Farnesoic Acid Research Articles

Isolation and expression analysis of multiple isoforms of putative farnesoic acid O-methyltransferase in several crustacean species

Farnesoic acid O-methyltransferase (FaMeT) is the enzyme responsible for the conversion of farnesoic acid (FA) to methyl farnesoate (MF) in the final step of MF synthesis. Multiple isoforms of putative FaMeT were isolated from six crustacean species belonging to the families Portunidae, Penaeidae, Scyllaridae and Parastacidae. The portunid crabs Portunus pelagicus and Scylla serrata code for three forms: short, intermediate and long. Two isoforms (short and long) were isolated from the penaeid prawns Penaeus monodon and Fenneropenaeus merguiensis. Two isoforms were also identified in the scyllarid Thenus orientalis and parastacid Cherax quadricarinatus. Putative FaMeT sequences were also amplified from the genomic DNA of P. pelagicus and compared to the putative FaMeT transcripts expressed. Each putative FaMeT cDNA isoform was represented in the genomic DNA, indicative of a multi-gene family. Various tissues from P. pelagicus were individually screened for putative FaMeT expression using PCR and fragment analysis. Each tissue type expressed all three isoforms of putative FaMeT irrespective of sex or moult stage. Protein domain analysis revealed the presence of a deduced casein kinase II phosphorylation site present only in the long isoform of putative FaMeT.

A Preliminary Examination of the Leaf Oils of the Genus Xanthostemon (Myrtaceae) in Australia

The leaf oils of the Australian species of Xanthostemon have been examined by a combination of GC and GC/MS. Xanthostemon arenarius produced an oil dominated by sesquiterpenes, with the principal components being β-selinene (12–17%), α-selinene (6–10%), 7-epi-α-selinene (7–11%), α-humulene (0.3–10%, the majority > 6%) and spathulenol (3–19%). Xanthostemon chrysanthus produced a leaf oil in which the principal component was the β-triketone leptospermone (65–84%). The leaf oil of X. crenulatus was dominated by the sesquiterpene ketone, cyclocolorenone (65–80%) and the aromatic ketone apodophyllone (6–17%). The leaf oil of X. eucalyptoides was dominated by the aromatic ketones baeckeol methyl ether (34–41%), baeckeol (15–29%), isobaeckeol (5–8%) and apodophyllone (7–9%). The leaf oil of X. formosus was, once again, sesquiterpenoid in nature. The principal components were β-caryophyllene (10–24%), β-bisabolene (9–16%) and sesquiphellandrene (9–20%). Xanthostemon graniticus was unusual within the genus in that it produced a monoterpenic oil, the principal component being α-pinene (69.5%). Xanthostemon oppositifolius gave an oil which was dominated by β-triketones. The principal components were xanthostemone (1625%) and a compound considered a one carbon homologue, which is as yet unidentified (24–35%). Xanthostemon paradoxus produced a leaf oil that was sesquiterpenoid in nature. The principal components were β-caryophyllene (14%), spathulenol (14.9%) and globulol (8%). Xanthostemon psidioides was another species whose oil was dominated by β-triketones, the principal component being xanthostemone (73.1%). Xanthostemon umbrosus, the species with the widest distribution in this investigation, produced a variable oil. The various oils were dominated by the sesquiterpene ketone, cyclocolorenone (77–83%), or methyl farnesoate (3257%) and farnesoic acid (9–26%) or α-santalene (6–7%), isobaeckeol (30–40%) and an unknown, presumed aromatic, compound mw 252 (3–23%). The leaf oil from X. verticillatus was unusual amongst the other Australian species of Xanthostemon in that it contained 1,3-dimethoxy-5-isopropylbenzene as its major component (96–97%). Xanthostemon whitei gave a sesquiterpenic oil which was similar to that produced by X. arenarius. Xanthostemon youngii also gave a sesquiterpenic oil, the principal components being α-copaene (3–13%), β-caryophyllene (11–13%), aromadendrene (3–12%), and γ-cadinene (4–18%). Xanthostemon sp. (Bolt Head JRC +8805) gave a terpenoid oil in which the major components were the hydrocarbons, γ-cadinene (18%) and calamenene (29.3%). Oil yields over the range of species were 0.1–0.6%, w/w, based on fresh leaves.

Characterization of vitellogenin in the shrimp Metapenaeus ensis: Expression studies and hormonal regulation of MeVg1 transcription in vitro

During gonad maturation, female shrimp accumulate the major egg yolk protein vitellin (Vn) in premolt stage, and the process of molting and reproduction is synchronized. Using a polyclonal anti-Vn antibody, immunopositive signals could be detected in the ovary and among the proteins secreted by the hepatopancreas by Western blot. In the ovary, Vn immunoreactivity was located in the posterior lobe. Hepatopancreas proteins with sizes identical to ovary vitellogenin (Vg) subunits (i.e., 78 and 157 kDa) were immunoreactive to the Vn antibody and these proteins included amino acid sequences identical to parts of the MeVg1 precursor. A major 7.8 kb MeVg1 transcript, was detected in the ovary. In the hepatopancreas, the transcripts were primarily small (<2.3 kb) and while the 7.8 kb transcript which constitutes <50% of the total Vg mRNA. MeVg1 transcript could be detected in the hepatopancreas of juvenile females with a maximum level during late intermolt and early premolt. To study the effect of different hormones on expression of MeVg1, explant cultures of hepatopancreas and ovary were developed. Although several hormones (20-hydroxyecdysone, estradiol (ES), farnesoic acid (FA), juvenile hormone (JH) III, methyl farnesoate, and progesterone (PG)) apparently stimulated MeVg1 gene expression, only FA consistently stimulated MeVg1 expression by the hepatopancreas explants, while both FA and 20-hydroxyecdysone were stimulated ovarian explants. In summary, (i) Vg transcripts can be detected in both reproductive and nonreproductive females; (ii) the presence of large quantities of smaller Vg transcripts and the absence of a large Vg precursor from the hepatopancreas suggests that smaller MeVg1 transcripts provide an important contribution to Vg synthesis in shrimp. Our results suggest that there is differential processing of the MeVg1 precursor in the ovary and hepatopancreas of shrimp.

Equal contribution of hepatopancreas and ovary to the production of vitellogenin (PmVg1) transcripts in the tiger shrimp, Penaeus monodon

Although the gene fragment and partial cDNA for the vitellogenin (Vg) of Penaeus monodon have been reported for several years, the complete gene sequence and full-length cDNA of this Vg has not been reported. Here we report the gene organization and cloning of the full-length cDNA of P. monodon Vg. Similar to the MeVg1 of M. ensis, the Vg gene of P. monodon (PmVg1) is confirmed to consist of 14 introns and 15 exons. Additionally, genomic DNAs that show high sequence identity to PmVg1 were isolated from a single shrimp. The result confirmed the existence of multiple Vg genes in P. monodon. PmVg cDNA is 7.8 kb in size and the deduced precursor is most similar to the Vg of Penaeus merguenesis (86% identity). Contrary to the previous report, similar levels of PmVg1 transcripts can be detected from the hepatopancreas and ovary suggesting that the ovary also plays a major role in the contribution of PmVg1 transcript during vitellogenesis. In shrimp at early vitellogenesis (i.e., GSI < 3%), the expression of PmVg1 in the ovary and hepatopancreas is low; the expression reached the maximum level in shrimp with GSI 4–8% and decreased in shrimp with GSI > 9%. Farnesoic acid and 20-hydroecdysone can cause a significant stimulation of PmVg1 expression in an in vitro hepatopancreas explant culture. In conclusion, vitellogenesis in P. monodon is most likely the result of the expression of multiple vitellogenin genes and the hepatopancreas and ovary contribute equally to the production of PmVg1 transcripts.

Expressed sequence tags from eyestalk of kuruma prawn, Marsupenaeus japonicus

We analyzed the expressed sequence tags (ESTs) obtained from a cDNA library of the eyestalk of the kuruma prawn, Marsupenaeus japonicus, to examine gene expression profile with special focus on female reproduction. The assembly of 1988 ESTs created 136 contigs from 738 ESTs; however 1250 ESTs remained singletons. Significant similarities (blast score ≥ 50 bits) to the DNA sequences in the databank were found for only 16.7% of the 1386 sequences (136 contigs plus 1250 singletons), suggesting that the eyestalk library contains many unknown genes. Ribosomal RNA and mitochondrial respiration enzymes with significant similarities were found abundantly in the ESTs, whereas genes related to maturation or endocrine systems were scarce. Three ESTs were assumed to encode novel eyestalk hormones with marked similarities to pigment-dispersing hormone, molt-inhibiting hormone and crustacean hyperglycemic hormone. Sequences encoding a product highly homologous to farnesoic acid O-methyltransferase, an enzyme that produces methyl farnesoate, were also found.

An Arabidopsis thaliana methyltransferase capable of methylating farnesoic acid

We previously reported the identification of a new family of plant methyltransferases (MTs), named the SABATH family, that use S-adenosyl- l-methionine (SAM) to methylate a carboxyl moiety or a nitrogen-containing functional group on a diverse array of plant compounds. The Arabidopsis genome alone contains 24 distinct SABATH genes. To identify the catalytic specificities of members of this protein family in Arabidopsis, we screened recombinantly expressed and purified enzymes with a large number of potential substrates. Here,we report that the Arabidopsis thaliana gene At3g44860 encodes a protein with high catalytic specificity towards farnesoic acid (FA). Under steady-state conditions, this farnesoic acid carboxyl methyltransferase (FAMT) exhibits K M values of 41 and 71 μM for FA and SAM, respectively. A three-dimensional model of FAMT constructed based upon similarity to the experimentally determined structure of Clarkia breweri salicylic acid methyltransferase (SAMT) suggests a reasonable model for FA recognition in the FAMT active site. In planta, the mRNA levels of At3g44860 increase in response to the exogenous addition of several compounds previously shown to induce plant defense responses at the transcriptional level. Although methyl farnesoate (MeFA) has not yet been detected in Arabidopsis, the presence of a FA-specific carboxyl methyltransferase in Arabidopsis capable of producing MeFA, an insect juvenile hormone made by some plants as a presumed defense against insect herbivory, suggests that MeFA or chemically similar compounds are likely to serve as new specialized metabolites in Arabidopsis.

Vitellogenesis in the Red Crab, Charybdis feriatus: Contributions from Small Vitellogenin Transcripts (CfVg) and Farnesoic Acid Stimulation of CfVg Expression

During reproductive maturation of the female red crab, Charybdis feriatus, the oocytes rapidly accumulate 110- and 78-kDa major polypeptides. Although the hepatopancreas expresses a high level of vitellogenin (CfVg) mRNA, tissue proteins and secreted proteins of the hepatopancreas consist of only small polypeptides. In addition to the 8.0-kb transcripts, many smaller mRNAs specific to the CfVg gene can be detected. These results suggest that the hepatopancreas also produces smaller CfVg transcripts for small CfVg subunits. Using an RT-PCR cloning approach, a population of the small cDNA clones were isolated. Determining the DNA sequence of these clones revealed that these transcripts were most likely the result of alternative splicing and/or alternative expression of the CfVg gene. In vitro treatment of the hepatopancreas fragments with low levels of farnesoic acid stimulated the expression of CfVg.

Regulation of methyl farnesoate production by mandibular organs in the crayfish, Procambarus clarkii: A possible role for allatostatins

Decapod crustaceans do not appear to produce juvenile hormone, but rather its immediate precursor, methyl farnesoate (MF). Both MF and its immediate precursor, farnesoic acid (FA) are produced by the mandibular organs (MO) in crustaceans. The MO are homologous to the insect corpora allata (CA), the site of juvenile hormone biosynthesis. However, the FGLamide allatostatin (ASTs) peptides, of which there are about 60 distinct forms reported from crustaceans, have previously been found to have no effect on MO activity in crustaceans. We have identified by immunocytochemistry the presence of FGLamide-like AST immunoreactivity in neurosecretory cells throughout the CNS as well as in neurohaemal structures such as the sinus gland and pericardial organs. The ASTs are likely delivered to the MO hormonally and/or by local neurohaemal release. Using MO from adult males, we have found wide variability between animals in the in vitro rates of MF and FA biosynthesis. Treatment with Dippu-ASTs has a statistically significant stimulatory effect on MF synthesis, but only in MO that are initially producing MF at lower rates. No effect on FA production was observed, suggesting that the FGLamide ASTs exert their effect on the o-methyl transferase, the enzyme responsible for the conversion of FA to MF.

Vitellogenesis in the red crab Charybdis feriatus: Hepatopancreas‐specific expression and farnesoic acid stimulation of vitellogenin gene expression

Vitellogenesis in the mature female crab Charybdis feriatus occurs all year round during which active synthesis of the vitellogenin (Vg) precursor occurs. Several polypeptides from the ovaries were shown to be immuno-reactive to the shrimp vitellin (Vn) antibody. N-terminal amino acid sequence determination revealed that several ovarian polypeptides and one polypeptide secreted by the hepatopancreas were identical to part of the C. feriatus Vg (CfVg) precursor. The full-length cDNA sequence encoding a protein with high amino acid sequence similarity to the Vg of the shrimp Metapenaeus ensis was cloned. In common with the shrimp M. ensis MeVg2, the crab vitellogenin gene is expressed only in the hepatopancreas. The expression level of CfVg is undetectable in the non-reproductive females, increases to maximum at the middle stages of vitellogenesis and drops to a lower level in late vitellogenesis. Expression of CfVg also extended to females that are undergoing brooding of developing larvae. Although the 8 kb transcript for the full-length cDNA was detected, smaller transcripts specific to CfVg mRNA were also detected, suggesting the occurrence of alternative splicing/expression of the CgVg gene to produce the smaller transcripts. Using a short term in vitro hepatopancreas explant culture assay, we have demonstrated that low concentrations of farnesoic acid (FA) stimulate CfVg gene expression in the hepatopancreas. Although both methyl farnesoate (MF) and juvenile hormone III also caused up-regulation of the CfVg gene, their effects are only significant at much higher concentrations.

Purification and characterization of a mandibular organ protein from the American lobster, Homarus americanus: a putative farnesoic acid O-methyltransferase

Methyl farnesoate (MF) appears to have important roles in the development, morphogenesis, and reproduction of crustaceans. To better understand the regulation of MF synthesis, we studied farnesoic acid O-methyltransferase (FAOMeT, the final enzyme in the MF biosynthetic pathway) in the American lobster ( Homarus americanus). FAOMeT purified from mandibular organ (MO) homogenates had a MW of approximately 38,000. The sequences of trypsin fragments of purified FAOMeT were used to design PCR primers to amplify a cDNA fragment, which was used to isolate a full-length cDNA containing a single open reading frame (ORF) of 828 bp encoding a protein of 276 amino acids. The deduced amino acid sequence of this putative FAOMeT protein contained two copies of a conserved ~135 amino acid domain we term the CF (CPAMD8/FAOMeT) domain; single copies of this domain also occur in the human CPAMD8 protein (a member of the alpha-2 macroglobulin family) and an uncharacterized Drosophila protein. The recombinant protein had no FAOMeT activity. However, its addition to MO homogenates from eyestalk ablated (ESA) lobsters increased enzyme activity by up to 75%, suggesting that FAOMeT may require an additional factor or modification (e.g., phosphorylation) for its activation. The mRNA for the putative FAOMeT was primarily found in the proximal region of the MO, the predominant site of MF synthesis. FAOMeT transcripts were found in muscle tissue from ESA animals, but not in green gland, hepatopancreas, or in muscle tissue from intact animals. FAOMeT mRNA was also detected in embryos and larval stages. This is the first comprehensive report of this protein in the lobster, and is an important step in elucidating the functions of MF in these animals.

Natural occurrence of cancer-preventive geranylgeranoic acid in medicinal herbs

Geranylgeranoic acid (GGA; all-trans 3,7,11,15-tetramethyl-2,6,10,14-hexadecatetraenoic acid) has been shown to induce apoptosis in a human hepatoma-derived cell line, HuH-7. We aimed not only to confirm the apoptogenic properties of GGA and its derivatives, but also to search for natural GGA in medicinal herbs. GGA induced apoptosis in human hepatoma-derived cell lines, HuH-7, PLC/PRF-5, and mouse transformed hepatocyte-derived cell line, MLE-10, in a dose- and time-dependent manner, but failed to induce cell death in human hepatoblastoma-derived HepG-2 and mouse primary hepatocytes in the same condition. Besides GGA, 4,5-didehydro GGA, 14,15-dihydro GGA, and 2,3-dihydro GGA were also active to induce cell death in HuH-7 cells, while 4,5-didehydro-10,11, 14,15-tetrahydro GGA, 4,5,8,9-tetrahydro GGA, farnesoic acid, and geranylgeraniol were inert. By using liquid chromatography/mass spectrometry, we found natural GGA as a negative ion of m/z 303.4 in a Chinese herb, Schisandra chinensis, and Schisandra GGA was identified by derivatization with both mild methylation and catalytic hydrogenation. Some other GGAs hydrogenated in the different degrees, including phytanic acid (perhydro GGA), were also found in S. chinensis. GGA and phytanic acid were detected in 24 out of 25 herbs tested. The present study is the first report of natural GGA in medicinal herbs.

A bacterial cell–cell communication signal with cross‐kingdom structural analogues

Extracellular signals are the key components of microbial cell-cell communication systems. This report identified a diffusible signal factor (DSF), which regulates virulence in Xanthomonas campestris pv. campestris, as cis-11-methyl-2-dodecenoic acid, an alpha,beta unsaturated fatty acid. Analysis of DSF derivatives established the double bond at the alpha,beta positions as the most important structural feature for DSF biological activity. A range of bacterial pathogens, including several Mycobacterium species, also displayed DSF-like activity. Furthermore, DSF is structurally and functionally related to farnesoic acid (FA), which regulates morphological transition and virulence by Candida albicans, a fungal pathogen. Similar to FA, which is also an alpha,beta unsaturated fatty acid, DSF inhibits the dimorphic transition of C. albicans at a physiologically relevant concentration. We conclude that alpha,beta unsaturated fatty acids represent a new class of extracellular signals for bacterial and fungal cell-cell communications. As prokaryote-eukaryote interactions are ubiquitous, such cross-kingdom conservation in cell-cell communication systems might have significant ecological and economic importance.

Juvenile hormone acid methyltransferase: a key regulatory enzyme for insect metamorphosis.

Juvenile hormone (JH) acid methyltransferase (JHAMT) is an enzyme that converts JH acids or inactive precursors of JHs to active JHs at the final step of JH biosynthesis pathway in insects. By fluorescent mRNA differential display, we have cloned a cDNA encoding JHAMT from the corpora allata (CA) of the silkworm, Bombyx mori (BmJHAMT). The BmJHAMT cDNA encodes an ORF of 278 aa with a calculated molecular mass of 32,544 Da. The predicted amino acid sequence contains a conserved S-adenosyl-l-methionine (SAM) binding motif found in the family of SAM-dependent methyltransferases. Purified N-terminal 6xHis-tagged recombinant BmJHAMT protein expressed in Escherichia coli catalyzed conversion of farnesoic acid and JH acids I, II, and III to their cognate methyl esters in the presence of SAM, confirming that this cDNA encodes a functional JHAMT. Putative orthologs, DmJHAMT and AgJHAMT, were identified from the genome sequence of the fruit fly Drosophila melanogaster, and a malaria vector, Anopheles gambiae, respectively. Northern blot and quantitative RT-PCR analyses revealed that the BmJHAMT gene was expressed specifically in the CA throughout the third and fourth instar. At the beginning of the last (fifth) instar, the expression level of BmJHAMT declined rapidly and became undetectable by day 4 and remained so until pupation. Correlation of the BmJHAMT gene expression and the JH biosynthetic activity in the CA suggests that the transcriptional suppression of the BmJHAMT gene is crucial for the termination of JH biosynthesis in the CA, which is a prerequisite for the initiation of metamorphosis.

Comparative immunohistochemistry and cellular distribution of farnesoic acid O-methyltransferase in the shrimp and the crayfish

Farnesoic acid O-methyltransferase (FAMeT) catalyzes the conversion of farnesoic acid (FA) to methylfarnesoate (MF) by the mandibular organ (MO) of crustaceans. Here we report the cellular localization of FAMeT and radiochemical assay of endogenous FAMeT activity in shrimp ( Metapenaeus ensis) and crayfish ( Procambarus clarkii) tissues. As in the eyestalk (ES), FAMeT is concentrated in specific neurosecretory cells of the ventral nerve cord (VNC) whereas only weak FAMeT immunoreactivity was observed in the MO. FAMeT was also detected in the ventral nerve cord, heart (HET), eyestalk, and muscle of the juvenile shrimp. Although the VNC shows the greatest FAMeT immunoreactivity, the heart extract exhibited the highest FAMeT enzymatic activity. These results suggest that FAMeT in the VNC may be inactive or inactivated at the stages of development tested. Contrary to the previous reports in other crustaceans, MO extract in shrimp shows only low FAMeT activity. The eyestalk, epidermis, ovary and testis show appreciable FAMeT activity. The presence of FAMeT in neurosecretory cells of VNC and eyestalk of shrimp and crayfish implies a possible interaction of FAMeT with the eyestalk CHH-family of neuropeptides. The widespread activity of FAMeT suggests that it has a wide spectrum of action in many tissues that contribute to the function and regulation of MF synthesis in shrimp and crayfish.

1,5-Disubstituted imidazoles inhibit juvenile hormone biosynthesis by the corpora allata of the mosquito Aedesaegypti

We investigated the effect of fifteen 1,5-disubstituted imidazoles (1,5-dis) on juvenile hormone III (JH III) and methyl farnesoate (MF) biosynthesis by the corpora allata (CA) of the mosquito Aedes aegypti in vitro. Four compounds (TH-35, TH-83, TH-62 and TH-28) significantly decreased JH biosynthesis in the CA dissected from 3-day old sugar-fed females. The decrease of JH synthesis was not always associated with increased MF. TH-30 and TH-83 increased MF levels, while TH-85 and TH-61 significantly decreased MF levels. Five compounds (TH-26, TH-60, TH-83, TH-35 and TH-30) significantly inhibited JH biosynthesis in the CA dissected from females 15 h after a blood meal. Four 1,5-dis (TH-30, TH-26, TH-28 and TH-66) caused MF increases in CA from blood-fed females. 1,5-Disubstituted imidazoles had higher inhibitory activity on JH synthesis when substituted at position 5 by a 3-benzyloxyphenyl group and at position 1 by a benzyl group (such as TH-35). Inhibition of JH and MF biosynthesis by TH-35 was age-dependent and influenced by nutritional status; inhibition differed when evaluated in the CA dissected from sugar-fed females at different days after emergence and in the CA dissected from females at different hours after a blood meal. Inhibition was always higher when the CA was more active. The addition of TH-35 significantly reduced the stimulatory effect of Aedes-allatotropin and farnesoic acid on JH synthesis. This is the first report of an inhibitory effect of 1,5-disubstituted imidazoles on JH synthesis in Diptera.

3-Hydroxy-3-methylglutaryl-coenzyme A reductase in the lobster mandibular organ: regulation by the eyestalk

The mandibular organ (MO) of the lobster, Homarus americanus, produces the isoprenoid methyl farnesoate (MF), a compound related to insect juvenile hormone (JH). To better understand the synthesis and regulation of MF, we studied 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase (HMGR), the rate-limiting enzyme in isoprenoid biosynthesis. Lobster HMGR had a K m of 11.4 μM for HMG-CoA, a K m of 14.8 μM for NADPH, and was at least 2000-fold more selective for this cofactor than for NADH. Lovastatin and mevalonic acid inhibited HMGR, with K I values of 1.3 nM and 25.3 μM, respectively, whereas MF, farnesoic acid, cholesterol, 20-hydroxyecdysone, and progesterone had no effect. Approximately 75% of the HMGR activity in lobster MO was soluble. Similar levels of HMGR activity were observed in all regions of the MO. Eyestalk removal increased MF synthesis and the activity of farnesoic acid O-methyltransferase (FAOMeT, the final step in MF synthesis) in the MO by 10.7- and 5.7-fold, respectively, and caused a 3.1-fold increase of HMGR activity. Injection of the eyestalk ablated lobsters with an extract of two sinus glands (SG), a neuroendocrine organ in the eyestalk, decreased MF synthesis, FAOMeT activity and HMGR activity to 3, 8, and 20%, respectively, of the levels observed in saline-treated animals. The regulation of crustacean HMGR by the SG suggests that the lobster MO is a useful model system for investigating the cellular regulation of HMGR activity.

Biosynthetic maturation of the corpus allatum of the female adult medfly, Ceratitis capitata, and its putative control

The major juvenile hormone (JH) homolog synthesized in vitro by the adult female Medfly (Ceratitis capitata) corpus allatum (CA) is JHB3, with JH-III the minor homolog. Methyl-incorporation in vitro in post-eclosion virgin females is age-dependent. Basal activity occurs during the first four days post-eclosion and increases significantly thereafter, peaking at five days. Biosynthetic maturation of the mated female CA is delayed by one day and reduced considerably. The delayed response may be due to direct cerebral or neural inhibition. Synthetic Drosophila melanogaster sex peptide depresses JH biosynthesis by the Medfly female CA in vitro. Male-derived accessory gland peptides of the Medfly are transferred to the female during mating and a Medfly SP-analog may be responsible for down-regulation of JH synthesis by the CA in mated Medfly females. Mevinolin, an inhibitor of the mevalonate pathway, significantly reduces the biosynthesis of JHB3, while farnesoic acid, a proximate precursor of JHIII, significantly stimulates the biosynthesis of both JHB3 and JHIII in vitro.

Culicine genomics

Aedes aegypti PISCF-allatostatin or allatostatin-C (Ae-AS-C) was isolated using a combination of high performance liquid chromatography and enzyme-linked immunosorbent assay (ELISA). The matrix-assisted laser desorption/ionization time-of-flight (TOF) mass spectrum of positive ELISA fractions revealed a molecular mass of 1919.0 Da, in agreement with the sequence qIRYRQCYFNPISCF, with bridged cysteines. This sequence was confirmed by matrix-assisted laser desorption/ionization tandem TOF/TOF mass spectrometry analysis. The corresponding Ae-AS-C cDNA was amplified by PCR, and the sequence of the peptide was confirmed. An in vitro radiochemical assay was used to study the inhibitory effect of synthetic Ae-AS-C on juvenile hormone biosynthesis by the isolated corpora allata (CA) of adult female A. aegypti. The inhibitory action of synthetic Ae-AS-C was dose-dependent; with a maximum at 10–9 m. Ae-AS-C showed no inhibitory activity in the presence of farnesoic acid, an immediate precursor of juvenile hormone, indicating that the Ae-AS-C target is located before the formation of farnesoic acid in the pathway. The sensitivity of the CA to inhibition by Ae-AS-C in the in vitro assay varied during the adult life; the CA was most sensitive during periods of low synthetic activity. In addition, the levels of Ae-AS-C in the brain were studied using ELISA and reached a maximum at 3 days after eclosion. These studies suggest that Ae-AS-C is an important regulator of CA activity in A. aegypti.

ChemInform Abstract: Evaluation of Morphogenic Regulatory Activity of Farnesoic Acid and Its Derivatives Against Candida albicans Dimorphism.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Function and cellular localization of farnesoic acid O-methyltransferase (FAMeT) in the shrimp, Metapenaeus ensis.

The isoprenoid methyl farnesoate (MF) has been implicated in the regulation of crustacean development and reproduction in conjunction with eyestalk molt inhibiting hormones and ecdysteroids. Farnesoic acid O-methyltransferase (FAMeT) catalyzes the methylation of farnesoic acid (FA) to produce MF in the terminal step of MF synthesis. We have previously cloned and characterized the shrimp FAMeT. In the present study, recombinant FAMeT (rFAMeT) was produced for bioassay and antiserum generation. FAMeT is widely distributed in shrimp tissues with the highest concentration observed in the ventral nerve cord. Interestingly, an additional larger protein in the eyestalk also showed immunoreactivity to anti-FAMeT serum. FAMeT was localized in the neurosecretory cells of the X-organ-sinus gland complex of the eyestalk. As shown by RT-PCR, FAMeT mRNA is constitutively expressed throughout the molt cycle in the eyestalk and the ventral nerve cord. To show that our cloned gene product had FAMeT activity, we demonstrated that expressed rFAMeT gene product catalyzed the conversion of FA to MF in a radiochemical assay. The ubiquitous distribution of FAMeT suggests that this enzyme is involved in physiological processes in addition to gametogenesis, oocyte maturation and development and metamorphosis of the shrimp. We hypothesize that FAMeT directly or indirectly (through MF) modulates the reproduction and growth of crustaceans by interacting with the eyestalk neuropeptides as a consequence of its presence in the neurosecretory cells of the X-organ-sinus gland.