Overlap of temporal niches among four sympatric species of shrews

Hypotheses about the dependence of circadian activity from metabolic rate and the segregation of temporal niches among competing species were verified by the study of activity patterns in a shrew community of two semiaquatic species,Neomys anomalus Cabrera, 1907 andN. fodiens (Pennant, 1771), and two terrestrial species,Sorex araneus Linnaeus, 1758 andS. minutus Linnaeus, 1766, co-existing in wet habitats of Białowieża Forest (E Poland). In ten trapping sessions, performed in early summer between 1991 and 2000, traps were open 24 hours continuously and patrolled at 1:00, 5:00, 10:00, 15:00, and 20:00. All the shrew species were most active between 20:00 and 1:00, and least active around mid-day (10:00–15:00). However, activity of the twoSorex species was lower than that of the twoNeomys species in the period 20:00–1:00, but higher in the period 15:00–20:00. BothNeomys species displayed clearly nocturnal, unimodal patterns of activity. In contrast, activity of bothSorex species was relatively evenly distributed over 24 hours and they increased their activity earlier (ie after 15:00) than bothNeomys species (after 20:00). These results confirm the idea that small shrew species with higher metabolic rate have more frequent and more equally distributed activity bouts than large species. Overlap of temporal niches was the highest within genera (99.29% between bothNeomys species and 98.36% between bothSorex species), the lowest betweenN. fodiens andS. araneus (88.26%) andS. minutus (89.34%), and intermediate betweenN. anomalus and bothSorex species (91.78 and 93.34%, respectively). Such high interspecific overlaps in activity suggest a joint-action of other mechanisms that separate ecological niches of these species also in other dimensions (eg food, microhabitat).     

Evidence for shallow‐water ‘Upper Kellwasser’ anoxia in the Frasnian–Famennian reefs of Alberta,Canada

The Frasnian–Famennian extinction witnessed the global devastation of both level‐bottom and reef communities in low latitudes. Marine extinctions in offshore level‐bottom communities are associated with two widespread, transgressive, anoxic ‘Kellwasser Events’ that support an anoxia–extinction link. Typical Kellwasser facies of bituminous limestones and shales are not obviously recorded in shallow‐water settings, and thus, it is unclear whether anoxia played a role in reef losses. We evaluate geochemical, petrographic and facies evidence for oxygen restriction from an extremely shallow‐water carbonate platform in Alberta. Sequence stratigraphy places the Frasnian–Famennian boundary at a sequence boundary that tops a laminated mudstone and interrupts carbonate platform deposition. Two transgressive pulses have been identified, one of which is associated with the second, major transgression of T‐R cycle IId of the Devonian eustatic sea‐level curve. Geochemical proxies indicate that these transgressions were accompanied by influx of dysoxic or anoxic waters. Organic carbon and U enrichment in the Frasnian, particularly just below the Frasnian–Famennian boundary, points to episodic dysoxic conditions that probably persisted into the basal Famennian and were coincidental with the global Upper Kellwasser Event. This study provides the first evidence for the smoking gun of an anoxia‐driven extinction in very shallow waters, implicating this potent killer in the demise of the Devonian reefs.     

Hydrophobic core formation in protein complex of cathepsin

The “fuzzy oil drop” model assumes that the idealized hydrophobic core in a protein body can be described by a 3D Gauss function. The structure of the 1ICF protein (cathepsin), which participates in the proteolysis process and has cysteine-type peptidase activity, has been analyzed on the basis of the “fuzzy oil drop” model. The authors have determined the contribution of individual exon fragments to the creation of a common hydrophobic core and assessed the involvement of each chain in this process, depending on the number of complexed chains. Quantitative assessment of exons, chains, dimers, and the whole complex suggest that each of these units plays a different role in shaping the protein’s hydrophobic core.     

Application of IGF2-specific identifier probe for cytogenetic study of somatic and sperm cells in horses

The development of molecular techniques with fluorochromes has had an invaluable impact on discovering the nature of chromatin structure. Here, we show the application of a locus specific identifier probe (LSI) for precise and selective visualization of the horse IGF2 gene in the metaphase, interphase nuclei and sperm cells. Our study may be helpful for interpretation of results of interphase fluorescence in situ hybridization (I-FISH). We analyze and discuss the variation in the number and localization of FISH signals in somatic and sperm cells of horse.     

Study on genetic diversity of genes encoding main adhesins among nontypeable Haemophilus influenzae strains isolated from children in Poland

The study was based on hypothesis that in the nontypeable population of H. influenzae strains isolated from children there are some genetically predisposed to induce symptomatic infection in children and that they might be divided into different groups depending on profiles of genes encoding main adhesins synthesis. The work aimed at analysis of distribution of genes encoding adhesins and evaluation of domination possibility of some strains representing particular adhesins genes profiles among NTHi population. Results of the study revealed that among population of NTHi strains, distribution of genes encoding main adhesins are differing. Among children, NTHi strains harbouring genes encoding HA and HMW1/HMW2 adhesins were more prevalent in healthy children and in children with symptomatic infections, respectively. Analysis of strains harbouring main adhesins profiles might be a useful screening method in monitoring strains circulating among children, in order to determine the most invasive NTHi strains.     

Synthesis of New Chiral Peptide Nucleic Acid (PNA) Monomers by a Simplified Reductive Animation Method

Abstract

The aim of this work was the preparation of four new peptide nucleic acid (PNA) monomer backbone by reductive animation of N^α-Boc-protected chiral amino aldehydes, derived from Leu, Phe, Tyr(Bzl), and Thr(Bzl), with methyl glycinate. To the crude 2-substituted methyl N-(2-Boc-aminoethyl)glycinates obtained, thymin-1-ylacetic acid was coupled using TBTU procedure in a one-pot reaction. PNA monomers were isolated and characterized.     

Role of NO and COX pathways in mediation of adenosine A1 receptor-induced renal vasoconstriction

The mechanism of adenosine A1 receptor-induced intrarenal vasoconstriction is unclear; it depends on sodium intake and may be mediated by changing the intrarenal activity of the nitric oxide (NO) and/or cyclooxygenase (COX) pathway of arachidonic acid metabolism. The effects of 2-chloro-N(6)-cyclopentyl-adenosine (CCPA), a selective A1 receptor agonist, on renal hemodynamics were examined in anesthetized rats maintained on high sodium (HS) or low sodium (LS) diet. Total renal (i.e., cortical) blood flow (RBF) as well as superficial cortical (CBF), outer medullary (OMBF), and inner medullary (IMBF) flows were determined by laser-Doppler. In HS rats, suprarenal aortic infusions of 8-40 nmol/kg/hr CCPA decreased IMBF (15%) and other perfusion indices (22%-27%); in LS rats, IMBF increased 3% (insignificant) and other indices decreased 13%-24%. In LS rats, pretreatment with N-nitro-L-arginine methyl ester prevented the A1 receptor-mediated decrease in RBF and CBF but not OMBF; the response in IMBF was not altered. Pretreatment with indomethacin prevented the decreases in RBF, CBF, and OMBF and did not change the response of IMBF. Thus, within the cortex the vasoconstriction that follows A1 receptor activation results both from inhibition of NO synthesis and from stimulation of vasoconstrictor products of the COX pathway. In the outer medulla, the latter products seem exclusively responsible for CCPA-induced vasoconstriction. The observation that in LS rats IMBF was not affected by stimulation of adenosine A1 receptors suggests that limiting salt intake may help protect medullary perfusion against vasoconstrictor stimuli which have the potential to disturb long-term control of arterial pressure.