Degradation of maize stem by two rumen fungal species, Piromyces communis and Caecomyces communis, in pure cultures or in association with cellulolytic bacteria.

Two species of rumen fungi, Piromyces (Piromonas) communis FL and Caecomyces (Sphaeromonas) communis FG10, were cultured alone or in association with the cellulolytic bacteria Ruminococcus flavefaciens or Fibrobacter succinogenes on maize stem. A kinetic study of the degradation of the substrate was then made. After 48 h of culture, all non-lignified tissues observed by scanning electron microscopy disappeared with P communis and degradation was as complete as that observed in the rumen. In contrast, C communis degraded little of the plant cell walls. The ability of P communis to more rapidly degrade maize stem was probably due to the presence of filamentous rhizoids. The extent of dry matter loss after 8 days of incubation was practically the same in all the monocultures and in the 4 cocultures. However, the rate of degradation was faster in the bacterial than in the fungal monocultures and the co-cultures. No metabolic interaction was observed.     

Effect of heterotrophic ruminal bacteria on xylan metabolism by the anaerobic fungus Piromyces communis

Six rumen bacteria were cocultured with the rumen fungus Piromyces communis and the effects on xylanolysis determined. The rate and extent of xylan utilization was enhanced in cocultures with Prevotella ruminicola or Succinivibrio dextrinosolvens. The positive effects of Suc. dextrinosolvens and Prev. ruminicola on xylanolysis by P. communis correlated with effective cross-feeding by the bacteria on arabinose and xylose released from xylan. Xylanolysis was not enhanced in cocultures of P. communis with Streptococcus bovis, Veillonella parvula or Ruminococcus flavefaciens. A comparison of fermentation product profiles and of extracellular enzyme activities showed that whereas saccharolytic species and Butyrivibrio fibrisolvens were dominant in cocultures, P. communis dominated in the culture with R. flavefaciens. Extracellular xylanase and β-xylosidase activities were not increased by cocultivation of P. communis with any of the heterotrophic bacteria.     

乡土植物芦苇对外来入侵植物加拿大一枝黄花的抑制作用

在城市建筑荒地中设立实验样地,通过对样方植物进行实地观测,并结合实验室比叶重和生物量测算,了解和分析野外建筑荒地中自然混生条件下芦苇(Phragmites communis)和加拿大一枝黄花(Solidago canadensis)的竞争过程和结果。结果表明芦苇和加拿大一枝黄花混生群落中芦苇发展近似于单优群落,芦苇以较高的平均株高和密度抑制加拿大一枝黄花生长,混生群落逐渐趋向于芦苇单优群落。混生群落芦苇比叶重和平均每株生物量近似于单优群落,加拿大一枝黄花比叶重和平均每株生物量显著低于其单优群落,光合作用受到显著抑制。de Wit模型分析显示,混生群落中芦苇和加拿大一枝黄花相互竞争、拮抗,前者竞争攻击力高于后者,模型预测混生群落中芦苇最终将把加拿大一枝黄花从样地中排除出去。浸提液种子培养显示加拿大一枝黄花具有化感作用,在低浓度条件(12.5mg/mL)下,对自生种子发芽有促进作用,高浓度条件下出现强烈抑制,但各浓度下芦苇种子不受加拿大一枝黄花化感作用影响;芦苇种子繁殖能力相对较弱,混生样地中加拿大一枝黄花在芦苇竞争胁迫下,种子千粒重和发芽率显著上升,扩散能力增强。芦苇具有在一定区域生态控制加拿大一枝黄花的潜力。     

The rumen flagellate Piromonas communis: its life-history and invasion of plant material in the rumen.

The rumen flagellat Piromonas communis is the zoospore of a phycomycete fungus inhabiting the rumen. Zoosporogenesis was stimulated by a dietary component (the inducer), and inhibited by compounds affecting membrane structure and function, but not by inhibitors of protein synthesis. The zoospores showed taxis towards the tissues surrounding the inflorescence of Lolium perenne L. in the rumen, invading principally the stomata and damaged tissues. The zoospores germinated on this substratum and the rhizoids of the developing vegetative stage penetrated the tissue, taking up C14 from labelled plant material, which was incorporated into the fungal cells. The conditions for maximum flagellate production (39 degrees C, pH 6-0 to 7-0, high concentration of CO2, absence of O2) resembled those found in the rumen. The organism was cultured in an undefined medium in vitro in the absence of other flagellates.     

Studies on the rumen flagellate Sphaeromonas communis.

The rumen flagellate Sphaeromonas communis showed a significant increase in population density 1 to 2 h after the host sheep commenced feeding, followed by a reduction in numbers to the pre-feeding level after a further 2 to 3 h. The life-history of the organism was shown to consist of a motile flagellate which germinated to produce a vegetative stage comprising a limited rhizoidal system on which up to three reproductive bodies were borne together with (in vitro) other spherical bodies of unknown function; in vivo, the reproductive bodies were stimulated to liberate flagellates by a component of the diet of the host. The vegetative stage strongly resembled that of certain species of aquatic phycomycete fungi, and the flagellates may therefore by zoospores. Flagellates liberated in vivo lost their motility within 2 to 3 h and developed into the reproductive vegetative phase, producing a rapid decrease in numbers of flagellates. Conditions of maximum flagellate production (pH 6.5, 39 degrees C, presence of CO2, absnece of oxygen) approximated to those found in the rumen. The organism was cultured in vitro in an undefined medium in the absnece of bacteria and other flagellates.     

Glycoside hydrolase enzymes present in the zoospore and vegetative growth stages of the rumen fungi Neocallimastix patriciarum, Piromonas communis, and an unidentified isolate, grown on a range of carbohydrates

The rumen fungi Neocallimastix patriciarum, Piromonas communis, and a morphologically distinct but unidentified isolate were cultivated on the polysaccharides starch, cellulose, xylan, and their principal component monosaccharides and disaccharides, and the range and specific activities of the glycoside hydrolases formed were monitored using gluco-oligosaccharide and p-nitrophenyl glycoside substrates. A wide range of enzyme activities was detected in preparations from vegetative growth and zoospores of all three isolates. Enzyme activity was also present in the culture medium. The specific activities were affected by the carbohydrate source available in the growth medium, although the more active hydrolases involved in the degradation of plant structural and storage polysaccharides were formed on all seven carbohydrate sources evaluated. Enzyme activities were increased in the zoospore, vegetative, and extracellular preparations after growth on the appropriate structurally related disaccharide or polysaccharide. The hemicellulolytic glycosidases (alpha-L-arabinofuranosidase, beta-D-xylosidase) were most active after growth on xylan, whereas alpha-/beta-glucosidase activity was increased with the corresponding glucan as growth substrate. However, whereas wide-ranging beta-glucosidase activity was detected following growth on maltose or starch, the alpha-glucosidase activities of P. communis were lower or undetectable in vegetative preparations grown on glucose or the beta-glucans cellobiose and cellulose.     

Contrasting patterns of genetic divergence in two sympatric pseudo-metallophytes: Rumex acetosa L. and commelina communis L

ABSTRACT: BACKGROUND: Patterns of genetic divergence between populations of facultative metallophytes have been investigated extensively. However, most previous investigations have focused on a single plant species making it unclear if genetic divergence shows common patterns or, conversely, is species-specific. The herbs Rumex acetosa L. and Commelina communis L. are two pseudo-metallophytes thriving in both normal and cupriferous soils along the middle and lower reaches of the Yangtze River in China. Their non-metallicolous and metallicolous populations are often sympatric thus providing an ideal opportunity for comparative estimation of genetic structures and divergence under the selective pressure derived from copper toxicity. RESULTS: In the present study, patterns of genetic divergence of R. acetosa and C. communis, including metal tolerance, genetic structure and genetic relationships between populations, were investigated and compared using hydroponic experiments, AFLP, ISSR and chloroplast genetic markers. Our results show a significant reduction in genetic diversity in metallicolous populations of C. communis but not in R. acetosa. Moreover, genetic differentiation is less in R. acetosa than in C. communis, the latter species also shows a clustering of its metallicolous populations. CONCLUSIONS: We propose that the genetic divergences apparent in R. acetosa and C. communis, and the contrasting responses of the two species to copper contamination, might be attributed to the differences in their intrinsic physiological and ecological properties. No simple and generalised conclusions on genetic divergence in pseudo-metallophytes can thus be drawn.     

Temperature-dependent competition hierarchy: a mechanism stabilizing the phenological strategy in the scorpionfly Panorpa communis L.

Previous studies of the phenologies and the different microclimatic patterns of the distribution of the scorpionflies Panorpa communis L. and Panorpa vulgaris Imhoff and Labram 1836 showed different phenological strategies. In P. communis , a species foraging at shadowy and cool places only, a majority of 90% of the individuals are univoltine; however, approximately 10% of the offspring of the first annual generation are bivoltine. This proportion remained unchanged in the Freiburg population over 8 years. Differently, all individuals of P. vulgaris foraging equally frequent at sunny and warm as at shadowy and cool places are bivoltine. The proximate cause of bivoltinism in both species is a heritable variation of different ‘day length thresholds’ triggering diapause‐free development if natural day length exceeds these thresholds. As selection favours maximal temporal exploitation of food availability it remains obscure why in P. communis the number of diapause‐free developing individuals does not increase continuously from year to year although this phenotype reproduces twice a year. Therefore, in the present paper, we focus on the following main questions. Does the competitive inferiority of P. communis in the presence of P. vulgaris at the temperature regime of the late summer function as a mechanism maintaining the majority of individuals of P. communis univoltine, by dramatically reducing the fitness of the bivoltine ones? As a long‐term evolutionary change in the frequency of bivoltine individuals in P. communis solely depends on the lifetime reproductive success of the females, we here consider the influence of interspecific competition and temperature conditions on the reproductive success of the females of P. communis only. Five lines of evidence suggest that the mechanism of maintaining univoltinism in P. communis is primarily because of differences in the ability of each species to exploit dead arthropod resources: (1) these species show complete diet overlap; (2) dead arthropods are limiting resources for both species of scorpionflies as indicated by positive demographic effects with increased food availability; (3) in competition with P. vulgaris at high temperatures, P. communis is competitively inferior in the ability to detect and exploit dead arthropods; (4) this reduced resource acquisition of female P. communis translates into significant reductions in the survivorship, body condition, fecundity and lifetime reproductive success; (5) exploitation competition does account for these negative demographic effects on second‐generation females of P. communis more than interference competition.     

无瓣海桑与芦苇两种湿地系统对N、P净化作用比较

比较研究了芦苇和无瓣海桑湿地系统的净化效应,分季节采样测定;了两系统中的水、土壤、植物样品进行N、P含量及相关指标。结果表明:两系统水体中秋冬季的污染比较严重,而无瓣海桑对水体中N、P的净化效果优于芦苇系统,尤其是在冬季;夏季土壤对N、P的吸附力比冬季时强,夏季无瓣海桑土壤中N含量低于芦苇,冬季则相反,无瓣海桑系统土壤对P的吸附作用也强于芦苇系统;不论在冬季还是夏季,无瓣海桑湿地系统的净化效果都要好于芦苇系统,芦苇对N的富集作用比对P的强,而无瓣海桑对P元素的富集作用相对较强。     

Effects of emulsified octadecanic acids on gas production and cellulolysis by the rumen anaerobic fungus, Piromyces communis M014

Responses of the rumen anaerobic fungus, Piromyces communis M014, to octadecanic long-chain fatty acids (LCFAs) were evaluated by measuring total and hydrogen gas productions, filter paper (FP) cellulose degradation and polysaccharidase enzyme activities. Octadecanic acids (stearic acid, C(18:0); oleic acid, C(18:1); linoleic acid, C(18:2) and linolenic acid, C(18:3)) were emulsified by ultrasonication under anaerobic conditions, and added to the medium at the level of 0.001%. When P. communis M014 was grown in culture with stearic and oleic acids, the cumulative gas production, FP cellulose digestion and enzyme activities were significantly (p<0.05) increased in the early incubation times relative to those for the control. However, the addition of linolenic acid inhibited all of the investigated parameters, including cellulose degradation, enzyme activities and gas production, up to 168h incubation. These results indicated that stearic and oleic acids tended to have stimulatory effects on fungal cellulolysis, whereas linolenic acid caused a significant (p<0.05) inhibitory effect on cellulolysis by the rumen fungus. The fungus, P. communis M014, can biohydrogenate C(18) unsaturated fatty acids to escape from their toxic effects. Therefore, in this study, the results indicated that the more highly the added C(18) LCFA to the fungal culture was unsaturated, the higher the inhibition of gas production and cellulase enzyme activity was.     

Effects of aromatic amino acids, phenylacetate and phenylpropionate on fermentation of xylan by the rumen anaerobic fungi, Neocallimastix frontalis and Piromyces communis

AIMS: Anaerobic fungi are important members of the fibrolytic community of the rumen. The aim of this study was to study their requirement for aromatic amino acids (AA) and related phenyl acids (phenylpropionic and phenylacetic acids) for optimal xylan fermentation. METHODS AND RESULTS: Neocallimastix frontalis RE1 and Piromyces communis P were grown in a defined medium containing oat spelts xylan as the sole energy source, plus one of the following N sources: ammonia; ammonia plus a complete mixture of 20 AA commonly found in protein; ammonia plus complete AA mixture minus aromatic AA; ammonia plus phenyl acids; ammonia plus complete AA mixture without aromatic AA plus phenyl acids. Both species grew in all the media, indicating no absolute requirement for AA. The complete AA mixture increased (P<0.05) acetate concentration by 18% and 15%, sugar utilization by 33% and 22% and microbial yield by about 22% and 15% in N. frontalis and P. communis, respectively, in comparison with the treatments that had ammonia as the only N source. Neither the supply of aromatic AA or phenol acids, nor their deletion from the complete AA mixture, affected the fermentation rate, products or yield of either species. CONCLUSIONS: AA were not essential for N. frontalis and P. communis, but their growth on xylan was stimulated. The effects could not be explained in terms of aromatic AA alone. SIGNIFICANCE AND IMPACT OF THE STUDY: Ruminant diets should contain sufficient protein to sustain optimal fibre digestion by ruminal fungi. Aromatic AA or phenyl acids alone cannot replace the complete AA mixture.     

The primary sequence of Ricinus communis agglutinin. Comparison with ricin

A mixture of synthetic oligonucleotides representing all possible sequences of a peptide present in the ricin B chain has been used to screen a cDNA library constructed using ripening castor bean seed poly(A+) RNA. The eight largest recombinant plasmids selected, by hybridization, a single mRNA species whose translational product was identified as preprolectin by immunoprecipitation. Restriction enzyme analysis of these clones demonstrated that two classes were present representing sequences complementary to two distinct but closely related preprolectin mRNA species. The nucleotide sequence of the cloned cDNA from one of these classes encodes preproricin and has been presented elsewhere (Lamb, F. I., Roberts, L. M., and Lord, J. M., (1985) Eur. J. Biochem. 148, 265-270). The nucleotide sequence of the second class is presented here and shown to represent prepro-Ricinus communis agglutinin. The entire coding sequence was deduced from two overlapping cDNA clones having inserts of 1668 and 1151 base pairs. The coding region defines a preproprotein with a 24-amino acid N-terminal signal sequence preceding the A chain (266 amino acids) which is joined to the B chain (262 amino acids) by a 12-amino acid linking peptide. The protein was confirmed as R. communis agglutinin since the deduced B chain N-terminal sequence corresponds exactly with that determined for purified R. communis agglutinin B chain over a region where several residue differences occur in the ricin B chain. The nucleotide and deduced amino acid sequences of the R. communis agglutinin precursor are compared with those of the ricin precursor.     

蓖麻提取物对南方根结线虫的防治作用

通过毒力测定及盆栽试验,研究了蓖麻提取物对南方根结线虫的杀线活性及防治效果.结果表明:蓖麻碱及蓖麻水提液均具有较强毒杀线虫活性,蓖麻碱浓度为2g·L-1、处理48 h杀线虫活性最强,线虫校正死亡率达91.5％,LC50为0.6 g·L-1;蓖麻水提液浓度为100g·L-1、处理48 h杀线虫活性最强,线虫校正死亡率达83.5％,LC50为18.3 g·L-1;蓖麻碱、蓖麻水提液和蓖麻叶植物粉处理接种南方根结线虫的番茄苗后,植株平均根结数分别为(17.6±1.7)、(20.6±1.5)和(22.8±3.7),均显著低于对照(37.4±2.3),根长分别比对照提高46.8％、34.5％和33.8％,株高分别比对照提高33.5％、22.6％和15.8％,植株鲜质量分别比对照增加41.4％、18.9％和10.1％.蓖麻提取物能减轻线虫危害,对盆栽番茄南方根结线虫病控制效果明显.     

盐胁迫下芦苇叶肉细胞超微结构的研究

对青藏高原柴达木盆地柯柯盐湖边盐碱地上生长的芦苇叶肉细胞的超微结构进行了研究,并以西宁地区非盐碱地上生长的芦苇作对照。结果表明：西宁地区的芦苇叶肉细胞的叶绿体呈椭圆形,其膜系统完整,基粒片层和基质片层发育良好。在盐碱地上生长的芦苇叶肉细胞的叶绿体呈圆形,叶绿体内出现较大的淀粉粒,并发现有线粒体嵌入叶绿体的现象。叶绿体的类囊体膨大,线粒体的嵴也有膨大的现象。在盐湖水中生长的芦苇叶肉细胞,叶绿体的类囊体排列紊乱、扭曲、松散。类囊体膜局部被破坏,部分类囊体膜解体,空泡化,甚至消失,一些溶解了的类囊体流进细胞质中。综上所述,芦苇叶肉细胞超微结构的变化是该植物适应柯柯盐湖地区盐渍、低温、低气压、强辐射等环境因子的结果。     

Association of rumen ciliate populations with plant particles in vitro

Seven known species of rumen ciliates and mixedEntodinium spp. showed association with plant particles in rumen fluid in vitro. Association was greater with fresh particles than with hay, and substantially decreased when the water-soluble components of the particles were removed, suggesting that the water-soluble components may be responsible for the association. The association was rapid and maximal between 5 and 35 min (depending on the ciliate species) after exposure to the particles, and involved major transfers of ciliate populations and biomass from the liquid phase to the solid phase of the system. The most rapid and largest population transfers to the particles from the rumen fluid were shown by the holotrich ciliates, where transfers of up to 97% of the population were recorded. Association with plant particles by all species examined occurred within the pH range 5.5–7.5, and decreased with time when the particles were incubated in rumen contents in vivo. The ciliate biomass transferring from the liquid to the solid phase varied with the composition of the ciliate population.     

Cadmium tolerance and its phytoremediation by two oil yielding plants Ricinus communis (L.) and Brassica juncea (L.) from the contaminated soil

The effect of increasing level of cadmium in soil was investigated on biomass production, antioxidants, Cd bioaccumulation and translocation in Ricinus communis vis-à-vis a commonly studied oil crop Brassica juncea. The plants were exposed to 25, 50, 75, 100, and 150 mg Cd/Kg soil for up to 60 days. It was found that R. communis produced higher biomass at all the contamination levels than that of B. juncea. Proline and malondialdehyde in the leaves increased with increase in Cd level in both the species, whereas soluble protein decreased. The bioaccumulation of Cd was higher in B. juncea on the basis of the per unit biomass, total metal accumulation per plant was higher in R. communis. The translocation of Cdfrom roots to shoot was also higher in B. juncea at all Cd concentrations. R. communis appeared more tolerant and capable to clean Cd contaminated soil for longer period in one sowing than B. juncea and the former can grow in wasteland soil also in which later cannot be cultivated.     

Ricin and Ricinus communis agglutinin subunits are all derived from a single-size polypeptide precursor

Antibodies have been raised in rabbits against the individually purified A and B subunits of the toxic castor bean lectin, ricin, and against the A' and B' subunits of Ricinus communis agglutinin type I. Each of the antisera recognised a single polypeptide species of Mr 60 500 when maturing castor bean endosperm mRNA was translated in vitro in a rabbit-reticulocyte-derived system. When dog pancreatic microsomal vesicles were included in the translational system, each subunit antiserum precipitated a group of 66 000-68 000-Mr core-glycosylated polypeptides which had been translocated into the lumen of the vesicles. The 60 500-Mr polypeptide appeared to be a common precursor to all four individual lectin subunits since (a) its glycosylated (66 000-68 000-Mr) forms were readily detected in the endoplasmic reticulum fraction isolated from maturing castor bean endosperm and (b) pulse-chase studies showed that the glycosylated precursors disappeared from the endoplasmic reticulum fraction with the concomittant appearance of authentic lectin subunits in a soluble protein fraction which included protein body matrix components. Antiserum prepared against whole R. communis agglutinin, type I, also precipitated the 65 000-Mr precursor in vitro and in vivo, but in addition precipitated a non-glycosylated 34 000-Mr polypeptide. This smaller protein is not a lectin subunit precursor, contradicting an earlier suggestion. It is most probably a precursor to the 2-S albumin storage proteins found in castor bean endosperm protein bodies.     

Purification and characteristics of cytosolic chitinase from Piromyces communis OTS1

Abstract A chitinase was purified from the cytosolic fraction of the anaerobic rumen fungus Piromyces communis OTS1 by affinity chromatography using regenerated chitin, gel filtration and chromatofocusing. The chitinase was most active at pH 6.2 and at 60 °C in a 20-min assay. The molecular mass of the purified protein was estimated by SDS-PAGE to be 42 kDa and its pI was 4.9. The enzyme activity, which was of the 'endo' type, was inhibited by A⁺, Hg²⁺ and allosamidin. N -Acetyl- β -glucosaminidase and 'exo' type chitinase activity were absent from the purified preparation.