Polysaccharide co-polymerase WzzB/WzzE chimeras reveal transmembrane 2 region of WzzB is important for interaction with WzyB

The ability of bacteria to synthesise complex polysaccharide chains at a controlled number of repeating units has wide implications for a range of biological activities that include: symbiosis, biofilm formation and immune system avoidance. Complex polysaccharide chains such as the O antigen (Oag) component of lipopolysaccharide and the enterobacterial common antigen (ECA) are synthesised by the most common polysaccharide synthesis pathway used in bacteria, known as the Wzy-dependent pathway. The Oag and ECA are polymerized into chains via the inner membrane proteins WzyB and WzyE, respectively, while the respective co-polymerases WzzB and WzzE modulate the number of repeat units in the chains or “the modal length” of the polysaccharide via a hypothesised interaction. Our data shows for the first time “cross-talk” between Oag and ECA synthesis in that WzzE is able to partially regulate Oag modal length via a potential interaction with WzyB. To investigate this, one or both of the transmembrane regions (TM1 and TM2) of WzzE and WzzB were swapped creating six chimera proteins. Several chimeric proteins showed significant increases Oag modal length control, while others reduced control. Additionally, co-purification experiments show an interaction between WzyB and WzzB for the first time without the use of a chemical cross-linker, and a novel interaction between WzyB and WzzE. These results suggest the TM2 region of Wzz proteins plays a critical role in Oag and ECA modal length control, presumably via the interaction with respective Wzy proteins, thus providing insight into the complex mechanism underlying the control of polysaccharide biosynthesis. Importance Bacteria synthesise complex polysaccharide chains at a controlled number of repeating units, this has wide implications for a range of bacterial activities involved in virulence. Examples of complex polysaccharide chains include, the O antigen (Oag) component of lipopolysaccharide and the enterobacterial common antigen (ECA), both of these examples are predominantly synthesised by their own independent Wzy-dependent pathway. Our data show for the first time “cross-talk” between Oag and ECA synthesis and identifies novel physical protein-protein interactions between proteins in these systems. These findings further the understanding of how the system functions to control polysaccharide chain length which has great implications for novel biotechnologies and/or the combat of bacterial diseases.

Algorithm for measuring fiber length distributions of raw cotton and combed wool using dual-beard image method

The dual-beard image method, which has been developed in recent years as a fast and economical method for fiber length measurement, consists of dual-beard specimen preparation, image processing, fibrogram extraction, and length parameter calculations. However, one of the shortcomings of this method is that it can only produce extremely limited length parameters such as mean length, coefficient of variation, modal length, and quality length (UHML, upper half mean length). This study introduces a new algorithm for converting the dual-beard fibrogram into a length distribution histogram which can be used to calculate most of the current length parameters. The algorithm is based on the short fiber content formulae but modified by theoretical analysis and experimental comparison. The length distributions of 24 cotton samples and 12 wool samples are measured by dual-beard image method with the new algorithm, and Advanced Fiber Information System (AFIS) and Almeter are employed for comparison. Comparative analysis shows that the peaks and ranges of the distribution histograms using the dual-beard method are similar to those from the reference methods, and the shapes of histograms from difference methods match well with one another. In addition, five length parameters calculated from the dual-beard distributions are verified to be consistent with those measured by AFIS and Almeter. The new algorithm employed in the dual-beard image method avoids the differential operation which amplifies the curve error, giving the dual-beard image method the ability to output more comprehensive length information.

Age and growth of Oreochromis niloticus (Perciformes: Cichlidae) in Mexico

Age and growth of Oreochromis niloticus from Lagoon of Coatetelco, Morelos State, Mexico were studied from January through December, 1993. Scales of 318 specimens were collected. Modal length at capture was 10. 5 -11. 5 cm standard length. Scales rings were forrned during December. Back-calculated lengths-at-age showed no significant differences by sexo Four check marks were recorded. According to the growth curve parameters for population, the fish grow at a low rate (k=O.07) until they achieve a size (Loo) of 2 9. 19 cm. Length-frequency analysis (Bhattacharya's Gaussian component deterrnination procedure) do not differ significantly (t-student, p

The Lophius budegassa component of monkfish catches in Scottish waters

Laurenson, C. H., Dobby, H., and McLay, H. A. 2008. The Lophius budegassa component of monkfish catches in Scottish waters. – ICES Journal of Marine Science, 65: 1346–1349. To date, research efforts on Lophius species in waters around Scotland (ICES Divisions IVa, VIa, and VIb) have focused almost exclusively on Lophius piscatorius. Here, the characteristics and distribution of the Lophius budegassa component of the catch are described using data collected by observers during commercial fishing trips and scientific surveys on chartered commercial fishing vessels between 1998 and 2006. At Rockall Bank (VIb), L. budegassa were rare, just 0.1% of the catch of Lophius spp., whereas west of Scotland (VIa) and around the Shetland Islands (IVa), they made up 18 and 2% of catches, respectively, with greatest prevalence towards the shelf edge. Fish length ranged from 16 to 89 cm with a modal length at 40 cm. Greater proportions of large individuals were recorded around the Shetland Islands than in other parts of the study area. Overall, the sex ratio was 1:1, and lengths at 50% maturity were estimated to be 70.4 cm for females and 49.4 cm for males.

Gillnet mesh selectivity of the sandbar shark (Carcharhinus plumbeus): implications for fisheries management

McAuley, R. B., Simpfendorfer, C. A., and Wright, I. W. 2007. Gillnet mesh selectivity of the sandbar shark (Carcharhinus plumbeus): implications for fisheries management. – ICES Journal of Marine Science, 64. Gillnet mesh selectivity parameters for the sandbar shark (Carcharhinus plumbeus) were estimated from catches taken by an experimental net of six panels of mesh, varying in size from 10.2 to 25.4 cm. The length selectivity of each mesh size was described by five different models. According to model deviance values, the four models based on the SELECT method of estimation provided better fits to the data than the gamma model previously applied to sharks. Lengths at maximum selectivity were estimated to be between 5.3 and 7.0×stretched mesh size. The breadth of the selectivity curves was greater than have been reported for most species of shark. Lognormal and normal curve forms yielded the lowest model deviance and were judged to provide the best fits to the data. Peak selectivity of the commercially utilized mesh sizes was generally estimated to be greater than the observed modal length class of the commercial C. plumbeus catch. This suggests that a relatively high abundance of smaller sharks in the study area offsets gear selectivity effects in determining the size composition of commercial catches. These results have important implications for the recovery of this overexploited stock and also for managing international gillnet fisheries for the species.