Increased incidence of developmental anomalies among descendants of carriers of methylenebisacrylamide-induced balanced reciprocal translocations

N,N'-Methylenebisacrylamide (MBA), a dimer of the monomeric acrylamide, was studied for induction of clastogenic effects in germ cells of male mice. It was found to be effective in inducing dominant-lethal mutations and heritable translocations in maturing sperm. The semisterile translocation carriers and their normal counterparts were used to determine the health impact of transmitted chromosomal rearrangements through anatomical analysis of their immediate descendants in utero. As expected, semisterility resulted primarily from embryonic death during the periimplantation stages presumably caused by sperm segregants with unbalanced chromosome complement fertilizing some of the eggs. Among conceptuses that survived to mid- and late-gestation stages, there was an increased incidence of developmental anomalies including fetal death and phenotypic defects. These anomalies are assumed to be caused by certain types of unbalanced segregants that are compatible with survival beyond the periimplantation period. This class of unbalanced segregants represent in humans a major health problem to the mother and her conceptus.     

Blockade of alpha-adrenergic receptors by analogues of phosphatidylcholine

The experimental evidence reviewed in this article suggests that the kidneys may have an additional function in regulating blood pressure besides their role in controlling both blood volume by urine formation and the relative state of vasoconstriction by the renin-angiotensin system. That is, the kidneys may have an additional influence upon the vasculature of a hormonal vasodilating system. The interstitial cells of the renal medulla appear to be mediating this activity and lipid compounds have been extracted from the renal medulla which display depressor activity. One such compound, the antihypertensive polar renomedullary lipid (APRL), has been demonstrated to consist of specific alkyl ether analogues of phosphatidylcholine. The vascular responses to these compounds include vasodilation of both arterioles and venules, rapid lowering of arterial blood pressure with little or no tachycardia, increased depressor activity in hypertensive animals, and blockade of vascular smooth muscle alpha 1-adrenergic receptors. Most recently, APRL and a synthetic analogue, 1-0-octadecyl-2-acetyl-sn-glycero-3-phosphorylcholine, have been used to demonstrate alpha-adrenergic receptor blockade on a smooth muscle cell line (DDT1) by radioligand assays. This action may be due to the insertion of these compounds into cell membranes causing subsequent steric interactions and blockade of the alpha-adrenergic receptor.     

Specific binding sites for prohormone atrial natriuretic peptides 1-30, 31-67 and 99-126

Two peptides with vasodilatory properties consisting of amino acids 1-30 and 31-67 of the 98 a.a. N-terminal end of the prohormone of atrial natriuretic factor (proANF) which circulates in man were investigated to determine if they have specific binding sites on membranes isolated from DDT1 MF-2 smooth muscle cells. Smooth muscle is a known biologic target of these peptides. Competitive binding experiments revealed that proANFs (1-30), (31-67), and (99-126) (i.e., C-terminus; ANF) each had specific and separate binding sites. The dissociation constants for proANFs (1-30), (31-67), and (99-126) binding were 0.11 nM, 4 nM, and 7.3 nM, respectively. The binding site concentrations for proANFs (1-30), (31-67), and ANF were 2.57, 59.91 and 40 fmols/10(6) cells, respectively. The number of binding sites per cell were 1548, 36,087, and 24,090, respectively, for proANFs (1-30), (31-67), and (99-126) (ANF). Each peptide bound to DDT1 MF-2 membranes between 10(-8) to 10(-11) M but could only bind to the other peptides' receptors at concentrations of 10(-6) and 10(-7)M. These results suggest that proANF(1-30) and proANF(31-67) do not work through the ANF receptor but rather have their own separate and distinct receptors that mediate their biologic effects.     

Pitfalls in the sample preparation and analysis of N-acylethanolamines

N-acylethanolamines (NAEs) are a group of lipid mediators synthesized in response to a number of physiological and pathological stimuli. Because of the low tissue concentrations of NAEs, analyses often include liquid extraction followed by solid-phase extraction and subsequent quantitation by LC/MS or GC/MS. Reported levels of NAEs vary considerably, however, and often no explanation is given for these discrepancies. Brought on by difficulties encountered during method development, the effects of using four different brands of silica-containing solid phase extraction (SPE) columns and five different brands of chloroform for sample preparation were investigated. Considerable variation in the retention and recoveries of seven NAEs and 2-arachidonoylglycerol existed between the SPE columns. Furthermore, it was found that some chloroforms contained quantifiable amounts of N-palmitoylethanolamine and N-stearoylethanolamine. Finally, it was found that use of one of the chloroforms resulted in a loss of N-oleoylethanolamine from solution due to addition of chlorine to the ω-9 bond. The identity of this reaction product was confirmed by LC-MS/MS and NMR. It is recommended that these aspects of sample preparation and analysis should be thoroughly validated during method development and the relevant information on specific brands used be reported in future communications in order to better estimate the validity of reported quantitative data.     

Starch-binding domain shuffling in Aspergillus niger glucoamylase

Aspergillus niger glucoamylase (GA) consists mainly of two forms, GAI [from the N-terminus, catalytic domain + linker + starch-binding domain (SBD)] and GAII (catalytic domain + linker). These domains were shuffled to make RGAI (SBD + linker + catalytic domain), RGAIDeltaL (SBD + catalytic domain) and RGAII (linker + catalytic domain), with domains defined by function rather than by tertiary structure. In addition, Paenibacillus macerans cyclomaltodextrin glucanotransferase SBD replaced the closely related A.niger GA SBD to give GAE. Soluble starch hydrolysis rates decreased as RGAII approximately GAII approximately GAI > RGAIDeltaL approximately RGAI approximately GAE. Insoluble starch hydrolysis rates were GAI > RGAIDeltaL > RGAI > GAE approximately RGAII > GAII, while insoluble starch-binding capacities were GAI > RGAI > RGAIDeltaL > RGAII > GAII > GAE. These results indicate that: (i) moving the SBD to the N-terminus or replacing the native SBD somewhat affects soluble starch hydrolysis; (ii) SBD location significantly affects insoluble starch binding and hydrolysis; (iii) insoluble starch hydrolysis is imperfectly correlated with its binding by the SBD; and (iv) placing the P.macerans cyclomaltodextrin glucanotransferase SBD at the end of a linker, instead of closely associated with the rest of the enzyme, severely reduces its ability to bind and hydrolyze insoluble starch.     

Molecular docking of potential inhibitors with the mTOR protein

The mTOR (mammalian or mechanistic Target of Rapamycin) is linked with oral cancer. Therefore, it is of interest to study the molecular docking-based binding of paclitaxel (a FDA approved drug for oral cancer) and its analogues with mTOR. Hence, we report the binding features of 10-Deacetyltaxol, 7-Epi-10-deacetyltaxol, 7-Epi-Taxol and 6alpha-Hydroxypaclitaxel with mTOR for further consideration.     

The Influence of Antimicrobial Peptides and Mucolytics on the Integrity of Biofilms Consisting of Bacteria and Yeasts as Affecting Voice Prosthetic Air Flow Resistances

The integrity of biofilms on voice prostheses used to rehabilitate speech in laryngectomized patients causes unwanted increases in airflow resistance, impeding speech. Biofilm integrity is ensured by extracellular polymeric substances (EPS). This study aimed to determine whether synthetic salivary peptides or mucolytics, including N-acetylcysteine and ascorbic acid, influence the integrity of voice prosthetic biofilms. Biofilms were grown on voice prostheses in an artificial throat model and exposed to synthetic salivary peptides, mucolytics and two different antiseptics (chlorhexidine and Triclosan). Synthetic salivary peptides did not reduce the air flow resistance of voice prostheses after biofilm formation. Although both chlorhexidine and Triclosan reduced microbial numbers on the prostheses, only the Triclosan-containing positive control reduced the air flow resistance. Unlike ascorbic acid, the mucolytic N-acetylcysteine removed most EPS from the biofilms and induced a decrease in air flow resistance.     

Detecting non-neutral heterogeneity across a region of DNA sequence in the ratio of polymorphism to divergence

Natural selection, in the form of balancing selection or selective sweeps, can result in a decoupling of the amounts of molecular polymorphism and divergence. Thus natural selection can cause some areas of DNA sequence to have greater silent polymorphism, relative to divergence between species, than other areas. It would be useful to have a statistical test for heterogeneity in the polymorphism to divergence ratio across a region of DNA sequence, one that could identify heterogeneity greater than that expected from the neutral processes of mutation, drift, and recombination. The only currently available test requires that a region be arbitrarily divided into sections that are compared with each other, and the subjectivity of this division could be problematic. Here a test is proposed in which runs of polymorphic and fixed sites are counted, where a "run" is a set of one or more sites of one type preceded and followed by the other type. The number of runs is smaller than otherwise expected if polymorphisms are clumped together. By simulating neutral evolution and comparing the observed number of runs to the simulations, a statistical test is possible which does not require any a priori decisions about subdivision.      

MALDI imaging mass spectrometry: molecular snapshots of biochemical systems

Matrix-assisted laser desorption/ionization (MALDI) imaging mass spectrometry (IMS) is emerging as a powerful tool for investigating the distribution of molecules within biological systems through the direct analysis of thin tissue sections. Unique among imaging methods, MALDI-IMS can determine the distribution of hundreds of unknown compounds in a single measurement. We discuss the current state of the art of MALDI-IMS along with some recent applications and technological developments that illustrate not only its current capabilities but also the future potential of the technique to provide a better understanding of the underlying molecular mechanisms of biological processes.