Disproportionate Contribution of Riparian Inputs to Organic Carbon Pools in Freshwater Systems

A lack of appropriate proxies has traditionally hampered our ability to distinguish riverine organic carbon (OC) sources at the landscape scale. However, the dissection of C₄ grasslands by C₃-enriched riparian vegetation, and the distinct carbon stable isotope signature (δ¹³C) of these two photosynthetic pathways, provides a unique setting to assess the relative contribution of riparian and more distant sources to riverine C pools. Here, we compared δ¹³C signatures of bulk sub-basin vegetation (δ¹³C_VEG) with those of riverine OC pools for a wide range of sites within two contrasting river basins in Madagascar. Although C₃-derived carbon dominated in the eastern Rianala catchment, consistent with the dominant vegetation, we found that in the C₄-dominated Betsiboka basin, riverine OC is disproportionately sourced from the C₃-enriched riparian fringe, irrespective of climatic season, even though δ¹³C_VEG estimates suggest as much as 96% of vegetation cover in some Betsiboka sub-basins may be accounted for by C₄ biomass. For example, δ¹³C values for river bed OC were on average 6.9 ± 2.7‰ depleted in ¹³C compared to paired estimates of δ¹³C_VEG. The disconnection of the wider C₄-dominated basin is considered the primary driver of the under-representation of C₄-derived C within riverine OC pools in the Betsiboka basin, although combustion of grassland biomass by fire is likely a subsidiary constraint on the quantity of terrestrial organic matter available for export to these streams and rivers. Our findings carry implications for the use of sedimentary δ¹³C signatures as proxies for past forest-grassland distribution and climate, as the C₄ component may be considerably underestimated due to its disconnection from riverine OC pools.     

Assessing antixenosis of soybean entries against Piezodorus guildinii (Hemiptera: Pentatomidae)

Piezodorus guildinii (Westwood) (Hemiptera: Pentatomidae) is a major soybean (Glycine max (L.) Merrill) pest and reduces grain quality and yield worldwide. In the context of integrated pest management strategies, plant resistance stands out as an extremely valuable tool for the management of pest populations. Here, we evaluated the resistance of several soybean entries to P. guildinii using tests of attractiveness and feeding preference. We also evaluated trichome number and length as well as pod hardness to evaluate the relationships between these parameters and the resistance to stink bug. D 75-10169, PI 171451, PI 229358, PI 227687, “IAC 100,” IAC 78-2318, PI 274454, PI 274453 and “IAC 19” were less attractive and less consumed by stink bugs. D 75-10169, PI 227687 and PI 274454 received low probe numbers and a short consumption duration per probe; “IAC 100” and PI 274453 received low probe numbers; PI 171451 and PI 229358 received short probe durations; and “IAC 19” received the highest number of probes. There was no correlation between trichome density and length with the attractiveness and feeding preference of the adult insects; however, pod hardness results suggested that this morphological factor may influence the number of probes performed by the insect. PI’s entries, D 75-10169, “IAC 100” and “IAC 19” expressed antixenosis resistance and should be appropriate for use in soybean breeding programs aimed at developing entries with higher resistance to pest insects.     

Intestinal Translocation of Clinical Isolates of Vancomycin-Resistant Enterococcus faecalis and ESBL-Producing Escherichia coli in a Rat Model of Bacterial Colonization and Liver Ischemia/Reperfusion Injury

The objectives of this study were to develop a rat model of gastrointestinal colonization with vancomycin-resistant Enterococcus faecalis (VRE) and extended-spectrum beta-lactamase (ESBL)-producing E. coli and to evaluate intestinal translocation to blood and tissues after total and partial hepatic ischemia. Methods - We developed a model of rat colonization with VRE and ESBL-E coli. Then we studied four groups of colonized rats: Group I (with hepatic pedicle occlusion causing complete liver ischemia and intestinal stasis); Group II (with partial liver ischemia without intestinal stasis); Group III (surgical manipulation without hepatic ischemia or intestinal stasis); Group IV (anesthetized without surgical manipulation). After sacrifice, portal and systemic blood, large intestine, small intestine, spleen, liver, lungs, and cervical and mesenteric lymph nodes were cultured. Endotoxin concentrations in portal and systemic blood were determined. Results – The best inocula were: VRE: 2.4×10¹⁰ cfu and ESBL-E. coli: 1.12×10¹⁰ cfu. The best results occurred 24 hours after inoculation and antibiotic doses of 750 µg/mL of water for vancomycin and 2.1 mg/mL for ceftriaxone. There was a significantly higher proportion of positive cultures for ESBL-E. coli in the lungs in Groups I, II and III when compared with Group IV (67%; 60%; 75% and 13%, respectively; p:0.04). VRE growth was more frequent in mesenteric lymph nodes for Groups I (67%) and III (38%) than for Groups II (13%) and IV (none) (p:0.002). LPS was significantly higher in systemic blood of Group I (9.761±13.804 EU/mL−p:0.01). No differences for endotoxin occurred in portal blood. Conclusion –We developed a model of rats colonized with resistant bacteria useful to study intestinal translocation. Translocation occurred in surgical procedures with and without hepatic ischemia-reperfusion and probably occurred via the bloodstream. Translocation was probably lymphatic in the ischemia-reperfusion groups. Systemic blood endotoxin levels were higher in the group with complete hepatic ischemia.     

White Matter Tract Damage in the Behavioral Variant of Frontotemporal and Corticobasal Dementia Syndromes

The phenotypes of the behavioral variant of frontotemporal dementia and the corticobasal syndrome present considerable clinical and anatomical overlap. The respective patterns of white matter damage in these syndromes have not been directly contrasted. Beyond cortical involvement, damage to white matter pathways may critically contribute to both common and specific symptoms in both conditions. Here we assessed patients with the behavioral variant of frontotemporal dementia and corticobasal syndrome with whole-brain diffusion tensor imaging to identify the white matter networks underlying these pathologies. Twenty patients with the behavioral variant of frontotemporal dementia, 19 with corticobasal syndrome, and 15 healthy controls were enrolled in the study. Differences in tract integrity between (i) patients and controls, and (ii) patients with the corticobasal syndrome and the behavioral variant of frontotemporal dementia were assessed with whole brain tract-based spatial statistics and analyses of regions of interest. Behavioral variant of frontotemporal dementia and the corticobasal syndrome shared a pattern of bilaterally decreased white matter integrity in the anterior commissure, genu and body of the corpus callosum, corona radiata and in the long intrahemispheric association pathways. Patients with the behavioral variant of frontotemporal dementia showed greater damage to the uncinate fasciculus, genu of corpus callosum and forceps minor. In contrast, corticobasal syndrome patients had greater damage to the midbody of the corpus callosum and perirolandic corona radiata. Whereas several compact white matter pathways were damaged in both the behavioral variant of frontotemporal dementia and corticobasal syndrome, the distribution and degree of white matter damage differed between them. These findings concur with the distinctive clinical manifestations of these conditions and may improve the in vivo neuroanatomical and diagnostic characterization of these disorders.     

In vitro organogenesis from root culture segments of Bixa orellana L. (Bixaceae)

The organogenic potential of root explants derived from cultured seedlings of Bixa orellana L. (annatto) was investigated in response to different incubation conditions and either 4.44 μM 6-benzyladenine, 4.54 μM Thidiazuron, or 4.56 μM Zeatin. Explants cultured in liquid media with agitation generally showed better development of adventitious buds versus explants cultured on semi-solid media. The most adventitious buds developed from explants cultured in liquid media under a 16-h photoperiod. Use of Zeatin and Thidiazuron promoted the development of more adventitious buds than 6-benzyladenine but morphological abnormalities among regenerating shoots and plants were observed. Fewer adventitious buds developed from explants cultured in liquid media supplemented with 6-benzyladenine, but the buds gave rise to the highest percentage of morphologically normal regenerated plants. Histological analyses showed that adventitious buds originated from cell proliferation within the pericycle, opposite the protoxylem poles of the explant. Seedling root tissue is useful for in vitro propagation of B. orellana.     

In vitro conservation of Mandevilla moricandiana (Apocynaceae): short-term storage and encapsulation–dehydration of nodal segments

In vitro conservation of Mandevilla moricandiana was performed by slow-growth storage and encapsulation–dehydration. For slow-growth storage, half- and full-strength Murashige and Skoog (MS) medium and Woody Plant Medium, with or without sorbitol, mannitol, or glucose, were used to test the development of nodal segments and maintenance of plant viability after 6 mo. Recovery was performed using MS medium. The basal medium and carbon source did not interact, and only the carbon source had a significant effect on slow-growth storage and recovery. Sorbitol and glucose, individually or in combination, promoted development of plants with a low multiplication rate during the slow-growth period and a high multiplication rate during the recovery period. For encapsulation–dehydration, nonencapsulated and sodium alginate-encapsulated nodal segments were evaluated to determine their viability after storage at different temperatures. Nonencapsulated nodal segments gave 16.6% recovery after 60 d at 25°C. The effects of preculturing encapsulated nodal segments in MS medium with 0.4 or 0.75 M sucrose followed by dehydration were also tested. Capsules precultured for 48 h in the presence of 0.40 M sucrose and dehydrated to 40% moisture content showed 93.3% recovery. These conditions were then used to store capsules under different temperatures and for different lengths of time. The precultured capsules showed ca. 30% recovery after storage for 30 d at 4°C. Well-developed plantlets regenerated from encapsulated, stored nodal segments were rooted and acclimatized successfully, with 100% survival.     

The influence of pH on Staphylococcus saprophyticus iron metabolism and the production of siderophores

Staphylococcus saprophyticus is a gram-positive coagulase negative bacteria which shows clinical importance due to its capability of causing urinary tract infections (UTI), as well as its ability to persist in this environment. Little is known about how S. saprophyticus adapts to the pH shift that occurs during infection. Thus, in this study we aim to use a proteomic approach to analyze the metabolic adaptations which occur as a response by S. saprophyticus when exposed to acid (5.5) and alkaline (9.0) pH environments. Proteins related to iron storage are overexpressed in acid pH, whilst iron acquisition proteins are overexpressed in alkaline pH. It likely occurs because iron is soluble at acid pH and insoluble at alkaline pH. To evaluate if S. saprophyticus synthesizes siderophores, CAS assays were performed, and the results confirmed their production. The chemical characterization of siderophores demonstrates that S. saprophyticus produces carboxylates derived from citrate. Of special note is the fact that citrate synthase (CS) is down-regulated during incubation at acid pH, corroborating this result. This data was also confirmed by enzymatic assay. Our results demonstrate that iron metabolism regulation is influenced by different pH levels, and show, for the first time, the production of siderophores by S. saprophyticus. Enzymatic assays suggest that citrate from the tricarboxylic acid cycle (TCA) is used as substrate for siderophore production.     

An efficient Agrobacterium tumefaciens-mediated transformation method for Simplicillium subtropicum (Hypocreales: Cordycipitaceae)

Filamentous fungi are the organisms of choice for most industrial biotechnology. Some species can produce a variety of secondary metabolites and enzymes of commercial interest, and the production of valuable molecules has been enhanced through different molecular tools. Methods for genetic manipulation and transformation have been essential for the optimization of these organisms. The genus Simplicillium has attracted increased attention given several potential biotechnological applications. The Simplicillium genus harbors several entomopathogenic species and some isolates have been explored for bioremediation of heavy metal contaminants. Furthermore, the myriad of secondary metabolites isolated from Simplicillium spp. render these organisms as ideal targets for deep exploration and further biotechnological mining possibilities. However, the lack of molecular tools hampered the exploration of this genus. Thus, an Agrobacterium tumefaciens-mediated transformation method was established for Simplicillium subtropicum, employing the far-red fluorescent protein TURBOFP635/Katushka, as a visual marker, and the selection marker SUR gene, that confers resistance to chlorimuron ethyl. Notably, one round of transformation using the established method yielded almost 400 chlorimuron resistant isolates. Furthermore, these transformants displayed mitotic stability for, at least, five generations. We anticipate that this method can be useful for deep molecular exploration and improvement of strains in the Simplicillium genus.     

Scrape cell-block technique for fine needle aspiration cytology smears

An inconclusive diagnosis on fine needle aspiration cytology (FNAC) may be due to poor spreading and presence of thick tissue fragments despite aspiration of adequate material. Repeat aspiration may not be possible especially when aspirates of deep seated organs have been obtained by image guided techniques. We have resorted to a 'scrape cell-block' (SCB) technique in such cases. In this technique the cellular material on the slides which had already been fixed and stained, was carefully removed by scraping following destaining and then processed as a cell block. SCB interpretation was then compared with the smear diagnosis and histological diagnosis, wherever available. A total of 27 cases were studied. In 12 cases SCB slides added information to the FNAC smears. In 14 cases SCB did not offer any additional information. SCB was inconclusive in one case. Final histological correlation was available in eight cases and the SCB diagnosis was confirmed in six cases, whereas in two cases SCB failed to identify the tumour. Immunocytochemistry (ICC) was done in one case. SCB is a useful technique to make the best use of the available material when reaspiration is difficult.     

Bird species of black water inundation forests in the Jaú National Park (Amazonas state, Brazil): their contribution to regional species richness

We compared the relative contribution of blackwater inundation forest (igapó) and unflooded (terra firme) forest for regional bird species diversity in the lower Rio Negro region. For analyses of habitat preference we used mist-net samples and an unpublished bird species check-list. The igapó forest had lower bird species diversity than the terra firme forest. However, some 14% of the forest bird species in the region are restricted to igapó forest. Species composition was found to be distinct between the understories of the two forest types. Common forest bird guilds in the Neotropics such as ant-following birds avoid igapó forest. The differential habitat selection among birds in the inundated and unflooded forest is likely to result from vegetation structure and biological interactions such as aggressive behaviour. Since the inundated forest has a typical biota, conservation efforts needs to be directed to protect these habitats. Unfortunately, inundation forests are threatened by several human actions, especially dam construction. The extent of protected areas in the Brazilian Amazon is insufficient for the adequate protection of the inundated habitats, because it includes only 3% of the total area.