Interdependence between lignocellulosic biomasses,enzymatic hydrolysis and yeast cell factories in biorefineries

Biorefineries have a pivotal role in the bioeconomy scenario for the transition from fossil-based processes towards more sustainable ones relying on renewable resources. Lignocellulose is a prominent feedstock since its abundance and relatively low cost. Microorganisms are often protagonists of biorefineries, as they contribute both to the enzymatic degradation of lignocellulose complex polymers and to the fermentative conversion of the hydrolyzed biomasses into fine and bulk chemicals. Enzymes have therefore become crucial for the development of sustainable biorefineries, being able to provide nutrients to cells from lignocellulose. Enzymatic hydrolysis can be performed by a portfolio of natural enzymes that degrade lignocellulose, often combined into cocktails. As enzymes can be deployed in different operative settings, such as separate hydrolysis and fermentation (SHF) or simultaneous saccharification and fermentation (SSF), their characteristics need to be combined with microbial ones to maximize the process. We therefore reviewed how the optimization of lignocellulose enzymatic hydrolysis can ameliorate bioethanol production when Saccharomyces cerevisiae is used as cell factory. Expanding beyond biofuels, enzymatic cocktail optimization can also be pivotal to unlock the potential of non-Saccharomyces yeasts, which, thanks to broader substrate utilization, inhibitor resistance and peculiar metabolism, can widen the array of feedstocks and products of biorefineries.     

The effects of testosterone implants on ovarian morphology in the bluehead wrasse, Thalassoma bifasciatum (Bloch) (Teleostei: Labridae)

The effects of exogenous testosterone pellet implants at 21 and 40 days on the ovary of Thalassoma bifasciatum , a protogynous marine fish, are described. The characteristic markings of the terminal blue phase appeared by 4 to 5 days and were complete by 18 days. There was no shift in sex ratio in the treated fish when compared to an untreated control group. None of the ovaries showed signs of precocious transformation, i.e., spermatogenic tissue was lacking, and there was no evidence of duct formation. Instead, however, the ovaries of the treated fish showed marked degenerative changes characterized by oocyte breakdown, fat infiltration, vacuolization, the accumulation of fibrous PAS+ material and the appearance of small eosinophilic cells.
These findings conflict with earlier studies on the same organism that employed different procedures. However, they resemble more closely the results obtained from work on another protogynoid, the ricefield eel, Monopterus albus. They add new light on the role of sex hormones in the reversal process of T. bifasciatum and hermaphroditic fishes in general.     

Morphology and Germination of Yellow and Brown Caryopses of Aegilops Geniculata Roth (Gramineae) Population from Italy

Abstract

The germination percentage of Aegilops geniculata Roth caryopses was studied on four Italian populations (Pisa, Manfredonia, Catania and Simbirizzi). Observation of the germination trend was carried out at constant temperatures of 10°, 20° and 30°C, from maturation up to 60 days after harvesting. Spike, spikelet and caryopsis phenotypic characteristics were also studied. The populations of Pisa, Manfredonia and Simbirizzi presented two different types of caryopses: yellow caryopses - larger, heavier and composing roughly 60% of total—and brown caryopses—smaller and lighter in weight. The Catania population formed an exception in that brown caryopses were virtually absent (5%). This Sicilian accession also showed the largest spikelet size.

Yellow caryopses germinated more rapidly than the dark ones, which were shown to be endowed with longer relative dormancy, above all at 10° and 30° C. Such a phenomenon allows the two types of caryopses to have a different germination ecology, thus providing A. geniculata with a broader choice of germination opportunities and consequently favouring spread and survival of the species.     

Immunolocalisation of vasoactive intestinal peptide and substance P in the developing gut of Dicentrarchus labrax (L.)

This study was carried out on the sea bass (Dicentrarchus labrax) to follow, during development, the appearance and distribution of substance P (SP) and vasoactive intestinal peptide (VIP), which act on gut motility. The results suggest that SP and VIP play an important role as neuromodulators, influencing the motility of the digestive tract starting from the early stages of gut development, even prior to exotrophic feeding. In the peptidergic nervous system, the appearance of immunoreactivity to SP began at the rectum and followed a distal to proximal gradient, whereas for VIP, it began proximally and progressed along a proximal to distal gradient. The two peptides also appeared in gut epithelial cells. In some regions, all the cells were positive. From this distribution of positive cells, we conclude that these peptides may also have other roles, besides being neurotransmitters in the enteric nervous system and hormones of the gastro-entero-pancreatic system. VIP and SP might have paracrine and/or autocrine activity in the physiological maturation of the gut epithelium, as it has already been hypothesised for other peptides.     

The double inhibition of endogenously produced BMP and Wnt factors synergistically triggers dorsal telencephalic differentiation of mouse ES cells

Embryonic stem (ES) cells are becoming a popular model of in vitro neurogenesis, as they display intrinsic capability to generate neural progenitors that undergo the known steps of in vivo neural development. These include the acquisition of distinct regional fates, which depend on growth factors and signals that are present in the culture medium. The control of the intracellular signaling that is active at different steps of ES cell neuralization, even when cells are cultured in chemically defined medium, is complicated by the endogenous production of growth factors. However, this endogenous production has been poorly investigated so far. To address this point, we performed a high‐throughput analysis of the expression of morphogens during mouse ES cell neuralization in minimal medium. We found that during their neuralization, ES cells increased the expression of members of Wnt, Fibroblast Growth Factor (FGF), and BMP families. Conversely, the expression of Activin/Nodal and Shh ligands was low in early steps of neuralization. In this experimental condition, neural progenitors and neurons generated by ES cells expressed a gene expression profile that was consistent with a midbrain identity. We found that endogenous BMP and Wnt signaling, but not FGF signaling, synergistically affected ES cell neural patterning, by turning off a profile of dorsal/telencephalic gene expression. Double BMP and Wnt inhibition allowed neuralized ES cells to sequentially activate key genes of cortical differentiation. Our findings are consistent with a novel synergistic effect of Wnt and BMP endogenous signaling of ES cells in inhibiting a cortical differentiation program. © 2014 Wiley Periodicals, Inc. Develop Neurobiol 75: 66–79, 2015     

Bomb-pulse 14C analysis combined with 13C and 15N measurements in blood serum from residents of Malmö, Sweden

The ¹⁴C content of 60 human blood serum samples from residents of Malmö (Sweden) in 1978, obtained from a biobank, has been measured to estimate the accuracy of ¹⁴C bomb-pulse dating. The difference between the date estimated using the Calibomb software and sampling date varied between ?3 ± 0.4 and +0.2 ± 0.5 years. The average age deviation of all samples was ?1.5 ± 0.7 years, with the delay between production and consumption of foodstuffs being probably the dominating cause. The potential influence of food habits on the ¹⁴C date has been evaluated using stable isotope δ¹³C and δ¹⁵N analysis and information about the dietary habits of the investigated individuals. Although the group consisting of lacto-ovo vegetarians and vegans (pooled group) was not completely separated from the omnivores in a stable isotopic trophic level diagram, this analysis proved to add valuable information on probable dietary habits. The age deviation of the sampling date from the respective Calibomb date was found strongly correlated with the δ¹³C values, probably due to influence from marine diet components. For the omnivore individuals, there were indications of seasonal effects on δ¹³C and the age deviation. No significant correlation was found between the age deviation and the δ¹⁵N values of any dietary group. No influence of sex or year of birth was found on neither the ¹⁴C nor the δ¹³C and δ¹⁵N values of the serum samples. The data were also divided into two groups (omnivores and pooled group), based on the level of δ¹⁵N in the samples. The consumption of high δ¹⁵N-valued fish and birds can be responsible for this clustering.     

Establishment of tree seedlings in the understory of restoration plantations: natural regeneration and enrichment plantings

Little is known about the potential of restoration plantations to provide appropriate understory conditions to support the establishment of seeds arriving from neighboring native forests. In this article, we investigated how seedling establishment is affected in the understory of restoration sites of different ages and assessed some of the potential environmental factors controlling this ecological process. We first compared the density and richness of native tree seedlings among 10‐, 22‐, and 55‐year‐old restoration plantations within the Atlantic Forest region of southeastern Brazil. Then, we undertook a seed addition experiment in each study site, during the wet season, and compared seedling emergence, survival, and biomass on local versus old‐growth forest soil (transferred from a reference ecosystem), in order to test whether local substrate could hamper seedling establishment. As expected, the oldest restoration site had higher density and richness of spontaneously regenerating seedlings. However, seedling establishment was less successful both in the oldest restoration planting and using substrate transferred from a reference ecosystem, where emergence and survival were lower, but surviving seedlings grew better. We attribute these results to lower light availability for seedlings in the understory of the oldest site and speculate that higher incidence of pathogens on old‐growth forest soil may have increased seedling mortality. We conclude that the understory of young restoration plantations provides suitable microsite conditions at the early establishment phases for the spontaneous regeneration or enrichment planting of native trees.