Mass spectrometry studies of the fragmentation patterns and mechanisms of protonated peptoids

Peptoids belong to a class of sequence-controlled polymers comprising of N-alkylglycine. This study focuses on using tandem mass spectrometry techniques to characterize the fragmentation patterns of a set of singly and doubly protonated peptoids consisting of one basic residue placed at different positions. The singly protonated peptoids fragment by producing predominately high-abundant C-terminal ions called Y-ions and low-abundant N-terminal ions called B-ions. Computational studies suggest that the proton affinity (PA) of the C-terminal fragments is generally higher than that of the N-terminal fragments, and the PA of the former increases as the fragments are elongated. The B-ions are likely formed upon dissociating the proton-activated amide bonds via an oxazolone structure, and the Y-ions are produced subsequently by abstracting a proton from the newly formed B-ions, which is energetically favored. The doubly protonated peptoids prefer to fragment closest to either the N- or the C-terminus and produce corresponding B/Y-ion pairs. The basic residue seems to dictate the preferred fragmentation site, which may be the result of minimizing the repulsion between the two charges. Water and terminal neutral losses are a facile process accompanying the peptoid fragmentation in both charge states. The patterns appear to be highly influenced by the location of the basic residue.     

Amphibians and squamates from the middle Eocene of Namibia,with comments on pre-Miocene anurans from Africa

Three middle Eocene localities (Silica North, Silica South, Black Crow) recently discovered in Namibia have produced terrestrial faunas that rank among the few known from the period of insulation of Africa (Aptian-early Miocene). Collectively, the three localities have yielded anuran amphibians (one pipid frog, the earliest assemblage [three taxa] of ranoid frogs in Africa, one indeterminate family) and squamate reptiles (an amphisbaenian ‘lizard’, a snake that likely represents a colubroid, and two indeterminate ‘lizards’). These Eocene faunas suggest that ranoids, colubroids and African pipids are autochthonous to Africa. However, whereas pipids are vicariants inherited from West Gondwana, ranoids and colubroids (if really autochthonous) originated in Africa from unknown stems. Silica North and Silica South correspond to aquatic environments, permanent fresh water being present in the first locality; the environment of Black Crow was drier.     

Biotyping,virulotyping and biofilm formation ability of ESBL-Klebsiella pneumoniae isolates from nosocomial infections

The aim of this study was to investigate the frequency, molecular characterization, virulence genes, resistance genes and antimicrobial profile of nosocomial extended spectrum beta lactamase producing Klebsiella species. A total of 22 (12.2%) K. pneumoniae strains were isolated from 180 clinical samples collected from hospitalized patients in Egypt. K. pneumoniae biotypes were B1 (72.8%), B3 (13.6%) and B4 (13.6%). The isolates were classified for the capsular serotypes, 86.4% (20/22) were of K1 serotype, while only two isolates (13.64%) were of K2 serotype. Hypermucoviscous K. pneumoniae isolates accounted for 68.2%. Biofilm formation ability of K. pneumoniae was determined by microtitre plate method. The majority of the isolates (40.9%) were moderate biofilm producers, while 27.3% were strong biofilm producers. All K. pneumoniae strains were positive for fimH and traT genes, while magA was identified in only 63.6% of the isolates. The antibiotic susceptibility profile of the isolates (n = 22) was determined by the disc diffusion technique using 23 different antibiotics. Streptomycin and imipenem are the most effective antibiotics against 22 tested K. pneumoniae isolates with sensitivity rates of 63.64% and 54.54% respectively. All tested K. pneumoniae isolates showed high resistance to amoxicillin∕clavulanate (100%), cefuroxime (100%) and ceftazidime (95.45%). Extended spectrum beta lactamases (ESBL) production and the presence of ESBL-related genes were tested in the isolates. All the isolates tested positive for blaVIM, NDM1 and blaTEM, while only 81.8 %tested positive for the blaSHV gene. Increasing antimicrobial resistance in K. pneumoniae causing nosocomial infections limits the use of antimicrobial agents for treatment. Furthermore, the spread of biofilm, multiple drug resistant and ESBL-producing K. pneumoniae isolates is a public threat for hospitalized patients.     

Complexing properties of some pyrimidines

The synthesis of transition metal barbiturate, and thiobarbiturate complexes containing different functional groups of variable electronic character with CoII, NiII, CuII, PdII, and PtII have been prepared. The stereochemistry and the mode of bonding of the complexes were determined by elemental analysis and electronic and vibrational spectra together with their magnetic moment values. Electronic spin resonance of copper complexes were recorded. The Racah parameter of some cobalt and nickel complexes were calculated. Some of the complexes are of mixed stereochemistry. All the PdII or PtII complexes are of square planar geometries.     

Amphibians and squamates from the Neogene Siwalik beds of Jammu and Kashmir, India

The Neogene Siwalik deposits of Jammu Province (India) have yielded amphibians and squamates. The collection includes the first amphibians and the first colubroid snakes from the Siwalik Group. Amphibians comprise only anurans: a possible Ranidae and one, or perhaps two, non-ranid frogs Squamates include one lizard,Varanus sp. (Varanidae), whereas snakes are represented by three taxa:Acrochordus dehmi (Acrochordidae), an indeterminate Colubridae, and a snake that is either a Colubridae or an Elapidae.Varanus sp. andA. dehmi have been yielded by the Upper Miocene Ramnagar Member, whereas the anurans and colubroid snakes come from the Upper Pliocene Labli Member. These taxa are indicative of aquatic palaeoenvironment.     

Puycelci, nouveau site à vertébrés de la série molassique d’Aquitaine. Densité et continuité biochronologique dans la zone Quercy et bassins périphériques au Paléogène

After the previous lacking evidence allowed the interpretation of a non-deposition episod, the newly recorded mammal fauna from Puycelci (Tarn, SW France, close South to the Quercy paleokarstic area) now shows the MP 26 standard level (Late Oligocene, Early Chattian) being represented within the Eastern Aquitaine molassic basin filling. According to the evolutionary stage of known mammal lineages, the most significant Puycelci fossils are the Issiodoromys pauffiensis rodent and the Metriotherium cf. sarelense nov. sp. (described in this paper) artiodactyl ungulate. This new dating exemplifies the improvement of the mammalian biochronologic record as regards both the Quercy paleokarst and the surrounding lacustrine Tertiary basins W, S, and S-E to the Quercy, as well as, directly E and N-E, the smaller tectonic Tertiary basins within the crystalline Massif Central basement. The updated record shows the strong extension in time of the paleokarstic data, down to the Middle and Early Eocene, and up to the Early Miocene. Regarding the classically reported Late Eocene to Late Oligocene span, as well in the paleokarst and the peripheral basins, the available biochronological data now attains a valuable density level, the variation of which is significant. On one side there are periods (Late Eocene, Early Oligocene, Early Late Oligocene) with high biochronologic density, allowing improved time resolution using evolutionary stages within mammalian lineages (e.g. numerical ages). Such periods corresponds to almost continuous sedimentary processes, with only possible short breaks. On the other side, there are periods with unreported data, shared in the paleokarst and peripheral basins (Late Oligocene as best example). Such periods may well correspond to some non-deposition episods as once alleged by geologists. Then the surrounding biochronologic data would bear constraining value regarding these episods.     

Kidney cancer mortality and ionizing radiation among French and German uranium miners

The investigation of potential adverse health effects of occupational exposures to ionizing radiation, on uranium miners, is an important area of research. Radon is a well-known carcinogen for lung, but the link between radiation exposure and other diseases remains controversial, particularly for kidney cancer. The aims of this study were therefore to perform external kidney cancer mortality analyses and to assess the relationship between occupational radiation exposure and kidney cancer mortality, using competing risks methodology, from two uranium miners cohorts. The French (n = 3,377) and German (n = 58,986) cohorts of uranium miners included 11 and 174 deaths from kidney cancer. For each cohort, the excess of kidney cancer mortality has been assessed by standardized mortality ratio (SMR) corrected for the probability of known causes of death. The associations between cumulative occupational radiation exposures (radon, external gamma radiation and long-lived radionuclides) or kidney equivalent doses and both the cause-specific hazard and the probability of occurrence of kidney cancer death have been estimated with Cox and Fine and Gray models adjusted to date of birth and considering the attained age as the timescale. No significant excess of kidney cancer mortality has been observed neither in the French cohort (SMR = 1.49, 95 % confidence interval [0.73; 2.67]) nor in the German cohort (SMR = 0.91 [0.77; 1.06]). Moreover, no significant association between kidney cancer mortality and any type of occupational radiation exposure or kidney equivalent dose has been observed. Future analyses based on further follow-up updates and/or large pooled cohorts should allow us to confirm or not the absence of association.     

The Effects of Periphyton, Fish and Fertilizer Dose on Biological Processes Affecting Water Quality in Earthen Fish Ponds

The potential of periphyton-based aquaculture in South Asia is under investigation in an extensive research program. This paper is a further analysis of data from four experiments carried out in that framework, to explore periphyton, fish and fertilizer dose effects on water quality. Factor analysis and ANOVA models applied to a data matrix of water quality parameters in ponds with and without artificial substrates (bamboo poles and kanchi sticks), with and without fish (filter feeders catla and rohu, with and without bottom feeder kalbaush), and with a standard or 50% increased fertilizer dose, allowed us to identify the underlying ecological processes governing this novel periphyton-based pond system, and construct conceptual graphic models of the periphyton–environment relationships observed. We clearly established that the phosphorus flow is mainly linked to phytoplankton activity in the water column and decomposition on the pond bottom, while nitrogen flow is mainly linked to autotrophic (photosynthesis) and heterotrophic (decomposition and nitrification) processes that take place in the periphyton in addition to the water column and pond bottom. Consequently, disruption of the pond bottom by bottom feeding fish primarily promoted phosphate cycling and phytoplankton, while periphyton development on the supplied substrates and fertilization mainly improved oxygen balance and nitrogen related processes developing in the water column. The use of bamboo poles led to better results than kanchi sticks, related to the greater autotrophic periphyton development on bamboo and to the larger surface of bamboo poles that facilitate fish grazing and periphyton dislodgment that in turn have a renewal effect on periphyton. Stocking bottom feeding fish produces a fertilizing effect through the food web that benefits the filter-feeding fish and that makes it unnecessary to increase the dose of inorganic and organic fertilizers applied to the ponds. Thus, the output of this analysis will help the fish farmers in resource constrained countries to improve their production in periphyton-based ponds just by choosing bamboo substrates, stocking a bottom feeder fish together with the filter feeders, and saving money on fertilizers.