Plastination—A scientific method for teaching and research

Over the last four decades, plastination has been one of the best processes of preservation for organic tissue. In this process, water and lipids in biological tissues are replaced by polymers (silicone, epoxy, polyester) which are hardened, resulting in dry, odourless and durable specimens. Nowadays, after more than 40 years of its development, plastination is applied in more than 400 departments of anatomy, pathology, forensic sciences and biology all over the world. The most known polymers used in plastination are silicone (S10), epoxy (E12) and polyester (P40). The key element in plastination is the impregnation stage, and therefore depending on the polymer that is used, the optical quality of specimens differs. The S10 silicone technique is the most common technique used in plastination. Specimens can be used, especially in teaching, as they are easy to handle and display a realistic topography. Plastinated silicone specimens are used for displaying whole bodies, or body parts for exhibition. Transparent tissue sections, with a thickness between 1 and 4 mm, are usually produced by using epoxy (E12) or polyester (P40) polymer. These sections can be used to study both macroscopic and microscopic structures. Compared with the usual methods of dissection or corrosion, plastinated slices have the advantage of not destroying or altering the spatial relationships of structures. Plastination can be used as a teaching and research tool. Besides the teaching and scientific sector, plastination becomes a common resource for exhibitions, as worldwide more and more exhibitions use plastinated specimens.     

The Coconut Water Antimicrobial Peptide CnAMP1 Is Taken up into Intestinal Cells but Does Not Alter P-Glycoprotein Expression and Activity

Plant Foods for Human Nutrition - Coconut antimicrobial peptide-1 (CnAMP1) is a naturally occurring bioactive peptide from green coconut water (Cocos nucifera L.). Although biological activities...     

Characterization of yam bean (Pachyrhizus erosus) proteins

Seed proteins from Mexican yam bean seeds (Pachyrhizus erosus L.) were sequentially extracted according to the Osborne classification. Albumins were the major fraction (52.1-31.0%), followed by globulins (30.7-27.5%). The minor protein fraction was prolamins (0.8%). Defatting with chloroform/methanol remarkably affected the distribution of protein solubility classes; albumins were the most affected fraction (4.3-17.5%). Electrophoretic patterns of albumins showed bands at 55, 40, 35, and 31 kDa. After reduction of the globulin fraction exhibited two triplets, one from 35 to 31 kDa and the second from 19 to 21 kDa, these could be compared to the acid and basic polypeptides of 11S-like proteins. Prolamins showed one band at 31 kDa, and glutelins after reduction showed three main bands at 52, 27, and 14 kDa. Trypsin inhibitors were assayed in saline extracts; the values found (1232-2608 IU/g of meal) were lower than those of other legumes. In general, yam bean seed proteins showed an excellent balance of all essential amino acids; albumins contain the highest amount of essential amino acids.     

A general model for designing networks of marine reserves

There is debate concerning the most effective conservation of marine biodiversity, especially regarding the appropriate location, size, and connectivity of marine reserves. We describe a means of establishing marine reserve networks by using optimization algorithms and multiple levels of information on biodiversity, ecological processes (spawning, recruitment, and larval connectivity), and socioeconomic factors in the Gulf of California. A network covering 40% of rocky reef habitat can fulfill many conservation goals while reducing social conflict. This quantitative approach provides a powerful tool for decision-makers tasked with siting marine reserves.     

Overexpression, purification, and in vitro refolding of the 11S globulin from amaranth seed in Escherichia coli

An amarantin 11S globulin cDNA encoding one of the most important storage proteins of amaranth seeds, with a high content of essential amino acids, was expressed in Escherichia coli. A good level of expression of recombinant amarantin with a molecular weight of 59 kDa was obtained. The recombinant protein was extracted by ammonium sulfate precipitation and purified to homogeneity using ion-exchange chromatography and reversed phase high-performance liquid chromatography. The expressed protein exhibited electrophoretic, immunochemical, and surface hydrophobicity properties similar to those of native amarantin from amaranth seed. Also, the recombinant protein was refolded in vitro using two different methods.     

In vitro starch digestibility and predicted glycemic index of corn tortilla, black beans, and tortilla-bean mixture: effect of cold storage

People in the rural areas of Mexico consume corn tortillas and beans as basic components of their diet. However, little is known about the nutritionally relevant features of starch present in such combined meals. The objective of the present study was to evaluate the in vitro bioavailability of starch in tortilla-bean mixtures stored at 4 degrees C for different times, as compared to that of corn tortilla and boiled black beans kept separately under the same conditions. Available starch (AS), resistant starch (RS), and retrograded resistant starch (RRS) contents were measured. The in vitro starch hydrolysis indices (HI) of freshly cooked and cold-stored samples were evaluated using a chewing/dialysis digestion protocol. HIs were used to predict glycemic indices (pGI) of the samples. AS in tortilla and beans decreased between 3 and 6% after 48-72 h, whereas values in the mixture fell by 3% after 48 h, with no further change by 72 h. Only minor rises in RS contents (1.5-1.6%) were recorded for tortilla and beans after 72 h of storage, and a lower increase (0.4%) was recorded in the mixture. Judging from RRS values, an important proportion of RS is due to starch retrogradation. The HI and pGI were higher in tortilla than in bean and the mixture. Hydrolysis rate values decreased in the stored samples, a pattern that corresponded with RS and RRS changes. The slow digestion features of common beans are largely retained by the legume-tortilla combination. Data support the perceived health beneficial properties of starch in this traditional cereal-legume food.     

Hydrolytic activity and ultrastructural changes in fruit skins from two prickly pear (Opuntia sp.) varieties during storage

The activity of four cell wall hydrolases, pectinmethylesterase (PME), polygalacturonase (PG), cellulase, and beta-galactosidase (beta-Gal), was measured in fruit skins of two prickly pear varieties, Naranjona and Charola, during storage at 18 degrees C and 85-95% relative humidity (RH). In Naranjona (Opuntia ficus indica), of short postharvest life (ca. 2 weeks), PG, cellulase, and beta-Gal increased their activity more than twice, whereas PME activity tended to increase only slightly during storage. In Charola (Opuntia sp.), of long postharvest life (ca. 2 months), only beta-Gal increased its activity (77%), showing a high PG activity from the beginning of storage. Transmission electron microscopy observations showed middle lamella dissolution at the end of storage for both varieties. Naranjona showed a higher cell wall enzymatic activity than Charola, in agreement with their storability differences. Our results suggest that PG and cellulase in Naranjona and PG and beta-Gal in Charola are the main enzymes responsible for cell wall hydrolytic and ultrastructural changes in skins of stored prickly pears.     

Urea treated maize straw for small-scale dairy systems in the highlands of Central Mexico

Maize straw is the main roughage for dairy herds in campesino farms in central Mexico. The objective was to evaluate feeding milking cows on maize straw treated with 40 g/kg DM of urea (A) or untreated straw (B), and 3.0 kg/d of 18% CP concentrate. Twenty-four Holsteins in late lactation from 8 farmers were sorted in two groups: sequence A-B-A or B-A-B; periods were 28 days. Mean daily milk yield for the last two weeks per period, and live-weight and body-condition score every 14 days were used for analysis. Maize straw was ad libitum. Chemical analysis and in vitro digestibility were analysed by Student’s t test, animal variables by a switch-back design. ‘A’ had 44.3 g/kg DM more CP and 106.5 g/kg DM higher in vitro digestibility than ‘B’ (710 g/kg DM ± 0.75 ‘A’ vs. 603.5 g/kg DM ± 1.44 ‘B’). Despite higher digestibility and intake, there were no differences (P > 0.05) for milk yield, live-weight or body-condition score, although there were in straw intake (P < 0.05). Cows on ‘A’ ate 1.7 kg/cow/day more straw DM than on ‘B’. Lack of response did not offset higher feeding costs although margins were high. Lack of response is attributed to short length of periods and late lactation of cows.     

Assessing the Oxidative Stress Induced by Paracetamol Spiked in Artificial Sediment on Hyalella azteca

Paracetamol is an antipyretic analgesic widely used globally. It has been recurrently found in water bodies and is known to elicit toxic effects in aquatic species; however, its potential ability to induce oxidative stress in sentinel species remains unknown The objective was to establish a methodology to evaluate the toxicity elicited on the sentinel species Hyalella azteca by paracetamol-enriched sediment using oxidative stress tests. Concentrations used in assays were determined using the previously obtained median lethal concentration (72?h LC₅₀). The following oxidative stress biomarkers were evaluated: lipid peroxidation (LPO), protein carbonyl content (PCC) in order to determine oxidized protein content, and the activity of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPX). LPO and PCC increased significantly while SOD, CAT, and GPX decreased significantly (p?<?0.05) with respect to controls. Paracetamol induces oxidative stress on H. azteca, and the set of tests employed is helpful in evaluating the toxicity of this group of pharmaceuticals on aquatic species.