Cdk1 triggers association of RNA polymerase to cell cycle promoters only after recruitment of the mediator by SBF.

Activation of HO in yeast involves recruitment of transcription factors in two waves. The first is triggered by inactivation of Cdk1 at the end of mitosis, which promotes import into the nucleus of the Swi5 transcription factor. Swi5 recruits the Swi/Snf chromatin-remodeling complex, which then facilitates recruitment of the SAGA histone acetylase, which in turn permits the binding of the SBF transcription factor. We show here that SBF then recruits the SRB/mediator complex and that this process occurs in the absence of Cdk1 activity. The second wave is triggered by reactivation of Cdk1, which leads to recruitment of PolII, TFIIB, and TFIIH. RNA polymerase is, therefore, recruited to HO in two steps and not as a holoenzyme. A similar sequence of events occurs at other SBF-regulated promoters, such as CLN1, CLN2, and PCL1.

Pds5 cooperates with cohesin in maintaining sister chromatid cohesion.

BACKGROUND: Sister chromatid cohesion depends on a complex called cohesin, which contains at least four subunits: Smc1, Smc3, Scc1 and Scc3. Cohesion is established during DNA replication, is partially dismantled in many, but not all, organisms during prophase, and is finally destroyed at the metaphase-to-anaphase transition. A quite separate protein called Spo76 is required for sister chromatid cohesion during meiosis in the ascomycete Sordaria. Spo76-like proteins are highly conserved amongst eukaryotes and a homologue in Aspergillus nidulans, called BimD, is required for the completion of mitosis. The isolation of the cohesin subunit Smc3 as a suppressor of BimD mutations suggests that Spo76/BimD might function in the same process as cohesin. RESULTS: We show here that the yeast homologue of Spo76, called Pds5, is essential for establishing sister chromatid cohesion and maintaining it during metaphase. We also show that Pds5 co-localizes with cohesin on chromosomes, that the chromosomal association of Pds5 and cohesin is interdependent, that Scc1 recruits Pds5 to chromosomes in G1 and that its cleavage causes dissociation of Pds5 from chromosomes at the metaphase-to-anaphase transition. CONCLUSIONS: Our data show that Pds5 functions as part of the same process as cohesin. Sequence similarities and secondary structure predictions indicate that Pds5 consists of tandemly repeated HEAT repeats, and might therefore function as a protein-protein interaction scaffold, possibly in the cohesin-DNA complex assembly.

Antiulcer activity of the crude extract from the leaves of casearia sylvestris.

In rats, administration of Casearia sylvestris extract derived from fresh and dried leaves protects stomach mucosa without changing gastric pH. In stress-induced acute lesions, the preventive effect of extract from dried leaves is more effective than extract from fresh leaves. In acetic acid-induced chronic ulcer, both extracts reduce the size of ulceration and increase the number of collagen fibers after 5 days of treatment, and these effects are similar with both extracts. These antiulcer activities of Casearia sylvestris may be due to the presence of volatile oils, tannins and triterpenerelated compounds.

Pharmacological assay of Cordia verbenacea. III: Oral and topical antiinflammatory activity and gastrotoxicity of a crude leaf extract.

The antiinflammatory effects and gastrotoxicity of a lyophilized 70% ethanol extract of the leaves of Cordia verbenacea were investigated through experimental models in rats and mice. The oral administration of 1.24 mg/kg of the extract significantly inhibited nystatin-induced oedema. Topical application of the extract at a dose of 0.09 mg/ear in mice was clearly more effective than 1.0 mg/ear of naproxen in the reduction of the ear oedema induced by corton oil. At antiinflammatory doses, the extract showed an important protective effect on the gastric mucosa, reducing significantly the number of gastric lesions.

Pharmacological assay of Casearia sylvestris. I: Preventive anti-ulcer activity and toxicity of the leaf crude extract.

An ethanol extract of the leaves of Brazilian Casearia sylvestris, given orally, inhibited gastric secretion in pylorus-ligated rats. At a prophylactic dose of 57.5 mg/kg, the extract showed a reduction of gastric juice more effective than misoprostol (500 micrograms/kg). In reducing hydrochloric acid output, the extract was less effective than misoprostol, cimetidine (32.0 mg/kg) and atropine (5.3 mg/kg). With the extract, the pH of the stomach contents was not significantly different from that of controls. Stress-induced lesions produced by restraint and water immersion were significantly prevented by the extract for all levels of severity when compared with the controls. The extract appeared more effective than misoprostol in suppressing light lesions, was equivalent to cimetidine and misoprostol for moderate lesions, and less effective than cimetidine and misoprostol for severe lesions. Toxicological experiments indicated a low acute toxicity, confirmed by subchronic daily testing. The oral LD50 value of greater than 1840 mg/kg was over 32 times higher than the antiulcerogenic ED50 (57.5 mg/kg).

Anti-inflammatory activity and sub-acute toxicity of artemetin.

The 5-hydroxy-3,6,7,3',4'-pentamethoxyflavone (artemetin) from Cordia verbenacea DC (Boraginaceae) showed marked anti-inflammatory activity using various experimental models in rats. Artemetin significantly inhibited carrageenin-induced paw edema following oral doses from 30.4 to 153.9 mg.kg-1. The doses of 102.6 and 153.9 mg.kg-1 showed an inhibitory effect similar to that of 50.0 mg.kg-1 of calcium phenylbutazone. The ED50 value of artemetin in rats was estimated to be 67.07 mg.kg-1. Repeated administration of artemetin at doses of 67.07 mg.kg-1 for a 6-day period reduced granuloma formation with a response comparable to that of 20.0 mg.kg-1 of calcium phenylbutazone. This same dose of artemetin also reduced the vascular permeability to intracutaneous histamine. Sub-acute toxicological experiments indicated a very low toxicity.

[Morphology and anatomy of the leaf of Cybistax antisyphilitica (Martius) Martius, Bignoniaceae]. / Sobre a morfologia e anatomia da folha do Cybistax antisyphilitica (Martius) Martius, Bignoniaceae

The anatomical study on the leaf of Cybistax antisyphilitica (Martius) Martius was perfomed. It is used in folk medicine. A comparative analysis with other organs of the same species, which is native in Brazilian flora, was made. In the leaf plentiful inclusions of reside oil were found whose chemical composition and pharmacodynamic effects are little know.