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1.
The proximate composition, nutrient and trace elements of the planktonic algal “jellies” of Lake Oguta in Southern Nigeria, are provided as guides to their utilization and control, using flood (rainy) and dry season samples. These “jellies” are an unusual, macroscopic planktonic algal community in the lake, made up mostly of blue-green algae (Microcystis, Anabaena, Chroococcus) with some green algae (e. g. Spirogyra) and pennate diatoms (e.g. Navicula) rather epiphytic on the mucous jellies of the blue-green algae. Water content was high (98.2% mean, range 97.5-99.5%). Ash, protein and fat had values of 41.7 (39.0-46.2%), 16.9 (15.6-19.4%), and 2.0 (1.7-2.1%) respectively. Crude fibre and carbohydrates were high (25.8% and 12.4%). The levels of phosphorus and nitrogen were rather high, so were the major cations whose order of dominance (Ca > K > Mg > Na) differed from that of the lake water. Macronutrients increased in their concentrations during the rainy flood season while the reverse was the case with the micronutrients. Diagenesis of the endogenic minerals rather than anthropogenic factors are thought to be the reason for the seasonal changes in the ionic concentrations. Possible uses of the algal jellies are discussed as well as their control options. 相似文献
2.
Mariana Cabral Oliveira 《Journal of phycology》2011,47(3):680-686
This study evaluated the phylogenetic relationship among samples of “Chantransia” stage of the Batrachospermales and Thoreales from several regions of the world based on sequences of two genes—the plastid‐encoded RUBISCO LSU gene (rbcL) and the nuclear SSU ribosomal DNA gene (SSU rDNA). All sequences of “Chantransia macrospora” were shown to belong to Batrachospermum macrosporum based on both molecular markers, confirming evidence from previous studies. In contrast, nine species are now associated with “Chantransia pygmaea,” including seven species of the Batrachospermales and two of the Thoreales. Therefore, the presence of “C. macrospora” in a stream can be considered reliable evidence that it belongs to B. macrosporum, whereas the occurrence of “C. pygmaea” does not allow the recognition of any particular species, since it is associated with at least nine species. Affinities of “Chantransia” stages to particular taxa were congruent for 70.5% of the samples comparing the rbcL and SSU analyses, which were associated with the same or closely related species for both markers. Sequence divergences have been reported in the “Chantransia” stage in comparison to the respective gametophyte, and this matter deserves further attention. 相似文献
3.
Rapid detection of “Candidatus Phytoplasma mali” by recombinase polymerase amplification assays
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Isothermal recombinase polymerase amplification (RPA) assays for the specific detection of “Candidatus Phytoplasma mali (Ca. P. mali),” the causal agent of apple proliferation, were developed. The assays amplify a fragment of the imp gene and amplimers were detected either by fluorescence in real‐time mode (TwistAmp®exo assay) using a fluorophore‐labelled probe or by direct visualization employing a lateral flow device (TwistAmp®nfo assay/Milenia®HybriDetect). The RPA assays specifically amplified DNA from “Ca. P. mali” strains, and cross‐reactivity with other phytoplasmas or plant DNA was not observed. The limit of detection was determined with a cloned imp standard, and positive results were obtained down to 10 copies with both RPA assay formats. In comparison with a TaqMan real‐time PCR assay based on the same target gene, the RPA assays were equally sensitive, but results were obtained faster. Simplified nucleic acid extraction procedures from plant tissue with Tris‐ and CTAB‐based buffers revealed that crude Tris–DNA extracts were a suitable source for RPA tests while larger concentrations of CTAB were inhibitory. This is the first report of RPA‐based assays for the detection of “Ca. P. mali”. The assays are suitable for high‐throughput screening of plant material and point‐of‐care diagnostic and can be potentially combined with a simplified DNA extraction procedure. 相似文献
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Yoh Iwasa Andrew Pomiankowski Sean Nee 《Evolution; international journal of organic evolution》1991,45(6):1431-1442
We use a general additive quantitative genetic model to study the evolution of costly female mate choice by the “handicap” principle. Two necessary conditions must be satisfied for costly preference to evolve. The conditions are (i) biased mutation pressure on viability and (ii) a direct relationship between the degree of expression of the male mating character and viability. These two conditions explain the success and failure of previous models of the “handicap” principle. Our model also applies to other sources of fitness variation like migration and host-parasite coevolution, which cause effects equivalent to biased mutation. 相似文献
6.
Growth and fecundity of fertile Miscanthus × giganteus (“PowerCane”) compared to feral and ornamental Miscanthus sinensis in a common garden experiment: Implications for invasion
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Maria N. Miriti Tahir Ibrahim Destiny Palik Catherine Bonin Emily Heaton Evans Mutegi Allison A. Snow 《Ecology and evolution》2017,7(15):5703-5712
Perennial grasses are promising candidates for bioenergy crops, but species that can escape cultivation and establish self‐sustaining naturalized populations (feral) may have the potential to become invasive. Fertile Miscanthus × giganteus, known as “PowerCane,” is a new potential biofuel crop. Its parent species are ornamental, non‐native Miscanthus species that establish feral populations and are sometimes invasive in the USA. As a first step toward assessing the potential for “PowerCane” to become invasive, we documented its growth and fecundity relative to one of its parent species (Miscanthus sinensis) in competition with native and invasive grasses in common garden experiments located in Columbus, Ohio and Ames, Iowa, within the targeted range of biofuel cultivation. We conducted a 2‐year experiment to compare growth and reproduction among three Miscanthus biotypes—”PowerCane,” ornamental M. sinensis, and feral M. sinensis—at two locations. Single Miscanthus plants were subjected to competition with a native grass (Panicum virgatum), a weedy grass (Bromus inermis), or no competition. Response variables were aboveground biomass, number of shoots, basal area, and seed set. In Iowa, all Miscanthus plants died after the first winter, which was unusually cold, so no further results are reported from the Iowa site. In Ohio, we found significant differences among biotypes in growth and fecundity, as well as significant effects of competition. Interactions between these treatments were not significant. “PowerCane” performed as well or better than ornamental or feral M. sinensis in vegetative traits, but had much lower seed production, perhaps due to pollen limitation. In general, ornamental M. sinensis performed somewhat better than feral M. sinensis. Our findings suggest that feral populations of “PowerCane” could become established adjacent to biofuel production areas. Fertile Miscanthus × giganteus should be studied further to assess its potential to spread via seed production in large, sexually compatible populations. 相似文献
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A disease with symptoms similar to palm lethal yellowing was noticed in the early 2013 in Khuzestan Province (Iran) in date palm (Phoenix dactylifera). Infected trees displaying symptoms of streak yellows and varied in the incidence and severity of yellowing. A study was initiated to determine whether phytoplasma was the causal agent. Polymerase chain reaction–restriction fragment length polymorphism (PCR‐RFLP) methods using universal phytoplasma primers pairs R16mF1/mR1 and M1/M2 were employed to detect putative phytoplasma(s) associated with date palm trees. Nested PCR using universal primers revealed that 40 out of 53 trees were positive for phytoplasma while asymptomatic date palms from another location (controls) tested negative. RFLP analyses and DNA sequencing of 16S rDNA indicated that the presence of two different phytoplasmas most closely related to clover proliferation (CP) phytoplasma (group 16SrVI) and ash yellows (AY) phytoplasma (group 16SrVII). Sequence analysis confirmed that palm streak yellows phytoplasmas in each group were uniform and to be phylogenetically closest to “CandidatusP. fraxini” (MF374755) and “Ca. P. trifolii” isolate Rus‐CP361Fc1 (KX773529). Result of RFLP analysis of secA gene of positive samples using TruI and TaqI endonuclease is in agreement with rDNA analysis. On this basis, both strains were classified as members of subgroups 16SrVI‐A and 16SrVII‐A. This is the first report of a phytoplasma related to CP and AY phytoplasma causing date palm yellows disease symptoms. 相似文献
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Biophysical considerations allow estimates of the mechanical stresses on self-bearing vertical stems of plants. Even at moderate wind velocities the stresses induced by aerodynamic forces dominate over those induced by the own weight. Using polar coordinates, analytical expressions of cross-sectional area and axial second moment of area for centrisymmetric structures with symmetries threefold or higher are derived. Calculating the relative section modulus for various (centrisymmetric) arrangements of stabilizing structures leads to an estimate of the “mechanical effectivity” of these structures. If for plant stems, seen as composite materials, the second moments of area and the elastic moduli are known, the contribution of the different tissues to mechanical stability can be determined quantitatively. The mechanical design of early “vascular” land plants and of stems of (fossil) trees and lianas in different ontogenetic stages can be assessed. 相似文献
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C. S. Nwadiaro 《International Review of Hydrobiology》1989,74(6):633-642
Preliminary observations were made between October 1982 and May 1983 on the nature, taxonomic composition, spatial distribution, buoyancy behaviour and nutrient requirements of some unusual planktonic algal “jellies” in Oguta Lake in Southeastern Nigeria. These “jellies” are macroscopic, blue-green algal masses whose excessive mucilage of high consistency acts as substrata for other epiphytic components viz. diatoms and green algae. They are more abundant in the lentic areas of the lake, undergo diurnal vertical movements and have their growth enhanced by spikes of nitrogen and phosphorus salts into their aquatic medium. The effects of these “jellies” on the ecology and general water use of the lake are discussed. Speculations on the reasons for their occurrence are given and possible control measures outlined. 相似文献
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Carey P. Yeager 《American journal of primatology》1990,20(2):95-106
Proboscis monkey (Nasalis larvatus) social organization was studied at the Tanjung Puting National Park in Kalimantan Tengah, Indonesia, for 12 months. Data were collected on one-male groups and all-male groups by using scan sampling and event sampling while following groups. Evening census surveys were also conducted. Proboscis monkeys were found to follow the typical Asian colobine pattern of one-male social groups, with extra-group males forming all-male groups. These groups appear stable, with few changes in membership. One-male groups appear to be “female bonded”; adult females direct affiliative behaviors towards their offspring and other adult females, not towards the male. Nearest-neighbor data indicate some peripheralization of juvenile animals. 相似文献
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Geoffrey N. Brown Christine Müller Eirini Theodosiou Matthias Franzreb Owen R.T. Thomas 《Biotechnology and bioengineering》2013,110(6):1714-1725
Cerium (IV) initiated “graft‐from” polymerization reactions were employed to convert M‐PVA magnetic particles into polyacrylic acid‐fimbriated magnetic cation exchange supports displaying ultra‐high binding capacity for basic target proteins. The modifications, which were performed at 25 mg and 2.5 g scales, delivered maximum binding capacities (Qmax) for hen egg white lysozyme in excess of 320 mg g?1, combined with sub‐micromolar dissociation constants (0.45–0.69 µm) and “tightness of binding” values greater than 49 L g?1. Two batches of polyacrylic acid‐fimbriated magnetic cation exchangers were combined to form a 5 g pooled batch exhibiting Qmax values for lysozyme, lactoferrin, and lactoperoxidase of 404, 585, and 685 mg g?1, respectively. These magnetic cation exchangers were subsequently employed together with a newly designed “rotor–stator” type HGMF rig, in five sequential cycles of recovery of lactoferrin and lactoperoxidase from 2 L batches of a crude sweet bovine whey feedstock. Lactoferrin purification performance was observed to remain relatively constant from one HGMF cycle to the next over the five operating cycles, with yields between 40% and 49% combined with purification and concentration factors of 37‐ to 46‐fold and 1.3‐ to 1.6‐fold, respectively. The far superior multi‐cycle HGMF performance seen here compared to that observed in our earlier studies can be directly attributed to the combined use of improved high capacity adsorbents and superior particle resuspension afforded by the new “rotor–stator” HGMS design. Biotechnol. Bioeng. 2013; 110: 1714–1725. © 2013 Wiley Periodicals, Inc. 相似文献
12.
Denis Baurain Laurent Renquin Stana Grubisic Patsy Scheldeman Amha Belay Annick Wilmotte 《Journal of phycology》2002,38(2):384-393
The internally transcribed spacer (ITS) sequences of 21 Arthrospira clonal strains from four continents and assigned to four different species (A. platensis, A. maxima, A. fusiformis, A. indica) in the culture collections were determined. Two main clusters, I and II, were differentiated by 49 positions out of 475 nt or 477 nt, respectively. Each cluster was further subdivided into two subclusters. Subclusters I.A and I.B were separated by two substitutions, whereas subclusters II.A and II.B were distinguished by four substitutions. After direct sequencing of the PCR products, three dried samples from Chad aged between 3 months and 35 years yielded a sequence belonging to subcluster I.A, as did a recent commercial product. The strains grown in production plants belonged to the same (sub)clusters as strains from culture collections, mainly I.A and II. PCR primers specific for each cluster and subcluster were designed and tested with crude cell lysates of Arthrospira strains. One dried sample (“dihé” 1) and a herbarium sample from Lake Sonachi (Kenya) only contained I.A sequences, whereas the commercial product was a mixture of the four genotypes and the other two dried samples contained minor polymorphisms characteristic of different clusters. Five clonal Arthrospira strains, thought to be duplicates, showed the simultaneous presence of the two forms of the four diagnostic positions that distinguish subclusters genotype II.A and genotype II.B. This is likely to be caused by multiple copies of the rDNA operon, in a intermediate stage of homogenization between subcluster II.A and subcluster II.B. The high conservation of ITS sequences is in contrast with the assignment to four different species, the great morphological variability of the strains, and their wide geographic distribution. 相似文献
13.
Craig W. Schneider 《Journal of phycology》2010,46(4):653-657
Recent collections of tetrasporangiate “Heterosiphonia” japonica Yendo from Watch Hill to Point Judith, Rhode Island, represent the first report of this nonnative alga in the western Atlantic. Native to the Pacific Ocean, this species was unintentionally introduced into European waters by 1984 and has subsequently invaded the eastern Atlantic Ocean widely from France to Norway and south into the Mediterranean Sea. Thus far, all western Atlantic collections of this species are confined to the outer coast of Rhode Island, and at present are not found in Narragansett Bay or in Long Island Sound along the Connecticut coast. Molecular and morphological studies confirm the identity of this newly introduced invasive species. 相似文献
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Yue Ma Guoqing Pan Ying Zhang Xianzhi Guo Huiqi Zhang 《Journal of molecular recognition : JMR》2013,26(5):240-251
Bisphenol A (BPA) and propranolol‐imprinted polymers have been prepared via both reversible addition–fragmentation chain transfer “bulk” polymerization (RAFTBP) and traditional radical “bulk” polymerization (TRBP) under similar reaction conditions, and their equilibrium binding properties were compared in detail for the first time. The chemical compositions, specific surface areas, equilibrium bindings, and selectivity of the obtained molecularly imprinted polymers (MIPs) were systematically characterized. The experimental results showed that the MIPs with molecular imprinting effects and quite fast binding kinetics could be readily prepared via RAFTBP, but they did not show improved template binding properties in comparison with those prepared via TRBP, which is in sharp contrast to many previous reports. This could be attributed to the heavily interrupted equilibrium between the dormant species and active radicals in the RAFT mechanism because of the occurrence of fast gelation during RAFTBP. The findings presented here strongly demonstrates that the application of controlled radical polymerizations (CRPs) in molecular imprinting does not always benefit the binding properties of the resultant MIPs, which is of significant importance for the rational use of CRPs in generating MIPs with improved properties. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
15.
Leanne T. Nash 《American journal of primatology》1983,5(3):181-196
The reproductive patterns (birth seasonality, litter size, litters per year) of two sympatric species of galago (Galago zanzibaricus and G. garnettii) were studied in a coastal forest in Kenya for a two-year period. Trap-retrap and radio tracking methods were employed. G. zanzibaricus has one infant twice per year; G. garnettii has one infant once per year. Both species are seasonal breeders. These East African galagos are intermediate in reproductive patterns when compared with galagos from South African woodland (G. senegalensis moholi and G. crassicaudatus umbrosis) and West African rainforest (G. alleni and G. demidovii). Climatic patterns (total annual rainfall, seasonal variability of rainfall, variability in total annual rainfall, and annual temperature variability) are also compared for the three regions. Climatically, East Africa is intermediate between West and South Africa in total annual rainfall and in seasonality of rainfall, but not in year-to-year variability in rainfall. East Africa shows the highest variability in annual rainfall. South Africa has the coldest dry seasons and highest variability in temperatures. The results of this study suggest that “r-selection” and “K-selection” do not provide adequate explanations of galago reproductive patterns. 相似文献
16.
Maryam Ghayeb Zamharir 《Journal of Phytopathology》2018,166(3):161-166
A large‐scale survey was conducted on pistachio plants exhibiting foliar symptoms including scorch, little leaf, yellows and reddish in pistachio growing areas in the Qom, Yazd and Qazvin provinces of Iran. Total DNA was extracted from symptomatic and symptomless pistachio and used in nested PCR assays with phytoplasma universal primers. Nested PCR products were obtained for symptomatic plant samples while the symptomless plants yielded no PCR products. Virtual restriction fragment length polymorphism, phylogenetic and DNA homology analyses of partial 16S ribosomal sequences of phytoplasma strains associated with symptomatic plants revealed the presence of phytoplasmas referable to two ribosomal groups; in particular, “Candidatus Phytoplasma solani” and “Ca. P. phoenicium” were identified. The presence of these phytoplasmas in pistachio is of great phytosanitary significance due to its commercial interest. 相似文献
17.
Rechargeable aqueous Zn‐based batteries are attractive candidates as energy storage technology, but the uncontrollable Zn dendrites, low stripping/plating coulombic efficiency, and inefficient utilization of Zn metal limit the battery reliability and energy density. Herein, for the first time, a novel presodiated TiS2 (Na0.14TiS2) is proposed and investigated as an intercalated anode for aqueous Zn‐ion batteries, showing a capacity of 140 mAh g?1 with a suitable potential of 0.3 V (vs Zn2+/Zn) at 0.05 A g?1 and superior cyclability of 77% retention over 5000 cycles at 0.5 A g?1. The remarkable performance originates from the buffer phase formation of Na0.14TiS2 after chemically presodiating TiS2, which not only improves the structural reversibility and stability but also enhances the diffusion coefficient and electronic conductivity, and lowers cation migration barrier, as evidenced by a series of experimental and theoretical studies. Moreover, an aqueous “rocking‐chair” Zn‐ion full battery is successfully demonstrated by this Na0.14TiS2 anode and ZnMn2O4 cathode, which delivers a capacity of 105 mAh g?1 (for anode) with an average voltage of 0.95 V at 0.05 A g?1 and preserves 74% retention after 100 cycles at 0.2 A g?1, demonstrating the feasibility of Zn‐ion full batteries for energy storage applications. 相似文献
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Shiheng Liu Conggang Zhang Tiantian Su Tiandi Wei Deyu Zhu Kang Wang Yan Huang Yuhui Dong Kun Yin Sujuan Xu Ping Xu Lichuan Gu 《Proteins》2014,82(9):1708-1720
The dibenzothiophene (DBT) monooxygenase DszC, which is the key initiating enzyme in “4S” metabolic pathway, catalyzes sequential sulphoxidation reaction of DBT to DBT sulfoxide (DBTO), then DBT sulfone (DBTO2). Here, we report the crystal structure of DszC from Rhodococcus sp. XP at 1.79 Å. Intriguingly, two distinct conformations occur in the flexible lid loops adjacent to the active site (residue 280–295, between α9 and α10). They are named “open”' and “closed” state respectively, and might show the status of the free and ligand‐bound DszC. The molecular docking results suggest that the reduced FMN reacts with an oxygen molecule at C4a position of the isoalloxazine ring, producing the C4a‐(hydro)peroxyflavin intermediate which is stabilized by H391 and S163. H391 may contribute to the formation of the C4a‐(hydro)peroxyflavin by acting as a proton donor to the proximal peroxy oxygen, and it might also be involved in the protonation process of the C4a‐(hydro)xyflavin. Site‐directed mutagenesis study shows that mutations in the residues involved either in catalysis or in flavin or substrate‐binding result in a complete loss of enzyme activity, suggesting that the accurate positions of flavin and substrate are crucial for the enzyme activity. Proteins 2014; 82:1708–1720. © 2014 Wiley Periodicals, Inc. 相似文献