were upregulated compared to age-matched WT. No Δ13-desaturation of vaccenic acid was observed in liver or heart in WT mice expressing FADS3 as was reported in vitro. Taken together, the fatty acid compositional results suggest that Fads3 enhances liver-mediated 22:6n-3 synthesis to support brain 22:6n-3 accretion before and during the brain growth spurt.

Free flight odor tracking in Drosophila: Effect of wing chemosensors, sex and pheromonal gene regulation.

The evolution of powered flight in insects had major consequences for global biodiversity and involved the acquisition of adaptive processes allowing individuals to disperse to new ecological niches. Flies use both vision and olfactory input from their antennae to guide their flight; chemosensors on fly wings have been described, but their function remains mysterious. We studied Drosophila flight in a wind tunnel. By genetically manipulating wing chemosensors, we show that these structures play an essential role in flight performance with a sex-specific effect. Pheromonal systems are also involved in Drosophila flight guidance: transgenic expression of the pheromone production and detection gene, desat1, produced low, rapid flight that was absent in control flies. Our study suggests that the sex-specific modulation of free-flight odor tracking depends on gene expression in various fly tissues including wings and pheromonal-related tissues.

[Fatty acid desaturase 1 polymorphism, marine fish oil intake and the risk of oral squamous cell carcinoma: A case-control study].

OBJECTIVE: To evaluate the independent and joint effects of FADS1 polymorphism and fish oil intake on oral squamous cell carcinoma( OSCC). METHODS: A case-control study was conducted with 259 newly diagnosed primary OSCC patients and538 controls frequency-matched by sex and age in Fujian from September 2010 to September 2014. Data on demographics and dietary habits such as marine fish oil intake were collected using a structure questionnaire. FADS1 rs174549 genotype was determined using Taq Man genotyping assays. Unconditional logistic regression was used to the oddsratios( ORs) and their 95% confidence intervals( CI) of FADS1 polymorphism and fish oil intake for OSCC. RESULTS: FADS1 rs174549 AA genotype was associated with decreased risk of OSCC( codominant model: OR = 0. 53, 95% CI 0. 33-0. 85; recessive model: OR = 0. 57, 95% CI 0. 38-0. 87). Compared with those who non-intake marine fish oil, regularly intake of marine fish oil decreased the risk of OSCC( OR = 0. 54, 95%CI: 0. 32-0. 91). Moreover, a multiplicative interaction between FADS1 rs174549 polymorphism and marine fish oil intake for oral cancer( OR_(multiplicative)= 0. 31, 95% CI0. 11-0. 87). CONCLUSION: FADS1 rs174549 polymorphism and marine fish oil intake may be independent protective factors for OSCC with a gene-diet multiplicative interaction.

FADS1 rs174549 Polymorphism May Predict a Favorable Response to Chemoradiotherapy in Oral Cancer Patients.

PURPOSE: The fatty acid desaturase 1 (FADS1) gene variant is a novel susceptibility marker for laryngeal squamous cell carcinoma identified by a recent genome-wide association study, but it is still unclear whether this genetic variant continues to influence oral cancer recurrence or death. The purpose of this study was to evaluate the role of FADS1 rs174549 polymorphism and its interaction with postoperative chemoradiotherapy in the prognosis of oral cancer. PATIENTS AND METHODS: A prospective cohort study involving 304 oral cancer patients with surgical resection was conducted in Fujian, China. Demographic and clinical data (adjuvant therapy types, histologic types, clinical stage, etc.) were extracted from medical records, and follow-up data were obtained by telephone interviews. We collected 5 to 8 mL of venous blood from all patients for DNA extraction, and rs174549 genotypes were determined by TaqMan assays (Life Technologies, Carlsbad, CA). A Cox proportional hazards model and Kaplan-Meier curve were used to assess the association between FADS1 rs174549 polymorphism and progression-free survival (PFS), as well as overall survival, in oral cancer. RESULTS: Carrying the AA genotype was significantly associated with a decreased risk of PFS: The hazard ratio was 0.52 (95% confidence interval, 0.29 to 0.93) for the codominant model and 0.54 (95% confidence interval, 0.31 to 0.94) for the recessive model. Moreover, better PFS was particularly obvious in patients who had received chemoradiotherapy. A positive multiplicative interaction between FADS1 rs174549 polymorphism and chemoradiotherapy was observed for PFS (P = .036). No significant association was found between FADS1 rs174549 polymorphism and overall survival. CONCLUSIONS: Our study suggests, for the first time, that FADS1 rs174549 polymorphism is a potentially independent and favorable factor in predicting oral cancer PFS especially for patients who undergo chemoradiotherapy, and it may serve as a potential target for individualized treatment in the future.

Detection of Acyl-CoA Derivatized with Butylamide for in vitro Fatty Acid Desaturase Assay.

Membrane-bound fatty acid desaturases acting on acyl-CoA contribute to the biosynthesis of unsaturated fatty acids, such as arachidonic acid and docosahexaenoic acid in higher organisms. We propose a simplified method for measuring the desaturase activity that combines the in vitro reaction by desaturase-expressing yeast cell homogenate and the detection of acyl-CoA product as butylamide derivatives by gas chromatography. To set up the in vitro reaction, we traced the in vivo activity of rat liver ∆6 fatty acid desaturase (D6d) expressed in the yeast, Saccharomyces cerevisiae, and determined the time taken for the D6d activity to reach its maximum level. The cell homogenate of yeast expressing the maximum D6d activity was made to react in vitro with linoleoyl-CoA to generate the D6d product, γlinolenoyl-CoA. This product was successfully detected as a peak corresponding to γ-linolenoyl butylamide on gas chromatography. This procedure, with low background expression, using non-labeled acyl-CoA as substrate, will contribute toward developing a simple in vitro desaturase assay. It will also help in elucidating the functions of membrane-bound fatty acid desaturases with various substrate specificities and regioselectivities.

Genetic variants of FADS gene cluster, plasma LC-PUFA levels and the association with cognitive function of under-two-year-old Sasaknese Indonesian children.

BACKGROUND/AIMS: Long-chain polyunsaturated fatty acids (LC-PUFA) are regarded as essential for child cognition. Genetic variation in fatty acid (FA) desaturase enzyme (FADS) has been recognized as an important effect modifier in the relation between LC-PUFA and child cognitive function. This study aimed to identify the distribution of genetic variant (genotype) SNP rs174468 and to assess plasma FA and developmental outcome by the genotype among under-2 year old Sasaknese Indonesian children. METHODS: Data was collected at baseline of a randomized trial (NUPICO, clinicaltrials.gov NCT01504633) in East Lombok district, Indonesia. Breastfed, 12- 17 month old children were recruited and 240 subjects were included in the study. Child cognition was assessed as Bayley Mental Developmental Index (MDI). RESULTS: From 206 subjects whose blood samples can be collected, only two genotypes were found (90.3% GG homozygotes, 9.7% AG heterozygotes), and minor allele AG was significantly associated with higher level of arachidonic acid (20:4 n-6), n-6 LC-PUFA and FADS1 index. MDI score was associated with a FADS2 index (DHA:EPA ratio) but not genotype (Adjusted R-square= 0.043). CONCLUSIONS: FADS2 index was associated with cognitive function. No difference was found between children with GG and AG genotypes who were all breastfed and not low birth weight.

Heart Rate Variability Correlates to Functional Aerobic Impairment in Hemodialysis Patients / Variabilidade RR ao Esforço Correlaciona-se com Déficit Funcional Aeróbico em Pacientes em Hemodiálise

Background: Autonomic dysfunction (AD) is highly prevalent in hemodialysis (HD) patients and has been implicated in their increased risk of cardiovascular mortality. Objective: To correlate heart rate variability (HRV) during exercise treadmill test (ETT) with the values obtained when measuring functional aerobic impairment (FAI) in HD patients and controls. Methods: Cross-sectional study involving HD patients and a control group. Clinical examination, blood sampling, transthoracic echocardiogram, 24-hour Holter, and ETT were performed. A symptom-limited ramp treadmill protocol with active recovery was employed. Heart rate variability was evaluated in time domain at exercise and recovery periods. Results: Forty-one HD patients and 41 controls concluded the study. HD patients had higher FAI and lower HRV than controls (p<0.001 for both). A correlation was found between exercise HRV (SDNN) and FAI in both groups. This association was independent of age, sex, smoking, body mass index, diabetes, and clonidine or beta-blocker use, but not of hemoglobin levels. Conclusion: No association was found between FAI and HRV on 24-hour Holter or at the recovery period of ETT. Of note, exercise HRV was inversely correlated with FAI in HD patients and controls. (Arq Bras Cardiol. 2015; [online]. ahead print, PP.0-0) .

Fundamento: A disfunção autonômica (DA) é altamente prevalente em pacientes em hemodiálise (HD) e tem sido implicada no risco aumentado de mortalidade cardiovascular. Objetivo: Correlacionar a variabilidade RR (VRR) durante o teste ergométrico (TE) com o déficit funcional aeróbico (FAI) em pacientes em HD e em um grupo controle. Métodos: Trata-se de um estudo transversal no qual as variáveis analisadas foram obtidas através de exame clínico, coleta de sangue, ecocardiograma transtorácico, Holter de 24 horas e TE. Foi realizado TE em esteira pelo protocolo de rampa, limitado por sintomas, com recuperação ativa. A VRR foi avaliada no domínio do tempo no exercício e na recuperação separadamente. Resultados: Quarenta e um pacientes em HD e 41 controles concluíram o estudo. Pacientes em HD tinham maior FAI e menor VRR do que os controles (p <0,001 para ambos). Houve correlação entre FAI e VRR no exercício (SDNN) em ambos os grupos. Esta associação foi independente de idade, sexo, tabagismo, índice de massa corporal, diabetes, clonidina, betabloqueador, mas não dos níveis de hemoglobina. Conclusão: A VRR no exercício foi inversamente correlacionada com o FAI em pacientes em HD e controles. Não foram observadas associações do FAI com VRR no Holter ou no período de recuperação do TE. .

Decreased saturated fatty acids, total cholesterol and LDL-C in sdd17 mice.

SDD17, a delta-15 desaturase from the fungus Saprolegnia can convert arachidonic acid to eicosapentanoic acid in yeast, plant embryos, and mammalian cells. Here, we generated transgenic mice that carried two copies of codon-optimized sdd17 cDNA within a non-coding domain of chromosome 6. RT-PCR analysis revealed that the foreign gene was expressed in the transgenic tissues. Gas chromatography showed that the levels of total unsaturated fatty acids in muscle, liver, and spleen tissues were significantly (p<0.05) increased in transgenic mice compared to non-transgenic mice at 3 or 8 weeks of age. In addition, the serum concentrations of total cholesterol and low-density lipoprotein cholesterol in transgenic females, but not in males, were significantly lower than those in sex-matched non-transgenic mice. These results suggest that endogenous sdd17 expression is beneficial for mammalian health and that its effects on fatty acid profiles may differ between sexes.

Handmade cloned transgenic piglets expressing the nematode fat-1 gene.

Production of transgenic animals via somatic cell nuclear transfer (SCNT) has been adapted worldwide, but this application is somewhat limited by its relatively low efficiency. In this study, we used handmade cloning (HMC) established previously to produce transgenic pigs that express the functional nematode fat-1 gene. Codon-optimized mfat-1 was inserted into eukaryotic expression vectors, which were transferred into primary swine donor cells. Reverse transcriptase PCR (RT-PCR), gas chromatography, and chromosome analyses were performed to select donor clones capable of converting n-6 into n-3 fatty acids. Blastocysts derived from the clones that lowered the n-6/n-3 ratio to approximately 1:1 were transferred surgically into the uteri of recipients for transgenic piglets. By HMC, 37% (n=558) of reconstructed embryos developed to the blastocyst stage after 7 days of culture in vitro, with an average cell number of 81±36 (n=14). Three recipients became pregnant after 408 day-6 blastocysts were transferred into four naturally cycling females, and a total of 14 live offspring were produced. The nematode mfat-1 effectively lowered the n-6/n-3 ratio in muscle and major organs of the transgenic pig. Our results will help to establish a reliable procedure and an efficient option in the production of transgenic animals.

Importance of ß,ß-carotene 15,15'-monooxygenase 1 (BCMO1) and ß,ß-carotene 9',10'-dioxygenase 2 (BCDO2) in nutrition and health.

In humans, varying amounts of absorbed ß-carotene are oxidatively cleaved by the enzyme ß,ß-carotene 15,15'-monooxygenase 1 (BCMO1) into two molecules of all-trans-retinal. The other carotenoid cleavage enzyme ß,ß-carotene 9',10'-dioxygenase (BCDO2) cleaves ß-carotene at the 9',10' double bond forming ß-apo-10'-carotenal and ß-ionone. Although the contribution of BCDO2 to vitamin A formation has long been debated, BCMO1 is currently considered the key enzyme for retinoid metabolism. Furthermore, BCMO1 has limited enzyme activity towards carotenoids other than provitamin A carotenoids, whereas BCDO2 exhibits a broader specificity. Both enzymes are located at different sites within the cell, with BCMO1 being a cytosolic protein and BCDO2 being located in the mitochondria. Expression of BCMO1 in tissues other than the intestine has recently revealed its function for tissue-specific retinoid metabolism with importance in embryogenesis and lipid metabolism. On the other hand, biological activity of BCDO2 metabolites has been shown to be important in protecting against carotenoid-induced mitochondrial dysfunction. Single-nucleotide polymorphisms (SNPs) such as R267S and A379V in BCMO1 can partly explain inter-individual variations observed in carotenoid metabolism. Advancing knowledge about the physiological role of these two enzymes will contribute to understanding the importance of carotenoids in health and disease.

Suppressed liver tumorigenesis in fat-1 mice with elevated omega-3 fatty acids is associated with increased omega-3 derived lipid mediators and reduced TNF-α.

Liver tumors, particularly hepatocellular carcinoma (HCC), are a major cause of morbidity and mortality worldwide. The development of HCC is mostly associated with chronic inflammatory liver disease of various etiologies. Previous studies have shown that omega-3 (n-3) polyunsaturated fatty acids (PUFAs) dampen inflammation in the liver and decrease formation of tumor necrosis factor (TNF)-α. In this study, we used the fat-1 transgenic mouse model, which endogenously forms n-3 PUFA from n-6 PUFA to determine the effect of an increased n-3 PUFA tissue status on tumor formation in the diethylnitrosamine (DEN)-induced liver tumor model. Our results showed a decrease in tumor formation, in terms of size and number, in fat-1 mice compared with wild-type littermates. Plasma TNF-α levels and liver cyclooxygenase-2 expression were markedly lower in fat-1 mice. Furthermore, there was a decreased fibrotic activity in the livers of fat-1 mice. Lipidomics analyses of lipid mediators revealed significantly increased levels of the n-3 PUFA-derived 18-hydroxyeicosapentaenoic acid (18-HEPE) and 17-hydroxydocosahexaenoic acid (17-HDHA) in the livers of fat-1 animals treated with DEN. In vitro experiments showed that 18-HEPE and 17-HDHA could effectively suppress lipopolysacharide-triggered TNF-α formation in a murine macrophage cell line. The results of this study provide evidence that an increased tissue status of n-3 PUFA suppresses liver tumorigenesis, probably through inhibiting liver inflammation. The findings also point to a potential anticancer role for the n-3 PUFA-derived lipid mediators 18-HEPE and 17-HDHA, which can downregulate the important proinflammatory and proproliferative factor TNF-α.

Cognitive function in adolescence: testing for interactions between breast-feeding and FADS2 polymorphisms.

OBJECTIVES: Breast-fed C-allele carriers of the rs174575 single nucleotide polymorphism in the fatty acyl desaturase 2 (FADS2) gene have been reported to show a 6.4 to 7 IQ point advantage over formula-fed C-allele carriers, with no effect of breast-feeding in GG carriers. An Australian sample was examined to determine if an interaction between breast-feeding and the rs174575 single nucleotide polymorphism had any effect on IQ. METHOD: This hypothesis was tested in more than 700 families of adolescent twins assessed for IQ and breast-feeding, birth weight, and FADS2 polymorphisms, and parental socioeconomic status and education, and maternal FADS2 status. RESULTS: No significant evidence for a moderating effect on IQ of rs174575 C-carrier status and breast-feeding was found, and there no effects of maternal FADS2 status on offspring IQ. In addition, no main effects of any FADS2 polymorphisms on IQ were found when the genotype was kept as two-homozygote and one-heterozygote categories and indeed no evidence for effects of breast-feeding on IQ scores after controlling for parental socioeconomic status and education. The investigation was extended to two additional FADS2 polymorphisms (rs1535 and rs174583), but again, although these polymorphisms code alleles affecting fatty acid metabolism, no main or interaction effects were found on IQ. CONCLUSION: These results support the view that apparent effects of breast-feeding on IQ reflect differential likelihood of breast-feeding as a function of parental education and did not support the predicted interaction effect of FADS2 and breast-feeding on IQ.

[Isolation of OsFAD2, OsFAD6 and FAD family members response to abiotic stresses in Oryza sativa L.].

Unsaturated fatty acids are synthesized by fatty acid desaturase in plant, which play an important role in plant development and defense to abiotic stresses. The key enzymes for the conversion of oleic into linoleic acid were isolated from rice (Oryza sativa L.) and were designated OsFAD2 and OsFAD6, respectively. The open reading frame (ORF) of OsFAD2 was 1 167 bp in length, which encoded a 388 amino acids sequence with the isoelectric point of 8.17 and molecular mass of 52.24 kDa, the OsFAD2 protein contained a C-terminal ER retrieval motif. The ORF of OsFAD6 was 1 365 bp in length and the predicted OsFAD6 protein has 454 amino acids with an estimated molecular mass of 44.35 kDa and an isoelectric point of 9.24, the predicted OsFAD6 protein possessed a putative N-terminal plastidial signal peptide. Both of them had three his-boxes, which were peculiar to membrane integrated fatty acid desaturase by Clustal X analysis. RT-PCR analysis showed that both genes were expressed in all tissues rice seedlings, with the maximum transcript accumulation in leaves. Among FAD family members of Oryza sativa L., the mRNA abundance of OsFAD2 and OsFAD6 in leaves did not change under cold stress; however, the mRNA abundance of OsFAD7 and OsFAD8 increased in the same condition. It was also found that the expression of FAD family members had diurnal rhythm phenomena. Based on the results of this study, it suggested that diurnal rhythm expression of OsFAD6 and OsFAD7 was related to the change of NADPH abundance.

Elucidation of the sex-pheromone biosynthesis producing 5,7-dodecadienes in Dendrolimus punctatus (Lepidoptera: Lasiocampidae) reveals Delta 11- and Delta 9-desaturases with unusual catalytic properties.

Sex pheromones produced by female moths of the Lasiocampidae family include conjugated 5,7-dodecadiene components with various oxygenated terminal groups. Here we describe the molecular cloning, heterologous expression and functional characterization of desaturases associated with the biosynthesis of these unusual chemicals. By homology-based PCR screening we characterized five cDNAs from the female moth pheromone gland that were related to other moth desaturases, and investigated their role in the production of the (Z)-5-dodecenol and (Z5,E7)-dodecadienol, major pheromone constituents of the pine caterpillar moth, Dendrolimus punctatus. Functional expression of two desaturase cDNAs belonging to the Delta 11-subfamily, Dpu-Delta 11(1)-APSQ and Dpu-Delta 11(2)-LPAE, showed that they catalysed the formation of unsaturated fatty acyls (UFAs) that can be chain-shortened by beta-oxidation and subsequently reduced to the alcohol components. A first (Z)-11-desaturation step is performed by Dpu-Delta 11(2)-LPAE on stearic acid that leads to (Z)-11-octadecenoic acyl, which is subsequently chain shortened to the (Z)-5-dodecenoic acyl precursor. The Dpu-Delta 11(1)-APSQ desaturase had the unusual property of producing Delta 8 mono-UFA of various chain lengths, but not when transformed yeast were grown in presence of (Z)-9-hexadecenoic acyl, in which case the biosynthetic intermediate (Z9,E11)-hexadecadienoic UFA was produced. In addition to a typical Z9 activity, a third transcript, Dpu-Delta 9-KPSE produced E9 mono-UFAs of various chain lengths. When provided with the (Z)-7-tetradecenoic acyl, it formed the (Z7,E9)-tetradecadienoic UFA, another biosynthetic intermediate that can be chain-shortened to (Z5,E7)-dodecadienoic acyl. Both Dpu-Delta 11(1)-APSQ and Dpu-Delta 9-KPSE thus exhibited desaturase activities consistent with the biosynthesis of the dienoic precursor. The combined action of three desaturases in generating a dienoic sex-pheromone component emphasizes the diversity and complexity of chemical reactions that can be catalysed by pheromone biosynthetic fatty-acyl-CoA desaturases in moths.

The key roles of elongases and desaturases in mammalian fatty acid metabolism: Insights from transgenic mice.

In mammalian cells, elongases and desaturases play critical roles in regulating the length and degree of unsaturation of fatty acids and thereby their functions and metabolic fates. In the past decade, a great deal has been learnt about these enzymes and the first part of this review summarizes our current knowledge concerning these enzymes. More recently, several transgenic mouse models lacking either an elongase (Elovl3(-/-), Elovl4(-/-), Elovl5(-/-), Elovl6(-/-)) or a desaturase (Scd-1(-/-), Scd-2(-/-), Fads2(-/-)) have been developed and the second part of this review focuses on the insights gained from studies with these mice, as well as from investigations on cell cultures.

Fatty acid desaturase-6 (Fad6) is required for salt tolerance in Arabidopsis thaliana.

Fatty acid desaturases play important role in plant responses to abiotic stresses including cold, high temperature, drought, and osmotic stress. In this work, we provide the evidence that Fad6, a chloroplast desaturase, is required for salt tolerance during the early seedling development of Arabidopsis. Expression of Fad6 was responsive to salt and osmotic stress. Compared with the wild-type plants, the fad6 mutant showed reduced tolerance to salt stress, and accumulated more Na(+) and less K(+) under high NaCl stress condition. Furthermore, cellular oxidative damage was more severe in fad6 when treated with high concentrations of NaCl, as indicated by increased electrolyte leakage rate and malondialdehyde production, as well as by decreased activities of anti-oxidative enzymes. All these results suggest that Fad6 is required for salt resistance in Arabidopsis.

FATTY ACID DESATURASE4 of Arabidopsis encodes a protein distinct from characterized fatty acid desaturases.

Polar membrane glycerolipids occur in a mixture of molecular species defined by a polar head group and characteristic acyl groups esterified to a glycerol backbone. A molecular species of phosphatidylglycerol specific to chloroplasts of plants carries a Delta(3-trans) hexadecenoic acid in the sn-2 position of its core glyceryl moiety. The fad4-1 mutant of Arabidopsis thaliana missing this particular phosphatidylglycerol molecular species lacks the necessary fatty acid desaturase, or a component thereof. The overwhelming majority of acyl groups associated with membrane lipids in plants contains double bonds with a cis configuration. However, FAD4 is unusual because it is involved in the formation of a trans double bond introduced close to the carboxyl group of palmitic acid, which is specifically esterified to the sn-2 glyceryl carbon of phosphatidylglycerol. As a first step towards the analysis of this unusual desaturase reaction, the FAD4 gene was identified by mapping of the FAD4 locus and coexpression analysis with known lipid genes. FAD4 encodes a predicted integral membrane protein that appears to be unrelated to classic membrane bound fatty acid desaturases based on overall sequence conservation. However, the FAD4 protein contains two histidine motifs resembling those of metalloproteins such as fatty acid desaturases. FAD4 is targeted to the plastid. Overexpression of the cDNA in transgenic Arabidopsis led to increased accumulation of the Delta(3-trans) hexadecanoyl group in phosphatidylglycerol relative to wild type. Taken together these results are consistent with the hypothesis that FAD4 is the founding member of a novel class of fatty acid desaturases.

desat1 and the evolution of pheromonal communication in Drosophila.

The evolution of communication is a fundamental biological problem. The genetic control of the signal and its reception must be tightly coadapted, especially in interindividual sexual communication. However, there is very little experimental evidence for tight genetic linkage connecting the emission of a signal and its reception. In Drosophila melanogaster, desat1 is the first known gene that simultaneously affects the emission and the perception of sex pheromones. Our experiments show that both aspects of pheromonal communication (the emission and the perception of sex pheromones) depend on distinct genetic control and may result from tissue-specific expression of different transcripts, all coding for the same desaturase. Therefore, and given the high conservation of its coding region, the pleiotropic activity of the desat1 gene may have arisen from an evolutionary process that shaped its regulatory regions.