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M Camatini

Publications and source records attributed to M Camatini.

At least 37 records · Page 2Linked to original sources
PubMed1988

Xenopus spermatozoon: is there any correlation between motility and oxygen consumption?

The motility status of Xenopus laevis spermatozoa does not affect their respiration rate. Oxygen consumption for 10(9) spermatozoa is approximately 0.4 mumol/minute. Oxygen consumption is not increased by gramicidin D, an uncoupler, and it is not blocked by KCN or NaN3. The adenosine triphosphate (ATP) content of spermatozoa that have been activated is definitely less than that in the spermatozoa that remained immotile. Incubation in KCN, NaN3, and gramicidin decreases the ATP content and impairs motility. The conclusions of the present study are that in Xenopus spermatozoa motility and oxygen consumption are not correlated, and the composition of the respiratory chain of these spermatozoa presents noteworthy peculiarities.

Adenosine Triphosphate↗
PubMed1988

Immunoelectron microscopic localization of actin in migrating cells during planarian wound healing.

Wound repair in planarians is mainly characterized by two cell-migratory events involving the epidermis adjacent to the wound and its basement membrane. The first event is the migration of epidermal cells to cover the wound surface; the second one is the migration of newly differentiating replacement epidermal cells from the parenchyma to the epidermis. In addition to these events, migration of fixed parenchymal cells is observed during wound healing. All migrating cells were characterized by the presence of actin, as shown by the results obtained by means of indirect immunolocalization with fluorescent and electron microscopy. Migrating cells were heavily labeled with gold particles, which clustered at the level of cell-matrix and cell-cell contacts.

Actins↗
PubMed1988

Immunocytochemical identification of actin in rabbit spermiogenesis and spermatozoa.

Actin was localized in testicular spermatids and in spermatozoa of rabbit by using a monoclonal anti-actin antibody and a specific antiserum against actin, labeled with colloidal gold. The antibody reactivity with sperm homogenates was determined by immunoblotting of one-dimensional gels. With on-grid postembedding immunostaining of Lowicryl K4M sections, actin was identified in the subacrosomal region of differentiating spermatids, and in four bulges situated between the inner acrosomal membrane and the nuclear envelope and in the anterior part of the postacrosomal region of ejaculated spermatozoa. Sperm actin was identified on two-dimensional gels as two spots in the isoelectric point and molecular weight corresponding to gamma and beta-isoforms of actin. Immunoblots stained with specific antibodies demonstrated that rabbit spermatozoa express gamma and beta-actin isoforms.

Actins↗
PubMed1987

Actin and calmodulin coexist in the equatorial segment of ejaculated boar sperm.

The direct overlay technique with iodinated calmodulin on boar sperm fractions evidenced a strong bond in the 45,000 molecular weight, which is the region recognized by anti-actin antibodies. This result and the close codistribution of the two staining patterns for calmodulin and actin with immunofluorescence and immunoelectronmicroscopy suggest a possible interaction between calmodulin and actin in boar sperm.

Actins↗
PubMed1986

Ca++ localization in boar spermatozoa by the pyroantimonate technique and X-ray microanalysis.

Intracellular, loosely bound Ca++ has been localized electron microscopically in freshly ejaculated boar spermatozoa by in situ precipitation with potassium antimonate. Ca++ was identified as the cation precipitated by testing the EGTA-sensitivity of the precipitates and by X-ray microprobe analysis. The data obtained revealed that the outer acrosomal membrane is the preferential site for Ca++ precipitation in the sperm head.

Animals↗
PubMed1986

Immunoelectronmicroscopic localization of actin in ionophore-treated boar sperm.

Actin in ionophore-A23187 treated boar sperm has been localized by indirect immunofluorescence and immunoelectronmicroscopy (IEM), using an anti-actin monoclonal antibody. By IEM, after en bloc staining technique and treatment with 15 nm colloidal gold-IgM complex, actin was found associated with the plasma membrane (PM) and the outer acrosomal membrane vesicles and under the PM of the equatorial segment.

Acrosome↗
PubMed1986

Immunocytochemical localization of calmodulin in intact and acrosome-reacted boar sperm.

Localization of calmodulin on intact and acrosome-reacted ionophore A23187 induced boar sperm has been performed with indirect immunofluorescence and immunoelectron microscopy. The results obtained with immunofluorescence are in agreement with previous reports. Immunoelectron microscopy was performed with the methods of preembedding immunostaining and on-grid post-embedding immunostaining of Lowicryl K4M sections with the protein A-colloidal gold. The presence of calmodulin is demonstrated in the acrosomal content and in the equatorial and postacrosomal regions of intact sperm. Apparently, calmodulin is released in association with the plasma membrane and the outer acrosomal membrane in acrosome-reacted sperm and it is maintained in the equatorial and postacrosomal regions. These results provide further evidence that also in mammalian sperm multiple classes of calmodulin-binding proteins may be present.

Acrosome↗
PubMed1986

Identification of actin in boar spermatids and spermatozoa by immunoelectron microscopy.

Actin was localized in testicular spermatids and in ionophore-treated ejaculated sperm of boar by use of a monoclonal anti-actin antibody labeled with colloidal gold. With the on-grid postembedding immunostaining of Lowicryl K4M sections, actin was identified in the subacrosomal region of differentiating spermatids, in the microfilaments of the surrounding Sertoli cells, and in the myoid cells of the tubular wall. Ejaculated sperm, labeled with the preembedding method, showed actin between the plasma membrane and the outer acrosomal membrane of the equatorial segment. Indirect immunofluorescence was positive in the equatorial segment and in the acrosomal cap of intact sperm, whereas reacted sperm at the anterior head region retained fluorescence only in the inner acrosomal membrane. Rhodamine-phalloidin failed to stain intact and reacted sperm. The distribution of actin in sperm head membranes (inner acrosomal membrane, membranes of the equatorial segment), which are retained after the acrosome reaction, is discussed.

Acrosome↗
PubMed1985

Evidence that a Ca2+ chelator and a calmodulin blocker interfere with the structure of inter-Sertoli junctions.

Ca2+ dependence of tight junction structure has been well documented in cultured epithelial tissues, and regulatory mechanisms have been identified. To analyse the possible control exerted on inter-Sertoli junctions, we exposed guinea-pig seminiferous tubules to the presence of a Ca2+ chelator (EGTA) and to a calmodulin blocker (Trifluoperazine, TFP) in vitro, for times ranging from 30 to 120 min. We observed the morphology of junctional complexes and the basal cytoplasmic regions in sections and replicas. Sertoli cell response to Ca2+ depletion involved several events: retraction of cells toward the base of the tubule and a consequent stretching of the points of fusion, augmented density of the cytoplasm, and destabilization of the array of intramembrane particles. Exposure of tubules to TFP resulted in disruption of the interactions between actin filaments and membrane junctional specialization, as well as a disorganization of other cytoskeletal elements. Thus, in vitro, junction integrity appears to be related to Ca2+ level, and Ca2+ depletion apparently interferes with Ca2+ distribution inside the cell and on microfilaments involved in junction regulation. Our results do not provide direct evidence for any particular mechanism of action of TFP, but a multiple effect is evident. TFP, which affects Ca2+ regulation and membrane fluidity, probably acts indirectly on junction-associated filaments. Both the experimental conditions tested suggest a Ca2+-mediated regulatory role of microfilaments of this complex junction.

Actins↗
PubMed1985

Morphological evidence for calcium stores at Sertoli-Sertoli and Sertoli-spermatid interrelations.

Potassium pyroantimonate technique has been employed to localize calcium ultrastructurally at Sertoli-Sertoli and Sertoli-spermatid junctional specializations. Identification of Ca++ as the major cation precipitated was performed by EGTA sensitivity and X-ray microprobe analysis. Ca++ deposits have been demonstrated in the endoplasmic reticulum cisternae underlying junctional complexes and along the plasma membranes of both Sertoli and germ cells.

Animals↗
PubMed1985

Structure and possible functional role of septate junctions in the ovotestis of a pond snail: inter-Sertoli junctions.

Junctions between Sertoli cells, which form a continuous layer at the periphery of the 'acinus' in the ovotestis of Biomphalaria glabrata (mollusc gastropod), have been studied with conventional sections, lanthanum impregnation, replicas and scanning analysis of unstained sections. Extensive undulating septate junctions link Sertoli cells, which surround the various stages of spermatid differentiation. The morphology of the pleated septate junctions here presented indicates a possible role as a permeability barrier, which might result from the peculiar organization of the septa. The junctional complex is formed of areas where septa are parallel and regularly spaced, alternating with areas where septa separate and assemble with others, thus creating a complex system of channels, completely compatible with the sealing properties expected for these junctions. The morphology of septa, their possible anchorage within the membranes, and the interconnections linking the closely parallel septa are presented.

Animals↗
PubMed1985

The effects of anticalmodulin drugs on the ultrastructure of boar spermatozoa.

Trifluoperazine, N-6-aminohexyl-5-chloro-1-naphthalene sulfonamide (W7), and calmidazolium are known to be calmodulin inhibitors and cell membrane soluble substances. In mammalian spermatozoa, calmodulin is present and is retained to mediate several sperm processes, such as sperm activation, sperm-egg fusion, microtubule disassembly, etc. We examined the effects of anticalmodulin drugs on the ultrastructure of freshly ejaculated boar spermatozoa. Whereas all the drugs, at the low concentrations tested, appear to prevent acrosomal alterations, at higher concentrations, they induced these alterations. Unexpectedly, the outer acrosomal membrane appeared to be more sensitive to the drugs than the plasma membrane; vesicles formed within the acrosome from the outer acrosomal membrane even when plasma membrane maintained its structural integrity. These findings were confirmed by the analysis carried out by fluorescent light microscopy by utilizing fluoresceinated Ricinus communis agglutinins to specifically stain the acrosomes.

Acrosome↗
PubMed1984

Responsiveness of testis morphology to chemotherapy in childhood leukemia.

The appearance of seminiferous tubules and interstitial cells of children, aged 2.5 to 13 years, affected by acute lymphoblastic leukemia was analyzed in sections. The testicular biopsies were performed at the end of therapy (vincristine, prednisone, L-asparaginase, 6-mercaptopurine, intrathecal methotrexate), which was affected for the same period and at the same doses. Three age groups were considered (I, 2.5 to 5 years; II, 6 to 9 years; III, 12 to 13 years). Age groups I and II presented damage of some tubules (25-35%) and areas of degeneration. Histometric analysis performed for A type spermatogonial population gave a mean value corresponding to controls in age group I and a mean value significantly lower with respect to controls in age group II. Moreover, age group II presented a lack of increase in tubular cross section. These results suggest that there is a vulnerability both of whole tubules and of some areas of Sertoli cells and germ cels to cytotoxic-induced damage. Leydig cells appear to be the cells least sensitive to drugs, and hormonal data indicate that the hypothalamic pituitary function appears to be intact, despite chemotherapy. Long-term prospective studies of reproductive function in children receiving cancer chemotherapy are needed to determine the magnitude and duration of damage resulting from therapeutic treatment.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1982

Chemotherapy does not affect the development of inter-Sertoli junctions in childhood leukaemia.

The inter-Sertoli junctions of children aged between 5 and 12 years, affected by acute lymphoblastic leukaemia, were analyzed in sections and freeze-fracture replicas. The testicular biopsies were performed at the end of therapy, when patients were in continuous remission for over 30 months. Chemotherapy does not seem to affect the development of junctions that were studied in sections and freeze fracture. Two age groups were considered (I, 5 to 8 years; II, 9 to 12 years). In age group I, oval Sertoli cells were connected by occasionally focal points of fusion, which in replicas appeared as scattered, interrupted ridges on the P face and grooves on the corresponding E face. In age group II Sertoli cells presented cytoplasmic extensions and interdigitations. Tight junctions appeared close to one another in conventional sections. Freeze fracture evidenced extensive although isolated areas formed by intervining strands. Lanthanum penetrated freely the intercellular spaces and gap junctions were observed in both age groups. The results suggest that tight junctions formation is initiated long before puberty; a progression in the complexity of the strand organization is present as the tubules mature; the strands reorganize in parallel and continuous rows only at puberty.

Animals↗
PubMed1981

Permeability to lanthanum of blood testis barrier in human germinal aplasia.

The permeability of Sertoli tight junctions to lanthanum administrated during fixation is demonstrated in biopsies of patients with partial germinal aplasia. In freeze-fracture replicas the number of fibrils is not significantly different from the data obtained in normal testis. Thus, in these pathological conditions junctional permeability is not related solely to the complexity of the network revealed by freeze-fracture.

Blood-Testis Barrier↗