Spittle protein profile of Mahanarva spectabilis (Hemiptera: Cercopidae) fed various elephant grass genotypes.

An understanding of the interaction between spittlebugs and forage grasses is essential for establishing factors that favor productive pastures. In the present study, we evaluated the protein profiles of the spittle of Mahanarva spectabilis (Distant, 1909) (Hemiptera: Cercopidae) fed various elephant grass genotypes. Each plant was infested with a single fifth-instar M. spectabilis. After 24 h, samples of the spittle produced by each nymph were collected and stored at -20°C, after which their protein profiles were analyzed. The exclusivity or interactions of the proteins present in the spittle produced by the insects revealed the susceptibility of the tested genotypes. The results indicate that groups of genotypes show identical spittle protein profiles when subjected to attack by spittlebugs. Resistant and susceptible elephant grass genotypes exhibited high similarity indices within each group. The similarity index was low for the resistance control species (Brachiaria brizantha) compared with that of the tested elephant grass genotypes. Qualitative and quantitative studies of the proteins expressed in the most promising materials will be performed in an ongoing genetic improvement program seeking to develop genotypes resistant to spittlebugs, which are the main biotic pests of elephant grasses.

Propagação vegetativa de Brosimum gaudichaudii Tréc. (mama-cadela) por estacas de raízes / Vegetative propagation of Brosimum gaudichaudii Tréc. (mama-cadela) by root cuttings

Brosimum gaudichaudii Tréc. (mama-cadela) é uma planta medicinal nativa do Cerrado, utilizada na medicina tradicional. O objetivo deste trabalho foi verificar a possibilidade de propagação de mama-cadela por meio de estacas de raízes, sob o efeito de reguladores de crescimento e de diferentes substratos. No experimento 1 foram avaliados os efeitos da aplicação de ácido indol-butírico (AIB) e ácido naftaleno-acético (ANA) na concentração de 1000 mg L-1 e três substratos (S1- areia; S2 - 75 por cento de areia + 25 por cento de substrato comercial; S3 - 50 por cento de areia + 50 por cento de substrato comercial). No experimento 2 foram avaliadas 4 doses de AIB: 0 - testemunha; 250 mg L-1 (1,3426 mM ); 500 mg L-1 (2,6853 mM) e 1000 mg L-1 (5,3706 mM); e 4 doses de ácido naftaleno-acético (ANA): 0 - testemunha; 250 mg L-1 (1,2295 mM); 500 mg L-1 (2,458 mM); e 1000 mg L-1 (4,918 mM). O delineamento experimental utilizado foi de blocos ao acaso com três repetições de seis estacas por parcela. No experimento 1, os substratos compostos por areia e areia (75 por cento) + substrato comercial (25 por cento) proporcionaram os maiores Índices de pegamento. A aplicação de AIB (1000 mg L-1) proporcionou aumentos relativos de 30,8 por cento e 51,3 por cento, no IMP quando comparada com a testemunha e a aplicação de ANA, respectivamente. No experimento 2, observou-se resposta quadrática significativa da aplicação de AIB sobre o IMP. A dose de 500 mg L-1 (2,6853 mM) promoveu maior IMP. Não houve efeito significativo das doses de ANA para os parâmetros avaliados. Não houve efeito significativo relevante de substratos ou hormônios sobre os demais parâmetros avaliados. Estes resultados evidenciam o potencial de utilização de estacas de raiz de mama-cadela para a produção de mudas clonais desta espécie.

Brosimum gaudichaudii Tréc. (mama-cadela) is a medicinal plant native to Cerrado and largely used in traditional medicine. The aim of this study was to verify the propagation of mama-cadela by means of root cutting under the effect of plant growth regulators and different substrates. In experiment 1, the effects of indole butyric acid (IBA) and naphthylacetic acid (NAA) at the concentration of 1000 mg L-1 were evaluated together with three substrates (S1 - sand; S2 - 75 percent sand + 25 percent commercial substrate; S3 - 50 percent sand + 50 percent commercial substrate). In experiment 2, 4 IBA levels were evaluated: 0 - control; 250 mg L-1 (1.3426 mM ); 500 mg L-1 (2.6853 mM) and 1000 mg L-1 (5.3706 mM), as well as 4 NAA levels: 0 - control; 250 mg L-1 (1.2295 mM); 500 mg L-1 (2.458 mM) and 1000 mg L-1 (4.918 mM). The adopted experimental design was in randomized blocks with three replicates of six cuttings per plot. In experiment 1, substrates containing sand and sand (75 percent) + commercial substrate (25 percent) promoted the highest average rooting indexes. Application of IBA (1000 mg L-1) led to increases of 30.8 percent and 51.3 percent in the average rooting indexes compared to control and NAA application, respectively. In experiment 2, there was a significant quadratic response of IBA application on the average rooting index. The level of 500 mg L-1 (2.6853 mM) promoted the highest average rooting index. There was no significant effect of NAA levels for the evaluated parameters. Similarly, there was no significant effect of substrates or hormones on the remaining parameters evaluated. These results show the potential use of mama-cadela root cuttings for the production of clonal seedlings of this species.

Anti-inflammatory and analgesic activities of the latex containing triterpenes from Himatanthus sucuuba.

Some triterpenes and iridoids were previously isolated from the stem bark of Himatanthus sucuuba. The latex from Himatanthus sucuuba is used in popular amazonian medicine as an anti-inflammatory remedy. Fractions of the latex were pharmacologically evaluated with a view to verify this popular use in the carrageenan-induced rat paw edema and in the acetic acid-induced mouse constriction tests. The hexane fraction inhibited the edema formation by 35.9% at a dose of 200 mg/kg (p.o.) but no activity was observed at 100 mg/kg (p.o.). The triterpenes present in the hexane fraction were identified as lupeol acetate, alpha-amyrin and lupeol cinnamates. The fraction containing only cinnamates inhibited the edema and the abdominal constrictions by 50-40% and 57.9%, respectively, at 100 mg/kg (p.o.). Among all the fractions studied, the fraction containing only cinnamates showed the greatest anti-inflammatory activity which suggests that these compounds were responsible for the previously described activity of the crude extract.

Processing, activity, and inhibition of recombinant cyprosin, an aspartic proteinase from cardoon (Cynara cardunculus).

The cDNA encoding the precursor of an aspartic proteinase from the flowers of the cardoon, Cynara cardunculus, was expressed in Pichia pastoris, and the recombinant, mature cyprosin that accumulated in the culture medium was purified and characterized. The resultant mixture of microheterogeneous forms was shown to consist of glycosylated heavy chains (34 or 32 kDa) plus associated light chains with molecular weights in the region of 14,000-18,000, resulting from excision of most, but not all, of the 104 residues contributed by the unique region known as the plant specific insert. SDS-polyacrylamide gel electrophoresis under non-reducing conditions indicated that disulfide bonding held the heavy and light chains together in the heterodimeric enzyme forms. In contrast, when a construct was expressed in which the nucleotides encoding the 104 residues of the plant specific insert were deleted, the inactive, unprocessed precursor form (procyprosin) accumulated, indicating that the plant-specific insert has a role in ensuring that the nascent polypeptide is folded properly and rendered capable of being activated to generate mature, active proteinase. Kinetic parameters were derived for the hydrolysis of a synthetic peptide substrate by wild-type, recombinant cyprosin at a variety of pH and temperature values and the subsite requirements of the enzyme were mapped using a systematic series of synthetic inhibitors. The significance is discussed of the susceptibility of cyprosin to inhibitors of human immunodeficiency virus proteinase and particularly of renin, some of which were found to have subnanomolar potencies against the plant enzyme.

Characterization of early induced genes in Arabidopsis thaliana responding to bacterial inoculation: identification of centrin and of a novel protein with two regions related to kinase domains.

The early response to bacterial inoculation has been investigated and two Arabidopsis genes, ap3.3a and ap4.3a have been characterized. The AP3.3A protein showed high identity to centrin, a ubiquitous cytoskeletal protein first identified in unicellular green alga. Amino-acid sequence analyses of the AP4.3A protein indicates that the second gene characterized encodes an unusual protein with two putative kinase domains. Expression of ap3.3a and ap4.3a was rapidly induced after pathogen inoculation. A role of ap3.3a in plant defense could be postulated based on its preferential induction during the incompatible interactions analyzed. In contrast, activation of ap4.3a was not specific and could be related to a more general stress response.

Arabidopsis thaliana class IV chitinase is early induced during the interaction with Xanthomonas campestris.

Endochitinases are widely distributed among higher plants, including a number of important crop species. They are generally considered to be involved in plant defence against potential pathogens. We have cloned a class IV chitinase gene (AtchitIV) from Arabidopsis thaliana. Southern blot analysis allowed the detection of two cross-hybridising genes in the A. thaliana genome. AtchitIV transcripts are detected in seedpods, but not in roots, inflorescence stems, leaves and flowers of healthy plants. The transcripts accumulated very rapidly in leaves after inoculation with Xanthomonas campestris. Maximum mRNA accumulation was reached one hour after infection and decreased to very low levels 72 hours after induction. This result suggests an involvement of AtchitIV in the initial events of the hypersensitive reaction. Nevertheless, A. thaliana plants transformed with the gus gene under the control of a class IV chitinase bean promoter, showed GUS activity in seed embryos. These data, together with the constitutive expression of the endogenous gene in the seedpods, points to additional physiological roles for this protein.

Desmin filaments in the electrocytes of the electric organ of the electric eel Electrophorus electricus.

Desmin protein is an abundant constituent of the intermediate filaments in the electrocytes of the electric organ of the electric eel Electrophorus electricus. Polyclonal antibodies were raised against purified desmin from the electric organ and used for immunolabeling of the protein in reconstituted filaments. In thick sections of the main electric organ that has been stained with fluorescein-labeled desmin-specific antibodies, light microscope revealed a diffuse meshwork of desmin filaments dispersed in the cytoplasm of electrocytes. In the region under the membrane, the immunostaining was slightly more intense than elsewhere. The meshwork of intermediate filaments composed of desmin was examined by electron microscopy of the main electric organ. Immuno-gold labeling demonstrated a widespread meshwork of desmin filaments in the cytoplasm and in close association with the plasma membrane. These observations suggest that intermediate filaments play a role in the maintenance of the morphology of electrocytes and, as an intracellular meshwork spanning the width of the cell, they may contribute to the organization of the intracellular compartments.

Isolation and characterization of a cDNA from flowers of Cynara cardunculus encoding cyprosin (an aspartic proteinase) and its use to study the organ-specific expression of cyprosin.

Poly(A)+ RNA isolated from flower buds of Cynara cardunculus has been used to prepare a cDNA library. Screening of the cDNA after expression of cloned DNA with antibodies raised against the large subunit of cyprosin 3 resulted in the isolation of six positive clones. One of these clones (cypro1s; a 1.7 kb Eco RI fragment) codes for cyprosin. The nucleotide sequence contain a 1419 bp open reading frame coding for 473 amino acids (aa) including a putative full-length mature protein (440 aa) and a partial prosequence (33 aa). Cypro1s contains a 162 bp 3' non-coding region followed by a poly(A) tail. The deduced amino acid sequence shows high homology to other plant aspartic proteinases. The homology to mammalian and microbial aspartic proteinases is somewhat lower. Plant aspartic proteinases contain an insert of around 100 aa. We are modelling where this plant-specific insert will appear in the structure of cyprosin. Using cypro1s as a probe in northern blot analysis, the expression of cyprosin in developing flowers and other tissues has been studied. The signal on the northern blot increased for RNA samples from early (flower buds 6 mm in length) to later stages of floral development (flower buds up to 40 mm in length). In late stages of floral development (open flowers 50 mm in length and styles from such flowers) no hybridization signal was visualized showing that the synthesis of mRNA encoding the cyprosin starts in early stages of floral development and switches off at maturation of the flower.(ABSTRACT TRUNCATED AT 250 WORDS)