À l’hiver 1947-1948, Henri Calet, au même titre que d’autres intellectuels métropolitains comme Michel Leiris ou Francis Ponge, est invité à Sidi Madani, au sud d’Alger, afin de débattre de questions ...politiques et culturelles propres à l’Algérie. Cette invitation est aussi pour chacun l’occasion de jouir d’excellentes conditions matérielles pour mener à bien ses propres travaux. L’escapade algérienne de Calet se prolonge par un voyage au Maroc, à caractère plus privé. Au cours de ce séjour, Calet prend des notes, écrit ses impressions, rend compte de ce qu’il voit. Réunis ici, les textes nord-africains de Calet, même sous leur aspect inachevé, sont représentatifs au premier chef de son style, de son humour, de sa faculté aiguë d’observation et, plus encore peut-être, de son inclination, qui sera de plus en plus forte au fil des années, à la notation brève et à l’écriture impressionniste.
This study investigated the involvement of glutamate-, arginine- and lysine-dependent systems in the Acid Tolerance Response (ATR) of
Bacillus cereus ATCC14579 strain. Cells were grown in a chemostat ...at external pH (pH
e) 7.0 and 5.5. Population reduction after acid shock at pH 4.0 was strongly limited in cells grown at pH 5.5 (acid-adapted) compared with cells grown at pH 7.0 (unadapted), indicating that
B. cereus cells grown at low pH
e were able to induce a marked ATR. Glutamate, arginine and lysine enhanced the resistance of unadapted cells to pH 4.0 acid shock of 1-log or 2-log populations, respectively. Amino acids had no detectable effect on acid resistance in acid-adapted cells. An acid shock at pH 4.0 resulted in a marked drop in internal pH (pH
i) in unadapted cells compared with acid-adapted cells. When acid shock was achieved in the presence of glutamate, arginine or lysine, pH
i was maintained at higher values (6.31, 6.69 or 6.99, respectively) compared with pH
i in the absence of amino acids (4.88). Acid-adapted cells maintained their pH
i at around 6.4 whatever the condition. Agmatine (a competitive inhibitor of arginine decarboxylase) had a negative effect on the ability of
B.
cereus cells to survive and maintain their pH
i during acid shock. Our data demonstrate that
B. cereus is able to induce an ATR during growth at low pH. This adaptation depends on pH
i homeostasis and is enhanced in the presence of glutamate, arginine and lysine. Hence evaluations of the pathogenicity of
B. cereus must take into account its ability to adapt to acid stress.
Schmitt Michel P. Au service des forces françaises libres. Agrippa d’Aubigné (1937-1953). In: Albineana, Cahiers d'Aubigné, 28, 2016. La fabrique du grand homme. pp. 127-138.
Tuberculosis (TB) still is the principal cause of death from infectious disease and improved vaccination strategies are required to reduce the disease burden and break TB transmission. Here, we ...investigated different routes of administration of vectored subunit vaccines based on chimpanzee-derived adenovirus serotype-3 (ChAd3) for homologous prime-boosting and modified vaccinia virus Ankara (MVA) for heterologous boosting with both vaccine vectors expressing the same antigens from
(Ag85B, ESAT6, Rv2626, Rv1733, RpfD). Prime-boost strategies were evaluated for immunogenicity and protective efficacy in highly susceptible rhesus macaques. A fully parenteral administration regimen was compared to exclusive respiratory mucosal administration, while parenteral ChAd3-5Ag prime-boosting and mucosal MVA-5Ag boosting were applied as a push-and-pull strategy from the periphery to the lung. Immune analyses corroborated compartmentalized responses induced by parenteral versus mucosal vaccination. Despite eliciting TB-specific immune responses, none of the investigational regimes conferred a protective effect by standard readouts of TB compared to non-vaccinated controls, while lack of protection by BCG underpinned the stringency of this non-human primate test modality. Yet, TB manifestation after full parenteral vaccination was significantly less compared to exclusive mucosal vaccination.
In the fall of 1947, the Algerian Service for Youth Movements and Popular Education invited metropolitan artists and writers to Sidi Madani near Blida for cultural meetings. The announced program ...allowed the guests plenty of free time to continue their personal work. Henri Calet and Francis Ponge seized the opportunity, the former to complete his narrative "Le Tout sur le tout" (published in 1948), and the latter to delve deeper into a literary theory he had been developing for some time. At the same time, both men took notes on what they saw in Algeria. In a volume titled "Mes impressions d’Afrique," we have collected Calet's unpublished notes (PUL, 2019). Ponge, on the other hand, wrote "My Creative Method," "Pochades en Prose," and "Le Porte-Plume d’Alger," three texts published in Volume I of his Complete Works (Bibliothèque de la Pléiade, NRF, Gallimard, 1999). The article presents these meetings in Sidi-Madani and questions the colonial stereotypes that influenced the perception of the two writers. It then compares two writings on the same subject, leading to the ethical and political stance of the two men as culturally foreign individuals in a country that, at that moment in history, was French.
RÉSUMÉ : À l’automne 1947, le Service algérien des Mouvements de Jeunesse et d’Éducation populaire invita à Sidi Madani près de Blida, des artistes et écrivains métropolitains pour participer à des rencontres culturelles. Le programme annoncé laissait aux invités beaucoup de temps libre pour poursuivre leurs travaux personnels. Henri Calet et Francis Ponge se saisirent de l’occasion, le premier pour achever son récit Le Tout sur le tout (publié en 1948) ; le second pour approfondir une théorie littéraire amorcée depuis longtemps. En même temps, les deux hommes prirent des notes sur ce qui leur était donné à voir en Algérie. Dans un volume intitulé Mes impressions d’Afrique, nous avons rassemblé les notes inédites de Calet (PUL, 2019). Ponge quant à lui rédigea « My creativ method », « Pochades en prose » et « Le Porte-plume d’Alger », trois textes publiés dans le volume I de ses Œuvres complètes (Bibliothèque de la Pléiade, NRF, Gallimard, 1999). L’article présente ces rencontres de Sidi-Madani et s’interroge sur les clichés coloniaux qui orientent la perception des deux écrivains. Puis il compare deux écritures autour d’un même sujet, pour déboucher sur la position éthique et politique des deux hommes, en situation objective d’étrangers culturels en un pays qui, à ce moment de l’histoire, était français.
This study examined the involvement of ATPase activity in the acid tolerance response (ATR) of Bacillus cereus ATCC14579 strain. In the current work, B. cereus cells were grown in anaerobic chemostat ...culture at external pH (pHe) 7.0 or 5.5 and at a growth rate of 0.2 h−1. Population reduction and internal pH (pHi) after acid shock at pH 4.0 was examined either with or without ATPase inhibitor N,N’‐dicyclohexylcarbodiimide (DCCD) and ionophores valinomycin and nigericin. Population reduction after acid shock at pH 4.0 was strongly limited in cells grown at pH 5.5 (acid‐adapted cells) compared with cells grown at pH 7.0 (unadapted cells), indicating that B. cereus cells grown at low pHe were able to induce a significant ATR and Exercise‐induced increase in ATPase activity. However, DCCD and ionophores had a negative effect on the ability of B. cereus cells to survive and maintain their pHi during acid shock. When acid shock was achieved after DCCD treatment, pHi was markedly dropped in unadapted and acid‐adapted cells. The ATPase activity was also significantly inhibited by DCCD and ionophores in acid‐adapted cells. Furthermore, transcriptional analysis revealed that atpB (ATP beta chain) transcripts was increased in acid‐adapted cells compared to unadapted cells before and after acid shock. Our data demonstrate that B. cereus is able to induce an ATR during growth at low pH. These adaptations depend on the ATPase activity induction and pHi homeostasis. Our data demonstrate that the ATPase enzyme can be implicated in the cytoplasmic pH regulation and in acid tolerance of B. cereus acid‐adapted cells.
Bacillus cereus is able to induce acid tolerance response. ATPase activity is induced and activated in cells grown at low pH. Internal pH was maintained in cells grown at low pH.
The food pathogen Bacillus cereus is likely to encounter acidic environments (i) in food when organic acids are added for preservation purposes, and (ii) during the stomachal transit of aliments. In ...order to characterise the acid stress response of B. cereus ATCC14579, cells were grown in chemostat at different pH values (pHo from 9.0 to 5.5) and different growth rates (μ from 0.1 to 0.8 h-¹), and were submitted to acid shock at pH 4.0. Cells grown at low pHo were adapted to acid media and induced a significant acid tolerance response (ATR). The ATR induced was modulated by both pHo and μ, and the μ effect was more marked at pHo 5.5. Intracellular pH (pHi) was affected by both pHo and μ. At a pHo above 6, the pHi decreased with the decrease of pHo and the increase of μ. At pHo 5.5, pHi was higher compared to pHo 6.0, suggesting that mechanisms of pHi homeostasis were induced. The acid survival of B. cereus required protein neo-synthesis and the capacity of cells to maintain their pHi and ΔpH (pHi - pHo). Haemolysin BL and non-haemolytic enterotoxin production were both influenced by pHo and μ.
Abstract
This study examined the involvement of
ATP
ase activity in the acid tolerance response (
ATR
) of
Bacillus cereus
ATCC
14579 strain. In the current work,
B. cereus
cells were grown in ...anaerobic chemostat culture at external
pH
(
pH
e
) 7.0 or 5.5 and at a growth rate of 0.2 h
−1
. Population reduction and internal
pH
(
pH
i
) after acid shock at
pH
4.0 was examined either with or without
ATP
ase inhibitor
N,N’
‐dicyclohexylcarbodiimide (
DCCD
) and ionophores valinomycin and nigericin. Population reduction after acid shock at
pH
4.0 was strongly limited in cells grown at
pH
5.5 (acid‐adapted cells) compared with cells grown at
pH
7.0 (unadapted cells), indicating that
B. cereus
cells grown at low
pH
e
were able to induce a significant
ATR
and Exercise‐induced increase in
ATP
ase activity. However,
DCCD
and ionophores had a negative effect on the ability of
B
.
cereus
cells to survive and maintain their
pH
i
during acid shock. When acid shock was achieved after
DCCD
treatment,
pH
i
was markedly dropped in unadapted and acid‐adapted cells. The
ATP
ase activity was also significantly inhibited by
DCCD
and ionophores in acid‐adapted cells. Furthermore, transcriptional analysis revealed that
atpB
(
ATP
beta chain) transcripts was increased in acid‐adapted cells compared to unadapted cells before and after acid shock. Our data demonstrate that
B. cereus
is able to induce an
ATR
during growth at low
pH
. These adaptations depend on the
ATP
ase activity induction and
pH
i
homeostasis. Our data demonstrate that the
ATP
ase enzyme can be implicated in the cytoplasmic
pH
regulation and in acid tolerance of
B. cereus
acid‐adapted cells.
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