Population genetic studies of the Atlantic halibut in the North Atlantic Ocean

Significant variation in frequency distribution of electrophoretically detectable protein variants between samples of Atlantic halibut Hippoglossus hippoglossus showed that the halibut from northern Norway and from the Faroes–Iceland–Greenland region may not belong to one panmictic population.     

Muscle growth in yolk-sac larvae of the Atlantic halibut as influenced by temperature in the egg and yolk-sac stage

Atlantic halibut eggs and yolk-sac larvae were incubated at 1, 5 and 8° C. Eggs incubated at 8° C gave slightly shorter larvae at hatching with a significantly smaller total cross-sectional area of white muscle fibres than eggs incubated at 5° C. Transport of eggs 2 days prior to hatching gave significantly longer larvae at hatching with a significantly larger red fibre cross-sectional area than when eggs were transported shortly after the blastopore closure. A higher survival until 230 degree days after hatching was also observed in the former group. All eggs incubated at 1° C died before hatching and all larvae incubated at 1° C died before 45 degree days after hatching. From hatching until 230 degree days the total white cross-sectional area increased threefold in all temperature groups. The increase in white cross-sectional area was entirely due to hypertrophy between hatching and 150 degree days (10 mm L _S). Recruitment of new white fibres increased in germinal zones at the dorsal, ventral and lateral borders of the myotome from 150 degree days onwards, but at 230 degree days (12–13 mm L _S) the recruitment fibre zone constituted <10% of the total white cross-sectional area. Larval incubation at 8° C gave slightly longer larvae with a significantly larger cross-sectional area of recruitment fibres at 230 degree days than incubation at 5° C. The larval group incubated at 8° C also had a significantly lower survival until 230 degree days than did the 5° C group. Incubation temperature regimes did not affect the volume density of myofibrils in the axial muscle fibres at 230 degree days. Thus hypertrophy is the predominant mechanism of axial white muscle growth in Atlantic halibut yolk-sac larvae and an increased rearing temperature during the yolk-sac stage increases white muscle fibre hyperplasia.     

A study of the mechanism of algal uptake in yolk-sac larvae of Atlantic halibut (Hippoglossus hippoglossus)

The drinking rate of water, and the ingestion- and assimilation rates of algae in yolk-sac larvae of Atlantic halibut were examined by use of³H-dextran and¹⁴C-labelled algae. The drinking rate throughout the yolk-sac stage was in the range of 7–160 nl per larva h⁻¹, with a slight increase towards the end of the period. The ingestion rate of algae ( Tetraselmis sp.) was very low before day 30 and showed a peak between day 43 and 48 at 5° C. The assimilation efficiency of the algae was in the range of 1-5%. The clearance rate of algae was 100–1000 times higher than the drinking rate, and was correlated to the distance between the gill arches. Bigger cells were more effectively retained than smaller ones. The results suggested that the larvae acted as filter feeders from day 30 up to the point when they are expected to start feeding on bigger prey.     

Cholecystokinin and tryptic activity in the gut and body of developing Atlantic halibut larvae: evidence for participation in the regulation of protein digestion

At 7 days after first feeding (DAFF), the peptide hormone cholecystokinin (CCK) content (fmol individual^?1) and the tryptic activity [μmol arginine‐methyl‐coumarinyl‐7‐amide (MCA) min^?1 individual^?1] per individual gut of Atlantic halibut Hippoglossus hippoglossus larvae were low: 0·2 ± 0·1 and 0·14 ± 0·10, respectively. Thereafter, both parameters increased with the increase in gut mass and reached 19·67 ± 5·58 and 2·71 ± 0·64 at 26 DAFF, respectively. Due to the small sample size, the dry mass (M_G, mg) of the individual gut could not be determined accurately at 7 DAFF. At 13 DAFF M_G represented 5·5% of whole body dry mass (M_w, mg) while at 26 DAFF it had increased to 23%. The mass specific tryptic activity [μmol MCA min^?1 per mg dry mass (M)] in the gut increased from 2·74 ± 1 ± 98 at 13 DAFF to 5·00 ± 0·78 at 26 DAFF. There was more individual variation in the mass specific CCK content (fmol M^?1) but no significant differences were found, although the data indicated an increase (from 23·38 ± 11·26 at 13 DAFF to 36·27 ± 8·96 fmol M^?1 at 26 DAFF). At 7 DAFF the CCK content of the gut represented c. 2% of the whole body CCK content while it increased to c. 62% of the whole body CCK content at 26 DAFF. This demonstrates that it is necessary to separate neural and gastrointestinal sources of CCK in order to determine its alimentary role in fish larvae. Trypsin activity was only found in the gut compartment. In larvae aged 45 DAFF dietary proteins delivery into the gut by tube‐feeding appeared to stimulate post‐prandial secretion of CCK from the gut as well as stimulate pancreatic trypsin secretion, suggesting that both factors contribute to protein digestion.     

Histomorphology of the early yolk-sac larvae of the Atlantic halibut (Hippoglossus hippoglossus L.)—an indication of the timing of functionality

Halibut larvae hatch at a very immature stage, and the duration of the yolk-sac period is very long (up to 50 days). This paper describes the histomorphological development of organs of the yolk-sac larvae (6° C) by use of light and electron microscopy. Rudimentary branchial cavities were open from 2 days after hatching. Kidneys seemed functional 16 days after hatching and onwards, and primitive lamellae on the gill arches were beginning to form at this age. Pancreatic zymogen granules were first observed 20daysafter hatching. The liver was segmented into lobes between 20 and 23 days after hatching, and the gall bladder seemed functional from day 23. The hindgut became extensively folded from day 26, and branchial capillaries were first observed at this stage. The larvae were able to catch food particles 24 days after hatching. Judging from ultrastructural observations, it seemed that halibut larvae were able to digest food particles between day 24 and 26 after hatching (around 150 daydegrees and 50% yolk absorption).     

The antioxidant effects of thylakoid Vitamin E (α-tocopherol)

Vitamin E (α-tocopherol) is essential for the prevention of photo-oxidative deterioration of biomembranes. The occurrence, relative biological activity and distribution of tocopherols in photosynthetic membranes is considered together with the possible biochemical and biophysical mechanisms by which tocopherols confer protection upon illuminated membranes. The common protective effects of Vitamin E in photo-synthetic membranes and in medically important light-induced diseases and conditions of the skin and eye in animal cell membranes are discussed. The importance of the Vitamin E-Vitamin C thylakoid antioxidant system is also examined, in terms of susceptibility to photo-oxidative damage under stress conditions including chilling, ageing and senescence, drought, atmospheric pollutants, herbicides and photosensitizing fungal toxins.     

Increased production of docosahexaenoic acid (22: 6 n-3, DHA) in catfish nutritionally stressed by the feeding of oxidized oils and the modulatory effect of dietary α-tocopheryl acetate

Production of hepatic docosahexaenoic acid in juvenile Clarias gariepinus was significantly increased ( P <0.05) by ingestion of rancid diets and this effect was modulated by dietary vitamin E. This has not been described previously in fish. Causal mechanisms are postulated.     

Different iodine and thyroid hormone levels between Atlantic halibut larvae fed wild zooplankton or Artemia from first exogenous feeding until post metamorphosis

The iodine concentration in wild zooplankton was 700 times higher than in Artemia and threefold higher in Atlantic halibut Hippoglossus hippoglossus larvae fed wild zooplankton than in those fed Artemia . In larvae fed wild zooplankton thyroxine (T4) and triiodothyronine (T3) concentrations were significantly higher than in those fed Artemia at the commencement of metamorphosis, 68–77 days post hatching. There was no difference in the amino acids phenylalanine and tyrosine levels in larvae fed Artemia in comparison with those fed wild zooplankton. The selenium level was significantly higher in larvae fed Artemia than in those fed wild zooplankton, but concentrations in the prey were not different. The results indicate sufficient amounts of phenylalanine, tyrosine and selenium in Artemia , but indicated a lower thyroid status due to an insufficient iodine supply at commencement of metamorphosis in larvae fed Artemia . This may partly explain the higher frequency of juveniles with complete eye migration and asymmetric pigmentation in the group fed wild zooplankton.     

Coinduction of α-L-arabinofuranosidase and α-D-galactosidase formation in Trichoderma reesei RUT C-30

Abstract Formation of α-L-arabinosidase can be induced in Trichoderma reesei by growing the fungus on L-arabinose or dulcitol, and by adding L-arabinose, L-arabitol, D-galactose, or dulcitol ot non-growing mycelia. The same conditions also stimulated the formation of α-D-galactosidase, but not that of various other enzymes involved in hemicellulose degradation. The optimal inducer concentration with all compounds was 4 mM for both enzymes. Using L-arabinose and D-galactose, the induction efficiency was highest at pH 6.5, whereas induction by arabitol and dulcitol was more efficient at low pH (2.5). The addition of 50 mM glucose did not repress α-L-arabinosidase or α-D-galactosidase formation. These findings suggest coregulation of two hemicellulose side-chain cleaving enzymes in T. reesei .     

Prevention of auxin-induced epinasty by α-aminooxyacetic acid

Elhylene production and epinastic growth of leaf petioles of tomato (Lycopersicon esculentum Mill. cv. Moneymaker) plants sprayed with 0.1 mM naphthyl-1-acetic acid were suppressed when 1 mMα-aminooxyacetic acid (AOA) was simultaneously sprayed on the plants. AOA had no effect on ethylene evolution and epinastic growth resulting from the application of 5 mM 1-aminocyclopropane-1-carboxylic acid, the immediate precursor of ethylene.     

Isolation and Identification of α-(γ-Aminobutyryl)-Hypusine

A new dipeptide, alpha-(gamma-aminobutyryl)-hypusine, was identified in bovine brain. This compound was isolated from trichloroacetic acid-soluble fraction of bovine brain with five steps of ion-exchange chromatography. Its structure was postulated by routine chemical analyses and determined by synthesis. The amount of the compound isolated from 1.2 kg of bovine brain was 870 nmol.     

Convulsive Activity of α-Guanidinoglutaric Acid and the Possible Involvement of 5-Hydroxytryptamine in the α-Guanidinoglutaric Acid-Induced Seizure Mechanism

alpha-Guanidinoglutaric acid (alpha-GGA) was first found in cobalt-induced epileptogenic focus tissue in the cerebral cortex of cats. We examined the effect of alpha-GGA on the electroencephalogram and on the brain 5-hydroxytryptamine (5-HT) level after intraventricular administration into rats. Sporadic low-voltage spikes appeared 4 min after the administration of alpha-GGA. Spikes increased in voltage 6 min after the administration. Multiple spikes appeared 10 min after the administration, and they reached maximal frequency 30 min after the administration. The epileptic discharges disappeared 100 min after the administration. The 5-HT level increased in the right and left cortices 3 min after the administration. The 5-HT level decreased in the mid-brain 5 min after the administration and subsequently in all regions of the brain 10 min after the administration. No change in the 5-HT level was found 30 min and 100 min after the administration. These results show that alpha-GGA induces epileptic seizures in rats after intraventricular administration. The results also suggest that alpha-GGA-induced seizures are associated with abnormal serotonergic function and that they are initiated by a decrease in the 5-HT level.     

Presence of α7 nicotinic acetylcholine receptors on dorsal root ganglion neurons proved using knockout mice and selective α-neurotoxins in histochemistry

In complex tissues where multiple subtypes of nicotinic acetylcholine receptors (nAChRs) are expressed, immunohistochemistry has been the most popular tool for investigation of nAChR subunit distribution. However, recent studies with nAChR subunit knockout mice demonstrated that a large panel of antibodies is unsuitable. Thus, we aimed to develop a histochemical method for selective labeling of α7 nAChR with neurotoxins, utilizing α7 nAChR-transfected cells, dorsal root ganglia (DRG) and spinal cord from wild-type and knockout mouse. The specificity of Alexa Fluor 488-conjugated α-bungarotoxin (Alexa-αBgt) was demonstrated in binding to α7-transfected cells inhibited by long-chain α-cobratoxin (CTX), but not short-chain α-neurotoxin II (NTII). In contrast, binding to Torpedo muscle-type nAChRs and to motor end plates in mouse tongue sections was prevented by both CTX and NTII. In tissue sections of DRG, expressing all neuronal nAChR subunits, only CTX precluded Alexa-αBgt labeling of neurons, with no staining for α7 nAChR knockout tissue. It proved that α7 nAChRs are the major αBgt-binding sites in mouse DRG. Corresponding results were obtained for terminals in the spinal cord. Thus, we present a protocol utilizing Alexa-αBgt and non-labeled CTX/NTII that allows specific histochemical detection of α7 nAChR with a spatial resolution at the level of single axon terminals.     

Regulation of δ-(L-α-aminoadipyl)-l-cysteinyl-d-valine and isopenicillin N biosynthesis in Penicillium chrysogenum by the α-aminoadipate pool size

The effect of changes in the intracellular concentration of alpha-aminoadipate on the formation of alpha-aminoadipyl-cysteinyl-valine (ACV) and isopenicillin N (IPN)--two intermediates of penicillin biosynthesis--by strains of Penicillium chrysogenum has been investigated by measuring the incorporation of radioactivity from (6-14C)-alpha-aminoadipate into cellular 14C-ACV and 14C-IPN. No ACV or IPN were found in any strain during cultivation on glucose, but were clearly detected in all three strains during growth on lactose, displaying increased formation in strains exhibiting increased penicillin productivity and increased intracellular alpha-aminoadipate pools. ACV and IPN formation was affected by subjected P. chrysogenum mycelia to either general amino acid control (by addition of amitrol) or by exogenous addition of 5 mM L-lysine. In all cases, the changes observed paralleled the changes in the intracellular alpha-aminoadipate pool. These results are consistent with the alpha-aminoadipate pool limiting the biosynthesis of ACV and IPN and hence penicillin biosynthesis in the present strains of P. chrysogenum.     

Variation in size and location of the Ag-NOR in the Atlantic halibut (<Emphasis Type="Italic">Hippoglossus hippoglossus</Emphasis>)

The distribution of differentially stained chromatin was studied in the Atlantic halibut (Hippoglossus hippoglossus) chromosomes (2n = 48). Four pairs of homologous chromosomes were identified using a combination of traditional cytogenetic staining techniques (Giemsa/DAPI/CMA3/Ag-NO3). Chromosome 1 showed a length polymorphism (1^S-short, 1^L-long isoforms of the chromosome 1) which was related to the variation of the size of the Ag-NORs. In one specimen the Ag-NOR was translocated from chromosome 1 into the telomeric region on the q-arm of the chromosome 2 forming a derivative chromosome der(2)t(1^S;2)(q?;q?). Four Ag-NOR genotypes have been shown: 1^S1^S, 1^S1^L, 1^L1^L and 1^S der(2)t(1^S;2)(q?;q?). The chromosome rearrangements did not leave any interstitially located telomeric sequences and the telomeres were confined to the ends of the chromosomes. A single chromosomal location of 5S rDNA clusters was found using the PRINS technique. In the extended metaphase spreads two adjacent clusters of 5S rDNA could be seen on one chromosome while condensed chromatin gave a single hybridization signal. Double 5S rDNA signals on the same chromosome arm suggested paracentric inversion of the minor rDNA site. 5S rDNA clusters were not co-localized with Ag-NORs. Although female and male karyotypes were compared no sex related cytogenetic markers were found.     

Effects of Gibberellic Acid on Primary Terpenoids and Δ9-Tetrahydrocannabinol in Cannabis sativa at Flowering Stage

Plants synthesize an astonishing diversity of isoprenoids, some of which play essential roles in photosynthesis, respiration, and the regulation of growth and development. Two independent pathways for the biosynthesis of isoprenoid precursors coexist within the plant cell: the cytosolic mevalonic acid (MVA) pathway and the plastidial methylerythritol phosphate (MEP) pathway. However, little is known about the effects of plant hormones on the regulation of these pathways. In the present study we investigated the effect of gibberellic acid (GA₃) on changes in the amounts of many produced terpenoids and the activity of the key enzymes, 1-deoxy-D-xylulose 5-phosphate synthase (DXS) and 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR), in these pathways. Our results showed GA₃ caused a decrease in DXS activity in both sexes that it was accompanied by a decrease in chlorophylls, carotenoids and Δ⁹-tetrahydrocannabinol (THC) contents and an increase in α-tocopherol content. The treated plants with GA₃ showed an increase in HMGR activity. This increase in HMGR activity was followed by accumulation of stigmasterol and β-sitosterol in male and female plants and campestrol in male plants. The pattern of the changes in the amounts of sterols was exactly similar to the changes in the HMGR activity. These data suggest that GA₃ can probably influence the MEP and MVA pathways oppositely, with stimulatory and inhibitory effects on the produced primary terpenoids in MVA and DXS pathways, respectively.     

Chronic nutritional deprivation of n-3 α-linolenic acid does not affect n-6 arachidonic acid recycling within brain phospholipids of awake rats

Using an in vivo fatty acid model and operational equations, we reported that esterified and unesterified concentrations of docosahexaenoic acid (DHA, 22 : 6 n-3) were markedly reduced in brains of third-generation (F3) rats nutritionally deprived of alpha-linolenic acid (18 : 3 n-3), and that DHA turnover within phospholipids was reduced as well. The concentration of docosapentaenoic acid (DPA, 22 : 5 n-6), an arachidonic acid (AA, 20 : 4 n-6) elongation/desaturation product, was barely detectable in control rats but was elevated in the deprived rats. In the present study, we used the same in vivo model, involving the intravenous infusion of radiolabeled AA to demonstrate that concentrations of unesterified and esterified AA, and turnover of AA within phospholipids, were not altered in brains of awake F3-generation n-3-deficient rats, compared with control concentrations. Brain DPA-CoA could be measured in the deprived but not control rats, and AA-CoA was elevated in the deprived animals. These results indicated that AA and DHA are recycled within brain phospholipids independently of each other, suggesting that recycling is regulated independently by AA- and DHA-selective enzymes, respectively. Competition among n-3 and n-6 fatty acids within brain probably does not occur at the level of recycling, but at levels of elongation and desaturation (hence greater production of DPA during n-3 deprivation), or conversion to bioactive eicosanoids and other metabolites.