Spatial distribution of chitinases and β-1,3-glucanase transcripts in bean arbuscular mycorrhizal roots under low and high soil phosphate conditions

Arbuscular mycorrhizal (AM) fungi extensively colonize the root cortex under low-soil-phosphate (P) conditions, whereas infection is limited under high-P conditions. Fungal growth under both P conditions might be influenced by plant defence-related gene expression. In this study, we used in situ hybridization methods to compare the cellular localization of three defence-related mRNAs in non-infected bean roots and in relation to fungal infection units. In non-infected and infected roots, mRNAs encoding acidic and basic endochitinases were generally most abundant in the vascular cylinder. High-P-grown mycorrhizal roots showed localized accumulation of the acidic endochitinase mRNA in cortical cells containing arbuscules and in their immediate vicinity (one to five cell layers). The pattern of accumulation of the basic endochitinase mRNA was not affected by P or AM fungal infection. At the low P concentration, the β-1,3-glucanase mRNA accumulated predominantly in the vascular cylinder of non-infected roots. Suppression of β-1,3-glucanase mRNA accumulation in these tissues was observed in non-infected roots at the high-P and in mycorrhizal roots at both P concentrations. The observed suppression extends at least several mm from fungal infection units, characterizing a systemic effect. Beta-1,3-glucanase mRNA accumulated also around a number of cortical cells containing arbuscules only at the low P concentration. The localized accumulations of the endochitinase and β-1,3-glucanase mRNAs suggest that the encoded proteins might be involved in the control of intraradical fungal growth.     

南五味子属(五味子科)三种植物之补记

报道南五味子属Kadsura的黑老虎K. coccinea (Lem.) A. C. Smith在印度尼西亚的分布新记录,毛南五味子K. induta A. C. Smith在中国贵州的分布新记录,冷饭藤K. oblongifolia Merrill在中国福建和台湾以及越南的分布新记录,补充或纠正了前人对毛南五味子的形态描述,取消了Saunders对海南黑老虎K. hainanensis Merrill和冷饭藤所作的后选模式。     

Floristic variation and willow carr development within a southwest England wetland

Abstract. Woodland colonization on wetlands is considered to have a detrimental effect on their ecological value, even though detailed analysis of this process is lacking. This paper provides an evaluation of the ecological changes resulting from succession of poor fen (base‐poor mire) to willow wet woodland on Goss Moor NNR in Cornwall, UK. Different ages of willow carr were associated with eight understorey communities. During willow colonization, in the ground flora, there was a progressive decrease in poor fen species and an associated increase in woodland species, which appeared to be related to an increase in canopy cover and therefore shade. The most diverse community was found to be the most recent willow and was dominated by poor fen species. The oldest willow was the second most diverse and was associated with a reduction in poor fen species and an increase in woodland species. Architectural features were used successfully to assess the general condition and structure of willow. Tree height and DBH were identified as useful parameters to accurately assess willow age in the field. The implications of active intervention to remove willow in order to conserve the full range of communities within the hydrosere are discussed.     

Structural and Functional Analysis of Fucose-Processing Enzymes from Streptococcus pneumoniae

Fucose metabolism pathways are present in many bacterial species and typically contain the central fucose-processing enzymes fucose isomerase (FcsI), fuculose kinase (FcsK), and fuculose-1-phosphate aldolase (FcsA). Fucose initially undergoes isomerization by FcsI producing fuculose, which is then phosphorylated by FcsK. FcsA cleaves the fuculose-1-phosphate product into lactaldehyde and dihydroxyacetone phosphate, which can be incorporated into central metabolism allowing the bacterium to use fucose as an energy source. Streptococcus pneumoniae has fucose-processing operons containing homologs of FcsI, FcsK, and FcsA; however, this bacterium appears unable to utilize fucose as an energy source. To investigate this contradiction, we performed biochemical and structural studies of the S. pneumoniae fucose-processing enzymes SpFcsI, SpFcsK, and SpFcsA. These enzymes are demonstrated to act in a sequential manner to ultimately produce dihydroxyacetone phosphate and have structural features entirely consistent with their observed biochemical activities. Analogous to the regulation of the Escherichia coli fucose utilization operon, fuculose-1-phosphate appears to act as an inducing molecule for activation of the S. pneumoniae fucose operon. Despite our evidence that S. pneumoniae appears to have the appropriate regulatory and biochemical machinery for fucose metabolism, we confirmed the inability of the S. pneumoniae TIGR4 strain to grow on fucose or on the H-disaccharide, which is the probable substrate of the transporter for the pathway. On the basis of these observations, we postulate that the S. pneumoniae fucose-processing pathway has a non-metabolic role in the interaction of this bacterium with its human host.     

高寒藏药—抱茎獐牙菜组织培养研究及其愈伤组织有效成分的测定

从抱茎獐牙菜的胚轴、幼叶及未成熟种子诱导出愈伤组织并再生植株,试验选用ＭＳ、Ｂ５和Ｎ６三种培养基,其中以附加２．４－Ｄ３．０ｍｇ／Ｌ＋６－ＢＡ０．５ｍｇ／Ｌ的ＭＳ培养基诱导率最高;以附加６－ＢＡ０．５ｍｇ／Ｌ＋ＮＡＡ０．２ｍｇ／Ｌ的ＭＳ培养基分化苗频率最高;以附加２．４－Ｄ２．０ｍｇ／Ｌ＋６－ＢＡ０．５ｍｇ／Ｌ的ＭＳ培养基愈伤组织的生长最好。结果表明,外植体,培养基,激素等对愈伤组织诱导、继代和分化均有明显影响。采用高压液相色谱法（ＨＰＬＣ）测定抱茎獐牙菜愈伤组织中齐墩果酸含量的结果表明,愈伤组织中齐果墩酸含量因培养基、继代培养时间的不同而有所差异     

库恩菇属一新组合种(国内新记录)

本文报导了A.H.Smith和L.R.Hesler1968年命名的Pholiota conica A.H.Smith et L.R.Hesler在我国的新记录, 并根据R.Singer1975年的分类系统进行了新组合Kuehneromyces conicus(A.H.Smith et L.R.Hesler)J.B.Wang et Z.B.Chen comb.nov.     

Micropropagation of Eucalyptus tereticornis Smith.

Axillary shoot bud multiplication has been achieved in Eucalyptus tereticornis Smith. using explants from different regions of 8–10 years old elite trees, growing in the field. Results showed that addition of NAA at 0.1 mgl^-1 and BAP at 1.0 mgl^-1 to modified MS medium induced maximum number of shoot buds. For inducing axial growth in regenerated bud promordia, the hormone concentration of the medium was lowered. The addition of charcoal and gibberellic acid to the medium were beneficial. Rooting was best in Knop's medium containing 1.0 mgl^-1 IBA. The key factor in root induction was primarily a dark incubation for a short period. The percentage of both rooting of shoots and survival of the rooted shoots was 60–80.Continuous trials using explants from the elite trees throughout the year showed that the period between July–September was the best season for the explant source for rapid and increased multiplication of axillary buds. Phenolic exudation was also minimum at this period. The experiments were repeated using 50 populations from different plantations. It was observed that during culture, genotypically different populations responded differently in spite of optimal growth conditions.     

In vitro stimulation of cell death in the moulting glands of Oncopeltus fasciatus by 20-hydroxyecdysone

The moulting glands of the milkweed bug, Oncopeltus fasciatus, normally degenerate just before the time of ecdysis to an adult (day 7 of the fifth instar). Morphologically normal cell death can be prematurely stimulated in vitro by 20-hydroxyecdysone. Breakdown is triggered by a 24-hr period of exposure to 20-hydroxyecdysone, but an additional incubation period is required before clear signs of degeneration are manifested. Glands removed after the onset of endogenous ecdysteroid secretion degenerate in vitro in the absence of added hormones. Thus, in the moulting glands of Oncopeltus, ecdysteroids appear to act as an important trigger for metamorphic cell death.     

A 13C NMR spin-lattice relaxation study of the interaction of myelin proteins with lipid vesicles

Natural abundance 13C nuclear magnetic spin-lattice relaxation times have been measured for bovine brain phosphatidylserine vesicles with and without bound proteins. The relaxation times were lower than published values for the corresponding nuclei in egg phosphatidylcholine, but showed the same trend, with relaxation times increasing along the acyl chains away from the polar headgroup. These times were inversely related to the degree of saturation of the lipid. Cytochrome c caused insignificant changes in the lipid acyl chain relaxation rates but reduced the resonance intensities, in agreement with Brown and Wüthrich (Biochem. Biophys. Acta 468 (1977) 389). In contrast, the basic protein from bovine myelin did not affect the intensities but reduced the relaxation times for 13C nuclei near the bilayer centre, and for nuclei near carbon-carbon double bonds. These proteins also dramatically broadened the serine headgroup carboxyl resonance. It appears, in accord with other recent evidence, that the basic protein does penetrate the hydrophobic region of the bilayer (possibly to the centre), producing quantitatively similar changes in the relaxation rates to proteolipid protein, an integral membrane protein.     

Cholinesterase enzymes in the blood of patients with Alzheimer's disease

Plasma pseudocholinesterase activity was about 100% higher in patients with Alzheimer's-type dementia than in similar age controls. Red cell acetylcholinesterase activity tended to be lower in patients than controls. Administration of lecithin substantially increased plasma choline levels but did not alter activity of either of the cholinesterase enzymes.