Problems in estimating growth rates of marine phytoplankton from short-term14C assays

Growth rate estimates () of phytoplankton populations that were sampled from nitrogen-limited continuous cultures and then incubated for short durations in batch culture with added¹⁴C-HCO₃ ^– were significantly different than steady-state growth rates () for 3 of 5 marine phytoplankton species. Two diatoms,Thalassiosira weissflogii andChaetoceros simplex, displayed virtually identical growth rates (=) over a wide range of, whereas for a third diatom,Phaeodactylum tricornutum, was overestimated by an average of 40% compared to. In contrast, was underestimated by the¹⁴C technique for the two remaining species: up to 40% at a steady-state of 1.0 day^–1 for the chlorophyteDunaliella tertiolecta and up to 100% at of 1.4 day^–1 for the haptophytePavlova lutheri. For the latter two species the divergence between and appeared to increase with increasing steady-state. A simple model of labeled and total carbon flow between the aqueous phase and cellular biomass was constructed to demonstrate that respiration was negligible when=, but was significant when>. In the cases in which<, a rapid physiological alteration presumably took place once the steady state was disturbed and cells were placed in the incubation chambers, which perhaps was related to the nutritional state of the cultures at the time of sampling. Questions thus are raised regarding our ability to measure accurately primary productivity from shipboard experiments with confined samples of phytoplankton from nutrient-impoverished waters that probably are less hardy than the laboratory cultures used in these studies.     

Effects of β-Amyloid-(25-35) Peptides on Radioligand Binding to Excitatory Amino Acid Receptors and Voltage-Dependent Calcium Channels: Evidence for a Selective Affinity for the Glutamate and Glycine Recognition Sites of the NMDA Receptor

The neurotoxic fragment corresponding to residues 25-35 of the -amyloid (A) peptide [A-(25-35)] has been shown to exert effects on (+)-[³H]5-methyl-10,11-dihydro-5H-dibenzo[a,d]-cyclohepten-5,10-imine maleate ([³H]MK-801) binding to the cation channel of the N-methyl-D-aspartate (NMDA) receptor. In the present study, we investigated whether the amidated and carboxylic acid C-terminated forms of A-(25-35) [A-(25-35-NH₂) and A-(25-35-COOH), respectively] exert effects on other excitatory amino acid receptor and cation channel types in rat cortical membranes. Both A-(25-35-NH₂) and A-(25-35-COOH) gave statistically significant dose-dependent inhibitions of [³H]glutamate and [³H]glycine binding to the agonist recognition sites of the NMDA receptor. Ten M A-(25-35-NH₂) and A-(25-35-COOH) gave 25% and 20% inhibitions of [³H]glutamate binding and 75% and 70% inhibitions of [³H]glycine binding, respectively. A-(25-35-NH₂), but not A-(25-35-COOH), gave a small (ca. 17% at 10 M) statistically significant increase of [³H]amino-3-hydroxy-5-methylisoxazole-4-propionate ([³H]AMPA) binding. [³H]kainate binding was not significantly affected by either peptide. Similarly, neither peptide affected either the maximal level or EC₅₀ value for calcium stimulation of [³H]nitrendipine binding. It is concluded that A-(25-35) shows slight affinity for the agonist recognition sites of the NMDA receptor, but not for other excitatory amino acid receptor types or for L-type voltage-dependent calcium channels.     

Alpha-thalassemia in Papua New Guinea

Summary A study of the distribution of -thalassemia in Papua New Guinea (PNG) was carried out by DNA analysis. A total of 664 DNA samples were screened for -thalassemia 2 and -thalassemia 1 caused respectively by either deletion of one or both of the duplicated -globin genes. -Thalassemia 2 was detected in high frequencies in coastal and lowland regions where malaria has been holo- to hyperendemic but in low frequencies in non-malarious highland regions. The highest frequency was observed in the north coast of PNG. The distribution of -thalassemia 2 seems to be in accordance with other conditions such as ovalocytosis and G6PD deficiency which are also prevalent in this population, suggesting that they may interact in protection against malaria. However, it appears to be negatively correlated with -thalassemia and -thalassemia 1, the latter being extremely rare in this population. Analysis of the types and subtypes of the single -globin gene deletion revealed a predominance of the –^4.2 type in general, except in some regions in the south where the –^3.7 type is prevalent. The –^3.7 I subtype is the common form of the –^3.7 deletion in the PNG mainland. The –^3.7 III subtype, previously reported to be unique in Melanesians and Polynesians, was detected in an offshore island of PNG. However, this subtype is very rare in Melanesians from the PNG mainland.     

Electrochemical potential of protons in vesicles reconstituted from purified,proton-translocating adenosine triphosphatase

Summary Measurements were made of the difference in the electrochemical potential of protons ( ) across the membrane of vesicles reconstituted from the ATPase complex (TF ₀ ·F ₁) purified from a thermophilic bacterium and P-lipids. Two fluorescent dyes, anilinonaphthalene sulfonate (ANS) and 9-aminoacridine (9AA) were used as probes for measuring the membrane potential () and pH difference across the membrane ( pH), respectively.In the presence of Tris buffer the maximal and no pH were produced, while in the presence of the permeant anion NO ₃ ^– the maximal pH and a low were produced by the addition of ATP. When the ATP concentration was 0.24mm, the was 140–150 mV (positive inside) in Tris buffer, and the pH was 2.9–3.5 units (acidic inside) in the presence of NO ₃ ^– . Addition of a saturating amount of ATP produced somewhat larger and pH values, and the attained was about 310 mV.By trapping pH indicators in the vesicles during their reconstitution it was found that the pH inside the vesicles was pH 4–5 during ATP hydrolysis.The effects of energy transfer inhibitors, uncouplers, ionophores, and permeant anions on these vesicles were studied.     

Measurement of 2J(H,C)- and 3J(H,C)-coupling constants by α/β selective HC(C)H-TOCSY

A new heteronuclear NMR pulse sequence for the measurement of ⁿJ(C,H) coupling constants, the /selective HC(C)H-TOCSY, is described. It is shown that the S³E element (Meissner et al., 1997a,b) can be used to obtain spin state selective coherence transfer in molecules, in which adjacent CH moieties are labeled with ¹³C. Application of the / selective HC(C)H-TOCSY to a 10nt RNA tetraloop 5-CGCUUUUGCG-3, in which the four uridine residues are ¹³C labeled in the sugar moiety, allowed measurement of two bond and three bond J(C,H) coupling constants, which provide additional restraints to characterize the sugar ring conformation of RNA in cases of conformational averaging.     

Natural selection on age of maturity in shrimp

Summary Darwinian fitness with respect to the age of maturity () in stationary populations can be written as the product of two functions: pre- survival times the Fisherian reproductive value of an age (a just mature) individual. This reduces normalizing selection on to the maximization of a simple product,a twodimensional problem (Charnov in press). I apply this products theorem to in Pandalid shrimp and compare the results to previous analysis (Roff, 1986) of in fish.     

Cloning and expression in Saccharomyces cerevisiae of a β-amylase gene from the oomycete Saprolegnia ferax

Genomic DNA and cDNA encoding the -amylase from the oomycete, Saprolegnia ferax, were cloned into Saccharomyces cerevisiae and analyzed. The Spl. ferax -amylase gene consisted of a 1350 bp open reading frame, encoding a protein of 450 amino acids with a calculated mass of 49353 Da, and was not interrupted by any intron. The deduced amino acid sequence of the -amylase gene had 42% similarity to the -amylase of Arabidopsis thaliana. The -amylase gene was expressed in Sacc. cerevisiae and its product was secreted into the culture medium.     

Genetics of resistance to Puccinia graminis tritici in ‘Chris’ and ‘W3746’ wheats

Summary Chris wheat possessed genes Sr5, Sr7a, Sr8a, Sr9g and Sr12. W3746, derived from the cross Chris/Baart, possessed Sr7a and Sr12. The response conferred by Sr7a was influenced by the genetic background. Although Sr7a or Sr12 alone conferred no observable resistance upon adult plants, the adult resistances of Chris and W3746 to predominant pathotypes appeared to be associated with the interaction of Sr7a and Sr12, or genes at closely linked loci.     

Uptake of DOPA and 5-HTP in pancreatic islets and parafollicular cells studied by combined autoradiographic and fluorescence microscopic techniques

Summary White albino mice were simultaneously injected with ³H-5-HTP and unlabelled DOPA or ³H-DOPA and unlabelled 5-HTP. The distribution patterns of the formed indol- and catecholamines in a) the pancreatic islets and b) the parafollicular cells were then compared by use of a combined autoradiographic-fluorescence microscopic technique.Localization in the same sections of radioactivity and fluorescence representing the respective monoamines corresponded very well for all the time intervals studied both in the pancreatic islets and in the parafollicular cells.In the pancreatic islets the monoamines were localized in all cells shortly after the injection of the precursors. The monoamines then first disappeared from the -cells leaving the -cells with the highest concentration of activity and fluorescence. In the thyroid the activity and fluorescence, localized in the same parafollicular cells, persisted for a longer time than in the islets.The authors wish to express their gratitude to Professor Sven Ullberg, Head of the Department of Toxicology, University of Uppsala, for much valuable advice during this work. The investigation was supported by grants from the Swedish Medical Research Council (No. 12x-713-01), Knut and Alice Wallenbergs Stiftelse and Ragnar and Torsten Söderbergs Stiftelse.     

Production of β-fructofuranosidase byAspergillus japonicus

A newly isolated strain, MU-2, which produces very high -fructofuranosidase activity, was identified asAspergillus japonicus. For enzyme production by the strain, sucrose at 20% (w/v) was the best carbon source and yeast extract at 1.5 to 3% (w/v) the best nitrogen source. Total enzymatic activity and cell growth were at maximum after 48 h, at 1.57×10⁴ U/flask and 0.81 g dry cells/flask, respectively. The optimum pH value of the enzymatic reaction was between 5.0 and 5.5 and the optimum temperature 60 to 65°C. The enzyme produced 1-kestose (O--d-fructofuranosyl-(21)--d-fructofuranosyl -d-glucopyranoside) and nystose (O--d-fructofuranosyl-(21)--d-fructofuranosyl-(21)--d-fructofuranosyl -d-glucopyranoside) from sucrose by fructosyl-transferring activity. The strain was found to be very useful for industrial production of -fructofuranosidase.     

Determination of internal dynamics of deoxyriboses in the DNA hexamer d(CGTACG)2 by 1H NMR

The conformations and internal dynamics of the deoxyriboses of d(CGTACG)₂ have been determined by NMR measurements at 15°C. The conformations of the sugars were determined using coupling constants and time-dependent NOE measurements. The J-splitting patterns of the H1, H2 and H2 resonances show that the sugars exist as mixtures of conformations near C2 endo (south) and C3 endo (north). The population of the south conformation was larger for the purines than for the pyrimidines. The overall tumbling time of the molecule in ²H₂O was determined from measurements of the cross relaxation rate constant for the H6-H5 vectors of the two cytosine residues. Order parameters were determined for the H1-H2, H2-H2 and H2-H3 vectors from measurements of cross relaxation rate constants, making use of multi-spin analysis of the NOE build up rates. These order parameters are weakly dependent of the base sequence, and except for the terminal Cyt 1 residue, the H2-H2 and H2-H3 vectors are near unity, indicating the absence of rapid pseudorotation on the nanosecond time scale. However, the order parameter for the H1-H2 vector is significantly smaller than expected for rapid pseudorotation indicating the presence of other motions of the sugars. This motion must be about an effective axis parallel to the H2-H vector, and to occur with an angular fluctuation of about 30°.The results show that to obtain highly refined structures for nucleic acids by NMR the effects of spin diffusion and motional averaging cannot be ignored.Some of this work was presented as a poster at the 30^th Experimental NMR Conference at Asilomar, California 1989     

Lambda transducing phages derived from a FinO- R100::lambda cointegrate plasmid: proteins encoded by the R100 replication/incompatibility region and the antibiotic resistance determinant.

Summary Three transducing phages have been isolated from pEDR20, an R100:: cointegrate plasmid in which the insertion inactivated the R100 finO gene. Physical analysis of the three phages showed that the is inserted at kilobase coordinate 81.3 of R100. All three phages carry different amounts of R100 DNA in the left arm of . Each phage contains IS1b, the mer genes and the region between coordinate 81.3 and 88.6; thus, all contain the genes necessary for R100 replication. One phage, VA73, contains the entire r-determinant of R100 in addition to the above DNA. Five proteins coded by the region between 81.3 and 88.6 were detected. These had subunit molecular weights of 10,400; 12,200; 16,200; 19,600; and 38,300. The first was made constitutively and the other four only from a promoter. Other constitutive proteins were one from the cml fus region with a molecular weight of 22,400 (cml) and two from the str sul region with molecular weights of 31,500 (str?) and 30,100 (sul?). Mercuric ion induced synthesis of at least 10 proteins. Six of these were known from earlier work. The total size of the proteins which appear to derive from the mer genes exceeds by a factor of 1.5, the coding capacity of this region without overlapping genes. Some, or all of these extra proteins may be chromosomal in origin, possibly derepressed in response to mercury gene products.     

An immunodominant site of γ-zein1 is in the region of tandem hexapeptide repeats

The immunochemical data from studies with polyclonal antisera to -zein₁, the 27 kD component of the maize prolamin, indicated that the region containing 8 tandem repeats of the sequence PPPVHL is an immunodominant site. In one case, the entire antibody repertoire of an antiserum recognized epitope(s) within this region. Three 17-mer oligopeptides corresponding to the predicted antigenic epitopes of -zein₁ were synthesized and reacted with three different anti--zein₁ sera in order to map antigenic sites in the intact protein. These antisera yielded positive reactions with a 17-mer peptide (peptide 37), which was not in a hydrophilic maximum but derived from the repeat region. The same antisera gave little or no reaction with other peptides (peptides 38 and 39), both of which were in a hydrophilic maximum. In addition, an antiserum to peptide 37 reacted strongly with both the homologous antigen and the intact -zein₁. Peptide 37 also blocked the binding of antisera to -zein₁ in competition assays. Subsequently, the shorter 6-mer (peptide 82) and 12-mer (peptide 80) versions of peptide 37 were synthesized, and both reacted with anti-peptide 37 serum and also with each of the three anti--zein₁ sera. In these reactions and in competition assays, the reactivity and the blocking ability increased in proportion to the length of the peptide. Based on these data, it was concluded that the repeat region of -zein₁ is the site of one or more continuous immunodominant epitopes. The data also suggest that the repeat region is exposed on the surface of the folded protein and probably occur as a mobile, random coil.     

Partial mispairing and crossing-over between β0 and δ genes as the origin of the δ β0 thalassemia gene

Summary Two double heterozygous ⁰/⁰ thalassemic sibs of Mexican descent were studied. The father had a ⁰/⁰ genotype, while the mother, one sib and several maternal relatives were ⁰/⁰ heterozygotes. Parental consanguinity and an apparently low frequency of thalassemia among Mexicans suggested a possible common origin of both ⁰ and ⁰ genes. A hypothesis to explain such a possibility is proposed on the basis of a partial mispairing between ⁰ and genes followed by a crossing-over which would results in a ⁰ recombinant gene. This hypothesis could also be extended to explain the 22 gluala, 22 alaglu and 116 arghis Hb variants as recombinants from double crossing-over between and mispaired genes for which the name interstitial-Lepore is proposed.     

Produktivität und Energiegehalte von Gefä\pflanzen im Adventdalen (Spitzbergen)

Zusammenfassung Im Sommer 1973 wurden im Adventdalen/Spitzbergen (=78°15 N, =17° E bis 15°30 E) pflanzenökologische Untersuchungen gemacht. Im einzelnen wurden während 13 Tagen Temperaturen und Strahlung gemessen. Ferner wurden Pflanzen und Pflanzengesellschaften nach der Erntemethode auf ihre Biomasse und Produktivität untersucht. Der Kaloriengehalt der Pflanzen wurde später im Labor ermittelt.Gegenüber anderen arktischen Gebieten ergaben sich höhere Produktivitätswerte, vor allem für gräser und grasartige Pflanzen. Dies ist zurückzuführen auf die klimatische Sonderstellung des Untersuchungsgebietes.

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Summary In the summer of 1973 in Adventdalen, spitzbergen (=78°15 lat., =17° to 15°30 long.) ecological studies of vascular plants were done. In particular, temperatures and radiation were measured over a 13-day period. In addition, plants and groups of plants were investigated according to the harvest method with respect to their biomasses and productivity. The caloric content of the plants was subsequently determined in the laboratory.In relation to other arctic areas, the area under study yielded higher productivity values, especially for grasses and grasslike plants. This is attributed to the special climatic position of the area.

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Unterstützt durch die Deutsche Forschungsgemeinschaft.     

Determination of 3J(H infi supN,C infi sup′ ) coupling constants in proteins with the C′-FIDS method

Summary We introduce the C-FIDS-¹H,¹⁵N-HSQC experiment, a new method for the determination of ³J(H _infi ^supN ,C _infi ^sup ) coupling constants in proteins, yielding information about the torsional angle . It relies on the ¹H,¹⁵N-HSQC or HNCO experiment, two of the the most sensitive heteronuclear correlation experiments for isotopically labeled proteins. A set of three ¹H,¹⁵N-HSQC or HNCO spectra are recorded: a reference experiment in which the carbonyl spins are decoupled during t₁ and t₂, a second experiment in which they are decoupled exclusively during t₁ and a third one in which they are coupled in t₁ as well as t₂. The last experiment yields an E.COSY-type pattern from which the ²J(H _infi ^supN ,C _infi-1 ^sup ) and ¹J(N_i,C _infi-1 ^sup ) coupling constants can be extracted. By comparison of the coupled multiplet (obtained from the second experiment) with the decoupled multiplet (obtained from the first experiment) convoluted with the ²J(H _infi ^supN ,C _infi-1 ^sup ) coupling, the ³J(H _infi ^supN ,C _infi ^sup ) coupling can be found in a one-parameter fitting procedure. The method is demonstrated for the protein rhodniin, containing 103 amino acids. Systematic errors due to differential relaxation are small for ⁿJ(H^N,C) couplings in biomacromolecules of the size currently under NMR spectroscopic investigation.     

Feeding in the rotifer Brachionus calyciflorus

Summary The laboratory feeding behavior of Brachionus calyciflorus varies depending upon the type of food cell available in suspension. When feeding on the yeast Rhodotorula glutinis, rotifers show a continuous increase in ingestion with increased cell density between 0.01 and 1000 g dry weight ml^-1. Effective clearance rates drop from ca. 50 l animal^-1 h^-1 to less than 0.5 l animal^-1 h^-1 over this food density range. When feeding on Englena gracilis, B. calyciflorus ingestion rates are constant between 1.0 and 100 g ml^-1 of available food, averaging close to 25 ng animal^-1 h^-1. The decrease in clearance rate is more striking than with R. glutinis, dropping from 45 l animal^-1 h^-1 at 0.1 g ml^-1 to 0.13 l animal^-1 h^-1 at 100 g ml^-1. Differences between the patterns obtained with the two food types indicate fundamental dissimilarities in the feeding behavior of this rotifer species when presented with these different foods.     

Comparative residual toxicities of pesticides to the predator Agistemus industani (Acari: Stigmaeidae) on citrus in Florida

Residual toxicities of registered and selected experimental pesticides used on citrus against Agistemus industani Gonzalez (Acari: Stigmaeidae) were compared. Pesticides considered highly toxic to A. industani were: abamectin 0.15 EC at 731ml/ha+FC 435-66 petroleum oil at 46.8l/ha, pyridaben 75WP at 469g/ha, ethion 4EC at 7.01l/ha+FC 435-66 petroleum oil at 46.8l/ha, propargite 6.55 EC at 3.51l/ha, chlorfenapyr 2SC at 1.46l/ha applied alone or in combination with FC 435-66 petroleum oil at 46.8l/ha, sulphur 80DF at 16.81kg/ha, dicofol 4EC at 7.01l/ha, fenbutatin oxide 50WP at 2.24kg/ha, benomyl 50WP at 2.24kg/ha, benomyl 50WP at 1.68kg/ha+ferbam 76 GF at 5.60kg/ha, ferbam 76GF at 11.21kg/ha, neem oil 90EC at 46.8l/ha, and copper hydroxide DF (40% metallic copper) at 4.48kg metallic copper/ha+FC 435-66 petroleum oil at 46.8l/ha. Pesticides that were moderately to slightly toxic included: copper sulphate 98% at 4.48kg metallic copper/ha+FC 435-66 petroleum oil at 46.8l/ha, fenbuconazole 2F at 280ml/ha+FC 435-66 petroleum oil at 46.8l/ha, FC 435-66 petroleum oil applied alone at 46.8l/ha or 23.4l/ha, and diflubenzuron 25WP at 1.40kg/ha. Pesticides that were non-toxic included: fenbuconazole 2F at 585ml/ha, malathion 57EC at 5.85l/ha, FC 435-66 petroleum oil at 46.8l/ha, carbaryl 80S at 3.36kg/ha, chlorpyrifos 4EC at 4.68l/ha, and formetanate 92SP at 1.12kg/ha. Understanding the toxic effects of field weathered pesticides against key predacious mite species is important for effective IPM. The results of this study provide a comparison of direct and indirect toxic effects of various pesticides to A. industani under field conditions.