In vitro effect of pulsed 900 MHz GSM radiation on mitochondrial membrane potential and motility of human spermatozoa

Ejaculated, density purified, human spermatozoa were exposed to pulsed 900 MHz GSM mobile phone radiation at two specific absorption rate levels (SAR 2.0 and 5.7 W/kg) and compared with controls over time. Change in sperm mitochondrial membrane potential was analysed using flow cytometry. Sperm motility was determined by computer assisted sperm analysis (CASA). There was no effect of pulsed 900 MHz GSM radiation on mitochondrial membrane potential. This was also the case for all kinematic parameters assessed at a SAR of 2.0 W/kg. However, over time, the two kinematic parameters straight line velocity (VSL) and beat-cross frequency (BCF) were significantly impaired (P < 0.05) after the exposure at SAR 5.7 W/kg and no exposure by time interaction was present. This result should not be ascribed to thermal effects, due to the cooling methods employed in the RF chamber and temperature control within the incubator.     

Laser-beam-triggered microcavitation: a novel method for selective cell destruction

We describe a new method of cell destruction that may have potential for use in antitumor therapy. Cells are loaded by phagocytosis with microparticles (<1 microm) and irradiated with short laser pulses. Absorption of laser energy by the microparticles causes localized vaporization of the fluid surrounding the microparticles, leading to the generation of transient vapor bubbles (microcavitation) around the microparticles. Using cultures of bovine aortic endothelial cells, we demonstrate that induction of intralysosomal microcavitation is an efficient, rapid and selective method of cell killing that is dependent on the number of microparticles, the number of laser pulses, and the fluence of the laser pulses. Cell killing by microcavitation is a very selective process that is restricted to cells containing microparticles, leaving other cells unaffected. Intracytoplasmic release of lysosomal hydrolases is, in part, responsible for cell death, because the protease inhibitors E64d and TLCK diminished cell killing. Using the broad-specificity caspase inhibitor Z-VAD-fmk, we determined that lysosomal hydrolases could induce apoptosis in a caspase-independent manner. We also examined the possibility of microcavitation-induced delayed effects in the cells that survived the treatment. Using flow cytometry, we determined that there was no delayed cell death between 1 and 4 days after microcavitation. Moreover, we did not observe changes in the cell cycle, in expression of the proteins BCL2, HSP70 and HSP27, or in PARP degradation. In conclusion, microcavitation induces rapid and specific cells death (limited only to cells containing microparticles), without producing delayed effects among the surviving cells.     

Social associations in common carp (Cyprinus carpio): Insights from induced feeding aggregations for targeted management strategies

Heterogeneity in social interactions can have important consequences for the spread of information and diseases and consequently conservation and invasive species management. Common carp (Cyprinus carpio) are a highly social, ubiquitous, and invasive freshwater fish. Management strategies targeting foraging carp may be ideal because laboratory studies have suggested that carp can learn, have individual personalities, a unique diet, and often form large social groups. To examine social feeding behaviors of wild carp, we injected 344 carp with passive integrated transponder (PIT) tags and continuously monitored their feeding behaviors at multiple sites in a natural lake in Minnesota, USA. The high‐resolution, spatio‐temporal data were analyzed using a Gaussian mixture model (GMM). Based on these associations, we analyzed group size, feeding bout duration, and the heterogeneity and connectivity of carp social networks at foraging sites. Wild carp responded quickly to bait, forming aggregations most active from dusk to dawn. During the 2020 baiting period (20 days), 133 unique carp were detected 616,593 times. There was some evidence that feeding at multiple sites was constrained by basin geography, but not distance alone. GMM results suggested that feeding bouts were short, with frequent turnover of small groups. Individual foraging behavior was highly heterogeneous with Gini coefficients of 0.79 in 2020 and 0.66 in 2019. “Superfeeders”—those contributing to 80% of total cumulative detections (top 18% and top 29% of foragers in 2020 and 2019 respectively)—were more likely to be detected earlier at feeding stations, had larger body sizes, and had higher network measures of degree, weighted degree, and betweenness than non‐superfeeders. Overall, our results indicate that wild carp foraging is social, easily induced by bait, dominated by large‐bodied individuals, and potentially predictable, which suggests social behaviors could be leveraged in management of carp, one of the world''s most recognizable and invasive fish.     

Conformational analysis of canonical 2-deoxyribonucleotides. 1. Pyrimidine nucleotides

The molecular structure and relative stability of north and south conformers of 2'-deoxyribonucleotides containing pyrimidine nucleic acid bases ( 2'-deoxythymidilic (pdT), 2'-deoxycytidilic (pdC) acids and their mono- and dianions) have been obtained and analyzed at the DFT/B3LYP level using the standard 6-31G(d) basis set. We have revealed that, when the nucleobase moiety is incorporated into the nucleotides, it maintains a nonplanar and nonrigid conformation due to out-of-plane deformation of the amino group and pyrimidine ring. It has been demonstrated that an increase of negative charge of the phosphate group results in increase of amino group pyramidalization, discrimination between conformers with syn and anti orientation of base with respect to sugar, strengthening of intramolecular C-H.O hydrogen bonds leading to deformation and fixation of geometry of nucleotides, and weakening of phosphodiester bond. These results allow to make suggestions about sources of twist and buckle deformations of base pairs, mechanisms of repaire of DNA via change of base orientation, and conditions for breakage of the P-O bonds during hydrolysis.     

Characterization of steroid hormone association with human plasma lipoproteins

Partition coefficient analysis, equilibrium dialysis, and computer simulation were used to evaluate associations of twelve steroid hormones (androstanediol, androstenediol, androstenedione, androsterone, dehydroepiandrosterone, dihydrotestosterone, estradiol, estriol, estrone, hydroxyprogesterone, progesterone, and testosterone) with human plasma high density lipoproteins (HDL), low density lipoproteins (LDL), and very low density lipoproteins (VLDL). It was determined that partitioning of steroid hormones (SH) between the aqueous medium and the surfaces of lipoproteins (LP) was the initial (first order) SH-LP interaction. For some SH, especially dehydroepiandrosterone, significant second order interactions, which may involve chemical conversions, were detected. The first order binding values of the twelve SH with three LP were combined with the corresponding binding values of SH with sex hormone-binding globulin, corticosteroid-binding globulin, and albumin in a 6 X 12 matrix. The computer program TRANSPORT was used to analyze the matrix and determine the distribution of each SH among six different binding agents in the "normal" male. It was concluded that LP are important vehicles for SH conveyance in plasma and may also be important for SH entry into cells.     

Efficient chemoenzymatic synthesis of globotriose and its derivatives with a recombinant alpha-(1-->4)-galactosyltransferase

A truncated alpha-(1-->4)-galactosyltransferase (LgtC) gene from Neisseria meningitidis was cloned. The recombinant glycosyltransferase was expressed in Escherichia coli BL21 (DE3) strain with high specific activity (5 units/mg protein). Its acceptor specificity was carefully characterized. Then the purified enzyme was utilized in highly efficient syntheses of globotriose and a variety of alpha-(1-->4)-galactosylated derivatives as potential antibacterial agents.     

Molecular determinants for antibody binding on group 1 house dust mite allergens

House dust mites produce potent allergens, Der p 1 and Der f 1, that cause allergic sensitization and asthma. Der p 1 and Der f 1 are cysteine proteases that elicit IgE responses in 80% of mite-allergic subjects and have proinflammatory properties. Their antigenic structure is unknown. Here, we present crystal structures of natural Der p 1 and Der f 1 in complex with a monoclonal antibody, 4C1, which binds to a unique cross-reactive epitope on both allergens associated with IgE recognition. The 4C1 epitope is formed by almost identical amino acid sequences and contact residues. Mutations of the contact residues abrogate mAb 4C1 binding and reduce IgE antibody binding. These surface-exposed residues are molecular targets that can be exploited for development of recombinant allergen vaccines.     

Estimation of melting points of large set of persistent organic pollutants utilizing QSPR approach

The presence of polyhalogenated persistent organic pollutants (POPs), such as Cl/Br-substituted benzenes, biphenyls, diphenyl ethers, and naphthalenes has been identified in all environmental compartments. The exposure to these compounds can pose potential risk not only for ecological systems, but also for human health. Therefore, efficient tools for comprehensive environmental risk assessment for POPs are required. Among the factors vital for environmental transport and fate processes is melting point of a compound. In this study, we estimated the melting points of a large group (1419 compounds) of chloro- and bromo- derivatives of dibenzo-p-dioxins, dibenzofurans, biphenyls, naphthalenes, diphenylethers, and benzenes by utilizing quantitative structure—property relationship (QSPR) techniques. The compounds were classified by applying structure-based clustering methods followed by GA-PLS modeling. In addition, random forest method has been applied to develop more general models. Factors responsible for melting point behavior and predictive ability of each method were discussed.     

AFM Imaging Reveals Topographic Diversity of Wild Type and Z Variant Polymers of Human α1-Proteinase Inhibitor

α₁-Proteinase inhibitor (antitrypsin) is a canonical example of the serpin family member that binds and inhibits serine proteases. The natural metastability of serpins is crucial to carry out structural rearrangements necessary for biological activity. However, the enhanced metastability of the mutant Z variant of antitrypsin, in addition to folding defect, may substantially contribute to its polymerization, a process leading to incurable serpinopathy. The metastability also impedes structural studies on the polymers. There are no crystal structures of Z monomer or any kind of polymers larger than engineered wild type (WT) trimer. Our understanding of polymerization mechanisms is based on biochemical data using in vitro generated WT oligomers and molecular simulations. Here we applied atomic force microscopy (AFM) to compare topography of monomers, in vitro formed WT oligomers, and Z type polymers isolated from transgenic mouse liver. We found the AFM images of monomers closely resembled an antitrypsin outer shell modeled after the crystal structure. We confirmed that the Z variant demonstrated higher spontaneous propensity to dimerize than WT monomers. We also detected an unexpectedly broad range of different types of polymers with periodicity and topography depending on the applied method of polymerization. Short linear oligomers of unit arrangement similar to the Z polymers were especially abundant in heat-treated WT preparations. Long linear polymers were a prominent and unique component of liver extracts. However, the liver preparations contained also multiple types of oligomers of topographies undistinguishable from those found in WT samples polymerized with heat, low pH or guanidine hydrochloride treatments. In conclusion, we established that AFM is an excellent technique to assess morphological diversity of antitrypsin polymers, which is important for etiology of serpinopathies. These data also support previous, but controversial models of in vivo polymerization showing a surprising diversity of polymer topography.