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1.
Makoto Mizuno 《Journal of phycology》1987,23(4):591-597
The morphology and sexual reproduction of the attached diatom Cocconeis scutellum Ehr. var. scutellum have been investigated using field and culture materials. The diatom grew well at 14–22° C and in a medium using enriched full strength seawater or 50% diluted seawater. One gamete was formed without cytokinesis in a gametangium and one auxospore arose from paired gametangia. The size of gametangia and initial cells were 17.8–29.9 μm and 43.3–59.5 μm, respectively. Valve width decreased linearly with decreasing valve length. The regression coefficient between them was invariable with the change of the environment. The transapical striation densities were 7–12 and 7.5–13.5 in 10 μm in araphid and raphid valves, respectively. The density showed a tendency to increase with decreasing valve length in both valves. The densities in both valves, except the small araphid valve, are invariable with the change of the environment. The relationships between valve length and width, and between valve length and striation density have been compared with those of taxa allied to C. scutellum var. scutellum. It is concluded that C. scutellum var. scutellum, as usually delimited, is a heterogenous taxon. 相似文献
2.
Aphanomyces sp. was isolated from the carapaces of two juvenile soft-shelled turtles with fungal infections imported from Singapore.
Their sizes were 2.9–3.5 cm in carapace length. Lesions with integumental necrosis and ulceration looked like white cotton.
The fungus exhibited slow growth, hyphae were 7.5–15 μm in diam, coarse, and abundantly branched. Zoosporangia observed in
the isolate were complex, its entire thallus being converted into zoosporangial units, with short or long lateral evacuation
tubes, and isodiametric, 100–500 μm in length. Clusters of zoospores were also produced at the terminals of hyphae. The production
of the primary zoospores was achlyoid. The primary encysted zoospores were spherical, 10–15 μm in diam. No sexual stages were
observed on a hemp seed incubated in sterile tap water. The optimal temperature for the fungus was 30° C. 相似文献
3.
4.
Acetylene reduction and indoleacetic acid production by Azospirillum isolates from Cactaceous plants
Azospirillum isolates were obtained from rhizosphere soil and roots of three cactaceae species growing under arid conditions.
All Azospirillum isolates from rhizosphere and roots ofStenocereus pruinosus andStenocereus stellatus were identified asA. brasilense; isolates of surface-sterilized roots fromOpuntia ficus-indica were bothA. brasilense andA. lipoferum. Azospirilla per g of fresh root in the three species ranged from 70×103 to 11×103. The most active strains in terms of C2H2 reduction (25–49.6 nmol/h·ml) and indoleacetic acid (IAA) production (36.5–77 μg/ml) were those identified asA. brasilense and isolated from Stenocereus roots.A. lipoferum isolated from Opuntia roots produced low amounts of IAA (6.5–17.5 μg/ml) and low C2H2-reduction activity (17.8–21.2 nmol/h·ml). 相似文献
5.
Three color morphotypes of Kappaphycus alvarezii var. adik-adik (brown, green and red) collected from a farming area in Tictauan Is., Zamboanga City, Philippines were used as explants
in the study in order to micropropagate ‘new’ plants. Individual sections of sterile Kappaphycus alvarezii var. adik-adik, initially cultured in a 48-well culture plate containing ESS/2 + E3 + PGR, released callus cells after 4–5 days of incubation
at 23–25°C, 13:11H LD cycle and 10–15 μmol photons m−2 s−1 light intensity. True calli were formed after 29–35 days following dense formation of filaments or undifferentiated round
cells at the medullary and inner cortical layers of the section. Plantlets (2–3 mm long) of Kappaphycus alvarezii var. adik-adik were able to regenerate after 98, 150 and 177 days in-vitro among the reds, greens, and browns, respectively. This study established successful methods for the production and regeneration
of tissue explants of Kappaphycus alvarezii var. adik-adik which can possibly be used to mass produce ‘new’ cultivars for land- and sea-based nurseries as sources for commercial farming.
Presented at the 6th Meeting of the Asian Pacific Society of Applied Phycology, Manila, Philippines. 相似文献
6.
Two clones of Pinnularia brebissonii (Kütz.) Rabh. var. brebissonii were established and maintained in logarithmic phase of growth. Initial length of the cells was 37 μm. As cell division occurred, the mean length of cells in each population decreased as predicted by the MacDonald-Pfitzer hypothesis; however, the decrease in mean length was not uniform throughout the growth period. This nonuniformity is probably caused by nonrandom division of cells in the population or by a changing increment of size reduction due to division. The initial increment of size reduction was calculated as 0.7 μm/division. The smallest, cells observed were 8 μm long. As cells decrease in length, cell volume decreases and the proportion of cells with aberrant valve structure increases. More than 90% of the valves were abnormal in a population with mean length of 14 μm. The abnormalities of structure involved the raphe, the central area and the striae. 相似文献
7.
Ruixiang Zhao Junliang Sun Peter Torley Dahong Wang Shengyang Niu 《World journal of microbiology & biotechnology》2008,24(8):1349-1354
Lactobacillus acidophilus, as a probiotic, is widely used in many functional food products. Microencapsulation not only increases the survival rate
of L. acidophilus during storage and extends the shelf-life of its products, but also optimal size microcapsule makes L. acidophilus have an excellent dispersability in final products. In this paper, L. acidophilus was microencapsulated using spray drying (inlet air temperature of 170°C; outlet air temperature of 85–90°C). The wall materials
used in this study were β-cyclodextrin and acacia gum in the proportion of 9:1 (w/w), and microcapsules were prepared at four
levels of wall materials (15, 20, 25 and 30% [w/v]) with a core material concentration of 6% (v/v). The microcapsule diameters
were measured by Malvern’s Mastersizer-2000 particle size analyzer. The results showed that the particle diameters of microcapsule
were mostly within 6.607 μm and 60.256 μm and varied with 2.884–120.226 μm (the standard smaller microcapsule designated as
<350 μm). Through comparison of microcapsule size and uniformity with different concentration of wall materials, we concluded
that the optimal concentration of wall material was 20% (w/v), which gave microcapsule with a relatively uniform size (averaging
22.153 μm), and the number of surviving encapsulated L. acidophilus was 1.50 × 109 c.f.u./ml. After 8 weeks storage at 4°C, the live bacterial number was above 107 c.f.u./ml, compared with unencapsulated L. acidophilus, 104–105 c.f.u./ml. Through the observation of scanning electron microscopy, we found that the shapes of microcapsule were round and
oval, and L. acidophilus cells located in the centre of microcapsule. 相似文献
8.
Summary Turfgrass, like other major crop species, is recalcitrant to manipulation in vitro. To perform efficient genetic transformation of turfgrass, it is necessary to optimize tissue culture conditions. In most
reports, plant tissue culture techniques have been applied to propagate a single cultivar or several cultivars in one species
of turfgrass. In this experiment, four turfgrass genera were used, namely common bermudagrass, Cynodon dactylon [L.] Pers. (California origin); red fescue, Festuca rubra L. var. rubra ‘Shadow’; perennial ryegrass, Lolium perenne L. ‘Barbal’; and Kentucky bluegrass, Poa pratensis L. ‘Merion.’ Mature seeds were surface-sterilized and cultured on basal Murashige and Skoog (MS) media supplemented with
30–250 μM 2,4-dichlorophenoxyacetic acid (2,4-D) for callus induction. Regeneration media consisted of MS supplemented with 5–10 μM 6-benzyladenine (BA). Among the genera, Poa had the higest callus induction percentage (CIP) regardless of 2,4-D concentration, followed by Cynodon, Lolium, and Festuca, respectively. Cynodon and Lolium had the highest callus regeneration percentage (CRP) and overall regeneration rate (ORR). Festuca had a poor CIP, CRP, and ORR compared to other studied genera. Cynodon produced the highest shoot number per explant. Based on the results of the present study, MS medium supplemented with 60
μM 2,4-D (for callus induction) and 7.5 μM BA (for regeneration) can be used in multi-generic transformation studies with the genera used. 相似文献
9.
C. P. Kaviraj G. Kiran R. B. Venugopal P. B. Kavi Kishor Srinath Rao 《In vitro cellular & developmental biology. Plant》2006,42(2):134-138
Summary This study reports a protocol for plant regeneration from cultured explants of green gram [Vigna radiata (L.) Wilezek] via somatic embryogenesis. Somatic embryos were induced from nature cotyledons of var., TAP-7 and Pusa Baisaki
when cultured on Murashige and Skoog (MS) medium fortified with different concentrations of 2,4-dichlorophenoxyacetic acid,
α-naphthaleneacetic acid (NAA) and 2,4,5-trichlorophenoxyacetic acid singly or in combination with 2.22–8.88 μM N
6-benzylaminopurine (BAP) or 2.32–9.38 μM kinetin. The type and concentration of auxin and plant genotype influenced the frequency of somatic embryogenesis. NAA was
the most effective auxin for somatic embryo induction. The well-developed, cotyledonary shaped embryos of var. TAP-7 germinated
into plantlets at a frequency of 56.6% on MS medium supplemented with 1.88 μM abscisic acid and 6.66 μM BAP. Regenerated plants were transferred to soil and grown to maturity with 90% survival. The protocol described here offers
a good potential for genetic improvement using gene transfer techniques and the production of synthetic seeds of V. radiata. 相似文献
10.
Zhao W Weber C Zhang CL Romanek CS King GM Mills G Sokolova T Wiegel J 《Extremophiles : life under extreme conditions》2006,10(4):337-345
A novel thermophilic, alkali-tolerant, and CO-tolerant strain JW/WZ-YB58T was isolated from green mat samples obtained from the Zarvarzin II hot spring in the Uzon Caldera, Kamchatka (Far East Russia). Cells were Gram-type and Gram stain-positive, strictly aerobic, 0.7–0.8 μm in width and 5.5–12 μm in length and produced terminal spherical spores of 1.2–1.6 μm in diameter with the mother cell swelling around 2 μm in diameter (drumstick-type morphology). Cells grew optimally at pH25°C 8.2–8.4 and temperature 50–52°C and tolerated maximally 6% (w/v) NaCl. They were strict heterotrophs and could not use either CO or CO2 (both with or without H2) as sole carbon source, but tolerated up to 90% (v/v) CO in the headspace. The isolate grew on various complex substrates such as yeast extract, on carbohydrates, and organic acids, which included starch, d-galactose, d-mannose, glutamate, fumarate and acetate. Catalase reaction was negative. The membrane polar lipids were dominated by branched saturated fatty acids, which included iso-15:0 (24.5%), anteiso-15:0 (18.3%), iso-16:0 (9.9%), iso-17:0 (17.5%) and anteiso-17:0 (9.7%) as major constituents. The DNA G+C content of the strain is 45 mol%. Phylogenetic analyses based on 16S rRNA gene sequences revealed that strain JW/WZ-YB58T is distantly (<93% similarity) related to members of Bacillaceae. On the basis of 16S rRNA gene sequence, physiological and phenotypic characteristics, the isolate JW/WZ-YB58T (ATCC BAA-1258; DSM 17740) is proposed to be the type strain for the type species of the new taxa within the family Bacillaceae, Thermalkalibacillus uzoniensis gen. nov. sp. nov. The Genbank accession number for the 16S rRNA gene sequence is DQ221694.The Genbank accession number for the 16S rRNA gene sequence of strain JW/WZ-YB58T is DQ221694. 相似文献
11.
Vi Khanh Truong Stuart Rundell Rimma Lapovok Yuri Estrin James Y. Wang Christopher C. Berndt David G. Barnes Christopher J. Fluke Russell J. Crawford Elena P. Ivanova 《Applied microbiology and biotechnology》2009,83(5):925-937
The influence of the ultrafine crystallinity of commercial purity grade 2 (as-received) titanium and titanium modified by
equal channel angular pressing (modified titanium) on bacterial attachment was studied. A topographic profile analysis of
the surface of the modified titanium revealed a complex morphology of the surface. Its prominent micro- and nano-scale features
were 100–200-nm-scale undulations with 10–15 μm spacing. The undulating surfaces were nano-smooth, with height variations
not exceeding 5–10 nm. These surface topography characteristics were distinctly different from those of the as-received samples,
where broad valleys (up to 40–60 μm) were detected, whose inner surfaces exhibited asperities approximately 100 nm in height
spaced at 1–2 μm. It was found that each of the three bacteria strains used in this study as adsorbates, viz. Staphylococcus aureus CIP 68.5, Pseudomonas aeruginosa ATCC 9025 and Escherichia coli K12, responded differently to the two types of titanium surfaces. Extreme grain refinement by ECAP resulted in substantially
increased numbers of cells attached to the surface compared to as-received titanium. This enhanced degree of attachment was
accompanied with an increased level of extracellular polymeric substances (EPS) production by the bacteria.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
12.
Morphological and Genetic Characterization of <Emphasis Type="Italic">Saimiri boliviensis</Emphasis>
Eliana Ruth Steinberg Mariela Nieves Marina Sofía Ascunce Ana María Palermo Marta Dolores Mudry 《International journal of primatology》2009,30(1):29-41
The taxonomy of Saimiri is controversial because morphological characteristics, traditionally used for identification, are insufficient to distinguish
species and subspecies. Genetic studies of specimens become relevant for captive management, especially considering their
frequently unknown geographical origin. We analyzed phenotypic and genetic parameters in Saimiri spp. in Argentinean zoological gardens and biological stations to provide a more accurate taxonomic identification. We studied
27 males and 19 females of Saimiri spp. The cytogenetic analysis in mitotic metaphases corroborated a modal number of 2N = 44, XX/XY, and FN = 75 for males
and FN = 76 for females. G- and C-bands, fluorescence in situ hybridization (FISH) and the pelage coloration pattern of all the specimens corresponded to Saimiri boliviensis boliviensis. We characterized for the first time the sperm cell morphology and morphometry (mean ± SE): total length: 71.39 ± 5.40 μm;
head length: 5.71 ± 0.81 μm; head width: 3.76 ± 0.70 μm; acrosome length: 3.70 ± 0.82 μm; midpiece length: 12.20 ± 2.22 μm.
Researchers can use the characterization of the sperm morphology as another parameter for taxonomic identification that, together
with cytogenetic and molecular ones, would allow a more precise identification of individual Saimiri boliviensis boliviensis. 相似文献
13.
Vinod Kumar Ashwani Sharma Bellur Chayapathy Narasimha Prasad Harishchandra Bhaskar Gururaj Parvatam Giridhar Gokare Aswathanarayana Ravishankar 《Acta Physiologiae Plantarum》2007,29(1):11-18
Direct shoot bud induction and plant regeneration was achieved in Capsicum frutescens var. KTOC. Aseptically grown seedling explants devoid of roots, apical meristem and cotyledons were inoculated in an inverted
position in medium comprising of Murashige and Skoog (Physiol Plant 15:472–497, 1962) basal medium supplemented with 2-(N-morpholine) ethanesulphonic acid buffer along with 2.28 μM indole-3-acetic acid, 10 μM silver nitrate and either of 13.31–89.77 μM
benzyl adenine (BA), 9.29–23.23 μM kinetin, 0.91–9.12 μM zeatin, 2.46–9.84 μM 2-isopentenyl adenine. Profuse shoot bud induction
was observed only in explants grown on a media supplemented with BA (26.63 μM) as a cytokinin source and 19.4 ± 4.2 shoot
buds per explant was obtained in inverted mode under continuous light. Incorporation of polyamine inhibitors in the culture
medium completely inhibited shoothoot bud induction. Incorporation of exogenous polyamines improved the induction of shoot
buds under 24 h photoperiod. These buds were elongated in MS medium containing 2.8 μM gibberellic acid. Transfer of these
shoots to hormone-free MS medium resulted in rooting and rooted plants were transferred to fields. This protocol can be efficiently
used for mass propagation and presumably also for regeneration of genetically transformed C. frutescens. 相似文献
14.
15.
Kensuke Toyoda David M. Williams Jiro Tanaka Tamotsu Nagumo 《Phycological Research》2006,54(3):173-182
The present study clarifies the fine structure of the vegetative frustules, initial valves and perizonium of Achnanthes crenulata Grunow. The valves of the vegetative cell are distinctly linear‐lanceolate with an undulate margin. The valve face is quite flat and in girdle view is smoothly curved as in species of Gephyria (Bacillariophyceae). However, the valve face of the initial cells is slightly rounded and does not have an undulate margin. Furthermore, the rapheless sternum is centrally positioned along the apical axis of the araphid initial valve. As this taxon develops from auxospore to initial valve, it forms only longitudinal perizonial bands; no transverse bands arise. The perizonium consists of three silicified bands: one large, central longitudinal plate and two bands that underlie this plate; these two bands are either open or closed. This taxon has several conspicuous structures compared to other marine species of Achnanthes, but the structure of the perizonium supports the position of A. crenulata within Achnanthes sensu stricto. 相似文献
16.
A new species of Hirsutella, H. proturicola, isolated from a subterranean proturan (Baculentulus densus; Protura, Hexapoda), is described and illustrated. Hirsutella proturicola is characterized by producing monoblastic phialides of 24–51.5 × 2.5–5 μm with a slightly roughened neck, fusiform and curved
conidia of 9–18 × 2.5–4 μm that have a truncate base and a papillate projection often capped with sheath-like mucilage, and
pluricellular, globose to subglobose chlamydospores of 21–48 × 21–41.5 μm. This species is morphologically and phylogenetically
close to H. rostrata, an acaropathogenic species, but can be distinguished from the size of the phialides and the size and shape of the conidia. 相似文献
17.
Callus induction and thallus regeneration from callus of phycocolloid yielding seaweeds from the Indian coast 总被引:1,自引:0,他引:1
The tissue culture of phycocolloid yielding seaweeds included preparation of axenic explants, callus induction, subculture
of excised callus and regeneration of plantlets from pigmented callus in the laboratory. Treatment of algal material with
0.1–0.5% detergent for 10 min and 1–2% betadine for 1–5 min and 3–5% antibiotic treatment for 48–72 h successively enabled
viable axenic explants to be obtained as high as 60% for Gracilaria
corticata, Sargassum
tenerrimum and Turbinaria
conoides and 10% for Hypnea
musciformis. Callus induction was more conspicuous in T. conoides than in the other three species investigated. Of the irradiances investigated, 30 μmol photons m−2 s−1 produced calluses in as many as 40% explants in G. corticata and T. conoides and 10% in H. musciformis and S. tenerrimum. The explants cultured at 5 and 70 μmol photons m−2 s−1 did not produce any callus in all the species studied except for H. musciformis in which 10% explants developed callus at 5 μmol photons m−2 s−1. Most of the species investigated showed uniseriate filamentous Type of growths and buds from cut ends and from all over
the surface of explants. Nevertheless, T. conoides had three Types of callus developments, namely (1) uniseriate filamentous Type of outgrowths from the centre of the cut end
of explant, (2) bubbly Type of callus and (3) club-shaped callus clumps. The subculture of T. conoides callus embedded in 0.4% agar produced two Types of filamentous growth, namely filiform (with elongated cells) and moniliform
filaments (with round cells) in the 2 months period after inoculation. Further, friable callus with loose cells was also found
associated with excised callus. The moniliform filaments showed prolific growth of micro-colonies resembling to somatic embryo-like
growth which, in liquid cultures, differentiated and developed into propagules with deformed shoots and distinct rhizoids.
The shoots of these propagules remained stunted with abnormal leaf stalks without forming triangular shaped leaves as the
parental plant and rhizoids had prolific growth in the laboratory cultures. The excised callus of G. corticata continued to grow when transferred to liquid cultures and showed differentiation of new shoots within 10 days. The shoots
grew to a maximum length of 5–6 cm in the 2 months period in aerated cultures in the laboratory.
Dedicated to the memory of Late Dr. Rangarajan. 相似文献
18.
Growth and sexual reproduction of the marine littoral diatom Cocconeis scutellum Ehrenb. var. ornata Grun. were investigated at 30 different combinations of temperature (5, 10, 14, 18, 22° C), irradiance (20, 60, 100 μE·m?2·s?1) and daylength (14:10 and 10:14 h LD cycle). Growth occurred at all combinations. The optimal growth was observed at 14–18° C, long daylength and highest-to-moderate irradiance, and at 18° C, short daylength and highest irradiance. Sexual reproduction on the other hand occurred between 5 and 18° C, and the optimal condition was 10–14° C and short daylength. Annual cyclic, and sesonal changes in the distribution of cell size (valve length) were observed in a field population. These changes were characterized by an annual minimum in mean cell size in autumn, an annual maximum in winter, a slight decrease from the mean in spring–middle summer, a rapid decrease from the mean in late summer–early autumn, and appearance of bimodal distribution of cell size in winter. These changes were caused by sexual reproduction in autumn, rapid growth in late summer–early autumn and slow growth in other seasons, and poor viability of small cells near the lower end of the size range. 相似文献
19.
Andres Jaanus Susanna Hajdu Seppo Kaitala Agneta Andersson Kaire Kaljurand Iveta Ledaine Inga Lips Irina Olenina 《Hydrobiologia》2006,554(1):137-146
During the latest years medium-sized (15–30 μm), single-celled dinoflagellates have been reported to form blooms in the northern
Baltic Proper and the Gulf of Finland in winter and spring. Recent studies (Kremp et al., 2003. Proceedings of the 7th International conference of Modern and Fossil Dinoflagellates, September 21–25, Nagasaki, Japan,
66 pp.) indicate that those blooms are caused by two isomorphic species – Scrippsiella hangoei (Schiller) Larsen, and a new species, tentatively belonging to the genus Woloszynskia. Until now there has been no report on how widely distributed these phytoplankton species are in the Baltic Sea. In this
study, the occurrence of Scrippsiella/Woloszynskia complex in the entire Baltic Sea was investigated, by using monitoring data from 1997 to 2003. The species occurred in a
salinity range from 2 to 8 PSU. Highest concentrations were observed at salinity 4.5–6.5 PSU. Maximum cell densities of Scrippsiella/Woloszynskia complex in the water column were mainly obtained in April or in the beginning of May by the water temperature <3 °C prior
to stratification was formed. In the central Gulf of Finland, the second maximum was found in 1999 and 2002 by the temperature
>6 °C. Bloom formations in the Baltic Proper and in the Gulf of Finland may not only be explained by optimum temperature and
salinity, but also with other factors e.g. high nutrient concentrations and good seeding conditions from the sediments. 相似文献
20.
Pradeep K. Agarwal Rajinder S. Ranu 《In vitro cellular & developmental biology. Plant》2000,36(5):392-397
Summary The in vitro plant regeneration potential of vegetatively propagated geraniums (Pelargonium x hortorum) has been investigated. Using various combinations of growth regulators and a choice of different explants, a regeneration
protocol has been developed to raise in vitro plantlets from young petiole and leaf explants from three different cultivars of geraniums. In all three cultivars, very
young petiole explants exhibited a higher regeneration potential as compared with leaf explants. Regeneration efficiencies
were found to be highly dependent on the cultivar, with cv. Samba showing the highest regeneration potential, followed by
cvs. Yours Truly and then Sincerity. Samba also showed the highest number of shoots from both the petiole [57 shoot buds per
petiole explant in the presence of 3 μM zeatin and 1 μM indole-3-acetic acid (IAA) and leaf explants (43 shoots per leaf explant with 10 μM zeatin and 2 μM IAA). Shoot buds transferred to Murashige and Skoog (MS) medium supplemented with 0.44 μM N6-benzyladenine and 0.11 μM IAA grew vigorously and attained 1–2 cm in length in 3–4 wk. These shoots rooted with 100% efficiency on MS basal medium,
and plants developed that showed normal growth and flowering under greenhouse conditions. 相似文献