Inhibition of penicillin biosynthetic enzymes by halogen derivatives of phenylacetic acid

Summary The effect of phenylacetic acid (PAA) and several analogs on the activity of isopenicillin N synthase (IPNS) and acyl-CoA: 6-APA acyltransferase (AT) fromPenicillium chrysogenum Wis 54-1255 has been tested. Whereas the substitution on the ring of a hydrogen atom by hydroxy-, methyl- or methoxy- groups did not cause any effect, the presence of halogens (Cl or Br) at positions 3 and/or 4 of PAA strongly inhibited these two enzymes. The replacement of hydrogen atoms by fluorine in certain positions also caused inhibition, but to a lesser extent.     

On a cranial bony nodular protuberance on Mourasuchus pattersoni Cidade et al. 2017 (Crocodylia,Alligatoroidea) from the late Miocene of Venezuela

Mourasuchus pattersoni, from the late Miocene Urumaco Formation of Venezuela, is the fourth and most recent species described for the genus. The holotype, and only known specimen, is comprised of an almost complete skull with both mandibular rami and several postcranial remains. In ventral view, the right palatine bone has a spherical, nodular bony protuberance located on the anterior portion, near the suture with the maxilla. Unfortunately, we cannot assign a specific diagnosis based only on macroscopic inspection. Its appearance, form and location are compatible with three conditions: torus palatinus, a common benign intraoral bone overgrowth; osteoma, a benign neoplasical overgrowth of the bone; and hamartoma, an overgrowth of normal bone tissue that can only be differed from an osteoma by histological features. While occurrences of torus palatinus or hamartomas are not yet known in the nonhominid vertebrate fossil record, there are previous records of osteomas in fossil vertebrates, including in crocodylians, such as a specimen assigned to ‘Crocodylus sp.’ from the Eocene, aside from several records for living crocodylians. Future studies are needed to uncover an accurate diagnosis of this unusual structure and help increase our knowledge of paleopathology in fossil crocodylomorphs in general, especially in the Caimaninae clade.     

Synthesis of a natural chalcone and its prenyl analogs--evaluation of tumor cell growth-inhibitory activities, and effects on cell cycle and apoptosis

Six prenyl (=3-methylbut-2-en-1-yl) chalcones (=1,3-diphenylprop-2-en-1-ones), 2-7, and one natural non-prenylated chalcone, 1, have been synthesized and evaluated for their in vitro growth-inhibitory activity against three human tumor cell lines. A pronounced dose-dependent growth-inhibitory effect was observed for all prenylated derivatives, except for 7. The chalcone possessing one prenyloxy group at C(2'), i.e., 2, was the most active derivative against the three human tumor cell lines (5.9相似文献   

Studies on genetic transformation of Theobroma cacao L.: evaluation of different polyamines and antibiotics on somatic embryogenesis and the efficiency of uidA gene transfer by Agrobacterium tumefaciens

In order to develop a more efficient genetic transformation system for cacao somatic embryos, the effects of polyamines and β-lactam antibiotics on somatic embryogenesis, hygromycin as selective agent, and different factors affecting uidA gene transfer have been evaluated. The polyamines putrescine, spermidine, and spermine significantly improved secondary somatic embryogenesis in cacao. Spermine at 1,000 μM provided the best responses, increasing 6.7× the percentage of embryogenic callus and 2.5× the average number of embryos per embryogenic callus. The β-lactam antibiotics timentin and meropenem, used for Agrobacterium tumefaciens counter-selection, had a non-detrimental effect on secondary somatic embryogenesis, depending on their concentration, whereas the commonly used β-lactam cefotaxime inhibited it, irrespective of the tested concentration. Hygromycin showed a strong inhibitory effect on secondary somatic embryogenesis of cacao, impairing completely the embryo production at 20 mg l⁻¹. Following the criterion of GUS activity, the best conditions for T-DNA transfer into cotyledon explants from primary somatic embryos of cacao were a sonication of the explants for 100 s, a 20-min incubation period in Agrobacterium solution, an Agrobacterium concentration of 1.0 (OD₆₀₀), and cocultivation of the explants on tobacco feeder layers. These findings will have important implications for studies on functional genomics of cacao.     

Evaluation of novel beta-lactam antibiotics in comparison to cefotaxime on plant regeneration of <Emphasis Type="Italic">Citrus sinensis</Emphasis> L. Osb.

Identification of beta-lactam antibiotics that have negligible effects on plant regeneration is a critical step towards the establishment of a reliable Agrobacterium-mediated transformation protocol for perennial trees. In the present report, we have evaluated the effects of the novel beta-lactam antibiotics meropenem and timentin on plant regeneration of a perennial woody fruit plant, Citrus sinensis, in comparison with the commonly used beta-lactam cefotaxime. It was observed that, in contrast to cefotaxime, meropenem and timentin had a positive or no detrimental effect on the shoot regeneration from epicotyl explants. Residual effects of the beta-lactams from shoot regeneration medium also affected the subsequent ability of the roots to elongate. The addition of meropenem and/or timentin in the rooting medium mostly improved or did not affect the rooting ability of the adventitious shoots. These data indicated that meropenem and timentin can positively replace cefotaxime in Agrobacterium-mediated transformation of C. sinensis.     

First microsatellite markers for <Emphasis Type="Italic">Paspalum plicatulum</Emphasis> (Poaceae) characterization and cross-amplification in different <Emphasis Type="Italic">Paspalum</Emphasis> species of the Plicatula group

Background

Paspalum plicatulum is a perennial rhizomatous grass with natural diploid and polyploid cytotypes. It is a member of Plicatula, which has historically been recognized as a highly complex group containing species of ecological, ornamental and forage importance. The complex nature of the P. plicatulum genome makes it a challenging species for genetic research. This study aimed to develop and characterize microsatellite molecular markers in P. plicatulum and to evaluate their transferability to other Plicatula group species.

Findings

Microsatellite sequences were identified from three enriched libraries from P. plicatulum. Specific primers were designed, and 25 displayed polymorphism when screened across 48 polyploid Paspalum spp. genotypes. The number of bands per locus ranged from 2 to 17, with a mean of 8.65. Private bands for each species were identified; the highest number of private bands was observed for P. plicatulum in 52% of the loci analyzed. The mean polymorphism information content of all loci was 0.69, and the mean discriminatory power was 0.82. Microsatellite markers were satisfactorily cross-amplified for the eight tested Plicatula-group Paspalum species, with P. atratum exhibiting the highest transferability rate (89.86%). STRUCTURE and Discriminant Analysis of Principal Components separated accessions into three groups but did not reveal separation of the accessions according to species.

Conclusions

This study describes the first microsatellite markers in P. plicatulum, which are polymorphic, efficient for the detection and quantification of genetic variation, and show high transferability into other species of the Plicatula group. This set of markers can be used in future genetic and molecular studies necessary for the proper development of conservation and breeding programs. Private bands within the markers can be used to assist in species identification.