Prefertilization ovule development in Capsella: the dyad, tetrad, developing megaspore, and two-nucleate gametophyte

1986 ◽  
Vol 64 (4) ◽  
pp. 875-884 ◽  
Author(s):  
Patricia Schulz ◽  
William A. Jensen

Ovules of Capsella bursa-pastoris at the dyad and tetrad stages of meiosis and at the megaspore and two-nucleate stages of the gametophyte were studied with the electron microscope. The cells of the dyad and tetrad are separated by aniline blue fluorescent cross walls and receive all types of organelles and autophagic vacuoles that were present in the meiocyte. Autophagic vacuoles enclose ribosomes and organelles and show reaction product for acid phosphatase. Autophagic vacuoles and some plastids are absorbed into the enlarging vacuoles of the growing megaspore. Other plastids appear to survive meiosis and there is no evidence for their de novo origin. Some mitochondria appear to degenerate in the enlarging megaspore but others look healthy and there is no evidence for the de novo origin of mitochondria. The nucleolus of the developing megaspore becomes very large and the cytoplasm is extremely dense with ribosomes. The cell wall is thickened by an electron-translucent, periodic acid – Schiff negative, aniline blue fluorescent material and contains plasmodesmata that link the megaspore with the nucellus. The plasmalemma of the growing megaspore produces microvilluslike extensions into this wall that disappear with the formation of the two-nucleate gametophyte. Plasmodesmata disappear from the cell wall at the four-nucleate stage.


1990 ◽  
Vol 36 (5) ◽  
pp. 327-335 ◽  
Author(s):  
Stephen H. Smith ◽  
Robert G. E. Murray

Aquaspirillum sinuosum cell walls bear two paracrystalline, proteinaceous surface layers (S layers). Each shows a different symmetry: the inner layer is closely apposed to the outer membrane and is a tetragonal array (90° axes; 5-nm units; repeat frequency 8 nm); the outer layer is a hexagonal array on the external surface (14-nm units; repeat frequency 18 nm) and, although the units have a six-pointed stellate form, the linkage between units is not resolved. The outer layer consists of a major 130-kDa protein and a 180-kDa minor component; these co-extract, co-assemble, and are inseparable by hydroxylapatite chromatography or by recrystallization. The solubilizing effects of reagents suggest stabilization by hydrogen bonding and Ca2+. The two outer layer proteins are serologically related and show partial identity by peptide mapping. Periodic acid – Schiff staining of the 180-kDa band suggests that this may be a glycosylated form of the 130-kDa component. The inner layer components form a doublet of 75- and 80-kDa polypeptides with extreme resistance to extraction. Close apposition to the outer membrane, resistance to chaotropes, aqueous insolubility, and behaviour in charge-shift electrophoresis suggest hydrophobic interaction between subunits and an integral association with the outer membrane. Key words: bacterial surface, cell wall, surface layers, cell-wall proteins, cell-wall assembly.



1987 ◽  
Vol 65 (6) ◽  
pp. 1445-1453 ◽  
Author(s):  
M. Samuel Cannon ◽  
H. W. Sampson ◽  
E. D. Kapes

Blood leukocytes of Bufo marinus were studied by light and phase-contrast microscopy and histochemical techniques for the localization of glycogen, lipids, several basic proteins, and a number of hydrolytic and oxidative enzymes. The hydrolytic enzymes occurred in varying amounts in neutrophils, eosinophils, lymphocytes, and monocytes; neutrophils were the only leukocytes to demonstrate alkaline phosphatase activity, while β-glucuronidase was only seen in lymphocytes, and aryl-sulfatase was not observed in any leukocytes. Periodic acid – Schiff (PAS) positive granules also occurred in varying amounts in leukocytes. Slight lipid activity was only seen in neutrophils, while arginine, and (or) lysine, and tyrosine reactivity was only observed in eosinophils. The appearance and histochemical reactivity of acid phosphatase granules in neutrophils corresponded closely with the appearance and number of specific neutrophilic granules seen in Wright–Giemsa preparations and with the PAS-positive granules. Small lymphocytes were myeloperoxidase (peroxidase) negative; β-glucuronidase, acid phosphatase, and PAS-positive granules corresponded to neutral red granules seen in supravital films. The oxidative enzymes also occurred in differing amounts in leukocytes, but strongly suggested that the leukocytes of Bufo marinus are capable of some degree of aerobic and anaerobic metabolism.



1984 ◽  
Vol 30 (3) ◽  
pp. 290-298 ◽  
Author(s):  
M. S. Manocha

Cell surface characteristics of three Mortierella species differing in their response to a mycoparasite, Piptocephalis virginiana, were examined. Their cell wall composition was typical of mucoraceous fungi with chitin and chitosan as major polysaccharides. Electron microscopy revealed that the mycoparasite penetrated and formed haustoria in the hyphae of susceptible hosts, M. pusilla and M. isabellina. The failure of the parasite to establish contact and penetrate a hypha of the nonhost, M. candelabrum, was not due to cell wall thickness, rigidity, or chitin contents. Markedly different protein patterns obtained from crude alkali extracts of host and nonhost cell walls by sodium dodecyl sulfate – polyacrylamide gel electrophoresis might explain the difference in host and nonhost response to the mycoparasite. Whereas most of the bands differed only in intensity after staining with either Coomassie blue or periodic acid – Schiff reagent, there were two distinct bands of glycoproteins (76 000 and 74 000) observed in the host species which were absent in the nonhost species.



1981 ◽  
Vol 59 (1) ◽  
pp. 61-69 ◽  
Author(s):  
B. J. Crawford ◽  
Alex Yan ◽  
M. MacDonald

The changes in surface morphology during the reexpression of differentiation of chick retinal pigmented epithelial cells (RPE) in clonal culture have been studied using the scanning electron microscope (SEM) and transmission electron microscope (TEM) and compared with those described in vivo. Three-week-old colonies demonstrated a gradual change in apical surface morphology along any colony radius. At the outer edge, the cell surfaces were either smooth with a few small filamentous protrusions or showed a varying number of large blebs. Toward the centre of the colony the surfaces demonstrated a gradual increase in filamentous protrusions. The apical surfaces of the most densely pigmented cells at the centre of the colony consisted mainly of small rounded protrusions. The changes in surface morphology of cells in the centre of younger colonies during redifferentiation were similar to those found along the radius of a 3-week-old colony. The results show that older colonies have all of the morphological stages of the redifferentiation process (and possibly the biochemical ones as well) arranged along any radius.The basal surfaces of all the colonies were covered by a thin acellular membrane that stained positively with periodic acid–Schiff (PAS) and which may contain fibronectins and appears to be involved in cellular attachment.



1981 ◽  
Vol 51 (1) ◽  
pp. 15-23
Author(s):  
R.E. Schmitter ◽  
A.J. Jurkiewicz

Periodic acid-Schiff staining, acid phosphatase localization, and yellow autofluorescence have been correlated with the PAS-body of Gonyaulax polyedra for the first time. PAS- staining and acid phosphatase activity are both correlated with the PAS-body of Gonyaulax tamarensis. These results that the PAS-body of these marine dinoflagellate algae functions in subcellular digestion.



1984 ◽  
Vol 69 (1) ◽  
pp. 127-135
Author(s):  
E.G. Williams ◽  
R.B. Knox ◽  
V. Kaul ◽  
J.L. Rouse

In Rhododendron spp. and Ledum groenlandicum a callose wall is laid down around the zygote in the first 2 days after fertilization. The periodic acid/Schiff-positive, aniline blue-fluorescence-positive callosic wall is initiated adjacent to the degenerating synergid, extends to cover the entire zygote surface, and remains visible during the initiation of embryogeny as the zygote elongates before the first proembryonal division. Unfertilized ovules show eventual callose deposition in the ovule wall cells during senescence in undeveloped abscising pistils, but show no development of callose within the embryo sac. Possible roles of a zygote special callose wall are discussed.



1980 ◽  
Vol 28 (2) ◽  
pp. 101-114 ◽  
Author(s):  
C Tougard ◽  
R Picart ◽  
A Tixier-Vidal

The binding sites of antisera (anti) to the beta (beta) subunits of rat follicle-stimulating hormone (rFSH), rat luteinizing hormone (rLH), and rat thyroid-stimulating hormone (rTSH) have been localized in rat anterior pituitaries by immunocytochemistry using light and electron microscopy. With the light microscope, LHbeta and FSHbeta were found in the same cells, which were violet after the alcian blue-periodic acid Schiff (AB-PAS) staining. TSHbeta was found in polygonal or stellate cells that were blue after AB-PAS. With the electron microscope, the thyrotropic cells contained very small secretory granules. LHbeta and FSHbeta were found in various types of cells (types A and B and their intermediate forms), which had previously been identified as gonadotropic cells. On serial ultrathin sections using the postembedding method the same cells and even some granules inside these cells were stained by both anti-rLHbeta and anti-rFSHbeta. A comparison of binding sites of anti-rLHbeta was performed using the preembeeding and the postembeeding methods. Antigenicity was observed on secretory granules whatever the method used. However, binding sites of anti-rLHbeta were detected inside the cisternae of the rough endoplasmic reticulum only with the preembedding method.



1972 ◽  
Vol 50 (7) ◽  
pp. 1611-1615 ◽  
Author(s):  
Lawrence C. W. Jensen

A previous paper in this series has reported on the effect of bisecting Aquilegia floral apices of different developmental stages by maintaining a continuous photographic record of living buds (Jensen 1971). The current paper is a preliminary light and electron microscope study of the cytological changes which occur following bisection of very young buds (sepal to petal stages). Bisected buds show a progressive increase in size of grains which are positive to periodic acid – Schiff stain up to 2 days after incision, followed by a progressive decrease in size up to 7 days after incision. These grains are probably starch as they were absent in sections treated with α-amylase and malt diastase. It is suggested that after bisection the buds are in a resting state for 1 to 2 days during which time sucrose is absorbed from the medium and stored as starch. As regeneration of a new apex proceeds, starch is digested and used by the cells of the growing bud.



1979 ◽  
Vol 57 (2) ◽  
pp. 314-322 ◽  
Author(s):  
M. Samuel Cannon ◽  
A. M. Cannon

Blood leukocytes of Bufo alvarius were studied by light and phase-contrast microscopy and histochemical techniques for the localization of glycogen and several hydrolytic enzymes, i.e., acid and alkaline phosphatases, nonspecific esterase, beta-glucuronidase, aryl-sulfatase, and myeloperoxidase (peroxidase). Neutrophils were the only leukocytes to demonstrate alkaline phosphatase activity, while beta-glucuronidase and aryl-sulfatase were not observed in any leukocytes. Periodic acid – Schiff (PAS) positive granules and granules containing hydrolytic enzymes occurred in varying amounts in leukocytes. In eosinophils, most glycogen was associated with smaller granules, while the larger refractile granules were PAS negative. Small lymphocytes were myeloperoxidase (peroxidase) negative. The present study agrees with previous investigations in mammals which indicate that specific granules in granulocytes may be PAS positive as well as contain one or more hydrolytic enzymes. In small lymphocytes of B. alvarius, PAS positive and acid phosphatase positive granules correspond to neutral red granules seen in supravital films. Furthermore, the appearance and histochemical reactivity of acid phosphatase granules in mature neutrophils, metamyelocytes, and late myelocytes correspond closely with the appearance and number of specific neutrophilic granules seen in Wright–Giemsa preparations and with PAS positive granules.



1973 ◽  
Vol 58 (3) ◽  
pp. 503-521 ◽  
Author(s):  
C. Tougard ◽  
B. Kerdelhue ◽  
A. Tixier-Vidal ◽  
M. Jutisz

The binding sites of antisera generated in the guinea pig against ovine luteinizing hormone (oLH) and its two subunits (oLHα and oLHß) have been localized in rat anterior pituitaries taken from normal or castrated males and from ovariectomized females with the peroxidase-labeled antibody method, using light and electron microscopy. With the light microscope, the cells positive with antiserum to ovine luteinizing hormone (A-oLH) were violet after the Alcian blue-periodic acid-Schiff (AB-PAS) staining; they were also positive for A-oLHα and for A-oLHß and, from castrated males, they displayed an increased affinity for A-oLHß. Another cell type which was blue after the AB-PAS method reacted with the A-oLHα only; these cells, presumably thyrotropic cells, were retracted after castration and, besides their affinity for A-oLHα, acquired an affinity for A-oLHß. As seen through the electron microscope, two cell types were positive for A-oLH, A-oLHß, and A-oLHα and may be identified as luteinizing hormone-secreting cells. Type A cells were characterized by two classes of rounded, secretory granules. Type B cells were smaller and contained only small secretory granules. 1 mo after the rats were castrated the type A cells were hypertrophied and vacuolized. In both cases the secretory granules were the main sites of the antigenicity with the three antisera. A positive reaction was also found in the cytoplasm, particularly in hypertrophied cells from ovariectomized females and with A-oLHß. The cisternae of the rough endoplasmic reticulum were usually negative, except in highly degranulated cells from ovariectomized females and with A-oLHß.



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