Immunogold Localization of Molecular Constituents Associated with Basal Bodies,  Flagella, and Extracellular Matrices in Male Gametes of Land Plants

As the oldest extant lineages of land plants, bryophytes provide a living laboratory in which to evaluate morphological adaptations associated with early land existence. In this paper we examine reproductive and structural innovations in the gametophyte and sporophyte generations of hornworts, liverworts, mosses and basal pteridophytes. Reproductive features relating to spermatogenesis and the architecture of motile male gametes are overviewed and evaluated from an evolutionary perspective. Phylogenetic analyses of a data set derived from spermatogenesis and one derived from comprehensive morphogenetic data are compared with a molecular analysis of nuclear and mitochondrial small subunit rDNA sequences. Although relatively small because of a reliance on water for sexual reproduction, gametophytes of bryophytes are the most elaborate of those produced by any land plant. Phenotypic variability in gametophytic habit ranges from leafy to thalloid forms with the greatest diversity exhibited by hepatics. Appendages, including leaves, slime papillae and hairs, predominate in liverworts and mosses, while hornwort gametophytes are strictly thalloid with no organized external structures. Internalization of reproductive and vegetative structures within mucilage–filled spaces is an adaptive strategy exhibited by hornworts. The formative stages of gametangial development are similar in the three bryophyte groups, with the exception that in mosses apical growth is intercalated into early organogenesis, a feature echoed in moss sporophyte ontogeny. A monosporangiate, unbranched sporophyte typifies bryophytes, but developmental and structural innovations suggest the three bryophyte groups diverged prior to elaboration of this generation. Sporophyte morphogenesis in hornworts involves non–synchronized sporogenesis and the continued elongation of the single sporangium, features unique among archegoniates. In hepatics, elongation of the sporophyte seta and archegoniophore is rapid and requires instantaneous wall expandability and hydrostatic support. Unicellular, spiralled elaters and capsule dehiscence through the formation of four regular valves are autapomorphies of liverworts. Sporophytic sophistications in the moss clade include conducting tissue, stomata, an assimilative layer and an elaborate peristome for extended spore dispersal. Characters such as stomata and conducting cells that are shared among sporophytes of mosses, hornworts and pteridophytes are interpreted as parallelisms and not homologies. Our phylogenetic analysis of three different data sets is the most comprehensive to date and points to a single phylogenetic solution for the evolution of basal embryophytes. Hornworts are supported as the earliest divergent embryophyte clade with a moss/liverwort clade sister to tracheophytes. Among pteridophytes, lycophytes are monophyletic and an assemblage containing ferns, Equisetum and psilophytes is sister to seed plants. Congruence between morphological and molecular hypotheses indicates that these data sets are tracking the same phylogenetic signal and reinforces our phylogenetic conclusions. It appears that total evidence approaches are valuable in resolving ancient radiations such as those characterizing the evolution of early embryophytes. More information on land plant phylogeny can be found at: http://www.science.siu.edu/landplants/index.html.

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Diversity of Sperm Cell Architecture in Ferns

Microscopy and Microanalysis ◽

10.1017/s1431927600028336 ◽

2001 ◽

Vol 7 (S2) ◽

pp. 452-453

Author(s):

Thomas H. Johnson ◽

Steven J. Schmitt ◽

Karen S. Renzaglia

Keyword(s):

Phosphate Buffer ◽

Vascular Plants ◽

Sperm Cell ◽

Electron Microscope Study ◽

Osmium Tetroxide ◽

Land Plants ◽

Scanning Electron Microscope Study ◽

Leptosporangiate Fern ◽

Male Gametes ◽

Cell Architecture

Among land plants, lower vascular plants produce the most elaborate of all male gametes. in order to characterize the degree of variability in sperm cell architecture among ferns, this scanning electron microscope study was undertaken on three highly disparate genera: Ceratopteris(a derived leptosporangiate fern) Angiopteris(a derived eusporangiate fern) and Psilotum(a putatively basal eusporangiate fern).Mature gametophytes were placed in 0.01M phosphate buffer (pH ca. 7.2) or distilled water until spermatozoids were released. Gametophyte portions were removed and the spermatozoid suspension fixed with 2% glutaraldehyde in 0.05M phosphate buffer. Post-fixation utilized 1% aqueous osmium tetroxide for lhr, followed by rinsing and dehydration in ethanol (10 min @ 25, 50, 75 and 100%). The dehydrated pellet was suspended in 100% hexamethyldisilazane, immediately centrifuged and the pellet deposited onto clean glass coverslips. Specimens were dried at 60°C, sputtered with ca. 350 A of palladium/gold and imaged in a Hitachi S570 SEM.

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Molecular Control of Sporophyte-Gametophyte Ontogeny and Transition in Plants

Frontiers in Plant Science ◽

10.3389/fpls.2021.789789 ◽

2022 ◽

Vol 12 ◽

Author(s):

Saurabh Pandey ◽

Amir Bahram Moradi ◽

Oleksandr Dovzhenko ◽

Alisher Touraev ◽

Klaus Palme ◽

...

Keyword(s):

Doubled Haploids ◽

Basic Research ◽

Land Plants ◽

Long Distance ◽

Developmental Programs ◽

Molecular Control ◽

Evolutionary Origins ◽

Male Gametes ◽

Sporophytic Development ◽

Alternation Of Generations

Alternation of generations between a sporophytic and gametophytic developmental stage is a feature common to all land plants. This review will discuss the evolutionary origins of these two developmental programs from unicellular eukaryotic progenitors establishing the ability to switch between haploid and diploid states. We will compare the various genetic factors that regulate this switch and highlight the mechanisms which are involved in maintaining the separation of sporophytic and gametophytic developmental programs. While haploid and diploid stages were morphologically similar at early evolutionary stages, largely different gametophyte and sporophyte developments prevail in land plants and finally allowed the development of pollen as the male gametes with specialized structures providing desiccation tolerance and allowing long-distance dispersal. Moreover, plant gametes can be reprogrammed to execute the sporophytic development prior to the formation of the diploid stage achieved with the fusion of gametes and thus initially maintain the haploid stage. Upon diploidization, doubled haploids can be generated which accelerate modern plant breeding as homozygous plants are obtained within one generation. Thus, knowledge of the major signaling pathways governing this dual ontogeny in land plants is not only required for basic research but also for biotechnological applications to develop novel breeding methods accelerating trait development.

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Comparative transcriptomic analysis reveals conserved transcriptional programs underpinning organogenesis and reproduction in land plants

10.1101/2020.10.29.361501 ◽

2020 ◽

Author(s):

Irene Julca ◽

Camilla Ferrari ◽

María Flores-Tornero ◽

Sebastian Proost ◽

Ann-Cathrin Lindner ◽

...

Keyword(s):

Phylogenetic Trees ◽

Large Scale ◽

Expression Profiles ◽

Gene Families ◽

Male Reproduction ◽

Land Plants ◽

Easy Access ◽

Specific Gene ◽

Male Gametes ◽

Organ Specific

AbstractThe evolution of plant organs, including leaves, stems, roots, and flowers, mediated the explosive radiation of land plants, which shaped the biosphere and allowed the establishment of terrestrial animal life. Furthermore, the fertilization products of angiosperms, seeds serve as the basis for most of our food. The evolution of organs and immobile gametes required the coordinated acquisition of novel gene functions, the co-option of existing genes, and the development of novel regulatory programs. However, our knowledge of these events is limited, as no large-scale analyses of genomic and transcriptomic data have been performed for land plants. To remedy this, we have generated gene expression atlases for various organs and gametes of 10 plant species comprising bryophytes, vascular plants, gymnosperms, and flowering plants. Comparative analysis of the atlases identified hundreds of organ- and gamete-specific gene families and revealed that most of the specific transcriptomes are significantly conserved. Interestingly, the appearance of organ-specific gene families does not coincide with the corresponding organ’s appearance, suggesting that co-option of existing genes is the main mechanism for evolving new organs. In contrast to female gametes, male gametes showed a high number and conservation of specific genes, suggesting that male reproduction is highly specialized. The expression atlas capturing pollen development revealed numerous transcription factors and kinases essential for pollen biogenesis and function. To provide easy access to the expression atlases and these comparative analyses, we provide an online database, www.evorepro.plant.tools, that allows the exploration of expression profiles, organ-specific genes, phylogenetic trees, co-expression networks, and others.

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Scanning Electron Microscopy of Motile Male Gametes of Land Plants

BIO-PROTOCOL ◽

10.21769/bioprotoc.2570 ◽

2017 ◽

Vol 7 (19) ◽

Author(s):

Karen Renzaglia ◽

Renee Lopez ◽

Steven Schmitt

Keyword(s):

Electron Microscopy ◽

Scanning Electron Microscopy ◽

Land Plants ◽

Male Gametes ◽

Scanning Electron

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Diversity, development and evolution of archegonia in land plants

Botanical Journal of the Linnean Society ◽

10.1093/botlinnean/boaa077 ◽

2020 ◽

Author(s):

Dmitry D Sokoloff ◽

Margarita V Remizowa

Keyword(s):

Pollen Tube ◽

Reproductive Organs ◽

Land Plant ◽

Land Plants ◽

Comparative Approach ◽

Egg Cell ◽

Plant Structure ◽

Male Gametes ◽

Canal Cell ◽

Cover Cell

Abstract We review the diversity and development of archegonia, the female reproductive organs of land-plant gametophytes. The archegonium is a uniquely land-plant structure, and studies of its evolution benefit from use of a comparative approach in a phylogenetic context. Archegonia of most land plants share a common developmental motif, here termed a T-shaped pattern. A primary axial cell produces a primary cover cell and a central cell by horizontal division. The upper cell usually divides vertically and the lower one horizontally. In mosses such as Atrichum, the T-shaped stage is shifted towards the end of archegonium development, whereas in vascular plants it appears at the beginning of development, but these stages are still probably homologous. The fully exposed archegonia are traditionally viewed as an ancestral (plesiomorphic) condition in land plants, but there is no direct support for this view. We speculate that the fully exposed condition is derived and synapomorphic for setaphytes (mosses and liverworts). The fully sunken hornwort archegonia may be similar to the ancestral type of land-plant archegonia. Developmental evidence suggests that archegonium necks of setaphytes and tracheophytes are not homologous to each other. The neck wall of pteridophytes is composed of four-celled tiers, and one such tier is present in gymnosperms with motile male gametes. Neck-cell arrangement is much more plastic in archegonia of gymnosperms with sperm cell delivery by pollen tube (siphonogamy), in which the neck plays a role similar to pollen-tube transmitting tissue of angiosperms. Angiosperm synergids are probably homologues of gymnosperm neck cells, and the angiosperm egg cell is probably homologous to the ventral canal cell of gymnosperms. Developmental genetic bases of archegonium diversity in land plants remain to be understood. Even descriptive developmental data are currently missing or controversial for some key lineages of land plants.

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Glucose metabolism in cancer cells: immunogold localization of hexokinase to the outer mitochondrial membrane

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100141597 ◽

1995 ◽

Vol 53 ◽

pp. 1044-1045

Author(s):

Krishan K. Arora ◽

Glenn L. Decker ◽

Peter L. Pedersen

Keyword(s):

Tumor Cells ◽

Mitochondrial Membrane ◽

Present Report ◽

Large Fraction ◽

Mitochondrial Fraction ◽

Immunogold Labeling ◽

Outer Mitochondrial Membrane ◽

Immunogold Localization ◽

Hexokinase Activity ◽

Normal Tissues

Hexokinase (ATP: D-hexose 6-phophotransferase EC 2.7.1.1) is the first enzyme of the glycolytic pathway which commits glucose to catabolism by catalyzing the phosphorylation of glucose with ATP. Previous studies have shown diat hexokinase activity is markedly elevated in rapidly growing tumor cells exhibiting high glucose catabolic rates. A large fraction (50-80%) of this enzyme activity is bound to the mitochondrial fraction (1,2) where it has preferred access to ATP (3). In contrast,the hexokinase activity of normal tissues is quite low, with one exception being brain which is a glucose-utilizing tissue (4). Biochemical evidence involving rigorous subfractionation studies have revealed striking differences between the subcellular distribution of hexokinase in normal and tumor cells [See review by Arora et al (4)].In the present report, we have utilized immunogold labeling techniques to evaluate die subcellular localization of hexokinase in highly glycolytic AS-30D hepatoma cells and in the tissue of its origin, i.e., rat liver.

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Ciliary coordination in newt lung cells requires microtubule-based linkages between basal bodies: A correlative light and EM study

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100123258 ◽

1992 ◽

Vol 50 (1) ◽

pp. 570-571

Author(s):

Robert Hard ◽

Gerald Rupp ◽

Matthew L. Withiam-Leitch ◽

Lisa Cardamone

Keyword(s):

Basal Body ◽

Untreated Control ◽

Beat Frequency ◽

Primary Cultures ◽

Living Cells ◽

Power Stroke ◽

Ultrastructural Changes ◽

Lung Cells ◽

Basal Bodies ◽

Ciliated Cells

In a coordinated field of beating cilia, the direction of the power stroke is correlated with the orientation of basal body appendages, called basal feet. In newt lung ciliated cells, adjacent basal feet are interconnected by cold-stable microtubules (basal MTs). In the present study, we investigate the hypothesis that these basal MTs stabilize ciliary distribution and alignment. To accomplish this, newt lung primary cultures were treated with the microtubule disrupting agent, Colcemid. In newt lung cultures, cilia normally disperse in a characteristic fashion as the mucociliary epithelium migrates from the tissue explant. Four arbitrary, but progressive stages of dispersion were defined and used to monitor this redistribution process. Ciliaiy beat frequency, coordination, and dispersion were assessed for 91 hrs in untreated (control) and treated cultures. When compared to controls, cilia dispersed more rapidly and ciliary coordination decreased markedly in cultures treated with Colcemid (2 mM). Correlative LM/EM was used to assess whether these effects of Colcemid were coupled to ultrastructural changes. Living cells were defined as having coordinated or uncoordinated cilia and then were processed for transmission EM.

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Immunogold localization of calmodulin in root caps of the maize Cultivar Merit

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100160923 ◽

1990 ◽

Vol 48 (3) ◽

pp. 674-675

Author(s):

P.T. Nguyen ◽

C. Uphoff ◽

C.L. Stinemetz

Keyword(s):

Calcium Binding ◽

Calcium Transport ◽

Primary Role ◽

Immunogold Localization ◽

Root Tips ◽

Electrical Currents ◽

Considerable Evidence ◽

Maize Cultivar ◽

Gravity Response ◽

Induced Changes

Considerable evidence suggest that the calcium-binding protein calmodulin (CaM) may mediate calcium action and/or transport important in the gravity response of plants. Calmodulin is present in both shoots and roots and is capable of regulating calcium transport in plant vesicles. In roots calmodulin is concentrated in the tip, the gravisensing region of the root; and is reported to be closely associated with amyloplasts, organelles suggested to play a primary role in gravi-perception. Inhibitors of CaM such as chlorpromazine, calmidazolium, and compound 48/80 interfere with the gravitropic response of both snoots and roots. The magnitude of the inhibition corresponded well with the extent to which the drug binds to endogenous CaM. Compound 48/80 and calmidazolium block gravi-induced changes in electrical currents across root tips, a phenomenon thought to be associated with the sensing of the gravity stimulus.In this study, we have investigated the subcellular distribution of CaM in graviresponsive and non-graviresponsive root caps of the maize cultivar Merit.

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