Combined effects of dietary arginine, leucine and protein levels on fatty acid composition and gene expression in the muscle and subcutaneous adipose tissue of crossbred pigs

The cumulative effects of dietary arginine, leucine and protein levels on fat content, fatty acid composition and mRNA levels of genes controlling lipid metabolism in pig longissimus lumborum muscle and subcutaneous adipose tissue (SAT) were investigated. The experiment was performed on fifty-four intact male pigs (Duroc × Pietrain × Large White × Landrace crossbred), with a live weight ranging from 59 to 92 kg. The pigs were randomly assigned to one of six experimental treatments (n 9). The treatments followed a 2 × 3 factorial arrangement, with two levels of arginine supplementation (0 v. 1 %) and three levels of a basal diet (normal protein diet, NPD; reduced protein diet, RPD; reduced protein diet to achieve 2 % of leucine, RPDL). The results showed that dietary arginine supplementation did not affect the intramuscular fat (IMF) content and back fat thickness, but increased the total fat in SAT. This effect was associated with an increase in fatty acid synthase (FASN) and stearoyl-CoA desaturase (SCD) mRNA levels in SAT, which suggests that arginine might be involved in the differential regulation of some key lipogenic genes in pig muscle and SAT. The increase in IMF content under the RPD, with or without leucine supplementation, was accompanied by increased FASN and SCD mRNA levels. Arginine supplementation did not influence the percentage of main fatty acids, while the RPD had a significant effect on fatty acid composition in both tissues. Leucine supplementation of RPD did not change IMF, total fat of SAT and back fat thickness, but increased 16 : 0 and 18 : 1cis-9 and decreased 18 : 2n-6 in muscle. © The Authors 2013

Influence of betaine and arginine supplementation of reduced protein diets on fatty acid composition and gene expression in the muscle and subcutaneous adipose tissue of cross-bred pigs

© The Authors 2016. The isolated or combined effects of betaine and arginine supplementation of reduced protein diets (RPD) on fat content, fatty acid composition and mRNA levels of genes controlling lipid metabolism in pig m. longissimus lumborum and subcutaneous adipose tissue (SAT) were assessed. The experiment was performed on forty intact male pigs (Duroc×Large White×Landrace cross-breed) with initial and final live weights of 60 and 93 kg, respectively. Pigs were randomly assigned to one of the following five diets (n 8): 16·0 % of crude protein (control), 13·0 % of crude protein (RPD), RPD supplemented with 0·33 % of betaine, RPD supplemented with 1·5 % of arginine and RPD supplemented with 0·33 % of betaine and 1·5 % of arginine. Data confirmed that RPD increase intramuscular fat (IMF) content and total fat content in SAT. The increased total fat content in SAT was accompanied by higher GLUT type 4, lipoprotein lipase and stearoyl-CoA desaturase mRNA expression levels. In addition, the supplementation of RPD with betaine and/or arginine did not affect either IMF or total fat in SAT. However, dietary betaine supplementation slightly affected fatty acid composition in both muscle and SAT. This effect was associated with an increase of carnitine O-acetyltransferase mRNA levels in SAT but not in muscle, which suggests that betaine might be involved in the differential regulation of some key genes of lipid metabolism in pig muscle and SAT. Although the arginine-supplemented diet decreased the mRNA expression level of PPARG in muscle and SAT, it did not influence fat content or fatty acid composition in any of these pig tissues

The family 11 carbohydrate-binding module of Clostridium thermocellum Lic26A-Cel5E accommodates β-1,4- and β-1,3-1,4-mixed linked glucans at a single binding site

Modular glycoside hydrolases that attack recalcitrant polymers generally contain noncatalytic carbohydrate-binding modules (CBMs), which play a critical role in the action of these enzymes by localizing the appended catalytic domains onto the surface of insoluble polysaccharide substrates. Type B CBMs, which recognize single polysaccharide chains, display ligand specificities that are consistent with the substrates hydrolyzed by the associated catalytic domains. In enzymes that contain multiple catalytic domains with distinct substrate specificities, it is unclear how these different activities influence the evolution of the ligand recognition profile of the appended CBM. To address this issue, we have characterized the properties of a family 11 CBM (CtCBM11) in Clostridium thermocellum, Lic26A-Cel5E, an enzyme that contains GH5 and GH26 catalytic domains that display β-1,4- and β-1,3-1,4-mixed linked endoglucanase activity, respectively. Here we show that CtCBM11 binds to both β-1,4-and β-1,3-1,4-mixed linked glucans, displaying Ka values of 1.9 × 105, 4.4 × 104, and 2 × 103 M-1 for Glc-β1,4-Glc-β1,4-Glc-β1,3-Glc, Glc-β1,4-Glc-β1,4-Glc-β1,4-Glc, and Glc-β1,3-Glc-β1,4- Glc-β1,3-Glc, respectively, demonstrating that CBMs can display a preference for mixed linked glucans. To determine whether these ligands are accommodated in the same or diverse sites in CTCBM11, the crystal structure of the protein was solved to a resolution of 1.98 Å. The protein displays a β-sandwich with a concave side that forms a potential binding cleft. Site-directed mutagenesis revealed that Tyr22, Tyr53, and Tyr129, located in the putative binding cleft, play a central role in the recognition of all the ligands recognized by the protein. We propose, therefore, that CtCBM11 contains a single ligand-binding site that displays affinity for both β-1,4- and β-1,3-1,4-mixed linked glucans.authorsversionpublishe

Higher order scaffoldin assembly in Ruminococcus flavefaciens cellulosome is coordinated by a discrete cohesin-dockerin interaction

The authors acknowledge financial support from Fundacao para a Ciencia e a Tecnologia (Lisbon, Portugal) through grants PTDC/BIA-MIC/5947/2014, RECI/BBB-BEP/0124/2012 while PB and VMRP were supported by the individual fellowships SFRH/BD/86821/2012 and IF/01621/2013, respectively. The authors also acknowledge Professor Maria Joao Romao for access to the crystallization facilities of the Protein Crystallography Group in the Faculty of Science and Technology, Universidade NOVA de Lisboa, as well as the Soleil synchrotron, L'Orme des Merisiers, Saint-Aubin, France, (beamline PROXIMA-1) for access and technical support during data collection, and the European Community's Seventh Framework Programme (FP7/2007-2013) under BioStruct-X (grant agreement No. 283570, proposal number: Biostruct-X_4399) for funding. The Unidade de Ciencias Biomoleculares Aplicadas (UCIBIO- REQUIMTE) is financed by national funds from Fundacao para a Ciencia e Tecnologia/Ministerio da Educacao e Ciencia (FCT/ME) (UID/Multi/04378/2013) and co-financed by the European Regional Development Fund under the PT2020 Partnership Agreement (POCI-01-0145-FEDER-007728).Cellulosomes are highly sophisticated molecular nanomachines that participate in the deconstruction of complex polysaccharides, notably cellulose and hemicellulose. Cellulosomal assembly is orchestrated by the interaction of enzyme-borne dockerin (Doc) modules to tandem cohesin (Coh) modules of a non-catalytic primary scaffoldin. In some cases, as exemplified by the cellulosome of the major cellulolytic ruminal bacterium Ruminococcus flavefaciens, primary scaffoldins bind to adaptor scaffoldins that further interact with the cell surface via anchoring scaffoldins, thereby increasing cellulosome complexity. Here we elucidate the structure of the unique Doc of R. flavefaciens FD-1 primary scaffoldin ScaA, bound to Coh 5 of the adaptor scaffoldin ScaB. The RfCohScaB5-DocScaA complex has an elliptical architecture similar to previously described complexes from a variety of ecological niches. ScaA Doc presents a single-binding mode, analogous to that described for the other two Coh-Doc specificities required for cellulosome assembly in R. flavefaciens. The exclusive reliance on a single-mode of Coh recognition contrasts with the majority of cellulosomes from other bacterial species described to date, where Docs contain two similar Coh-binding interfaces promoting a dual-binding mode. The discrete Coh-Doc interactions observed in ruminal cellulosomes suggest an adaptation to the exquisite properties of the rumen environment.publishersversionpublishe

Genetic background and diet impact beef fatty acid composition and stearoyl-CoA desaturase mRNA expression

Articles in International JournalsThe intramuscular fat composition of ruminant meats influences the quality of the final product, which explains the increasing interest in assessing the fatty acid profile of meat from different production systems. In this study, it was hypothesized that there are breed- and diet induced variations on lipid metabolism in the muscle, which may be, at least partially, modulated by the stearoyl-CoA desaturase (SCD) gene expression levels. Forty purebred young bulls from two phylogenetically distant autochthonous cattle breeds, Alentejana and Barrosã(n = 20 for each breed), were assigned to two different diets (low vs. high silage) and slaughtered at 18 months of age. Meat fatty acid composition, including the detailed conjugated linoleic acid (CLA) isomeric profile, was determined along with the SCD mRNA levels. Meat from Barrosã bulls fed the low silage diet was richer in monounsaturated fatty acids, CLA and trans fatty acids, when compared to that from Alentejana bulls. The meat content in polyunsaturated fatty acids was similar across experimental groups. Moderate positive correlations between the SCD mRNA levels and the products of this enzyme activity were found, although they were not reflected on the calculated desaturase indices. Overall, these findings highlight the importance of taking into account the genetic background while devising feeding strategies to manipulate beef fatty acid composition

Characterisation of microbial attack on archaeological bone

As part of an EU funded project to investigate the factors influencing bone preservation in the archaeological record, more than 250 bones from 41 archaeological sites in five countries spanning four climatic regions were studied for diagenetic alteration. Sites were selected to cover a range of environmental conditions and archaeological contexts. Microscopic and physical (mercury intrusion porosimetry) analyses of these bones revealed that the majority (68%) had suffered microbial attack. Furthermore, significant differences were found between animal and human bone in both the state of preservation and the type of microbial attack present. These differences in preservation might result from differences in early taphonomy of the bones. © 2003 Elsevier Science Ltd. All rights reserved