Isolation and Partial Characterization of Bacteriophages of the Phytopathogen Pseudomonas syringae

Bacteriophages isolated from culture supernatants of Pseudomonas syringae pv. syringae and from sewage were identified. The DNA from each phage was isolated and digested with the restriction endonuclease EcoRI. Eight isolates were determined to be different, with two phage isolates from sewage having restriction patterns identical to two phages from culture supernatants. The sizes of the phage DNA ranged from 24 to49 kilobases for isolates from sewage and from 39 to 52.5 kilobases for the isolates from culture supernatants. Buoyant densities of phage particles in CsCl varied from 1.498 to 1.507 g/cm³ for isolates from sewage and from 1.506 to 1.516 g/cm³ for isolates from culture supernatants. Electron microscopy revealed four morphological types. Based on plaque-forming ability of culture supernatants, 31 out of 47 strains of P. syringae are probably lysogenic.     

Studies of the GTPase domain of archaebacterial ribosomes

Ribosomes from the methanogens Methanococcus vannielii and Methanobacterium formicicum catalyse uncoupled hydrolysis of GTP in the presence of factor EF-2 from rat liver (but not factor EF-G from Escherichia coli). In this assay, and in poly(U)-dependent protein synthesis, they were sensitive to thiostrepton. In contrast, ribosomes from Sulfolobus solfataricus did not respond to factor EF-2 (or factor EF-G) but possessed endogenous GTPase activity, which was also sensitive to thiostrepton. Ribosomes from the methanogens did not support (p)ppGpp production, but did appear to possess the equivalent of protein L11, which in E. coli is normally required for guanosine polyphosphate synthesis. Protein L11 from E. coli bound well to 23S rRNA from all three archaebacteria (as did thiostrepton) and oligonucleotides protected by the protein were sequenced and compared with rRNA sequences from other sources.     

Dispersal of Beauveria bassiana by the activity of nettle insects

Recent studies have shown that the entomopathogenic fungus Beauveria bassiana occurs naturally on the phylloplanes of several plants, including nettles. Insects could, by their activity, be contributing to this inoculum by dispersing it from other sites. The potential of nettle aphids Microlophium carnosum and their predator Anthocoris nemorum to disperse conidia of B. bassiana from soil to nettles and from sporulating cadavers in the nettle canopy was investigated in laboratory experiments. In petri dish assays, aphids showed potential to distribute B. bassiana from soil to nettle leaves. Predators dispersed inoculum from both soil and cadavers to nettle leaves in petri dishes. In microcosms, aphids did not disperse B. bassiana from the soil or from cadavers confined in the canopy, but A. nemorum were able to transfer inoculum from soil into the nettle canopy and to distribute conidia from cryptic cadavers. In some instances, infections were initiated in aphids and predators as a consequence of dispersal.     

Photosynthetic properties of permaplasts of anacystis

A treatment procedure using lysozyme and ethylenediaminetetracetic acid gave intact but permeable cells (permeaplasts) of Anacystis nidulans. Rates of electron transport from water to carbon dioxide, ferricyanide, 2,6-dichlorophenol indophenol, benzoquinone, and methyl viologen, and from reduced indophenol to methyl viologen were measured as a function of treatment time. Rates of oxygen evolution in complete photosynthesis and electron flow from water to methyl viologen showed rapid and parallel decline with treatment time. Electron flow from water to ferricyanide and from reduced indophenol to methyl viologen increased during the first half hour of treatment (phase 1) to 60 to 80% of the original photosynthetic rate. Longer treatment (phase 2) resulted in decreased rate of ferricyanide reduction but not in rate of methyl viologen reduction from indophenol. Electron flow from water to quinone was two to three times higher than for complete photosynthesis in intact cells. It remained high during phase 1 and declined during phase 2. Phase 1 permeaplasts apparently retain high activity for photosystems 1 and 2 photoreactions.     

Agars of Gelidiella acerosa of west and southeast coasts of India

Seventeen agar samples were extracted from Gelidiella acerosa (Forsskal) Feldmann and Hamel (Rhodophyta, Gelidiales) specimens collected from nine different sites on the Indian coast-five from southeast coast and four from the west coast. The agar samples were analysed. The stability characteristics of the gels of selected agar samples were studied by rheometry under applied stress conditions, i.e. variation of the storage (G') and loss moduli (G') were studied under varying frequency and duration (time) of the stress applied. Yield, apparent and dynamic viscosities, gelling and melting temperatures, 3,6-anhydrogalactose (3,6-AG), sulphate contents and TGA (Thermogravimetric Analysis) measurements of the products were done. It was observed that the best quality agar was produced by G. acerosa occurring in the Gulf of Mannar region in the southeast coast. The gel strengths and the viscosities of agars extracted from Gelidiella acerosa occurring in the Gulf of Mannar ranged from 500 to 700gcm(-2) and 33 to 45cP for 2001 collections and for 2002 collections the corresponding values were 450 to 845gcm(-2) and 55 to 67cP respectively. On the other hand, for the agar samples extracted from the west coast of India, the gel strength and viscosities values ranged from 225 to 400gcm(-2) and from 15 to 30cP, respectively. The agars obtained from G. acerosa collected from southeast coast have been found to be suitable for bacterial culture and molecular biology. This is the first report of superior quality of agar from the Indian agarophytes.     

山羊卵母细胞的减数分裂进程

The meiotic progression of goat oocytes from follicles of different diameters was investigated in this study. The results were summarized as follows: (1) The in vitro meiotic maturation capacity was different among oocytes from follicles of different diameters. And thus oocytes from < or = 0.5 mm follicles were unable to resume meiosis; oocytes from 0.8-1.2 mm follicles were capable to resume meiosis, but could develop only to MI stage (60% at 24 h); oocytes from 1.5-5 mm follicles had acquired full-meiotic maturation capacity and 91% of them developed to M II stage at 24 h of culture. (2) The percentage of oocytes with intact-germinal vesicles from 1.5-5 mm follicles decreased significantly during 2-8 h of in vitro maturation and the decrease was even more rapid during 4-6 h of culture (from 60% to 19%, p < 0.0005). The percentage of oocytes at M I-stage increased from 24% to 61% during 6-12 h of in vitro maturation, and it then decreased. By 24 h of culture, only 2% oocytes remained at M I-stage. Twenty one percent of the oocytes in this group developed to M II-stage at 16 h of culture, and by 24 h of culture, 91% were at M II-stage. (3) Statistic analysis of the meiotic progression (the duration of each cell cycle stage) of oocytes from 1.5-5 mm follicles showed that GV stage lasted from 0 to 3 h of culture, prometaphase-I stage was from 3.0 to 7.0 h, metaphase-I stage was from 7.0 to 14.6 h, anaphase-I/telophase-I was from 14.6 to 18.4 h and metaphase-II stage lasted from 18.4 to 24 h. (4) Whether the oocytes capable of GVBD and entrance of M I developed to M II, the timing of meiotic progression prior to M I was similar. In summary, our results provided necessary data for studies on the mechanisms and control of meiosis in mammalian oocytes.     

Effect of recirculation of currant-finishing wastewater (CFW) on its composition

The feasibility of recirculation of currant-finishing wastewater in a currant-wash process was investigated in a laboratory scale plant. Recycle ratios from 0% to 95% were examined. By increasing the recycle ratio, effluent BOD increased from 681 to 5378 mg/l, effluent COD from 3808 to 43,722 mg/l, total suspended solids from 12.3 to 57.7 g/l, total sugars from 2.57 to 42.13 g/l, total phosphorus from 0.79 to 5.14 mg/l, total Kjeldahl nitrogen from 7.36 to 51.9 mg/l and total phenolic compounds from 0.095 to 1.13 g/l, while fresh water addition decreased from 6 to 0.3 kg/kg of currants processed and total sugars loss from 15.43 to 12.64 g/kg of currants processed. For a recycle ratio of 95%, the mass of currants recovered as a final product increased by 10% due to the proportional decrease in the sugars wasted per kg of currants processed.     

Isolation of Clostridium difficile from various colonies of laboratory mice

An attempt was made to isolate Clostridium difficile from a total of 565 mice from nine different conventional mouse colonies and six different specified-pathogen-free mouse colonies. C. difficile was isolated from all the conventional colonies but from none of the specified-pathogen-free colonies. Ampicillin injected intraperitoneally increased the isolation rate of C. difficile from mouse faeces to 63.6% compared with 19.4% from untreated mice.     

Effects of serum from human subjects of various ages on proliferation of human lung and skin fibroblasts

We carried out a study to determine whether serum from old human subjects inhibited cell proliferation. The results showed that serum from old subjects of either sex did not greatly inhibit the proliferation of human fetal lung fibroblast TIG-1 cells, even when serum from subjects in their 80s was used. The same results were obtained when the effects of serum on cell proliferation were examined up to a serum concentration of 50%. It was also found that serum from old subjects did not inhibit proliferation of human skin fibroblasts from a young adult to any greater degree than serum from young adult subjects, and that serum from young adult subjects did not stimulate proliferation of skin fibroblasts from an elderly donor to any greater degree than serum from old subjects.     

Quinolone-resistant mutations of the gyrA gene of Escherichia coli

Summary DNA fragments of 8.5 kb containing the gyrA gene were cloned from Escherichia coli KL-16 and from four spontaneous gyrA mutants which showed various levels of resistance to quinolones. The gyrA gene was situated at about 4 kb in front of the nrdA gene and transcribed counterclockwise on the E. coli chromosome. It encoded a polypeptide of 875 amino acids with a molecular weight of about 97000. The four gyrA mutations were located strikingly close to one another within a small region near the N-terminus of the gyrA polypeptide, i.e., nucleotide changes from C to T, from C to G, from G to T and from G to T at nucleotides 248, 248, 318 and 199, respectively, resulting in amino acid changes from Ser to Leu, from Ser to Trp, from Gln to His and from Ala to Ser at amino acids 83, 83, 106 and 67, respectively. These mutations were situated in the relatively hydrophilic regions of the GyrA polypeptide and close to Tyr at amino acid 122 which has been shown to be the site covalently bound to DNA.     

Influence of Indigenous Microbiota on Amount of Protein and Activities of Alkaline Phosphatase and Disaccharidases in Extracts of Intestinal Mucosa in Mice

The protein content and the activities of alkaline phosphatase, maltase, and sucrase were measured at 0800, 1000, 1200, 1400, and 1600 in saline extracts of the proximal small bowels of germfree and of ex-germfree mice colonized with an indigenous microbiota. In extracts prepared from germfree mice, the total activities of all of the enzymes were relatively constant throughout the sampling period. Likewise, the total activity of alkaline phosphatase in extracts prepared from associated mice varied little as a function of time. By contrast, the total activities of maltase and sucrase in the extracts from these latter animals varied significantly from sample to sample. The total activity levels in extracts from germfree mice were approximately twofold greater than the levels in extracts from associated mice. The specific activities of alkaline phosphatase and sucrase did not vary from sample to sample in extracts prepared from either type of mouse. In contrast, the specific activity of maltase in extracts prepared from both germfree and associated mice differed significantly from sample to sample. The specific activities of all three enzymes were greater in extracts from germfree animals than in those from associated animals. The protein content of extracts prepared from germfree mice also was greater than that of extracts prepared from associated animals at every sampling time. The amount of protein extractable from the mucosa of the small bowels of the former animals varied significantly at different sampling times during the day, whereas the amount of protein extractable from the tracts of associated animals remained relatively constant throughout the day. The indigenous microbiota apparently stabilizes in some way the amount of protein extractable from the mucosa of the mouse small bowel.     

Major trends of evolution in palms

From the diversity found among palms the following evolutionary trends are suggested:habit: from sympodial to monopodial;size: from moderate toward large and also toward small;stem: from unbranched to dichotomously branched, from little to much sclerenchyma, from short to elongate internodes;leaf: from an undivided eophyll to a palmate, costapalmate, pinnately ribbed or pinnate blade; from undivided and plicate to divided along the adaxial rib (“induplicate”) or along the abaxial rib (“reduplicate”); from pinnate to bipinnate or to pinnae onceor twicedivided longitudinally; from sheath split opposite the petiole to sheath tubular; from marcescent to deciduous; from central vascular bundles of the petiole with a single phloem strand to two phloem strands;inflorescence units: from moderately branched to spicate or less frequently to more diffusely branched, from one unit per leaf axil to more than one per axil, from among the leaves to below them or to above them in a compound terminal inflorescence, from pleonanthic to hapaxanthic;prophyll: from completely to incompletely encircling the peduncle, from incompletely to completely sheathing in bud;bracts: from conspicuous to small or absent at maturity, first peduncular bract from tubular and open at the apex to completely enclosing the inflorescence in bud, and then from ungrooved to deeply plicate;flower arrangement: from solitary, pedicellate, bracteolate flowers to a sympodial cincinnus of 2 or 3 or more, or to a short monopodial axis of 2–4 or more;bracteoles: from sheathing and prophyllate to completely closed or to incompletely developed or absent;flowers: from bisexual to unisexual, then associated with polygamy or monoecism to dioecism;perianth: from trimery to dimery or tetramery to decamery or to reduced and monochlamydeous;sepals: from distinct and imbricate to connate or separated;petals: from distinct and imbricate to valvate, or strongly imbricate, or connate; from small and ovate to large and variously shaped, or to small;stamens: from 6 to 3 or to more than 6 (to 950+);filaments: from relatively slender and distinct to broad and thick, and often connate or adnate to the perianth or both;staminodes: from stamenlike with abortive anthers only, to short teeth, or to a cupule at the base of the ovary, or to absent;pollen: from monosulcate to trichotomosulcate to dicolpate to monocolpate, diporate, or triporate;gynoecium: from apocarpous to syncarpous, from thin walls to thick, variously specialized walls;carpels or locules: from 3 to 2-1 or to 4–10;ovules: from moderate to small or to large, from anatropous to hemianatropous to campylotropous to orthotropous;pistillode: from only slightly modified from the gynoecium to vestigial or lacking or rarely to prominent;fruit: from fleshy to dry and fibrous;endocarp: from little differentiated or thin, to thick and hard, and sometimes with a pore or operculum over the embryo;seed: from moderate to small or to very large, from entire to dissected, bilobed, or perforate;endosperm: from homogeneous to invaginated or ruminate;germination: from remotetubular or -ligular to adjacent-ligular;chromosome complement: fromn = 18 ton = 17, 16, 15, 14, 13.     

Generation of pluripotent stem cells from eggs of aging mice

Oocytes can reprogram genomes to form embryonic stem (ES) cells. Although ES cells largely escape senescence, oocytes themselves do senesce in the ovaries of most mammals. It remains to be determined whether ES cells can be established using eggs from old females, which exhibit reproductive senescence. We attempted to produce pluripotent stem cell lines from artificial activation of eggs (also called pES) from reproductive aged mice, to determine whether maternal aging affects pES cell production and pluripotency. We show that pES cell lines were generated with high efficiency from reproductive aged (old) mice, although parthenogenetic embryos from these mice produced fewer ES clones by initial two passages. Further, pES cell lines generated from old mice showed telomere length, expression of pluripotency molecular markers (Oct4, Nanog, SSEA1), alkaline phosphatase activity, teratoma formation and chimera production similar to young mice. Notably, DNA damage was reduced in pES cells from old mice compared to their progenitor parthenogenetic blastocysts, and did not differ from that of pES cells from young mice. Also, global gene expression differed only minimally between pES cells from young and old mice, in contrast to marked differences in gene expression in eggs from young and old mice. These data demonstrate that eggs from old mice can generate pluripotent stem cells, and suggest that the isolation and in vitro culture of ES cells must select cells with high levels of DNA and telomere integrity, and/or with capacity to repair DNA and telomeres.     

Parasitism of cowpea by Striga gesnerioides: variation in virulence and discovery of a new source of host resistance

In glasshouse experiments in the United Kingdom, Striga gesnerioides-resistant cowpea varieties, Suvita-2 and 58–57, were assessed alongside a susceptible variety for their responses to seventeen samples of S. gesnerioides from four West African countries. The susceptible variety was attacked by all samples, while Suvita-2 was resistant to samples from Burkina Faso and Mali, and 58–57 was resistant only to samples from Burkina Faso.
At least three physiological groups of the parasite can be distinguished: samples from Burkina Faso attacking the smallest range of cowpea varieties; those from Mali being intermediate; those from Niger and Nigeria attacking all the cowpea varieties. A sample from Cameroon behaved slightly differently and may represent a fourth type.
A cowpea line from Botswana, B.301, selected for its field resistance to Alectra vogelii proved resistant to all Striga populations to which it was exposed, including those from Niger and Cameroon.     

In vitro synthesis of oligosaccharides by acceptor reaction of dextransucrase from Leuconostoc mesenteroides

Glucose was used as acceptor to obtain small chain oligossaccharides from sucrose using dextransucrase from Leuconostoc mesenteroides NRRL B-512F. Better conditions for the synthesis of the oligosaccharides were obtained using experimental design and response surface methodology. Yield of oligosaccharides was increased from 5% to 45% following an increase in both sucrose and glucose/sucrose concentrations, from 58 g/l to 142 g/l and from 0.02 to 0.18, respectively. Molecular weight increased from 2800 to 4500 daltons with a temperature shifting from 10°C to 30°C. © Rapid Science Ltd. 1998     

The effect of different temperatures on the development of intra-molluscan stages of

The duration of various development stages of inside the intermediate host were determined at different constant temperatures ranged from 12° to 30°C. The rate of development of sporocyst, redia, daughter redia and cercaria was accelerated as a result of increasing the temperature. Thus, an increase in the incubation temperatures from 15° to 30°C reduced the duration of sporocyst from 21 to 4 days, the redia from 37 to 11 days, daughter redia from 53 to 22 days and the cercaria from 73 to 25 days. At 12°C, the parasite developed to redial stage only and it required 51 days. Cercaria formation was observed at temperatures between 15 to 30°C. The highest cercaria output/snail was observed at 15°C and the lowest at 30°C.     

Growth of a pogonophore: a study of Polybrachia canadensis with a discussion of the development of taxonomic characters

Heptabrachia canadensis , previously known from one juvenile specimen, has been redescribed from new material and transferred to the genus Polybrachia. About 1400 specimens were available for study, including a series of developmental stages ranging from juveniles less than 0.1 mm in diameter to adults 0.6 mm in diameter. The smallest juveniles have one tentacle while most adults have 30 to 40 tentacles. Juveniles differ from adults in diameter, length, number of tentacles and type of tube. The most important observation to emerge is the variability of characters hitherto thought to distinguish different genera, and the need for care in the diagnosis of new species from limited material.     

Comparison of chemical analyses of boat and helicopter-collected water samples

Helicopters can be used to collect water samples from many lakes over a wide geographic area within a relatively short time period. Here we report the results from an experiment in which sequential water samples from a lake were collected first from a nonmotorized boat and then immediately afterward from a helicopter. No significant differences were found between the means of the measurement of 20 chemical parameters for the two methods of collection. When compared to obtaining samples from a boat, collection of samples from a helicopter platform had no effect on the content of the water samples.     

Evolution of an embryo

In fossil material from two welis from Java, one section from East Java and two sections from Madura, specimens belonging to the extinet genusLepidocyclina (Foraminifera) were examined. Attention was paid to the embryonic part of the megalospheric forms exclusively. The size of the protoconch and deuteroconch was measured, but in particular also their spatial relation as determined by the extent to which the latter encloses the former, or the extent to which the dividing-wall between them is curved (“degree of curvature”). This parameter was found to increase persistently from 10% in the Middle Oligocene to 67% in the Middle Miocene. The rate of evolution showed to be inconstant, changing from very slow to very fast to slow again and to fast again. The first period of rapid change coincides with the time (Middle Oligocene) during which the genus migrated from America to Europe and to the Far East and Australia. The second phase of rapid evolution took place from the beginning of the Miocene up to the moment of dying out of the genus. The progressive change of this parameter is considered from the point of view of genetic variation and selection.