Tight Closure of Finite Length Modules in Graded Rings

We look at how the equivalence of tight closure and plus closure (or Frobenius closure) in the homogeneous m-coprimary case implies the same closure equivalence in the non-homogeneous m-coprimary case in standard graded rings. Although our result does not depend upon dimension, the primary application is based on results known in dimension 2 due to the recent results of H. Brenner. We also show that unlike the Noetherian case, the injective hull of the residue field over $R^+$ or $R^\infty$ contains elements that are not killed by any power of the maximal ideal of R.Comment: 14 pages, minor revisions mad

Riboflavin induces Metarhizium spp. to produce conidia with elevated tolerance to UV-B, and upregulates photolyases, laccases and polyketide synthases genes

Aims: The effect of nutritional supplementation of two Metarhizium species with riboflavin (Rb) during production of conidia was evaluated on (i) conidial tolerance (based on germination) to UV-B radiation and on (ii) conidial expression following UV-B irradiation, of enzymes known to be active in photoreactivation, viz., photolyase (Phr), laccase (Lac) and polyketide synthase (Pks). Methods and Results: Metarhizium acridum (ARSEF 324) and Metarhizium robertsii (ARSEF 2575) were grown either on (i) potato dextrose agar medium (PDA), (ii) PDA supplemented with 1% yeast extract (PDAY), (iii) PDA supplemented with Rb (PDA+Rb), or (iv) PDAY supplemented with Rb (PDAY+Rb). Resulting conidia were exposed to 866·7 mW m−2 of UV-B Quaite-weighted irradiance to total doses of 3·9 or 6·24 kJ m−2. Some conidia also were exposed to 16 klux of white light (WL) after being irradiated, or not, with UV-B to investigate the role of possible photoreactivation. Relative germination of conidia produced on PDA+Rb (regardless Rb concentration) or on PDAY and exposed to UV-B was higher compared to conidia cultivated on PDA without Rb supplement, or to conidia suspended in Rb solution immediately prior to UV-B exposure. The expression of MaLac3 and MaPks2 for M. acridum, as well as MrPhr2, MrLac1, MrLac2 and MrLac3 for M. robertsii was higher when the isolates were cultivated on PDA+Rb and exposed to UV-B followed by exposure to WL, or exposed to WL only. Conclusions: Rb in culture medium increases the UV-B tolerance of M. robertsii and M. acridum conidia, and which may be related to increased expression of Phr, Lac and Pks genes in these conidia. Significance and Impact of the Study: The enhanced UV-B tolerance of Metarhizium spp. conidia produced on Rb-enriched media may improve the effectiveness of these fungi in biological control programs.Fil: Pereira-Junior, R.A.. Universidade Federal de Goiás; Brasil. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner". Universidad Nacional de la Plata. Facultad de Ciencias Médicas. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner"; ArgentinaFil: Huarte Bonnet, Carla. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner". Universidad Nacional de la Plata. Facultad de Ciencias Médicas. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner"; Argentina. Universidade Federal de Goiás; BrasilFil: Paixão, F.R.S.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner". Universidad Nacional de la Plata. Facultad de Ciencias Médicas. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner"; Argentina. Universidade Federal de Goiás; BrasilFil: Roberts, D.W.. State University of Utah; Estados UnidosFil: Luz, C.. Universidade Federal de Goiás; BrasilFil: Pedrini, Nicolás. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner". Universidad Nacional de la Plata. Facultad de Ciencias Médicas. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner"; ArgentinaFil: Fernandes, É.K.K.. Universidade Federal de Goiás; Brasi

De novo lipogenesis at the mitotic exit is used for nuclear envelope reassembly/expansion: Implications for combined chemotherapy

Mitosis has been traditionally considered a metabolically inactive phase. We have previously shown, however, that extensive alterations in lipids occur as the cells traverse mitosis, including increased de novo fatty acid (FA) and phosphatidylcholine (PtdCho) synthesis and decreased lysophospholipid content. Given the diverse structural and functional properties of these lipids, we sought to study their metabolic fate and their importance for cell cycle completion. Here we show that FA and PtdCho synthesized at the mitotic exit are destined to the nuclear envelope. Importantly, FA and PtdCho synthesis, but not the decrease in lysophospholipid content, are necessary for cell cycle completion beyond G2/M. Moreover, the presence of alternative pathways for PtdCho synthesis renders the cells less sensitive to its inhibition than to the impairment of FA synthesis. FA synthesis, thus, represents a cell cycle-related metabolic vulnerability that could be exploited for combined chemotherapy. We explored the combination of fatty acid synthase (FASN) inhibition with agents that act at different phases of the cell cycle. Our results show that the effect of FASN inhibition may be enhanced under some drug combinations.Fil: Rodriguez Sawicki, Luciana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner". Universidad Nacional de la Plata. Facultad de Ciencias Médicas. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner"; ArgentinaFil: Garcia, Karina Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner". Universidad Nacional de la Plata. Facultad de Ciencias Médicas. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner"; ArgentinaFil: Córsico, Betina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner". Universidad Nacional de la Plata. Facultad de Ciencias Médicas. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner"; ArgentinaFil: Scaglia, Natalia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner". Universidad Nacional de la Plata. Facultad de Ciencias Médicas. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner"; Argentin

Tolerance to Abiotic Factors of Microsclerotia and Mycelial Pellets From Metarhizium robertsii, and Molecular and Ultrastructural Changes During Microsclerotial Differentiation

Metarhizium spp. fungi are able to produce resistant structures termed microsclerotia, formed by compacted and melanized threads of hyphae. These propagules are tolerant to desiccation and produce infective conidia, thus they are promising candidates to use in biological control programs. In this study, we investigated the tolerance to both UV-B radiation and heat of microsclerotia of M. robertsii strain ARSEF 2575. We also adapted the liquid medium and culture conditions to obtain mycelial pellets from the same isolate in order to compare these characteristics between both types of propagules. We followed the peroxisome biogenesis and studied the oxidative stress during differentiation from conidia to microsclerotia by transmission electron microscopy after staining with a peroxidase activity marker, and by the expression pattern of genes potentially involved in these processes. We found that despite their twice smaller size, microsclerotia exhibited higher dry biomass, yield, and conidial productivity than mycelial pellets, both with and without UV-B and heat stresses.. From the sixteen genes measured, we found an induction after 96-h differentiation in the oxidative stress marker genes MrcatA, MrcatP, and Mrgpx, the peroxisome biogenesis factors Mrpex5 and Mrpex14/17, and the photoprotection genes Mrlac1, Mrlac2, and Mrlac3. We concluded that an oxidative stress scenario is induced during microsclerotia differentiation in M. robertsii, and confirmed that due to its tolerance to desiccation, heat, and UV-B, this fungal structure could be an excellent candidate for use in biological control of pests under tropical and subtropical climates where heat and UV radiation are detrimental to entomopathogenic fungi survival and persistence.Fil: Paixão, Flávia R. S.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner". Universidad Nacional de la Plata. Facultad de Ciencias Médicas. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner"; ArgentinaFil: Huarte Bonnet, Carla. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner". Universidad Nacional de la Plata. Facultad de Ciencias Médicas. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner"; ArgentinaFil: Ribeiro-Silva, Cárita de S.. Universidade Federal de Goias. Instituto de Patologia Tropical E Saude Publica.; BrasilFil: Mascarin, Gabriel M.. Empresa Brasilera de Pesquisa Agropecuaria.; BrasilFil: Fernandes, Éverton. Universidade Federal de Goias. Instituto de Patologia Tropical E Saude Publica.; BrasilFil: Pedrini, Nicolás. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner". Universidad Nacional de la Plata. Facultad de Ciencias Médicas. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner"; Argentin

Hair Trigger 25

An anthology, edited by students, featuring the fiction, prose and creative non-fiction work of students, alumni, and staff. Editors: Marcia K. Brenner, Shelli Johnson, Carla McCarthy, Lila Nagarajan, Lisa Redmond, Tina Raffaelle-Lamitie, Christine M. Semenow, Michael David Sims, Simon Smith. Cover photograph: Sarah Faust. 277 pages.https://digitalcommons.colum.edu/hairtrigger/1022/thumbnail.jp

Saccharomyces cerevisiae and Schizosaccharomyces pombe contain a homologue to the 54-kD subunit of the signal recognition particle that in S. cerevisiae is essential for growth.

We have isolated and sequenced genes from Saccharomyces cerevisiae (SRP54SC) and Schizosaccharomyces pombe (SRP54sp) encoding proteins homologous to both the 54-kD protein subunit (SRP54mam) of the mammalian signal recognition particle (SRP) and the product of a gene of unknown function in Escherichia coli, ffh (Römisch, K., J. Webb, J. Herz, S. Prehn, R. Frank, M. Vingron, and B. Dobberstein. 1989. Nature (Lond.). 340:478-482; Bernstein H. D., M. A. Poritz, K. Strub, P. J. Hoben, S. Brenner, P. Walter. 1989. Nature (Lond.). 340:482-486). To accomplish this we took advantage of short stretches of conserved sequence between ffh and SRP54mam and used the polymerase chain reaction (PCR) to amplify fragments of the homologous yeast genes. The DNA sequences predict proteins for SRP54sc and SRP54sp that are 47% and 52% identical to SRP54mam, respectively. Like SRP54mam and ffh, both predicted yeast proteins contain a GTP binding consensus sequence in their NH2-terminal half (G-domain), and methionine-rich sequences in their COOH-terminal half (M-domain). In contrast to SRP54mam and ffh the yeast proteins contain additional Met-rich sequences inserted at the COOH-terminal portion of the M-domain. SRP54sp contains a 480-nucleotide intron located 78 nucleotides from the 5' end of the open reading frame. Although the function of the yeast homologues is unknown, gene disruption experiments in S. cerevisiae show that the gene is essential for growth. The identification of SRP54sc and SRP54sp provides the first evidence for SRP related proteins in yeast

On the arithmetic of tight closure

We provide a negative answer to an old question in tight closure theory by showing that the containment x^3y^3 \in (x^4,y^4,z^4)^* in K[x,y,z]/(x^7+y^7-z^7) holds for infinitely many but not for almost all prime characteristics of the field K. This proves that tight closure exhibits a strong dependence on the arithmetic of the prime characteristic. The ideal (x,y,z) \subset K[x,y,z,u,v,w]/(x^7+y^7-z^7, ux^4+vy^4+wz^4+x^3y^3) has then the property that the cohomological dimension fluctuates arithmetically between 0 and 1