Identification of Eggshell Membrane Proteins and Purification of Ovotransferrin and β-NAGase from Hen Egg White

Exposure of selected Gram-positive and Gram-negative bacterial pathogens to egg shell membranes (ESM) significantly reduced their thermal resistance and/or inactivated cells. Although the components responsible for this antibacterial activity have not been conclusively identified, several proteins associated with the ESM activity have been identified including β-N-acetylglucosaminidase, lysozyme and ovotransferrin, with each displaying varying degrees of antibacterial activity. Numerous attempts to purify active fractions of β-N-acetylglucosaminidase, lysozyme and ovotransferrin from the ESM proved somewhat limited; however, hen egg white (HEW) β-N-acetylglucosaminidase was purified using a two-step chromatographic procedure, isoelectric focusing followed by cation exchange chromatography. Pure fractions of ovotransferrin were also obtained in the process. SDS-PAGE electrophoresis and Matrix-Assisted Laser Desorption Time-of-Flight Mass Spectrometry were then used to partially characterize the individual protein components. Purified protein fractions such as these will be required in order to fully elucidate the mechanism responsible for the antimicrobial properties associated with the ESM.     

Characterization of bovine seminal plasma by proteomics

Previous investigations of bovine seminal plasma (BSP) have revealed the identities of the three major proteins, BSP-PDC109, BSP-A3 and BSP-30 kDa, which together constitute about half of the total protein, as well as about 30 of the minor proteins. Analyses of BSP by 2-DE have revealed about 250 protein spots, suggesting that much of the BSP proteome remains undescribed. In this study, BSP has been analyzed by 2-D LC-based and SDS-PAGE-based proteomic methods. Ninety-nine proteins were identified, including 49 minor proteins that have not previously been described in seminal plasma of any species.     

Seasonal home ranges and fidelity to breeding sites among ringed seals

Population structure and patterns of habitat use among ringed seals (Phoca hispida) are poorly known, in part because seasonal movements have not been adequately documented. We monitored the movements of 98 ringed seals in the Beaufort and Chukchi seas between 1990 and 2006 using three forms of telemetry. In the winter—spring period (when the seals were occupying shorefast ice), we used radio and ultra-sonic tags to track movements above and below the ice, respectively. We used satellite-linked transmitters in summer and fall (when the seals ranged away from their winter sites) to track at-sea movements. In the shorefast ice habitat, the home ranges of 27 adult males ranged from <1 to 13.9 km² (median = 0.628) while the home ranges of 28 adult females ranged from <1 to 27.9 km² (median = 0.652). The 3-dimensional volumes used by 9 seals tracked acoustically under the ice averaged 0.07 (SD = 0.04) km³ for subadults and adult males and 0.13 (SD = 0.04) km³ for adult females. Three of the radio-tracked seals and 9 tracked by satellite ranged up to 1,800 km from their winter/spring home ranges in summer but returned to the same small (1–2 km²) sites during the ice-bound months in the following year. The restricted movements of ringed seals during the ice-bound season—including the breeding season—limits their foraging activities for most of the year and may minimize gene flow within the species.     

Evaluation of nutrient digestibility and fecal characteristics of exotic felids fed horse‐ or beef‐based diets: use of the domestic cat as a model for exotic felids

The objective of this study was to determine the effects of feeding commercially available beef‐ and horse‐based diets on nutrient digestibility and fecal characteristics of large captive exotic felids and domestic cats. Four species of large exotic felids including cheetahs, Malayan tigers, jaguars, and Amur tigers, and domestic cats were utilized in a crossover design. Raw meat diets included a beef‐based diet (57% protein; 28% fat) and a horse‐based diet (51% protein; 30% fat). All cats were acclimated to the diet for 16 days followed by a 4 day collection period, where total feces, including one fresh sample, were collected. All feces were scored on collection. Intake did not differ due to diet, but fecal output was greater when cats consumed the horse‐based diet. Total tract apparent dry matter (DM) digestibility was higher (P<0.05) and organic matter (OM) and crude protein (CP) digestibilities were lower (P<0.05) when cats were fed the beef‐based diet compared with the horse‐based diet. CP digestibility was similar in domestic cats and cheetahs, and greater (P<0.05) than Amur tigers. Fecal scores were lower and fecal DM was greater (P<0.05) when cats consumed the horse‐based diet compared with the beef‐based diet. Domestic cats had lower (P<0.05) fecal ammonia concentrations compared with all other species. Fecal ammonia concentrations were lowest (P<0.05) when cats were fed the horse‐based diet. Fecal total short‐chain fatty acid (SCFA), branched‐chain fatty acid (BCFA), and butyrate concentrations were higher (P<0.05) when cats consumed the beef‐based diet. Our results suggest that the domestic cat serves as an appropriate model for large exotic felid species, but differences among the species exist. Decreased nutrient digestibility by tigers and jaguars should be considered when developing feeding recommendations for these species based on domestic cat data. Zoo Biol 29:432–448, 2010. © 2009 Wiley‐Liss, Inc.     

Photoaffinity labeling of Ras converting enzyme 1 (Rce1p) using a benzophenone-containing peptide substrate

Isoprenylation is a post-translational modification that increases protein hydrophobicity and helps target certain proteins to membranes. Ras converting enzyme 1 (Rce1p) is an endoprotease that catalyzes the removal of a three residue fragment from the C-terminus of isoprenylated proteins. To obtain structural information about this membrane protein, photoaffinity labeling agents are being prepared and employed. Here, we describe the synthesis of a benzophenone-containing peptide substrate analogue for Rce1p. Using a continuous spectrofluorometric assay, this peptide was shown to be a substrate for Rce1p. Mass spectrometry was performed to confirm the site of cleavage and structure of the processed probe. Photolysis of the biotinylated compound in the presence of membranes containing Rce1p followed by streptavidin pull-down and Western blot analysis indicated that Rce1p had been labeled by the probe. Photolysis in the presence of both the biotinylated, benzophenone-containing probe and a farnesylated peptide competitor reduced the extent of labeling, suggesting that labeling is occurring in the active site.     

Cadmium stress: an oxidative challenge

At the cellular level, cadmium (Cd) induces both damaging and repair processes in which the cellular redox status plays a crucial role. Being not redox-active, Cd is unable to generate reactive oxygen species (ROS) directly, but Cd-induced oxidative stress is a common phenomenon observed in multiple studies. The current review gives an overview on Cd-induced ROS production and anti-oxidative defense in organisms under different Cd regimes. Moreover, the Cd-induced oxidative challenge is discussed with a focus on damage and signaling as downstream responses. Gathering these data, it was clear that oxidative stress related responses are affected during Cd stress, but the apparent discrepancies observed in between the different studies points towards the necessity to increase our knowledge on the spatial and temporal ROS signature under Cd stress. This information is essential in order to reveal the exact role of Cd-induced oxidative stress in the modulation of downstream responses under a diverse array of conditions.