Left-handed helix conformation of poly-L-proline II type in globular proteins. Statistics of incidence and a role of sequence]

Regions of left-handed polyproline II type conformation in globular proteins were studied throughout the PDB bank. The length and sequence of corresponding fragments were analyzed. It was found that a lot of tetrapeptides (from combinatorial possible ones) show the tendency to be included in the left-handed helices. Much more tetrapeptides do not occur in this structure type.     

Simple methods of enzymatic amplification of DNA for clinical practice]

The methods for enzymatic DNA amplification in vitro that allow to avoid the step of preliminary DNA extraction and purification are proposed. Lysates of blood cells in the solution or immobilized on the nylon membrane filters and dried blood spots on the filter paper blotters were used directly in amplification permitting one to solve the problems of adapting the method of polymerase chain reaction in clinical practice, for instance, in massive screening of genome mutations, viral infections etc.     

Cloning and characteristics of recA gene in Pseudomonas aeruginosa

A recA-like gene from Pseudomonas aeruginosa was cloned and identified by means of interspecific complementation of gene recA repair defect in Escherichia coli. The gene was mapped in the PvuII-HindIII Ps. aeruginosa chromosome fragment of 1.5 kbp in length. Having been recloned in pUC18 or 19 plasmids in either of possible orientations, this fragment was shown to complement three different defects of E. coli recA mutants: in repair, recombination and SOS functions.     

Cloning and regulation of gene expression of EcoRV restriction- modification system

A number of recombinant plasmids, containing EcoRV restriction-modification genes have been constructed. Individual genes of this system were introduced into plasmids of various incompatibility groups. Promoter regions of genes encoding methylase and restrictase have been cloned and studied. With the use of specialized vector pVE8 it was shown that the efficiency of the endonuclease gene promoter is comparable with early lambda phage promoters and produced about 70% of PL efficiency. The efficiency of the methylase gene promoter region was twice less than the efficiency of the restriction endonuclease gene promoter. Plasmid with restriction endonuclease gene promoter located downstream in relation to the additional regulatable phage lambda promoter PL has been obtained. It enabled us to construct strains 30-40 fold overproducing this enzyme under conditions of inactivation of the temperature sensitive phage repressor c1857. This construction directs the production of a high level (10%) of the total cellular soluble proteins) of the EcoRV restriction enzyme. The factors that influenced the level of enzyme synthesis under induction are discussed.     

Big flies, small repeats: the "Thr-Gly" region of the period gene in Diptera

The region of the clock gene period (per) that encodes a repetitive tract of threonine-glycine (Thr-Gly) pairs has been compared between Dipteran species both within and outside the Drosophilidae. All the non- Drosophilidae sequences in this region are short and present a remarkably stable picture compared to the Drosophilidae, in which the region is much larger and extremely variable, both in size and composition. The accelerated evolution in the repetitive region of the Drosophilidae appears to be mainly due to an expansion of two ancestral repeats, one encoding a Thr-Gly dipeptide and the other a pentapeptide rich in serine, glycine, and asparagine or threonine. In some drosophilids the expansion involves a duplication of the pentapeptide sequence, but in Drosophila pseudoobscura both the dipeptide and the pentapeptide repeats are present in larger numbers. In the nondrosophilids, however, the pentapeptide sequence is represented by one copy and the dipeptide by two copies. These observations fulfill some of the predictions of recent theoretical models that have simulated the evolution of repetitive sequences.      

Evolutionary origin of human and primate malarias: evidence from the circumsporozoite protein gene

We have analyzed the conserved regions of the gene coding for the circumsporozoite protein (CSP) in 12 species of Plasmodium, the malaria parasite. The closest evolutionary relative of P. falciparum, the agent of malignant human malaria, is P. reichenowi, a chimpanzee parasite. This is consistent with the hypothesis that P. falciparum is an ancient human parasite, associated with humans since the divergence of the hominids from their closest hominoid relatives. Three other human Plasmodium species are each genetically indistinguishable from species parasitic to nonhuman primates; that is, for the DNA sequences included in our analysis, the differences between species are not greater than the differences between strains of the human species. The human P. malariae is indistinguishable from P. brasilianum, and P. vivax is indistinguishable from P. simium; P. brasilianum and P. simium are parasitic to New World monkeys. The human P. vivax-like is indistinguishable from P. simiovale, a parasite of Old World macaques. We conjecture that P. malariae, P. vivax, and P. vivax-like are evolutionarily recent human parasites, the first two at least acquired only within the last several thousand years, and perhaps within the last few hundred years, after the expansion of human populations in South America following the European colonizations. We estimate the rate of evolution of the conserved regions of the CSP gene as 2.46 x 10(-9) per site per year. The divergence between the P. falciparum and P. reichenowi lineages is accordingly dated 8.9 Myr ago. The divergence between the three lineages leading to the human parasites is very ancient, about 100 Myr old between P. malariae and P. vivax (and P. vivax-like) and about 165 Myr old between P. falciparum and the other two.      

Excitation of System I and System II in Photosynthesis as a Possible Control Mechanism of Glycolate Metabolism in the Blue-Green Alga Anacystis nidulans

Photosynthetic enhancement studies performed at 619 nm (excitation of Systems I and II) and at 446 nm (mainly excitation of System I) revealed an 18% photosynthetic enhancement simultaneously with a 31% reduction in glycolate excretion. This observation supports the hypothesis that some glycolate may be consumed in an oxidation process associated with System I when System II is poorly excited and the supply of electrons from the water splitting process of photosynthesis is low.     

The anabolic action of intermittent parathyroid hormone on cortical bone depends partly on its ability to induce nitric oxide‐mediated vasorelaxation in BALB/c mice

There is strong evidence that vasodilatory nitric oxide (NO) donors have anabolic effects on bone in humans. Parathyroid hormone (PTH), the only osteoanabolic drug currently approved, is also a vasodilator. We investigated whether the NO synthase inhibitor L‐NAME might alter the effect of PTH on bone by blocking its vasodilatory effect. BALB/c mice received 28 daily injections of PTH[1–34] (80 µg/kg/day) or L‐NAME (30 mg/kg/day), alone or in combination. Hindlimb blood perfusion was measured by laser Doppler imaging. Bone architecture, turnover and mechanical properties in the femur were analysed respectively by micro‐CT, histomorphometry and three‐point bending. PTH increased hindlimb blood flow by >30% within 10 min of injection (P < 0.001). Co‐treatment with L‐NAME blocked the action of PTH on blood flow, whereas L‐NAME alone had no effect. PTH treatment increased femoral cortical bone volume and formation rate by 20% and 110%, respectively (P < 0.001). PTH had no effect on trabecular bone volume in the femoral metaphysis although trabecular thickness and number were increased and decreased by 25%, respectively. Co‐treatment with L‐NAME restricted the PTH‐stimulated increase in cortical bone formation but had no clear‐cut effects in trabecular bone. Co‐treatment with L‐NAME did not affect the mechanical strength in femurs induced by iPTH. These results suggest that NO‐mediated vasorelaxation plays partly a role in the anabolic action of PTH on cortical bone. © 2016 The Authors. Cell Biochemistry and Function published by John Wiley & Sons, Ltd.