Enhanced transcription of genes of the intracisternal A particles and B2 elements in mouse tumors

A comparison of the expression of two mobile genetic elements A1 and B2 was studied in normal and tumor tissues. The A1 element is a chromosomal homolog of IAP genes, and B2 is a short ubiquitous repetitive sequences of the mouse genome. These sequences were earlier cloned in our laboratory and in this study were used as probes in hybridization experiments with RNA isolated from different mouse tumor and normal tissues. Both elements were efficiently transcribed in tumor cells. The level of expression of A1 sequences in tumors was 100-200 times higher than in normal tissues. The amount of B2 small cytoplasmic RNA significantly varied in different normal tissues. The content of this RNA was much higher in tumors. Closed circular DNA molecules containing IAP sequences were found in Ehrlich carcinoma cells. These DNA molecules are considered as intermediate forms of the mobile elements. The role of these mobile elements in the regulation of RNA expression and tumor progression is 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.      

Long double-stranded sequences (dsRNA-B) of nuclear pre-mRNA consist of a few highly abundant classes of sequences: evidence from DNA cloning experiments.

DNA preparations from about hundred randomly selected clones containing mouse DNA fragments were screened for the existence of sequences complementary to long double-stranded regions of pre-mRNA able to snap back after melting (dsRNA-B). Many clones containing such sequences were found. The cloned sequences can be subdivided into three groups: (1) those complementary to about a half (at least to 30-40%) of the total dsRNA, designated as sequences B1; (2) those complementary to a part of sequence B1; and (3) sequences complementary to about a quarter (at least to 15%) of the total dsRNA referred to as sequence B2. The size of DNA sequence complementary to dsRNA is about 400 base pairs.Melting experiments with hybrids show that the members of B1 family are very similar if not identical, while the divergence among B2 sequences is higher, but still the number of substitutions does not exceed 9% of bases. Thus, the major part of dsRNA-B consists of a small number of highly abundant sequences as was suggested earlier on the basis of renaturation kinetics /1-3/. Sequences B1 and B2 are represented by many copies in the mouse genome and in pre-mRNA, and many of them probably do not form hairpin-like structures.     

Bov-B-mobilized SINEs in vertebrate genomes

Two new short retroposon families (SINEs) have been found in the genome of springhare Pedetes capensis (Rodentia). One of them, Ped-1, originated from 5S rRNA, while the other one, Ped-2, originated from tRNA-derived SINE ID. In contrast to most currently active mammalian SINEs mobilized by L1 long retrotransposon (LINE), Ped-1 and Ped-2 are mobilized by Bov-B, a LINE family of the widely distributed RTE clade. The 3' part of these SINEs originates from two sequences in the 5' and 3' regions of Bov-B. Such bipartite structure of the LINE-derived part has been revealed in all Bov-B-mobilized SINEs known to date (AfroSINE, Bov-tA, Mar-1, and Ped-1/2), which distinguishes them from other SINEs with only a 3' LINE-derived part. Structural analysis and the distribution of Bov-B LINEs and partner SINEs supports the horizontal transfer of Bov-B, while the SINEs emerged independently in lineages with this LINE.     

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.     

Phylogeny of the order Rodentia inferred from structural analysis of short retrotransposon B1

A large-scale study of short retroposon (SINE) B1 has been conducted in the genome of rodents from most of the known families of this mammalian order. The B1 nucleotide sequences of rodents from different families exhibited a number of characteristic features including substitutions, deletions, and tandem duplications. Comparing the distribution of these features among the rodent families, the currently discussed phylogenetic relationships were tested. The results of analysis indicated (1) an early divergence of Sciuridae and related families (Aplodontidae and Gliridae) from the other rodents; (2) a possible subsequent divergence of beavers (Castoridae); (3) a monophyletic origin of the group Hystricognathi, which includes several families, such as porcupines (Hystricidae) and guinea pigs (Caviidae); (4) a possible monophyletic origin of the group formed by the remaining families, including six families of mouselike rodents (Myodonta). Various approaches to the use of short retroposons for phylogenetic studies are discussed.     

Barley microgreen incorporation in diet-controlled diabetes and counteracted aflatoxicosis in rats

Increased environmental pollution and unhealthy lifestyle are blamed for escalated chronic diseases. Exposure to aflatoxins was recently suggested to have a role in the increased incidence of type 2 diabetes mellitus. Diet modification and consumption of different functional food are now gaining attention, especially in diabetes management. This study investigates the effect of a diet containing barley microgreen against diabetes induced by streptozotocin with or without aflatoxin administration in rats. Barley microgreen was rich in 3′-Benzyloxy-5,6,7,4′-tetramethoxyflavone (48.8% of total) followed by 5β,7βH,10α-Eudesm-11-en-1α-ol (18.46%). Streptozotocin injection and/or aflatoxin administration significantly elevated glucose level, decreased insulin level, decreased β-cell function, deteriorated liver and kidney function parameters, and induced oxidative stress in the liver. Histopathology revealed irregular small-sized islets and decreased area % of insulin-positive beta cells in the pancreas, hepatic degeneration, nephropathy, and neuropathy in diabetic and/or aflatoxin administered rats compared to control. Barley microgreen diet fed to diabetic rats with or without aflatoxin alleviated all evaluated parameters. Barley microgreen diet also ameliorated the toxic effect of aflatoxin. In conclusion, exposure to aflatoxin aggravated diabetes and its complication. The incorporation of barley microgreen in the diet was able to control type 2 diabetes mellitus and the improved outcomes observed with barley microgreen treatments involved or occurred in conjunction with improved biomarkers of oxidative stress.