Developmental changes in rat brain membrane lipids and fatty acids. The preferential prenatal accumulation of docosahexaenoic acid.

Information on the prenatal accumulation of rat brain membrane lipids is scarce. In this study we investigated in detail the fatty acid (FA) composition of the rat brain, on each day from embryonic day 12 (E12) up to birth, and on 8 time points during the first 16 days of postnatal life, and correlated the FA changes with well-described events of neurogenesis and synaptogenesis. Between E14 and E17, there was a steep increase in the concentration of all the FAs: 16:0 increased by 136%, 18:0 by 139%, 18:1 by 92%, 20:4n-6 by 98%, 22:4n-6 by 116%, 22:5n-6 by 220%, and 22:6n-3 by 98%. After this period and up to birth, the concentration of the FAs plateaued, except that of 22:6n-3, which accumulated further, reaching an additional increase of 75%. After birth, except 22:5n-6, all FAs steadily increased at various rates. Estimation of the FA/PL molar ratios showed that prenatally the ratios of all the FAs either decreased or remained constant, but that of 22:6n-3 increased more than 2-fold; postnatally the ratios remained constant, with the exception of 22:4n-6 and 22:5n-6, which decreased. In conclusion, prenatal accumulation of brain fatty acids parallels important events in neurogenesis. 22:6n-3 is exceptional inasmuch in its steep accumulation occurs just prior to synaptogenesis.

The p10 gene of Spodoptera littoralis nucleopolyhedrovirus: nucleotide sequence, transcriptional analysis and unique gene organization in the p10 locus.

The p10 gene of the Spodoptera littoralis (Spli) multicapsid nucleopolyhedrovirus (MNPV) was identified. With a coding sequence of 315 nucleotides (nt), corresponding to a protein of 104 amino acids, the SpliMNPV p10 gene is the longest p10 gene known. This gene codes for a putative protein with an Mr of 11130 and was found to be most closely related to the Spodoptera exigua (Se) MNPV p10 (49.4% amino acid identity) and most distant from the Autographa californica (Ac) MNPV p10 (20.0% amino acid identity). Characterization of the protein's secondary structure and a comparison with other p10 protein species suggested that this p10 has an extended alpha-helical domain with high probability of forming a large coiled-coil structure. The p10 mRNA was about 1500 nt long, as determined by Northern blot analysis. Primer extension assay mapped three transcription start sites to a conserved baculovirus late promoter motif, TAAG. In the SpliMNPV genome, the p10 gene is not flanked by genes similar to p26 and p74, as found in SeMNPV, AcMNPV, Choristoneura fumiferana MNPV and Orgyia pseudotsugata MNPV. Instead, an open reading frame (ORF) of 945 bp is located downstream from the p10 gene and is followed by another ORF in opposite orientation, encoding the p74 protein. Upstream of the p10 sequences, an ORF of 552 bp was identified that potentially encodes a 184 amino acid protein of Mr 20925, which showed 52.2% identity with the encoded product of the SeMNPV xb187 gene.

Replenishment of docosahexaenoic acid in n-3 fatty acid-deficient fetal rats by intraamniotic ethyl-docosahexaenoate administration.

A procedure for intraamniotic ethyl-docosahexaenoate (Et-DHA) administration was used to restore the docosahexaenoic acid (DHA; 22:6 n-3) levels in n-3-deficient fetal rats. The state of deficiency, characterized by a 34% and 60% decrease in DHA content of fetal brain and liver, respectively, was attained by feeding the pregnant dams from day 8 and up to 20 days gestation, with an n-3 linolenic acid-deprived diet. After a single intraamniotic administration of Et-DHA on day 18 or 19, a rapid increase in both fetal brain and liver DHA was achieved. This increase was accompanied by a decrease in the docosapentaenoic acid (DPA; 22:5 n-6) level. After 48 hr following Et-DHA administration, the major phospholipids (PLs) phosphatidylserine (PS), phosphatidylethanolamine (PE), and phosphatidylcholine (PC), together accounting for more than 90% of total lipid phosphorus in sunflower oil (SFO)-treated animals, regained the DHA content to levels similar to control animals in both fetal brain and liver tissues. Unlike brain, however, most of the DHA content in liver PLs was restored by 24 hr, suggesting that the fetal liver may have a higher metabolic turnover. The DHA/DPA ratio was used to assess the degree of DHA correction. Fetal brain PS, PC, and PE ratios following Et-DHA administration grew steadily over a period of 48 hr but reached only approximately 60% of the control levels. Liver PS regained a value similar to the control, while those of PC and PE were 33% and 46% lower than the controls, respectively. Alterations in the PL polar head-group composition were observed following the dietary manipulations and Et-DHA administration. Although the intraamniotic injection is an invasive approach, the ability to rapidly enhance DHA acylation during intrauterine life may hold potential clinical value whenever an indication for DHA deficiency exists.

Genomic localization and nucleotide sequence of a lef-8 gene of the Spodoptera littoralis nucleopolyhedrovirus.

A gene similar to lef-8 of the Autographa californica (Ac) nucleopolyhedrovirus (MNPV) was identified in the Spodoptera littoralis (Spli) MNPV. The SpliMNPV lef-8-like gene was localized on the genomic map between 26.9 and 29 map units and is flanked by a chitinase gene and p47 gene. This gene arrangement differs from that of similar genes in the AcMNPV genome, where the lef-8 gene is located about 62 kbp from the chitinase gene and about 7 kbp from the p47 gene. Sequence analyses of the lef-8 gene revealed an ORF of 2730 nucleotides, predicted to encode a protein with Mr 104876. The putative protein is 60.9% identical to the AcMNPV LEF-8 and contains an identical sequence of a conserved motif of DNA-dependent RNA polymerases. Sequences downstream of the lef-8 gene contain two sequence repeats which resemble a repeated motif of the SpliMNPV enhancer element and other repetitive sequences from the viral genome.

Identification and nucleotide sequence of an ecdysteroid UDP-glucosyltransferase gene of Spodoptera littoralis multicapsid nuclear polyhedrosis virus.

The Spodoptera littoralis multicapsid nuclear polyhedrosis virus (SlMNPV) is a member of the Baculoviridae that shows a distant genetic relationship to the prototype Autographa californica MNPV (AcMNPV). Using an AcMNPV gene-specific probe, we identified and mapped an ecdysteroid UDP-glucosyltransferase (egt) gene in the genome of SlMNPV. Sequence determination of a part from the hybridizing DNA fragment revealed an open reading frame of 1548 nucleotides that exhibits 38% and 44% identity to the egt amino acid sequences of AcMNPV and Lymantria dispar MNPV (LdMNPV), respectively. Sequences flanking the SlMNPV egt gene, including the promoter region, were found to be unique to the virus. The presence of this nonstructural gene in SlMNPV and several other baculoviruses points to the importance of egt for the viral infection process.

Spatial and temporal distribution of pheromone biosynthesis-activating neuropeptide in Helicoverpa (Heliothis) armigera using RIA and in vitro bioassay.

A [3H]-PBAN (pheromone biosynthesis-activating neuropeptide) analog was synthesized, and binding of the radioligand to a specific PBAN-antiserum was achieved. The inhibition of binding of the radioligand by unlabeled PBAN, several PBAN analogs, and other competitors was studied and a specific radio-immunoassay was developed. Using this radioimmunoassay we found PBAN-like immunoreactivity in methanol extracts of hemolymph and neural tissues from females. Higher levels of PBAN-like immunoreactivity in extracts of brain-suboesophageal ganglion complexes, corpora cardiaca, thoracic ganglia, and abdominal ganglia were observed during the 4-5th h scotophase when compared to the PBAN-like immunoactivity levels during the 6-11th h photophase. On the other hand, the concentrations of PBAN-like immunoreactivity, in the terminal abdominal ganglion were higher during the photophase relative to minimal levels observed during the scotophase, indicating an accumulation before the onset of pheromone production. These differences in concentrations of PBAN were also reflected in the stimulation of in vitro pheromone glands, whereby significant stimulations were obtained by scotophase and photophase brain extracts, scotophase thoracic ganglia extracts, and photophase terminal abdominal ganglia extracts. No detectable levels of PBAN were found in hemolymph extracts during the sampling periods.