Synthesis of polypeptides by microwave heating II. Function of polypeptides synthesized during repeated hydration-dehydration cycles

Summary Polypeptides, synthesized from a mixture of amino acid amides by microwave heating during repeated hydration-dehydration cycles, showed hydrolase- and oxidoreductase-like catalytic activities. Poly(GAVDH), polypeptides synthesized from an equimolar mixture (each 0.1 M) of glycinamide,l-alaninamide,l-valinamide,l-aspartic acid -amide, andl-histidinamide, catalyzed the hydrolysis of PNPAc. The hydrolytic rate of PNPAc with poly(GAVDH) was the quadruple of that ofl-histidine alone. Though the k_cat values of different resulting polypeptides were 10³–10⁶ times less than those of native hydrolases, the K_m value of the polypeptides further containing phenylalanine residues was nearly equal to that of the esterase. This result indicates the presence of hydrophobic interaction between a substrate and the polypeptides. Resulting polypeptides also showed catalytic activity for the reduction of ferricyanide ion [Fe(CN)^3–] with NADH. The polypeptides seemed to have a strong affinity for adenine nucleotides, because the reaction was inhibited by adenine derivatives such as NAD⁺ and AppA. A hypothesis for the emergence of primitive protein enzymes is discussed.     

An AP site can protect against the mutagenic potential of 8-oxoG when present within a tandem clustered site in E. coli

Ionizing radiation induces clustered DNA damaged sites, defined as two or more lesions formed within one or two helical turns of the DNA through passage of a single radiation track. It is now established that clustered DNA damage sites are found in cells and present a challenge to the repair machinery of the cell but to date, most studies have investigated the effects of bi-stranded lesions. A subset of clustered DNA damaged sites exist in which two or more lesions are present in tandem on the same DNA strand. In this study synthetic oligonucleotides containing an AP site 1, 3 or 5 bases 5' or 3' to 8-oxo-7,8-dihydroguanine (8-oxoG) on the same DNA strand were synthesized as a model of a tandem clustered damaged sites. It was found that 8-oxoG retards the incision of the AP site by exonuclease III (Xth) and formamidopyrimidine DNA glycosylase (Fpg). In addition the rejoining of the AP site by xrs5 nuclear extracts is impaired by the presence of 8-oxoG. The mutation frequency arising from 8-oxoG within a tandem clustered site was determined in both wild type and mutant E. coli backgrounds. In wild-type, nth, fpg and mutY null E. coli, the mutation frequency is slightly elevated when an AP site is in tandem to 8-oxoG, compared with when 8-oxoG is present as a single lesion. Interestingly, in the double mutant mutY/fpg null E. coli, the mutation frequency of 8-oxoG is reduced when an AP site is present in tandem compared with when 8-oxoG is present as a single lesion. This study demonstrates that tandem lesions can present a challenge to the repair machinery of the cell.     

Commissural ring nerve: A female-specific neurosecretory tract supplied by bifurcating median neurons in the cockroach Periplaneta americana (L.) and the cricket Teleogryllus commodus (Walker)

Summary In the American cockroach, Periplaneta americana, and the Australian field cricket, Teleogryllus commodus, the two nerves supplying the bases of the cerci are joined by a branch that crosses behind the last abdominal ganglion. This commissural ring nerve is restricted to females, and it contains many axons filled with granular and agranular vesicles. The axons stem from somata located within the ganglion. There are one (Periplaneta) or two (Teleogryllus) groups of median neurons with bilaterally symmetrical bifurcations, and a group of postero-ventral neurons on each side. In T. commodus, these neurons are distinct from others associated with the cerci. In the two species, the ring nerve neurons contribute to a neuropile near the root of each cereal nerve. The bifurcating median neurons arborize on both sides before entering the ring nerve, while the postero-ventral ones branch more extensively ipsilateral to their somata. The possibilities are discussed that the bifurcating neurons may be homologous to dorsal unpaired median neurons, and that the ring nerve may be a neurohemal area.     

Determination of platinated purines in oligoribonucleotides by limited digestion with ribonucleases T1 and U2

Platinum complexes which are known to react preferentially with guanine (G) and adenine (A) bases of oligonucleotides can be used as tools to analyze their tertiary structures and eventually to cross-link them. However, this requires efficient methods to allow the identification and quantification of the corresponding adducts which have so far been developed only for oligodeoxyribonucleotides. Maxam-Gilbert type digestions cannot be used for RNAs and HPLC techniques would require too large amounts of expensive material for separation and further characterization. We report a method to determine platination sites on oligoribonucleotides based on the cleavage activity of ribonucleases T1 and U2. To test the method, these enzymes were first used under conditions of limited digestion on 5-mer oligoribonucleotides platinated at a single defined purine. The phosphodiester bond on the 3^′ side of platinated G or A appeared fully resistant to cleavage by ribonuclease T1 or U2, respectively. An inhibitory effect was also observed due to neighboring platinated purines, which decreases with their distance (−2, −1, +1, +2) from the cleavage site and with the enzyme concentration. The method allowed the identification and quantification of the platination sites of a 17-mer oligoribonucleotide, based on the analysis of the mixture of monoplatinated adducts.     

Ultrafine Pt Nanoparticle‐Decorated Pyrite‐Type CoS2 Nanosheet Arrays Coated on Carbon Cloth as a Bifunctional Electrode for Overall Water Splitting

To improve the utilization efficiency of precious metals, metal‐supported materials provide a direction for fabricating highly active and stable heterogeneous catalysts. Herein, carbon cloth (CC)‐supported Earth‐abundant CoS₂ nanosheet arrays (CoS₂/CC) are presented as ideal substrates for ultrafine Pt deposition (Pt‐CoS₂/CC) to achieve remarkable performance toward the hydrogen and oxygen evolution reactions (HER/OER) in alkaline solutions. Notably, the Pt‐CoS₂/CC hybrid delivers an overpotential of 24 mV at 10 mA cm^?2 and a mass activity of 3.89 A Pt_mg^?1, which is 4.7 times higher than that of commercial Pt/C, at an overpotential of 130 mV for catalyzing the HER. An alkali‐electrolyzer using Pt‐CoS₂/CC as a bifunctional electrode enables a water‐splitting current density of 10 mA cm^?2 at a low voltage of 1.55 V and can sustain for more than 20 h, which is superior to that of the state‐of‐the‐art Pt/C+RuO₂ catalyst. Further experimental and theoretical simulation studies demonstrate that strong electronic interaction between Pt and CoS₂ synergistically optimize hydrogen adsorption/desorption behaviors and facilitate the in situ generation of OER active species, enhancing the overall water‐splitting performance. This work highlights the regulation of interfacial and electronic synergy in pursuit of highly efficient and durable supported catalysts for hydrogen and oxygen electrocatalytic applications.     

Pathogenesis of barley leaves by Helminthosporium teres I: Green island formation and the possible involvement of cytokinins

Infection sites/green islands were formed in host leaf tissue infected with drops of H. teres. They exhibited higher cytokinin-like activity, sugar and starch than their surrounding tissue and tissue under water drops. The cytokinin-like activity at the infection sites increased from 24 to 72 h of incubation. However, the cytokinin-like activity of the tissue surrounding the infection drops and the tissue under water drops fell from 24 to 72 h incubation. The culture filtrate extracts of the fungus also produced cytokinin-like activity which increased from 1 to 10 days incubation. Application of this culture filtrate extract evoked green island formation. Application of kinetin to host leaves duplicated the green island effect. Thin-layer chromatographic fractions of the tissue extracts and the culture filtrate extracts revealed that a major portion of cytokinin-like activity corresponded to zeatin and zeatin riboside. The presence of zeatin and zeatin riboside (both in tissue and culture filtrate extracts) was confirmed by high performance liquid chromatography. Increases in the amounts of cytokinin-like substances, particularly zeatin and zeatin riboside, attributed to pathogen influence are suggested to be involved in infection and pathogenicity of H. teres.     

Translocations,conservation, and climate change: use of restoration sites as protorefuges and protorefugia

High levels of human activity have affected the quality and usability of the natural landscape, leading to habitat degradation, loss of connectivity between sites, and reduced chances of long‐term survival for individual species. In line with conservation policy, ecological restoration practitioners try to improve degraded sites by means of reestablishing species lost from these sites, thereby returning ecological functionality and maintaining biological diversity. It may appear difficult to integrate the long‐term potential impacts of climate change within restoration strategies. However, more refined climate projections and species distribution models provide us with better understanding of likely scenarios, enabling us to consider future proofing as an integral part of the design of restoration sites, aiding plant conservation. We believe that it is possible to go one step further with a closer integration of restoration and conservation objectives. We introduce the novel concepts of “protorefuges” and “protorefugia”—restoration sites that threatened species can be translocated to, where the restoration design can be specifically adapted to help reduce the decline of threatened species at the leading and trailing edges (respectively) of bioclimatic envelope shifts. This is particularly relevant for nuclear decommissioning sites, which may be free from human activity for decades to centuries.     

The relationship among primary anatomic subsite and risk and distribution of second malignant neoplasms in patients with stage I/II diffuse large B-cell lymphoma: An analysis of the surveillance,epidemiology, and end results database

BackgroundRecent studies have reported that diffuse large B-cell lymphoma (DLBCL) involving different primary extranodal sites have distinct clinicopathological characteristics and prognosis. However, the risk of secondary malignant neoplasms (SMNs) in DLBCL survivors with different primary extranodal sites are unknown.MethodsA total of 40,714 patients diagnosed with stage I/II DLBCL were included from the Surveillance, Epidemiology, and End Results (SEER) database from 1983 to 2015.The standardized incidence ratio (SIR) and absolute excess risk (AER) were used to assess the risk of SMNs.ResultsThe results show that the risk of SMN was significantly higher in extranodal DLBCL than in the US general population (SIR, 1.18; 95% CI, 1.11–1.26), and the risk of developing SMN remains significantly elevated with increased latency. Moreover, there were multiple site-specific risk patterns. There was a 22%, 44%, 66%, 123% and 151% increased risk of SMN 10 years after primary gastrointestinal tract, head/neck, skeletal, lung and liver/pancreas DLBCL diagnosis, respectively. There was a significant decrease risk of SMN with increasing age at diagnosis for primary gastrointestinal tract and skeletal DLBCL. In addition, DLBCL patients with primary sites in the gastrointestinal tract, thyroid and liver/pancreas had the highest incidences of secondary stomach cancer, second thyroid cancer, and second hepatobiliary cancer, respectively, which indicated that the initial site of DLBCL may predict the type of SMN.ConclusionsThe strategies for cancer surveillance after extranodal DLBCL diagnosis may need to be individualized according to the subsite of extranodal DLBCL.     

Structure based prediction of functional sites with potential inhibitors to Nudix enzymes from disease causing microbes

The functional sites were predicted for Nudix enzymes from pathogenic microorganisms such as Streprococcus pneumonia (2B06) and Enterococcus faecalis (2AZW). Their structures are already determined, however, no data is reported about their functional sites, substrates and inhibitors. Therefore, we report prediction of functional sites in these Nudix enzymes via Geometric Invariant (GI) technique (Construct different geometries of peptides which remain unchanged). The GI method enumerated 2B06: RA57, EA58, EA61, EA62 and 2AZW: RA62, EA63, EA66, EA67 as putative functional sites in these Nudix enzymes. In addition, the substrate was predicted via Molecular docking (Docking of substrates against whole structure of Nudix enzymes). The substrate ADP-Ribose was docked with the Nudix enzymes, 2B06 (Docking energy -15.68 Kcal/mol) and 2AZW (Docking energy -10.86 Kcal/mol) with the higher affinity and the lower docking energy as compared to other substrates. The residues EA62 in 2B06 and RA62 in 2AZW make hydrogen bonds with the ADP-ribose. Furthermore, we screened 51 inhibitor compounds against structures of 2B06 and 2AZW. The inhibitor compounds AMPCPR and CID14258187 were docked well as compared to other compounds. The compound CID14258187 was also in agreement with Lipinski rule of 5 for drug likeness properties. Therefore, our findings of functional sites, substrates and inhibitors for these Nudix enzymes may help in structure based drug designing against Streprococcus pneumonia and Enterococcus faecalis.     

Effects of phospholipases,proteases and neuraminidase on γ-hydroxybutyrate binding sites

Summary -Hydroxybutyric acid (GHB) is a natural compound of mammalian brain synthesized from GABA. The characteristics of its synthesis, transport, release, distribution and turnover, in addition to the presence of a high affinity binding site for this substance in brain are in favor of a modulator role for GHB. The effects of hydrolytic enzymes on the specific binding capacity of GHB have been studied in the present work. Phospholipases A₂ and C, neuraminidase and Pronase markedly decrease GHB binding to crude synaptosomal membranes from rat brain. This effect is time and enzyme concentration dependent. Trypsin, under the conditions employed, is less active. The inhibitory effects of phospholipases is correlated with phospholipid hydrolysis. Lysophospholipids, in the absence of bovine fatty acid free serum albumin partially inhibit GHB binding. The action of neuraminidase has been followed by sialic acid release and modifications of the ganglioside profile. The effects of phospholipase C and of neuraminidase are completely different to those on GABA binding sites. These results represent further data concerning the molecular existence of specific GHB binding sites on rat brain membranes.Abbreviations GHB -hydroxybutyrate - LPC L--lysophosphatidylcholine - LPE Lysophosphatidylethanolamine - PC Phosphatidylcholine - PE Phosphatidylethanolamine - BSA Bovine Serum Albumin