Arrangement of Mitochondria in Spermatozoa of the Mexican Axolotl, Ambystoma Mexicanum

1973 ◽  
Vol 31 ◽  
pp. 626-627
Author(s):  
Ezzatollah Keyhani ◽  
Larry F. Lemanski ◽  
Sharon L. Lemanski
Keyword(s):  
Plasma Membrane ◽  
Sperm Motility ◽  
Substrate Oxidation ◽  
Ambystoma Mexicanum ◽  
Axial Filament ◽  
Mexican Axolotl ◽  
Middle Piece

Energy for sperm motility is provided by both glycolytic and respiratory pathways. Mitochondria are involved in the latter pathway and conserve energy of substrate oxidation by coupling to phosphorylation. During spermatogenesis, the mitochondria undergo extensive transformation which in many species leads to the formation of a nebemkem. The nebemkem subsequently forms into a helix around the axial filament complex in the middle piece of spermatozoa.Immature spermatozoa of axolotls contain numerous small spherical mitochondria which are randomly distributed throughout the cytoplasm (Fig. 1). As maturation progresses, the mitochondria appear to migrate to the middle piece region where they become tightly packed to form a crystalline-like sheath. The cytoplasm in this region is no longer abundant (Fig. 2) and the plasma membrane is now closely apposed to the outside of the mitochondrial layer.

Mitochondrial morphology in the spermatozoa of the Mexican axolotl, Ambystoma mexicanum

1981 ◽  
Vol 50 (1) ◽  
pp. 449-461
Author(s):  
E. Keyhani ◽  
L.F. Lemanski
Keyword(s):  
Electron Microscopy ◽  
Plasma Membrane ◽  
Thin Section ◽  
Freeze Fracture ◽  
Ambystoma Mexicanum ◽  
Mitochondrial Morphology ◽  
Spherical Form ◽  
Mexican Axolotl ◽  
Tight Contact ◽  
Mature Spermatozoa

Thin-section and freeze-fracture electron microscopy of immature and mature spermatozoa of the Mexican axolotl, Ambystoma mexicanum, revealed numerous small spherical mitochondria with diameters ranging from 0.15 to 0.22 micrometers. Both the spherical form and the small size of these mitochondria were confirmed by serial thin-section studies. In mature spermatozoa, the mitochondria are located in the midpiece region, in tight contact with each other, exhibiting an almost crystalline arrangement. They do not surround the midpiece, but form a semicircular sheet over the sustained filament. The portion of the midpiece on the side of the undulating membrane and the flagellum is devoid of mitochondria. The plasma membrane in the midpiece region is tightly apposed to the mitochondria, so that in freeze-fracture or scanning electron microscopy the mitochondria seem to protrude through the plasma membrane. We suggest that the unusual organization of mitochondria in axoloti sperm facilitates the oxidative processes and increases the efficiency of ATP production and/or distribution within the cell.

The Ultrastructure of Myocardial Cells in Normal and Cardiac Lethal Mutant Mexican Axolotls, (Ambystoma Mexicanum)

1970 ◽  
Vol 28 ◽  
pp. 62-63
Author(s):  
Larry F. Lemanski ◽  
Eldridge M. Bertke ◽  
J. T. Justus
Keyword(s):  
Fine Structure ◽  
Heart Development ◽  
Osmium Tetroxide ◽  
Picric Acid ◽  
Ambystoma Mexicanum ◽  
Recessive Mutation ◽  
Acid Mixture ◽  
Myocardial Cells ◽  
Lethal Mutant ◽  
Mexican Axolotl

A recessive mutation has been recently described in the Mexican Axolotl, Ambystoma mexicanum; in which the heart forms structurally, but does not contract (Humphrey, 1968. Anat. Rec. 160:475). In this study, the fine structure of myocardial cells from normal (+/+; +/c) and cardiac lethal mutant (c/c) embryos at Harrison's stage 40 was compared. The hearts were fixed in a 0.1 M phosphate buffered formaldehyde-glutaraldehyde-picric acid-styphnic acid mixture and were post fixed in 0.1 M s-collidine buffered 1% osmium tetroxide. A detailed study of heart development in normal and mutant embryos from stages 25-46 will be described elsewhere.

Recent decline and potential distribution in the last remnant area of the microendemic Mexican axolotl (Ambystoma mexicanum)

2009 ◽  
Vol 142 (12) ◽  
pp. 2881-2885 ◽  
Author(s):  
Victoria Contreras ◽  
Enrique Martínez-Meyer ◽  
Elsa Valiente ◽  
Luis Zambrano
Keyword(s):  
Potential Distribution ◽  
Ambystoma Mexicanum ◽  
Mexican Axolotl

scholarly journals Melatonin Effect on Cryopreserved Sperm Cells of Crioulo Stallions

2020 ◽  
Vol 5 (2) ◽  
pp. 1-8
Author(s):  
Eraldo L Zanella
Keyword(s):  
Plasma Membrane ◽  
Sperm Motility ◽  
Membrane Integrity ◽  
Male Gamete ◽  
The Body ◽  
Cellular Damage ◽  
Ros Generation ◽  
Sperm Cells ◽  
Beneficial Effects ◽  
Endogenous Antioxidant

The freezing/thawing process of spermatozoa can cause cellular damage to the male gamete, decreasing the fertilization potential due to the increase in the production of reactive oxygen species (ROS). Melatonin is a potent endogenous antioxidant that protects the body against the damage caused by ROS. This study has evaluated different melatonin concentrations on the sperm viability of cryopreserved semen of Crioulo stallions. For that, three ejaculates were collected from five stallions diluted in a commercial extender followed by centrifugation and resuspension in a commercial freezing extender supplemented with 0; 1.25; 2.5. 5mM of Melatonin before the cryopreservation process. After thawing, the evaluation was performed assessing motility and flow cytometry evaluations: the plasma membrane integrity (PI), the integrity of the acrosomal membrane (FITC-PNA), mitochondrial membrane potential (JC1), and ROS generation (DCF-DA). Our results showed that sperm motility in the group without Melatonin and the 1.25mM group did not show the difference; however, the groups 2.5mM and 5mM presented a reduction in sperm motility. The 1.25 mM concentration was able to protect the plasma membrane during the cryopreservation process, in addition to showing a significant reduction in the production of ROS and increasing the percentage of sperm with integral acrosome. It can also be seen that high concentrations of Melatonin did not show beneficial effects. In conclusion, the addition of 1.25 mM of the Melatonin in Crioulo sperm cells showed to have a protective effect on the sperm cell during cryopreservation.

Ontogeny of immunoglobulin expression in the Mexican axolotl

Development ◽  
1989 ◽  
Vol 107 (2) ◽  
pp. 253-263
Author(s):  
J.S. Fellah ◽  
D. Vaulot ◽  
A. Tournefier ◽  
J. Charlemagne
Keyword(s):  
B Cell ◽  
Polyclonal Antibodies ◽  
Relative Proportion ◽  
Absolute Number ◽  
Ambystoma Mexicanum ◽  
Temporal Expression ◽  
Cell Compartment ◽  
Mexican Axolotl ◽  
Marked Enhancement ◽  
Ig Synthesis

The ontogeny of immunoglobulin (Ig) synthesis was followed at both cellular and serological levels in the Mexican axolotl (Ambystoma mexicanum) using polyclonal antibodies recognizing all Ig molecules and a set of monoclonal antibodies (Mabs) specific for the C mu and Cv heavy Ig chain isotypes and for the light chain constituents shared by IgM and IgY molecules. Clusters of IgM- and of IgY-synthesizing lymphocytes, often located in separate sites, are first present in spleen sections of 7-week-old 25 mm larvae, about one month after differentiation of the spleen anlage (stage 39–40). In 12-week-old 30–35 mm larvae, the relative proportion of IgM- and IgY-synthesizing cells in the spleen is the same as that in adult animals. However, a marked enhancement of the spleen B cell compartment occurs from 5 to 9 months when Ig-positive cells represent about 88% of the lymphocytes population compared to 60% in adults. No structures equivalent to B cell germinal centers were observed at any stage of the spleen differentiation and cells, although often clustered in small groups, remain dispersed in the entire organ. The relative proportions of IgM and IgY B cells throughout the spleen remain constant during development (about 1 IgY+ cell for 5–6 IgM+ cells) and IgM molecules are first detected in the serum of 2.5-month-old larvae. The enhancement of the serum IgM level correlates well with the absolute number of IgM+ cells in the growing spleen. IgY molecules cannot be detected in the serum before the 7th month but their level quickly increases to reach about 60% of the adult value at 10 months. Thyroxine-induced metamorphosis or hyperimmunization of 4- to 6-month-old larvae had no effect upon the temporal expression of the Ig classes in serum.

Variation in rDNA Redundancy Level and Nucleolar Organizer Length in Normal and Variant Lines of the Mexican Axolotl

1974 ◽  
Vol 15 (2) ◽  
pp. 239-257
Author(s):  
J. H. SINCLAIR ◽  
CAROLE R. CARROLL ◽  
R. R. HUMPHREY
Keyword(s):  
Genetic Material ◽  
Nucleolar Organizer ◽  
Ambystoma Mexicanum ◽  
The Other ◽  
Colour Pattern ◽  
Nucleolar Organizer Regions ◽  
Wild Type ◽  
Mexican Axolotl ◽  
Apparent Lack ◽  
Heterozygous Condition

The level of redundancy of ribosomal genes, and the relationship of this level to nucleolar formation at different stages of embryonic development, have been examined in the Mexican axolotl, Ambystoma mexicanum. Individuals from 4 inbred stocks were examined, as well as descendants from 2 nucleolar variants which, in the heterozygous condition, are distinguished by exceptionally small nucleoli. Ribosomal RNA-DNA hybridization assays show that one of the 4 wild type lines has only about one-third as much ribosomal DNA (rDNA) as the other three. One of the nucleolar variants has the same level of rDNA as the larger wild-type level; the other variant has the same amount as the smaller ribosomal genome line. Both original nucleolar variants arose as F1 progeny of crosses between a large rDNA genome line and the small genome line. Cytological examination of pregastrula stage embryos from wild type and nucleolar variant lines show that the lengths of the nucleolar organizer regions (NOR) and the sizes of nucleoli formed, are directly correlated with the amount of rDNA present at the nucleolar locus. During gastrulation of the nucleolar variants, however, a transition appears to take place and the amount of rDNA ceases to be the determining factor in nucleolar size. After late gastrula, heterozygous progeny resulting from crosses of either large rDNA genome or small rDNA genome wild type individuals with either nucleolar variant line, have a small and a large nucleolus. The factor or factors associated with this apparent lack of competitive ability of the variant NOR, when opposed to a normal NOR, are unknown. It might be suggested that since the chromosomal alterations which produced the nucleolar variants in both cases eliminated the gene determining the dark colour pattern, they could at the same time have eliminated other genetic material.

Transplantation of nuclei of various cell types from neurulae of the Mexican axolotl (Ambystoma mexicanum)

1964 ◽  
Vol 10 (2) ◽  
pp. 233-246 ◽  
Author(s):  
Robert Briggs ◽  
Jacques Signoret ◽  
R.R. Humphrey
Keyword(s):  
Cell Types ◽  
Ambystoma Mexicanum ◽  
Mexican Axolotl
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