Changes in fatty acids,amino acids and carbon/nitrogen biomass during nitrogen starvation of ammonium- and nitrate-grownIsochrysis galbana

Growth of cells ofIsochrysis galbana with either nitrate or ammonium as the N-source, and the effects of subsequent N-starvation of these cells, were compared. During exponential N-sufficient growth nitrate-grown cells had double the fatty acid content of the ammonium-grown cells but lower concentrations of a few amino acids. Following resuspension in N-free medium the fatty acid content of the ammonium-grown cells increased to that of the nitrate-grown cells, but there was no further increase in fatty acid content on a C-biomass or cellular basis during the following 4 days for either culture. Fatty acid synthesis was continuous during N-starvation, while it occurred during the light-phase only in exponential growth. The proportion of 18:1n9 fatty acid increased from 10 to 25% total fatty acids during N-starvation. Intracellular free amino acid content decreased in a similar manner in both cultures on N-starvation, the ratio of intracellular free amino-N/cell-C falling more rapidly than overall cellular N/C. It was concluded that optimal amino acid and fatty acid content would be attained by growth in the presence of excess nitrate. Measurements of chlorophyll and carotenoid content and ofin vivo fluorescence indicated that these parameters had potential for monitoring the C and N biomass in cultures grown under relatively constant (not necessarily continuous) illumination.     

Identification of variable region differences in Neisseria meningitidis class 3 protein sequences among five group B serotypes

Strains of Neisseria meningitidis express one of two porin proteins. These porins have been identified as the class 2 and class 3 proteins, and express serotype-specific epitopes. The gene for the class 3 protein was amplified by the polymerase chain reaction from the DNA of a serotype 4 strain as a 1025 bp fragment. The nucleotide sequence of this gene was determined and compared with two recently published sequences. On the basis of this comparison we have identified two major variable regions in the translated protein sequence, VR1 and VR2, that may be associated with serotype specificity. Three other variable regions were also identified. The sequences in the VR1 and VR2 regions from five additional group B N. meningitidis strains of serotypes 1, 4, 8, 12, and 15, all expressing class 3 proteins, were determined. The VR1 and VR2 regions were variable and were flanked by highly conserved regions among eight different class 3 sequences. These two variable regions of 15 and 9 amino acids are predicted to be in surface-exposed loops.     

Revision of “<Emphasis Type="Italic">Aemilia</Emphasis>” <Emphasis Type="Italic">pagana</Emphasis> Species-Group (Lepidoptera: Erebidae: Arctiinae), with a Description of a New Endemic Species and Comments on the Conservation Status

A taxonomical rearrangement of “Aemilia” pagana species-group is proposed: Leucanopsis pagana (Schaus in Proc Zool Soc London 1894:225–243, 1894) comb. nov. and L. ninae (Orfila in Rev Soc Entomol Argent 21:67–70, 1959) comb. nov. A new endemic species from Pampa de Achala, Córdoba, Argentina, closer to both species, is described: Leucanopsis navarroi sp. nov. These three species can be recognized because the color pattern is the darkest among species of Leucanopsis. Characteristics of male genitalia suggest the nomenclatural rearrangement proposed. Leucanopsis pagana comb. nov. has a wide distribution from the center of Brazil to northeastern Argentina, including southern Paraguay. The known distribution and geospatial analysis suggest that this species is not in danger. Leucanopsis ninae comb. nov. is restricted to only one known locality (Villa Gesell, Buenos Aires). The restricted known distribution, the different land use practices, and geospatial analysis suggest that this species could be endangered. Leucanopsis navarroi sp. nov. is endemic to the high plateau present in the center of Argentina called Pampa de Achala. The known distribution and geospatial analysis suggest that this species could be endangered. Further studies are necessary to determine effectively the conservation status of these three species.     

Nucleotide Polymorphism at the rp49 region of Drosophila subobscura: Lack of geographic subdivision within chromosomal arrangements in Europe

Restriction-site polymorphism at the rp49 gene region has been studied in 234 lines of Drosophila subobscura representing different gene arrangements for the O chromosome. The population surveyed (El Pedroso, Spain) was sampled four times in each of two consecutive years. The data indicate that the two chromosomal classes studied, O_[ST] and O_{[3 + 4]}, are genetically differentiated in El Pedroso. Comparison of the present results with those previously obtained for two other populations further supports that, for a given chromosomal class, European populations are not genetically differentiated. This lack of differentiation at the rp49 region within O_[ST] and within O_{[3 + 4]} stands in contrast to the clear latitudinal clines found in Europe for these arrangements.     

Biomarker studies on microbial carbonates: Extractable lipids of a Calcifying Cyanobacterial mat (Everglades, USA)

Summary Biomarker investigations are applied to the free lipid fractions of a naturally grown freshwater microbial mat, constructed by calcifying cyanobacteria (Scytonema sp. andSchizothrix sp.). The absolute and relative concentrations of hydrocarbons, free alcohols and carboxylic acids are studied and their probable biological precursors are discussed. A significant signal of cyanobacterial lipids is recognized by the strong predominance ofn-heptadecane (C₁₇),n-heptadecene, two monomethyl-heptadecanes, and the pentacyclic triterpenoid diploptene. Their occurrences parallel the lipid distributions found in pure cultured cyanobacteria and in recent cyanobacterial mats grown in particular environments (hypersaline, lagoonal, hot spring). The observed compound signature appears to be a suitable reference for environments, where cyanobacteria are directly associated with theloci of carbonate precipitation and thus, rock formation. In the studied material, a significant contribution of organic matter from other sources, especially higher plants is characterized by the occurrence of several specific marker compounds, namely lup-20(29)-ene-3-ol, high molecular weightn-alkanes and carboxylic acids. Although these components comprise a notably high portion of the sample’s lipid inventory, they are shown to be distinguished easily from the signal left by the predominant mat building organisms.     

THE MAIN NONPOLAR CHLOROPHYLL c FROM EMILIANIA HUXLEYI (PRYMNESIOPHYCEAE) IS A CHLOROPHYLL c 2-MONOGALACTOSYLDIACYLGLYCERIDE ESTER: A MASS SPECTROMETRY STUDY

The main nonpolar chlorophyll c  -like pigment was extracted from Emiliania huxleyi (Lohm.) Hay et Mohler (strain CCMP 370) cultures and isolated by preparative column chromatography and HPLC. The pigment, whose visible spectrum closely resembled that of chlorophyll c  ₂, was studied by low-resolution fast atom bombardment mass spectrometry, showing a very high mass molecular ion (m/z 1313). The fragment ions, either in the direct spectrum or obtained by tandem mass spectrometry with collision-induced dissociation of the molecular ion, were compatible with the consecutive losses of two fatty acids (14:0 and 18:4), glycerol, and a hexose, leaving a chlorophyll c  ₂ backbone, suggesting the molecule consists of a chlorophyll c  ₂ residue linked, via an ester bond, to the sugar moiety of a monohexosyldiacylglycerol. The identities of the two fatty acid residues (14:0 and 18:4n-3) were subsequently corroborated by gas chromatography of the corresponding methyl esters. Chemical hydrolysis–derivatization–gas chromatography–mass spectrometry demonstrated the occurrence of glycerol and that galactose is the constituent sugar. The porphyrin obtained on acid hydrolysis showed chromatographic and visible spectral properties identical to pheoporphyrin c  ₂. This evidence led us to propose a tentative structure whose molecular formula, C₇₆H₉₆O₁₄N₄Mg, was supported by the values of exact mass measurements by high-resolution fast atom bombardment mass spectrometry. This novel structure represents the highest molecular weight natural chlorophyll described to date.     

Mutagenicity of antiamebic and anthelmintic drugs in the Salmonella typhimurium microsomal test system

4 amebicides (chloroquine diphosphate, diiodohydroxyquin, iodochlorohydroxyquin and dehydroemetine) and 6 anthelmintics (bephenium hydroxynaphthoate, 4-hexylresorcinol, mebendazole, niclosamide, pyrantel pamoate and pyrvinium pamoate) were tested for mutagenicity in the Salmonella typhimurium microsomal test system. Frameshift mutations were induced by dehydroemetine and niclosamide following activation by microsomal enzymes, while pyrvinium pamoate induced both frameshift and base-pair substitution mutations with or without metabolic activation. The urine of mice treated with dehydroemetine or pyrvinium pamoate showed no mutagenic activity. However, urine obtained from mice treated with niclosamide was mutagenic in strains TA98 and TA1538. The fluctuation assay showed chloroquine diphosphate to be mutagenic in TA1537, a strain which detects frameshift mutations.     

Voraussetzungen und derzeitige Grenzen der quantitativen elektronenmikroskopischen Autoradiographie bei Kinetikstudien an Drüsenzellen

Zusammenfassung Einer weiblichen Maus wurde 3 Tage post partum 750 C ³H-Leucin i. p. injiziert. Zu verschiedenen Zeiten nach der Leucinapplikation wurden dem leicht narkotisierten Tier Gewebeteile der Milchdrüse entnommen und zu elektronenmikroskopischen Autoradiogrammen verarbeitet. An Hand der dabei gewonnenen Ergebnisse wurde versucht, den zeitlichen Ablauf der Milcheiweißbildung rechnerisch zu erfassen. 5 und 15 min nach der ³H-Leucinapplikation kann die Aktivität über dem rauhen endoplasmatischen Retikulum, nach 30 min über dem Golgi-Feld, und nach 240 min zur Hauptsache über den Lumina der Ausführungsgänge beobachtet werden. Die Halbwertszeit von markierten Proteinen im Ergastoplasma errechnete sich zu etwa 22 min, diejenige im Golgi-Feld zu etwa 3 Std.Die Voraussetzungen und derzeitigen Grenzen einer quantitativen elektronenmikroskopischen Autoradiographie werden diskutiert. Wegen der vielen möglichen Fehlerquellen wird die Berechnung der Kinetik der Milcheiweißbildung lediglich als Modell gewertet.

---

Summary A female mouse, 3 days post partum, was injected with ³H-leucine. After various intervals parts of the mammary gland were processed for electronmicroscopic autoradiograms, the results of which were mathematically evaluated in order to understand the temporal course of milk protein formation. After 5 and 15 minutes the leucine-activity is located mainly in the rough endoplasmic reticulum, after 30 minutes in the Golgi field and after 240 minutes in the lumina of the mammary ducts. The half-live time of labelled proteins in the rough endoplasmic reticulum is about 22 minutes, in the Golgi field about 3 hours.The preconditions and limitations of quantitative electronmicroscopic autoradiography are discussed. Because of the many possible sources of error, the calculations of the kinetics of protein synthesis and secretion in the mammary gland are merely regarded as a model.

---

---

Ausgeführt mit Unterstützung durch die Deutsche Forschungsgemeinschaft.

---

Wesentliche Teile der Arbeit werden Von Ute Seitter der Medizinischen Fakultät der Universität Freiburg i. Br. als Inaugural-Dissertation vorgelegt.     

Plant regeneration through somatic embryogenesis from mature seed and young inflorescence of wild rice (Oryza perennis Moench)

Somatic embryogenesis in the wild rice species (Oryza perennis) was induced from cultured mature seeds and young inflorescences. Murashige and Skoog's (MS) medium supplemented with 2 mg/l 2,4-D and 0.2 mg/l BAP was used for induction of a compact, white nodular callus and somatic embryos. Plant regeneration occurred with the tranfer of the nodular callus to MS basal medium containing 0.5 mg/l IAA, 0.5 mg/l NAA, 4 mg/l BAP and 500 mg/l casein hydrolysate. The embryogenic nature of the callus from both explants was maintained over 10 subcultures for about 12 months. Plant regeneration with respect to the number of calli plated from the 6th to 10th passage varied from 80% to 60% for young inflorescence derived callus and from 75% to 69.8% for seed-derived callus.Abbreviations MS Murashige and Skoog medium - BAP 6-benzylaminopurine - 2,4-D 2,4-dichlorophenoxyacetic acid - IAA indole-3-acetic acid - NAA naphthalene acetic acid - CH casein hydrolysate     

A test for choosing the most convenient procedure for chloropigment analysis by RP-HPLC

A test to choose the most appropriate procedure for the analysisof chloropigments in natural marine samples is described. Thistest allows the selection of the most convenient RP-HPLC method:a rapid one or a gradient method with which both polar and non-polarchloropigments can be analysed.