Isolation and characterization of a Forssman antigen-binding lectin from velvet bean (Mucuna derringiana) seeds

A Forssman antigen (GalNAc1-3GalNAc1-3Gal1-4Gal1-4Glc1-1Cer)-binding lectin has been purified from velvet bean (Mucuna derringiana) seeds by a combination of affinity chromatography and reversed phase HPLC. This lectin agglutinates both native and trypsin-treated sheep erythrocytes as well as trypsinized rabbit erythrocytes, but neither native rabbit nor human erythrocytes, irrespective of blood group type. SDS-PAGE and gel filtration chromatography reveal the lectin to be a homodimer consisting of two 54 kDa subunits linked by non-covalent bonds. The results obtained by quantitative precipitation, haemagglutination inhibition and TLC overlay assays indicate that theMucuna lectin specifically recognizes Forssman antigen and Forssman disaccharide (GalNAc1-3GalNAc)-related structures. Abbreviations: The abbreviations and the trivial names used are: AH, 6-aminohexyl; BSA, bovine serum albumin; Cer, ceramide; HPLC, high performance liquid chromatography; PAGE, polyacrylamide gel electrophoresis; PBS, 10mm phosphate-buffered saline, pH 7,2, containing 0.15m NaCl; PMSF, phenyl methyl sulfonyl fluoride; SDS, sodium dodecyl sulphate; TFA, trifluoroacetic acid; TBS, 20mm tris-buffered saline, pH 7.2; TLC, thin-layer chromatography; A disaccharide, GalNAc1-3Gal; A trisaccharide, GalNAc1-3[Fuc1-2]Gal; Forssman disaccharide, GalNAc1-3GalNAc; CDH (ceramide dihexoside or lactosyl ceramide) Gal1-4Glc1-1Cer (LacCer); CTH (ceramide trihexoside or globotriosyl ceramide), Gal1-4Gal1-4Glc1-1Cer (GbOse₃Cer or Gb₃); globoside (globotetraosyl ceramide), GalNAc1-3Gal1-4Gal1-4Glc1-1Cer (GbOse₄Cer or Gb₄); Forssman antigen (globopentaosyl ceramide), GalNAc1-3GalNAc1-3Gal1-4Gal1-4Glc1-1Cer (GbOse₅Cer).     

Effects of growth under elevated UV-B on photosynthesis and isoprene emission in Quercus gambelii and Mucuna pruriens

Increasing surface levels of UV-B resulting from stratospheric ozone reduction directly affect tropospheric photochemistry. There may also be indirect tropospheric effects due to changes in emission of organic compounds from vegetation. We treated woody and herbaceous isoprene-emitting species in the field with supplemental UV-B simulating 30% ozone depletion. For Quercus gambelii, photosynthesis and isoprene emission were significantly greater in elevated UV-B treatments when expressed on a leaf area basis, but not on a leaf mass basis. Leaves of Mucuna pruriens, however, showed no significant differences in photosynthesis or isoprene emission between treatments, nor when exposed for 45 min to acute high levels of UV-B. Elevated UV-B during growth did not elicit significant isoprene emission from Acer platanoides, a non-emitting species. Other potential UV-B effects, such as changes in leaf area or species composition, which may influence regional isoprene emissions, should be examined.     

中国一新记录亚种——多褶果黧豆(豆科)

作者在给中国科学院植物研究所生态室鉴定标本时, 发现一西藏新记录属--黧豆属(Mucuna Adans.), 所鉴定标本是多褶果黧豆Mucuna hainanensis ssp.multilamellata Wilmot-Dear, 为一中国新记录亚种, 现特予报道。     

Concentric leaf spot of yam (Dioscorea spp) in South-western Nigeria

The etiology and epidemiology of concentric leaf spot and seedling blight diseases of yam (Dioscorea spp) was investigated at Jbadan, south western Nigeria, in the low land humid tropics. Sclerotium rolfsii was associated with the concentric leaf spot and seedling blight of yam. The pathogen was also harbored by weeds namely Mucuna pruriensis, Commelina erecta, ipomea triloba, I. involucrataand Ipomoea sp found growing within the yam plots. A high mean inoculum densities of 3.0 ± 0.5 × 10⁶ colony forming unit/g of soil was estimated in the soil samples obtained from the yam plots This revised version was published online in June 2006 with corrections to the Cover Date.     

Floral traits of mammal‐pollinated Mucuna macrocarpa (Fabaceae): Implications for generalist‐like pollination systems

Floral traits are adapted by plants to attract pollinators. Some of those plants that have different pollinators in different regions adapt to each pollinator in each region to maximize their pollination success. Mucuna macrocarpa (Fabaceae) limits the pollinators using its floral structure and is pollinated by different mammals in different regions. Here, we examine the relationships between floral traits of M. macrocarpa and the external morphology of mammalian pollinators in different regions of its distribution. Field surveys were conducted on Kyushu and Okinawajima Island in Japan, and in Taiwan, where the main pollinators are the Japanese macaque Macaca fuscata, Ryukyu flying fox Pteropus dasymallus, and red‐bellied squirrel Callosciurus erythraeus, respectively. We measured the floral shapes, nectar secretion patterns, sugar components, and external morphology of the pollinators. Results showed that floral shape was slightly different among regions and that flower sizes were not correlated with the external morphology of the pollinators. Volume and sugar rate of nectar were not significantly different among the three regions and did not change throughout the day in any of the regions. However, nectar concentration was higher in Kyushu than in the other two regions. These results suggest that the floral traits of M. macrocarpa are not adapted to each pollinator in each region. Although this plant limits the number of pollinators using its flower structure, it has not adapted to specific mammals and may attract several species of mammals. Such generalist‐like pollination system might have evolved in the Old World.     

Who can open the flower? Assessment of the flower opening force of mammal‐pollinated Mucuna macrocarpa

Effective pollinators in Fabaceae species with papillionaceous flowers should have sufficient force to open the petals and expose the stamens and pistils from the keel petals. Here, we assessed the force that is required (operative force) to open the petals of the mammal‐pollinated Mucuna macrocarpa, in parallel with estimating the force of bee species. The operative force of M. macrocarpa was quantified by a digital force gauge and the force of three bee species that frequent these flowers was estimated from body mass. The operative force was 1.635 ± 0.146 (mean ± SD) newton (N). This force was far larger than that estimated for the largest bee in the study area. In addition, the operative force of M. macrocarpa was 16–409 times greater than that of bee‐pollinated plants. Our results demonstrate that the operative force of M. macrocarpa flowers is adapted to mammalian openers, preventing potential nectar robbers.     

Bioconversion of para-substituted monophenolic compounds into corresponding catechols by alginate entrapped cells ofMucuna pruriens

Alginate-entrapped cells ofM. pruriens were able to convert a number of parasubstituted monophenolic compounds into the corresponding catechols. All catechols produced were released into the medium, which offered the opportunity to isolate these products via a relatively simple procedure. Prepurification was performed on a Sephadex G10 gel and catechols were concentrated on Affigel 601. The identity of all products was confirmed with combined liquid chromatography/mass spectrometry (LC/MS) or MS using the desorption chemical ionization technique, depending on the catechol. For the entrapped cells and for a cell homogenate prepared of the same cell line ofM. pruriens the substrate specificities were qualitatively identical when judged on initial rates of synthesis calculated on protein basis.     

The belonging of gpMuc, a glycoprotein from Mucuna pruriens seeds, to the Kunitz-type trypsin inhibitor family explains its direct anti-snake venom activity

In Nigeria, Mucuna pruriens seeds are locally prescribed as an oral prophylactic for snake bite and it is claimed that when two seeds are swallowed they protect the individual for a year against snake bites. In order to understand the Mucuna pruriens antisnake properties, the proteins from the acqueous extract of seeds were purified by three chromatographic steps: ConA affinity chromatography, tandem anionic-cationic exchange and gel filtration, obtaining a fraction conventionally called gpMucB. This purified fraction was analysed by SDS-PAGE obtaining 3 bands with apparent masses ranging from 20 to 24 kDa, and by MALDI-TOF which showed two main peaks of 21 and 23 kDa and another small peak of 19 kDa. On the other hand, gel filtration analysis of the native protein indicated a molecular mass of about 70 kDa suggesting that in its native form, gpMucB is most likely an oligomeric multiform protein. Infrared spectroscopy of gpMucB indicated that the protein is particularly thermostable both at neutral and acidic pHs and that it is an all beta protein.All data suggest that gpMucB belongs to the Kunitz-type trypsin inhibitor family explaining the direct anti-snake venom activity of Mucuna pruriens seeds.     

Assessment of nodulation of Mucuna pruriens by promiscuous indigenous rhizobia in the moist savanna zone of Nigeria

Leucaena leucocephala failed to nodulate effectively with promiscuous indigenous rhizobia with which Mucuna pruriens nodulated effectively. Mucuna pruriens was adequately established and well nodulated due to the presence of favourable climatic and edaphic factors which enhanced its establishment in the humid/moist savanna zone of Nigeria. The microsymbiont for M. pruriens seems to thrive more in an alkaline rhizosphere. Introduction of M. pruriens into the farming system in Nigeria may serve as a low input agricultural system, which is not only sustainable but also economically viable.     

Rat- and bat-pollination of Mucuna championii (Fabaceae) in Hong Kong

Mucuna (Fabaceae) species possess gullet-type flowers that open explosively and which are thought to be specifically adapted for bat- or bird-pollination. However, recent studies have shown that non-flying mammals are also important pollinators of this genus in Asia. Here we report on the pollination system of Mucuna championii (endemic in southeast China) in Hong Kong. As is typical for the genus, explosive opening is essential for fruit set, but flowers are unable to open in the absence of manipulation by an effective pollinator. Camera trap surveys of three individuals revealed both chestnut spiny rats (Niviventer fulvescens) and short-nosed fruit bats (Cynopterus sphinx) to be capable of triggering explosive opening. The number of flowers opened by each species did not differ significantly, and both removed most pollen grains from the flowers they visited, but either species visited different individuals. Sucrose-rich nectar was secreted by flowers throughout the day. Our results reveal that M. championii can be pollinated by both rats and bats, with this representing only the second report of rat-pollination in tropical Asia. The sympatric M. birdwoodiana often occurs in close proximity to M. championii and has an overlapping flowering season, suggesting that pollinator segregation may have played a role in shaping the evolutionary ecology of these two species.