Regulation of Growth, Cell Shape, Cell Division, and Gene Expression by Second Messengers (p)ppGpp and Cyclic Di-GMP in Mycobacterium smegmatis

The alarmone (p)ppGpp regulates transcription, translation, replication, virulence, lipid synthesis, antibiotic sensitivity, biofilm formation, and other functions in bacteria. Signaling nucleotide cyclic di-GMP (c-di-GMP) regulates biofilm formation, motility, virulence, the cell cycle, and other functions. In Mycobacterium smegmatis, both (p) ppGpp and c-di-GMP are synthesized and degraded by bifunctional proteins Rel(Msm) and DcpA, encoded by rel(Msm) and dcpA genes, respectively. We have previously shown that the Delta rel(Msm) and Delta dcpA knockout strains are antibiotic resistant and defective in biofilm formation, show altered cell surface properties, and have reduced levels of glycopeptidolipids and polar lipids in their cell wall (K. R. Gupta, S. Kasetty, and D. Chatterji, Appl Environ Microbiol 81:2571-2578, 2015, http://dx.doi.org/10.1128/AEM.03999-14). In this work, we have explored the phenotypes that are affected by both (p) ppGpp and c-di-GMP in mycobacteria. We have shown that both (p) ppGpp and c-di-GMP are needed to maintain the proper growth rate under stress conditions such as carbon deprivation and cold shock. Scanning electron microscopy showed that low levels of these second messengers result in elongated cells, while high levels reduce the cell length and embed the cells in a biofilm-like matrix. Fluorescence microscopy revealed that the elongated Delta rel(Msm) and Delta dcpA cells are multinucleate, while transmission electron microscopy showed that the elongated cells are multiseptate. Gene expression analysis also showed that genes belonging to functional categories such as virulence, detoxification, lipid metabolism, and cell-wall-related processes were differentially expressed. Our results suggests that both (p) ppGpp and c-di-GMP affect some common phenotypes in M. smegmatis, thus raising a possibility of cross talk between these two second messengers in mycobacteria. IMPORTANCE Our work has expanded the horizon of (p) ppGpp and c-di-GMP signaling in Gram-positive bacteria. We have come across a novel observation that M. smegmatis needs (p) ppGpp and c-di-GMP for cold tolerance. We had previously shown that the Delta rel(Msm) and Delta dcpA strains are defective in biofilm formation. In this work, the overproduction of (p) ppGpp and c-di-GMP encased M. smegmatis in a biofilm-like matrix, which shows that both (p) ppGpp and c-di-GMP are needed for biofilm formation. The regulation of cell length and cell division by (p) ppGpp was known in mycobacteria, but our work shows that c-di-GMP also affects the cell size and cell division in mycobacteria. This is perhaps the first report of c-di-GMP regulating cell division in mycobacteria.

Impossibilità di pensare Dio non esistente : il Proslogion di Anselmo d'Aosta come applicazione implicita dei moderni procedimenti di logica aletica

Resumen: La vera intenzione teologica di Anselmo d’Aosta nello scrivere il Proslogion e il vero significato del suo celebre unum argumentum vanno visti nella funzione che la ragione svolge necessariamente all’interno della vita di fede del cristiano. Anselmo, come Tommaso d’Aquino, non sostiene che l’esistenza di Dio sia un “articulus fidei” ma piuttosto uno dei “praeambula fidei”. La ragione naturale ha la certezza che Dio esiste, ancora prima della dimostrazione metafisica, e questo non fa che confermare l’assurdità di pensare che non esista il fondamento reale di tutte le cose esistenti.

La distruzione delle statue di Pausania nella Sparta tardoantica (Lib. Ep. 1518)

Abstract: The late antique destruction of two bronze statues of Pausanias - the Spartan general responsible for the Greek victory at the Battle of Plataea (479 BC) - housed in the temple of Athena Chalkioikos in Sparta (Lib. Ep. 1518), has been interpreted as one of the few cases of a violent conflict between pagan and Christian population in Greece. Nevertheless the sources suggest that late antique Sparta was a bastion of Hellenic paganism and give a picture of a small and quiet town ruled by a pagan educated élite, where pagans like Libanius wanted to live. Since there is no evidence of a violent conflict between pagans and Christians in Sparta, and Libanius confirms that in 365 AD all the temples and cult statues were still in place, this paper addresses the issue from a different point of view and offers a new contribution to the history of Sparta in Late Antiquity. By using literary, archaeological and epigraphic evidence the paper explores: 1) the relationship between Roman administration and Spartan élite in the IVth century AD; 2) the historical memory of Pausanias in Late Antiquity. It will be emphasized that the obscure burning of the two statues helped to remove from Sparta the memory of Pausanias - a controversial figure, misrepresented in Late Antiquity and connected to the ancient staseis in Laconia - in order to promote a positive image of Sparta as a city without conflicts and ruled by the political system of Lycurgus (eunomia). As documented by local inscriptions in praise of late Roman governors, the mythical lawgiver Lycurgus was the paradigm of the imperial governors who rebuilded the town in the IVth cent. AD. It can be assumed that while Rome, Constantinople, Antioch and Athens were troubled by political and religious violence or by seditions between different factions, Sparta aimed to revive its traditional model of civic order in the new historical context of Late Antiquity.

Evaluación de la eficacia de la técnica de floating system para la producción de radicchio rosso var. di Verona en condiciones controladas

La técnica de producción en Floating system constituye una alternativa económica y veloz de producción en hidroponia. Este sistema permite obtener hojas de vegetales de pequeño tamaño “Baby leaf” listas para consumir (IV Gama), cuyo consumo a nivel mundial muestra una tendencia creciente. Dicha técnica no se encuentra aún muy difundida para la producción de radicchio rosso. El objetivo de este trabajo fue evaluar el efecto del tamaño de celda, del substrato y de la técnica de floating system sobre la producción de radicchio. Los ensayos se realizaron en cámara a 25 ºC con un fotoperíodo de 16 hs de luz y 8 de oscuridad y con una intensidad de luz de 10 000 Lux. Se utilizó un diseño experimental factorial totalmente aleatorizado, con 5 repeticiones y 3 factores, cuyos niveles fueron: 1) Tamaño de celda, (T), con 3 niveles: grande, mediano y pequeño, 2) Técnica de producción, (F), con 2 niveles: floating system y sistema convencional, 3) Sustrato, (S), con 2 niveles: vermiculita y mezcla. Se analizaron las siguientes variables: 1) peso fresco, 2) peso seco, 3) largo de planta, 4) número de hojas y 5) área foliar. Los resultados obtenidos resultan alentadores respecto del empleo de la técnica de floating system. Para la obtención de plántulas con calidad de IV Gama resulta más conveniente el empleo de celdas de 80 cm3 y sustrato mezcla.

Vita, et fatti dell'invitissimo imperatore Carlo Qvinto, et historie universali del mondo, de' suoi tempi... opera vitilissima a prencipi, signori, & capitani, & qual si voglia persona che d'historie si diletta composta dal Sig. Alfonso Ulloa, con la Pace, & Capitolationi seguite, tra li due potentissimi Prencipi Di Francia, & Spagna : & Con Toaule Copiosissime : & In questa ultima qditione in molti moughi mccresciuta, & migliorata

Afonso de Ulloa, escritor espanhol, nasceu em Zamora na primeira metade do século XVl e morreu em Veneza, Itália, em 1580. Filho de Francisco de Ulloa, oficial que esteve na África com Carlos V, seguiu também a carreira das armas, estabelecendo-se depois em Veneza. Desempenhou várias missões diplomáticas, escreveu muitas obras e traduziu para o italiano, língua que conhecia tanto quanto a materna, autores espanhóis e portugueses. Quanto à obra Vita, et fatti dell' invitissimo imperatore Carlo Qvinto.. . sabe-se que foi pela primeira vez impressa em Veneza em 1560 por Vincenzo Valgrisio e que foi muitas vezes reeditada. Salvo pela época, a edição supra referenciada não oferece grande interesse artístico, mas há uma interessante gravura com a efígie de Carlos V.