Distribution of Mononchoidea (Nematoda: Enoplea) in pasture soils,with description of lotonchus stockdilli n. sp.

Abstract

Across 64 sites 8 species were found, with Clarkus propapillatus at 60 sites, C. composticola at 7, Prionchulus muscorum at 3, Mylonchulus ubis at 7, M. sigmaturus at 1, Cobbonchus australis at 9, lotonchus basidontus at 4, and I. stockdilli n. sp. at 3 sites. Sampling effort varied at the sites and significant annual and management effects have previously been reported on mononchid populations. No clear geographic or soil factor is apparent in the distributions, but more species may occur at sites with higher annual rainfall. lotonchus stockdilli n. sp. is a large (female L = 3.05–5.90 mm), bisexual species with dorsal tooth at the posterior of the sclerite, female tail about 400 μm or 14%, and no cuticular pores in the vulval region.     

Frequency of occurrence of mangrove fungi from the east coast of India

This paper describes the frequency of occurrence and biodiversity of fungi from mangroves of the Godavari and Krishna deltas, on the east coast of India. Seventy three species were identified from Godavari and 67 from the Krishna mangroves. Fifty five species were common to both sites, 18 were found only at Godavari and 12 at Krishna mangroves. Verruculina enaliawas found to be very frequent at both sites with a higher frequency of occurrence at Godavari. Eutypa bathurstensis was very frequent at Godavari but only frequent at Krishna. Cirrenalia pygmea and Cryptosphaeria mangrovei were frequent at the Godavari mangrove, but were recorded occasionally at Krishna. Decaying samples of Rhizophora and Avicennia were studied in detail. Forty three species were common to both hosts, while 22 species were recorded only from Avicennia and 20 only from Rhizophora. Verruculina enalia was the only very frequent fungus recorded on both hosts with a lower percentage occurrence (14.8%) on R. apiculata as compared to Avicennia spp. (24.3%). Eutypa bathurstensis was the next most frequent fungus on Avicennia, while Rhizophila marina was next most frequent on Rhizophora. Dactylospora haliotrepha which was recorded frequently on Rhizophorawas infrequent on Avicennia.     

两种国兰C类花发育MADS基因的克隆与表达研究

该研究以蕙兰(Cymbidium faberi)和墨兰(Cymbidium sinense)为材料,利用RT-PCR对AGAMOUS (AG)基因进行克隆,并利用qRT-PCR进行组织表达.结果 表明:(1)获得3个AG基因均属于植物特有的C类MIKC型MADS-box基因,其中2个蕙兰AG基因命名为CfAG1(登录号...     

Folded chromosomes of Saccharomyces cerevisiae

Folded chromosome phenotypes have been examined and compared in four cell-division-cycle (cdc) mutants during transitions between cycling and non-cycling states. The two start mutants, cdc 28 and cdc 25, can undergo G₀ arrest at the restrictive temperature. Arrest at start, defined by the cdc 28 and cdc 25 block points, is distinguishable from G₀ arrest. Arrest at the cdc 28 and cdc 25 block points can also be distinguished from each other: folded chromosomes appear to be destabilized at the cdc 25 block, but are stable at the cdc 28 arrest point. On the other hand, folded chromosomes from cdc 28 in sporulation medium at the restrictive temperature appear unstable, while chromosomes from cdc 25 are stable. The G₁ arrest mutants, cdc 4 and cdc 7, can undergo G₀ arrest at the restrictive temperature. In sporulation medium no meiotic replication form is detected at the restrictive temperature, although incorporation of labeled precursors into nuclear DNA does take place. A schematic model incorporating these various findings is presented.     

Distribution of Plectidae (Nematoda: Araeolaimida) in pasture soils

Abstract

Across 88 sites 9 species were found, with Anaplectus granulosus at 56 sites, Plectus parietinus at 47, P. longicaudatus at 30, P. parvus at 15, P. cirratus and Wilsonema otophorum at 11, P. armatus and A. porosus at 4, and Tylocephalus auriculatus at 1 site. A key to Anaplectus males is given. For nine sites mean length of female A. granulosus is negatively correlated with mean annual air temperature. The most diverse fauna comprised six species in Kaitoke silt loam; it appears that faunal diversity increases with higher rainfall. Species apparently coexist through separation in size and time. Tylocephalus was only found in soils with a thermic soil temperature regime.     

Antagonism between Gliodadium roseum,Trichoderma harzianum,or Trichothecium roseum and Phytophthora megasperma f. sp. glydnea

The antagonism between Gliodadium roseum, Trichoderma harzianum, or Trichothecium roseum and Phytophthora megasperam f. sp. glycinea (Pmg), cause of Phytophthora rot of soybeans (Glycine max), was studied. G. roseum, T. harzianum, and 17 isolates of T. roseum were grown separately on modified Czapek-Dox medium (MCD) in the dark for 25 days at 25 °C. Culture filtrates of T. roseum at 0.5% and 20.0% concentrations inhibited mycelial growth of Pmg at 3.1% and 90.4%; and those of G. roseum at –0.7% and 44.0%; and of T. harzianum at 0.7% and 46.0%, respectively. Culture filtrates of T. roseum at 0.5% concentration inhibited zoosporangenesis of Pmg at 98.0% and at 1.0% concentration prevented it. Culture filtrates of G. roseum and T. harzianum at 5% concentration significantly (P=0.05) inhibited zoosporangenesis of Pmg, but differences were not significant from that on MCD. Culture filtrates of 17 isolates of T. roseum inhibited mycelial growth and zoosporangenesis of Pmg at different percentages with different concentrations with those of isolate 9 showing the greatest inhibition of both. Mycelial growth of most of 16 races of Pmg was prevented at 10% concentration of the culture filtrates of isolate SS-2 of T. roseum, and all 16 races, except race 6, was prevented at 20% concentration. Zoosporangenesis of all races of Pmg was prevented at 2% the culture filtrate of SS-2. Culture filtrates of SS-2 inhibited zoosporangenesis of Pmg in soil.     

The effects of salinity on growth,nodulation and nitrogen fixation ofCasuarina equisetifolia

The growth, nodulation and nitrogen fixation ofCasuarina equisetifolia were compared at six levels (0–500mM NaCl) of salinity in sand culture. Dry weight of nodules, shoots and roots and N content of shoots increased at intermediate levels of salinity (50–100 mM) but decreased at 500 mM NaCl. Nodulation occurred at all NaCl levels, but at 500mM NaCl level, the nodule dry weight declined by 50% from the control. Increasing NaCl concentration of up to 200mM had little effect on the N₂-fixation rate, but at 500mM NaCl level the rate decreased to 40% of the control value.     

The control of allelic recombination at histidine loci in Neurospora crassa

The gene rec-1⁺ which reduces allelic recombination at the his-1 locus by a factor of between 15 and 30 has no effect upon allelic recombination at the his-2, his-3, his-5, his-6 and his-7 loci. Other genes controlling recombination at two of these loci, namely rec-x at his-2 and rec-w at his-3, have been found. There is a strong possibility that rec-x may be identical with rec-3, so far known to regulate recombination only at the am-1 locus. It is probable that the stocks used all carry a rec⁺ gene which regulates recombination at the his-6 locus, since all prototroph frequencies are low, but no regulatory gene active at the his-5 and his-7 loci.     

Artificial control of cytoplasmic pH and its bearing on cytoplasmic streaming,electrogenesis and excitability of characeae cells

Effects of changing the cytoplasmic pH on the cytoplasmic streaming, membrane potential and membrane excitability were studied in tonoplast-free cells ofChara australis andNitellopsis obtusa. The cytoplasmic pH was varied by internal perfusion of pH-buffered media.Nitellopsis cells were perfused only once, whileChara cells were perfused twice to control the pH more accurately. In both materials the rate of cytoplasmic streaming was maximum at about pH 7, low at pH 8.5–9 and almost zero at pH 5–5.5. The membrane potential was most negative at about pH 7. InChara the membrane potential supported by Mg·ATP was strongly inhibited at pH 5.5, and almost zero at pH 9, supporting the results obtained by Fujiiet al. (1979) on cells ofChara australis which were perfused once. The action potential could be induced by electrical stimulation inChara at pH 6.0–9.0 and inNitellopsis at pH 6.6–7.9. The membrane resistance ofNitellopsis was high at acidic and neutral pH values and low at alkaline pH, while that ofChara was low at both acidic and alkaline pH values.     

High-performance liquid chromatographic method for the determination of the major quinine metabolite, 3-hydroxyquinine, in plasma and urine

The determination of 3-hydroxyquinine in urine and plasma samples is described. Extraction was performed using a mixture of toluene–butanol (75:25, v/v), followed by back-extraction into the mobile phase, which consisted of 0.1 M phosphate buffer, acetonitrile, tetrahydrofuran and triethylamine. A reversed-phase liquid chromatography system with fluorescence detection and a CT-sil C₁₈ column were used. The within-assay coefficient of variation of the method was 2% at the higher concentration values in plasma, 2.95 μM, 4% at 227 nM and 9% at the lower limit of quantitation, 4.5 nM. In urine, the coefficient of variation was 11% at the lower concentration, 227 nM and was 3% at 56.8 μM. The between-assay coefficient of variation was 4% at the low concentration (5.1 nM) in plasma, 2% at 276.8 nM and 3% at 1.97 μM. In urine, the between assay coefficient of variation was 4% at 204.6 nM, 3% at 5.12 μM and 2% at 56.8 μM.     

Soil-borne viruses occurring in nursery soils and infecting some ornamental species of Rosaceae

Soil from twelve of twenty-six sites on ten nurseries growing ornamental trees and shrubs contained viruliferous nematodes, transmitting arabis mosaic virus (AMV) at eight sites, tomato black ring virus at three and tobacco rattle virus at one site. Tobacco necrosis virus was detected at two sites. Xiphinema spp. were found at nine sites, Longidorus spp. at sixteen and Trichodorus spp. at thirteen sites. Thirty-one ornamental species of Rosaceae were tested for virus infections and AMV was found in Spiraea bumalda, Spiraea japonica alba and Kerria japonica.     

Effect of osmotic potential on the growth of Gaeumannomyces graminis and Phialophora spp.

The linear growth of 10 isolates each of Gaeumannomyces graminis var. graminis, G. graminis var. tritici and Phialophora graminicola and five isolates each of G. graminis var. avenae and a lobed-hyphopodiate Phialophora sp. was studied on osmotically adjusted agar at 20 °C. While most isolates of G. graminis var. avenae ceased growing at osmotic potentials of -60 bars (1 bar = 10⁵ Pa), six out of 10 isolates of G. graminis var. tritici grew at that potential. The growth of all isolates of G. graminis var. tritici and var. avenae ceased at -70 bars. In contrast, four out of 10 isolates of P. graminicola grew at -70 bars, but all stopped growing at -80 bars. Most of the isolates of G. graminis var. graminis and the lobed-hyphopodiate Phialophora sp. grew at -70 bars while three out of 10 isolates of G. graminis var. graminis and one out of five isolates of the lobed-hyphopodiate Phialophora sp. were capable of growth at -80 bars. None of the fungi grew at -90 bars. Detailed studies of the growth of two or three isolates each of the five fungi at 10, 20, 30 and 35 °C were carried out on osmotic agar controlled by the addition of either sodium chloride or potassium chloride. In general, similar reductions in growth occurred with decreasing osmotic potential regardless of the solute used. At 10 and 20 °C., all three isolates of P. graminicola showed optimal growth at about -5 bars while the other fungi grew fastest at -1²middot; bars. At 30 °C., one isolate of the lobed hyphopodiate Phialophora sp. and two isolates each of P. graminicola, G. graminis var. tritici and G. graminis var. avenae grew optimally at osmotic potentials of -10 to -15 bars. The other isolate of the Phialophora sp. and two isolates of G. graminis var. graminis studied grew optimally at the highest potential (-1·2 bars). However, at 35 °C the last three fungi exhibited optimal growth at osmotic potentials of-10 to -20 bars. The ecological significance of these results is discussed in relation to cross-protection against the take-all fungi by the avirulent fungi.     

Aspergillus fumigatus AR04 obeys Arrhenius' rule in cultivation temperature shifts from 30 to 40°C

To set a benchmark in fungal growth rate, a differential analysis of prototrophic Aspergillus fumigatus AR04 with three ascomycetes applied in > 10³ t year^-1 scale was performed, i.e. Ashbya gosspyii (riboflavin), Aspergillus niger (citric acid) and Aspergillus oryzae (food-processing). While radial colony growth decreased 0.5-fold when A. gossypii was cultivated at 40°C instead of 28°C, A. fumigatus AR04 responded with 1.7-fold faster hyphal growth. A. niger and A. oryzae formed colonies at 40°C, but not at 43°C. Moreover, all A. fumigatus strains tested grew even at 49°C. In chemostat experiments, A. fumigatus AR04 reached steady state at a dilution rate of 0.7 h^-1 at 40°C, 120% more than reported for A. gossypii at 28°C. To study mycelial growth rates under unlimited conditions, carbon dioxide increase rates were calculated from concentrations detected online in the exhaust of batch fermentations for 3 h only. All rates calculated suggest that A. fumigatus AR04 approximates Arrhenius’ rule when comparing short cultivations at 30°C with those at 40°C. Linearization of the exponential phase and comparison of the slopes revealed an increase to 192% by the 10°C up-shift.     

Heat-stability of peroxidase in mycelia of some toxigenic and nontoxigenic Aspergilli and Penicillia

Seven-day-old mycelia from 19 cultures of Aspergillus and 12 cultures of Penicillium were heated to 50, 60, 65, 70, 75, 80, 85, 90 or 95 C for no more than min, and tested for residual peroxidase. The peroxidase from all aspergilli survived heating at 50 through 80 C. Peroxidase from toxigenic strains of Aspergillus flavus, Aspergillus parasiticus and Aspergillus ochraceus survived heating at 85 C and often at 90 C, whereas peroxidase from nontoxigenic strains of A. flavus was inactivated at 90 C and markedly reduced in activity at 85 C. Peroxidase from all penicillia survived heating at all temperatures through 80 C, although the activity of several cultures was reduced at 80 C. Peroxidase activity in mycelia of two strains of Penicillium cyclopium and one of Penicillium puberulum failed to survive heating at 85 C. One strain each of Penicillium roqueforti and Penicillium viridicatum exhibited some peroxidase activity after heating at 90 C, whereas the peroxidase of all other penicillia was inactivated at this temperature.     

Effect of ectomycorrhizal infection on growth and photosynthetic characteristics of <Emphasis Type="Italic">Pinus densiflora</Emphasis> seedlings grown under elevated CO<Subscript>2</Subscript> concentrations

The effect of ectomycorrhizal Pisolithus tinctorius (Pt) infection was studied on the growth and photosynthetic characteristics of Pinus densiflora seedlings grown at ambient (360 µmol mol⁻¹, AC) and elevated (720 µmol mol⁻¹, EC) CO₂ concentrations. After 18 weeks, Pt inoculation had led to significantly increased dry mass and stem diameter of P. densiflora at both CO₂ concentrations, relative to non-inoculated seedlings. Moreover, EC significantly increased the ectomycorrhizal development. The phosphate content in needles inoculated with Pt was about three times higher than without inoculation at both CO₂ concentrations. The PAR saturated net photosynthetic rates (P _sat) of P. densiflora inoculated with Pt were clearly higher than for control seedlings at both CO₂ concentrations, and the maximum net photosynthetic rate (P _N) at saturated CO₂ concentration (P _max) was higher than in controls. Moreover, the carboxylation efficiency (CE) and RuBP regeneration rate of the P _N/C _i curve for P. densiflora inoculated with Pt were significantly higher than for non-inoculated seedlings at both CO₂ concentrations, especially at EC. The water use efficiency (WUE) of seedlings inoculated with Pt grown at EC was significantly raised. Allocation of photosynthates to roots was greater in Pt inoculated pine seedlings, because of the enhanced activity of ectomycorrhiza associated with seedlings at EC. Moreover, P _N of non-inoculated seedlings grown for 18 weeks at EC tended to be down regulated; in contrast, Pt inoculated seedlings showed no down-regulation at EC. The activity of ectomycorrhiza may therefore be enhanced physiological function related to water and phosphate absorption in P. densiflora seedlings at EC.This study was partly sponsored by the Ministry of Education, Sport, Culture, Science and Technology of Japan (RR2002, Basic Research B and Sprout study).     

Effect of pH on growth and biochemical responses of <Emphasis Type="Italic">Dunaliella bardawil</Emphasis> and <Emphasis Type="Italic">Chlorella ellipsoidea</Emphasis>

The goal of the present investigation was to study the effect of pH on growth and biochemical responses of Dunaliella bardawil and Chlorella ellipsoidea when exposed to different pH values. The two tested microalgae could grow in a wide range of pH (4–9 for D. bardawil and 4–10 for C. ellipsoidea). The dry weight gain and the biochemical components of D. bardawil were greatly enhanced at pH 7.5. In contrast, dry weight and carbohydrate content of C. ellipsoidea attained their maximum values at the alkaline pH. On the other hand, the protein content of C. ellipsoidea recorded its highest value at pH 4, while the pigment content of the same alga was highest at pH 4, 6, and 7.5 and decreased at alkaline pH. Both pH 6 and pH 9 stimulated the accumulation of β-carotene, vitamin E and vitamin C in D. bardawil, with the highest values of the three compounds recorded at pH 9. In the case of C. ellipsoidea, β-carotene content increased at pH 6 and pH 10 as compared with the control, but the amount of β-carotene was much higher at pH 6 than at pH 10. Vitamin E content was higher in C. ellipsoidea cells at pH 10 than at pH 6. Both pH 6 and pH 10 caused a significant decline in vitamin C content of C. ellipsoidea.     

Dry matter production, population structure and environmental conditions of the spring ephemeralErythronium japonicum growing in various habitats differing in sunlight exposure in cool temperate Japan

Phenology, dry matter production, population structure and environmental conditions were examined inErythronium japonicum Decne plants growing on the floor of a deciduous broad-leavedQuercus mongolica forest (Q.m. stand), an evergreen coniferousCryptomeria japonica plantation (C. j. stand) and bare ground left for 3 years after the clearing of a forest composed of youngQ. mongolica andPinus densiflora trees (bare stand) in the cool temperate zone of Japan. The average population density of the plants growing at theQ.m. stand was much higher than that observed at the bare stand, whereas the average number of flowering plants at the former stand was less than half of that at the latter. The population density and number of flowering plants growing at theC. j. stand were both less than 30% of those at theQ. m. stand. The number of seedlings at theQ. m. stand was much more than that at the bare andC. j. stands. Their survivorship rate over 1 year at the former stand also seems to be significantly higher than those at the other stands. Their aboveground and belowground parts at the bare stand were exposed to more severe heat and water stress than those at the other two stands. The net production per leaf area of the plants growing at theQ. m. stand was two and six times larger than those at the bare andC. j. stands, respectively. The plants at the bare stand did not use the available solar radiation as efficiently for dry matter production through photosynthesis as those growing at theQ. m. stand, whereas those at theC. j. stand are strongly restricted in their photosynthetic process by the significantly limited light condition on the floor of the evergreen coniferous plantation. The differences in the number of plants reaching sexual maturity, the density and structure of the population and the net production between their three habitats are discussed here from the standpoint of differences in environmental conditions.     

Cytological studies on the nuclear differentiation in microspore division of some angiosperms

In all of the 32 species studied the chromatin in one of the daughter nuclei produced by microspore division was found to diffuse earlier than the chromatin of the other. The former developed into a vegetative nucleus and the latter into a generative nucleus. The stage at which this difference between daughter nuclei was first found appeared to vary widely among species. The earliest was found to be at mid-anaphase observed inHemerocallis thunbergii andMagnolia denudata, and the latest at early interphase observed inLilium japonicum, Pogonia japonica andEpipactis thunbergii. InNarcissus jonquilla and 4 other species the nuclear differentiation started at late anaphase, inHaplopappus gracilis and 13 other species at early telophase, and inTradescantia paludosa and 7 other species at mid-telophase.     

Genetic regulation of developmental phases in winter wheat

The orderly development of winter wheat through its life cycle can be marked at three stages: stem elongation, heading date, and physiological maturity. The duration of a developmental phase between two stages is important in yield component generation. In this study the three developmental stages were characterized and 350 markers were mapped in a population of recombinant inbred lines (RILs) generated from a cross between two winter wheat cultivars (‘Jagger’ and ‘2174’). Three major QTLs were found to control variation in developmental process, and each of them was tightly associated with a known flowering gene, VRN-A1 on chromosome 5A, PPD-D1 on chromosome 2D, and VRN-D3 on chromosome 7D. The average contribution of the gene marker for each QTL to the total phenotypic variation (R ²) was evaluated over 3 years. The effect of VRN-A1 ranged from 21.5% at stem elongation to 17.4% at physiological maturity. The effect of PPD-D1 was minor (6.7%) at stem elongation but increased to 29.7% at heading and 20.1% at physiological maturity. The effect of VRN-D3 was not detected at stem elongation but increased to 14.6% at heading and to 20.5% at physiological maturity. Hence, the VRN-A1 locus, the PPD-D1 locus, and the VRN-D3 locus had greatest impact on development at stem elongation, heading date, and physiological maturity, respectively. Whereas the Jagger VRN-A1 and VRN-D3 alleles accelerated development, the Jagger PPD-D1 allele delayed the developmental process due to its sensitivity to photoperiod. Our findings suggest that through the appropriate combination of alleles at these three loci one would be able to regulate the various developmental phases to accommodate different agricultural needs.     

Temperature-dependent phosphate solubilization by cold- and pH-tolerant species of Aspergillus isolated from Himalayan soil

Ten species of Aspergillus isolated from soil samples collected from different locations in the Indian Himalayan region have been studied for their growth requirements and tricalcium phosphate solubilization at different temperatures. The Aspergillus species could grow at low temperature and tolerated a wide range of pH. Phosphate solubilization by various Aspergillus species ranged between 374 μg/ml (A. candidus) to 1394 μg/ml (A. niger) at 28°C, 33 μg/ml (A. fumigatus) to 2354 μg/ml (A. niger) at 21°C, 93 μg/ml (A. fumigatus) to 1452 μg/ml (A. niger) at 14°C, and 21 μg/ml (A. wentii) to 83 μg/ml (A. niger) at 9°C. At 21 and 28°C, phosphate solubilization showed a decrease within 4 weeks of incubation, whereas at 9°C and 14°C, it continued further up to 6 weeks of incubation. In general, phosphate solubilization by different Aspergillus species was recorded at a maximum of 28°C or 21°C; biomass production was favored at 21°C or 14°C. Conversely, A. nidulans and A. sydowii exhibited maximum phosphate solubilization at 14°C and produced maximum biomass at 21°C. Data suggest that suboptimal conditions (higher or lower temperature) for fungal growth and biomass production were optimal for the production of metabolites involved in phosphate solubilization. Significant negative correlations were obtained between pH and phosphate solubilization for eight species at 28°C, for seven at 21°C, and for nine at 14°C. Extracellular phosphatase activity was exhibited only in case of A. niger, whreas intracellular phosphatase activity was detected in all species, the maximum being in A. niger. Statistically significant positive or negative correlations were obtained between phosphate solubilization and other parameters in most cases at different temperatures.