Glucose utilization and growth response to protein hydrolysates byFusobacterium species

Glucose uptake was measured in the supernatants of 18 strains ofFusobacterium species cultured in BM medium. Some species, such asF. nucleatum andF. necrophorum, used between 25% and 48% of the glucose in the medium, but the terminal pH remained near neutral. By contrast, strains ofF. mortiferum andF. necrogenes used on average over 90% of the available glucose in the medium and produced a predictably low acidic pH. Strains ofF. varium used between 86% and 91% of the glucose present but produced a near neutral pH of between 5.8 and 5.9. The metabolic fate of glucose inF. varium was, therefore, examined in more detail. Glucose stimulated the growth of this species, and [¹⁴C]glucose was incorporated into the metabolic end products and various cellular components. Protein hydrolysates, tested for their growth-promoting effects onFusobacterium species, produced two general growth response patterns. Most species grew prolifically on trypticase, proteose peptone, and yeast extract, but poorly in casamino acids and vitamin-free casamino acids. Growth in bactocasitone was poor, but for three species,F. necrophorum, F. varium, andF. nucleatum, there was an approximately linear growth response up to 0.5%. These results suggest a major role for nitrogen metabolism but do not preclude glucose as an energy source in at least some species ofFusobacterium.     

Semipermeable polymer tubes provide a microenvironment for in vivo analysis of dorsal root regeneration

The regeneration of lesioned axons is critically influenced by the local microenvironment. In this study, semipermeable polymer tubes were used to provide a defined microenvironment in vivo to analyze the regeneration of dorsal root axons under various conditions in the adult rat. Cut dorsal root fibers grew across a 2.7 mm gap within enclosed polymer tubes by 4 weeks. The pattern of axonal outgrowth was dramatically influenced by mechanical factors such as the inner surface topography of the polymer tube. Tubes containing various molecular and cellular substrates were also used to study their effect on dorsal root regeneration.     

Chromosome association and pollen fertility of parental and interspecific hybrids of Lycopersicon esculentum X L. hirsutum and L. pennellii

Cytological studies were carried out on two wild species (L. hirsutum and L. pennellii) and the cultivated species (L. esculentum) of tomato and their F1 hybrids. Both parents and hybrids show a diploid chromosome number of 2n=24. The meiotic behaviour of the cultivated species showed a high degree of chromosome homology resulting in a high level of chiasmata frequency per bivalent. In contrast, the two wild species showed a slight increase in uniyalent frequency and a decrease in bivalent formation and chiasmata frequency. The meiotic behaviour of the hybrids showed a high level of univalents and low levels of bivalents as well as trivalents. Highly significant decreases in chiasmata frequency and increases in meiotic abnormalities, especially in the L. esculentum X L. pennellii hybrid, also were detected. The high meiotic irregularity and low chiasmata frequency recorded in the second hybrid indicated the disharmony and difference between its parental genomes and also served to predict its sterility. With regard to degree of pairing recorded in the hybrids, there is a possibility that sterility in such cases may refer to genetic factors in addition to the previously mentioned reasons. Pollen fertility showed no great difference between L. esculentum and L. hirsutum and their F1 hybrid, but a significant decrease was recorded in the L. esculentum X L. pennellii hybrid, which was clearly associated with high meiotic irregularity, low chiasmata frequency and chromosome association.     

The MAN antigens are non-lamin constituents of the nuclear lamina in vertebrate cells

The characterization of the human antiserum designated MAN has led to the identification of a subset of non-lamin proteins that are exclusively located at the nuclear periphery in all vertebrate cell types examined, from human to fish. Immunoreactive protein species were whown to comprise three major polypeptides of M _r 78000, 58000 and 40000. These antigens co-partitioned with the nuclear lamina during in situ isolation of nuclear matrices from lamin A/C-positive and-negative mammlian cells. Using double immunofluorescence, the spatial relationship of MAN antigens to type-A and type-B lamins was further examined throughout the cell cycle of lamin A/C-positive mammalian cells. In interphase HeLa and 3t3 cells, MAN antigens colocalized with both types of lamins at the periphery of the nucleus, but were absent from intranuclear foci of lamin B. As HeLa cells proceeded into mitosis, MAN antigens were seen to segregate from lamins A/C and coredistribute with lamin B. Lamins A/C disassembled during late prophase/early prometaphase and reassociated with chromatin in telophase/cytokinesis. In contrast, MAN antigens and lamin B dispersed late during prometaphase and reassembled on chromosomes in anaphase. Altogether, our data suggest that MAN antigens may play key functions in the maintenance of the structural integrity of the nuclear compartment in vertebrate cells.     

Cytological relationships of selected species ofPanicum L.

The cytological investigation of 12 taxa ofPanicum L. revealed that the vast majority of them have the basic number x=9 at different ploidy levels. The basic number x=8 was recorded only in the tetraploid speciesP. maximum with 2n=32. The diploid number 2n=18 was encountered inP. capillare, P. laevifolium, P. antidotale andP. coloratum (2) with 3B-chromosomes recorded in the latter species. The tetraploid chromosome number 2n=36 was found to exist inP. miliaceum, P. miliare, P. coloratum (1) andP. virgatum. The hexaploid number 2n=54 was recorded inP. bulbosum, P. dichotomiflorum andP. esculentum. The karyotypes of all accessions were mostly symmetrical and mainly comprised of meta- and submetacentric chromosomes with little variation in length among them within each karyotype. Investigation of chromosome association during metaphase I of meiosis revealed that the frequency of bivalents/cell was the highest among all investigated diploid, tetraploid and hexaploid accessions. Univalents were also frequently encountered in various accessions. These results may indicate that segmental alloploidy has been the major process by which polyploid species have originated.     

Deep-water macroalgae from the Canary Islands: new records and biogeographical relationships

Due to the geographical location and paleobiogeography of the Canary Islands, the seaweed flora contains macroalgae with different distributional patterns. In this contribution, the biogeographical relations of several new records of deep-water macroalgae recently collected around the Canarian archipelago are discussed. These areBryopsidella neglecta (Berthold) Rietema,Discosporangium mesarthrocarpum (Meneghini) Hauck,Hincksia onslowensis (Amsler et Kapraun) P. C. Silva,Syringoderma floridana Henry,Peyssonnelia harveyana J. Agardh,Cryptonemia seminervis (C. Agardh) J. Agardh,Botryocladia wynnei Ballantine,Gloiocladia blomquistii (Searles) R. E. Norris,Halichrysis peltata (W. R. Taylor) P. Huvé et H. Huvé,Leptofauchea brasiliensis Joly, andSarcodiotheca divaricata W. R. Taylor. These new records, especially those in the Florideophyceae, support the strong affinity of the Canary Islands seaweed flora with the warm-temperate Mediterranean-Atlantic region. Some species are recorded for the first time from the east coast of the Atlantic Ocean, enhancing the biogeographic relations of the Canarian marine flora with that of the western Atlantic regions.     

Are the characeae able to indicate the origin of groundwater in former river channels?

The macroscopic algae Characeae are usually assumed to occur in waterbodies supplied by groundwater with low phosphate content, but the indicative value of the species is seldom defined in bibliography. Former braided channels of the Rhône river are supplied with groundwater originating from the main channel (seepage) or from hillslope aquifer. The aim of the present paper was to determine if it possible to use the Characeae as indicators of physicochemical characteristies of water in order to assess the origin of groundwater supplying former river channels. Four former braided channels of the Rhône River colonized by Characeae were investigated, and the physico-chemical characteristics of i) the channels, ii) the groundwater and iii) the river were measured over a period of several months. Species are arranged along a gradient of conductivity, alkalinity, ammonium and phosphate content of the water. Charophyte species can indicate the origin of groundwater, either seepage or hillslope nutrient-poor aquifer, and integrate both the average value of the chemical parameter, and their variations. C. hispida occurs in a nutrient-poor channel mainly supplied by highly calcareous groundwater coming from hillslope aquifer. Chara major has requirements close to those of C. hispida, but is more tolerant to periodic inputs of nutrients. C. vulgaris and N. syncarpa both tolerate mesotrophic waters originating from both hillslope aquifer and seepage, and C. globularis is associated to a channel mainly supplied by mesotrophic to eutrophic river seepage.     

Further progress towards a catalogue of all Arabidopsis genes: analysis of a set of 5000 non-redundant ESTs

Nearly 7000 Arabidopsis thaliana -expressed sequence tags (ESTs) from 10 cDNA libraries have been sequenced, of which almost 5000 non-redundant tags have been submitted to the EMBL data bank. The quality of the cDNA libraries used is analysed. Similarity searches in international protein data banks have allowed the detection of significant similarities to a wide range of proteins from many organisms. Alignment with ESTs from the rice systematic sequencing project has allowed the detection of amino acid motifs which are conserved between the two organisms, thus identifying tags to genes encoding highly conserved proteins. These genes are candidates for a common framework in genome mapping projects in different plants.