Comparison of protein fermentation characteristics in rumen fluid determined with the gas production technique and the nylon bag technique

In this study, a modified version of the gas production technique was used to determine protein fermentation characteristics in rumen fluid of 19 feedstuffs. Performing the incubations in a N-free environment, and with an excess of rapidly fermentable carbohydrates, made N the limiting factor to microbial growth, and so gas production profiles reflected the availability of N from the feed samples. Results showed that fermentation of protein in rumen fluid can be determined with this modified gas production technique, and that there were distinct differences in protein fermentation between the feed samples. Availability of protein for fermentation was highest in wheat, potato pieces and lupin, and lowest in Rumiraap, a formaldehyde treated rapeseed meal, palm kernel expeller and brewery grains. The protein degradation characteristics of the 19 feed ingredients were also determined with the in situ nylon bag technique. With the obtained results, the amount of rumen escape protein (REP) was calculated for each feedstuff. The results showed that the rate of degradation ranged from 0.010/h for Rumiraap to 0.151/h for wheat. The amount of REP ranged from 197 g/kg CP for lupin to 840 g/kg CP for Rumiraap. Comparing the gas production results with the results obtained with the nylon bag technique showed that there was a good relationship between the gas production after 12–25 h of incubation and the calculated amount of REP (r² = 0.83–0.85). The results show that the adapted gas production technique, being depleted of N and using an excess of rapidly fermentable carbohydrates, is suitable to recognize differences in N availability between feed samples and can be used as an alternative to the nylon bag technique and other in vitro techniques.     

<Emphasis Type="Italic">mab-31</Emphasis> and the TGF-β pathway act in the ray lineage to pattern <Emphasis Type="Italic">C. elegans</Emphasis>male sensory rays

Background  

C. elegans TGF-β-like Sma/Mab signaling pathway regulates both body size and sensory ray patterning. Most of the components in this pathway were initially identified by genetic screens based on the small body phenotype, and many of these mutants display sensory ray patterning defect. At the cellular level, little is known about how and where these components work although ray structural cell has been implicated as one of the targets. Based on the specific ray patterning abnormality, we aim to identify by RNAi approach additional components that function specifically in the ray lineage to elucidate the regulatory role of TGF-β signaling in ray differentiation.     

Measuring morphological parameters of the pelvic floor for finite element modelling purposes

The goal of this study was to obtain a complete data set needed for studying the complex biomechanical behaviour of the pelvic floor muscles using a computer model based on the finite element (FE) theory. The model should be able to predict the effect of surgical interventions and give insight into the function of pelvic floor muscles. Because there was a lack of any information concerning morphological parameters of the pelvic floor muscle structures, we performed an experimental measurement to uncover those morphological parameters. Geometric parameters as well as muscle parameters of the pelvic floor muscles were measured on an embalmed female cadaver. A three-dimensional (3D) geometric data set of the pelvic floor including muscle fibre directions was obtained using a palpator device. A 3D surface model based on the experimental data, needed for mathematical modelling of the pelvic floor, was created. For all parts of the diaphragma pelvis, the optimal muscle fibre length was determined by laser diffraction measurements of the sarcomere length. In addition, other muscle parameters such as physiological cross-sectional area and total muscle fibre length were determined. Apart from these measurements we obtained a data set of the pelvic floor structures based on nuclear magnetic resonance imaging (MRI) on the same cadaver specimen. The purpose of this experiment was to discover the relationship between the MRI morphology and geometrical parameters obtained from the previous measurements. The produced data set is not only important for biomechanical modelling of the pelvic floor muscles, but it also describes the geometry of muscle fibres and is useful for functional analysis of the pelvic floor in general. By the use of many reference landmarks all these morphologic data concerning fibre directions and optimal fibre length can be morphed to the geometrical data based on segmentation from MRI scans.These data can be directly used as an input for building a mathematical model based on FE theory.     

Intellectual disability-associated disruption of O-GlcNAc cycling impairs habituation learning in Drosophila

O-GlcNAcylation is a reversible co-/post-translational modification involved in a multitude of cellular processes. The addition and removal of the O-GlcNAc modification is controlled by two conserved enzymes, O-GlcNAc transferase (OGT) and O-GlcNAc hydrolase (OGA). Mutations in OGT have recently been discovered to cause a novel Congenital Disorder of Glycosylation (OGT-CDG) that is characterized by intellectual disability. The mechanisms by which OGT-CDG mutations affect cognition remain unclear. We manipulated O-GlcNAc transferase and O-GlcNAc hydrolase activity in Drosophila and demonstrate an important role of O-GlcNAcylation in habituation learning and synaptic development at the larval neuromuscular junction. Introduction of patient-specific missense mutations into Drosophila O-GlcNAc transferase using CRISPR/Cas9 gene editing leads to deficits in locomotor function and habituation learning. The habituation deficit can be corrected by blocking O-GlcNAc hydrolysis, indicating that OGT-CDG mutations affect cognition-relevant habituation via reduced protein O-GlcNAcylation. This study establishes a critical role for O-GlcNAc cycling and disrupted O-GlcNAc transferase activity in cognitive dysfunction, and suggests that blocking O-GlcNAc hydrolysis is a potential strategy to treat OGT-CDG.     

Skewed Segregation of the mtDNA nt 8993 (TrG) Mutation in Human Oocytes

Rapid changes in mtDNA variants between generations have led to the bottleneck theory, which proposes a dramatic reduction in mtDNA numbers during early oogenesis. We studied oocytes from a woman with heteroplasmic expression of the mtDNA nt 8993 (T-->G) mutation. Of seven oocytes analyzed, one showed no evidence of the mutation, and the remaining six had a mutant load > 95%. This skewed expression of the mutation in oocytes is not compatible with the conventional bottleneck theory. A possible explanation is that, during amplification of mtDNA in the developing oocyte, mtDNA from one mitochondrion is preferentially amplified. Thus, subsequent mature oocytes may contain predominantly wild-type or mutant mitochondrial genomes.     

Characterization of theAc/Ds behaviour in transgenic tomato plants using plasmid rescue

We describe the use of plasmid rescue to facilitate studies on the behaviour ofDs andAc elements in transgenic tomato plants. The rescue ofDs elements relies on the presence of a plasmid origin of replication and a marker gene selective inEscherichia coli within the element. The position within the genome of modifiedDs elements, rescued both before and after transposition, is assigned to the RFLP map of tomato. Alternatively to the rescue ofDs elements equipped with plasmid sequences,Ac elements are rescued by virtue of plasmid sequences flanking the element. In this way, the consequences of the presence of an (active)Ac element on the DNA structure at the original site can be studied in detail. Analysis of a library ofAc elements, rescued from the genome of a primary transformant, shows thatAc elements are, infrequently, involved in the formation of deletions. In one case the deletion refers to a 174 bp genomic DNA sequence immediately flankingAc. In another case, a 1878 bp internalAc sequence is deleted.     

Cell surface antigens on osteoclasts and related cells in the quail studied with monoclonal antibodies

The properties of five monoclonal antibodies raised against isolated osteoclasts are described. Osteoclasts were isolated from medullary bone of egg-laying female quails. Mice were immunized with cell preparations consisting for about 10% of multinucleated osteoclasts. A large number of monoclonal antibodies against cell surface antigens were obtained, five of which were extensively characterized by their interactions with different tissues of the quail and their cross-reactivity with other species. Two monoclonals (OC 5.3 and OC 6.8), recognize surface antigens present on osteoclasts, monocytes, granulocytes and endothelial cells, but not on osteoblasts, osteocytes, fibroblasts, lymphocytes, erythrocytes and others. The three other monoclonal antibodies are specific for multinucleated osteoclasts in bone tissue but recognize some cell surface structures in other tissues. Antibody OC 6.9, which in bone tissue stains primarily the surface area of the osteoclast that is adjacent to the resorbing bone surface, also interacts with bile capillaries in the liver and with specific, but not yet identified parts of the nephron. The antibodies OC 6.1 and OC 6.3 interact with Kupffer cells in the liver and tissue macrophages of small intestine. In view of the possible fallacies inherent to the use of cell surface markers for the demonstration of cell relationship and origin, definite conclusions can not yet be made. The fact that the osteoclast, the Kupffer cell and the intestine macrophage are the only cells in bone, bone marrow, liver, kidney and intestine, that share the same surface antigen recognized by monoclonals OC 6.1 and OC 6.3, suggests, however, a common origin for osteoclasts and a number of well described tissue macrophages.