Literatura académica sobre el tema "Sperm speed"

Sperm swimming performance affects male fertilization success, particularly in species with high sperm competition. Understanding how sperm morphology impacts swimming performance is therefore important. Sperm swimming speed is hypothesized to increase with total sperm length, relative flagellum length (with the flagellum generating forward thrust), and relative midpiece length (as the midpiece contains the mitochondria). We tested these hypotheses and tested for divergence in sperm traits in five island populations of Canary Islands chiffchaff (Phylloscopus canariensis). We confirmed incipient mitochondrial DNA differentiation between Gran Canaria and the other islands. Sperm swimming speed correlated negatively with total sperm length, did not correlate with relative flagellum length, and correlated negatively with relative midpiece length (for Gran Canaria only). The proportion of motile cells increased with relative flagellum length on Gran Canaria only. Sperm morphology was similar across islands. We thus add to a growing number of studies on passerine birds that do not support sperm morphology–swimming speed hypotheses. We suggest that the swimming mechanics of passerine sperm are sufficiently different from mammalian sperm that predictions from mammalian hydrodynamic models should no longer be applied for this taxon. While both sperm morphology and sperm swimming speed are likely under selection in passerines, the relationship between them requires further elucidation.

Previous work has demonstrated that genomic incompatibilities work together with ecologically divergent selection to promote and maintain reproductive isolation between incipient species (dwarf and normal) of lake whitefish ( Coregonus clupeaformis (Mitchill, 1818)). Whitefish spawn in groups with external fertilization, which creates conditions for strong sperm competition. In this study, we asked whether reduced sperm performance in hybrids from whitefish species-pair matings might contribute to postzygotic isolating mechanisms between these taxa. We examined two sperm traits, sperm swimming speed and flagellum length, in pure dwarf and normal whitefish and in their F1 and backcross hybrids. We observed significantly reduced sperm swimming speed in backcross but not in F1 hybrids. Sperm flagellum length was not significantly correlated with sperm swimming speed. These results demonstrate that F1 hybrids formed in nature should be capable of the same fertilization success as the parental species during sperm competition, everything else being equal. However, reduced sperm performance in the backcross generation is consistent with other evidence suggesting that genomic incompatibilities create a range of negative fitness effects in post-F1 whitefish hybrids and provides evidence for an additional postzygotic isolation mechanism involved in the incipient speciation of sympatric dwarf and normal whitefish.

Sperm preparation for intracytoplasmic sperm injection (ICSI) is described and the effect of high speed centrifugation during preparation on fertilization rate is evaluated. No significant differences were found in the 2-pronuclear or abnormal fertilization rates between sibling oocytes injected with sperm prepared by swim-up or mini-Percoll combined with high speed centrifugation. The high fertilization rate obtained with both methods indicates that high speed centrifugation is not necessary to prepare sperm for ICSI. Fertilization rates were also compared for sperm obtained from ejaculates, fresh and frozen epididymal aspirates, and testicular biopsies. High fertilization rates were obtained from all groups but they were significantly higher in those oocytes injected with epididymal sperm (78% per oocyte surviving injection). The high fertilization rate with epididymal sperm may reflect sperm quality or may result from the method of sperm preparation for injection. Fertilization after the injection of sperm from which the tail was dislodged during immobilization was compared with that obtained using intact sperm. A significantly lower rate of 2-pronuclear fertilization was found in those oocytes injected with sperm heads only (55%) compared with intact sperm (68%), although cleavage rates between the two groups were similar. The use of hypo-osmotic medium to select potentially live sperm from an immotile sample is also described and fertilization was obtained after the injection of sperm with a structural defect which were selected using this technique. These results indicate that high fertilization rates can be obtained with ejaculated, epididymal and testicular sperm without special treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Computer-assisted semen analysis systems insist on evaluating sperm characteristics. These systems afford capacity to study and evaluate sperm statistical and morphological characteristics such as concentration, morphology, and motility, which have an important role in diagnosis and treatment of male infertility. In this paper, the proposed algorithm allows the assessment of concentration and motility rate of sperms in microscopic videos. First, enhancement process is required because of microscopic images limitations such as low contrast and noises. Then, for true sperm recognition among noise and debris, a hybrid approach is proposed using a combination between segmentation techniques. After, the use of geometric features of the bounding ellipse of the sperm head led to define sperm concentration. Finally, inter-frame difference is applied for motile sperm detection. The proposed method was tested on microscopic videos of human semen; the performance of this method is analyzed in terms of speed, accuracy, and complexity. Obtained results during the experiments are very promising compared with those obtained by the traditional assessment, which is the most widely used and approved in the laboratories.

Sperm traits of externally fertilizing fish species are typically measured in fresh (or salt) water, even though the spawning environment of their ova contains ovarian fluid. In this study, we measured sperm traits of Chinook salmon ( Oncorhynchus tshawytscha (Walbaum in Artedi, 1792)) in both fresh water and dilute ovarian fluid at 10 and 20 s postactivation, using a computer-assisted sperm analysis system. Spermatozoa swam faster, and had both higher percent motility and a straighter path trajectory for a longer period of forward motility when activated in ovarian fluid compared with activation in fresh water. Comparing sperm activity of 10 males in water versus ovarian fluid, we found a weak but significant correlation for sperm swimming speed at 10 s postactivation (r = 0.34, p = 0.01), but not for any other sperm traits measured. Most important, across males, mean sperm swimming speed in water accounted for <10% of the observed variation in mean sperm swimming speed in ovarian fluid. Thus, we argue that sperm traits measured in fresh water are not particularly relevant to those same traits during normal spawning in this species. We suggest that sperm performance measured in fresh water should be used with caution when comparing the potential for individual males to fertilize ova, especially in studies of sperm competition in externally fertilizing species.

Spermatozoa vary enormously in their form and dimensions, both between and within species, yet how this variation translates into fertilizing efficiency is not known. Sperm swimming velocity is a key determinant of male fertilization success, but previous efforts to identity which sperm phenotypic traits are associated with swimming velocity have been unsuccessful. Here, we examine the relationship between the size of several sperm components and sperm swimming velocity in natural populations of red deer ( Cervus elaphus hispanicus ) where selective pressures to enhance male reproductive success are expected to be strong. Our results show that there is little within-male and considerable between-male variation in sperm dimensions. Spermatozoa with longer midpieces swim more slowly, a finding which does not support the hypothesis that the size of the midpiece determines the amount of energy which is translated into swimming speed. In contrast, spermatozoa with elongated heads, and those in which the relative length of the rest of the flagellum is longer, swim faster. Thus, the hydrodynamic shape of the head and the forces generated by the relative size of the rest of the flagellum seem to be the key determinants of sperm swimming velocity.

Theoretical models predict that subordinate males should have higher sperm velocity to compensate for their disadvantaged mating role and because they experience sperm competition more frequently than dominant males. Differences in mean velocity between sperm of dominants and subordinates in the predicted direction are also documented for a few species, including the Arctic char, Salvelinus alpinus (L., 1758). Yet, this difference in mean velocity does not imply that the fastest sperm within an ejaculate, which are those most likely to fertilize eggs, swim faster in subordinates than in dominants. We studied the 5% and 10% fastest sperm cells in ejaculates of dominant and subordinate Arctic char. Before individuals attained their status, there were no differences in velocity between the fastest sperm of males that later became dominant or subordinate. Yet, after establishment of social position, subordinates showed significantly higher sperm swimming speed of the fastest cells in the first 30 s post activation (i.e., at 15, 20, and 30 s post activation). Males that became subordinates showed no change in sperm speed of the fast cells compared with those at pre-trial levels, whereas males that became dominant reduced the speed of their sperm (15 s post activation) compared with those at pre-trial levels. Our results suggest that males which attain social dominance are unable to maintain high sperm velocity, even among the small fraction of the fastest cells.

Optical trapping is a non-invasive biophysical tool which has been widely applied to study physiological and biomechanical properties of cells. Using laser ‘tweezers’ in combination with custom-designed computer tracking algorithms, the swimming speeds and the relative swimming forces of individual sperm can be measured in real time. This combination of physical and engineering tools has been used to examine the evolutionary effect of sperm competition in primates. The results demonstrate a correlation between mating type and sperm motility: sperm from polygamous (multi-partner) primate species swim faster and with greater force than sperm from polygynous (single partner) primate species. In addition, sperm swimming force linearly increases with swimming speed for each species, yet the regression relating the two parameters is species specific. These results demonstrate the feasibility of using these tools to study rapidly moving (μm s −1 ) biological cells.

The measurement of sperm motility is critical when studying fertilization kinetics and chemotaxis. Analysis of motility has traditionally been carried out on cells in small fluid volumes on microscope slides. Several theoretical treatments suggest that drag forces significantly affect flagellar motion within 10 sperm body lengths of the slide surface. Understanding how sperm move in the absence of surface drag is crucial when considering natural locomotory patterns. To examine the effects of solid surfaces, motile sperm from sea urchins (Arbacia punctulata) were placed in a Plexiglas chamber (69 mmx45 mmx15.5 mm; length x width x height). A system was constructed to minimize convective flow by limiting temperature differences within the chamber to less than 0.1 degrees C. The movement of sperm was video-recorded at two levels: (3/4)100 micron (3 body lengths) and 5 mm (150 body lengths) below the chamber lid. When swimming speeds were measured using a computerized video motion-analysis system, a highly significant difference (P&lt;0. 0001) between cells at the two depths was found. Cells nearest the lid swam at 174.6+/-5.9 micron s-1 (mean +/- s.e.m.), whereas those farther away slowed to only 111.1+/-9.9 micron s-1 (mean +/- s.e.m.). Swimming speed was also found to be significantly (P&lt;0.01) affected by paternity, but not by sperm age. We conclude that viscous wall effects must be carefully considered in studies of sperm motility and chemotaxis. The analysis of sperm on a microscope slide may substantially exaggerate swimming speed.

Sperm competition favours an increase in sperm swimming velocity that maximises the chances that sperm will reach the ova before rival sperm and fertilise. Comparative studies have shown that the increase in sperm swimming speed is associated with an increase in total sperm size. However, it is not known which are the first evolutionary steps that lead to increases in sperm swimming velocity. Using a group of closely related muroid rodents that differ in levels of sperm competition, we here test the hypothesis that subtle changes in sperm design may represent early evolutionary changes that could make sperm swim faster. Our findings show that as sperm competition increases so does sperm swimming speed. Sperm swimming velocity is associated with the size of all sperm components. However, levels of sperm competition are only related to an increase in sperm head area. Such increase is a consequence of an increase in the length of the sperm head, and also of the presence of an apical hook in some of the species studied. These findings suggest that the presence of a hook may modify the sperm head in such a way that would help sperm swim faster and may also be advantageous if sperm with larger heads are better able to attach to the epithelial cells lining the lower isthmus of the oviduct where sperm remain quiescent before the final race to reach the site of fertilisation.

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This dissertation is based on the development of two separate scientific papers. (1) First article it is a scientometric analysis: In 2007 was released in the scientific means by Wilson-Leedy and Ingermann, the first article using the CASA free software in sperm mobility analysis for fish, for this study, from of scientometric techniques, the contribution has been assessed and the impact that the article caused the scientific community. It also evaluated the frequency in the number of publications using andrologic analysis in fish, from 2007 to 2014 in four magazines that publish articles related to this topic. Were evaluated under articles made soundness analysis in fish using any existing CASA system, the variables used and ways to interpret the results to determine the sperm viability and correlate the sperm motion parameters with the potential fertilization. For scientometry CASA launching the contribution in free software took place in the google scholar search to get all the work that had quoted the article. For scientometry of items with fish using CASA, was conducted using the search index of ScienceDirect. And to assess the variables and the interpretations made by the authors, harvest characteristics of the materials and methods and results in the articles. It was found 123 quotes Wilson-Leedy article and Ingermann these, 94 are articles, of which 66 were performed with fish, and 35 of these conducted their research using CASA in free software, and there was an increase of 85% in citing publications the author reference. In the search for articles that use in fish soundness analysis, an increase of 59.4% from 2007 to 2014. Of the publications articles using any home system for the assessment of sperm motility in fish, 75.76% of the two work assesses or more times the spermatic movement, 51.52% use at least four of the characteristics generated by CASA, about ¼ of the work validated the CASA results with fertilization and hatching of eggs and used statistical models to group correlated variables CASA and explanations them, less than 10% of articles explores statistical modeling in sperm kinetics and to explain the characteristics generated by CASA on sperm fertility. The article by Wilson-Leedy and Ingermann contributed to the advancement of research with fish sperm, and sperm was used in the evaluation of other animals and other cells also concluded that little is known of the relationship of some sperm variables generated by CASA with fertility sperm in fish. And the researchers do not use in full the resources of the CASA system. (2) According to an article this is an experiment of artificial reproduction: The objective of this study was to evaluate the interactive effects of the relationship or independent mobile sperm: oocyte and sperm speed on artificial reproduction procedures with the use of semen catfish (Rhamdia quelen) cryopreserved. Through the Computer Assisted Sperm Analysis (CASA) were evaluated in six replicates motility and sperm velocity of cryopreserved semen from eight seconds of its activation and to each according to the end of the spermatic movement. For the fertilization test an experimental design was used in a factorial (6x3x3) consists of six mobile sperm relations: oocyte (70,000, 90,000, 110,000, 130,000, 150,000 and 170,000), three sperm speeds (60, 40 and 20μm.s-1) and three experimental replicates or blocks (pools of oocytes from three groups of female). Activation curves of sperm (kinetic) have been prepared with the help of non-linear statistical model. The effects were evaluated on the fertilization, hatching and normal larvae. In evaluating the variables, the response surface analysis showed no interaction effect (p>0.05) between the relationship moving sperm: oocyte and sperm speed, on the fertilization rates, hatching and normal larvae. Only linear effect was found (p<0.05) of sperm speed under the fertilization rates and hatching eggs. According to the results, it is concluded that there is no difference between the use of 70,000 up to 170,000 mobile sperm for each oocyte on the reproductive success in terms of fertilization rate, hatching and larval normality of catfish (Rhamdia quelen) and that the value of the sperm velocity is decisive on the reproductive success of sperm catfish (Rhamdia quelen) decreasing the fertilization and hatching rates as decreases sperm speed.
Esta dissertação baseia-se na elaboração de dois artigos científicos distintos. (1) Primeiro artigo trata-se de uma análise cientométrica: Em 2007 foi lançado no meio cientifico por Wilson-Leedy e Ingermann, o primeiro artigo utilizando o CASA em software livre em análise de mobilidade espermática para peixes, para este estudo, a partir de técnicas cientométricas, foi avaliado a contribuição e o impacto que o artigo provocou na comunidade cientifica. Também foi avaliada a frequência no número de publicações utilizando analises andrológicas em peixes, desde 2007 à 2014 em quatro revistas que publicam artigos referentes a este tema. Foram avaliados sob artigos que realizaram analise andrológica em peixes utilizando algum sistema CASA existente, as variáveis utilizadas e as formas de interpretação dos resultados para determinar a viabilidade espermática e correlacionar os parâmetros de movimento espermático com o potencial de fertilização. Para a cientometria da contribuição do lançamento do CASA em software livre foi realizada busca no google acadêmico para levantar todos os trabalhos que haviam citado o artigo. Para a cientometria dos artigos com peixes utilizando o CASA, foi realizado busca utilizando o indexador da ScienceDirect. E para avaliar as variáveis e as interpretações realizadas pelos autores, colhemos suas características dos materiais e métodos e resultados nos artigos. Encontrou-se 123 citações do artigo de Wilson-Leedy e Ingermann destes, 94 são artigos, dos quais 66 foram realizados com peixes e, 35 destes realizaram suas pesquisas utilizando o CASA em software livre, e ocorreu um aumento de 85% nas publicações citando o autor referência. Na busca de artigos que utilizam analise andrológica em peixes, ocorreu um aumento de 59,4% das publicações de 2007 à 2014. Dos artigos que utilizam qualquer sistema CASA para a avaliação da mobilidade espermática em peixes, 75,76% dos trabalhos avalia dois ou mais tempos do movimento espermático, 51,52% utiliza pelo menos quatro das características geradas pelo CASA, aproximadamente ¼ dos trabalhos validou os resultados do CASA com fertilização ou eclosão dos ovos e usou modelos estatísticos para agrupar as variáveis correlacionadas do CASA e explica-las, menos de 10% dos artigos explora modelagem estatística na cinética espermática e para explicar as características gerados pelo CASA sobre a fertilidade espermática. O artigo de Wilson-Leedy e Ingermann contribuiu para o avanço das pesquisas com espermatozoides de peixes, e foi utilizado na avaliação espermática de outros animais e outras células, também concluímos que pouco se sabe da relação de algumas variáveis espermáticas geradas pelo CASA com a fertilidade espermática em peixes. E que os pesquisadores não utilizam em sua totalidade os recursos do sistema CASA. (2) Segundo artigo trata-se de um experimento de reprodução artificial: O objetivo deste estudo foi avaliar os efeitos interativos ou independentes da relação espermatozoides móveis:ovócito e da velocidade espermática em procedimentos de reprodução artificial com o uso do sêmen do jundiá (Rhamdia quelen) criopreservado. Através do Computer Assisted Sperm Analysis (CASA) foram avaliadas em seis réplicas a motilidade e a velocidade espermática do sêmen criopreservado a partir de oito segundos da sua ativação e a cada um segundo até o termino do movimento espermático. Para o ensaio de fertilização foi aplicado um delineamento experimental em esquema fatorial (6 x 3) composto de seis relações espermatozoides móveis:ovócito (70.000, 90.000, 110.000, 130.000, 150.000 e 170.000), três velocidades espermáticas (60, 40 e 20µm.s-1) e três réplicas ou blocos experimentais (pools de ovócitos provenientes de três grupos de fêmeas). As curvas de ativação dos espermatozoides (cinéticas) foram elaboradas com auxílio de modelo estatístico não linear. Os efeitos foram avaliados sobre as taxas de fertilização, eclosão e larvas normais. Na avaliação das variáveis, a análise de superfície de resposta não mostrou efeito interativo (p>0,05) entre a relação espermatozoides móveis:ovócito e as velocidades espermáticas, sobre as taxas de fertilização, de eclosão e de larvas normais. Somente foi encontrado efeito linear (p<0,05) da velocidade espermática sob as taxas de fertilização e de eclosão dos ovos. De acordo com os resultados, conclui-se que não há diferença alguma entre uso de 70.000 até 170.000 espermatozoides móveis para cada ovócito sobre o sucesso reprodutivo em termos de taxa de fertilização, eclosão dos ovos e normalidade larval do jundiá (Rhamdia quelen) e, que o valor da velocidade espermática é determinante sobre o sucesso reprodutivo dos espermatozoides de jundiá (Rhamdia quelen) diminuindo as taxas de fertilização e eclosão conforme diminui a velocidade espermática.

Thesis (M.S.)--University of Wisconsin--Madison, 1997.
Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 69-80).

Frost formation is of a major research interest as it can affect many industrial processes. Frost appears as a thin deposit of ice crystals when the temperature of the surface is below the freezing point of the liquid. The objective of this research is to study icing with hope to propose new anti-icing and deicing methods. In the beginning of the research, cracking of the ice layer was observed when a deionized water droplet impacts a ?50 oC cooled sphere surface that is in contact with dry ice. To further investigate the cracks occurrence, multiple experiments were conducted. It was observed that the sphere surface temperature and droplet temperature (ranges from 10-80 oC) have no effect on the crack formation. On the other hand, it was observed that formation of a thin layer of frost on the sphere before the drop impact leads the lateral cracking of the ice. Thus, attempts to reproduce the cracks on clean super cold sphere surfaces were made using scratched and sandblasted spheres as well as superhydrophobized and polymer particle coated spheres. Furthermore, innovative methods were tried to initiate the cracks by placing epoxy glue bumps and ice-islands coatings on the surface of the spheres. All of these attempts to reproduce the crack formation without the presence of frost, failed. Nonetheless, the adding of isolated frost on the sphere surfaces always leads to the crack formation. Generally, frost forms on the small spheres faster than it does on the bigger ones. Additionally, the cold water droplet produces thicker water and ice layer compared to a hot water droplet; and the smaller the sphere the larger its water and ice layer thicknesses.

This chapter deals with the controversial market of eggs and sperm. It examines how egg and sperm donors respond to variation in the organizational framing of paid donation—as either gift or job—and finds that it does have consequences for how individuals experience bodily commodification. Despite the fact that egg and sperm donors are alike in being motivated by the compensation, and they spend the money on similar things, they end up adopting gendered conceptualizations of what it is they are being paid to do. Women speak with pride about the huge gift they have given, while men consider donation to be a job, and some sperm donors even reference feelings of alienation and objectification.

Modes of development of marine crustaceans and other marine invertebrates include presence or absence of a larval stage, of larval feeding, and of maternal protection of offspring. These different developmental modes impose different compromises (trade-offs) between the number of offspring and their size or the extent of maternal protection. Crustaceans differ from many marine animals in not shedding eggs prior to fertilization, which eliminates the complication of selection on size of eggs as a target for sperm. Features shared with marine invertebrates of several phyla include rare and ancient origins of feeding larvae, irreversible losses of a feeding larval stage, a constraint on brooding imposed by embryos’ need for oxygen, and possible benefits from slower development of protected embryos. Crustaceans differ, however, in having a diverse exoskeletal tool kit that has provided unusual capabilities. Nauplii and zoeae are diverse in form, behavior, and habitat, despite each being nominally one type of larva. Nauplii, as feeding larvae, have adapted to both the benthos and plankton. Settling stages (cyprids and decapodids) with enhanced speed have evolved twice. Some very large adults can supply their large broods with oxygen. Capacity for defense of offspring and home has led a few times to eusociality. The need to molt to grow and change form imposes episodic risk and growth and, in some cases, links evolution of egg size and size at metamorphosis. Crustaceans’ diverse life histories enable comparisons with broad implications for marine invertebrates: opportunity for dispersal is similar for larvae and adults of some crustaceans, demonstrating that marine larvae need not be adaptations for dispersal; development from very small eggs is enabled by less equipment needed for first larval feeding and also by postlarval stages being parasites; eggs shed into the water suffer greater mortality than planktonic larvae or brooded eggs, yet some planktonic crustaceans depend on benthic resting eggs for persistence of populations; larvae escape predation in diverse ways, and bigger larvae are not consistently safer; predation near the seafloor makes settlement a risky stage. Parallels with other taxa are numerous, but the crustacean exoskeletal tool kit has conferred unusual evolutionary opportunities and constraints. Even among marine crustaceans, however, evolutionary options for life histories differ among clades because of rare evolutionary origins of traits of larvae and mothers and biased evolutionary transitions in those traits.

This chapter extends the discussion of surrogacy by focusing on how the people of Spey Bay thought about paying for bodily services and substances and what they felt this said about them as members of a community. People in Spey Bay do not think of money as inherently corrupting but hold individuals responsible for their own decisions about how they make and spend it. This chapter analyzes the views of the people of Spey Bay about blood, egg, and sperm donation in order to highlight the connections between community values and reproductive ethics, as well the circulation and meanings of money in their personal and professional lives. In doing so, it revisits questions about the contextual nature of ethics and the broad significance of reproduction in everyday life.

Microogranisms such as sperm and E. coli swim in a low-Reynolds number environment. In the zero-Reynolds-number Stokes limit, their kinematics are completely controlled by viscous forces and inertia is unimportant. This swimming environment is quite different from our usual (high Reynolds number) intuition about swimming. For example, due to the kinematic reversibility of Stokes flow, motions that look the same going forward and backward in time, such as the linear motion of an oar-like appendage, do not lead to net translation. Thus microorganisms in Newtonian fluids use swimming motions with a clear time-direction, such as the traveling waves or rotating corkscrew shapes of eukaryotic and bacterial flagella, respectively. While there has been much investigation of microorganism swimming in Newtonian fluids such as water, much less attention has been paid to swimming in complex materials, such as non-Newtonian, viscoelastic fluids and gels. However, in many cases microorganisms do in fact swim through such complex materials in their natural biological environments. For example, mammalian sperm swim through viscoelastic cervical mucus in the female reproductive tract, while H. pylori swim through the gastric mucus lining the inside of the stomach. In this talk I discuss two ways in which swimming through complex media differs from swimming in Newtonian fluids. First, the forces exerted by a viscoelastic medium are different from those exerted by a Newtonian fluid. I address how this affects swimming shapes and speeds of flexible swimmers such as sperm. Second, I discuss swimming through solids such as gels, where compressibility and heterogeneity become important.