Litter production and leaf nutrient concentration and remobilization in response to climate seasonality in the central Amazon

Litterfall is the largest source of nutrients to for-est soils of tropical rainforests.However,variability in lit-terfall production,nutrient remobilization,and changes in leaf nutrient concentration with climate seasonality remain largely unknown for the central Amazon.This study meas-ured litterfall production,leaf nutrient remobilization,and leaf area index on a forest plateau in the central Amazon.Litterfall was measured at monthly intervals during 2014,while nitrogen,phosphorus,potassium,calcium and mag-nesium concentrations of leaf litter and canopy leaves were measured in the dry and rainy seasons,and remobilization rates determined.Leaf area index was also recorded in the dry and rainy seasons.Monthly litterfall varied from 33.2(in the rainy season)to 87.6 g m^(-2) in the dry season,while leaf area index increased slightly in the rainy season.Climatic seasonality had no effect on concentrations of nitrogen,calcium,and magnesium,whereas phosphorous and potassium responded to rainfall seasonality oppositely.While phosphorous increased,potassium decreased during the dry season.Over seasons,nitrogen,potassium,and phosphorous decreased in leaf litter;calcium increased in leaf litter,while magnesium remained unaffected with leaf aging.Regardless,the five nutrients had similar remobilization rates over the year.The absence of climate seasonality on nutrient remobilization suggests that the current length of the dry season does not alter nutrient remobilization rates but this may change as dry periods become more prolonged in the future due to climate change.

Microsatellites and the Polyploid Guarana Plant:Diversity under a Sea of Alleles

Repeat blocks, microsatellites or simple sequence repeats (SSRs) can produce good co-dominant molecular markers for genetic diversity analysis and the determination of self-pollination rates in progenies originating from open pollination of selected genotypes. The enrichment of guarana genomic libraries was underway when it was confirmed that we are working with a complex polyploid species with 210 chromosomes. The probes (CA)12, (CT)12 and (TC)14 were used to finish the enrichment of four libraries for repeat blocks and the screening of a databank of expressed sequence tags (ESTs) from guarana seeded-fruits was accomplished as well. Fifteen clonal cultivars were genotyped with three replicas at 10 out of 27 identified loci using the 59 alleles that passed the reproducibility criterion. A large number of short repeat blocks were identified and this was considered to be a consequence of the recent polyploidization event. However, blocks with eight or more repeats ideal for genotyping were scarce. Annealing of most probes to short blocks by partial complementarity could explain the scarcity of longer blocks in genomic libraries but cannot explain why they were rare in the ESTs. Due to the complexity of the genotypes, alleles were treated as dominant traits. ESTs harboring repeat blocks had the functional annotation renewed. Locus GRN07 is inserted in a homologue of the MOTHER OF FLOWERING LOCUS T AND TFL1 (MFT), in which 3’-UTR displays clear post-transcriptional regulatory features. MFT and its variants are probably involved in the determination of seed germination and embryo growth characteristics. Other accessed loci can be involved in plant architecture and defense reactions. It was concluded that the alleles described in the present work can be used to distinguish guarana cultivars and possibly to analyze segregation using the progenies of controlled pollinations between divergent genitors. Also, the fingerprints obtained can be added to the morphological and agronomic descriptors of the cultivars.

Opposite latitudinal gradients for species richness and phylogenetic diversity of endemic snakes in the Atlantic Forest

The decrease in species richness toward higher latitudes is an expected biogeographical pattern.This pattern could be related to particular envi-ronmental constraints and the evolutionary history of clades.However,species richness does not fully represent the evolutionary history of the clades behind their distributions.Phylogenetic diversity better clarifies the role of historical factors in biogeographical patterns.We analyzed envi-ronmental and historical drivers related to latitudinal variation in species richness and phylogenetic diversity of Atlantic Forest endemic snakes.We implemented species distribution models,from voucherbased locality points,to map the snake ranges and diversity.We used generalized additive mixed models to evaluate the relationships among the diversity metrics and area,topographical roughness,and past climate change velocity since the Last Maximum Glacial in the Atlantic Forest latitudinal gradient.Contrary to the expected general pattern,species richness was higher toward higher latitudes,being positively related to past climatic stability.Species richness also increased with total area and higher topographical roughness.Phylogenetic diversity,on the other hand,showed opposite relationships related to the same factors.Phylogenetic diversity increased with lower climatic stability in lower latitudes.Thus,dimensions of diversity were affected in different ways by historical and environmental constraints in this unique and threatened biodiversity hotspot.

Biochemical Changes of Cubiu Fruits (Solanum sessiliflorum Dunal, Solanaceae) According to Different Tissue Portions and Ripening Stages

Cubiu fruits (Solanum sessiliflorum Dunal, Solanaceae) are known for their high nutritional value and low caloric content. This work aimed at evaluating biochemical indices of cubiu fruits according to different tissues (peel, pulp and placenta) and ripening stages (green, turning, ripe and fully ripe). The fruits were randomly harvested to investigate sensory aspects (colorimetry, blanching effect, pigments) and biochemical indices (moisture and dry matter, Total Soluble Solids (TSS), pH, Titratable Acidity (TA), TSS/TA ratio, ascorbic acid, Alcohol-Insoluble Solids (AIS), pectinesterase activity and pectin content). The analyses were performed at the laboratory of Instituto Nacional de Pesquisas da Amazonia (INPA), Manaus, Brazil. The blanching process preserved pulp colors at all ripening stages. Chlorophylls were higher in green peels;flavonoids and carotenoids, in fully ripe peels. Anthocyanins were entirely absent. Pulp (turning fruits) showed the highest moisture content (91.05), followed by ripe pulp (90.70) and fully ripe pulp (90.62). Pulp TSS changed little whereas placenta TSS declined and were associated with increased TA and pH reduction (fully ripe fruits). Pulp pH and TA varied little whereas placenta pH was notably low and TA was remarkably high (fully ripe fruits). Pulp TSS/TA ratio showed predominance of TSS while in placenta, there was predominance of organic acids. AIS, precursors of pectin, were stable during ripening. The statistical analysis of dietary fiber content showed one modal value in the AIS. In pulp, pectinesterase activity correlated inversely with pectin content. Cubiu fruits were significant sources of bioactive compounds, e.g. chlorophylls, flavonoids and carotenoids, predominantly in the peel and the pulp;soluble functional fibers, e.g. pectin (g/100 g fresh weight), particularly in the green peel (1.00) and the fully ripe pulp (1.12), and other versatile molecules, e.g. ascorbic acid (mg/100 g fresh weight), especially in the fully ripe peel (32.45) and placenta (24.84) and the turning placenta (21.27). Cubiu fruits are rich in ascorbic acid and should be included in the human diet.

Ancient DNA of the pygmy marmoset type specimen Cebuella pygmaea(Spix,1823)resolves a taxonomic conundrum

The pygmy marmoset,the smallest of the anthropoid primates,has a broad distribution in Western Amazonia.Recent studies using molecular and morphological data have identified two distinct species separated by the Napo and Solimoes-Amazonas rivers.However,reconciling this new biological evidence with current taxonomy,i.e.,two subspecies,Cebuella pygmaea pygmaea(Spix,1823)and Cebuella pygmaea niveiventris(Lönnberg,1940),was problematic given the uncertainty as to whether Spix’s pygmy marmoset(Cebuella pygmaea pygmaea)was collected north or south of the Napo and Solimoes-Amazonas rivers,making it unclear to which of the two newly revealed species the name pygmaea would apply.Here,we present the first molecular data from Spix’s type specimen of Cebuella pygmaea,as well as novel mitochondrial genomes from modern pygmy marmosets sampled near the type locality(Tabatinga)on both sides of the river.With these data,we can confirm the correct names of the two species identified,i.e.,C.pygmaea for animals north of the Napo and Solimoes-Amazonas rivers and C.niveiventris for animals south of these two rivers.Phylogenetic analyses of the novel genetic data placed into the context of cytochrome b gene sequences from across the range of pygmy marmosets further led us to reevaluate the geographical distribution for the two Cebuella species.We dated the split of these two species to 2.54 million years ago.We discuss additional,more recent,subdivisions within each lineage,as well as potential contact zones between the two species in the headwaters of these rivers.

亚马孙流域与河流化学相关的人体汞污染

在淡水生物区系中,溶解有机碳(DOC)和pH是影响汞含量的两个主要因子。DOC与汞络合促使汞向水生生态系统的传输和积累。低pH环境宜于汞的甲基化及其在水生食物链中的生物淀积。汞在食肉鱼类体内的富集与DOC呈正相关,而与pH则呈负相关关系。在亚马孙河一条名为内格罗河的黑水支流上游,我们在食鱼人群中遇到了相似的模式。人类汞污染最严重的区域均位于DOC异常高及低pH值支流中。在考虑了其他亚马孙河支流的数据后,一个总体模式随之产生。头发中的汞含量与河水中的DOC呈正相关,而与pH值呈负相关关系。金矿挖掘对汞污染没有明显的影响。研究结果表明了河流化学在确定亚马孙流域汞污染模式中的重要性。

A new method for quantification of total polyphenol content in medicinal plants based on the reduction of Fe(III)/1,10-phenanthroline complexes

This paper proposes an alternative analytical spectrophotometric method for the total polyphenol quantification in the aqueous extract of plants. When these extracts are added to solutions of Fe(III), in presence of 1,10-phenanthroline, the absorbance values at 551 nm (A511nm) due to the complexes formed are proportional to the total polyphenol concentration expressed as pyrogallic acid (PA). A typical calibration graph of A511nm values vs. PA is linear from 0.16 to 0.64 mg L-1 (r = 0.994, n = 6) with a limit of detection 0.041 mg L-1. The results of the polyphenol content of the aqueous extracts of twenty medicinal Brazilian plants obtained with the proposed method were compared with values using the Folin-Ciocalteu reagent. A paired t-test revealed no statistically significant difference for the species analyzed. The total antioxidant capacity of the same twenty extracts was determined based on the scavenging of stable radical DPPH.

Molecular Study of the Genetic Variability of Pumpkins Landraces from Brazilian Amazon

The Cucurbita maxima Duchesne is a vegetable crop plant cultivated and maintained by traditional Amazon communities, Brazil. The situation is worsened by the possibility of disappearance of local populations and genetic variability of this specie, taking into account the today changes promoted in family farming. The aim of this study was to estimate the current levels of genetic variability of local cultivars through the use of molecular markers (Amplified Fragment Length Polymorphism—AFLP). We chose to collect in two distinct micro regions in order to identify possible influences of geographic isolation and different levels of market requirements in the conservation of the genetic variability of the C. maxima. For the molecular analysis, bulk samples of fresh leaves of 15 plants/half-sibling family were collected in paper bags. There were 34 samples from the half-sib families. The analysis of the results half-sib obtained by methods of estimation of genetic variation by molecular markers shows that the forms of cultivation and management adopted by family farmers maintain the identities of the local/landraces (native cultivars) and, at the same time, the levels of diversity for the assurance of adaptability macro-environmental.

Queens remate despite traumatic mating in stingless bees

Males can control female reproduction using genital plugs to impede access by rivals.In social bees,ants,and wasps,plugging may involve traumatic mating,with females being harmed.In stingless bees,chances are that plugs may promote ovarian activan,and are thought to ensure single mating—a general tendency among the social Hymenoptera.However,understanding on relationships between mating plugs,traumatic mating,and mating systems in stingless bees remains limited.To address this,we(1)compared mated queens of 7 Neotropical species to understand the patterns of copulatory marks in females and(2)compared pre-and post-mating genitalia of males and females in Melipona fasciculata to depict plug functional morphology.Data revealed an unprecedented consequence of mating in stingless bees:the characteristic marks left by mating plugs on female abdomens and the inferences that can be made from them.To our surprise,in 1 species M.fasciculata we found that queens retain the plug long after mating,and may carry it for the rest of their lives.All the other 6 species retained the plug for only a short period.Remated queens were only found in M.seminigra,whose multiple copulatory marks match previous findings of polyandry in this species.Our study shows that queens can remate,and suggests that male genital morphology may determine in part the time persistence of plugs.We conclude that traumatic mating plugs do not fully prevent remating in stingless bees and that mating systems are not uniform in this group.Nonetheless,exceptional cases of facultative polyandry in social insects—for example,when mating plugs fail—may confirm a general tendency for single mating in close link with efficient mating plugs.