Morphometric analysis of Schizachyrium condensatum (Poaceae) and related species

Our aim was to assess the degree of morphological differentiation of a group of taxa of Schizachyrium Nees, which presents similar inflorescences and shares habitat and geographic areas: Schizachyrium bimucronatum, S. condensatum, S. lactiflorum, S. microstachyum subsp. microstachyum, S. microstachyum subsp. elongatum, and S. plumigerum. To accomplish this purpose, 22 exomorphological traits were analyzed using multivariate methods. The results obtained support the identity of Schizachyrium condensatum and related species as independent taxa. In addition, the analysis evidences the reliability of several inflorescence characters, which had not been previously considered in the identification of the different taxa. Based upon the information obtained, a new identification key for these taxa was constructed.     

DNA base composition of species of the genusSaccharomyces

DNA base compositions (GC content) ofSaccharomyces species are reported and discussed. Several amendments of the four groups given by van der Walt are suggested, viz. the transfer ofS. kluyveri to group 1, and ofS. eupagycus, S. cidri, S. montanus, S. microellipsodes andS. florentinus to group 2. The synonomy ofS. amurcae andS. cidri is suggested. The DNA base compositions revealed two possible pairs of sibling species:S. elegans andS. bailii, with a difference in GC content of 4.1%;S. dairensis andS. servazzii with a difference in GC content of ca. 3%.S. mrakii had a GC content of 47.3–48.5% the highest encountered in this genus and similar to that ofKluyveromyces thermotolerans.     

Identification ofEnterococcus sp. from midgut of silkworm based on biochemical and 16S rDNA sequencing analysis

Enterococcus sp. was isolated from the midgut of silkworm against the germination ofNosema bombycis spores. Identification was based on the biochemical characteristics, 16S rDNA sequences analysis and species-specific probes ofEnterococcus spp. The isolated strains fermented sorbitol and arabinose but did not ferment raffinose.Enterococcus sp. was clustered together withEnterococcus mundtii ATCC 43188 and 100% sequence homology was found by 16S rDNA sequences BLAST analysis and constructing the phylogenetic tree. Comparison of the sequences of the 16S rDNA species-specific probes ofEnterococcus spp. with the 16S rDNA sequence of isolate revealed similar segment to the species-specific probe ofE. mundtii. So, we can make conclusion the 16S rDNA segment ofEnterococcus sp. can hybridise with species-specific probe ofE. mundtii. Enterococcus mundtii was detected for the first time in the intestine of silkworm.     

Morphometric and karyological analysis of a population ofSesleria sadleriana Janka in the Biele Karpaty Mountains (Slovakia)

Morphometric and karyological analysis was employed to prove the occurrence of a population ofSesleria sadleriana Janka, at the locality “Vr?atec” in the Biele Karpaty Mts. (Slovakia). Morphological characters of this population were analysed statistically (ANOVA, PCA) and compared with those of a population ofS. sadleriana in Austria (Hainburg an der Donau) and a population ofS. albicans Kit. exSchult. in the Czech Republic (Javo?í?ko). The two populations ofS. sadleriana did not differ from each other in the uppermost leaf length, spike length, glume length, lemma length, awn length of lemma and palea length. On the other hand, they differed significantly in these morphological characters from the population ofS. albicans. Karyological analysis demonstrated that both populations ofS. sadleriana consisted of octoploid plants (2n=8x=56). In addition to chromosome counting, flow cytometry was employed to screen ploidy levels. The experiment demonstrated a positive correlation between the ploidy estimated by chromosome counting and DNA flow cytometry inS. sadleriana andS. albicans. Flow cytometry proved extremely useful for ploidy screening in large numbers of plants. The locality “Vr?atec” represents the northernmost locality ofS. sadleriana known so far.     

Authentication of ATCC strains in theSaccharomyces cerevisiae complex by PCR fingerprinting

Restriction fragment length polymorphisms in the rDNA internal transcribed spacer region (ITS) of 18 yeast strains currently assigned toSaccharomyces cerevisiae, S. pastorianus, andS. bayanus were examined. Primers complementary to the ITS region were used to amplify the ITS rDNA by the polymerase chain reaction (PCR). The products were digested with 10 endonucleases and cluster analysis was used to generate a phenogram from the restriction fragment data. Three strains ofS. cerevisiae (ATCC 10609, 26250, and 66162) exhibited restriction patterns that were different from the type strain but identical to those of theS. bayanus-S. pastorianus cluster. In contrast,S. pastorianus (ATCC 76671) showed restriction profiles that were different from its type strain but were identical to the type strain ofS. cerevisiae (ATCC 18824). These results suggest that the three strains ofS. cerevisiae should be reassigned to eitherS. pastorianus orS. bayanus, and the strain ofS. pastorianus (ATCC 76671) should be reclassified asS. cerevisiae.     

Misapplication of the name stachys nuttallii (Lamiaceae) to a new southeastern species

A recent study of Southeastern species ofStachys points out a problem involving the identity ofS. nuttallii Shuttlew. ex Bentham. Type material ofS. nuttallii is clearly representative of what is commonly known asS. riddellii House.S. riddellii of current authors must now be calledS. nuttallii, S. riddellii becoming a taxonomic synonym. However, no valid names have been uncovered in the literature that can be correctly applied to the species, primarily from the Blue Ridge Mountains, previously known to most botanists as “S. nuttallii.” These plants are described as a new species,Stachys eplingii.     

Detection of the intercellular adhesion loci (ica) in clinicalStaphylococcus aureus strains responsible for hospital acquired auricular infection

In clinicalStaphylococcus aureus strains, the presence of theica genes, biofilm formation and susceptibility to antibiotics are considered important factors of virulence. In this study, 35 strains ofS. aureus, isolated from auricular infection, were investigated for slime production using Congo red agar (CRA) method, antibiotic susceptibility, presence ofmecA gene, and presence oficaA andicaD gene. The results show that 60% of strains weremecA positive when tested by PCR although 25.7% of strains were oxacillin resistant when tested with ATB STAPH. Qualitative slime production ofS. aureus using CRA revealed that 74.3% ofS. aureus were slime producers. All the strains carried theica gene.     

Salix occidentalis Walter,the correct name for S. tristis Aiton (Salicaceae)

In 1788 Walter described three species ofSalix inFlora Caroliniana. HisSalix pentandra is the same asS. caroliniana, andS. alpina andS. occidentalis are the same asS. tristis Aiton (1789).Salix alpina is a later homonym ofS. alpina Scopoli (1722), and must be rejected, butS. occidentalis is the earliest legitimate name forS. tristis and takes precedence.     

Changes in the West Indian operculina (Convolvulaceae)

Two West Indian names inOperculina are briefly discussed and compared with the Old WorldO. turpethum (L.) S. Manso. The conclusions are made thatO. triquetra (Vahl) H. Hallier is a taxonomic synonym ofO. turpethum and thatO. ventricosa (Bertero) Peter may best be considered a variety ofO. turpethum. Typification ofOperculina is discussed, and it is found that, although S. Manso had a mixed concept ofO. turpethum, this species must be the type of the genus.     

Karyological studies in IberianSonchus (Asteraceae: Lactuceae): S. oleraceus, S. microcephalus andS. asper and a general discussion

Chromosome numbers and karyotypes ofSonchus oleraceus (n=16, 2n=32),S. asper (n=9, 2n=18 for subsp.asper and subsp.glaucescens, andS. microcephalus (n=15, 2n=30) are studied; for the first time their idiograms are given. Karyotypes mainly comprise small chromosomes with a degree of asymmetry 2B inS. oleraceus andS. microcephalus and 2A or 2A-2B inS. asper. No karyological differences can be pointed out betweenS. asper subspecies. Data presented support the amphiploid character ofS. oleraceus, and the origin ofS. microcephalus through a dysploid process involving the former taxon. In Iberian representatives of the genus, diagrams of karyotype asymmetry indices show a cluster grouping for species, with the detached exceptions ofS. maritimus andS. crassifolius, which spontaneously hybridize in central Spain. A review of available karyological data shows that in the evolution of the genusSonchus s.l. and relatives, the basic chromosome number x=9 has generally been maintained. Dysploidy is restricted to the seriesS. bourgeaui (n=8) —S. tenerrimus (n=7) andS. oleraceus (n=16) —S. microcephalus (n=15), evolutionarily related and included in the present subgenusSonchus. Polyploidy has been detected in a total of nine taxa ofSonchus and in the generaEmbergeria, Kirkianella, andDendroseris, being more common in peripheral regions of the distribution area of the group. Five diversification centers are proposed for the whole group, of which the Western Mediterranean area, including the Iberian Peninsula, is related to diversification of the present subgenusSonchus.     

Plasticity of Sapium sebiferum seedling growth to light and water resources: Inter- and intraspecific comparisons

Two main hypotheses have been posed to explain the role of phenotypic plasticity in the invasive success of exotic plants: (1) invasive species may be more plastic than resident species in the introduced range, and (2) invasive populations of an exotic species may be more plastic relative to native populations due to evolutionary changes after introduction. To test the first hypothesis, we conducted a greenhouse pot experiment in which seedlings of invasive Sapium sebiferum competed against native Schizachyrium scoparium grasses under different light and water conditions. To test the second hypothesis, we performed an additional greenhouse pot experiment in which seedlings from native and invasive populations of S. sebiferum were grown under environmental treatments analogous to those in the first greenhouse experiment. Compared to native S. scoparium grasses, or to S. sebiferum seedlings from native populations, growth rates of S. sebiferum seedlings from invasive populations were generally higher. When they were competing with S. scoparium grasses, the greater response of S. sebiferum to light and water conditions reflected different patterns: S. sebiferum seedlings were better able to respond with increased growth in unflooded soils, whereas S. sebiferum had more robust growth in the shaded conditions. No difference in responses to change in water conditions, but a significant difference in responses to variation in light conditions was found between two population types of S. sebiferum. The results of this study suggest that relative to S. scoparium, the greater plasticity of S. sebiferum to variation in light conditions is evolved in the introduced range, while that to variation in water conditions reflects an innate property.     

Life cycle and host range of the gall-forming moth,Meskea horor (Lep.: Thyrididae), and its suitability as a biological control agent forSida acuta andS. rhombifolia (Malvaceae)

The life cycle of the moth,Meskea horor Dyar and its host specificity toSida acuta andS. rhombifolia were investigated. Moths emerge early in the morning and are usually inactive during the day. Feeding by the adults in the field was not observed. However, those in the laboratory fed on flowers ofS. acuta, S. rhombifolia andHibiscus sabdariffa, and drank water or dilute honey solution. Eggs are mainly laid on the underside of leaves. Larvae ofM. horor form galls in the stems ofS. acuta andS. rhombifolia which retard plant growth and flowering. Pupation occurs within the gall. The development time from egg to adult was 192 days and the adults lived for 11 to 14 days. Forty-eight plant species were tested to determine the host range ofM. horor. Adults emerged from seven species of plants in the family Malvaceae and larvae formed galls but died before pupating on a further 17 species.M. horor is considered to have too broad a host range to be used as a biological control agent forS. acuta andS. rhombifolia.     

Ecological impacts of the invasive grass Sorghum halepense on native tallgrass prairie

Invasive plants frequently have competitive advantages over native species. These advantages have been characterized in systems in which the invading species has already become well established. Surprisingly, invader impacts on native communities currently undergoing invasion are lacking from most ecological studies. In this work we document and quantify shifting patterns in plant community structure in a native ecosystem (remnant tallgrass prairie) undergoing invasion by the invasive exotic Sorghum halepense (Johnsongrass). Further, we use manipulative field and greenhouse studies to quantify impacts of potential allelochemicals contained in whole-plant S. halepense leachates on growth of the dominant native grass, Schizachyrium scoparium (Little Bluestem), and tested the inhibitory effects of the potential soil legacy of S. halepense on the native grass in the greenhouse. Plant diversity indices revealed three distinct plant communities within the remnant prairie: a native community, a densely S. halepense invaded area, and a transitional zone between the two. Dominance of the native grass, determined by relative percent cover, significantly declined with increased S. halepense invasion via rhizomatous growth. Annual global positioning system monitoring of the S. halepense invasion front was used to quantify advancement into native prairie, documented at an average rate of 0.45 m year^?1. In the manipulative field and greenhouse studies, native S. scoparium treated with invasive S. halepense leachate had significantly less biomass and fewer inflorescences than control plants. These findings indicate the prolific clonal growth in conjunction with the plant chemistry of S. halepense play a significant role in displacement of the native grass.     

Analysis of chimeric UmuC proteins: identification of regions inSalmonella typhimurium UmuC important for mutagenic activity

UnlikeEscherichia coli, the closely related bacteriumSalmonella typhimurium is relatively unresponsive to the mutagenic effects of DNA-damaging agents. Previous experiments have suggested that these phenotypic differences might result from reduced activity of theS. typhimurium UmuC protein. To investigate this possibility, we have taken advantage of the high degree of homology between the UmuC proteins ofE. coli andS. typhimurium and have constructed a series of plasmid-encoded chimeric proteins. The possibility that the phenotypic differences might be due to differential expression of the respective UmuC proteins was eliminated by constructing chimeric proteins that retained the first 25 N-terminal amino acids of either of the UmuC proteins (and presumably the same translational signals), but substituting the remaining 397 C-terminal amino acids with the corresponding segments from the reciprocal operon. Constructs expressing mostlyE. coli UmuC were moderately proficient for mutagenesis whereas those expressing mostlyS. typhimurium UmuC exhibited much lower frequencies of mutation, indicating that the activity of the UmuC protein ofS. typhimurium is indeed curtailed. The regions responsible for this phenotype were more precisely localized by introducing smaller segments of theS. typhimurium UmuC protein into the UmuC protein ofE. coli. While some regions could be interchanged with few or no phenotypic effects, substitution of residues 212–395 and 396–422 ofE. coli UmuC with those fromS. typhimurium resulted in reduced mutability, while substitution of residues 26–59 caused a dramatic loss of activity. We suggest, therefore, that the primary cause for the poor mutability ofS. typhimurium can be attributed to mutations located within residues 26–59 of theS. typhimurium UmuC protein.     

Biological and ecological studies of the parasitoidChelonus inanitus [Hym.: Braconidae] in Israel

Only one species ofChelonus Panzer,Chelonus inanitus (L.), was found to be widespread in all areas of Israel. The parasitoid was particularly widespread in alfalfa fields but also was present in cotton, sugar beet, artichoke and corn. Spodoptera littoralis (Boisd) andS. exigua (Hbn.) were the main hosts ofC. inanitus although it might develop in other Lepidoptera species. A study of its population showed that adults were present in the spring, summer and autumn but not during the winter. In most cases the population density of the parasitoid appeared to be related to that of the hosts. Parasitism and sex ratio ofC. inanitus in alfalfa fields were studied. The number of males (average of 75%) was higher than that of the females. Percentage of parasitism in larvae ofS. littoralis andS. exigua reached up to 39.8% and 13.5% respectively. The parasitism values in eggs ofS. littoralis were up to 71%.     

Studies in Stryphnodendron (Leguminosae: Mimosoideae) including two new taxa

Stryphnodendron campestre Forero andS. guianense (Aubl.) Benth. ssp.glandulosum Forero are described and illustrated, and notes on the nomenclature ofS. adstringens and on the exclusion ofS. colombianum from the genus are included.     

Reproductive biology and conservation genetics ofSerapias vomerace (Orchidaceae)

Serapias vomeracea is considered to be a particular example of the deceptive strategy of terrestrial orchids. Information on its reproductive biology and population genetic variation is needed to develop conservation strategies. The pollination biology and breeding system were investigated in four populations ofS. vomeracea. Hand-pollination experiments showed thatS. vomeracea is self-compatible. Bagged inflorescence produced no fruits; artificial pollination resulted in 89.7–100% fruit set through induced autogamy, 91.1–100% with geitonogamous, and 89.3–94.4% following xenogamous pollination. Fruit set in the open-pollinated control ranged from 13.4 to 20.9%. We evaluated the spatial genetic structure of 13 populations using five nuclear microsatellite loci. Italian and isle of Corfu populations ofS. vomeracea are characterized by a low mean allele number, ranging from 2.4 to 3.8, by intermediate to high heterozygosity levels, ranging from 0.50 to 0.71, and by frequent deviations from the Hardy-Weinberg equilibrium (9 out 13 populations). Most of theS. vomeracea populations exhibited significant heterozygote excess. The population size reduction is most probably the cause of the low genetic variation observed in the populations ofS. vomeracea. For the genetic conservation and management ofS. vomeracea suitable strategies should be developed based on these data.     

The variation and evolution of selected species of Solanum section Basarthrum (Solanaceae). II

Five taxa ofSolanum sect.Basarthrum were studied in an effort to clarify their taxonomic position and to determine the effective evolutionary mechanisms. Methods included an analysis of chromosome number and behavior, artificial hybridizations and a study of herbarium material. The data suggest thatS. canense andS. suaveolens are closely related and that 5.suaveolens may have been the progenitor ofS. canense. The only successful interspecific cross involving one of these two species was vigorous but highly sterile. Evidence from both morphology and crossing studies indicates a close relationship betweenS. basendopogon andS. caripense. Hybrids between these two species with relatively high fertility through the F₃ generation were secured. The status ofS. basendopogon f.obtusum remains a problem since there is but one collection of the typical form. The placement ofS. sanctae-marthae in sect.Basarthrum is considered problematic. Virtually none of 170 interspecific crosses with this species were successful. Seed size and the presence and size of a seed wing are proposed as useful morphological characters in sect.Basarthrum. There is apparently a correlation between short styles and self-compatibility. All species are diploid (n = 12) and no chromosomal or meiotic aberrations were noted in the species or hybrids. Most of the more than 1,000 interspecific crosses failed. Most of the hybrid fruits bore no seeds or seeds which did not germinate. The primary barriers separating species are considered to be strong prefertilization isolating mechanisms and ecogeographic factors.