Seasonal flooding changes chemical and morphometric characteristics of the tropical floodplain lakes, affecting stratification which can influence mercury dynamics. We investigate the influence of ...flooding on the mercury dynamics in an Amazon floodplain lake. Three points on the lake, the Solimões River, and the connecting channel to the river were sampled along the annual flood pulse. During high-water, the lake was deep (12.7 m, on average) and the area farthest from the river was stratified with low oxygen and high methylmercury concentrations (MeHg) at depths below 7 m (0.37 ng l
−1
, on average). The two sites closest to the river were destratified and the MeHg was lower (0.077 ng l
−1
, on average along all depths). At low-water, the lake was shallower (3 m, on average) and destratified, with higher oxygen concentrations, and no difference in MeHg along the water column at all lake sites. Independent of season, the MeHg in the connecting channel was higher than those in the river. The MeHg in phytoplankton varied in response to changes in biomass, showing a biodilution effect. Variations in lake morphometry controlled the stratification and MeHg in the lake during the high-water. Floodplain lakes export hypolimnetic MeHg to their associated rivers during high-water.
Mesoclemmys raniceps is a medium-sized aquatic turtle widely distributed throughout the northern Amazon Basin in South America. Little information has been published about its reproductive biology. ...Because there is a significant problem identifying juveniles of this species found in the wild, and a controversy concerning the taxonomic status of the Mesoclemmys nasuta group, we incubated eggs from known females from known localities at controlled and ambient temperatures. We describe the hatchlings produced. The eggs hatched after an incubation period of 249 d at 28°C. Incubation experiments found both M. raniceps and Mesoclemmys heliostemma phenotypes hatching from the same clutch of eggs, suggesting that these taxa are conspecific. Mesoclemmys wermuthi had been incorrectly synonymized with M. nasuta and later absorbed by M. raniceps when M. raniceps was elevated to species status, resulting in the confusion of M. raniceps being different from M. heliostemma. Mesolemmys wermuthi is a distinct species separate from M. raniceps; however, M. wermuthi is preceded by Hydraspis maculata, which was synonymized with M. raniceps and is available for this species as Mesoclemmys maculata.
We describe a new species of small chelid turtle from perennial streams in the Araguaia River subbasin near Serra das Andorinhas State Park, São Geraldo do Araguaia, Pará, Brazil. It is ...morphologically distinct and the smallest known member of the genus Mesoclemmys, with an average straight-line carapace length (CL) of 144 mm and maximum recorded CL of 170 mm. The species has a moderate head width of approximately 20% of CL. The carapace and dorsal soft parts are blackish, the plastron is light brownish yellow with a blackish brown central plastral figure, and the ventral soft parts are pale yellow. It has the largest femoral scutes of any Mesoclemmys and its plastral contact formula is Intergular > Anal > Humeral > Femoral > Abdominal > Pectoral > Gular. We describe the shell and skull morphology of the new species and performed genetic analysis using mitochondrial DNA (cytochrome c oxidase, subunits I COI and 16S) to build a phylogenetic tree for the genus, which placed the new species as sister to M. vanderhaegei.
The matamatas (Chelus fimbriata and the recently described Chelus orinocensis) are the largest species in the family Chelidae, easily identified by their distinct morphological characteristics. The ...matamatas have a wide distribution in South America, occurring in Bolivia, Brazil, Colombia, Ecuador, Guyana, French Guiana, Peru, and Venezuela, as well as Trinidad and Tobago. However, there are many gaps in the knowledge of its distribution. The objective of this study was to present new records of occurrence for the C. fimbriata species complex and describe the area of distribution. We compiled data from published papers, databases in museums and other scientific collections, and research institutes and conservation organizations. From these data we mapped the species distribution, considering 3 types of river drainages based on water color in the Amazon Basin. We added 182 new records in Brazil, Venezuela, Colombia, Bolivia, and Peru, demonstrating that the C. fimbriata species complex has a wide distribution, totaling 6,907,551 km2 across all 3 river types. Most records were concentrated in areas lower than 200 m above sea level.
There is a long history of exploitation of the South American river turtle Podocnemis expansa. Conservation efforts for this species started in the 1960s but best practices were not established, and ...population trends and the number of nesting females protected remained unknown. In 2014 we formed a working group to discuss conservation strategies and to compile population data across the species’ range. We analysed the spatial pattern of its abundance in relation to human and natural factors using multiple regression analyses. We found that > 85 conservation programmes are protecting 147,000 nesting females, primarily in Brazil. The top six sites harbour > 100,000 females and should be prioritized for conservation action. Abundance declines with latitude and we found no evidence of human pressure on current turtle abundance patterns. It is presently not possible to estimate the global population trend because the species is not monitored continuously across the Amazon basin. The number of females is increasing at some localities and decreasing at others. However, the current size of the protected population is well below the historical population size estimated from past levels of human consumption, which demonstrates the need for concerted global conservation action. The data and management recommendations compiled here provide the basis for a regional monitoring programme among South American countries.
The extractable organic material (EOM) from atmospheric total suspended particles (TSP) contains several organic compounds including non-substituted polycyclic aromatic hydrocarbons (PAHs), ...alkyl-PAHs, and nitro-PAHs. These chemicals seem to be among the key drivers of TSP genotoxicity. We have shown previously that the mutagenic potencies of the EOM from Limeira, Stockholm, and Kyoto, cities with markedly different meteorological conditions and pollution sources are similar. Here we compare the profiles of non-substituted PAHs (27 congeners), alkyl-PAHs (15 congeners), and nitro-PAHs (7 congeners) from the same EOM samples from these cities. We also compared the genotoxicity profiles using comet and micronucleus assays in human bronchial epithelial cells. The profiles of PAHs, as well as the cytotoxic and genotoxic potencies when expressed in EOM, were quite similar among the studied cities. It seems that despite the differences in meteorological conditions and pollution sources of the cities, removal, mixing, and different atmospheric transformation processes may be contributing to the similarity of the PAHs composition and genotoxicity profiles. More studies are required to verify if this would be a general rule applicable to other cities. Although these profiles were similar for all three cities, the EOM concentration in the atmospheres is markedly different. Thus, the population of Limeira (∼10-fold more EOM/m
than Stockholm and ∼6-fold more than Kyoto) is exposed to higher concentrations of genotoxic pollutants, and Kyoto's population is 1.5-fold more exposed than Stockholm's. Therefore, to reduce the risk of human exposure to TSP genotoxins, the volume of emissions needs to be reduced.
Due to their natural history and ecological attributes, turtles are excellent organisms for studies of heavy metal contamination. Turtles have a large geographical distribution, occupy different ...aquatic habitats, and occupy various trophic levels. The present study investigated mercury bioaccumulation in the carnivorous chelonian
Chelus fimbriata
(Matamata turtle) and Hg biomagnification in relation to its aquatic food chain in the middle Rio Negro, AM-Brazil. Tissue samples of muscle, carapace and claws were collected from 26
C. fimbriata
individuals, as well as collections of autotrophic energy sources found in the turtle’s aquatic habitat area. The samples were collected in February-March/2014 and analyzed for THg concentrations and carbon (δ
13
C) and nitrogen (δ
15
N) stable isotopes. The highest THg levels were found in claws (3780 ng.g
−1
), carapace (3622 ng.g
−1
) and muscle (403 ng.g
−1
), which were found to be significantly different F(2.73) = 49.02
p
< 0.01. However, THg concentrations in muscle tissue were below the consumption threshold indicated by the WHO and Brazilian Health Ministry. The average δ
13
C and δ
15
N values in Matamata samples were −31.7‰ and 11.9‰, respectively. The principal energy source sustaining the food chain of
C. fimbriata
was found to be terrestrial shrubs, with smaller contributions from emergent aquatic herbaceous plants and algae, while δ
15
N values showed its trophic position to be two levels above the autotrophic energy sources. There was a positive correlation between THg and turtle size, while a significant relationship was found between THg and δ
15
N, showing strong biomagnification in the food chain of
C. fimbriata
: y = 0.21x + 0.46;
r
2
= 0.45;
p
< 0.001, for which the slope presented a value of 0.21.
Resins for 3D printing usually do not present suitable photoluminescence for application in optoelectronic devices. Herein, a conjugated polymer (PFeBSe) with luminescent and high refraction index ...properties was synthesized and used to modify an acrylate-based resin. This PFeBSe copolymer presents an ester-based side group that enhances the compatibility with the acrylate resin, resulting in a homogeneous polymeric blend. Further, the modified resin was employed with the 3D digital light processing (DLP) technique to produce luminescent guiding structures with a tailored refraction index. To maintain the processing parameters of the acrylate resin, the blending with the conjugated polymer was kept at a low concentration in the range of 5% to 15% (v/v). The blending changed the refraction index of the pristine acrylate from 1.49 to 1.51 (5% v/v) and 1.56 (15% v/v), respectively. Moreover, the resulting structures present a low extinction coefficient at the wavelength region above 600 nm. These characteristics enable the fabrication of structures with controllable forms and dimensions that can be used in the design of advanced sensors and optoelectronic devices.
The high complexity of the oral microbiota of healthy dogs and the close exposure of humans to companion animals represent a risk of the transmission of potential zoonotic microorganisms to humans, ...especially through dog bites, including multidrug-resistant ones. Nonetheless, a limited number of comprehensive studies have focused on the diversity of the microorganisms that inhabit the oral cavities of healthy dogs, particularly based on modern molecular techniques. We investigated bacterial and fungal organisms in the oral cavities of 100 healthy dogs based on a combination of conventional and selective microbiological culture, mass spectrometry (MALDI-TOF MS), and next-generation sequencing. In addition, in vitro antimicrobial susceptibility patterns of isolates and
A resistance gene were assessed. A total of 213 bacteria and 20 fungi were isolated.
(40/100 = 40%), α-hemolytic
(37/100 = 37%), and
(22/100 = 22%) were the most prevalent bacteria diagnosed by microbiological culture and MALDI-TOF MS, whereas
(10/100 = 10%) was the most common fungi identified. Based on next-generation sequencing of selected 20 sampled dogs,
(32.5%),
(16.3%),
(12.8%),
(9.5%),
(5%),
(3.8%), and
(3.4%) genera were prevalent. A high multidrug resistance rate was observed in
isolates, particularly to azithromycin (19/19 = 100%), penicillin (15/19 = 78.9%), and sulfamethoxazole/trimethoprim (15/19 = 78.9%). In addition, the
A resistance gene was detected in 6.1% (3/49) of coagulase-positive staphylococci. Here, we highlight the microbial complexity of the oral mucosa of healthy dogs, including potential zoonotic microorganisms and multidrug-resistant bacteria, contributing with the investigation of the microbiota and antimicrobial resistance patterns of the microorganisms that inhabit the oral cavity of healthy dogs.
To date, oil-rich plants are the main source of biodiesel products. Because concerns have been voiced about the impact of oil-crop cultivation on the price of food commodities, the interest in oil ...plants not used for food production and amenable to cultivation on non-agricultural land has soared. As a non-food, drought-resistant and oil-rich crop, Jatropha curcas L. fulfils many of the requirements for biofuel production.
We have generated 13,249 expressed sequence tags (ESTs) from developing and germinating Jatropha seeds. This strategy allowed us to detect most known genes related to lipid synthesis and degradation. We have also identified ESTs coding for proteins that may be involved in the toxicity of Jatropha seeds. Another unexpected finding is the high number of ESTs containing transposable element-related sequences in the developing seed library (800) when contrasted with those found in the germinating seed library (80).
The sequences generated in this work represent a considerable increase in the number of sequences deposited in public databases. These results can be used to produce genetically improved varieties of Jatropha with increased oil yields, different oil compositions and better agronomic characteristics.
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