RESUMO
Asparagaceae's large embryo sacs display a central cell nucleus polarized toward the chalaza, which means the sperm nucleus that fuses with it during double fertilization migrates an atypical long distance before karyogamy. Because of the size and inverted polarity of the central cell in Asparagaceae, we hypothesize that the second fertilization process is supported by an F-actin machinery different from the short-range F-actin structures observed in Arabidopsis and other plant models. Here, we analyzed the F-actin dynamics of Agave inaequidens, a classical Asparagaceae, before, during, and after the central cell fertilization. Several parallel F-actin cables, spanning from the central cell nucleus to the micropylar pole, and enclosing the vacuole, were observed. As fertilization progressed, a thick F-actin mega-cable traversing the vacuole appeared, connecting the central cell nucleus with the micropylar pole near the egg cell. This mega-cable wrapped the sperm nucleus in transit to fuse with the central cell nucleus. Once karyogamy finished, and the endosperm started to develop, the mega-cable disassembled, but new F-actin structures formed. These observations suggest that Asparagaceae, and probably other plant species with similar embryo sacs, evolved an F-actin machinery specifically adapted to support the migration of the fertilizing sperm nucleus within a large-sized and polarity-inverted central cell.
RESUMO
With more than 200 species, the genus Agave is one of the most interesting and complex groups of plants in the world, considering for instance its great diversity and adaptations. The adaptations include the production of a single, massive inflorescence (the largest among plants) where after growing for many years, sometimes more than 30, the rosette dies shortly afterward, and the remarkable coevolution with their main pollinators, nectarivorous bats, in particular of the genus Leptonycteris. The physiological adaptations of Agave species include a photosynthetic metabolism that allows efficient use of water and a large degree of succulence, helping to store water and resources for their massive flowering event. Ecologically, the agaves are keystone species on which numerous animal species depend for their subsistence due to the large amounts of pollen and nectar they produce, that support many pollinators, including bats, perching birds, hummingbirds, moths, and bees. Moreover, in many regions of Mexico and in the southwestern United States, agaves are dominant species. We describe the contributions of H. S. Gentry to the understanding of agaves and review recent advances on the study of the ecology and evolution of the genus. We analyze the present and inferred past distribution patterns of different species in the genus, describing differences in their climatic niche and adaptations to dry conditions. We interpret these patterns using molecular clock data and phylogenetic analyses and information of their coevolving pollinators and from phylogeographic, morphological, and ecological studies and discuss the prospects for their future conservation and management.
Assuntos
Agave , Animais , Abelhas , Ecologia , México , Filogenia , Polinização , Sudoeste dos Estados UnidosRESUMO
Bioassay-guided isolation using an in vitro assay testing for anti- schistosomiasis yielded a novel triterpene saponin, asparagalin A, from the n-butanol extract of the roots of Asparagus stipularis Forssk., Asparagaceae. The structure was elucidated by spectroscopic analysis and chemical transformations. Administration of asparagalin A resulted in a retardation of worm growth and locomotion at the first day and showed a significant activity of egg-laying suppression at 200 µg/mL concentration.
RESUMO
The hemolytic, anti-inflammatory and antinociceptive properties from hydrolyzed extract Agave sisalana Perrine ex Engelm., Asparagaceae (HEAS) was evaluated on classic inflammation models. Male Swiss mice and male Wistars rats received HEAS (500 mg/kg) in two administration p.o. and i.p. in saline solution 0.9 percent. The acid hydrolysis inhibited the hemolytic action of saponins due to the retreat of side chain sugar. The treatment of the ear induced oedema by xylene with HEAS significantly reduced in two routes 13±1.5 and 10±0.63 mg, respectively, p.o. and i.p., in comparison with controls 27±1.5 saline and 13.5±1.2 AAS. The HEAS also diminished edema induced by carrageenin 43±1.58 mg (p.o.) and 17±1.26 mg (i.p.), when compared with control groups 52±1.58 mg (saline) and 10.05±1.58 (indomethacin). HEAS showed analgesic effects in abdominal constrictions 30.7 percent (p.o.), 88.7 percent (i.p.) comparable to that produced by (AAS) 70.6 percent. However in granuloma cotton pellet a chronic model of inflammation just the i.p. pathway decreased granulomatous tissue (20.4±1.32 mg) compared with controls 30.5±2.53 mg (saline) and 20.2±2.18 mg (dexamethasone). These data suggest that HEAS has anti-inflammatory and analgesic activity on acute and chronic processes.
As propriedades hemolítica, anti-inflamatória e antinociceptiva do extrato hidrolisado de Agave sisalana Perrine ex Engelm, Aparagaceae (HEAS) foram avaliadas em modelos clássicos de inflamação. Camundongos Swiss e ratos Wistars machos receberam HEAS (500 mg/kg) em duas vias de administração p.o e i.p em solução salina 0.9 por cento. A hidrólise ácida inibiu a ação hemolítica das saponinas através da retirada das cadeias laterais de açúcar. O tratamento com HEAS reduziu significativamente o edema de orelha induzido por xilol em duas vias 13±1.5 e 10±0.63 mg respectivamente, p.o e i.p, em comparação com os controles 27±1.5 salina e 13.5±1.2 AAS. O HEAS também diminuiu o edema induzido por carragenina 43±1.58 mg (p.o) e 17±1.26 mg (i.p), quando comparado com os grupos controle 52±1.58 (salina) e 10.05±1.58 (indometacina). HEAS apresentou efeito analgésico em modelo de contorções abdominais 30.7 por cento (p.o), 88.7 por cento (i.p) comparado com aquele produzido pelo (AAS) 70.6 por cento. Contudo, no modelo crônico de inflamação granuloma cotton pellet apenas a via i.p diminuiu o tecido granulomatoso (20.4±1.32 mg) comparado com os controles 30.5±2.53 (salina) e 20.2±2.18 mg (dexametasona). Esses dados sugerem que o HEAS possui atividades anti-inflamatória e analgésica em processos agudos e crônicos.