scholarly journals Sperm head morphology is associated with sperm swimming speed: A comparative study of songbirds using electron microscopy

Evolution ◽  
2018 ◽  
Vol 72 (9) ◽  
pp. 1918-1932 ◽  
Author(s):  
Hanna Nyborg Støstad ◽  
Arild Johnsen ◽  
Jan Terje Lifjeld ◽  
Melissah Rowe
Keyword(s):  
Electron Microscopy ◽  
Comparative Study ◽  
Swimming Speed ◽  
Sperm Head ◽  
Sperm Swimming Speed ◽  
Head Morphology

scholarly journals Sperm competition differentially affects swimming velocity and size of spermatozoa from closely related muroid rodents: head first

Reproduction ◽  
2011 ◽  
Vol 142 (6) ◽  
pp. 819-830 ◽  
Author(s):  
Laura Gómez Montoto ◽  
María Varea Sánchez ◽  
Maximiliano Tourmente ◽  
Juan Martín-Coello ◽  
Juan José Luque-Larena ◽  
...  
Keyword(s):  
Sperm Competition ◽  
Swimming Speed ◽  
Comparative Studies ◽  
Sperm Head ◽  
Swimming Velocity ◽  
Evolutionary Changes ◽  
Muroid Rodents ◽  
Sperm Swimming Speed ◽  
Sperm Size ◽  
Head Area

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.

Variation in Sperm Head Morphology in the Australian Rodent Notomys alexis

1983 ◽  
Vol 31 (3) ◽  
pp. 313 ◽  
Author(s):  
WG Breed ◽  
V Sarafis
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Fluorescence Microscopy ◽  
Functional Significance ◽  
Sperm Head ◽  
Considerable Variability ◽  
Head Morphology ◽  
Scanning Electron

Scanning electron microscopy of the sperm head of the hopping-mouse indicates considerable variability in shape, much of which is probably due to the fragility of the acrosome. However, fluorescence microscopy of the sperm after staining with 4'-6-diamidino-2-phenylindole (DAPI) indicates some nuclear variability as well. Such polymorphism in sperm head morphology is unusual in mammals; its functional significance remains to be determined.

scholarly journals Scanning Electron Microscopy Analysis of the Anterior Capsulotomy Edge: A Comparative Study between Femtosecond Laser-Assisted Capsulotomy and Manual Capsulorhexis

2018 ◽  
Vol 2018 ◽  
pp. 1-6 ◽  
Author(s):  
Daniele Tognetto ◽  
Chiara De Giacinto ◽  
Alberto Armando Perrotta ◽  
Tommaso Candian ◽  
Alessandro Bova ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Femtosecond Laser ◽  
Comparative Study ◽  
Surface Irregularity ◽  
Significant Difference ◽  
Group 2 ◽  
Cut Surface ◽  
Scanning Electron ◽  
Group 1

Purpose. To compare the capsule edges ultrastructure obtained by two femtosecond laser-assisted cataract surgery (FLACS) platforms and manual continuous curvilinear capsulorhexis (CCC) using scanning electron microscopy (SEM). Setting. Eye Clinic, University of Trieste, Italy. Design. Experimental comparative study. Methods. 150 anterior capsules were collected and divided into three groups as follows: Group 1 (50 capsules) obtained with manual CCC, Groups 2 and 3 (each with 50 capsules) obtained with the Catalys Laser and the LenSx Laser, respectively. All samples were imaged by means of SEM and regularity of the cut surface, and thickness of the capsule edge were evaluated and compared. Results. All femtosecond laser (FSL) capsules were perfectly circular, whereas some alteration of the circular shape was observed in the manual ones. Group 1 showed a smooth and regular capsule edge without any surface irregularity, conversely Groups 2 and 3 showed postage-stamp perforations on the capsule edge. The cut surface irregularity value in Group 2 was 1.4 ± 0.63, while it was 0.7 ± 0.49 in Group 3 (p<0.05). Group 1 had a significantly lower thickness of the capsule edge than the FSL groups (p<0.05). No statistically significant difference in the capsule edge thickness between the FSL groups was found (p=0.244). Conclusions. Despite the presence of slight cut surface irregularities, both FSL capsulotomies showed a better geometry and circularity than the manual ones. Capsulotomy specimens obtained using both FSL capsulotomies showed laser-induced alterations of the capsule edge when compared with smooth and regular edges obtained using manual CCC.

scholarly journals Biosynthesis, characterization, and antibacterial activity of ZnO nanoaggregates using aqueous extract from Anacardium occidentale leaf: comparative study of different precursors

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Eric Kwabena Droepenu ◽  
Ebenezer Aquisman Asare ◽  
Boon Siong Wee ◽  
Rafeah Binti Wahi ◽  
Frederick Ayertey ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Antibacterial Activity ◽  
Comparative Study ◽  
Aqueous Extract ◽  
Zinc Chloride ◽  
Zinc Acetate ◽  
Zinc Acetate Dihydrate ◽  
Inhibition Zone ◽  
Anacardium Occidentale ◽  
Acetate Dihydrate

Abstract Background Various parts of Anacardium occidentale plant possess curative qualities like antidiabetic, anti-inflammatory, antibacterial, antifungal, and antioxidant. Aqueous extract of this plant leaf was used in biosynthesizing zinc oxide (ZnO) nanoaggregates using two precursors of zinc salt (zinc acetate dihydrate [Zn(CH3COO)2∙2H2O] and zinc chloride [ZnCl2]). The synthesized ZnO samples were used in a comparative study to investigate the antibacterial activity against selected Gram-positive and Gram-negative microbes [Staphylococcus aureus, Exiguobacterium aquaticum (Gram +ve) and Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumannii (Gram −ve)]. The synthesized ZnO nanoaggregates from the two precursors were characterized using Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive x-ray spectroscopy (EDX) techniques. Results Micrographs of SEM and TEM confirmed nanoparticles agglomerated into aggregates. While spherical nanoaggregates were identified in samples prepared from Zn(CH3COO)2∙2H2O, flake-like structures were identified in samples synthesized from ZnCl2. Particle size determined by TEM was 107.03 ± 1.54 nm and 206.58 ± 1.86 nm for zinc acetate dihydrate and zinc chloride precursors respectively. ZnO nanoaggregate synthesized using zinc acetate as precursor gave higher antibacterial activity than its counterpart, zinc chloride with K. pneumonia recording the highest inhibition zone of 2.08 ± 0.03 mm (67.53%) whereas S. aureus recorded the least inhibition zone of 1.06 ± 0.14 mm (34.75%) for ZnO nanoaggregate from zinc chloride precursor. Also, antibacterial activity increases with increasing concentration of the extract in general. However, A. baumannii, E. aquaticum, and K. pneumoniae did not follow the continuity trend with regards to the 250 ppm and 500 ppm concentrations. Conclusion Biosynthesis of ZnO nanoaggregates using aqueous extract of A. occidentale leaf from zinc acetate dihydrate and zinc chloride as precursors was successful with the formation of nanospheres and nanoflakes. The study suggested that A. occidentale sp. could be an alternative source for the production of ZnO nanoparticles and are efficient antibacterial compounds against both Gram +ve and Gram −ve microbes with its promising effect against infectious bacteria.

A Comparative Study of Trichomes in Angophora Cav. And Eucalyptus L'hérit. - A Question of Homology

1984 ◽  
Vol 32 (5) ◽  
pp. 561 ◽  
Author(s):  
PY Ladiges
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Comparative Study ◽  
Light Microscopy ◽  
Evolutionary Trends ◽  
Oil Glands ◽  
Ancestral Condition ◽  
Scanning Electron

The trichomes of Angophora and Eucalyptus are illustrated from scanning electron microscopy and light microscopy, and evolutionary trends are discussed. Bristle glands of Angophora and Eucalyptus subgen. Blakella and Corymbia are emergent oil glands of varying lengths. Emergent oil glands occur in all other Eucalyptus subgenera but they are most conspicuous in Blakella, Corymbia and Angophora, in which they are characterized by four cap cells each ornamented with micropapillae. Hairs in Angophora are unique, being multicellular; they are also uniseriate and scattered on the epidermis. In contrast, hairs in Eucalyptus are simple extensions, short or long, of the cells on the sides of or the cap cells of the emergent oil glands, and they are not homologous with those of Angophora. Eucalyptus setosa (subgen. Blakella) and E. brockwayi (subgen. Symphyomyrtus) are two exceptions, having unicellular hairs on the epidermis, not associated with oil glands. It is suggested that this is an ancestral condition (or secondary reversal to it).

Comparative Study of Field Emission-Scanning Electron Microscopy and Atomic Force Microscopy to Assess Self-assembled Monolayer Coverage on Any Type of Substrate

1999 ◽  
Vol 5 (6) ◽  
pp. 413-419 ◽  
Author(s):  
Bernardo R.A. Neves ◽  
Michael E. Salmon ◽  
Phillip E. Russell ◽  
E. Barry Troughton
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Atomic Force Microscopy ◽  
Comparative Study ◽  
Field Emission ◽  
Self Assembled Monolayer ◽  
Force Microscopy ◽  
Atomic Force ◽  
Self Assembled ◽  
Scanning Electron

Abstract: In this work, we show how field emission–scanning electron microscopy (FE-SEM) can be a useful tool for the study of self-assembled monolayer systems. We have carried out a comparative study using FE-SEM and atomic force microscopy (AFM) to assess the morphology and coverage of self-assembled monolayers (SAM) on different substrates. The results show that FE-SEM images present the same qualitative information obtained by AFM images when the SAM is deposited on a smooth substrate (e.g., mica). Further experiments with rough substrates (e.g., Al grains on glass) show that FE-SEM is capable of unambiguously identifying SAMs on any type of substrate, whereas AFM has significant difficulties in identifying SAMs on rough surfaces.

A comparative study between electron microscopy and immunofluorescence mapping in the diagnosis of epidermolysis bullosa

2006 ◽  
Vol 47 (4) ◽  
pp. A59-A59 ◽  
Author(s):  
Eleni Yiasemides ◽  
Judie Walton ◽  
Penelope Marr ◽  
Elmer V. Villanueva ◽  
Dédée F. Murrell
Keyword(s):  
Electron Microscopy ◽  
Comparative Study ◽  
Epidermolysis Bullosa
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