Megasporogenesis in normal and a synaptic-mutant (sy-2) of Solanum commersonii Dun.

Genome ◽  
1988 ◽  
Vol 30 (4) ◽  
pp. 536-539 ◽  
Author(s):  
W. A. Parrott ◽  
R. E. Hanneman Jr.
Keyword(s):  
Meiotic Division ◽  
Daughter Cell ◽  
Intermediate Stage ◽  
Differential Interference Contrast Microscopy ◽  
Solanum Commersonii ◽  
Linear Tetrad ◽  
Polygonum Type ◽  
Nomarski Differential Interference Contrast ◽  
Contrast Microscopy ◽  
Interference Contrast Microscopy

Nomarski differential interference contrast microscopy was used to study megasporogenesis in intact ovules of Solanum commersonii Dun., following staining with Mayer's hemalum and clearing with methyl salicylate or cedarwood oil. Previous studies in Solanum have observed the Polygonum type of megasporogenesis, in which a linear tetrad of megaspores is formed. The three micropylar megaspores then degenerate, leaving the chalazal megaspore to divide mitotically to form the egg sac. Contrary to expectation, only 30% of the observed sporads within the same ovary were tetrads. Triads, including some with one deteriorating cell at the micropylar end, were the predominant form. Many dyads, which are an intermediate stage in megasporogenesis, were found with one cell prematurely deteriorating. These observations can be explained if the micropylar daughter cell of the dyad stage, which formed after telophase I, began deteriorating before the second meiotic division, such that it never underwent the second division. The chalazal daughter cell would still undergo the second meiotic division, followed by death of the new micropylar megaspore.Key words: Solanum, potato, megasporogenesis, S. commersonii, ovule, clearing.

Teleost epiboly: a reassessment of deep cell movement in the germ ring

Development ◽  
1988 ◽  
Vol 102 (3) ◽  
pp. 575-585 ◽  
Author(s):  
A. Wood ◽  
L.P.M. Timmermans
Keyword(s):  
Direct Evidence ◽  
Cell Layer ◽  
Cell Movement ◽  
Current View ◽  
Differential Interference Contrast Microscopy ◽  
Nomarski Differential Interference Contrast ◽  
Contrast Microscopy ◽  
Interference Contrast Microscopy ◽  
Intrinsic Marker

Using the prominent cell nucleus as an intrinsic marker, individual deep cell blastomeres have been monitored in vivo using Nomarski differential interference contrast microscopy during spreading of the teleost blastoderm. Involution of these cells has been recorded during early to mid stages of epiboly about an apparent point of shear located centrally within the germ ring. This involuting movement involves superficial deep cells, adjacent to the enveloping layer, as well as those located more centrally within the germ ring and is associated with a continuous vegetal displacement of the outer strata of deep cell blastomeres towards the edge of the blastodisc. During the early stages of epiboly this process is qualitatively similar at any location around the entire circumferential margin of the blastodisc. Postinvoluting deep cells are found close to the yolk syncytial layer, are surrounded by considerable intercellular space and illustrate less directional displacement. In contrast to the deep cell layer, the enveloping layer was never observed to invaginate. These results contradict the current view that no involution or global rearrangement of deep cells occurs during teleost gastrulation and present the first direct evidence of involution within the deep cell population during early epiboly.

scholarly journals Significance of Enhanced Morphological Detection of Cryptosporidium sp. Oocysts in Water Concentrates Determined by Using 4′,6′-Diamidino-2-Phenylindole and Immunofluorescence Microscopy

2002 ◽  
Vol 68 (10) ◽  
pp. 5198-5201 ◽  
Author(s):  
H.V. Smith ◽  
B. M. Campbell ◽  
C. A. Paton ◽  
R. A. B. Nichols
Keyword(s):  
Fluorescein Isothiocyanate ◽  
Alternative Methods ◽  
Water Type ◽  
Raw Water ◽  
Differential Interference Contrast Microscopy ◽  
Oocyst Wall ◽  
Nomarski Differential Interference Contrast ◽  
Contrast Microscopy ◽  
Interference Contrast Microscopy

ABSTRACT Of 2,361 water concentrates analyzed for the presence of Cryptosporidium spp. oocysts between January 1992 and May 1998, 269 (11.4%) were positive, of which 235 (87.4%) were raw and 34 were final water concentrates. Of 740 oocysts enumerated in positive samples, 656 oocysts (88.7%) were detected in raw and 84 oocysts (11.3%) were detected in final water concentrates by using a commercially available fluorescein isothiocyanate-labeled anti-Cryptosporidium sp. monoclonal antibody and the nuclear fluorogen 4′,6′-diamidino-2-phenylindole (DAPI). Of raw water positive samples, 66.8% had oocysts that contained nuclei, while 58.8% of final water samples had oocysts that contained nuclei. The most frequently identified oocysts had either no DAPI-positive nuclei and no internal morphology according to Nomarski differential interference-contrast microscopy (DIC) or four DAPI-positive nuclei together with internal contents according to DIC (39.5 and 32.8% of raw and 42.9 and 30.9% of final water positives, respectively). By use of the presence of DAPI-stained nuclei to support oocyst identification based upon oocyst wall fluorescence, 56.5% of oocysts were identified when at least one nucleus was present, while increasing the number of nuclei necessary for identification to four reduced the percentage identifiable to 32.8% in raw water concentrates. In final water concentrates, 51% of oocysts were identified using oocyst wall fluorescence and the presence of at least one nucleus, while increasing the number of nuclei necessary for identification to four reduced the percentage identifiable to 30.9%. By consolidating our identification criteria from the presence of at least one nucleus to the presence of four nuclei, we excluded approximately 20% of oocysts in either water type. Approximately 40% of oocysts detected in these United Kingdom samples were empty and could not be detected by alternative methods, including the PCR and fluorescence in situ hybridization.

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