Sperm morphology of two species of Olivancillaria (Gastropoda: Olividae) from the south-western Atlantic

2012 ◽  
Vol 93 (3) ◽  
pp. 825-831 ◽  
Author(s):  
Valeria Teso ◽  
Juliana Giménez
Keyword(s):  
Sperm Morphology ◽  
Sperm Ultrastructure ◽  
Tail Region ◽  
Western Atlantic ◽  
Acrosomal Vesicle ◽  
Double Electron ◽  
Snail Family ◽  
Membrane Bound ◽  
Slight Narrowing ◽  
Different Levels

Sperm ultrastructure in two species of the marine snail family Olividae is examined. Euspermatozoa of both species are composed of a conical, membrane-bound acrosomal vesicle; an axial rod and a basal plate similar in both species; a solid and highly electron-dense nucleus; an elongate midpiece consisting of the axoneme sheathed by helical mitochondrial elements; an elongate glycogen piece; a double electron-dense ring at the junction of the midpiece and glycogen piece; and a free tail region. The slight narrowing in the acrosomal vesicle invagination is situated in different levels between Olivancillaria deshayesiana and Olivancillaria carcellesi. This morphology could be considered as a specific character. The length of the nucleus in O. carcellesi and in O. deshayesiana is shorter than that of other neogastropods, and could be diagnostic at family level.

Spermatogenesis and sperm morphology in Trophon geversianus (Gastropoda: Muricidae)

2013 ◽  
Vol 93 (7) ◽  
pp. 1881-1886 ◽  
Author(s):  
Juliana Giménez
Keyword(s):  
Sperm Morphology ◽  
Developmental Pattern ◽  
Diagnostic Feature ◽  
Tail Region ◽  
Acrosomal Vesicle ◽  
Dense Nucleus ◽  
Dense Vesicles

The ultrastructure of spermatogenesis, the euspermatozoa and paraspermatozoa, is investigated in Trophon geversianus. Spermatogenesis follows the general developmental pattern of caenogastropods. Paraspermatid development is characterized by elongation of the cell, concurrent with the appearance of a cytoplasmic elongation at the apex of the cell and the breakdown of the nucleus into small round fragments (caryomerites). Euspermatozoa consist of: a tall, conical acrosomal vesicle (with a invagination); a rod-shaped, highly electron-dense nucleus with an internal axoneme; an elongate midpiece consisting of the axoneme sheathed by helical mitochondrial elements; an elongate glycogen piece; and a short free-tail region. Paraspermatozoa of T. geversianus are vermiform. They contain approximately 12–16 axonemes arranged peripherally, numerous oblong dense vesicles, numerous less dense (round) vesicles, and scattered mitochondria. Most of the euspermatozoal features of T. geversianus are also observed in many neogastropods. However, the presence of the axoneme continuously located inside of the nucleus has not been reported before, and may prove to be a diagnostic feature of the Muricidae.

Sperm ultrastructure in two species of Brachidontes (Bivalvia, Mytilidae) from the south-western Atlantic Ocean

2015 ◽  
Vol 95 (5) ◽  
pp. 991-998 ◽  
Author(s):  
María Eugenia Torroglosa ◽  
Juliana Giménez
Keyword(s):  
Sperm Morphology ◽  
Spherical Nucleus ◽  
Rocky Shores ◽  
Sperm Ultrastructure ◽  
Intertidal Area ◽  
Western Atlantic ◽  
Transmission Electron ◽  
Anterior Extension ◽  
Wide Geographic Distribution ◽  
Mature Spermatozoa

Brachidontes rodriguezii and Brachidontes purpuratus have a wide geographic distribution along the Argentinean coast. Both species are abundant in the intertidal area of rocky shores. We used transmission electron microscopy to study the spermatogenesis of B. rodriguezii and the structure of mature spermatozoa from B. rodriguezii and B. purpuratus. Our results show that spermatogenesis in B. rodriguezii is very similar to that reported in other mytilids. The spermatozoa of both Brachidontes are of the primitive or ect-aquasperm type showing a spherical nucleus capped by a conical acrosome with an anterior extension. The chromatin was electron-dense, homogeneous and compact. The mid-piece region consisted of 5 spherical mitochondria grouped in a ring around a pair of short cylindrical centrioles. The flagellum exhibit the typical 9 + 2 microtubule structure. Studies of spermatozoa ultrastructure are considered a useful tool in bivalve phylogeny. Characters in the spermatozoa morphology of these two species were observed and a brief discussion about the sperm morphology along the distribution of both species is presented. We suggest that the acrosome complex presents the most significant differences between both species.

Effect of glycosylation on the extracellular domain of the Ag43 bacterial autotransporter: enhanced stability and reduced cellular aggregation

2008 ◽  
Vol 412 (3) ◽  
pp. 563-577 ◽  
Author(s):  
Stine K. Knudsen ◽  
Allan Stensballe ◽  
Magnus Franzmann ◽  
Uffe B. Westergaard ◽  
Daniel E. Otzen
Keyword(s):  
Mammalian Cells ◽  
Bacterial Attachment ◽  
Passenger Domain ◽  
Glycosylation Sites ◽  
Structural And Functional Properties ◽  
Cellular Aggregation ◽  
Membrane Bound ◽  
Extracellular Environment ◽  
Resistant Structure ◽  
Different Levels

Autotransporters constitute the biggest group of secreted proteins in Gram-negative bacteria and contain a membrane-bound β-domain and a passenger domain secreted to the extracellular environment via an unusually long N-terminal sequence. Several passenger domains are known to be glycosylated by cytosolic glycosyl transferases, promoting bacterial attachment to mammalian cells. In the present study we describe the effect of glycosylation on the extracellular passenger domain of the Escherichia coli autotransporter Ag43α, which induces frizzy colony morphology and cell settling. We identify 16 glycosylation sites and suggest two possible glycosylation motifs for serine and threonine residues. Glycosylation stabilizes against thermal and chemical denaturation and increases refolding kinetics. Unexpectedly, glycosylation also reduces the stabilizing effect of Ca2+ ions, removes the ability of Ca2+ to promote cell adhesion, reduces the ability of Ag43α-containing cells to form bacterial amyloid and increases the susceptibility of the resulting amyloid to proteolysis. In addition, our results indicate that Ag43α folds without a stable intermediate, unlike pertactin, indicating that autotransporters may arrive at the native state by a variety of different mechanisms despite a common overall structure. A small but significant fraction of Ag43α can survive intact in the periplasm if expressed without the β-domain, suggesting that it is able to adopt a protease-resistant structure prior to translocation across the membrane. The present study demonstrates that glycosylation may play significant roles in structural and functional properties of bacterial autotransporters at many different levels.

scholarly journals Characterization of the binding domains on platelet glycoproteins Ib-IX and IIb/IIIa complexes for the quinine/quinidine-dependent antibodies

Blood ◽  
1991 ◽  
Vol 77 (10) ◽  
pp. 2190-2199 ◽  
Author(s):  
BH Chong ◽  
XP Du ◽  
MC Berndt ◽  
S Horn ◽  
CN Chesterman
Keyword(s):  
Antibody Binding ◽  
The Other ◽  
Target Antigen ◽  
Tail Region ◽  
Proteolytic Fragment ◽  
Specific Epitope ◽  
Binding Domains ◽  
Membrane Bound ◽  
Drug Dependent

Abstract Sera of 12 patients with quinine/quinidine-induced thrombocytopenia showed drug-dependent antibody binding to glycoprotein (GP) Ib-IX complex. The reaction with GPIb-IX complex of 11 of these 12 sera was strongly inhibited by the complex-specific monoclonal antibodies (MoAbs) AK1 and SZ1. The exception was a quinine-induced serum designated BU. The reaction of the six quinidine-induced sera was also partially blocked by an anti-GPIX MoAb, FMC25. Only 3 of the 12 patient sera showed drug-dependent antibody binding to GPIIb/IIIa, which was strongly inhibited by the anti-GPIIIa MoAb 22C4, and the anti-GPIIb alpha MoAb SZ22. With detergent-solubilized Serratia metalloprotease- treated platelets, quinine/quinidine-induced sera, except BU, immunoprecipitated a membrane-bound proteolytic fragment of GPIb-IX complex. In contrast, BU immunoprecipitated glycocalicin and a 40-Kd peptide tail fragment of GPIb alpha from the cell supernatant. Using purified GPIb-IX complex or its components as the target antigen, all the quinine-induced sera, except BU, immunoprecipitated GPIb-IX complex but failed to immunoprecipitate GPIb, GPIX, or the complex reformed from GPIb and GPIX. The quinidine-induced sera strongly immunoprecipitated purified GPIb-IX complex, weakly immunoprecipitated purified GPIX and the recombined complex, but did not immunoprecipitate purified GPIb. The combined data suggest that one quinine-dependent antibody (BU) recognizes an epitope in the peptide tail region of GPIb alpha and the other five quinine-dependent antibodies react with a complex-specific epitope on the membrane-associated region of GPIb-IX complex, whereas each of the six quinidine-induced sera contain two drug-dependent antibodies, one reactive with the GPIb-IX complex- specific epitope and the other reactive with GPIX. The binding domain(s) on GPIIb/IIIa for the quinine/quinidine-dependent antibodies appear to be sterically close to the epitopes for 22C4 and SZ22.

Sperm ultrastructure in the ocean quahog Arctica islandica (Arcticidae) and Neotrapezium sublaevigatum (Trapezidae), with a discussion of relationships within the Arcticoidea and with other Euheterodonta (Bivalvia)

2020 ◽  
Vol 86 (3) ◽  
pp. 173-185
Author(s):  
John M Healy ◽  
Paula M Mikkelsen ◽  
Rüdiger Bieler
Keyword(s):  
North Atlantic ◽  
Marine Bivalve ◽  
Sperm Ultrastructure ◽  
Arctica Islandica ◽  
Basal Ring ◽  
Acrosomal Vesicle ◽  
The North ◽  
Sperm Characters ◽  
Distal Centriole ◽  
Reticulate Structure

ABSTRACT Sperm ultrastructure is described for the ocean quahog Arctica islandica (Linnaeus, 1767) (Arcticidae), a long-lived, and commercially and phylogenetically important marine bivalve from the North Atlantic, and for Neotrapezium sublaevigatum (Lamarck, 1819), an Indo-Pacific member of the only other family of Arcticoidea (Trapezidae). Spermatozoa of A. islandica consist of (in anterior to posterior sequence): an elongate-conical, deeply invaginated, acrosomal vesicle (length 2.0 ± 0.2 μm; invagination occupied by a granular subacrosomal material); a straight, anteriorly-tapered, rod-shaped nucleus (length 6.6 ± 0.4 μm); a short (approximately 0.8 μm) midpiece consisting of two orthogonally arranged centrioles, surrounded by four (approximately 75% of spermatozoa observed) or, less commonly, five (approximately 25% of spermatozoa observed) spherical mitochondria; nine satellite fibres connecting the distal centriole to mitochondria and the plasma membrane; and a flagellum (length 60 ± 5.0 μm, with 9+2 axoneme), originating from the distal centriole. Contents of the acrosomal vesicle of A. islandica are differentiated into a very electron-dense basal ring (with reticulate structure) and two less electron-dense zones. Spermatozoa of N. laevigatum (Lamarck, 1819) differ substantially from those of A. islandica and are characterized by: a rounded-conical, deeply invaginated, acrosomal vesicle (length 0.43 ± 0.2 μm), with a curved basal ring and two less conspicuous components; a barrel-shaped nucleus (length 1.6 ± 0.5 μm) with a broad apical depression accommodating the base of the acrosomal vesicle; a midpiece composed of five (approximately 80% of spermatozoa observed) or four (approximately 20% of spermatozoa observed) mitochondria. Centriolar and flagellar details are essentially as for A. islandica, and putative glycogen deposits are associated with the distal centriole and mitochondria in both species. Sperm data corroborate recent transcriptomic analyses separating Arcticidae and Trapezidae in different imparidentian clades. Based on sperm morphology, A. islandica would appear more closely related to the Glauconomidae of the Cyrenoidea than to the Trapezidae, Veneroidea or any other previously examined group of euheterodonts, suggesting that it could be the only living member of the Arcticoidea. The relationships of the Trapezidae remain uncertain, with apparent sperm similarities to members of several groups of euheterodonts (e.g. Tellinoidea, Pholadoidea, Galeommatoidea), while several potentially closely related key taxa (e.g. Glossidae) remain unstudied for sperm characters.

scholarly journals Characterization of the binding domains on platelet glycoproteins Ib-IX and IIb/IIIa complexes for the quinine/quinidine-dependent antibodies

Blood ◽  
1991 ◽  
Vol 77 (10) ◽  
pp. 2190-2199 ◽  
Author(s):  
BH Chong ◽  
XP Du ◽  
MC Berndt ◽  
S Horn ◽  
CN Chesterman
Keyword(s):  
Antibody Binding ◽  
The Other ◽  
Target Antigen ◽  
Tail Region ◽  
Proteolytic Fragment ◽  
Specific Epitope ◽  
Binding Domains ◽  
Membrane Bound ◽  
Drug Dependent

Sera of 12 patients with quinine/quinidine-induced thrombocytopenia showed drug-dependent antibody binding to glycoprotein (GP) Ib-IX complex. The reaction with GPIb-IX complex of 11 of these 12 sera was strongly inhibited by the complex-specific monoclonal antibodies (MoAbs) AK1 and SZ1. The exception was a quinine-induced serum designated BU. The reaction of the six quinidine-induced sera was also partially blocked by an anti-GPIX MoAb, FMC25. Only 3 of the 12 patient sera showed drug-dependent antibody binding to GPIIb/IIIa, which was strongly inhibited by the anti-GPIIIa MoAb 22C4, and the anti-GPIIb alpha MoAb SZ22. With detergent-solubilized Serratia metalloprotease- treated platelets, quinine/quinidine-induced sera, except BU, immunoprecipitated a membrane-bound proteolytic fragment of GPIb-IX complex. In contrast, BU immunoprecipitated glycocalicin and a 40-Kd peptide tail fragment of GPIb alpha from the cell supernatant. Using purified GPIb-IX complex or its components as the target antigen, all the quinine-induced sera, except BU, immunoprecipitated GPIb-IX complex but failed to immunoprecipitate GPIb, GPIX, or the complex reformed from GPIb and GPIX. The quinidine-induced sera strongly immunoprecipitated purified GPIb-IX complex, weakly immunoprecipitated purified GPIX and the recombined complex, but did not immunoprecipitate purified GPIb. The combined data suggest that one quinine-dependent antibody (BU) recognizes an epitope in the peptide tail region of GPIb alpha and the other five quinine-dependent antibodies react with a complex-specific epitope on the membrane-associated region of GPIb-IX complex, whereas each of the six quinidine-induced sera contain two drug-dependent antibodies, one reactive with the GPIb-IX complex- specific epitope and the other reactive with GPIX. The binding domain(s) on GPIIb/IIIa for the quinine/quinidine-dependent antibodies appear to be sterically close to the epitopes for 22C4 and SZ22.

scholarly journals Heterotrimeric Kinesin II Is the Microtubule Motor Protein Responsible for Pigment Dispersion in Xenopus Melanophores

1998 ◽  
Vol 143 (6) ◽  
pp. 1547-1558 ◽  
Author(s):  
M. Carolina Tuma ◽  
Andrew Zill ◽  
Nathalie Le Bot ◽  
Isabelle Vernos ◽  
Vladimir Gelfand
Keyword(s):  
Fluorescent Protein ◽  
Dominant Negative ◽  
Pigment Dispersion ◽  
Tail Region ◽  
Microtubule Motors ◽  
Microtubule Motor ◽  
Alkaline Conditions ◽  
Membrane Bound ◽  
Conventional Kinesin ◽  
Green Fluorescent

Melanophores move pigment organelles (melanosomes) from the cell center to the periphery and vice-versa. These bidirectional movements require cytoplasmic microtubules and microfilaments and depend on the function of microtubule motors and a myosin. Earlier we found that melanosomes purified from Xenopus melanophores contain the plus end microtubule motor kinesin II, indicating that it may be involved in dispersion (Rogers, S.L., I.S. Tint, P.C. Fanapour, and V.I. Gelfand. 1997. Proc. Natl. Acad. Sci. USA. 94: 3720–3725). Here, we generated a dominant-negative construct encoding green fluorescent protein fused to the stalk-tail region of Xenopus kinesin-like protein 3 (Xklp3), the 95-kD motor subunit of Xenopus kinesin II, and introduced it into melanophores. Overexpression of the fusion protein inhibited pigment dispersion but had no effect on aggregation. To control for the specificity of this effect, we studied the kinesin-dependent movement of lysosomes. Neither dispersion of lysosomes in acidic conditions nor their clustering under alkaline conditions was affected by the mutant Xklp3. Furthermore, microinjection of melanophores with SUK4, a function-blocking kinesin antibody, inhibited dispersion of lysosomes but had no effect on melanosome transport. We conclude that melanosome dispersion is powered by kinesin II and not by conventional kinesin. This paper demonstrates that kinesin II moves membrane-bound organelles.

The significance of cAMP induced alterations in the cellular structure of Phycomyces

1977 ◽  
Vol 23 (4) ◽  
pp. 378-388 ◽  
Author(s):  
J. C. Tu ◽  
S. K. Malhotra
Keyword(s):  
Cell Wall ◽  
Plasma Membrane ◽  
Chitin Synthesis ◽  
Phycomyces Blakesleeanus ◽  
Thin Sections ◽  
Tube Emergence ◽  
Membrane Bound ◽  
Time Required ◽  
Small Clusters ◽  
Different Levels

Effect of cyclic AMP (cAMP) on Phycomyces blakesleeanus was studied by growing sporangiospores on glucose–asparagine agar or liquid medium containing three different levels of cAMP (10, 20 and 40 μM) in addition to the control (no cAMP added). The response of Phycomyces to the exogenous cAMP concentration in the medium is as follows: (1) the time required for germ tube emergence is reduced; (2) the diameter of the mycelium is increased (sometimes more than 10 times) and frequency of branching is also increased; (3) the cell wall of the mycelium is thickened (in some cases more than 5 times); (4) the glycogen in the cytoplasm is decreased as visualized in thin sections and also demonstrated in biochemical quantitation; and (5) the distribution of intercalated membranous particles (Imp) on plasma membrane is altered and this can be easily detected in freeze-fractured replica. Such a change in Imp is seen in the formation of small clusters of aggregated particles on the plasmic half (PF) and craters on the complementary exoplasmic half(EF)of the plasma membrane. Although the mechanism of cAMP action requires further exploration, it is possible that the addition of cAMP to the culture medium leads to degradation of glycogen and enhancement of chitin synthesis since the cell wall is largely composed of chitin. The alteration in Imp may be related to a change in the activity of chitin synthetase which is a plasma membrane-bound enzyme.

Ultrastructural study of the mature gametes of two species of Bankia (Mollusca : Teredinidae)

1974 ◽  
Vol 22 (1) ◽  
pp. 1 ◽  
Author(s):  
JD Popham ◽  
MR Dickson ◽  
CK Goddard
Keyword(s):  
Ultrastructural Study ◽  
Dense Granule ◽  
The Other ◽  
Sperm Ultrastructure ◽  
Electron Dense Granule ◽  
Acrosomal Vesicle

This work describes the ultrastructure of sperm from two species of shipworm. The most significant differences were found in the structure and arrangement of the acrosomes. The acrosomal vesicle contains two types of material, one appearing as fibrils, the other as an electron-dense granule. It is concluded that sperm ultrastructure can be used as a basis for teredinid identification. The results are discussed with particular reference to their bearing on bivalve classification.

Sign in / Sign up

Export Citation Format

Share Document