Properties of the amniotic membrane for potential use in tissue engineering

An important component of tissue engineering (TE) is the supporting matrix upon which cells and tissues grow, also known as the scaffold. Scaffolds must easily integrate with host tissue and provide an excellent environment for cell growth and differentiation. Most scaffold materials are naturally derived from mammalian tissues. The amniotic membrane (AM) is considered an important potential source for scaffolding material. The AM represents the innermost layer of the placenta and is composed of a single epithelial layer, a thick basement membrane and an avascular stroma. The special structure and biological viability of the AM allows it to be an ideal candidate for creating scaffolds used in TE. Epithelial cells derived from the AM have the advantages of stem cells, yet are a more suitable source of cells for TE than stem cells. The extracellular matrix components of the basement membrane of the AM create an almost native scaffold for cell seeding in TE. In addition, the AM has other biological properties important for TE, including anti-inflammatory, anti-microbial, anti-fibrosis, anti-scarring, as well as reasonable mechanical property and low immunogenicity. In this review, the various properties of the AM are discussed in light of their potential use for TE

Influence of olfaction in host-selection behavior of the cassava whitefly Bemisia tabaci

Open Access Journal; Published online: 18 Nov 2021Cassava is a vital food-security crop in Sub-Saharan Africa. Cassava crops are, however, severely affected by viral diseases transmitted by members of the whitefly species complex Bemisia tabaci. We have here investigated the role of olfaction in host selection behavior of the cassava whitefly B. tabaci SSA-ESA biotype. Surprisingly, we find that the whiteflies appear to make little use of olfaction to find their favored host. The cassava whitely shows a highly reduced olfactory system, both at the morphological and molecular level. Whitefly antennae possess only 15 sensilla with possible olfactory function, and from the genome we identified just a handful of candidate chemoreceptors, including nine tuning odorant receptors, which would afford the whitefly with one of the smallest olfactomes identified from any insect to date. Behavioral experiments with host and non-host plants, as well as with identified specific volatiles from these sources, suggest that the few input channels present are primarily tuned toward the identification of unwanted features, rather than favored ones, a strategy quite unlike most other insects. The demonstrated repellence effect of specific volatile chemicals produced by certain plants unflavored by whiteflies suggests that intercropping with these plants could be a viable strategy to reduce whitefly infestations in cassava fields

Induced in Vitro Differentiation of β-Tubulin III Expressed Cells from Human Amniotic Epithelial Cells

AbstractBackground and Objectives: The differentiation of neural cells from embryonic stem cells is influenced by several factors. Amniotic epithelial cells (AECs) share many of the same characteristics as embryonic stem cells, and therefore, those factors may similarly affect the derivation of neural cells from AECs. In this study, we examined the differentiation of neural cells in vitro from AECs using the expression of β-tubulin III marker, after AECs treatment with retinoic acid (RA), and the impact of basic fibroblast growth factor (bFGF). We also studied whether blocking bone morphogenetic protein (BMP) signaling the use of its antagonist, noggin, affects the derivation of neural cells from AECs.Methods: AECs were isolated from fresh human amniotic membrane and aggregated for 5 days in bacteriological dishes. The dissociated cells were transferred to adherent culture dishes and treated with noggin and bFGF for 7 days. In some cultures, bFGF was removed and RA was added and the cultures were allowed to differentiate for 21 days. Analysis of AECs derived neural cells was performed at the β-tubulin III expression levels by immunocitochemistry.Results: All cultures treated with noggin showed the higher levels of β-tubulin III expression than noggin free cultures. Combined treatment with bFGF and RA showed the highest level of β-tubulin III in all treatment groups with or without noggin. bFGF withdrawal did not promote expression of β-tubulin III, while its maintenance increased the expression of β-tubulin III.Conclusions: These results show the capability of AECs to express neural cell marker and this potential is affected by some factors including noggin, bFGF, RA.Keywords: Amnionc Epithelial Cells; Noggin Protein; bFGF; Tretinoin; β-tubulin III

Phylogeography and Population Genetic Analyses in the Iberian Toothcarp (Aphanius iberus Valenciennes, 1846) at Different Time Scales

Secondary freshwater fish species inhabiting fluctuating and extreme environments are susceptible to changes in dispersion, effective population size, and genetic structure. The Iberian toothcarp Aphanius iberus is an endemic cyprinodontid of the Iberian Peninsula restricted to brackish water of salt marshes and coastal lagoons on the eastern Spanish Mediterranean coast. In this study, we analyzed mitochondrial cytochrome b (cyt b) DNA and microsatellite variation to evaluate ways in which the processes of extinction, dispersal, and colonization of A. iberus across its geographic distribution have affected its population genetic structure over time and space. The A. iberus network reconstruction indicated subtle levels of phylogeographic structuring.This, combined with substantial mitochondrial DNA (mtDNA) genetic diversity, suggests that Pleistocene glaciations had a lesser effect on the demographic structure of its populations than was the case for Iberian freshwater species with a similar distribution. Haplotype network, hierarchical analysis of molecular variance, and pairwise ΦST comparisons involving some Levantine samples showed a relatively high degree of mtDNA differentiation, which could be explained by historical isolation of the Villena Lagoon population. Conversely, significant genetic differentiation that follows an isolation-by-distance pattern, and a reduction in Ne though time was detected with microsatellites, suggesting extensive habitat fragmentation on the Mediterranean coast of the Iberian Peninsula over the past hundreds of years. At a smaller geographical scale (Mar Menor Lagoon), habitat fragmentation, probably due to human activity, appears to have resulted in substantially reduced migration and increased genetic drift, as shown by expanded genetic differentiation of populations.Subject areas: Population structure and phylogeography, Conservatio

A double-edged sword : Unrecognized cryptic diversity and taxonomic impediment in Eois (Lepidoptera, Geometridae)

The genus Eois Hübner (Geometridae: Larentiinae) comprises 254 valid species. Being a hyperdiverse genus, Eois potentially includes many undescribed cryptic species and embodies a problematic taxonomic scenario. The actual diversity of Eois is greatly underestimated and the Neotropical fauna needs to be well known since it figures as one of the most threatened terrestrial ecosystem. In the present study, we compare three species delimitation methods to highlight the hidden diversity within a subset of Eois species: Automatic Barcode Gap Discovery, Bayesian Poisson Tree Processes and Multi-Rate Poisson Tree Processes. Our results point to an increase up to 176% in the currently valid species number. The hypothesis of cryptic diversity is corroborated by morphological characters within some species complexes. For complexes comprising species of Brazilian fauna, we provide a preliminary taxonomic assessment. Additionally, we found no congruence among the three delimitation methods for some species complexes, which indicates the importance of species and locality sampling as well as the previous alpha taxonomic knowledge in avoiding result bias. In this sense, we tried to standardize the identification provided for the Genbank sequences used in most relevant publications for Eois, in order to minimize biases and maximize the replicability of analyses in future studies. Moreover, we stress the importance of an integrative taxonomic approach for cryptic species discovery approach by employing both morphological attributes and life history to corroborate molecular analysis

Potential applications of the chondrocyte micropellets.

<p>The direct use of chondrocyte micropellets in articular cartilage defect repair (A). The use of cartilage micropellets in the manufacture of osteochondral tissues <i>in vitro</i> (B).</p

Metabolic activity, growth and sGAG production in pellets.

<p>AlamarBlue® graph for metabolic activity (A), DNA quantification (B), sGAG in construct (C) and sGAG in media (D) measurements on days 4, 7, 11, 14. The sGAG/DNA ratio (calculated by dividing the total amount of sGAG produced during the culture to the amount of DNA measured on day 14) (E) and the total sGAG graph demonstrating the total sGAG in media and in construct separately (F).</p

Hypoxic micropellets assembled into macrotissues.

<p>Alcian blue staining for hypoxic micropellets assembled at different time points (indicated days). The total culture duration was 21 days. Scale bars: 100 µm.</p

Cell and matrix localization throughout pellets following 14 days of culture.

<p>DAPI staining of nuclei in pellets (A).Immunofluorescence images for collagen I (B), collagen X (C), and collagen II (D), Alcian blue staining for sGAG (E). Scale bars: 100 µm.</p