Investigacion preliminar de la accion inhibitoria in vitro de los antibioticos frente a las algas del genero Prototheca

Resumen Se investigó la posible acción inhibitoria in vitro de antibióticos en disco sobre algas microscópicas, potencialmente patógenas para el hombre, del Género Prototheca y la especie P. wickerhamii.Se utilizó el método de disco-placa en medio de Agar de Saboureaud.Resultaron como inhibidores in vitro: Amikacina, Colistina, Dibekacina, Framicetina, Gentamicina, Kanamicina, Lividomicina, Neomicina, Polimixina, Paromomicina, Ribostamicina, Sisomicina y Tobramicina.Se destaca el interés del estudio de sensibilidad a estas drogas ante un caso de Protothecosis humana.

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We investigated the possible inhibitory action in vitro by antibiotic containing discs against microscopic alga that are potential human pathogens of the genus Prototheca especially P. wickerhamii.The results indicated that inhibitors in vitro included amicacin, colistin, dibecacin, framicetin, gentamycin, kanamycin, lividomycin, neomycin, polymyxin, paromomycin, ribostamycin, sisomycin and tobramycin.We emphasize the interest in the effectiveness at these drugs in a case of human protothecosis.

     

Comparative study on the chloroplast,mitochondrial and nuclear genome differentiation in two cultivated rice species,Oryza sativa and O. glaberrima,by RFLP analyses

Summary Restriction fragment length polymorphisms of chloroplast (ct), mitochondrial (mt) and nuclear DNA were investigated using eight cultivars of Oryza sativa and two cultivars of O. glaberrima. Relative variability in the nuclear and cytoplasmic genomes was estimated by a common measure, genetic distance. Based on the average genetic distances among ten cultivars for each genome, the evolutionary variabilities of the mitochondrial and nuclear genomes were found to be almost the same, whereas the variability of the chloroplast genome was less than half that of the other two genomes. Cluster analyses on ct and mt DNA variations revealed that chloroplast and mitochondrial genomes were conservative within a taxon and that their differentiations were well-paralleled with respect to each other. For nuclear DNA variation, an array of different degrees of differentiation was observed in O. sativa, in contrast with little variation in O. glaberrima. As a whole, differentiation between O. sativa and O. glaberrima was clearly observed in all three genomes. In O. sativa, no notable difference was found between the cultivars Japonica and Javanica, whereas a large differentiation was noticed between Japonica (including Javanica) and Indica. In all three genomes, the average genetic distances within Indica were much larger than those within Japonica (including Javanica), and almost similar between Japonica (including Javanica) and Indica. These facts indicate that differentiation in O. sativa was due mainly to Indica.     

The role of frequency-dependent selection in the outcome of experimental populations in evolution

In February 1978, in Puerto Montt (Chile) the palearctic species Drosophila subobscura was detected. The expansion of the species in this country has been very rapid, and now it is found over a distance of at least 2000 km North-South. The newly established populations are very flourishing and show a high degree of inversion chromosomal polymorphism. On the basis of the chromosomal arrangements present, an hypothesis can be formulated about the origin and characteristics of the founder group. Possibly, the founders came from Eastern or South Eastern Spain and formed a group of 10 or more individuals. The colonization of D. subobscura in Chile seems to follow the model of expansion of a cosmopolitan species, passively transported by man rather than the more active expansion of colonizers less tied to human activity, envisaged in Carson's models of colonization processes. The high level of chromosomal polymorphism observed in the populations of D. subobscura in Chile, coincides with this interpretation.This work has been supported by a grant from the Programa de Cooperación con Iberoamérica. Ministerio de Universidades e Investigación. Spain, by the Comisión de Investigación de la Universidad de Chile (Proyecto B-027-794) and Proyecto PNUD/UNESCO (RLA 78/024).     

Polysaccharides of diatoms occurring in Lake Baikal

Polysaccharide composition of neutral, acid- and alkali-soluble fractions of the diatoms Stephanodiscus meyerii Genkal et Popovsk and Aulacoseira baicalensis (K. Meyer) Simonsen of Lake Baikal has been studied. Neutral polysaccharides were represented by chrysolaminarans (13;16--D-glucans). The chrysolaminaran from S. meyerii consists of the high- and low-molecular-weight fractions (40 and 2–5 kDa, respectively) and contains a large number of -16-bound glucose residues. The chrysolaminaran from A. baicalensis is a low-molecular-weight 13;16--D-glucan containing a small number of -16-bonds, with mannitol being attached to the reducing unit of its chain. Acid- and alkali-soluble polysaccharide fractions are practically absent in S. meyerii. The alkali-soluble fraction from A. baicalensis is a low-molecular-weight (2-kDa) glycoprotein, the carbohydrate moiety of which is represented by a heteropolysaccharide.Translated from Prikladnaya Biokhimiya i Mikrobiologiya, Vol. 41, No. 2, 2005, pp. 213–219.Original Russian Text Copyright © 2005 by Alekseeva, Shevchenko, Kusaykin, Ponomorenko, Isakov, Zvyagintseva, Likhoshvai.     

Shift in the behaviours regulating monogyny is associated with highgenetic differentiation in the queenless ant Diacamma ceylonense

Summary In the queenless ant genus Diacamma, one mated worker (called gamergate) maintains reproductive mono-poly in a colony by mutilating newly emerged workers. However, in several populations from south India, referred to as nilgiri, gamergates do not mutilate their nestmates but monopolize reproduction using dominance interactions . Various lines of evidence indicate that nilgiri populations are closely related to the neighboring species D. ceylonense. To determine whether this important behavioural difference between nilgiri and D. ceylonense is associated with signi-ficant genetic differentiation, we have used microsatellite and mitochondrial markers to examine genetic variation within and between nilgiri and D. ceylonense. We found a very high genetic differentiation between the two forms, which suggests a lack of gene flow. There was an unexpected pattern of mitochondrial variation, because all nilgiri populations show identical or very closely related COII sequences except one population with a very different haplotype. This divergent haplotype is genetically much more distant from the other nilgiri haplotypes than are D. ceylonense haplotypes. This pattern is not observed at the nuclear level, which suggests that introgression of mitochondrial DNA probably occurred in some nilgiri populations.     

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.     

DDT concentrations in surficial sediments of three estuarine systems in Portugal

Levels of p,p-DDT and its metabolites in surficial sediments of Tagus and Sado Estuary and lagoon Ria Formosa varied one or two orders of magnitude. In general, p,-DDE and p,-DDD were the dominant metabolites and p,-DDT was a minor component. While concentrations of p,-DDT, p,-DDD and p,-DDE were hardly related to loss on ignition, concentrations of total DDT (tDDT) in surficial sediments of each studied system were positively correlated to that parameter. Higher contaminated samples were excluded from these relationships: a few sediment samples from the Tagus outlet channel, most of the sediments from the upper Sado Estuary, and some particulate matter samples collected in sediment traps in the adjoining area to the Ria Formosa. Concentration of tDDT appears, thus, to be related to sedimentary organic matter of these estuarine systems except near the actual sources of pollution. On the basis of the relationship slopes, one may conclude that lower Tagus Estuary is more contaminated than Ria Formosa and lower Sado Estuary.     

Diatom communities of acidic mountain streams in Poland

A comparison has been made of the species composition of diatom communities developing in acidic Polish mountain streams which flow over calcium-poor substrates: sandstones in the Silesian Beskid (section of the Western Carpathians), the witokrzyskie Mts, and over granite in the Karkonosze range (in the Sudetic Mts). The number of taxa and diversity of the diatom assemblages decreased along a decreasing pH gradient. The correlation between pH and the number of taxa was positive and significant (r ² = 0.69, p < 0.005). A small number of species (< 20) and low diversity were found in the communities developing in strongly acidic streams such as in the witokrzyskie Mts with pH 4.1–5.2, and in the Silesian Beskid with pH 3.5–4.0. In the stream of the Karkonosze Mts, with pH 5.2–6.0, the communities were characterized by their greater number of species and higher diversity.Acidobiontic and acidophilous diatoms were generally dominant. The pH-indiferent forms were less abundant, and their proportion increased above pH 5.0. Eunotia exigua, E. paludosa var. trinacria, E. tenella and Pinnularia subcapitata dominated in streams with the lowest pH, while E. exigua, E. sudetica and Achnanthes kryophila predominated in a stream with water pH above 5.2. Eunotia exigua, a common acidobiontic species was present in all the examined communities, and was a strong dominant in waters of pH 5.0. A corresponding decrease in abundance of E. exigua was observed with an increase in pH.     

A novel wheat alpha-amylase gene (alpha-Amy3)

Summary A genomic clone of a wheat -amylase gene (Amy3/33) was identified, on the basis of hybridisation properties, as different from -Amy1 and -Amy2 genes which had been characterised previously. The nucleotide sequence revealed that this gene has the normal sequence motifs of an active gene and an open reading frame interrupted by two introns. The protein sequence encoded by this open reading frame is recognisably similar to that of -amylase from the -Amy1 and -Amy2 genes and there is high sequence homology in all three proteins at the putative active sites and Ca⁺⁺ binding region. In addition, the introns are at positions equivalent to the position of introns in the -Amy1 and -Amy2 genes. However, the sequence was less similar to -Amy1 and -Amy2 than these are to each other. Southern blot analysis showed that the Amy3/33 DNA is one of a small multigene family carried on a different chromosome (group 5) from either the -Amy1 or -Amy2 genes. A further difference from the -Amy1 and -Amy2 genes was the pattern of expression. Amy3/33 was expressed only in immature grains and, unlike the -Amy1 and -Amy2 genes, not at all in germinating aleurones. These data suggested therefore that this gene represents a third type of -amylase gene, not described before, which shares a common evolutionary ancestor with the -Amy1 and -Amy2 genes.     

Identification of incompatibility alleles in the tetraploid species sour cherry

The incompatibility genetics of sour cherry (Prunus cerasus), an allotetraploid species thought to be derived from sweet cherry (diploid) and ground cherry (tetraploid), were investigated by test crossing and by analysis of stylar ribonucleases which are known to be the products of incompatibility alleles in sweet cherry. Stylar extracts of 36 accessions of sour cherry were separated electrophoretically and stained for ribonuclease activity. The zymograms of most accessions showed three bands, some two or four. Of the ten bands seen, six co-migrated with bands that in sweet cherry are attributed to the incompatibility alleles S ₁ , S ₃ , S ₄ , S _6, S ₉ and S ₁₃ . aanski Rubin, Erdi Botermo B, Koro and Ujfehertoi Furto, which showed bands apparently corresponding to S ₁ and S ₄ , were test pollinated with the sweet cherry Merton Late (S ₁ S ₄ ). Monitoring pollen tube growth, and, in one case, fruit set, showed that these crosses were incompatible and that the four sour cherries indeed have the alleles S ₁ and S ₄ . Likewise, test pollination of Marasca Piemonte, Marasca Savena and Morello, Dutch with Noble (S ₆ S ₁₃ ) showed that these three sour cherries have the alleles S ₆ and S ₁₃ . S ₁₃ was very frequent in sour cherry cultivars, but is rare in sweet cherry cultivars, whereas with S ₃ the situation is reversed. It was suggested that the other four bands are derived from ground cherry and one of these, provisionally attributed to S _B , occurred frequently in a small set of ground cherry accessions surveyed. Analysing some progenies from sour by sweet crosses by S allele-specific PCR and monitoring the success of some sweet by sour crosses were informative. They indicated mostly disomic inheritance, with sweet cherry S alleles belonging to one locus and, presumably, the ground cherry alleles to the other, and helped clarify the genomic arrangement of the alleles and the interactions in heteroallelic pollen.Communicated by H.F. Linskens     

The influence of prey hardness on Daphnia's selectivity for large prey

Two comparable methods were used to study the feeding of four species of Daphnia on large spherical particles which differed in size and hardness. The first method used gut analysis to estimate the selectivities of daphnids feeding in a broad size range of a single particle type, including polystyrene beads (4–60 µm diameter) in the laboratory and Eudorina colonies (10–90 µm) in the field. In the second method, Daphnia of different sizes fed in a mixture of 6.5 µm Chlamydomonas and one of eight test particles. Smaller daphnids were less effective in feeding on large test particles. Nonlinear regression was therefore used to estimate the Daphnia body size at which the clearance rate on a test particle was reduced to 50% of that for Chlamydomonas. The results of both methods show that prey size and hardness are both very important in determining daphnid feeding selectivity. For a given particle size, soft algae (naked and gelatinous flagellates) are more readily ingested than hard algae (diatoms and dinoflagellates), and hard algae are more readily ingested than polystyrene beads. Daphnia can feed effectively on algae that are 2–5 times larger than the largest ingestible bead.     

Transverse relaxation optimised spin-state selective NMR experiments for measurement of residual dipolar couplings

Three transverse relaxation optimised NMR experiments (TROSY) for the measurement of scalar and dipolar couplings suitable for proteins dissolved in aqueous iso- and anisotropic solutions are described. The triple-spin-state-selective experiments yield couplings between ¹H^N-¹³C, ¹⁵N-¹³C, ¹H^N-¹³C _i–1, ¹⁵N-¹³C _i–1, ¹H^N-¹³C_i–1, ¹⁵N-¹³C_i–1, and ¹³C_i–1-¹³C _i–1 without introducing nonessential spectral crowding compared with an ordinary two-dimensional ¹⁵N-¹H correlation spectrum and without requiring explicit knowledge of carbon assignments. This set of /-J-TROSY experiments is most useful for perdeuterated proteins in studies of structure–activity relationships by NMR to observe, in addition to epitopes for ligands, also conformational changes induced by binding of ligands.     

On the phytochrome phototransformation kinetics in mustard seedlings

Summary The in vivo phototransformation kinetics of mustard hook and cotyledon phytochrome exhibit a deviation from a single first order curve, quite similar to that for pumpkin hooks as reported in a previous paper (Boisard, Marmé and Schäfer, 1971). The P _frP_rkinetics can be characterized by the ratios _fr, ^I · P _fr ^I / _fr, ^II · P _fr, ^II and where P _fr ^I and P _fr ^II are two populations of phytochrome molecules which convert to P _rwith a first order half-life of and . These ratios depend on the length of time of etiolation. The ratio _fr, ^I · P _fr ^I / _fr, ^II · P _fr, ^II is independent of the amount of total P _frpresent at the beginning of the P _frP_rphototransformation after a non-saturating dose of red light. The half-lives of the two populations, however, depend on the concentration of total P _frinitially present. P _frP_rphototransformation kinetics with different light intensities show that reciprocity holds.     

The origin of Q-independent derivatives of phage lambda

Summary qsr (Q-independent) phages are characterised by the replacement of the region of the genome that contains Q, S, R, and the late gene promoter, P_R, with host-derived DNA that codes for functions analogous to those deleted. Restriction endonuclease analysis and DNA/DNA hybridisation methods have been used to show that p4 and qin A 3, two such Q-independent phages, are the product of recombination between and a defective lambdoid prophage (the qsr prophage) located at an as yet unidentified site in the E. coli K 12 chromosome. The qsr prophage is distinct from the defective lambdoid prophage Rac (Kaiser and Murray 1979). In the E. coli K 12 strain AB1157 from which qsr phages cannot be generated, the qsr prophage has suffered an internal deletion. That the qsr prophage appears not to carry a full complement of essential late genes suggests one explanation for its apparently defective nature.     

Microbiology of the fermentation of ‘iru pete’ and ‘iru woro’ obtained from local producers

Summary The microorganisms responsible for the fermentation of iru, obtained from local producers, were isolated and identified. Only bacteria were involved in the fermentation; the species areMicrococcus luteus, Staphylococcus aureus, Bacillus subtilis, Lactobacillus plantarum, Citrobacter freundii, Lactobacillus salivarius andStreptococcus pyogenes. Microbial population, temperature, pH and moisture content increased with increase in period of fermentation. A progressive in titratable acidity accompanied the fermentation.

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Resumen Se aislaron e identificaron los microorganismos responsables de la fermentación de iru obtenido de productores locales. En el proceso de fermentación unicamente estaban implicadas bacterias que se identificaron como:Micrococcus luteus, Staphylococcus aureus, Bacillus subtilis, Lactobacillus plantarum, Citrobacter freundii, Lactobacillus salivarius yStreptococcus pyogenes. La población microbiana, la temperatura, el pH y el contenido en humedad se incrementaron al aumentar el periodo de fermentación. Se observó un decremento progresivo del título de acidez a lo largo de la fermentación.

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Résumé Les microorganismes responsables de la fermentation des iru obtenus de producteurs locaux ont été isolés et identifiés. Seules des bactéries sont impliquées dans la fermentation. Les espèces sontMicrococcus luteus, Staphylococcus aureus, Bacillus subtilis, Lactobacillus plantarum, Citrobacter freundii, Lactobacillus salivarius etStreptococcus pyogenes. La population microbienne, la température, le pH et la teneur en eau agumentent avec l'augmentation du temps de fermentation. Une baisse progressive de l'acidité titrable accompagne la fermentation.

     

Haploid production in durum wheat by the interaction of Aegilops kotschyi cytoplasm and 1BL/1RS chromosomal interchange

The present study describes the development of an alloplasmic haploid-inducer in durum wheat cv Cando. This cultivar possesses the homozygous wheat-rye translocation 1BL/1RS from the 6x-wheat cv Veery. The nucleus of 4x-Cando-Veery 1BL/1RS was introduced into Aegilops kotschyi cytoplasm by initially using (kotschyi)-Salmon as the maternal parent. In the cross of this alloplasmic durum line with Cando-Veery 1BL/1RS, which was used as the recurrent pollen parent, haploids (n=14) were produced. The frequency of haploids increased from 5.7% in the F₁ generation to 14% in the BC₁ generation. The presence of rye chromosome arm 1RS and the concomitant loss of 1BS in (kotschyi)-Cando-Veery 1BL/1RS are necessary for haploid induction. Proposals are made which may enable the use of haploids produced by nucleo-cytoplasmic interactions in future wheat breeding programs.     

Glycogen phosphorylase ‘b’ in Dictyostelium: stability and endogenous phosphorylation

Summary The slime mold Dictyostelium discoideum has two forms of the enzyme glycogen phosphorylase. The inactive phosphorylase b form requires 5 AMP for activity and is present in early development. The active phosphorylase a form is 5 AMP independent and occurs during later development. We here show that the 92 kd b enzyme subunit exists either as a singlet or a doublet upon SDS-PAGE, depending on the method of sample extraction. In the presence of exogenously added Mn²⁺ and ATP, the phosphorylase b shows apparent conversion into a 5 AMP independent form as measured by enzyme activity. In addition, Mn²⁺ and ATP also support an in vitro phosphorylation of the 92 kd phosphorylase b subunit. We also demonstrate phosphorylation of the b enzyme subunit in vivo by ³²-P incorporation into the enzyme protein. A protein kinase responsible for the observed in vitro phosphorylation of the phosphorylase b subunit is characterized.     

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.     

Fromβ-lactams toα- andβ-amino acid derived peptides

Summary The potential of-lactams as intermediates for the access to- and-amino acid-derived peptides is shortly reviewed, with major focus on the technologies developed in our group. The two general strategies lie, on one side, in the oxidative ring expansion of 3-hydroxy-lactams toN-carboxy-amino acid anhydrides or Leuch's anhydrides and subsequent coupling with-amino acid esters and, on the other side, in the nucleophilic ring opening ofN-Boc--lactams. Both approaches have been successfully applied to the synthesis of,-diamino acid,-amino--hydroxy acid, polyhydroxylated-amino acid,,-disubstituted-amino acid,-amino acid,-amino--hydroxy acid and,-disubstituted-amino acid derived peptides. Because of the mild reaction conditions needed for the above transformations and the highly stereoselective procedures employed for the construction of the starting-lactam ring, the whole process allows the production of optically pure final products.