Embryology of Festuca microstachys (Gramineae)

1977 ◽  
Vol 55 (13) ◽  
pp. 1768-1782 ◽  
Author(s):  
Jack Maze ◽  
Lesley R. Bohm
Keyword(s):  
Cell Division ◽  
Outer Integument ◽  
Outer Wall ◽  
Ovary Wall ◽  
Dense Layer ◽  
Stored Energy ◽  
Protective Function ◽  
Starch Grains ◽  
Different Types ◽  
Degree Of Similarity

As the ovary wall develops, some similar events are seen in the dorsal and upper portions. These are as follows: (1) the deposition of many starch grains in most of the ground meristem cells; (2) considerable cell growth in most of the ground meristem cells; (3) the development of a thick outer wall on the outer protoderm of the ovary; and (4) elongation in the protoderm cells lining the inner part of the ovary. Unlike the upper ovary wall, starch grains appear in the outer protoderm cells of the dorsal ovary wall. A cytoplasmically dense layer of cells subjacent to the inner protoderm of the dorsal ovary wall continues to undergo cell division when other ground meristem cells are enlarging. This layer of cytoplasmically dense cells is the only recognizable layer in the ovary wall when the seed is mature. The ovule is bitegmetic, hemianatropous, and tenuinucellate. Integuments are protodermal in origin and both are mostly two cells thick. Cell division is more prolonged in the inner than in the outer integument and the inner layer of the inner integument develops safraninophilic granules in the cytoplasm of its cells. The outer integument is stretched and obliterated before the inner. As a result of faster growth in the basal end of the nucellus, the ovule undergoes a change in orientation from orthotropous to hemianatropous. Periclinal divisions are rare in the nucellar protoderm. The nucellus is eliminated by the time that the seed is mature. Megagametophyte development is normal and callose is associated with megaspores. Unlike most grasses, only three antipodals form but each antipodal is large and contains what appear to be many atypical nuclei. The endosperm initially lacks cell walls but they appear later in development. When the endosperm is cellular, its surface layer is meristematic. Starch grains are numerous in the endosperm cells and the cells have thick walls. The thick walls are a possible source of stored energy. A cuticle on the surface of the endosperm may serve a protective function. Different types of grass ovules are the result of different degrees of the same developmental phenomenon at comparable sites. Relationships as determined by cluster analysis of a similarity matrix based on detailed embryological data show that four members of the tribe Stipeae cluster together and this cluster is separate from a cluster consisting of F. microstachys and Agrostis interrupta. Furthermore, the degree of similarity between the four stipeae was higher than that between F. microstachys and A. interrupta. This correlates well with the modem opinion that Festuca and Agrostis are in separate tribes.

The growth of supernumerary legs in the cockroach

Development ◽  
1986 ◽  
Vol 92 (1) ◽  
pp. 115-131
Author(s):  
Paul R. Truby
Keyword(s):  
Wound Healing ◽  
Cell Division ◽  
Rapid Rate ◽  
Large Area ◽  
Anteroposterior Axis ◽  
Cell Divisions ◽  
Leucophaea Maderae ◽  
Different Types ◽  
Local Cell

When the anteroposterior axis of a cockroach leg is reversed at a graft by exchanging a left leg for a right leg at the mid-tibia level, regeneration occurs in the region of the graft/host junction. This results in the formation of a pair of lateral supernumerary legs. In these experiments the patterns of cell division which take place during supernumerary leg formation were observed in sections of regenerating legs of the cockroach Leucophaea maderae. Early patterns of cell division resemble those seen in control grafts in which no axial reversal had been carried out during grafting. These cell divisions are associated with the process of wound healing. Later, a large area of the epidermis proximal to the graft/host junction becomes activated and shows a rapid rate of cell division. This area forms two outgrowths which grow by cell division throughout their epidermis to form the epidermis of the supernumerary legs. The results are more consistent with the view that the formation of supernumerary legs involves dedifferentiation of the epidermis in the region of the graft/host junction to form a blastema, rather than being due to local cell division at the point of maximum pattern discontinuity. This conclusion is used to offer an explanation for the range of different types of outcome of left-right grafts that has been observed.

Unequal cleavage in leech embryos: zygotic transcription is required for correct spindle orientation in subset of early blastomeres

Development ◽  
1996 ◽  
Vol 122 (2) ◽  
pp. 599-606
Author(s):  
S.T. Bissen ◽  
C.M. Smith
Keyword(s):  
Cell Division ◽  
Early Period ◽  
Spindle Orientation ◽  
Mitotic Spindles ◽  
Maternal Control ◽  
Transcription Analysis ◽  
Cell Divisions ◽  
Zygotic Transcription ◽  
Different Types ◽  
Alpha Amanitin

Leech embryos undergo invariant sequences of equal and unequal cell divisions to give rise to identifiable progeny cells. While many of the early cleavages are under maternal control, the divisions of a subset of early blastomeres (the large cells of the D' lineage) are perturbed after the inhibition of zygotic transcription. Analysis of the different types of cells produced in embryos injected with the transcriptional inhibitor, alpha-amanitin, revealed that the symmetry of cell division is perturbed in these large D'-derived cells during this early period of development. These cells, which would normally undergo a series of equal and unequal cleavages, always undergo equal cleavages after the inhibition of zygotic transcription. It appears that zygotically transcribed gene product(s) are required in the large cells of the D' lineage to orient the mitotic spindles properly for these unequal cell cleavages.

Secretion and ultrastructure of the periostracum of some terebratulide brachiopods

1978 ◽  
Vol 202 (1147) ◽  
pp. 191-209 ◽  
Keyword(s):  
Outer Boundary ◽  
Basal Layer ◽  
Dense Layer ◽  
Simple Type ◽  
Cell Region ◽  
Primitive Type ◽  
Representative Species ◽  
Different Types ◽  
History Of ◽  
Partial Resorption

A survey of the periostracum of representative species of living terebratulide brachiopods reveals that it originates within a slot separating the lobate and vesicular cells of the outer mantle lobe and that three fundamentally different types are synthesized beneath a mucopolysaccharide film exuded by the lobate cells. The simplest type, which is found among the Terebratulacea, consist of a uniformly textured, electron-dense layer, either splaying externally at irregular intervals into acutely disposed subsidiary sheets up to 4 μm long as in Terebratulina , or bearing externally scattered secretion droplets and rare vesicles as in Liothyrella . This simple type of periostracum is a correlative of an undifferentiated basal layer which underlies the periostracal succession of all known terebratellaceans, not only in its structure, but also in its secretion by the vesicular cell region of the outer mantle lobe. The basal layer of terebratellaceans, however, supports a complex superstructure. In Waltonia and other terebratellids as well as dallinids, kraussinids, laqueids and possibly platitiids, the superstructure is an elaborate proteinous succession composed of vesicles and secretion droplets amalgamated by accretionary growth and fashioned by partial resorption into a labyrinthine structure covered by fibrillar proteinous rods arranged in undulating interconnected rows. In the megathyridid Gwynia , the superstructure consists of proteinous sheets secreted as a series of isoclinal folds normal to the basal layer. Both types of superstructure as well as the secretion droplets and vesicles of Liothyrella are exuded mainly by distal lobate cells forming the outer boundary of the periostracal slot. This difference in origin between the basal layer and the superstructure precludes consideration of periostraca as chronologically stratified successions. Concordance of the various types with the phylogenetic history of the Order based mainly on the evolution of the lophophore supports, suggests that the simplest periostracum is the most primitive type and that it may have been widespread among Palaeozoic brachiopods.

scholarly journals Chromosome interaction over a distance in meiosis

2015 ◽  
Vol 2 (2) ◽  
pp. 150029 ◽  
Author(s):  
Mary Brady ◽  
Leocadia V. Paliulis
Keyword(s):  
Cell Division ◽  
Sex Chromosomes ◽  
Sister Chromatid ◽  
Daughter Cell ◽  
Sister Chromatid Cohesion ◽  
Sister Chromatids ◽  
Physical Connection ◽  
Chromatid Cohesion ◽  
Different Types ◽  
Random Segregation

The challenge of cell division is to distribute partner chromosomes (pairs of homologues, pairs of sex chromosomes or pairs of sister chromatids) correctly, one into each daughter cell. In the ‘standard’ meiosis, this problem is solved by linking partners together via a chiasma and/or sister chromatid cohesion, and then separating the linked partners from one another in anaphase; thus, the partners are kept track of, and correctly distributed. Many organisms, however, properly separate chromosomes in the absence of any obvious physical connection, and movements of unconnected partner chromosomes are coordinated at a distance. Meiotic distance interactions happen in many different ways and in different types of organisms. In this review, we discuss several different known types of distance segregation and propose possible explanations for non-random segregation of distance-segregating chromosomes.

scholarly journals Bivariate flow cytometric analysis and sorting of different types of maize starch grains

2017 ◽  
Vol 93 (2) ◽  
pp. 213-221 ◽  
Author(s):  
Xudong Zhang ◽  
Jiaojiao Feng ◽  
Heng Wang ◽  
Jianchu Zhu ◽  
Yuyue Zhong ◽  
...  
Keyword(s):  
Flow Cytometric Analysis ◽  
Maize Starch ◽  
Starch Grains ◽  
Flow Cytometric ◽  
Different Types

scholarly journals A Pan-Cancer Analysis of Cystatin E/M Reveals Its Dual Functional Effects and Positive Regulation of Epithelial Cell in Human Tumors

2021 ◽  
Vol 12 ◽  
Author(s):  
Dahua Xu ◽  
Shun Ding ◽  
Meng Cao ◽  
Xiaorong Yu ◽  
Hong Wang ◽  
...  
Keyword(s):  
Epithelial Cell ◽  
Cell Infiltration ◽  
Dual Function ◽  
Melanoma Metastasis ◽  
Protective Function ◽  
Mesenchymal Transition ◽  
Dual Functional ◽  
Different Types ◽  
Cancer Types ◽  
Pan Cancer

Cystatin E/M (CST6), a representative cysteine protease inhibitor, plays both tumor-promoting and tumor-suppressing functions and is pursued as an epigenetically therapeutic target in special cancer types. However, a comprehensive and systematic analysis for CST6 in pan-cancer level is still lacking. In the present study, we explored the expression pattern of CST6 in multiple cancer types across ∼10,000 samples from TCGA (The Cancer Genome Atlas) and ∼8,000 samples from MMDs (Merged Microarray-acquired Datasets). We found that the dynamic expression alteration of CST6 was consistent with dual function in different types of cancer. In addition, we observed that the expression of CST6 was globally regulated by the DNA methylation in its promoter region. CST6 expression was positively correlated with the epithelial cell infiltration involved in epithelial-to-mesenchymal transition (EMT) and proliferation. The relationship between CST6 and tumor microenvironment was also explored. In particular, we found that CST6 serves a protective function in the process of melanoma metastasis. Finally, the clinical association analysis further revealed the dual function of CST6 in cancer, and a combination of the epithelial cell infiltration and CST6 expression could predict the prognosis for SKCM patients. In summary, this first CST6 pan-cancer study improves the understanding of the dual functional effects on CST6 in different types of human cancer.

scholarly journals Assembly and regulation of γ-tubulin complexes

Open Biology ◽  
2018 ◽  
Vol 8 (3) ◽  
pp. 170266 ◽  
Author(s):  
Dorian Farache ◽  
Laurent Emorine ◽  
Laurence Haren ◽  
Andreas Merdes
Keyword(s):  
Cell Division ◽  
Chromosome Segregation ◽  
Intracellular Transport ◽  
Eukaryotic Cells ◽  
Cellular Structures ◽  
Activator Proteins ◽  
Multiprotein Complexes ◽  
Microtubule Organizing Centres ◽  
Different Types ◽  
Ring Complexes

Microtubules are major constituents of the cytoskeleton in all eukaryotic cells. They are essential for chromosome segregation during cell division, for directional intracellular transport and for building specialized cellular structures such as cilia or flagella. Their assembly has to be controlled spatially and temporally. For this, the cell uses multiprotein complexes containing γ-tubulin. γ-Tubulin has been found in two different types of complexes, γ-tubulin small complexes and γ-tubulin ring complexes. Binding to adaptors and activator proteins transforms these complexes into structural templates that drive the nucleation of new microtubules in a highly controlled manner. This review discusses recent advances on the mechanisms of assembly, recruitment and activation of γ-tubulin complexes at microtubule-organizing centres.

scholarly journals Broad-spectrum survey of medicinal plants as a potential source of anticancer agents

2022 ◽  
Vol 21 (1) ◽  
pp. 1-40
Author(s):  
K Saranya ◽  
◽  
V Manivasagan ◽  
K Gopi ◽  
K Karthik ◽  
...  
Keyword(s):  
Cell Division ◽  
Side Effects ◽  
Medicinal Plants ◽  
Broad Spectrum ◽  
Anticancer Agents ◽  
Cancer Treatments ◽  
Potential Source ◽  
African Populations ◽  
Different Types ◽  
Different Parts

Cancer is an abnormal and uncontrolled growth of cells that spreads through cell division. There are different types of medicines available to treat cancers, but no drug is found to be fully effective and safe for humans. The major problem involved in the cancer treatments is the toxicity of the established drug and their side effects. Medicinal plants are used as folk medicines in Asian and African populations for thousands of years. 60% of the drugs for treating cancer are derived from plants. More than 3000 plants have anticancer activity. The present review aims at the study of a broad spectrum survey of plants having anticancer components for different type of cancers. This article consists of 364 medicinal plants and their different parts as potential Source of Anticancer Agents.

Ultrastructure of cell division in Cladophora. Pregametangial cell division in the haploid generation of Cladophora flexuosa

1976 ◽  
Vol 54 (13) ◽  
pp. 1546-1560 ◽  
Author(s):  
J. L. Scott ◽  
K. W. Bullock
Keyword(s):  
Life History ◽  
Electron Microscope ◽  
Cell Division ◽  
Nuclear Envelope ◽  
Double Membrane ◽  
Cell Divisions ◽  
Gamete Formation ◽  
Reproductive Differentiation ◽  
Different Types ◽  
Vacuolar System

Cell division preceding gamete formation in the haploid generation of Cladophora flexuosa was studied with the electron microscope. Numerous, asynchronous mitotic nuclear divisions are concurrent with the progressive cleavage of the cytoplasm by invaginations of a central and peripheral vacuolar system. The spindle is enclosed by the nuclear envelope during all stages of mitosis and is associated with polar centriole pairs. The cytokinetic process is not associated with microtubules and is basically similar to that observed in other macroscopic, multinucleate green algae. Unusual mitochondria, characterized by specialized double-membrane-enclosed, presumptive DNA regions, were found during the later stages of reproductive differentiation. It is emphasized that the different types of cell divisions which can occur in plants possessing a haplodiplontic type of life history should all be thoroughly examined before the establishment of a particular mitotic sequence for any given species.

Ultrastructure of sporodochium and conidium development in the anamorphic fungus Epicoccum nigrum

2005 ◽  
Vol 83 (10) ◽  
pp. 1354-1363 ◽  
Author(s):  
C.W. Mims ◽  
E.A. Richardson
Keyword(s):  
Basal Cell ◽  
Apical Cell ◽  
Outer Wall ◽  
Wall Layer ◽  
Dense Layer ◽  
Epicoccum Nigrum ◽  
Transparent Layer ◽  
Transmission Electron ◽  
Anamorphic Fungus ◽  
Agar Surface

Scanning and transmission electron microscopy were used to examine sporodochium and conidium development in Epicoccum nigrum Link. Each sporodochium, a slightly raised mass of hyphae consisting of a pseudoparenchymous stroma covered with muriform conidia, arose from a group of loosely packed hyphae that formed on the agar surface. Conidiophores developed from the surface of the stroma. Each possessed a two-layered wall consisting of an inner electron transparent layer and an outer electron dense layer. Most conidiophores consisted of only two cells, the apical of which became swollen and gave rise to a solitary conidium initial in a holoblastic fashion. This initial enlarged and became divided into a smaller basal cell and a larger apical cell by a transverse septum. While the basal cell did not divide further, the apical cell became divided into numerous cells as the result of the formation of longitudinal and transverse septa. As a conidium matured the electron transparent inner layer of its wall thickened while the surface of its electron dense outer wall layer became transformed into small wart-like surface ornaments. Conidium secession was schizolytic and involved a transverse splitting of the septum separating the basal cell of a conidium from its conidiophore. The end of the basal cell and the tip of the conidiophore became rounded off during conidium secession.

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