Characterization of the ecology of endangered timber species is a crucial step in any forest management strategy. In this study, we described the animal communities involved in seed dispersal and predation of a high‐value timber species Guibourtia tessmannii (Fabaceae; Detarioideae), which is newly listed on Appendix II of CITES. We compared the animal communities between two forest sites (Bambidie in Gabon and Ma'an in Cameroon). A total of 101 hr of direct observations and 355 days of camera trapping revealed that a primate (Cercopithecus nictitans nictitans) and a hornbill (Ceratogymna atrata) were important seed dispersers in Gabon. Conversely, a greater presence of a rodent (Cricetomys emini), which could act both as predator and disperser, was observed in Cameroon. This study suggests that animal communities involved in seed dispersal of G. tessmannii may vary depending on environmental conditions and anthropogenic impacts. However, further studies are needed to properly identify the factors involved in seed dispersal and predation of G. tessmannii. 相似文献
Knowledge of spatial patterns of biological diversity is fundamental for ecological and biogeographical analyses and for priority setting in nature conservation, particularly in West Africa where the existing high biodiversity is increasingly threatened by human activities. The maximum entropy approach was used to model the geographic distribution of 3,393 vascular plant species at a spatial resolution of 0.0833°. Species richness decreases along temperature and precipitation gradients with high species numbers in the south and lower numbers towards the north of the transect. All centres of plant species diversity are confined to humid areas in concordance with the high positive correlation between species richness and rainfall which appears to be the most important delimiter for the distribution ranges of many species in the area. The effectiveness of the existing protected areas at regional and national levels is investigated based on the proportion of species covered. Considering the whole study area, 95% of all species are covered by protected areas according to their distribution ranges. However, the proportion of species covered is considerably lower for some countries such as Benin and Togo. Our results could provide guidance for essential land use management interventions to decision‐makers and conservationists in the region. 相似文献
Heavy metals are considered some of the most toxic environmental pollutants. Exposure to heavy metals including lead (Pb), cadmium (Cd), arsenic (As), and methyl mercury (MeHg) has long been known to cause damage to human health. Many recent studies have supported the hippocampus as the major target for these four metals for inflicting cognitive dysfunction. In the present study, we proposed hippocampal relevant in vitro toxicity of Pb, Cd, As, and MeHg in HT-22 cell line. This study reports, initially, cytotoxic effects in acute, subchronic, chronic exposures. We further investigated the mechanistic potency of DNA damage and apoptosis damage with the observed cytotoxicity. The genotoxicity and apoptosis were measured by using the comet assay, annexin-V FTIC / propidium iodide (PI) assay, respectively. The results of cytotoxicity assay clearly demonstrated significant concentration and time-dependent effects on HT-22 cell line. The genotoxic and apoptosis effects also concentration-dependent fashion with respect to their potency in the range of IC10–IC30, maximal level of damage observed in MeHg. In conclusion, the obtained result suggests concentration and potency-dependent response; the maximal level of toxicity was observed in MeHg. These novel findings support that Pb, Cd, As, and MeHg induce cytotoxic, genotoxic, and apoptotic effects on HT-22 cells in potency-dependent manner; MeHg> As> Cd> Pb. Therefore, the toxicity of Pb, Cd, As, and MeHg could be useful for knowing the common underlying molecular mechanism, and also for estimating the mixture impacts on HT-22 cell line.
Artemisinin-ferrocene conjugates incorporating a 1,2-disubstituted ferrocene analogous to that embedded in ferroquine but attached via a piperazine linker to C10 of the artemisinin were prepared from the piperazine artemisinin derivative, and activities were evaluated against asexual blood stages of chloroquine (CQ) sensitive NF54 and CQ resistant K1 and W2 strains of Plasmodium falciparum (Pf). The most active was the morpholino derivative 5 with IC50 of 0.86?nM against Pf K1 and 1.4?nM against Pf W2. The resistance indices were superior to those of current clinical artemisinins. Notably, the compounds were active against Pf NF54 early and late blood stage gametocytes – these exerted >86% inhibition at 1?µM against both stages; they are thus appreciably more active than methylene blue (~57% inhibition at 1?µM) against late stage gametocytes. The data portends transmission blocking activity. Cytotoxicity was determined against human embryonic kidney cells (Hek293), while human malignant melanoma cells (A375) were used to assess their antitumor activity. 相似文献
Legume plants develop nodules during their symbiotic interaction with rhizobia, and much progress has been made towards understanding Nod factor perception and downstream signaling pathways, while our knowledge about the maintenance of nodule organogenesis was limited. We report here the knockdown mutants of LjCOCH, an ortholog of COCHLEATA in Pisum sativum, cause severe defects in nodule organogenesis in Lotus japonicus. The mature nodule number was drastically decreased accompanied with abnormal lenticel and vascular bundle developmental defects, but not produce roots from nodules in both Ljcoch mutants and LjCOCH-RNAi transgenic hairy roots. LjAPP1, a membrane-associated soluble aminopeptidase P1, was identified to interact with LjCOCH through yeast two-hybrid screening. Unlike that of Ljcoch mutants, insertion mutants of LjAPP1 and LjAPP1-RNAi transgenic hairy roots showed increased nodule number, while the lenticel and vascular development were not affected. Gene expression analysis indicated that LjCOCH and LjAPP1 were differentially upregulated by rhizobia inoculation, and LjNF-YA1 was the major downstream target of LjCOCH and LjAPP1. Our findings suggested that LjCOCH acts as a key factor involved in determinate nodule development through direct interaction with LjAPP1 to regulate the expression of LjNF-YA1, opposite effects of LjCOCH and LjAPP1 provide a dynamic regulation of nodule development in L. japonicus. 相似文献
Pterygiella luzhijiangensis Huan C. Wang, is described and illustrated as a new species endemic to Yunnan, southwest China. It occurs in thickets of the Luzhijiang hot‐dry valley at elevations of 1000–1300 m a.s.l. This new species is closely related to P. duclouxii Franch., but clearly differs from the latter by its procumbent stems, much branched at the base, 7–20 cm long, the leaves 1.0–2.2 cm long, 0.1–0.2 (0.25) cm wide, the corolla 2.0–2.2 cm long, obviously longer than the calyx, with the lower lip of the corolla much longer than the upper one. 相似文献