Guaianolides and heliangolides from Hymenopappus newberryi

The aerial parts of Hymenopappus newberryi afforded two heliangolides, two thymol derivatives, as well as two new guaianolides and a trans, trans-germacranolide closely related to hiyodorilactone A. Furthermore, the ent-kaurene derivative abbeokutone was present. These results are of chemotaxonomic interest.     

Millerenolides,sesquiterpene lactones from Milleria quinqueflora

The aerial parts of Milleria quinqueflora afforded 17 new germacranolides (five melampolides and 12 millerenolides), two ent-pimarene and two ent-kaurene derivatives as well as two alicyclic diterpenes and a galactoside. The structures were elucidated by NMR spectroscopy. The chemotaxonomic situation is discussed.     

N-Coronafacoyl-L-isoleucine and N-coronafacoyl-L-alloisoleucine,potential biosynthetic intermediates of the phytotoxin coronatine

Two new naturally-occurring analogues of the phytotoxin coronatine have been isolated from liquid cultures of Pseudomonas syringae pv. glycinea. These have been identified as N-coronafacoyl-L-isoleucine and N-coronafacoyl-L-alloisoleucine by mass spectrometry and by studies of the products of acid hydrolysis of the two compounds. The compounds were purified as a mixture of ca 2:1 composition, but the two parent components were not preparatively separated. The possible significance of the two compounds, to the biosynthesis of coronatine, is discussed.     

Rhodopirellula lusitana sp. nov. and Rhodopirellula rubra sp. nov., isolated from the surface of macroalgae

Twenty two strains of Rhodopirellula were isolated from the epiphytic community of several marine macroalgae and separated into two groups, designated as group B and group C. In this study, we characterized these groups as two novel species belonging to the genus Rhodopirellula.     

Protoglobigérines et Oberhauserellidae (Foraminifères) du Bajocien-Bathonien du Jura méridional, France

A detailed investigation of the Bajocian-Bathonian protoglobigerinids and other globigerina-like foraminifera of the Southern Jura Mountains reveals an unsuspected diversity, with seven species of Conoglobigerinidae and two species of Oberhauserellidae. The discovery of two umbilical apertures in Oberhauserella as well as in some Conoglobigerina questions the generic taxonomy and raises the problem of comparisons with literature. For these reasons, five new species have been proposed: Oberhauserellaparocula and O. aff. parocula (with two apertures), “Conoglobigerina”trilocula and “C”.biapertura (with two apertures), C.solaperta and C.pupa. We demonstrate that Globuligerinabalakhmatovae (Morozova, 1961) (here emended) has a small globuligerine aperture as well as G. aff. dagestanica (Morozova, 1961). Despite the different taxonomic concepts, the Southern Jura Mountains associations, that are typical of the epicontinental platform, most closely match those of the Dagestan in the Caucasus. They clearly differ from those of the oceanic Tethys.     

Steroidal alkaloids of Marsdenia rostrata

Some of the main constituents of Marsdenia rostrata, originating from two localities, were isolated and identified. The sample from the Toonumbar State Forest in northern New South Wales contains the known alkaloid anabasine and two new steroidal ester alkaloids, rostratine and dihydrorostratine. They were identified as O-acetyl-O-nicotinoylsarcostin and O-acetyl-O-nicotinoyldihydrosarcostin. The sample from the South Coast of N.S.W. yielded the two new ester alkaloids and a number of neutral polyhydroxy pregnane aglycones, one of which has been identified as metaplexigenin, but there was no anabasine.     

The light-harvesting chlorophyll a/b · protein complex of the green alga Acetabularia mediterranea isolation and characterization of two subunits

In the green alga Acetabularia mediterranea a light-harvesting chlorophyll a/b · protein complex of 67 000 daltons has been found which contains two polypeptide chains of 21 500 and 23 000 daltons. These two polypeptides were isolated on a preparative scale and were further characterized by several different methods. Both polypeptides proved to be very similar. While their amino acid and sugar compositions as well as their immunochemical properties were almost identical the tryptic peptides and the cyanogen bromide fragments of the two polypeptides revealed minor but significant differences. The 67 000-dalton chlorophyll a/b · protein complex and its two polypeptide components were compared to the light-harvesting chlorophyll a/b · protein of higher plants.     

Enhanced antibacterial activity of an attacin-coleoptericin hybrid protein fused with a helical linker

Previously, we isolated and characterized attacin from Spodoptera exigua and a coleoptericin-like protein from Protaetia brevitarsis seulensis. In this study, we fused these two genes encoding antimicrobial proteins to obtain a hybrid protein with enhanced antimicrobial activity. To fuse the two antimicrobial proteins, we employed helical and non-helical linker sequences that function as inter-domain linkers in proteins. We used the Gly–Gly–Gly–Gly–Ser peptide as a non-helical linker. The hybrid protein produced using this linker showed less antimicrobial activity against Escherichia coli, Bacillus subtilis, Burkholderia glumae, Pseudomonas corrugate, and Erwinia rhapontici than either of the two parental antimicrobial proteins. In addition, the MIC value of the hybrid protein was 23.1 μM, which indicates poor activity against E. coli. When we used three Glu–Ala–Ala–Ala–Lys (EAAAK) peptide sequences as a helical linker to fuse the two proteins, the resultant hybrid protein had much higher antimicrobial activity than the parental antimicrobial proteins. In particular, this hybrid protein had strong antimicrobial activity against P. corrugate. These results indicate that the EAAAK motif can be used to effectively separate two antimicrobial proteins and produce a hybrid protein with more antimicrobial activity than either of the parent proteins.     

Tricyclic sesquiterpenes and further diterpenes from Espeletiopsis species

The investigation of five Espeletiopsis and two Coespeletia species afforded, in addition to numerous known compounds, two new kaurene derivatives 19-acetoxy-ent-kaurene and 17-oxo-ent-kaur- 15-en-19-oic acid, as well as two new tricyclic sesquiterpenes, one being the previously reported oxidation product of copaborneol and the second one the 5-oxo derivative of silphiperfol-6-ene. The structures were elucidated by NMR studies and by chemical transformations. The chemotaxonomic situation is discussed briefly.     

Molecular phylogeny of the paper wasp subgenus Polistes (Polistella) Ashmead, 1904 (Hymenoptera: Vespidae: Polistinae) from Vietnam

This study provides the first molecular phylogeny of the social wasp subgenus Polistella (Hymenoptera: Vespidae: Polistes) from Vietnam. Fragments of the mitochondrial COI and 16S rRNA genes were used to reconstruct the phylogenetic trees among 38 Polistes species plus two out-group species (Vespa soror du Buysson and Ropalidia fasciata (Fabricius)). Our results support the existence of several species-groups, including two that are congruent with the previous stigma and Stenopolistes groups defined on the basis of morphology. Moreover, we recovered a clade including the stigma group and the two species P. humilis and P. variabilis that was sister to all other species of Polistella. However, the results also challenged the definition of other groups of Polistella based on morphological data, as well as the definition of two species: P. brunus and P. affinis. This first study calls for further analyses including morphological characters to clarify the taxonomy and the classification of the group.     

Temperature effect on affinity chromatography of two lectins from the seeds of Ricinus communis

Specific adsorption capacity of Sepharose 4B in affinity chromatography for two purified galactose-binding lectins, designated as III_L and III_H, from the seed of Ricinus communis (castor bean) was measured from 7 to 24°C. The adsorption coefficients for these two protein fractions as a function of temperature were also obtained. It was found that there is a characteristic transition of adsorption coefficient at 18°C for both lectins. Adsorption coefficients between Sepharose 4B and these two lectins were also expressed in terms of ΔG, ΔH, andΔS. It is suggested that the difference in the temperature dependence of the binding energy of these two lectins may be used for their separation at selected temperature.     

Mg isotopes and Mg/Ca values of coccoliths from cultured specimens of the species Emiliania huxleyi and Gephyrocapsa oceanica

Coccoliths from cultured specimens of two species of coccolithophores (Emiliania huxleyi and Gephyrocapsa oceanica) were sampled during two growth phases (late exponential and stationary), and their Mg isotope values (δ²⁶Mg) as well as Mg/Ca values were measured in order to investigate whether δ²⁶Mg can be used as a temperature proxy. Mg/Ca values were positively related with temperature (~ 0.002 mmol/mol/°C), without statistically significant differences between the two growth phases and the two species. Both species were depleted in heavier Mg isotopes relative to the culture medium, and δ²⁶Mg values were temperature dependent in both growth phases of E. huxleyi, although the δ²⁶Mg values differed in the two growth phases. In G. oceanica, a weak correlation between δ²⁶Mg values and temperature was seen in the late exponential growth phase only, and the δ²⁶Mg values differed between growth phases. The large differences between δ²⁶Mg values as measured in calcite formed during different growth phases indicate that Mg isotopes of coccoliths cannot be simply used as a temperature proxy. Our conclusions are preliminary and more data must be collected in order to fully evaluate the use of Mg isotopes of coccoliths as a temperature proxy.     

Centromere parC of plasmid R1 is curved

The centromere sequence parC of Escherichia coli low-copy-number plasmid R1 consists of two sets of 11 bp iterated sequences. Here we analysed the intrinsic sequence-directed curvature of parC by its migration anomaly in polyacrylamide gels. The 159 bp long parC is strongly curved with anomaly values (k-factors) close to 2. The properties of the parC curvature agree with those of other curved DNA sequences. parC contains two regions of 5-fold repeated iterons separated by 39 bp. We modified 4 bp within this intermediate sequence so that we could analyse the two 5-fold repeated regions independently. The analysis shows that the two repeat regions are not independently curved parts of parC but that the overall curvature is a property of the whole fragment. Since the centromere sequence of an E.coli plasmid as well as eukaryotic centromere sequences show DNA curvature, we speculate that curvature might be a general property of centromeres.     

Evolutionary analysis of circumsporozoite surface protein and merozoite surface protein-1 (CSP and MSP-1) sequences of malaria parasites

Malaria, one of the world''s most common diseases, is caused by the intracellular protozoan parasite known as Plasmodium. In this study, we have determined the evolutionary relationship of two single-copy proteins, circumsporozoite protein (CSP) and merozoite surface protein-1 (MSP-1), among Plasmodium species using various bioinformatics tools and softwares. These two proteins are major blood stage antigens of Plasmodium species. This study demonstrates that the circumsporozoite protein of Plasmodium falciparum shows similarity with Plasmodium cynomolgi and Plasmodium knowlesi. The merozoite surface protein-1 of Plasmodium coatneyi forms a monophyletic group with Plasmodium knowlesi, demonstrating their close relationship and these two species also reveal similarity between the human malaria Plasmodium vivax. This Plasmodium phylogenetic arrangement is evidently crucial to identify shared derived characters as well as particular adaptation of plasmodium species from inside and between monophyletic groups.     

Mitochondrial COI and morphological evidence for host specificity of the black cherry aphids Myzus cerasi (Fabricius, 1775) collected from different cherry tree species in Europe (Hemiptera,Aphididae)

Partial sequences of the mitochondrial COI gene of forty eight European and two Turkish population samples of Myzus cerasi from different winter hosts (Prunus spp.) were subjected to phylogenetic analyses. The analysed M. cerasi samples emerged as paraphyletic relative to a Myzus borealis sample used as an out-group, and formed two major clades in neighbor joining, maximum parsimony, maximum likelihood and Bayesian inference trees, corresponding to subspecies living specifically on Prunus avium and P. cerasus. Multivariate discriminant analysis (method of canonical variates) was applied to find out if morphological variation of samples correlated with mitochondrial COI and host plant information. Mean scores on the first two canonical variables clustered samples fully in accordance with their COI haplotypes and host plants confirming the existence of two morphologically similar winter host - specific subspecies of M. cerasi in Europe. No single morphological character enabled satisfactory discrimination between apterous viviparous females of the two subspecies. A three-character linear discriminant function enabled 92.37% correct identification of apterous viviparous females of M. cerasi cerasi (n = 118) and 93.64% of M. cerasi pruniavium (n = 110). A key for the morphological identification of the two subspecies is presented and their taxonomic status is discussed.     

New Hybrids between Saccharomyces Sensu Stricto Yeast Species Found among Wine and Cider Production Strains

Two yeast isolates, a wine-making yeast first identified as a Mel⁺ strain (ex. S. uvarum) and a cider-making yeast, were characterized for their nuclear and mitochondrial genomes. Electrophoretic karyotyping analyses, restriction fragment length polymorphism maps of PCR-amplified MET2 gene fragments, and the sequence analysis of a part of the two MET2 gene alleles found support the notion that these two strains constitute hybrids between Saccharomyces cerevisiae and Saccharomyces bayanus. The two hybrid strains had completely different restriction patterns of mitochondrial DNA as well as different sequences of the OLI1 gene. The sequence of the OLI1 gene from the wine hybrid strain appeared to be the same as that of the S. cerevisiae gene, whereas the OLI1 gene of the cider hybrid strain is equally divergent from both putative parents, S. bayanus and S. cerevisiae. Some fermentative properties were also examined, and one phenotype was found to reflect the hybrid nature of these two strains. The origin and nature of such hybridization events are discussed.     

Assembly of bacteriophage T4 tail fibers. IV. Subunit composition of tail fibers and fiber precursors

Using a novel purification procedure, the protein composition of the tail fibers of bacteriophage T4 has been determined. Fibers contain four proteins whose molecular weights, as estimated by sodium dodecyl sulfate/acrylamide gel electrophoresis, are 150,000, 125,000, 40,000 and 24,000. The two largest proteins have been previously identified as the products of genes 34 (P34) and 37 (P37), respectively (King and Laemmli, 1971; Ward and Dickson, 1971). The two smaller proteins have now been identified as the products of genes 35 (P35) and 36 (P36), respectively. The products of the two other known phage genes required for fiber assembly, 38 and 57, have been identified as non-structural phage proteins with molecular weights of 26,000 and 10,000, respectively.     

Comparative analysis of the Borrelia garinii genome

Three members of the genus Borrelia (B.burgdorferi, B.garinii, B.afzelii) cause tick-borne borreliosis. Depending on the Borrelia species involved, the borreliosis differs in its clinical symptoms. Comparative genomics opens up a way to elucidate the underlying differences in Borrelia species. We analysed a low redundancy whole-genome shotgun (WGS) assembly of a B.garinii strain isolated from a patient with neuroborreliosis in comparison to the B.burgdorferi genome. This analysis reveals that most of the chromosome is conserved (92.7% identity on DNA as well as on amino acid level) in the two species, and no chromosomal rearrangement or larger insertions/deletions could be observed. Furthermore, two collinear plasmids (lp54 and cp26) seem to belong to the basic genome inventory of Borrelia species. These three collinear parts of the Borrelia genome encode 861 genes, which are orthologous in the two species examined. The majority of the genetic information of the other plasmids of B.burgdorferii is also present in B.garinii although orthology is not easy to define due to a high redundancy of the plasmid fraction. Yet, we did not find counterparts of the B.burgdorferi plasmids lp36 and lp38 or their respective gene repertoire in the B.garinii genome. Thus, phenotypic differences between the two species could be attributable to the presence or absence of these two plasmids as well as to the potentially positively selected genes.     

Partial Characterization of Bacteriocins Produced by Two New Enterococcus faecium Isolated from Human Intestine

This study aimed at characterizing two novel bacteriocin-producing enterococcal strains isolated from human intestine. A total of 200 lactic acid bacteria were isolated from a woman stool sample. Two of them were selected for characterization due to their high antimicrobial activity against five strains of Listeria monocytogenes. The selected bacteria were identified as two different strains of Enterococcus faecium and designated MT 104 and MT 162. The bacteriocins produced by MT 104 and MT 162 were stable at different pH ranging from 2 to 11 and were active after different treatments such as heat, enzymes, detergents, and γ-irradiation. The two isolated strains exhibited some probiotic properties such as survival in simulated gastric fluid and intestinal fluid, lack of expression of bile salt hydrolase or hemolytic activity, adhesion to Caco-2 cells efficiently, and sensitivity to clinical antimicrobial agents. Thus, the two isolated strains of E. faecium could become new probiotic bacteria and their bacteriocins could be used for controlling L. monocytogenes in combination with irradiation for food preservation.