Fabrication and Characterization of Native and Oxidized Potato Starch Biodegradable Films

The need to replace conventional polymers due to environmental pollution caused by them has led to increased production of biodegradable polymers such as starch. Thus, the application possibilities of starch have increased. In this study, we produced and characterized biodegradable films derived from native and oxidized potato starch. The film-forming solution was prepared with different concentrations of extracted starch (native or oxidized) and a plasticizer (glycerol or sorbitol). Then, the mechanical, barrier, morphological, and structural properties of the films were characterized. The moisture content of the films varied from 15.35?±?1.31 to 21.78?±?0.49%. The elastic modulus of the films ranged from 219?±?14.97 to 2299?±?62.91 MPa. The film of oxidized starch plasticized with sorbitol in the lowest content was the most resistant and flexible; moreover, this film also presented lower water vapor permeability and low solubility in water. Fourier-transform infrared spectroscopic analysis of the biodegradable films indicated the presence of same functional groups as those of starch with bands in the same regions. The film thickness was lower for the films plasticized with glycerol whereas the color variation (Δ?) was lower for the ones plasticized with sorbitol. In case of both plasticizers, the increase in their content decreased the Δ? value. All the biodegradable films presented stability against water absorption owing to their low solubility in water. Morphological evaluation revealed the presence of partially gelatinized starch granules in the films. The roughness parameter (Rq) of the films varied from 3.39 to 10.9 nm, indicating that their surfaces are smooth. X-ray diffraction studies showed a B-type pattern for the starches, which is representative of tubers. Further, the films present higher relative crystallinity (RC) compared to the starches. The biodegradable starch films are uniform, transparent and with low solubility in water. The oxidation of starch and use of sorbitol as a plasticizer resulted in improved properties of the starch films, which is suitable for application.     

Arsenic speciation in marine sediments: A comparison between two sequential extraction procedures

ABSTRACT

Arsenic distribution and mobility in marine sediments was investigated by means of total extraction and two sequential extraction procedures i.e. a modified sequential extraction procedure proposed by the European Standard, Measurementand Testing (SM&T) program, formerly the Community Bureau of Reference (BCR) procedure and a five steps sequential extraction based on the Wenzel extraction procedure, called modified Wenzel extraction. Sediments were collected from Cagliari’s harbour and Cagliari’s gulf, in Western Mediterranean Sea, Italy. The modified Wenzel extraction provided a more detailed As binding pattern and turned out to be much more appropriate than the modified SM&T procedure for gaining information regarding the mobilization of As within marine sediments. In the harbour, the largest part of As is contained in the residual fraction. At the contrary, As concentration, which is higher in the Cagliari’s gulf, is primarily associated with amorphous and crystalline hydrous Fe(Mn, Al) oxide. Moreover, this study suggests the possibility to segregate different types of marine sediments depending of human or industrial activities and to trace As contaminated marine sediments to determine the origin of contamination following the percentile of As contained in each extraction steps.     

The role of landscape change and paleoclimatic events in shaping the evolutionary history of the Polioptila gnatcatchers (Passeriformes,Polioptilidae) with emphasis on species associated with open habitats

We conducted a large‐scale phylogenetic and biogeographical inference of the Poliptila gnatcatchers and investigated the evolutionary history of two closely related neotropical bird species linked to open habitats, Polioptila dumicola and Polioptila plumbea. A Bayesian inference was employed based on the NADH subunit 2 gene to reconstruct the phylogenetic relationship of the gnatcatchers, and ancestral area reconstructions were estimated using BioGeoBEARS. For the phylogeographic analysis, we analyzed two mitochondrial genes, cytochrome b and ND2, of 102 individuals from P. dumicola and P. plumbea distributed throughout the complete range of both species. To reconstruct the dates related to the splitting events, we included a subset of sequences from the nuclear gene beta‐fibrinogen intron‐7. A striking result was the recovery of the sister relationship between the lineages of P. dumicola /plumbea and the paraphyly among the subspecies of P. plumbea: the first group was formed by P. dumicola, P. p. plumbea, P. p. parvirostris, P. p. atricapilla and P. lactea, occurring mainly on the Brazilian shield; while the second group consisted of lineages from north of the Amazon, west of the Andes, and Central America, and included P. maior, P. p. cinericia, P. p. bilineata and P. p. innotata. Significant phylogeographic structure was evident within lineages attributed to P. plumbea, with high levels of differentiation in the well‐defined clades according to all phylogenetic analyses. Our biogeographic analyses support distinct evolutionary histories related to founder events and vicariance, occurring during the late Pliocene and early Pleistocene. Several dispersal episodes between North/Central America and South America led to the establishment of populations which became differentiated due to landscape changes, such as the establishment of riverine barriers, the uplift of the Andes and the formation of the Panama Isthmus.     

Disentangling the effects of spring anomalies in climate and net primary production on body size of temperate songbirds

Body size is implicated in individual fitness and population dynamics. Mounting interest is being given to the effects of environmental change on body size, but the underlying mechanisms are poorly understood. We tested whether body size and body condition are related to ambient temperature (heat maintenance hypothesis), or/and explained by variations in primary production (food availability hypothesis) during the period of body growth in songbirds. We also explored whether annual population‐level variations of mean body size are due to changes of juvenile growth and/or size‐dependent mortality during the first year. For 41 species, from 257 sites across France, we tested for relationships between wing length (n = 107 193) or body condition (n = 82 022) and local anomalies in temperature, precipitation and net primary production (NDVI) during the breeding period, for juveniles and adults separately. Juvenile body size was best explained by primary production: wings were longer in years with locally high NDVI, but not shorter in years with low NDVI. Temperature showed a slightly positive effect. Body condition and adult wing length did not covary with any of the other tested variables. We found no evidence of climate‐driven size‐dependent mortality for the breeding season. In our temperate system, local climatic anomalies explained little of the body size variation. A large part of wing length variance was site‐specific, suggesting that avian size was more dependent on local drivers than global ones. Net primary production influenced juvenile size the most through effects on body growth. We suggest that, during the breeding season in temperate systems, thermoregulatory mechanisms are less involved in juvenile growth than food assimilation.     

Genome sequence of M6, a diploid inbred clone of the high‐glycoalkaloid‐producing tuber‐bearing potato species Solanum chacoense,reveals residual heterozygosity

Cultivated potato (Solanum tuberosum L.) is a highly heterozygous autotetraploid that presents challenges in genome analyses and breeding. Wild potato species serve as a resource for the introgression of important agronomic traits into cultivated potato. One key species is Solanum chacoense and the diploid, inbred clone M6, which is self‐compatible and has desirable tuber market quality and disease resistance traits. Sequencing and assembly of the genome of the M6 clone of S. chacoense generated an assembly of 825 767 562 bp in 8260 scaffolds with an N50 scaffold size of 713 602 bp. Pseudomolecule construction anchored 508 Mb of the genome assembly into 12 chromosomes. Genome annotation yielded 49 124 high‐confidence gene models representing 37 740 genes. Comparative analyses of the M6 genome with six other Solanaceae species revealed a core set of 158 367 Solanaceae genes and 1897 genes unique to three potato species. Analysis of single nucleotide polymorphisms across the M6 genome revealed enhanced residual heterozygosity on chromosomes 4, 8 and 9 relative to the other chromosomes. Access to the M6 genome provides a resource for identification of key genes for important agronomic traits and aids in genome‐enabled development of inbred diploid potatoes with the potential to accelerate potato breeding.     

Synthesis and biological evaluation of novel mono- and bivalent ASGP-R-targeted drug-conjugates

Asialoglycoprotein receptor (ASGP-R) is a promising biological target for drug delivery into hepatoma cells. Nevertheless, there are only few examples of small-molecule conjugates of ASGP-R selective ligand equipped by a therapeutic agent for the treatment of hepatocellular carcinoma (HCC). In the present work, we describe a convenient and versatile synthetic approach to novel mono- and multivalent drug-conjugates containing N-acetyl-2-deoxy-2-aminogalactopyranose and anticancer drug – paclitaxel (PTX). Several molecules have demonstrated high affinity towards ASGP-R and good stability under physiological conditions, significant in vitro anticancer activity comparable to PTX, as well as good internalization via ASGP-R-mediated endocytosis. Therefore, the conjugates with the highest potency can be regarded as a promising therapeutic option against HCC.     

C. elegans Eats Its Own Intestine to Make Yolk Leading to Multiple Senescent Pathologies

1. Download high-res image (211KB)
2. Download full-size image