The effect of a rosette-crown fly, Botanophila turcica, on growth,biomass allocation and reproduction of the thistle Carthamus lanatus

Plant growth and reproductive output of the winter annual invasive thistle, Carthamus lanatus was characterised in relation to plant size in three native populations in southern France. The effects of the rosette-crown feeding fly Botanophila turcica on these plant characteristics were assessed by comparing unattacked with naturally attacked plants at each site and by a field experiment. Indirect effects of B. turcica on plant seed production were also compared with direct seed loss caused by a guild of capitulum-feeding insects that incidentally attacked the marked plants at these sites. C. lanatus showed no size or weight requirement for flowering, but larger flowering plants produced less total receptacle surface and less seed production (female reproductive potential) in proportion to plant weight than smaller flowering plants. B. turcica did not select hosts on the basis of size or density. B. turcica reduced plant relative growth rate (RGR) in all situations, but attacked plants compensated fully at two of three sites as attack failed to halt rosette growth. Attacked plants suffered 12 % mortality, and 71 % lower seed production than unattacked plants at the site with the lowest RGR. This corresponded to 9 % lower seed production for the whole thistle population compared to 8.6–19.5 % direct seed loss to capitulum insects across all sites.     

Expression of sialyl Le, sialyl Le, Le and Le glycotopes in secreted human ovarian cyst glycoproteins

Human blood group A, B, H, Ii, Le^a and Le^b antigens and their determinants expressed on ovarian cyst glycoproteins have been studied for over five decades. However, little is known about sialyl Le^x and sialyl Le^a glycotopes, which play essential roles in normal immunity, inflammation, and cancer cell metastasis. Furthermore, Le^x and Le^y were classified as glycotopes of unknown genes. Identification of these Lewis epitopes was hampered by the lack of specific antibodies. In this study, the occurrence of sialyl Le^x, sialyl Le^a, Le^x and Le^y reactivities in cyst glycoproteins was characterized by enzyme-linked immunosorbent assays. The results indicated that most human ovarian cyst glycoproteins carried Le^x (8/25) and/or Le^y (17/25) glycotopes. The expression (epitopes) of the new genes described in previous reports are Le^x and Le^y glycotopes; the reactivities of sialyl Le^x and sialyl Le^a glycotopes in secreted cyst glycoproteins may be affected by the conditions of purification; the relationship between Le^y and human blood group ABH was confirmed; recognition profiles of sialyl Le^x, sialyl Le^a, Le^x and Le^y present in the carbohydrate chains of water-soluble cyst glycoproteins were illustrated; possible attachments of glycotopes to the internal carbohydrate complex of cyst glycoproteins have been reconstructed; proposed biosynthetic pathways for the formation of sialyl Le^a, sialyl Le^x, Le^x, Le^y, ALe^y and BLe^y determinant structures on Type I and Type II core structures of human ovarian cyst glycoproteins are also included in this study.     

DNA sequence-specific ligands. XVII. Synthesis,spectral properties,virological and biochemical studies of fluorescent dimeric bisbenzimidazoles DBA(n)

A series of DNA minor groove binding fluorescent dimeric bisbenzimidazoles DBA(n) bearing linkers of various length were synthesized and their biochemical and antiviral activities were evaluated. Their antiviral activity was assessed in model cell systems infected with human herpes simplex virus (HSV-1) and cytomegalovirus (CMV). Compounds DBA(1) and DBA(7) demonstrated in vitro inhibitory properties towards HSV-1, and DBA(7) completely blocked the viral infection. Compound DBA(11) displayed the in vitro therapeutic activity towards both HSV-1 and CMV. All of the DBA(n) could fluoresce, were well soluble in water, not cytotoxic to a concentration of 240?µM, penetrated well into cell nuclei by binding to DNA and could inhibit topo-I at low micromolecular concentrations.     

Floral Ontogeny in Bourreria (Ehretiaceae, Boraginales)

Gynoecium and fruit ontogeny is studied in eight species of Bourreria (Ehretiaceae, Boraginales). The internal architecture of the bicarpellate ovary results from the development of several secondary septs, i.e., apical, basal, and false septs. Flower and fruit morphology provide additional characters for phylogenetic analyses. Apomorphies of monophyletic Bourreria are the valvate calyx lobes, an extensive disc, and an additional sterile chamber in each endocarpid (i.e., fruit part). The development of transfer cells and endosperm haustoria confirm the systematic placement of Bourreria in the Primarily Woody Boraginales (i.e., Heliotropiaceae, Cordiaceae, and Ehretiaceae including Lennoaceae). However, the precise systematic position of Bourreria within Ehretiaceae cannot be resolved on the basis of the morphological data provided here.     

INHIBITION OF CELL DIVISION BUT NOT NUCLEAR DIVISION BY 1- O -OCTADECYL-2- O -METHYL- Sn -GLYCERO-3-PHOSPHOCHOLINE

1- O -Octadecyl-2- O -methyl-glycero-3-phosphocholine (ET-18-OCH₃) selectively inhibits the growth of cancer cells. Here we show that in some cell types ET-18-OCH₃and liposome-associated ET-18-OCH₃inhibit cell division without concurrent inhibition of nuclear division, leading to multinucleate cell formation, and cell death through apoptosis. Cell cycle analysis revealed that ET-18-OCH₃-treated U-937 cells continued to move through the cell cycle, but many cells were not able to divide and instead accumulated as tetraploid cells or octaploid cells in the G0/G1 phase of the cell cycle. Inhibition of cytokinesis has been shown to be paralleled by activation of U-937 cells, including upregulation of some cell-surface markers, acquisition of phagocytic activity, and secretion of tumor necrosis factor (TNF)-α (Pushkareva et al., 2000). Furthermore, treatment of cells with ET-18-OCH₃results in the accumulation of apoptotic cells in time- and dose-dependent manner. It is possible that inhibition of cytokinesis may be related to cytoskeletal effects.     

A large male hominin cranium from Sterkfontein, South Africa, and the status ofAustralopithecus africanus

Stw 505 is the most complete hominin cranium discovered in Sterkfontein Member 4 since Broom's excavations. It was found in situ in Member 4 breccia in 1989 and is larger, on the whole, than any other cranium from Sterkfontein that has comparable parts. Displacement due to breakage, as well as plastic deformation, has affected Stw 505 in several areas, especially the face and the vault. Diagnosticmorphology is nevertheless abundant in the specimen. In several areas-the distinct anterior pillar, the straight inferior border of the zygoma, the pattern of cresting on the naso-alveolar clivus, the basal aspect of the temporal bone-Stw 505 closely matches the morphology of specimens of Australopithecus africanus and is distinct from other hominins. Some isolated characters overlap with other groups, mainly early Homo and/or A. robustus. However, only the hypodigm of A. africanus can accommodate the entire suite of morphology.In some cases, Stw 505 introduces more variation into the Sterkfontein sample. For example, prominent superciliary eminences occupy the medial portions of the supraorbital region and flow medially into a strongly protruding glabellar mound. These characteristics are probably attributable to sexual dimorphism. In many respects, Stw 505 highlights similarities between A. africanus and early Homo. Comparison with other species suggests that males of A. africanus do not show derived features of A. robustus that are not also present in females, and that cranial differences between A. afarensis and A. africanus have, if anything, been understated.     

Anatomical and ultrastructural study of the secretory cavity development ofCitrus sinensis and Citrus limon: evaluation of schizolysigenous ontogeny

The ontogeny and ultrastructure of secretory oil glands in the fruits of Citrus sinensis and Citrus limon were studied with light and electron microscopy (TEM). Oil glands were initiated by cell division in globular/oval clusters of young meristematic cells under or including also the epidermis. Successively, the central oil cells increased greatly in size by growth and coalescence of one or more vacuoles. Starting from these cells the oil cavity formation and enlargment occurred by schizogenous and lysigenous precesses which overlap one another. The separation of the cell walls, in both Citrus species, was accompanied by strong structural disorganization of the cytoplasm, loss of nuclei, plasmolysis, and followed by autolysis processes. Prior these changes a great quantity of oil droplets filled the cells. In Citrus sinensis this material was formed in the plastids; on the contrary, in Citrus limon oil droplets appeared only in the cytoplasm, and no connection with the plastids was observed. The processes of schizogeny and lysigeny occurred in a centrifugal direction. The peripheral oil chamber cells were so pushed outward and flattened with the progressive expansion of the gland cavity. Also these cells became vacuolated, showed schizogenous processes together with cytoplasm and nuclei breakdown. These cell modifications were preceded by an abundant essential oil synthesis. Electron dense material appeared in the cavity near the boundary cells. Among the cell layers surrounding the cavity, the outer peripheral cells showed very thick walls. These cells, probably, had a protective function, while the inner cells continued, at least in part, to produce and secrete oil compounds. In the two Citrus species the pattern of oil gland development was practically the same, except the different plastid behaviour.     

IN VITRO MORPHOGENESIS OF AMPHIBIAN ERYTHROBLASTS

Non-mammalian vertebrate erythrocytes are flattened nucleated ellipsoids containing marginal bands (MBs) of microtubules that assemble during cellular morphogenesis. Earlier work suggested that pointed erythroid cells containing pointed MBs were intermediate stages in terminal differentiation, rather than aberrant forms, but direct evidence was lacking. Here we report on morphogenesis in individual post-cytokinetic amphibian erythroblasts in culture. Daughter cells remained adjacent in pairs, and developed pointed morphology over 1–2 h in the following sequence: (a) ends opposite the cytokinetic furrow became pointed, producing a spheroidal singly-pointed stage; (b) furrow ends usually became pointed, yielding doubly-pointed cells; (c) furrow-end points disappeared, producing a second singly-pointed stage that was flattening. Over a longer term, the single points sometimes disappeared, yielding a flattened discoid. These observations support the hypothesis that pointed cells are normal intermediates in a biogenetic program in which post-mitotic centrosomes organize MBs while occupying the singly-pointed ends of differentiating erythroblasts.     

The circadian conidiation rhythm inNeurospora crassa

The filamentous fungusNeurospora crassais one of the best organisms for analysing the molecular basis of the circadian rhythm observed in asexual spore formation, conidiation. Many clock mutants in which the circadian conidiation rhythm has different characteristics compared to those in the wild-type strain have been isolated since the early 1970s. With the cloning of one of these clock genes,frq, the molecular basis of the circadian clock inNeurosporahas become gradually clearer. Physiological and pharmacological studies have also contributed to our understanding of the physiological basis of the circadian clock inNeurospora. These studies strongly indicate that the circadian clock is based on or is closely related to a network of metabolic processes for cellular activities. Based on these studies, it may be possible to isolate new types of clock mutants which should contribute to a better understanding of the molecular basis of the circadian clock inNeurospora.     

Adaptive and phylogenetic significance of ontogenetic sequences in Archaeolemur, subfossil lemur from Madagascar

Among the best known of recently extinct Malagasy lemurs is Archaeolemur, which is represented by many hundreds of specimens. The phylogenetic affinities of this taxon are unclear, especially in light of recent preliminary analysis of ancient DNA which does not support its previously accepted close relationship with the living Indridae. We examined the nearly complete skeletons of two adults and one juvenile and other less complete specimens to reconstruct aspects of the ontogeny of Archaeolemur. To compare the development of Archaeolemur to that of living strepsirrhines we collected data on Propithecus verreauxi, Eulemur fulvus, and Lemur catta. Additionally, because Archaeolemur exhibits some morphological convergences with distantly related papionins, we tested for convergence in the developmental patterns of Archaeolemur and Macaca fascicularis. Data include the status of tooth eruption, craniofacial sutural closure, and postcranial epiphyseal fusion, as well as linear measurements. We used discriminant function analysis and other tools to explore ontogenetic similarities and differences. The adaptive and phylogenetic significance of ontogenetic information is discussed. Our analysis shows that Archaeolemur displays a clear strepsirrhine pattern of development with only minor macaque convergences. Among the Strepsirrhini, Archaeolemur is slightly more similar developmentally to E. fulvus and L. catta than to P. verreauxi. Some of the distinctive features of the ontogeny of Archaeolemur may be related to diet, while others bear apparent testimony to a relatively rapid absolute pace of growth and development.     

Mechanisms of antibiotic resistance and tolerance in Streptococcus pneumoniae

Streptococcus pneumoniae is a major pathogen causing potentially life-threatening community-acquired diseases in both the developed and developing world. Since 1967, there has been a dramatic increase in the incidence of penicillin-resistant and multiply antibiotic-resistant pneumococci worldwide. Prevention of access of the antibiotic to the target, inactivation of the antibiotic and alteration of the target are mechanisms that S. pneumoniae has developed to resist antibiotics. Recent studies on antibiotic-tolerant pneumococcal mutants permitted development of a novel model for the control of bacterial cell death.     

Characterization of natural rubber biosynthesisin Ficus benghalensis

Natural rubber was identified for the first time in the latex of Ficus benghalensis, and the rubber biosynthetic activity in latex and rubber particles was investigated. ¹³C NMR analysis of samples prepared by successive extractions with acetone and benzene confirmed that the benzene-soluble residues were natural rubber, cis-1,4-polyisoprene. The rubber content in the latex of F. benghalensis was approximately 17 %. Gel permeation chromatography revealed that the molecular mass of the natural rubber from F. benghalensis was approximately 1 500 kDa. The high rubber content and large molecular size suggest that F. benghalensis is a good candidate for an alternative rubber source. Examination of latex serum from F. benghalensis by SDS-polyacrylamide gel electrophoresis revealed a small number of proteins with major proteins of 31 and 55 kDa in size. The 31-kDa protein was predominant in catalytically-active rubber particles. Determination of metal ion concentration in latex and a comparison of the effect of ethylenediamine-tetraacetic acid on in vitro rubber biosynthesis in F. benghalensis, F. carica and Hevea brasiliensis suggest that the divalent metal ion present in latex serum is an important physiological factor controlling the rubber biosynthetic activities in these plant species. Microscopic examination revealed that the rubber in F. benghalensis occurred in a series of laticifer cells located in concentric zones in the inner bark of stems and branches.     

Photosynthetic and growth responses to fire of the subtropical-temperate grass, Spartina argentinensis Parodi

Fire is a common phenomenon in grasslands but there is little experimental evidence of the mechanism involved in the rapid recovery of the plant growth. We tested under controlled conditions the hypothesis that after fire Spartina argentinensis leaves that restart growing have high photosynthetic rates. Photosynthetic rates and emergence of leaves and culms were registered. Initial photosynthetic rates were higher among plants which restarted growth after fire or clipping than in control ones, without effect of different water availability. High photosynthetic rate values remained during two months after fire or clipping treatments though then affected by water availability, and thereafter started declining towards the end of season. From January onwards no differences among treatments were detected except that control plants under water stress conditions had lower photosynthetic rates than all others. Leaf and culm emergence were promoted by both fire and clipping treatments. Though affect-ed by water availability, burned and clipped plants had the highest percentages of living tissues at the end of the experiment. Considering photosynthetic and growth responses after fire it can be concluded that burning is a regular component of the subtropical-temperate S. argentinensis habitat, among the South American grasslands.     

Degradation and Utilization of Xylans by the Rumen AnaerobePrevotella bryantii(formerlyP. ruminicolasubsp.brevis) B14

Freshly harvested whole cells from cultures ofP. bryantiiB₁4 grown with oat spelt xylan (OSX) as an energy source showed less than 25% of the enzyme activity against OSX, and less than 15% of the activity against birchwood xylan (BWX) and carboxymethylcellulose, that was detectable in sonicated cell preparations. This indicates that much of this hydrolytic activity is either periplasmic, membrane-associated or intracellular and may be concerned with the processing of transported oligosaccharides.P. bryantiiB₁4 cultures were able to utilise up to 45% and 51% of the total pentose present in OSX and BWX, respectively, after 24 h, but could utilize 84% of a water-soluble fraction of BWX. Analysis of the xylan left undegraded after incubation withP. bryantiishowed that while xylose and arabinose were removed to a similar extent, uronic acids were utilized to a greater extent than xylose. Predigestion of xylans with two cloned xylanases from the cellulolytic rumen anaerobeRuminococcus flavefaciensgave little increase in overall pentose utilization suggesting that externalP. bryantiixylanases are as effective as the clonedR. flavefaciensenzymes in releasing products that can be utilised byP. bryantiicells. The xylanase system ofP. bryantiiis able to efficiently utilise not only xylo-oligosaccharides but also larger water-soluble xylan fragments.