Development of a dynamic model for estimating the food web transfer of chemicals in small aquatic ecosystems

A dynamic combined fate and food web model was developed to estimate the food web transfer of chemicals in small aquatic ecosystems (i.e. ponds). A novel feature of the modeling approach is that aquatic macrophytes (submerged aquatic vegetation) were included in the fate model and were also a food item in the food web model. The paper aims to investigate whether macrophytes are effective at mitigating chemical exposure and to compare the modeling approach developed here with previous modeling approaches recommended in the European Union (EU) guideline for risk assessment of pesticides. The model was used to estimate bioaccumulation of three hypothetical chemicals of varying hydrophobicity in a pond food web comprising 11 species. Three different macrophyte biomass densities were simulated in the model experiments to determine the influence of macrophytes on fate and bioaccumulation. Macrophytes were shown to have a significant effect on the fate and food web transfer of highly hydrophobic compounds with log K_OW > = 5. Modeled peak concentrations in biota were highest for the scenarios with the lowest macrophyte biomass density. The distribution and food web transfer of the hypothetical compound with the lowest hydrophobicity (log K_OW = 3) was not affected by the inclusion of aquatic macrophytes in the pond environment. For the three different hypothetical chemicals and at all macrophyte biomass densities, the maximum predicted concentrations in the top predator in the food web model were at least one order of magnitude lower than the values estimated using methods suggested in EU guidelines. The EU guideline thus provides a highly conservative estimate of risk. In our opinion, and subject to further model evaluation, a realistic assessment of dynamic food web transfer and risk can be obtained using the model presented here.     

Morphological tools to evaluate the digestory apparatus in rocky cavy (Kerodon rupestris)

This research describes for the first time the complete morphology of the digestive apparatus of rock cavies. Dissection, light microscopy, and scanning electron microscopy were performed. The oral cavity has: the hard palate without palatine wrinkles and the soft palate; the tongue composed by striated musculature, with presence of vallate, foliated, and fungiform papillae with taste buds and filiform papillae with mechanical function; and, 20 teeth of the hypsodonts type. Esophagus, stomach, small intestine (duodenum, jejunum, and ileum), and the large intestine (cecum, colon, and rectum) are found. The anus is present at the end of the alimentary channel. Organs of digestive tube are composed by four tunics: mucosa, submucosa, muscular, and serosa. The duodenum, jejunum and ileum have villi. Jejunum, ileum and cecum present Lieberkühn crypts. The cecum has mucous glands. Colon and rectum are folded and have goblet cells. Anus presents sebaceous glands. As associated glands it is found the liver with six lobes and gallbladder; a lobulated pancreas; and a pair of each major salivary gland (parotid, mandibular, and sublingual). Parotid glands have serous acini and mandibular and sublingual glands have mucous acini. Pancreas has adenomers. The liver has hepatocytes and portal vein, hepatic artery, and bile duct (portal triad), separated by sinusoids. It is concluded that the digestive apparatus of the rock cavy has variations in the dentition, lingual papillae, and acini of the salivary glands when compared to other rodents. Other variations refer to the well‐developed cecum characteristic of herbivorous behavior.     

Responses of clonal tea to location of production and plucking intervals

Tea is cultivated in diverse environments causing yield and quality differences in its beverages. To maximise yields and quality, agronomic practices should be optimised. But agronomic recommendations are uniform in different environments in Kenya despite variations in the growth factors responsible for changes in yields and quality. Plucking is labour intensive and a costly agronomic input in tea production. Trials were conducted for ten years in five tea growing regions in Kenya to assess yields and quality responses of clone BBK 35 tea to location of production and harvesting intervals. There were different (P ? 0.05) yields in the various locations, with significant (P ? 0.05) interaction effects between locations and harvesting intervals. Yields declined in three out of five regions but increased in one location with longer plucking intervals. Yields in a geographical area of production can not be used to estimate its expected yields in other tea growing areas. Black tea theaflavins varied significantly (P ? 0.05) with geographical area of production, but other plain tea quality parameters did not vary with location. It is therefore possible to make similar black teas with similar plain tea quality parameters except theaflavins from all tea growing regions of Kenya. Tea quality improved with short plucking rounds. One way to maximise tea quality is through shortening harvesting intervals. It is necessary to establish optimal harvesting rounds in the different tea growing regions in Kenya to maximise yields and quality.     

Effect of temperature on antioxidant capacity during drying process of mortiño (Vaccinium meridionale Swartz)

The mortiño fruit (Vaccinium meridionale Swartz) has been recognized as an excellent source of antioxidants, phenolic compounds, and anthocyanins. Drying conditions, particularly temperature, often lead to food quality degradation. The present study investigated the influence of drying temperature (40, 50, and 60°C) on antioxidant activity, anthocyanin, and phenol content of mortiño. Four different thin layer drying models of drying kinetics (Modified page, Newton, Henderson & Pabis and, two-terms) were fitted to the experimental data. For antioxidant capacity determination, oxygen radical absorbance capacity and ferric ion reducing antioxidant power assays were used. The results showed that antioxidant capacity, and phenolic and anthocyanin content all decreased with increasing temperature and drying time. It was observed that phenols and anthocyanins were conserved in greater amounts at 60°C with 34% (5.85 mg gallic acid/g dm) and 32% (2.36 mg Cyanidin-3-glucoside/g dm) preservation of initial content, respectively. Drying kinetics models were compared based on their R² and root mean square error values between the experimental and predicted moisture ratios. The two-terms model was found to satisfactorily describe the drying curves for all temperatures evaluated, with a determination coefficient (R²) above 0.9987 and root mean square error lower than 0.0201.     

Development of a transformation and selection system for the glycolipid-producing yeast Candida bombicola

Sophorolipids are surface-active compounds synthesized by the non-pathogenic yeast Candida bombicola. Over recent decades much effort has been spent to optimize culture conditions in order to improve the yield and production process. As far as we know, however, hardly any attention has been given to the genetics of the producing yeast strain itself and there are no published results available on the genetic engineering of C. bombicola. Nevertheless, this can be a useful tool for the study of the sophorolipid synthesis pathway and open up perspectives for improved production. A first step is the development of a suitable transformation and selection method. This article describes the creation and selection of an uracil auxotrophic C. bombicola mutant, which can be transformed back to prototrophy with the species' own orotidine 5'-phosphate decarboxylase or URA3 gene. Successful transformation was confirmed by a PCR-based method discriminating between the wild-type and mutated URA3 gene.     

A century of bacteriophage research and applications: impacts on biotechnology,health, ecology and the economy!

About a century ago, bacteriophages or phages – viruses that infect bacteria – were discovered and reported in the scientific literature. This review aims at a comprehensive survey of bacteriophage discovery, research and applications since the 1920s, and its impact on molecular biology, biotechnology, health, ecology and the economy. Phage therapy has been proven a valuable asset to deal with pathogenic bacterial infections since the early 1920s, and has been practiced ever since, especially in the former Soviet Union and in Eastern Europe. The Western world remained sceptical and resorted to the widespread use of antibiotics since the 1940s. Now that antibiotic resistance among pathogenic bacteria has spread alarmingly and few really novel antibiotic compounds are in the pipeline, renewed attention is being directed to the use of phages as antibacterial agents in medicine. Because of this renewed interest in phage therapy in the Western world, novel applications with phages are being pursued in the human health, environmental and the agri-food sectors. This review will focus on (1) the history of early phage use and its successes and problems, (2) the study of phages as important tools in the development of molecular biology and biotechnology, (3) current developments in phage research including the use of phage endolysins for use in antibacterial treatment, (4) phage production systems including undesirable phage contamination of industrial fermentation processes based on bacteria, (5) recent applications in phage therapy and in phage-based control, and (6) the roles of phages in nature and in the human gut. © 2018 Society of Chemical Industry     

Multifaceted Target Specificity Analysis as a Tool in Antimicrobial Drug Development: Type III Pantothenate Kinases as a Case Study

The research and development of a new antimicrobial drug using a target-based approach raises the question of whether any resulting hits will also show activity against the homologous target in other closely related organisms. While an assessment of the similarities of the predicted interactions between the identified inhibitor and the various targets is an obvious first step in answering this question, no clear and consistent framework has been proposed for how this should be done. Here we developed Multifaceted Target Specificity Analysis (MTSA) and applied it to type III pantothenate kinase (PanK_III) – an essential enzyme required for coenzyme A biosynthesis in a wide range of pathogenic bacteria – as a case study to establish if targeting a specific organism's PanK_III would lead to a narrow- or broad-spectrum agent. We propose that MTSA is a useful tool and aid for directing new target-based antimicrobial drug development initiatives.