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951.
Renata Plocinska Luis Martinez Purushotham Gorla Emmanuel Pandeeti Krishna Sarva Ewelina Blaszczyk Jaroslaw Dziadek Murty V. Madiraju Malini Rajagopalan 《Journal of bacteriology》2014,196(23):4120-4129
The septal association of Mycobacterium tuberculosis MtrB, the kinase partner of the MtrAB two-component signal transduction system, is necessary for the optimal expression of the MtrA regulon targets, including ripA, fbpB, and ftsI, which are involved in cell division and cell wall synthesis. Here, we show that MtrB, irrespective of its phosphorylation status, interacts with Wag31, whereas only phosphorylation-competent MtrB interacts with FtsI. We provide evidence that FtsI depletion compromises the MtrB septal assembly and MtrA regulon expression; likewise, the absence of MtrB compromises FtsI localization and, possibly, FtsI activity. We conclude from these results that FtsI and MtrB are codependent for their activities and that FtsI functions as a positive modulator of MtrB activation and MtrA regulon expression. In contrast to FtsI, Wag31 depletion does not affect MtrB septal assembly and MtrA regulon expression, whereas the loss of MtrB increased Wag31 localization and the levels of PknA/PknB (PknA/B) serine-threonine protein kinase-mediated Wag31 phosphorylation. Interestingly, we found that FtsI decreased levels of phosphorylated Wag31 (Wag31∼P) and that MtrB interacted with PknA/B. Overall, our results indicate that MtrB interactions with FtsI, Wag31, and PknA/B are required for its optimal localization, MtrA regulon expression, and phosphorylation of Wag31. Our results emphasize a new role for MtrB in cell division and cell wall synthesis distinct from that regulating the MtrA phosphorylation activities. 相似文献
952.
Laureano Castro Luis Castro-Nogueira Miguel A. Castro-Nogueira Miguel A. Toro 《Biology & philosophy》2010,25(3):347-360
Humans have developed the capacity to approve or disapprove of the behavior of their children and of unrelated individuals.
The ability to approve or disapprove transformed social learning into a system of cumulative cultural inheritance, because
it increased the reliability of cultural transmission. Moreover, people can transmit their behavioral experiences (regarding
what can and cannot be done) to their offspring, thereby avoiding the costs of a laborious, and sometimes dangerous, evaluation
of different cultural alternatives. Our thesis is that, during ontogeny, the evaluative communication (approval/disapproval)
between parents and offspring is substituted by other evaluative communications among peers, like individuals of the same
generation. Each person belongs to a reference social group with individuals that interact more intensively. Humans have developed
psychological mechanisms that enable cultural transmission by being receptive to parental advice as well as their reference
social group. The selective pressure that promoted these new evaluative interactions arose to facilitate the establishment
of efficient cooperative relationships. In short, the social control of behavior is essential to understand human cultural
transmission. 相似文献
953.
Marta Rodríguez-Sáiz Juan Luis de la Fuente José Luis Barredo 《Applied microbiology and biotechnology》2010,88(3):645-658
Astaxanthin is a red xanthophyll (oxygenated carotenoid) with large importance in the aquaculture, pharmaceutical, and food
industries. The green alga Haematococcus pluvialis and the heterobasidiomycetous yeast Xanthophyllomyces dendrorhous are currently known as the main microorganisms useful for astaxanthin production at the industrial scale. The improvement
of astaxanthin titer by microbial fermentation is a requirement to be competitive with the synthetic manufacture by chemical
procedures, which at present is the major source in the market. In this review, we show how the isolation of new strains of
X. dendrorhous from the environment, the selection of mutants by the classical methods of random mutation and screening, and the rational
metabolic engineering, have provided improved strains with higher astaxanthin productivity. To reduce production costs and
enhance competitiveness from an industrial point of view, low-cost raw materials from industrial and agricultural origin have
been adopted to get the maximal astaxanthin productivity. Finally, fermentation parameters have been studied in depth, both
at flask and fermenter scales, to get maximal astaxanthin titers of 4.7 mg/g dry cell matter (420 mg/l) when X. dendrorhous was fermented under continuous white light. The industrial scale-up of this biotechnological process will provide a cost-effective
method, alternative to synthetic astaxanthin, for the commercial exploitation of the expensive astaxanthin (about $2,500 per
kilogram of pure astaxanthin). 相似文献
954.
955.
Torregrosa-Hetland CJ Villanueva J López-Font I Garcia-Martinez V Gil A Gonzalez-Vélez V Segura J Viniegra S Gutiérrez LM 《Cellular and molecular neurobiology》2010,30(8):1315-1319
In chromaffin cells, SNARE proteins, forming the basic exocytotic machinery are present in membrane clusters of 500–600 nm
in diameter. These microdomains containing both SNAP-25 and syntaxin-1 are dynamic and the expression of altered forms of
SNAREs modifies not only their motion but also the mobility of the associated granules. It is also clear that SNARE microdomain
location defines the place for individual vesicle fusion and that the alteration of cluster dynamics affects the fusion process
itself. Interestingly, these SNARE patches colocalize with the borders of F-actin cages forming the cytoskeletal cortical
network, and these borders also contain clusters of L- and P/Q type calcium channels. The organization of the secretory machinery
in association with the borders of cytoskeletal cages seems to be an effective way to promote fast coupling between calcium
entry and catecholamine release as demonstrated with the use of mathematical secretory models. 相似文献
956.
Neeraja Vajrala Luis A. Sayavedra-Soto Peter J. Bottomley Daniel J. Arp 《Archives of microbiology》2010,192(11):899-908
Nitrosomonas europaea has a single three-gene operon (nitABC) encoding an iron ABC transporter system (NitABC). Phylogenetic analysis clustered the subunit NitB with Fe3+-ABC transporter permease components from other organisms. The N.
europaea strain deficient in nitB (nitB::kan) grew well in either Fe-replete or Fe-limited media and in Fe-limited medium containing the catecholate-type siderophore,
enterobactin or the citrate-based dihydroxamate-type siderophore, aerobactin. However, the nitB::kan mutant strain was unable to grow in Fe-limited media containing either the hydroxamate-type siderophores, ferrioxamine and
ferrichrome or the mixed-chelating type siderophore, pyoverdine. Exposure of N. europaea cells to a ferrichrome analog coupled to the fluorescent moiety naphthalic diimide (Fhu-NI) led to increase in fluorescence
in the wild type but not in nitB::kan mutant cells. Spheroplasts prepared from N.
europaea wild type exposed to Fhu-NI analog retained the fluorescence, while spheroplasts of the nitB::kan mutant were not fluorescent. NitABC transports intact Fe3+-ferrichrome complex into the cytoplasm and is an atypical ABC type iron transporter for Fe3+ bound to ferrioxamine, ferrichrome or pyoverdine siderophores into the cytoplasm. The mechanisms to transport iron in either
the Fe3+ or Fe2+ forms or Fe3+ associated with enterobactin or aerobactin siderophores into the cell across the cytoplasmic membrane are as yet undetermined. 相似文献
957.
Saul Tlecuitl-Beristain Gustavo Viniegra-González Gerardo Díaz-Godínez Octavio Loera 《Mycopathologia》2010,169(5):387-394
Rice and oat flours were analyzed as media for the production of conidia by M. anisopliae var. lepidiotum. The presence of peptone increased conidia yield regardless of the substrate used; however, the highest yield was achieved
on oat flour media. The effect of oxygen on conidia production using oat-peptone medium was also studied at two levels: Normal
atmosphere (21% O2) and Oxygen-rich pulses (26% O2). Maximum conidia production (4.25 × 107 conidia cm−2) was achieved using 26% O2 pulses after 156 h of culture, which was higher than 100% relative to conidial levels under normal atmosphere. Conidia yield
per gram of biomass was 2.6 times higher with 26% O2 (1.12 × 107 conidia mg−1). Conidia quality parameters, such as germination and hydrophobicity, did not show significant differences (P < 0.05) between those treatments. Bioassays parameters, using Tenebrio molitor adults, were analyzed for conidia obtained in both atmospheres and data were fitted to an exponential model. The specific
mortality rates were 2.22 and 1.26 days−1, whereas lethal times for 50% mortality were 3.90 and 4.31 days, for 26% O2 pulses and 21% O2 atmosphere, respectively. These results are relevant for production processes since an oxygen increase allowed superior levels
of conidia by M. anisopliae without altering quality parameters and virulence toward Tenebrio molitor adults. 相似文献
958.
959.
Takahiro Shinoda Leandro A. Miranda Kozue Okuma Ricardo S. Hattori Juan I. Fernandino Goro Yoshizaki Gustavo M. Somoza Carlos A. Strüssmann 《Molecular reproduction and development》2010,77(6):521-532
In this study, we cloned and characterized the follicle stimulating hormone receptor (Fshr) and luteinizing hormone receptor (Lhr) cDNAs of pejerrey Odontesthes bonariensis, a species with temperature‐dependent sex determination (TSD), and analyzed their expression in relation to Fshb and Lhb subunits during gonadogenesis at temperatures producing only females (17°C, FPT), both sexes (25°C, MixPT), and only males (29°C, MPT). The pejerrey Fshr cDNA had 3,069 bp for a mature protein of 694 amino acids (aa) and a signal peptide of 22 aa; the Lhr cDNA had 2,936 bp for a mature protein of 676 aa and a signal peptide of 25 aa. With the exception of Lhr in fish at the MPT, all genes showed significant increases and/or peaks of expression before histological differentiation of the gonads regardless of temperature. Larvae at the FPT had lower Fshb and Lhb but higher Lhr expression during the TSD period than those at the MPT; a clear pattern could not be ascertained for Fshr. At the MixPT, Fshb, Lhb, and Lhr mRNA increased in approximately half of the fish during TSD and sex differentiation and the sex ratio was 55.2% male. Based on the above results, it is suggested that animals with high Fshb and Lhb and low Lhr values represent putative males. These evidences, together with other studies, suggest that temperature may signal through the pituitary (differential expression of Fshb and Lhb) down to the gonads (differential expression of Lhr), probably affecting the regulation of steroidogenesis during the TSD process of pejerrey. Mol. Reprod. Dev. 77: 521–532, 2010. © 2010 Wiley‐Liss, Inc. 相似文献
960.
Mario Arias Zabala Mónica Angarita Juan M. Restrepo Luis A. Caicedo Margarita Perea 《In vitro cellular & developmental biology. Plant》2010,46(3):233-238
Thevetia peruviana is a small tree that produces several compounds with pharmaceutical application, among which peruvoside could be highlighted.
However, these compounds are produced in low concentration in the plant, making it important to develop strategies such as
plant cell culture and elicitation to obtain higher quantities of the desired product. In this work, cell suspension cultures
of T. peruviana were established in four different culture media: Murashige–Skoog (MS), half Murashige–Skoog (half MS), Schenk–Hildebrandt
(SH), and Gamborg (B5) to study their effect on cell growth. Cell growth kinetics were studied in SH medium, and the extracellular
peruvoside production during the culture time was determined. The best culture medium for the establishment of cell suspension
cultures was MS with a growth index of 3.17 ± 0.2 g g−1 inoculum. The cell growth kinetics showed the four characteristic growth phases of a cell culture (lag, exponential, stationary,
and death), and during none of these phases was it possible to observe peruvoside production. The elicitor effect of methyl-jasmonate
(MeJ) was studied in cell suspension cultures established in SH medium. The effect of MeJ concentration and the time in which
it should be applied were determined. The best results were obtained at a concentration of 100 mg l−1 of MeJ applied at the beginning of the culture, which induced a peruvoside production of 8.93 mg l−1 medium. The current results are the first report of an in vitro peruvoside production system. 相似文献