Isolation of biologically active peptides from the venom of Japanese carpenter bee, Xylocopa appendiculata

Background Mass spectrometry-guided venom peptide profiling is a powerful tool to explore novel substances from venomous animals in a highly sensitive manner. In this study, this peptide profiling approach is successfully applied to explore the venom peptides of a Japanese solitary carpenter bee, Xylocopa appendiculata (Hymenoptera: Apoidea: Apidae: Anthophila: Xylocopinae: Xylocopini). Although interesting biological effects of the crude venom of carpenter bees have been reported, the structure and biological function of the venom peptides have not been elucidated yet. Methods The venom peptide profiling of the crude venom of X. appendiculata was performed by matrix-assisted laser desorption/ionization-time of flight mass spectroscopy. The venom was purified by a reverse-phase HPLC. The purified peptides were subjected to the Edman degradation, MS/MS analysis, and/or molecular cloning methods for peptide sequencing. Biological and functional characterization was performed by circular dichroism analysis, liposome leakage assay, and antimicrobial, histamine releasing and hemolytic activity tests. Results Three novel peptides with m/z 16508, 1939.3, and 1900.3 were isolated from the venom of X. appendiculata. The peptide with m/z 16508 was characterized as a secretory phospholipase A2 (PLA2) homolog in which the characteristic cysteine residues as well as the active site residues found in bee PLA2s are highly conserved. Two novel peptides with m/z 1939.3 and m/z 1900.3 were named as Xac-1 and Xac-2, respectively. These peptides are found to be amphiphilic and displayed antimicrobial and hemolytic activities. The potency was almost the same as that of mastoparan isolated from the wasp venom. Conclusion We found three novel biologically active peptides in the venom of X. appendiculata and analyzed their molecular functions, and compared their sequential homology to discuss their molecular diversity. Highly sensitive mass analysis plays an important role in this study.(AU)

Isolation of biologically active peptides from the venom of Japanese carpenter bee, Xylocopa appendiculata

Abstract Background Mass spectrometry-guided venom peptide profiling is a powerful tool to explore novel substances from venomous animals in a highly sensitive manner. In this study, this peptide profiling approach is successfully applied to explore the venom peptides of a Japanese solitary carpenter bee, Xylocopa appendiculata (Hymenoptera: Apoidea: Apidae: Anthophila: Xylocopinae: Xylocopini). Although interesting biological effects of the crude venom of carpenter bees have been reported, the structure and biological function of the venom peptides have not been elucidated yet. Methods The venom peptide profiling of the crude venom of X. appendiculata was performed by matrix-assisted laser desorption/ionization-time of flight mass spectroscopy. The venom was purified by a reverse-phase HPLC. The purified peptides were subjected to the Edman degradation, MS/MS analysis, and/or molecular cloning methods for peptide sequencing. Biological and functional characterization was performed by circular dichroism analysis, liposome leakage assay, and antimicrobial, histamine releasing and hemolytic activity tests. Results Three novel peptides with m/z 16508, 1939.3, and 1900.3 were isolated from the venom of X. appendiculata. The peptide with m/z 16508 was characterized as a secretory phospholipase A2 (PLA2) homolog in which the characteristic cysteine residues as well as the active site residues found in bee PLA2s are highly conserved. Two novel peptides with m/z 1939.3 and m/z 1900.3 were named as Xac-1 and Xac-2, respectively. These peptides are found to be amphiphilic and displayed antimicrobial and hemolytic activities. The potency was almost the same as that of mastoparan isolated from the wasp venom. Conclusion We found three novel biologically active peptides in the venom of X. appendiculata and analyzed their molecular functions, and compared their sequential homology to discuss their molecular diversity. Highly sensitive mass analysis plays an important role in this study.

A gynandromorph of Xylocopa nigrocincta Smith (Hymenoptera: Apidae) / Un ginandromorfo de Xylocopa nigrocincta Smith (Hymenoptera: Apidae)

We describe a mixed gynandromorph of Xylocopa (Neoxylocopa) nigrocincta from a single specimen from Argentina. The specimen presents bilateral asymmetry, with the right half of its head displaying male characters and the left half displaying female characters; the mesosoma presents male characters mostly in the right half of the prothorax, pronotal lobe and distal half of the fore tibia and in the pubescence of tarsus; the rest of the mesosoma and the metasoma display female features

Se describe un ginandromorfo mixto de Xylocopa (Neoxylocopa) nigrocincta de un ejemplar de Argentina. El ginandromorfo tiene asimetría bilateral en la cabeza, con su mitad derecha con caracteres del macho y su mitad izquierda con caracteres de la hembra. El mesosoma presenta algunas características de macho en la mitad anterior derecha (protorax, lóbulo pronotal, mitad posterior de la protibia y pubescencia del tarso), el resto de meso y metasoma con caracteres de la hembra.

Xylocopa (Monoxylocopa) abbreviata Hurd & Moure (Hymenoptera: Apidae) e Encholirium spectabile (Bromeliaceae): uma associação estreita no semi-árido do Brasil tropical / Xylocopa (Monoxylocopa) abbreviata Hurd & Moure (Hymenoptera: Apidae) and Encholirium spectabile (Bromeliaceae): a tight association at the semi-arid of Brazil

Xylocopa (Monoxylocopa) abbreviata Hurd & Moure nidifica nas hastes de inflorescências de Encholirium spectabile (Bromeliaceae), que crescem expostas ao sol nos afloramentos rochosos das caatingas do semi-árido. No maior agregado, a densidade de X. abbreviata pode alcançar 1,7 ninho/haste e 20 ninhos/ha. Cada haste pode abrigar ninhos por cerca de três meses, apenas, mas a floração contínua e assincrônica na população de E. spectabile assegura oferta ao longo do ano todo. A haste é compacta, porém macia, e a fêmea escava uma única galeria linear em poucos dias. A galeria linear abriga, em média, cinco células de cria sem revestimento interno, que são separadas entre si por divisória elaborada com o material triturado do próprio substrato. A galeria fica isolada do meio externo por uma fina parede da haste. Quando perturbada, a fêmea fundadora bloqueia totalmente a entrada circular do ninho, com o dorso do seu abdome. Embora use um substrato de nidificação efêmero, esta espécie de Xylocopa apresenta várias gerações ao longo do ano. Colocam-se em perspectiva as restrições comportamentais e ecológicas relacionadas à escolha desse tipo de substrato conspícuo e efêmero. Argumenta-se que a escolha das hastes de Encholirium restringe a distribuição a porções de hábitats restritos do semi-árido e determina a relativa raridade de X. abbreviata nessa região do Brasil.

Females of Xylocopa (Monoxylocopa) abbreviata Hurd & Moure build their nests in the flower stalks of Encholirium spectabile (Bromeliaceae). This bromeliad grows clumped on rock outcrops exposed to direct sunlight in the semi-arid tropical caatingas of northeastern Brazil. In the largest aggregation of E. spectabile, X. abbreviata reached 1,7 nests/stalk and around 20 nests/ha. The stalks are available as nest site after fruiting, and can be used for three months before final decaying. However the flowering asynchronism within local population assures good stalks almost all year round. The flower stalk is filled with a soft pulp where the female dig a single linear nest gallery in a few days. The single linear gallery keeps five brood cells, on average. The top of each cell is delimitated with the powdered material from the stalk pulp, and no lining bee material was observed on the inner cell walls. The cell gallery is isolated from the outside by a thin stalk wall that is exposed to direct sunlight. When disturbed the founder female blocks the entrance with the dorsum of its abdomen. Although using an ephemeral nesting substrata, X. abbreviata presented several generations all year round. Ecological and behavioral constraints upon this Xylocopa species are discussed concerning the tight association with the conspicuous and ephemeral stalks of E. spectabile. This association is also assumed to determine the patchy distribution and the rarity of X. abbreviata in the semi-arid region.