Concept: Cycas revoluta
The Asian cycads are mostly allopatric, distributed in small population sizes. Hybridization between allopatric species provides clues in determining the mechanism of species divergence. Horticultural introduction provides the chance of interspecific gene flow between allopatric species. Two allopatrically eastern Asian Cycas sect. Asiorientales species, C. revoluta and C. taitungensis, which are widely distributed in Ryukyus and Fujian Province and endemic to Taiwan, respectively, were planted in eastern Taiwan for horticultural reason. Higher degrees of genetic admixture in cultivated samples than wild populations in both cycad species were detected based on multilocus scans by neutral AFLP markers. Furthermore, bidirectional but asymmetric introgression by horticultural introduction of C. revoluta is evidenced by the reanalyses of species associated loci, which are assumed to be diverged after species divergence. Partial loci introgressed from native cycad to the invaders were also detected at the loci of strong species association. Consistent results tested by all neutral loci, and the species-associated loci, specify the recent introgression from the paradox of sharing of ancestral polymorphisms. Phenomenon of introgression of cultivated cycads implies niche conservation among two geographic-isolated cycads, even though the habitats of the extant wild populations of two species are distinct.
First record of Crypticerya zeteki (Cockerell, 1914) (Monophlebidae) in Brazil and Maconellicoccus hirsutus (Green, 1908) (Pseudococcidae) in the state of Maranhão
- Brazilian journal of biology = Revista brasleira de biologia
- Published over 1 year ago
Crypticerya zeteki (Cockerell, 1914) (Hemiptera: Coccomorpha: Monophlebidae) is recorded for the first time from Brazil and Maconellicoccus hirsutus (Green, 1908) (Hemiptera: Coccomorpha: Pseudococcidae) is recorded for the first time from the state of Maranhão, Brazil. Both species were collected from branches, leaves and fruits of various fruit trees in the municipalities of São José de Ribamar, São Luís and Paço do Lumiar, Maranhão, Brazil. Crypticerya zeteki was collected on Citrus spp. (Rutaceae), Cocos nucifera (L.) (Arecaceae), Cycas revoluta L. (Cycadaceae), Malpighia punicifolia L. (Malpighiaceae), Mangifera indica L. (Anacardiaceae), Musa paradisiaca L. (Musaceae) and Theobroma grandiflorum Schum (Malvaceae), all first records for this species. Maconellicoccus hirsutus was collected on Spondias tuberosa Arruda (Anacardiaceae) and M. punicifolia L. (Malpighiaceae), both new records for this species.
Chilades pandava (Lepidoptera: Lycaenidae) larval food quality was studied to determine its influence on adult life history traits. A wild population from Cycas nongnoochiae (Cycadales: Cycadaceae) endemic habitat behaved similarly to the population collected from a garden setting. Cycas micronesica, Cycas revoluta, and Cycas seemannii leaves were used as high-quality food, whereas C nongnoochiae, Cycas taitungensis, and Cycas condaoensis leaves were used as low-quality food. The daily oviposition rate was not influenced by food quality, but longevity and lifetime fecundity of females were increased by high-quality larval food. These results indicate that in situ Cycas species impose a physiological constraint on the genetic capacity to produce offspring by C pandava. The removal of that constraint by high-quality novel Cycas species may be one reason this butterfly can increase in population rapidly after an invasion event and express greater herbivory of Cycas species within invaded regions.
Transglycosylation (TG) activity of a family GH18 chitinase from the cycad, Cycas revoluta, (CrChiA) was modulated by removing or introducing a tryptophan side chain. The removal from subsite +3 through mutation of Trp168 to alanine suppressed TG activity, while introduction into subsite +1 through mutation of Gly77 to tryptophan (CrChiA-G77W) enhanced TG activity. The crystal structures of an inactive double mutant of CrChiA (CrChiA-G77W/E119Q) with one or two N-acetylglucosamine residues occupying subsites +1 or +1/+2, respectively, revealed that the Trp77 side chain was oriented toward +1 GlcNAc to be stacked with it face-to-face, but rotated away from subsite +1 in the absence of GlcNAc at the subsite. Aromatic residues in the aglycon-binding site are key determinants of TG activity of GH18 chitinases.
Phytochemical investigation of the ethyl acetate extract of Cycas revoluta Thunb. leaflets afforded five compounds including two new dihydroamentoflavone glucosides, (2S)-I-(2,3)-dihydro-I-7-O-β-d-glucopyranosylamentoflavone (1) and (2S)-I-(2,3)-dihydro-I-7,II-7-di-O-β-d-glucopyranosylamentoflavone (2), in addition to the known compounds prunin (3), vitexin-2″-rhamnoside (4) and protocatechuic acid (5). Compounds (3) and (4) being reported for the first time in this plant. The structures of these compounds were established by the detailed analysis of their spectroscopic data, mainly 1D NMR, 2D NMR, CD and HR-MSD-TOF. The ethyl acetate extract showed weak cytotoxicity against HepG2 (IC50 = 207.6 μg/mL) and RAW 264.2 cells (IC50 = 160.8 μg/mL). Compound 4 showed significant activity towards Leishmania donavani (IC50 = 13.8 μM, IC90 = 34.6 μM). The isolated compounds showed weak antimicrobial activity (IC50>10 μg/mL).
• Premise of the study: Thermogenesis is a prominent pollination-related feature of cycad cones and is generally assumed to play a role in pollination. Although typically studied just before, during, and immediately after the cones' pollination phase, thermogenesis may be present in other cone developmental phases.• Methods: We assayed thermogenesis in Cycas micronesica, Guam’s endangered cycad, over successive cone developmental phases by measuring temperatures in shaded and unshaded in situ cones for up to 7 wk. We also studied the effect of ambient conditions on cone thermogenesis in laboratory experiments and estimated the cones' metabolic heating rates.• Key results: Pollen cones exhibit a continuous, but small, metabolically generated thermogenesis for multiple weeks, including a single thermogenic peak temperature greater than peak ambient each day. The magnitudes of those daily peak temperature elevations above ambient reach maxima twice during cone development: a few days before dehiscence and approximately 1 wk post-dehiscence. Excised cones in dark, fixed temperature environments generated multiple thermogenic events (∼24 h period) over ∼10 d. Cones appear to initiate a protective temperature regulatory response at temperatures ≥∼38°C.• Conclusions: Cycas micronesica pollen cones exhibit several thermogenic attributes not reported in other cycads, including continuous thermogenesis for many weeks. These cones grow in a hot tropical environment that likely confines their metabolically generated temperature increases to a small thermogenic window beyond which they encounter heat stress. These findings suggest the presence of thermogenic functions not strictly related to pollination and a potential vulnerability to warming climates.