Rhamnolipids are conserved biosurfactants molecules: implications for their biotechnological potential

A range of isolates of Pseudomonas aeruginosa from widely different environmental sources were examined for their ability to synthesise rhamnolipid biosurfactants. No significant differences in the quantity or composition of the rhamnolipid congeners could be produced by manipulating the growth conditions. Sequences for the rhamnolipid genes indicated low levels of strain variation, and the majority of polymorphisms did lead to amino acid sequence changes that had no evident phenotypic effect. Expression of the rhlB and rhlC rhamnosyltransferase genes showed a fixed sequential expression pattern during growth, and no significant up-regulation could be induced by varying producer strains or growth media. The results indicated that rhamnolipids are highly conserved molecules and that their gene expression has a rather stringent control. This leaves little opportunity to manipulate and greatly increase the yield of rhamnolipids from strains of P. aeruginosa for biotechnological applications.     

Trypsin Activity Reduced by an Autocatalytically Produced Nonapeptide

Abstract

Trypsin, a serine protease enzyme plays a pivotal role in digestion and is autocatalytic. The crystal structure of a complex formed between porcine trypsin and an auto catalytically produced peptide is reported here. This complex shows a reduction in enzyme activity as compared to native β-trypsin. The nonapeptide has a lysine, which is recognized by Asp 189 at the specificity pocket. The auto catalytically produced native nonapeptide is bound at the active site cleft like other trypsin inhibitors but the important interactions with the oxyanion hole are absent. The peptide covers only a part of the active site cleft and hence the enzyme activity is reduced rather than being inhibited.     

Biometric analysis of Nummulites bahariyaensisn. sp. (Nummulites partschi group) from the Bartonian of Bahariya Oasis,Egypt

Nummulites bahariyaensisn. sp., typical of Nummulites partschi group, Nummulites gizehensis subgroup, is biometrically studied, described and photographed through both generations from El-Hamra Formation, Garra El Hamra, northern plateau of Bahariya Oasis, Western Desert of Egypt. From the biometric analysis, N. bahariyaensis is phylogenetically parallel to Nummulites lyelli, both of Bartonian age based on the presence of Nummulites decrouezae and Nummulites aff. pulchellus which were dated as Bartonian from Gebel Mokattam, the species which is equated with those from Naalon stratigraphic section, Fayum, by Morsi et al. (2003). Nummulites bahariyaensis could be compared with Nummulites champollioni as both are thick in the microspheric generation. However, the phylogeny of the present new species should be searched on. The described species spans SBZ 17 of the Shallow Benthic Zones of Serra-Kiel et al. (1998, Bull Soc Geol France 169(2):281–299), which denotes an Early Bartonian ( = Biarritzian sensu Hottinger and Schaub 1960, Eclogae Geol Helv 53: 453–479). At Garra El Hamra, El-Hamra Formation with N. bahariyaensis unconformably overlies the Qazzun Formation (Late Ypresian) emphasising that the Lutetian and the top part of Ypresian possibly are missing.http://zoobank.org/22549148-0BD6-4097-A22C-01CA614B5CE1     

New Middle Eocene Nummulites from Kait Bey,Gebel Mokattam,Egypt

Nummulites paucispira and Nummulites kaitbeyi are newly erected from the Upper Building Stone Member (Bartonian) of the Mokattam Formation at Kait Bey, Gebel Mokattam, Greater Cairo, Egypt both belong to Nummulites partschi group. N. paucispira and N. kaitbeyi are different in their ontogenetic growth stages; N. paucispira has a step of coiling from tight to lax, contrary to N. kaitbeyi. The regression line of both species indicates that both are distinct and they belong to different lineages. Detailed investigations of the new species N. paucispira n. sp. and N. kaitbeyi n. sp. of N. partschi group and their ontogenetic growth stages are discussed. This study is of considerable importance for distinguishing paleoecological events of Bartonian stage and for tracing the phylogenetic trends for the entire Tethys basin.     

What is Nummulites depressus Kenawy 1978? Evolution of Nummulites fabianii group in the Middle Eocene of Egypt

New species Nummulites vetustufabianiin. sp. is described from the El Hamra Formation, Gara El Hamra section Bahariya Oasis Western Desert. The biometrical measurements include maximum and minimum diameter of the successive radii and heights of whorls, length/height ratio, number of chambers and the marginal cord thickness of each whorl for the megalospheric generation as well as the diameter of proloculus were elaborated to differentiate between some allied granulated species such as Nummulites depressus, Nummulites decrouezae, Nummulites cuvillieri and N. vetustufabianiin. sp.Nummulites fabianii group has lateral distribution for the entire Tethys basin, hence such biometrical studies are needed to emphasise the polyphyletic nature of the group.     

Fixed and Random Effects Selection in Mixed Effects Models

Summary We consider selecting both fixed and random effects in a general class of mixed effects models using maximum penalized likelihood (MPL) estimation along with the smoothly clipped absolute deviation (SCAD) and adaptive least absolute shrinkage and selection operator (ALASSO) penalty functions. The MPL estimates are shown to possess consistency and sparsity properties and asymptotic normality. A model selection criterion, called the IC_Q statistic, is proposed for selecting the penalty parameters ( Ibrahim, Zhu, and Tang, 2008 , Journal of the American Statistical Association 103, 1648–1658). The variable selection procedure based on IC_Q is shown to consistently select important fixed and random effects. The methodology is very general and can be applied to numerous situations involving random effects, including generalized linear mixed models. Simulation studies and a real data set from a Yale infant growth study are used to illustrate the proposed methodology.     

Antimicrobial Activity of Two Novel Venoms from Saudi Arabian Scorpions (Leiurus quinquestriatus and Androctonus crassicauda)

International Journal of Peptide Research and Therapeutics - Many recent studies have shown the benefits of scorpion venom, as it components may be used as potential candidates for drug...     

Impact of diet and genes on murine autoimmune pancreatitis

The impact of environmental factors, such as diet, and the genetic basis of autoimmune pancreatitis (AIP) are largely unknown. Here, we used an experimental murine AIP model to identify the contribution of diet to AIP development, as well as to fine‐map AIP‐associated genes in outbred mice prone to develop the disease. For this purpose, we fed mice of an autoimmune‐prone intercross line (AIL) three different diets (control, calorie‐reduced and western diet) for 6 months, at which point the mice were genotyped and phenotyped for AIP. Overall, 269 out of 734 mice (36.6%) developed AIP with signs of parenchymal destruction, equally affecting mice of both sexes. AIP prevalence and severity were reduced by approximately 50% in mice held under caloric restriction compared to those fed control or western diet. We identified a quantitative trait locus (QTL) on chromosome 4 to be associated with AIP, which is located within a previously reported QTL. This association does not change when considering diet or sex as an additional variable for the mapping. Using whole‐genome sequences of the AIL founder strains, we resolved this QTL to a single candidate gene, namely Map3k7. Expression of Map3k7 was largely restricted to islet cells as well as lymphocytes found in the exocrine pancreas of mice with AIP. Our studies suggest a major impact of diet on AIP. Furthermore, we identify Map3k7 as a novel susceptibility gene for experimental AIP. Both findings warrant clinical translation.