Znaleziono wyników: 3

Liczba wyników na stronie

Wyniki wyszukiwania

Sortuj według:

Ogranicz wyniki do:

Artykuł dostępny w postaci pełnego tekstu - kliknij by otworzyć plik

Temporal dynamics of the geographic differentiation of Late Devonian Palmatolepis assemblages in the Prototethys

100%

Girard C., Ta H. P., Savage N., Renaud S.

Acta Palaeontologica Polonica

2010

tom 55

nr 4

Throughout their history, species had to face environmental variations spatially and temporally. How both levels of variation interact will be of key importance in conditioning their response to major perturbations. We addressed this question by focusing on a period in Earth’s history marked by dramatic environmental and faunal changes, the Late Devonian Frasnian/Famennian boundary. From a paleogeographic point of view, this period is characterized by a cosmopolitanism of the faunas across a large ocean, the Prototethys. We considered the biotic reaction at a seldom considered scale, namely within a single subgenus of conodont, Palmatolepis (Manticolepis). Patterns of spatial and temporal differentiation were quantified using morphometrics of its platform element. The recognized cosmopolitanism of the faunas was confirmed at this scale of variation since temporal records gathered in distant areas around the Prototethys, including the seldom documented regions located nowadays in South−East Asia, displayed similar morphological trends in response to the major F/F crisis. Beyond this overall cosmopolitanism, subtle geographic structure was evidenced but was not stable through time. Geographic differentiation was maximal shortly before the F/F crisis, suggesting that despite high sea−level, tectonics leaded to complex submarine landscapes promoting differentiation. In contrast any geographic structure was swamped out after the crisis, possibly due to a global recolonization from few favorable patches.

Flow cytometric assessment of the antimicrobial properties of an essential oil mixture against Escherichia coli

100%

Girard C., Fayolle K., Kerros S., Leriche F.

Journal of Animal and Feed Sciences

2019

tom 28

nr 2

Essential oils are increasingly being used in human health and animal farming as alternatives to antibiotics. The aim of this study was to better understand the mode of antimicrobial action of a natural essential oil mix (EO mix) by comparison with the colistin, as an antibiotic. The growth inhibitory concentration (GIC) of the EO mix and colistin was determined by turbidimetry. Escherichia coli exposed to EO mix and colistin were analysed by flow cytometry using the fluorescent dyes 3,3-diethyloxacarbocyanine iodide(DiOC2 (3)) to assess membrane potential, and propidium iodide (PI) and SYTO9 to assess membrane integrity following treatment at the GIC and ½-GIC of the EO mix every h for 4 h. At 1 h, treatment with EO mix and colistin resulted in significant cell membrane alteration and depolarization. Membrane integrity measurements identified four sub-populations that were not distributed in the same way between EO mix and antibiotic treated cells. Colistin at GIC and ½-GIC drastically disintegrated the cells that appeared as debris (69.8% of cells were lysed after 1 h of treatment) whereas the EO mix at GIC altered membrane of a majority of cells (67.4 ± 1.3% of cells were partially altered). Contact with ½-GIC EO mix led to sub-populations that persisted or recovered a physiological state with intact membrane (from 1 h to 4 h of treatment, intact cells increased from 23 to 33%). So, it was demonstrated that the EO mix presented antibacterial action against E. coli. It altered membrane properties by decreasing its polarity and integrity which were reversible phenomena here.

Effect of urea supplementation on urea kinetics and splanchinic flux of amino acids in dairy cows

76%

Lapierre H., Ouellet D. R., Berthiaume R., Girard C., Dubreuil P., Babkine M., Lobley G. E.

Journal of Animal and Feed Sciences. Supplement

2004

tom 13

nr 1

Ograniczanie wyników

1 Acta Palaeontologica Polonica

1 Journal of Animal and Feed Sciences

1 Journal of Animal and Feed Sciences. Supplement

3 Girard C.

1 Babkine M.

1 Berthiaume R.

1 Dubreuil P.

1 Fayolle K.

1 Kerros S.

1 Lapierre H.

1 Leriche F.

1 Lobley G. E.

1 Ouellet D. R.

1 Renaud S.

1 Savage N.

1 Ta H. P.

1 2019

1 2010

1 2004

Wyniki wyszukiwania

Temporal dynamics of the geographic differentiation of Late Devonian Palmatolepis assemblages in the Prototethys

Flow cytometric assessment of the antimicrobial properties of an essential oil mixture against Escherichia coli

Effect of urea supplementation on urea kinetics and splanchinic flux of amino acids in dairy cows