Search

This article explores the surface architecture formation on layered A3B6 semiconductors, such as In4Se3, InSe, and InTe, focusing on kinetics of surface roughness parameters, such as RMS, skewness and kurtosis, and power spectral density (PSD) under indium deposition studied through large-scale 1 × 1 µm2 and 150 × 150 nm2 scanning tunneling microscopy (STM) images analysis. Our findings reveal common kinetics of surface parameters across different crystals, suggesting fundamental similarities in their interface kinetics. Particularly, PSD analysis elucidates the role of low-frequency spatial structures, underscoring their significance in surface roughness kinetics to some extent independent of the specific layered crystal surface structure. [ABSTRACT FROM AUTHOR]

The studies of In nanosystem formation on (100) surface of In4Se3 were conducted applying analysis of STM data from 1 × 1µm2 areas considering the distribution of image pixels' height depending on the In deposition degree and kinetics of root mean square, skewness, kurtosis parameters. We have shown the possibility of highly-oriented 1D indium nanostructures' growth with the Volmer-Weber growth mode on In4Se3 (100) surface applied as template. The optimal conditions to obtain the most oriented nano wire like nanostructures is thermal-induced Volmer–Weber growth in successive cycles of indium deposition – heating with activation of the solid state dewetting process. [ABSTRACT FROM AUTHOR]

Sb2Te3 layered chalcogenide crystal's (0001) surface was applied for self-organizing of deposited indium nanostructures' arrays while solid state dewetting procedure. Sb2Te3 samples were characterized by XRD, XPS, LEED and STM/STS. STM shows that shape and spatial arrangement of indium induced 0 D nanostructures are consistent with the surface lattice symmetry. The fractal analysis of STM images of the (0001) Sb2Te3 and (0001) InSe surfaces, which are similar in symmetry, shows that distribution in size of indium nanostructures are almost the same under commensurate experimental conditions. The STS reveals correlation between indium coverage and quantity of DOS within energy gap of Sb2Te3. [ABSTRACT FROM AUTHOR]

Sperm maturation, as a process through which spermatozoa acquire the ability for motility activation and fertilization, is well‐known for many groups of animals. This process takes place in a taxon‐specific manner in different parts of male reproductive tract. In contrast to most fish with external fertilization, a large number of animals have internal fertilization where transit through the epididymis of the male reproductive tract is necessary for the completion of sperm maturation. Although Chondrichthyes are fishes, they exhibit internal fertilization and possess specific male genital anatomy that resembles mammals. The existence of sperm maturation in the epididymis of cartilaginous fishes has been proposed but has yet to be confirmed. In this study, we used mature ocellate river stingrays Potamotrygon motoro, as a representative of Chondrichthyes, collected during the natural spawning period and evaluated sperm motility parameters during transit through the male reproductive tract, and upon contact with uterine fluid. Our data demonstrate that spermatozoa acquire motility after transit through the epididymis and are stored in a motile state within a specific organ – the seminal vesicles. Moreover, these motile spermatozoa are able to increase their velocity under the influence of uterine fluid in the female reproductive tract. Sexually mature ocellate river stingrays (Potamotrygon motoro, representative of Chondrichthyes) possess specific features of male gametes: (1) their spermatozoa acquire motility after leaving the testes during the transit through the epididymis; (2) thereafter spermatozoa are stored in a motile state within a specific male organ – the seminal vesicles; and (3) these motile spermatozoa are able to change their motility parameters under the influence of uterine fluid in the female reproductive tract. Based on the changes in these parameters during sperm transit through the male reproductive tract and upon contact with uterine fluid, we have confirmed the occurrence of epididymal sperm maturation and suggested the occurrence of capacitation stage in ocellate river stingrays. [ABSTRACT FROM AUTHOR]

The actuality of the creation of new eco-friendly bio-based lubricants and hence a new generation of multifunctional additives to the them based on metals of life and bioligands has been substantiated. Methods for the synthesis of model complexes-additives of Mg(II), Cu(II) and Mo(IV) with β-dicarbonyl ligands and hydroxamic acids, the peculiarities of their molecular structure, and tribological properties in ethyl laurate solution (base oil of vegetable origin) are considered. It has been found that copper- and molybdenumcontaining antiwear additives affect the microstructure and composition of the surfaces and subsurface layers of the friction zone due to the penetration of their elements as impurities into depth of surface layer for the samples of friction pairs. [ABSTRACT FROM AUTHOR]

Fish speciation was accompanied by changes in the urogenital system anatomy. In evolutionarily modern Teleostei, male reproductive tracts are fully separated from the excretory system, while in evolutionarily ancient Chondrostei and Holostei, the excretory and reproductive tracts are not separated. Sturgeon post-testicular sperm maturation (PTSM) occurring as a result of sperm/urine mixing is phenomenologically well described, while, in holosteans, functional intimacy of seminal ducts with kidney ducts and the existence of PTSM still need to be addressed. In Lepisosteus platostomus (Holostei), sperm samples were collected from testes (TS), efferent ducts (EDS), and Wolffian ducts (WDS). While WDS was motile, no motility was found in TS and EDS. The existence of PTSM was checked by in vitro PTSM procedure. After TS and EDS incubation in seminal fluid from WDS, no more than 5% motile spermatozoa were observed in TS, whereas in EDS the motility percentage was up to 75%. Experimental dyeing of urogenital ducts in gars and sturgeons revealed some differences in the interconnection between sperm ducts and kidneys. It is concluded that post-testicular sperm maturation occurs in gars and suggests that infraclass Holostei occupies an intermediate evolutionary position between Teleostei and Chondrostei in the anatomical arrangement of the urogenital system., (© 2023. The Author(s).)

Regarding the sperm of cold-water fish, the contributions of different bioenergetic pathways, including mitochondrial respiration, to energy production at the spawning temperature and its adaptation at the maximum critical temperature (CTmax) are unclear. The roles of glycolysis, fatty acid oxidation, oxidative phosphorylation (OXPHOS) at 4 °C, and OXPHOS at 15 °C for energy production in burbot ( Lota lota ) spermatozoa were studied by motility and the oxygen consumption rate (OCR) (with and without pathway inhibitors and the OXPHOS uncoupler). At both temperatures, the effects of the inhibitors and the uncoupler on the motility duration, curvilinear velocity, and track linearity were insignificant; in addition, the OCRs in activation and non-activation media differed insignificantly and were not enhanced after uncoupler treatment. After inhibitor treatment in both media, OXPHOS was insignificantly different at the 2, 30, and 60 s time points at 4 °C but was reduced significantly at the 30 and 60 s time points after treatment with sodium azide at 15 °C. In conclusion, for burbot sperm at both the spawning temperature and the CTmax, the energy synthesized via OXPHOS during motility was insufficient. Therefore, the majority of the energy required to sustain motility was derived from pre-accumulated energy produced and stored during the quiescent state of the spermatozoa.

Sturgeon sperm maturation occurs outside the testes during the transit of testicular spermatozoa (TS) through the kidneys and the Wolffian ducts. A method of in vitro TS maturation in sterlet Acipenser ruthenus was used to investigate the effects of temperature and hormonal stimulation of spermiation on the ability of TS to complete this process. Spermatozoa motility parameters after in vitro maturation of testicular sperm, concentrations of sex steroid hormones and testis morphology were studied in three groups of sterlet: (1) after overwintering in ponds (OW), (2) adapted to spawning temperature (ST), and (3) adapted to spawning temperature with hormonal induction of spermiation (ST-HI). Blood plasma concentrations of testosterone, 11-ketotestosterone and 17,20β-dihydroxy-pregnenolone increased significantly after hormonal induction of spermiation (group ST-HI). In all groups, TS were not motile. After in vitro sperm maturation, motility was up to 60% only in group ST-HI. The data suggest that the ability of TS to be matured in vitro was not related to the environmental temperature, while hormonal stimulation of spermiation during the spawning season was an absolute requirement for optimal in vitro maturation.

The importance of reactive oxygen species and the antioxidant system in sperm biology has been recognized for different bony fishes but nothing is known in this regard for chondrichthyans. For the first time for cartilaginous fishes, the enzymatic antioxidant system was shown herein to be present in both fractions of sperm (spermatozoa and seminal fluid) collected from two different places (seminal vesicle and cloaca). In internally fertilizing freshwater ocellate river stingray, Potamotrygon motoro, the activity of superoxide dismutase and glutathione peroxidase was not changed upon sperm transition from the seminal vesicle to the cloaca. The activity of catalase was significantly increased for both sperm fractions at transition from the seminal vesicle to the cloaca (1.6 times for spermatozoa and 1.9 times for seminal fluid). The role of the sperm antioxidant system for different aspects of internal fertilization is discussed. The presented results are the initiatory step in uncovering the biochemical events of internal reproduction in Chondrichthyes.

Rationale: Glycolipids play important roles in many physiological processes - despite their commonly low abundance. This study summarizes selected data on the (glyco)lipid composition of sperm from different fish species., Methods: Lipid extraction of fish sperm was performed according to the procedure by Bligh and Dyer. The lipid composition of the organic extracts was analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) and electrospray ionization ion trap (ESI-IT)MS coupled to high-performance thin-layer chromatography (HPTLC)., Results: It was shown that sperm from carp, northern pike, rainbow trout and burbot contain high amounts of neutral and acidic glycosphingolipids as well as sulfoglycolipids. These particular lipids are presumably involved in reproduction requirements., Conclusions: Phospholipids and glycolipids in crude lipid extracts can be analyzed in parallel by MS coupled to TLC. The direct application of tandem mass spectrometry (MS/MS) helps to elucidate the glycolipid structure. Thus, compositional analysis can be performed very rapidly., (© 2020 The Authors. Rapid Communications in Mass Spectrometry published by John Wiley & Sons Ltd.)

Sturgeon spermatozoa are unique for their sustained motility. We investigated the relative importance of bioenergetic pathways in the energy supply of Siberian sturgeon Acipenser baerii spermatozoa during motile and immotile states. Spermatozoon motility and oxygen consumption rate (OCR) were analysed following exposure to inhibitors of oxidative phosphorylation (sodium azide, NaN 3 ), glycolysis (2-deoxy-D-glucose, DOG) and β-oxidation of fatty acids (sodium fluoride, NaF), and to an uncoupler of oxidative phosphorylation (carbonyl cyanide m-chlorophenyl hydrazine, CCCP). No significant difference in curvilinear velocity was observed after addition of these reagents to activation medium (AM) or nonactivation medium (NAM) for incubation. Incubation of spermatozoa in NAM containing CCCP or NaN 3 resulted in significantly decreased motility duration compared to controls. The OCR of sturgeon spermatozoa in AM (11.9 ± 1.4 nmol O 2 min -1 (10 9  spz) -1 ) was significantly higher than in NAM (8.2 ± 1.5 nmol O 2 min -1 (10 9  spz) -1 ). The OCR significantly declined with addition of NaN 3 to AM and NAM. No significant difference in motility parameters or OCR was observed with NaF or DOG. These results suggest active oxidative phosphorylation in both immotile and motile spermatozoa. Nevertheless, mitochondrial respiration occurring during motility is not sufficient to meet the high energy demands, and the energy required for sustained motility of Siberian sturgeon spermatozoa is derived from adenosine triphosphate accumulated during the quiescent state., (© 2020 The Fisheries Society of the British Isles.)

The lipid composition of sperm membranes is crucial for fertilization and differs among species. As the evolution of internal fertilization modes in fishes is not understood, a comparative study of the sperm lipid composition in freshwater representatives of externally and internally fertilizing fishes is needed for a better understanding of taxa-specific relationships between the lipid composition of the sperm membrane and the sperm physiology. The lipidomes of spermatozoa from stingray, a representative of cartilaginous fishes possessing internal fertilization, and sterlet, a representative of chondrostean fishes with external fertilization, have been studied by means of nuclear magnetic resonance (NMR), matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), electrospray MS, gas chromatography-(GC) MS, and thin-layer chromatography (TLC). NMR experiments revealed higher cholesterol content and the presence of phosphatidylserine in stingray compared to sterlet sperm. Unknown MS signals could be assigned to different glycosphingolipids in sterlet (neutral glycosphingolipid Gal-Cer(d18:1/16:0)) and stingray (acidic glycosphingolipid sulpho-Gal-Cer(d18:1/16:0)). Free fatty acids in sterlet sperm indicate internal energy storage. GC-MS experiments indicated a significant amount of adrenic acid, but only a low amount of docosahexaenoic acid in stingray sperm. In a nutshell, this study provides novel data on sperm lipid composition for freshwater stingray and sterlet possessing different modes of fertilization., Competing Interests: The authors declare no conflict of interest.

Influence of in vitro temperature on sperm antioxidant enzyme activity, thiobarbituric acid-reactive substance (TBARS) content and motility parameters was evaluated in sterlet Acipenser ruthenus and rainbow trout Oncorhynchus mykiss. Sperm activation was conducted at 4, 14 and 24 °C in both species. Duration of motility was significantly longer at 4 °C than at 14 and 24 °C in both species. At 60 s post-activation, the velocity of sterlet spermatozoa was highest at 24 °C. This trend continued to 420 s post-activation. In rainbow trout, at 10 s post-activation, the highest velocity was observed at 14 °C. Significantly higher catalase activity was seen at 4 °C in both species. No significant difference in spermatozoon superoxide dismutase activity among temperatures was observed. In sterlet, TBARS content was significantly higher at 24 °C compared to other temperatures, but, in rainbow trout, it was highest at 4 °C. The results presume species-specific level of antioxidant enzyme activity and TBARS content at studied temperatures.

Morphology of the urogenital system has evolved during fish speciation. Chondrostei (sturgeons and paddlefishes) possess an excretory system which is called "primitive" in that the sperm ducts enter the kidneys and share the excretory ducts where sperm is mixed with urine before it is released into the spawning environment. Further, in this group of fishes there are also physiological characteristics which are associated with these anatomical features where the mixing of sperm and urine is a prerequisite for the final sperm maturation rather than contamination. In the Holostei (gars and bowfins) which are closely related to the Chondrostei, sperm also naturally mixed with urine, but the physiological role of such mixing for sperm biology has not been described. In contrast, urinary and sperm ducts in the more evolved Teleostei are completely separate, and sperm and urine are not mixed before being released during spawning. Thus, urine constitutes an inappropriate environment which can be a source of problems when sperm is collected during fisheries practices. In this review, the consequences of such divergent conditions in the urogenital anatomy will be considered in relation to general features of fish sperm biology and in relation to aquaculture and fisheries practices., (Copyright © 2019 Elsevier Inc. All rights reserved.)

All extant groups of Elasmobranches have internal fertilization and the structure of the male reproductive organs is very specific: sperm passes from the internal organs via the cloaca, but the male copulating organ (clasper) is distant from the cloaca. This suggests that sperm can contact the surrounding medium before fertilization. Because of this involvement with the environment, external signaling in sperm motility activation could occur in these species even though their fertilization mode is internal. In this case, spermatozoa of Elasmobranches should hypothetically possess a specific structure and membrane lipid composition which supports physiological functions of the sperm associated with environmental tonicity changes occurring at fertilization. Additionally, sperm motility properties in these taxa are poorly understood. The current study examined sperm lipid composition and motility under different environmental conditions for the ocellate river stingray, Potamotrygon motoro, an endemic South America freshwater species. Sperm samples were collected from six mature males during the natural spawning period. Sperm motility was examined in seminal fluid and fresh water by light video microscopy. Helical flagellar motion was observed in seminal fluid and resulted in spermatozoon progression; however, when diluted in fresh water, spermatozoa were immotile and had compromised structure. Lipid class and fatty acid (FA) composition of spermatozoa was analyzed by thin layer and gas chromatography. Spermatozoa FAs consisted of 33 ± 1% saturated FAs, 28 ± 1% monounsaturated FAs (MUFAs), and 41 ± 1% polyunsaturated FAs (PUFAs), and a high content of n-6 FAs (32 ± 2%) was measured. These results allowed us to conclude that sperm transfer from P. motoro male into female should occur without coming into contact with the hypotonic environment so as to preserve potent motility. In addition, this unusual reproductive strategy is associated with specific spermatozoa structure and lipid composition. Low level of docosahexaenoic acid and relatively low PUFA/MUFA ratio probably account for the relatively low fluidity of freshwater stingray membrane and can be the main reason for its low tolerance to hypotonicity., (Copyright © 2019 Elsevier Inc. All rights reserved.)

The morphology of the reproductive system of acipenseriform fishes is quite different from that of teleostean species, but an associated unique physiological difference in male sturgeons was not discovered until recently; sperm of sturgeons passes through the kidneys then via Wolffian ducts into the environment rather that emptying directly through seminal ducts. The mixing of sperm with excretory products has been found to be a requisite for the capacity to be activated (maturation step) instead of being deleterious. In the current review we summarize results of studies performed in our laboratory on physiological processes involved in sturgeon sperm maturation, namely changes in: 1) ionic environment; 2) sensitivity of spermatozoa to calcium ions (Ca 2+ ); 3) antioxidant enzymes and proteolytic activities; and 4) content in macroergic phosphates arising during this maturation process. We also discuss taxa-specific aspects of sturgeon sperm maturation in relation to hormonal regulation of spermiation, and the unusual features of sturgeon sperm maturation relative to using testicular sturgeon sperm in aquaculture., (Copyright © 2017 Elsevier Inc. All rights reserved.)

In fish, sperm quality is frequently associated with sperm motility variables. The response of sperm motility to different temperatures varies among species and plasma membrane lipid composition may contribute to variations in findings in previous research. In the present study, sperm motility and lipid composition were analysed between motile or immotile carp Cyprinus carpio sperm at different in vitro temperatures (4, 14 and 24°C). The duration of the period over which sperm motility is sustained was longer at 4°C compared with 14 and 24°C; while sperm velocity was greatest at 24°C. Motile sperm had lesser proportions of 18:3 (n-3) and 22:6 (n-3) fatty acids at 24°C relative to immotile sperm. There was no difference in fatty acid composition of motile and immotile sperm at 4 and 14°C. The total phospholipid content was less in motile than in immotile sperm at 24°C. At 24°C, phosphatidylcholine and phosphatidylserine proportions were less in motile than immotile sperm. It is concluded that lipid composition of motile carp sperm is affected by temperature, with greater temperatures associated with reduced lipid content, elevation of sperm curvilinear velocity and a decreased duration of the period over which motility is sustained., (Copyright © 2017 Elsevier B.V. All rights reserved.)

In sturgeon, the acquisition of the potential for motility activation called spermatozoon maturation takes place outside testes. This process can be accomplished in vitro by pre-incubation of immature testicular spermatozoa in seminal fluid collected from fully mature Wolffian duct sperm. Addition of trypsin inhibitor to the pre-incubation medium disrupts spermatozoon maturation. There are no available data for the role of proteolysis regulators in fish spermatozoon maturation, while their role is recognized in mammalian sperm maturation. The present study evaluated the involvement of seminal fluid proteases and anti-proteolytic activity in the sterlet spermatozoon maturation process. Casein and gelatin zymography and quantification of amidase and anti-proteolytic activity were conducted in sturgeon seminal fluid from Wolffian duct sperm and seminal fluid from testicular sperm, along with spermatozoon extracts from Wolffian duct spermatozoa, testicular spermatozoa, and testicular spermatozoa after in vitro maturation. We did not find significant differences in proteolytic profiles of seminal fluids from Wolffian duct sperm and ones from testicular sperm. Zymography revealed differences in spermatozoon extracts: Wolffian duct spermatozoon extracts were characterized by the presence of a broad proteolytic band ranging from 48 to 41 kDa, while testicular spermatozoon extracts did not show such activity until after in vitro maturation. The differences in amidase activity coincided with these results. It may not be the levels of proteolytic and anti-proteolytic activity per se, but the alterations in their interactions triggering a cascade of signaling events, that is crucial to the maturation process.