Effects of a n-3 polyunsaturated fatty acid-enriched diet on embryo production in dairy cows

Beneficial effects of n-3 polyunsaturated fatty acid (PUFA) supplementation on dairy cow reproduction have been previously reported. The objectives of the present study were to assess whether n-3 PUFA supplementation would affect in vitro embryo production (IVP) after ovarian stimulation. Holstein cows received a diet with 1% dry matter supplementation of either n-3 PUFA (n = 18, microencapsulated fish oil) or a control, n-6 PUFA (n = 19, microencapsulated soy oil). Both plasma and follicular fluid FA composition showed integration of total PUFA through the diet. All cows underwent an IVP protocol consisting of ovarian stimulation, ultrasound-guided transvaginal oocyte retrieval (ovum pick-up, OPU, five per cow) followed by in vitro maturation, fertilisation and 7 days of embryo development. A tendency toward an increase in the blastocyst rate (diet effect, P = 0.0865) was observed in n-3 cows, with 49.6 ± 5.5% vs 42.3 ± 5.5% in control n-6 cows. A significant increase (diet effect, P = 0.0217) in the good-quality blastocyst rate (freezable blastocysts) was reported in n-3 cows (42.2 ± 7.7%) compared to control n-6 cows (32.7 ± 7.7%). A significant difference in lipid composition was shown in the oocytes recovered by OPU from n-3 and n-6 treated cows, by intact single-oocyte MALDI-TOF mass spectrometry. The 42 differentially abundant identified lipids were mainly involved in cell membrane structure. In conclusion, n-3 PUFA supplementation enhanced oocyte quality and modified their lipid composition. Further studies are necessary to investigate the potential link of these lipid modifications with enhanced oocyte quality.

Binder of Sperm Proteins 1 and 5 have contrasting effects on the capacitation of ram spermatozoa

Binder of Sperm Proteins (BSPs) are the most abundant seminal plasma protein family in the ram and bull. They have been extensively studied in the bull but less is known about their function in ovine seminal plasma and current knowledge suggests that BSPs may have different effects in these two species. In the bull, they facilitate capacitation and destabilize the sperm membrane during in vitro handling, whereas in the ram, they appear to stabilize the sperm membrane and prevent cryopreservation-induced capacitation-like changes. Further investigation into the effects of BSPs on ram spermatozoa under capacitating conditions is required to further clarify their physiological roles in the ram. We investigated the effects of Binder of Sperm Proteins 1 and 5 on epididymal ram spermatozoa in conditions of low, moderate, and high cAMP. BSPs had minimal effects on sperm function in low-cAMP conditions, but caused significant changes under cAMP upregulation. BSP1 stabilized the membrane and qualitatively reduced protein tyrosine phosphorylation, but significantly increased cholesterol efflux and induced spontaneous acrosome reactions. BSP5 slightly increased spontaneous acrosome reactions and caused sperm necrosis. However, BSP5 had minimal effects on membrane lipid order and cholesterol efflux and did not inhibit protein tyrosine phosphorylation. These findings demonstrate that under maximal cAMP upregulation, BSP1 affected ram spermatozoa in a manner comparable to bull spermatozoa, while BSP5 did not.

Identification of the epidermal growth factor receptor as the receptor for Salmonella Rck-dependent invasion

The Salmonella Rck outer membrane protein binds to the cell surface, which leads to bacterial internalization via a Zipper mechanism. This invasion process requires induction of cellular signals, including phosphorylation of tyrosine proteins, and activation of c-Src and PI3K, which arises as a result of an interaction with a host cell surface receptor. In this study, epidermal growth factor receptor (EGFR) was identified as the cell signaling receptor required for Rck-mediated adhesion and internalization. First, Rck-mediated adhesion and internalization were shown to be altered when EGFR expression and activity were modulated. Then, immunoprecipitations were performed to demonstrate the Rck-EGFR interaction. Furthermore, surface plasmon resonance biosensor and homogeneous time-resolved fluorescence technologies were used to demonstrate the direct interaction of Rck with the extracellular domain of human EGFR. Finally, our study strongly suggests a noncompetitive binding of Rck and EGF to EGFR. Overall, these results demonstrate that Rck is able to bind to EGFR and thereby establish a tight adherence to provide a signaling cascade, which leads to internalization of Rck-expressing bacteria.-Wiedemann, A., Mijouin, L., Ayoub, M. A., Barilleau, E., Canepa, S., Teixeira-Gomes, A. P., Le Vern, Y., Rosselin, M., Reiter, E., Velge, P. Identification of the epidermal growth factor receptor as the receptor for Salmonella Rck-dependent invasion.

Purification of native HBHA from Mycobacterium avium subsp. paratuberculosis

Background

Paratuberculosis remains today a major global problem in animal health, especially for dairy cattle. However, the diagnosis of its etiologic agent, Mycobacterium avium subsp. paratuberculosis (Map), still lacks sensitivity because of the lack of available antigens. Little is known about the virulence factors for this pathogen. In this study we have developed a method to produce and purify the heparin-binding hemagglutinin (HBHA), a major adhesin of Mycobacteria, from a culture of Map.

Findings

For this extremely slow-growing Mycobacterium, a culture was established in a 3-liter bioreactor. Using the bioreactor the amount of the Map biomass was increased 5-fold compared to a classical culture in flasks. The map-HBHA was purified from a Map lysate by heparin-Sepharose chromatography on HiTrap columns. Binding of map-HBHA onto heparin-Sepharose can be reduced in the presence of salt. Consequently, all steps of sample preparation and column equilibration were carried out in 20 mM Tris–HCl (pH 7.2). The map-HBHA was eluted by a linear NaCl gradient. High resolution mass spectrometry analyses revealed that the native form of map-HBHA has posttranslational modifications, including the removal of the initiation methionine, acetylation of the alanine residue at the N-terminal extremity and the presence of methylated lysines in the C-terminal domain of the protein.

Conclusions

An optimized culture of Map in a bioreactor was established to purify the native map-HBHA from a Map lysate by heparin-Sepharose chromatography. The availability of this antigen offers the possibility to study the structure of the protein and to examine its role in pathogenicity, in particular to better understand the specific interactions of Map with the intestinal tissue. The map-HBHA obtained in its native immunogenic form may also be useful to improve the diagnostic test, especially for the development of a new T-cell-based interferon gamma release assays.

Identification of a Member of a New RNase A Family Specifically Secreted by Epididymal Caput Epithelium1

In this study, we purified the first member of a new ribonuclease (RNase) A family from fluid of the proximal caput of the boar epididymis. This protein, named "Train A," is the most abundant compound secreted in the anterior part of the boar epididymis. After 2D electrophoresis, it is characterized by more than 10 isoforms ranging in size from 26 to 33 kDa and pI from 5 to 8.5. Several tryptic peptides were N-terminal sequenced, and an antiserum against one of these peptides was obtained. The protein was immunolocalized in the epididymal epithelium of the proximal caput, especially in the Golgi zone and the apical cytoplasm of the principal cells. In the lumen, spermatozoa were negative but droplets of reaction product were observed within the lumen. Full lengths of Train A cDNA were obtained from a lambdagt11 boar caput epididymis library and sequenced. The deduced protein is composed of 213 amino acids, including a 23-amino acid peptide signal and a potential N-glycosylation site. The mRNA of this protein has been retrieved and partially sequenced in the bull, horse, and ram, and homologous cDNA is found in databanks for the rat, mouse, and human. All the sequences are highly conserved between species. This protein and its mRNA are male-specific and exclusively expressed in the proximal caput of the epididymis, the only site where they have been found. Train A presents an RNase A family motif in its sequence. The RNase A family is a group of several short proteins (20-14 kDa) with greater and lesser degrees of ribonucleolytic activity and with supposed different roles in vivo. However, the presence of a long-conserved N-terminal specific sequence and the absence of RNase catalytic site for Train A indicate that Train A protein is a member of a new family of RNase A.

Cloning, nucleotide sequence, and expression of the Brucella melitensis sucB gene coding for an immunogenic dihydrolipoamide succinyltransferase homologous protein

The Brucella melitensis sucB gene encoding the dihydrolipoamide succinyltransferase (E2o) enzyme (previously identified as an immunogenic protein in infected sheep) was cloned and sequenced. The amino acid sequence predicted from the cloned gene revealed 88.8 and 51.2% identity to the dihydrolipoamide succinyltransferase SucB protein from Brucella abortus and Escherichia coli, respectively. Sera from naturally infected sheep showed antibody reactivity against the recombinant SucB protein.

Characterization of heat, oxidative, and acid stress responses in Brucella melitensis

Brucella melitensis is a facultative intracellular pathogen which is able to survive and replicate within phagocytic cells. Therefore, it has to adapt to a range of different hostile environments. In order to understand the mechanisms of intracellular survival employed by virulent B. melitensis 16M, an initial approach consisting of analysis of the differences in patterns of protein synthesis in response to heat, oxidative, and acid pH stresses by two-dimensional (2-D) polyacrylamide gel electrophoresis was used. Depending on the stress, this involved about 6.4 to 12% of the 676 protein spots detected in 2-D gel electrophoresis. On the basis of N-terminal sequence analysis and database searching, 19 proteins whose level of synthesis was up- or down-regulated by stress conditions were identified. Some of them were previously reported for Brucella, such as BvrR, DnaK, GroEL, and Cu-Zn superoxide dismutase (SOD). Eight other proteins closely matched proteins found in other bacteria: AapJ, alpha-ETF, ClpP, Fe and/or Mn SOD, malate dehydrogenase, IalB, 30S ribosomal protein S1, and pyruvate dehydrogenase E1 component beta subunit. Results indicated that B. melitensis could bring specific regulatory mechanisms into play in response to stress conditions. For example, the ribosome releasing factor in B. melitensis appeared to be a heat shock protein, whereas the ClpP protein, described as a heat shock protein for Escherichia coli, was strongly down-regulated in B. melitensis in response to heat stress. Some of the identified proteins and their potential specific regulation could be required for the adaptation of B. melitensis to environmental stresses encountered in phagocytic cells and possibly for bacterial virulence.

Identification and characterization of Brucella ovis immunogenic proteins using two-dimensional electrophoresis and immunoblotting

In a previous report, proteins from Brucella melitensis were characterized by two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) and N-terminal microsequencing. In the present report, we have extended this study to the second etiologic agent in ovine brucellosis, B. ovis, responsible for ram epididymitis and infertility. The combination of 2-D gel electrophoresis and protein microsequencing facilitated the location and identification of the major proteins of B. ovis on the 2-D pattern. These proteins comprised cytoplasmic, periplasmic, and some membrane proteins except the major outer membrane proteins. By comparing 2-D gel profiles of B. ovis with that of B. melitensis described previously, a few proteins with different expression levels were readily identified. Serum from a ram naturally infected with B. ovis was used in immunoblotting studies to identify immunogenic proteins recognized during the course of infection. This serum showed antibody reactivity against approximately 82 protein spots. Twenty-one of these proteins were identified either by use of monoclonal antibodies or by N-terminal microsequencing. Several proteins previously described in earlier Brucella works were identified: the 89 kDa outer membrane protein, DnaK, GroEL, BP26, and Cu-Zn superoxide dismutase. Eight proteins had amino acid sequences homologous to those of various proteins from other bacteria found in protein databases; NikA, dihydrolipoamide succinyltransferase, a hypothetical 31 kDa protein, malate dehydrogenase, succinyl-CoA synthetase alpha subunit, an amino acid ABC type transporter, Leu/Ile/Val-binding protein precursor, and ClpP. The remaining eight proteins had N-terminal sequences lacking similarity to existing databases entries. Thus, the 2-D PAGE analysis provided a convenient first approach in the characterization of immunogenic proteins.

Mapping and identification of Brucella melitensis proteins by two-dimensional electrophoresis and microsequencing

Two-dimensional (2-D) gel electrophoresis was used to map Brucella melitensis proteins. The 2-D proteins map of B. melitensis B115 revealed 595 silver-stained protein spots separated by both isoelectric point and molecular mass. Twenty-five proteins were identified either by immunoblotting using monoclonal antibodies (MAbs) or by N-terminal microsequencing. The protein spots identified by MAbs were the 89 kDa outer membrane protein, DnaK, bacterioferritin, CP24, and BP26. Some spots were identified by N-terminal microsequencing as proteins whose sequences had been reported previously from Brucella, such as three heat-shock proteins, namely DnaK, GroEL and GroES; bacterioferritin; Cu-Zn superoxide dismutase; and the 50S ribosomal protein L7/L12. Other proteins had amino acid sequences homologous with those of various proteins from other bacteria found in protein databases: ClpP; the 10K-S protein; the ORFU phosphoprotein; succinyl-CoA synthetase alpha sub-unit; an inorganic pyrophosphatase; the Fe and/or Mn superoxide dismutase; the nucleoside diphosphate kinase, an amino acid ABC type transporter, and an electron transfer flavoprotein small subunit. Seven proteins were identified with N-terminal sequences not yet reported in databases. The 2-D map established in this study will be the basis for comparative studies of protein expression in Brucella.