290 3-DIMENSIONAL VISUALIZATION OF BOVINE OOCYTE FERTILIZATION BY CONFOCAL LASER SCANNING MICROSCOPY

2015 ◽  
Vol 27 (1) ◽  
pp. 234
Author(s):  
E. De Monte ◽  
M. Reichenbach ◽  
H. Reichenbach ◽  
E. Wolf ◽  
F. Habermann

Cattle can serve as a model organism to resolve central questions in mammalian reproduction that cannot be clarified in the mouse model due to notable species-specific peculiarities of early mouse embryogenesis. As part of a project on structural, molecular, and functional deficiencies of bovine oocytes, we started to systematically investigate fertilization and the onset of embryo development in vitro by 3-dimensional multicolor fluorescence microscopy. We are using 3D visualisation as key approach to clarify the multiple parallel and sequential processes and events of fertilization as well as to identify and classify errors and failures. Moreover, we aim to gain insights into the mechanisms of aberrations by linking processes at the cellular and the molecular level. We studied class I and II oocytes collected from slaughterhouse ovaries and matured for 23 h in vitro. Oocytes were fixed at different times from 4 to 12 h postinsemination with formaldehyde in a microtubule-stabilising buffer containing taxol in such a way that the 3-dimensional cell architecture was maintained, and were stained for DNA, microtubules, and f-actin microfilaments. In addition, serine 10-phosphorylated histone H3 was used as a marker for chromosome condensation and the spindle midbody. For 3-dimensional imaging of the oocytes in toto, confocal serial sections were captured at 1-µm intervals using a 40× objective (NA = 1.3). For imaging details, we used a high spatial sampling density (pixel size: 50 × 50 nm, z-step size: 200 nm) close to the Nyquist criterion and image restoration by maximum likelihood estimation (MLE) deconvolution. A series of more than 500 three-dimensional snapshots of fertilized oocytes at different points in time gives a first detailed view on the spatial and temporal course of the sperm entry, the formation of the paternal pronucleus and the sperm aster, completion of oocyte meiosis and the formation of the maternal pronucleus, as well as dynamic changes of the cytoskeleton. Moreover, we can document a spectrum of abnormalities including spontaneous parthenogenetic oocyte activation, polyspermy, and aberrations of meiosis I and II. The latter include irregular spindle formation and chromosome segregation, the occurrence of chromatin bridges and abnormal spindle positioning and rotation (e.g. leading to nonextrusion of a first or a second polar body or the extrusion of two second polar bodies). Our microscopic investigation in the bovine system contributes to unraveling the origins of irregular cleavage, aneuploidy, and mosaicism in mammals. Three-dimensional high-speed microscopy of oocytes and zygotes in affordable timeframes could be of great value in improving the differential diagnosis of oocyte and sperm dysfunction, as well as in identifying and dissecting problems, limitations, and potential risks of reproductive technologies (ART).This work is supported by the Deutsche Forschungsgemeinschaft (DFG FOR 1041).

Reproduction ◽  
2006 ◽  
Vol 132 (6) ◽  
pp. 859-867 ◽  
Author(s):  
Xiao-Qian Meng ◽  
Ke-Gang Zheng ◽  
Yong Yang ◽  
Man-Xi Jiang ◽  
Yan-Ling Zhang ◽  
...  

Microfilaments (actin filaments) regulate various dynamic events during meiotic maturation. Relatively, little is known about the regulation of microfilament organization in mammalian oocytes. Proline-rich tyrosine kinase2 (Pyk2), a protein tyrosine kinase related to focal adhesion kinase (FAK) is essential in actin filaments organization. The present study was to examine the expression and localization of Pyk2, and in particular, its function during rat oocyte maturation. For the first time, by using Western blot and confocal laser scanning microscopy, we detected the expression of Pyk2 in rat oocytes and found that Pyk2 and Try402 phospho-Pyk2 were localized uniformly at the cell cortex and surrounded the germinal vesicle (GV) or the condensed chromosomes at the GV stage or after GV breakdown. At the metaphase and the beginning of anaphase, Pyk2 distributed asymmetrically both in the ooplasm and the cortex with a marked staining associated with the chromosomes and the region overlying the meiotic spindle. At telophase, Pyk2 was observed in the cleavage furrows in addition to its cortex and cytoplasm localization. The dynamics of Pyk2 were similar to that of F-actin, and this kinase was found to co-localize with microfilaments in several developmental stages during rat oocyte maturation. Microinjection of Pyk2 antibody demolished the microfilaments assembly and also inhibited the first polar body (PB1) emission. These findings suggest an important role of Pyk2 for rat oocyte maturation by regulating the organization of actin filaments.


2020 ◽  
Vol 119 (12) ◽  
pp. 4159-4168
Author(s):  
Runhui Zhang ◽  
Wanpeng Zheng ◽  
Arwid Daugschies ◽  
Berit Bangoura

AbstractMixed infections of Toxoplasma gondii and Eimeria tenella are likely to occur frequently due to the high prevalence of both pathogens in free-ranging chickens. In this study, we investigated the co-occurrence of the two parasites in the same immune-competent host cell towards altered patterns of parasite-host interactions. Chicken blood monocyte–derived macrophages were co-infected with T. gondii RH tachyzoites and E. tenella Houghton sporozoites in vitro for 24 h. Through monitoring the uptake of pH-sensitive pHrodo™ Zymosan BioParticles (“Zymosan”) by macrophages, we created a three-dimensional model and to analyze quantitatively phagocytosis using confocal laser scanning microscopy. Assessments of parasite populations were performed by qPCR at 2, 6, 12, and 24 h post-infection (hpi). At 6 hpi, phagocytosis was inhibited in the E. tenella–infected cultures while no inhibition of phagocytosis was observed due to T. gondii. Phagocytosis activity revealed more complex interactions during co-infection. At 12 and 24 hpi, phagocytosis response to “Zymosan” was distinctly weaker in co-infected cells than in all other groups except for cells mono-infected with high doses of E. tenella at 24 hpi. By qPCR, significantly reduced numbers of both intracellular parasites were recorded (10-fold) in all infected groups at 2 hpi. At 12 hpi, the T. gondii population reached lowest values but dramatically increased by 24 hpi. Our data confirm that macrophage phagocytosis is involved in the control of invasion by apicomplexan parasites in chicken which particularly applies to E. tenella infection and it was able to be altered by the co-existing parasites.


2006 ◽  
Vol 72 (4) ◽  
pp. 2864-2875 ◽  
Author(s):  
Cordula Lembke ◽  
Andreas Podbielski ◽  
Carlos Hidalgo-Grass ◽  
Ludwig Jonas ◽  
Emanuel Hanski ◽  
...  

ABSTRACT Streptococcus pyogenes (group A streptococcus [GAS]) is a frequent cause of purulent infections in humans. As potentially important aspects of its pathogenicity, GAS was recently shown to aggregate, form intratissue microcolonies, and potentially participate in multispecies biofilms. In this study, we show that GAS in fact forms monospecies biofilms in vitro, and we analyze the basic parameters of S. pyogenes in vitro biofilm formation, using Streptococcus epidermidis as a biofilm-positive control. Of nine clinically important serotype strains, M2, M6, M14, and M18 were found to significantly adhere to coated and uncoated polystyrene surfaces. Fibronectin and collagen types I and IV best supported primary adherence of serotype M2 and M18 strains, respectively, whereas serotype M6 and M14 strains strongly bound to uncoated polystyrene surfaces. Absorption measurements of safranin staining, as well as electron scanning and confocal laser scanning microscopy, documented that primary adherence led to subsequent formation of three-dimensional biofilm structures consisting of up to 46 bacterial layers. Of note, GAS isolates belonging to the same serotype were found to be very heterogeneous in their biofilm-forming behavior. Biofilm formation was equally efficient under static and continuous flow conditions and consisted of the classical three steps, including partial disintegration after long-term incubation. Activity of the SilC signaling peptide as a component of a putative quorum-sensing system was found to influence the biofilm structure and density of serotype M14 and M18 strains. Based on the presented methods and results, standardized analyses of GAS biofilms and their impact on GAS pathogenicity are now feasible.


2016 ◽  
Vol 82 (22) ◽  
pp. 6799-6807 ◽  
Author(s):  
Adam C. Mumford ◽  
Irini J. Adaktylou ◽  
David Emerson

ABSTRACTMicrobially influenced corrosion (MIC) is a major cause of damage to steel infrastructure in the marine environment. Despite their ability to grow directly on Fe(II) released from steel, comparatively little is known about the role played by neutrophilic iron-oxidizing bacteria (FeOB). Recent work has shown that FeOB grow readily on mild steel (1018 MS) incubatedin situor as a substrate for pure culturesin vitro; however, details of how they colonize steel surfaces are unknown yet are important for understanding their effects. In this study, we combine a novel continuously upwelling microcosm with confocal laser scanning microscopy (CLSM) to determine the degree of colonization of 1018 MS by the marine FeOB strain DIS-1. 1018 MS coupons were incubated with sterile seawater (pH 8) inoculated with strain DIS-1. Incubations were performed both under oxic conditions and in an anoxic-to-oxic gradient. Following incubations of 1 to 10 days, the slides were removed from the microcosms and stained to visualize both cells and stalk structures. Stained coupons were visualized by CLSM after being mounted in a custom frame to preserve the three-dimensional structure of the biofilm. The incubation of 1018 MS coupons with strain DIS-1 under oxic conditions resulted in initial attachment of cells within 2 days and nearly total coverage of the coupon with an ochre film within 5 days. CLSM imaging revealed a nonadherent biofilm composed primarily of the Fe-oxide stalks characteristic of strain DIS-1. When incubated with elevated concentrations of Fe(II), DIS-1 colonization of 1018 MS was inhibited.IMPORTANCEThese experiments describe the growth of a marine FeOB in a continuous culture system and represent direct visualizations of steel colonization by FeOB. We anticipate that these experiments will lay the groundwork for studying the mechanisms by which FeOB colonize steel and help to elucidate the role played by marine FeOB in MIC. These observations of the interaction between an FeOB, strain DIS-1, and steel suggest that this experimental system will provide a useful model for studying the interactions between microbes and solid substrates.


2018 ◽  
Vol 14 (4) ◽  
pp. 512-514
Author(s):  
Nor Shahida Abdul Rahman ◽  
Mimi Sophia Sarbandi ◽  
Wan Hafizah Wan Jusof ◽  
Zolkapli Eshak ◽  
Salina Othman ◽  
...  

The timing of the first zygotic cleavage is an accurate predictor of embryo quality. Embryos that cleaved early have higher developmental viability compared to their late counterparts. During embryonic development, cleavage is affected by cellular metabolic processes performed by mitochondria and its synergistic interaction with endoplasmic reticulum (ER). However, in depth study on differences of mitochondria and ER ultrastructures in early- cleaving (EC) versus late- cleaving (LC) embryos is limited. This study compares mitochondria and ER ultrastructures of EC versus LC embryos using Confocal Laser Scanning Microscopy (CLSM) and Transmission Electron Microscopy (TEM). Embryos were obtained from female ICR superovulated mice, 28-30 hours post hCG. Two-cell embryos were categorized as early-cleaving (EC), while zygotes with the second polar body and two pronuclei present were categorized as late-cleaving (LC). The LC embryos were cultured in vitro until the 2- cell stage. In EC embryos, mitochondria were mostly found at the perinuclear region and closely associated with dense ER. Meanwhile, mitochondria of LC embryos were distributed uniformly within the cytoplasm. Mitochondrial fluorescence intensity was significantly higher in EC versus LC [(18.7 ± 0.4) versus (14.6 ± 0.4)] x 105 pixel, (p<0.01). Development to the blastocyst stage was also significantly higher in EC compared to LC embryos (96.7% versus 60.9%) (p<0.01). Higher viability of EC embryos is attributed to the close association of their mitochondria to ER. This contributed to better mitochondrial fission, resulting in enhanced energy generating processes and preimplantation development. 


2015 ◽  
Vol 65 (3) ◽  
pp. 371-389 ◽  
Author(s):  
Čabarkapa Ivana ◽  
Škrinjar Marija ◽  
Lević Jovanka ◽  
Kokić Bojana ◽  
Blagojev Nevena ◽  
...  

AbstractSalmonella entericaserotype Enteritidis is an important alimentary pathogen that recently gained special attention due to the ability of a large number of strains to form biofilms. Qualitative testing of biofilm forming ability was performed by observing the morphotype of the colonies on Congo Red agar and by conducting the pellicle test, while quantitative testing was carried out by Cristal violet assay on microtiter plates. A total of 14 isolates of S. Enteritidis were tested for biofilm forming ability, while Salmonella Enteritidis ATTC 13076 was used as the reference strain. Based on the morphotype of colonies cultivated on Congo Red agar at 25°C incubation temperature, among tested isolates three morphotypes were detected – red, dry and rough (rdar), brown, dry and rough (bdar) and smooth and white (saw). Half of the tested isolates demonstrated rdar morphotype. All isolates that showed a specific morphotype at this incubation temperature also formed the corresponding type of pellicle at the air-liquid interface. Additionally, comparing OD (optical density) values obtained by crystal violet test between groups of isolates that represent one of the three detected morphotypes (rdar, bdar and saw), statistically significant differences were detected. Based on OD values obtained by crystal violet test at both applied incubation temperatures, isolates were classified into three categories, regarding their ability to form biofilms: strong, moderate and weak biofilm producers. By comparing the amounts of the biofilms formed after 48h at 25°C and 37°C, statistically significant differences were noted (P<0.05). In this research we presented micrographs and a reconstruction of three-dimensional projections of biofilm developing phases of rdar morphotype isolates, which were obtained using confocal laser scanning microscopy.


2004 ◽  
Vol 16 (2) ◽  
pp. 263
Author(s):  
J.L. Tremoleda ◽  
T.A.E. Stout ◽  
B.M. Gadella ◽  
B. Colenbrander

In vitro fertilization (IVF) has proven to be a surprisingly unsuccessful way of producing horse embryos. The aim of this study was to investigate the interaction between sperm and the cumulus oocyte complex (COC) during IVF. In experiment 1, three IVF conditions were tested: (A) COCs recovered from slaughtered mares were categorized with respect to cumulus morphology (C: compact, n=86, or E: expanded, n=55) and matured in TCM199 containing 0.01IU/mL porcine FSH and equine LH (IVM); after IVM, the oocytes were denuded and those with a visible polar body were incubated with sperm (IVF) in the presence or absence of 150ng/mL progesterone (P4) to induce the acrosome reaction (AR); (B) IVM oocytes from C-COCS were denuded (n=52) or not (n=67) before IVF in the presence of P4;; (C) in vivo-matured oocytes (n=15) recovered by transvaginal ultrasound-guided aspiration from preovulatory follicles 32h after the donor mare was treated with hCG, were fertilized in vitro in the presence of P4. In all cases, IVF was performed with frozen-thawed, Percoll-selected sperm from a single stallion, at a final concentration of 1×106spermatozoa/ml in fertil-TALP for 20h (Parrish et al., 1988 Biol. Reprod. 38, 1171–1180). In experiment 2, the possibility that semen cryopreservation or stallion critically influenced IVF was examined by incubating denuded IVM oocytes with fresh or frozen/thawed sperm from the same (fresh;; n=17 for both C- and E-COCs and frozen-thawed; n=12 and 21 for C and E-COCs, respectively) or one other stallion (Fresh;; n=12 and 19 and frozen-thawed; n=12 and 19 for C and E-COCs, respectively), in the presence of P4 for 20h. In both experiments, the resulting sperm-oocyte complexes were fixed, permeabilized and labelled with fluorescein-conjugated peanut agglutinin (EY Laboratores, San Mateo, CA, USA) and ethidium homodimer (Molecular Probes, Eugene, OR, USA) to stain the acrosomal membrane and DNA, respectively, so that membrane status and position of the sperm within the oocyte investments could be detected by confocal laser scanning microscopy. The total number of sperm bound per oocyte was compared between treatments using one-way ANOVA with pair-wise multiple comparison (Bonferroni t-test). Despite binding to the zona pellucida (ZP), neither fresh nor frozen/thawed sperm from either stallion acrosome-reacted or penetrated any oocytes, irrespective of cumulus morphology at the onset of IVM, denudation prior to IVF or the presence of P4. However, more sperm bound to the ZP of cumulus-denuded IVM oocytes (65±32 and 62±28 [mean±sd] for C and E-COCs, respectively), than cumulus-intact IVM (5±4) or in vivo-matured oocytes (23±17: P&lt;0.001). None of the other factors investigated affected bound sperm numbers. In all cases, ZP-bound sperm failed to AR in the classical fashion, and all oocytes remained arrested at the MII stage. In summary, fertilization failed because sperm did not acrosome-react after binding to the ZP. It is concluded that failure to adequately activate stallion sperm is an important obstacle to successful IVF in horses.


2013 ◽  
Vol 25 (1) ◽  
pp. 199
Author(s):  
A. A. Gratao ◽  
A. Beck ◽  
M. Reichenbach ◽  
H. D. Reichenbach ◽  
E. Wolf ◽  
...  

A high proportion of bovine oocytes fertilized in vitro fail to develop beyond the first 4 cleavage cycles. The first mitotic division of the zygote and proper segregation of chromosomes and cytoplasmic components seems to be a particularly delicate task. Notably, zygotes cleaving with a delay of only a few hours seem to have a very low chance of developing to the blastocyst stage. But what exactly goes wrong, how often, and why? To answer such questions we have to visualize in greater detail basic structures and processes such as the sperm aster, DNA replication, migration and apposition of the 2 pronuclei, synchronous chromosome condensation and breakdown of the nuclear envelopes, assembly of the first mitotic spindle and chromosome congression, anaphase, and cytokinesis. Oocytes fertilized in vitro were fixed at different time points around the first cleavage and stained for DNA, Ser10-phosphorylated histone H3, microtubules, and microfilaments. Zygotes were imaged in toto by recording confocal serial sections at 1-µm intervals using a 40× objective (NA = 1.3). Details were recorded with high spatial sampling densities (pixel size 50 × 50 nm, z-step size of 200 nm) close to the Nyquist criterion and restored by maximum likelihood estimation deconvolution using the real point spread function. We present a series of 3-D confocal images captured at different stages of the first cleavage. The images reveal new insights into the formation, structure, and function of the first mitotic spindle and the occurrence of spindle aberrations, irregular chromosome segregation, and abnormal cytokinesis. The microscopic findings guide us to candidate proteins for localization analyses and functional studies based on 3-D fluorescence live-cell imaging of zygotes and early embryos. This work is supported by the Deutsche Forschungsgemeinschaft (DFG FOR 1041).


Author(s):  
M. H. Chestnut ◽  
C. E. Catrenich

Helicobacter pylori is a non-invasive, Gram-negative spiral bacterium first identified in 1983, and subsequently implicated in the pathogenesis of gastroduodenal disease including gastritis and peptic ulcer disease. Cytotoxic activity, manifested by intracytoplasmic vacuolation of mammalian cells in vitro, was identified in 55% of H. pylori strains examined. The vacuoles increase in number and size during extended incubation, resulting in vacuolar and cellular degeneration after 24 h to 48 h. Vacuolation of gastric epithelial cells is also observed in vivo during infection by H. pylori. A high molecular weight, heat labile protein is believed to be responsible for vacuolation and to significantly contribute to the development of gastroduodenal disease in humans. The mechanism by which the cytotoxin exerts its effect is unknown, as is the intracellular origin of the vacuolar membrane and contents. Acridine orange is a membrane-permeant weak base that initially accumulates in low-pH compartments. We have used acridine orange accumulation in conjunction with confocal laser scanning microscopy of toxin-treated cells to begin probing the nature and origin of these vacuoles.


2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Jiang Lan Fan ◽  
Jose A. Rivera ◽  
Wei Sun ◽  
John Peterson ◽  
Henry Haeberle ◽  
...  

AbstractUnderstanding the structure and function of vasculature in the brain requires us to monitor distributed hemodynamics at high spatial and temporal resolution in three-dimensional (3D) volumes in vivo. Currently, a volumetric vasculature imaging method with sub-capillary spatial resolution and blood flow-resolving speed is lacking. Here, using two-photon laser scanning microscopy (TPLSM) with an axially extended Bessel focus, we capture volumetric hemodynamics in the awake mouse brain at a spatiotemporal resolution sufficient for measuring capillary size and blood flow. With Bessel TPLSM, the fluorescence signal of a vessel becomes proportional to its size, which enables convenient intensity-based analysis of vessel dilation and constriction dynamics in large volumes. We observe entrainment of vasodilation and vasoconstriction with pupil diameter and measure 3D blood flow at 99 volumes/second. Demonstrating high-throughput monitoring of hemodynamics in the awake brain, we expect Bessel TPLSM to make broad impacts on neurovasculature research.


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