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CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico FAPESP - Fundação de Amparo à Pesquisa do Estado de São Paulo Alkalization is a step of cocoa processing and consists of the use of alkali and high temperature to improve the sensorial and technological qualities of cocoa. Intense food processing can select spores, which can compromise safety and quality of the final product. Thus, the aim of this study was to evaluate the fate of B. cereus and G. stearothermophilus spores during the alkalization of pre-roasted (Pr) nibs (held at 120 °C) and unroasted (Ur) nibs (held at 90 °C) using potassium carbonate (0, 2, 4 and 6% w/w). In all conditions, log-linear inactivation kinetics with a tail was observed. The inactivation rate (kmax) for B. cereus varied from 0.065 to 1.67 min−1, whereas the kmax for G. stearothermophilus varied from 0.012 to 0.063 min−1. For both microorganisms, the lowest kmax values were observed during Ur nibs alkalization. The carbonate concentration increase promoted kmax values reduction. The highest tail values were observed for G. stearothermophilus in Ur nibs alkalization, reaching 3.04 log spores/g. Tail formation and low kmax values indicated that cocoa alkalization does not cause significant reductions on bacterial spore population. Therefore, the microbiological control should be primarily ensured by the raw material quality and by avoiding recontamination in the cocoa

Summary RhoA-mediated regulation of myosin-II activity in the actin cortex controls the ability of cells to contract and bleb during a variety of cellular processes, including cell migration and division. Cell contraction and blebbing also frequently occur as part of the cytopathic effect seen during many different viral infections. We now demonstrate that the vaccinia virus protein F11, which localizes to the plasma membrane, is required for ROCK-mediated cell contraction from 2 hr post infection. Curiously, F11-induced cell contraction is dependent on RhoC and not RhoA signaling to ROCK. Moreover, RhoC-driven cell contraction depends on the upstream inhibition of RhoD signaling by F11. This inhibition prevents RhoD from regulating its downstream effector Pak6, alleviating the suppression of RhoC by the kinase. Our observations with vaccinia have now demonstrated that RhoD recruits Pak6 to the plasma membrane to antagonize RhoC signaling during cell contraction and blebbing., Graphical Abstract, Highlights • Vaccinia F11 protein is required for virus-induced cell contraction and blebbing • F11-induced cell contraction depends on RhoC, but not RhoA, signaling to ROCK • RhoD recruits Pak6 to the plasma membrane to antagonize RhoC signaling • F11 inhibits RhoD signaling to its downstream effector Pak6, Many different viral infections induce cell contraction and blebbing. Durkin, Leite, et al. show that during vaccinia infection, RhoC and not RhoA regulates this ROCK-mediated cytopathic effect of cell contraction. They delineate a pathway for RhoC regulation, in which the viral protein F11 blocks RhoC antagonism by RhoD-recruited Pak6.

アフリカツメガエル初期胚(stage15-24)の尾部予定材料の細胞群を切り出して外植実験を行った。stage20-24の胚において,肛門部を含まない尾部予定域の細胞群を培養した場合,正常幼生の尾とは異なる形態の尾片が発生してきた。しかしstage15-19の胚においては原口周辺部,stage20-24の胚においては肛門部を含んで切り出した尾部予定域の細胞群からは正常幼生に見られるような背鰭および腹鰭のよく発達した尾片が発生してきた。またそれらの尾片においては肛門の分化も明らかに認められた。今後は外植された尾部予定域の細胞群から生じた尾片が正常幼生の尾部と同様に変態ホルモンであるチロキシンに応答して退化するか否かを調べる予定である。, We carried out the explantation experiment that isolated the cells of the presumptive tail region from the early stage (stages 15-24) Xenopus embryos and then cultured them. When we cultured the cells of the presumptive tail region excluding the presumptive anus region, they developed into the different shaped tail fragments from the tail region of the normal larvae. However, the cells in the vicinity of the blastopore from stages 15-19 embryos developed into the tail fragments accompanied by dorsal and ventral fins and the anus. Also, the cells of the presumptive tail region including the presumptive anus region for stages 20-24 embryos showed the same tendencies. We are planning to test whether or not the tail fragments derived from the presumptive tail region reply to the thyroid hormones as do the cells of the tail region of the normal larvae.

将来アフリカツメガエル幼生の尾部を構成する細胞群と頭部および胴部を構成する細胞群が初期発生のどの段階で区画されるかを明らかにする目的で,(1)正常発生における尾の形成過程を観察し,(2)原腸胚期から神経板期における尾の予定域を明らかにした。(2)に基ずいて(3)原腸胚期および神経板期の胚から尾の予定域を除去し,除去の影響が顕著に認められる発生段階を検討した。その結果,尾の予定域は原腸胚期では原口腹唇,後には卵黄栓の周辺に位置すること,また尾を構成する細胞群が原腸胚後期に決定されつつあることが示唆された。なおアフリカツメガエル幼生の尾部形成の初期においては,他の種では認められない特別の構造物が存在することが明らかとなった。その構造物は,細胞構成および形成部域から推測してニワトリ胚対外膜の一種の尿嚢と相同の器官ではないかと考える。, We are interested in when the cells constituting the tail region of Xenopus larva that degenerate during metamorphosis are discriminated from the cells constituting the head and the trunk regions. Therefore, we started to observe the normal development process of the tail region in Xenopus embryos. During the tail bud stages, the characteristic structure, which were not recognized in the other species of anuran, was observed on the ventral side of tail gut region of the Xenopus larvae and it was composed endodermal- and mesodermal cells. We postulated that the structure is similar to the allantoic anlage of chick embryo. After examining the fate map of tail region in 10 1/2-14 stages embryos, we carried out the experiments that removed the cells of the presumptive tail region from the embryos. These results suggest that the cells of the tail region are discriminated from the cells forming the head and the trunk regions during the slit-blastopore stage (stage13).

Listeria monocytogenes (Lm) is a ubiquitous bacterium able to survive and thrive within the environment and readily colonizes a wide range of substrates, often as a biofilm. It is also a facultative intracellular pathogen, which actively invades diverse hosts and induces listeriosis. So far, these two complementary facets of Lm biology have been studied independently. Here we demonstrate that the major Lm virulence determinant ActA, a PrfA-regulated gene product enabling actin polymerization and thereby promoting its intracellular motility and cell-to-cell spread, is critical for bacterial aggregation and biofilm formation. We show that ActA mediates Lm aggregation via direct ActA-ActA interactions and that the ActA C-terminal region, which is not involved in actin polymerization, is essential for aggregation in vitro. In mice permissive to orally-acquired listeriosis, ActA-mediated Lm aggregation is not observed in infected tissues but occurs in the gut lumen. Strikingly, ActA-dependent aggregating bacteria exhibit an increased ability to persist within the cecum and colon lumen of mice, and are shed in the feces three order of magnitude more efficiently and for twice as long than bacteria unable to aggregate. In conclusion, this study identifies a novel function for ActA and illustrates that in addition to contributing to its dissemination within the host, ActA plays a key role in Lm persistence within the host and in transmission from the host back to the environment., Author Summary Listeria monocytogenes (Lm) is a ubiquitous bacterium that survives and thrives within the environment, and a facultative intracellular pathogen that induces listeriosis. So far, these two complementary facets of Lm biology have been studied independently. Here we identify ActA, which is a major Lm virulence determinant mediating actin-based motility, as critical for bacterial aggregation and biofilm formation. ActA promotes Lm aggregation via direct ActA-ActA interaction and ActA C-terminal region, which is not involved in actin polymerization, is essential for aggregation. Whereas ActA-mediated Lm aggregation is not observed in infected tissues, it occurs in the gut lumen. Strikingly, ActA-dependent aggregating bacteria exhibit an increased ability to persist within the gut lumen, and are shed in the feces three order of magnitude more and for twice as long than bacteria unable to aggregate. This study identifies a novel function for ActA, which plays a key role in Lm persistence within the host and transmission.

Although the tail is one of the major characteristics of animals of the phylum Chordata, evolutionary aspects of the molecular mechanisms involved in its formation are not clear. To obtain insights into these issues, we have isolated and investigated the caudal gene of an ascidian, one of the lower animal groups among chordates. Ascidian caudal is expressed from the midgastrula stage onward in the lateral walls of the posterior neural tube cell lineage and also in the posterior epidermal cells from the neurula stage. Thus, ascidian caudal expression is restricted to the ectoderm of a tail-forming region throughout embryogenesis. Suppression of caudal function by an antisense oligonucleotide or a dominant negative construct caused inhibition of the cell movement required for tail formation. Overexpression of wild-type caudal mRNA in an ascidian animal cap, an animal half explant prepared at the eight-cell stage, caused elongation of the cap. Furthermore, Xenopus embryos injected with dominant negative ascidian caudal exhibited defects in elongation, suggesting a conserved caudal function among chordates. These results indicate that caudal function is required for chordate tail formation and may play a key role in its evolution.