A new Bauhinia monandra galactose-specific lectin purified in milligram quantities from secondary roots with antifungal and termiticidal activities

This work describes the purification in milligram quantities of a lectin from Bauhinia monandra secondary roots (BmoRoL) and its antifungal and termiticidal activities. The BmoRoL (6.2 mg) was isolated through ammonium sulfate fractionation and affinity chromatography on guar gel. Native lectin was resolved as a single band on polyacrylamide gel electrophoresis for basic proteins. Under denaturing and reducing conditions it appeared as a unique glycosylated polypeptide of 26 kDa. The highest agglutination activity of BmoRoL was found with glutaraldehyde-treated rabbit erythrocytes. BmoRoL showed antifungal activity against phytopathogenic species of Fusarium and was more active on Fusarium solani. The lectin also showed termiticidal activity on Nasutitermes corniger workers and soldiers with LC₅₀ of 0.09 and 0.395 mg ml⁻¹ for 12 days. In conclusion, BmoRoL is a new antifungal and termiticidal lectin that can be purified in milligram quantities and has potential biotechnological application for control of agricultural pests.     

Revisión taxonómica del complejo Bauhinia macranthera (Fabaceae: Caesalpinioideae: Cercideae), un grupo endémico del centro y noreste de México

Resumen  La presente revisión tuvo como objetivo la resolución del complejoBauhinia macranthera. Por medio de un estudio de morfología comparada que incluyó polen, se reconocen aBauhinia bartlettii, B. macranthera yB. ramosissima; se restableceB. retifolia y se propone aB. ramosissima var. uniflora, como nueva combinación.

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The purpose of this study was the resolution of theBauhinia macranthera complex using comparative morphology, including pollen.Bauhinia bartlettii, B. macranthera B. ramosissima, andB. retifolia are recognized, andB. ramosissima var. uniflora is proposed as a new combination.

     

The peptidases of Trypanosoma cruzi: Digestive enzymes, virulence factors, and mediators of autophagy and programmed cell death

Trypanosoma cruzi, the agent of the American Trypanosomiasis, Chagas disease, contains cysteine, serine, threonine, aspartyl and metallo peptidases. The most abundant among these enzymes is cruzipain, a cysteine proteinase expressed as a mixture of isoforms, some of them membrane-bound. The enzyme is an immunodominant antigen in human chronic Chagas disease and seems to be important in the host/parasite relationship. Inhibitors of cruzipain kill the parasite and cure infected mice, thus validating the enzyme as a very promising target for the development of new drugs against the disease. In addition, a 30 kDa cathepsin B-like enzyme, two metacaspases and two autophagins have been described. Serine peptidases described in the parasite include oligopeptidase B, a member of the prolyl oligopeptidase family involved in Ca²⁺-signaling during mammalian cell invasion; a prolyl endopeptidase (Tc80), against which inhibitors are being developed, and a lysosomal serine carboxypeptidase. Metallopeptidases homologous to the gp63 of Leishmania spp. are present, as well as two metallocarboxypeptidases belonging to the M32 family, previously found only in prokaryotes. The proteasome has properties similar to those of other eukaryotes, and its inhibition by lactacystin blocks some differentiation steps in the life cycle of the parasite. This article is part of a Special Issue entitled: Proteolysis 50 years after the discovery of lysosome.     

Defence,growth and nutrient allocation in the tropical shrub Bauhinia brevipes (Leguminosae)

Herbivory in natural communities can be high, reducing the growth and reproduction of individual plants. To diminish the impact of herbivores, plants use a variety of defensive mechanisms. It is now recognized that the plant world is characterized by a proliferation of secondary metabolites, but models of the evolution of defence strategies assume that plants are constrained by finite resources, and that defences are costly. In the present study, the relationships between defence, growth and nutrient concentration in Bauhinia brevipes Vog. (Leguminosae) in south‐eastern Brazil were investigated. Patterns of herbivory and defence were examined for 170 B. brevipes individuals in 1997 and 1998. Leaf age influenced tannin concentration and herbivore attack on B. brevipes. Mature leaves had higher concentrations of tannins than young leaves, and young leaves were approximately 60% more likely to be attacked than mature leaves. Carbon and nitrogen content explained 36% of the variation in the percentage of attacked leaves in B. brevipes (y = 16.29 – 0.31 C + 0.25 N; r² = 0.36; F = 9.56; P < 0.0001). Tannins acted as defensive compounds on B. brevipes leaves against free‐feeding herbivores, but no clear pattern was observed against galling herbivores. The amounts of nitrogen, carbon, potassium, and aluminium explained approximately 69% of the variation in tannin concentration on B. brevipes leaves (y = 0.62 – 0.16 N – 0.36 K – 0.26 Al + 0.74 C; r² = 0.69; F = 21.18; P < 0.0001). We found an inverse relationship between shoot growth rates and tannin concentration in B. brevipes, indicating that the production of tannins may be costly, therefore offering some evidence for the trade‐off hypothesis. Nevertheless, the weak relationship observed between herbivore damage and tannin concentration indicates that other factors are also involved with herbivore pressure.     

羊蹄甲属中国特有种的花粉形态学

对羊蹄甲属植物11种中国特有种的花粉形态进行了研究。结果表明,花粉萌发孔类型均为三孔沟,少数还有合沟;花粉均具半覆盖层,表面纹饰有皱波状、皱波状-穿孔、疣状、孔穴-穿孔、穿孔-网状。依据Larsen(1975)的划分,这11种植物的花粉隶属于Integrifolia型、Glauca型和Curtisii型,我们根据花粉纹饰的差异在Integrifolia型下进一步划分了Auma亚型和Paucinervata亚型。     

Comparative responses of three fuel wood yielding plants to PEG-induced water stress at seedling stage

Three species of fast growing fuel wood yielding plants locally available (Acacia holosericea, Bauhinia variegata and Cassia siamea) were characterized in respect of their responses to water stress. Seedlings (25 days) of these species, exposed to two levels of water stress (−0.5 and −1.0 MPa) induced by PEG-6000 for 24 h, were analysed for relative water content (RWC) and the contents of chlorophyll, protein, soluble sugars and proline in leaves along with activities of catalase, peroxidase and superoxide dismutase (SOD). RWC was lower in stressed compared to the unstressed seedlings. However, stress-induced decline in RWC was lowest in B. variegata. Chlorophyll and protein contents declined with increasing levels of water stress, decline being least in B. variegata. Soluble sugar and proline contents increased under water stress particularly in B. variegata. The enzyme activity of catalase (EC-1.11.1.6), peroxidase (EC-1.11.1.7) and SOD (EC-1.15.1.1) decreased with increased levels of water stress. Such decline in the activity of these enzymes was least in B. variegata. Apparently, B. variegata is potentially the species most tolerant to water stress among these three fuel wood-yielding plants.     

Immunocytochemical evidence for the involvement of golgi apparatus in the deposition of seed lectin ofBauhinia purpurea (Leguminosae)

Summary The seed lectin of the tree legume,Bauhinia purpurea alba, was localized by electron microscopic immunocytochemistry. The pattern of lectin deposition and site of intracellular localization was examined in mid- to late-maturation seeds. The seed tissue was embedded in Lowicryl K4M, the use of which with seed tissues is discussed. Immunocytochemical labeling was accomplished with colloidal gold coupled to a second antibody. The immunocytochemical reaction was specific and sensitive. Protein bodies, Golgi apparatus and Golgi secretion vesicles were densely labeled. Golgi apparatus was oriented such that Golgi secretion vesicles were in close proximity to the protein bodies. The entire Golgi apparatus was labeled with no concentration gradient across the Golgi stack. These observations indicate that the final site of lectin deposition is the protein body, and that the Golgi apparatus plays an essential role in the deposition process.     

Patterns of fruit and seed production inBauhinia ungulata (Leguminosae)

Patterns of seed and fruit production ofBauhinia ungulata, a small tree legume indigenous in tropical America, were studied in Costa Rica. Only about 8% of flowers produced fruits. The average pod had 19 ovules and about two thirds of these began seed development, with mature pods containing an average of 9.7 mature undamaged seeds. About half of the mature pods were damaged by herbivores and within these, 27% of ovules or seeds had been eaten. Among trees there was no significant variation in pod production, but the number of ovules per pod and seed production per pod varied significantly. Within infructescences most pods were retained at middle positions. Within pods, the probability of an ovule developing into a seed increased toward the distal end. The pattern of seed and fruit production in this species agrees well in general with that reported for other neotropical legumes. The abortion of seeds and fruits can be regarded as a way of controlling maternal investment, and as a response to herbivory.     

Bauhinia forficata lectin (BfL) induces cell death and inhibits integrin-mediated adhesion on MCF7 human breast cancer cells

Background

Plant lectins have attracted great interest in cancer studies due to their antitumor activities. These proteins or glycoproteins specifically and reversibly bind to different types of carbohydrates or glycoproteins. Breast cancer, which presents altered glycosylation of cell surface glycoproteins, is one of the most frequent malignant diseases in women. In this work, we describe the effect of the lectin Bauhinia forficata lectin (BfL), which was purified from B. forficata Link subsp. forficata seeds, on the MCF7 human breast cancer cellular line, investigating the mechanisms involved in its antiproliferative activity.

Methods

MCF7 cells were treated with BfL. Viability and adhesion alterations were evaluated using flow cytometry and western blotting.

Results

BfL inhibited the viability of the MCF7 cell line but was ineffective on MDA-MB-231 and MCF 10A cells. It inhibits MCF7 adhesion on laminin, collagen I and fibronectin, decreases α₁, α₆ and β₁ integrin subunit expression, and increases α₅ subunit expression. BfL triggers necrosis and secondary necrosis, with caspase-9 inhibition. It also causes deoxyribonucleic acid (DNA) fragmentation, which leads to cell cycle arrest in the G2/M phase and a decrease in the expression of the regulatory proteins pRb and p21.

Conclusion

BfL shows selective cytotoxic effect and adhesion inhibition on MCF7 breast cancer cells.

General significance

Cell death induction and inhibition of cell adhesion may contribute to understanding the action of lectins in breast cancer.     

The varieties of Bauhinia pottsii G. Don in Thailand (Leguminosae-Caesalpinioideae)

 Bauhinia pottsii G. Don, B. subsessilis Craib, B. velutina (Wall. ex Benth.) Baker, B. mollissima (Wall.) Prain, and B. decipiens Craib were recently recognized as five varieties of Bauhinia pottsii G. Don. They grow naturally in southern Myanmar, Thailand, Indochina and the Malay Peninsula. Bauhinia pottsii var. decipiens (Craib) K. Larsen & S. S. Larsen is endemic to Thailand and known only from the type collection, so it was omitted from this study. Quantitative and qualitative morphological characters were examined in 200 specimens using multivariate and univariate analyses to determine the taxonomic relationship among the four. Some variation in qualitative characters was found between the varieties which separated them as previously defined in Flora of Thailand. Forty-three quantitative characters were subjected to cluster analysis to allow an objective classification into groups. The groups were subsequently evaluated by a canonical discriminant analysis. It was found that these characters collectively support the four varieties as defined by qualitative characters. However, the close relationship of varieties mollissima (Wall. ex Prain) K. Larsen & S. S. Larsen and velutina (Wall. ex Benth.) K. Larsen & S. S. Larsen is observed. The linear discriminant function has an overall rate of 98.5% correct classification and is useful for variety classification. Among quantitative characters, petal-claw length and ovarystalk length together with some qualitative characters are useful for key construction to separate the four varieties. Received April 24, 2001 Accepted December 11, 2001