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1.
P. G. Mantle 《The Annals of applied biology》1969,63(3):425-434
Isolates from C. purpurea sclerotia occurring naturally on Phragmites communis usually sporulated vigorously on the culture medium employed, and their failure to produce alkaloid in vitro was associated with a thin white growth form. Such isolates also failed to produce sclerotia on the host plants tested. A variant having a plectenchymatic morphology in vitro and producing a thick pigmented non-sporulating growth form yielded alkaloid (up to approximately 300μg/ml mainly δ8–9 and δ9–10 lysergic acids and chanoclavine) in surface or submerged culture and developed typical ergot sclerotia (containing 0·2-0·4% alkaloid, mainly ergotoxine and ergotamine) in vivo. Improved alkaloid yield in vitro was obtained from a strain reselected after passing through a parasitic phase. Aetiological aspects of the P. communis ergot are discussed. 相似文献
2.
Colonies of Pseudomonas aeruginosa exhibit sectors that were shown to be located at specific intervals within the colony. Maxima in the distribution of sectors
were observed every 5 mm as measured from the center of the colony. These maxima correlated with changes in the expansion
rates of colonies. The absolute average number of sectors per colony was higher for colonies grown at higher temperatures.
These results increase our understanding of colony pattern formation.
Received: 2 February 1999 / Accepted: 7 April 1999 相似文献
3.
Ullrich Keller 《Applied microbiology》1983,46(3):580-584
Claviceps purpurea ATCC 20102, which is aconidial under laboratory conditions, was grown in submerged culture in the presence of mutagens and various nutritional additives. Protoplasts from such cultures were prepared and regenerated on solid medium to obtain colonies from single cell units. Frequencies of auxotrophs and high alkaloid producers were on the order of 1 to 2%. Some of the auxotrophic mutants derived from strain ATCC 20102 were constantly segregating prototrophs. High-alkaloid-producing derivatives showed sclerotia-like morphology and violet-brown pigmentation, in contrast to the parent strain; some of them also showed segregation sectors when grown as giant colonies. Mutagenesis of strain 1029, isolated during this study and having an increased level of alkaloid synthesis and sclerotia-like cell morphology, was done in the same fashion as with the original parent strain, ATCC 20102. Mutants obtained from this strain were all stable with respect to their genotypes. However, a large proportion of colonies derived from regenerated protoplasts, even in the mutagen-free controls, showed a lowered level of alkaloid production and were morphologically more similar to the original wild type, ATCC 20102. The influence of protoplast preparation or regeneration or both on the stability of genes involved in differentiation is discussed. 相似文献
4.
In many species of eusocial Hymenoptera, conflict about the production of males is resolved through “policing.” Recent studies
in wasps and the ant Temnothorax unifasciatus suggest that in these species policing workers are dominant themselves and selfishly increase their own chances of later
becoming fertile. Policing may therefore to some extent be associated with dominance and selfishness, and dominance and policing
behaviour are indeed difficult to distinguish and often not mutually exclusive. Moreover, selfish policing requires that workers
form rank orders already in the presence of the queen. Here, we try to allocate aggressiveness by workers towards policing
and/or dominance behaviour and investigate whether hierarchies based on subtle, non-aggressive interactions exist in queenright
colonies of the ant T. unifasciatus. We either split colonies into a queenright and queenless halve or temporarily removed the queen from complete colonies,
which in both cases allows a few dominant workers to lay eggs in the queenless colony. Reunification of colony halves and
return of the queen to orphaned colonies led to aggression against those workers that had become fertile during the absence
of the queen. Dominant workers in reunited, split colonies were more severely attacked than those in orphaned colonies after
return of the queen. Furthermore, we observed that workers, which later became dominant egg layers under queenless conditions,
have more contact with the queen than other workers. Both results corroborate the existence of rank relationships among workers
in queenright colonies and show that results from policing experiments may be affected by the disturbance of pre-existing
hierarchies through colony splitting. 相似文献
5.
Optimal colony size in eusocial insects likely reflects a balance between ecological factors and factors intrinsic to the
social group. In a seminal paper Michener (1964) showed for some species of social Hymenoptera that colony production of immature
stages (productivity), when transformed to a per-female basis, was inversely related to colony size. He concluded that social
patterns exist in the social insects that cause smaller groups to be more efficient than larger groups. This result has come
to be known as “Michener’s paradox” because it suggests that selection on efficiency would oppose the evolution of the large
and complex societies that are common in the social insects. Michener suggested that large colony size has other advantages,
such as improved defense and homeostasis, that are favored by selection. For his analysis of swarm-founding wasps, Michener
combined data from colonies of different species and different developmental stages in order to obtain adequate sample sizes;
therefore, his study did not make a strong case that efficiency decreases with increasing colony size (across colonies) in
these wasps. We tested Michener’s hypothesis on the Neotropical swarm-founding wasp Parachartergus fraternus, while controlling for stage of colony development. We found that small colonies were more variable in percapita productivity
relative to larger colonies, but found no evidence for a negative relationship between efficiency and size across colonies.
Received 1 February 2006; revised 5 May 2006; accepted 11 May 2006. 相似文献
6.
Colony age and size can be poorly related in scleractinian corals if colonies undergo fission to form smaller independent
patches of living tissue (i.e., ramets), but the implications of this life-history characteristic are unclear. This study
explored the ecological consequences of the potential discrepancy between size and age for a massive scleractinian, first
by testing the effect of colony origin on the growth of small colonies, and second by quantifying the contribution of ramets
to population structure. Using Siderastrea siderea in St. John (US Virgin Islands) as an experimental system, the analyses demonstrated that the growth of small colonies derived
from sexual reproduction was 2.5-fold greater than that of small ramets which were estimated to be ≈100 years older based
on the age of the parent colonies from which they split. Although fission can generate discrete colonies, which in the case
of the study reef accounted for 42% of all colonies, it may depress colony success and reef accretion through lowered colony
growth rates. 相似文献
7.
As a contribution to the occurrence of ergot alkaloids in ergot from German rye and triticale, samples from the 2007 and 2008
harvests were analyzed. Twelve alkaloids—six pairs of main alkaloids and their corresponding epimers—were determined in extracts
prepared under alkaline conditions by HPLC with fluorescence detection without preceding purification. The total alkaloid
content was found to be 0.03–0.18% in ergot from rye (n = 19) and 0.06–0.22% in ergot from triticale (n = 4), respectively. Furthermore, single sclerotia (n = 40) were investigated in terms of alkaloid content and distributional pattern. The main alkaloids in ergot were ergocristine,
ergotamine and ergocornine, although the alkaloid composition was highly variable.
Presented in part at the 30th Mykotoxin-Workshop, Utrecht, The Netherlands, April 28–30, 2008 相似文献
8.
Viable protoplasts of Taxus yunnanensis were isolated from friable, light yellow callus. Protoplast yield was dependent on callus age, with a maximum from 20-day-old
callus. Protoplasts were induced to undergo sustained divisions and to form cell colonies when cultured in medium consisting
of B5 salts, KM vitamin and organic components, 0.45 M fructose, 3.0 mg l-1 2,4-dichlorophenoxyacetic acid and 0.1 mg l-1 kinetin. The planting density was 2.5–3.0×105 protoplasts per ml of culture medium. Cell-free extract from callus enhanced protoplast division and the highest plating
efficiency was about 7%. Protoplast-derived colonies showed significant variations in both growth and paclitaxel content.
A negative correlation existed between paclitaxel accumulation in colonies and their growth to some extent (r = −0.4485).
Among 70 colonies isolated from the heterogeneous protoplast cultures, colony TY-7 accumulated the highest paclitaxel content.
Paclitaxel accumulation in colony TY-7 was not great enough to produce paclitaxel for commercial purposes, however, success
in inducing colony formation from T. yunnanensis protoplasts provides an opportunity to obtain cell lines with high paclitaxel productivity from mutagenized protoplast cultures.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
9.
Fusion to form a chimera has been documented in many marine invertebrate taxa, including poriferans, cnidarians, bryozoans, and colonial ascidians. Allogenic interactions in chimeric ascidian colonies vary widely across taxonomic groups but are poorly characterized in the invasive colonial ascidian Didemnum vexillum. The moderate level of discrimination expressed in the fusion–rejection response of D. vexillum suggests that there is some integration of cells beyond the fusion line in a chimeric colony. We tracked the shifts in representation of microsatellite alleles between fused colonies of D. vexillum to elucidate the extent of genotypic integration in fused colonies and the patterns of changes to the genotypic composition of colonies immediately following chimera formation. By genotyping colonies before and after fusion, we found that allogeneic fusion in D. vexillum may lead to genotypic changes beyond the visible fusion line. Alleles from one colony were found in multiple tissue samples in the chimera 7–10 days after fusion had occurred. In some instances, alleles that were in a single colony prior to fusion were lost following fusion. We observed multiple patterns of allelic change, including both the unidirectional transfer and reciprocal exchange of alleles between fused colonies. Our findings suggest that tissue or cells are exchanged following allogeneic fusion between colonies of D. vexillum and that the genotypic composition of chimeric colonies may be fluid. 相似文献
10.
Tomasz W?odarczyk 《Journal of Insect Behavior》2012,25(2):105-113
It was examined whether Formica polyctena and F. sanguinea ants from a mixed colony elicit higher levels of aggression of conspecific ants in comparison to ants from homospecific colonies.
Individuals were confronted in an experimental arena and their behavior was recorded. It was found that F. polyctena workers behaved more aggressively toward ants from a mixed colony. This pattern, however, was not confirmed in F. sanguinea. Moreover, both species clearly discriminated between conspecific and allospecific ants from a mixed colony. It seems that
as a result of social interactions both species exchanged cuticular hydrocarbons, which caused their recognition labels to
adjust to some extent. Results of the present study support the idea that that F. sanguinea is able to form mixed colonies in which species-specific recognition cues are probably still retained. 相似文献
11.
Role of weed grasses in the etiology of ergot disease in wheat 总被引:1,自引:0,他引:1
Forty isolates of the ergot fungus Claviceps purpurea collected from nineteen gramineous host species were used to inoculate male-sterile wheat. The isolates segregated into highly and weakly infective groups. The marked pathogenicity, on wheat, of the fungal strains occurring on certain grass species has been correlated with distinctive patterns of alkaloids within the sclerotia. Analysis of the alkaloid content of 241 samples of naturally occurring ergot sclerotia from twenty gramineous host species has confirmed the existence of host restricted strains characterized also by their particular spectra of alkaloids. Similarity of the alkaloid spectra of ergot sclerotia from blackgrass (Alopecurus myosuroides) and wheat, ease of cross-infection from blackgrass to wheat and an association between blackgrass infestation and the occurrence of ergot sclerotia in surveyed wheat crops have confirmed the hypothesis that the presence of this early flowering weed grass increases the risk of high levels of ergot infection in wheat. 相似文献
12.
The presence of the stoloniferous hydroid Obelia geniculata (L.) had no effect on the pigment concentration or nitrogen status of underlying blade tissue of the giant kelp Macrocystis pyrifera (L.) C. Agardh. The sheet-like colonies of the bryozoan Membranipora membranacea (L.) markedly reduced the pigment concentration of colonized blade tissue, but only during winter. Reductions in pigment
concentration are most likely a result of damage to underlying tissue due to some factor related to the presence of bryozoan
colonies on blade surfaces. Blade tissue colonized by M. membranacea also had higher δ15N signatures than surrounding bryozoan-free tissue, possibly indicating the provision of nitrogen to M. pyrifera by bryozoan colonies. Results show that seasonal changes in nitrogen and colony size can strongly modify the effect of epifauna
on macroalgae they colonize. Unlike bryozoans, hydroid colonies provided no barrier to nitrogen uptake by colonized M. pyrifera tissue and enhanced ammonium uptake was observed for tissue colonized by O. geniculata during nitrogen limitation. Epifauna with stoloniferous growth forms such as hydroids are more likely to have benign or even
mutualistic relationships with macroalgae they colonize than the sheet-like colonies of bryozoans. 相似文献
13.
João D. Santos Christoph F. J. Meyer Carlos Ibáñez Ana G. Popa‐Lisseanu Javier Juste 《Ecology and evolution》2016,6(22):8193-8204
For elusive mammals like bats, colonization of new areas and colony formation are poorly understood, as is their relationship with the genetic structure of populations. Understanding dispersal and group formation behaviors is critical not only for a better comprehension of mammalian social dynamics, but also for guiding conservation efforts of rare and endangered species. Using nuclear and mitochondrial markers, we studied patterns of genetic diversity and differentiation among and within breeding colonies of giant noctule bats (Nyctalus lasiopterus), their relation to a new colony still in formation, and the impact of this ongoing process on the regionwide genetic makeup. Nuclear differentiation among colonies was relatively low and mostly nonsignificant. Mitochondrial variation followed this pattern, contrasting with findings for other temperate bat species. Our results suggest that this may indicate a recent population expansion. On average, female giant noctules were not more closely related to other colony members than to foreign individuals. This was also true for members of the newly forming colony and those of another, older group sampled shortly after its formation, suggesting that contrary to findings for other temperate bats, giant noctule colonies are not founded by relatives. However, mother–daughter pairs were found in the same populations more often than expected under random dispersal. Given this indication of philopatry, the lack of mitochondrial differentiation among most colonies in the region is probably due to the combination of a recent population expansion and group formation events. 相似文献
14.
球形棕囊藻(Phaeocystis globosa)是中国近海海区常见有害藻华原因种, 其异型生活史中包含单细胞和球形囊体两种形态。游离单细胞直径一般为几微米, 囊体最大直径可达3 cm, 巨大的体积可能导致囊体具有特殊的结构和细胞分布。以球形棕囊藻汕头株为研究对象, 测定了囊体直径、囊体细胞丰度和游离单细胞丰度, 并探讨球形棕囊藻囊体形态与细胞分布的关系。研究结果表明, 囊体形态在其异型生活史中占优势, 囊体对生物量的贡献介于38%–95%之间, 在对数生长期的后期和稳定期, 囊体细胞与单细胞相比占绝对优势。囊体细胞数量与囊体直径的对数呈线性相关, 回归线斜率为1.34, 该值显著低于世界海区其它球形棕囊藻株系的研究结果, 表明汕头株单位囊体表面上分布的细胞数更少。中国海区的球形棕囊藻囊体结构和细胞分布与其它株系不同, 在爆发球形棕囊藻的海区, 巨大的囊体能够有效地抵御摄食, 可能对区域海洋食物链结构和功能有重要影响。 相似文献
15.
Krzywda A Petelenz E Michalczyk D Płonka PM 《Cellular & molecular biology letters》2008,13(1):130-143
Acellular (true) slime moulds (Myxomycetes) are capable of a transition to the stage of sclerotium — a dormant form of plasmodium produced under unfavourable environmental
conditions. In this study, sclerotia of Fuligo septica were analyzed by means of electron paramagnetic resonance (EPR) spectroscopy. The moulds were cultivated in vitro on filter paper, fed with oat flour, and kept until the plasmodia began to produce sclerotia. The obtained sclerotia differed
in colour from yellow through orange to dark-brown. The EPR spectra revealed a free radical, melanin-like signal correlated
with the depth of the colour; it was strongest in the dark sclerotia. Sclerotization only took place when the plasmodia were
starved and very slowly dried. Only the yellow sclerotia were able to regenerate into viable plasmodia. This suggests that
myxomycete cytoplasm dehydration is an active process regulated metabolically. Plasmodial sclerotization may therefore serve
as a convenient model system to study the regulation of cytoplasmatic water balance, and sclerotia as a convenient material
for EPR measurements, combining the quality of plasmodia with the technical simplicity of the measurements characteristic
of dry spores. Darkening of the sclerotia is most probably a pathological phenomenon connected with the impairment of water
balance during sclerotization.
Paper authored by participants of the international conference: XXXIV Winter School of the Faculty of Biochemistry, Biophysics
and Biotechnology of Jagiellonian University, Zakopane, March 7–11, 2007, “The Cell and Its Environment”. Publication costs
were partially covered by the organisers of this meeting. 相似文献
16.
The cooperation and aggression between five laboratory colonies of Monomorium pharaonis were compared using an aggressiveness test and pupa-carrying test in laboratory arenas. The colonies were derived from field
collections in different parts of Europe and USA. Generally, inter-colony aggressiveness was low and acceptance of pupae from
other colonies was high. Workers from one colony (Lužiny, CZ), however, frequently displayed aggressive behavior when paired
with workers from other colonies, and the Lužiny pupae were avoided by workers of other colonies in pupa-carrying tests. Behavioral
tests were only partly consistent with the phylogenetic relatedness of ants because the Wisconsin colony (USA) grouped with
the Lužiny colony (and not with the other three colonies) in the phylogenetic analysis but grouped with the other three colonies
in the behavioral tests. 相似文献
17.
《Critical reviews in biotechnology》2013,33(3):257-299
AbstractThe morphology, biochemistry, and physiology studies during development of Claviceps purpurea fungi clearly demonstrate that alkaloid synthesis is linked to a specific stage of the fungal life cycle. In nature, ergot alkaloids are synthesized in the course of developing sclerotia, while in submerged cultures, lacking sexual reproduction, alkaloid synthesis proceeds in sclerotia-like cells. Highly active submerged strains could be obtained by combination of mutagens with a different mode of action as well as by somatic hyphal anastomoses or efficient protoplast fusions to obtain the parasexual cycle. Fused strains not only retained the biosynthetic activity of parent strains but produced even much higher amounts of alkaloids. In our strains, the appropriate morphology always corresponded to high productivity. Furthermore, the form of cell differentiation was typical for each particular strain. When comparing active and inactive strains, measurements of qualitative and quantitative changes in mycelium composition revealed different metabolic patterns and certain characteristics necessary for efficient alkaloid production. Evaluation of activities of some enzymes from the central metabolic pathways, which generate the basic intermediates for ergot alkaloid synthesis also contributed to the overall knowledge of mechanisms involved. 相似文献
18.
Pedro P. Olea 《Population Ecology》2009,51(1):161-174
The spatial and temporal variation in population sizes of animal colonies are rarely studied simultaneously. I examined factors
determining colony size (number of nests) for 23 colonies from the only breeding population of rook Corvus frugilegus in Spain over 7 years. Population sizes within colonies were highly predictable over time, with autocorrelations up to a
distance (lag) of 6 years. Autoregressive mixed models were used to explain colony size as a function of environmental factors,
while controlling for temporal autocorrelation. These factors included refuse tips, widely used as food resource, and a derived
variable that incorporated the two factors most often related to avian colony size (inter-colony competition and foraging
habitat around colonies). Autoregressive models provided a better fit to the data than models which did not consider temporal
autocorrelation. The information-theoretic (AICc-based) approach revealed uncertainty in the selection of the best model explaining colony-size, but relatively strong support
for certain variables. The highest weights of evidence were for year (ω
i
= 0.90) and the number of competitors per unit of foraging habitat (i.e., derived variable; ω
i
= 0.63), showing that the size of rook colonies in Spain was negatively affected by inter-colony competition relative to
the foraging habitat surrounding the colonies. This variable measured within a 6-km radius from the colonies had ~30 times
higher weight of evidence (more plausible) than the same variable measured within 3 km, indicating that food limitation may
occur outside the breeding period. Sizes of colonies tended to decrease when distance between the colony and the nearest refuse
tip increased. There was some evidence supporting the idea that the effect of the number of competitors per unit of foraging
habitat on colony size varied from year to year, but statistical power was weak. These findings suggest that variation in
number of rook nests within colonies reflects spatial and temporal heterogeneity of net food via both inter-colony competition
and foraging habitat around the colony.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
19.
Nostoc commune Vauch. is one of the few freshwater cyanobacteria that has been used as human food. But its commercial production has been
elusive. This prompted us to investigate further on the chemical composition and morpho-cytological characteristics of the
discoid and spherical forms of the alga from the Philippines and Japan. Light microscopy of the two forms revealed that they
consisted of irregularly coiled, unbranched, heterocystous filaments. Transmission electron microscopy showed that a trichome
was enclosed by a 14 μm thick mucilaginous sheath (extracellular polysaccharide, EPS). A colonial sheath enveloped a spherical
colony that was made up of a blue-green outer core that enclosed an inner, whitish, fleshy core, while the discoid form was
a deflated or desiccated form of the spherical form. Cytologically, the outer core of the spherical colony (PS) had significantly
(p < 0.01) shorter filaments and higher heterocyst frequency than the discoid colony while the discoid type had greater number
of detached heterocysts than the other type. Chemical analyses revealed that the cyanobacterium had 34–45% oxalate-oxalic
acid soluble substances (OOSS), a dietary fiber that was found to be in higher concentration among the discoid forms than
the spherical forms. The major components of OOSS were identified as glucuronic and galacturonic acids that may play a role
in modulating water flow in the glycans of the mucilaginous sheath. There were 17 amino acids identified. Philippine spherical
(PS) colonies yielded generally higher concentration for each of these amino acids than the discoid types (PD and JD) except
for phenylalanine, aspartic acid, and proline. There were six soluble proteins identified in the samples with the following
molecular weights in kDa: 73, 55, 39, 36, 29, and 14.4. A protein band of 55 kDa was common to all types of colonies while
73 kDa was identified in the spherical form (PS) and faintly in the discoid form (JD). The protein bands of 39, 36, 29, and
14.4 kDa were found distinctly among the discoid forms (desiccated types) regardless of origin but absent in the spherical
forms. In vitro protein digestion was improved, by as much as 30%, when the pigments were extracted. However, the presence of phenolic compounds
could also affect protein digestion. Morpho-cytological studies and chemical analyses showed that N. commune of the same colony form generally had the same characteristics regardless of their origin. Although the common traits were
more obviously observed among the discoid colonies. However, protein, crude lipid, and chlorophyll a concentrations were found to be more dependent on the age and culture condition of the cyanobacterium than on colony form
or origin.
Presented at the 6th Meeting of the Asia Pacific Society of Applied Phycology, Manila, Philippines. 相似文献
20.
Extreme variability in the size, shape and spacing of skeletal spines ofPocillopora damicornis has been demonstrated both within single colonies and also between colonies from different environments. Preliminary studies
indicated that the majority of spines from branch tips at the apex of the colony display a ‘fasciculate’ growth surface in
contrast to partly fasciculate or ‘smooth’ growth surfaces exhibited by spines from branch tips at the base of the colony.
No significant differences in the height and width of costal spines from apical and basal branch tips within a single colony
were observed, although spines from colonies exposed to strong wave action tended to be significantly shorter and narrower
than those from more sheltered environments. Both costal and coenosteal spines from wave-exposed colonies displayed branching
and divided extremities while those from sheltered environments consisted of simple cones. Spines develop as an outgrowing
of the calicoblastic ectoderm which secretes the skeleton. Growing costal and coenosteal spines are enveloped by a layer of
calicoblastic ectoderm which penetrates through mesogloea, aboral gastroderm, coelenteron, oral gastroderm, mesogloea and
finally oral ectoderm. Spines within the corallite are surrounded by calicoblastic ectoderm, mesogloea and aboral gastroderm
only. A scheme for the growth of the spines is discussed. 相似文献