Kinetic and stability properties of Penicillium chrysogenum ATP sulfurylase missing the C-terminal regulatory domain

ATP sulfurylase from Penicillium chrysogenum is a homohexameric enzyme that is subject to allosteric inhibition by 3'-phosphoadenosine 5'-phosphosulfate. In contrast to the wild type enzyme, recombinant ATP sulfurylase lacking the C-terminal allosteric domain was monomeric and noncooperative. All kcat values were decreased (the adenosine 5'-phosphosulfate (adenylylsulfate) (APS) synthesis reaction to 17% of the wild type value). Additionally, the Michaelis constants for MgATP and sulfate (or molybdate), the dissociation constant of E.APS, and the monovalent oxyanion dissociation constants of dead end E.MgATP.oxyanion complexes were all increased. APS release (the k6 step) was rate-limiting in the wild type enzyme. Without the C-terminal domain, the composite k5 step (isomerization of the central complex and MgPPi release) became rate-limiting. The cumulative results indicate that besides (a) serving as a receptor for the allosteric inhibitor, the C-terminal domain (b) stabilizes the hexameric structure and indirectly, individual subunits. Additionally, (c) the domain interacts with and perfects the catalytic site such that one or more steps following the formation of the binary E.MgATP and E.SO4(2-) complexes and preceding the release of MgPPi are optimized. The more negative entropy of activation of the truncated enzyme for APS synthesis is consistent with a role of the C-terminal domain in promoting the effective orientation of MgATP and sulfate at the active site.     

A computational investigation of kinetoplastid trans-splicing

Trans-splicing is an unusual process in which two separate RNA strands are spliced together to yield a mature mRNA. We present a novel computational approach which has an overall accuracy of 82% and can predict 92% of known trans-splicing sites. We have applied our method to chromosomes 1 and 3 of Leishmania major, with high-confidence predictions for 85% and 88% of annotated genes respectively. We suggest some extensions of our method to other systems.     

Antioxidant and Antibacterial Activities of Crude Extracts and Essential Oils of Syzygium cumini Leaves

This research highlights the chemical composition, antioxidant and antibacterial activities of essential oils and various crude extracts (using methanol and methylene chloride) from Syzygium cumini leaves. Essential oils were analyzed by gas chromatography-mass spectrometry (GC-MS).The abundant constituents of the oils were: α-pinene (32.32%), β-pinene (12.44%), trans-caryophyllene (11.19%), 1, 3, 6-octatriene (8.41%), delta-3-carene (5.55%), α-caryophyllene (4.36%), and α-limonene (3.42%).The antioxidant activities of all extracts were examined using two complementary methods, namely diphenylpicrylhydrazyl (DPPH) and ferric reducing power (FRAP). In both methods, the methanol extract exhibited a higher activity than methylene chloride and essential oil extracts. A higher content of both total phenolics and flavonoids were found in the methanolic extract compared with other extracts. Furthermore, the methanol extract had higher antibacterial activity compared to methylene chloride and the essential oil extracts. Due to their antioxidant and antibacterial properties, the leaf extracts from S. cumini may be used as natural preservative ingredients in food and/or pharmaceutical industries.     

Biodiversity of 52 chicken populations assessed by microsatellite typing of DNA pools

In a project on the biodiversity of chickens funded by the European Commission (EC), eight laboratories collaborated to assess the genetic variation within and between 52 populations from a wide range of chicken types. Twenty-two di-nucleotide microsatellite markers were used to genotype DNA pools of 50 birds from each population. The polymorphism measures for the average, the least polymorphic population (inbred C line) and the most polymorphic population (Gallus gallus spadiceus) were, respectively, as follows: number of alleles per locus, per population: 3.5, 1.3 and 5.2; average gene diversity across markers: 0.47, 0.05 and 0.64; and proportion of polymorphic markers: 0.91, 0.25 and 1.0. These were in good agreement with the breeding history of the populations. For instance, unselected populations were found to be more polymorphic than selected breeds such as layers. Thus DNA pools are effective in the preliminary assessment of genetic variation of populations and markers. Mean genetic distance indicates the extent to which a given population shares its genetic diversity with that of the whole tested gene pool and is a useful criterion for conservation of diversity. The distribution of population-specific (private) alleles and the amount of genetic variation shared among populations supports the hypothesis that the red jungle fowl is the main progenitor of the domesticated chicken.     

Synthesis,biological evaluation,and molecular docking of new series of antitumor and apoptosis inducers designed as VEGFR-2 inhibitors

Based on quinazoline, quinoxaline, and nitrobenzene scaffolds and on pharmacophoric features of VEGFR-2 inhibitors, 17 novel compounds were designed and synthesised. VEGFR-2 IC₅₀ values ranged from 60.00 to 123.85 nM for the new derivatives compared to 54.00 nM for sorafenib. Compounds 15_a, 15_b, and 15_d showed IC₅₀ from 17.39 to 47.10 µM against human cancer cell lines; hepatocellular carcinoma (HepG2), prostate cancer (PC3), and breast cancer (MCF-7). Meanwhile, the first in terms of VEGFR-2 inhibition was compound 15_d which came second with regard to antitumor assay with IC₅₀ = 24.10, 40.90, and 33.40 µM against aforementioned cell lines, respectively. Furthermore, Compound 15_d increased apoptosis rate of HepG2 from 1.20 to 12.46% as it significantly increased levels of Caspase-3, BAX, and P53 from 49.6274, 40.62, and 42.84 to 561.427, 395.04, and 415.027 pg/mL, respectively. Moreover, 15_d showed IC₅₀ of 253 and 381 nM against HER2 and FGFR, respectively.     

lemmingA encodes the Apc11 subunit of the APC/C in Drosophila melanogaster that forms a ternary complex with the E2-C type ubiquitin conjugating enzyme, Vihar and Morula/Apc2

Background

The spindle assembly checkpoint (SAC) inhibits anaphase progression in the presence of insufficient kinetochore-microtubule attachments, but cells can eventually override mitotic arrest by a process known as mitotic slippage or adaptation. This is a problem for cancer chemotherapy using microtubule poisons.

Results

Here we describe mitotic slippage in yeast bub2?? mutant cells that are defective in the repression of precocious telophase onset (mitotic exit). Precocious activation of anaphase promoting complex/cyclosome (APC/C)-Cdh1 caused mitotic slippage in the presence of nocodazole, while the SAC was still active. APC/C-Cdh1, but not APC/C-Cdc20, triggered anaphase progression (securin degradation, separase-mediated cohesin cleavage, sister-chromatid separation and chromosome missegregation), in addition to telophase onset (mitotic exit), during mitotic slippage. This demonstrates that an inhibitory system not only of APC/C-Cdc20 but also of APC/C-Cdh1 is critical for accurate chromosome segregation in the presence of insufficient kinetochore-microtubule attachments.

Conclusions

The sequential activation of APC/C-Cdc20 to APC/C-Cdh1 during mitosis is central to accurate mitosis. Precocious activation of APC/C-Cdh1 in metaphase (pre-anaphase) causes mitotic slippage in SAC-activated cells. For the prevention of mitotic slippage, concomitant inhibition of APC/C-Cdh1 may be effective for tumor therapy with mitotic spindle poisons in humans.     

Relation between leptin and estradiol levels in Egyptian lactating Arab mares during foaling heat

Sixteen Arab lactating mares belonging to Al-Zahraa Arab Horse Stud underwent two ultrasound examinations at 3 weeks interval starting from the day of demonstration of foaling heat. In addition, daily blood samples were collected from parturition until after exhibiting first postpartum estrus (day 11) with daily observation of estrous signs. Both leptin and estradiol hormones were assayed. Mean day of foaling heat was 8.9 ± 0.9 day. Most mares came in foaling heat during days 9 and 10 had high conception rate compared to those who came in estrus earlier or later. Estradiol levels were high after day of foaling then decrease after expression of foaling heat. But leptin levels increase from day 8 to day 10 compared to other days before and after the first ovulation. A significant positive correlation was found between estradiol and leptin (r = 0.58, p < 0.025). The positive correlation between leptin and estradiol led us to suggest that leptin hormone plays an important role in ovulation of the first postpartum estrus in mares.     

Respiratory muscle dysfunction in mechanically-ventilated patients

The interaction between a patient and a ventilator is the major determinant of the amount of respiratory muscle rest achieved by the machine. We are beginning to acquire a better understanding of the mechanisms that underlie this complex interaction, but this information has yet to be integrated into the routine clinical management of ventilator-supported patients. To achieve that goal, we need better techniques of detecting and monitoring patient-ventilation asynchrony, and the development of simple algorithms that can minimize its occurence. Finally, research is needed to determine the occurrence and importance of respiratory muscle fatigue during failed weaning attempts so as to better guide the timing and pace of the weaning process in problematic patients.     

O-Heterocyclic Embeurekols from Embellisia eureka,an Endophyte of Cladanthus arabicus

Three new polyketides (-)-1 , (+)-1 , and 2 ) were isolated from the EtOAc extract of the fungus Embellisia eureka, an endophyte of the Moroccan plant Cladanthus arabicus (Asteraceae). The structures of these new compounds were determined on the basis of one- and two-dimensional NMR spectroscopy as well as by high-resolution mass spectrometry. The absolute configurations of (-)-1 , (+)-1 , and 2 were determined by TDDFT ECD calculations of solution conformers, online HPLC-ECD analysis, and the modified Mosher method. Chirality 25:250–256, 2013. © 2013 Wiley Periodicals, Inc.