共查询到20条相似文献,搜索用时 31 毫秒
1.
Electrical transmission in the mammalian brain is now well established. A new study by Thomson and colleagues elegantly demonstrates
coupling between CA1 hippocampal pyramidal cells, which is far more common than previously supposed. Although the history
of coupling is extensive, doubt, predjudice, and technical issues long kept it from wide acceptance. Here “spikelets” or “fast
prepotentials” are found when two cells are coupled and in this situation result from electrical transmission of impulses
from one coupled cell to the other. Interesting questions remain as to whether connexin or pannexin gap junctions serve as
the molecular substrate of transmission, and the role of electrical transmission in hippocampal physiology is uncertain. Increased
coupling could well contribute to the known tendency of the hippocampus to exhibit seizure activity. 相似文献
2.
Sah NK Singh SN Sahdev S Banerji S Jha V Khan Z Hasnain SE 《Journal of biosciences》2005,30(4):499-505
Selaginella bryopteris is a lithophyte with remarkable ressurection capabilities. It is full of medicinal properties, hence also known as ‘Sanjeevani’ (one that infuses life). For lack of credible scientific evidence the plant is not in active use as a medicinal herb. We
provide scientific evidence for whyS. bryopteris is known as ‘Sanjeevani’.
The aqueous extract ofS. bryopteris possesses growth-promoting activity as well as protective action against stress-induced cell death in a number of experimental
cell systems including mammalian cells. Treatment of the cells in culture with 10% aqueous extract enhanced cell growth by
about 41% in Sf9 cells and 78% in mammalian cells. Pre-treatment of cells with the Selaginella extract (SE) (1-2x5%) protected
against oxidative stress (H2O2)-induced cell death. The killing potential of ultra violet (UV) was also significantly reduced
when the cells were pre-treated with SE for 1 h. Thermal radiation suppressed cell growth by about 50%. Pre-treatment of cells
with SE for 1 h afforded complete protection against heat-induced growth suppression. SE may possess anti-stress and antioxidant
activities that could be responsible for the observed effects. Chemical analysis shows that SE contains hexoses and proteins.
Taken together,S. bryopteris extract may help in stress-induced complications including those due to heat shock. 相似文献
3.
Shimpei Uraguchi Masako Kiyono Takuya Sakamoto Izumi Watanabe Katsuji Kuno 《Planta》2009,230(2):267-276
The contributions of cadmium (Cd) accumulation in cell walls, antioxidative enzymes and induction of phytochelatins (PCs)
to Cd tolerance were investigated in two distinctive genotypes of black oat (Avena strigosa Schreb.). One cultivar of black oat ‘New oat’ accumulated Cd in the leaves at the highest concentration compared to another
black oat cultivar ‘Soil saver’ and other major graminaceous crops. The shoot:root Cd ratio also demonstrated that ‘New oat’
was the high Cd-accumulating cultivar, whereas ‘Soil saver’ was the low Cd-accumulating cultivar. Varied levels of Cd exposure
demonstrated the strong Cd tolerance of ‘New oat’. By contrast, low Cd-accumulating cultivar ‘Soil saver’ suffered Cd toxicity
such as growth defects and increased lipid peroxidation, even though it accumulated less Cd in shoots than ‘New oat’. Higher
activities of ascorbate peroxidase (EC 1.11.1.11) and superoxide dismutase (EC 1. 15. 1. 1) were observed in the leaves of
‘New oat’ than in ‘Soil saver’. No advantage of ‘New oat’ in PCs induction was observed in comparison to Cd-sensitive cultivar
‘Soil saver’, although Cd exposure increased the concentration of total PCs in both cultivars. Higher and increased Cd accumulation
in cell wall fraction was observed in shoots of ‘New oat’. On the other hand, in ‘Soil saver’, apoplasmic Cd accumulation
showed saturation under higher Cd exposure. Overall, the present results suggest that cell wall Cd accumulation and antioxidative
activities function in the tolerance against Cd stress possibly in combination with vacuolar Cd compartmentation. 相似文献
4.
5.
This contribution is aimed to give support to ‘bottom-up’ approaches to the minimal or early cell research project. Even if,
from this perspective, the most simple living cell still seems very far away, the analysis of less complex, infrabiological
cellular systems (some of which could be relatively soon implemented in the lab) probably holds the key, or one of the fundamental
keys, to the problem of origins of life. On these lines, we propose a simulation model to study the transition from proto-metabolic
‘lipid’ cells to ‘lipid-peptide’ cells, as a critical step in which self-reproducing vesicles could develop into more functionalized supramolecular systems
Presented at: International School of Complexity – 4th Course: Basic Questions on the Origins of Life; “Ettore Majorana” Foundation and Centre for Scientific Culture, Erice, Italy, 1–6 October 2006. 相似文献
6.
N. Friesen R. Fritsch K. Bachmann 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1997,95(8):1229-1238
Random amplified polymorphic DNA (RAPD) and genomic in situ hybridization (GISH) methods have been used to verify the hybridogenic
origin and to identify the parental species of some ornamental cultivars in the subgenus Melanocrommyum of the genus Allium. The cultivars had been selected from seed obtained after uncontrolled pollination in breeders’ fields. The combination of
GISH analysis with RAPD markers is very suitable for testing the hybridogenic origin of plants and to ascertain the parental
species of the hybrids in such cases. As suspected, A. macleanii and A. cristophii are the parental species of ‘Globemaster’. The parental species of cultivar ‘Globus’ are A. karataviense and A. stipitatum, and not A. cristophii and A. giganteum as has been assumed on morphological grounds. Cultivars ‘Lucy Ball’ and ‘Gladiator’ are of hybrid origin, though only one
of the parental species, A. hollandicum, could be confirmed. The cultivars ‘Purple Sensation’, ‘Mount Everest’, ‘White Giant’, ‘Michael H. Hoog’ and ‘Mars’ are not
hybrids since neither GISH nor RAPD suggest the presence of a second genome. ‘Purple Sensation’ belongs to A. hollandicum, ‘Mount Everest’, ‘White Giant’ and ‘Mars’ to A. stipitatum,‘Michael H. Hoog’ to A. rosenorum.
Received: 3 July 1997 / Accepted: 9 October 1997 相似文献
7.
Summary Anthers and ovaries of six grapevine cultivars (three Vitis vinifera L., two V × Labruscana L. H. Bailey, and one complex hybrid) were extracted from flower buds over 2 yr and cultured on three media reported to promote
somatic embryogenesis in Vitis tissues. The highest percent embryogenesis from the hybrid ‘Chancellor’ and V. vinifera ‘Chardonnay’, ‘Merlot’, and ‘Pinot Noir’ occurred on medium C [Nitsch and Nitsch, 1969, basal medium with 3.0% (w/v) sucrose,
0.01% (w/v) inositol. 0.3% (w/v) Phytagel, 2.5 μM 2.4-dichlorophenoxyacetic acid, 2.5μM β-naphthoxyacetic acid, 5.0μM N-(2-chloro-4-pyridyl)-N′-phenylurea, and 0.05% (w/v) glutamine]. Regardless of the media, the labrusca cultivars ‘Concord’ and ‘Niagara’ produced
soft non-embryogenic callus that was sometimes mixed with well-developed somatic embryos. Nine vinifera genotypes were further
tested for several different years on medium C. Embryogenic cultures suitable for transformation were obtained from all genotypes
in more than 1 yr. The average percent embryogenesis from ovaries was 7-fold higher than from anthers. There was significant
annual variation in percent embryogenesis, demonstrating the need for media comparisons to be replicated for more than one
season. Suspension cultures suitable for use in genetic transformation were initiated from ‘Chardonnay’, ‘Merlot,’ and ‘Pinot
Noir’ pro-embryogenic masses. ‘Chardonnay’ suspension cultures plated and grown under conditions developed for recovery of
plants after biolistic transformation yielded approximately 500 non-transformed embryos per plate after 4 mo. of culture,
with 68.6% of the embryos converting to plants. This is the first reported protocol for embryogenesis from ‘Concord,’ ‘Cabernet
Franc,’ and ‘Pinot Noir’ grapevines. 相似文献
8.
Gerald Kastberger Ronald Thenius Anton Stabentheiner Randall Hepburn 《Journal of Insect Behavior》2009,22(1):65-85
Colony defence in Apis mellifera involves a variety of traits ranging from ‘aggressive’ (e.g. entrance guarding, recruitment
of flying guards) to ‘docile’ (e.g. retreating into the nest) expression. We tested 11 colonies of three subspecies (capensis, scutellata, carnica) regarding their defensiveness. Each colony was selected as reportedly ‘aggressive’, ‘intermediate’ or ‘docile’ and consisted
of about 10,000 bees. We applied three stimulation regimes (mechanical disturbance, exposure to alarm pheromones, and the
combination of both) and measured their behaviours by tracking the rates of outflying bees at the entrance sites of the test
hives. We provided evidence that for mechanical disturbances the test colonies resolved into two response types, if the ‘immediate’
defence response, assessed in the first minute of stimulation, was taken as a function of foraging: ‘releaser’ colonies allocated flying guards, ‘retreater’ colonies reduced the outside-hive activities. This division was observed irrespective
of the subspecies membership and maintained in even roughly changing environmental conditions. However, if pheromone and mechanical
stimulation were combined, the variety of colony defensiveness restricted to two further types irrespective of the subspecies
membership: six of nine colonies degraded their rate of flying defenders with increasing foraging level, three of the colonies
extended their ‘aggressiveness’ by increasing the defender rate with the foraging level. Such ‘super-aggressive’ colonies
obviously are able to allocate two separate recruitment pools for foragers and flying defenders. 相似文献
9.
Martin Maiden 《Morphology》2009,19(1):59-86
This study examines some cases of heteroclisis in the history of Romanian dialects, and concludes that the data call for a
reconsideration of Stump’s distinction (Language 82:279–322, 2006) between ‘cloven’ heteroclisis, where the intraparadigmatic
‘split’ is aligned with some morphosyntactic feature distinction, and ‘fractured’ heteroclisis, where this is not the case
and the pattern of heteroclisis is purely morphological. Stump’s account creates the impression that the ‘cloven’ variety
is universally predominant, and that the ‘fractured’ variety tends to follow very closely the available ‘cloven’ patterns
of the language. I shall suggest, instead, that the ‘fractured-only’ situation may in fact underlie heteroclisis cross-linguistically,
the phenomenon being in general sensitive not directly to morphosyntactic content, but rather to characteristic, and often
purely ‘morphomic’, patterns of stem-allomorphy.
Research for this paper was undertaken as part of the Arts and Humantities Research Council-funded project Autonomous Morphology in Diachrony: comparative evidence from the Romance Languages, currently being conducted at Oxford University. 相似文献
10.
Zhentu Ying Thomas L. Davenport Taifang Zhang Raymond J. Schnell Cecile L. Tondo 《Plant Molecular Biology Reporter》2009,27(3):374-380
‘Hass’ is the most popular avocado (Persea americana Mill.) cultivar in the world. It has been characterized as a crop requiring cross-pollination. However, the potential extent
of self-pollination and the most effective pollen donors (best cross-pollinizing cultivars) have not been determined. In this
study, 56 markers were screened against ‘Hass’ and nine commonly used pollinizing cultivars grown in southern California:
‘Bacon,’ ‘Ettinger,’ ‘Fuerte,’ ‘Harvest,’ ‘Lamb Hass,’ ‘Marvel,’ ‘Nobel,’ ‘Sir Prize,’ and ‘Zutano.’ Seventeen microsatellite,
i.e., simple sequence repeat (SSR) markers, were found to be very promising for paternity analysis. Four highly informative
SSR markers were selected to accurately and unequivocally identify pollen parents of ‘Hass’ fruit from an orchard interplanted
with these pollinizing cultivars. From 2003 to 2006, 7,984 ‘Hass’ fruit were analyzed for their paternity. Overall, the pollen
parents of 99.55% of the analyzed fruit could be unequivocally identified with a single multiplex polymerase chain reaction
(PCR). Only 36 fruits (<0.45%) required a second PCR reaction to reach unequivocal identification of the pollen parents. 相似文献
11.
The purpose of this paper is to investigate the differential responses of flower opening to ethylene in two cut rose cultivars,
‘Samantha’, whose opening process is promoted, and ‘Kardinal’, whose opening process is inhibited by ethylene. Ethylene production
and 1-aminocyclopropane-1-carboxylate (ACC) synthase and oxidase activities were determined first. After ethylene treatment,
ethylene production, ACC synthase (ACS) and ACC oxidase (ACO) activities in petals increased and peaked at the earlier stage
(stage 3) in ‘Samantha’, and they were much more dramatically enhanced and peaked at the later stage (stage 4) in ‘Kardinal’
than control during vasing. cDNA fragments of three Rh-ACSs and one Rh-ACO genes were cloned and designated as Rh-ACS1, Rh-ACS2, Rh-ACS3 and Rh-ACO1 respectively. Northern blotting analysis revealed that, among three genes of ACS, ethylene-induced expression patterns of
Rh-ACS3 gene corresponded to ACS activity and ethylene production in both cultivars. A more dramatic accumulation of Rh-ACS3 mRNA was induced by ethylene in ‘Kardinal’ than that of ‘Samantha’. As an ethylene action inhibitor, STS at concentration
of 0.2 mmol/L generally inhibited the expression of Rh-ACSs and Rh-ACO in both cultivars, although it induced the expression of Rh-ACS3 transiently in ‘Kardinal’. Our results suggests that ‘Kardinal’ is more sensitive to ethylene than ‘Samantha’; and the changes
of Rh-ACS3 expression caused by ethylene might be related to the acceleration of flower opening in ‘Samantha’ and the inhibition in
‘Kardinal’. Additional results indicated that three Rh-ACSs genes were differentially associated with flower opening and senescence as well as wounding. 相似文献
12.
Monica Santa-Maria Kenneth V. Pecota Craig G. Yencho George Allen Bryon Sosinski 《Plant Cell, Tissue and Organ Culture》2009,97(1):109-117
Sweetpotato (Ipomoea batatas L.) is an important crop in North Carolina with annual production of 0.33 million tons, accounting for 37% of total US supply
(USDA, Louisiana Farm Reporter 8(12), August 2008). To target industrial use, novel high-starch industrial-type varieties that contain more than 30% dry matter were developed
by conventional breeding methods. In vitro cultures from selected genotypes were established using meristem culture. To establish
regeneration procedures that could be coupled with transformation experiments, conditions for the induction of rapid shoot-organogenesis
in leaf explants were compared using varying concentrations of the auxins ‘NAA’, ‘IAA’, ‘2,4-D’, and ‘4-FA’ either alone or
in combination with zeatin riboside. Regeneration efficiencies, defined as the number of explants developing shoots out of
the total number tested, were as high as 57% for the best genotypes, with a significant genotype-dependent response observed
in all the hormone regimes evaluated. In all treatments, shoot regeneration was observed within 2 months. Our results led
to the establishment of optimized in vitro regeneration procedures for the novel high-starch sweetpotato (SP) genotypes ‘DM01-158’,
‘FTA94’, ‘FT489’, and ‘PDM P4’ that are rapid and reliable. 相似文献
13.
An earlier theory of cell differentiation and morphogenesis (Wassermann, 1972, 1973, 1978) is combined with the genetic control
model of Davidson and Britten (e.g. 1979). The resulting new theory suggests how, bysystematic process algorithms, specifically enumerated combinations of batteries of structural genes can become switched on in particularly enumerated
cells, via battery-specific enumerable regulator genes. The systematization is idealized. Up to a certain stage of development
in each mitotically arising cell a unique cell-specific combination of structural genes called ‘marker genes’ is active. Marker
genes are assumed to code for cell-specifying marker proteins (CSMPs) which permit cells carrying related markers to recognize
each other, thus permitting specific cell sorting.Batteries of marker genes could ensure great developmental precision and can safeguard—via redundancies of CSMP types—against accidental
loss or detrimental mutational modification of CSMPs or marker genes, respectively. This paper is much concerned with cell
lineage in relation to ‘microdifferentiation’, where ‘microdifferentiation’ of a cell refers to a cell's active marker genes
and its syntheses of CSMPs. A drastic distinction is made between ‘microdifferentiation’ and ‘gross’ differentiation of a
cell, where the same ‘gross’ differentiation may be shared by a large number of cells that could each be uniquely ‘microdifferentiated’.
Typical ‘gross’ differentiation could manifest itself in tissue specificity, whereas, up to certain stages of development,
all cells of the same gross differentiation type (say tissue specificity) could each be uniquely ‘microdifferentiated’. The
theory also assumes that at certain stages of the developmental process some (or in some organisms all) of the previously
uniquely specified cells could give rise to small (or occasionally large) clones of equispecified cells, some of which might
form clusters that represent complete ‘morphogenetic fields’ Tentative implementation mechanisms are proposed which suggest
how the theory could operate in molecular biological terms. In particular, CSMPs could endow cell surface membranes with a
highly specific protein network, and an associated equally specific cell surface coat. It is suggested how these highly specified
cell surface coats and other systems could provide an ‘extracellular guidance network’ which could help to direct cells to
attain energetically optimal locations relative to each other based on the matching of their surface specificities. In numerous
experimental situations, where normally present optimal matching of cells is excluded, ‘alternative matching’ based on experiment-specific
suboptimal matching could explain many data, notably in experimental development neurobiology (Wassermann, 1978). 相似文献
14.
This study analyzed genetic differences of 19 cultivars selected from somaclonal variants of Syngonium podophyllum Schott along with their parents as well as seven additional Syngonium species and six other aroids using amplified fragment length polymorphism (AFLP) markers generated by 12 primer sets. Among the 19 somaclonal cultivars, ‘Pink Allusion’ was selected from ‘White Butterfly’. Tissue culture of ‘Pink Allusion’ through organogenesis resulted in the development of 13 additional cultivars. Self-pollination of ‘Pink Allusion’ obtained a cultivar, ‘Regina Red Allusion’, and tissue culture propagation of ‘Regina Red Allusion’ led to the release of five other cultivars. The 12 primer sets generated a total of 1,583 scorable fragments from all accessions, of which 1,284 were polymorphic (81.9%). The percentages of polymorphic fragments within ‘White Butterfly’ and ‘Regina Red Allusion’ groups, however, were only 1.2% and 0.4%, respectively. Jaccard's similarity coefficients among somaclonal cultivars derived from ‘White Butterfly’ and ‘Regina Red Allusion’, on average, were 0.98 and 0.99, respectively. Seven out of the 15 cultivars from the ‘White Butterfly’ group and three out of six from the ‘Regina Red Allusion’ group were clearly distinguished by AFLP analysis as unique fragments were associated with respective cultivars. The unsuccessful attempt to distinguish the remaining eight cultivars from the ‘White Butterfly’ group and three from the ‘Regina Red Allusion’ group was not attributed to experimental errors or the number of primer sets used; rather it is hypothesized to be caused by DNA methylation and/or some rare mutations. This study also calls for increased genetic diversity of cultivated Syngonium as they are largely derived from somaclonal variants. 相似文献
15.
Ying Li Yuping Song Gongjun Shi Jianjun Wang Xilin Hou 《Acta Physiologiae Plantarum》2009,31(1):155-162
Changes in ascorbic acid content and antioxidant enzyme activities were investigated in non-heading Chinese cabbage (Brassica campestris ssp. chinensis Makino) leaves of ‘Wutacai’ and ‘Erqing’ exposed to excess copper (Cu). Cu treatment reduced the fresh weight of shoot and
root by 57% and 46% in ‘Wutacai’, and 60 and 54% in ‘Erqing’, respectively. The accumulation of copper in leaves was higher
in ‘Wutacai’ than that in ‘Erqing’. Compared to the control, ascorbic acid (AsA) contents were significantly decreased after
copper treatment in both cultivars, while they were higher in ‘Wutacai’ than in ‘Erqing’, which may explain the higher copper-tolerance
of ‘Wutacai’ with higher copper accumulation. The higher AsA contents of ‘Wutacai’ resulted from their lower activities of
degrading enzymes, such as ascorbate oxydase (AAO) and ascorbate peroxidase (APX), as well as the increasing activity of dehydroascorbate
reductase (DHAR) after copper treatment compared with ‘Erqing’. Copper stimulated superoxide dismutase (SOD) activity in both
cultivars, but for catalase (CAT), there was little difference between both cultivars. Peroxidases (POD) activity was decreased
after copper treatment in ‘Erqing’, while in ‘Wutacai’, it was significantly increased at 14 days, and POD activity was higher
in ‘Wutacai’ than that in ‘Erqing’ at 21 and 28 days. Therefore, the induced increasing activity of POD in ‘Wutacai’ also
played an important role in its copper tolerance. 相似文献
16.
Summary A study of the bacterial microflora of muds colonized bySpartina townsendii agg. in healthy and ‘die-back’ sites in the Lymington estuary was made. No important qualitative differences were found between
the microfloras of the two types of site. Fewer species, however, were present in the die-back sites. It is suggested that
under anaerobic conditions, such as occur in a ‘die-back’ site, the bacteria will utilise such oxygen as is present, and will
then engage in anaerobic metabolic processes, producing reduced ions which will reduce the oxidation-reduction potential still
further. The occurrence of abundant sulphate reducers in the ‘die-back’ sites may be particularly significant in this respect.
No evidence was obtained of any more direct relationship between bacterial flora and the development of ‘die-back’. 相似文献
17.
Marielle Merlino Philippe Leroy Christophe Chambon Gérard Branlard 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2009,118(7):1321-1337
Albumins and globulins of wheat endosperm represent 20% of total kernel protein. They are soluble proteins, mainly enzymes
and proteins involved in cell functions. Two-dimensional gel immobiline electrophoresis (2DE) (pH 4-7) × SDS-Page revealed
around 2,250 spots. Ninety percent of the spots were common between the very distantly related cultivars ‘Opata 85’ and ‘Synthetic
W7984’, the two parents of the International Triticeae Mapping Initiative (ITMI) progeny. ‘Opata’ had 130 specific spots while
‘Synthetic’ had 96. 2DE and image analysis of the soluble proteins present in 112 recombinant inbred lines of the F9-mapped
ITMI progeny enabled 120 unbiased segregating spots to be mapped on 21 wheat (Triticum aestivum L. em. Thell) chromosomes. After trypsic digestion, mapped spots were subjected to MALDI-Tof or tandem mass spectrometry for
protein identification by database mining. Among the ‘Opata’ and ‘Synthetic’ spots identified, many enzymes have already been
mapped in the barley and rice genomes. Multigene families of Heat Shock Proteins, beta-amylases, UDP-glucose pyrophosphorylases,
peroxydases and thioredoxins were successfully identified. Although other proteins remain to be identified, some differences
were found in the number of segregating proteins involved in response to stress: 11 proteins found in the modern selected
cultivar ‘Opata 85’ as compared to 4 in the new hexaploid `Synthetic W7984’. In addition, ‘Opata’ and ‘Synthetic’ differed
in the number of proteins involved in protein folding (2 and 10, respectively). The usefulness of the mapped enzymes for future
research on seed composition and characteristics is discussed.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
18.
In vitro induction, regeneration and analysis of autotetraploids derived from protoplasts and callus treated with colchicine in Citrus 总被引:2,自引:0,他引:2
Shao-Hua Zeng Chuan-Wu Chen Liu Hong Ji-Hong Liu Xiu-Xin Deng 《Plant Cell, Tissue and Organ Culture》2006,87(1):85-93
In the present paper attempts were made to induce chromosome doubling of ‘Meiwa’ kumquat (Fortunella crassifolia) protoplasts and ‘Frost’ navel orange (Citrus sinensis Osbeck) embryogenic callus via colchicine treatment. Colchicine decreased protoplast viability, delayed protoplast division and inhibited callus growth, indicating presence of toxicity to cells. Cell lines established from ‘Meiwa’ protoplasts treated with 0.01 and 0.1% colchicine for 8, 16 and 24 h at each concentration showed different responses when they were cultured on embryoid-induction medium. Flow cytometry (FCM) demonstrated that tetraploids were detected in cell lines and embryoids from all of the treatments, with the highest frequency being 19.23%. As for ‘Frost’, tetraploid cells were only detected when the callus was treated with 0.1% colchicine for either 4 or 8 days, from which plantlets were regenerated. FCM and chromosome counting confirmed them as true tetraploids. The diploid cells were more active in mitotic division during a 12-day culture and smaller in size than their tetraploid counterpart. Potential applications of the novel tetraploid germplasms obtained through in vitro chromosome doubling to citrus cultivar improvement are discussed. 相似文献
19.
Wellyzar Sjamsuridzal Yoshito Tajiri Hiromi Nishida Ta Bich Thuan Hiroko Kawasaki Aiko Hirata Akira Yokota Junta Sugiyama 《Mycoscience》1997,38(3):267-280
To study the phylogeny and evolution of archiascomycetes, we determined the full sequence of the nuclear 18S rRNA gene from
14Taphrina species and 2Protomyces species, and the partial sequence ofSchizosaccharomyces japonicus var.japonicus. The sequences were phylogenetically analyzed by the neighbor-joining, maximum parsimony, and maximum-likelihood methods.
We also looked at their principal phenotypic characters and genotypic character. Relationships within the Ascomycota are concordant
with the previously published phylogenies inferred from 18S rDNA sequence divergence and divide the archi-, hemi-and euascomycetes
into distinct major lineages. All the trees show that, within the archiascomycete lineage, 11 of the 14Taphrina species and the 2Protomyces species are monophyletic. A core groups ofTaphrina andProtomyces is always monophyletic. The evidence from molecular and phenotypic characters such as cell wall sugar composition, ubiquinone,
cell wall ultrastructure, and mode of conidium ontogeny, strongly suggests that ‘T’. californica CBS 374.39, ‘T’. maculans CBS 427.69 and ‘T’. farlowii CBS 376.39 should be excluded from the archiascomycete lineage. ‘Taphrina’ farlowii CBS 376.39 groups withCandida albicans in the Saccharomycetales, whereas ‘T’. californica CBS 374.39 and ‘T’. maculans CBS 427.69 have a basidiomycete affinity and group with Tremellalean members in the hymenomycete lineage.Schizosaccharomyces is monophyletic. The strictly anamorphic yeastSaitoella complicata groups with the apothecial ascomyceteNeolecta vitellina rather than theTaphrina/Protomyces branch. 相似文献
20.
W. E. Van de Weg 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1997,94(8):1092-1096
Phytophthora fragariae var. fragariae is the causal agent of red stele (red core) root rot in strawberry (Fragaria spp.). The inheritance of resistance to one isolate of this fungus was studied in 12 segregating populations of F.×ananassa derived from crosses between four resistant cultivars (‘Climax’, ‘Redgauntlet’, ‘Siletz’, and ‘Sparkle’) and three susceptible
cultivars (‘Blakemore’, ‘Glasa’, and ‘Senga’ Sengana’). The analysis clearly supports the hypothesis of a single segregating
dominant resistance gene. It is proposed that this gene be designated Rpf2.
Received 12 November 1996 / Accepted: 22 November 1996 相似文献